JP2001260014A - Sheet-type double-face lapping machine and wafer manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve finishing precision of a lapped silicon wafer. SOLUTION: In this sheet-type double-face lapping machine, a work W as a silicon wafer is lapped by being held between a pair of facing lapping surface plates 11, 21. One lapping surface plate 11 is rotationally driven by a fixed reference shaft 1, and the other lapping surface plate 21 is rotationally driven by a pressurizing shaft 2 and pressed against the work W with pressurizing force. A driving roller device 7 is provided with a reference roller 72 supported from the reference shaft 1 side and a pressurizing roller 73 to be pressed against the work W with desired energizing force, and the work W is rotationally driven. Pressing force of the pressurizing shaft 2 is reduced from a rough machining process to a finishing process, energizing force of the pressurizing roller 73 is also reduced, and therefore, bending deformation is not generated on the work W, and finishing precision is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a sheet-fed double-sided lapping machine for lapping a disk-shaped work such as a silicon wafer from both sides.

[0002]

2. Description of the Related Art Conventional single-wafer double-sided lapping machines are disclosed, for example, in Japanese Patent Application Laid-Open Nos. 10-80861 and 10-2.
There is one disclosed in JP-A-49718.

That is, as shown in FIG. 7, a conventional single-sided double-sided lapping machine is supplied with a machining fluid L containing abrasive grains and rotates while facing each other while sandwiching a disc-shaped work W from both front and back surfaces. It has a pair of lap plates 101 and 102. The single-wafer double-sided lapping machine further includes four guide rollers 103 that come into contact with the outer peripheral surface of the work W from all sides and rotatably support the work W, and rotate the work W supported by the guide rollers 103 at a predetermined angular velocity. And two pairs of drive rollers 104 that are driven to rotate.

The lapping plates 101 and 102 are ring-shaped or disk-shaped members having a diameter slightly more than half of the diameter of the work W, each having a ring-shaped lap surface at the tip and a rotating shaft. Fixed. Wraps 101, 10
The two lapping plates 101 and 1 are driven to rotate at high speed at the same rotational speed in opposite directions by a hollow rotary shaft.
The working fluid L is pressurized and supplied to the inside of the cylinder 02 through a hole in the axis of the rotating shaft. On the other hand, the work W is a silicon wafer which is thin and easily broken, and whose surface is to be precisely and flatly polished.

[0005] One lap surface plate 101 is a lap surface plate on the reference axis side and is fixed in the axial direction, and a work W supported by four guide rollers 103 and two pairs of drive rollers 104 is The lap platen 101 is lightly pressed. Then, the other lap plate 102 (the lap plate on the pressing shaft side) moves in the axial direction from behind, and the work W is pressed against the lap plate 101 with a predetermined pressing force.
, The front and back surfaces of the work W are polished by the two lap plates 101 and 102. At this time, the work W is rotationally driven by the drive roller 104, and the work W
All parts on the front and back sides of the lap plate 10 are sent in order.
Since it comes into sliding contact with the wrap surfaces 1, 102, the front and back surfaces of the work W are polished flat and smooth. Further, since the processing liquid L is always supplied from the inner peripheral side to the lap surfaces of the lap surfaces 101 and 102 during the processing, the lap surfaces and the workpiece W are appropriately cooled while the processing liquid L is being supplied. Is polished by the abrasive grains.

As described above, the diameter of the lapping plates 101 and 102 is slightly larger than the radius of the disk of the silicon wafer serving as the work W.
The area of 102 is only a little more than a quarter of the area of the work W. Therefore, such a single-wafer double-sided lapping machine is configured to be relatively small even if the diameter of the silicon wafer as the work W is considerably large, and is therefore small, lightweight and inexpensive.

[0007]

The prior art single-wafer type double-sided lapping machine has a reference shaft which is driven by supporting one lapping plate 101 at a predetermined position, and a lapping plate 101 with respect to the reference shaft. And a pressing shaft for pressing the other lap surface plate 102 with a predetermined pressing force. The inventors of the present invention have been researching and developing a single-sided double-sided lapping machine of this type, and have filed a patent application for a single-sided double-sided lapping machine as a prior art last year (Japanese Patent Application No. 11-70975). And Japanese Patent Application No. 11-70981).

As shown in FIG. 8, the prior art single-wafer double-sided lapping machine sandwiches an outer edge of a work W which is a silicon wafer and drives the work W to rotate.
3 is provided. Here, one of the pair of drive rollers 72, 73 is a reference roller 72 positioned and fixed on the reference shaft 1 side, and the other is pressed and urged from the pressure shaft 2 side toward the reference roller 72. Pressure roller 73. And the drive roller device 7
An air cylinder (not shown) is provided for urging the pressing roller 73 toward the reference roller 72 with a predetermined urging force.
Therefore, while the work W is being wrapped, the work W is placed between the pressure roller 73 pressed and urged with a constant urging force and the reference roller 72 with the position of the rotating shaft fixed. It is held and rotated.

