POLISHING SYSTEM FOR SEMICONDUCTING WAFER SUBSTRATES

Description

BACKGROUND

Chemical mechanical polishing (“CMP”) is used in the manufacture of integrated circuits. A combination of chemical and mechanical forces is used to provide a level surface on a layer of a semiconducting wafer substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1A is a side view of a CMP system, in accordance with some embodiments of the present disclosure.

FIG. 1B is a plan view of the CMP system showing only some components.

FIG. 1C is a plan view of another embodiment of a CMP system, in accordance with some embodiments of the present disclosure. Here, one polishing pad can be used with two wafer carriers to polish two wafer substrates simultaneously.

FIG. 2 is a simplified side view of the CMP system, focusing on the polishing pad and the slurry arm.

FIG. 3 is a simplified perspective view of the CMP system, focusing on the slurry arm.

FIG. 4A is a side view of a gate of a valve of the CMP system in a closed state.

FIG. 4B is a side view of a gate of a valve of the CMP system in an open state. FIG. 4C is a side view of a gate of a valve of the CMP system in a semi-open state.

FIGS. 5A-5F show different shapes of holes and valves of the CMP system.

FIG. 6 is a plan view of a slurry arm with a configuration of open and closed holes.

FIGS. 7A-7P show different combinations of open and closed holes for the slurry arm.

FIG. 8A is a perspective view of a first example configuration of holes for slurry output through the slurry arm. FIG. 8B is a perspective view of a second example configuration of holes for slurry output through the slurry arm. FIG. 8C is a perspective view of a third example configuration of holes for slurry output through the slurry arm.

FIG. 9 is a schematic cross-sectional plan view of the slurry arm where all holes are supplied with slurry by a single supply tube within the slurry arm.

FIG. 10 is a schematic cross-sectional plan view of the slurry arm where all holes are supplied with slurry by different supply tubes within the slurry arm.

FIG. 11A is a schematic perspective view of the slurry arm where slurry exits the slurry arm via holes on the bottom of the slurry arm. FIG. 11B is a cross-sectional plan view of the slurry arm of FIG. 11A.

FIG. 12A is a schematic perspective view of the slurry arm where slurry exits the slurry arm via holes on one side of the slurry arm. FIG. 12B is a cross-sectional plan view of the slurry arm of FIG. 12A.

FIG. 13A is a schematic perspective view of the slurry arm where slurry exits the slurry arm via holes on both sides of the slurry arm. FIG. 13B is a cross-sectional plan view of the slurry arm of FIG. 13A.

FIG. 14 is a flow chart illustrating a method for performing CMP, in accordance with some embodiments.

FIG. 15A is a side view of a substrate with two layers thereon, prior to CMP.

FIG. 15B is a side view of a substrate with two layers thereon, after CMP has planarized the top layer.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Numerical values in the specification and claims of this application should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values which differ from the stated value by less than the experimental error of conventional measurement technique of the type described in the present application to determine the value. All ranges disclosed herein are inclusive of the recited endpoint.

The term “about” can be used to include any numerical value that can vary without changing the basic function of that value. When used with a range, “about” also discloses the range defined by the absolute values of the two endpoints, e.g., “about 2 to about 4” also discloses the range “from 2 to 4.” The term “about” may refer to plus or minus 10% of the indicated number.

The present disclosure relates to structures which are made up of different layers. When the terms “on” or “upon” are used with reference to two different layers (including the substrate), they indicate merely that one layer is on or upon the other layer. These terms do not require the two layers to directly contact each other, and permit other layers to be between the two layers. For example all layers of the structure can be considered to be “on” the substrate, even though they do not all directly contact the substrate. The term “directly” may be used to indicate two layers directly contact each other without any layers in between them. In addition, when referring to performing process steps to the substrate or upon the substrate, this should be construed as performing such steps to whatever layers may be present on the substrate as well, depending on the context.

The term “wafer substrate,” as used herein, refers to a substrate or to the combination of a substrate and any layers upon the substrate.

