System and method for controlling the surface profile of a wafer sliced by a wire saw

Abstract

A system and method for controlling the surface profile of a wafer sliced by a wire saw machine. The system and method are generally operable to change the nanotopology of a wafer sliced from an ingot by controlling the shape of the wafer. The shape of the wafer is changed, for example, by changing the temperature of a temperature-controlled fluid that is attached to a fixed bearing sidewall of the wire saw and circulates in fluid communication with the sidewall.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 365,921, filed Jun. 6, 2022, the disclosure of which is hereby incorporated by reference in its entirety.

[0002] This disclosure generally relates to wire saw machines used to slice ingots into wafers, and more particularly, to systems and methods for controlling the surface profile of semiconductor wafers sliced by wire saw machines.

Background Art

[0003] Semiconductor wafers, such as silicon wafers, are typically sliced from ingots using a wire saw. These ingots are often made of silicon, or other semiconductor or solar - grade materials. During operation, the ingot contacts a web of movable wires that are tensioned against bearings and rollers within the wire saw that slice the ingot into multiple wafers. Wafers cut with known saws may have surface defects that result in a nanoscale topology that deviates from a set standard. To improve the deviating nanoscale topology, such wafers may be subject to additional processing steps. These steps are time - consuming and costly.

[0004] Surface defects formed during the cutting of the ingot may occur, at least in part, due to thermal deformation of the components of the wire saw. The sidewalls supporting the rollers may deform or expand during the cutting process, causing the tensioned wire to move relatively. The cutting process can take several hours to complete, and as a result, the temperature rises over time, with the maximum temperature rise occurring during the first few hours of the cutting operation. By controlling the deformation of the sidewalls during the cutting operation, the surface defects of the cut wafers can be reduced.

[0005] Furthermore, in known wire saw machines, it is not possible to adjust the shape and / or warp of the surface of the wafer cut from the ingot by the machine. Therefore, there is a need for a more efficient and effective system for controlling the nanotopology of wafers cut by wire saw machines.

[0006] This section is intended to introduce the reader to various aspects of the technology that may be related to the various aspects of the present disclosure described and / or claimed below. This discussion is considered useful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, these descriptions should be read in this context and do not admit prior art. SUMMARY OF THE INVENTION

[0007] In one aspect, a system for controlling the surface profile of a wafer sliced from an ingot by a wire saw is disclosed. The system includes a wire saw base including a fixed bearing sidewall and a free bearing sidewall facing the fixed bearing sidewall. A wire guide assembly supports the wire, and the wire guide assembly includes a roller having a first end connected to the fixed bearing sidewall and a second end supported by the free bearing sidewall. The wire guide rotates on the bearing, and a thermal deformation of the fixed bearing sidewall from a first state to a second state corresponds to a change in the cut surface profile of the cut wafer from a first cut surface profile to a second cut surface profile. A temperature adjustment system is attached to the fixed bearing sidewall to control the thermal deformation of the fixed bearing sidewall. A control system for controlling the temperature of the fixed bearing sidewall includes a temperature sensor for measuring the temperature of the fixed bearing sidewall. A processor is connected to the temperature adjustment system and the control system, and the processor is configured to control the temperature of the fixed bearing sidewall to a desired temperature by operating the temperature adjustment system.

[0008] Another aspect is a system for controlling the cut surface profile of a wafer cut from an ingot by a wire saw. This system includes a temperature control system attached to the fixed bearing side wall of the wire saw base to control the thermal deformation of the fixed bearing side wall. The control system for controlling the temperature of the fixed bearing side wall includes a temperature sensor for measuring the temperature of the fixed bearing side wall and a displacement sensor for measuring the thermal deformation of the fixed bearing wall. The processor is connected to the temperature control system and the control system, and the processor is configured to control the temperature of the fixed bearing side wall to a desired temperature by operating the temperature control system.

[0009] In yet another aspect, a method of slicing an ingot into wafers using a wire saw is disclosed. This method receives an input from a user, the input including a desired wafer surface profile corresponding to a temperature set point of the fixed bearing side wall of the wire saw base, operates a temperature control system attached to the fixed bearing side wall to control the thermal deformation of the fixed bearing side wall, where the thermal deformation of the fixed bearing side wall corresponds to the desired wafer surface profile, starts a slicing operation such that a wire supported by a wire guide assembly cuts the wafer from the ingot, the wire guide assembly including a roller having a first end connected to the fixed bearing side wall and a second end supported by the free bearing side wall of the wire saw base, the wire guide rotating on the bearing, and the thermal deformation of the fixed bearing side wall from a first state to a second state corresponding to a change in the cut surface profile of the cut wafer from a first cut surface profile to a second cut surface profile.

