The present disclosure relates to an apparatus for polishing and a method of polishing configured to polish a substrate such as a semiconductor wafer.
In a manufacturing process of semiconductors, planarization technology of planarizing the surfaces of the semiconductor devices become increasingly important. The most important technique of this planarization technology is chemical mechanical polishing (CMP). This CMP technique performs polishing by bringing a substrate such as a wafer into sliding contact with a polishing surface with supplying a polishing solution containing abrasive grains such as silica (SiO2) onto a polishing pad.
A polishing apparatus performing the CMP includes a polishing table configured to support a polishing pad having a polishing surface; and a substrate holing member called a top ring or the like and configured to hold a substrate. A procedure of polishing a substrate by using such a polishing apparatus presses the substrate against the polishing surface by a predetermined pressure, while holding the substrate by the top ring. The procedure of polishing then moves the polishing table and the top ring relative to each other, so as to bring the substrate into sliding contact with the polishing surface and perform flat and mirror polishing of the surface of the substrate.
In such a polishing apparatus, when a relative pressing force between the wafer and the polishing surface of the polishing pad during polishing is not uniform over the entire surface of the wafer, insufficient polishing or excessive polishing may occur according to the pressing forces applied to respective parts of the wafer. A measure taken to equalize the pressing force applied to the wafer provides a pressure chamber made of an elastic membrane (membrane) in a lower portion of a top ring and supply a gas such as the air to this pressure chamber. This polishes the substrate, while the substrate is pressed against the polishing surface of the polishing pad by the pressure of the gas.
After completion of the polishing process, the wafer on the polishing surface is vacuum-sucked to the top ring. The top ring with the wafer sucked thereto is moved up and is then moved to a position above a transfer or conveyance stage, where the wafer is released (separated) from the membrane. The release of the wafer is performed by injecting a release shower to a clearance between the wafer and the membrane with supplying the gas to the pressure chamber to swell the membrane (as described in PTL 1 and PTL 2).
In the wafer release process described above, in the case where a fluid including a gas such as nitrogen gas is injected or sprayed as the release shower to a location between the membrane and the wafer, the surface of the wafer may be instantaneously dried to cause a defect (fault) in the wafer.
By taking into account the foregoing, one object of the present disclosure is to suppress a substrate from being dried in the course of releasing the substrate from a substrate holding member in a polishing apparatus.
According to one aspect of the present disclosure, there is provided the apparatus for polishing, comprising: a polishing table configured to support a polishing pad; a substrate holding member having a substrate holding surface and a pressure chamber, which are made of an elastic membrane, wherein the pressure chamber has a plurality of areas arranged concentrically and a substrate is pressed against the polishing pad by a pressure in the pressure chamber; a pressure regulator configured to regulate a pressure of a gas that is supplied to the pressure chamber of the substrate holding member; one or a plurality of release nozzles configured to inject a pressurized fluid; and a control device configured to perform a substrate release process of releasing the substrate from the elastic membrane, the substrate release process controlling the pressure regulator to pressurize entirety of the elastic membrane by pressurizing all the areas in the pressure chamber and subsequently pressurize a center portion of the elastic membrane by pressurizing the pressure chamber such as to make a pressure in one or multiple areas on a center side, which include an area at a center of the pressure chamber, higher than pressures in other areas, wherein meanwhile the substrate release process controls the one or plurality of release nozzles to inject the pressurized fluid to a contact location between the elastic membrane and the substrate.
The following describes an embodiment with referring to the drawings. A substrate processing apparatus 100 according to this embodiment is a polishing apparatus configured to polish substrates, as one example. This embodiment is described with wafers referring to as one example of the substrates. The present disclosure is, however, applicable to any substrates other than the wafers (for example, glass substrates and printed circuit boards).
The loading/unloading module 2 includes two or more (four according to the embodiment) front loading units 20 which wafer cassettes stocked with a large number of wafers (substrates) are respectively mounted thereon. These front loading units 20 are arranged adjacent to the housing 1 and are arrayed along a width direction (a direction perpendicular to a longitudinal direction) of the substrate processing apparatus 100. An open cassette, an SMIF (standard manufacturing interface) pod or an FOUP (front opening unified pod) may be mounted on each of the front loading units 20. The SMIF pod and FOUP herein are closed containers configured to place a wafer cassette inside thereof and covered with a partition wall to maintain an environment independent of the outside space.
In the loading/unloading module 2, a traveling mechanism 21 is laid along the array of the front loading units 20, and a transfer robot (loader) 22 is placed on this traveling mechanism 21 to be movable along an array direction of the wafer cassettes. The transfer robot 22 moves on the traveling mechanism 21 to access the wafer cassettes mounted on the front loading units 20. The transfer robot 22 has two hands respectively provided on an upper side and on a lower side and is allowed to use the upper hand and the lower hand separately: using the upper hand to return each processed wafer to the wafer cassette and using the lower hand to take out each unprocessed wafer or each wafer to be processed, from the wafer cassette. Additionally, the lower hand of the transfer robot 22 is configured to rotate around a shaft center thereof and thereby invert the wafer.
The loading/unloading module 2 is an area that requires to maintain the cleanest state, so that the inside of the loading/unloading module 2 is continuously kept at higher pressure than the pressures of all of the outside of the substrate processing apparatus 100, the polishing module 3 and the cleaning module 4. The polishing module 3 uses a slurry as a polishing solution and is accordingly a dirtiest area. Accordingly, a negative pressure is formed inside of the polishing module 3, and the internal pressure of the polishing module 3 is kept lower than the internal pressure of the cleaning module 4. The loading/unloading module 2 is provided with a filter fan unit (not shown) that includes a clean air filter, such as an HEPA filter, a ULPA filter or a chemical filter and that is configured to continuously blow off the clean air after exclusion of particles, toxic vapors, and toxic gases.
