JPH0837169A - Method and apparatus for grinding semiconductor substrate and manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the peripheral edge part of a semiconductor substrate from being chipped and cracked and to enhance the yield in a rear grinding process when the rear of the semiconductor substrate is ground. CONSTITUTION:In a state that a semiconductor substrate 1 has been ground to a desired thickness, the semiconductor substrate 1 is tilted with reference to its rear, and its peripheral edge part on the rear is ground so as to become a state that the peripheral edge of the substrate 1 is chamfered. After that, the whole rear of the semiconductor substrate 1 is ground equally in such a way that a part of a slope 1a formed by its grinding operation is left. Consequently, the peripheral edge part on the rear side of the semiconductor substrate 1 is ground while it is tilted with reference to the rear. After that, while the slope 1a at the peripheral edge part on the rear side is left, the rear is ground equally. Thereby, the slope 1a, at the peripheral edge part on the rear side, which is left after the rear has been ground becomes a chamfered shape. As a result, it is possible to prevent the peripheral edge part from being chipped and cracked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of semiconductor device manufacturing, and is particularly effective when applied to a method of grinding the back surface of a semiconductor substrate.

[0002]

2. Description of the Related Art Transistors and semiconductor integrated circuits (ICs)
In the manufacture of such a semiconductor device, in order to form an element on the main surface of the semiconductor substrate, the surface of the semiconductor substrate is subjected to treatments such as impurity implantation, diffusion, photolithography, etching and CVD. At this time, since the semiconductor substrate is transferred and transported between each processing step, there is a problem that chipping occurs at the peripheral edge of the semiconductor substrate and the fragments adhere to the surface of the semiconductor substrate. to solve this problem,
Conventionally, as disclosed in JP-B-53-38594, chamfering is performed on the peripheral edge of a semiconductor substrate (FIG. 7A). Recently, the diameter of the semiconductor substrate has been increased to 6 inches or 8 inches,
In order to maintain its strength, the plate thickness is made thicker than the conventional one to prevent chipping and cracking. However, since the package thickness is standardized when the pellets are sealed in the package, it is necessary to reduce the thickness of the semiconductor substrate to about 400 to 500 μm in advance.
Among them, particularly in IC cards and surface mount ICs, it is essential to reduce the plate thickness to about 200 to 300 μm and divide into pellets.

As a technique for thinning a semiconductor substrate, a method of mechanically grinding the back surface of the semiconductor substrate is widely used. The method for grinding a semiconductor substrate is described in, for example, Japanese Patent Publication No. 63-12741.

[0004]

When a back surface of a semiconductor substrate is ground, a protective film such as a resist or a tape is formed in order to protect elements formed on the front surface, and then a thickness specified by package specifications is reached. The back surface is ground, but by carrying out the back surface grinding, the cross-sectional shape of the chamfer of the peripheral edge of the semiconductor substrate changes to an acute angle shape as shown in FIGS. 7B and 7C. This shape greatly differs depending on the thickness of the semiconductor substrate to be ground on the back surface, and becomes thinner as it becomes thinner. Further, if the semiconductor substrate becomes thinner, the strength of the substrate itself will be extremely reduced. In particular, in recent semiconductor substrates having a large diameter, the strength is remarkably reduced.
Therefore, when the acute angle portion 17b is subjected to stress during back surface grinding or even a slight impact in the post-treatment process, chipping easily occurs. Furthermore, the chipping point becomes a break, and it is easy to break with a slight impact.

Therefore, an object of the present invention is to prevent chipping or cracking of the peripheral edge of the semiconductor substrate during backside grinding of the semiconductor substrate and improve the yield in the backside grinding process.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0007]

The outline of the representative one of the inventions disclosed in the present application will be briefly described as follows. That is, after the peripheral edge portion on the back surface side of the semiconductor substrate is inclined and ground with respect to the rear surface, the entire rear surface surface is ground while leaving the inclined surface of the peripheral edge portion on the rear surface side to a desired thickness. It's something to say.

[0008]

According to the above means, since the inclined surface of the peripheral portion on the back surface side remaining after grinding the back surface has a chamfered shape, chipping and cracking can be prevented.

[0009]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a manufacturing flow chart of a semiconductor device of the present invention, and FIG. 2 shows a grinding method of a semiconductor substrate 1. First, the surface of the semiconductor substrate 1 whose peripheral edge is chamfered in advance is subjected to treatments such as impurity implantation, diffusion, photolithography, etching and CVD to form an element that constitutes an integrated circuit. Next, a protective film such as a resist or a tape is formed to protect the elements formed on the surface of the semiconductor substrate 1,
The back surface of the semiconductor substrate is ground using a grinding machine. At this time, in the state where the semiconductor substrate 1 is ground to a desired thickness, the rear surface peripheral portion of the semiconductor substrate 1 is ground by inclining it with respect to the rear surface so that the peripheral portion of the semiconductor substrate 1 is chamfered. After that, the entire back surface of the semiconductor substrate 1 is evenly ground so that a part of the inclined surface 1a formed by this grinding remains. According to this method, since the inclined surface 1a is formed in the peripheral portion of the back surface of the semiconductor substrate 1 in advance, it is chamfered even after the back surface is ground. Therefore, chipping and cracks accompanying it can be reduced during back surface grinding and in the subsequent post-treatment process. If the inclined surface 1a is formed on the back surface side before the element is formed, for example, when the semiconductor substrate itself is formed, only the back surface grinding may be performed after the element formation as usual.