[0010] There are various improvements to the features described in connection with the aspects above. Similarly, further features may be incorporated into the aspects above. These improvements and additional features may exist individually or in any combination. For example, the various features described later in connection with any of the illustrated embodiments may be incorporated into any of the aspects above of the present disclosure, either alone or in any combination.

Brief Description of the Drawings

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[0012] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

Best Mode for Carrying Out the Invention

[0013] Referring to the drawings, an example of a system for controlling the surface profile of a wafer cut from an ingot 102 by a wire saw machine 103 is shown in FIG. 1 and is generally designated by 100. As used herein, the term "surface profile" or "wafer surface profile" refers to both the nanotopology and the shape of the surface of the wafer.

[0014] The systems and methods described herein are generally capable of controlling the shape of a wafer, i.e., the nanotopology, by controlling the shape of the wafer sliced from an ingot. The shape of the wafer may be controlled by controlling the temperature of the sidewall of the wire saw to which the bearing is attached. The bearing supports the wire guide of the saw. The temperature of at least one wall of the wire saw base is controlled by a temperature control system attached to the fixed bearing sidewall or both sidewalls of the wire saw bar to control the thermal deformation of the sidewall. Similar to the deformation of the sidewall required to produce a wafer having a desired shape and / or nanotopology, different feedback systems may be used to determine the temperature of the sidewall, but such a feedback system is not essential. Nanotopology is defined as the deviation of the wafer surface within a spatial wavelength of about 0.2 mm to about 20 mm. This spatial wavelength corresponds very closely to the nanometer-scale surface features of a processed semiconductor (e.g., silicon) wafer. The foregoing definition was proposed by SEMI (Semiconductor Equipment and Materials International), a worldwide industry group in the semiconductor industry (SEMI Document 3089). Nanotopology measures the deviation in the height direction of one side of the wafer and does not consider the thickness variation of the wafer as in conventional flatness measurements. Several measurement methods have been developed to detect and record such surface variations. For example, very small surface variations can be detected by measuring the deviation of the reflected light from the incident light. These methods are used to measure the peak-to-valley (PV) variation within the wavelength. Nanotopology can be predicted or estimated based on the measurement of the surface of the wafer after slicing and before polishing.

[0015] The wire saw 103 (i.e., the wire saw machine) is of the type used to slice (i.e., cut or saw) an ingot 102 into wafers with a web of wire 104. The ingot 102 is connected to a bond beam 101, and the bond beam 101 is connected to a clamping rail 105. The clamping rail 105 is connected to the wire saw 103. The web of wire 104 (best shown in FIG. 2 and only one wire is shown in the end view of FIG. 3) moves along a circumferential path around three wire guides 106 when slicing the ingot 102. The number of wires 104 shown in FIG. 2 has been greatly reduced for clarity, and their spacing has likewise been greatly exaggerated for clarity. One or more wire guides 106 may be connected to a drive source to rotate the guide and rotate the web of wire 104.

[0016] In an exemplary embodiment, the wire saw 103 is used to slice an ingot 102 made of a semiconductor material (e.g., silicon) or a photovoltaic material. The wire saw 103 may also be used to slice ingots of other materials into wafers.

[0017] The wire guide 106 has opposing ends 108, 110, and each end is connected by a bearing 114 to a frame 112 of the wire saw 103 (only a part of which is shown in FIG. 2). The frame 112 includes a fixed bearing side wall 180 and the opposite side free bearing side wall 182 thereof.

[0018] Each bearing 114 of the fixed bearing side wall 180 has a rotating race 116 connected to respective ends 108 of the wire guides 106 and a fixed race 118 connected to the fixed bearing side wall 180. The rotating race 116 is best shown in FIG. 3. The rotating race 116 rotates when the wire guide 106 to which the rotating race 116 is connected rotates. Similarly, the fixed race 118 hardly moves even when the rotating race 116 and the wire guide 106 rotate. In the exemplary embodiment, the bearing 114 is a typical roller bearing, but in other embodiments, it may be other suitable types of bearings (e.g., roller bearings).

