Substrate handling system and method for CMP processing

Abstract

A system and method for sequential single-sided CMP processing of opposing surfaces of a silicon carbide (SiC) substrate are disclosed. The method includes pressing a first surface of the substrate against one of a plurality of polishing pads, the polishing pads being mounted on corresponding polishing platens of a plurality of rotatable polishing platens. The method includes transferring the substrate from a substrate carrier loading station to a substrate alignment station using a first side of an end effector. The method includes transferring the substrate from the substrate alignment station to the substrate carrier loading station using the first side of the end effector. The method includes pressing a second surface of the substrate against one of the polishing platens.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments described herein generally relate to chemical mechanical polishing (CMP) systems and processes used in the manufacture of electronic devices. In particular, embodiments herein relate to substrate handling schemes for sequential single-sided CMP of opposing surfaces of a substrate, such as a silicon carbide (SiC) substrate. [Background technology]

[0002] Chemical-mechanical polishing (CMP) is commonly used to planarize or polish material layers deposited on the surface of crystalline silicon (Si) substrates during semiconductor device fabrication. In a typical CMP process, the substrate is held in a substrate carrier, which presses the backside of the substrate against a rotating polishing pad in the presence of a polishing fluid. The polishing fluid generally comprises an aqueous solution of one or more chemical components and nanoscale abrasive particles suspended in the aqueous solution. Through a combination of chemical and mechanical activity provided by the polishing fluid and the relative motion between the substrate and polishing pad, material is removed across the surface of the material layer of the substrate that contacts the polishing pad.

[0003] CMP can also be used to fabricate crystalline silicon carbide (SiC) substrates, which, due to their unique electrical and thermal properties, offer superior performance to Si substrates in advanced high-power and high-frequency semiconductor device applications. SiC substrates are typically sliced ​​from single-crystal ingots to provide circular wafers with a silicon-terminated surface (Si-surface) and a carbon-terminated surface (C-surface) opposite the Si-surface. Each of the Si-surface and C-surface is then typically processed to a desired thickness and surface finish using a combination of grinding, lapping, and CMP processes. For example, CMP processes can be used to planarize one or both of the Si-surface and C-surface, to remove subsurface damage caused by previous grinding and / or lapping steps, and / or to prepare the SiC substrate for subsequent epitaxial growth of SiC.

[0004] CMP processing of Si and C surfaces can be performed simultaneously, for example, using a double-sided polishing system, or sequentially using a single-sided polishing system. Due to their different atomic compositions and therefore different reactivity to the CMP process, different polishing results, such as material removal rates and finished surface roughness, can be obtained for Si and C surfaces for the same polishing parameters. Sequential single-sided polishing of Si and C surfaces advantageously allows for fine tuning of the respective CMP processes used therewith, resulting in improved surface finish results when compared to double-sided polishing.

[0005] Reusing a single-sided polishing system previously used for CMP processing during semiconductor device fabrication provides the fine control desired for the fabrication of SiC substrates. Unfortunately, the substrate handlers of single-sided polishing systems used during the fabrication of semiconductor devices on Si substrates are typically configured to polish only one side of the substrate surface, e.g., only the active side of the substrate on which electronic devices are formed. Therefore, to facilitate sequential single-sided polishing of the Si and C surfaces, or vice versa, the SiC substrate is typically removed from the CMP system after its first surface (Si or C surface) has been polished, inverted within its substrate holder, and returned to the CMP system for polishing its second surface (the remaining unpolished Si or C surface).

[0006] Flipping the SiC substrate in its substrate holder between successive single-sided CMP processes is typically performed manually, which unfortunately is labor-intensive and can result in undesirable errors and delays during processing, thereby increasing the cost of processing the substrate.

[0007] Therefore, what is needed in the art is an apparatus and method for solving the above problems. Summary of the Invention

[0008] The present disclosure relates generally to chemical mechanical polishing (CMP) systems and processes used in the manufacture of electronic devices. In particular, the present disclosure relates to a substrate handling method used in sequential single-sided CMP processing of silicon carbide (SiC) substrates on both sides in a single-sided polishing system.

[0009] In one embodiment, a substrate polishing system includes a basin defining a substrate holding area, the basin being sized to receive one or more substrate cassettes, each configured to hold a plurality of substrates. The system includes a substrate alignment station disposed within the substrate holding area, a plurality of polishing stations, each polishing station including a rotatable polishing platen, and a substrate carrier loading station. The system includes a plurality of substrate carriers suspended from a carriage assembly, the carriage assembly being rotatable about a carriage axis to move individual substrate carriers among the plurality of substrate carriers between the plurality of polishing stations and the substrate carrier loading station, a substrate handler including an end effector having a first side and a second side opposite the first side, and a computer-readable medium having stored thereon instructions for a substrate processing method. The substrate processing method includes, in sequence: (a) pressing a first surface of a substrate against one of a plurality of polishing pads, the plurality of polishing pads being mounted on corresponding polishing platens of a plurality of rotatable polishing platens; (b) using a first side of an end effector to transfer the substrate from a substrate carrier loading station to a substrate alignment station; (c) using the first side of the end effector to transfer the substrate from the substrate alignment station to the substrate carrier loading station; and (d) pressing a second surface of the substrate against one of the plurality of polishing pads.

[0010] In another embodiment, a substrate processing method includes: (a) pressing a first surface of a substrate against one of a plurality of polishing pads, the polishing pads being mounted on corresponding polishing platens of a plurality of rotatable polishing platens; (b) using a first side of an end effector to transfer the substrate from a substrate carrier loading station to a substrate alignment station; (c) using the first side of the end effector to transfer the substrate from the substrate alignment station to the substrate carrier loading station; and (d) pressing a second surface of the substrate against one of the plurality of polishing platens.

[0011] In yet another embodiment, a computer-readable medium has stored thereon instructions for a substrate processing method, the substrate processing method including: (a) pressing a first surface of a substrate against one of a plurality of polishing pads, the plurality of polishing pads being mounted on corresponding polishing platens of a plurality of rotatable polishing platens; (b) transferring the substrate from a substrate carrier loading station to a substrate alignment station using a first side of an end effector; (c) transferring the substrate from the substrate alignment station to the substrate carrier loading station using the first side of the end effector; and (d) pressing a second surface of the substrate against one of the plurality of polishing platens.