The polishing module 3 is an area where polishing (flattening) of the wafers is performed and includes a first polishing unit 3A, a second polishing unit 3B, a third polishing unit 3C and a fourth polishing unit 3D. The first polishing unit 3A, the second polishing unit 3B, the third polishing unit 3C and the fourth polishing unit 3D are arranged, for example, along the longitudinal direction of the substrate processing apparatus 100 as shown in
As shown in
Similarly, the second polishing unit 3B includes a polishing table 30B with a polishing pad 10 mounted thereon; a top ring (substrate holding member) 31B; a polishing solution supply nozzle 32B; a dresser 33B; and an atomizer 34B. The third polishing unit 3C includes a polishing table 30C with a polishing pad 10 mounted thereon; a top ring (substrate holding member) 31C; a polishing solution supply nozzle 32C; a dresser 33C; and an atomizer 34C. The fourth polishing unit 3D includes a polishing table 30D with a polishing pad 10 mounted thereon; a top ring (substrate holding member) 31D; a polishing solution supply nozzle 32D; a dresser 33D; and an atomizer 34D.
The following describes a transfer mechanism configured to convey or transfer the wafer. As shown in
A second linear transporter 7 is placed adjacent to the third polishing unit 3C and the fourth polishing unit 3D. This second linear transporter 7 is a mechanism of conveying or transferring each wafer between three transfer or conveyance positions along the direction of the array of the third polishing unit 3C and the fourth polishing unit 3D (the three transfer positions are referred to as a fifth transfer position TP5, a sixth transfer position TP6, and a seventh transfer position TP7 sequentially aligned from the loading/unloading module side).
The wafer is conveyed to the first polishing unit 3A and the second polishing unit 3B by the first linear transporter 6. The top ring 31A of the first polishing unit 3A is moved between a polishing position and the second transfer position TP2 by a swing action of a top ring head 110. Accordingly, the wafer is transferred to the top ring 31A at the second transfer position TP2. Similarly, the top ring 31B of the second polishing unit 3B is moved between a polishing position and the third transfer position TP3, and the wafer is transferred to the top ring 31B at the third transfer position TP3. The top ring 31C of the third polishing unit 3C is moved between a polishing position and the sixth transfer position TP6, and the wafer is transferred to the top ring 31C at the sixth transfer position TP6. The top ring 31D of the fourth polishing unit 3D is moved between a polishing position and the seventh transfer position TP7, and the wafer is transferred to the top ring 31D at the seventh transfer position TP7.
A lifter 11 is placed at the first transfer position TP1 to receive the wafer from the transfer robot 22. The wafer is transferred from the transfer robot 22 to the first linear transporter 6 via this lifter 11. A shutter (not shown) is provided in the partition wall 1a to be placed between the lifter 11 and the transfer robot 22 and is opened in the course of conveyance of the wafer to transfer the wafer from the transfer robot 22 to the lifter 11. A swing transporter 12 is placed between the first linear transporter 6 and the second linear transporter 7 and the cleaning module 4. This swing transporter 12 is provided with a hand that is movable between the fourth transfer position TP4 and the fifth transfer position TP5. The wafer is transferred from the first linear transporter 6 to the second linear transporter 7 by the swing transporter 12. The wafer is conveyed to the third polishing unit 3C and/or the fourth polishing unit 3D by the second linear transporter 7. The wafer polished in the polishing module 3 is conveyed via the swing transporter 12 to the cleaning module 4, is washed and dried in the cleaning module 4 and is then transferred to the transfer robot 22.
The configuration of the polishing apparatus described above is only illustrative, and another configuration may be employed as the configuration of the polishing apparatus. The substrate processing apparatus 100 may be an apparatus other than the polishing apparatus.
[Polishing Unit]
The following describes the polishing unit more in detail. The first polishing unit 3A, the second polishing unit 3B, the third polishing unit 3C and the fourth polishing unit 3D have identical configurations with one another. The first polishing unit 3A is accordingly described below.
The polishing table 30A is connected via a table shaft 30Aa with a motor (not shown) that is placed below the polishing table 30A to be rotatable about this table shaft 30Aa. The polishing pad 10 is applied on an upper face of the polishing table 30A. A polishing surface 10a of the polishing pad 10 forms a polishing surface serving to polish a wafer W. A polishing solution supply nozzle 32A is placed above the polishing table 30A. A polishing solution Q is supplied onto the polishing pad 10 on the polishing table 30A by this polishing solution supply nozzle 32A.
The top ring 31A is basically comprised of: a top ring main body 202 configured to press the wafer W against the polishing surface 10a; and a retainer ring 203 configured to hold an outer periphery of the wafer W and prevent the wafer W from being protruded from the top ring 31A.
The top ring 31A is connected with a top ring shaft 111, which is configured to be vertically moved or moved up and down relative to the top ring head 110 by a vertical moving mechanism 124. The entire top ring 31A is lifted up and down to be positioned relative to the top ring head 110 by vertically moving this top ring shaft 111. A rotary joint 125 is attached to an upper end of the top ring shaft 111.
The vertical moving mechanism 124 configured to move up and down or vertically move the top ring shaft 111 and the top ring 31A includes a bridge 128 provided to support the top ring shaft 111 in a rotatable manner via a bearing 126; a ball screw 132 attached to the bridge 128; a support base 129 supported by a supporting column 130; and a servomotor 138 provided on the support base 129. The support base 129 that supports the servomotor 138 is fixed to the top ring head 110 via the supporting column 130.
The ball screw 132 includes a threaded shaft 132a connected with the servomotor 138; and a nut 132b which this threaded shaft 132a is screwed into. The top ring shaft 111 is integrated with the bridge 128 to be moved up and down. Accordingly, driving the servomotor 138 vertically moves the bridge 128 via the ball screw 132, so as to vertically move the top ring shaft 111 and the top ring 31A.
