TWI567812B - Systems and methods for controlling surface profiles of wafers sliced in a wire saw - Google Patents

Description

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

The present invention relates generally to wire sawing machines for slicing an ingot into a wafer, and more particularly to systems and methods for controlling the surface profile of a sliced wafer in a wire saw.

Semiconductor wafers are typically formed by cutting an ingot with a wire saw. These ingots are typically made of tantalum or other semiconductor or solar grade materials. The ingot is connected to the structure of the wire saw by a joint beam and an ingot holder. The ingot is bonded to the joint beam by means of an adhesive, and the joint beam is then joined to the ingot holder by means of an adhesive. The ingot holder is coupled to the wire saw structure by any suitable joining system.

In operation, the ingot is contacted by one of the moving wires in the wire saw that slices the ingot into a plurality of wafers. The splice beam is then attached to a hoist and the wafer is dropped onto a truck.

Wafers cut by conventional saws can have surface defects that cause the wafer to have a nanotopology that deviates from the set standard. In order to improve the nano topology of the deviation, such wafers can be subjected to additional processing steps. These steps are time consuming and expensive. Moreover, conventional wire saws are inoperable to adjust the shape and/or warpage of the surface of the wafer being cut from the ingot by such machines. Therefore, there is a need for a more efficient and efficient system for controlling the nanotopology of a wafer being cut in a wire saw.

This section is intended to introduce the reader to various aspects of the techniques of the various aspects of the invention, which are set forth and/or claimed. It is believed that this The discussion helps to provide the reader with background information to facilitate a better understanding of one of the various aspects of the invention. Therefore, it is to be understood that such statements are to be understood as being in terms of

One aspect is a system for controlling the surface profile of a wafer sliced from an ingot in a wire saw, the wire saw comprising a wire guide of the support wire, the wire guide rotating on a bearing, and The fluid is in thermal communication with the bearing. The system includes: a memory for storing a temperature variation curve, each temperature variation curve being associated with a surface profile and defining a temperature set point of at least one of the fluid and the bearing; a control system a temperature sensor for measuring the temperature of at least one of the fluid and the bearing; and a processor communicatively coupled to the memory, the control system, and a temperature sensor configured to receive an input identifying a desired surface profile and extract an associated temperature set point from the memory, the processor configured to pass instructions to the control system The temperature of the bearing is controlled based at least in part on the temperature set point of the fluid and at least one of the bearings and the measured temperature.

Another aspect is a system for controlling the surface profile of a wafer cut from an ingot by a wire saw. The system includes: a wafer measurement sensor for measuring a surface of the wafer previously cut by the wire saw; a sensor disposed to measure support in the wire saw a displacement of a bearing of one of the wire guides; and a processor for determining a temperature set point, the processor being configured to determine the measured displacement and the previous cut based at least in part on the bearing One of the measured surfaces of the wafer to determine the temperature At a set point, the processor is communicatively coupled to the wafer metrology sensor and the sensor.

A further aspect is a system for controlling the surface profile of a wafer sliced from an ingot in a wire saw, the wire saw comprising a wire guide of the support wire, the wire guide rotating on a bearing, and The fluid is in thermal communication with the bearing. The system includes: a memory for storing a temperature variation curve, each temperature variation curve being associated with a surface profile and defining a temperature set point of the bearing; a valve for controlling the flow rate of the fluid; a temperature sensor for measuring the temperature of the bearing; and a processor communicatively coupled to the memory, the valve, and the temperature sensor, the processor configured to receive and identify a desired One of the surface profiles is input and an associated temperature set point is drawn from the memory, the processor being configured to pass an instruction to the valve to be based at least in part on the temperature set point of the bearing and the measured temperature This flow rate of the fluid is controlled.

Another aspect is a method for slicing a semiconductor or solar ingot into a wafer using a wire saw, the wire saw comprising a wire guide of the support wire, the wire guide rotating on a bearing, and a fluid The bearing is in thermal communication. The method includes: receiving an input from a user, the input including a desired wafer surface profile; selecting a temperature and displacement amount curve based on the input; initiating a slice operation; measuring a displacement of the bearing, measuring the At least one of a temperature of one of the bearings and a temperature of one of the fluids based at least in part on the measured displacement of the bearing, the selected temperature and displacement amount curve, and the at least one of the fluid and the bearing One of the measured temperatures determines a temperature set point; and controls the fluid and the bearing based on the temperature set point At least one of the temperatures.

A further aspect is a method for slicing an ingot into a wafer using a wire saw, the wire saw comprising a wire guide of the support wire, the wire guide rotating on a bearing, and a fluid is hot with the bearing Connected. The method includes receiving an input from a user, the input including a desired surface profile, selecting a prescription based on the desired surface profile, the prescription including defining a temperature magnitude curve of one of the fluid temperature set points; based on the selection The formulation controls a temperature of the fluid, wherein the temperature controlling the fluid controls the temperature of the bearing; and initiates a slicing operation.