The inventors of the present invention use such a prior art single-sided double-sided lapping machine to perform a lapping stepwise into a plurality of steps including at least a roughing step and a finishing step. I have tried to do it separately. That is, as the process shifts from the roughing process to the finishing process, a wafer manufacturing method in which the pressing force of the pressing shaft is reduced stepwise has been attempted. Then, in the roughing step, the work is polished at high speed to eliminate irregularities in a short time, and in the finishing step, the work is precisely polished, so that both the front and back surfaces of the work can be finished quite precisely.

[0010] However, as the degree of integration of ICs becomes higher, the demands on the finishing accuracy of wafers become more severe, and it is desired to further improve the finishing accuracy.

Therefore, the present invention is a first object to be solved to provide a single-wafer double-sided lapping machine capable of further improving the finishing accuracy of lapping.
Another object of the present invention is to provide a wafer manufacturing method capable of manufacturing a wafer with more precise finishing accuracy using the single-wafer double-sided lapping machine.

[0012]

Means for Solving the Problems In order to solve the above problems, the inventors have invented the following means.

That is, as a result of repeated studies by the inventors, the factors that degrade the wafer finishing accuracy are as follows.
It was found that there was a slight misalignment between the lap surface of the lap surface plate on the reference shaft side and the outer peripheral surface of the reference roller. That is,
It was found that if the positions in the axial direction were slightly deviated from each other, the wafer was bent during lapping according to the magnitude of the deviation, and the finishing accuracy of the wafer was deteriorated. Then, even if the pressing force of the pressing shaft is precisely aligned in the large roughing process, in the finishing process in which the pressing force of the pressing shaft is small, the position of the lap plate and the position of the drive roller are shifted. I discovered what was happening.

It is presumed that the above-mentioned positional deviation is caused by the elastic deformation of both resin-made drive rollers.
Not only that, but the cause has not yet been fully elucidated, but it has been discovered that the wafer is distorted if the clamping force between the two driving rollers is too strong. Also,
In the roughing process in which both lapping plates strongly clamp the wafer, the clamping force of the drive roller needs to be strong.However, due to the large urging force, the force acting on the guide roller also increases, Was also found to be deformed. On the other hand, the inventors have also thought that in the finishing process in which the holding force of both lap surface plates becomes weak, the holding force by both drive rollers is sufficient even if it is weak.

[0015] Such a fact has been gradually found out while trying to precisely measure the distortion of the wafer and performing various tests. For example, when a test for changing the urging force of the drive roller was performed, it was found that there was a relationship between the urging force of the drive roller and the deformation of the wafer because the amount of deformation of the wafer changed.

Therefore, based on the above findings and ideas, the clamping force of the driving roller is adjusted in accordance with the magnitude of the pressing force of the pressure shaft, and the relative position between the lap surface plate and the driving roller is appropriately controlled. As a result, the inventors have invented the following means.

(First Means) A first means according to the present invention comprises a pair of lapping plates for rotating a disk-shaped work opposite to each other while sandwiching the work from both the front and back surfaces, and lapping the front and back surfaces of the work. It is a sheet-fed double-sided lapping machine. This means includes: a reference shaft that moves and positions one of the lap surface plates in the axial direction and axially supports and drives the lap surface plate; And a pressurizing shaft for urging with a predetermined pressing force while rotating and pressing the work. A plurality of guide rollers that abut against the outer peripheral surface of the work and rotatably support the work;
A drive roller device having at least a pair of drive rollers for rotating and driving the work while sandwiching an outer edge of the work. A base table that supports the reference axis, the pressure axis, each of the guide rollers and the drive roller device,
A control device for controlling the reference shaft, the pressing shaft, and the drive roller device.

The feature of the single-wafer double-sided lapping machine of the present means lies mainly in the drive roller device. That is, the pair of drive rollers, a reference roller fixed to the reference shaft side,
And a pressure roller pressed against the reference roller from the pressure shaft side. The drive roller device includes an urging unit for urging the pressure roller toward the reference roller and an adjusting unit for appropriately adjusting the urging force.

Here, the work is mainly assumed to be a semiconductor wafer, but the work is not limited to the wafer, and any work may be used as long as it needs to be polished on both sides with a disk-shaped member. . Further, in the configuration of the driving roller device, the biasing unit and the adjusting unit may be integrated or separate, and either of them may be separate from the main body of the driving roller device. Good.

In this means, the driving roller device has the urging means for urging the pressing roller toward the reference roller and the adjusting means for appropriately adjusting the urging force. The pressing roller can be pressed against the work with the urging force corresponding to the pressure.