The present disclosure relates to chemical mechanical polishing (CMP) systems. CMP is used to planarize the surface of a wafer using relative motion between the wafer and a rotating CMP polishing pad to which a slurry is applied. Downward pressure is applied to push the wafer against the polishing pad, and elevated elements are worn down to obtain a surface with low surface roughness. This improves within die (WiD), within-wafer (WiW), and wafer-to-wafer (WtW) uniformity, which is desired.

Conventionally, a slurry arm for CMP has multiple holes. However, the slurry tubing (which provides the slurry) only leads directly to one hole. When the operator wants to change the landing position of the slurry upon the wafer, the operator has to stop the slurry tool and manually change the position of the slurry tubing in the slurry arm so that the slurry exits the slurry arm through a different hole. This causes downtime and decreases operational efficiency. The present disclosure provides an applicator or a slurry arm which uses multiple valves to control the slurry flow through the desired holes. This permits the operator to remotely control the landing position of the slurry and decreases tool downtime.

FIG. 1A is a side view of a CMP system 100, according to some embodiments of the present disclosure. FIG. 1B is a plan view of the CMP system. It is noted that not all components are illustrated in both figures.

Referring to both figures, the CMP system 100 includes a housing 110 that contains a chamber 112 for providing a sealed environment for the various components. One or more load ports (not shown) can be coupled to the wall of the chamber 112 to permit wafer substrates to enter and exit the CMP system 100 using a robotic wafer transfer system. A door 114 is illustrated which permits access to the chamber 112. A wafer load/unload station 116 is shown, where the wafer substrate 200 is placed.

Continuing, the CMP system 100 includes a polishing platen 120. The platen is in the form of a flat plate having an upper surface. The platen is attached to a shaft 124, which is coupled to a motor (not shown) for rotating the platen.

A polishing pad 130 is attached to the upper surface of the platen 120. This attachment is typically performed by adhesive, mechanical, or vacuum means. The polishing pad 130 is commonly made from materials that are soft enough not to substantially scratch the wafer 200, but hard enough to push abrasive particles in the slurry against the wafer to cause mechanical polishing. Examples of such materials may include polyurethane and polyester. The upper surface 132 of the polishing pad 130 may also include high-aspect grooves and asperities between the grooves. The polishing pad 130 has a surface roughness (Ra), which is used for polishing of the wafer substrate 200. The texture, composition, and/or the structure of the polishing pad 130 may vary depending on the material that is being polished.

A wafer carrier 140 (also known as a polishing head) includes a carrier head 142 which is attached to a carrier body 144. The carrier head 142 is rotatable relative to the body 144. The body 144 is best seen in FIG. 1B, and is attached to a robotic arm 150 for moving the wafer carrier between the load/unload station 116 and the platen 120, as indicated in FIG. 1A. The wafer carrier 140 can be positioned above the polishing pad 130, and can also be moved up-and-down relative to the polishing pad 130, both for transport and for applying a desired amount of force to press the wafer against the polishing pad 130, as indicated in FIG. 1B. One or more motors (not shown) may be present for rotating the carrier head, moving the carrier head, and/or moving the robotic arm.

The wafer substrate 200 can be picked up by the carrier head 142, for example using a vacuum to suck and hold the wafer substrate 200 upon the carrier head 142. A flexible membrane 152 is located between the wafer substrate 200 and the carrier head 142. The membrane can be inflated and used to press the wafer against the polishing pad 130. Vacuum is generally not applied during the polishing process. In some embodiments, the membrane can be made from a silicone, although other materials may also be used.

An annular retaining ring 154 is present along the perimeter of the carrier head to retain the wafer substrate 200 and prevent it from spinning off the wafer carrier 140. The retaining ring is typically formed from a wear-resistant material. Examples of suitable materials may include polyphenylene sulfide (PPS), polyetheretherketone (PEEK), or other polymers. In use, the retaining ring surrounds the circumference of the wafer substrate 200.

Continuing, an applicator or slurry dispenser 160 is present for applying slurry to the polishing pad 130 during the CMP process. The slurry is a mixture of abrasive particles and fluids. If desired, the fluids may be reactive with the top layer of the wafer substrate 200, which can aid in the CMP process. The abrasive particles mechanically polish the top layer of the wafer substrate 200. The abrasive particles may be, for example, silica, aluminum oxide ceria, silicon carbide, zirconium oxide, iron oxide, zinc oxide, or titanium dioxide. Other chemicals may also be present in the slurry, such as an oxidizer, a chelator, a surfactant, a corrosion inhibitor, a removal rate enhancer, etc. The composition of the slurry may vary depending on the material that is being polished.

