JP2009233763A - Method of fixing crystal substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of uniformly fixing a substrate to a pasting base while preventing an abrasive from flowing to the rear surface in a semiconductor substrate rough polishing step. <P>SOLUTION: This method of fixing a crystal substrate includes a coating step of heating the pasting base for fixing a substrate to be polished thereon and coating the substrate with a thermosoluble adhesive agent, an adhesive agent pressing step of pressing the thermosoluble adhesive agent by an elastic body, a removing step of removing the thermosoluble adhesive agent adhered to the elastic body, a substrate installation step of installing the substrate to be polished on the thermosoluble adhesive agent, a substrate pressing step of pressing the substrate to be polished by the elastic body, and a removal step of removing the substrate to be polished together with the pasting base for the substrate to be polished. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor substrate, and more particularly, to a fixing technique for polishing a SiC single crystal substrate.

The manufacturing process of a semiconductor substrate includes steps of slicing to form a crystal-grown ingot material, rough polishing for adjusting the substrate shape, and precision polishing for reducing the roughness of the outermost surface. In this, rough polishing is performed while the substrate is fixed to the sticking table. This is a process of improving the flatness (TTV: Total Thickness variation) of the substrate by uniformly fixing the substrate to the affixing base. Conventionally, a heat-soluble adhesive applied to a heated affixing table was used, and the periphery of the affixing table was in a vacuum state, and the substrate was fixed by uniformly pressing the substrate with an elastic body in a state where bubbles in the adhesive were removed . (For example, refer to Patent Document 1).
JP 2007-123670 A (first page, FIG. 1)

  However, in the conventional method, the adhesive is not necessarily uniformly applied to the affixation base, and the pressure is applied to the substrate through the elastic body and the adhesive is extended, so that it is easily affected by the shape of the substrate. . In particular, materials such as SiC that are difficult to process have poor SORI after slicing, and the adhesive does not spread uniformly on the back surface of the substrate only by pressing with an elastic body. When there is a portion where the adhesive is not applied between the substrate and the affixing table, the abrasive flows between the substrate and the affixing table in the rough polishing process, and the back surface of the substrate is locally processed. Rough polishing is performed by stepping the front and back surfaces in two steps or more, and by changing the abrasive grains in the abrasive. Each process needs to reduce the size of the abrasive grains in the abrasive step by step. For example, when the B surface on the opposite side of the substrate after the rough polishing of the A surface is rough polished, the surface is rougher at first. Since the polishing agent is used, the polishing agent flows into the A surface roughly polished with a finer polishing agent and roughens the A surface. In this case, the A side must be coarsely polished again.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a method for preventing the polishing agent from flowing into the back surface and more uniformly fixing the substrate to the sticking table in the rough polishing step of the semiconductor substrate. And

  In order to solve the above-mentioned conventional problems, the crystal substrate fixing method of the present invention includes an application step of heating a sticking base for fixing a substrate to be polished to apply a heat-soluble adhesive, and the heat-soluble adhesive. An adhesive pressurizing step that pressurizes the elastic body, a removal step of removing the heat-soluble adhesive attached to the elastic body, a substrate installation step of installing the substrate to be polished on the heat-soluble adhesive, The method includes a substrate pressing step of pressing the substrate to be polished by the elastic body, and a step of taking out the substrate to be polished together with the base for attaching the substrate to be polished.

  Furthermore, the present invention provides an application step of applying a heat-soluble adhesive by heating a sticking base for fixing a substrate to be polished to a first temperature, and applying the heat-soluble adhesive to the first elastic body. An adhesive pressurizing step for pressurizing; an elastic body heat retaining step for maintaining the first elastic body at a second temperature; a substrate placing step for placing the substrate to be polished on the heat-soluble adhesive; and the substrate to be polished. It comprises a substrate pressurizing step for applying pressure by a second elastic body, and a removing step for taking out the substrate to be polished together with a base for attaching the substrate to be polished.

  According to the method for fixing a crystal substrate of the present invention, since the adhesive is applied to the pasting surface of the pasting base in advance, it is possible to prevent the abrasive from wrapping around after the pasting of the substrate. Furthermore, since the adhesive is uniformly applied to the entire surface of the sticking table, the local adhesive is not retained and the substrate can be more uniformly fixed to the sticking table.

  An example of the crystal substrate fixing method of the present invention will be described in detail with reference to the drawings. Note that “SORI” in this specification refers to a value measured by a measuring instrument such as a laser oblique incidence interferometer.

(Embodiment 1)
FIG. 1 illustrates a process of a crystal substrate fixing method according to a first embodiment of the present invention. The apparatus used for fixing the substrate includes a lower chamber 10 in which the substrate 1 and the sticking table 2 are installed, an adhesive 3, and an upper chamber A 11 having an elastic body 8 for pressurizing the substrate 1. The lower chamber 10 and the upper chamber A11 are respectively connected to the intake / exhaust port 6 and the intake / exhaust port 7 so as to be able to pressurize and depressurize the inside of the lower chamber 10 and the elastic body 8.

