CARRIER HEAD MEMBRANE

Description

FIELD OF THE INVENTION

The present invention relates to a carrier head membrane, specifically to a flexible membrane mounted on a carrier head that achieves uniform pressurization and stable vacuum suction for wafer transfer.

BACKGROUND OF THE INVENTION

Chemical Mechanical Polishing (CMP) is a typical planarization method and procedure used in integrated circuit manufacturing. Usually, the substrate is mounted on a carrier head or polishing head, with the surface of the substrate pressed against a polishing pad or other polishing materials. The polishing effect is achieved through the relative movement between them. During the CMP process, factors such as the polishing pad, polishing slurry, polishing pad conditioner, and carrier head all influence the quality and efficiency of substrate planarization.

Regarding the carrier head, a flexible membrane is typically installed on the carrier head. This flexible membrane directly contacts the backside of the substrate. The chamber behind the flexible membrane is pressurized by gas or vacuumed to hold the wafer, causing the flexible membrane to expand outward and thereby apply pressure to the substrate for planarization polishing.

As the size of integrated circuits decreases and their density increases, the precision and technical requirements of manufacturing also increase. In the CMP process, the presence of unexpected non-uniform pressure in the chamber between the flexible membrane and the carrier head substrate further affects the planarization results.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a carrier head membrane for use in a polishing head.

The carrier head membrane comprises a main portion, a vertical portion, a horizontal portion and an outer periphery portion. The main portion is substantially flat and has a working surface for contacting a backside of a wafer. The vertical portion extends substantially vertically from the main portion. The horizontal portion extends from the vertical portion. The outer periphery portion extends substantially vertically from an outer edge of the main portion. A plurality of pressurizable regional chambers are provided and defined between the main portion and the polishing head, and a groove is provided in a circumferential junction portion between the main portion and the outer ring portion, which is located in the regional chamber and recessed toward an inner wall surface of the circumferential junction portion.

Other objectives, features and advantages of the invention will be further understood from the further technological features disclosed by the embodiments of the invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 shows a typical chemical mechanical polishing system.

FIG. 2 is a perspective view of a flexible membrane of the carrier head according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of FIG. 2.

FIG. 4A is an enlarged view of FIG. 3.

FIG. 4B is another aspect of the embodiment of FIG. 4A.

FIG. 4C is yet another aspect of the embodiment of FIG. 4A.

FIG. 5 is a perspective view of a flexible membrane of the carrier head according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view of FIG. 5.

FIG. 7A is an enlarged view of FIG. 6.

FIG. 7B is another aspect of the embodiment of FIG. 7A.

FIG. 7C is yet another aspect of the embodiment of FIG. 7A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It should be understood that although terms like first, second, and so on are used here to describe various elements, these terms are not intended to limit the elements by order or importance. These terms are merely for distinguishing one element from another. For instance, a first element might just as well be referred to as a second element, and vice versa, without deviating from the scope of this disclosure.

In the illustrations, the thicknesses of layers and regions are exaggerated for clarity. It is also important to note that when an element such as an element, layer, portion, or region is mentioned as being “on,” “over,” or “atop” another element, it may be directly in contact with it, or there may be intervening elements between them. Conversely, when something is stated to be “directly on,” “directly over,” or “directly atop” another, it implies no intervening elements.

Relative terms may be employed in this document to describe the relationship between one element, layer, portion, or region and another as depicted in the figures. It should be understood that these terms, along with those previously mentioned, are intended to encompass various orientations, not just the orientation shown in the figures.

The terminology used in this document is specifically for describing certain embodiments and is not meant to limit the scope of the disclosure. The singular forms “a,” “an,” and “the” include plural forms as well, unless clearly indicated otherwise by the context. Additionally, the terms “comprises,” “comprising,” “includes,” and “including” signify the presence of certain features, elements, or components, but do not exclude the possibility of additional features, elements, components, or their combinations. Unless the context explicitly dictates otherwise, indefinite and definite articles should be understood to encompass both the singular and plural forms.

FIG. 1 illustrates a chemical mechanical polishing system, which mainly comprises a platen 90, a polishing pad 91, a wafer carrier 92, a pad conditioner 93, and a slurry supply line 94. The wafer carrier 92 is equipped with a carrier head flexible membrane 10 (shown in FIG. 2 to FIG. 7C). A wafer 95 is placed on the polishing pad 91, with the carrier head flexible membrane 10 contacting and applying pressure to the backside of the wafer 95. This allows the front side of the wafer 95 to be polished under the action of the slurry and the polishing pad 91. The pad conditioner 93 is used to dress the polishing pad 91.

FIG. 2 and FIG. 3 show a carrier head flexible membrane 10 according to an embodiment of the present invention. The carrier head flexible membrane 10 includes a main portion 11, a vertical portion 12, a horizontal portion 13, and an outer ring portion 14. The carrier head flexible membrane 10 is designed to conform to the shape of the wafer carrier 92. In this embodiment, an outer structure of the carrier head flexible membrane 10 is a disc-shaped cover, while an internal structure of the carrier head flexible membrane 10 comprises multiple concentric ring structures.