[0019] As shown in FIG. 4, the frame 112 may thermally deform during the cutting process. The thermal deformation of the frame 112 changes the surface profile and causes defects on the surface of the cut ingot. Although the wire guide 106 is connected to the fixed bearing side wall 180, it is movable relative to the free bearing side wall 182, so the movement of the wire guide 106 due to the thermal deformation of the free bearing side wall 182 is small. In other words, the first state is defined by the frame 112 without thermal deformation and the side walls (180, 182), and the second state is defined by the frame 112 under the thermal deformation of the fixed bearing side wall 180. The ingot cut in the first state may have a different surface profile from the ingot cut in the second state. As will be described in more detail below, a temperature control system 200 may be attached to the fixed bearing side wall 180 to control or reduce the thermal deformation of the fixed bearing side wall 180 by adjusting the temperature of the fixed bearing side wall 180. In some embodiments, the temperature control system 200 may be attached to the free bearing side wall 182 to adjust the temperature of the free bearing side wall 182. The embodiments of the temperature control system 200 described below may be attached to either or both of the fixed bearing side wall 180 and the free bearing side wall 182.

[0020] The main function of the temperature control system 200 is to reduce the thermal expansion, and thus the deflection, of the fixed bearing sidewall 180. In some embodiments, however, the temperature control system 200 may be configured to selectively increase the temperature of the fixed bearing sidewall 180, as will be described in more detail below. Since the temperature control system 200 can selectively thermally deform any wall, variations in the surface profile caused by external uncontrolled causes can be corrected by the operation of the temperature control system 200.

[0021] FIG. 5 is a side view of the heat exchanger 210 of the temperature control system 200 disposed on the inner surface 202 of the fixed bearing sidewall 180. FIG. 6 is a front view of the heat exchanger 210 disposed on the inner surface The heat exchanger 210 may be disposed in the vicinity of the region most susceptible to the effects of thermal deformation, and the heat exchanger 210 may be connected to more heat exchangers 210 on the inner surface 202. The heat exchanger 210 is preferably a Peltier cooler, a thermoelectric cooler module, or a solid state heat pump. In some embodiments, the heat exchanger 210 includes a highly conductive thermal plate in contact with the inner surface 202 and a reservoir 206 adjacent to the thermal plate. The reservoir 206 can pass fluid therethrough to facilitate heat transfer from the thermal plate to the inner surface 202. In some embodiments, the fluid conduit 212 may connect a plurality of heat exchangers 210 to an external reservoir 206 (not shown) that defines a fluid circuit. In some embodiments, the fluid circuit includes a valve or pump connected to a processor, as will be described in more detail below. In some embodiments, the heat exchanger 210 is a cooling jacket.

[0022] The heat exchanger 210 may be retrofitted to an existing frame 112. As an example, the heat exchanger 210 may be attached to the inner surface 202 of the fixed bearing sidewall 180 and may be connected to an external reservoir 206 and a valve or pump. In some embodiments, the inner surface 202 of the fixed bearing sidewall 180 may include a slot sized to receive the heat exchanger 210 such that the heat exchanger 210 is substantially flush with the inner surface 202 of the fixed bearing sidewall 180, reducing the installation area of the heat exchanger 210.

[0023] Figures 7-10B illustrate embodiments of the fluid passage 220 of the temperature control system 200. Figures 7 and 8 are respectively a side view and a front view of an embodiment of the temperature control system 200 in which the fluid flow path 220 is Inside (or within) the fixed bearing wall 180 therein. Figure 9 is a side view of an embodiment of the temperature control system 200 in which the fluid flow path 220 is outside the fixed bearing side wall 180. In the embodiment shown in Figure 9, the fluid flow path 220 is Disposed on the inner surface 202 of the fixed bearing sidewall 180 also well (shown in Figure 10A), the fluid flow path 220 is Of the fixed bearing sidewall 180 outer surface 203 Disposed thereon may also be (shown in Figure 10B) .

[0024] As best shown in FIG. 8, the fluid flow path 220 may be inside the fixed bearing wall 180 or may be embedded within the fixed bearing wall 180. As best shown in FIG. 10A, the fluid passage 220 may be disposed on the inner surface 202 of the fixed bearing sidewall 180 and be directed toward the wire guide 106. As best shown in FIG. 10B, the fluid passage 220 may be disposed on the outer surface 203 of the fixed bearing sidewall 180, and the outer surface 203 faces the inner surface 202.