The top ring shaft 111 is connected with a rotary cylinder 112 via a key (not shown). This rotary cylinder 112 is provided with a timing pulley 113 on an outer circumferential portion thereof. A top ring rotating motor 114 is fixed to the top ring head 110. The timing pulley 113 is connected with a timing pulley 116 provided on the top ring rotating motor 114 via a timing belt 115. Accordingly, rotation driving of the top ring rotating motor 114 causes the rotary cylinder 112 and the top ring shaft 111 to be rotated integrally via the timing pulley 116, the timing belt 115 and the timing pulley 113, so as to rotate the top ring 31A. The top ring rotating motor 114 is provided with an encoder 140. The encoder 140 has a function of detecting a rotation angle position of the top ring 31A and a function of integrating the number of rotations of the top ring 31A. A sensor of detecting a rotation angle of the top ring 31A “reference position (0 degree)” may be provided separately. The top ring head 110 is supported by a top ring head shaft 117 that is supported by a frame (not shown) in a rotatable manner.
The control device 5 is configured to control the respective devices included in the apparatus, for example, the top ring rotating motor 114, the servomotor 138 and the encoder 140. A storage unit 51 is connected with the control device 5 by wire or wirelessly, so that the control device 5 is allowed to refer to the storage unit 51. Programs for controlling substrate processing operations, various parameters and the like are stored in the storage unit 51. The storage unit 51 includes a volatile and/or nonvolatile memory.
In the first polishing unit 3A configured as shown in
[Top Ring]
The following describes the top ring (substrate holding member) included in the polishing apparatus of the present disclosure.
As shown in
The elastic membrane (membrane) 204 has a plurality of partition walls 204a that are arranged concentrically to form a pressure chamber consisting of a plurality of areas/rooms between an upper face of the elastic membrane 204 and the lower face of the top ring main body 202. This pressure chamber includes a first area 205 that is a circular chamber, a second area 206 that is a ring-shaped chamber, a third area 207 that is a ring-shaped chamber, and a fourth area 208 that is a ring-shaped chamber. More specifically, the first area 205 is formed in a center portion or at the center of the top ring main body 202, and the second area 206, the third area 207 and the fourth area 208 are concentrically arranged and sequentially formed in a direction from the center toward the outer circumference. In the illustrated example, four areas are formed inside of the elastic membrane 204. The number of the areas may, however, be three or less or may be five or more (for example, eight).
The elastic membrane (membrane) 204 has a plurality of holes 204h for suction of the wafer that are pierced in a thickness direction of the elastic membrane and that are provided in the second area 206. The holes 204h are provided in the second area according to the embodiment but may be provided in a location other than the second area. A modified configuration may not provide a plurality of holes for suction of the wafer in the elastic membrane 204 but may cause the wafer to be adsorbed by the adsorptive property of the rubber material of the elastic membrane 204 and expansion/contraction of the elastic membrane 204.
A flow path 211 communicating with the first area 205, a flow path 212 communicating with the second area 206, a flow path 213 communicating with the third area 207 and a flow path 214 communicating with the fourth area 208 are formed inside of the top ring main body 202. The flow path 211 communicating with the first area 205, the flow path 213 communicating with the third area 207 and the flow path 214 communicating with the fourth area 208 are respectively connected with a flow path 221, a flow path 223 and a flow path 224 via a rotary joint 225. The flow paths 221, 223 and 224 are respectively connected with a pressure regulating unit 230 via valves V1-1, V3-1 and V4-1 and pressure regulators (for example, electropneumatic regulators) R1, R3 and R4. The flow paths 221, 223 and 224 are also respectively connected with a vacuum source 231 via valves V1-2, V3-2 and V4-2 and are respectively allowed to communicate with the atmosphere via valves V1-3, V3-3 and V4-3.
The flow path 212 communicating with the second area 206 is, on the other hand, connected with a flow path 222 via the rotary joint 225. The flow path 222 is connected with the pressure regulating unit 230 via a steam water separation tank 235, a valve V2-1 and a pressure regulator (for example, electropneumatic regulator) R2. The flow path 222 is also connected with a vacuum source 131 via the steam water separation tank 235 and a valve V2-2 and is allowed to communicate with the atmosphere via a valve V2-3. The pressure regulators R1 to R4 are connected with the control device 5. The control device 5 controls the pressure regulators R1 to R4 to change the pressures of the gas supplied to the respective areas inside of the membrane 204.
This configuration of changing the pressures in the respective chambers inside of the membrane 204 controls the swelling of the membrane 204 and enables the wafer W sucked to the membrane 204 to be released (separated) from the membrane 204. For example, the configuration of changing the pressures of the gas supplied into the membrane 204 according to the sticking force of the wafer W to the membrane 204 controls the swelling of the membrane 204 and stabilizes a time period required for releasing the wafer W from the membrane 204 (hereinafter may be referred to as wafer release time). For example, changing the pressures inside of the membrane 204 achieves a change to an appropriate pressure for the wafer W and thereby reduces the stress placed on the wafer W.
A retainer ring compression chamber 209 made of an elastic membrane is formed immediately above the retainer ring 203. The retainer ring compression chamber 209 is connected with a flow path 226 via a flow path 215 formed inside of the top ring main body (carrier) 202 and via the rotary joint 225. The flow path 226 is connected with the pressure regulating unit 230 via a valve V5-1 and a pressure regulator (for example, electropneumatic regulator) R5. The flow path 226 is also connected with the vacuum source 231 via a valve V5-2 and is allowed to communicate with the atmosphere via a valve V5-3. The retainer ring compression chamber 209 is used as a retainer ring pressing mechanism according to the embodiment. The retainer ring pressing mechanism may, however, be a fluid actuator using the air, water, oil or the like, an electric actuator using a ball screw or the like, or an elastic member including a spring and a bag-like portion.
