JP5145131B2 - Manufacturing method of polishing head - Google Patents

Description

  The present invention relates to a method for manufacturing a polishing head for holding a workpiece when polishing the surface of the workpiece, and a polishing apparatus having a polishing head manufactured by the method, and in particular, holding a workpiece with a rubber film. The present invention relates to a polishing head manufacturing method and a polishing apparatus including the manufactured polishing head.

As a device for polishing the surface of a workpiece such as a silicon wafer, there are a single-side polishing device for polishing a workpiece one side at a time and a double-side polishing device for polishing both surfaces simultaneously.
A typical single-side polishing apparatus includes, for example, a surface plate 88 to which a polishing cloth 89 is attached, an abrasive supply mechanism 90, a polishing head 82, and the like as shown in FIG. In such a polishing apparatus 81, the workpiece W is held by the polishing head 82, the polishing agent is supplied from the polishing agent supply mechanism 90 onto the polishing cloth 89, and the surface plate 88 and the polishing head 82 are rotated to rotate the workpiece W. Polishing is performed by bringing the surface of the substrate into sliding contact with the polishing cloth 89.

  As a method of holding the work on the polishing head, there is a method of attaching the work to a flat disk-shaped plate via an adhesive such as wax. In addition, as a holding method for improving the flatness of the entire workpiece by suppressing the jumping and sagging especially at the outer periphery of the workpiece, the workpiece holding portion is made of a rubber film, and a pressurized fluid such as air is provided on the back surface of the rubber film. There is a so-called rubber chuck system in which a rubber film is inflated with a uniform pressure and a workpiece is pressed against a polishing cloth (see, for example, Patent Document 1).

  An example of the configuration of a conventional rubber chuck type polishing head is schematically shown in FIG. The main part of the polishing head 102 includes an annular rigid ring 104 made of SUS, a rubber film 103 bonded to the rigid ring 104, and an intermediate plate 105 coupled to the rigid ring 104. A sealed space 106 is defined by the rigid ring 104, the rubber film 103, and the intermediate plate 105. Further, an annular template 114 is provided concentrically with the rigid ring 104 around the lower surface of the rubber film 103. Further, the pressure of the space is adjusted by supplying a pressurized fluid to the center of the intermediate plate 105 by a pressure adjusting mechanism 107. Further, a pressing means (not shown) for pressing the intermediate plate 105 in the direction of the polishing pad 109 is provided.

As a material of the rubber film 103 , Patent Document 2 discloses a rubber hardness of 10 to 100, a tensile strength of 3 to 20 MPa, a tensile elongation of 50 to 1000%, such as fluorine-based rubber, urethane rubber, silicon rubber, and ethylene propylene rubber. Various rubber materials have been proposed.
Using the thus configured polishing head 102, the work W is held on the lower surface portion of the rubber film 103 via the backing pad 113, the edge portion of the work W is held by the template 114, and the intermediate plate 105 is pressed. Then, the work W is brought into sliding contact with the polishing cloth 109 attached to the upper surface of the surface plate 108 and polished.

Japanese Patent Laid-Open No. 5-69310 JP 2005-7521 A

  By polishing the workpiece W using such a polishing head 102 that holds the workpiece W on the rubber film 103, the flatness and polishing margin uniformity of the entire workpiece W may be improved. When the production lot is different even with the material 103 or the same material, there is a problem that the flatness and the polishing margin uniformity are lowered, and a stable flatness of the workpiece W cannot be obtained.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a polishing head manufacturing method and a polishing apparatus that can stably obtain a certain flatness in polishing a workpiece W.