[0025] The fluid flow path 220 may be disposed near the region most susceptible to the effects of thermal deformation. As best shown in FIG. 7, in some embodiments, the fluid flow path 220 may travel in a series or parallel path. As best shown in FIG. 9, the fluid flow path 220 may include a single flow path. The fluid flow path 220 may be connected to an external reservoir 206 (not shown) that defines a fluid circuit. In some embodiments, the fluid circuit includes a valve or pump connected to a processor, as will be described in further detail below.

[0026] The fluid flow path 220 may be retrofitted to an existing frame 112. For example, the fluid flow path 220 may be attached to the inner surface 202 of the fixed bearing side wall 180 and connected to an external reservoir 206 and a valve or pump, as shown in FIGS. 9 and 10. In some embodiments, the inner surface 202 of the fixed bearing side wall 180 may include a slot sized to receive the fluid passage 220 such that the fluid passage 220 is substantially flush with the inner surface 202 of the fixed bearing side wall 180, reducing the installation area of the fluid passage 220.

[0027] The temperature control fluid (alternatively referred to as "fluid") is thermally connected to the temperature control system 200 such that the fluid contacts at least a portion of the fixed bearing side wall 180.

[0028] In an exemplary embodiment, the fluid conduit 212 receives fresh fluid from the reservoir 206. The fluid conduit 212 may be a pipe, a hose, or other suitable structure (not shown).

[0029] The displacement sensor 130 (broadly referred to as a "sensor") is disposed adjacent to the rotating race 116 to measure the movement and / or axial displacement of the race. Similarly, another displacement sensor 132 may be disposed adjacent to the stationary race 118 to measure the displacement of the race. In other embodiments, one of these sensors 130, 132 may be omitted. In an exemplary embodiment, these sensors 130, 132 are non-contact sensors that measure the axial displacement of the corresponding races 116, 118, respectively. In other embodiments, the sensors 130, 132 may have different configurations and / or arrangements to measure different types of movement of the bearing 114. The sensors 130, 132 communicate with a processor 140 (described in detail below) via any suitable communication system (e.g., wired and / or wireless networks).

[0030] Only one of each of the sensors 130, 132 is shown in the figure for clarity, but in an exemplary embodiment, each race of each bearing 114 that is thermally connected to the fluid is provided with a plurality of such sensors. In other embodiments, the sensors 130, 132 may be arranged adjacent to different bearings 114 or portions thereof to measure displacement of the respective bearing or a portion thereof.

[0031] The temperature sensors are arranged to be thermally connected to the fluid to measure the temperature of the fluid. In an exemplary embodiment, the temperature sensor 134 is arranged adjacent to the rotating race 116, and the temperature sensor 136 is arranged adjacent to the fixed race 118. Accordingly, the temperature sensors 134, 136 are arranged adjacent to each race that is thermally connected to the fluid that is in turn thermally connected to the corresponding race. Since the fluid at these locations is thermally connected to the corresponding races 116, 118 respectively, the temperature of the fluid indicates the temperature of the race. In an exemplary embodiment, it is assumed that the temperature of the fluid adjacent to each of the races 116, 118 is generally equal to the temperature of the race. In other embodiments, this may not be the case, and the temperature of the fluid adjacent to the races 116, 118 may be different from the temperature of the race. A large flow rate of fluid is applied to the system so that the temperature of the fluid is maintained at an equal value at every location of each of the races 116, 118. If the flow rate is low, a temperature difference will occur between the inlet and the outlet of the system due to the heat absorbed at every location of the temperature control system 200.

[0032] The temperature sensors 134, 136 are communicatively connected to a processor 140 (details will be described later) by any suitable communication system (e.g., wired and / or wireless network). The processor, schematically shown in FIGS. 2 and 3 and generally designated by reference numeral 140, is communicatively connected to the temperature sensors 134, 136, the displacement sensors 130, 132, and the temperature control system 200. Generally, as will be described in more detail below, the processor 140 is configured to receive input from a user that specifies a desired wafer nanotopology profile or shape of a wafer sliced from an ingot. Alternatively, the processor 140 is configured to maintain the temperature at a set level to suppress deformation. Based on this input and the measured temperature of the fluid, the processor 140 transmits instructions to the temperature control system 200 to control (i.e., adjust, change or vary) the temperature of the fluid.

[0033] The flow rate is generally kept constant. The temperature of the fluid may be controlled by operating a heater or cooler (not shown) connected to the reservoir 206. The reservoir 206 has a sufficient volume such that the fluid circulating within the reservoir 206 is uniformly heated or cooled. Alternatively, liquid may be partially discharged from the reservoir 206 and fresh liquid may be added to the reservoir 206. The fresh fluid has a target temperature such that the reservoir 206 reaches the target temperature.

