JPH06254841A - Method for recovering of semiconductor water - Google Patents

Abstract

PURPOSE:To provide a method wherein breakage generated by bringing a blade edge of a slicer into contact with the crosssection of a wafer is prevented from occurring and two pieces of wafers divided by cutting are recoverable together. CONSTITUTION:In a cutting process wherein a silicon semiconductor wafer W is cut into two pieces from the center of the thickness by means of an inner peripheral slicer B, after the wafers under a condition where they are cut to the reinforcing part P by means of the inner peripheral slicer B are supported respectively by means of an independent supporting stage 1 and 2, the wafers are completely cut and divided and the wafers W1 and W2 are moved to the central part C of the inner peripheral slicer B under a condition where a specified distance is held between the wafers W1 and W2 and water is sprayed between both wafers W and cut faces of both wafers W are brought into contact with each other and the tightly contacted and integrated both wafers are pinched by means of a pinching body to recover two pieces together.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering a silicon semiconductor wafer, and more particularly, when a silicon semiconductor wafer is cut into two parts in the thickness direction by an inner peripheral slicer, the individual wafers are cut by cutting. It relates to a method of rational recovery without damaging.

[0002]

2. Description of the Related Art Conventionally, as a processing method for forming a discrete substrate by forming impurity diffusion layers on both front and back surfaces of a silicon semiconductor wafer, the above silicon semiconductor wafer is processed from its thickness center to its inner periphery. A specific processing method of so-called “two-piece cutting”, in which two discrete substrates are obtained by cutting into two pieces with a type slicer, can be roughly classified into two. One of them is to form a pillar like an ordinary silicon ingot by closely adhering a large number of diffused wafers, and cut them one by one with an inner peripheral slicer, or with a wire saw at the same time. Is the way to
The other is a method of cutting a diffused wafer into single wafers by an inner peripheral slicer. The present invention relates to the latter method, the basic processing concept of which is JP-A-55-10.
No. 370, and JP-A No. 64-19729. However, in the above invention,
It does not specifically disclose a method of supplying a wafer and collecting a processed wafer, which are indispensable for carrying out the two-piece processing on a mass production scale.

[0003]

When processing two wafers that have been subjected to diffusion processing as described above, one wafer is cut and divided into two wafers. The number is twice the number of grooves on the supply side wafer carrier, and because of the space between the wafer carriers and their movement,
This leads to an increase in the size of the cutting device. As a countermeasure against this, a wafer carrier on the recovery side is divided into two grooves and two wafers.
It is rational to collect them one by one. FIG. 8 shows a conventional cutting and processing apparatus that can carry out the above-described recovery method.
In the figure, 101 is a holding plate made of polar ceramics, which holds a wafer W having diffusion layers Wa formed on both sides by suction, and a blade B which is tensioned by a chuck body 104.
It is located on the rotation center line C of (a in the figure). During processing, the holding plate 101 cuts the thickness center of the wafer W while moving toward the blade edge B1 on the inner circumference of the blade B, and cuts when cut into the reinforcing portion P as shown by (B) in the figure. Stop and move toward the center of rotation, which is the starting point. After that, the holding plate 101 retracts a predetermined distance L along the rotation center line C (C in the figure), and the two wafers W1 and W2 connected via the holding section P are put together by a wafer collecting mechanism (not shown). To collect.

However, in the above cutting apparatus, the blade B which rotates while moving the wafer W is used.
The blade B must be pulled out from between the wafers W1 and W2 after returning to the same path after being cut in two from the center of thickness by. Therefore, during the return stroke, the blade edge B1 that has been bent due to the cutting resistance until then is released from the resistance and returns to the cutting edge of the wafer W1 and may be significantly damaged. Therefore, in order to perform the above-mentioned cutting process, it is necessary to add the thickness of the damage due to the blade to the cutting thickness of the wafer, and this amount causes an extra material loss.

The present invention has been made in view of the above problems, and when a silicon semiconductor wafer is cut into two parts from the center of thickness by an inner peripheral type slicer, the blade edge of the slicer and the wafer cross section contact each other. An object of the present invention is to provide a method capable of preventing damage and recovering two wafers cut and divided together.

