JPH11156684A - Mirror finishing device for semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve accurate mirror finish by oscillating a wafer in the axial line direction of a polishing drum. SOLUTION: A device is constituted of a polishing drum driving means 2 consisting of a polishing drum 6 and a drum driving source 7 for rotating and driving this polishing drum 6, at least one wafer driving means 3 placed near the grinding drum driving means 2, a chuck driving means 15 which is provided for the wafer driving means 3 and can oscillate in the axial line direction of the polishing drum 6 with an oscillation means 8, a chuck 17 which is provided for the chuck driving means 15 and holds a wafer 20 for a chamfered part 20a on the outer peripheral surface of the polishing drum 6, and a chuck driving source 16 for rotating and driving the chuck 17, and enables the highly accurate mirror finish of the chamfer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mirror processing apparatus for mirror-processing a semiconductor wafer having a peripheral portion chamfered.

[0002]

2. Description of the Related Art Conventionally, semiconductor wafers used for integrated circuits and the like have been manufactured by thinly slicing an ingot made of silicon single crystal, but recently, in order to prevent occurrence of pitching at an edge portion, The edge is mirror-polished to prevent chamfering of the edge and to prevent particles and increase strength.

As a method for mirror-finishing a chamfered portion of a semiconductor wafer, for example, a method described in Japanese Patent Publication No. 7-61601 is known.

In the mirror polishing method disclosed in the above publication, a step of holding a disc-shaped wafer having a chamfered outer peripheral portion on a chuck table, a step of rotating the wafer around an axis of the wafer, and a linear movement A step of bringing the polishing drum, which is supported so as to be able to freely contact and separate, and the wafer into contact with the urging force of a vertically suspended weight, and polishing the chamfered portion of the wafer with the rotating polishing drum; It has a step of changing the contact position with the wafer by moving the polishing drum in the axial direction, and has the effect of enabling the entire surface of the chamfer to be reliably and uniformly mirror-polished. doing.

[0005]

However, in the mirror polishing method disclosed in the above publication, when a plurality of wafers are brought into contact with the same polishing drum to perform mirror polishing, the oscillating condition cannot be set for each wafer. Therefore, there is a problem that each wafer cannot be mirror-finished.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a mirror polishing apparatus for a semiconductor wafer capable of mirror polishing under optimum polishing conditions for each wafer. is there.

[0007]

In order to achieve the above object, the invention according to claim 1 is a polishing drum driving means comprising a polishing drum and a drum driving source for rotating the polishing drum, and the polishing drum. At least one wafer driving means provided in the vicinity of the driving means, a chuck driving means provided on the wafer driving means, and capable of oscillating in the axial direction of the polishing drum by an oscillating means; and being provided on the chuck driving means. And a chuck for holding a wafer whose chamfered portion is mirror-finished on the outer peripheral surface of the polishing drum, and a chuck drive source for rotating the chuck.

With the above structure, the chamfered portion of the wafer is mirror-finished on the outer peripheral surface of the polishing drum while the wafer is oscillated in the axial direction of the polishing drum, so that minute irregularities generated in the chamfered portion can be reliably removed. And the mirror finishing of the chamfered portion can be performed efficiently in a short time.

In addition, by oscillating the wafer in the axial direction of the polishing drum, the contact position between the chamfered portion and the polishing drum is constantly shifted, so that the cloth of the polishing drum is not locally worn, thereby reducing the life of the cloth. In addition, the cost of replacing the cloth can be reduced, and the maintenance management becomes easy.

According to a second aspect of the present invention, there is provided an urging means for urging the chuck driving means toward the polishing drum, and a retracting means for retracting the chuck driving means in a direction away from the polishing drum. .

According to the above configuration, the chamfered portion of the wafer can always be brought into contact with the outer peripheral surface of the polishing drum with a constant surface pressure, so that a stable mirror finish can be performed and the processing accuracy of the chamfered portion can be improved. .

In order to achieve the above object, the invention according to claim 3 is provided with angle varying means for inclining the rotation center of the chuck provided in the chuck driving means at an arbitrary angle.

With the above configuration, the center of rotation of the chuck can be inclined according to the chamfer angle of the chamfered portion, so that the present invention can be applied to all wafers having different chamfer angles, and the center of rotation of the chuck is parallel to the center of rotation of the polishing drum. By doing so, it becomes possible to mirror-process the outer peripheral surface of the wafer.

According to a fourth aspect of the present invention, a plurality of wafer driving means are provided near the polishing drum driving means.

According to the above configuration, by separately controlling the oscillating means of each wafer driving means, it becomes possible to mirror-process the chamfered portion under optimum polishing conditions in accordance with the polishing conditions of each surface of the wafer to be mirror-polished.

