Surface shape prediction method and wafer processing method

Abstract

To provide a surface shape prediction method capable of easily predicting a surface shape of a wafer and a processing member by predicting an in-plane distribution of a wafer removal amount by processing of the wafer and an abrasion state of the processing member such as a surface plate, a grinder and a pad by a simple computer simulation.SOLUTION: A method for predicting a surface shape of a wafer and / or a processed member of the wafer by processing, the method comprising: performing a frictional heat generation simulation when the wafer and / or the processed member of the wafer is processed using a processing condition as a parameter; and predicting the surface shape of the wafer and / or the processed member by the processing based on a frictional heat generation amount obtained by the frictional heat generation simulation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a surface shape prediction method and a wafer processing method. [Background technology]

[0002] The surface of a silicon wafer, which is used as a component of a semiconductor product, is generally finished to a high-quality mirror surface through a lapping process, a grinding process (rough polishing process), and a polishing process (precision polishing process).

[0003] The polishing step typically includes a preliminary polishing step (preliminary polishing step) and a final polishing step (finish polishing step). The preliminary polishing step can be preferably carried out in a manner in which both sides of the silicon substrate are polished simultaneously (double-sided polishing: DSP). The final polishing step can be preferably carried out in a manner in which one side of the silicon substrate is polished (CMP).

[0004] In the lapping, grinding, double-sided polishing, and CMP processes, the distribution of removal stock within a wafer and the difference in removal stock between wafers vary depending on the processing conditions, such as the surface plate used in lapping, DSP, and CMP, the grinding machine used during grinding, the rotation speed of the carrier or head that holds the wafer, the pressure applied to the wafer, and the shapes of the surface plate, grinding machine, pad, etc. In addition, adjustments are made using a dresser to manage the processing equipment, and the amount of removal of the surface plate, grinding machine, or pad by the wafer, carrier, or dresser also varies depending on the rotation speed, pressure, and the shapes of the surface plate, grinding machine, pad, etc.

[0005] By processing wafers under various conditions, it is possible to determine the trends in the removal allowance within and between wafers, as well as the wear amount of the surface plate, grinding machine, and pads, but this requires processing under many conditions, which is time-consuming and costly. In particular, the wear of the surface plate, grinding machine, and pads changes gradually over a long period of processing, which takes time, and it is necessary to replace the surface plate, grinding machine, or pads every time the conditions are changed, which is time-consuming and costly. Therefore, attempts are being made to determine the trends in the removal allowance within and between wafers, as well as the wear amount of the surface plate, grinding machine, and pads, using computer simulations.

[0006] Methods for estimating a machining shape corresponding to machining conditions have also been studied. For example, Patent Document 1 provides a machining shape prediction method that can accurately predict a corresponding machining shape when machining conditions are given. Specifically, in step S11, a model formula including a correction coefficient, i.e., a model formula for a machining shape determined corresponding to predetermined machining conditions, is created. Next, in step S12, simple machining conditions are set and machining is performed. Subsequently, in step S13, the machining shape is measured. Then, in step S14, a correction coefficient is identified so that the machining shape calculated using the model formula is close to the actually obtained machining shape. Thereafter, in step S15, the identified model formula is used to estimate a machining shape corresponding to the given machining conditions.

[0007] Patent Document 2 also describes the following method for determining machining conditions. That is, in step S11, the amount of variation (parameter) is changed stepwise at a predetermined pitch, and standard machining conditions consisting of a combination of these are determined. Machining is actually performed under each of all standard machining conditions, and the resulting machined shapes are set as standard machining shapes for the standard machining conditions (step S12). If an appropriate simulation program is available, the standard machining shape may be determined by simulation without actually performing machining. The standard machining conditions and standard machining shape thus determined are stored in a storage device. When a target shape to be machined is given in step S13, a standard machining shape close to the target shape is searched for in step S14. In this way, when a machining shape is given, the corresponding machining conditions can be determined. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-153229 [Patent Document 2] International Publication No. 03 / 078104 Summary of the Invention [Problem to be solved by the invention]

[0009] Although simulation programs are sometimes used to estimate the processed shape corresponding to the processing conditions, most computer simulations require solving complex calculations, which is problematic as only experts can perform them.In addition, most computer simulations have a narrow analysis area and can only calculate specific points on the wafer, surface plate, or pad, which means that the in-plane distribution cannot be determined.

