JPH06104297B2 - Chamfering equipment for semiconductor wafers - Google Patents

Description

TECHNICAL FIELD The present invention relates to a chamfering device for a semiconductor wafer, which chamfers an edge of a semiconductor wafer by grinding it with a rotary grindstone.

[Prior Art] This type of semiconductor wafer chamfering device has a substantially V-shaped or U-shaped structure as shown in FIG. 4 or FIG.
Grooves 2a and 2b having a V-shaped cross-section are formed, and the edge portion of the semiconductor wafer 10 is chamfered by moving the grindstone in the direction of the arrow while rotating. 5 to show the order of this movement. Both cross sections have arcs A ₁ B ₁ and A ₂ B ₂ with radii R ₁ and R _{2 at} the bottom, and open ends E ₁ and E ₂ and _one ends B ₁ and B _{2 of} this arc are connected by a straight line. It has a curved shape. For example, for a semiconductor wafer 10 thickness of 0.6 to 0.7 mm, arc radii R ₁ and R ₂ are 0.25 mm, and groove depths D ₁ and D ₂ are 1 m.
m, the opening widths W ₁ and W ₂ of the grooves are 1.16 mm and 6 mm, respectively, and the side surface inclination angle θ is 22 °.

At the time of this chamfering, in order to maintain the grinding ability, the cathode block is brought close to this groove, the conductive grindstone is used as an anode, and a DC voltage is applied while flowing an electrolytic solution between both electrodes, so that the electrolytic dressing of the grindstone is performed. It is possible.

[Problems to be Solved by the Invention] However, electrolytic dressing is not performed uniformly along the surface of the groove of the grindstone, and electrolytic dressing on the bottom side of the groove is not performed as indicated by the alternate long and short dash line in FIGS. It becomes remarkable and the chamfered shape is deformed as shown by the alternate long and short dash line. In this case, for example, when a photoresist is applied to the mirror surface of the semiconductor wafer 10, the stepped portion rises, and when the chamfering inclination is small, the mask is prevented from approaching. Alternatively, even if such a stepped portion is not formed, the chamfered portion of the semiconductor wafer has an uneven shape. Therefore, it is necessary to replace the grindstone before such deformation.

In view of the above problems, an object of the present invention is to provide a chamfering device for a semiconductor wafer, which can maintain the shape of the groove of the grindstone in the initial shape for a long period of time.

[Means for Solving the Problems] In order to achieve this object, in a chamfering device for a semiconductor wafer according to the present invention, a conductive grindstone in which a chamfering groove having rotationally symmetrical chamfering grooves is formed on an outer peripheral surface, A means for rotating the grindstone about its rotational symmetry center line; an electrode whose surface facing the groove is substantially the same as the surface of the groove; and an electrode which is arranged close to the surface of the groove, A surface having a plane passing through the rotational symmetry center line and a surface of the groove, having means for flowing an electrolytic solution between the surfaces of the groove and the electrode facing each other, and means for applying a DC voltage between the grindstone and the electrode. The line of intersection with is a concave shape in which the central portion is depressed toward the rotational symmetry center line side, and the bottom side portion which is the boundary portion between the bottom portion and the side portion of the concave portion is a curved portion having a radius of curvature of 0.4 mm or more.

It is preferable that, in the intersecting line, a groove end portion that is a boundary portion between the concave portion and both sides thereof is a curved portion having a curvature radius of 1.5 to 2.5 times a curvature radius of the bottom side portion.

The more specific cross-sectional shape of the groove is, for example, a substantially V shape as shown in FIG. 2 or a substantially U shape as shown in FIG.

As a material for the electrode, a material that is easy to mold and has chemical resistance to an electrolytic solution, particularly graphite is preferable.

[Operation] With a grindstone having a groove having such a cross-sectional shape, concentration of electrolytic action at the bottom side of the groove is greatly reduced, and a preferable initial cross-sectional shape can be maintained for a long period of time.

In the cross-sectional shape of the groove on the outer peripheral surface of the grindstone, if the groove end is a curved portion having a radius of curvature of 1.5 to 2.5 times the radius of curvature of the bottom side,
The intensive electrolytic dressing at the groove ends is prevented, and the above effect is enhanced.

The grinding wheel edge is consumed by repeated grinding work and electrolytic dressing, so it is necessary to finely modify the shape of the electrode.However, when the electrode is made of graphite, this fine modification is well performed due to the ease of processing of graphite. Be seen.

EXAMPLES Examples of the present invention will be described below with reference to the drawings.

(1) First Embodiment FIG. 1 shows a schematic configuration of a semiconductor wafer chamfering device.

The clamp device 12 includes a pair of clamp disks 12a and 12b.The semiconductor wafer 10 is concentrically placed on the lower rotatable clamp disk 12a and then lifted to be pressed against the clamp disk 12b. The disk 12b is rotationally driven and integrally rotated.