The pressure regulators R1, R2, R3, R4 and R5 respectively have pressure regulating functions to regulate the pressures of a pressurized fluid supplied from the pressure regulating unit 230 to the first area 205, to the second area 206, to the third area 207, to the fourth area 208 and to the retainer ring compression chamber 209. The pressure regulators R1, R2, R3, R4 and R5 and the respective valves V1-1 to V1-3, V2-1 to V2-3, V3-1 to V3-3, V4-1 to V4-3 and V5-1 to V5-3 are connected with the control device 5 (shown in
In the top ring 31A configured as shown in
The following describes a series of polishing process performed by the substrate processing apparatus 100 configured as shown in
After completion of this wafer treatment process on the polishing pad 10, the membrane 204 is contracted, and the wafer W is vacuum sucked to the top ring 31A. The top ring 31A is then moved up and is moved to a substrate transfer apparatus (for example, a pusher) 150 provided in the first linear transporter (substrate transporting module) 6. After such moving, a gas (for example, nitrogen) is supplied to the respective areas inside of the membrane 204, so as to swell the membrane 204 to a predetermined degree and reduce the sticking area of the membrane 204 to the wafer W. A pressurized fluid is then blown between the membrane 204 and the wafer W. This releases the wafer W from the membrane 204. The release or separation of the wafer W from the membrane 204 may be referred to as wafer release. The following describes the details of this wafer release.
The predetermined degree to which the membrane 204 is swollen denotes a degree that causes the position of the wafer W to be a position where the pressurized fluid is injectable or sprayable from release nozzles (described later) to the rear face of the wafer W. In one example, the membrane 204 is swollen to make the height of the rear face of the wafer W substantially equal to the height of release nozzles 153 or slightly lower than the height of the release nozzles 153. This causes the pressurized fluid injected from the release nozzles 153 to enter between the membrane and the wafer, to hit against the membrane (and/or the rear face of the wafer), and to be supplied to a contact location between the membrane and the wafer.
[Pusher]
The following describes the operations of transferring the wafer W from the top ring 31A to the pusher 150. After completion of the wafer treatment process on the polishing pad the top ring 31A holds the wafer W by suction. The suction of the wafer W is implemented by making the holes 204h of the membrane 204 communicate with the vacuum source 131. The top ring 31A has the membrane 204 with the holes 204h provided in the surface thereof to suck the wafer W via these holes 204h as described above, so that the wafer W is sucked to the surface of the membrane 204.
After suction of the wafer W, the top ring 31A is moved up and is moved to the pusher 150 to release (separate) the wafer W. After the top ring 31A is moved to the pusher 150, a cleaning operation may be performed by rotating the top ring 31A with supplying pure water or a chemical solution to the wafer W sucked and held by the top ring 31A.
The push stage 152 and the top ring guide 151 of the pusher 150 are then moved up, and the top ring guide 151 is fit in the outer circumferential surface of the top ring 31A to achieve centering between the top ring 31A and the pusher 150. In this state, the top ring guide 151 pushes up the retainer ring 203. Simultaneous evacuation of the retainer ring compression chamber 209 accelerates the move-up of the retainer ring 203. After completion of the move-up of the pusher 150, a bottom face of the retainer ring 203 is pressed by an upper face of the top ring guide 151 to be pushed up to above a lower face of the membrane 204, so that a location between the wafer and the membrane is exposed. In the illustrated example of
A plurality of the release nozzles 153 are provided at a predetermined interval in a circumferential direction of the top ring guide 151 and are configured to inject the pressurized fluid F inward in a radial direction of the top ring guide 151 and toward the center of the top ring guide 151. This configuration injects a release shower made of the pressurized fluid F between the wafer W and the membrane 204 and performs the wafer release to release or separate the wafer W from the membrane 204.
[Fluid Supply Module to Release Nozzles]
The liquid supply source 312 supplies a liquid of a predetermined pressure or a liquid adjusted to a predetermined pressure. A valve 313 and a flowmeter 314 are provided in the flow path 311 connected with the liquid supply source 312. The valve 313 may be a gate valve or a flow control valve controlled by the control device 5. The flowmeter 314 may be, for example, a Karman vortex flowmeter or a differential pressure type flowmeter. The liquid supply source 312 is configured to supply the liquid adjusted to the predetermined pressure to the valve 313. The liquid supply source 312 may include, for example, a utility line in a factory or the like, a flow path connected with the utility line in the factory or the like, and/or a pressure regulator, a flow control valve and the like connected with the utility line in the factory or the like (not shown). The valve 313 may be directly connected with the utility line in the factory or the like. Opening the valve 313 enables the liquid of the predetermined pressure to be supplied from the liquid supply source 312 through the flow path 311 to the flow path 331.
The gas supply source 322 supplies a gas of a predetermined pressure or a gas adjusted to a predetermined pressure. A valve 323 and a check valve 324 are provided in a flow path 321 connected with the gas supply source 322. The valve 323 may be a gate valve or a flow control valve controlled by the control device 5. The gas supply source 322 is configured to supply the gas adjusted to the predetermined pressure to the valve 323. The gas supply source 322 may include, for example, a utility line in a factory or the like, a flow path connected with the utility line in the factory or the like, and/or a pressure regulator, a flow control valve and the like connected with the utility line in the factory or the like (not shown). The valve 323 may be directly connected with the utility line in the factory or the like. Opening the valve 323 enables the gas of the predetermined pressure to be supplied from the gas supply source 322 through the flow path 321 to the flow path 331.
In the configuration described above, closing the valve 323 and opening only the valve 313 enables only the liquid as the pressurized fluid F to be injected from the release nozzles 153. In the configuration described above, on the other hand, closing the valve 313 and opening only the valve 323 enables only the gas as the pressurized fluid F to be injected from the release nozzles 153. The configuration described above also enables both the liquid and the gas as the pressurized fluid F to be injected from the release nozzles 153.
