JPH11267963A - Lapping or polishing method for large diameter wafer and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the single weight of a device and disperse the load added to a building floor by inserting a large diameter wafer to a carrier hole eccentrically bored in a carrier to lap or polish the large diameter wafer. SOLUTION: One carrier hole 34 is bored in each of a plurality of carriers 32 arranged on a lower surface plate so as to be off-centered by an eccentric quantity (e) from the center (m) of the carrier 32. The eccentric quantity (e) is set to about 10-20% of the diameter of a wafer W. One large diameter wafer W is inserted to the carrier hole 34. The diameter of the carrier hole 34 is set slightly larger than the diameter of the large diameter wafer W, for example, by 0.5 mm. The diameter of the carrier 32 is set 20-50% of the wafer to be lapped. The lapping or polishing work can be regulated by inserting a dummy wafer Wd made of a synthetic resin such as vinyl chloride resin to a slurry extracting hole 42 as occasion demands.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lapping or polishing method for efficiently lapping or polishing semiconductor silicon single crystal wafers (hereinafter sometimes simply referred to as wafers), particularly large diameter wafers. And an apparatus.

[0002]

2. Related Art In general, a method of manufacturing a mirror-finished semiconductor silicon wafer includes a slicing step of slicing a single crystal rod manufactured by a single crystal manufacturing apparatus to obtain a thin disk-shaped wafer, and a wafer obtained by the slicing step. A chamfering step of chamfering the outer peripheral edge portion to prevent cracking of the
A lapping step of lapping the chamfered wafer to flatten it, an etching step of removing processing strain remaining on the chamfered and lapped wafer surface, and a polishing step of finishing the etched wafer surface to a mirror surface And a cleaning step of cleaning the polished wafer.

[0003] The purpose of the lapping step is to obtain the required shape accuracy, such as flatness and parallelism, while making the sliced wafer have a predetermined thickness. In general, it is known that the wafer after the lapping process has the highest shape accuracy, and it is also said that the shape of the final wafer is determined, and the shape accuracy in the lapping process is extremely important.

Conventionally, the lapping technique combines three movements of a concentric lap surface plate, a revolving movement of a circular workpiece holding bracket with respect to the apparatus body, and a rotating motion of a circular workpiece holding bracket. A lapping device for performing lapping by giving a relative motion between a lapping plate and a workpiece is known. This wrapping device has, for example, a configuration as shown in FIGS.

FIG. 7 is a schematic exploded explanatory view of a wrapping device,
FIG. 8 is a schematic cross-sectional explanatory view of the lapping apparatus, and FIG. 9 is a schematic top explanatory view showing a state where the upper lap platen of the lapping apparatus is removed.

In FIG. 7 to FIG.
Has a lower lap surface plate 24 and an upper lap surface plate 26 provided to face each other in the vertical direction. The lower lap surface plate 24
The upper lap platen 26 is rotated in opposite directions by a driving means (not shown).

The lower lap surface plate 24 has a sun gear 28 on the upper surface of a central portion thereof, and an annular internal gear 30 is provided adjacent to a peripheral portion thereof.

Reference numeral 32 denotes a disk-shaped workpiece holding bracket (generally referred to as a carrier). A gear portion meshing with the sun gear 28 and the internal gear 30 is formed on an outer peripheral surface of the bracket, thereby forming a gear structure as a whole. ing. The workpiece holding bracket 32 has a plurality of receiving holes (carrier holes).
34 are drilled. A workpiece W such as a wafer to be wrapped is disposed in the receiving hole 34.

A workpiece holding bracket 32 is placed between the upper and lower lap plates 26, 24, and between a sun gear 28 located at the center of the lower lap plate 24 and an internal gear 30 outside the lower lap plate 24. The gears on the outside of the workpiece holding bracket 32 engage with each other to lower the upper lap plate 26, and the workpiece holding bracket 32 performs a planetary gear motion between the upper and lower lap plates 26 and 24 rotating while facing each other. The workpiece W fits into the receiving hole 34 opened in the workpiece holding bracket 32, and the rotation of the workpiece holding bracket 32 rotates and revolves.