[0012] So that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the present disclosure briefly summarized above can be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the present disclosure is also susceptible to other equally effective embodiments, and therefore, the accompanying drawings illustrate only typical embodiments of the present disclosure and should not be considered as limiting the scope of the present disclosure. [Brief explanation of the drawings]

[0013] [Figure 1A]FIG. 1 is a schematic side view of an exemplary polishing station that may be used to practice the methods described herein, according to one embodiment. [Figure 1B] FIG. 1 is a schematic plan view of a portion of a multi-station polishing system that may be used to practice the methods described herein, according to one embodiment. [Figure 1C] FIG. 1C is a schematic cross-sectional side view of the substrate carrier loading station of FIG. 1B, according to one embodiment. [Figure 2A] FIG. 1C is a schematic isometric view of the multi-station polishing system of FIG. 1B, further including a substrate handling system that may be used to perform methods described herein, according to one embodiment. [Figure 2B] 2B schematically illustrates degrees of movement of an end effector of the substrate handling system of FIG. 2A according to one embodiment. [Figure 2C] 2B schematically illustrates degrees of movement of an end effector of the substrate handling system of FIG. 2A according to one embodiment. [Figure 2D] 2B schematically illustrates degrees of movement of an end effector of the substrate handling system of FIG. 2A according to one embodiment. [Figure 3] 3 is a schematic cross-sectional side view of a substrate alignment station that can be used with the substrate handling system of FIG. 2 according to one embodiment. [Figure 4] 1A-1D illustrate a substrate processing method according to an embodiment. [Figure 5A] 5 is a schematic side view of a polishing station that can be used to perform the method of FIG. 4, according to one embodiment. [Figure 5B] 4A is a schematic isometric view of the multi-station polishing system of FIG. 2 illustrating one aspect of the method described in FIG. 4, according to one embodiment. [Figure 5C] 4A is a schematic isometric view of the multi-station polishing system of FIG. 2 illustrating one aspect of the method described in FIG. 4, according to one embodiment. [Figure 5D] 4A is a schematic isometric view of the multi-station polishing system of FIG. 2 illustrating one aspect of the method described in FIG. 4, according to one embodiment. [Figure 5E] 5 is a schematic side view of a polishing station that can be used to practice the method of FIG. 4, according to an embodiment. [Figure 6A] 1 is a schematic isometric view of an exemplary substrate handler assembly according to one or more embodiments. [Figure 6B] FIG. 6B is an enlarged isometric view of the exemplary end effector shown in FIG. 6A. [Figure 6C] 6C is an enlarged cross-sectional view of the exemplary rotary actuator taken along section line 6-6' of FIG. 6B. [Figure 6D] FIG. 6D is an isometric view of the rotary actuator of FIG. 6C. DETAILED DESCRIPTION OF THE INVENTION

[0014] For ease of understanding, wherever possible, identical reference numerals have been used to designate identical elements common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0015] The present disclosure relates generally to chemical mechanical polishing (CMP) systems and processes used in the manufacture of electronic devices. In particular, embodiments of the present disclosure relate to flipping silicon carbide (SiC) substrates for continuous single-sided CMP polishing.

[0016] FIGURE 1A is a schematic side view of one embodiment of a polishing station 100a that can be used to implement the methods described herein. FIGURE 1B is a schematic plan view of a portion of a multi-station polishing system 101 including multiple polishing stations 100a-100c, each of which is substantially similar to the polishing station 100a shown in FIGURE 1A. In FIGURE 1B, at least some of the components of the polishing station 100a shown in FIGURE 1A are not shown on the multiple polishing stations 100a-100c to reduce visual clutter.

[0017] 1A, polishing station 100a includes a platen 102, a first actuator 104 coupled to platen 102, a polishing pad 106 mounted on and secured to platen 102, a fluid delivery arm 108 positioned above polishing pad 106, a substrate carrier 110 (shown in cross section), and a pad conditioner assembly 112. Here, substrate carrier 110 is suspended from a carriage arm 113 (FIG. 1B) of a carriage assembly 115, such that substrate carrier 110 is positioned above polishing pad 106 and faces toward polishing pad 106. The carriage assembly 115 is rotatable about a carriage axis C to move the substrate carrier 110, and thus the substrate 122 chucked thereon, between the substrate carrier loading station 103 (FIG. 1B) and / or between the polishing stations 100a-100c of the multi-station polishing system 101. The substrate carrier loading station 103 includes a load cup 150 (shown in phantom) for loading the substrate 122 onto the substrate carrier 110.

[0018] During polishing of a substrate, the first actuator 104 is used to rotate the platen 102 about a platen axis A, and the substrate carrier 110 is disposed above the platen 102 and faces the platen 102. The substrate carrier 110 is used to press the surface to be polished (shown in phantom lines) of a substrate 122 disposed therein against the polishing surface of the polishing pad 106 while simultaneously rotating about a carrier axis B. Here, the substrate carrier 110 includes a housing 111, an annular retaining ring 115 coupled to the housing 111, and a membrane 117 extending across the inner diameter of the retaining ring 115. The retaining ring 115 surrounds the substrate 122 and prevents the substrate 122 from slipping off the substrate carrier 110 during polishing. The membrane 117 is used to apply a downward force to the substrate 122 and to chuck the substrate onto the substrate carrier 110 during substrate loading operations and / or between substrate polishing stations. For example, during polishing, pressurized gas is typically supplied to the carrier chamber 119 to exert a downward force on the membrane 117, and therefore on the substrate 122 in contact with the membrane 117. Before and after polishing, a vacuum may be applied to the chamber 119, causing the membrane 117 to bow upward, forming a low-pressure pocket between the membrane 117 and the substrate 122, thus vacuum-chucking the substrate 122 within the substrate carrier 110.

[0019] The substrate 122 is pressed against the pad 106 in the presence of a polishing fluid supplied by the fluid supply arm 108. Typically, a rotating substrate carrier 110 moves between the inner and outer diameters of the platen 102, in part to reduce uneven wear on the surface of the polishing pad 106. Here, the substrate carrier 110 is rotated using a first actuator 124 and oscillated using a second actuator 126.