  In order to achieve the above object, according to the present invention, at least an annular rigid ring, a rubber film bonded to the rigid ring with a uniform tension, and a rubber film coupled to the rigid ring, the rubber film and the rigid An intermediate plate that forms a space together with the ring, and a pressure adjusting mechanism that changes the pressure of the space, holds the back surface of the work on the bottom surface of the rubber film, and places the surface of the work on a surface plate A method of manufacturing a polishing head that is polished by being brought into sliding contact with an attached polishing cloth, and at least before the rubber film is bonded to a rigid ring, a tensile test based on JIS K6251 is performed on the rubber film to obtain a strain. Using a rubber film including a step of selecting a slope value obtained by linearly approximating a stress-strain curve within 5% and having a slope value of 10 MPa or less, wherein the selected slope value is 10 MPa or less. To provide a method of manufacturing a polishing head, characterized in that to produce a polishing head and adhered to the rigid ring (claim 1).

  In this way, at least before the rubber film is bonded to the rigid ring, a tensile test based on JIS K6251 of the rubber film is performed, and a stress-strain curve within 5% of the strain is linearly approximated by the least square method. And manufacturing a polishing head by bonding to the rigid ring using a rubber film having the selected inclination value of 10 Mpa or less. When polishing a workpiece, it is possible to suppress variations in the type of rubber film and the variation in polishing stock uniformity that occurs between lots of rubber film material, and to ensure stable and good flatness A head can be manufactured.

At this time, the workpiece to be held may be a silicon single crystal wafer having a diameter of 300 mm or more.
Thus, even if the workpiece to be held is a silicon single crystal wafer having a large diameter such as 300 mm or more, the present invention can be polished with a more uniform pressing force over the entire surface of the workpiece. Flatness can be ensured.

Further, the present invention comprises at least an abrasive cloth affixed on a surface plate, an abrasive supply mechanism for supplying an abrasive onto the abrasive cloth, and an abrasive head for holding a workpiece, A polishing apparatus for holding a back surface of a work by the polishing head and polishing the surface of the work, wherein the polishing head includes at least an annular rigid ring and a rubber film bonded to the rigid ring with a uniform tension. And an intermediate plate coupled to the rigid ring and forming a space portion together with the rubber film and the rigid ring, and a pressure adjusting mechanism for changing the pressure of the space portion, the rubber film comprising the rubber film The strain obtained by a tensile test in accordance with JIS K6251 is a rubber material having a slope of 10 MPa or less obtained by linear approximation of a stress-strain curve having a strain of 5% or less. The Young's modulus of the abrasive cloth is 3 The surface of the workpiece is slidably contacted with the polishing cloth affixed on the surface plate and polished while the pressure of the space is controlled by the pressure adjusting mechanism. that provides a polishing apparatus for a.

  As described above, the polishing head includes at least an annular rigid ring, a rubber film bonded to the rigid ring with a uniform tension, and the rigid ring, and a space portion is formed together with the rubber film and the rigid ring. An inner plate to be formed; and a pressure adjusting mechanism for changing the pressure in the space. The rubber film has a stress-strain of 5% or less in a strain obtained by a tensile test according to JIS K6251 of the rubber film. It is formed of a rubber material having an inclination value obtained by linearly approximating a line of 10 MPa or less, and the Young's modulus of the polishing cloth is 3.5 MPa or less, while controlling the pressure of the space portion with the pressure adjusting mechanism. If the surface of the workpiece is polished by being brought into sliding contact with the polishing cloth affixed on the surface plate, the kind of rubber film material or the polishing average generated between lots of rubber film material Can suppress the variation in sex, it is possible to polish the workpiece stably by ensuring good flatness.

At this time, the work of the polishing, Ru can diameter of more silicon single crystal wafers 300 mm.
Thus, even if the workpiece to be polished is a silicon single crystal wafer having a large diameter such as 300 mm or more, it is more uniform over the entire surface of the workpiece by holding and polishing with the polishing head of the present invention. It is possible to polish with a pressing force of 2 to ensure good flatness.