  Fig.1 (a) shows the application | coating process of an adhesive agent. A heat-soluble adhesive 3 is applied on the sticking table 2 in the lower chamber 10 and heated by the heater 4 in the lower chamber 10. Here, the application position of the adhesive 3 is determined by an adhesive guide 5.

  FIG. 1B shows a pressing process of the adhesive 3. The outer walls of the lower chamber 10 and the upper chamber A11 are brought into contact with each other, and the space between the lower chamber 10 and the upper chamber A11 is decompressed through the intake / exhaust port 6. Further, pressurization is performed through the intake / exhaust port 7 to expand the elastic body 8, and the adhesive 3 is uniformly formed on the sticking table 2. After the adhesive 3 is formed, pressurization from the intake / exhaust port 7 is released, and then the decompression from the intake / exhaust port 6 is released. Thereafter, the upper chamber A11 is separated from the lower chamber 10. Then, the adhesive 3 attached to the elastic body 8 is removed.

  FIG. 1C is a process of placing the substrate 1 on the adhesive 3. Here, the guide 9 for the substrate is replaced with the guide 5 for the adhesive. When the substrate 1 is installed, the substrate 1 must be completely covered with the adhesive 3 pressed in FIG.

  FIG. 1D shows a pressurizing process of the substrate 1. The outer walls of the lower chamber 10 and the upper chamber A11 are brought into contact with each other, and the space between the lower chamber 10 and the upper chamber A11 is decompressed through the intake / exhaust port 6. Further, pressure is applied through the intake / exhaust port 7 to inflate the elastic body 8 and pressurize the substrate 1 to the sticking table 2. After about 1 minute from the start of pressurization, heating by the heater 4 is stopped, and after the substrate 1 and the mounting base 2 are sufficiently cooled, the pressurization from the intake / exhaust port 7 is released, and then the intake / exhaust port 6 Release the vacuum from. The cooling method may be an air cooling method, but can be more effectively cooled by using a water cooling method.

  FIG. 1E shows a process of taking out the substrate 1 and the sticking table 2. After separating the upper chamber A11 from the lower chamber 10 and removing the substrate guide 9, the substrate 1 fixed to the affixing stand 2 is taken out.

  The substrate 1 is assumed to be the substrate 1 immediately after slicing the ingot material or the substrate 1 that has been subjected to rough polishing on one side. It is preferable that the edge portion of the substrate 1 be beveled (chamfered). This is to prevent damage to the elastic body 8 when the elastic body 8 presses the substrate 1.

  Further, for example, a board having a smaller area than that of the substrate 1 as shown in FIG. 2A is used as a spacer, and the substrate 1 is placed on the center of the substrate 1 and pressed to apply the substrate 1 to the affixing base 2 more uniformly. Can be fixed. It is also effective when a substrate 1 having a large SORI, such as a SiC single crystal substrate, is fixed to the affixing base 2 or when a plurality of substrates 1 are affixed to the affixing base 2 at a time. In this case, in order to suppress damage to the substrate 1 due to the spacer, it is also effective to put medicine wrapping paper or the like between the substrate 1 and the spacer. The medicine wrap also serves to prevent the elastic body 8 from adhering to the substrate 1 or the substrate guide 9 by the adhesive 3. In order to prevent damage to the elastic body 8 by the spacer, it is preferable to bevel the edge portion of the spacer. The material of the spacer is preferably the same as that of the substrate 1 or a material having a hardness slightly softer than that of the substrate 1. As shown in FIG. 2B, the spacer may be installed on the substrate 1 in the step of installing the substrate 1 of FIG.

  Since the affixing stand 2 becomes a weight in the rough polishing process as it is, it is preferably a hard material that is not easily deformed. In general, ceramics such as alumina are preferred. Moreover, since it becomes a reference surface when the board | substrate 1 is fixed, the sticking surface of the sticking stand 2 and its back surface need to be flat and parallel.

  The adhesive 3 is heat-soluble. For example, a shift wax manufactured by Nikka Seiko may be used. If the substrate 1 has a size of 2 inches to 3 inches, the amount applied to the sticking table 2 may be about 0.2 to 0.3 g per sheet, and is applied to the vicinity of the center of the substrate sticking portion of the sticking table 2. Although the set temperature of heating by the heater 4 varies depending on the adhesive 3 to be used, it should be 20 ° C. or more of the softening point of the adhesive 3 generally used and not more than the heat resistance temperature of the elastic body 8. When the set temperature is low, the viscosity of the adhesive 3 is increased, and it is difficult to sufficiently stretch the adhesive 3 to the substrate pasting portion of the pasting base 2 by pressurization with the elastic body 8. On the contrary, when the set temperature is high, the elastic body 8 tends to deteriorate. When the application amount of the adhesive 3 is too small, the abrasive wraps around the back surface of the substrate 1 during rough polishing. On the other hand, when the application amount of the adhesive 3 is too large, the adhesive 3 wraps around the back surface of the substrate guide 9 in FIG. 1 (e), and the substrate guide 9 is also fixed to the sticking table 2.

