RETAINER RING AND WAFER POLISHING SYSTEM INCLUDING THE RETAINER RING

Description

The present application claims priority under 35 U.S.C. § 119(a) to Korean patent application number 10-2025-0090815, filed on July 7, 2025, and Korean patent application number 10-2024-0136258, filed on October 8, 2024, in the Korean Intellectual Property Office, which applications are incorporated herein by reference in their entirety.

BACKGROUND

1. Technical Field

Embodiments generally relate to a semiconductor manufacturing apparatus, and more particularly, to a retainer ring and a wafer polishing system including the retainer ring.

2. Related Art

In general, Chemical Mechanical Polishing (CMP) may be used to planarize the side of a wafer having topographical features or to remove materials that may be difficult to etch using conventional methods.

The CMP process may be performed using a wafer polishing system, also referred to as a CMP apparatus, which may include a polishing pad and a polishing head.

A wafer to be polished may be placed on the polishing pad. The polishing head may apply pressure to the wafer positioned on the polishing pad. During the CMP process, slurry may be supplied between the polishing pad and the polishing head. The polishing pad and the polishing head may rotate relative to each other. Additionally, the polishing head may further include a retainer ring coupled to a bottom side of the polishing head to prevent or mitigate the wafer from dislodging during the CMP process.

However, when the polishing pad rotates during the CMP process, a centrifugal force may be generated, which may cause the slurry to move outward from a center of the polishing pad. The displaced slurry may generate a slurry bow wave at an outer edge of the retainer ring, thereby deteriorating the polishing efficiency.

SUMMARY

According to an embodiment, there may be provided a retainer ring. The retainer ring may include a coupling block and a mold block. The coupling block may be configured to be coupled to a polishing head. The mold block may be coupled to the coupling block and configured to support a wafer disposed on a polishing pad. The mold block may be in contact with the polishing pad. The mold block may include a body, a pad contact, a plurality of slurry passages, a plurality of slurry guides and an auxiliary slurry passage. The body may be configured to be coupled to the coupling block. The pad contact may be disposed on the body and may be in contact with the polishing pad. The plurality of slurry passages may be formed in the pad contact and may be configured to allow slurry to flow from an outer circumferential side of the body to an inner circumferential side of the body. The plurality of slurry guides may be respectively located outside the pad contact, on a rear side with respect to a rotation direction of the polishing head, and may be in communication with the respective slurry passages. The auxiliary slurry passage may be formed in the pad contact and be in communication with the plurality of slurry passages.

According to an embodiment, there may be provided a retainer ring. The retainer ring may include a coupling block and a mold block. The coupling block may be coupled to a polishing head. The mold block may be coupled to the coupling block and may be configured to support a wafer positioned on a polishing pad. The mold block may contact the polishing pad. The mold block may include a body and a pad contact. The body may be coupled to the coupling block. The pad contact may be disposed on the body and may be configured to contact the polishing pad. The pad contact may include a connection passage, a plurality of inlet passages, a plurality of outlet passages and a plurality of guide passages. The connection passage may be formed in the pad contact along a circumferential direction of the body and may be configured to divide the pad contact into an inner pad contact and an outer pad contact. The plurality of inlet passages may extend from the connection passage to an outer peripheral side of the pad contact, and may be configured to introduce slurry into the connection passage. The plurality of outlet passages may extend from the connection passage to an inner peripheral side of the pad contact and may be configured to discharge the slurry from the connection passage. The plurality of guide passages may be respectively positioned at outer sides of the pad contact located at a rear side of a rotation direction of the polishing head. Each of the plurality of guide passages may be interconnected to a corresponding one of the plurality of outlet passages.

According to an embodiment, there may be provided a wafer polishing system. The wafer polishing system may include a polishing pad, a polishing head, a slurry supplier and a retainer ring. The polishing head may be positioned over the polishing pad and may press the wafer against the polishing pad by bringing the wafer into contact with the polishing pad. The slurry supplier may supply slurry to the polishing pad. The retainer ring may be mounted on the polishing head and may support the wafer. The retainer ring may include a coupling block and a mold block. The coupling block may be coupled to the polishing head. The mold block may be coupled to the coupling block and may be configured to support the wafer positioned on the polishing pad. The mold block may contact the polishing pad. The mold block may include a body, a pad contact, a plurality of slurry passages, a plurality of slurry guides and an auxiliary slurry passage. The body may be coupled to the coupling block. The pad contact may be disposed on the body and may contact the polishing pad. The plurality of slurry passages may be formed in the pad contact and may transfer the slurry from an outer peripheral side of the body to an inner peripheral side of the body. The plurality of slurry guides may be respectively positioned at outer sides of the pad contact located at a rear side of a rotation direction of the polishing head. Each of the slurry guides may be in fluid communication with a corresponding one of the slurry passages. The auxiliary slurry passage may be formed in the pad contact and may be in fluid communication with the plurality of slurry passages.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and another aspects, features and advantages of the subject matter of the present disclosure will be more easily understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view illustrating a wafer polishing system in accordance with an embodiment;