  In the present invention, at least before the rubber film is bonded to the rigid ring, a tensile test in accordance with JIS K6251 of the rubber film is performed, and a stress-strain curve having a strain within 5% is linearly approximated. Including a step of selecting one having a value of 10 MPa or less, and a polishing head is manufactured by adhering to a rigid ring using a rubber film having the selected inclination value of 10 MPa or less. In addition, it is possible to manufacture a polishing head that can suppress variations in polishing material uniformity between types of rubber films and lots of rubber film materials, and can stably ensure good flatness. it can.

  The polishing apparatus according to the present invention includes at least an abrasive cloth affixed on a surface plate, an abrasive supply mechanism for supplying an abrasive onto the abrasive cloth, and the manufacturing method according to the present invention described above. The polishing cloth has a Young's modulus of 3.5 MPa or less, and the surface of the workpiece is polished by being brought into sliding contact with the polishing cloth affixed on the surface plate. The variation in the polishing allowance uniformity generated between the types of the materials and the lots of the rubber film material can be suppressed, and the workpiece can be polished stably while securing good flatness.

Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to this.
When using a conventional polishing head to hold the workpiece on the rubber film and polishing the workpiece, the difference in the type of rubber that is the material of the rubber film of the polishing head, As a result, there is a problem in that the polishing characteristics vary and good flatness cannot be obtained.
Moreover, it has been difficult to predict such variations in polishing characteristics from physical properties such as hardness and tensile strength of rubber raw material lots that are rubber film materials.

Accordingly, the present inventors have conducted intensive experiments and studies on the cause of such problems.
As a result, the present inventors have found the following.
In other words, regardless of the type, hardness, and tensile strength of the rubber used as the material for the rubber film, the use of a rubber material having a small stress with respect to a minute deformation having a strain of 5% or less provides good polishing margin uniformity. It turns out that it is obtained. That is, it has been found that polishing can be performed with uniform pressing force over the entire surface of the work by polishing the work using a rubber film having a small stress at the time of minute deformation as the rubber film of the polishing head. Furthermore, when polishing a workpiece using a polishing head having a template, the pressure distribution on the outer periphery of the workpiece caused by a slight difference between the height of the lower end surface of the template and the height of the lower end surface of the workpiece is alleviated, resulting in polishing. It has been found that the stock uniformity is good.

  Therefore, the present inventors conducted further diligent experiments and studies, quantified the stress at the time of minute deformation of rubber materials used as rubber films, investigated the polishing characteristics of those rubber materials, and optimized them. The present invention was completed.

FIG. 1 shows an example of a polishing head and a polishing apparatus according to the present invention.
As shown in FIG. 1, the polishing apparatus 1 has a polishing head 2 and a surface plate 8. The surface plate 8 has a disk shape, and a polishing cloth 9 for polishing the workpiece W is attached to the upper surface. A drive shaft 11 is vertically connected to the lower portion of the surface plate 8 and is rotated by a surface plate rotation motor (not shown) connected to the lower portion of the drive shaft 11.

  The polishing head 2 is installed above the surface plate 8. The polishing head 2 includes an annular rigid ring 4 and a rubber film 3 that is bonded to the rigid ring 4 with a uniform tension and has a flat bottom surface and an intermediate plate 5 that is connected to the rigid ring 4 with, for example, a bolt or the like. A sealed space 6 is formed by the rigid ring 4, the rubber film 3, and the intermediate plate 5.

Further, the polishing head 2 is rotatable around its axis.
Here, the material of the rigid ring 4 is not particularly limited, but may be a rigid material such as SUS (stainless steel). The material, shape, etc. of the intermediate plate are not particularly limited as long as the space 6 can be formed.
Here, the thickness of the rubber film 3 is not particularly limited, but can be, for example, about 1 mm.

Here, the rubber film used in the polishing head of the polishing apparatus according to the present invention has a characteristic as described below.
FIG. 2A shows an example of a stress-strain curve of a rubber film obtained by a tensile test based on JIS K6251. FIG. 2B is an enlarged view of a portion where the strain of the stress-strain curve of FIG. Here, a straight line obtained by linearly approximating a stress-strain curve with a strain of 5% or less as shown in FIG. 2B by the least square method is expressed as stress = a × strain + b.
In the present invention, a rubber film is used in which the straight line inclination a is 10 MPa or less.