  The heater 4 is used for heating the adhesive 3. The heater 4 in the lower chamber 10 heats up to the process of cooling the substrate 1 in FIG.

  The inner diameter of the adhesive guide 5 is preferably the same as the substrate 1 or about 2 to 3 mm smaller. This is because the substrate 1 is installed at the position of the adhesive 3 in FIG. The back surface of the adhesive guide 5 is preferably flat so that the adhesive 3 can be brought into close contact with the sticking table 2 so that the adhesive 3 does not enter between the sticking table 2 and the adhesive guide 5.

  On the other hand, the inner diameter of the substrate guide 9 needs to take into account an error in the diameter of the substrate 1, but generally only needs to be about 5 mm larger than the substrate 1. Further, the portion of the guide 9 for the substrate adjacent to the adhesive 3 and the substrate 1 is formed by the adhesive 3 protruding from between the substrate 1 and the attaching base 2 after the adhesive 3 is cooled in FIG. In order to make it difficult for the guide 9 for fixing to be fixed to the affixing base 2, it is preferable to form a gap a as shown in FIG. 3 on the contact surface side of the guide 9 for the substrate to the affixing base 2. . As described above, the substrate 1 is preferably beveled at the edge portion to prevent damage to the elastic body 8. At this time, the shape of the edge portion of the substrate 1 has an inclination as shown in FIG. 3, and the gap “a” of the guide 9 for the substrate must be lower than the height “b” where the substrate 1 has the maximum diameter. This is because the end surface of the substrate 1 may enter between the sticking table 2 and the substrate guide 9.

  The elastic body 8 may be heat-resistant silicon rubber or the like. The pressing force applied to the elastic body 8 may be about 0.3 MPa when a 2 inch or 3 inch size SiC substrate 1 having a SORI of 20 μm or less is fixed to the single sticking table 2. When the number of substrates 1 with SORI of 20 μm or more or the number of pasted substrates increases, when the size of the substrate 1 increases, it is necessary to further increase the applied pressure. In addition, when the adhesive 3 is pressed in FIG. 1B, a pressure of about 0.1 MPa to 0.3 MPa may be applied to the elastic body 8.

  Hereinafter, examples of the crystal substrate fixing method of the present invention will be described in more detail. In each of the examples and comparative examples, a 3 inch size SiC single crystal substrate was used as the substrate 1. The substrate 1 is preliminarily made of diamond abrasive grains having an average particle size of 9 μm on one side, and first-stage rough polishing is performed on a cast iron surface plate. The rough grinding of the 2nd step was performed with the board. The surface not subjected to rough polishing is a surface not subjected to polishing treatment. The edge portion of the substrate 1 was chamfered by beveling on both sides. As the adhesive 3, shift wax 582W made by Nikka Seiko having a softening point of 52 ° C. was used. The pressure applied to the adhesive 3 by the elastic body 8 was 0.3 MPa.

  In each of the examples and comparative examples, the fixing accuracy when the surface of the substrate 1 subjected to rough polishing was fixed to the sticking table 2 was confirmed. Further, it was confirmed whether or not the adhesive 3 protruded from the guide 9 for the substrate when the substrate 1 was pressed with the elastic body 8. Then, the substrate 1 was fixed to the sticking table 2 and then rough polishing was performed. After the rough polishing, the substrate 1 was removed, and the presence or absence of the abrasive wrapping around the back surface of the substrate 1 was confirmed.

  In each of the examples and comparative examples, diamond abrasive grains having an average particle size of 9 μm were used, and rough polishing was performed using a cast iron surface plate. Each example and comparative example was carried out 10 times each.

Example 1
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking table 2 was 0.2 g. The pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa.

(Example 2)
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking base 2 was 0.1 g. The pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa.

(Example 3)
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking base 2 was 0.5 g. The pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa.

Example 4
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 70 ° C., and the amount of the adhesive 3 applied to the sticking base 2 was 0.2 g. The pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa.

(Example 5)
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 110 ° C., and the amount of the adhesive 3 applied to the sticking base 2 was 0.2 g. The pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa.

(Example 6)
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking table 2 was 0.2 g. The pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa. Further, a 2-inch SiC material was placed on the substrate 1 as a spacer, and the substrate 1 was pressurized. The edge portion of the spacer was beveled.

(Example 7)
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking table 2 was 0.2 g. The pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was set to 0.1 MPa.

(Comparative Example 1)
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking table 2 was 0.2 g. The pressure applied to the substrate 1 by the elastic body 8 was 0.3 MPa. The adhesive 3 was pressed simultaneously with the substrate 1 without being pressed by the elastic body 8.

  Examples 1 to 7 and Comparative Example 1 were carried out, and the fixing accuracy of the substrate 1 to the affixing base 2 and the presence / absence of the wraparound of the abrasive to the back surface of the substrate 1 after rough polishing, It was confirmed whether or not the adhesive 3 protruded from the guide 9.