In order to perform a lapping operation, a polishing liquid such as aluminum oxide (Al ₂ O ₃ ) or silicon carbide (SiC), which is called a lap slurry, and a turbid liquid A such as water containing a surfactant are applied to a nozzle 36. From the workpiece W to the gap between the upper and lower lap plates 26, 24 through a through hole 38 provided in the upper lap plate 26 to feed abrasive grains between the workpiece W and the upper and lower lap plates 26, 24. The shapes of the surface plates 26 and 24 are transferred to the workpiece W.

Here, in order to obtain the flatness, it is necessary to faithfully transfer the shapes of the upper and lower lap plates 26 and 24 to the workpiece W, and the upper and lower laps are relatively moved with the workpiece W performing relative motion. The movement of the lap slurry A between the platens 26 and 24 cannot be ignored.

This is because the abrasive grains in the lap slurry A are constantly worn, and the grain size and sharpness change. Here, if the movement of the lap slurry A is biased, a portion to be processed with poorly sharpened abrasive grains having a small particle diameter compared to other portions is immediately thickened in a place where the flow of the lap slurry A is poor.

For this reason, grooves 40 called grids are dug in the upper and lower lap plates 26 and 24 at intervals of 20 mm to 50 mm, and unnecessary lap slurry A and chips are discharged therefrom.

Conventionally, the lapping apparatus as described above, which has been used for lapping a semiconductor silicon single crystal wafer, is used to pursue improvement in productivity as the diameter of a work (semiconductor silicon single crystal wafer) increases. In general, processing is performed without reducing the number of pieces (simultaneous processing) to be performed.

As a result, the size of the wrapping device has been increased, and the weight of the device has been increased accordingly. Although the weight of the lapping device increases in comparison with the nominal diameter, if this is expressed by the actual device weight, approximately 9B = 1.5t, 12B =
2.2. t, 15B = 3.5t, 17B = 4.0t, 2
0B = 5.0t, 22B = 6.5t, 24B = 10.0
t, 30B = 13.0t, 32B = 17.0t-24.
0t.

In the future, there is a demand for using 40B or 50B, and the device weight of 30t and 40t is becoming a reality. In order to install such a heavy-weight wrapping device, the structure of a building or the like also increases the risk as in the prior art, so that the structure must be reconsidered.

The symbol B represents the size of the lapping device or the polishing device in units of inches of the size of the carrier mounted on the device. For example, 20B means a lapping device or a polishing device to which a carrier having a diameter of 20 inches can be mounted.

When the diameter of a work increases and the size of the lapping device increases with the size of the work, the time required for loading the work into the lapping device and taking out the work in the lapping process is inevitably increased. Cannot ignore its effects.

[0019] Even in consideration of automation of the charging operation and the like, there is a difficulty in loading a plurality of wafers into each carrier for a plurality of carriers, and it can be said that practical use is now a step. .

[0020] Grinding with fixed abrasive grains as a substitute for lapping has also been studied from the viewpoint of the lightness of the apparatus and automation due to the use of single wafers, but it has not yet been introduced into mass production processes. Is the current situation. A similar problem also occurs in the polishing step.

[0021]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides the same wafer quality (flatness ≦ 1 μm) as the conventional one and can reduce the unit weight of the apparatus. The load applied to the building floor will be dispersed, and there is no need to reconsider the structure of the building, and existing equipment (for example, a small wrapping device or polishing device) or a partially improved device can be used. In addition, the apparatus productivity with respect to the apparatus occupied area is equal to or greater than that of a case where a large apparatus is introduced, and the automation can be performed, thereby reducing the man-hour of the operator to 1/4. It is an object of the present invention to provide a method and apparatus for lapping or polishing large diameter wafers.

