JP6513174B2 - Design method of wafer holding carrier - Google Patents

Description

  The present invention relates to a wafer holding carrier, a method for double-side polishing of a wafer using the same, and a method for evaluating and designing a wafer holding carrier.

Conventionally, when polishing both sides of a wafer simultaneously, the wafer is held by a wafer holding carrier.
FIG. 1 is a schematic view illustrating double-sided polishing of a wafer W by a general double-sided polishing apparatus 10 used conventionally. As shown in FIG. 1, the wafer W is held by a wafer holding carrier 101 which is formed to be thinner than the wafer W.

  The wafer holding carrier 101 is engaged with the sun gear 4 and the internal gear 6, and is rotated by the rotation of the sun gear 4 and the internal gear 6. Then, the upper surface plate 7 and the lower surface plate 8 are reversely rotated while supplying the abrasive 11 from the abrasive supply device 12 to the polishing surface, so that the polishing cloth 3 attached to the upper and lower surface plates 7 and 8 is used. The two sides of the wafer W are simultaneously polished.

When the polishing agent 3 is not sufficiently supplied between the polishing pad 3, the wafer holding carrier 101, and the wafer W during double-side polishing, clogging of the polishing pad 3 is accumulated due to frictional heat, and so on. A drip occurs. In particular, since the abrasive 11 is supplied from the upper surface plate 7 on the lower surface plate 8 side, the supply amount is further reduced.
Therefore, as described in FIG. 2 and Patent Document 1, by providing various abrasive passage holes 9 in the wafer holding carrier in addition to the wafer holding holes 5, the supply amount of the abrasive is increased, and both sides are provided. The flatness of the wafer after polishing was improved.

JP, 2004-283929, A

However, depending on the arrangement of the wafer holding hole and the abrasive passage hole, the in-plane strength of the carrier may vary, and as a result, the wafer flatness may be deteriorated.
This is because, by maximizing the area of the abrasive passage holes, the shortage of the supply of the abrasive is improved, but the strength of the wafer holding carrier is lowered.

  When the strength of the wafer holding carrier is lowered, local distortion may occur in the wafer holding carrier 101 as shown in FIG. 3 when the wafer is double-sided polished. When a distorted wafer holding carrier is used, the outer peripheral portion of the wafer W as well as the wafer holding carrier 101 collides with the polishing pad 3, and an outer peripheral sag occurs on the wafer W. In such a case, the thickness of the wafer holding carrier 101 is extremely reduced locally along with the insert resin 2, and variations in thickness occur in the peripheral portion of the wafer holding hole 5.

  Furthermore, as described above, the wafer holding carrier in which the thickness variation occurs in the peripheral portion of the wafer holding hole can be obtained as shown in FIG. 4 even if no distortion occurs in the subsequent double-side polishing. The edge is easily polished and an outer peripheral sag occurs.

  As described above, when the wafer holding carrier is used in which the wafer holding carrier is locally distorted or when the thickness of the wafer holding hole is uneven, the wafer W having high flatness is obtained. There was a problem that it became difficult to manufacture.

  The present invention has been made in view of the problems as described above, and a wafer holding carrier capable of supplying a polishing agent sufficiently while suppressing the displacement amount of the wafer holding carrier at the time of double-side polishing, and using the same It is an object of the present invention to provide a method for double-side polishing of a wafer, an evaluation method for a wafer holding carrier, and a design method.

In order to achieve the above object, according to the present invention, in a double-side polishing apparatus, a wafer holding hole is disposed between an upper platen and a lower platen to which a polishing pad is attached, for receiving and holding a wafer. What is claimed is: 1. A carrier for holding a wafer, comprising: and a plurality of abrasive passage holes for passing an abrasive.
The diameter of the abrasive passage hole is 10 to 20 mm,
According to another aspect of the present invention, there is provided a wafer holding carrier, wherein the distance between adjacent abrasive passage holes is in the range of 1 to 2 times the diameter of the abrasive passage holes.

  With such a wafer holding carrier, it is possible to provide a wafer holding carrier that can sufficiently supply the polishing agent while suppressing the displacement amount of the wafer holding carrier during double-side polishing.

At this time, it is preferable that a distance between the abrasive passage hole and the wafer holding hole adjacent thereto is in a range of 1 to 2 times of a diameter of the abrasive passage hole.
With such a thing, the displacement amount of the wafer holding carrier at the time of double-sided polishing can be suppressed more reliably.