A further aspect is a method for slicing an ingot into a wafer using a wire saw, the wire saw comprising a wire guide of the support wire, the wire guide rotating on a bearing, a fluid in thermal communication with the bearing And a valve is used to control the flow rate of the fluid. The method includes receiving an input from a user, the input including a desired surface profile, selecting a prescription based on the input, the prescription including at least one of a temperature variation curve and a displacement amount curve of the bearing; The selected prescription controls a flow rate of the fluid, wherein controlling the flow rate of the fluid controls the temperature of the bearing; and initiating a slice operation.

Another aspect is a method for controlling the surface profile of a wafer sliced from an ingot using a wire saw. The method includes measuring a surface of one of the wafers previously cut by the wire saw; measuring a displacement of one of the bearings of one of the wire guides supporting the wire saw, based at least in part on the amount of the bearing Determining the displacement and one of the measured surfaces of the previously cut wafer determines a temperature set point of the bearing; and controlling a temperature of one of the fluids in contact with the bearing based on the temperature set point, wherein The temperature control controls the The temperature of the bearing, and wherein the control of the temperature of the bearing controls the surface profile of the wafer sliced from the ingot by the wire saw.

Still another aspect is a method of controlling displacement of a bearing in a wire saw for slicing a semiconductor or solar ingot into a wafer, the wire saw comprising a wire guide of the support wire, the wire guide being in the bearing Rotating up and a fluid in thermal communication with the bearing. The method includes: measuring a displacement of the bearing; determining a temperature set point of the bearing based at least in part on the measured displacement of the bearing; and controlling a temperature of the fluid based on the temperature set point and based on the temperature At least one of a flow rate of the fluid at a set point, wherein the control of at least one of the temperature and the flow rate of the fluid controls the displacement of the bearing.

Yet another aspect is a method of controlling the displacement of a bearing in a wire saw that is used to slice an ingot into a wafer. The method includes: measuring a displacement of a bearing of a wire guide supporting a wire in the wire saw; determining a temperature set point based at least in part on the measured displacement of the bearing; and controlling and controlling the set point based on the temperature The bearing contacts a temperature of one of the fluids, wherein the control of the temperature of the fluid controls the displacement of the bearing.

Another aspect is a system for controlling the surface profile of a wafer cut from an ingot by a wire saw. The system includes: a sensor positioned to measure a displacement of a bearing supporting one of the wire guides of the wire in the wire saw; and a processor communicatively coupled to the sensor and Configuring to determine a temperature set point of the bearing, the processor being configured to determine the temperature set point based at least in part on the measured displacement of the bearing, wherein the temperature is used in controlling the temperature of the bearing Temperature set point control by the wire saw The surface profile of the wafer cut from the ingot.

Still another aspect is a system for controlling a nanotopology of a wafer sliced in a wire saw for slicing a semiconductor or solar ingot into a wafer, the wire saw comprising a wire guide of the support wire, The wire guide rotates on a bearing and a fluid is in thermal communication with the bearing. The system includes: a sensor positioned to measure displacement of the bearing of the wire guide; a processor communicatively coupled to the sensor and configured to determine for control A temperature set point is used in the temperature of the fluid, the processor being configured to determine the temperature set point based at least in part on the measured displacement of the bearing, wherein control of the temperature of the fluid controls the a displacement of the bearing, and wherein the control of the displacement of the bearing controls the nanotopology of the wafer cut from the ingot by the wire saw; and a memory communicatively coupled to the processor and configured Used to store this temperature set point.

Yet another aspect is a system for controlling a surface profile of a wafer sliced in a wire saw for slicing a semiconductor or solar ingot into a wafer, the wire saw comprising a wire guide of the support wire, the wire The guide rotates on a bearing and a fluid is in thermal communication with the bearing. The system includes: a sensor positioned to measure displacement of the bearing of the wire guide; a processor communicatively coupled to the sensor and configured to determine for control A temperature set point is used in one of the fluid flow rates, the processor being configured to determine the temperature set point based at least in part on the measured displacement of the bearing, and wherein controlling control of the flow rate of the fluid The displacement of the bearing, and wherein the control of the displacement of the bearing controls the surface profile of the wafer cut from the ingot by the wire saw; and a memory that is communicatively coupled To the processor and configured to store the temperature set point.

There are various improvements to the features described in relation to the above mentioned aspects. Further features may also be incorporated in the above mentioned aspects. Such improvements and additional features may exist individually or in any combination. For example, various features discussed below in relation to any one of the illustrated embodiments may be incorporated into any of the aspects set forth above, either individually or in any combination.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to the drawings, an exemplary system for controlling the surface profile of a wafer cut from an ingot 102 by a wire saw 103 is shown in FIG. 1 and generally indicated at 100. As used herein, the term "surface profile" or "wafer surface profile" refers to both the nanotopography and shape of the surface of a wafer.