FIG. 2A is a perspective view illustrating a retainer ring in accordance with an embodiment;

FIG. 2B is an enlarged perspective view illustrating a portion “A” of FIG. 2A;

FIGS. 2A, 2B, 2C, 2D, 2E, and 2F are perspective views illustrating outer shapes of the retainer ring in accordance with an embodiment;

FIG. 3A is a view illustrating an operation of a comparative example of a retainer ring;

FIG. 3B is a schematic view illustrating an operation of a retainer ring in accordance with an embodiment;

FIGS. 4A, 4B, 4C, and 4D are views illustrating retainer rings in accordance with an embodiment;

FIG. 5 is a plan view illustrating an operation of a retainer ring in accordance with an embodiment;

FIG. 6A is a perspective view illustrating a mold block with an inclined side in accordance with an embodiment;

FIG. 6B is an enlarged perspective view illustrating a portion “A” in FIG. 6A;

FIG. 6C is a cross-segmental view taken along a line b-b’ of FIG. 6B;

FIG. 7A is a perspective view illustrating a mold block with a modified inclined side in accordance with an embodiment;

FIG. 7B is an enlarged perspective view illustrating the mold block shown in FIG. 7A;

FIG. 7C is a cross-segmental view taken along a line b-b’ of FIG. 7B;

FIGS. 8A and 8B are views illustrating first lateral sides of pad contacts in accordance with an embodiment;

FIGS. 9A, 9B, and 9C are perspective views illustrating a retainer ring in accordance with an embodiment; and

FIGS. 10A, 10B, and 10C are perspective views illustrating a retainer ring in accordance with an embodiment.

DETAILED DESCRIPTION

For clarity, the dimensions and relative proportions of layers and areas illustrated in the drawings may be exaggerated. Throughout the specification, like reference numerals refer to like elements. The words “connected” or “coupled,” as used herein for some embodiments, means that two components are directly connected with one another.  For example, a first component coupled to a second component means the first component is contacting the second component.  For other embodiments, coupled components have one or more intervening components.  For example, a first component is coupled to a second component when the first and second components are both in contact with a common third component even though the first component is not directly contacting the second component. For example, a coupling block coupled to a polishing head means for some embodiments, that the two components are directly connected with one another and for other embodiments means there are one or more intervening components between the coupling block and the polishing head.

Various embodiments provide a retainer ring capable of improving polishing efficiency, and a wafer polishing system including the same.

In an embodiment, each of the plurality of slurry passages may include a passage extending from an outer peripheral side of each of the pad contacts to an inner peripheral side of the respective pad contact to divide the pad contact into a plurality of segments.

In an embodiment, the auxiliary slurry passage may include a plurality of passages formed along a circumferential direction of each of the pad contacts to divide each of the pad contacts into an outer pad contact and an inner pad contact.

In an embodiment, the mold block may further include an auxiliary slurry guide formed on an outer side of the inner pad contact.

In an embodiment, each of the plurality of slurry passages may include a plurality of inlet passages extending from the outer peripheral side of the pad contact to allow a slurry inflow, and a plurality of outlet passages configured to discharge the slurry introduced through the inlet passages. The auxiliary slurry passage may include a connection passage formed in the pad contact and configured to connect the plurality of inlet passages and the plurality of outlet passages.

In an embodiment, the connection passage may be formed along a circumferential direction of the pad contact to divide the pad contact into an outer pad contact and an inner pad contact.

In an embodiment, the plurality of inlet passages may be formed in the outer pad contact along a radial direction of the pad contact to divide the outer pad contact into a plurality of segments.

In an embodiment, the plurality of outlet passages may be formed in the inner pad contact along a radial direction of the pad contact to divide the inner pad contact into a plurality of segments.

In an embodiment, the retainer ring may further include an auxiliary slurry guide formed on an outer side of each of the inner pad contacts.

In an embodiment, the auxiliary slurry guide may have the same shape as that of the slurry guide.

