JP4290295B2 - Double-side polishing template and double-side polishing method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a double-sided polishing template and a double-sided polishing method using the same, and more particularly to a double-sided polishing template capable of polishing an object to be polished with high flatness and a double-sided polishing method using the same.
[0002]
[Prior art]
In order to manufacture a semiconductor wafer, a single crystal semiconductor ingot is made from polycrystalline silicon by, for example, the Czochralski method, and this ingot is sliced to a predetermined thickness using a multi-wire saw or the like to manufacture a semiconductor wafer.
[0003]
The uneven saw marks present on the surface of the semiconductor wafer are removed and smoothed, and the depth of processing distortion is made uniform, lapping using alumina abrasive grains or the like to make the thickness within the wafer and between the wafers uniform, and so on. It is processed into a smooth and undistorted mirror surface by a mirror polishing process using an abrasive.
[0004]
In the conventional mirror polishing process, a double-side polishing apparatus 31 as shown in FIG. 9 is used, and an abrasive is poured between an upper polishing cloth 34 and a lower polishing cloth 35 provided on an upper surface plate 32 and a lower surface plate 33, respectively. A semiconductor wafer W1 loaded on a template 36 disposed between an upper polishing cloth 34 and a lower polishing cloth 35 is rotated under pressure, and both surfaces of the semiconductor wafer W1 are chemically and mechanically polished by rubbing, thereby processing strain layers. The dirt is removed and the semiconductor wafer W1 is polished into a mirror surface.
[0005]
The conventional template 36 includes a template main body 37 and a storage hole 38 provided in the template main body 37. The template main body 37 is made of a glass epoxy resin made of a single layer, a disc shape, and an inelastic body, and has a thickness thereof. t _p is less than the thickness _{t w} of the semiconductor wafer _{W 1,} which is housed in the housing hole 38.
[0006]
Therefore, when the semiconductor wafer W1 is loaded on the template 36 as described above and is pressure-polished between the upper polishing cloth 34 and the lower polishing cloth 35, the thickness tp of the template main body 37 is obtained as shown in FIG. 10 is thinner than the thickness tw of the semiconductor wafer W1, and a part of the semiconductor wafer W1 protrudes from the template main body 37, so that the upper polishing cloth 34 and the lower polishing cloth 35 are pressed and deformed. As shown in FIG. 3, since the processing pressure applied to the outer peripheral portion W1o of the semiconductor wafer W1 is larger than that of the central portion W1c, the thickness of the outer peripheral portion of the semiconductor wafer W1 after polishing is larger than the thickness of the central portion. It became thin and caused a decrease in flatness.
[0007]
There is a polishing method disclosed in Japanese Patent Laid-Open No. 9-234667 as a method for polishing a semiconductor wafer that prevents surface fringing that occurs on the outer periphery of the semiconductor wafer. This polishing method includes a polishing block, a surface plate, a backing pad, and a polishing block. This is a method for polishing a semiconductor wafer comprising a template and using a backing pad having a higher compression ratio than the polishing cloth.
[0008]
As a problem of this polishing method, the disclosed polishing method is a single-side polishing method in which a backing pad is attached to an upper surface plate and a polishing cloth is provided on a lower surface plate, and a double-side polishing method that is superior in flatness and good in productivity. The point which is not.
[0009]
[Problems to be solved by the invention]
Therefore, there is a demand for a double-sided polishing template and a double-sided polishing method using the same, which can manufacture a semiconductor wafer having a high flatness without reducing the thickness of the outer peripheral portion of the polished semiconductor wafer as compared with the thickness of the central portion. It had been.
[0010]
The present invention has been made in consideration of the above-described circumstances, and the thickness of the outer peripheral portion of the polished semiconductor wafer is not reduced compared to the thickness of the central portion, and both sides on which a highly flat semiconductor wafer can be manufactured. An object is to provide a polishing template and a double-side polishing method using the same.
[0011]
[Means for Solving the Problems]
The invention of claim 1 of the present invention made to achieve the above-mentioned object has a template main body comprising an elastic body and two disc-shaped inelastic bodies provided on both sides of the elastic body, and The template body is thicker than the thickness of the flat plate-shaped workpiece before polishing in the non-pressurized state, and the thickness is in the pressurized state. The gist of the present invention is a double-side polishing template characterized by being equivalent to the thickness of an object to be polished accommodated in the accommodation hole .
[0012]
The gist of the invention of claim 2 is the double-side polishing template according to claim 1, wherein the elastic body has the same disc shape as the inelastic body.
[0014]
The gist of the invention of claim 3 is the double-side polishing template according to claim 1 or 2, wherein the object to be polished is a semiconductor wafer.