Further, according to the present invention, there is provided a method of double-side polishing a wafer,
The carrier for holding a wafer according to the present invention is disposed between an upper surface plate and a lower surface, to which a polishing cloth is attached, and the wafer is held in the wafer holding hole formed in the wafer holding carrier. A method is provided for double sided polishing of a wafer comprising polishing.

  With such a double-side polishing method, since the carrier for holding a wafer according to the present invention, which can sufficiently supply the polishing agent while suppressing the displacement amount of the carrier for wafer holding at the time of double-side polishing, is used, the flatness is high. Wafers can be obtained.

Further, according to the present invention, in the double-side polishing apparatus, a wafer holding hole which is disposed between an upper surface plate and a lower surface plate to which a polishing pad is attached and which receives and holds a wafer, passes an abrasive. And a method of evaluating a wafer holding carrier having a plurality of abrasive passage holes.
When a force is applied to the wafer holding hole of the wafer holding carrier in the horizontal direction of the wafer holding carrier, the amount of displacement of the wafer holding carrier in the vertical direction of the wafer holding carrier is a finite element. A method of evaluating a wafer holding carrier characterized by evaluation by stress analysis using a method is provided.

  With such a method for evaluating a wafer holding carrier, the displacement amount of the wafer holding carrier at the time of double-sided polishing can be evaluated, and the suitability of the wafer holding carrier can be accurately evaluated.

Further, according to the present invention, there is provided a method of designing a carrier for holding a wafer, wherein the evaluation method of the present invention described above is used.
The relationship between the diameter of the polishing agent passage hole and the displacement amount of the wafer holding carrier is determined, and the diameter of the polishing agent passage hole is designed to be within a range in which the displacement amount obtained has a minimum value. ,
Within the range of the diameter, the relationship between the distance between adjacent abrasive passage holes and the amount of displacement of the wafer holding carrier is determined, and the distance between adjacent abrasive passage holes determined as described above The present invention provides a method of designing a wafer holding carrier characterized by designing the distance to be in a range in which the amount of reduction takes a local minimum value.

  With such a method for designing a wafer holding carrier, it is possible to design a wafer holding carrier that can sufficiently supply an abrasive while suppressing the displacement amount of the wafer holding carrier at the time of double-side polishing.

  The carrier for holding a wafer according to the present invention can suppress occurrence of local distortion during double-side polishing. In addition, by using such a wafer holding carrier of the present invention, it is possible to polish a wafer on both sides with high flatness. Furthermore, according to the method for evaluating a wafer holding carrier of the present invention, the displacement amount of the wafer holding carrier can be accurately evaluated, and a wafer holding carrier capable of double-sided polishing of a highly flat wafer can be designed.

It is the schematic which showed an example of a common double-sided grinding | polishing apparatus. It is the schematic which showed an example of the conventional carrier for wafer holding. It is the schematic which shows a mode that distortion generate | occur | produces locally in the carrier for wafer holding, and the outer peripheral sag has generate | occur | produced in the wafer. It is the schematic which shows a mode that double-sided grinding | polishing of a wafer is performed using the carrier for wafer holdings in which one part became thin. It is the schematic which showed an example of the carrier for wafer holding of this invention. It is the schematic which showed an example of how to apply force to the wafer holding part of the conventional carrier for wafer holding. It is the schematic which shows the relationship between the diameter of an abrasive | polishing agent passage hole, and the displacement amount of the carrier for wafer holding. It is a figure which shows the relationship between the space | interval of abrasives passage holes, and the displacement amount of the wafer holding carrier. It is a figure which shows the relationship of the ratio of the diameter of the abrasive | polishing agent passage hole and the space | interval of abrasives passage holes, and the displacement amount of the wafer holding carrier. It is the schematic which showed an example of the carrier for wafer holding of this invention. Is a graph showing measurement results of _{SFQR max} in Example 2 (the distance 15mm between the holding hole). Is a graph showing measurement results of _{ESFQR max} in Example 2 (the distance 15mm between the holding hole). Is a graph showing measurement results of _{SFQR max} in Example 2 (the distance 22mm between the holding hole). Is a graph showing measurement results of _{ESFQR max} in Example 2 (the distance 22mm between the holding hole). It is a schematic diagram of the measurement results of _{SFQR max} in Comparative Example 1. Is a graph showing measurement results of _{ESFQR max} in Comparative Example 1. Is a diagram showing the relationship between the displacement amount and the _{SFQR max} wafer holding carrier. Is a diagram showing the relationship between the displacement amount and the _{ESFQR max} wafer holding carrier. It is a figure which shows the location which measures the thickness in the wafer holding hole peripheral part. It is a diagram showing the relationship between variation and SFQR _max of the thickness of the holding hole peripheral portion in Comparative Example 2. It is a diagram showing the relationship between variation and ESFQR _max of the thickness of the holding hole peripheral portion in Comparative Example 2. FIG. 16 is a view showing the measurement results of the thickness of the wafer holding hole peripheral portion in Comparative Example 3; FIG. 16 is a view showing the measurement results of the thickness of the wafer holding hole peripheral portion in Example 3;

