JPH02180554A - Method and device for notch grinding of semiconductor wafer - Google Patents

Abstract

PURPOSE:To perform beveling even for almost V shaped notch with holding the flatness of a semiconductor wafer in good state and to prevent the generation of dust, by moving the semiconductor wafer held at the orthogonal position with a grindstone in the direction approaching to or separating from the grindstone with moving the grindstone in the rotating shaft direction. CONSTITUTION:A rotating discoid grindstone 4 and a semiconductor ware 2 ground by this grindstone 4 are arranged at the position where the respective face is orthogonal each other, the grindstone 4 is moved in the axial line direction of the rotating shaft 13 thereof and the semiconductor wafer 2 is moved in the direction approaching to the grindstone 4 or separating therefrom. Moreover, the beveling in the circumferential direction and plate thickness direction of the notch 2c of the semiconductor wafer 2 is performed by moving the grindstone 4 in the direction orthogonal with the axial line direction and approaching or separating direction. Thus the generation of dust can be prevented by beveling the notch 2c.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method and apparatus for notch grinding a semiconductor wafer, and in particular moves a rotating disk-shaped grindstone in the axial direction (X direction) of its rotation axis. The semiconductor wafer is moved in the direction (Y direction) in which the semiconductor wafer approaches or leaves the grindstone, and the grindstone is moved in the direction of
To provide a semiconductor wafer which can simultaneously efficiently chamfer a notch of a semiconductor wafer in the circumferential direction and the thickness direction by moving the notch in the direction of the semiconductor wafer, and which can arbitrarily change the size of the chamfer in the thickness direction. The present invention relates to a notch grinding method and device.

Background Art A wafer such as a semiconductor wafer is a general term for a thin disk-shaped semiconductor, and is usually cut into a disk shape from a single crystal base material refined into a cylindrical shape, as shown in FIG. It is mirror-polished, and various semiconductor elements are formed on the surface by etching or the like. For example, a semiconductor wafer has dimensions of 10 to 400 mm in diameter and 2 mm in thickness.
It is a thin disc-shaped object with 00 tt to 10 fins, and in order to easily align the circumferential direction, it is called an oriental cylinder flat (OF) with a part of the outer periphery ground into a straight line.
) or a roughly V-shaped notch.

On the other hand, when performing fine processing on the surface of a semiconductor wafer, the problem is dust generated from the surface and outer circumferential surface of the semiconductor wafer, and if the outer circumferential surface of the semiconductor wafer is sharp, the generation of dust becomes a problem. It becomes. Therefore, eliminating sharp edges in the thickness direction of the orientation flat or notch, especially at the connection surface between the orientation flat or notch and the outer circumferential surface, is an effective means for preventing the generation of dust.

Furthermore, machining the orientation flat or notch to accurate dimensions can shorten the alignment time during the next step of micromachining, so high-precision grinding is required.

Conventionally, it has been difficult to process the sharp edges of a roughly V-shaped notch, so orientation flats, which are relatively easy to process, have often been used;
There was a drawback that expensive semiconductor wafers could not be used effectively.

Conventionally, a chemical polishing method or a total cutter method has been adopted as a method for grinding notches. In the chemical polishing method, as shown in FIG. 6, a semiconductor wafer 2 cut into a disk shape from a cylindrical base material 1 is immersed in an etching solution to chemically remove the 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 becomes thinner, resulting in poor flatness of the wafer, which has the disadvantage of having a negative impact on microfabrication in the next step. . In addition, the amount of processing by this method is very small, and ILs
There is a drawback that processing is insufficient to prevent the generation of submicron dust, which is a problem when processing I and the like.

In addition, in the total cutter method, a cutter with the same shape as the notch 2C is created to grind the notch 2C, so if the shape of the notch 2C is changed, a cutter must be created each time, and the cutter must be created each time the shape of the notch 2C is changed. The shape of the cutter changes during grinding, and a cutter that has been used for some time must be replaced with a new one, which is not only economically expensive, but also
This method has the drawback of requiring a large number of man-hours for setup work. Also V
Since it is not possible to chamfer one major reading point between the letter-shaped notch 2C and the outer periphery 2d of the wafer 2, and to chamfer the notch 2C in the thickness direction with one grindstone, it is usually done in the thickness direction. Although only the chamfering process is performed and the next step is micromachining, dust is generated from the unprocessed circumferential edge part 2a, which may cause serious effects such as disconnection of the conductor part, etc. It had the disadvantage of giving away.

