JPS602310A - Inner circumferential type cutter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an internal cutting machine, for example, silicon, GG
This invention relates to an internal circumferential cutting machine that cuts expensive samples such as G with a small cutting margin and with high precision.

[Background of the invention]

The inner circumferential cutting machine rotates an inner circumferential grindstone in which an abrasive grain layer is formed on a donut-shaped grindstone base metal within the grinding wheel surface, and is placed on the inner circumferential side of the inner circumferential grindstone and held on a sample table. The sample is cut by the abrasive grain layer by moving the sample in the radial direction of the inner grindstone, and this inner circumferential cutter can cut a sample with a large cross-sectional area into small pieces with high precision. It is used for cutting with cutting margin.

However, with conventional internal circumferential cutting machines, 1) the minimum cutting distance is 0.28 to 0.35 am, resulting in poor material yield; 2) ridges are produced on the cut surface, making it difficult to There was a problem in that it was not possible to slice accurately.

These problems will be explained using FIG. 1.

FIG. 1 is a sectional view of a main part showing a state in which a sample is being cut by a conventional internal circumferential cutter.

In this FIG. 1, 11 is a donut-shaped grindstone base metal 3
An inner circumferential grindstone 5 formed by forming an abrasive layer 1 along the inner circumference of the inner circumferential grindstone 11 is an ingot for cutting a sample (for example, a silicon ingot), which is disposed on the inner circumferential side of the inner circumferential grindstone 11.
6 is a wafer cut from this cutting ingot 5;
2 is a cutting groove of the cutting ingot 5; 12 is a wafer 6;
This is coolant flowing through the gap between the grinding wheel base metal 3 and the grinding wheel base metal 3. The arrow indicates the direction of movement of the cutting ingot 5, and the inner grindstone 11 rotates in a direction perpendicular to the paper surface.

In the internal circumferential cutting machine configured in this way, the internal circumferential grindstone 1
1 (in a direction perpendicular to the page) and cut the cutting ingot 5.
While moving in the direction of the arrow, the cutting ingot 5 is cut by the abrasive layer 1 while the coolant 12 is supplied.

In this case, the coolant 12 and air flowing through the gap between the wafer 6 and the whetstone base metal 3 create an attractive force between the wafer 6 and the whetstone base metal 3, and the wafer 6 comes into contact with the whetstone base metal 3, causing the whetstone to There is a risk of scratching the base metal 3. Further, due to the imbalance of internal stress occurring in the process-affected layers on both sides of the wafer 6, there is a risk that the wafer 6 will bend and scratch the grindstone base metal 3. When the whetstone base metal 3 gets scratched, the inner whetstone 11
In order to shorten the life of the abrasive grain layer 1 and the grindstone base metal 3, conventionally, steps with a size e=65 to 80 μm are provided on both sides to prevent the contact.

On the other hand, in order to improve the precision of cutting, the rigidity of the inner grindstone 11 must be greater than a certain value, and for this purpose the thickness tb of the grindstone base metal 3 must be at least 0.1 to 0.14 m. Must be.

Therefore, the thickness t of the inner grindstone 11 is at least t=t,
+2e =023~0.30■. Since this includes the runout δ (-50 μm) of the inner grinding wheel 11, the minimum cutting distance is 10 δ as described above.
=0.28-0.35m.

By the way, as mentioned above, the dimension of the step is e-65~8
Even if it is set to 0 μm, the wafer 6 and the grinding wheel base metal 3 often come into contact with each other, and although this has little effect on the life of the inner grinding wheel 11, the pressing force caused by this contact and the inner grinding wheel 11 The inner grindstone 11 is displaced by the vibration, and the position of the abrasive grain layer 1 is changed. For this reason, as described above, undulations occur on the cut surface of the wafer 6, reducing cutting accuracy.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an internal circumferential cutting machine that eliminates the drawbacks of the prior art described above and can cut with a small cutting margin and with high precision.