The systems and methods described herein are generally operable to control the shape of the wafer sliced from an ingot and thus the nanotopology by controlling the shape of the wafer. The shape of the wafer can be controlled by controlling the temperature of the bearing that supports the wire guide of the saw. The temperature of the bearing is controlled by controlling the temperature of one of the temperature controlled fluids in fluid communication with the bearing and/or controlling the flow rate of the fluid. Different feedback systems can be used to determine the temperature of the fluid and/or bearings required to produce a wafer having a desired shape and/or nanotopology, but such feedback systems are not necessarily required. In addition, systems and methods can be used to store and retrieve the temperature and/or displacement curve that defines the fluid and/or bearing corresponding to the desired surface profile. Embodiments of the systems and methods described herein are operable to reduce or eliminate the formation of the surface of the wafer being cut in a wire saw machine In and/or exit tags.

The nanotopology has been defined as the deviation of a wafer surface over a spatial wavelength of from about 0.2 mm to about 20 mm. This spatial wavelength closely corresponds to the surface characteristics of the processed semiconductor wafer at the nanoscale. The foregoing definition has been proposed by the International Union of Semiconductor Equipment and Materials (SEMI) (Global Trade Association of the Semiconductor Industry (SEMI Document 3089)). As with conventional flat metrology, the nanotopology measures the façade deviation of one surface of the wafer and does not account for variations in wafer thickness. Several metrology methods have been developed to detect and record such surface changes. For example, the deviation of the measured light from the incident light allows for the detection of minimal surface variations. These methods are used to measure peak-to-valley (PV) changes in wavelengths. The nano topology can be predicted or estimated based on measurements made on its surface after the wafer has been sliced but before it is subjected to polishing.

The wire saw 103 (i.e., a wire saw) is of the type used to slice (i.e., cut or saw) the ingot 102 into a wafer by means of a mesh of wires 104. The ingot 102 is coupled to a joint beam 101 which in turn is coupled to a clamping rail 105. The clamping rail 105 is connected to the wire saw 103. When the ingot 102 is sliced, the wire 104 (best shown in Figure 2, showing only one of the lines in the end view of Figure 3) travels around the three wire guides 106 along a circuitous path. For the sake of clarity, the number of lines 104 shown in Figure 2 is drastically reduced, and the line spacing is also greatly magnified for clarity. One or more of the wire guides 106 can be coupled to a drive source to rotate the wire guides and in turn rotate the wire of the wire 104.

In an exemplary embodiment, the wire saw 103 is used to slice an ingot 102 made of a semiconductor material (eg, germanium) or a photovoltaic material. Wire saw 103 can also Used to slice ingots of other materials into wafers.

In this embodiment, the wire guide 106 has opposite ends 108, 110, each of which is coupled to one of the frames 112 of the wire saw 103 by a bearing 114 (only the frame is shown in Figure 2) Part of it). Each bearing 114 (only one of which is shown in the figures for clarity) has a rotating race 116 connected to one of the respective ends 108 of the wire guide 106 and a fixed race connected to the frame 112 118. The rotating race 116 is best seen in Figure 3. As the name implies, the rotating race 116 rotates as it is connected to the wire guide 106. Likewise, the fixed race 118 does not move significantly as the rotating race 116 and the wire guide 106 rotate. In the exemplary embodiment, bearing 114 is a typical ball bearing, but in other embodiments bearing 114 may be any other suitable type of bearing (eg, a roller bearing). A temperature controlled fluid (interchangeably referred to as "fluid") is in thermal communication with a bearing 114 that supports each wire guide 106 such that the fluid contacts at least a portion or structure of the bearing, which in turn contacts the bearing.

In an exemplary embodiment, each of the fixed races 118 has an inlet 120 for receiving fresh fluid from a heat exchanger 124 and an outlet 122 for discharging fluid from the race to one of the heat exchangers. Likewise, each rotating race 116 has an inlet 126 for receiving fresh fluid from heat exchanger 124 and an outlet 128 for discharging fluid from the race to one of the heat exchangers. The inlets 120, 126 and outlets 122, 128 are connected to the heat exchanger 124 by means of tubes, hoses or other suitable structures (not shown). For the sake of clarity, only one set of inlets 120, 126 and outlets 122, 128 of one bearing 114 are shown. It should be understood that other bearings have the same or similar configuration and/or number of inlets and outlets. In an exemplary embodiment, only the bearing 114 on the left side of the system 100 is movable and the bearing on the right side is immovable. Thus, in the exemplary embodiment, the bearing 114 on the left side of the system 100 is the only bearing that undergoes significant displacement and only the displacement of the bearings is adjustable. In various embodiments, this is not the case and the bearings 114 on both sides of the system are movable and/or their displacements are adjustable. Moreover, in certain embodiments, the non-movable (i.e., fixed) bearing may experience some degree of displacement during use of the saw and thus its position may be by a system similar or identical to the systems and methods described herein. And methods to control.