On the other hand, on both the upper and lower sides of the core disc 14, side discs
16 and 18 are fixed concentrically. Side disc 16, 18
Have the same radius and are larger than the radius of the core disk 14, and a ring-shaped groove is formed in the peripheral surface portion of the core disk 14. A ring-shaped chamfering grindstone 20 is fixed to the groove. The binder of the grindstone 20 is electrically conductive and is preferably a cast bond or cast iron fiber bond. The abrasive grains of the grindstone 20 are, for example, # 2,000 high count abrasive grains. Whetstone 2
On the outer peripheral surface of 0, a rotationally symmetrical ring-shaped groove 20a is formed. The surface of the groove 20a has a plane of symmetry perpendicular to the center line of the core disk 14, and one side of the symmetric figure has an arc A ₁ B ₁ with a radius R _{3 at} the bottom as shown in FIG. The curved line B ₁ C ₁ smoothly connects the circular arc A ₁ B ₁ and the side straight line E ₁ C ₁ . In addition, the opening has an arc E _{1 with a} radius R ₄
Have F ₁ .

Since the chamfering of the semiconductor wafer is processed by the curve B ₁ C ₁ part and the arc A ₁ B ₁ part, the radius R _{4 of the} opening is not directly related to the present invention. R _{3 is} used to prevent intensive electrolytic removal at the opening.
> R ₁ , preferably R ₄ = 1.5 to 2.5R ₃ .

The inclination angle θ and the depth D ₃ of the substantially straight line C ₁ E ₁ are the same as those shown in FIG.

In FIG. 1, a core disk 14, side disks 16 and 18 are concentrically fixed to one end of a rotary shaft 22, and the rotary shaft 22 is rotated by a motor (not shown).

In order to maintain the grinding ability of the grindstone 20, electrolytic dressing is performed during grinding.

That is, the cathode block 24 is arranged so as to face the groove 20a. The surface shape of the cathode block 24 is substantially the same as the surface shape of the groove 20a. The cathode block 24 is made of an electrically conductive and easily moldable material such as carbon or graphite, and is pressed into the groove 20a of the grindstone 20. The cathode block 24 is fitted and held by an insulative cathode block holder 26, and the cathode block holder 26 is fixed to one end of an inverted L-shaped arm 28, and the other end of the arm 28 includes a contacting / separating mechanism 30 and a lifting mechanism 32. Through fixed base
It is attached to one end of 34. Micrometer heads 30a and 32a for operating the contacting / separating mechanism 30 and the elevating mechanism 32 are attached respectively. When the micrometer heads 30a and 32a are rotated, the cathode block 24 is moved in the left-right direction in FIG. , Moved up and down.

The cathode block 24 is connected to the negative terminal of the DC pulse power supply 36 via wiring. On the other hand, an anode block 40 is attached to the lower end of the fixed insulating support rod 38, and this anode block 40 is in contact with the conductive side disk 16. The anode block 40 is connected to the positive terminal of the DC pulse power supply 36. Therefore, the cathode block 24 and the grindstone 20
A pulsed electric field is formed in the gap between and.

Cathode block 24 and cathode block holder 26 have multiple holes.
41 are bored, and these are commonly connected to a supply pipe 42, and an electrolytic solution is supplied to the supply pipe 42 to flow into the gap between the cathode block 24 and the grindstone 20. This electrolytic solution is electrically conductive (resistivity of about 2 × 10 ¹⁴ Ωcm) and is water-soluble ground. For example, commercially available Noritake Cool AFC-M (manufactured by Noritake Co., Ltd.) or water-soluble chemical solution Johnson JC-707. (Manufactured by Johnson Co., Ltd.) is diluted 20 to 50 times, and also functions as a cooling liquid.

On the other hand, a nozzle 44 is arranged on the side opposite to the cathode block 24 in the diameter direction with respect to the grindstone 20, and the grinding liquid is jetted from the nozzle 44 to the silicon wafer 10 and the grindstone 20 which are in contact with each other. As the search liquid, the same liquid as the electrolytic liquid can be used.

In the above configuration, the distance between the grindstone 20 and the cathode block 24
Adjust the rotary shaft 22 to, for example, 1200
The rotary shaft 22 and the fixed base 34 are integrally moved to the left in FIG. 1 while rotating at ˜1500 rapm. Then, as shown in FIG. 2, the silicon wafer 10 is brought into contact with the groove 20a of the grindstone 20 and the edge thereof is ground, and the movement of the rotary shaft 22 to the left is stopped to move the silicon wafer 10 to, for example, 50 sec / rev, Chamfering is performed on the entire circumference of the silicon wafer 10 by rotating with.

(2) Test Example Using the above apparatus, a grindstone having a sectional shape shown in FIG.
When chamfering was performed using the grindstone 20 having the sectional shape shown in the figure, when chamfering about 50 silicon wafers 10 with the former grindstone, the bottom of the groove was stepped as shown by the dashed line in FIG. No change was observed in the step surface shape of the groove 20a even when chamfering 50 pieces with the whetstone No. 20, and about 300 pieces formed the same step portion as the former 50 pieces.