[0034] Due to the change in temperature of the fixed bearing sidewall 180, their displacements change, and the displacements of the wire guide 106 and the wire 104 also change. By controlling the displacements of the wire guide 106 and the wire 104, the surface shape of the wafer is controlled and the nanotopology of the surface is controlled.

[0035] Next, the operation of the processor 140 and the system 100 will be described in more detail. FIG. 11As shown, input device 160 may be communicatively coupled to processor 140 and used to receive input from a user specifying a desired wafer nanotopology or wafer shape. In other embodiments, processor 140 may receive this input from another computer system communicatively coupled to the processor.

[0036] Once this input is received by processor 140, the processor retrieves a recipe associated with the input from memory 150. Memory is described in more detail below. The recipe specifies a fixed bearing sidewall 180 associated with the recipe and / or a temperature setpoint of the temperature control fluid (i.e., a desired temperature). The recipe may include, in addition to or instead of, the temperature setpoint of the bearing and / or fluid, a displacement measurement of the bearing. By complying with the temperature and / or displacement measurements included in the recipe during cutting of ingot 102 by saw 103, generally a wafer having the same or similar characteristics as the input is obtained. The recipe may be interchangeably referred to as a "temperature profile", a "displacement profile", and / or a "temperature displacement profile". The processor sends a signal to activate a heater or cooler connected to reservoir 206.

[0037] Recipes may be created in a variety of ways. The specific temperature and / or displacement of each recipe may be determined empirically (i.e., during previous slicing operations) or empirically based on the material properties of bearing 114 (i.e., the coefficient of thermal expansion of the bearing material). In one embodiment, a recipe is created empirically by measuring the temperature of the fluid and bearing and / or the displacement of bearing 114 during slicing of ingot 102 and storing these measurements in memory 150. Thereafter, at least one surface of the wafer is measured and the shape and / or nanotopology characteristics of the wafer are stored in memory 150. Together with the temperature measurements and / or displacement measurements, these characteristics of the wafer form the recipe. As will be described below, this process may also be used to periodically update the recipe.

[0038] As described above, in an exemplary embodiment, the temperature of the bearing 114 is generally equivalent to the temperature of the temperature control fluid thermally connected to the bearing. The recipe is associated with the input such that use of the recipe by the system results in a wafer having the desired nanotopology and / or shape of the input sliced by the saw 103. These recipes are stored in a memory 150 communicatively connected to the processor 140. This memory 150 is any suitable form of computer-readable medium including a tangible storage device (e.g., hard disk drive, flash memory, optical drive, etc.).

[0039] These temperatures of the fluid cause a change in the position of the bearing 114 due to a change in the fixed bearing sidewall 180, such that the wafer sliced by the saw will have the desired nanotopology and / or shape. In an exemplary embodiment, the processor 140 obtains a temperature setpoint from the memory 150.

[0040] During operation, the saw 103 then begins slicing the ingot 102, and the processor 140 communicates commands to the temperature control system 200 to adjust the temperature of the fluid within the reservoir 206 based on the temperature setpoint and the measured temperature of the fluid. For example, the processor 140 may be connected to a heater or cooler (not shown). Once the temperature of the fluid equals the temperature of the temperature setpoint, the processor 140 sends an instruction to the heater or cooler to stop adjusting the temperature of the fluid. The processor 140 may continue to monitor the temperature measurements received from the temperature sensors 134, 136.

[0041] The controlled deformation of the fixed bearing sidewall 180 can be achieved by heating or cooling only one surface of the fixed bearing sidewall 180. The processor 140 may be connected to a pump or valve (204) to block or throttle the flow to the heat exchanger 210 on either the inner or outer surface of the fixed bearing sidewall 180.

[0042] This temperature change of the fixed bearing side wall 180 due to the change in the flow rate of the fluid changes their displacement and the displacement of the wire guide 106 and the wire 104. By controlling the displacement of the wire guide 106 and the wire 104, the shape of the wafer surface is controlled and the surface nanotopology is controlled.

[0043] The fluid may be chilled plant water at a relatively constant temperature (e.g., between about 5°C and about 10°C) obtained from the reservoir 206 or other source before being circulated in contact with the fixed bearing side wall 180. After contact with the bearing, the fluid is returned to the reservoir 206.