Moreover, as shown in FIG. 1, the polishing slurry supply means 10 for supplying the slurry for polishing above the surface plate 8 is provided.
At this time, an annular template 14 for holding the edge portion of the workpiece W can be disposed around the lower surface portion of the rubber film 3 so that the workpiece W is not detached during polishing. In this case, the template 14 can be arranged so as to be concentric with the rigid ring 4 and protrude downward along the outer peripheral portion of the lower surface portion of the rubber film 3.

Here, the height of the lower end surface of the template 14 is the same as the height of the lower end surface of the workpiece W held, or is slightly lower than the height of the lower end surface of the workpiece W, for example by about 10 μm. can do.
Thus, if the template 14 is provided, the pressure distribution on the outer periphery of the workpiece can be relaxed, overpolishing of the outer periphery of the workpiece can be prevented, and the polishing allowance uniformity of the workpiece can be improved.

Further, the template 14 can have an outer diameter that is at least larger than the inner diameter of the rigid ring 4 and an inner diameter that is smaller than the inner diameter of the rigid ring 4.
In this way, the pressing force applied to the entire surface of the work can be made more uniform and polished.
Here, the material of the template 14 does not contaminate the workpiece W and does not cause scratches or indentations, so it is softer than the workpiece W and is not easily worn even if it is in sliding contact with the polishing pad 9 during polishing. A material with high wear resistance is preferred.

As shown in FIG. 1, the polishing apparatus 1 includes a pressure adjusting mechanism 7 that changes the pressure in the space 6 of the polishing head 2.
A pressure adjusting through hole 12 communicating with the pressure adjusting mechanism 7 is provided at the center of the intermediate plate 5, and the pressure of the space portion 6 is adjusted by supplying pressurized fluid by the pressure adjusting mechanism 7. Can be done.
In addition, it has means for pressing the intermediate plate 5 against the polishing pad 9 (not shown).

  At this time, the backing pad 13 can be attached to the lower surface of the rubber film 3. The backing pad 13 attaches the work W with water and holds the work W on the work holding surface of the rubber film 3. Here, the backing pad 13 can be made of foamed polyurethane, for example. By providing such a backing pad 13 and containing water, the workpiece W can be reliably held by the surface tension of the water contained in the backing pad 13.

As the polishing cloth 9 attached to the upper surface of the surface plate 8, a soft cloth having a Young's modulus of 3.5 MPa or less is used. By using the polishing head 2 according to the present invention in combination with a soft polishing cloth 9 having a Young's modulus of 3.5 MPa or less, the contact pressure distribution between the workpiece W and the polishing cloth 9 can be more reliably relaxed, The polishing margin uniformity of the workpiece W can be improved more reliably.
Although FIG. 1 shows a mode in which the template 14 is directly bonded to the rubber film 3, the present invention does not exclude the case where the template 14 is bonded to the rubber film 3 via the backing pad 13 or the like. .

  Using the polishing apparatus 1 configured in this way, the intermediate plate 5 is pressed in the direction of the polishing cloth 9 affixed on the surface plate 8 by an intermediate plate pressing means (not shown), and the abrasive supply mechanism 10 is used. While supplying the abrasive, the work W is brought into sliding contact with the polishing cloth 9 to polish the surface of the work W. Here, it is preferable that the intermediate plate pressing means can press the intermediate plate 5 with a uniform pressure over the entire surface using, for example, an air cylinder.