The main portion 11 is substantially flat and extends along a plane, having an upper surface 111 and a working surface 112 for mounting the wafer 95. The outer ring portion 14 extends substantially vertically upward from a circumferential edge 113 of the main portion 11, forming an annular sidewall of the carrier head flexible membrane 10.

The vertical portion 12 extends substantially vertically upward from a central region 10a of the carrier head flexible membrane 10. The vertical portion 12 includes a first annular section 121 and a second annular section 122. The first annular section 121 extends vertically upward from the main portion 11. The second annular section 122 extends upward at an angle not equal to 90 degrees relative to the main portion 11. The angle between the second annular section 122 and the main portion 11 may be greater than 90 degrees or less than 90 degrees. In other words, the vertical portion 12 may extend upward longitudinally or inclined upward. A plurality of pressurizable regional chambers 20 are defined between the main portion 11 and the polishing head by the vertical portion 12.

The horizontal portion 13 extends radially in a planar direction from a top end of the vertical portion 12. The horizontal portion 13 includes a first concentric annular flap 131 and a second concentric annular flap 132. The first concentric annular flap 131 extends towards a central axis C of the main portion 11, while the second concentric annular flap 132 extends towards the circumferential edge 113 of the main portion 11. In one embodiment, the horizontal portion 13 may include a thick rim portion 133, located at one end of the horizontal portion 13 and protruding upward from the end. The cross-section of the thick rim portion 133 may be semicircular, rectangular, or other geometric shapes.

Referring to FIGS. 4A to 4C, the carrier head flexible membrane 10 further includes a junction portion 15. The junction portion 15 comprises a first region 151 located at the main portion 11 and a second region 152 located at the outer ring portion 14. The first region 151 is connected to the second region 152. The junction portion 15 further has an inner wall surface 153 and an outer wall surface 154. The inner wall surface 153 is recessed to form a groove 155. The groove 155 may extend outward in the planar direction (towards the circumference of the main portion 11), downward in the vertical direction, or outward and downward at an angle less than 90 degrees with the planar direction. In this embodiment, the groove 155 extends continuously along the circumference of the main portion 11, forming an annular groove. In other embodiments, the groove 155 may extend intermittently along the circumference of the main portion 11, forming multiple grooves arranged along the circumference of the main portion 11.

In one example, the groove 155 includes an upper wall surface 155a, a lower wall surface 155b, and an end wall 155c located between the upper wall surface 155a and the lower wall surface 155b. The upper wall surface 155a may be an inclined wall or a horizontal wall, while the lower wall surface 155b may be an arcuate wall, an inclined wall (as shown in FIG. 4A), or a horizontal wall (as shown in FIG. 4B and FIG. 4C). The end wall 155c may be an arcuate wall.

The groove 155 allows for an increase in air pressure within the outermost regional chamber 20a of the carrier head flexible membrane 10, thereby enhancing the downward pressure near the circumferential edge 113. This increase in pressure improves the polishing efficiency at the wafer edge.

In one embodiment, the junction portion 15 further includes a protrusion 156, which is formed on the outer wall surface 154 and extends downward. In this embodiment, the protrusion 156 extends continuously along the circumference of the main portion 11, forming an annular shape. In other embodiments, the protrusion 156 may extend intermittently along the circumference of the main portion 11, resulting in multiple protrusions 156 arranged along the circumference of the main portion 11. From a top view, the maximum distance across the protrusion 156 is less than the outer diameter of the wafer 95, and the thickness of the protrusion 156 relative to the working surface 112 of the main portion 11 is not greater than the thickness of the wafer 95. The cross-section of the protrusion 156 may be semicircular (as shown in FIG. 4A), rectangular (as shown in FIG. 4B and FIG. 4C), or another geometric shape. For example, the protrusion 156 may have a geometric shape that causes the plane of the working surface 112 to form an angle greater than 0 degrees.

During operation, the wafer 95 is positioned within the protrusion 156. The protrusion 156 helps to prevent and block residual chemicals and other contaminants from coming into contact with the wafer 95, thereby reducing the likelihood of contamination or scratching of the wafer's backside or frontside.

In one embodiment, the junction portion 15 further includes a protrusion 156, which is formed on the outer wall surface 154 and extends downward. In this embodiment, the protrusion 156 extends continuously along the circumference of the main portion 11, forming an annular shape. In other embodiments, the protrusion 156 may extend intermittently along the circumference of the main portion 11, resulting in multiple protrusions 156 arranged along the circumference of the main portion 11. From a top view, the maximum distance across the protrusion 156 is less than the outer diameter of the wafer 95, and the thickness of the protrusion 156 relative to the working surface 112 of the main portion 11 is not greater than the thickness of the wafer 95. The cross-section of the protrusion 156 may be semicircular, rectangular, or another geometric shape. For example, the protrusion 156 may have a geometric shape that causes the plane of the working surface 112 to form an angle greater than 0 degrees.