[0006]

In order to solve the above-mentioned problems, a method of recovering a semiconductor wafer according to the present invention is a cutting method in which a semiconductor wafer is cut from a center of its thickness by a blade of an inner peripheral type slicer and divided into two pieces. In the processing, one side of the semiconductor wafer is held by a holding plate, the wafer is started to be cut by the blade of the inner peripheral type slicer, and the other side of the wafer is held while being held by the auxiliary holding plate. After the completion, the holding plate and the sub-holding plate are separated from each other to maintain a predetermined distance between the opposing wafers, and both wafers are relatively moved to the central portion of the blade of the inner peripheral type slicer, and the two facing wafers are opposed to each other. Water is sprayed on the cut surfaces of the wafers, the cut surfaces are brought into contact with each other, and the two wafers that are closely adhered and integrated via water are sandwiched by a sandwiching body instead of the holding plate and the sub-holding plate. It is intended to recover to. Further, the semiconductor wafer has a reinforcing portion on the cutting end side, and the other surface of the wafer is held by the sub-holding plate during cutting by the blade of the slicer while cutting the reinforcing portion, and then the cutting is completed. You may do it. The above-mentioned silicon semiconductor wafer is processed to have non-uniformity in the thickness direction on both sides and to have a material characteristic symmetrical with respect to the center of thickness.

[0007]

According to the above means, the wafer cut from the center of the thickness by the inner slicer is held by the holding plate and the sub-holding plate separately on both sides at the time when the wafer is cut to the reinforcing portion on the outer circumference. . The holding plate and the sub-holding plate are separated when the wafer is completely divided and cut, and the blade edge of the slicer comes into contact with the cut surfaces of the two wafers with a predetermined separation distance between the divided wafers. Prevent. And
Each holding plate moves both wafers while facing each other with a separation distance therebetween, and pulls both wafers out from the blade of the slicer, and at the same time, relatively moves both wafers to the center of the blade of the inner peripheral type slicer. The wafer may be moved by moving the holding plate with respect to the blade, or by moving the blade with respect to the holding plate. After that, water is sprayed between the cut surfaces of both wafers, and the cut surfaces are brought into contact with each other. Both wafers are closely adhered and integrated by the surface tension and adhesiveness of the sprayed water. The two wafers after cutting are warped and deformed in opposite directions due to the influence of the diffusion layer. However, when the wafers are brought into close contact with each other via water, the warps of the two wafers are offset to form a flat plate shape. The two closely attached wafers are sandwiched by a sandwiching body instead of the holding plate, and the two closely attached wafers are collected together.

[0008]

As described above, according to the present invention, both wafers completely cut and divided from the center of thickness by the inner peripheral type slicer are separately held by the holding plate and the sub-holding plate and are separated by a predetermined distance. Since it is moved toward the center of the circumferential slicer, it is possible to prevent the phenomenon that the blade comes into contact with the cut surface of the wafer and is damaged after the cutting by the slicer. According to this, from the grinding allowance to be ground in the grinding process performed after the cutting process, the thickness required for the damage by the blade, which has been conventionally required, becomes unnecessary, and the material loss can be reduced accordingly. In addition, by spraying water onto the cut surfaces of the two divided wafers to bring them into close contact, the two wafers that are warped and deformed in opposite directions are brought into close contact with each other in a flat plate shape, and the two wafers are collected together by the sandwiching body. By doing so, it is possible to recover two wafers together without difficulty, and as a result, it is possible to simplify the structure of the wafer recovery mechanism and to consolidate the cutting apparatus to save space. Become. Further, since it is possible to store twice as many wafers as a single wafer carrier, it is possible to improve the efficiency of the stripping of the reinforced portion by acid dilution water and the rough cleaning process performed for each carrier after storing the wafer in the wafer carrier. It can be greatly improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of recovering a wafer according to the present invention will be described below with reference to the drawings. 1 to 5 show a cutting and processing apparatus for a silicon semiconductor wafer W. The apparatus holds a wafer W having a diffusion layer formed on both sides by a holding plate 1,
The wafer W is cut from the center of thickness by a blade B of an inner peripheral type slicer to be divided into two pieces, and the divided wafers W1 and W2 are brought into close contact with each other by spraying water. The upper body W1 and W2 are 2 by the holding body 3.
The wafers are collected together and stored in a wafer carrier (not shown).

The blade B of the inner peripheral type slicer is a donut-shaped disk as shown in FIG. 1, and a blade edge B1 formed by electrodepositing diamond particles along the inner peripheral edge.
And is rotatably supported by the chuck body 4. The holding plate 1 located at the rotation center C of the blade B is a circular base made of porous ceramics, and holds the wafer W by suction on a flat vacuum suction surface. Further, the holding plate 1 can move horizontally on the moving base toward the blade B, and can also move within the range of the set distance L along the rotation center axis C.