In an embodiment, the plurality of inlet passages and the plurality of outlet passages may be arranged in a staggered manner.

In an embodiment, the plurality of inlet passages and the plurality of outlet passages may be arranged in parallel to each other.

In an embodiment, the plurality of inlet passages and the plurality of outlet passages may be oriented orthogonally to the connection passage.

In an embodiment, the plurality of inlet passages may be formed in the outer pad contact along a radial direction of the pad contact and may be configured to divide the outer pad contact into a plurality of segments. The plurality of outlet passages may be formed in the inner pad contact along a radial direction of the pad contact and may be configured to divide the inner pad contact into a plurality of segments.

In an embodiment, the pad contact may further include an auxiliary guide passage formed on an outer side of each of the inner pad contacts.

In an embodiment, the plurality of inlet passages and the plurality of outlet passages may be arranged in a staggered and parallel configuration.

In an embodiment, the plurality of inlet passages and the plurality of outlet passages may be oriented orthogonally to the connection passage.

In an embodiment, each of the plurality of slurry passages may extend from an outer peripheral side of each of the pad contacts to an inner peripheral side thereof to divide each pad contact into a plurality of segments. The auxiliary slurry passage may include a plurality of passages formed along a circumferential direction of each of the pad contacts to divide each of the pad contacts into an outer pad contact and an inner pad contact.

According to an embodiment, the retainer ring with improved slurry delivery performance, and the wafer polishing system including the same, may prevent or mitigate the slurry from flowing outward toward the outer region of the polishing pad when the slurry impinges upon the mold block of the retainer ring without entering into the polishing head. In an embodiment, the guide may guide the slurry into grooves, thereby improving an amount of slurry supplied toward the wafer. As a result, in an embodiment, the polishing efficiency of the polishing system may be enhanced.

Because, in an embodiment, the auxiliary slurry passage may be formed in the pad contact, the amount of slurry supplied toward the wafer may be further increased, thereby further improving the polishing efficiency of the polishing system.

Referring to FIG. 1, a wafer polishing system of an embodiment may include a platen 5, a polishing pad 1, a polishing head 2, a slurry supplier 3 and a retainer ring 1000.

The platen 5 may rotate in a first direction R1. The polishing pad 1 may be disposed on an upper side of the platen 5 and may rotate together with the platen 5 in the first direction R1. The slurry supplier 3 may supply slurry onto the polishing pad 1. For example, the first direction R1 may be referred to a rotational direction.

The polishing head 2 may be disposed over the platen 5 and may rotate in the same direction R1 as the polishing pad 1. The polishing head 2 may hold a wafer 4 and press the wafer against the polishing pad 1.

The retainer ring 1000 may be disposed over a bottom side of the polishing head 2. The retainer ring 1000 may have a ring shape supporting an outer peripheral side of the wafer 4. The retainer ring 1000, for example, a bottom side of the retainer ring 1000 (e.g., a side contacting the polishing pad 1), may include a plurality of grooves. The slurry may be supplied through the grooves to a space between the wafer 4 and the upper side of the polishing pad 1.

As described above, the slurry may be introduced into the retainer ring 1000 through the grooves of the retainer ring 1000 to polish the side of the wafer 4. The polishing efficiency of the wafer 4 may be proportional to an amount of the slurry supplied into the retainer ring 1000.

For convenience of explanation, FIG. 2A shows the retainer ring 1000 of FIG. 1 in a flipped (180° rotated) orientation. In the following description, an upper side of the retainer ring 1000 refers to a side that contacts the wafer, and a bottom side refers to a side that contacts the polishing head.

Hereinafter, the retainer ring, in an embodiment, configured to improve the amount of supplied slurry will be described in more detail with reference to the drawings.

Referring to FIGS. 1, 2A and 2B, the retainer ring 1000 of an embodiment may include a mold block 100 and a coupling block 400.

The mold block 100 may be coupled to an upper side of the coupling block 400. At least one coupling groove 400h may be formed on the upper side of the coupling block 400. The mold block 100 may be mechanically coupled to the coupling block 400 by means of the coupling groove 400h and a fastening member (not shown).

The coupling block 400 may be in direct contact with the polishing head 2. For example, the bottom side of the coupling block 400 shown in FIG. 2A may be coupled to the bottom side of the polishing head 2 shown in FIG. 1. The coupling block 400 may have a ring shape corresponding to a curvature of an outer circumference of the wafer 4, but is not limited thereto.