  Examples 1 to 3 were carried out to confirm the effective range of the adhesive application amount, and Examples 1, 4 and 5 were carried out to confirm the effective range of the heater set temperature. It is a thing. Furthermore, Example 1 and Example 6 were performed for confirming the effectiveness of spacer installation, and Example 1 and Example 7 were for confirming pressurization to the substrate.

  “Fixing accuracy” in Table 1 is an item for confirming whether or not the substrate 1 is evenly attached to the attaching base 2. The height of the central part 1 and the peripheral part 4 of the substrate 1 after the substrate 1 is fixed to the affixing stand 2 with a height gauge is confirmed, and the inclination, the central part 1 of the substrate 1 and the peripheral part 4 points are checked. It was confirmed whether there was a difference in height. As a result of performing each example and comparative example 10 times, the case where the inclination not caused by the thickness unevenness of the substrate 1 and the difference in height between the central portion and the outer peripheral portion of the substrate 1 are not performed in all 10 times, When there was an inclination not caused by the thickness unevenness of the substrate 1 or there was a difference in height between the central portion and the outer peripheral portion of the substrate 1, it was marked as x. Here, whether there is an inclination not caused by uneven thickness of the substrate 1 or a difference in height between the central portion and the outer peripheral portion of the substrate 1 is determined based on whether there is a difference of 20 μm or more.

  The “presence / absence of wraparound to the abrasive” in Table 1 indicates that after the substrate 1 is fixed to the affixing base 2, rough polishing is performed, and the abrasive flows into the back side of the substrate 1 during rough polishing, and the back surface of the substrate 1 is processed. It is an item that has been confirmed whether or not. As a result of carrying out each example and comparative example 10 times, it was evaluated as ◯ when the back surface of the substrate 1 was not processed, and × when the back surface of the substrate was processed.

  “The presence or absence of the adhesive sticking out to the substrate guide” in Table 1 indicates that the adhesive 3 on the back surface of the substrate 1 is the guide 9 for the substrate when the substrate 1 is pressed against the base 2 by the elastic body 8. It is the item which confirmed whether it adhered to. As a result of carrying out each example and comparative example 10 times, when the adhesive 3 is not attached to the guide 9 for the substrate, it is indicated as ◯ when the adhesive 3 is attached to the guide 9 for the substrate. .

  Comprehensive evaluation in Table 1 is ◯ when the results of “fixing accuracy”, “presence / absence of wrap around abrasives”, and “presence / absence of adhesive sticking out to substrate guide” are all ◯, and other cases X. The results confirmed for the above items are shown in Table 1.

  From the comparison of the result of Example 1 and the result of Comparative Example 1, by pressing the adhesive 3 with the elastic body 8 in advance and then pressing the substrate 1, the fixing accuracy of the substrate is improved, and the substrate during rough polishing 1 It was confirmed that the sneaking of the abrasive into the back surface could be prevented. Further, the substrate 1 could be fixed to the affixing table 2 well without the adhesive sticking out to the substrate guide.

  The following results were obtained from the results of Example 2 and Example 3. When the amount of the adhesive 3 applied to the affixing base 2 is small, the adhesive 3 does not spread over the entire area where the substrate 1 is installed, and as a result, the fixing accuracy of the substrate 1 is deteriorated, and the rough polishing is performed on the back surface of the substrate 1. It becomes a factor that wraparound of the agent occurs. On the other hand, when the amount of the adhesive 3 applied to the sticking table 2 is large, the adhesive 3 adheres to the guide 9 for the substrate, and the guide 9 for the substrate is also fixed to the sticking table 2.

  In the case of fixing the 2 inch or 3 inch size substrate 1 to the affixing table 2, when the amount of adhesive 3 applied to the affixing table 2 was changed as in Example 2 and Example 3 and confirmed, When approximately 0.2 to 0.3 g of the adhesive 3 was used, stable and good results were obtained.

  The following results were obtained from the results of Example 4 and Example 5. When the set temperature of the heater 4 is low, the adhesive does not sufficiently soften and the adhesive 3 does not spread over the entire area where the substrate 1 is installed. As a result, the fixing accuracy of the substrate 1 deteriorates, and the rough polishing is applied to the back surface of the substrate 1. This is a factor that causes the polishing agent to wrap around. On the other hand, when the set temperature of the heater 4 was high, the substrate 1 could be fixed to the sticking table 2 without any particular problem by removing the adhesive adhering to the elastic body 8 each time before pressurizing the substrate 1.

  When the set temperature of the heater 4 was changed and confirmed as in Example 4 and Example 5, good results were obtained if the set temperature was 20 ° C. or higher from the softening point of the adhesive 3.

  From the result of Example 6, it was confirmed that there is no problem in applying the spacer between the substrate 1 and the elastic body 8. Further, the accuracy of fixing the substrate 1 to the affixing base 2 was better with the spacer than with Example 1 without the spacer.