Moreover, in the exemplary embodiment, a single heat exchanger 124 (in general, a "control system") is used to control the temperature of the fluid, but in other embodiments, multiple heat exchangers may alternatively be used. For example, a single heat exchanger can be used to control the temperature of the fluid in contact with the rotating race 116 of all of the bearings 114, while another heat exchanger can be used to control the temperature of the fluid in contact with the fixed race 118. Heat exchanger 124 is of any suitable type and is operable to cool and/or heat the fluid. By controlling the temperature of the fluid, the heat exchanger is thus operable to control the temperature of the bearing 114 in thermal communication with the fluid.

A displacement sensor 130 (in other words, a "sensor") is disposed adjacent to the rotating race 116 for measuring the movement and/or axial displacement of the race. Likewise, another displacement sensor 132 can be placed adjacent to the fixed race 118 for measuring the displacement of the race. In other embodiments, one of the sensors 130, 132 may be omitted. In an exemplary embodiment, the sensors 130, 132 measure the axial displacement of the respective races 116, 118 and are non-contact Sensor. In other embodiments, the sensors 130, 132 can be configured and/or positioned differently to measure the movement of different types of bearings 114. The sensors 130, 132 are communicatively coupled to a processor 140 (discussed in greater detail below) by any suitable communication system (e.g., a wired and/or wireless network).

For clarity, only one of each of the sensors 130, 132 is shown in the figures, but each of the bearings 114 in thermal communication with the fluid in the exemplary embodiment has such sensors. In other embodiments, the sensors 130, 132 can be positioned adjacent to the different bearings 114 or portions thereof to measure the displacement of the respective bearings or portions thereof.

The temperature sensor is placed in thermal communication with the fluid to measure its temperature. In an exemplary embodiment, a temperature sensor 134 is positioned adjacent to the rotating race 116 and a temperature sensor 136 is positioned adjacent the fixed race 118. Thus, the temperature sensors 134, 136 are positioned in thermal communication with each of the races in fluid, which in turn is in thermal communication with the respective races. Since the fluid in these locations is in thermal communication with the respective races 116, 118, 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 the respective races 116, 118 is substantially equal to the temperature of the race. In other embodiments, this may not be the case and the temperature of the fluid adjacent the races 116, 118 is different than the temperature of the race. Temperature sensors 134, 136 are communicatively coupled to processor 140 (discussed in greater detail below) by any suitable communication system (e.g., a wired and/or wireless network).

A processor, shown schematically in Figures 2 and 3 and generally indicated at 140, is communicatively coupled to temperature sensors 134, 136, displacement sensors 130, 132 and heat exchanger 124. In general, and as discussed in more detail below, processor 140 is configured to receive input from one of the users to identify one of the desired wafer nanotop profiles or shapes from one of the wafers of the ingot slice. Based on the input and the measured temperature of the fluid, processor 140 passes the command to heat exchanger 124 to control (ie, adjust, modify, or change) the temperature of the fluid. The adjustment of the temperature of the fluid in turn controls the temperature of the portion of the bearing 114 that is in contact with the fluid and, consequently, the rest of the bearing. This change in temperature of the bearing 114 changes its displacement and the displacement of the wire guides 106 and 104. Control of the displacement of the wire guides 106 and wires 104 controls the shape of the surface of the wafer, which in turn controls the nanotopology of the surface.

The operation of processor 140 and system 100 will now be described in greater detail. An input device 160 (shown schematically in Figures 2 and 3) is communicatively coupled to the processor 140 and can be used to receive input from a user identifying the desired wafer nanotop or wafer shape. In other embodiments, processor 140 can receive this input from another computer system communicatively coupled to the processor.

Once this input is received by processor 140, the processor retrieves a prescription associated with the input from a memory 150. The memory is explained in more detail below. The prescription specifies a temperature set point (i.e., a desired temperature) of one of the bearings 114 and/or the temperature control fluid associated with the prescription. The prescription may also include displacement measurements of the bearing in addition to or in lieu of the temperature set point of the bearing and/or fluid. Compliance with the temperature and/or displacement measurements contained in the formulation during cutting of the ingot 102 by the saw 103 will typically result in a wafer having the same or similar characteristics as the input. The prescription is interchangeably referred to as a "temperature change curve", a "displacement change curve" and/or a "temperature displacement change" curve".

The prescription can be formed according to various methods. The specific temperature and/or displacement of each prescription may have been experimentally determined (i.e., during previous slicing operations) or empirically based on the material properties of the bearing 114 (i.e., the coefficient of thermal expansion of the material of the bearing). In one embodiment, the formulation is experimentally formed by measuring the fluid, the temperature of the bearing, and/or the displacement of the bearing 114 during slicing of the ingot 102 and storing the measurements in the memory 150. The surface of at least one of the wafers is then measured and then the shape of the wafer and/or the characteristics of the nanotopology are stored in memory 150. These characteristics of the wafer, along with temperature measurements and/or displacement measurements, form a prescription. As explained below, this procedure can also be used to periodically upgrade prescriptions.

