JP2611829B2 - Notch grinding method and apparatus for semiconductor wafer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for notch grinding a semiconductor wafer, in particular, by moving a rotating disk-shaped grinding wheel in the axial direction (X direction) of its rotating shaft, The semiconductor wafer is moved in a direction (Y direction) for approaching or detaching from the grindstone, and the grindstone is moved in the Z direction perpendicular to the X direction and the Y direction, so that the circumferential direction and thickness of the notch of the semiconductor wafer are changed. The present invention relates to a method and an apparatus for notch grinding a semiconductor wafer, which can simultaneously and efficiently perform chamfering in a direction and can arbitrarily change the size of chamfering in a thickness direction.

2. Description of the Related Art A wafer such as a semiconductor wafer is a general term for a thin disk-shaped semiconductor, and is generally cut into a disk shape from a single crystal base material purified into a column shape as shown in FIG. Various semiconductor elements are mirror-polished and formed on their surfaces by etching or the like. In a semiconductor wafer, for example, its dimensions are 10 to 400 mm in diameter and 200 μ in thickness.
It has a thin disk shape of m to 10 mm, and an orientation flat (OF) or a substantially V-shaped notch in which a part of the outer peripheral portion is ground in a straight line in order to easily adjust the circumferential orientation. Form.

On the other hand, when performing fine processing on the surface of the semiconductor wafer, a problem is dust generated from the surface or the outer peripheral surface of the semiconductor wafer, and when the outer peripheral surface of the semiconductor wafer is sharp, generation of dust increases. . Therefore, eliminating the connecting surface between the orientation flat or the notch and the outer peripheral surface, particularly the sharp edge in the plate thickness direction of the orientation flat or the notch, is an effective means for preventing generation of dust.

Further, processing the orientation flat or notch to an accurate dimension can shorten the time required for alignment in the next step of fine processing, so that high-precision grinding is required.

Conventionally, since it is difficult to remove a sharp edge of a substantially V-shaped notch, an orientation flat that is relatively easy to use has been often used.However, the orientation flat has to take a lot of missing parts, There was a disadvantage that expensive semiconductor wafers could not be used effectively.

Conventionally, a chemical polishing method or a general cutter method has been adopted as a notch grinding method. In the chemical polishing method, as shown in FIG. 6, a semiconductor wafer 2 cut into a disk shape from a columnar base material 1 is immersed in an etching solution to chemically remove an edge portion 2a. As shown in FIG. 7, not only the edge portion 2a but also the entire portion 2b immersed in the etching solution is eroded and thinned, so that the flatness of the wafer is deteriorated, and there is a disadvantage that the fine processing in the next step is adversely affected. .
Further, the amount of processing by this method is extremely small, and there is a disadvantage that only insufficient processing can be performed to prevent generation of dust in submicron units, which is a problem when processing VLSI or the like.

In the form cutter method, in order to create a cutter having the same shape as the shape of the notch 2c and grind the notch 2c, when the shape of the notch 2c is changed, a cutter must be created each time. The shape of the cutter changed with the grinding, and the cutter used to some extent had to be replaced with a new cutter, which was economically expensive, and had the drawback that the setup work required many man-hours. . In addition, since the chamfering process at the connection point between the V-shaped notch 2c and the outer peripheral portion 2d of the wafer 2 and the chamfering process of the notch 2c in the thickness direction cannot be performed with one grindstone, the normal thickness Although only the chamfering in the direction is performed and the fine processing of the next process is performed, dust is generated from the unprocessed circumferential edge portion 2a, so serious effects such as disconnection of the conductive wire portion may be affected. There is a disadvantage that it gives to the semiconductor element.

Object The present invention has been made in order to eliminate the above-mentioned disadvantages of the prior art, and an object of the present invention is to move a rotating disc-shaped grindstone in the direction of its rotation axis while orthogonally crossing the grindstone. By moving the semiconductor wafer held at the position in a direction approaching or leaving the grindstone, the grindstone is relatively moved along the outer shape of the substantially V-shaped notch, and by grinding the notch, For parts where conventional processing has been difficult, while maintaining the flatness of the surface of the semiconductor wafer where fine processing is performed in the next process in a good state,
The purpose is to enable chamfering sufficient to prevent the generation of dust. Another purpose is that even if the shape of the notch is changed, it is not necessary to replace the grindstone,
An object of the present invention is to enable efficient grinding work without setup work. Still another object is to improve the working efficiency by simultaneously chamfering the notch in the circumferential direction and the thickness direction with one large-diameter grindstone, and to prevent the generation of dust from the edge portion. It is another object of the present invention to prevent a property of a semiconductor element formed on a semiconductor wafer from being adversely affected.