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.
As described above, in the double-side polishing of a wafer using the wafer holding carrier, there is a problem that the flatness of the polished wafer is deteriorated, for example, a sag occurs on the outer periphery of the wafer.
Therefore, the inventor conducted experiments to investigate the cause of the occurrence of such a problem and repeated studies. As a result, it has been found that a local displacement occurs in the wafer holding carrier at the time of double-side polishing, which causes peripheral sag of the wafer. In addition, it has become clear that double-sided polishing with high flatness can be performed by using a wafer holding carrier having a small displacement amount.

  As shown in FIG. 5, the wafer holding carrier 1a of the present invention is provided with a wafer holding hole 5 for holding a wafer and an abrasive passage hole 9 for supplying an abrasive to the polishing surface. .

  The wafer holding carrier 1a is used when double-side polishing the wafer W in the double-side polishing apparatus 10 as shown in FIG. The double-side polishing apparatus 10 includes an upper surface plate 7 and a lower surface plate 8 provided opposite to each other in the vertical direction, and a polishing pad 3 is attached to each surface plate. A sun gear 4 is provided at a central portion between the upper surface plate 7 and the lower surface plate 8, and an internal gear 6 is provided at the peripheral portion.

  The outer teeth of the wafer holding carrier 1a are engaged with the respective teeth of the sun gear 4 and the internal gear 6, and the upper surface plate 7 and the lower surface plate 8 are rotated by a drive source (not shown). The wafer holding carrier 1a revolves around the sun gear 4 while rotating. At this time, the wafer W held by the wafer holding holes 5 of the wafer holding carrier 1 a is simultaneously polished on both sides by the upper and lower polishing pads 3. During polishing of the wafer W, the polishing agent 11 is supplied from the polishing agent supply device 12 to the polishing surface of the wafer W.

Here, in the wafer holding carrier 1a of the present invention, the diameter of the abrasive passage hole 9 is 10 to 20 mm, and the distance between adjacent abrasive passage holes is 1 to 2 times the diameter of the abrasive passage hole 9 To be in the range of
Thus, the polishing agent can be sufficiently passed through and supplied onto the lower surface plate 8 while suppressing the displacement amount of the wafer holding carrier at the time of double-side polishing.

  At this time, it is preferable that the distance between the abrasive passage hole 9 and the wafer holding hole 5 adjacent to the wafer is in the range of 1 to 2 times the diameter of the abrasive passage hole 9. Thereby, the displacement of the wafer holding carrier can be suppressed more reliably.

  The material of the wafer holding carrier 1a is not particularly limited, but may be made of, for example, Ti (titanium) or glass epoxy. All materials conventionally used can be used.

Next, the method for double-sided polishing of a wafer according to the present invention will be described below.
In the method for double-side polishing of a wafer according to the present invention, the carrier 1a for holding a wafer according to the present invention as described above is disposed in the double-side polishing apparatus 10.

Next, the wafer W is inserted into the wafer holding hole 5 of the wafer holding carrier 1a and held.
Next, the upper and lower surfaces of the wafer W are sandwiched by the polishing pad 3 and the upper and lower platens are rotated while supplying the polishing agent 11 to the polishing surface to perform double-side polishing of the wafer W.
In this way, if the wafer W is double-sided polished, the wafer holding carrier 1a of the present invention can be used which can sufficiently supply the polishing agent 11 while suppressing the displacement of the wafer holding carrier 1a during double-sided polishing. It is possible to obtain a wafer with a high degree of flatness by suppressing the occurrence of sagging in the outer peripheral portion of the wafer.