Purpose The present invention has been made in order to eliminate the drawbacks of the prior art described above, and its purpose is to move a rotating disc-shaped grindstone in the direction of its rotational axis while By moving the semiconductor wafer held at a position toward or away from the grindstone, the grindstone is moved so as to follow the outer shape of the relatively V-shaped notch, and the notch is ground. , it is now possible to perform sufficient chamfering to prevent the generation of dust while maintaining the flatness of the surface of the semiconductor wafer, which will be microfabricated in the next process, in a good condition, even in areas that were previously difficult to process. The goal is to make it possible. Another object is to eliminate the need to replace the grindstone even if the shape of the notch is changed, thereby enabling efficient grinding work without setup work. Another purpose is to improve work efficiency by making it possible to simultaneously chamfer the notch in the circumferential direction and the plate thickness direction using one large-diameter grindstone, as well as to prevent the generation of dust from the edge. However, the purpose is to prevent adverse effects on the characteristics of semiconductor elements formed on a semiconductor wafer.

Configuration In short, the method of the present invention (claim 1) comprises disposing a grindstone on a rotating disc and a semiconductor wafer to be ground with the grindstone at positions where their respective surfaces are perpendicular to each other, and the grindstone is placed on the axis of rotation of the grindstone. The semiconductor wafer is moved in the axial direction (X direction) and moved in the direction (Y direction) in which the semiconductor wafer approaches or leaves the grindstone, and the grindstone is moved in the axial direction (X direction).
chamfering of the notch of the semiconductor wafer in the circumferential direction and thickness direction by moving the notch in the direction (Z direction) perpendicular to the approaching or separating direction (Y direction) and the approaching or separating direction (Y direction). It is something.

The device of the present invention (claim 2) also includes a disc-shaped grindstone rotatably disposed on a movable table, and a grindstone that moves the movable table in the axial direction (X direction) of the rotation axis of the grindstone. 1 and a direction (Z direction) perpendicular to the axial direction (X direction) and the direction (Y direction) in which the grindstone approaches or leaves the semiconductor wafer to be ground by the grindstone (Y direction);
a second drive device that moves the semiconductor wafer to a surface of the grindstone; a work holder that rotatably holds the semiconductor wafer in a plane perpendicular to the surface of the grindstone; and a third drive device that rotationally drives the semiconductor wafer on the work holder. A driving device and a direction (Y direction) in which the work holder approaches or departs from the grindstone.
a fourth drive device for moving the first,
The grindstone and the semiconductor wafer are relatively moved in three axial directions (X, Y, and Z directions) by second, third, and fourth drive devices.
The present invention is characterized in that the notch of the semiconductor wafer is chamfered in the circumferential direction and the thickness direction by moving the notch.

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

The whetstone 4 is formed by hardening diamond abrasive grains 4b with metal or electrodeposition around a whetstone main body 4a formed by solidifying diamond sand, and is removably fixed to a rotating shaft 13 with a nut 14. .

The rotational drive mechanism 5 for the grindstone 4 rotates the grindstone 4 in one direction with an 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 stand 16 and a moving stand 19, and the moving stand 19 is guided by a dovetail groove 18 formed on the guide stand 16 so that it can slide in a straight line. There is.

The first drive device 8 is configured to move a movable table 19 guided by a dovetail groove 18 in the axial direction (X direction) of the rotating shaft 13 of the grindstone 4, and is configured to drive, for example, the rotation of a DC servo motor 20. A feed screw 21 formed on the shaft 20a is rotatably screwed onto an internal screw 22 formed on the moving table 19.

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

The work holder 10, as shown in FIGS. 1 to 3,
A plurality of, for example four, air suction holes 10a are provided on the upper surface 10.
b, and the air suction hole 10a is connected to a vacuum pump (not shown), and when the vacuum pump operates, air is sucked from the air suction hole 10a to adsorb the semiconductor wafer 2. It is configured as follows. Further, a pair of grooves 10c perpendicular to the radial direction and a concentric groove 10d in the circumferential direction are formed on the upper surface 10b. Further, the work holder 10 is rotatably supported by a support cylinder 28 fixed to a moving table 26, and the wafer 2 attracted to the work holder 10 is slowly rotated by the third driving bag M11. It is composed of

The fourth drive device 12 moves the work holder lO closer to or away from the grinding wheel 4, and is fixed to the rotating shaft 29a of the DC servo motor 29 like the first and second drive devices 8 and 9. It is composed of a feed screw 30 and a feed nut 3F screwed onto the feed screw 30 and disposed on a moving table 26, and by rotating the feed screw 30 in forward and reverse directions, the moving table 26 can be reciprocated in the Y direction. It looks like this.

and first, second, third and fourth drive devices 89.11
and 12 are electrically connected to a control device 32 having an operation panel 33.