That is, first, the position of the lap surface of the lap surface plate on the reference shaft side and the outer peripheral surface of the reference roller are precisely adjusted in a no-load state. When the urging force of the pressure shaft is large in the roughing process, the urging force of the pressure roller is also set large so that the pressure roller does not run idle. Then, the biasing force causes the two drive rollers to be elastically deformed and displaced, and the work undergoes some bending deformation, and the work is slightly distorted.

However, when the lapping process proceeds and the urging force of the pressing shaft is reduced in the finishing process, the urging force of the pressing roller is adjusted to be small. That is, the urging means is adjusted by the adjusting means so that the elastic deformation of the driving roller is reduced and the holding force of the driving roller applied to the work is reduced.

As a result, the position of the lap surface of the lap surface plate on the reference shaft side and the position of the outer peripheral surface of the reference roller are shifted from the roughing process in which the pressing force of the reference shaft is large to the finishing process in which the pressing force is small. As they do, they will almost completely coincide. Then, in the finishing step, deformation of the work due to the clamping force of the driving roller is almost eliminated, and deterioration of the finish accuracy due to the distortion of the work is prevented, so that further improved finish accuracy can be obtained.

Therefore, according to the single-wafer double-sided lapping machine of the present means, there is an effect that the finishing accuracy of the lapping process can be further improved. That is, the first problem described above is solved.

(Second Means) The second means of the present invention is the above-mentioned first means, further comprising a sizing means supported by the base table to measure the thickness of the wafer during lapping. The control device controls the pressure shaft and the drive roller device based on a measurement result of the sizing unit.

According to this means, the thickness of the work can be measured in-process during the lapping process, and can be reflected almost in real time in the control of the pressing force of the pressing shaft and the control of the urging force of the driving roller. become. Therefore, the thickness of the work can be monitored during the lapping process from the roughing process to the finishing process,
Process management can be performed more appropriately. As a result, not only the finishing accuracy of the thickness of the work is improved, but also the lapping time can be reduced.

Therefore, according to this means, in addition to the effect of the first means, not only the accuracy of finishing the thickness of the work is improved, but also the effect of shortening the lapping time can be obtained. is there.

(Third Means) The third means of the present invention is a single-sheet double-sided lapping machine of the first and second means described above.
This is a wafer manufacturing method for lapping a wafer as a work. The feature of this means is that the lapping step comprises at least two steps of a roughing step and a finishing step, and as the process shifts from the roughing step to the finishing step, the pressing force of the pressing shaft is reduced. And the urging force applied to the pressure roller of the drive roller device is reduced.

According to this means, as the lapping process shifts from the roughing process to the finishing process, not only does the pressing force of the pressing shaft decrease, but also the pressing force of the drive roller device is correspondingly increased. The urging force applied to the pressure roller is also reduced. Therefore, as mentioned in the first means,
As the lapping process proceeds, deformation of the work is reduced. Then, the deterioration of the finishing accuracy due to the deformation of the wafer being processed is prevented, so that the finishing accuracy is further improved.

Therefore, according to the wafer manufacturing method of this means, there is an effect that a wafer can be manufactured with more precise finishing accuracy using a single-wafer double-sided lapping machine. That is, the aforementioned second problem is solved.

(Fourth Means) According to a fourth aspect of the present invention, in the above-mentioned third means, the lapping step is performed before the roughing step with the pressing force of the pressure shaft and the driving roller device. And a preliminary step of operating the single-wafer double-sided lapping machine in a state where the urging force applied to the pressure roller is small.

Here, when a lapping process is performed on a wafer, it is usual to start with a roughing process.
In this case, a state in which the processing liquid containing abrasive grains is not sufficiently distributed between both the lapping plate and the wafer in the initial stage of the roughing process may occur. Such a state is likely to occur particularly when cleaning is performed such that the working liquid is also cleanly washed off from both lap surfaces. Then, after that, the next wafer is loaded and set in a dry state, and there is no processing liquid between the lapping plate and the wafer, and the rough processing starts in a state close to dry friction, so the wafer is too large and irregular The wafer may be damaged due to high frictional stress.

Therefore, if the preliminary step is performed with a light load prior to the rough processing step as in the present means, the load applied to the wafer in the preliminary step is small and the wafer is not damaged. Then, the working fluid is supplied in the preliminary process, and the working fluid spreads between both the lapping plate and the wafer,
Even in the rough processing step, a sufficient lubrication state can be obtained between the both lapping plate and the wafer from the beginning of the rough processing step.
As a result, the breakage of the wafer is prevented, so that the yield of the wafer is improved and the manufacturing cost of the wafer is reduced.

Therefore, according to this means, in addition to the effect of the above-described third means, there is an effect that breakage of the wafer is prevented, the yield is improved, and the manufacturing cost of the wafer is reduced.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the single-wafer double-sided lapping machine and the method of manufacturing a wafer according to the present invention will be clearly and fully described in the following examples so that those skilled in the art can understand the present invention. .