Thus, if the workpiece | work W is grind | polished using the grinding | polishing apparatus 1 which concerns on this invention, the kind of material of the rubber film 3 and the dispersion | variation in the grinding | polishing allowance uniformity which generate | occur | produce between lots of the material of the rubber film 3 will be suppressed. Therefore, the workpiece W can be polished with stable and good flatness.
Further, the pressure distribution in the outer peripheral portion of the workpiece W caused by a slight difference between the height of the lower end surface of the template 14 and the height of the lower end surface of the workpiece W can be relaxed. Therefore, even when the thickness of the workpiece W or the thickness of the template 14 varies to some extent, polishing can be performed while the pressing force applied to the workpiece W is kept uniform over the entire surface. As a result, it is possible to perform polishing with a good polishing margin uniformity of the workpiece W.

At this time, the workpiece to be polished can be a silicon single crystal wafer having a diameter of 300 mm or more.
As described above, even if the workpiece to be polished is a silicon single crystal wafer having a large diameter such as 300 mm or more, by holding and polishing with the polishing head of the present invention, more uniform pressing can be performed over the entire surface of the workpiece. Polishing can be performed with pressure, and good flatness can be ensured.

Next, a method for manufacturing a polishing head according to the present invention will be described.
As shown in FIG. 1, for example, the polishing head manufactured by the manufacturing method according to the present invention includes at least an annular rigid ring 4, a rubber film 3 bonded to the rigid ring 4 with a uniform tension, and a rigid ring 4. The middle plate 5 that forms the space 6 together with the rubber film 3 and the rigid ring 4, and the pressure adjustment mechanism 7 that changes the pressure in the space 6 are provided.

The method for producing a polishing head according to the present invention includes at least a step of selecting the rubber film 3 as described below.
First, the rubber film 3 is subjected to a tensile test based on JIS K6251 to obtain a stress-strain curve as shown in FIG. Then, from this stress-strain curve, a stress-strain curve having a strain of 5% or less as shown in FIG. 2B is extracted, and the extracted curve is linearly approximated by the least square method to obtain a straight line. This straight line is expressed as stress = a × strain + b.

Then, the rubber film 3 is selected so that the value of the straight line inclination a is 10 MPa or less.
The rubber film 3 thus selected is used to adhere to the rigid ring 4 with a uniform tension.
Here, the selection of the rubber film 3 can be performed at the stage of the rubber material before forming the rubber film 3 alone, and anyway, it may be performed before the rubber film 3 is bonded to the rigid ring 4.

  Thus, at least before the rubber film 3 is bonded to the rigid ring 4, a tensile test based on JIS K6251 of the rubber film 3 is performed, and a stress-strain curve with a strain within 5% is obtained by linear approximation. Including a step of selecting a slope having a slope value of 10 MPa or less, and manufacturing the polishing head 2 by adhering to the rigid ring 4 using the rubber film 3 having the selected slope value of 10 MPa or less. When polishing the workpiece W, it is possible to suppress variations in the type of the rubber film 3 and the variation in polishing margin uniformity that occurs between lots of the material of the rubber film 3, and stable and good flatness. A polishing head 2 that can be secured can be manufactured.

  Next, the rigid ring 4 and the intermediate plate 5 are joined together, and the space 6 is formed by the rigid ring 4, the intermediate plate 5, and the rubber film 3 bonded to the rigid ring 4. Then, the pressure adjustment mechanism 7 is disposed above the intermediate plate 5. These steps can be performed by a method similar to the conventional method.

  At this time, an annular template 14 for holding the edge portion of the workpiece W can be disposed around the lower surface portion of the rubber film 3 so that the workpiece W is not detached during polishing. In this case, the template 14 can be arranged so as to be concentric with the rigid ring 4 and protrude downward along the outer peripheral portion of the lower surface portion of the rubber film 3.

Here, the height of the lower end surface of the template 14 is the same as the height of the lower end surface of the workpiece W when it is held, or slightly protrudes downward by, for example, about 10 μm from the height of the lower end surface of the workpiece W. Can be.
Thus, if the template 14 is disposed, an excessive pressure distribution applied to the outer periphery of the workpiece can be relaxed, and a polishing head capable of improving the workpiece polishing uniformity can be obtained.