In the method according to the present invention, a rotating disc-shaped grindstone 4 and a semiconductor wafer 2 to be ground by the grindstone are arranged at positions where their surfaces are orthogonal to each other, and the grindstone 4 is rotated in the axial direction of its rotating shaft 13. (X direction), moves the semiconductor wafer 2 in the direction (Y direction) in which it approaches or leaves the grindstone 4, and moves the grindstone 4 in the axial direction (X direction) and the direction in which it approaches or leaves the grindstone 4 (Y direction). ) and the direction perpendicular to (
In this method, the notch 2C of the semiconductor wafer 2 is chamfered in the circumferential direction and the thickness direction by moving the notch 2C in the X direction.

The present invention is constructed as described above, and its operation will be explained below. Referring to FIGS. 1, 2, and 6, a semiconductor wafer 2 is obtained by cutting and separating a cylindrical base material l into a disk shape with a substantially V-shaped notch la formed in its axial direction. It is placed on the upper surface 10b of the work holder 10, and a vacuum pump (not shown) is operated. Since the vacuum pump sucks air through the suction hole 10a, the semiconductor wafer 2 is fixed to the work holder 10 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, that is, the semiconductor wafer 2 in the direction of the arrow θ, and a detection device (not shown) detects that the notch 2C is correctly opposed to the grindstone 4. is detected and the operation of the drive device 1 is stopped.

Further, by rotating the DC servo motor 25, the base 6 is moved in the directions of arrows z and z by the action of the feed screw 24 and the feed nut 23.
4, as shown in FIG.
Match 3a.

The position of the grindstone 4 and the semiconductor wafer 2 at this time is the third position.
As shown in the figure (separated positional relationship, semiconductor wafer 2
is not processed yet. When the DC servo motor 29 is operated to rotate the feed screw 30 in the direction of arrow B,
The moving table 26 moves in the direction of arrow Y and approaches the grindstone 4,
The rotating grindstone 4 and the semiconductor wafer 2 come into contact.

After the grindstone 4 and the semiconductor wafer 2 come into contact, the moving table 26 is further moved in the direction of arrow Y by a predetermined distance, and the semiconductor wafer 2 is processed. Then, the DC servo motor 20 is slowly rotated, the rotary drive device 5 is arranged, and the movable table 19 is moved into the dovetail groove 18.
The grindstone 4 is moved in the direction of the arrow X or X' along the
The base 6 is moved by the distance fiLX to the position indicated by the virtual line in the figure, and the DC servo motor 25 is also operated to move the base 6 by the amount of movement LZ shown in the red mark Z or Z' force direction in FIG. 3g>( direction and the amount of movement in the The calculation is performed according to the calculated formula, and the DC servo motor 29 is rotated according to the calculation result.

As described above, by controlling the three axes of the X, Y, and X directions, the grindstone 4 and the semiconductor wafer 2 are relatively
There are notches 2C in the circumferential direction of the semiconductor wafer 2 shown in the figure.
along the shape of the arrow C, and in the thickness direction shown in Fig. 4.
In other words, in the Y direction, chamfering is performed by moving relatively from LY to LY, +, so in the circumferential direction, the notch 2
A small circular arc shape, for example, a chamfer of 0.2 to 2.5R, is formed at the connection point 2e between C and the outer circumference 2d, and at the valley 2'' of the notch 2c, and in the thickness direction, as shown in Fig. 5. As shown, the edge portion 2a can be chamfered into a small arc at the same time.The radius R of the semiconductor wafer 2 is, for example, lO
The radius R2 to the valley 2f of the notch is, for example, 8 to 394 mm.

Also, the angle α of the notch 2c varies depending on the product, and is 50
'' to 1506 angles are used, but even if the value of the angle α changes, simply inputting the angle from the operation panel 33 allows the grinding wheel 4 to
Chamfering can be performed without replacing. Furthermore, the size of the chamfer can be arbitrarily selected and processed without changing the grindstone 4.

In addition, in the above embodiment, the control was explained as controlling in the X, Y, and Z directions simultaneously, but the control was performed in the x,
The control is not limited to simultaneous control in the y and Z directions;
The notch 2c is moved relatively along the shape of the notch 2c by operating only the DC servo motors 20 and 29 without moving in the direction, that is, by controlling the two axes in the X direction and the Y direction.
Grinding is performed in the outer circumferential direction, and then the DC servo motor 25
to move it slightly in the direction of the arrow Z or Z', and then move it again in the X direction and Y direction using the DC servo motors 2o and 29.
The chamfering process of the notch 2c in the plate thickness direction may be sequentially performed by controlling the notches 2c in two directions. In this case, the shape of the chamfer in the plate thickness direction is a so-called C-chamfering process.