[0010] The present invention has been made to solve the above problems, and has as its object to provide a surface shape prediction method that can predict, by simple computer simulation, the wafer removal amount due to wafer processing and the in-plane distribution of the wear state of processing members such as a surface plate, grinding machine, and pad, thereby easily predicting the surface shapes of wafers and processing members. [Means for solving the problem]

[0011] The present invention has been made to achieve the above-mentioned object, and provides a surface shape prediction method for predicting the surface shape of a wafer and / or a processed member of a wafer due to processing, which performs a frictional heat simulation when processing a wafer and / or a processed member of a wafer using processing conditions as parameters, and predicts the surface shape of the wafer and / or the processed member due to the processing based on the amount of frictional heat obtained from the frictional heat simulation.

[0012] According to this surface shape prediction method, it is possible to predict the wafer removal amount due to wafer processing and the in-plane distribution of the wear state of processing members such as a surface plate, grinding machine, and pad by simple computer simulation, and as a result, it is possible to easily predict the surface shapes of the wafer and processing members.

[0013] In this case, the amount of frictional heat generated by the frictional heat simulation can be converted into the removal amount of the wafer or the amount of wear of the processed member due to the processing, thereby forming a surface shape prediction method for predicting the surface shape of the wafer or the processed member due to the processing.

[0014] This makes it easy to evaluate the distribution of machining allowance and wear amount.

[0015] At this time, the frictional heat generation simulation may be performed using a surface shape prediction method in which the thermal conductivity of the wafer and / or the processed member of the wafer is set to 0. Also, the frictional heat generation simulation may be performed using a surface shape prediction method in which the surface of the wafer and / or the processed member of the wafer is set to be thermally insulated.

[0016] This makes it possible to more easily predict the surface shape with higher accuracy.

[0017] In this case, the surface shape prediction method may be such that the processing is any one of lapping, grinding, double-side polishing, and single-side polishing.

[0018] The surface shape prediction method according to the present invention can be particularly suitably applied to such processing.

[0019] In this case, the processing conditions may be any one of lapping conditions, grinding conditions, polishing conditions, and dressing conditions.

[0020] The surface shape prediction method according to the present invention can be applied to such processing conditions in particular.

[0021] In this case, the surface shape prediction method may be such that the processing member is one or more of a surface plate, a grinding machine, and a pad.

[0022] The surface shape prediction method according to the present invention can be particularly suitably used for predicting the surface shape of such processed members.

[0023] In this case, the wafer processing method can be such that the above-mentioned surface shape prediction method is performed for a plurality of wafer processing conditions, the surface shape of the wafer resulting from processing of the wafer is predicted for each of the plurality of wafer processing conditions, processing conditions for obtaining a target wafer surface shape are determined based on the predicted results, and the wafer is processed under the determined processing conditions.

[0024] This makes it possible to easily determine the processing conditions for a wafer having a desired surface shape, and to efficiently process the wafer. [Effects of the Invention]

[0025] As described above, the surface shape prediction method of the present invention makes it possible to predict, by simple computer simulation, the wafer removal amount due to wafer processing and the in-plane distribution of the wear state of processing members such as a surface plate, grinding machine, and pad, and as a result, it becomes possible to easily predict the surface shapes of the wafer and processed members. [Brief explanation of the drawings]

[0026] [Figure 1] 1 shows the shape of the dresser analyzed in Example 1. [Figure 2] An example of mesh generation for a lapping platen and dresser is shown below. [Figure 3] The analysis results of Example 1 are shown. [Figure 4] 10 shows the predicted results of the wear amount of the surface plate based on the analysis results of Example 1. [Figure 5] 10 is a diagram for explaining an analysis target of Example 2. [Figure 6] 10 is a diagram illustrating the analysis results of Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will be described in detail below, but the present invention is not limited thereto.