[0020] Here, pad conditioner assembly 112 includes a fixed abrasive conditioning disk 120, such as a diamond-impregnated disk, that can be pressed against polishing pad 106 to regenerate its surface and / or remove polishing by-products or other debris therefrom. In other embodiments, pad conditioner assembly 112 may include a brush (not shown).

[0021] Here, operation of the multi-station polishing system 101 and / or its individual polishing stations 100a-100c is facilitated by a system controller 136 (FIG. 1A). The system controller 136 includes a programmable central processing unit (CPU 140), which is operable with memory 142 and support circuits 144. The support circuits 144 are conventionally connected to the CPU 140 and include cache, clock circuits, input / output subsystems, power supplies, etc., and combinations thereof, connected to various components of the polishing system 101 to facilitate control of the substrate polishing process. For example, in some embodiments, the CPU 140 can be one of any form of general-purpose computer processor used in industrial settings, such as a programmable logic controller (PLC), to control various polishing system components and sub-processors. Memory 142 is connected to CPU 140 and is non-transitory, typically being one or more readily available memories such as random access memory (RAM), read only memory (ROM), a floppy disk drive, a hard disk, or any other form of local or remote digital storage.

[0022] As used herein, memory 142 is a form of computer-readable storage medium (e.g., non-volatile memory) that contains instructions that, when executed by CPU 140, facilitate operation of processing system 101. The instructions in memory 142 are in the form of a program product, such as a program that implements the methods of the present disclosure (e.g., a middleware application, an appliance software application, etc.). The program code may conform to any one of several different programming languages. In one example, the present disclosure may be implemented as a program product stored on a computer-readable medium for use with a computer system. The program of the program product defines functions of embodiments (including the methods described herein).

[0023] Exemplary computer-readable storage media include, but are not limited to, (i) non-writable storage media on which information is permanently stored (e.g., a read-only memory device within a computer, such as a CD-ROM disk readable by a CD-ROM drive, a flash memory, a ROM chip, or any type of solid-state nonvolatile semiconductor memory), and (ii) writable storage media on which changeable information is stored (e.g., a floppy disk in a disk drive or hard disk drive, or any type of solid-state random-access semiconductor memory). Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, become embodiments of the present disclosure.

[0024] 1C is a schematic cross-sectional side view of the substrate carrier loading station 103 of FIG. 1B according to one embodiment. As shown in FIG. 1C, a load cup 150 includes a pedestal 152 for loading a substrate 122 to be polished thereon into the substrate carrier 110 and for unloading a polished substrate 122 from the substrate carrier 110. The pedestal 152 is movable in the Z direction, i.e., toward and away from the substrate carrier 110 disposed thereon. Here, the load cup 150 includes a shroud 154 surrounding the pedestal 152. In some embodiments, the load cup 150 further includes one or more nozzles (not shown) disposed radially inward of the pedestal 152 for directing a cleaning liquid, such as deionized water, toward the surface of the substrate carrier 110 to remove polishing liquid accumulated on the surface.

[0025] Herein, the substrate 122 is transferred to and from the pedestal 152 with the surface to be polished facing downward. For example, here, a first surface 122a of the substrate 122 to be polished is in contact with, and therefore faces, the pedestal 152, and a second surface 122b of the substrate 122 opposite the first surface faces away from the pedestal 152 toward the substrate carrier 110.

[0026] In some embodiments, the substrate 122 may be a crystalline silicon carbide (SiC) substrate, where the first surface 122a is silicon-terminated (Si-surface) and the second surface 122b is carbon-terminated (C-surface), or vice versa. In such embodiments, the first surface 122a may be polished first by loading the substrate 122 in a "face-down orientation," i.e., so that the first surface 122a is in contact with the surface of the pedestal 152 that faces the substrate carrier. Here, the substrate 122 is transferred to the substrate carrier loading station 103 using the end effector 242 of the substrate handling system 200 (shown in FIG. 2). The pedestal 152 is then raised and / or the substrate carrier 110 is lowered, and the substrate 122 is vacuum-chucked into the substrate carrier 110. The substrate carrier 110 is used to move the substrate 122 between one or more polishing stations 100a-100c and to press the first surface 122a of the substrate 122 against one or more polishing pads 106 of the polishing stations 100a-100c.

[0027] Once the first surface 122a has been polished, the substrate carrier 110 is returned to its position above the substrate carrier loading station 103, and the substrate 122 is transferred from the substrate carrier 110 with its first surface facing down onto the surface of the pedestal 152. Typically, polishing the second surface 122b of the substrate 122 involves reversing the orientation of the substrate 122 or flipping the substrate 122 so that its second surface 122b faces downward relative to the pedestal 152. For example, the substrate 122 may be flipped over so that its first surface 122a faces toward the substrate carrier 110 and its second surface 122b contacts the pedestal 152. After the substrate 122 is flipped over, the substrate 122 is loaded into the substrate carrier 110 with its second surface facing down, so that its second surface 122b can be polished at one or more of the polishing stations 100a-100c. A method for reversing the orientation of the substrate 122, i.e., flipping the substrate 122, to facilitate sequential single-sided polishing of the first surface 122a and the second surface 122b is described in FIG.

[0028] 2A is a schematic isometric view of a multi-station polishing system 101, according to one embodiment, further illustrating a substrate handling system 200 that may be used to perform the methods described herein. As shown in FIG. 2A, the substrate handling system 200 generally includes a basin 202, a substrate handler assembly 230, and an alignment station 260. The basin 202 is characterized by walls 204 and a base 206 that define a substrate holding area 208 that is sized to accommodate a plurality of substrate transfer containers, e.g., cassettes 220. During use, the basin 202 typically contains a fluid 210, such as deionized water, and one or more cassettes 220 disposed within the substrate holding area 208 are submerged in the fluid 210. Here, fluid 210 is used to keep the substrate to be polished and the polished substrate wet between processing steps and to prevent the polishing fluid from drying out on the substrate before the substrate can be removed for post-CMP cleaning in a stand-alone post-CMP cleaning system (not shown). One or more cassettes 220 are aligned along a first longitudinal axis 212 of basin 202, where each cassette 220 is configured to hold multiple substrates 122 for processing in polishing system 101. For example, for a CMP system configured to polish 200 mm diameter substrates, each cassette 220 is typically configured to hold approximately 25 substrates.