A plurality of sucker type sub-holding plates 2 are installed at the tip of the movable arm 20 so as to face the holding plate 1. These sub holding plates 2 are installed on the same moving base as the holding plate 1 and move integrally with the holding plate 1. As shown in FIG. 6, the sub-holding board 2 is slidably fitted into a hollow base screw 22 in which a sliding tube 24 that is integrally fitted with the suction pad 21 is screwed to a suction tube 26. While being inserted, a cap nut 23 is screwed so as to connect the base screw 22 and the collar portion 24a of the sliding tube 24, and a coil spring 25 is mounted inside the cap nut 23. It Therefore, as will be described later, when the auxiliary holding plate 2 is brought into contact with the wafer W from above or when the divided wafer W2 is brought into close contact with W1, the suction pad 21 is elastically compressed by the compression of the coil subring 25. , So that an unreasonable load is not applied to the wafer W. The sub-holding board 2 is provided in parallel with the tip of the arm 20, but the individual sub-holding boards 2 are attached in a slightly inclined state as shown in FIG. This inclination is a consideration for applying the suction pads 21 of both sub-holding plates 2 according to the warp of the wafer W2 which is deformed by cutting.

The above-described cutting apparatus is provided with a spray nozzle 5 and a holding body 3 which are used when collecting the cut and divided wafers W1 and W2. The spray nozzle 5 is attached to the arm 20 of the auxiliary holding plate 2 and cut and divided into the wafers W1 and W.
Spray water between two. The holding body 3 collects both the wafers W1 and W2 that are brought into close contact with each other by spraying water from the holding plate 1 and stores them in a groove of a wafer carrier (not shown) for collection. The wafer W is held between the sandwiching pieces 3a.
It is configured to hold the edges of 1 and W2. It should be noted that the groove 1a cut out in the peripheral portion of the holding plate 1 is used as the holding piece 3 of the holding body 3.
It is for inserting a.

In the following, two wafers are cut by the cutting apparatus having the above-described structure, and the cut wafer W is cut.
A method of collecting 1, W2 will be described in the order of steps. As shown in FIG. 7, the wafer W to be cut has a reinforcing portion P made of carbon, silicon, epoxy resin or the like formed on a part of the outer periphery of a silicon semiconductor wafer having a thickness of about 1 mm. Diffusion layers Wa are formed on both sides of the wafer W with an undiffused layer Wb sandwiched between them. One side of the wafer W is an undiffused layer and the other side is a diffused layer by dividing the wafer W into two parts based on the thickness center Wc. Two discrete substrates are obtained.

As shown in FIG. 1, the wafer W supplied onto the holding plate 1 by the wafer supply mechanism (not shown) is held by the suction force applied through the porous ceramics. At this time, the wafer W and the holding plate 1 are positioned at the center C of the blade B of the inner peripheral type slicer, and the thickness center Wc of the wafer W exactly matches the level of the blade edge B1. The holding plate 1 moves horizontally at a high speed right before the blade edge B1 and the blade edge B1 moves to the wafer W.
Immediately before contacting the thickness center of the, the speed is reduced to a speed suitable for cutting, and the cutting is continued while maintaining this speed.

When the blade edge B1 cuts the wafer W in two and advances to the middle of the reinforcing portion P at the outer peripheral portion, the auxiliary holding plate 2 is moved and held by suction with respect to the upper wafer W2 (FIG. 2). ). Immediately thereafter, when the reinforcing portion P is cut by the blade edge B1 and the wafers W1 and W2 are completely divided, the holding plate 1 and the sub-holding plate 2 move slightly downward and upward in the figure (FIG. 3). ). As a result, both wafers W
1 and W2 are separated by a predetermined distance, and a safe distance for avoiding contact between the cut surfaces of the wafers W1 and W2 and the blade edge B1 is maintained. Next, the holding plate 1 and the sub holding plate 2
Moves toward the center C of the blade B while maintaining a predetermined separation distance between the wafers W1 and W2.

As shown in FIG. 4, water is sprayed from the spray nozzle 5 between the wafers W1 and W2 that have moved to the center C of the blade B, and an appropriate amount of water is attached to the cut surfaces of both wafers W1 and W2. . Next, the wafer W2 held by the sub-holding plate 2 is moved and brought into contact with the wafer W1 of the holding plate 1, and then the holding plate 1 and the sub-holding plate 2 are moved to the blade B center C while maintaining the state. A predetermined distance L is retracted along (FIG. 5). When the sub-holding plates 2 are moved to bring the wafer W2 into contact with the wafer W1 as described above, the suction pads 21 of both sub-holding plates 2 are elastic within a predetermined stroke range as described above. The amount of protrusion between the auxiliary holding discs 2 that is generated due to the inclination is absorbed, and the wafer W2 can be brought into planar contact with the wafer W1 without any difficulty.