[0028] As described above, there has been a demand for a surface shape prediction method that can predict, by simple computer simulation, the wafer removal amount due to wafer processing and the in-plane distribution of the wear state of processing parts such as surface plates, grinders and pads, and that can easily predict the surface shapes of wafers and processing parts.

[0029] As a result of extensive research into the above-mentioned problems, the present inventors have discovered that a method for predicting the surface shape of a wafer and / or a processed member of a wafer due to processing can be accomplished through a simple computer simulation by using a surface shape prediction method that performs a frictional heat simulation when processing a wafer and / or a processed member of a wafer using processing conditions as parameters, and predicts the surface shape of the wafer and / or the processed member due to processing based on the amount of frictional heat obtained from the frictional heat simulation.The method makes it possible to predict the wafer removal amount due to wafer processing and the in-plane distribution of the wear state of processed members such as a surface plate, grinder, and pad, and as a result, the surface shape of the wafer or processed member can be easily predicted, thereby completing the present invention.

[0030] The following description will be made with reference to the drawings.

[0031] [Surface shape prediction method] As mentioned above, attempts have been made to use computer simulations to determine the wafer removal rate within the wafer surface and between wafers during wafer processing, as well as the wear trends of processing parts used in processing, such as lapping and polishing plates, grinding machines, and polishing pads. In particular, for equipment design and management, it is important to predict the surface shape of the wafer processing parts, and therefore to estimate the amount of removal (amount of wear) (predicting changes over life).

[0032] The inventors noticed that the related parameters in the formula for deriving the polishing amount (wear amount) and the formula for calculating the amount of frictional heat are almost the same, and conducted extensive research to determine whether the distribution of the polishing amount (wear amount) or its change over time due to life could be predicted from the amount of frictional heat, and completed the present invention.

[0033] The amount of polishing generally follows Preston's law, and the following relational expression is generally known. Polishing amount δ ∝ Machining pressure (p) · Relative speed (v) · Machining time (t) · Area (s) It is also known that the amount of frictional heat is related by the following formula: Frictional heat generation Q ∝ Load (W) · Relative speed (v) · Machining time (t) · Area (s) The present inventors have noticed that the parameters that affect the polishing amount and the amount of frictional heat generation are almost the same.

[0034] In other words, rather than directly simulating the removal amount and wear amount using complex calculations, it was discovered that by simulating the amount of frictional heat, which can be calculated simply, it is possible to easily predict the removal amount within the wafer surface and between wafers, as well as the amount of wear and its distribution tendency of wafer processing parts such as lapping and polishing plates, grinding machines, and polishing pads used in processing.As a result, it is possible to easily predict the surface shapes of the wafers and processing parts, and it is easy to set processing conditions and manage their life (shape management of platens, etc.).

[0035] The surface shape prediction method of the present invention can set arbitrary processing conditions when processing a wafer or a processed member of a wafer, perform a frictional heat simulation under those processing conditions, and predict the processed shape of the wafer or processed member based on the amount of frictional heat obtained from the frictional heat simulation.

[0036] Furthermore, the inventors have found that there is a particularly good correlation between changes in the amount of frictional heat (temperature) obtained by performing a frictional heat simulation and changes in the amount of wear (amount of polishing). Specifically, it was found that in areas where the amount of frictional heat is large (high temperature), the amount of wear (amount of polishing) is also large, and conversely, in areas where the amount of frictional heat is small (low temperature), the amount of wear (amount of polishing) is also small. By utilizing this, it is possible to obtain the amount of frictional heat (temperature) by performing a frictional heat simulation and easily convert that amount of frictional heat (temperature) into the amount of polishing (amount of wear), thereby predicting the distribution of the removal rate and amount of wear of wafers and parts used in processing (predicting the processed shape) and designing and managing the processing process (determining the processing conditions).

