JP6197598B2 - Double-side polishing apparatus and double-side polishing method for work - Google Patents

Description

  The present invention relates to a double-side polishing apparatus and a double-side polishing method for a workpiece.

  In the manufacture of semiconductor wafers such as silicon wafers, which are typical examples of workpieces used for polishing, there is a double-side polishing process that simultaneously polishes the front and back surfaces of the wafer in order to obtain higher-precision wafer flatness quality and surface roughness quality. It has been adopted.

  This double-side polishing generally uses a double-side polishing machine that has a carrier plate with a hole for holding the workpiece between the upper and lower surface plates, holds the workpiece in the holding hole of this carrier plate, and supplies polishing slurry. While rotating the upper and lower surface plates, the polishing pad affixed to the upper and lower surface plates and the front and back surfaces of the workpiece are slid to simultaneously polish both surfaces of the workpiece.

  Here, normally, the slurry is supplied temporarily from a slurry supply source to a slurry ring provided above the upper platen, and is spontaneously dropped from the slurry supply hole to pass through the upper platen. And is fed onto the polishing pad.

  However, in the method of supplying the polishing slurry by natural dripping, even if the flow rate of the polishing slurry is adjusted to increase the flow rate, the polishing slurry may not sufficiently flow into the polishing surface. There was a possibility that the supply amount of the polishing slurry was insufficient and the polishing rate was lowered or the workpiece was convex. Such a problem becomes a prominent problem especially when a workpiece having a large diameter of 450 mm or more is used.

  On the other hand, a method has been proposed in which the polishing slurry is directly pumped between the upper and lower surface plates using a pumping pump (see, for example, Patent Document 1). According to this method, since the polishing slurry is pumped, the supply amount of the polishing slurry on the polishing surface can be ensured, and the accuracy of workpiece shape control can be improved.

Japanese Patent No. 4163485

  However, as described in Patent Document 1, in the method in which the polishing slurry is pumped, the back pressure increases as the polishing slurry flow rate increases, and the polishing pressure on the work by the surface plate becomes inappropriate, and the polishing rate decreases. There is a problem of inviting.

  The present invention is intended to solve the above problems, and an object of the present invention is to provide a workpiece double-side polishing apparatus and a polishing method capable of obtaining a desired workpiece shape while maintaining a high polishing rate. There is to do.

The gist configuration of the present invention is as follows.
The workpiece double-side polishing apparatus of the present invention includes a rotating surface plate having an upper surface plate and a lower surface plate, a sun gear provided at the center of the rotating surface plate, and an internal gear provided at the outer peripheral portion of the rotating surface plate. And a carrier plate provided between the upper surface plate and the lower surface plate and having one or more holding holes for holding a workpiece,
A dropping supply section for supplying the polishing slurry between the upper and lower surface plates by natural dropping;
A pressure feed supply section for feeding the polishing slurry between the upper and lower surface plates by pressure feed, and further comprising:
A polishing slurry can be simultaneously supplied between the upper and lower surface plates from the dropping supply unit and the pressure supply unit.
Here, “natural dripping” refers to a slurry dripping method that is supplied not by pressure feeding between the surface plates but by gravity dropping.

  In the double-side polishing apparatus for workpieces according to the present invention, it is preferable that each of the dropping supply unit and the pressure feeding supply unit has a flow rate adjusting valve for adjusting the flow rate of the polishing slurry.

  Furthermore, in the double-side polishing apparatus for a workpiece according to the present invention, it is preferable that each of the dropping supply unit and the pressure supply unit has a slurry supply hole.

  Furthermore, in the double-side polishing apparatus for a workpiece according to the present invention, it is preferable that the pressure supply unit is provided above the sun gear.

Here, in the workpiece polishing method of the present invention, the workpiece is held on a carrier plate provided with one or more holding holes for holding the workpiece, and the workpiece is sandwiched between rotating surface plates composed of an upper surface plate and a lower surface plate. The rotation platen and the carrier plate are rotated relative to each other by the rotation of the sun gear provided at the center of the rotation platen and the rotation of the internal gear provided at the outer periphery of the rotation platen. A double-side polishing method for a workpiece in which both sides of the workpiece are simultaneously polished,
The polishing slurry is supplied between the upper and lower surface plates by pressure feeding simultaneously with supplying the polishing slurry between the upper and lower surface plates by natural dripping.