[0044] The temperature sensors 134, 136 are suitably used to measure the temperature of the fluid and / or the fixed bearing side wall 180. The temperature regulation system 200 described above may be used to control the temperature of the fluid, and the recipe may include a temperature set point for the bearing in addition to the temperature set point for the fluid.

[0045] The temperature set point may be determined based on the measured displacement of the fixed race 118 and / or the rotating race 116 of the bearing 114. For example, if the measured displacement of the fixed bearing side wall 180 is within the range of displacement specified by the recipe, the temperature set point may be adjusted so that the temperature of the fluid and / or the flow rate of the fluid thermally connected to the fixed bearing side wall 180 is not changed. The measured displacement of the fixed bearing side wall 180 may function as feedback to the processor to adjust the temperature set point.

[0046] By measuring the surface of the wafer sliced from the ingot, the recipe or process may be updated after the slicing operation. For example, the surface of the wafer may be measured and compared to the desired wafer shape and / or nanotopology profile input by the user. If the measured value of the surface is different from that input by the user, the recipe may be updated. This update may include adjusting the temperature setpoint of the fluid included in the recipe and / or the flow rate of the fluid. The update may also include adjusting the desired displacement of a portion of the fixed bearing sidewall 180.

[0047] In another embodiment, the displacement of the fixed bearing sidewall 180 is measured by displacement sensors 130, 132 at set intervals during the slicing of the ingot 102. Thereafter, the displacement measurement is received by the processor 140. In response to the received measurement, the processor 140 reduces or removes the displacement of the fixed bearing sidewall 180 and determines the temperature setpoint of the fixed bearing sidewall 180 necessary to improve the adverse effects that such displacement may have on the wafer.

[0048] Next, the processor 140 communicates an instruction to the temperature control system 200 to control the temperature of the fluid based at least in part on the measured displacement of the fixed bearing sidewall 180. In embodiments using the valve 204, the processor 140 may communicate an instruction to a heater or cooler to control the temperature of the fluid. These instructions to the valve 204 are also based at least in part on the measured displacement of the fixed bearing sidewall 180. As a result of the actions obtained from both the temperature control of the temperature control system 200 and the reservoir 206, the temperature of the fixed bearing sidewall 180 is controlled, and as a result, the displacement of the fixed bearing sidewall 180 is controlled. Further, the instructions generated by the processor 140 may be based at least in part on one or more recipes stored in the memory 150.

[0049] In one example, the processor 140 may determine a temperature set point based on the measured displacement of the fixed bearing sidewall 180 or a portion thereof. Next, the processor communicates an instruction to the temperature control system 200 to cool the fluid based on the measured displacement of the fixed bearing sidewall 180 or a portion thereof. Due to the temperature drop of the fluid, the temperature of the fixed bearing sidewall 180 decreases, and their displacement is reduced or eliminated. The temperature sensors 134, 136 may be used to measure the temperature of the fluid and / or the fixed bearing sidewall 180 and communicate these temperature measurements to the processor 140. These temperature measurements function as feedback to the processor 140.

[0050] In another embodiment, only the temperature of the fluid is controlled, and the displacement of the fixed bearing sidewall 180 is not measured during slicing of the ingot 102. In these embodiments, the temperature control system 200 controls the temperature of the fluid to control the temperature of the fixed bearing sidewall 180 according to the temperature set point. This temperature set point may be obtained from the recipe as described above. Alternatively, it may be received as an input from a user or another computer system to the system 100. The system 100 may, in some embodiments, measure the temperature of the fluid using the respective sensors 134, 136 and use the measurements as feedback for controlling the temperature control system 200.

[0051] A method of slicing an ingot into wafers using a wire saw is shown in FIG. 12. The method receives 302 an input from a user, the input including a desired wafer surface profile corresponding to a temperature set point of a fixed bearing sidewall of a wire saw frame, and operates 304 a temperature control system attached to the fixed bearing sidewall to control thermal deformation of the fixed bearing sidewall, where the thermal deformation of the fixed bearing sidewall corresponds to a desired wafer surface shape, and initiates 306 a slicing operation such that a wire supported by a wire guide assembly cuts a wafer from the ingot, the wire guide assembly including a roller having a first end connected to the fixed bearing sidewall and a second end supported by a free bearing sidewall of the wire saw frame, the wire guide rotating on the bearing, and the thermal deformation of the fixed bearing sidewall from a first state to a second state corresponding to a change in a first cut surface profile of a cut surface profile of the cut wafer to a second cut surface profile. In some embodiments, method 300 further includes maintaining 308 the temperature of the fixed bearing sidewall at a first desired temperature, the first desired temperature corresponding to a first cut surface profile of the cut wafer. In some embodiments, the method further includes raising 310 the temperature of the fixed bearing housing to a second desired temperature, the second desired temperature corresponding to a second cut surface profile of the cut wafer.