In one example, after only the valve 313 is opened to fill the flow path 331 with the liquid (for example, DIW), only the valve 323 is opened to cause the liquid (for example, DIW) filled in the flow path 331 to be injected from the release nozzles 153 by the gas (for example, nitrogen gas) supplied from the gas supply source 322. In this case, the pressurized fluid F is a fluid mixture of the liquid (for example, DIW) and the gas (for example, nitrogen gas). The pressure of the gas (for example, nitrogen gas) supplied from the gas supply source 322 may be set higher than the pressure of the liquid (for example, DIW) supplied from the liquid supply source 312. For example, the pressure of the liquid (for example, DIW) may be set to 0.2 MPa, and the pressure of the gas (for example, nitrogen gas) may be set to 0.4 MPa. In the case where there is a pressure difference between the liquid and the gas, it is not preferable to open the valve 313 and the valve 323 simultaneously, because of the reason described later. The configuration of this embodiment accordingly first fills the flow path 331 with only the liquid and subsequently supplies the gas to the flow path 331 with stopping the supply of the liquid as described above. This causes the gas to push out and inject or spray the liquid. In this state, in order to prevent the liquid filled in the flow path from being used up prior to the wafer release and thereby prevent only the gas from being injected to the wafer, an injection start timing of the pressurized fluid is adjusted, based on a membrane swelling start timing. This effectively suppresses the wafer from being dried.
A conventional configuration simultaneously opens the valves 323 and 313, which are respectively connected with the gas supply source 322 and with the liquid supply source 312 having different pressures, to inject the fluid mixture of the gas and the liquid from the release nozzles. In this case, however, there may be a pressure difference occurring in a piping joint portion (a joint portion of the flow paths 311 and 321) of the gas and the liquid. This may cause the liquid to be blocked by the gas and cause only the gas to be injected from the release nozzles. The wafer is thus likely to be dried, depending on the wafer release time. The configuration of the embodiment, on the other hand, first fills the flow path 331 with only the liquid and subsequently supplies the gas to the flow path 331 with stopping the supply of the liquid. This configuration suppresses or prevents only the gas from being injected from the release nozzles and thereby suppresses the wafer from being dried. Furthermore, the configuration of the embodiment starts injection of the pressurized fluid after elapse of a predetermined delay time since the membrane swelling start timing. This prevents the liquid filled in the flow path from being used up prior to the wafer release and thereby prevents only the gas from being injected to the wafer. This effectively suppresses the wafer from being dried.
[Directions of Release Nozzles]
[Principle of Wafer Release]
As described above, after completion of the wafer treatment process on the polishing pad 10, the process moves the top ring 31A with the wafer W sucked thereto to the pusher 150 and causes the retainer ring 203 of the top ring 31A to be engaged with the top ring guide 151 of the pusher 150 (as shown in
The process subsequently stops vacuum suction of the wafer W by the top ring 31A, supplies the gas to all the areas 205 to 208 of the membrane 204 to pressurize and swell the entirety of the membrane 204 (overall pressurization step, as shown in
The process subsequently supplies the gas to the respective areas 205 to 208 of the membrane 204, such as to pressurize/swell the center portion of the membrane 204 (center portion pressurization step, as shown in
As described above, the membrane has the higher swellability on the center side. In the case where the respective areas are pressurized by an identical pressure, the area on the center side of the membrane is swollen to be slightly protruded from the other areas. The center portion pressurization step according to the embodiment is, however, different from this procedure but makes the pressure in the area on the center side of the membrane higher than the pressures in the other areas, so as to make the center side of the membrane protruded more prominently. This configuration sufficiently reduces the area of the contact location between the membrane and the wafer and accelerates the wafer release.
In the course of at least the center portion pressurization step, the process injects or sprays the pressurized fluid F from the release nozzles 153 toward the contract location between the membrane and the wafer (as shown in
When a wafer release is not detected in one center portion pressurization step, the center portion pressurization step may be performed repeatedly with a reset step of resetting the pressures in all the areas of the membrane 204 between the center portion pressurization steps, until detection of a wafer release. In the case where a wafer release is not detected during repetition of a predetermined number of (one or more) center portion pressurization steps, the process may reset the pressures in all the areas of the membrane 204 and repeat the control cycle from the overall pressurization step (shown in
[Control Cycle of Wafer Release]
In the comparative example (shown in
In the embodiment (shown in
As shown in
In the example of
As shown in
In the example of
[Flowchart of Wafer Release Process]
At step S10, after completion of a polishing operation, the top ring 31A with the wafer held thereby is moved to the transfer position (above the pusher 150).
At step S20, the pusher 150 is moved up to be engaged with the top ring 31A. This completes preparation for a start of the wafer release process.
At step S30, one control cycle in the sequence of wafer release process described above with referring to
At step S40, the wafer release process determines whether a release of the wafer is detected at every predetermined time interval. The detection of the wafer release may be determined, for example, by determining whether or not all the plurality of seating sensors 154 detect the wafer. When a release of the wafer is detected, the wafer release process stops the injection of the pressurized fluid F (step S50) and is terminated by stopping the pressurization of the membrane 204 and resetting the pressures in all the areas of the membrane 204 to the atmospheric pressure (step S60). The pusher 150 is then moved down to be separated from the top ring 31A and is moved to a cleaning position (a position where the wafer is transferred to the cleaning module 4) (step S70).
When a release of the wafer is not detected at step S40, the wafer release process proceeds to step S80. At step S80, it is determined whether one control cycle in the sequence of wafer release process is terminated. When it is determined at step S80 that one control cycle is not yet terminated, the wafer release process returns to step S30 to continue the currently ongoing one control cycle. When it is determined at step S80 that one control cycle is terminated, on the other hand, the wafer release process proceeds to step S90.
At step S90, the wafer release process determines whether the number of repetition of the one control cycle reaches an upper limit number of times. When it is determined that the number of repetition of the one control cycle does not yet reach the upper limit number of times, the wafer release process proceeds to step S110. The wafer release process performs an all area open setting to open all the area of the membrane 204 to the atmospheric pressure (corresponding to the reset step of
When it is determined at step S90 that the number of repetition of the one control cycle reaches the upper limit number of times, on the other hand, the wafer release process gives an alarm and performs an error process (step S100).