[0037] In this way, by regarding the temperature distribution of the wafer and / or the processed member of the wafer as the polishing amount (wear amount) distribution, it is possible to more easily predict the surface shape of the wafer and / or the processed member of the wafer.

[0038] The wafer processing is preferably any one of lapping, grinding, double-side polishing, and single-side polishing. These processes involve wear on both the product and the equipment, and it is particularly important to estimate the surface shape.

[0039] The processing conditions are preferably any one of lapping, grinding, polishing, and dressing conditions. The type of wear is likely to change depending on the processing conditions, so it is particularly important to estimate the surface shape in advance in order to set the processing conditions and manage life (shape management of the surface plate, etc.).

[0040] Furthermore, the processing member is preferably one or more of a surface plate, a grinding plate, and a pad, and it is particularly important to estimate the surface shape of these members.

[0041] In particular, the processed shape can be the shape of the wafer, the shape of the surface plate, grinding machine, or pad, or the removal amount of the wafer, the surface plate, grinding machine, or pad.Things that wear out include products (intentionally processed by a set amount of removal amount) and equipment (components wear out as a result of processing), and it is important to estimate their shapes and removal amount (especially the removal amount distribution).

[0042] Simulations can reveal the wear trends when using specific processing conditions, allowing users to check the equipment status and set processing conditions that are appropriate for that equipment.

[0043] In the present invention, the apparatus and conditions for each step are not particularly limited, but the steps can be carried out using commonly used apparatuses, etc. Each processing step will be specifically described below.

[0044] In the lapping process, if it is necessary to keep the lapping plate flat, and if it has a convex shape, dressing conditions are set that make it easier to create a concave shape, and the plate shape is corrected.

[0045] In lapping processing, a lapping device is known that performs lapping by combining three motions: the rotational motion of a concentric circular platen, the revolutional motion of a disk-shaped lapping carrier relative to the device body, and the rotational motion of the disk-shaped lapping carrier, thereby imparting relative motion to the platen and the workpiece.

[0046] The lapping device has a lower platen and an upper platen (sometimes referred to as "lapping platen" or simply "platen") arranged opposite each other in the vertical direction. The lower platen and / or the upper platen are rotated by a drive means. The lower platen has a sun gear at its center on its upper surface, and an annular internal gear is attached adjacent to its periphery. A disc-shaped lapping carrier has a gear portion formed on its outer periphery that meshes with the sun gear and internal gear, forming a gear structure as a whole. The carrier has multiple workpiece holding holes. The workpiece W, such as a wafer to be lapped, is placed in the workpiece holding holes. The lapping carrier is placed between the upper and lower platens, and the outer gear of the lapping carrier is engaged between the sun gear located in the center of the lower platen and the internal gear located on the outside of the lower platen, and the upper platen is lowered. The lapping carrier performs planetary motion between the upper and lower platens, which rotate in opposite directions. The workpiece W fits into the workpiece holding hole opened in the lapping carrier, and is subjected to the lapping carrier's rotational and revolutionary motion. To perform the lapping process, a turbid liquid called slurry, which is a mixture of abrasive grains such as aluminum oxide or silicon carbide and a liquid such as water containing a surfactant, is poured from a nozzle into the gap between the upper and lower platens through through holes in the upper platen, sending abrasive grains between the workpiece W and the upper and lower platens, and processing is performed by transferring the shape of the upper and lower platens to the workpiece W.

[0047] In addition, the lapping surface plate gradually changes due to the processing of the workpiece W that will become the final product. Therefore, the shape of the lapping surface plate is periodically corrected by processing using a dressing carrier (sometimes called a "dresser") instead of a lapping carrier.

[0048] With this type of equipment, it is possible to simulate how the wafer shape (machining allowance) changes by changing the conditions of planetary motion, or, for example, how the lapping platen is scraped by designing several patterns of the dressing carrier shape.

[0049] In grinding, for example, a surface grinder is used to perform single-wafer processing, and examples of such devices include a double-head grinder that simultaneously grinds both the front and back sides of a wafer, and a single-side grinder that grinds only the front or back side of a wafer. With such a surface grinder, for example, it is possible to simulate grinding marks on a wafer and wear on a grinding wheel.