[0015]
In the invention of claim 4 of the present application, the object to be polished is compared with the double-sided polishing template that has a disk shape, is formed to be compressible, and has a thickness greater than that of the flat plate-shaped object to be polished when not polished. After loading and placing between the upper and lower polishing cloths, the polishing cloth is rotated to a predetermined amount by compressing the double-side polishing template to a thickness equivalent to the object to be polished by this polishing cloth. The gist is that it is a double-side polishing method.
[0016]
The gist of the invention of claim 5 is the double-side polishing method according to claim 4 , wherein the object to be polished is a semiconductor wafer.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a double-side polishing template and a double-side polishing method using the same according to the present invention will be described below with reference to the accompanying drawings.
[0018]
FIG. 1 is a perspective view showing a template according to the present invention with a part cut away.
[0019]
The template 1 includes a disk-shaped elastic body 2 and two disk-shaped inelastic bodies 3 a and 3 b which are the same size as the elastic body 2 and are provided on both sides of the elastic body 2. The template main body 4 formed in a three-layer structure has a plurality, for example, three storage holes 5 for an object to be polished. It has a template body 4 has a thickness T _p, non-abrasive (not used) during workpiece polished by a flat plate shape and is thicker than the thickness T _W1 before polishing, for example, a semiconductor wafer W.
[0020]
The elastic body 2 preferably has a flat plate shape, and may be composed of a plurality. The material is preferably the same material as urethane foam, SUS, or polishing cloth, and the thickness of the elastic body 2 is preferably such that the elastic body 2 is elastically deformed within the polishing allowance range. The thickness may be less than that of the elastic bodies 3a and 3b.
[0021]
The non-elastic bodies 3a and 3b have rigidity such as glass epoxy resin and SUS generally used as a template member, and are formed of non-elastic members. The thickness of the two non-elastic bodies 3a and 3b (Sum of two sheets) is preferably the difference between the thickness of the polished semiconductor wafer and the thickness when the elastic body 2 is thinned when compressed in the elastic region.
[0022]
The template body 4 is formed by either bonding the elastic body 2 and the non-elastic bodies 3a and 3b after processing into a predetermined shape, or cutting them into a predetermined shape after bonding. The elastic body 2 is inelastic. Since it is the same disk shape as the bodies 3a and 3b, the template has uniform elasticity throughout, and the polishing cloth can be surely brought into a uniform plane state.
[0023]
Further, a tooth portion 6 that meshes with a drive gear and an internal gear provided in the polishing apparatus is formed on the outer peripheral portion of the template body 4 over the entire periphery.
[0024]
The template 1 is formed so that the elastic body 2 and the non-elastic bodies 3a, 3b are in contact with each other over the entire surface. However, as shown in FIG. You may provide only the circumference | surroundings of the storage hole 10 so that the circumference | surroundings of the storage hole 10 formed in the elastic bodies 9a and 9b may be surrounded. In this case, the compression state of the template can be changed as necessary, and a template having a wide application range can be obtained.
[0025]
Next, a method for polishing both sides of a semiconductor wafer using a template according to the present invention will be described.
[0026]
First, a double-side polishing apparatus used for double-side polishing of a semiconductor wafer will be described.
[0027]
As shown in FIG. 3, the double-side polishing apparatus 11 has a lower polishing cloth 12 on which the semiconductor wafer W loaded in the template 1 is placed, and a lower surface plate 13 to which the lower polishing cloth 12 is attached. The disc 13 is a disc body having a circular opening formed at the center, and a thick cylindrical column 14 is provided on the lower surface of the disc 13 so as to continuously extend downward. The support column 14 is fixed to a main body frame (not shown) of the double-side polishing apparatus 11.
[0028]
A rotary shaft 15 is inserted into the column 14, and a drive gear 16 is provided at the upper end of the rotary shaft 15 so as to be substantially at the same horizontal position as the upper surface of the lower surface plate 13. The rotating shaft 15 is connected to a driving device (not shown) below and is rotatable. Further, a thin cylindrical outer structure 17 that covers the lower surface plate 13 in an annular shape is provided outside the lower surface plate 13 so as to have a common axis with the drive gear 16.
[0029]
The outer structure 17 has an inner peripheral flange 18 at the inner edge of the upper end, and an inner gear 19 is formed along the inner peripheral surface of the inner peripheral flange 18 so as to face the drive gear 16.
[0030]
A plurality of gears 6 are arranged between the drive gear 16 and the internal gear 19, and the tooth portions 6 formed on the outer periphery thereof are meshed with the drive gear 16 and the internal gear 19, respectively. By this meshing, the template 1 operates as a planetary gear with respect to the drive gear 16 and the internal gear 19 respectively, and the template 1 revolves while rotating by the rotational drive of the rotating shaft 15.