As illustrated here, the slurry dispenser 160 includes a slurry arm 300 and one or more nozzles or holes (not visible) for dispensing the slurry. The slurry is usually dispensed near the center of the polishing pad 130, and then travels outwards due to centrifugal forces from rotation of the platen 120 and polishing pad 130. The slurry arm 300 may also move between the center of the polishing pad 130 and the perimeter of the polishing pad 130, as indicated in FIG. 1B.

The CMP system 100 also includes a pad conditioner 170, which is used to condition the polishing pad 130. The removal rate of a polishing pad 130 will decrease over time due to surface degradation, also known as glazing. The pad conditioner 170 removes the glazed surface of the polishing pad 130, uncovering fresh pad material, and also creates grooves and asperities to provide a more uniform and stable removal rate over time and over the entire surface of the polishing pad 130.

The pad conditioner 170 includes a conditioner head 172 which is attached to a conditioner body 174. The conditioner head 172 is rotatable relative to the body 174. The body 174 is attached to a movable arm 166 which can move between the center of the polishing pad 130 and the perimeter of the polishing pad 130, as indicated in FIG. 1B. The pad conditioner 170 can also be moved up-and-down relative to the polishing pad 130 for applying a desired amount of force to the polishing pad 130, as indicated in FIG. 1A. A pad conditioning ring 180 is affixed to the underside of the conditioner head 172. One or more motors (not shown) may be present for rotating the carrier head 142 and the conditioning ring 180, moving the carrier head 142, and/or moving the movable arm 166.

A controller 168 is used to control the various components, and to measure various conditions within the chamber 112 for the CMP process. In some embodiments, the system 100 can include one or more temperature sensors 182 configured to measure the temperature across the surface of the platen 120/polishing pad 130. These components are usually at a higher temperature than the slurry, so when slurry is deposited upon the polishing pad 130, the temperature sensor(s) 182 can detect the landing position of the slurry due to its lower temperature. In some embodiments, the system 100 can include one or more radiation sensors 184 (in addition to or in lieu of the temperature sensor(s) 182) configured to detect the temperature of the slurry to acquire the status of slurry distribution (e.g. infrared sensors). The temperature sensor(s) 182 and/or the radiation sensor(s) 184 can be attached to the slurry arm 300, or to the platen 120, or any other suitable location.

The system 100 may also include additional sensors (not shown) for monitoring other applicable parameters. For example, such sensors may include those for tracking the slurry flow rate, slurry pressure, the down force of the wafer carrier 140 and/or the pad conditioner 170, the rotation speed of the platen 120/wafer carrier/pad conditioner 170, the dwell time of the wafer carrier 140/pad conditioner 170, the temperature of the wafer substrate 200, etc. The controller 168 can also determine whether to activate or deactivate the system 100, how/when to move the wafer carrier 140 and/or the pad conditioner 170, control the motion of any automated handling system that may be present, etc. It is noted that these various parameters may not have to be held steady during operation, and could be changed by the controller 168 operating a computer program which alters their setpoints as appropriate. The controller 168 may also include a user interface for communicating with operators.

The controller 168 may be implemented on one or more general purpose computers, special purpose computer(s), a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an ASIC or other integrated circuit, a digital signal processor, a hardwired electronic or logic circuit such as a discrete element circuit, a programmable logic device such as a PLD, PLA, FPGA, Graphical card CPU (GPU), or PAL, or the like. Such devices typically include at least memory for storing a control program (e.g., RAM, ROM, EPROM) and a processor for implementing the control program.

During the CMP process, the polishing pad 130 rotates along with the platen 120. The carrier head 142 also rotates, causing the wafer substrate 200 to rotate. The polishing pad 130 and the carrier head 142 may rotate in the same direction (clockwise or counter-clockwise), or in opposite directions. As they rotate, slurry is deposited upon the polishing pad 130 and flows between the polishing pad 130 and the carrier head 142. Through the chemical reaction between reactive chemicals in the slurry and the top layer of the wafer substrate 200, and further through mechanical polishing due to contact between the abrasive particles in the slurry and the fop layer of the wafer substrate 200, the top layer of the wafer substrate 200 is planarized.