[0050] In double-sided polishing, the double-sided polishing machine typically used is a so-called four-way system, which has an upper and lower platen to which polishing cloth (sometimes simply called "pads") made of nonwoven fabric or the like is attached, and has a planetary gear structure with a sun gear in the center and an internal gear on the periphery.

[0051] When polishing silicon wafers, the wafers are inserted and held inside the multiple wafer holding holes formed in the carrier plate, polishing slurry is supplied to the wafer from above, and the upper and lower surface plates are rotated while the opposing polishing cloths on the upper and lower surface plates are pressed against both the front and back sides of the wafer, and the carrier plate is rotated and revolved between the sun gear and internal gear, allowing both sides of each wafer to be polished simultaneously.

[0052] Another type of double-sided polishing apparatus is known, in which a carrier plate sandwiched between upper and lower platens is moved in a circular motion, drawing small circles, to perform double-sided polishing, without rotating.

[0053] When polishing continues using the same polishing cloth in a polishing machine, the wafer shape gradually changes. This is mainly due to the life of the polishing cloth, and is affected by changes in the compressibility of the polishing cloth and clogging, etc. As the frequency of use increases, the wafer shape changes, and the outer periphery of the wafer is easily over-polished, resulting in so-called peripheral sagging. Therefore, to prevent such changes in wafer shape, the wafer surface is dressed periodically or constantly.

[0054] For example, in such a double-sided polishing machine, several patterns of dressing members can be designed and a simulation can be performed to see how the shape of the polishing pad changes (how it is removed). It is also possible to simulate the wafer removal amount when polishing conditions such as the rotation and oscillation of the carrier are changed.

[0055] In single-sided polishing, an example of an apparatus is one in which the wafer is held by a polishing head, the polishing head is pressed against a surface plate, and the polishing head and the surface plate are rotated to polish the wafer.

[0056] With such a single-sided polishing apparatus, for example, it is possible to design several patterns for the dressing member and simulate how the shape of the polishing pad (sometimes simply called the pad) changes (is scraped).

[0057] The surface shape prediction method of the present invention will now be described in detail. First, simulation software capable of analyzing frictional heat generation is prepared. General software for simulations to determine the amount of frictional heat generation is commercially available, and can be performed relatively easily. For example, an explicit analysis program, which is excellent for analyzing discontinuous problems where there is a lot of contact / friction, can be used.

[0058] Next, create a CAD model of the wafer, equipment, and its components (carrier, dresser, surface plate, pad) that you want to analyze for lapping, grinding, double-sided polishing, single-sided polishing, etc. You can also design multiple processing conditions that you particularly want to change.

[0059] Next, the simulation conditions are set. For example, the rotation and oscillation conditions of the wafer, carrier, dresser, surface plate, grinding machine, and pad are set. Generally, generated heat is transferred to the lower temperature side within a solid, but the amount of material removed by polishing or abrasion does not move. Therefore, in the surface shape prediction method of the present invention, it is preferable to set the thermal conductivity of the wafer and / or wafer processing member to be analyzed to 0. Alternatively, since heat is transferred between the solid surface and the fluid, but the amount of material removed by polishing or abrasion does not move from the solid surface to the fluid, the surface of the wafer and / or wafer processing member may be set to be thermally insulated in the frictional heat generation simulation of the present invention.

[0060] Next, set the analysis time. For example, bring the wafer, carrier, or dresser you want to analyze into contact with the surface plate, grinder, or pad, and simultaneously start rotating or oscillating them. Then, use Solver, a Microsoft spreadsheet program, to calculate the amount of frictional heat.

[0061] After the analysis is completed, the obtained temperature distribution can be regarded as the grinding stock removal (wear) distribution, and the surface shape prediction results can be obtained.