[Summary of the invention]

The configuration of the internal cutting machine according to the present invention is such that an inner peripheral grindstone formed by forming an abrasive grain layer on a donut-shaped grindstone base metal is rotated within the grinding wheel surface, and the inner peripheral grindstone is rotated on the inner peripheral side of the inner peripheral grindstone. In an internal circumferential cutting machine that cuts the sample with the abrasive grain layer by moving the sample arranged and held on the sample table in the radial direction of the inner circumferential grindstone, the inner circumferential grindstone is The part of the inner periphery of the grindstone base metal to which the abrasive grains are attached is made thinner than the other parts, and this part is made into an inner periphery grindstone with an abrasive layer formed thereon, and the inside part is inserted into the grindstone entrance part of the cutting groove formed on the sample. A compressed air inflow device or an air inflow guide capable of inflowing compressed air or air from above and below the peripheral grindstone is held on the sample table and moved in synchronization with the sample.

More details are as follows.

As can be seen from the components of the cutting allowance described above, in order to reduce the cutting allowance without deteriorating the cutting accuracy, it is necessary to reduce the dimension e of the step and also to reduce the runout δ.

In order to implement this, the inner circumferential grindstone is made such that the abrasive grain adhesion part on the inner circumference of the whetstone base metal is thinned, an abrasive grain layer is formed in this abrasive grain adhesion part, and the grindstone entrance part of the cutting groove is made thin. Further, a compressed air inflow device is provided that can flow compressed air into the cutting groove.

[Embodiments of the invention]

Hereinafter, the present invention will be explained by examples.

Figure 2 is a plan view showing the main parts of an internal circumferential cutting machine according to an embodiment of the present invention, Figure 3 is a sectional view taken along ■--m of Figure 2, and Figure 4 is a cross-sectional view of Figure 2. Fig. 5 is a pressure distribution diagram along the rotation direction of the grinding wheel when compressed air is introduced into the grinding wheel inlet of the cutting groove in Fig. 3, and Fig. 6 is an enlarged cross-sectional view of
7 is a wafer deformation characteristic diagram showing the amount of deformation of the wafer due to the compressed air; FIG. It is a schematic diagram which expands and shows the cut surface shape of Ueno cut by the internal circumferential cutter.

In each figure, the same parts as in Figure 1 are marked with the same strange rocks. As shown in detail in FIG. 4, 11A has a part on the inner periphery of the whetstone base metal 3A to which abrasive grains are attached (hereinafter referred to as the abrasive grain adhesion part 3a) that is thinner than other parts (for example, by etching). ) and the abrasive grain adhesion part 3a.
This is an inner peripheral grindstone with an abrasive grain layer l formed thereon. Therefore, this inner peripheral grindstone 11A has its abrasive grain layer 1 and grindstone base metal 3A.
The thickness of the inner grinding wheel lIA remains unchanged from that of the conventional one (that is, the life of the grinding wheel and the rigidity of the grinding wheel base metal 3A do not decrease), and the thickness of the inner grinding wheel lIA is reduced by reducing the step dimension e'.
′ can be made thinner than before. In addition, 10th grade,
Inner circumference whetstone 11. It is a bare metal chuck body that is used to tension and secure A.

4 is a compressed air inflow device (details will be described later) that allows compressed air to flow into the grindstone inlet 2a of the cutting groove 2 formed in the cutting ingot 5 from the upper and lower sides of the inner grindstone 11A.
This compressed air inlet device 4 is held on a sample table (not shown) and is movable in synchronization with the cutting ingot 5.

The compressed air inflow device 4 has a compressed air introduction part 4a, a pair of arcuate upper nozzles 4c with a lid and an H-shaped cross-section, in which a plurality of compressed air discharge holes 4b are drilled in a distributed manner. The lower nozzles 4d are arranged to face each other with a predetermined distance d apart,
A compressor (not shown) is installed in the compressed air introduction section 4a.
The compressed air supply hose 13 that is connected to the compressed air supply hose 13 is inserted thereinto.