[0022]

In order to solve the above-mentioned problems, a method of the present invention comprises inserting a wafer into a carrier hole formed in a carrier disposed between upper and lower platens, and lapping the wafer. Or, in a lapping or polishing method for performing polishing, one large-diameter wafer is inserted into one carrier hole that is eccentrically opened to one carrier, and the large-diameter wafer is wrapped or polished. And

The large-diameter wafer is 200 m in diameter.
m or more can be targeted.

The carrier diameter is preferably 25 to 50% larger than the diameter of the wafer to be wrapped or polished.

The eccentric amount of the carrier hole is preferably set to 10 to 20% of the wafer diameter.

The rotation speed of the upper and lower platens is 100 to 15
The range of 0 rpm is preferable from the viewpoint of lapping or polishing efficiency.

Lapping or polishing can be adjusted by inserting a dummy wafer into a slurry hole formed in the periphery of the carrier.

In the present invention, since a large-diameter wafer is wrapped or polished with one carrier and one wafer with a small-sized lapping apparatus or polishing, the load of wafer preparation / removal work is extremely reduced and the preparation / removal work is extremely reduced. Automation of the take-out operation can be realized.

The automatic lapping or polishing apparatus of the present invention comprises:
An apparatus for performing the above method, wherein one large-diameter wafer is inserted into one carrier hole that is eccentrically opened in each of a plurality of carriers disposed between upper and lower platens, It is characterized by having an apparatus main body for lapping or polishing the wafer, and robot means installed near the apparatus main body and capable of automatically inserting and removing the wafer into and from the carrier hole.

That is, according to the apparatus of the present invention, by using an existing (commercially available) small-sized lap or polishing apparatus, the position of the carrier is detected and the position of the carrier hole for loading the wafer is confirmed, so that the loading and unloading operations can be performed by the robot. It becomes possible by transportation.

In the present invention, the nominal diameter of a lapping device or a polishing device for the diameter of a wafer to be processed is set to (diameter + 1 to 3) B as a guide.
~ 12B, 14B ~ 15B, φ400 for φ300mm
mm, 18B to 20B can be used. In this case, as described above, 9B = 1.5 t, 1
2B = 2.2t, 15B = 3.5t, 20B = 5.0t
Therefore, there is no problem even if the existing building structure is used as it is.

On the other hand, when such a large-diameter wafer is wrapped by a lapping apparatus having a structure in which a plurality of carrier holes are formed in one carrier as in the conventional case,
32B for φ200mm, 40B for φ300mm, φ
At 400 mm, 52B will be used. The device weight in that case is 32B = 17 to 24t, 40B = 30 to
It is estimated that 35t, 52B = 40-50t, and it is very dangerous to install such a heavy equipment in a conventional building structure, and it is necessary to reconsider the building structure fundamentally. Things.

According to the present invention, the required number of lapping devices or polishing devices is increased in consideration of the production capacity, but the load applied to the building floor is dispersed because the weight of the single device is small. In other words, it is not necessary to reconsider the structure of the building, and the existing apparatus or a part of the apparatus can be improved to effectively lap or polish a large-diameter wafer.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a plan view showing the structure of a sun gear and a lower platen of a lapping apparatus according to the present invention, FIG. 2 is a side view of FIG. 1, FIG. 3 is a view showing a carrier hole, and FIG. FIG. 5 is a side view of FIG. 4, and FIG. 6 is a flow chart showing the procedure of the automatic charging and taking-out operation of the wrapping method of the present invention. In addition, FIG.
5, the same members or similar members as those in FIGS. 7 to 9 are denoted by the same reference numerals.

In FIG. 1, a plurality of carriers 32 arranged on the lower platen 24 are each formed with a single carrier hole 34 eccentric from the center m of the carrier 32 by an eccentricity e (see FIG. 1). 3). The eccentricity e is equal to the wafer W
The diameter is preferably 10 to 20% of the diameter.

One large-diameter wafer W is inserted into the carrier hole 34. The diameter of the carrier hole 34 is slightly larger than the diameter of the large-diameter wafer W to be inserted, for example, 0.5 mm larger. The carrier 32
Is preferably 25 to 50% larger than the wafer to be wrapped.