Next, the method for evaluating a wafer holding carrier according to the present invention will be described.
In the method for evaluating a wafer holding carrier according to the present invention, the double-side polishing apparatus 10 is disposed between the upper surface plate 7 and the lower surface plate 8 to which the polishing pad 3 is attached. The wafer holding carrier having the wafer holding holes 5 and a plurality of abrasive passage holes 9 for passing the abrasives 11 is evaluated.

Then, when a force is applied to the wafer holding hole 5 of the wafer holding carrier in the horizontal direction of the wafer holding carrier, the amount by which the wafer holding carrier is displaced in the vertical direction of the wafer holding carrier is a finite element. Evaluated by stress analysis using the method.
At this time, force F can be applied to the surface of the wafer holding hole 5 in contact with the wafer W in the direction as shown in FIG. At this time, the magnitude of the force F applied to the wafer holding hole 5 can be set to 1000 N, for example.

The stress analysis using the finite element method can be performed, for example, by simulation analysis.
Here, with the finite element method, an object having a complicated shape or property is divided into small parts (elements) of a simple shape or property, and the characteristics of each element are expressed using mathematical equations. After being approximately expressed, this simple equation is combined, and the whole behavior is predicted by finding a solution that satisfies all the equations. Note that the behavior of the entire object indicates, for example, deformation or stress distribution.

  With such a method for evaluating a wafer holding carrier, it is possible to evaluate the amount of displacement of the wafer holding carrier in the vertical direction during double-side polishing.

Next, the method for designing a wafer holding carrier according to the present invention will be described.
First, the relationship between the diameter of the polishing agent passage hole and the displacement amount of the wafer holding carrier is determined by the evaluation method of the wafer holding carrier of the present invention described above.
Then, the diameter of the abrasive passage hole is designed to a length in a range in which the obtained displacement amount of the wafer holding carrier takes a minimum value.
Here, the length of the range in which the local minimum value is taken is a range that includes the local minimum value and in which the displacement amount is a value that does not cause a problem (a value that can be regarded as almost equal). Specifically, for example, in the case of FIG. 7 obtained in Example 1 to be described later, the length of the range in which the minimum value is obtained can be set to the range of 10 to 20 mm in diameter of the abrasive passage hole.

Then, next, the distance between the adjacent abrasive passage holes and the distance between the wafer holding carrier and the distance between the adjacent abrasive passage holes are within the range of the diameter of the abrasive passage hole having a length where the displacement amount takes a minimum value. Seek a relationship.
Then, the distance between the adjacent abrasive passage holes is designed to be a distance in a range in which the determined displacement amount has a minimum value.
Here, the distance in the range where the local minimum value is taken is the same definition as above, and specifically, for example, in the case of FIG. 9 obtained in Example 1 described later, it is 1 of the diameter of the abrasive passage hole. Since the abrasive passage holes are 15 mm in this case, the distance between the abrasive passage holes can be in the range of 15 to 30 mm.

  By designing in this manner, the polishing agent can be sufficiently supplied while suppressing the displacement amount of the wafer holding carrier at the time of double-side polishing. Therefore, it is possible to design a wafer holding carrier capable of double-sided polishing with high flatness.

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

Example 1
When double-sided polishing of a wafer is performed using a double-sided polishing apparatus, the amount of displacement of the wafer holding carrier is evaluated by performing simulation using the finite element method, and further, the wafer holding carrier is designed. The

  The simulation using the finite element method was calculated using Femtet software manufactured by Murata Software Co., Ltd.

First, Femtet was launched, stress analysis was selected as an analysis item, and a drawing of a wafer holding carrier created by 3D CAD was input to Femtet.
5 mm was selected in the analysis mesh size setting, and Ti (titanium) was selected as an applied material from the material selection screen. Then, Poisson's ratio 0.32, Young's modulus 1.157E11, etc. were extracted from the existing information of Femtet.

As a boundary condition, a simulation was performed in which a force F of 1000 N in magnitude was applied to the surface of the wafer holding hole in contact with the wafer in the direction shown in FIG.
At that time, the diameter of the abrasive passage hole 9 of the wafer holding carrier 1a as shown in FIG. 5 was changed from 5 mm to 40 mm. The distance between the abrasive passage holes 9 and the distance between the wafer holding holes 5 adjacent to the abrasive passage holes 9 were set to be the same as the diameter of the abrasive passage holes 9.
Further, a simulation was performed on the wafer holding carrier 101 having the abrasive passage holes 9 having diameters of 50 mm and 135 mm as shown in FIG.
The results of these simulations are shown in Tables 1 and 2 and further in FIG.