In short, the method of the present invention (Claim 1) is to dispose a grindstone on a rotating disk and a semiconductor wafer to be ground by the grindstone at positions where their respective surfaces are orthogonal to each other, and attach the grindstone to the axis of its rotating shaft. Direction (X direction) to move the semiconductor wafer toward or away from the grindstone (Y direction).
Direction) and the direction in which the grindstone is moved in the axial direction (X direction) and the direction in which the whetstone approaches or separates (Y direction).
The semiconductor wafer is moved in a direction (Z direction) orthogonal to the above, and the notch of the semiconductor wafer is chamfered in a circumferential direction and a thickness direction.

Further, the apparatus of the present invention (claim 2) is a disk-shaped grindstone rotatably disposed on a movable table, and a moving means for moving the movable table in the axial direction (X direction) of the rotation axis of the grindstone. 1 and the moving table is moved in a direction (Z direction) orthogonal to the axial direction (X direction) and a direction (Y direction) in which the grindstone approaches or separates from the semiconductor wafer to be ground by the grindstone (Y direction). A second driving device, a work holder that rotatably holds the semiconductor wafer in a plane perpendicular to the surface of the grinding wheel, a third driving device that rotationally drives the semiconductor wafer on the work holder, A fourth driving device for moving the work holder in a direction (Y direction) for approaching or detaching from the grindstone, and the first, second, third, and fourth driving devices drive the grinding wheel and The semiconductor wafer Pairs to three axis directions (X, Y, Z directions)
To perform chamfering in the circumferential direction and the thickness direction of the notch of the semiconductor wafer.

Hereinafter, the present invention will be described based on embodiments shown in the drawings. The notch grinding device 3 for a semiconductor wafer according to the present invention includes a disc-shaped grindstone 4, a grindstone rotation drive mechanism 5, a base 6 on which the rotation drive mechanism is mounted, a first drive device 8, A second driving device 9, a work holder 10, a third driving device 11,
And a fourth driving device 12.

The grindstone 4 is formed by solidifying diamond abrasive grains 4b by metal or electrodeposition around a grindstone main body 4a formed by solidifying hardened sand and is detachably fixed to a rotating shaft 13 by a nut 14. .

The rotation drive mechanism 5 of the grindstone 4 rotates the grindstone 4 in one direction by the electric motor 15, and rotates the grindstone 4 fixed to the rotating shaft 13 of the electric motor 15, for example, in the direction of arrow A. ing.

The base 6 is composed of a guide base 16 and a movable base 19, and the movable base 19 guided on the dovetail groove 18 formed on the guide base 16 can slide on a straight line. I have.

The first driving device 8 is configured to move a moving table 19 guided by a dovetail groove 18 in the axial direction (X direction) of the rotating shaft 13 of the grindstone 4.
The feed screw 21 is formed on the movable base 19 and is rotatably screwed to the screw 22.

The second driving device 9 is for moving the grindstone 4 in the Z direction, and has a rotary shaft 25a directly connected to a feed screw 24 rotatably screwed to a feed nut 23 fixed to the guide table 16. It is configured as a DC servo motor 25.

The work holder 10, as shown in FIGS. 1 to 3,
A plurality of, for example, four air suction holes 10a are formed in the upper surface 10b, and the air suction holes 10a are connected to a vacuum pump (not shown), and air is actuated by the operation of the vacuum pump. Semiconductor wafer 2 sucked from suction hole 10a
Is configured to be adsorbed. Further, a pair of grooves 10c orthogonal to the radial direction and concentric grooves 10d in the circumferential direction are formed on the upper surface 10b. Furthermore, the work holder 10 is
It is rotatably supported by a support cylinder 28 fixed to 6, and is configured to slowly rotate the wafer 2 attracted to the work holder 10 by the third driving device 11.

The fourth drive device 12 moves the work holder 10 closer to or away from the grindstone 4 and includes first and second drive units 12.
A drive screw 30 fixed to the rotating shaft 29a of the DC servomotor 29 and a feed nut 31 disposed on the movable base 26 screwed to the feed screw 30 like the drive devices 8, 9 By performing the forward and reverse rotation, the movable table 26 can be reciprocated in the Y direction.