Moreover, in the workpiece | work grinding | polishing method of this invention, it is preferable that the flow volume of the polishing slurry by pumping is 5%-50% of the total flow volume of polishing slurry.
The “total flow rate of the polishing slurry” means the sum of the flow rate of the polishing slurry by natural dripping and the flow rate of the polishing slurry by pressure feeding.

  Furthermore, in the workpiece polishing method of the present invention, it is preferable to supply polishing slurry between the upper and lower surface plates by pressure feeding from above the sun gear.

  According to the present invention, it is possible to provide a workpiece double-side polishing apparatus and a polishing method capable of obtaining a desired workpiece shape while maintaining a high polishing rate.

It is sectional drawing which shows the double-side polish apparatus of the workpiece | work concerning one Embodiment of this invention. It is a figure which shows the polishing rate and the evaluation result of GBIR when changing the flow volume of polishing slurry about the case where the polishing slurry is supplied only by pressure feeding. It is a figure which shows the evaluation result of a polishing rate and GBIR when changing the flow volume of polishing slurry about the case where polishing slurry is supplied only by natural dripping. It is a figure which shows the polishing rate and the evaluation result of GBIR when changing the flow volume of polishing slurry about the case where polishing slurry is supplied by the method using both natural dripping and pressure feeding. It is a figure which shows the evaluation result of a polishing rate and GBIR when changing the flow volume distribution of the polishing slurry by pumping with respect to the total flow volume of polishing slurry.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing a double-side polishing apparatus for a workpiece according to an embodiment of the present invention. As shown in FIG. 1, the double-side polishing apparatus 1 includes a rotating surface plate 4 having an upper surface plate 2 and a lower surface plate 3, a sun gear 5 provided at the center of the rotating surface plate 4, and a rotating surface plate 4. An internal gear 6 provided on the outer periphery, and a carrier plate 7 provided between the upper surface plate 2 and the lower surface plate 3 and having one or more holding holes (not shown) for holding the workpiece. ing. In addition, although illustration is abbreviate | omitted, the polishing pad is affixed on the lower surface which is a polishing surface of the upper surface plate 2, and the upper surface which is the polishing surface of the lower surface plate 3, respectively.
Here, as shown in FIG. 1, a concave portion is provided in the central portion of the lower surface of the upper surface plate 2, and this portion has a sealed structure. Further, the sun gear 5 and the lower surface plate 3 rotate independently of each other, but the gap between the sun gear 3 and the lower surface plate 3 is sealed so that the polishing slurry does not leak. As shown in FIG. 1, the upper surface of the sun gear 5 is located above the upper surface of the carrier plate 7.

As shown in FIG. 1, the double-side polishing apparatus 1 of this embodiment includes two drip supply units 8 in the illustrated example, which supplies polishing slurry between the upper and lower surface plates 2 and 3 by natural drip.
In the illustrated example, the dropping supply unit 8 includes a slurry supply source 9 that is a polishing slurry supply source, a flow rate adjusting valve 10 that adjusts the flow rate of the polishing slurry, and a bifurcated dropping supply hose 11 through which the polishing slurry passes. A slurry supply nozzle 13 connected to the tip of the dropping supply hose 11 and disposed above the slurry ring 12 to which polishing slurry is temporarily supplied; and the upper and lower surface plates 2 by dropping the polishing slurry from the slurry ring 12; 3, and a supply hose 14 that passes through the upper surface plate 2 and is connected to the supply hose 14.
In the present embodiment, the double-side polishing apparatus 1 has two drip supply units 8, but there may be one or more drip supply units 8, and the number is not particularly limited.
In the illustrated example, a bifurcated dropping supply hose 11 that branches off from one slurry supply source 9 and one flow rate adjustment valve 10 is used, but each dropping supply unit 8 has a slurry supply source 9 and a flow rate, respectively. The adjusting valve 10 may be included.
Further, in the illustrated example, the two drip supply units 8 each have three supply hoses 14 and three slurry supply holes 15 corresponding to the three supply hoses 14, respectively. In the present invention, the number of supply hoses 14 and slurry supply holes 15 is not particularly limited.