Referring again to FIG. 1A, the wafer substrate 200 may have a diameter 205 ranging from about 150 millimeters (mm) to about 450 mm, or even higher. Thus, the wafer carrier 140 may have a diameter 145 of about 170 mm to about 470 mm, or in more specific embodiments from about 300 mm to about 320 mm for handling 300 mm wafer substrates. Other ranges and values for these various diameters are also within the scope of this disclosure.

FIG. 1C illustrates another embodiment of a CMP system 100, in accordance with some embodiments of the present disclosure. In this embodiment, the system 100 includes two wafer carriers 140, 146 and one pad conditioner 170 that includes a conditioning ring 180. CMP can be concurrently performed using the two wafer carriers 140, 146 on the same polishing pad 130. This is possible because more of the polishing pad surface 132 can be used, particularly near the edge of the polishing pad 130. The two wafer carriers are independent of each other. The slurry arm 300 is shown in a retracted position, and is not over the polishing pad 130.

Referring now to FIG. 2 and FIG. 3, an embodiment of the slurry arm 300 is shown. As shown in FIG. 2, the slurry arm 300 includes a slurry arm main body 310. The slurry arm main body 310 has a length 311 along a Y-axis, a width 313 along an X-axis, and a height 315 along a Z-axis. In particular embodiments, the length 311 may be from about 50 centimeters (cm) to about 150 cm. In particular embodiments, the width 313 may be from about 10 cm to about 30 cm. In particular embodiments, the height 315 may be from about 5 cm to about 20 cm. However, other ranges and values are within the scope of the present disclosure. The length of the slurry arm main body 310 may be positioned along a radius of the polishing pad 130 for slurry deposition.

A plurality of nozzles or holes 320 is disposed along a length of the slurry arm main body 310. Twelve holes 320 are shown in FIG. 2, and thirteen holes 320 are shown in FIG. 3, although any suitable number of holes 320 may be used. The slurry arm 300 is positioned so that the holes 320 are positioned over a top surface of the polishing pad 130 for depositing slurry (indicated by arrow 305 extending out of the slurry arm main body 310).

The slurry arm main body 310 includes a proximal end 312 and a distal end 314. The proximal end 312 of the slurry arm 300 is mounted onto a support shaft 316, while the distal end 314 is positioned over the polishing pad 130. A controller valve 340 may be configured to control the physical flow of the slurry through a supply tube 342 in the slurry arm main body 310, and is illustrated as being present within the support shaft 316.

Not visible in FIG. 2 and FIG. 3 are valves 330 for controlling the slurry flow through one or more holes 320. However, a control circuit 302 is shown extending from controller 168 through the slurry arm, which is used to control the valves. It is contemplated in particular embodiments that slurry flow through each individual hole 320 may be controlled by an individual valve, and/or that slurry flow through one or more holes may be controlled by a given valve.

FIGS. 4A-4C show an example of a valve 330. In some embodiments, each valve 330 comprises a main gate body 332, a pair of gates 334 disposed in the main gate body 332, and an aperture 336 passing through the main gate body 332 that can be closed by the gates 334. Each gate 334 is positioned at opposite sides of the valve 330 and configured to move laterally relative to each other. The gates 334 are retractable within a portion of the main gate body 332. The controller can thus open or close each valve 330 by controlling movement of each gate 334.

The gates 334 for a corresponding valve 330 are continuously movable between a closed state and an open state. FIG. 4A shows the valve 330 in a closed state. As shown in FIG. 4A, the gates 334 are contacting each other, closing off the aperture 336 to prevent slurry flow therethrough. The gates 334 are slidable through a groove 323 defined within the main gate body 332. FIG. 4B shows the valve 330 in an open state. As shown in FIG. 4B, the gates 334 are completely retracted away from each other, opening the aperture 336 to its full extent to permit slurry flow therethrough. FIG. 4C shows the valve 330 in a semi-open state. As shown in FIG. 4C, the gates 334 are partially retracted within the main gate body 332, partially opening the aperture 336. This permits slurry flow therethrough, but at a slower rate compared to the open state of FIG. 4B. In particular embodiments, each gate 334 can be partially retracted at a distance of about 0.05 cm to about 2.5 cm. The aperture 336 itself may have a width 337 of about 0.1 cm to about 5 cm. However, other ranges and values are within the scope of the present disclosure. The state of the gate may also be considered the state of the valve.