During operation, the wafer 95 is positioned within the protrusion 156. The presence of the protrusion 156 helps to prevent and block residual chemicals and other contaminants from coming into contact with the wafer 95, thereby reducing the likelihood of contamination or scratching of the wafer's backside or front side.

In one example, the upper surface 111 of the main portion 11 may be a flat plane extending from one end to the other. However, in some cases, the upper surface 111 of the main portion 11 may be divided into multiple regions corresponding to the regional chambers 20. Some regions of the upper surface 111 may be flat planes (as shown in FIG. 4C), while other regions may be inclined planes (as shown in FIG. 4A and FIG. 4B). For a single region, the upper surface 111 may consist of a single inclined plane (as shown in FIG. 4A), for example, sloping upward or downward from the central axis C of the main portion 11 towards the circumference. Alternatively, it may consist of multiple inclined planes, such as a first inclined plane and a second inclined plane (as shown in FIG. 4B), where the first inclined plane slopes downward from the central axis C of the main portion 11 towards the circumference, and the second inclined plane connects to the first inclined plane and slopes upward from the central axis C of the main portion 11 towards the circumference. The width of the first inclined plane and the second inclined plane may be equal, but it may also be that the width of the first inclined plane is greater or less than that of the second inclined plane. From a top view, the upper surface 111 of each region is concentric and annular, and if inclined, the inclined surface forms a concentric conical surface. If the upper surface 111 is inclined, the angle between the upper surface 111 and the horizontal plane (for example, based on the flat working surface 112) may range from 0.001 degrees to 3 degrees.

The configuration of the inclined upper surface 111 allows for controlling the concentration of air pressure within the regional chambers 20, thereby enabling different regional chambers 20 to have varying downward pressures and pressure distributions. This allows different regions of the wafer 95 to achieve different levels of wafer flatness and material removal according to the specific needs, resulting in improved control over wafer flatness and polishing removal across different regions.

The thickness of the main portion 11 is defined by the upper surface 111 and the working surface 112. In one example, the working surface 112 is a substantially flat plane, and thus the thickness of the main portion 11 varies according to the contour of the upper surface 111. In some examples, both the upper surface 111 and the working surface 112 are substantially flat planes, resulting in a uniform thickness of the main portion 11 from one end to the other. However, in some examples, the upper surface 111 of the main portion 11 is divided into multiple regions corresponding to the regional chambers 20 of the carrier head flexible membrane 10, with each region having a different thickness. Within a single region, the thickness of the main portion 11 may be constant, but it may also vary.

Similarly, by controlling the thickness distribution of the main portion 11, the concentration of air pressure within the regional chambers 20 of different areas of the carrier head flexible membrane 10 can be controlled. This enables different regional chambers 20 to have varying downward pressures and pressure distributions, allowing different regions of the wafer 95 to achieve different levels of polishing flatness and material removal according to specific requirements, thereby achieving better control over the polishing flatness and material removal process.

The outer ring portion 14 includes an outer wall surface 141 and an inner wall surface 142. The outer wall surface 141 may have different contours depending on the structure of the wafer carrier 92. For example, the outer wall surface 141 could be a flat sidewall, but it may also feature one or more protrusions and one or more recesses. These protrusions and recesses can assist in mounting the carrier head membrane 10 onto the fixture and can also improve the flatness after installation. The inner wall surface 142 may be a flat sidewall, but it could also be an inclined sidewall, such as one that slopes downward radially outward (towards the circumference), causing the thickness of the outer ring portion 14 to gradually decrease from top to bottom.

In one example, the horizontal portion 13 extending from the vertical portion 12 is provided with one or more protruding sections. These protruding sections may be radially outwardly expanding blocks 134a (as shown in FIG. 2), which could be radially extending segments 134b (as shown in FIG. 5) These can assist in mounting the carrier head membrane 10 onto the fixture and can also improve the flatness after installation. The protruding sections on the horizontal portion 13 in different regions can have varying shapes. For instance, the protruding section in the central region 10a of the carrier head membrane 10 may be a radially outwardly expanding block 134a, while the protruding section in the peripheral region 10b of the carrier head membrane 10 may be a radially extending segment 134b.

FIGS. 5 and 6 illustrate another embodiment of the carrier head membrane 10 according to the present invention. This embodiment of the carrier head membrane 10 is designed for use with a different specification of the wafer carrier 92 compared to the embodiment shown in FIGS. 1 and 2. FIGS. 7A to 7C show different variations of this embodiment of the carrier head membrane 10. In some examples, the groove 155 may include a first side wall surface 155d, a second side wall surface 155e, and an end wall 155c located between the first side wall surface 155d and the second side wall surface 155e. The first side wall surface 155d may be an arcuate wall surface (as shown in FIG. 7A and FIG. 7B), an inclined wall surface, or a vertical wall surface (as shown in FIG. 7C), and the second side wall surface 155e may also be an inclined wall surface or a vertical wall surface, while the end wall 155c is an arcuate wall surface.