[0052] The method may also include lowering the temperature of the fixed bearing housing to a third desired temperature, the third desired temperature corresponding to a third cut surface profile of the cut wafer. The method may further include, by a processor, obtaining a wafer surface profile from a memory, the processor being configured to communicate instructions for controlling the temperature control system to a control system. In some embodiments, the method further includes operating a valve of the temperature control system for controlling the temperature of the fixed bearing sidewall.

[0053] The described system and method control the nanotopology and shape of wafers cut by the wire saw machine 103. It has been found that in conventional systems, the fixed bearing sidewall 180 or a part thereof may be displaced or moved during the slicing of the ingot 102. This displacement of the fixed bearing sidewall 180 may be kept relatively constant even during the slicing of the ingot 102 by the wire saw 103. However, the displacement of the rotating race 116 is readily apparent. This displacement of the bearing 114 causes displacement of the wire guide 106 and the wire 104 of the saw 103 due to the deformation of the fixed bearing sidewall 180. The displacement of the wire guide 106 and the wire 104 causes defects in the shape and / or nanotopology of the wafers sliced from the ingot 102. Entry marks and exit marks are one such type of defect. The displacement of the bearing 114 may be caused by a temperature change in the fixed bearing sidewall 180 and thus in the fluid that is thermally connected to the fixed bearing sidewall 180.

[0054] By controlling the temperature of the fluid in contact with the fixed bearing sidewall 180, the systems and methods described herein control the temperature of the fixed bearing sidewall 180. By controlling the temperature of the fixed bearing sidewall 180, the displacement of the fixed bearing sidewall 180 is controlled. Thus, the displacement of the fixed bearing sidewall 180 can be minimized or eliminated by controlling the temperature of the fixed bearing sidewall 180. By doing so, the displacement of the wire guide 106 and the wire 104 can also be minimized or eliminated. Therefore, defects in the shape and / or nanotopology of the wafers (e.g., entry marks or exit marks) can be reduced or eliminated. This reduction in defects improves the yield of the wafer manufacturing process. Further, the time of downstream processing steps (e.g., grinding) can be shortened or omitted, thus reducing the time and cost of wafer manufacturing.

[0055] The systems and methods also enable controlling the shape and / or nanotopology of the wafer, in addition to or instead of reducing or removing other defects (e.g., entry marks or exit marks). Accordingly, a user can input a desired shape and / or nanotopology profile of a wafer sliced from an ingot 102. A user may need wafers having different shapes and / or nanotopologies for various reasons.

[0056] When introducing elements of the present disclosure or embodiments of the present disclosure, the articles "a", "an", "the", and "said" are intended to mean that there is one or more of the elements. The terms "comprising", "including", and "having" are intended to be inclusive and mean that additional elements other than the listed elements may exist.

[0057] Since various modifications can be made without departing from the scope of the present disclosure, all matters included in the above description and shown in the accompanying drawings are intended to be interpreted as illustrative and not in a limiting sense.

Claims

1. A system for controlling the surface profile of a wafer sliced from an ingot by a wire saw, comprising: A wire saw base including a fixed bearing side wall and a free bearing side wall facing the fixed bearing side wall; A wire guide assembly for supporting a wire, the wire guide assembly including a roller having a first end connected to the fixed bearing side wall and a second end supported by the free bearing side wall, the wire guide rotating on the bearing, and a thermal deformation of the fixed bearing side wall from a first state to a second state corresponding to a change of a first cut surface profile of a cut surface of the cut wafer to a second cut surface profile; the wire guide assembly; A temperature control system attached to the fixed bearing side wall for controlling the thermal deformation of the fixed bearing side wall; A control system for controlling the temperature of the fixed bearing side wall, including a temperature sensor for measuring the temperature of the fixed bearing side wall; A processor connected to the temperature control system and the control system, the processor being configured to control the temperature of the fixed bearing side wall to a desired temperature by operating the temperature control system. A system comprising the above.

2. The system according to claim 1, wherein the processor is configured to maintain the temperature of the fixed bearing side wall at a first desired temperature, and the first desired temperature corresponds to the first cut surface profile of the cut wafer.