As shown in FIG. 5, the abutting blades W1 and W2 are closely and integrally integrated due to the surface tension and adhesiveness of the sprayed water. After the cutting, both wafers W1 and W2 are warped and deformed in opposite directions.
As described above, by bringing the two wafers W1 and W2 into close contact with each other via water, the warpage that has occurred in the two wafers W1 and W2 is offset, and the wafers W1 and W2 are brought into close contact with each other in a flat plate shape as if they were one wafer.

The holding plate 1 and the sub-holding plate 2 retracted to the state shown in FIG. 5 to collect the wafers W1 and W2 by the holding body 3 stop the suction force applied to the wafers W1 and W2 and hold them. Then, the sandwiching body 3 is approached from the side at the same time, and the peripheral portions of the wafers W1 and W2 placed in close contact with each other on the holding plate 1 are sandwiched and picked up together.
Then, the sandwiching pair 3 moves along a predetermined moving base, and then inserts the sandwiched wafers W1 and W2 into the groove of a wafer carrier for recovery (not shown) to store them.

According to the above recovery method, it is possible to prevent contact between the blade edge B1 and the cut surfaces of the two wafers W1 and W2 after cutting, and at the same time, to attach the wafers W1 and W2 that are brought into close contact with each other by spraying water. There is an advantage that two wafers can be collected together and stored in the groove of the wafer carrier.
Further, since twice as many wafers as usual can be stored in the groove of the recovery wafer carrier, it is possible to improve the work efficiency of the peeling of the reinforcing portion P by the acid dilution water and the rough cleaning process performed after the cutting process. Although the above-described embodiment has been described as a horizontal device in which the blades of the slicer are rotatably arranged in the vertical direction, a vertical device in which the blades are horizontally arranged is also optional, and a diffusion layer is formed on both surfaces. However, the semiconductor wafer to be processed may be an SOI material wafer or the like in which dummy wafers are welded on both sides.

[Brief description of drawings]

FIG. 1 is a front view showing a cutting apparatus for carrying out the present invention.

FIG. 2 is a front view of the same apparatus showing a state in which a wafer is cut to a reinforcing portion.

FIG. 3 is a front view of the same device showing a state where the cut wafers are separated from each other.

FIG. 4 is a front view of the apparatus showing a state in which water is sprayed between the two opposing wafers.

FIG. 5 is a front view of the apparatus showing a state in which both wafers, which have been cut by retracting the holding plate, are brought into close contact with each other.

FIG. 6 is a vertical sectional view showing a sub holding plate.

FIG. 7 is an enlarged vertical sectional view of a wafer.

FIG. 8 is a schematic view showing a cutting process by a conventional cutting device.

[Explanation of symbols]

 B ... Blade B1 ... Blade edge C ... Blade center W ... Wafer W1, W2 ... Wafer (cut wafer) Wa ... Diffusion layer P ... Reinforcing part 1 ..・ Holding board 2 ・ ・ ・ Sub-holding board 3 ・ ・ ・ Clamping body

Claims (3)

[Claims] 1. A cutting process in which a semiconductor wafer is cut from the center of thickness by a blade of an inner peripheral type slicer and divided into two pieces, and one side of the semiconductor wafer is held by a holding plate, and this wafer is cut by an inner peripheral type slicer. After the cutting is started by the blade and the cutting is completed while the other surface of the wafer is held by the auxiliary holding plate in the middle of the cutting, the holding plate and the auxiliary holding plate are separated from each other between the facing wafers. While maintaining a predetermined distance, move both wafers relative to the center of the inner peripheral slicer blade, spray the water on the cut surfaces of the two facing wafers, and then bring the cut surfaces into contact with each other. A method for collecting semiconductor wafers, in which both wafers that have been brought into close contact with each other are held by a holding body instead of the holding plate and the auxiliary holding plate and are collected together. 2. The semiconductor wafer has a reinforcing portion on the cutting end side, and the other surface of the wafer is held by a sub-holding plate during cutting by the blade of the slicer while cutting the reinforcing portion, and then cut. The method for collecting a semiconductor wafer according to claim 1, wherein the process is completed. 3. The method for recovering a semiconductor wafer according to claim 1, wherein the silicon semiconductor wafer is processed on both surfaces thereof so as to have non-uniformity in a thickness direction and have a material property symmetrical with respect to a thickness center. .