Reference numeral 42 denotes a carrier hole 3 of the carrier 32.
There are a plurality (three in the example of FIG. 3) of slurry holes drilled in opposition to 4. Lapping or polishing can be adjusted by inserting a synthetic resin dummy wafer Wd such as a vinyl chloride resin into the slurry hole 42 as needed.

In FIG. 2, a lower rotating shaft 44 is rotatably mounted on the lower surface of the lower platen 24. Reference numeral 46 denotes a drive motor provided below the lower rotary shaft 44.
Reference numeral 48 denotes an encoder provided adjacent to the drive motor 46. By the combination of the drive motor 46 and the encoder 48, the lower platen 24 has a structure capable of intermittent feeding.

In FIG. 3, reference numeral 52 denotes a position detecting mark having a predetermined diameter (for example, 1 mm in diameter).
Are embedded in the upper surface of the carrier 32 at three equally spaced points on the circumference at a predetermined distance (for example, 5 mm) from the outer periphery of the carrier.

4 and 5, reference numeral 54 denotes a wafer W
The robot means comprises a robot arm 56 capable of swinging left and right on the carrier 32 and a wafer suction transfer section 58 attached to the tip of the robot arm 56. The wafer suction transfer unit 58 includes a sensor holding disk 62 in which carrier hole detection sensors 60 are arranged at three equal points on the circumference so that the position detection mark 52 can be detected. And a wafer suction member 64 provided at the center of the lower surface.

With the above-described configuration, the automatic charging (automatic insertion) and unloading of wafers in the lapping method of the present invention will be described with reference to the flowchart shown in FIG.

First, the robot means 54 is set at the origin (step 100). Next, the wafer W is received from the previous process by the robot means 54 (step 102).
The received wafer W is suction-held by the wafer suction member 64 of the robot means 54 (step 10).
4).

The position of the carrier 32 is adjusted by rotating the internal gear 30 by a combination of the drive motor 46 and the encoder 48 (step 106). The carrier hole 34 is detected by detecting the position detection mark 52 on the carrier 32 by the carrier hole detection sensor 60 of the robot 54 (Step 110).

The wafer W sucked and held by the wafer suction member 64 is inserted into the carrier hole 34 and charged (step 112). A predetermined lapping process is performed on the wafer W inserted into the carrier hole 34 (Step 114).

When the lapping process is completed, the position of the carrier 32 is adjusted in the same manner as in step 106 (step 116).

Further, the carrier hole 34 is detected in the same manner as in the step 110 (step 120), and the wrapped wafer W is sucked by the wafer suction member 64 of the robot means 54 and taken out from the carrier hole 34 (step 122). ). The removed wafer W is transferred to the next process by the robot means 54 (step 124), and finally, the robot means 54 returns to the origin (step 126).

In the above work procedure, only the lapping process (step 114) is mechanically processed in the conventional method, but the remaining preparation (insertion) work (step 102) is performed.
To 112) and take-out work (steps 116 to 124)
Are manually performed by the worker. Therefore, the automation of the wafer preparation (insertion) and take-out operations achieved by the present invention can significantly reduce labor and contribute to improvement in productivity.

In the method of the present invention, for example, as shown in the above-mentioned embodiment, the number of preparations (insertions) at the time of lapping is limited to five, so that productivity is expected to decrease. 26, 24, internal gear 30 and sun gear 28 are driven by four independent motors, and high productivity is ensured by giving the platen speed of 100 rpm or less and high speed rotation of 100 rpm or more. In addition, it is possible to maintain flatness, which is a quality mission given to lapping. The rotation speed of the platen is preferably 100 to 150 rpm.

Further, regarding the above four motors,
In order to prevent heat generation of the motor, it is possible to use a motor having a structure in which a plate in which cooling water flows is brought into contact with the motor unit, and use a special servomotor having high motor efficiency.

The upper and lower stools 26 and 24 have a structure capable of cooling.
For example, a structure in which the temperature of the upper and lower stools 26 and 24 can be adjusted to a set temperature by a cooling water temperature controller (not shown),
It is preferable to ensure the accuracy of flatness.