  In Tables 1 and 2, the model shows a carrier for holding a wafer in which the abrasive passage holes for which simulation was performed are disposed. Further, the minimum displacement amount indicates the displacement amount of the largest portion jumping out to the back surface side of the carrier, and the maximum displacement amount indicates the displacement amount of the largest portion jumping out to the surface side of the carrier. And a displacement amount shall show the sum of the absolute value of the minimum displacement amount and the maximum displacement amount. Then, the degree of indicating the amount of displacement of each simulated wafer holding carrier is shown.

As shown in Table 1, Table 2 and FIG. 7, it can be seen that the displacement amount of the wafer holding carrier takes a minimum value when the diameter of the abrasive passage hole is in the range of 10 mm to 20 mm.
When the diameter of the abrasive passage hole was 15 mm, the displacement amount of the wafer holding carrier was the smallest, 31.4 μm. Therefore, the diameter of the abrasive passage hole is designed to be 15 mm.

Next, when the diameter of the abrasive passage hole is 15 mm, the displacement amount of the wafer holding carrier when the distance between the abrasive passage holes is changed between 10 mm and 40 mm is the same as above. The simulation was performed to evaluate the wafer holding carrier. The simulation results at this time are shown in Tables 3 and 4 and FIGS. 8 and 9.
FIG. 8 also shows the results of the displacement of the wafer holding carrier when the diameter of the abrasive passage hole is 30 mm.

  Further, in Tables 3 and 4, the model shows a carrier for holding a wafer in which the abrasive passage holes for which simulation was performed are disposed. In the same manner as described above, the minimum displacement amount indicates the displacement amount of the largest portion jumping out to the back side of the carrier, and the maximum displacement amount refers to the displacement amount of the largest portion jumping out to the surface side of the carrier Show. And a displacement amount shall show the sum of the absolute value of the minimum displacement amount and the maximum displacement amount. Then, the degree of indicating the amount of displacement of each simulated wafer holding carrier is shown.

As shown in Tables 3 and 4 and FIG. 8, it was found that the displacement amount of the wafer holding carrier takes a minimum value when the distance between the abrasive passage holes is in the range of 15 mm to 30 mm.
That is, as shown in FIG. 9, the displacement of the wafer holding carrier takes a minimum value when the distance between the abrasive passage holes is in the range of 1 to 2 times the diameter of the abrasive passage holes. I understood.
When the distance between the abrasive passage holes was 22 mm, the displacement amount of the wafer holding carrier was the smallest 31.1 μm.

  Further, as shown in FIG. 8, when the diameter of the abrasive passage hole is 30 mm, the displacement amount is the smallest when the distance between the abrasive passage holes is 30 mm, but compared with the case where the diameter of the abrasive passage hole is 15 mm. Thus, it can be understood that the displacement amount is large.

  Based on the above results, as shown in FIG. 5, the diameter of the abrasive passage holes 9 is 15 mm, the distance between the abrasive passage holes 9 and the wafer holding holes 5 adjacent to the abrasive passage holes 15 is 15 mm. The wafer holding carrier 1a has a diameter of 15 mm for the abrasive passage holes 9 as shown in FIG. 10, the distance between the abrasive passage holes 9 and the wafer holding holes 5 adjacent to the abrasive passage holes 22 is 22 mm. A certain wafer holding carrier 1b was designed.

  In this way, it is possible to design a wafer holding carrier that can sufficiently supply the polishing agent while suppressing the displacement amount of the wafer holding carrier during double-side polishing.

(Example 2, Comparative Example 1)
The wafer holding carrier 1a designed in Example 1, the diameter of the abrasive passage hole 9 being 15 mm, the distance between the abrasive passage holes 9 and the distance of the wafer holding hole 5 adjacent to the abrasive passage hole 15 being 15 mm. The diameter of the abrasive passage hole 9 is 15 mm, and the distance between the abrasive passage holes 9 and the distance between the abrasive passage hole 9 and the wafer holding hole 5 adjacent to the wafer holding hole 5 are 300 mm in diameter using the wafer holding carrier 1b. Double-side polishing was performed on 45 wafers W of each of the wafers W (Example 2).
Similarly, 45 wafers W were double-sided polished for the wafer holding carrier 101 as shown in FIG. 2 (Comparative Example 1).