[0031]
An upper polishing cloth 21 attached to the upper surface plate 20 is provided on the upper surface of the semiconductor wafer W so as to be slidable. The upper surface plate 20 has an opening having the same shape as the opening of the lower surface plate 13 in the center thereof, and is a thick disk body whose outer diameter is substantially equal to that of the lower surface plate 13, and is connected to a driving device (not shown). Thus, the upper surface plate 20 is rotated in the same manner as the axis of the drive gear 16.
[0032]
To double-side polish a semiconductor wafer W using the double-side polishing apparatus 11 as described above, first, as shown in FIGS. 1 and 4, the semiconductor wafer W is accommodated in each accommodation hole 5 of the template 1, and the semiconductor The wafer W is loaded on the template 1.
[0033]
Thereafter, the template 1 loaded with the semiconductor wafer W is attached to a double-side polishing apparatus 11 as shown in FIG. Alternatively, after attaching the template 1 to the double-side polishing apparatus 11, a semiconductor wafer may be stored in each storage hole 5 of the template 1.
[0034]
The template 1 is mounted on the double-side polishing apparatus 11 by placing the template 1 on the lower polishing cloth 12 and placing the upper polishing cloth 21 in contact with the upper surface of the semiconductor wafer W from above. At this time, as shown in FIG. 4, the template body 4 is formed such that the thickness T _p1 is thicker than the thickness T _W1 before polishing of the semiconductor wafer W, so that the non-elastic body 3 a and the upper polishing cloth 21 are formed. Are in contact with each other, but the semiconductor wafer W and the upper polishing cloth 21 are not in contact with each other, and a gap g is formed between the semiconductor wafer W and the upper polishing cloth 21.
[0035]
Next, as shown in FIG. 3, the driving gear 16 is rotated in the direction of the arrow in the figure while injecting the abrasive into the upper and lower surfaces of the semiconductor wafer W, and the template 1 is rotated in the direction opposite to the driving gear 16. By this rotation, the semiconductor wafer W is polished by rubbing the lower surface thereof against the upper surface of the lower polishing cloth 12 while drawing a planetary orbit on the lower polishing cloth 12. Further, the upper surface plate 20 is rotated in the direction opposite to that of the drive gear 16, whereby the upper surface of the semiconductor wafer W is rubbed against the lower surface of the upper polishing cloth 21 and polished.
[0036]
During this polishing step, as shown in FIG. 5, the upper surface plate 20 and the upper polishing cloth 21 provided with the upper surface plate 20 are lowered, and the template 1 and the semiconductor wafer W loaded in the template 1 are The upper polishing cloth 21 and the lower polishing cloth 12 are pressed. Since the elastic body 2 of the template 1 is compressed, the thickness _{TP1 of the} entire template 1 is reduced to become _TP2 , and the template 1 thickness _TP2 is constantly being polished during polishing of the semiconductor wafer W to be polished. The thickness becomes the same as the thickness _TW2 .
[0037]
Accordingly, the semiconductor wafer W contacts the upper polishing cloth 21 and the lower polishing cloth 12 in a uniform state over the entire surface (entire area).
[0038]
Further, as shown in FIG. 6 (a), the semiconductor wafer W is uniformly pressed from both sides by the upper polishing cloth 21 and the lower polishing cloth 12 during the polishing process, as shown in FIG. 6 (b). The upper polishing cloth 21 and the lower polishing cloth 12 apply a uniform processing pressure to the semiconductor wafer W. For this reason, in the semiconductor wafer W to be polished, the outer peripheral portion of the semiconductor wafer is polished more than the central portion as in the conventional case, the thickness is reduced, and the flatness of the entire semiconductor wafer is not deteriorated. However, a semiconductor wafer with high flatness can be manufactured.
[0039]
In addition, although the example which used the template concerning this invention used for processing of a semiconductor wafer for grinding | polishing was demonstrated, it is also possible to use the template concerning this invention for lapping.
[0040]
This lapping keeps the template loaded with the semiconductor wafer in parallel as in the case of the above polishing and puts it between the upper lap surface plate and the lower lap surface plate, and pours into the upper lap surface plate, the lower lap surface plate and the semiconductor wafer. Wrapping both sides of the semiconductor wafer by rotation and sliding under pressure. Also in this case, a semiconductor wafer with high flatness can be manufactured in the same manner as used for the above polishing.
[0041]
【Example】
Using a template according to the present invention as shown in FIG. 1 and a polishing apparatus as shown in FIG. 3, a silicon wafer having a diameter of 8 inches is polished, the processing pressure during the polishing process and the thickness of the polished silicon wafer Was measured, and the results shown in FIGS. 7 and 8 were obtained.
[0042]
(result)
(1) As shown in FIG. 7, it was found that the working pressure was uniformly applied over the entire surface of the silicon wafer in the example. On the other hand, it was found that a large working pressure was applied to the outer peripheral portion in the conventional example.