Furthermore, according to the method of the present invention, all the edges of the notch 2c in the circumferential direction and the plate thickness direction are ground, so that it is also possible to remove the processing strain layer generated in processing the notch 1a of the base material 1.

Effect The present invention is to move a rotating disc-shaped grindstone in the direction of its rotational axis as described above, while moving a semiconductor wafer held at a position orthogonal to the grindstone in a direction toward or away from the grindstone. As a result, the notch is ground by moving the whetstone along the relatively V-shaped outer shape of the notch, thereby maintaining the flatness of the semiconductor wafer in a good condition, which is difficult to do with conventional processing. It is possible to perform chamfering large enough to prevent the generation of dust on the notched parts, and even if the shape of the notch is changed, there is no need to replace the grindstone, and there is no setup work and one efficiency. This has the effect of allowing good grinding work to be performed. Additionally, the size of the chamfer and the shape of the notch can be changed arbitrarily without changing the grindstone. Furthermore, chamfering in the circumferential direction and thickness direction of the notch can be performed simultaneously using one large-diameter grindstone, which improves work efficiency and reduces the generation of dust from the edges. It has the effect of preventing adverse effects on the characteristics of semiconductor elements formed on semiconductor wafers.

[Brief explanation of the drawing]

1 to 6 relate to embodiments of the present invention, FIG. 1 is a perspective view of a semiconductor wafer and a notch grinding device for semiconductor wafers, FIG. 2 is a plan view of essential parts of the grinding device, and FIG. 3 is a semiconductor wafer notch grinding device. FIG. 4 is an enlarged plan view of the main part showing the state of chamfering in the circumferential direction of the wafer, FIG. 4 is an enlarged longitudinal sectional side view of the main part showing the state of chamfering in the thickness direction of the semiconductor wafer, and FIG. FIG. 6 is a partially enlarged vertical cross-sectional view of a semiconductor wafer that has been subjected to directional chamfering, FIG. 6 is a perspective view showing the state of the semiconductor wafer cut and created from the base material, and FIG. 7 is a conventional chemical polishing method. FIG. 3 is an enlarged vertical cross-sectional view of a main part showing a state of blurring in chamfering. 2 is a semiconductor wafer, 2C is a notch, 3 is a semiconductor wafer chamfering device, 4 is a grindstone, 8 is a first drive device, 9
10 is a second drive device, 10 is a work holder, 11 is a third drive device, 12 is a fourth drive device, 13 is a rotating shaft, 19
is a moving platform. Patent applicant Mtic Co., Ltd.

Claims (1)

[Scope of Claims] 1. A grindstone on a rotating disc and a semiconductor wafer to be ground by the grindstone are arranged at positions where their surfaces are orthogonal to each other, and the grindstone is placed in the axial direction of its rotation axis (X direction). move it to
The semiconductor wafer is moved in a direction (Y direction) in which the semiconductor wafer approaches or leaves the grindstone, and the grindstone is moved in a direction (Z direction) orthogonal to the axial direction (X direction) and the direction (Y direction) in which it approaches or leaves the grindstone. 1. A method for grinding a notch in a semiconductor wafer, the method comprising: chamfering the notch of the semiconductor wafer in the circumferential direction and the thickness direction by moving the notch in the semiconductor wafer direction. 2. A disc-shaped grindstone rotatably arranged on a movable table,
a first drive device that moves the movable table in the axial direction (X direction) of the rotating shaft of the grindstone; and a first drive device that moves the movable table in the axial direction (X direction) and the grindstone to approach the semiconductor wafer to be ground by the grindstone. Direction to move or move away from (Y direction)
a second drive device that moves the semiconductor wafer in a direction perpendicular to the grinding wheel (Z direction); a work holder that rotatably holds the semiconductor wafer in a plane perpendicular to the surface of the grindstone; A third drive device that rotationally drives the work holder, and a fourth drive device that moves the work holder in a direction (Y direction) in which the work holder approaches or leaves the grindstone, and these first, second, and third drive devices and a fourth driving device to relatively move the grindstone and the semiconductor wafer by 3.
A notch grinding device for a semiconductor wafer, characterized in that it is configured to chamfer the notch of the semiconductor wafer in the circumferential direction and the board thickness direction by moving in the axial direction (X, Y, two directions).