  Here, as shown in FIG. 1, in this embodiment, the three slurry supply holes 15 of the two drip supply units 8 are provided above the carrier plate 7.

Further, as shown in FIG. 1, the double-side polishing apparatus 1 of the present embodiment includes one pumping supply unit 16 in the illustrated example that supplies polishing slurry between the upper and lower surface plates 2 and 3 by pumping.
In the illustrated example, the pressure supply unit 16 has a slurry supply pump 17 for pumping the polishing slurry at a predetermined pressure by a pump action, a flow rate adjusting valve 18 for adjusting the flow rate of the polishing slurry, and the pumped polishing slurry passes therethrough. A pressure-feeding supply hose 19 and a pressure-feeding supply nozzle 20 that is connected to the pressure-feeding supply hose 19 and penetrates the center of the upper surface plate 2 are provided. In the illustrated example, the pressure supply unit 16 is provided above the sun gear 5.
In the present embodiment, the double-side polishing apparatus 1 has only one pressure supply unit 16, but in the present invention, the double-side polishing apparatus 1 may have two or more pressure supply units 16. good.

Using this double-side polishing apparatus 1, a workpiece is held on a carrier plate 7 provided with one or more holding holes for holding the workpiece, and the workpiece is held by a rotating platen 4 including an upper platen 2 and a lower platen 3. The rotating surface plate 4 and the carrier plate 7 are rotated by rotating the sun gear 5 and the internal gear 6 while sandwiching and supplying the polishing slurry onto a polishing pad (not shown) affixed to the upper and lower surface plates 2 and 3. Can be rotated relative to each other to polish both surfaces of the workpiece simultaneously.
Here, the supply of the polishing slurry is performed by dropping the polishing slurry by the dropping supply unit 8 and supplying the polishing slurry between the upper and lower surface plates 2 and 3, and at the same time feeding the polishing slurry by the pumping supply unit 16. It is performed by supplying between three. At this time, the flow rate of the polishing slurry by dripping and the flow rate of the polishing slurry by pressure feeding can be adjusted by the opening / closing amounts of the flow rate adjusting valves 10 and 18.
Hereinafter, the effect of this embodiment is demonstrated.

According to this embodiment, the polishing slurry is dropped by the dropping supply unit 8 and supplied between the upper and lower surface plates 2 and 3, and at the same time, the polishing slurry is pumped by the pressure supply unit 16 and between the upper and lower surface plates 2 and 3. Therefore, polishing slurry can be sufficiently supplied to the center of the workpiece, which tends to be insufficiently supplied by natural dripping alone. Deterioration of shape control such as shaping can be prevented. On the other hand, when only the pressure feeding method is used, if the polishing slurry flow rate is increased, a back pressure is generated, and the desired polishing pressure is not applied to the workpiece, and the polishing rate may be reduced. Since the supply of the polishing slurry by dripping is also used, back pressure does not occur even when the flow rate of the polishing slurry is increased, and stable processing can be performed at a high polishing rate.
As described above, according to the present embodiment, by using both the supply of the polishing slurry by natural dripping and the supply of the polishing slurry by pressure feeding, it is possible to obtain a desired workpiece shape while maintaining a high polishing rate. Can do.

  Here, in this invention, it is preferable that the dripping supply part 8 and the pressure supply part 16 have the flow volume adjustment valves 10 and 18 which adjust the flow volume of polishing slurry, respectively. And it is preferable to adjust the flow volume of the polishing slurry by pumping to 5 to 50% of the total flow volume of the polishing slurry. This is because, as will be described in the examples described later, by setting this range, it is possible to obtain a polished workpiece with high flatness while maintaining a particularly high polishing rate.

  Moreover, in this invention, it is preferable that the dripping supply part 8 and the pumping supply part 16 have the slurry supply holes 15 and 20, respectively. This is because the polishing slurry can be supplied from above the upper surface plate 2 through the slurry supply holes 15 and 20.