Here, the template 14 may have an outer diameter that is at least larger than an inner diameter of the rigid ring 4 and an inner diameter that is smaller than the inner diameter of the rigid ring 4.
In this way, it is possible to obtain a polishing head capable of polishing with a more uniform pressing force applied to the entire surface of the workpiece.

  Here, the material of the template 14 does not contaminate the workpiece W and does not cause scratches or indentations, so it is softer than the workpiece W and is not easily worn even if it is in sliding contact with the polishing pad 9 during polishing. It is preferable to use a material with high wear resistance.

  At this time, a backing pad 13 made of, for example, polyurethane foam can be attached to the lower surface of the rubber film 3. By providing such a backing pad 13 and including water, a polishing head that can reliably hold the workpiece W by the surface tension of the water contained in the backing pad 13 can be obtained.

At this time, the work to be held can be a silicon single crystal wafer having a diameter of 300 mm or more.
Thus, even if the workpiece to be held is a silicon single crystal wafer having a large diameter such as a diameter of 300 mm or more, the present invention can be polished with a more uniform pressing force over the entire surface of the workpiece. Sex can be secured.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples of the present invention, but the present invention is not limited thereto.

Example 1
A polishing head as shown in FIG. 1 was manufactured by the manufacturing method according to the present invention, a silicon single crystal wafer was polished by a polishing apparatus equipped with the polishing head, and polishing stock removal uniformity of the polished workpiece was evaluated.

  First, in order to select a rubber film, as rubber materials for rubber film, two types of lots A and B of ethylene propylene diene rubber (EPDM) having a rubber hardness conforming to JIS K6253 and a hardness standard of 80 ° (hereinafter referred to as “rubber film material”) , EPDM 80 ° A and EPDM 80 ° B), and silicone rubber, hardness standards 70, 80 and 90 ° (hereinafter, silicone 70 °, silicone 80 ° and silicone 90 °) were prepared. And about these 5 types of rubber materials, the JIS K6251 tensile test was done and the measurement of the stress-strain curve was implemented.

Table 1 shows the results. Moreover, the result of the obtained stress-strain curve is shown in FIG. Then, using the stress-strain curve up to 5% strain shown in FIG. 3A as shown in FIG. 3B, linear approximation is performed with stress = a × strain + b to obtain the value of the slope a. It was.
The result is shown in FIG. As shown in FIG. 4, it can be seen that even if the same type of rubber material is used, the value of the slope a varies depending on the lot. It can be seen that the rubber material of EPDM 80 ° B, silicone 70 °, and silicone 80 ° has a slope a value of 10 MPa or less.

  In this way, the rubber material of the rubber film was selected, and three polishing heads were manufactured as follows using EPDM 80 ° B, silicone 70 °, and silicone 80 ° with a slope a value of 10 MPa or less. .

  First, three kinds of rubber materials (EPDM 80 ° B, silicone 70 °, silicone 80) having an inclination a of 10 MPa or less are formed on the outer periphery of an annular rigid ring made of SUS having an outer diameter of 360 mm and closed at the top by an intermediate plate. At 1 °, a rubber film having a thickness of 1 mm was attached with a uniform tension.

  In addition, a commercially available template assembly in which a backing pad is attached to the work holding surface of the rubber film of each polishing head, and a glass epoxy laminate template having an outer diameter of 355 mm and an inner diameter of 302 mm is attached to the surface of the backing pad. Affixed with double-sided tape. Further, the surface of the rubber film molded with silicone rubber was subjected to a coating process of a thin polyurethane film of about several μm for the purpose of improving the adhesion to the double-sided tape. Further, as the template, a commercially available template assembly having a thickness of 787 μm was used so that the lower surface position of the template slightly protruded from the lower surface position of the workpiece.