[Difference in Wafer Release Time by Injection Start Timing of Release Shower]
According to the measurement results shown in
In the configuration of pushing out the liquid by the gas to inject the pressurized fluid F, when the delay time is equal to 0.0 second, DIW filled in the flow path and injected from the release nozzles is run out prior to a release of the wafer, and afterwards only the nitrogen gas is sprayed onto the wafer. The wafer is thus likely to be dried. When the delay time of 0.5 seconds is employed, on the other hand, the power of DIW pushed out by the nitrogen gas is effectively and efficiently used for the wafer release and thus enables the wafer to be released in a DIW injection time. Completion of the wafer release in the DIW injection time suppresses the wafer from being dried and thereby suppresses the occurrence of a defect.
[Difference in Wafer Release Time by Directions of Release Nozzles]
According to the measurement results shown in
The configuration of the embodiment described above injects or sprays the pressurized fluid to the contact location between the membrane and the wafer in the state that the center portion of the membrane is pressurized to reduce the area of the contact location between the membrane and the wafer. This shortens the wafer release time. Shortening the wafer release time suppresses the wafer surface from being dried by the pressurized fluid and thereby suppresses the occurrence of a defect.
Furthermore, the configuration of the embodiment pressurizes the entire membrane prior to the pressurization of the center portion of the membrane. This reduces the stress placed on the wafer.
In the embodiment described above, the configuration of injecting only the liquid (for example, DIW) as the pressurized fluid effectively suppresses/prevents the wafer surface from being dried and suppresses/prevents the occurrence of a defect. In the case of injecting only the liquid (for example, DIW) as the pressurized fluid, the pressure of the pressurized fluid becomes lower and is thus likely to increase the wafer release time. The combination of the overall pressurization of the membrane and the center portion pressurization of the membrane described above, however, swells the membrane promptly and reduces the contact area between the membrane and the wafer. The injection of the liquid in this state shortens the wafer release time. The configuration of the embodiment thus effectively suppresses/prevents the wafer surface from being dried even when only the liquid is injected as the pressurized fluid, while avoiding the problem of the increase in the wafer release time.
In the embodiment described above, in the configuration of filling the liquid (for example, DIW) in the flow path of the release nozzles and pushing out and injecting the liquid from the release nozzles by the gas (for example, nitrogen gas), the liquid filled in the flow path may be run out prior to release of the wafer to cause injection of only the gas. Starting the injection from the release nozzles (injection of the liquid by the gas) after elapse of an appropriate delay time since the swelling start time of the membrane, however, enables the wafer to be released during the injection time of the liquid, before the liquid filled in the flow path is run out. This suppresses the wafer from being dried and thereby suppresses the occurrence of a defect.
Furthermore, the configuration of employing the combination of the overall pressurization of the membrane with the center portion pressurization of the membrane described above, and regulating the delay time of the pressurized fluid injection, shortens the wafer release time with the high reproducibility. This suppresses the wafer surface from being dried and thereby suppresses the occurrence of a defect even when only the gas is injected as the pressurized fluid.
The configuration of the embodiment described above sets the directions of the release nozzles toward the center of the wafer. This enables the pressurized fluid to be concentrated on the contact location between the membrane and the wafer and further shortens the wafer release time.
The configuration of the embodiment described above regulates the injection start timing/delay time of the release shower (pressurized fluid) to the appropriate value. This shortens the wafer release time, while avoiding reduction of the stability/reproducibility of the wafer release process.
In the configuration of the embodiment described above, the release nozzles are connected in a switchable manner with the liquid supply source and with the gas supply source. This configuration enables only the liquid, only the gas, and both the liquid and the gas to be injected as the pressurized fluid, in response to the user's request.
(1) The above embodiment describes the case that the pusher is the substrate transfer apparatus as an example. The substrate transfer apparatus may, however, be a retainer ring station made of a ring-shaped member that is engaged with the top ring. The retainer ring station has a shape substantially corresponding to the ring-shaped portion of the top ring guide 151 of the pusher 150 shown in
(2) The method of the wafer release process described in the above embodiment is not limited to the wafer and the polishing apparatus but may be applied to any substrate processing apparatus having a mechanism of holding any substrate on a surface of a membrane.
At least the following aspects are provided from the description of the above embodiments.
[1] According to one aspect, there is provided an apparatus for polishing, comprising: a polishing table configured to support a polishing pad; a substrate holding member having a substrate holding surface and a pressure chamber, which are made of an elastic membrane, wherein the pressure chamber has a plurality of areas arranged concentrically and a substrate is pressed against the polishing pad by a pressure in the pressure chamber; a pressure regulator configured to regulate a pressure of a gas that is supplied to the pressure chamber of the substrate holding member; one or a plurality of release nozzles configured to inject a pressurized fluid; and a control device configured to perform a substrate release process of releasing the substrate from the elastic membrane, the substrate release process controlling the pressure regulator to pressurize entirety of the elastic membrane by pressurizing all the areas in the pressure chamber and subsequently pressurize a center portion of the elastic membrane by pressurizing the pressure chamber such as to make a pressure in one or multiple areas on a center side, which include an area at a center of the pressure chamber, higher than pressures in other areas, wherein meanwhile the substrate release process controls the one or plurality of release nozzles to inject the pressurized fluid to a contact location between the elastic membrane and the substrate.
The substrate holding member is configured to hold the substrate by the substrate holding surface.
An injection start timing of the pressurized fluid may be at the start of the pressurization of the entirety of the elastic membrane or during the pressurization of the entirety of the elastic member.
The “one or multiple areas on the center side, which include the area at the center of the pressure chamber” may be one or multiple areas (including the area at the center of the pressure chamber) included in a range from the center of the pressure chamber (the elastic membrane, the substrate holding surface) to a length in a radial direction of not greater than 50% of a radius of the pressure chamber. More preferably, the “one or multiple areas on the center side, which include the area at the center of the pressure chamber” may be one or multiple areas (including the area at the center of the pressure chamber) included in a range from the center of the pressure chamber to a length in the radial direction of 40% to 50% of the radius of the pressure chamber. For example, in the case of a pressure chamber (the elastic membrane, the substrate holding surface) having a radius r, one or multiple areas included in a circular range having a radius of not greater than 0.5 r from the center (in another example, a radius of not greater than 0.45 r) may be pressurized as the center portion of the pressure chamber (the elastic membrane, the substrate holding surface). The one or multiple areas to be pressurized may be continuous areas or may be discrete areas.