[0016]

Embodiments of the present invention will be described in detail with reference to the drawings. 1 is a front view of the mirror finishing apparatus, FIG. 2 is a plan view of the same, FIG. 3 is a view taken in the direction of arrow A in FIG. 1, and FIG.

In these figures, reference numeral 1 denotes an apparatus main body, which comprises a polishing drum driving means 2 and one or a plurality of wafer driving means 3 installed in the vicinity thereof. The polishing drum driving means 2 has a cylindrical drum housing chamber 4 on a gantry 1a, and a rotary shaft 5 is supported in the center of the drum housing chamber 4 in a vertical direction. A polishing drum 6 housed in a drum housing chamber 4 is detachably attached to the upper end of the drum.

The polishing drum 6 has a cylindrical drum body 6.
A cloth 6b is wound around the outer peripheral surface of the wafer 20a, and a chamfered portion 20a of the wafer 20 described later is mirror-finished on the surface of the cloth 6b. The lower end of the rotary shaft 5 is connected to a drum drive source 7 such as a motor fixed to the gantry 1 a side, and the polishing drum 6 is rotated by the drum drive source 7 via the rotary shaft 5. Has become.

On the other hand, the wafer driving means 3 has a box-shaped casing 3a whose periphery is covered by a cover 3b, and is vertically movable by an oscillating means 8 on the top of the casing 3a. A table 10 is provided. A vertical support member 10a is provided on the lower surface of the elevating table 10, and a support portion 8a fixed to the support member 10a is provided with a pair of LM guides 8b fixed vertically in the housing 3a. It is supported slidably up and down.

In the vicinity of the support member 10a, the LM
A ball screw 8c is rotatably supported so as to be parallel to the guide 8b.
The ball screw 8c is screwed together, and the lower end of the ball screw 8c is connected to an oscillating drive source 9 composed of a motor via a gear 8e. The reverse rotation allows the lifting table 10 to move up and down along the guide rod 8b.

A pair of guide rails 12 are laid on the upper surface of the elevating table 10 so as to be horizontal in the direction of the polishing drum driving means 2. It is supported movably. On the slide table 13, there is provided a chuck driving means 15 which can be tilted to an arbitrary angle by an angle changing means 14.

The angle varying means 14 has a movable member 14b above a support frame 14a fixed on the slide table 13, as shown in FIG. The movable member 1
Reference numeral 4b denotes the support frame 14a via a horizontal shaft 14c provided in a direction orthogonal to the moving direction of the slide table 13.
Is rotatably supported on the upper part of the shaft, and can be inclined at an arbitrary angle about the horizontal shaft 14c by an actuator 14d such as a hydraulic cylinder. The chuck driving source 1 of the chuck driving means 15 is attached to the movable member 14b.
6 are attached.

The chuck driving source 16 is composed of, for example, a motor, and is connected to a rotating shaft 16a supported at a position close to the polishing drum 6 via a gear 16b. 17 is fixed. The chuck 17 has a smaller diameter than the outer diameter of the wafer 20 to be mirror-finished, so that the upper surface of the chuck 17 can detachably adsorb the wafer 20.

On the other hand, a bracket 13a protrudes from the lower surface of the slide table 13 into the housing 3a, and one end of a cable 18a of the urging means 18 is connected to the tip of the bracket 13a. The urging means 18
Is to press the wafer 20 attached to the chuck 17 against the outer peripheral surface of the polishing drum 6 by using the weight of the weight 18b, and for example, three support members 10c fixed to the lower surface of the lifting table 10 Guide rollers 18c, 18d,
18e is rotatably supported.

These guide pulleys 18c-18e
The weight 18b is connected to the other end of the cable 18a that is detoured to the support member 10c, and a retracting means 19 is attached to the support member 10c substantially horizontally. Evacuation means 19
Is composed of, for example, a hydraulic cylinder or a pneumatic cylinder, and a pair of guide rods 19 is provided at the tip of a piston rod 19b projecting from the cylinder 19a in a direction opposite to the polishing drum 6.
A connecting rod 19d fixed to one end face of the link c is fixed.

The other end of each guide rod 19c is loosely inserted into a notch 13b formed in the bracket 13a, and a stopper 19d protruding from the other end of each guide rod 19c is connected to the notch 13d. 13b, the stopper 19d is engaged with the bracket 13a so that the chuck driving means 14 can be retracted in the direction of separating the chuck driving means 14 from the polishing drum 6 against the urging force of the urging means 18. It has become.

In the figure, reference numeral 15e denotes a cover which covers the angle varying means 14 and the chuck driving means 15. Further, in the above-described embodiment, the case where one wafer driving unit 3 is installed near the polishing drum driving unit 2 has been described. However, actually, a plurality of wafer driving units 3 having the same structure are installed. Thus, these wafer driving means 3 can be controlled independently.