The mold block 100 may include a body 110, a plurality of slurry passages 120, a plurality of pad contacts 130, a plurality of slurry guides 140 and a plurality of auxiliary slurry passages 150.

The body 110 may have a substantially ring shape. The body 110 may include a bottom side and an upper side. The bottom side of the body 110 may be coupled to the upper side of the coupling block 400. Accordingly, the ring shape of the body 110 may correspond to the ring shape of the coupling block 400.

The pad contacts 130 may be disposed on the upper side of the body 110. The pad contacts 130 may be arranged along the circumferential direction of the body 110. The pad contacts 130 may be spaced at set intervals, although the embodiments are not limited thereto. The word “predetermined” as used herein with respect to a parameter, such as a predetermined interval(s), means that a value for the parameter is determined prior to the parameter being used in a process or algorithm.  For some embodiments, the value for the parameter is determined before the process or algorithm begins.  In other embodiments, the value for the parameter is determined during the process or algorithm but before the parameter is used in the process or algorithm.

The spaces between adjacent pad contacts 130 may serve as the slurry passages 120, which may correspond to the grooves. Each slurry passage 120 may extend from the outer circumferential side 110a of the body 110 toward the inner circumferential side 110b, allowing slurry to flow to the polishing pad 1 through the slurry passage 120. The slurry passage 120 may be inclined along the rotational direction R1 of the polishing head 2. For example, the extension direction of the slurry passage 120 may be substantially perpendicular to the rotational direction R1.

Each auxiliary slurry passage 150 may be formed on each of the pad contacts 130. In an embodiment, the auxiliary slurry passage 150 may be a groove formed along the circumferential direction of the body 110, that is, along the circumferential direction of the pad contact 130. Thus, the auxiliary slurry passage 150 may function as a channel connecting adjacent slurry passages 120. Accordingly, in an embodiment, the slurry introduced through one slurry passage 120 may also flow through the auxiliary slurry passage 150, thereby improving the amount of slurry supplied toward the wafer 4.

Although in an embodiment, the auxiliary slurry passage 150 may be illustrated as being formed along the circumferential direction of the body 110, it is not limited thereto. For example, the auxiliary slurry passage 150 may also be formed in a direction intersecting the circumferential direction of the body 110.

Each pad contact 130 may be integrally formed with the body 110 or separately formed and disposed on the upper side of the body 110. For convenience of explanation, the pad contact 130 and the body 110 may be described as separate elements, but if made of the same material, they may be understood as a single integrated structure.

Each pad contact 130 may include a first lateral side 131, a second lateral side 132, a pad attaching side CS, an outer side 133 and an inner side 134. For example, the first lateral side 131 may correspond to a rear side of the pad contact 130 with respect to the rotational direction R1 of the polishing head 2. The second lateral side 132 may correspond to the front side. That is, the polishing head 2 may rotate from the first lateral side 131 toward the second lateral side 132. The outer side 133 may connect the outer edges of the first and second lateral sides 131 and 132. The inner side 134 may connect the inner edges of the first and second lateral sides 131 and 132.

In an embodiment, the auxiliary slurry passage 150 may extend across the first and second lateral sides 131 and 132 of the pad contact 130. That is, the slurry passages 120 adjacent to the first and second lateral sides 131 and 132 may be intersected to the auxiliary slurry passage 150.

Accordingly, as the auxiliary slurry passage 150 may pass through the pad contact 130, the pad contact 130 may be divided into an outer pad contact 135 and an inner pad contact 136.

The pad attaching side CS may be a side in direct contact with the polishing pad 1 and may correspond to a plane connecting the upper edges of the first and second lateral sides 131 and 132.

The longitudinal axes of the outer and inner sides 133 and 134 may be parallel to the rotational direction R1 of the polishing head 2. For example, the outer side 133 may be located closer to the outer circumference of the body 110, and the inner side 134 may be located closer to the inner circumference 110b or adjacent to the outer circumference of the wafer 4.

Each slurry guide 140 may be located at the outer circumferential side 110a of the body 110. For example, the slurry guide 140 may define a space having an expanding width Wg in a direction -R1 (hereinafter, reverse rotational direction) opposite to the rotation direction R1 of the polishing head 2. For example, a region having a maximum width Wg_max in the slurry guide 140 may be intersected to the slurry passage 120, thereby forming an expanded slurry passage SP. In an embodiment, the slurry guide 140 may have a triangular prism shape.