  Further, in the present invention, it is preferable that the pressure supply unit 16 is provided above the sun gear 5 and supplies the polishing slurry fed from there. As a result, the polishing slurry pumped from the pumping supply section 16 flows from the upper surface of the sun gear 5 to the center of the workpiece by centrifugal force, and thereby, the supply amount of the polishing slurry tends to be insufficient only by natural dripping. This is also because the polishing slurry can be supplied efficiently and the amount of polishing can be further secured.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

In order to confirm the effect of the present invention, as an example of the invention, double-side polishing was performed using the double-side polishing apparatus shown in FIG. 1, and a test for evaluating the polishing rate and GBIR (Global Backside Ideal Range) was conducted.
Further, as Comparative Example 1, the same evaluation was performed when the polishing slurry was supplied only by pressure feeding, and as Comparative Example 2, the polishing slurry was supplied only by natural dripping.

Here, in the above test, the following conditions were used in common with the invention example and the comparative examples 1 and 2.
The polishing pad used was Suba800 manufactured by Rodel Nitta, and the polishing slurry used was nalco2350 manufactured by Rodel Nitta. The number of rotations of the upper and lower surface plates was 20 to 30 rpm, and the processing surface pressure was 300 g / cm ² . Moreover, the diameter of the used upper and lower surface plate was 2000 mm, and the diameter of the wafer was 450 mm. Furthermore, the thickness of the carrier plate was 920 μm, and the target wafer thickness was 923 μm.

Here, the polishing rate was determined by setting the difference between the thickness of the wafer after polishing and the thickness of the wafer before starting polishing as the polishing amount (μm) and dividing the polishing amount by the polishing time (min).
The thickness of the wafer was measured using a laser displacement meter manufactured by Keyence Corporation.
GBIR is obtained by calculating the difference between the maximum displacement and the minimum displacement of the entire wafer on the basis of the back surface of the wafer when it is assumed that the back surface of the polished wafer is completely adsorbed. Yes, and measured using a Keyence Corporation laser displacement meter.

<Comparative Example 1>
FIG. 2 is a diagram showing the evaluation results of the polishing rate and GBIR when the polishing slurry is supplied only by pumping according to Comparative Example 1 and the polishing slurry flow rate is changed every 1 L / min.
As shown in FIG. 2, in the case of supplying the polishing slurry only by the pressure feeding method, increasing the polishing slurry flow rate decreases GBIR and improves the flatness of the wafer, but the polishing rate gradually decreases. .

<Comparative example 2>
FIG. 3 is a diagram showing the evaluation results of the polishing rate and GBIR when the polishing slurry is supplied by only natural dripping according to Comparative Example 2 and the flow rate of the polishing slurry is changed every 1 L / min.
As shown in FIG. 3, in the case of supplying the polishing slurry only by the natural dripping method, it can be seen that GBIR is improved only moderately even if the flow rate of the polishing slurry is increased. On the other hand, it can be seen that the polishing rate does not change much depending on the flow rate of the polishing slurry.

<Invention Example>
FIG. 4 shows the evaluation results of the polishing rate and GBIR when the polishing slurry is supplied by a method using both natural dripping and pressure feeding according to the invention example, and the flow rate of the polishing slurry is changed every 1 L / min. FIG. In FIG. 4, the flow rate of the polishing slurry by pumping was 20% of the total flow rate of the polishing slurry.
As shown in FIG. 4, according to the present invention, the polishing rate is stable at a high level (about 0.55 μm / min) regardless of the flow rate of the polishing slurry, and the flow rate of the polishing slurry is changed. However, it can be seen that a good GBIR (about 0.2 μm) can be maintained, and therefore the change in the shape of the wafer after polishing is small and it is easy to control to the same finished shape. Also, the value of GBIR is lower than that shown in FIGS. 2 and 3, and it can be seen that the flatness of the polished wafer is high.
Thus, from the result shown in FIG. 4, the synergistic effect by combined use with the natural dripping method and the pumping method by this invention was able to be confirmed.