The first, second, third and fourth driving devices 8, 9, 11 and 12 are electrically connected to a control device 32 having an operation panel 33.

Then, the method according to the present invention provides a rotating disc-shaped grinding wheel 4.
And the semiconductor wafer 2 to be ground by the grindstone are arranged at positions where their respective surfaces are orthogonal to each other, and the grindstone 4 is moved in the axial direction (X direction) of the rotating shaft 13 so that the semiconductor wafer 2 approaches the grindstone 4. The whetstone 4 is moved in the direction (Y direction) perpendicular to the direction of the axis (X direction) and the direction of approach or separation (Y direction). This is a method of chamfering the notch 2c in the circumferential direction and the plate thickness direction.

Operation The present invention is configured as described above, and the operation will be described below. Referring to FIG. 1, FIG. 2 and FIG. 6, a semiconductor wafer 2 obtained by processing a columnar base material 1 and processing a substantially V-shaped notch 1a in the axial direction thereof into a disk shape and separating the same into a disk shape. Place on the upper surface 10b of the work holder 10,
A vacuum pump (not shown) is operated. Since the vacuum pump sucks air from the suction hole 10a, the semiconductor wafer 2
The work holder 10 is fixed by suction.

In response to a command from the control device 32, the third drive device 11 is operated to slowly rotate the work holder 10, ie, the semiconductor wafer 2, in the direction of the arrow θ, and a detection device (not shown) that the notch 2c correctly faces the grindstone 4 is provided. Detected by the drive device 11
Stop the operation of.

Further, by rotating the DC servo motor 25 to move the base 6 up and down in the directions of arrows Z and Z 'by the action of the feed screw 24 and the feed nut 23, as shown in FIG. The central portion is aligned with the axis 13a of the rotating shaft 13 of the grinding wheel 4. At this time, the positions of the grindstone 4 and the semiconductor wafer 2 are separated from each other as shown in FIG. 3, and the semiconductor wafer 2 is not yet processed. Where the DC servo motor
When the feed screw 30 is rotated in the direction of arrow B by operating 29, the moving table 26 moves in the direction of arrow Y, approaches the grindstone 4, and the rotating grindstone 4 and the semiconductor wafer 2 come into contact.

After the grindstone 4 and the semiconductor wafer 2 come into contact with each other, the movable table 26 is further moved by a predetermined distance in the direction of arrow Y by operating the fourth driving device 12 to process the semiconductor wafer 2. Then, the DC servomotor 20 is slowly rotated to move the movable table 19 on which the rotary drive device 5 is disposed in the direction of the arrow X or X 'along the dovetail groove 18 to move the grindstone 4 to the position indicated by a virtual line in FIG. 4 and the DC servo motor 25 is also operated to move the base 6 in the direction of arrow Z or Z 'by the amount of movement LZ shown in FIG. Then, the movement amounts in the X direction and the Z direction are transmitted to the control device 32 every moment, and the control device 32 stores in advance the distance to be moved by the movable table 26 for processing along the shape of the V-shaped notch 2c. The DC servo motor 29 is rotated according to the calculation result.

As described above, by controlling the three axes in the X, Y and Z directions, the grindstone 4 and the semiconductor wafer 2 are relatively moved to the third position.
The circumferential direction of the semiconductor wafer 2 shown in FIG relative along the shape of the notch 2c, also in the direction of arrow C in the thickness direction as shown in Figure 4, i.e. from LY ₁ in the Y direction until LY ₂ To the notch 2c and the outer peripheral part 2d in the circumferential direction.
At the connection point 2e, and at the valley 2f of the notch 2c, a small arc shape, for example, a chamfer r of 0.2 to 2.5R, and in the thickness direction, as shown in FIG. 5, a small arc at the edge 2a. The chamfering of the shape can be performed simultaneously. Semiconductor wafer 2
Radius R ₁ of example, a 10～400Mm, radius R ₂ to the valley portion 2f of the notch is 8~394mm example.

The angle α of the notch 2c differs depending on the product, and is 50 °
An angle of up to 150 ° is used, but even if the value of the angle α changes, chamfering can be performed without changing the grindstone 4 only by inputting the angle from the operation panel 33. Also, the size of the chamfer can be arbitrarily selected and processed without changing the grindstone 4.