Accordingly, the expanded slurry passage SP including the slurry passage 120 and the slurry guide 140 may have an expanding width SPW in the reverse rotational direction -R1. In a radial direction R2 from the outer circumferential side 110a to the inner circumferential side 110b of the body 110 (i.e., slurry inflow direction), the width SPW of the slurry passage SP may decrease.

In an embodiment, by being adjacent to the first lateral side 131 of the pad contact 130, the slurry guide 140 may facilitate an inflow of the slurry from the outer circumferential side 110a of the body 110 to the inner circumferential side 110b where the wafer 4 may be located, especially during the rotation of the polishing head 2.

In an embodiment, the first lateral side 131 may be designed to have a smaller cross-sectional area than the second lateral side 132, thereby increasing the exposed area of the body 110 toward the reverse rotational direction (–R1), and consequently increasing the volume of the slurry guide 140.

In an embodiment, a length d1 of an upper edge of the first lateral side 131 may be substantially equal to a length of a bottom edge of the first lateral side 131. A length d2 of an upper edge of the second lateral side 132 may be substantially equal to a length of a bottom edge of the second lateral side 132. In an embodiment, the length d1 of the upper (or bottom) edge of the first lateral side 131 may correspond to about 0.1% to about 85% of a width d0 of the body 110, defined as a distance from an outer circumferential side 110a to an inner circumferential side 110b of the body 110. In an embodiment, the length d2 of the upper edge of the second lateral side 132 may be about 95% to about 100% of the width d0 of the body 110.

As such, because the cross-sectional area of the first lateral side 131 may be designed to be smaller than that of the second lateral side 132, the exposed area of the body 110 may increase toward the first lateral side 131 from the second lateral side 132 (e.g., the reverse rotational direction: –R1) with respect to one pad contact 130. Accordingly, a volume of the slurry guide 140 may increase. Here, the slurry guide 140 may be understood as a space between the outer side 133 of the pad contact 130 and an upper region of the body 110.

For reference, the first lateral side 131, the second lateral side 132, the outer side 133 and the inner side 134 may each be planar and substantially perpendicular to the upper side of the body 110 and a pad attachment side CS.

As described above, the slurry guide 140 may be intersected to the slurry passage 120, and the expanded slurry passage SP having a wider gap than the slurry passage 120 may be provided in the retainer ring 1000. Accordingly, in an embodiment, upon the rotation of the polishing head 2, a greater amount of slurry located at the outer periphery of the retainer ring 1000 (or of the outer circumferential side 110a of the body) may be guided toward the inner circumferential side 110b of the body 110.

In particular, because, in an embodiment, the slurry guide 140 may be provided adjacent to the first lateral side 131, the slurry passage SP may have a laterally asymmetric structure favorable for slurry inflow with respect to the slurry passage 120.

In an embodiment, due to the presence of the slurry guide 140, a bent portion B may be formed on the outer side 133 of the pad contact 130, as illustrated in FIG. 2C. For example, the bent portion B of the outer side 133 may result from a difference in cross-sectional area between the first lateral side 131 and the second lateral side 132.

Referring to the bent portion B, a first region 133-1 of the outer side 133 adjacent to the first lateral side 131 may be in contact with the slurry guide 140. In other words, the first region 133-1 of the outer side 133 may define the slurry guide 140. A second region 133-2 of the outer side 133, adjacent to the second lateral side 132 with reference to the bent portion B, may be positioned on substantially the same plane as the outer circumferential side 110a of the body 110, thereby forming the outer side of the retainer ring 1000. The term “inside” shown in the drawing refers to a direction toward the inner circumferential side 110b or toward the wafer, whereas “outside” refers to an outer direction of the retainer ring 1000. However, the present disclosure is not limited thereto. If the second region 133-2 may be located further inward than the outer circumferential side 110a of the body 110, the second region 133-2 may also be understood as being in contact with the slurry guide 140.

As shown in FIG. 2D, a bent portion B1 may be rounded toward the outside direction, such that the outer side 133 may have a convex curvature. Meanwhile, as illustrated in FIG. 2E, a bent portion B2 may be rounded toward the inside direction, such that the outer side 133 may have a concave curvature.

Referring to FIG. 2F, an auxiliary slurry guide 142 may be further formed in the auxiliary slurry passage 150. Particularly, the auxiliary slurry guide 142 may be formed on the outer side of the inner pad contact 136. The auxiliary slurry guide 142 may have functions substantially the same as the functions of the slurry guide 140, i.e., the guiding the slurry into the slurry passage 140.