Embodiment 1 (Equipment Configuration of Embodiment 1) A single-wafer double-sided lapping machine as Embodiment 1 of the present invention, as shown in a plan view of FIG. The work W has a pair of lap surfaces 11 and 21 for rotating oppositely to each other coaxially while holding the work W from both sides.

The work W is a silicon wafer having a rough surface sliced by sawing from an ingot made of a large single crystal of silicon. The purpose of the single-wafer double-sided lapping machine is to wrap the workpiece W flat and smooth with both front and back surfaces parallel to each other.
The object is to produce a thin disk-shaped silicon wafer whose front and back surfaces are finished smoothly.

In the single-wafer double-sided lapping machine of this embodiment, one lapping platen 11 is moved in the axial direction to position the lapping platen 11, and the lapping platen 11 is pivotally driven to rotate. And a pressing shaft 2 that presses against the work W with a predetermined pressing force while rotating and driving the other lap surface plate 21. 2, a plurality of resin-made guide rollers 31 that abut on the outer peripheral surface of the work W and rotatably support the work W are provided as shown in FIG. In addition, a drive roller device 7 having a pair of drive rollers 72 and 73 for holding the outer edge of the work W and rotating the work W is provided. Further, as shown in FIG. 1 again, there is a base table 100 that directly or indirectly supports the reference shaft 1, the pressing shaft 2, the respective guide rollers 31, and the respective drive rollers 72 and 73.

As shown in FIG. 3, the single-sided double-sided lapping machine of this embodiment also has a control device 5 for controlling the whole of the single-sided double-sided lapping machine of this embodiment. The control device 5 is a programmable numerical control device having a microcomputer as a core. The control device 5 has a function of appropriately controlling the reference shaft 1, the pressing shaft 2, and the drive roller device 7 according to a predetermined program.

Here, in the drive roller device 7, the pair of drive rollers 72, 73 are pressed by the reference roller 72 fixed to the reference shaft 1 side and pressed by the reference roller 72 from the pressure shaft 2 side. And a pressure roller 73. Drive roller device 7
Has an air cylinder 74 as urging means for urging the pressing roller 73 toward the reference roller 72 and an electropneumatic regulator 76 as adjusting means for appropriately adjusting the urging force. Then, the pressing roller 73 is
The urging force generated by the pressure roller 73 to pinch the workpiece W with the work 2 is adjusted by the controller 5 via the D / A converter 78 by the electropneumatic regulator 76, and is appropriately set.

The single-sided double-sided lapping machine of this embodiment
The apparatus further includes an in-process sizing device 4 that is supported by the base table 100 and that measures the thickness of the work W during lapping. And the control device 5
Has a function of appropriately controlling the pressing force applied to the pressing shaft 2 and the urging force applied to the pressing roller 73 of the drive roller device 7 based on the measurement result of the in-process sizing device 4.

Hereinafter, the configuration of the single-sided double-sided lapping machine of this embodiment will be described in more detail.

As shown in the plan view of FIG. 1 again, the single-wafer type double-sided lapping machine of the present embodiment is supplied with a working fluid L containing abrasive grains and opposed to each other while sandwiching a disc-shaped work W from both front and back surfaces. And a pair of lap plates 11 and 21 that rotate in opposite directions
Having. Further, as shown in FIG. 2 again, there are three guide rollers 31 that abut on the outer peripheral surface of the work W and support the work W rotatably from three directions. Further, a pair of opposing surfaces (not shown) opposing each other to cover the vicinity of the outer edge portion of the work W contacting each guide roller 31 with a predetermined gap between the front and back surfaces thereof, W
Fluid supply hole 3 for supplying purge fluid P toward
Each of the guide rollers 31 has three purge devices 3 in which 0 is formed. That is, each purge device 3 has a built-in guide roller 31 and rotatably supports the guide roller 31.

That is, as shown in FIG. 1 again, the single-wafer double-sided lapping machine of this embodiment has a base table 100, a reference shaft 1 slidably supported on the base table 100, and a reference shaft. 1 and a pressure shaft 2 coaxially opposed and supported on a base table 100. Further, as shown in FIG. 2 again, the portal column 8 is fixed on the base table 100 across the reference shaft 1 and the pressing shaft 2. The gate-shaped support 8 has a pair of lower purging devices 3 covering the guide rollers 31, a retracting device 6 supporting the purging device 3 immediately above the work W, and rotationally driving the work W at a predetermined angular velocity. The driving roller device 7 is fixed.

The reference shaft 1 has a built-in motor 12 and
And a lap surface plate 11 attached to the tip of a rotating shaft driven to rotate by the motor. The lapping plate 11 is a hollow cylindrical member that is short in the axial direction, and the lap surface 11a with which the lapping plate 11 slides on the workpiece W has a ring shape. Then, in the internal space of the lap surface plate 11, a slurry-like working fluid L containing abrasive grains is passed through a working fluid supply hole 10 penetrating the axis of a rotating shaft driven to rotate by a built-in motor 12. It is supplied under pressure.