In one example embodiment, each valve 330 may comprise a hydrophilic material. The hydrophilic material may be, for example, a photocatalyst type polymer (i.e., a polymer that can be synthesized using ultraviolet light). In another example embodiment, each valve 330 comprises a hydrophobic material. The hydrophobic material may be, for example, an acrylic resin, epoxy resin, polyethylene, polystyrene, polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), polydimethylsiloxane (PDMS), polyester, or polyurethane, or combinations thereof.

These materials can also be used for manufacturing each of the components of the slurry arm 300. In addition, the slurry arm 300 can also be made from polyfluoroalkyl (PFA), polytetrafluoroethylene (PTF), or polyetheretherketone (PEEK). The material used to make the slurry arm may depend on the characteristics of the slurry and abrasive particles. In general, the hydrophobicity characteristic of the slurry arm material would be the reverse of the slurry. The slurry can be an aqueous solution or an organic solution with abrasive particles. Deionized water may also pass through the slurry arm for cleaning, or possibly other chemicals.

FIGS. 5A-5F illustrate different shapes that may be used for the holes 320 and/or the valves 330. In particular embodiments, each hole 320 and/or valve 330 has a cross-sectional shape comprising a triangle (FIG. 5A), a rectangle (FIG. 5B), a circle (FIG. 5C), a hexagon (FIG. 5D), a trapezoid (FIG. 5E), or a heptagon (FIG. 5F). In particular embodiments, each valve 330 has a cross-sectional shape that matches the shape of the corresponding hole 320 in which the valve 330 is disposed. Each valve 330 can have a side having a length 335 of about 0.1 cm to about 5.0 cm, which can correspond to the dimensions of the holes 320. It is noted that the hole and valve do not have to have the same cross-sectional shape, so long as the valve is appropriately sized to close off the hole. For example, the hole may have a circular cross-section, and the valve may have a square or rectangular cross-section.

FIG. 6 is a side view of one example of the slurry arm 300 and how it can be used to control the slurry flow. The slurry arm is illustrated here with nine holes 320a-320i. Two of the holes 320a, 320i are disposed at opposing ends of the slurry arm main body 310) and are in an open state (illustrated as white rectangles). The other seven holes 320b-320h are in a closed state (illustrated as dark rectangles). When slurry flows through the slurry arm main body 310, the slurry is only output through the open holes 320a, 320i (designated again as an arrow 305) and blocked from flowing through the closed holes 320b-320h by the closed valves.

FIGS. 7A-7P shows different combinations of open and closed holes 320 (again, designated as corresponding white and dark rectangles). Generally, any suitable combination of open and closed holes 320 can be achieved via commands sent by the controller 168. For example, in these figures, the slurry arm 300 is illustrated as having five holes 320. The proximal end 312 and distal end 314 are also labeled.

Generally, any number of holes may be open, and any number of holes may be closed. In FIG. 7A, the two holes near the proximal end 312 are open. In FIG. 7B, the three holes near the proximal end 312 are open. In FIG. 7C, the four holes near the proximal end 312 are open. This may change the amount of slurry deposited near the perimeter of the polishing pad. In FIG. 7D, all five holes are open. This may deposit slurry across the entire surface of the polishing pad. In FIGS. 7E-7G, various holes are open in different locations. This may be done to concentrate slurry at desired radii upon the polishing pad. In FIG. 7H, the four holes near the distal end 314 are open. This may deposit slurry closer to the center of the polishing pad. In FIGS. 71-7O, various holes are open in different locations. Again, this can concentrate slurry at desired radii. In FIG. 7P, the two holes near the distal end 314 are open. This may deposit slurry closer to the center of the polishing pad.