However, the dimensions that determine the shape of the groove are 0.6 mm in thickness and 1 in diameter.
For a 25 mm silicon wafer, R ₁ = 0.25 mm R ₃ = 0.5 mm R ₄ = 1.0 mm D ₁ = 1.0 mm D ₃ = 1.3 mm W ₁ = 1.16 mm θ = 22 ° in Figs. It was

The effect of the present invention was obtained even when the same test was performed with R _{3 set} to 0.4 mm.

(3) Second Embodiment FIG. 3 shows the groove 20b of the grindstone of the second embodiment corresponding to FIG.
The cross-sectional shape of The other points are the same as in the first embodiment.
The shape of this groove 20b is such that the bottom surface is a straight line parallel to the opening end surface, the side portion has an arc A ₂ B ₂ with a radius R ₅ of the bottom portion, and this arc A ₂ B ₂ and the substantially straight line of the side portion. The curve B ₂ C ₂ is smoothly connected to E ₂ F _2, and the opening has an arc E ₂ F ₂ with a radius of ₆ .
The radii R ₅ , R ₆ , the shape of the curve A ₂ B ₂ C ₂ E ₂ F ₂ , the inclination angle θ of the substantially straight line C ₂ E ₂ and the groove depth D ₄ are the same as those shown in FIG. Radius ₆ is the same as above, preferably radius ₅ is 1.5 to 2.5
Double.

The function and effect of the groove 20b is the same as the function and effect of the groove 20a shown in FIG.

[Advantages of the Invention] In the chamfering device for a semiconductor wafer according to the present invention, in the sectional shape of the outer peripheral surface of the rotary grindstone, the bottom side of the groove has a radius of curvature
Since it is a curved portion of 0.4 mm or more, the concentration of electrolytic action at the bottom side of the groove is greatly reduced, and it has an excellent effect that it is possible to maintain a preferable initial cross-sectional shape for a long period of time. It is not necessary to frequently replace the wafers, which contributes to the improvement of work efficiency and the reduction of the manufacturing cost of the semiconductor wafer.

Further, in the cross-sectional shape of the groove on the outer peripheral surface of the grindstone, the groove end,
By forming the curved portion with a radius of curvature 1.5 to 2.5 times the radius of curvature of the bottom side portion, intensive electrolytic dressing at the groove end is prevented, and the above effect is enhanced.

[Brief description of drawings]

1 and 2 relate to a first embodiment of the present invention. FIG. 1 is a schematic configuration diagram of a chamfering device for a semiconductor wafer, and FIG. 2 is an enlarged sectional view of a groove 20a shown in FIG. FIG. 3 is a sectional view showing the groove shape of the grindstone of the second embodiment. FIGS. 4 and 5 are sectional views showing the shapes of the grooves of the conventional grindstone corresponding to FIGS. 2 and 3, respectively. In the figure, 10: Silicon wafer 12: Clamping device 14: Core disk 16, 18: Side disk 20: Grindstone 22: Rotary shaft 24: Cathode block 26: Cathode block holder 28: Arm 36: DC pulse power supply 40: Anode block 42 : Electrolyte supply pipe 44: Grinding liquid nozzle

Claims (5)

[Claims] 1. A chamfering groove (20a, 20a) having rotational symmetry on the outer peripheral surface.
b) a conductive grindstone (20) having formed therein, means for rotating the grindstone (20) around its rotational symmetry center line, and the shape of the surface facing the groove (20a, 20b) is the surface of the groove. An electrode (24) having substantially the same shape as that of the electrode (24) arranged close to the surface of the groove, and a means for flowing an electrolytic solution between the surfaces of the groove (20a, 20b) and the electrode (24) facing each other, A means for applying a DC voltage between the grindstone (20) and the electrode (24), the line of intersection between the plane passing through the rotational symmetry center line and the surface of the groove (20a, 20b) is The central part has a concave shape that is recessed toward the rotational symmetry center line side, and the bottom side part that is the boundary part between the bottom part and the side part of the recess is 0.4 m.
A chamfering device for a semiconductor wafer, which is a curved portion (A ₁ B ₁ , A ₂ B ₂ ) having a radius of curvature (R ₃ , R ₅ ) of m or more. 2. The intersection line has a groove end portion which is a boundary portion between the concave portion and both sides thereof and has a radius of curvature (R ₃ , R ₅ ) of the bottom side portion.
The apparatus according to claim 1, wherein the curved portion has a radius of curvature (R ₄ , R ₅ ) of 1.5 to 2.5 times. 3. The device according to claim 2, wherein the cross-sectional shape of the groove is substantially V-shaped. 4. The device according to claim 2, wherein the cross-sectional shape of the groove is substantially U-shaped. 5. Device according to claim 2, characterized in that the electrode (24) is made of graphite or carbon.