Next, FIG. 5 is a diagram showing the evaluation results of the polishing rate and GBIR when the flow rate distribution of the polishing slurry by pumping is changed with respect to the total flow rate of the polishing slurry for the inventive example. In FIG. 5, the total flow rate of the polishing slurry was fixed at 13 L / min.
As shown in FIG. 5, it can be seen that the convex shape of the wafer changes to a concave shape as the flow rate distribution of the polishing slurry by pumping is increased with respect to the total flow rate of the polishing slurry.
In particular, the polishing rate is good when the flow rate of the polishing slurry by pumping is in the range of 5% to 70% of the total flow rate of the polishing slurry. In GBIR, the flow rate of polishing slurry by pumping is 5% of the total flow rate of the polishing slurry. It is good in the range of% to 50%. That is, the flow rate of the polishing slurry by pumping was in the range of 5% to 50% of the total flow rate of the polishing slurry, and while maintaining a high polishing rate, it was possible to obtain a workpiece with high flatness after polishing. Recognize.

According to the present invention, it is possible to provide a workpiece double-side polishing apparatus and a polishing method capable of obtaining a desired workpiece shape while maintaining a high polishing rate.
The present invention is particularly suitable as a double-side polishing apparatus and double-side polishing method for a large diameter workpiece having a diameter of 450 mm or more.

DESCRIPTION OF SYMBOLS 1 Double-side polish apparatus 2 Upper surface plate 3 Lower surface plate 4 Rotation surface plate 5 Sun gear 6 Internal gear 7 Carrier plate 8 Drop supply source 9 Slurry supply source 10 Flow control valve 11 Drop supply hose 12 Slurry ring 13 Slurry supply nozzle 14 Supply hose 15 Slurry supply hole 16 Pressure supply part 17 Slurry supply pump 18 Flow rate adjusting valve 19 Pressure supply hose 20 Slurry supply hole

Claims (7)

A rotating surface plate having an upper surface plate and a lower surface plate, a sun gear provided at a central portion of the rotating surface plate, an internal gear provided at an outer peripheral portion of the rotating surface plate, the upper surface plate, and the lower surface plate A double-side polishing apparatus for a workpiece, comprising a carrier plate having one or more holding holes for holding the workpiece,
A dropping supply section for supplying the polishing slurry between the upper and lower surface plates by natural dropping;
A pressure feed supply section for feeding the polishing slurry between the upper and lower surface plates by pressure feed, and further comprising:
A double-side polishing apparatus for a workpiece, characterized in that polishing slurry can be simultaneously supplied between the upper and lower surface plates from the dropping supply section and the pressure supply section.   2. The double-side polishing apparatus for a workpiece according to claim 1, wherein each of the dropping supply section and the pressure supply section includes a flow rate adjusting valve that adjusts a flow rate of the polishing slurry.   The double-side polishing apparatus for a workpiece according to claim 1, wherein each of the dropping supply unit and the pressure supply unit has a slurry supply hole.   The double-side polishing apparatus for a workpiece according to any one of claims 1 to 3, wherein the pumping supply unit is provided above the sun gear. The workpiece is held on a carrier plate provided with one or more holding holes for holding the workpiece, the workpiece is sandwiched by a rotating surface plate composed of an upper surface plate and a lower surface plate, and provided at the center of the rotating surface plate. A double-side polishing method for a workpiece, in which both surfaces of the workpiece are polished simultaneously by rotating the rotary platen and the carrier plate relative to each other by rotation of a sun gear and rotation of an internal gear provided on an outer peripheral portion of the rotary platen. Because
A method for double-side polishing a workpiece, wherein the polishing slurry is supplied between the upper and lower surface plates by natural dripping and simultaneously the polishing slurry is supplied by pressure feeding between the upper and lower surface plates.   The double-side polishing method for a workpiece according to claim 5, wherein the flow rate of the polishing slurry by pressure feeding is 5% to 50% of the total flow rate of the polishing slurry.   The double-side polishing method for a workpiece according to claim 5 or 6, wherein polishing slurry is supplied between the upper and lower surface plates by pressure feeding from above the sun gear.

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