For double-side polishing of the wafer W, a double-side polishing apparatus manufactured by SpeedFam Co., Ltd. was used, a urethane pad having a thickness t = 1.3 mm was used for the polishing cloth, and colloidal silica was used for the polishing liquid.
As for the conditions of the double-side polishing apparatus at the time of polishing, the number of rotations of the upper surface plate is -5 to -15 rpm, the number of rotations of the lower surface plate is 10 to 25 rpm, the number of rotations of the sun gear is 10 to 20 rpm, and the rotation of the internal gear The double-side polishing was performed at a number of 0 to 10 rpm and a polishing pressure of 100 to 150 g / cm ² .

The flatness of the surface of the wafer W polished on both sides under the conditions as described above is referred to as flatness of the wafer surface with a flatness measuring device (WaferSight) SFQR _max (M49 mode @ 26 × 8/0 × 0 mm E · E _x = 2mm) and _{ESFQR max (Length35mm Wedges72 E · E} x = 1mm) were measured.

In addition, SFQR (site front least squares range) and ESFQR (edge site front least squares range) are the inside of the site which calculated data by the least squares method in the set site in the state which corrected the wafer back to a plane. The plane is taken as a reference plane, and the difference in maximum and minimum positional displacement from this plane for each site is shown.
Also, SFQR _max or ESFQR _max indicates the largest one of the differences for each site.

The measurement results of SFQR _max and ESFQR _max of wafer holding carrier 1a of Example 2 are shown in FIGS. 11 and 12, respectively, and the measurement results of wafer holding carrier 1b are shown in FIG. It showed in FIG.
Similarly, the measurement results of SFQR _max and ESFQR _max of Comparative Example 1 are shown in FIGS. 15 and 16, respectively.
In addition, in Table 5 and Table 6, the average value, the maximum value, and the minimum value of SFQR _max and ESFQR _max in Example 2 and Comparative Example 1 are shown, respectively.
Furthermore, a relationship between the average value and the carrier displacement amount of _{SFQR max} and _{ESFQR max} at this time is shown in FIG. 17 and FIG. 18.

In addition, as the value of SFQR _max shown in the chart, one normalized with the average value of SFQR _max of Comparative Example 1 as 1 was used.
Similarly, the value of _{ESFQR max} was also used as the normalized average value of _{ESFQR max} of Comparative Example 1 as 1.

As a result, in Example 2, compared to Comparative Example 1, it was found that the values of both SFQR _max and ESFQR _max were smaller, the flatness was good, and double-sided polishing was performed.
From the results of FIG. 17 and FIG. 18, it was found that SFQR _max and ESFQR _max become smaller as the displacement amount of the wafer holding carrier becomes smaller.

(Comparative example 2)
A wafer holding carrier having different thickness variations around the wafer holding holes was prepared, and the flatness of the wafer was measured after double-side polishing of the wafer using each wafer holding carrier.

As a wafer holding carrier, five titanium wafer holding carriers 101 each having an abrasive passage hole 9 having a diameter of 50 mm and 135 mm as shown in FIG. 2 were prepared.
The wafer holding carriers 101 have different thickness variations around the wafer holding holes 5 respectively.

The thickness of the periphery of the wafer holding hole 5 was measured by placing the wafer holding carrier 101 on a horizontal measurement table and using a Keyence laser displacement meter LK-G15.
The thickness was measured at eight measurement points a to h around the wafer holding hole 5 at 5 to 7 mm from the wafer holding hole 5 as shown in FIG.
The difference between the maximum value and the minimum value of the measurement results of the thickness around the wafer holding hole at this time was taken as the variation of the thickness.

  Then, 15 wafers each having a diameter of 300 mm were subjected to double-side polishing using these wafer holding carriers 101.

The conditions for double-sided polishing of the wafer were the same as in Example 2, and the flatness of the surface of the double-sided polished wafer was also measured in the same manner as in Example 2.
From the measurement results, FIG. 20 shows the relationship between the variation in thickness of the wafer holding hole peripheral portion and the average value of SFQR _max . Similarly, FIG. 21 shows the relationship between the variation in thickness of the wafer holding hole peripheral portion and the average value of the flatness ESFQR _max .