When the internal cutting machine configured as described above is turned on, the internal grinding wheel 11A rotates in the grinding wheel rotation direction 15, and the cutting ingot 5, together with the compressed air inlet device 4, moves in the sample moving direction 1.
Move to 6. Then, the cutting ingot 5 is cut by the abrasive grain layer 1 with the inner peripheral grindstone 11A positioned between the upper nozzle 4C and the lower nozzle 4d of the compressed air inlet device 4. A coolant (not shown) is supplied between the grinding wheel base metal 3A of the cutting groove 2 and the Ueno 6, and compressed air supplied to the compressed air introduction part 4a of the compressed air inlet device 4 (this supply air The pressure (referred to as primary air pressure) passes through the compressed air discharge hole 4b, enters the grinding wheel inlet portion 2a of the cutting groove 2 from both sides of the inner peripheral grinding wheel 11 as shown by the arrow 14, and cuts the grinding wheel base metal 3A and the cutting ingot 5. and the gap between the grinding wheel base metal 3A and the wafer 6. The pressure distribution of the compressed air flowing into each gap along the grinding wheel rotation direction 15 is as shown in FIG. Due to the action of the compressed air having this pressure distribution, a repulsive force acts between the grindstone base metal 3A and the wafer 6. The magnitude of this repulsive force is larger than the above-mentioned attractive force, and is still smaller than the bending moment due to the imbalance of internal stress generated in the process-affected layers on both sides of the wafer 6. The amount of deformation of Ueno 6 due to this repulsive force is the curve 8 in Figure 6 (when -th air pressure === 11., / C,,) 9 with respect to the grinding wheel cutting depth C (see Figure 2). Curve 7 (when the negative air pressure is −2 Kg/crt), for example, when the negative air pressure is 2 Kg/crt
When the depth of cut is 80, the wafer 6 is separated from the grindstone base metal 3A by about 80 μm and does not come into contact with the grindstone base metal 38. On the other hand, when compressed air is not allowed to flow in (glue cut by a conventional internal circumferential cutter), the result is curve 9, and the cutting depth of the grindstone is 95 m or more (tatashi,
When the diameter of the wafer 6 is 100 mm), the wafer 6 is attracted to the grindstone base metal 3 and comes into contact with it.

As described above, the compressed air that has flowed into the gap between the grindstone base metal 3A and the wafer 6 separates the wafer 6 from the whetstone base metal 3A and pushes it downward, and at the same time tries to push up the whetstone base metal 38. However, since compressed air also flows into the gap between the cutting ingot 5 and the grindstone base metal 3A, the air pressure applied to the grindstone base metal 3A from above and below is balanced, and the amount of deformation of the grindstone base metal 3A is as shown in FIG. It is extremely small as shown in curve 17 (when the primary air pressure of the upper nozzle 4c = I Kg/ctrl and the primary air pressure of the lower nozzle 4d = 2 n/cd).

In addition, curves 18 and 19 are respectively upper nozzle 4c (-next air pressure "IK9/cnl) and lower/7:k4
This is the amount of deformation to the grindstone base metal 3 when compressed air is introduced only from d (-secondary air pressure = 2 K9/crtl).

In this way, the amount of deformation to the grindstone base metal 3 is small, the vibration of the inner peripheral grindstone 11A is reduced due to the vibration damping effect due to air pressure, and furthermore, since there is no contact between the wafer 6 and the grindstone base metal 3A, The displacement of the inner peripheral grindstone 11A during cutting is significantly reduced, and as shown by the solid line in FIG. 8, the waviness of the cut surface is reduced and cutting accuracy is improved. Note that the curve shown by the broken line is the cut surface shape of the wafer cut after the conventional inner circumferential cutting.

The effect of reducing the cutting allowance will be specifically explained below.

The thickness tb of the whetstone metal 3A is the same as before <0.1~0
．． The length shall be 14m. The amount of deformation of the grindstone metal 3A due to air pressure is negligible, as shown by curve 17 in Fig. 7, but considering the warping of about 20 μm during cutting, the dimension e' of the step is set on the safe side. When e'=30 μm, the thickness t' of the inner grinding wheel 11A is t''' t b +26' = (0,1~0.1'4)+2 X O,030=
0.16 to 0.20% Added to this is the runout amount δ' of the grindstone base metal, which decreases from 50 μm to 20 μm because the whetstone base metal 3A is pressed from above and below by air pressure.

Therefore, the minimum limit of cutting distance is t'+δ'=018~0
22 sea bream, which is a reduction of 0.10 to 0.13 rrtm compared to the conventional 0.28 to 35 bream.

According to the embodiments described above, the cutting allowance is reduced and the material yield is improved. In addition, since the ridges on the cut surface are reduced, the machining allowance for lapping or grinding, which is the next step after cutting, can be reduced.
The manufacturing cost of wafers such as G can be significantly reduced.

In addition, since undulations with large wavelengths cannot be corrected by lapping, they are an obstacle in the process of forming LSI patterns on wafers. Since the wafer thus formed has almost no waviness with a large wavelength, it also has the effect of contributing to an improvement in yield in the pattern forming process.