The configuration of this aspect injects or sprays the pressurized fluid to the contact location between the elastic membrane and the substrate in the state that the center portion of the elastic membrane is pressurized to reduce the area of the contact location between the elastic membrane and the substrate. This shortens a substrate release time. Shortening the substrate release time suppresses a substrate surface from being dried by the pressurized fluid and thereby suppresses the occurrence of a defect. The entire elastic membrane is evenly swollen, prior to swelling of the center portion of the elastic membrane. This reduces the stress placed on the substrate.
The configuration of this aspect pressurizes the area of the high swellability on the center side of the membrane (the pressure chamber) to have the higher pressure than the pressure in the area of the low swellability on the outer side. This causes the center portion of the membrane to be protruded more prominently and effectively reduces the area of the contact location between the membrane and the substrate. In the case where the pressure chamber has a large number of areas, multiple areas including a center area may be pressurized to have a higher pressure than pressures in the other areas. This regulates the degree of protrusion in the center portion of the membrane and reduces the stress placed on the substrate.
[2] According to one aspect, the apparatus for polishing may further comprise a detection device configured to detect a release of the substrate from the elastic membrane. The control device may be configured to perform an overall pressurization step of pressurizing the entirety of the elastic membrane and subsequently perform a center portion pressurization step of pressurizing the center portion of the elastic membrane a predetermined number of times, and the control device may terminate the substrate release process when the detection device detects the release of the substrate from the elastic membrane. The detection device may be, for example, a contact sensor such as a seating sensor and may be configured to monitor pressures in the membrane and detect a release of the substrate.
In the case where the substrate is not released in one center portion pressurization step, the configuration of this aspect repeats a process of performing the center portion pressurization step after resetting the pressurization of the elastic membrane (by opening the pressure chamber of the elastic membrane to the atmosphere), so as to release the substrate.
[3] According to one aspect, in the apparatus for polishing, the control device may be configured to perform one control cycle repeatedly up to a predetermined upper limit number of times, wherein one control cycle performing the overall pressurization step and subsequently performing the center portion pressurization step the predetermined number of times, and the control device may terminate the substrate release process when the detection device detects the release of the substrate from the elastic membrane.
In the case where the substrate is not released in one control cycle, the configuration of this aspect repeats the control cycle, so as to release the substrate.
[4] According to one aspect, in the apparatus for polishing, the control device may control the release nozzle to start injection of the pressurized fluid during the pressurization of the entirety of the elastic membrane after elapse of a predetermined delay time since a start of the pressurization of the entirety of the elastic membrane.
The configuration of this aspect starts injection of the pressurized fluid after elapse of an appropriate delay time since a start of pressurization of the elastic membrane. This suppresses a variation in the substrate release time and improves the stability (reproducibility) of the substrate release process. In the case where the liquid is filled in a flow path of the release nozzle and is pushed out and injected from the release nozzle by the gas, the injection from the release nozzle (injection of the liquid by the gas) is started after elapse of an appropriate delay time since a start of swelling of the membrane. This prevents the liquid filled in the flow path from being used up prior to a release of the substrate (wafer) and prevents only the gas from being injected but enables the substrate to be released during an injection time of the liquid. This suppresses the substrate from being dried and thereby prevents the occurrence of a defect.
[5] According to one aspect, in the apparatus for polishing, the control device may pressurize the center portion of the elastic membrane by pressurizing the pressure chamber such as to make a pressure in the area at the center of the pressure chamber higher than pressures in other areas.
The configuration of this aspect pressurizes the pressure chamber such that only a single area at the center of the pressure chamber has the higher pressure than the pressures in the other areas. This effectively reduces the contact area between the elastic membrane and the substrate and further shortens the substrate release time.
[6] According to one aspect, in the apparatus for polishing, the one or multiple areas on the center side, which include the area at the center of the pressure chamber, may be one or multiple areas included in a range from the center of the pressure chamber to a length in a radial direction of not greater than 50% of a radius of the pressure chamber.
The configuration of this aspect effectively achieves a balance between the reduction of stress placed on the substrate and the reduction of the contact area between the elastic membrane and the substrate.
[7] According to one aspect, in the apparatus for polishing, the one or multiple areas on the center side, which include the area at the center of the pressure chamber, may be one or multiple areas included in a range from the center of the pressure chamber to a length in the radial direction of 40% to 50% of the radius of the pressure chamber.
The configuration of this aspect more effectively achieves a balance between the reduction of stress placed on the substrate and the reduction of the contact area between the elastic membrane and the substrate.
[8] According to one aspect, in the apparatus for polishing, an injection direction of the one or plurality of release nozzles may be directed toward the center of the substrate.
The configuration of this aspect enables the pressurized fluid to be concentrated on a contact location between the elastic membrane and the substrate that is contracted to the center of the elastic membrane/substrate by the center portion pressurization. This further shortens the substrate release time.
[9] According to one aspect, in the apparatus for polishing, the pressurized fluid injected from the release nozzle may be a liquid. For example, pure water such as DIW or another liquid that does not affect a semiconductor manufacturing process may be used as the liquid.
The configuration of this aspect uses the liquid as the pressurized fluid that is injected to the contact location between the elastic membrane and the substrate. This more effectively suppresses the substrate surface from being dried and thereby suppresses the occurrence of a drying-induced defect.
[10] According to one aspect, in the apparatus for polishing, the pressurized fluid injected from the release nozzle may be a gas. For example, an inert gas such as nitrogen gas or another gas that does not affect the semiconductor manufacturing process may be used as the gas.
The configuration of pressurizing the center portion of the elastic membrane and injecting the pressurized fluid shortens the substrate release time. Even when the gas is used as the pressurized fluid, this configuration suppresses the substrate surface from being dried and thereby suppresses the occurrence of a drying-induced defect.