In an embodiment, the auxiliary slurry guide 142 may have a shape substantially the same as the shape of the slurry guide 140. Thus, any further illustrations with respect to the shape of the auxiliary slurry guide 142 may be omitted herein for brevity. Alternatively, the shape of the auxiliary slurry guide 142 may be different from the shape of the slurry guide 140.

Referring to FIGS. 3A and 3B, a comparative example and an embodiment are illustrated to describe the operation of the retainer ring.

As shown in FIG. 3A, in the case of a comparative example of a retainer ring having slurry passages 12 with a uniform width between pad contacts 13, slurry remaining on the outer side of the mold block 10 may flow into the inner side of the body 11 only through the slurry passages 12. Particularly, because the slurry passages 12 may be formed in a substantially linear shape, the slurry may collide with and bounce off the outer side 16 of the pad contacts 13 (denoted by A1). The slurry that remains due to such collision may cause a slurry bow wave phenomenon, thereby reducing polishing efficiency.

Apart from this, as shown in FIG. 3B, when the slurry guides 140 is provided adjacent to the first lateral side 131 and the outer side 133 of the pad contacts 130, the expanded slurry passage SP may be formed. As a result, in an embodiment, the slurry remaining on the outer side of the mold block 100 may be more effectively introduced into the slurry passage 120 through the slurry guide 140 (denoted by A2).

Referring now to FIGS. 4A to 4D, various embodiments of the retainer ring are illustrated.

In FIG. 4A, a retainer ring 1000a may include a mold block 100a and a coupling block 400. The mold block 100a may include a body 110, a plurality of slurry passages 120, a plurality of pad contacts 130a, a plurality of slurry guides 140a and a plurality of auxiliary slurry passages 150.

Because the auxiliary slurry passages 150 of an embodiment may have substantially the same shape and function as described earlier, a repeated explanation is omitted. Although not shown in the figure, an auxiliary slurry guide as shown in FIG. 2F may also be provided in an embodiment.

Each slurry passage 120 may be disposed between a pair of adjacent pad contacts 130a. Each pad contact 130a may include a first lateral side 131a, a second lateral side 132a, an outer side 133a and an inner side 134a.

The length d1a of the upper side of the first lateral side 131a may be substantially equal to that of the bottom side of the first lateral side 131a, and likewise for d2a of the second lateral side 132a. In an embodiment, d1a may correspond to about 50% to 60% of the body width d0, and d2a may correspond to about 95% to 100% of the width d0.

Due to the difference in length between d1a and d2a, the slurry guide 140a may be formed between the outer side 133a of the pad contact 130a and the outer circumferential side 110a of the body 110.

Accordingly, the width wg1 of the slurry guide 140a may gradually increase from the second lateral side 132a toward the first lateral side 131a. Because the slurry guide 140a may be in communication with the slurry passage 120, the inlet of the slurry transfer passage SP in the retainer ring 1000a may be expanded. Optionally, the upper edge of the outer side 133a may be curved.

As shown in FIG. 4B, another embodiment of the retainer ring 1000b includes a mold block 100b and a coupling block 400. The mold block 100b includes a body 110, slurry passages 120, pad contacts 130b, slurry guides 140b and auxiliary slurry passages 150.

The pad contacts 130b each include a first lateral side 131b, a second lateral side 132b, an outer side 133b, an inner side 134b and a pad attaching side CS. The length d1b of the upper and bottom sides of the first lateral side 131b may be shorter than the length d2b of the second lateral side 132b. For example, d1b may be about 0.1 to 15% of the body width d0, and d2b may be about 95 to 100% of the body width d0. Accordingly, the width wg2 of the slurry guide 140b may be greater than that of the slurry guide 140a in FIG. 4A.

In an embodiment, the upper and bottom edges of the outer side 133b may be curved to prevent or mitigate polishing defects or physical damage to the retainer ring 1000a or 1000b during operation.

In FIG. 4C, a retainer ring 1000c may be shown with a configuration similar to that of FIG. 4B, except that the outer side 133c of the pad contact 130c and the slurry guide 140c differ. In an embodiment, the outer side 133c may be formed as a flat side perpendicular to the pad attaching side CS, with the upper and bottom edges of the outer side 133c extending in a straight line parallel to the tangent of the outer circumferential side 110a. Thus, the slurry guide 140c in contact with the outer side 133c may have a rectangular flat shape.

Referring to FIG. 4D, variations in the length da to dd (where d0 > da > db > dc > dd) of the first lateral side 131 of the pad contact 130 may be used to vary the shape of the slurry guide 140 accordingly.