FIG. 9 is a plan view showing essential parts of an internal circumferential cutter according to another embodiment of the present invention, and FIG. 10 is a sectional view taken along line XX in FIG. 9.

In each figure, parts given the same numbers as in FIG. 2 are the same parts. 20 is a grindstone entrance portion 2a of the cutting groove 2.
A predetermined interval d having a streamlined air introduction portion 20a that allows air to flow into the inner peripheral grindstone 11 from both sides.
A pair of upper guides 20 facing each other and separated by o
b, an air inflow guide consisting of a lower guide 20C; this air inflow guide 20 is movably held together with the cutting ingot 5 by a sample table (not shown);

By attaching the air inflow guide 20 in this way, when the inner circumferential cutter is turned on and the inner circumferential grindstone 11A rotates in the grindstone rotation direction 15, as shown by the arrow 21, air near the air introduction portion 20a is However, as the whetstone base metal 3A changes and approaches the whetstone inlet part 2a, the air introduction part 20
While being compressed by a, it enters the grindstone inlet 2a of the cutting groove 2 from both sides of the inner grindstone 11, and enters the gap between the grindstone base metal 3A and the cutting ingot 5, and the gap between the grindstone base metal 3A and the wafer 6. flows. The air that has flowed in in this way has almost the same effect as the compressed air in the embodiment described above, and prevents contact between the wafer 6 and the grindstone base metal 3A, and also prevents the grindstone base metal 3A from coming into contact with the wafer 6.
The deflection of A can be reduced. Therefore, there is an effect of reducing the cutting margin and reducing the waviness of the cut surface.

The present embodiment described above does not require supplying compressed air to the air inflow guide 20, so it has a practical effect of being simpler in configuration than the embodiment shown in FIG. Examples are upper nozzle 4c and lower nozzle 4d, respectively.
This embodiment is better than the present embodiment in that by adjusting the medical pressure of the compressed air supplied to the grinding wheel base metal 38, the air pressure applied to the grindstone base metal 38 can be balanced and the amount of deformation of the grindstone base metal 3N can be minimized. Are better.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide an internal circumferential cutter that has a small cutting allowance and can cut with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing a state in which a sample is cut by a conventional internal circumferential cutter, and FIG. 2 is a main part of an internal circumferential cutter according to one embodiment of the present invention. The plan view and Figure 3 are as follows:
■-River surface diagram in Figure 2 Figure 4 shows IV-IV in Figure 2.
An enlarged cross-sectional view, FIG. 5 is a pressure distribution diagram along the rotational direction of the grinding wheel when compressed air is introduced into the grinding wheel inlet of the cutting groove in FIG. 3, and FIG. 7 is a deformation characteristic diagram of the grindstone ingot showing the amount of deformation of the grindstone ingot due to the compressed air. FIG. FIG. 9 is a schematic diagram showing an enlarged cut surface shape of a wafer cut by a cutting machine, and FIG. is X in Figure 9
-X sectional view. DESCRIPTION OF SYMBOLS 1... Abrasive grain layer, 2... Cutting groove, 2a... Grinding wheel entrance part, 3N... Grinding wheel base metal, 3a... Abrasive grain adhesion part, 4.
...Compressed air inlet device, 4c...Upper nozzle, 4d...
・Lower nozzle, 5... Cutting ingot, 6... Wafer, 11A... Inner peripheral grindstone, 15... Grinding wheel rotation direction,
16... Sample movement direction, 20... Air inflow guide,
20b...upper guide, 20C...lower guide. Agent Patent attorney Kosaku Fukuda (and 1 other person) 1st Kyo v4 Figure Kaya G Katama Kaya July thing 3 Figure 10 Prisoner

Claims (1)

[Claims] 1. While rotating an inner peripheral grindstone formed by forming an abrasive grain layer on a donut-shaped grindstone base metal within the grinding wheel surface, a sample is placed on the inner peripheral side of the inner peripheral grindstone and held on a sample table. is moved in the radial direction of the inner peripheral grindstone to cut the sample with the abrasive grain layer,
The inner circumferential whetstone is made by making the inner circumferential part of the whetstone metal where the abrasive grains are attached thinner than the other parts, and forming an abrasive grain layer on this part. A compressed air inflow device or an air inflow guide capable of inflowing compressed air or air into the inlet portion from above and below the inner grinding wheel is held on the sample table and moved in synchronization with the sample. Features an internal cutting machine.