[0062] [Wafer processing method] A wafer processing method can be provided that utilizes the above-described surface shape prediction method. The surface shape prediction method according to the present invention is performed for a plurality of wafer processing conditions, and the wafer surface shape resulting from wafer processing under each of the plurality of wafer processing conditions is predicted. Based on the predicted results, processing conditions for obtaining a target wafer surface shape can be determined. By processing a wafer under the processing conditions determined in this manner, it is possible to efficiently process a wafer to have a desired surface shape. [Example]

[0063] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0064] Example 1 In wafer processing (lapping processing), the shape of the lapping plate (processed shape) was predicted by setting arbitrary processing conditions (shape of the lap dresser) and performing a frictional heat simulation of the platen under those processing conditions (set shape of the lap dresser) regarding the amount of wear of the lapping platen.

[0065] Lap dressers are generally circular, and when a lap platen is dressed with this dresser, the outer periphery in the radial direction tends to be significantly worn away. This is effective for correcting a surface plate with a concave shape in the radial direction, but in the case of a convex shape, the convexity becomes even stronger. Therefore, several designs were devised, and the amount of wear due to dressing (the shape of the lap dresser) was predicted through simulation.

[0066] Specifically, as lap dressers, a circular (ring-shaped) dresser 1A shown in FIG. 1(A), a circular (with a cross section) dresser 1B shown in FIG. 1(B), and a circular (disk-shaped) dresser 1C shown in FIG. 1(C) were set up, and the change in the surface shape of the surface plate 2 was predicted.

[0067] First, a model of the object to be analyzed was created using 3D CAD. The analysis was performed on a lapping plate and dresser as shown in Figure 1. The software used was ANSYS SpaceClaim (ANSYS Inc.).

[0068] Next, meshes were generated for the lapping platen 2 and dresser to be evaluated, as shown in Figure 2. Note that Figure 2 shows an example of mesh generation for the dresser 1A and lapping platen 2 in Figure 1(A). Mesh generation for each component was performed using ANSYS LS-Dyna (ANSYS Inc.).

[0069] Next, the physical properties were set. In this case, deformation due to contact or heat was not taken into consideration, so both the dresser and the surface plate were set to rigid bodies, and the thermal conductivity of both the dresser and the surface plate was set to 0. In particular, it was found that setting the thermal conductivity to 0 improved the correlation between the temperature obtained by the frictional heat simulation and the amount of polishing (amount of wear). In addition, the surfaces of both the dresser and the surface plate were set to insulating. It was found that setting the surfaces to insulating improved the correlation between the temperature obtained by the frictional heat simulation and the amount of polishing (amount of wear).

[0070] Next, we set common processing conditions other than the shape of the lap dresser and performed a simulation. Set the rotation speed of the surface plate and the dresser. 0.1 seconds after the start of the analysis, the dresser is pushed 0.1 mm into the surface plate. -Analysis is performed for 100 seconds. The simulation was carried out under these conditions.

[0071] After the analysis was completed, the amount of wear on the surface plate was estimated from the obtained temperature distribution. The analysis results are shown in Figure 3. Figure 3 shows the temperature distribution obtained from the analysis, which was considered to represent the amount of wear, with high temperature areas representing large amounts of wear and low temperature areas representing small amounts of wear. Figure 4 shows the temperature (amount of wear) profile in the radial direction of the surface plate (change from the inside to the outside of the surface plate). When the surface plate shape was estimated from these, as shown in Figure 4, it was predicted that with the circular (ring-shaped) dresser (design 1) in Figure 1(A), the amount of wear on both ends of the surface plate would tend to be large.

[0072] In the case of the circular (with cross section) dresser (Design 2) in Figure 1(B), it was predicted that the center in the radial direction would be locally and significantly worn away.

[0073] In the case of the circular (disk-shaped) dresser (Design 3) in Figure 1(C), it was predicted that the amount of wear would be large overall, with the amount of wear at the center in the radial direction being large.

[0074] In fact, when design 3 in Figure 1(C) was used and dressing was repeated, the center of the lapping plate in the radial direction became concave, and it was confirmed that the surface shape prediction results based on the simulation, which showed that the amount of wear in the center in the radial direction was large, were correct.