  From the results of Example 7, the following could be confirmed. When the pressure applied to the substrate 1 by the elastic body 8 is weak, the polishing agent does not wrap around during rough polishing, but the substrate 1 is not sufficiently pressed against the affixing base 2, so that the fixing accuracy of the substrate 1 to the affixing base 2 is high. Gets worse. The upper limit of the pressure applied by the elastic body 8 is not constant because it is influenced by the rigidity of the apparatus used, the material, thickness, hardness, and shape of the substrate 1, and the size and quantity of defects, but the SORI is 20 μm or less. In the case of fixing a single 2 inch or 3 inch size SiC single crystal substrate 1 to the affixing base 2, the substrate 1 could be fixed to the affixing base 2 satisfactorily with a pressure of about 0.3 MPa.

  From the above results, 0.2 to 0.3 g of the adhesive 3 is applied to the sticking table 2 heated by the heater 4 at a temperature 20 ° C. or more higher than the softening point of the adhesive 3, and then the elastic body 8 is pressed in advance. When the adhesive 3 is stretched and the adhesive 3 adhering to the elastic body 8 is removed, and the substrate 1 is appropriately pressed against the sticking base 2 with the elastic body 8, the substrate 1 is accurately applied to the sticking base 2. Can be fixed. Further, it is possible to prevent the polishing agent from flowing into the back surface of the substrate 1 during rough polishing and to prevent the back surface of the substrate 1 from being processed.

(Embodiment 2)
FIG. 4 illustrates the process of the crystal substrate fixing method according to the second embodiment of the present invention. The apparatus used for fixing the substrate includes a lower chamber 10 in which the substrate 1 and the attaching base 2 are installed, an upper chamber B12 having an elastic body 8 for pressurizing the adhesive 3, and an elastic body 8 for pressurizing the substrate 1. And upper chamber A11. The lower chamber 10, the upper chamber A11, and the upper chamber B12 are respectively connected to the intake / exhaust port 6 and the intake / exhaust port 7 so as to be able to pressurize and depressurize the lower chamber 10 and the elastic body 8.

  The difference between the configuration of the first embodiment and the configuration of the second embodiment is that the upper chamber B12 is used in FIGS. 4 (a) and 4 (b). In other words, by disposing the elastic body 8 that presses the adhesive 3 and the elastic body 8 that presses the substrate 1 in different upper chambers, it is not necessary to remove the adhesive 3 adhering to the elastic body 8, and a more continuous operation can be achieved. It becomes possible.

  FIG. 4A shows an adhesive application process. A heat-soluble adhesive 3 is applied on the sticking table 2 in the lower chamber 10 and heated by the heater 4 in the lower chamber 10. Here, the application position of the adhesive 3 is determined by an adhesive guide 5.

  FIG. 4B shows the pressing process of the adhesive 3. The outer walls of the lower chamber 10 and the upper chamber B12 are brought into contact with each other, and the space between the lower chamber 10 and the upper chamber B12 is decompressed through the intake / exhaust port 6. Further, pressurization is performed through the intake / exhaust port 7 to expand the elastic body 8, and the adhesive 3 is uniformly formed on the sticking table 2. After the adhesive 3 is formed, pressurization from the intake / exhaust port 7 is released, and then the decompression from the intake / exhaust port 6 is released. Thereafter, the upper chamber B12 is separated from the lower chamber 10. Then, the heater 4 in the upper chamber B12 is heated so that the adhesive 3 attached to the elastic body 8 does not solidify. When the adhesive 3 is solidified, the surface of the elastic body 8 is covered with the cured adhesive, and the substrate 1 cannot be uniformly pressed.

  FIG. 4C is a process of placing the substrate 1 on the adhesive 3. Here, the upper chamber A11 is prepared, and the guide 9 for the substrate is replaced with the guide 5 for the adhesive. When the substrate 1 is installed, the substrate 1 must be completely covered with the adhesive 3 pressed in FIG. 4B.

  FIG. 4D shows the pressurizing process of the substrate 1. The outer walls of the lower chamber 10 and the upper chamber A11 are brought into contact with each other, and the space between the lower chamber 10 and the upper chamber A11 is decompressed through the intake / exhaust port 6. Further, pressure is applied through the intake / exhaust port 7 to inflate the elastic body 8 and pressurize the substrate 1 to the sticking table 2. After about 1 minute from the start of pressurization, heating by the heater 4 is stopped, and after the substrate 1 and the mounting base 2 are sufficiently cooled, the pressurization from the intake / exhaust port 7 is released, and then the intake / exhaust port 6 Release the vacuum from. The cooling method may be an air cooling method, but can be more effectively cooled by using a water cooling method.

  FIG. 4E shows a process of taking out the substrate 1 and the sticking table 2. After separating the upper chamber A11 from the lower chamber 10 and removing the substrate guide 9, the substrate 1 fixed to the affixing stand 2 is taken out.