The reference shaft 1 is mounted on a pair of parallel rails 14 formed on the base table 100, and a ball screw drive motor 13 is provided behind the reference shaft 1 in the axial direction. It is fixed to the table 100. The reference shaft 1 is provided with a ball screw driving motor 13 for driving a ball screw 15 (see FIG. 3) mounted below the reference shaft 1.
Thereby, it is possible to move in the axial direction along the rail 14.

On the other hand, similarly to the aforementioned reference shaft 1, the pressurizing shaft 2 has a built-in motor 22 (see FIG. 3) and a lap surface plate 21 attached to the tip of a rotating shaft driven to rotate by the motor. And The lap surface plate 21 has the same configuration as the lap surface plate 11 of the reference shaft 1, and the pair of lap surface plates 11 and 21 have respective lap surfaces 11a and 12a.
Are arranged so as to face each other and to face each other coaxially. The working fluid L is also applied to the internal space of the lap surface plate 21 on the side of the pressurizing shaft 2 through the working fluid supply hole 20 which also penetrates the axis of the rotating shaft driven by the built-in motor 22. Pressure supplied.

However, unlike the reference shaft 1, the pressing shaft 2 is not disposed on the rail, but can be slightly moved in the axial direction by two pressing cylinders 23 disposed in parallel. is there. That is, the pressing shaft 2 is configured such that the lap plate 21 of the pressing shaft 2 is pressed against the work W by the pressing cylinder 23 with a predetermined pressing force. The pressing force applied to the pressing shaft 2 by the pressing cylinder 23 is appropriately set by the control device 5.

The retracting device 6 supports the purging device 3 which covers and supports the guide roller 31 immediately above the work W, and retreats the purging device 3 when the work W is replaced so that the work W can be taken in and out. It is a device for making.

The drive roller device 7 is, as shown in FIG.
It has a driving motor 71 fixed to the above-described portal 8 and a reference roller 72 rotatably supported on the portal 8 by a support member having a built-in bearing. Drive motor 7
Reference numeral 1 denotes a motor that drives the reference roller 72 to rotate at a desired number of rotations. The driving roller device 7 also includes a reference roller 72.
And a spring 75 for urging the pressure roller 73 away from the work W, and an air cylinder 74 for pressing the pressure roller 73 against the work W against the urging force of the spring 75. Have.

The pair of drive rollers 72 and 73 are both frustoconical resin rollers, and as shown in FIGS. 1 and 2 again, the rotation axis of the work W and the two drive rollers 72 and 73 are positioned relative to the work W. The rotation axis 73 is disposed at an angle and a position where the rotation axis intersects like a bevel gear. therefore,
When the work W is rotationally driven by being sandwiched between the pair of drive rollers 72, 73, the contact surface between the outer edge of the work W and the drive rollers 72, 73 is in contact only by rolling, and does not make sliding contact. Therefore, the polishing action hardly occurs.

As shown in a schematic plan view in FIG. 4, an air source 74 for urging the pressure roller 73 is provided with an air source 7.
7 is supplied with working air at a desired pressure via an electropneumatic regulator 76. Therefore, the pressure roller 73 is pressed with the desired urging force toward the reference roller 72 via the work W.

The in-process sizing device 4 is disposed at a position substantially opposite to the drive roller device 7 with the axis of the work W interposed therebetween, as shown in a schematic plan view in FIG. The in-process sizing device 4 is essentially a work W
Are a pair of displacement sensors disposed so as to sandwich the sensor in the axial direction. That is, the in-process sizing device 4 includes the adjusting screw 4
2 has a pair of sensor portions 43 whose length is adjusted.
4 lightly touches the outer edges of the front and back surfaces of the work W. The tip of each diamond tip 44 is formed into a round shape with an appropriate curvature, and care is taken so as not to damage the work W even if it touches the work W.

The slight inclination of the sensor unit 43 is as follows.
The signal is converted into an electric signal by a differential transformer type sensor incorporated in the main body 41, converted into a digital signal by an A / D converter (not shown), and input to the control device 5. In this way, the displacements of the front and back surfaces of the work W are measured in-process by the in-process sizing device 4, and the difference is calculated by the control device 5. therefore,
During the lapping process, the thickness of the work W is measured in real time. The main bodies 41 are fixedly supported by a support member 40 in a row in the horizontal direction, and the support member 40 is fixed to the portal column 8.

As shown in FIG. 2 again, each of the purging devices 3 has a guide roller 31 built therein and is rotatably supported. The purging device 3 has a pair of opposing surfaces that cover the vicinity of the outer edge of the work W abutting on the guide roller 31 with a predetermined gap between the front and back surfaces thereof, and a work opening and opening on both opposing surfaces. A purge fluid supply hole 30 for supplying the purge fluid P toward W is formed.