Next, the operation of the above-structured mirror finishing apparatus will be described. The outer peripheral edge of the wafer 20 to be mirror-finished is preliminarily chamfered as shown in FIG. 5, and recently, a back surface oxide film 20b for back sealing is formed on the back surface of the chamfered wafer 20. If the oxide film on the outer peripheral edge cannot be completely removed in the mirror polishing process, nodules 20c made of granular polysilicon are generated in the chamfered portion 20a in the subsequent heat treatment process. If this nodule 20c is not removed, it will peel off during the heat treatment process,
When the chamfered portion 20a is mirror-finished, the backside oxide film 20b is also removed from the wafer 20 on which the backside oxide film 20b has been formed, since this causes particles to be generated.

First, the chuck driving means 15 is stopped at a position where the chuck 17 becomes horizontal, and the wafer 20 to be mirror-finished is carried into the upper surface of the chuck 17 by a transfer means (not shown) and is suction-held on the upper surface of the chuck 17. . Next, in this state, the rotation center O of the chuck 17 is inclined about the horizontal axis 14c by the angle varying means 14 in accordance with the chamfer angle θ of the chamfered portion 20a of the wafer 20.

Then, the polishing drum 6 is driven by the drum driving source 7.
The retracting means 19 is contracted while the chuck 17 is rotated by the chuck driving source 16, and the chuck driving means 15 is moved toward the polishing drum 6, and the chamfered portion 20 a of the wafer 20 held by the chuck 17 is illustrated. As shown by the imaginary line 1, the elevating table 10 is moved up and down (oscillate) in a direction parallel to the rotation center O ′ of the polishing drum 6 by means of the oscillating means 18, and the chamfering is performed. The mirror processing of the part 20a is started.

During the mirror finishing, the weight 1 of the urging means 18 is
The chamfered portion 20a is pressed against the outer peripheral surface of the polishing drum 6 with a constant surface pressure using the weight of 8b. When a plurality of wafer driving units 3 are provided, the oscillation speed and stroke of the oscillation unit 8 provided for each wafer driving unit 3 are individually determined according to the polishing conditions of the wafer 20 to be mirror-finished. By performing the control, the mirror polishing of the chamfered portion 20a can be performed under the optimal polishing conditions for each wafer 20.

When the mirror finishing of one chamfered portion 20a is completed as described above, the chuck 17 is returned to the horizontal position while the chuck driving means 15 is retracted by the retracting means 19 in the direction away from the polishing drum 6, and In this state, the wafer 20 which has been mirror-polished on one side is turned upside down, sucked on the chuck 17 again, and the above operation is repeated to mirror-process the remaining chamfered portion 20a. In such a case, the wafer 20 on which one-side mirror processing has been completed may be carried into the next wafer driving means 3 while being inverted, and the remaining chamfered portion 20a may be subjected to mirror processing.

Further, the chuck driving means 15 is moved toward the polishing drum 6 while the chuck 17 is held horizontally, and the outer peripheral surface of the wafer 20 is brought into contact with the outer peripheral surface of the polishing drum 6. Mirror finishing is also possible.

[Brief description of the drawings]

FIG. 1 is a front view showing a semiconductor wafer mirror finishing apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing a semiconductor wafer mirror processing apparatus according to an embodiment of the present invention;

FIG. 3 is a view from arrow A in FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is an explanatory view of a wafer to be mirror-finished;

[Explanation of symbols]

 2 Polishing drum driving means 3 Wafer driving means 6 Polishing drum 7 Drum driving source 8 Oscillating means 14 Angle changing means 15 Chuck driving means 16 Chuck driving source 17 Chuck 18 Urging means 19 Retreat Means 20: Wafer 20a: Chamfer O: Chuck rotation center

Claims (4)

[Claims] 1. A polishing drum driving means (2) comprising a polishing drum (6) and a drum driving source (7) for rotationally driving the polishing drum (6), and installed near the polishing drum driving means (2). At least one wafer driving means (3) provided, and
And the above-mentioned polishing drum (6) by an oscillating means (8)
Chuck driving means (1
5) a chamfered portion (20a) provided on the chuck driving means (15) and formed on the outer peripheral surface of the polishing drum (6).
Chuck (1) holding a wafer (20) for mirror-finish
7) and a chuck driving source (16) for rotating and driving the chuck (17). 2. An urging means (18) for urging the chuck driving means (15) toward the polishing drum (6), and a retracting means (19) for retracting the chuck driving means (15) away from the polishing drum (6).
2. The mirror finishing apparatus according to claim 1, wherein the apparatus comprises: 3. The mirror finishing according to claim 1, further comprising an angle varying means (14) for inclining the rotation center (O) of the chuck (17) provided in the chuck driving means (15) to an arbitrary angle. apparatus. 4. The mirror processing apparatus according to claim 1, wherein a plurality of wafer driving means (3) are provided near the polishing drum driving means (2).