As set forth above, in the exemplary embodiment, the temperature of the bearing 114 is typically equal to the temperature of the temperature controlled fluid in thermal communication with the bearing. The prescription is associated with the input such that the use of the prescription by the system will result in the wafer sliced by the saw 103 having the desired nanotop topology and/or shape of the input. These recipes are stored in memory 150 communicatively coupled to processor 140. The memory 150 is any suitable form of computer readable medium, including tangible storage devices (eg, a hard disk drive, flash memory, optical disk drive, etc.).

Such temperatures of the fluid will result in a change in the position of the bearing 114 which will result in the wafer being sliced to have the desired nanotopology and/or shape. In an exemplary embodiment, processor 140 retrieves a temperature set point from memory 150.

In operation, the saw 103 then begins to slice the ingot 102 and the processor 140 passes the command to the heat exchanger 124 to set the point and location based on the temperature of the fluid. The temperature is measured to adjust the temperature of the fluid. Once the temperature of the fluid is equal to the temperature at the temperature set point, the processor 140 sends an instruction to the heat exchanger 124 to stop adjusting the temperature of the fluid. The processor 140 can continue to monitor the temperature measurements received from the temperature sensors 134, 136. When the temperature of the fluid deviates from the temperature set point by more than a difference (eg, about +/- 0.1 degrees Celsius), processor 140 can send an instruction to heat exchanger 124 to again adjust the temperature of the fluid.

In other embodiments, the fluid flow rate is adjusted to control the temperature of the bearing rather than adjusting the temperature of the fluid to control the temperature of the bearing. The temperature of the fluid may not be measured and the temperature of the bearing 114 may be measured by temperature sensors 134, 136 instead. The temperature sensors 134, 136 are positioned such that they are capable of measuring the temperature of the bearing 114 (eg, the sensor is in contact with one of the bearings). In these embodiments, the formulation contains a temperature profile curve that illustrates one of the temperature set points of the bearing rather than the temperature set point of the fluid. Prescriptions may be generated and upgraded according to the same or similar methods as set forth herein.

A valve 170 (in general, a "control system") is provided in these embodiments to control (i.e., adjust, modify or change) the flow rate of the fluid, which in turn controls the temperature of the bearing 114. Valve 170 is in fluid communication with inlets 120, 126 and/or outlets 122, 128 via tubes, hoses or other suitable structures. Multiple valves 170 may be used in certain embodiments to control the flow rate of the fluid. Additionally, valve 170 can be communicatively coupled to processor 140 and actuated by an actuator or other suitable device by an actuator or other suitable device. According to some embodiments, the valve 170 is a proportional control valve, but in other embodiments the valve is any suitable valve (eg, a ball valve or a gate valve). In other embodiments, a variable flow rate pump can be used in place of or in combination with a valve to control the flow of fluid. rate.

When the flow rate of the fluid is increased by valve 170 (e.g., by opening the valve to a greater extent), the fluid can transfer more heat away from bearing 114. The fluid is therefore able to cool the bearing 114 and reduce its temperature. Reducing the flow rate of the fluid by means of the valve 170 (for example by closing the valve to a greater extent) has the opposite effect. That is, the reduced fluid flow cannot transfer so much heat away from the bearing 114. Depending on the flow rate, the temperature of the bearing 114 may therefore not decrease rapidly, remain stable or increase.

This temperature change of the bearing 114 caused by a change in the flow rate of the fluid changes its displacement and displacement of the wire guides 106 and 104. Control of the displacement of the wire guides 106 and wires 104 controls the shape of the surface of the wafer, which in turn controls the nanotopology of the surface.

Thus, in such embodiments, a heat exchanger is not used to control the temperature of the fluid. The fluid may be a cold-excited plant water at a relatively constant temperature (e.g., between about 5 ° C and about 10 ° C) obtained from a storage tank or other source prior to circulation in contact with the bearing 114. After contact with the bearing, the fluid is returned to the storage tank.

In other embodiments, the temperature and displacement of the bearing 114 are controlled by adjusting the flow rate of the fluid in conjunction with the temperature of the conditioning fluid. Temperature sensors 134, 136 can be used to measure the temperature of the fluid and/or bearing 114. A valve and/or variable flow rate pump as described above can be used to adjust the flow rate of the fluid to control the temperature of the bearing 114. The heat exchanger 124 set forth above can be used to control the temperature of the fluid. In these embodiments, the prescription also contains the temperature set point of the bearing in addition to the temperature set point of the fluid.