That is, each of the purging devices 3 is formed with a pair of opposing surfaces that oppose each other to cover the vicinity of the outer edge of the work W abutting the guide roller 31 with a predetermined gap between the front and back surfaces thereof. I have. Furthermore, each purging device 3
Are formed with a pair of purge fluid supply holes 30 which are respectively opened on both opposing surfaces and supply the purge fluid P toward the work W. Both opposing surfaces form a slot with a gap of a predetermined dimension larger than the thickness of the work W.
Then, the outer edge of the work W fits into this slot with a predetermined gap, and the outer circumferential surface of the work W comes into contact with the outer circumferential surface of the guide roller 31 rotatably housed in the purge device 3 so as to roll. Has become.

Therefore, at the opening of the slot of each purging device 3, the purge fluid P which vigorously flows out of the slot collides against the slow flow of the working liquid L traveling on the front and back surfaces of the work W, Working fluid L to slot
To prevent infiltration. As a result, the guide roller 31 comes into contact only with the outer peripheral surface of the work W and the purge fluid P, and the machining fluid L
Do not touch.

The working liquid L is a slurry liquid containing a large amount of abrasive grains using water as a solvent. On the other hand, since the purge fluid P is water and the water is the solvent of the working fluid L, no inconvenience occurs even if the purge fluid P is mixed with the working fluid L.

(Wafer Manufacturing Method of the First Embodiment) In the wafer manufacturing method as the first embodiment of the present invention, the work W which is a silicon wafer is wrapped by the single-sided double-sided lapping machine of the present embodiment having the above configuration. It is a method of processing.

In the wafer manufacturing method of this embodiment, as shown in FIG. 5, the lapping process R is performed in the order of a preliminary process R0, a rough processing process R1, a medium processing process R2, and a finishing process R3. Become. And the roughing process R
As the process moves from 1 to the finishing process R3 via the intermediate working process R2, the pressing force of the pressing shaft 2 and the urging force applied to the pressing roller 73 of the drive roller device 7 are reduced stepwise. The preliminary process R0 is performed in a state where the pressing force of the pressing shaft 2 and the urging force applied to the pressing roller 73 of the driving roller device 7 are small before the roughing process R1. This is the step of operating the panel.

That is, when the single-wafer double-sided lapping machine of this embodiment is started, first, the work W is carried in and set.
After the short-time preliminary process R0 is completed, full-scale lapping processes R1, R2, and R3 are performed. When the lapping process is completed, the workpiece W is washed, dropped in the processing liquid L, and carried out. Then, the next work W is carried in, and the same process is repeated.

In the wafer manufacturing method of this embodiment, as shown in FIG. 6, the pressing force applied from the pressing shaft 2 to the work W is different in each of the lapping processes R0 to R3. Not only that, but also the clamping force of the work W by the two drive rollers 72 and 73 of the drive roller device 7 is different in each of the steps R0 to R3 in accordance with the pressing force of the pressure shaft 2.

First, in the preliminary process R0, the operation of the single-sided double-sided lapping machine is performed for a very short time while the work W is held between the lapping plates 11 and 21 with a very light pressing force P0. The load on the work W is very small,
The work W is not damaged. Then, the preliminary process R0
, A slurry-like working fluid L containing abrasive grains is supplied, and the working fluid L spreads between the lapping plates 11 and 21 and the work W. Therefore, even if the process shifts to the rough processing step R1, a processing state in which a sufficient working fluid is distributed between the both lap surfaces 11 and 21 and the work W can be obtained from the beginning of the rough processing step R1. As a result, the damage of the work W is prevented, so that the yield of the work W is improved and the manufacturing cost of the silicon wafer is reduced.

Next, in the roughing process R1, the pressing force P1 of the pressing shaft 2 and the urging force of the pressing roller 73 are both large (see FIG. 4), and the work W is polished on both front and back surfaces at a fast pitch. Rough processing is performed so that there is not much unevenness or distortion. At this time, the pressing roller 73 is pressed in accordance with the pressing force P1 of the pressing shaft 2.
The biasing force is also set large. That is, the pressure of the air supplied to the air cylinder 74 of the drive roller device 7 is appropriately adjusted by the electropneumatic regulator 76 controlled by the control device 5.

In the middle processing step R2, the pressing force P2 of the pressing shaft 2 and the urging force of the pressing roller 73 are both medium, and the surface of the work W is polished at a medium speed, and almost no work is performed. Medium-processed so that there is no unevenness. At this time, the reference shaft 1 retreats due to elastic deformation due to the pressing force P2 of the pressure shaft 2, but the urging force of the pressure roller 73 is also moderate so that the reference roller 72 is retracted to a size corresponding to this. Set to about. That is, the pressure of the air supplied to the air cylinder 74 of the drive roller device 7 is appropriately reduced.