[0029] The substrate handler assembly 230 includes an overhead track 232 disposed above the basin 202. Here, the overhead track 232 is oriented along a second axis 234 that is substantially parallel to the first axis 212 of the basin 202. In one or more embodiments, the overhead track 232 can be oriented horizontally, i.e., the second axis 234 is perpendicular to the direction of gravity. The substrate handler assembly 230 further includes an arm 236 disposed at least partially within a housing 238, where the housing 238 guides the arm 236, which is movable in the Z direction. For example, here, the arm 236 can move toward and away from the basin 202 along a third axis 240, where the third axis 240 is perpendicular to the second axis 234 of the overhead track 232. The arm 236 may extend relative to the housing 238 along a third axis 240 toward and away from the basin 202. In one or more embodiments, the arm 236 may be oriented vertically, i.e., parallel to the direction of gravity.

[0030] Here, the substrate handling system 200 further includes an end effector 242 coupled to a first end or lower end of the arm 236 by a wrist assembly 244. The substrate handling system 200 further includes a blade mount 243 and a rotational actuator 245 coupled between the end effector 242 and the wrist assembly 244. In one embodiment, the end effector 242 is a vacuum blade and has a port 246 formed in a substrate handling surface, here a first surface 242a thereof. The port 246 is fluidly coupled to a low-pressure pump (not shown) for applying vacuum pressure through the port 246. The vacuum pressure is used to engage the surface of the substrate 122 when the substrate handling surface, here the first surface 242a thereof, of the end effector 242 is brought close to or into contact with the surface of the substrate 122. For example, the end effector 242 can be lowered into the substrate holding area 208 and positioned adjacent to a substrate 122 held in one of the cassettes 220. In this position, vacuum pressure can be applied to engage the surface of the substrate 122 with the first side 242a of the end effector 242. Typically, the substrate 122 is disposed in a substantially vertical orientation within the cassette 220 when the cassette 220 is disposed in the basin 202, where substantially vertical is within about 20° from the direction of gravity. The first side 242a of the end effector 242 is typically parallel to the surface of the substrate 122, facilitating vacuum engagement therebetween. Thus, when the arm 236 is lifted upward and away from the cassette 220, the end effector 242 and the substrate 122 vacuum-engaged therewith are disposed in a substantially vertical orientation. Here, the wrist assembly 244, alone or in combination with the arm 236, provides at least one degree of motion to the end effector 242. This degree of movement is in addition to the vertical translation (described above) provided by arm 236 as it extends toward or away from basin 202, or the rotation (described below) of arm 236 provided by second actuator 252. At least one degree of movement is shown schematically in FIG. 2B.

[0031] 2B illustrates the degrees of movement used to move the end effector 242 from a vertical or substantially vertical orientation to a horizontal orientation. The vertical or substantially vertical orientation is used to transfer the substrate 122 to and from the cassette 220 and / or to and from the substrate alignment station 260. The horizontal orientation is used to place or remove the substrate 122 from the pedestal 152. For example, in FIG. 2B , the wrist assembly 244 is configured to move the end effector 242 about a fourth axis 248, thereby moving the substrate 122 secured to the end effector 242 between a first position 249 a and a second position 249 b, where the fourth axis 248 is orthogonal to the third axis 240 of the arm 236. In one or more embodiments, the fourth axis 248 may be oriented horizontally. In the first position 249a, the first side 242a of the end effector 242 is parallel to the first axis 212 of the basin 202 and / or the second axis 234 of the catenary track 232. In the second position 249b, the first side 242a of the end effector 242 is parallel to the third axis 240 of the arm 236, and the end effector 242 extends from the arm 236 towards the basin 202. In the second position 249b, the end effector 242 is positioned to lower into the basin 202 and vacuum engage the substrate 122 as described above.

[0032] Here, the rotational actuator 245, alone or in combination with the blade mount 243, provides at least one degree of motion to the end effector 242. This degree of motion is in addition to the vertical translation provided by the arm 236 as it extends toward or away from the basin 202 (discussed above), or the rotation of the arm 236 provided by the second actuator 252 (discussed below), or the movement of the end effector 242 about the fourth axis 248 provided by the wrist assembly 244 (discussed above). The at least one degree of motion is shown schematically in Figures 2C-2D, which illustrate the degrees of motion used to rotate or pivot the end effector 242 about the fifth axis 253 between a first orientation 251a shown in Figure 2C and a second orientation 251b shown in Figure 2D. Here, the fifth axis 253 is orthogonal to the fourth axis 248 of the wrist assembly 244. In one or more embodiments, the fifth axis 253 can be oriented vertically. Here, the rotational actuator 245 is configured to rotate the end effector 242 approximately 180 degrees about the fifth axis 253, thereby reversing the orientation of the first side 242a and the second side 242b of the end effector. For example, in the first orientation 251a, the first side 242a of the end effector faces the negative X direction, and the second side 242b of the end effector faces the positive X direction. However, in the second orientation 251b, the orientation of the end effector 242 is reversed, such that the first side 242a of the end effector faces the positive X direction, and the second side 242b of the end effector faces the negative X direction. In some other embodiments, the rotational actuator 245 can be configured to rotate or pivot the end effector 242 greater than about 180 degrees, such as between about 180 degrees and about 360 degrees, about the fifth axis 253. In some embodiments, the rotational actuator 245 can rotate or pivot the end effector 242 clockwise, counterclockwise, or both.

[0033] Here, the substrate handler assembly 230 further includes a first actuator 250 for moving the arm 236 along the overhead track 232. Typically, the substrate handler assembly 230 includes a second actuator 252, such as a drive assembly, for rotating the arm 236 about a third axis 240 to facilitate depositing the substrate 122 on the pedestal 152 of the substrate carrier loading station 103. In some embodiments, the second actuator 252 is connected to the first actuator 250 such that the second actuator 252 moves with the arm 236 along the overhead track 232.