FIGS. 8A-8C show three different examples of different hole configurations. FIG. 8A shows a slurry arm 300 having thirteen holes 320. The second and sixth holes are in the open state, the tenth hole is in the semi-open state, and the remaining holes are in the closed state. This configuration or recipe can be set automatically by the controller 168, or an operator can provide manual inputs through a user interface 186 (e.g., finger taps, pressing buttons, and so forth) in order to set this configuration of open holes 320. The user interface 186 can be, for example, a touchscreen, a set of buttons, a set of switches, and so forth, whether located proximate the slurry arm or in a remote location therefrom.

In the example of FIG. 8B, when the polishing rate is low along the center of the wafer substrate, a number of valves can be opened for the corresponding holes 320. In FIG. 8B shows that the tenth hole is now in the closed state while the eleventh, twelfth, and thirteenth holes are now in the open state. As a result, more slurry will be deposited on the polishing pad near the distal end 314 of the slurry arm 300.

In the example of FIG. 8C, when the polishing rate of the wafer is low closer to the edge of the wafer, the valves can be opened for the corresponding holes closer to the support shaft 316. The gates can be opened in the corresponding holes 320. FIG. 8C shows that the eleventh and twelfth holes 320 have been closed, and the fifth and seventh holes 320 have now been opened. As a result, more slurry will be deposited on the polishing pad closer to the edge of the wafer substrate.

FIG. 9 and FIG. 10 show different configurations of the slurry arm 300. FIG. 9 is a plan cross-sectional view of the slurry arm main body 310 showing all of the valves 330 are supplied with slurry using a single supply tube 342. FIG. 10 shows a configuration of the slurry arm 300 where a plurality of supply tubes 342 are used to supply slurry to the valves 330. As shown in FIG. 10, a first supply tube 342a supplies slurry to the four valves 330 near the proximal end 312 of the slurry arm, a second supply tube 342b supplies slurry to the center four valves 330, and a third supply tube 342c supplies slurry to the four valves 330 at the distal end 314 of the slurry arm. It will be appreciated that any number of supply tubes 342 can supply slurry to any possible combination of adjacent valves 330.

FIGS. 11A-13B show different embodiments of the slurry arm 300. FIG. 11A and FIG. 11B show an embodiment where the holes 320 are positioned on a bottom surface 327 of the slurry arm 300. FIG. 11A shows a perspective view of the slurry arm 300, showing a side surface 329 without any holes. Instead, the holes 320 are visible in the bottom surface 327 in the plan view of FIG. 11B. In this illustration, the slurry is supplied through a single supply tube 342 (represented by dotted box), and is illustrated as exiting through the holes (arrows 305).

FIG. 12A and FIG. 12B show an embodiment where the holes 320 are positioned on a single side surface 329 of the slurry arm 300, and not on side surface 328. Again, the plan view of FIG. 12B shows the slurry being supplied through a single supply tube 342 to all of the valves 330.

FIG. 13A and FIG. 13B show an embodiment where the holes 320 are positioned on opposing side surfaces 328, 329 of the slurry arm 300, and slurry can flow out of both sides surfaces 328, 329 of the slurry arm 300. In addition, the plan view of FIG. 13B illustrates the use of one valve to control slurry flow through more than one hole 320. As illustrated here, valve 330a (open) controls the slurry flow through supply tube 342a to two holes 320a, 320b. Similarly, valve 330b (open) controls the slurry flow through supply tube 342b to two holes 320c, 320d. Valve 330c (closed) controls the slurry flow through supply tube 342c to two holes 320e, 320f. Thus, three valves can control the slurry flow through six holes. It is noted the holes 320 can be positioned laterally, overlapping, or staggered relative to each other.

Although the valves 330 have been generally illustrated as being located within the slurry arm 300 adjacent to the holes 320, this is not required. For example, this does not occur in FIG. 13B. As another example, the valves 330 could be located within the support shaft 316 along with controller valve 340.

FIG. 14 is a flow chart illustrating a method 400 for performing CMP, in accordance with some embodiments. Reference to FIG. 1A, FIG. 2, FIG. 3, FIG. 10, and FIGS. 15A-15B may be helpful for better understanding. It is noted that not all steps described in the flow chart are required, and other steps may occur that are not described in the flow chart.