[0043]
(2) As shown in FIG. 8, it was found that the example had a uniform thickness over the entire surface of the silicon wafer. In contrast, it has been found that the outer peripheral portion of the conventional example is thinner than the central portion.
[0044]
【The invention's effect】
According to the double-side polishing template and the double-side polishing method using the same according to the present invention, the thickness of the outer peripheral portion of the polished semiconductor wafer is not thinner than the thickness of the central portion, and the semiconductor with high flatness A double-side polishing template capable of producing a wafer and a double-side polishing method using the same can be provided.
[0045]
That is, it has a template main body composed of an elastic body and two flat plate-shaped non-elastic bodies provided on both sides of the elastic body, and the template main body has a flat plate shape that is polished when its thickness is not polished. The semiconductor to be polished is a double-sided polishing template that is thicker than the thickness of the polishing object, has a thickness equivalent to that of the polishing object during polishing, and has a storage hole in which the polishing object is loaded. For the wafer, the outer peripheral part of the semiconductor wafer is polished and thinned as compared with the central part as before, and the flatness of the entire semiconductor wafer is not lowered. Can be manufactured.
[0046]
In addition, since the elastic body has the same disk shape as the non-elastic body, the elastic body has uniform elasticity over the entire template, and the polishing cloth can be surely made to be in a uniform plane state. It can be polished flat.
[0047]
Further, since the elastic body is provided only around the storage hole so as to surround the storage hole, the compression state of the template can be changed as necessary, and a template with a wide application range can be provided.
[0048]
Further, since the object to be polished is a semiconductor wafer, a semiconductor wafer with high flatness can be manufactured.
[0049]
In addition, for a double-sided polishing template having a disk shape that is compressible and thicker than a flat plate-shaped workpiece to be polished when not polished, the workpiece is loaded and between the upper and lower polishing cloths. This is a double-sided polishing method in which a predetermined amount of polishing is performed by rotating the polishing cloth while compressing the double-sided polishing template to a thickness equivalent to the object to be polished. As in the past, the outer peripheral part of the semiconductor wafer is polished more than the center part and the thickness is reduced, and the flatness of the entire semiconductor wafer is not lowered, and the entire semiconductor wafer is manufactured with high flatness. can do.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a template according to the present invention with a part cut away.
FIG. 2 is a cross-sectional view of an embodiment in addition to a template according to the present invention.
FIG. 3 is an explanatory view of a polishing apparatus used in a double-side polishing method according to the present invention.
FIG. 4 is an explanatory diagram showing a use state of a template according to the present invention.
FIG. 5 is an explanatory diagram showing a use state of a template according to the present invention.
FIGS. 6A and 6B are explanatory views showing a use state of a template according to the present invention and a processing pressure state thereof.
FIG. 7 is a result diagram when a polishing test is performed using a template according to the present invention.
FIG. 8 is a result diagram when a polishing test is performed using a template according to the present invention.
FIG. 9 is an explanatory diagram showing a use state of a conventional template.
FIGS. 10A and 10B are explanatory views showing a use state of a conventional template and a processing pressure state thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Template 2 Elastic body 3a Inelastic body 3b Inelastic body 4 Template main body 5 Storage hole 6 Tooth part 7 Template 8 Elastic body 9a Inelastic body 9b Inelastic body 10 Storage hole 11 Double-side polishing apparatus 12 Lower polishing cloth 13 Lower surface plate 14 gear struts 15 in the rotary shaft 16 driving the gear 17 the outer assembly 18 inner peripheral flange 19 20 upper surface plate 21 above the polishing cloth W semiconductor wafer _{T p1} thickness _{T W1} thickness _{T p2} polishing in the template of the non-polishing time of template Thickness of semiconductor wafer before polishing _TW2 Thickness during polishing of semiconductor wafer W

Claims (5)

A template body comprising an elastic body and two disc-shaped inelastic bodies provided on both sides of the elastic body, and a storage hole for loading an object to be polished is provided; In the non-pressurized state, the thickness is thicker than the thickness of the flat-plate-shaped workpiece before polishing, and in the pressurized state, the thickness is equal to the thickness of the workpiece stored in the storage hole. Double-sided polishing template.   The double-sided polishing template according to claim 1, wherein the elastic body has the same disk shape as the inelastic body.   The double-side polishing template according to claim 1, wherein the object to be polished is a semiconductor wafer.   For a double-sided polishing template that has a disc shape, is formed to be compressible, and has a thickness greater than that of a flat plate-shaped workpiece to be polished when not polished, loading the workpiece and placing it between the upper and lower polishing cloths A double-side polishing method comprising: polishing a predetermined amount by rotating the polishing cloth while compressing the double-side polishing template to a thickness equivalent to an object to be polished with the polishing cloth after the arrangement.   The double-side polishing method according to claim 4, wherein the object to be polished is a semiconductor wafer.

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