  Using a polishing apparatus as shown in FIG. 1 equipped with a polishing head manufactured by such a manufacturing method of a polishing head according to the present invention, a silicon single crystal wafer having a diameter of 300 mm and a thickness of 775 μm is polished as a workpiece W. went. Note that the silicon single crystal wafer used was subjected to primary polishing on both surfaces in advance, and the edge portion was also polished. Further, a surface plate having a diameter of 800 mm was used, and a polishing cloth using a non-woven fabric impregnated with urethane and a Young's modulus of 2.2 MPa having a pressure of 3.5 MPa or less were used.

  In polishing, an alkaline solution containing colloidal silica was used as an abrasive, and the polishing head and the surface plate were rotated at 31 and 29 rpm, respectively. The polishing load (pressing force) of the workpiece W was 15 KPa. The polishing time was 3 minutes.

  The workpieces polished in this way were evaluated for polishing margin uniformity and polishing pressure distribution during polishing. The polishing margin uniformity is obtained by measuring the thickness of the workpiece before and after polishing in the diameter direction of the wafer with a flatness measuring device in the area excluding the outermost 2 mm width as the flatness guarantee area. The polishing allowance uniformity (%) = (maximum polishing allowance in the diameter direction−minimum polishing allowance in the diameter direction) / average polishing allowance in the diameter direction.

FIG. 5 shows a polishing pressure distribution in the range of 120 to 148 mm from the center in the radial direction of a wafer polished by a polishing head using EPDM 80 ° B as the rubber material of the rubber film. The pressure distribution was determined by converting the polishing allowance at each position by polishing allowance at each position / average polishing allowance × polishing load (15 MPa).
As shown in FIG. 5, the pressure drop in the outer peripheral portion of the workpiece W is suppressed compared to a polishing head using a rubber film of a rubber material of a comparative example, which will be described later, having a slope a value larger than 10 MPa, and the polishing pressure distribution It can be seen that the uniformity is good.

Further, FIG. 6 shows the result of the polishing allowance uniformity.
As shown in FIG. 6, by polishing with a polishing apparatus equipped with a polishing head using a rubber film made of EPDM 80 ° B, silicone 70 °, and silicone 80 °, polishing is performed in comparison with the results of comparative examples described later. It was found that the non-uniformity was improved and a good result of 10% or less was obtained.
Accordingly, when the polishing apparatus of the present invention including the polishing head manufactured by the manufacturing method according to the present invention is used, the type of the rubber film and the lot of the rubber film material between the lots of the material of the rubber film are polished. It was confirmed that the variation in the polishing allowance uniformity generated in step 1 can be suppressed, and good flatness can be secured stably.

(Example 2)
As the polishing cloth, except that the one having a Young's modulus of 3.2 MPa was used, only a polishing head using EPDM 80 ° B as a rubber film material was manufactured in the same manner as in Example 1, and the polishing was performed. A silicon single crystal wafer was polished by a polishing apparatus equipped with a head, and polishing stock removal uniformity was evaluated.
The result is shown in FIG. As shown in FIG. 7, it was found that the polishing allowance uniformity was improved as compared with the results of the comparative example described later, and a favorable result of 10% or less was obtained.
As shown in FIG. 7, it was found that when the Young's modulus of the polishing pad was 3.5 MPa or less, the polishing margin uniformity was 10% or less, which was a good result.

(Comparative example)
In Example 1, a rubber material having a slope a value greater than 10 MPa obtained by linear approximation of a stress-strain curve up to 5% strain with stress = a × strain + b, that is, EPDM 80 ° A and silicone 90 °. A silicon single crystal wafer was polished under the same conditions as in Example 1 except that the polishing head was manufactured by using it as a rubber film material, and the polishing margin uniformity of the wafer after polishing and the polishing pressure distribution during polishing were evaluated. .

FIG. 5 shows the result of the polishing pressure distribution. As shown in FIG. 5, when compared with the results of Example 1 in which a rubber film having a slope a value of 10 MPa or less was selected, the pressure drop in the outer peripheral portion of the workpiece became more remarkable, and the uniformity of the polishing pressure distribution was It turns out that it has fallen.
FIG. 6 shows the result of the polishing allowance uniformity. As shown in FIG. 6, it can be seen that the polishing margin uniformity is worse than the result of Example 1.