[0034] The alignment station 260 is positioned within the basin 202 along the first axis 212 in alignment with the plurality of cassettes 220. The alignment station 260 is positioned and oriented to receive the substrate 122 from the end effector 242 when the end effector 242, and thereby the substrate 122, is positioned at the second position 249b. Here, the alignment station 260 is positioned within the substrate holding area 208 while being submerged in the fluid 210. Alternatively, the alignment station 260 may be positioned outside the substrate holding area 208. The alignment station 260 is used to temporarily hold the substrate 122 to facilitate the method 400 of FIG. 4 . For example, here, the alignment station 260 is used to assist in reversing or flipping the substrate between polishing the first surface 122a and polishing the second surface 122b. Reversing the orientation of a substrate or flipping a substrate typically involves placing the substrate in the alignment station 260 using the end effector 242 positioned in a first orientation 251a, moving the first surface 122a or the second surface 122b of the substrate 122 away from the end effector 242, rotating or pivoting the end effector 242 180 degrees about the fifth axis 253 to position the end effector in a second orientation, and then re-engaging the opposite surface (122a or 122b) of the substrate 122 with the end effector 242.

[0035] FIG. 3 is a schematic cross-sectional side view of a substrate alignment station 260 that can be used with the substrate handling system 200 of FIG. 2 , according to one embodiment. As shown in FIG. 3 , the alignment station 260 includes a frame 262 having an end flange 264. The frame 262 is shaped to support a substrate in an upright and / or substantially vertical orientation. The frame 262 is closed at its bottom end to support the substrate 122. The frame 262 is open at its top end to allow the substrate 122 to be inserted into and removed from the frame 262 from above. The end flange 264 surrounds the outer edge of the frame 262. It will be appreciated that the end flange 264 is configured to support the substrate 122 in an upright orientation without actually gripping the substrate 122. Thus, the end flange 264 is configured to support the edge of the substrate 122. Alternatively, the frame 262 may include a slot at its bottom end for receiving the substrate 122, and the end flange 264 may be omitted. In some other embodiments, the frame 262 and / or the end flange 264 may be shorter, for example, enclosing about three-quarters or less of the substrate 122, about half or less of the substrate 122, or about one-quarter or less of the substrate 122. In some embodiments, the frame 262 may be attached to a base 266 to attach the alignment station 260 to the substrate handling system 200 (e.g., in the substrate holding area 208).

[0036] FIG. 4 illustrates a method 400 for processing a substrate 122, according to one embodiment. FIGS. 5A-5E are used to explain aspects of the method 400 of FIG. 4, according to one embodiment. In some embodiments, one or more operations of the method 400 are stored as instructions in a computer-readable medium of the system controller 136. The method 400 generally includes polishing a first surface 122a of the substrate 122, reversing the orientation of the substrate 122 using the substrate handling system 200, i.e., flipping the substrate 122 over, and polishing a second surface 122b of the substrate 122. Advantageously, the method 400 is performed without removing the substrate 122 from the polishing system 101.

[0037] In operation 402, the method 400 includes pressing a first surface 122a of a substrate 122 against one of a plurality of polishing pads 106, the plurality of polishing pads 106 being mounted on corresponding polishing platens of a plurality of rotatable polishing platens 102. Pressing the first surface 122a of the substrate 122 against the polishing pad 106 is shown in FIG. 5A, where during the pressing, the substrate carrier 110 engages the second (opposite) surface 122b of the substrate 122, e.g., the second surface 122b contacting the film 117.

[0038] In operation 404, the method 400 includes transferring the substrate 122 from the substrate carrier loading station 103 to a substrate cassette 220 disposed within the substrate holding area 208 using a first side 242a of the end effector 242, where the first side 242a of the end effector 242 engages a second surface 122b of the substrate 122. The end effector 242 has a second side 242b facing opposite the first side 242a. Figure 5B illustrates the substrate 122 being transferred to the substrate cassette 220.

[0039] In operation 404, transferring the substrate 122 from the substrate carrier loading station 103 to the substrate cassette 220 typically involves engaging the end effector 242 with the substrate 122, which is placed on the pedestal 152. To place the substrate 122 on the pedestal, the substrate 122 is transferred from the substrate carrier 110 to the load cup 150 of the substrate carrier loading station 103 ( FIG. 1C ). Here, the substrate carrier 110 is moved about carriage axis C to position the substrate carrier 110 on the substrate carrier loading station 103. Either the pedestal 152 or the substrate carrier 110 is moved, or both are moved relative to each other, to transfer the substrate 122 therebetween. For example, here, the first surface 122 a of the substrate 122 is brought into contact with the pedestal 152, and the second surface 122 b of the substrate 122 is disengaged from the substrate carrier 110 to transfer the substrate 122 with the pedestal 152. Thereafter, to facilitate access to the substrate 122 by the end effector 242, one of the load cup 150 and the substrate carrier 110 is moved, or both are moved relative to each other, to create a gap between the substrate 122 and the substrate carrier 110.

[0040] Engaging the end effector 242 with the substrate 122 involves rotating the arm 236 about the third axis 240 to move the end effector 242, which is disposed in a substantially horizontal position, into the gap between the substrate carrier 110 and the pedestal 150 on which the substrate 122 is placed. Thereafter, either the end effector 242 or the pedestal 152 and the substrate 122 disposed thereon are moved relative to or toward each other, so that the second surface 122b of the substrate 122 contacts the first side 242a of the end effector 242.

[0041] After engaging the end effector 242 with the substrate 122, the arm 236 is rotated about the third axis 240 to move the end effector 242 and the engaged substrate 122 to a first position 249a (FIG. 2A shows the first position 249a with the substrate 122 not positioned on the end effector). In the first position 249a, the end effector 242 and the substrate 122 are positioned above the substrate holding area 208. Typically, the arm 236 is moved along the overhead track 232 to position the end effector 242, and thereby the engaged substrate 122, above the desired "open" position of the cassette 220, i.e., above the desired slot in the cassette 220 for transferring the substrate 122 thereto. Aligning the substrate 122 with the desired open position in the cassette 220 further includes moving the end effector 242 about the fourth axis 248 of the wrist assembly 244 to the second position 249b such that the end effector 242 and substrate 122 are lowered and positioned within the substrate holding area 208. Once the substrate 122 is aligned with the desired open position, the arm 236 extends along the third axis 240 toward the cassette 220 to position the substrate 122 therein. Once the substrate 122 is positioned within the desired opening in the cassette 220, the vacuum between the substrate 122 and the end effector 242 is released to disengage the substrate 122 from the end effector 242, and the arm 236 is retracted upward to remove the end effector 242 from the cassette.