Further, it is preferable that the suspended position of the upper stool 26 is calculated so as not to cause bending, and the upper stool 26 is structured to descend horizontally.

In the above description, the case where the present invention is mainly applied to a lapping apparatus and a lapping method has been described. However, the same applies to a polishing apparatus (including a double-side polishing apparatus) and a polishing method (including a double-side polishing method). Of course, it can be applied to

[0054]

As described above, according to the present invention, the same wafer quality (flatness ≦ 1 μm) as the conventional one can be obtained.
As for the equipment productivity with respect to the equipment occupied area, the same or more results can be obtained as compared with the case where a large lapping apparatus or a large polishing apparatus is introduced, and automation becomes possible. There is an effect of reducing to / 4.

[Brief description of the drawings]

FIG. 1 is a plan view showing the structure of a sun gear and a lower surface plate of a lapping device of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is an illustration of a carrier hole.

FIG. 4 is a plan view showing a robot that sucks and conveys a wafer.

FIG. 5 is a side view of FIG. 4;

FIG. 6 is a flowchart showing a procedure of an automatic charging and discharging operation of the wrapping method of the present invention.

FIG. 7 is an exploded perspective view of a conventional wrapping device.

FIG. 8 is a sectional explanatory view of a conventional lapping device.

FIG. 9 is an explanatory top view showing a state where an upper surface plate of a conventional lapping device is removed.

[Explanation of symbols]

22: lapping device, 24: lower surface plate, 26: upper surface plate,
28: Sun gear: 30: Internal gear, 32: Carrier, 34: Carrier hole, 36: Nozzle, 38: Through hole, 40: Partition groove, 42: Slurry hole, 4
4: lower rotating shaft, 46: drive motor, 48: encoder, 52: position detection mark, 54: robot means, 5
6: Robot arm, 58: Wafer suction transfer unit, 6
0: Carrier hole detection sensor, 62: Sensor holding disk, 64: Wafer suction member, A: Wrap slurry,
e: eccentricity, m: carrier center, W: wafer, W
d: Dummy wafer.

Claims (8)

[Claims] 1. A lapping or polishing method for lapping or polishing a wafer by inserting a wafer into a carrier hole formed in a carrier disposed between an upper and lower platen, and eccentrically moving one carrier. 1 pierced
Insert one large-diameter wafer into each carrier hole,
A method for lapping or polishing a large-diameter wafer, comprising lapping or polishing the large-diameter wafer. 2. The method for lapping or polishing a large diameter wafer according to claim 1, wherein the large diameter wafer has a diameter of 200 mm or more. 3. The method for lapping or polishing a large-diameter wafer according to claim 1, wherein the diameter of the carrier is 25 to 50% larger than the diameter of the wafer to be lapped or polished. 4. The method according to claim 1, wherein the eccentric amount of the carrier hole is 10 to 20% of a wafer diameter.
4. The method for lapping or polishing a large-diameter wafer according to any one of 3. 5. The rotation speed of the upper and lower platens is 100 to 15
The lapping or polishing method for a large-diameter wafer according to any one of claims 1 to 4, wherein the rotation speed is 0 rpm. 6. The method for lapping or polishing a large-diameter wafer according to claim 1, wherein a dummy wafer is inserted into a slurry hole formed in a peripheral portion of the carrier. . 7. A step of inserting the large-diameter wafer into the carrier hole, performing a lapping or polishing process on the wafer, and then removing the wafer from the carrier hole. 7. The method for lapping or polishing a large-diameter wafer according to claim 1, wherein the method is performed automatically. 8. An apparatus for carrying out the method according to claim 7, wherein one carrier hole eccentrically opened in each of a plurality of carriers disposed between the upper and lower platens. An apparatus main body for inserting one large-diameter wafer and lapping or polishing the wafer, and a robot installed close to the apparatus main body and capable of automatically inserting and removing the wafer into and from the carrier hole Means for automatic lapping or polishing.