  The upper chamber B12 has a heater 4 in addition to the elastic body so that the adhesive 3 adhered to the elastic body 8 is cooled and not solidified when the process of fixing the crystal substrate in the present invention is continuously performed. Yes. The set temperature of heating by the heater 4 is preferably the same as the set temperature of the heater 4 in the lower chamber 10. This is because when there is a temperature difference between the two heaters 4, the viscosity of the adhesive 3 also varies. Moreover, although it is set temperature of the heater 4, when using in Embodiment 2, it is the temperature of 20 to 50 degreeC of the softening point of the adhesive agent 3 generally used, and below the heat-resistant temperature of the elastic body 8. There is a need to. The reason why the set temperature must be 20 ° C. or higher and the reason why the set temperature must be lower than the heat resistant temperature of the elastic body 8 are the same as in the first embodiment. The reason why the softening point of the adhesive 3 that uses the set temperature must be 50 ° C. or lower is that the adhesive 3 adheres to the elastic body 8 in the upper chamber B12 and is always heated, so that the adhesive 3 itself It is because it becomes easy to deteriorate.

  Hereinafter, examples of the crystal substrate fixing method of the present invention will be described in more detail. In each of the examples and comparative examples, a 3 inch size SiC single crystal substrate was used as the substrate 1. The substrate 1 is preliminarily made of diamond abrasive grains having an average particle size of 9 μm on one side, and first-stage rough polishing is performed on a cast iron surface plate. The rough grinding of the 2nd step was performed with the board. The surface not subjected to rough polishing is a surface not subjected to polishing treatment. The edge portion of the substrate 1 was chamfered by beveling on both sides. As the adhesive 3, shift wax 582W made by Nikka Seiko having a softening point of 52 ° C. was used. The pressure applied to the adhesive 3 by the elastic body 8 was 0.3 MPa.

  In each of the examples and comparative examples, the fixing accuracy when the surface of the substrate 1 subjected to rough polishing was fixed to the sticking table 2 was confirmed. Further, it was confirmed whether or not the adhesive 3 protruded from the guide 9 for the substrate when the substrate 1 was pressed with the elastic body 8. And after fixing the board | substrate 1 to the sticking stand 2, rough grinding | polishing was performed, the board | substrate 1 was removed after rough grinding | polishing, and it was confirmed whether there was any wraparound of the abrasive | polishing agent to the board | substrate 1 back surface. Finally, after each example was performed a plurality of times, whether or not the adhesive 3 adhered to the elastic body 8 in the upper chamber B12 was changed with time was also confirmed.

  In each of the examples and comparative examples, diamond abrasive grains having an average particle size of 9 μm were used, and rough polishing was performed using a cast iron surface plate. Each example and comparative example was carried out 10 times each. The comparative example was performed under the same conditions as the comparative example of the first embodiment.

(Example 8)
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking table 2 was 0.2 g. The pressure applied to the adhesive 3 used the upper chamber B12, and the pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa.

Example 9
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking base 2 was 0.1 g. The pressure applied to the adhesive 3 used the upper chamber B12, and the pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa.

(Example 10)
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking base 2 was 0.5 g. The pressure applied to the adhesive 3 used the upper chamber B12, and the pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa.

Example 11
As the substrate 1, a 3 inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 70 ° C., and the amount of the adhesive 3 applied to the sticking base 2 was 0.2 g. The upper chamber B12 was used for pressurization to the adhesive 3, and the pressurization to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa.

Example 12
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 110 ° C., and the amount of the adhesive 3 applied to the sticking base 2 was 0.2 g. The pressure applied to the adhesive 3 used the upper chamber B12, and the pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa.

(Example 13)
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking table 2 was 0.2 g. The pressure applied to the adhesive 3 used the upper chamber B12, and the pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was 0.3 MPa. Further, a 2-inch SiC material was placed on the substrate 1 as a spacer, and the substrate 1 was pressurized. The edge portion of the spacer was beveled.

(Example 14)
As the substrate 1, a 3-inch SiC single crystal substrate having an SOI of 20 μm was prepared. The set temperature of the heater 4 was 90 ° C., and the amount of the adhesive 3 applied to the sticking table 2 was 0.2 g. The pressure applied to the adhesive 3 used the upper chamber B12, and the pressure applied to the substrate 1 by the elastic body 8 in the upper chamber A11 was set to 0.1 MPa.

  Examples 8 to 14 and Comparative Example 1 were carried out, and the fixing accuracy of the substrate 1 to the affixing base 2 and the presence / absence of the wraparound of the polishing agent to the back surface of the substrate 1 after rough polishing, Whether or not the adhesive 3 protruded from the guide 9 and each change of the adhesive 3 attached to the upper chamber B12 when each example was performed a plurality of times were confirmed.

  Examples 8 to 10 were carried out to confirm the effective range of the adhesive application amount, and Examples 8, 11 and 12 were carried out to confirm the effective range of the heater set temperature. It is a thing. Furthermore, Example 8 and Example 13 were performed in order to confirm the effectiveness of spacer installation, and Example 8 and Example 14 were for confirming the pressurization to the substrate in each embodiment. It is what went to.