[0042] In operation 406, the method 400 includes transferring the substrate 122 from the substrate cassette 220 to the substrate alignment station 260 using the first side 242a of the end effector 242, where the first surface 242a of the end effector 242 engages the second surface 122b of the substrate 122 during transfer.

[0043] In operation 406, transferring a substrate 122 from the substrate cassette 220 to the substrate alignment station 260 typically involves engaging an end effector 242 with the substrate 122 disposed within the substrate cassette 220 (see FIG. 5B ). Here, the first surface 122a of the substrate 122 is the device-side surface on which electronic devices are fabricated, and the second surface 122b is the non-device-side, or back-side, surface. Typically, when removing and returning the substrate 122 from and to the substrate cassette 220, the end effector 242 engages only the second surface 122b to avoid substrate handling-induced defects, such as scratches on the device-side surface. Reversing the orientation of the substrate 122 to facilitate sequential polishing of two substrate surfaces requires engaging the end effector 242 with each surface. Therefore, the non-device side surface, or second surface 122b, is typically polished first, thereby eliminating any surface damage caused to the first surface 122a by the end effector 242 during polishing of the first surface 122a.

[0044] Typically, the substrate cassette 220 is seated in the basin 202 so that the substrates 122 are tilted from the vertical in the -x direction by about 3° to about 5°. As shown in FIG. 5B , the first surface 122a of the substrate 122 faces the +x direction, and the second surface 122b of the substrate 122 faces the -x direction. Thus, the substrate 122 is picked up from the second surface 122b, which faces the -x direction. After engaging the second surface 122b of the substrate 122 in the substrate cassette 220, the arm 236 retracts along the third axis 240 away from the cassette 220. In some embodiments, the end effector 242 is rotated or pivoted about the fifth axis 253 using the rotational actuator 245 from the second orientation 251b ( FIG. 2D ) to the first orientation 251a ( FIG. 2C ). In some embodiments, before rotating the end effector 242 about the fifth axis 253, the end effector 242 is moved about the fourth axis 248 using the wrist assembly 244 to an intermediate position between the first position 249a and the second position 249b (FIG. 2B). At this point, the arm 236 is moved along the catenary track 232 so that the arm 236 is positioned above the substrate alignment station 260, and thus the substrate 122 is aligned with the substrate alignment station 260. The arm 236 is then extended along the third axis 240 toward the substrate alignment station 260, as shown in FIG. 5C, and the substrate 122 is positioned within the frame 262. In this position, the first side 242a of the end effector 242 faces the second surface 122b of the substrate 122. Once the base plate 122 is positioned within the frame 262 , the first side 242 a of the end effector 242 disengages from the base plate 122 and the arm 236 retracts upwardly toward the overhead track 232 .

[0045] In some embodiments, for example when the first surface 122a of the substrate 122 is polished, the substrate 122 is transferred from the substrate carrier loading station 103 to the substrate alignment station 260 using the first side 242a of the end effector 242 without transferring the substrate 122 to the substrate cassette 220.

[0046] In operation 408, the method 400 includes transferring the substrate 122 from the substrate alignment station 260 to the substrate carrier loading station 103 using the first side 242a of the end effector 242. Here, transferring the substrate 122 from the substrate alignment station 260 to the substrate carrier loading station 103 includes reorienting the end effector 242 with respect to the substrate 122 such that the first side 242a of the end effector 242 engages the first surface 122a of the substrate 122 during transfer. Figure 5D shows the end effector 242 positioned in a second orientation 251b (see Figure 2D), where the first side 242a engages the first surface 122a of the substrate 122. Engagement of the first side 242a of the end effector 242 with the first surface 122a of the substrate 122 facilitates placing the substrate 122 on the pedestal 152 (FIG. 1C) with the second surface 122b "face down."

[0047] Typically, after disengaging the end effector 242 from the substrate 122 in operation 406 (see FIG. 5C ), the arm 236 is moved away from the substrate alignment station 260 to create a gap between the end effector 242 and the substrate alignment station 260 and / or the substrate 122 disposed thereon. In some embodiments, the arm 236 can be retracted along the third axis 240 to create a gap between the end effector 242 and the substrate 122. In some embodiments, the end effector 242 is rotated or pivoted about the fifth axis 253 using the rotational actuator 245 from a first orientation 251 a ( FIG. 2C ) to a second orientation 251 b ( FIG. 2D ). In some other embodiments, changing the orientation of the end effector 242 includes rotating or pivoting the arm 236 about the third axis 240 to move the end effector 242 between a first orientation 251 a ( FIG. 2C ) and a second orientation 251 b ( FIG. 2D ). In some embodiments, the arm 236 is rotated or pivoted about the third axis 240 approximately 180 degrees, such that the first side 242 a of the end effector 242 faces away from the second surface 122 b of the substrate 122. In some embodiments, the arm 236 is rotated more than approximately 180 degrees, for example, from approximately 180 degrees to approximately 360 degrees. In some other embodiments, the arm 236 is rotated clockwise, counterclockwise, or both. In some embodiments, the second orientation of the arm 236 relative to the third axis 240 is opposite to the first orientation of the arm 236 relative to the third axis 240.

[0048] Here, operation 408 includes moving the arm 236 along the second axis 234 of the catenary track 232 until the end effector 242 passes over the substrate alignment station 260. In this position, the first side 242a of the end effector 242, which is disposed in the second orientation 251b, faces the first surface 122a of the substrate 122 (see FIG. 5D ). The arm 236 can be moved along the second axis 234 before, after, or simultaneously with reorienting the end effector from the first orientation 251a to the second orientation 251b. Operation 408 includes extending the arm 234 along the third axis 240 to position the end effector 242 for engagement with the first surface 122a of the substrate 122, and engaging the end effector 242 with the first surface 122a of the substrate 122.