Referring to FIG. 5, a schematic plan view is shown to illustrate the operation of the retainer ring 1000 of an embodiment.

The retainer ring 1000 may include the slurry guide 140 disposed adjacent to the outer side 133 of the pad contact 130. The slurry guide 140 may be formed to have a width that gradually increases toward the reverse rotational direction (−R1), which is opposite to the rotational direction R1 of the polishing head 2 (see FIG. 1). As a result, in an embodiment, the volume of the slurry guide 140 may increase in that direction, which improves the amount of slurry inflow and consequently may enhance the polishing efficiency. Because, in an embodiment, the slurry guide 140 may be located along the outer circumference of the retainer ring 1000, it may help prevent or mitigate slurry from stagnating during the polishing process and may reduce the occurrence of a slurry bow wave phenomenon.

FIGS. 6A to 6C illustrate a mold block having an inclined side in accordance with an embodiment.

Referring to FIGS. 6A to 6C, a mold block 200 may include a body 210, a plurality of slurry passages 220, a plurality of pad contacts 230 and a plurality of slurry guides 240.

Because the auxiliary slurry passages 250 are substantially the same as those previously described (e.g., 150), repeated descriptions are omitted. Although not shown in the drawings, an auxiliary slurry guide such as the one shown in FIG. 2F may also be provided in an embodiment.

Each pad contact 230 may include a first lateral side 231, a second lateral side 232, an outer side 233, an inner side 234, a pad attachment side CS and an inclined side 235. The inclined side 235 may be disposed between the pad attachment side CS and the outer side 233 of the pad contact 230. The inclined side 235 may have a chamfer shape and be sloped relative to both the pad attachment side CS and the outer side 233. The slope (θ) and shape of the inclined side 235 may be variable depending on the required amount of slurry during the polishing process. The pad attachment side CS may remain flat and maintain a uniform thickness.

In an embodiment, the inclined side 235 may have a rectangular planar structure, such that the upper edge length d1U of the first lateral side 231 may be shorter than the bottom edge length d1L. The upper edge length d2U of the second lateral side 232 may be greater than d1U but smaller than its own bottom edge length d2L. The bottom edge length d2L may be equal to or slightly less than the body width d0. For instance, the upper edge length d1U of the first lateral side 231 may range from about 0.1% to about 85% of the body width d0. The outer side 233 may maintain a uniform height.

As such, the chamfered inclined side 235 may extend the slurry guide space 240 up to the side of the inclined portion. Consequently, in an embodiment, a greater amount of slurry may flow into the retainer ring via the slurry guide 240 and the slurry passage 220.

FIGS. 7A to 7C show a mold block with a modified inclined side in accordance with an embodiment.

Referring to FIGS. 7A to 7C, a mold block 200a may include a body 210, a plurality of slurry passages 220, a plurality of pad contacts 230a and a plurality of slurry guides 240a.

Because the auxiliary slurry passages 250 are substantially the same as those previously described (e.g., 150), repeated descriptions are omitted. Although not shown in the drawings, an auxiliary slurry guide such as the one shown in FIG. 2F may also be provided in an embodiment.

Each pad contact 230a may include a first lateral side 231a, a second lateral side 232a, an outer side 233a, an inner side 234a, a pad attachment side CS1 and a modified inclined side 235a. The inclined side 235a may be formed in a chamfered shape at the interface between the pad attachment side CS1 and the outer side 233a. The slope of the inclined side 235a may vary by position. For example, the inclination angle θ1 of the inclined side 235a adjacent to the first lateral side 231a may be shallower than the inclination angle θ2 of the inclined side adjacent to the second lateral side 232a.

As a result, in an embodiment, an upper edge length d11U of the first lateral side 231a may be shorter than a bottom edge length d11L. In an embodiment, an upper edge length d21U of the second lateral side 232a may be greater than d11L. In an embodiment, a bottom edge length d21L of the second lateral side 232a may be greater than d21U and equal to or less than the body width d0.

Thus, the pad attachment side CS1 may maintain a constant height, while the thickness of the outer side 233a gradually decreases toward the first lateral side 231a due to the inclined side 235a. This increases the area and volume of the slurry guide 240a adjacent to the first lateral side 231a, allowing a larger amount of slurry to flow into the interior of the mold block 200a through the slurry passage 220.

FIGS. 8A and 8B illustrate additional variations of the inclined side of a pad contact.

In FIG. 8A, an inclined side 235b of a pad contact 230b may be disposed in a convex shape protruding outward. Alternatively, as shown in FIG. 8B, an inclined side 235b′ may be formed in a concave shape recessed inward.