[11] According to one aspect, in the apparatus for polishing, the pressurized fluid injected from the release nozzle may be a liquid and a gas.
The configuration of pressurizing the center portion of the elastic membrane and injecting the pressurized fluid shortens the substrate release time. Even when the liquid and the gas are used as the pressurized fluid, this configuration suppresses the substrate surface from being dried and thereby suppresses the occurrence of a drying-induced defect.
[12] According to one aspect, in the apparatus for polishing, the release nozzle may be connected with a liquid supply source and with a gas supply source to inject a liquid and/or a gas as the pressurized fluid.
The configuration of this aspect enables a liquid, a gas or a fluid mixture of a liquid and a gas to be selected as the pressurized fluid, in response to a user's request.
[13] According to one aspect, there is provided a method of polishing a substrate by using a substrate holding member having a substrate holding surface and a pressure chamber, which are made of an elastic membrane, wherein the pressure chamber has a plurality of areas arranged concentrically. The method comprises: a step of pressing the substrate against a polishing pad by a pressure in the pressure chamber and moving the substrate and the polishing pad relative to each other to polish the substrate; a step of holding the substrate after being polished, onto the substrate holding surface of the substrate holding member; and a step of releasing the substrate from the elastic membrane when the substrate is transferred from the substrate holding member to a substrate transfer apparatus. The step of releasing comprises: an overall pressurization step of pressurizing entirety of the elastic membrane by pressurizing all the areas in the pressure chamber; a center portion pressurization step of pressurizing a center portion of the elastic membrane by pressurizing the pressure chamber to make a pressure in one or multiple areas on a center side, which include an area at a center of the pressure chamber, higher than pressures in other areas; and a step of injecting the pressurized fluid to a contact location between the elastic membrane and the substrate, at least while the center portion of the elastic membrane is pressurized.
The configuration of this aspect has similar functions and advantageous effects to those described above with respect to the above aspect [1].
[14] According to one aspect, there is provided a non-volatile storage medium configured to store therein a program that causes a computer to perform a control method of an apparatus for polishing, wherein the apparatus for polishing is configured to polish a substrate by using a substrate holding member having a substrate holding surface and a pressure chamber, which are made of an elastic membrane, wherein the pressure chamber has a plurality of areas arranged concentrically. The program causes the computer to perform: a step of pressing the substrate against a polishing pad by a pressure in the pressure chamber and moving the substrate and the polishing pad relative to each other to polish the substrate; a step of holding the substrate after being polished, onto the substrate holding surface of the substrate holding member; and a step of releasing the substrate from the elastic membrane when the substrate is transferred from the substrate holding member to a substrate transfer apparatus. The step of releasing comprises: an overall pressurization step of pressurizing entirety of the elastic membrane by pressurizing all the areas in the pressure chamber; a center portion pressurization step of pressurizing a center portion of the elastic membrane by pressurizing the pressure chamber to make a pressure in one or multiple areas on a center side, which include an area at a center of the pressure chamber, higher than pressures in other areas; and a step of injecting the pressurized fluid to a contact location between the elastic membrane and the substrate, at least while the center portion of the elastic membrane is pressurized.
The configuration of this aspect has similar functions and advantageous effects to those described above with respect to the above aspect [1].
According to one aspect, there is provided an apparatus for processing a substrate, comprising: a substrate holding member having a substrate holding surface and a pressure chamber, which are made of an elastic membrane, wherein the pressure chamber has a plurality of areas arranged concentrically; a pressure regulator configured to regulate a pressure of a gas that is supplied to the pressure chamber of the substrate holding member; one or a plurality of release nozzles configured to inject a pressurized fluid; and a control device configured to perform a substrate release process of releasing the substrate from the elastic membrane, the substrate release process controlling the pressure regulator to pressurize entirety of the elastic membrane by pressurizing all the areas in the pressure chamber and subsequently pressurize a center portion of the elastic membrane by pressurizing the pressure chamber such as to make a pressure in one or multiple areas on a center side, which include an area at a center of the pressure chamber, higher than pressures in other areas, wherein meanwhile the substrate release process controls the one or plurality of release nozzles to inject the pressurized fluid to a contact location between the elastic membrane and the substrate. The apparatus for processing the substrate may include any of the technical features described in the above aspects [2] to [12].
According to one aspect, there is provided a method of processing a substrate by using a substrate holding member having a substrate holding surface and a pressure chamber, which are made of an elastic membrane, wherein the pressure chamber has a plurality of areas arranged concentrically. The method of processing the substrate comprises a step of holding the substrate after being processed, onto the substrate holding surface of the substrate holding member; and a step of releasing the substrate from the elastic membrane when the substrate is transferred from the substrate holding member to a substrate transfer apparatus, wherein the step of releasing comprises: an overall pressurization step of pressurizing entirety of the elastic membrane by pressurizing all the areas in the pressure chamber; a center portion pressurization step of pressurizing a center portion of the elastic membrane by pressurizing the pressure chamber to make a pressure in one or multiple areas on a center side, which include an area at a center of the pressure chamber, higher than pressures in other areas; and a step of injecting the pressurized fluid to a contact location between the elastic membrane and the substrate, at least while the center portion of the elastic membrane is pressurized. The method of processing the substrate may include any of the technical features described in the above aspects [2] to [12].
Although the embodiments of the present invention have been described based on some examples, the embodiments of the invention described above are presented to facilitate understanding of the present invent ion, and do not limit the present invention. The present invention can be altered and improved without departing from the subject matter of the present invention, and it is needless to say that the present invention includes equivalents thereof. In addition, it is possible to arbitrarily combine or omit the embodiments and the modifications described above and it is also possible to arbitrarily combine or omit respective constituent elements described in the claims and the specification in a range where at least a part of the above-mentioned problem can be solved or a range where at least a part of the effect is exhibited.
Number | Date | Country | Kind |
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2022-087034 | May 2022 | JP | national |