3. The system according to claim 1, wherein the processor is configured to raise the temperature of the fixed bearing housing to a second desired temperature, and the second desired temperature corresponds to the second cut surface profile of the cut wafer.

4. The system according to claim 1, wherein the processor is configured to lower the temperature of the fixed bearing housing to a third desired temperature, and the third desired temperature corresponds to the third cut surface profile of the cut wafer.

5. The control system further comprises a memory for storing temperature profiles, each temperature profile being associated with a cut surface profile and defining a temperature setpoint for the fixed bearing sidewall, the processor being configured to obtain the associated temperature setpoint from the memory, and the processor being configured to transmit instructions to the control system to control the temperature regulation system, the system according to claim 1.

6. The temperature regulation system includes a fluid flow path and a valve in fluid communication with the fluid flow path, the processor being connected to the valve, and the processor being configured to maintain the temperature of the fixed bearing sidewall at a desired temperature by actuating the valve, the system according to claim 1.

7. The fluid flow path is inside the fixed bearing sidewall, the system according to claim 6.

8. The fluid flow path is on the inner surface of the fixed bearing sidewall, the system according to claim 7.

9. The fluid flow path is on the outer surface of the fixed bearing sidewall, the system according to claim 6.

10. The temperature regulation system includes a heat exchanger, the processor being communicably connected to the heat exchanger, and the processor being configured to maintain the temperature of the fixed bearing sidewall at a desired temperature by operating the heat exchanger, the system according to claim 1.

11. The system according to claim 1 further includes a sensor connected to the fixed bearing sidewall for measuring the thermal displacement of the fixed bearing sidewall.

12. The control system is connected to the valve of the temperature regulation system to control the flow rate of the fluid of the temperature regulation system, the system according to claim 1.

13. A system for controlling the cut surface profile of a wafer cut from an ingot by a wire saw, the system comprising a temperature regulation system attached to a fixed bearing sidewall of a wire saw base for controlling the thermal deformation of the fixed bearing sidewall, and a control system for controlling the temperature of the fixed bearing sidewall, including a temperature sensor for measuring the temperature of the fixed bearing sidewall and a displacement sensor for measuring the thermal deformation of the fixed bearing sidewall. A processor that communicates with the temperature control system and the control system, wherein the processor is configured to control the temperature of the fixed bearing sidewall to a desired temperature by operating the temperature control system, the processor and A system comprising. **Claim 14** A method of slicing an ingot into wafers using a wire saw, wherein The method includes Receiving an input from a user, the input including a desired wafer surface profile corresponding to a temperature set point of a fixed bearing sidewall of a wire saw base, Operating a temperature control system attached to the fixed bearing sidewall to control thermal deformation of the fixed bearing sidewall, wherein the thermal deformation of the fixed bearing sidewall corresponds to the desired wafer surface profile, Initiating a slicing operation such that a wire supported by a wire guide assembly cuts a wafer from the ingot, the wire guide assembly including a roller having a first end connected to the fixed bearing sidewall and a second end supported by a free bearing sidewall of the wire saw base, the wire guide rotating on a bearing, and a thermal deformation of the fixed bearing sidewall from a first state to a second state corresponding to a change in a cut surface profile of the cut wafer from a first cut surface profile to a second cut surface profile A method comprising. **Claim 15** The method of claim 14, further comprising maintaining the temperature of the fixed bearing sidewall at a first desired temperature, the first desired temperature corresponding to the first cut surface profile of the cut wafer. **Claim 16** The method of claim 14, further comprising raising the temperature of the fixed bearing housing to a second desired temperature, the second desired temperature corresponding to the second cut surface profile of the cut wafer. **Claim 17** The method of claim 14, further comprising lowering the temperature of the fixed bearing housing to a third desired temperature, the third desired temperature corresponding to a third cut surface profile of the cut wafer. **Claim 18** The method of claim 14, wherein the wafer surface profile is stored in a memory connected to a processor, the processor is connected to the temperature control system, and each of the wafer surface profiles is associated with a temperature set point of the fixed bearing sidewall. **Claim 19** The method according to claim 18, further comprising obtaining, by the processor, a wafer surface profile from the memory, wherein the processor is configured to transmit instructions to a control system to control the temperature regulation system.

20. The method according to claim 14, further comprising operating a valve of the temperature regulation system for controlling the temperature of the fixed bearing side wall.

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