In the above embodiment, the control has been described as performing control in the X, Y and Z directions simultaneously, but the control is performed in the X, Y
The control of the DC servomotor 25 is not limited to the one that simultaneously performs the control of the DC servomotor 25, the rotation of the DC servomotor 25 is stopped, the movement in the Z direction is not performed, and only the DC servomotors 20 and 29 are operated. By controlling the two axial directions, the outer peripheral direction of the notch 2c is relatively ground along the shape of the notch 2c, and then only the DC servo motor 25 is operated to slightly move in the direction of the arrow Z or Z '. The notch 2c may be sequentially chamfered in the thickness direction by two-way control in the X and Y directions by the DC servo motors 20 and 29 again. In this case, the shape of the chamfer in the thickness direction is so-called C chamfering.

Further, according to the method of the present invention, all edges in the circumferential direction and the thickness direction of the notch 2c are ground, so that a work strain layer generated by processing the notch 1a of the base material 1 can be removed.

Effect The present invention is to move a semiconductor wafer held at a position orthogonal to the grindstone in a direction approaching or leaving the grindstone while moving the disc-shaped grindstone rotating as described above in the rotation axis direction. With this, the notch is ground by moving the grindstone relatively along the substantially V-shaped notch outer shape, so that conventional processing is difficult while maintaining the flatness of the semiconductor wafer in a good state. Can be chamfered to a size large enough to prevent the generation of dust, and even if the shape of the notch is changed, it is not necessary to replace the grindstone, and there is no setup work There is an effect that a grinding operation can be performed. Further, there is an effect that the size of the chamfer and the shape of the notch can be arbitrarily changed without changing the grindstone. Furthermore, since the chamfering process in the circumferential direction of the notch and the plate thickness direction can be simultaneously performed with one large-diameter grindstone, work efficiency can be improved, and generation of dust from the edge portion can be reduced. This has the effect that the characteristics of the semiconductor elements formed on the semiconductor wafer can be prevented from being adversely affected.

[Brief description of the drawings]

1 to 6 relate to an embodiment of the present invention, FIG. 1 is a perspective view of a semiconductor wafer and a notch grinding device for a semiconductor wafer, FIG. 2 is a plan view of a main part of the grinding device, and FIG. FIG. 4 is an enlarged plan view of a principal part showing a circumferential chamfering state of a wafer; FIG. 4 is an enlarged partial longitudinal sectional side view of a principal part showing a chamfering state of a semiconductor wafer in a plate thickness direction; FIG. 6 is a partially enlarged vertical sectional view of a semiconductor wafer subjected to chamfering in one direction, FIG. 6 is a perspective view showing a state of a semiconductor wafer cut from a base material, and FIG. 7 is a chemical polishing method according to a conventional example. It is a principal part expanded longitudinal cross-sectional view which shows the state of the sagging of the chamfering process by. 2 is a semiconductor wafer, 2c is a notch, 3 is a chamfering device for a semiconductor wafer, 4 is a grindstone, 8 is a first driving device, 9 is a second driving device, 10 is a work holder, and 11 is a third driving device. The device, 12 is a fourth driving device, 13 is a rotating shaft, and 19 is a moving table.

Claims (2)

(57) [Claims] 1. A grindstone on a rotating disk and a semiconductor wafer to be ground by the grindstone are disposed at positions where their surfaces are orthogonal to each other, and the grindstone is moved in the axial direction (X direction) of its rotating shaft. To move the semiconductor wafer toward or away from the grindstone (Y direction), and to move the grindstone in the direction perpendicular to the axial direction (X direction) and the approaching or detaching direction (Y direction). (Z direction)
The notch of the semiconductor wafer is circumferentially and chamfered in the thickness direction. 2. A whetstone on a disk rotatably disposed on a moving table, a first driving device for moving the moving table in an axial direction (X direction) of a rotation axis of the whetstone, Moving the movable table in the axial direction (X direction) and a direction (Z direction) orthogonal to the direction in which the grindstone approaches or separates from the semiconductor wafer to be ground by the grindstone (Y direction);
A driving device, a work holder for rotatably holding the semiconductor wafer in a plane perpendicular to the surface of the whetstone, and a third for rotationally driving the semiconductor wafer on the work holder.
And a fourth moving device for moving the work holder in a direction (Y direction) for approaching or detaching from the grindstone.
And the first, second, third and fourth driving devices move the grindstone and the semiconductor wafer relatively in three axial directions (X, Y, Z directions). A notch grinding apparatus for a semiconductor wafer, which is configured to perform chamfering in a circumferential direction and a thickness direction of a notch of the semiconductor wafer.