[0049] From this position, transferring the substrate 122 to the substrate carrier loading station 103 involves performing operation 404 in reverse. Here, the first side 242a of the end effector 242 engages the first surface 122a of the substrate 122. Thus, when the end effector 242 is near the substrate carrier loading station 103, the second surface 122b of the substrate faces downward, such that the pedestal 152 of the load cup 150 engages the second surface 122b of the substrate 122 and the substrate carrier 110 engages the first surface 122a of the substrate 122. Thus, when the substrate carrier 110 moves about the carriage axis C to position the substrate carrier 110 over the polishing pad 106, the second surface 122b of the substrate 122 faces toward the polishing pad 106, as shown in FIG. 5E.

[0050] 5E is a schematic side view of the polishing station 100a illustrating operation 410. In operation 410, the method 400 includes pressing the second surface 122b of the substrate 122 against one of the polishing pads 106, where during the pressing, the substrate carrier 110 engages the first surface 122a of the substrate 122, e.g., the first surface 122a contacting the film 117.

[0051] Advantageously, method 400 can be used to flip the orientation of a SiC substrate within its substrate holder during sequential single-sided CMP processing of both sides of the substrate without removing the substrate from the processing system. Thus, method 400 desirably reduces and / or eliminates unwanted errors and delays during processing and the corresponding increase in substrate processing costs associated therewith.

[0052] 6A is an isometric view of an exemplary substrate handler assembly 630 that may replace the substrate handler assembly 200 of the multi-station polishing system shown in FIG. 2A. The substrate handler assembly 630 generally includes an overhead track 632, a housing 638, an end effector 642, and a first actuator 650 and a second actuator 652. The overhead track 632 includes a first rail 632a and a second rail 632b oriented along the second axis 234. A carriage assembly 639 is movable along the first rail 632a and the second rail 632b. The housing 638 is coupled to a base of the carriage assembly 639 and is movable therewith. The carriage assembly 639 includes a second actuator 652 for rotating the housing 638, in which an arm (not shown) is disposed, about the third axis 240. Here, a first actuator 650 is disposed between a first rail 632a and a second rail 632b of the overhead track 632. The first actuator 650 drives a belt 651 that moves along the first rail 632a. The belt 651 is coupled to the carriage assembly 639 to move the carriage assembly 639 along the first rail 632a and the second rail 632b. An end effector 642 is coupled to the housing 638 via an arm (not shown) and a wrist assembly 644.

[0053] FIG. 6B is an enlarged isometric view of a portion of FIG. 6A including an end effector 642. Here, the end effector 642 is a vacuum blade having a first side 642a (shown facing upward). A blade mount 643 couples the end effector 642 to a wrist assembly 644. The blade mount 643 includes a connector 643a for supplying vacuum pressure to a port (not shown) formed in a second side 642b of the end effector 642. A rotational actuator 645 is coupled between the blade mount 643 and the wrist assembly 644. The rotational actuator 645 drives rotation of the end effector 642 about a fifth axis 253 between a first orientation 251a and a second orientation 251b (FIGS. 2C-2D). The rotational actuator 645 includes multiple, here a pair of, pneumatic connectors 645a for driving rotation of the end effector 642 about the fifth axis 253.

[0054] Here, a mapper 647 is coupled to an arm that is oriented generally orthogonal relative to the end effector 642. Typically, the arm maintains the generally orthogonal orientation relative to the end effector 642 while both the arm and the end effector 642 move about the fourth axis 248. The mapper 647 includes one or more sensors 647a that can be used to track the plurality of substrates 122. The sensing functionality of the mapper 647 can be used in combination with the system controller 136 to perform one or more of the following: position each substrate 122 within one or more cassettes 220; number each substrate 122 within the one or more cassettes 220; store the position of each substrate 122 within the one or more cassettes 220 in a memory of the system controller 136; track each substrate 122 throughout processing; and return each substrate 122 to its respective position within the one or more cassettes 220. Here, the mapper 647 is integral with the rotary actuator 645, such that the rotary actuator 645 and the mapper 647 have a fixed relative position. In embodiments where the rotary actuator 645 and the mapper 647 are integrally formed, repeatability of the sensing of the mapper 647 is improved. In some other embodiments, the mapper 647 is coupled to the arm 638, the catenary track 632, or other components of the substrate handler assembly 630.

[0055] Figure 6C is an enlarged cross-sectional view of an exemplary rotary actuator 645 taken along section line 6-6' of Figure 6B. Figure 6D is an isometric view of the rotary actuator 645 of Figure 6C. The rotary actuator 645 includes a bearing housing 645b and a bearing 645c disposed therein. The bearing 645c is disposed between the bearing housing 645b and a bearing shaft 643b of the blade mount 643. The rotary actuator 645, to which the end effector 642 is coupled, is rotated in a first direction using a first pneumatic connector 645a of a pair of pneumatic connectors 645a. The rotary actuator 645 is rotated in a second, opposite direction using a second pneumatic connector 645a of the pair of pneumatic connectors 645a. The rotary actuator 645 includes one or more sensors 645d for sensing the position of the rotary actuator 645 and the end effector 642 attached thereto. In some embodiments, sensor 645d is a magnetic-based proximity sensor, such as a Hall Effect sensor. Sensor 645d is configured to indicate whether end effector 642 has rotated to a desired position, such as whether it has been flipped over. In some embodiments, a sudden drop or increase in air pressure in a pneumatic system connected to pair of connectors 645a indicates a problem with the rotation of rotational actuator 645.

[0056] While the above description is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, the scope of which is defined by the claims that follow.

Claims

1. 1. A substrate polishing system comprising: a substrate alignment station having a frame, the frame having a bottom and sides, the bottom configured to support a substrate by an edge of the substrate and the sides configured to support the substrate in an upright and substantially vertical position without gripping the substrate; a plurality of polishing stations each including a rotatable polishing platen; a substrate carrier loading station; a substrate handler including an end effector having a first side and a second side opposite the first side; 1. A non-transitory computer readable medium having stored thereon instructions for a substrate processing method, the method comprising, in sequence: (a) pressing a first surface of the substrate against one of a plurality of polishing pads, the plurality of polishing pads being mounted on a corresponding one of the plurality of rotatable polishing platens; (b) using the first side of the end effector to transfer the substrate from the substrate carrier loading station to the substrate alignment station and position the substrate in a substantially vertical position at the substrate alignment station; (c) transferring the substrate from the substrate alignment station to the substrate carrier loading station using the first side of the end effector; and (d) pressing the second surface of the substrate against one of the plurality of polishing pads; A substrate polishing system comprising:

2. 2. The system of claim 1, wherein the substrate handler further comprises an arm movable along an overhead track between the substrate alignment station and a substrate cassette positioned within a substrate holding area, the end effector being rotatably coupled to the arm.