In one example, at least one of the following corners may be rounded, for example, a corner E1 where the outer side 233b and the inclined side 235b (or 235b′) meet, a corner E2 where the inclined side 235b (or 235b′) and the pad attachment side CS meet, a corner E3 where the pad attachment side CS and the inner side 234b meet.

The planar configuration of the inclined side 235b or 235b′ may correspond to that shown in either FIG. 6B or FIG. 7B.

FIGS. 9A to 9C are perspective views illustrating a retainer ring in accordance with an embodiment.

Referring to FIGS. 9A to 9C, a mold block 300 of a retainer ring in an embodiment may include a body 310 and a pad contact 330.

Because the body 310 is substantially the same as the previously described body 110, detailed description thereof is omitted.

The pad contact 330 may include a connection passage 350, a plurality of inflow passages 322, a plurality of outflow passages 320 and a plurality of guide passages 340.

The connection passage 350 may be formed in the pad contact 330 and extend along the circumferential direction of the body. Accordingly, the pad contact 330 may be divided into an outer pad contact 332 and an inner pad contact 334 by the connection passage 350.

The plurality of inflow passages 322 may be formed in the outer pad contact 332 and configured to introduce slurry into the connection passage 350.

Particularly, each inflow passage 322 may extend from the outer side of the outer pad contact 332 to the connection passage 350. As such, the slurry located outside the outer pad contact 332 may be introduced into the connection passage 350 through the inflow passages 322.

In an embodiment, the inflow passages 322 may be formed parallel to the radial direction of the pad contact 330, and may be substantially perpendicular to the connection passage 350. Alternatively, the inflow passages may be formed at an angle to the radial direction.

Because the inflow passages 322 penetrate the outer pad contact 332 in the radial direction, the outer pad contact 332 may be divided into multiple segments. If the space between inflow passages may be uniform, the respective outer pad contact segments may have substantially equal sizes.

The plurality of outflow passages 320 may be formed in the inner pad contact 334 and configured to discharge slurry from the connection passage 350 toward the wafer.

Particularly, each outflow passage 320 may extend from the connection passage 350 to the inner side of the inner pad contact 334. Therefore, the slurry residing in the connection passage 350 may be guided to the wafer through the outflow passages 320.

Like the inflow passages 322, the outflow passages 320 may be formed in the radial direction and may be substantially perpendicular to the connection passage 350. Accordingly, the outflow passages 320 and the inflow passages 322 may be arranged in parallel. In an embodiment, the outflow passages 320 may be formed at an angle to the radial direction.

Because the outflow passages 320 may penetrate the inner pad contact 334 in the radial direction, the inner pad contact 334 may also be divided into a plurality of segments. If the spacing between outflow passages is uniform, the respective inner pad contact segments may have substantially equal sizes.

In an embodiment, the inflow passages 322 and the outflow passages 320 may be arranged in a staggered manner. For example, at least one of the outflow passages 320 may be disposed between two adjacent inflow passages 322. In an embodiment, two or more outflow passages may be located between adjacent inflow passages.

Each guide passage 340 may be formed in the outer pad contact 332 and may be in communication with a corresponding inflow passage 322. The guide passages 340 may correspond to the previously described slurry guides 140, and repeated description of their structure and function is omitted.

FIGS. 10A to 10C are perspective views illustrating a retainer ring in accordance with an embodiment.

A mold block 300a of an embodiment may include an additional auxiliary guide passage 342, in addition to the elements shown in FIG. 9. Thus, the same reference numerals may refer to the same elements and any further illustrations with respect to the same elements may be omitted herein for brevity.

Referring to FIGS. 10A to 10C, the mold block 300a may further include an auxiliary guide passage 342.

The auxiliary guide passage 342 may be formed on the outer side of the inner pad contact 334. The auxiliary guide passage 342 may have the same shape and function as the guide passage 340, and may correspond to the previously described auxiliary slurry guide 142. Thus, repeated descriptions are omitted.

According to an embodiment, the retainer ring includes a slurry guide having an expanded width in communication with the slurry passage and formed with consideration of the polishing head’s rotational direction. In an embodiment, as the volume of the slurry guide increases, the slurry inflow amount is improved, thereby enhancing polishing efficiency and reducing the occurrence of the slurry bow wave phenomenon.

In particular, according to an embodiment, by forming an auxiliary slurry passage in the pad contact, the amount of slurry supplied to the wafer may be further improved, leading to enhanced performance of the wafer polishing system.