As a result, when polishing a workpiece using a conventional polishing device, even if the material of the rubber film and the same material are different from each other in the production lot, there will be variations in the polishing stock uniformity and stable workpiece flatness. It was confirmed that cannot be obtained.
Next, a silicon single crystal wafer was polished under the same conditions as in Example 2 except that a polishing cloth having a Young's modulus of 4.5 MPa was used, and the polishing margin uniformity of the polished wafer was evaluated.
The result is shown in FIG. As shown in FIG. 7, it can be seen that the polishing allowance uniformity is worse than the result of Example 2. That is, with the polishing head of the present invention selected as a rubber film that has a slope value of 10 MPa or less obtained by linear approximation of a stress-strain curve with a strain within 5%, the polishing margin uniformity can be improved. When this is placed in a polishing apparatus for polishing, the polishing cloth adhered to the surface plate needs to have a Young's modulus of 3.5 MPa or less.

The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.
For example, the polishing head manufactured by the manufacturing method according to the present invention is not limited to the embodiment shown in FIG. 1. For example, the shape of the intermediate plate may be appropriately designed.
Further, the configuration of the polishing apparatus is not limited to that shown in FIG. 1. For example, a polishing apparatus including a plurality of polishing heads manufactured by the manufacturing method according to the present invention may be used.

It is the schematic which showed an example of the grinding | polishing apparatus which concerns on this invention. 5 is a graph showing an example of a stress-strain curve obtained in the method for manufacturing a polishing head according to the present invention. (A) All stress-strain curves. (B) Stress-strain curve with a strain within 5%. 3 is a graph showing a stress-strain curve in the rubber film selection process of Example 1. FIG. (A) All stress-strain curves. (B) Stress-strain curve within 5% strain. It is a figure which shows the result of the value of the inclination obtained by carrying out the linear approximation of the stress-strain curve in which the distortion | strain is less than 5% in the selection process of the rubber film of Example 1. It is a figure which shows the result of polishing pressure distribution in Example 1 and a comparative example. It is a figure which shows the result of the grinding | polishing allowance uniformity in Example 1 and a comparative example. It is a figure which shows the result of grinding | polishing allowance uniformity in Example 2 and a comparative example. It is the schematic which shows an example of the conventional grinding | polishing head. It is the schematic which shows an example of the conventional single-side polish apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Polishing apparatus, 2 ... Polishing head, 3 ... Rubber film,
4 ... Rigid ring, 5 ... Middle plate, 6 ... Space part,
7 ... Pressure adjusting mechanism, 8 ... Surface plate, 9 ... Polishing cloth, 10 ... Abrasive supply mechanism,
DESCRIPTION OF SYMBOLS 11 ... Drive shaft, 12 ... Through-hole, 13 ... Backing pad,
14 ... Template.

Claims (2)

At least an annular rigid ring, a rubber film bonded to the rigid ring with a uniform tension, an intermediate plate coupled to the rigid ring and forming a space with the rubber film and the rigid ring, and the space And a pressure adjusting mechanism for changing the pressure of the rubber film. The polishing head holds the back surface of the work on the lower surface of the rubber film and polishes the work surface by sliding the surface of the work on a polishing cloth affixed on a surface plate. A manufacturing method of at least
Before adhering the rubber film to the rigid ring, a tensile test based on JIS K6251 of the rubber film is performed, and a slope value obtained by linearly approximating a stress-strain curve with a strain within 5% is 10 MPa or less. A method of manufacturing a polishing head, comprising: a step of selecting a target, and a polishing head is manufactured by adhering to the rigid ring using a rubber film having the selected inclination value of 10 MPa or less.   The method of manufacturing a polishing head according to claim 1, wherein the workpiece to be held is a silicon single crystal wafer having a diameter of 300 mm or more.

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