According to certain embodiments, the temperature set point is also determined based on the measured displacement of one of the fixed race 118 and/or the rotating race 116 of the bearing 114. For example, if the measured displacement of the bearing 114 is within a range of displacement specified by the prescription, the temperature set point can be adjusted such that the temperature of the fluid in thermal communication with the bearing and/or the flow rate of the fluid is not altered. The measured displacement of the bearing 114 can thus act as a feedback to the processor to adjust the temperature set point.

In some embodiments, the prescription can be upgraded after the slicing operation by measuring the surface of the wafer from the ingot slicing. For example, the surface of the wafer can be measured and compared to the desired wafer shape and/or nanotop profile input by the user. The prescription can be upgraded if the measurement of the surface is different from the desired wafer shape and/or nanotop profile input by the user. This upgrade may include adjusting the temperature set point of the fluid contained in the formulation and/or the flow rate of the fluid. The upgrade may also include adjustments to the desired displacement of portions of the bearing 114.

In another embodiment, the displacement of the bearing 114 is measured by the displacement sensors 130, 132 during the slicing of the ingot 102 at set intervals. The displacement measurement is then received by the processor 140. In response to the received measurements, the processor 140 determines to reduce or eliminate the displacement of the bearing 114 and to improve the temperature set point of the bearing 114 that this displacement can have on the wafer.

Processor 140 then passes the instructions to heat exchanger 124 to control the temperature of the fluid based, at least in part, on the measured displacement of bearing 114. In embodiments where valve 170 is used, processor 140 may also pass commands to the valve to control the flow rate of the fluid. These commands to valve 170 are also based, at least in part, on the measured displacement of bearing 114. The resulting action of both heat exchanger 124 and valve 170 controls the temperature of bearing 114, which in turn controls the displacement of the bearing. In addition, by processing The instructions generated by the device 140 may also be based, at least in part, on one or more prescriptions stored in the memory 150.

In one example, processor 140 may determine a temperature set point based on the measured displacement of bearing 114 or a portion thereof. The processor then passes the command to heat exchanger 124 to cool the fluid based on the measured displacement of the bearing or portion thereof. The decrease in temperature of the fluid reduces the temperature of the bearing 114, which in turn reduces or eliminates its displacement. Temperature sensors 134, 136 can also be used to measure the temperature of the fluid and/or bearing 114 and communicate such temperature measurements to processor 140. These temperature measurements are used as feedback for the processor 140.

In still other embodiments, only the temperature of the fluid is controlled during slicing of the ingot 102 and the displacement of the bearing 114 is not measured. In such embodiments, heat exchanger 124 controls the temperature of the fluid to control the temperature of bearing 114 based on a temperature set point. This temperature set point can be taken from a prescription as explained above. Alternatively, the temperature set point can be received from a user or other computer system as input to one of the systems 100. In certain embodiments, system 100 can measure the temperature of the fluid by means of respective sensors 134, 136 and use the measurement as feedback to control heat exchanger 124.

In still other embodiments, only the flow rate of the fluid is controlled during the slicing of the ingot 102 and the displacement of the bearing 114 is not measured. In such embodiments, valve 170 controls the flow rate of the fluid to control the temperature of bearing 114 based on a temperature set point. This temperature set point can be taken from a prescription as explained above. Alternatively, the temperature set point can be received from a user or other computer system as input to one of the systems 100. In some embodiments, system 100 can measure the temperature of bearing 114 by means of individual sensors 134, 136 and use measurement as Feedback is provided to control valve 170.

The systems and methods described herein control the nanotopology and shape of the wafer being cut in a wire saw machine 103. It has been determined that in prior systems, the bearing 114 or portions thereof were typically subjected to displacement or movement during slicing of the ingot 102. Graph 1 shows experimental data illustrating this change in displacement of the bearing 114. As shown in the graph of FIG. 4, the displacement of the fixed race 118 can remain relatively constant during slicing of the ingot 102 by the wire saw 103. However, the displacement of the rotating race 116 is already apparent. As such, in the exemplary embodiment, system 100 is directed to controlling the displacement of rotating race 116. In other embodiments, the displacement of the fixed race 118 can be controlled in conjunction with or in lieu of the displacement of the rotating race 116.

This displacement of the bearing 114 causes displacement of the wire guide 106 and wire 104 of the saw 103. This displacement of the wire guides 106 and wires 104 in turn causes defects in the shape of the wafer sliced from the ingot 102 and/or the nanotopology. Entry and exit tags are the type of such defects. It is believed that the displacement of the bearing 114 is caused by a change in one of the temperature of the bearing and thus a change in the temperature of the fluid in thermal communication with the bearing. The graph of Figure 5 shows experimental data illustrating this correlation between the temperature of the bearing and its displacement. The graph of Figure 6 shows experimental data illustrating the correlation between bearing displacement and wafer shape. In particular, the topmost data set represents the average displacement of the bearing, while the intermediate data set (including the data series of six wafers) represents the warpage measurement of the wafer. The lower data set (including the data series for the same six wafers) represents one WI measurement of the wafer. One of the mathematical transformations of the WI system's warpage measurement, which is predicted by one of its nanotopologies after the wafer has been polished. "FB" and "MB" identify the position of the wafer relative to the jigsaw 103.