Finally, in the finishing step R3, the pressing force P3 of the pressing shaft 2 and the urging force of the pressing roller 73 are both small, and the surface of the work W is gently polished and the surface of the work W has almost no irregularities. Finished in a shape. In this case, too, the urging force of the pressure roller 73 is set to be small according to the pressing force P2 of the pressure shaft 2. That is, the pressure of the air supplied to the air cylinder 74 of the drive roller device 7 is further reduced.

The holding force between the driving rollers 72 and 73 is
In the middle processing step R2, it is smaller than the rough processing step R1, and in the finishing processing step R3, it is even smaller. However, as described above, the clamping force of the lap surface plates 11 and 21 is also reduced, so that the clamping force of the drive rollers 72 and 73 overcomes the frictional force generated between the lap surface plates 11 and 21 and the work W. It is enough to rotate the work W.

As described above, in the wafer manufacturing method of this embodiment, the contact between the lap surface 11a of the lap plate 11 on the reference shaft 1 side and the outer peripheral surface of the reference roller 72 is performed in all the lapping processes R0 to R3. The plane matches. therefore,
Driving Roller 7 and Portion of Lapping Plates 11 and 21
The bending deformation of the work W hardly occurs between the work W and the portion sandwiched between the work pieces 2 and 73. As a result, a decrease in processing accuracy due to the bending deformation of the work W is greatly reduced, and a finish accuracy of the work W is greatly improved.

The lapping surface 11a of the lapping plate 11 on the side of the reference shaft 1 and the tangent plane of the outer peripheral surface of the reference roller 72 are adjusted in advance so as to match under no load.

The end of each of the rough processing step R1, the intermediate processing step R2, and the finishing processing step R3 is determined based on the thickness of the work W monitored by the in-process sizing device 4. Therefore, each processing step R1
The switching timing of .about.R3 is properly set, and not only lapping is performed in a relatively short time, but also the finished thickness of the work W is controlled with high accuracy.

Further, as described above, in all the lapping processes R0 to R3, the clamping force of the driving rollers 72 and 73 overcomes the frictional force generated between the lapping plates 11 and 21 and the work W and the work W Is large enough to rotate. Therefore, there is no inconvenience that the driving rollers 72 and 73 idle and the work W is not rotated at a predetermined angular velocity.

(Effect of Embodiment 1) As described in detail above,
The single-wafer double-sided lapping machine and the method of manufacturing a wafer according to the present embodiment exhibit three effects, which are roughly divided as follows.

First, since the work W hardly bends in the finishing step as described above, the finishing accuracy of the front and back surfaces of the work W is greatly improved not only in the prior art but also in the prior art. effective.

Second, the in-process sizing device 4
Since the thickness of the work W is precisely monitored in each of the lapping processes R0 to R3, the accuracy of the process control relating to the thickness is increased, and the finishing accuracy of the thickness of the work W is extremely high. is there. In addition, since the processing steps R1 to R3 are switched based on the thickness instead of the time control, the processing time can be shortened.

Third, before the roughing step R1, the preliminary step R
0, and in the roughing process R1, the working liquid L is distributed from the beginning to the sliding contact surface between the lapping surfaces 11 and 21 and the work W, so that the work W is less likely to be damaged. As a result, the yield of the work W is improved, so that the cost of the work W can be reduced.

(Modification 1 of Embodiment 1) In the wafer manufacturing method of this embodiment, as shown in FIG.
1. In the middle processing step R2 and the finishing processing step R3, the pressing force of the pressing shaft 2 and the urging force of the pressing roller 73 are switched in a stepwise manner. However, as a first modification of the present embodiment, the finishing step R1 is performed from the beginning of the roughing step R1.
Until the end of Step 3, it is possible to implement a wafer manufacturing method in which the pressing force of the pressing shaft 2 and the urging force of the pressing roller 73 are continuously and gradually reduced. This modification can be easily implemented by the single-sheet double-sided lapping machine of the first embodiment only by modifying the control program of the control device 5 as described above.

According to this modification, the lapping table 1 is provided from the beginning of the roughing step R1 to the end of the finishing step R3.
The holding force of the work W by the reference numerals 1 and 21 can be kept at an optimum value. Therefore, if an appropriate program is given to the control device 5, there is an effect that the processing time can be shortened without any deterioration in finishing accuracy.

[Brief description of the drawings]

FIG. 1 is a plan view showing the configuration of a single-wafer double-sided lapping machine as a first embodiment;

FIG. 2 is a side view showing the configuration of a single-wafer double-sided lapping machine as the first embodiment;

FIG. 3 is a schematic diagram showing the configuration of a single-wafer double-sided lapping machine as a first embodiment;

FIG. 4 is a schematic diagram showing a configuration of a main part of a single-wafer double-sided lapping machine as a first embodiment;

FIG. 5 is a flowchart illustrating a wafer manufacturing method according to the first embodiment.