3. 3. The system of claim 2, wherein the catenary track has a first axis parallel to a longitudinal axis of a basin defining the substrate holding area, and the end effector is rotatable about a second axis substantially perpendicular to the first axis.

4. (b) transferring the substrate from the substrate carrier loading station to the substrate alignment station includes engaging the end effector with the second surface of the substrate; and (c) transferring the substrate from the substrate alignment station to the substrate carrier loading station includes: rotating the end effector approximately 180 degrees about the second axis; After rotating, engaging the first side of the end effector with the first surface of the substrate; The system of claim 3 , comprising:

5. 5. The system of claim 4, wherein the substrate handler further comprises a wrist assembly configured to rotate the end effector relative to the arm about a third axis orthogonal to the first axis and the second axis.

6. The system of claim 4 , wherein rotating the end effector approximately 180 degrees about the second axis reverses the orientation of the first and second sides of the end effector.

7. the substrate carrier loading station comprises a load cup, and the method comprises: transferring the substrate from one of the polishing stations to the load cup, the first surface of the substrate facing downward relative to the load cup after the transfer; transferring the substrate from the load cup to one of the polishing stations, the second surface of the substrate facing downward relative to the load cup prior to the transfer; The system of claim 1 further comprising:

8. 1. A method of processing a substrate, comprising: (a) pressing a first surface of a substrate against one of a plurality of polishing pads, the plurality of polishing pads being mounted on a corresponding polishing platen of a plurality of rotatable polishing platens; (b) using a first side of an end effector to transfer the substrate from a substrate carrier loading station to a substrate alignment station and position the substrate in a substantially vertical position at the substrate alignment station; (c) transferring the substrate from the substrate alignment station to the substrate carrier loading station using the first side of the end effector; (d) pressing the second surface of the substrate against one of the plurality of polishing pads; Including, The method, wherein the substrate alignment station has a frame, the frame having a bottom and sides, the bottom configured to support the substrate by its edge surface, and the sides configured to support the substrate in an upright and substantially vertical position without gripping the substrate.

9. 9. The method of claim 8, wherein the end effector is rotatably coupled to an arm, the method further comprising moving the arm along an overhead track between the substrate alignment station and a substrate cassette disposed in a substrate holding area.

10. 10. The method of claim 9, wherein the arm moves along a first axis of the catenary track, the first axis being parallel to a longitudinal axis of a basin defining the substrate holding area, the method further comprising rotating the end effector about a second axis substantially perpendicular to the first axis.

11. (b) transferring the substrate from the substrate carrier loading station to the substrate alignment station includes engaging the end effector with the second surface of the substrate; and (c) transferring the substrate from the substrate alignment station to the substrate carrier loading station includes: rotating the end effector approximately 180 degrees about the second axis; After rotating, engaging the first side of the end effector with the first surface of the substrate; The method of claim 10, comprising:

12. 12. The method of claim 11, wherein the end effector is rotatably coupled to the arm by a wrist assembly configured to rotate the end effector about a third axis orthogonal to the first axis and the second axis.

13. 12. The method of claim 11, wherein the end effector has a second side opposite the first side, and rotating the end effector approximately 180 degrees about the second axis reverses the orientation of the first and second sides of the end effector.

14. the substrate carrier loading station comprises a load cup, and the method comprises: transferring the substrate from one of a plurality of polishing stations to the load cup, the first surface of the substrate facing downward relative to the load cup after the transfer; transferring the substrate from the load cup to one of the polishing stations, the second surface of the substrate facing downward relative to the load cup prior to the transfer; The method of claim 8 further comprising:

15. 1. A non-transitory computer readable medium having stored thereon instructions for a substrate processing method, the method comprising: (a) pressing a first surface of a substrate against one of a plurality of polishing pads, the plurality of polishing pads being mounted on a corresponding polishing platen of a plurality of rotatable polishing platens; (b) using a first side of an end effector to transfer the substrate from a substrate carrier loading station to a substrate alignment station and position the substrate in a substantially vertical position at the substrate alignment station; (c) transferring the substrate from the substrate alignment station to the substrate carrier loading station using the first side of the end effector; (d) pressing the second surface of the substrate against one of the plurality of polishing pads; Including, a substrate alignment station configured to support the substrate in an upright and substantially vertical position without gripping the substrate;

16. 16. The non-transitory computer-readable medium of claim 15, wherein the end effector is rotatably coupled to an arm, and the method further comprises moving the arm along an overhead track between the substrate alignment station and a substrate cassette disposed in a substrate holding area.

17. 17. The non-transitory computer-readable medium of claim 16, wherein the arm moves along a first axis of the catenary track, the first axis being parallel to a longitudinal axis of a basin defining the substrate holding area, and the method further comprising rotating the end effector about a second axis substantially orthogonal to the first axis.

18. (b) transferring the substrate from the substrate carrier loading station to the substrate alignment station includes engaging the end effector with the second surface of the substrate; and (c) transferring the substrate from the substrate alignment station to the substrate carrier loading station includes: rotating the end effector approximately 180 degrees about the second axis; After rotating, engaging the first side of the end effector with the first surface of the substrate; 20. The non-transitory computer-readable medium of claim 17, comprising:

19. 20. The non-transitory computer-readable medium of claim 18, wherein the end effector is rotatably coupled to the arm by a wrist assembly configured to rotate the end effector about a third axis orthogonal to the first axis and the second axis.

20. 20. The non-transitory computer-readable medium of claim 18, wherein the end effector has a second side opposite the first side, and wherein rotating the end effector approximately 180 degrees about the second axis reverses orientation of the first and second sides of the end effector.

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