Referring initially to FIG. 15A, an example is shown of the wafer substrate 200 having a frontside 202 and a backside 204. A first layer 210 is present upon the frontside 202, and a second layer 212 covers the first layer 210. The second layer is the top layer 218 of the substrate, or put another way is the outermost exposed layer of the frontside of the substrate. The second layer includes the step height 213 of the first layer 210, and can be thinner over the edges of the first layer. This can be undesirable for high-resolution photolithography which requires height differences to be minimized for accurate printing. Thus, to obtain a level surface, the second layer is deposited to an initial thickness 215 that is greater than the final desired thickness, and CMP is performed to remove the step height.

The substrate 200 may be, for example, a wafer made of a semiconducting material. Such semiconductor materials can include silicon, for example in the form of crystalline Si. In alternative embodiments, the substrate can be made of other elementary semiconductors such as germanium, or may include a compound semiconductor such as silicon carbide (SiC), gallium arsenide (GaAs), gallium carbide, gallium phosphide, indium arsenide (InAs), indium phosphide (InP), silicon germanium (SiGe), silicon germanium carbide, gallium arsenic phosphide, or gallium indium phosphide. In particular embodiments, the substrate is silicon.

The first layer 210 and the second layer 212 can be a dielectric layer, an electrically conductive layer, a diffusion barrier layer, or any other layer that is useful in a semiconductor device or integrated circuit. Examples of dielectric materials may include silicon dioxide (SiO₂), silicon nitride (Si₃N₄), silicon carbide (SiC), hafnium dioxide (HfO₂), zirconium dioxide (ZrO₂), aluminum oxide (Al₂O₃), silicon oxynitride (SiO_xN_y), hafnium oxynitride (HfO_xN_y) or zirconium oxynitride (ZrO_xN_y), or hafnium silicates (ZrSi_xO_y) or zirconium silicates (ZrSi_xO_y) or silicon carboxynitride (SiC_xO_yN_z), or hexagonal boron nitride (hBN). Other dielectric materials may include tantalum oxide (Ta₂O₅), nitrides such as silicon nitride, polysilicon, phosphosilicate glass (PSG), fluorosilicate glass (FSG), undoped silicate glass (USG), high-stress undoped silicate glass (HSUSG), and borosilicate glass (BSG). Examples of electrically conductive materials may include metals such as copper, aluminum, nickel, chromium, gold, germanium, silver, titanium, tungsten, platinum, tantalum, ruthenium, cobalt, rhenium, palladium, or zirconium; composites like TiN, WN, or TaN; or alloys thereof; electrically conductive polymers; and carbon nanotubes. A diffusion barrier layer prevents metals from diffusing into a dielectric layer. Examples of suitable materials that act as a diffusion barrier can include Ti, Ta, Ru, TiN, TaN, or WN.

In step 402 of FIG. 14, and referring back to FIG. 1B, the wafer substrate 200 is mounted upon a wafer carrier 140. The backside 204 is proximate the wafer carrier head 142, and the frontside 202 of the wafer substrate faces the polishing pad 130 of the CMP system 100.

In step 404 of FIG. 14, a profile of the wafer substrate 200 is measured. This may be done, for example, using an appropriate sensor to measure the height across the surface of the wafer substrate 200, either directly or indirectly. Using that information, a polishing profile can be determined to obtain a level surface across the wafer substrate.

In step 406 of FIG. 14, the current settings of the valves 330 controlling slurry flow to the corresponding holes 320 is determined. To do so, the current state of each of the valves 330 is determined (i.e., whether the valves 330 are closed, open, or semi-open) by the controller 168. Then, in step 408, a desired configuration of the holes 320 and/or valves 330 is selected and set based on the polishing profile. This can be done automatically by the controller 168 according to preset recipes or based on appropriate algorithms, or by one or more manual user inputs. Examples of some parameters that may be set include (i) which holes 320 to flow the slurry through, (ii) how open or closed each valve 330 should be set, and/or (iii) a desired pressure or flow rate of the slurry through each supply tube 342.