The system and method described herein control the temperature of the bearing by controlling the temperature of the fluid in contact with the bearing 114. In addition, in addition to or in lieu of fluid temperature control, the flow of the control fluid can be used to control the temperature of the bearing. Control of the temperature of the bearing 114 in turn controls its displacement. Therefore, the displacement of the bearing 114 can be minimized or eliminated by controlling the temperature of the bearing 114. By doing this, the displacement of the wire guide 106 and the wire 104 can also be minimized or eliminated. As such, the shape of the wafer and/or its nanotopological defects (eg, entry or exit markings) can be reduced or eliminated. This reduction in defects increases the yield of the wafer fabrication process. In addition, downstream processing operations (eg, double side grinding) can be reduced or eliminated over time, thus reducing the time and cost of manufacturing wafers.

In addition to or in lieu of reducing or eliminating other defects (eg, entering or exiting a mark), systems and methods also permit a user to control the shape and/or nanotopology of the wafer. A user is thus able to input the desired shape and/or nanotop profile of one of the wafers sliced from the ingot 102. The user may desire the wafer to have a different shape and/or nanotopology for a variety of reasons.

For example, a wafer subjected to an epitaxial deposition process can be bent or warped to some extent by the program. In these examples, the shape of the wafer can be controlled by the system 100 during slicing of the ingot 102 such that the wafer has warpage or bending as opposed to warping or bending caused by the epitaxial deposition process. . For example, if a post-deposition epitaxial deposition process tends to bend the wafer in a convex direction, the shape of the wafer can be controlled by the system such that it is concave after being sliced. Therefore, once the wafer is later subjected to Lei In the crystal deposition process, the concave shape of the wafer will counteract the tendency of the program to warp the wafer in a convex direction. This will result in the wafer having a substantially flat shape after completion of the epitaxial deposition process.

The articles "a" and "the" are intended to mean the presence of one or more of the elements. The terms "including", "comprising" and "having" are intended to be inclusive and mean that there are additional elements in addition to the elements listed.

Since various changes can be made in the above without departing from the scope of the invention, all the contents contained in the above description and as illustrated in the accompanying drawings are to be construed as illustrative and not limiting. .

100‧‧‧Executive systems/systems

101‧‧‧Joint beam

102‧‧‧Ingots

103‧‧‧Wire sawing machine / wire saw / saw

104‧‧‧ line

105‧‧‧Clamping track

106‧‧‧Line guides

108‧‧‧ opposite end/different end

110‧‧‧ opposite end

112‧‧‧Frame

114‧‧‧ bearing

116‧‧‧Rotating Seat / Individual Seat / Seat

118‧‧‧Fixed seat/separate seat/seat

120‧‧‧Import

122‧‧‧Export

124‧‧‧Heat exchanger/single heat exchanger

Imported 126‧‧‧

128‧‧‧Export

130‧‧‧ Displacement Sensor/Sensor

132‧‧‧ Displacement Sensor/Sensor

134‧‧‧Temperature Sensor / Individual Sensors

136‧‧‧Temperature Sensor / Individual Sensors

140‧‧‧ processor

150‧‧‧ memory

160‧‧‧Input device

170‧‧‧ valve

FB‧‧‧ wafer position relative to the wire saw

Position of MB‧‧‧ wafer relative to wire saw

Mathematical transformation of WI‧‧‧ warpage measurement

Figure 1 is a perspective view of one of the systems including an ingot and a wire saw; Figure 2 is an end view of the system of Figure 1; Figure 3 is a left side view of the system of Figure 1; Figure 4 is shown by a wire saw A graph showing the relationship between bearing displacement and time when cutting an ingot; Figure 5 is a graph showing the relationship between bearing temperature and bearing displacement; and Figure 6 shows the relationship between bearing displacement and wafer shape. A chart.

100‧‧‧Executive systems/systems

101‧‧‧Joint beam

102‧‧‧Ingots

103‧‧‧Wire sawing machine / wire saw / saw

104‧‧‧ line

105‧‧‧Clamping track

106‧‧‧Line guides

108‧‧‧ opposite end/different end

114‧‧‧ bearing

116‧‧‧Rotating Seat / Individual Seat / Seat

118‧‧‧Fixed seat/separate seat/seat

120‧‧‧Import

122‧‧‧Export

124‧‧‧Heat exchanger/single heat exchanger

Imported 126‧‧‧

128‧‧‧Export

130‧‧‧ Displacement Sensor/Sensor

132‧‧‧ Displacement Sensor/Sensor

134‧‧‧Temperature Sensor / Individual Sensors

136‧‧‧Temperature Sensor / Individual Sensors

140‧‧‧ processor

150‧‧‧ memory

160‧‧‧Input device

170‧‧‧ valve

Claims (15)