  “Fixing accuracy” in Table 2 is an item for confirming whether or not the substrate 1 is evenly attached to the attaching table 2. The height of the central part 1 and the peripheral part 4 of the substrate 1 after the substrate 1 is fixed to the affixing stand 2 with a height gauge is confirmed, and the inclination, the central part 1 of the substrate 1 and the peripheral part 4 points are checked. It was confirmed whether there was a difference in height. As a result of performing each example and comparative example 10 times, the case where the inclination not caused by the thickness unevenness of the substrate 1 and the difference in height between the central portion and the outer peripheral portion of the substrate 1 are not performed in all 10 times, When there was an inclination not caused by the thickness unevenness of the substrate 1 or there was a difference in height between the central portion and the outer peripheral portion of the substrate 1, it was marked as x. Here, whether there is an inclination not caused by uneven thickness of the substrate 1 or a difference in height between the central portion and the outer peripheral portion of the substrate 1 is determined based on whether there is a difference of 20 μm or more.

  The “presence / absence of wrapping around the abrasive” in Table 2 indicates that after the substrate 1 is fixed to the affixing base 2, rough polishing is performed, and the abrasive flows into the back side of the substrate 1 during rough polishing, and the back surface of the substrate 1 is processed. It is an item that has been confirmed whether or not. As a result of carrying out each example and comparative example 10 times, it was evaluated as ◯ when the back surface of the substrate 1 was not processed, and × when the back surface of the substrate was processed.

  “The presence or absence of the adhesive sticking out to the substrate guide” in Table 2 indicates that the adhesive 3 on the back surface of the substrate 1 is the guide 9 for the substrate when the substrate 1 is pressed against the base 2 by the elastic body 8. It is the item which confirmed whether it adhered to. As a result of carrying out each example and comparative example 10 times, when the adhesive 3 is not attached to the guide 9 for the substrate, it is indicated as ◯ when the adhesive 3 is attached to the guide 9 for the substrate. .

  The “state of the adhesive adhered to the upper chamber” in Table 2 indicates that the adhesive 3 that adheres to the elastic body 8 when the adhesive 3 is pressed against the sticking table 2 by the elastic body 8 using the upper chamber B12. It is an item for confirming changes. As a result of carrying out each example 10 times, when the adhesive 3 adhered to the elastic body 8 did not change or discolor, ○, and when the adhesive 3 adhered to the elastic body 8 changed or discolored, × did. In Comparative Example 1, since the upper chamber B12 was not used, this item was excluded from the subject.

  The overall evaluation in Table 2 is the result of “fixing accuracy”, “presence / absence of sneaking into abrasive”, “presence / absence of adhesive sticking out to substrate guide”, “state of adhesive attached to upper chamber” When it was ○, it was ○, and when it was not so, it was ×. The results confirmed for the above items are shown in Table 2.

  From the comparison of the result of Example 8 and the result of Comparative Example 1, by pressing the adhesive 3 with the elastic body 8 in advance and then pressing the substrate 1, the fixing accuracy of the substrate is improved, and the substrate during rough polishing 1 It was confirmed that the sneaking of the abrasive into the back surface could be prevented. Further, the substrate 1 could be fixed to the affixing table 2 well without the adhesive sticking out to the substrate guide. Furthermore, it was confirmed that there was no deterioration of the adhesive adhered to the upper chamber B12.

  The following results were obtained from the results of Example 9 and Example 10. When the amount of the adhesive 3 applied to the affixing base 2 is small, the adhesive 3 does not spread over the entire area where the substrate 1 is installed, and as a result, the fixing accuracy of the substrate 1 is deteriorated, and the rough polishing is performed on the back surface of the substrate 1. It becomes a factor that wraparound of the agent occurs. On the other hand, when the amount of the adhesive 3 applied to the sticking table 2 is large, the adhesive 3 adheres to the guide 9 for the substrate, and the guide 9 for the substrate is also fixed to the sticking table 2.

  If the 2 inch or 3 inch size substrate 1 is to be fixed to the affixing base 2, the amount of adhesive 3 applied to the affixing base 2 was confirmed as in Example 9 and Example 10, When approximately 0.2 to 0.3 g of the adhesive 3 was used, stable and good results were obtained.

  The following results were obtained from the results of Example 11 and Example 12. When the set temperature of the heater 4 is low, the adhesive does not sufficiently soften and the adhesive 3 does not spread over the entire area where the substrate 1 is installed. As a result, the fixing accuracy of the substrate 1 deteriorates, and the rough polishing is applied to the back surface of the substrate 1. This is a factor that causes the polishing agent to wrap around. On the other hand, when the set temperature of the heater 4 was high, the adhesive 3 was easily deteriorated due to high temperature, and the adhesive 3 attached to the upper chamber B12 was liable to change with time.

  When the setting temperature of the heater 4 was changed as in Example 11 and Example 12 and confirmed, good results were obtained if the setting temperature was 20 ° C. or more and 50 ° C. or less from the softening point.

  From the result of Example 13, it was confirmed that there is no problem in applying the spacer between the substrate 1 and the elastic body 8. Further, the accuracy of fixing the substrate 1 to the affixing base 2 was better with the spacer than with Example 8 without the spacer.