[0075] Therefore, we manufactured a dresser of Design 3 and used it on a device with a convex surface plate. We were able to efficiently correct (dress) the convex portion and make the surface plate flat.

[0076] In this way, by using the frictional heat generation simulation described above to estimate which dresser shape should be used for which equipment, it was possible to easily determine the processing conditions.

[0077] Example 2 The carrier plate 3 sandwiched between the upper and lower surface plates was not rotated but moved in a circular motion in a small circle to perform double-sided polishing. The polishing conditions (oscillating conditions) were set for wafer processing (double-sided polishing), and a frictional heat generation simulation was performed under these processing conditions to predict the shape of the wafer (processed shape).

[0078] The frictional heat generation simulation was carried out under the following conditions: oscillation condition 1, horizontal oscillation of the carrier plate 3; oscillation condition 2, figure-of-eight oscillation; and oscillation condition 3, circular oscillation (see Fig. 5).

[0079] Three wafers A, B, and C were held on the carrier plate 3, and the manner in which each of the wafers A, B, and C was polished was simulated using the method of the present invention.

[0080] First, a model of the object to be analyzed was created using 3D CAD. As shown in Figure 5, the analysis targets were wafers A, B, and C, carrier plate 3, its oscillation, and surface plate 4. The software used was ANSYS SpaceClaim (ANSYS Inc.).

[0081] Next, meshes were generated for wafers A, B, and C and surface plate 4. The mesh generation was performed using ANSYS LS-Dyna (ANSYS Inc.).

[0082] Next, the physical properties were set. In this case, deformation due to contact or heat was not taken into consideration, so both the wafer and the surface plate were set to rigid bodies, and the thermal conductivity of both the wafer and the surface plate was set to 0. In particular, it was found that setting the thermal conductivity to 0 improved the correlation between the temperature obtained by the frictional heat simulation and the polishing amount (amount of wear). In addition, the surfaces of both the dresser and the surface plate were set to insulating. It was found that setting the surfaces to insulating improved the correlation between the temperature obtained by the frictional heat simulation and the polishing amount (amount of wear).

[0083] Next, common processing conditions other than the oscillation for double-sided polishing were set. Specifically, Set the rotation speed of the surface plate and the wafer, assuming that the wafer rotates on its axis. 0.1 seconds after the start of analysis, the wafer is pressed 0.1 mm onto the surface plate. -Analysis is performed for 100 seconds. The simulation was carried out under these conditions.

[0084] After the analysis was completed, the wafer shape (machining allowance, wear amount) was estimated from the obtained temperature distribution of wafers A, B, and C. The analysis results are shown in Fig. 6. As shown in Fig. 6, the results of the frictional heat simulation made it possible to make the following predictions.

[0085] In oscillation condition 1 (horizontal oscillation), there is variation in the temperatures (removal allowance) of the three sheets. In the figure-eight oscillation of oscillation condition 2, there is some variation in the temperatures (removal allowance) of the three sheets. In the circular oscillation mode of oscillation condition 3, the temperatures (removal allowances) of the three sheets are almost the same.

[0086] When wafer processing was actually carried out under the three oscillation condition patterns described above, the variation between wafers was smallest when oscillating under oscillation condition 3, and the quality between wafers and between batches was stable.

[0087] In Examples 1 and 2, Ansys LS-DYNA (ANSYS Inc.) was used, which is an explicit analysis program that excels in analyzing discontinuous problems with a lot of contact / friction. However, it is also possible to use a program that can perform frictional heat generation analysis, such as an implicit program that handles nonlinear analysis.

[0088] As described above, it was found that a simple computer simulation using frictional heat generation can easily predict the wafer removal allowance and the in-plane distribution of the wear state of the surface plate, grinding machine, and pad, and that predicting the amount of polishing (amount of wear) and changes over life will facilitate management of the processing process and the design and management of processing equipment.