From FIG. 20 and FIG. 21, when double-side polishing is performed using a wafer holding carrier with large variations in thickness around the wafer holding hole, both SFQR _max and ESFQR _max are large, and a wafer holding carrier with small variation is used. It was found that SFQR _max and ESFQR _max were both small when polishing was performed.

(Example 3, Comparative Example 3)
As shown in FIG. 5, a titanium wafer holding 15 mm in diameter of the abrasive passage hole 9, a distance between the abrasive passage holes 9 and a distance of 15 mm between the wafer holding hole 5 adjacent to the abrasive passage hole 9 The wafer was polished on both sides by a double side polishing apparatus using the carrier 1a. After completion of the double-side polishing, the thickness of the periphery of the wafer holding hole 5 of the wafer holding carrier 1a was measured (Example 3).
Similarly, after using a titanium wafer holding carrier 101 having 50 mm and 135 mm abrasive passage holes 9 as shown in FIG. 2 in double-side polishing processing, measurement of the thickness around the wafer holding holes 5 Were performed (comparative example 3).

The double-side polishing was performed under the same conditions as in Example 2, and the wafer was double-sided polished.
The thickness was measured in the same manner as in Comparative Example 2, and as shown in FIG. 19, the measurement was performed on eight points a to h around the wafer holding hole.

The measurement was performed after using each wafer holding carrier for 70000 minutes or more.
The thickness of the periphery of the wafer holding hole in Comparative Example 3 after 70000 minutes of use is as shown in FIG.
Also, the thickness around the wafer holding hole in Example 3 is as shown in FIG.

As a result, it was found that in Comparative Example 3 shown in FIG. 22, there were observed portions where the thickness around the wafer holding hole was locally reduced like the measurement positions b and f.
On the other hand, in Example 3 shown in FIG. 23, it was found that the thickness around the wafer holding hole was uniform as a whole.

  This is because, as shown in Table 1 above, the displacement amount of the wafer holding carrier 101 is 246.6 μm, whereas the displacement amount of the wafer holding carrier 1 a is 31.4 μm, which is equivalent to the time of double-side polishing This is because the amount of displacement is small.

As described above, since the wafer holding carrier 1a of Example 3 has a small displacement amount at the time of double-side polishing, variation in thickness around the wafer holding hole after being used in double-side polishing is small.
Therefore, as can be seen from the results in Comparative Example 2, the variation in thickness around the wafer holding hole is small, and if double-side polishing is performed using the wafer holding carrier of the present invention, both SFQR _max and ESFQR _max are obtained. It has been found that a small, high flatness wafer can be obtained.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has the substantially same constitution as the technical idea described in the claims of the present invention, and the same effects can be exhibited by any invention. It is included in the technical scope of

1a, 1b, 101: Carrier for holding a wafer, 2 ... Insert resin, 3 ... Abrasive cloth,
4 sun gear 5 wafer holding hole 6 internal gear 7 top plate
8: Lower surface plate, 9: Abrasive passage hole, 10: Double-side polishing device, 11: Abrasive,
12: Abrasive supply device, F: Force, W: Wafer.

Claims (2)

In a double-side polishing apparatus, a wafer holding hole for accommodating and holding a wafer, which is disposed between an upper platen and a lower platen to which an abrasive cloth is attached, and a plurality of abrasives pass through for passing abrasives. A method of designing a wafer holding carrier having a hole
When a force is applied to the wafer holding hole of the wafer holding carrier in the horizontal direction of the wafer holding carrier, the amount of displacement of the wafer holding carrier in the vertical direction of the wafer holding carrier is a finite element. Evaluated by stress analysis using
The relationship between the diameter of the polishing agent passage hole and the displacement amount of the wafer holding carrier is determined, and the diameter of the polishing agent passage hole is designed to be within a range in which the displacement amount obtained has a minimum value. ,
In the range of the diameter, the relationship between the distance between the adjacent abrasive passage holes and the displacement of the wafer holding carrier is determined.
A design method of a wafer holding carrier, wherein a distance between adjacent abrasive passage holes is designed to be a distance in a range of 1 to 2 times a diameter of the abrasive passage holes . The method for designing a wafer holding carrier according to claim 1, wherein the diameter of the abrasive passage hole is changed in the range of 5 mm to 40 mm, and the distance between adjacent abrasive passage holes is in the range of 10 mm to 40 mm. A method of designing a wafer holding carrier characterized in that it is changed to obtain a relationship with the amount of displacement.

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