A system for controlling a surface profile of a wafer cut from an ingot by a wire saw, the system comprising: a sensor for measuring a wire guide supporting a wire in the wire saw a displacement of a bearing; a temperature sensor for measuring the temperature of the bearing; and a processor communicatively coupled to both the sensor and the temperature sensor, the processor Configuring to determine a temperature set point of the bearing based at least in part on both the measured displacement of the bearing and the measured temperature of the bearing, the processor configured to provide an instruction to a valve Controlling a flow rate of the fluid based at least in part on the temperature set point, wherein the control of the flow rate of the fluid controls the displacement of the bearing, and the control of the displacement of the bearing is controlled by the wire saw The surface contour of the ingot-cut wafer, and wherein the flow system has water at a temperature between about 5 and 10 degrees Celsius. The system of claim 1, wherein the surface profile of the wafer comprises at least one of a nanotopology of the wafer and a shape of the surface of the wafer. The system of claim 1, wherein the sensor is configured to measure a displacement of one of the rotating seats of the bearing. The system of claim 1, wherein the sensor is configured to measure a displacement of one of the bearings to fix the race. The system of claim 3, wherein the sensor is a first sensor, and the system further comprises a measure for measuring a displacement of one of the bearings and communicatively coupled to the processor Two sensors. The system of claim 1, wherein the processor is configured to provide an instruction to a heat exchanger to control a temperature of a fluid circulating in contact with the bearing, wherein control of the temperature of the fluid controls the bearing The displacement, and wherein the control of the displacement of the bearing controls the surface profile of the wafer cut by the wire saw from the ingot. A system of claim 6 further comprising a temperature sensor for measuring the temperature of the fluid, wherein the temperature sensor is communicatively coupled to the processor. The system of claim 7, wherein the processor is configured to provide an instruction to the heat exchanger to control the temperature of the fluid based at least in part on the measured temperature of the fluid. A system for controlling a nanotopology of a sliced wafer in a wire saw for slicing a semiconductor or solar ingot into a wafer, the wire saw comprising a wire guide of the support wire, the wire guide being a bearing rotates and a fluid is in thermal communication with the bearing, the system comprising: a sensor disposed to measure displacement of the bearing of the wire guide, wherein the sensor includes a first sense a detector for measuring the displacement of one of the rotating races of the bearing, and a second sensor for measuring the displacement of one of the fixed races of the bearing; a processor communicatively coupled To the sensor and configured to determine a temperature set point for use in controlling the temperature of the fluid, the processor being configured to determine the temperature based at least in part on the measured displacement of the bearing a set point, wherein the control of the temperature of the fluid controls the displacement of the bearing, wherein the control of the displacement of the bearing Controlling a nanotopology of the wafer cut from the ingot by the wire saw, and wherein the flow system has water at a temperature between about 5 and 10 degrees Celsius; and a memory communicatively coupled to The processor is also configured to store the temperature set point. The system of claim 9 further comprising a heat exchanger for controlling the temperature of the fluid, the heat exchanger being communicatively coupled to the processor, the heat exchanger and one of the rotating races of the fluid inlet And a fluid outlet of one of the rotating races, a fluid inlet of the fixed race, and a fluid outlet of the fixed race for fluid communication. The system of claim 9, further comprising a temperature sensor for measuring the temperature of the fluid, wherein the temperature sensor is communicatively coupled to the processor. A system for controlling a surface profile of a sliced wafer in a wire saw for slicing a semiconductor or solar ingot into a wafer, the wire saw comprising a wire guide of the support wire, the wire guide The bearing rotates and a fluid is in thermal communication with the bearing, the system comprising: a sensor disposed to measure displacement of the bearing of the wire guide, wherein the sensor includes a first sensing And a second sensor for measuring displacement of one of the bearings to fix the race; a processor communicatively coupled to The sensor is configured to determine a temperature set point for use in controlling a flow rate of the fluid, the processor being configured to be based at least in part on the bearing Measuring the displacement determines the temperature set point, wherein control of the flow rate of the fluid controls displacement of the bearing, wherein control of the displacement of the bearing controls the surface profile of the wafer cut from the ingot by the wire saw And wherein the flow system has water at a temperature between about 5 and 10 degrees Celsius; and a memory communicatively coupled to the processor and configured to store the temperature set point. The system of claim 12, further comprising a valve for controlling the flow rate of the fluid, the valve being communicatively coupled to the processor. The system of claim 12, wherein the processor is configured to determine the temperature set point for use in controlling the temperature of the fluid. The system of claim 12, further comprising a heat exchanger for controlling the temperature of the fluid, the heat exchanger being communicatively coupled to the processor.