[0089] As described above, according to the embodiment of the present invention, by performing a frictional heat generation simulation, it was possible to predict with high accuracy the surface shape of a wafer to be easily processed and a processed member of the wafer.

[0090] The present specification includes the following aspects. [1]: A method for predicting the surface shape of a wafer and / or a processed member of a wafer due to processing, which performs a frictional heat simulation when processing a wafer and / or a processed member of a wafer using processing conditions as parameters, and predicts the surface shape of the wafer and / or the processed member due to the processing based on the amount of frictional heat obtained from the frictional heat simulation. [2]: The surface shape prediction method according to [1], which predicts the surface shape of the wafer or the processed member due to the processing by converting the amount of frictional heat generated by the frictional heat simulation into the removal amount of the wafer or the amount of wear of the processed member due to the processing. [3]: The surface shape prediction method according to [1] or [2], wherein the thermal conductivity of the wafer and / or the processing member of the wafer is set to 0 in the frictional heat simulation. [4]: The surface shape prediction method according to [1] or [2], wherein the surface of the wafer and / or the processing member of the wafer is set to be thermally insulated in the frictional heat generation simulation. [5]: The surface shape prediction method according to [1], [2], [3] or [4], wherein the processing is any one of lapping, grinding, double-side polishing and single-side polishing. [6]: The surface shape prediction method according to [1], [2], [3], [4] or [5] above, wherein the processing conditions are any of lapping conditions, grinding conditions, polishing conditions and dressing conditions. [7]: The surface shape prediction method according to [1], [2], [3], [4], [5] or [6], wherein the processing member is one or more of a surface plate, a grinding machine, and a pad. [8]: A wafer processing method, comprising: performing the surface shape prediction method of [1], [2], [3], [4], [5], [6] or [7] above for a plurality of wafer processing conditions; predicting the surface shape of the wafer resulting from processing the wafer for each of the plurality of wafer processing conditions; determining processing conditions for obtaining a target wafer surface shape based on the predicted results; and processing the wafer under the determined processing conditions.

[0091] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention. [Explanation of symbols]

[0092] 1A, 1B, 1C...Lap dresser (dresser), 2...Surface plate, 3...Carrier plate, 4...Surface plate. A, B, C... wafers.

Claims

1. 1. A method for predicting a surface shape of a wafer and / or a processed member of a wafer due to processing, comprising: A frictional heat generation simulation is performed when processing the wafer and / or the processing member of the wafer, using the processing conditions as parameters; A surface shape prediction method, comprising predicting a surface shape of the wafer and / or the processed member due to the processing based on the amount of frictional heat generated by the frictional heat simulation.

2. 2. The surface shape prediction method according to claim 1, wherein the amount of frictional heat generated by the frictional heat simulation is converted into a removal amount of the wafer or an amount of wear of the processed member due to the processing, thereby predicting the surface shape of the wafer or the processed member due to the processing.

3. 2. The surface shape prediction method according to claim 1, wherein the thermal conductivity of the wafer and / or the member to be processed on the wafer is set to 0 in the frictional heat simulation.

4. 2. The surface shape prediction method according to claim 1, wherein the surface of the wafer and / or the processed member of the wafer is set to be thermally insulated in the frictional heat generation simulation.

5. 2. The method for predicting a surface shape according to claim 1, wherein the processing is any one of lapping, grinding, double-side polishing, and single-side polishing.

6. 2. The method for predicting a surface shape according to claim 1, wherein the processing conditions are any one of lapping conditions, grinding conditions, polishing conditions, and dressing conditions.

7. 2. The method for predicting a surface shape according to claim 1, wherein the processing member is at least one of a surface plate, a grinding machine, and a pad.

8. A wafer processing method comprising:

8. A wafer processing method comprising: performing the surface shape prediction method according to claim 1 for a plurality of wafer processing conditions; predicting a surface shape of the wafer resulting from processing the wafer for each of the plurality of wafer processing conditions; determining processing conditions for obtaining a target wafer surface shape based on the predicted results; and processing the wafer under the determined processing conditions.

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