In step 410, slurry is flowed through the slurry arm 300 towards the holes 320. This can be performed using the supply tube(s) 342. In step 412, the slurry is deposited upon the polishing pad 130 after passing through the open (or semi-open) valves 330.

In step 414, the wafer substrate 200 is pushed against the polishing pad 130 by the wafer carrier 140. The polishing pad rotates, and the substrate is planarized. As indicated by reference numeral 416, these method step may be continuously repeated during polishing. This may occur, for example, if the planarization of the substrate does not occur as predicted and adjustment is needed.

In step 418, once planarization is completed, slurry flow ceases. In step 420, the wafer substrate is removed from contact with the polishing pad. The resulting structure is shown in FIG. 15B. The step height is no longer present, and the final thickness 217 of the second layer is less than the initial thickness 215 as shown in FIG. 15A.

It is also contemplated the slurry arm 300 could be used for applying photoresist. For example, in spin coating, the substrate is placed on a rotating platen, which may include a vacuum chuck that holds the substrate in plate. The photoresist composition is then applied to the substrate using a slurry arm. The speed of the rotating platen is then increased to spread the photoresist evenly from the center of the substrate to the perimeter of the substrate. An even photoresist layer is desired, and the use of the slurry arm to deposit photoresist in desired locations may be useful in obtaining the even photoresist layer. The method of FIG. 14 is suitably adapted to photoresist application as well by measuring the profile of the photoresist layer rather than the wafer substrate.

The slurry arms of the present disclosure have several advantages. The slurry arm contains a plurality of holes, all of which are fed by a slurry supply tube (instead of only one hole at a time). In addition, the holes can be selectively opened and closed either automatically or manually from a remote location. This permits process recipes to be used that can open or close particular holes at given times to control slurry flow. This provides better wafer profile control, lowers the downtime frequency, lowers the workload of the operator, and provides for higher wafer throughput because the operator no longer needs to stop the CMP tool and manually re-position the slurry arm.

Some embodiments of the present disclosure thus relate to a slurry arm for an associated CMP system for semiconducting wafer substrates. The slurry arm includes a slurry arm main body. A plurality of holes is disposed along a length of the slurry arm main body. At least one valve controls slurry flow through each hole of the plurality of holes. A controller is configured to open or close each valve.

Other embodiments of the present disclosure relate to methods of performing CMP. The profile of a wafer substrate is measured. A configuration of a plurality of valves controlling slurry flow to a plurality of holes disposed along a length of the slurry arm is determined. The configuration comprises setting each of the valves in an open state, a semi-open state, or a closed state. Slurry flows through the slurry arm towards the plurality of holes, and the slurry is deposited upon a polishing pad.

In additional embodiments of the present disclosure, the landing position(s) of slurry upon the polishing pad are detected using at least one temperature sensor(s) and/or radiation sensor(s).

Still other embodiments of the present disclosure relate to CMP systems for semiconducting wafer substrates. A polishing pad is mounted upon a platen. A wafer carrier that can be positioned above the polishing pad is present. A slurry arm for depositing slurry upon the polishing pad includes a plurality of holes disposed along a length thereof. Each hole has a corresponding valve, and a controller is configured to control movement of each valve of the plurality of valves.

Other embodiments of the present disclosure relate to methods of applying photoresist to a wafer substrate. A configuration of a plurality of valves controlling photoresist flow to a plurality of holes disposed along a length of the photoresist applicator arm is determined. The configuration comprises setting each of the valves in an open state, a semi-open state, or a closed state. Photoresist flows through the photoresist applicator arm towards the plurality of holes, and the photoresist is deposited upon the wafer substrate. The wafer substrate is located on a rotating platen. The profile of the photoresist layer is measured, and the valve configuration can be changed to obtain a level photoresist surface.

Still other embodiments of the present disclosure relate to photoresist application systems for semiconducting wafer substrates. A wafer substrate can be placed upon a rotatable platen. A photoresist applicator arm for depositing photoresist includes a plurality of holes disposed along a length thereof. Each hole has a corresponding valve, and a controller is configured to control movement of each valve of the plurality of valves. The photoresist applicator arm can be moved over the rotatable platen.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.