  The following could be confirmed from the results of Example 14. When the pressure applied to the substrate 1 by the elastic body 8 is weak, the polishing agent does not wrap around during rough polishing, but the substrate 1 is not sufficiently pressed against the affixing base 2, so that the fixing accuracy of the substrate 1 to the affixing base 2 is high. Gets worse. The upper limit of the pressure applied by the elastic body 8 is not constant because it is influenced by the rigidity of the apparatus used, the material, thickness, hardness, and shape of the substrate 1, and the size and quantity of defects, but the SORI is 20 μm or less. In the case of fixing a single 2 inch or 3 inch size SiC single crystal substrate 1 to the affixing base 2, the substrate 1 could be fixed to the affixing base 2 satisfactorily with a pressure of about 0.3 MPa.

  From the above results, 0.2 to 0.3 g of the adhesive 3 was applied to the sticking table 2 heated at a temperature of 20 ° C. or more and 50 ° C. or less from the softening point of the adhesive 3 by the heater 4, and then the elastic body 8 When the pressure is applied and the adhesive 3 is stretched, and then the substrate 1 is appropriately pressed to the sticking base 2 with the elastic body 8 by another elastic body 8, the substrate 1 is fixed to the sticking base 2 with high accuracy. it can. Further, it is possible to prevent the polishing agent from flowing into the back surface of the substrate 1 during rough polishing and to prevent the back surface of the substrate 1 from being processed.

  According to the method for fixing a crystal substrate according to the present invention, the substrate can be fixed to the affixing base with high precision, and at the same time, the polishing agent can be prevented from wrapping around the back surface of the substrate. This is useful as a method for fixing the substrate.

  Further, according to the method for fixing a crystal substrate according to the present invention, the substrate can be accurately fixed to the affixation base, and at the same time, the polishing agent can be prevented from wrapping around the back surface of the substrate. It is also useful as a substrate fixing method during polishing for the production of ceramics, oxides and the like.

The figure which shows an example of the board | substrate fixing method of this invention The figure which showed an example of the spacer of the board | substrate fixing method of this invention, and its use The figure which showed the height relationship of the board | substrate and the guide for board | substrates in the board | substrate fixing method of this invention The figure which shows an example of the board | substrate fixing method of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Attaching stand 3 Adhesive 4 Heater 5 Adhesive guide 6 Air intake / exhaust port 7 Air intake / exhaust port 8 Elastic body 9 Substrate guide 10 Lower chamber 11 Upper chamber A
12 Upper room B

Claims (12)

An application step of applying a heat-soluble adhesive by heating a sticking table for fixing the substrate to be polished;
An adhesive pressing step of pressing the heat-soluble adhesive with an elastic body;
A removal step of removing the heat-soluble adhesive adhered to the elastic body;
A substrate installation step of installing the substrate to be polished on the heat-soluble adhesive;
A substrate pressing step of pressing the substrate to be polished by the elastic body;
A step of taking out the substrate to be polished together with a base for the substrate to be polished,
A method for fixing a crystal substrate comprising: 2. The crystal substrate fixing method according to claim 1, wherein, in the substrate installation step, a spacer smaller than the substrate to be polished whose end surface is chamfered is disposed on the substrate to be polished so that the center thereof coincides with the center of the substrate to be polished. . The method for fixing a crystal substrate according to claim 1, wherein the heating temperature of the sticking table is in a range of 20 ° C. or more and a heat resistant temperature of the elastic body or more than a softening point of the heat-soluble adhesive. The crystal substrate fixing method according to claim 1, wherein the substrate to be polished is made of SiC. The crystal substrate fixing method according to claim 4, wherein the substrate is a SiC single crystal substrate having a maximum diameter of 2 to 3 inches and an SORI of 20 μm or less. The method for fixing a crystal substrate according to claim 5, wherein the amount of the heat-soluble adhesive applied is in the range of 0.2 g to 0.3 g per substrate to be polished. An application step of applying a heat-soluble adhesive by heating a sticking base for fixing a substrate to be polished to a first temperature;
An adhesive pressing step of pressing the heat-soluble adhesive with a first elastic body;
An elastic body heat retaining step for maintaining the first elastic body at a second temperature;
A substrate installation step of installing a substrate to be polished on the heat-soluble adhesive;
A substrate pressing step of pressing the substrate to be polished by a second elastic body;
A step of taking out the substrate to be polished together with a base for the substrate to be polished,
A method for fixing a crystal substrate comprising: The crystal substrate fixing method according to claim 7, wherein, in the substrate installation step, a spacer smaller than the substrate to be polished whose end face is chamfered is disposed on the substrate to be polished so that the center thereof coincides with the center of the substrate to be polished. . The method for fixing a crystal substrate according to claim 7, wherein the first and second temperatures are in a range from 20 ° C. to 50 ° C. from a softening point of the heat-soluble adhesive. The crystal substrate fixing method according to claim 7, wherein the substrate to be polished is made of SiC. The crystal substrate fixing method according to claim 10, wherein the substrate is a SiC single crystal substrate having a maximum diameter of 2 to 3 inches and a SORI of 20 μm or less. The method for fixing a crystal substrate according to claim 11, wherein an application amount of the heat-soluble adhesive is 0.2 g or more and 0.3 g or less per substrate to be polished.

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