FIG. 6 is a time chart illustrating a wafer manufacturing method according to the first embodiment.

FIG. 7 is a perspective view showing a configuration of a main part of a single-wafer double-sided lapping machine according to a conventional technique.

FIG. 8 is a schematic diagram showing a main part configuration of a single-wafer double-sided lapping machine according to the prior art.

[Explanation of symbols]

100: base table 1: reference axis 10: machining fluid supply hole 11: lap surface plate (ring shape) 11a: lap surface 12: built-in motor 13: ball screw drive motor 14: rail 15: ball screw 2: pressurization Shaft 20: machining fluid supply hole 21: lap surface plate (ring shape) 21a: lap surface 22: built-in motor 23: pressurizing cylinder 3: purge device 30: purge fluid supply hole 31: guide roller 4: in-process sizing Apparatus (as sizing means) 40: Supporting member 41: Main body 42: Sensor adjusting screw 43: Sensor 44: Diamond chip 5: Control device 6: Evacuation device 7: Driving roller device 71: Driving motor 72, 73: Driving roller (outer peripheral surface is a conical surface) 72: Reference roller 72a: Outer peripheral surface (tangential plane of) 73: Pressure roller 74: Air cylinder (with 75: Spring 76: Electro-pneumatic regulator (as adjusting means) 77: Air source 78: D / A converter 8: Portal type L: Working liquid (slurry containing water as solvent and abrasive grains) P: Water (As a purge fluid) W: Work (disk-shaped silicon wafer) R: Lapping process R0: Preliminary process R1: Rough machining process R2: Medium machining process R3: Finishing process 101, 102: Lapping plate 103: Guide roller 104: drive roller

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsuji Osaka 1-1-1 Asahi-cho, Kariya-shi, Aichi Toyota Machine Works Co., Ltd. (72) Inventor Hiroshi Suzuki 1-1-1 Asahi-cho, Kariya-shi, Aichi Toyoda Machine Inside (72) Inventor Toshio Murakami 1-1-1 Asahi-cho, Kariya-shi, Aichi Toyota Machine Works Co., Ltd. (72) Inventor Hideki Iwai 1-1-1, Asahi-cho, Kariya-shi, Aichi Prefecture Toyoda Machine Works Co., Ltd. ( 72) Inventor Sadaaki Hagino 555-1, Nakanotani, Annaka-shi, Gunma F-term in the Super Silicon Research Laboratories Co., Ltd. 3C043 BC06 CC07 CC11 DD06 EE04 3C058 AA07 AA18 AB01 AB04 AB06 AC01 BA02 BA05 BB02 BC02 CB01 DA18

Claims (4)

[Claims] 1. A pair of lap plates for rotating a disk-shaped work facing each other while sandwiching the work from both front and back sides, and lapping the front and back surfaces of the work, A reference shaft that is moved and positioned in the longitudinal direction and is rotatably driven while pivotally supporting the lap surface plate, and is biased with a predetermined pressing force while being rotationally driven while pivotally driving the other of the lap surface plates. A pressure shaft that presses against the work, a plurality of guide rollers that abut against the outer peripheral surface of the work and rotatably support the work, and at least one pair of drives that rotate the work by sandwiching an outer edge of the work. A driving roller device having rollers; a base table supporting the reference shaft, the pressing shaft, the guide rollers and the driving roller device; and a control for controlling the reference shaft, the pressing shaft, and the driving roller device. With a device In the leaf-type double-sided lapping machine, the pair of drive rollers are a reference roller fixed to the reference shaft side, and a pressure roller pressed against the reference roller from the pressure shaft side. The single-sided double-sided lapping machine according to claim 1, wherein the roller device includes an urging unit that urges the pressing roller toward a reference roller and an adjusting unit that appropriately adjusts the urging force. 2. A sizing means which is supported by the base table and measures the thickness of the wafer during lapping, wherein the control device controls the pressure based on a measurement result of the sizing means. The single-sided double-sided lapping machine according to claim 1, wherein the single-sided double-sided lapping machine controls a shaft and the drive roller device. 3. A wafer manufacturing method for lapping a wafer as the work by using the single-wafer double-sided lapping machine according to claim 1, wherein the lapping step is at least performed. It comprises two steps, a rough processing step and a finishing processing step. As the process moves from the rough processing step to the finishing processing step, the pressing force of the pressing shaft and the attachment applied to the pressing roller of the drive roller device are changed. A method for manufacturing a wafer, wherein the power is reduced. 4. The method according to claim 1, wherein the lapping process is performed before the roughing process in a state where the pressing force of the pressing shaft and the urging force applied to the pressing roller of the driving roller device are small. The wafer manufacturing method according to claim 3, further comprising a preliminary step of operating the leaf-type double-sided lapping machine.