After cleaning the back surface, the semiconductor substrate 1 is processed into individual semiconductor devices through steps such as probe inspection, dicing, assembly and packaging after cleaning. still,
After cleaning, in order to reinforce the thinned semiconductor substrate 1, a reinforcing material such as a UV tape may be attached from the back surface. In that case, if the pellets are attached up to the dicing step and peeled off from the reinforcing material when the pellets are picked up, the pellets can be mounted on the pellet mounting substrate with the back surface ground thinness.

Next, a semiconductor substrate grinding apparatus used in the present invention will be described. FIG. 3 shows the main part of the grinding device 3. The main part of the grinding device 3 is a stage 4 for mounting and fixing the semiconductor substrate 1 and performing a rotary motion at the time of grinding, and a grindstone 5 is attached to the surface of a support 6 on a disk, so that vertical movement and rotary motion can be performed. Composed of possible grinding members 7. In the present invention,
By adding the inclination θ to the stage 4, the semiconductor substrate 1
It is possible to form the inclined portion 1a at the peripheral portion of the back surface of the. First, the semiconductor substrate 1 is fixed to the stage 4 with the front surface as a mounting surface. Next, the stage 4 is rotated with an inclination of θ, and the grinding member 7 is lowered while being rotated to grind the peripheral portion of the semiconductor substrate 1. After the inclined portion 1a is formed by such a grinding method, the stage 4 is attached to the support 6
Then, the back surface of the semiconductor substrate 1 is evenly ground while the inclined portion 1a remains. In this grinding device 3, the inclined surface 1a can be formed only by inclining the stage 4, so that the mechanical surface does not need to be significantly modified. Therefore,
The backside grinding of the present invention can be easily supported.

[0012]

[Embodiment 2] In this embodiment, a method for simultaneously performing chamfering and back grinding will be described. FIG. 4 shows a flow chart of manufacturing a semiconductor device in this embodiment, and FIG. 5 shows a method of grinding the semiconductor substrate 8. First, the surface of the semiconductor substrate 8 whose peripheral edge is chamfered in advance is subjected to treatments such as impurity implantation, diffusion, photolithography, etching, and CVD to form an element forming an integrated circuit. Next, the semiconductor substrate 8
A protective film 9 such as a resist or a tape is formed to protect the element formed on the front surface, and the back surface of the semiconductor substrate is ground using a grinding machine. In this embodiment, in the state where the semiconductor substrate 8 is ground to a desired thickness, the back surface is chamfered at the same time as the back surface grinding so that the peripheral portion of the semiconductor substrate 8 is chamfered. FIG. 6 shows a main part of the grinding device 10 used in this embodiment. The main part of the grinding apparatus 10 is a stage 11 that mounts and fixes the semiconductor substrate 8 and performs a rotary motion during grinding, and a grindstone 13 is attached to the surface of a support 12 on a disk so that vertical movement and rotation can be performed. Possible grinding member 1
It is composed of 4. In the present invention, the chamfering grindstone 16 for chamfering the peripheral portion simultaneously with the back surface grinding by the grinding member 14
Is provided. First, the semiconductor substrate 8 is fixed to the stage 11 with the front surface as a mounting surface. Next, the grinding member 14 is rotated and lowered to uniformly grind the back surface of the semiconductor substrate 8, and the chamfering grindstone 16 is rotated to be brought into contact with the peripheral edge portion on the back surface side of the semiconductor substrate 8 for chamfering. By this method, chipping and cracks accompanying it can be reduced during the backside grinding and the subsequent post-treatment step, and both the backside grinding and the chamfering of the semiconductor substrate can be performed within the conventional backside grinding time. .

After cleaning the back surface of the semiconductor substrate 8, the semiconductor substrate 8 is processed into individual semiconductor devices through steps such as probe inspection, dicing, assembly and packaging.

The operation and effect of the present invention will be described below.

(1) The back surface is ground by inclining the peripheral edge portion on the back surface side of the semiconductor substrate with respect to the back surface and then grinding the back surface evenly while leaving the inclined surface of the peripheral edge portion on the back surface side. Since the inclined surface of the peripheral portion on the back surface side that remains afterward has a chamfered shape, chipping and cracking can be prevented.

(2) After grinding the backside peripheral edge of the semiconductor substrate whose peripheral edge has been chamfered in advance with respect to the backside, grinding the backside while leaving the backside peripheral edge sloped surface. Since the grinding is performed uniformly, it is not necessary to newly chamfer the front surface side.

(3) By forming the inclined surface of the peripheral portion on the back surface side before forming the element on the semiconductor substrate, only the back surface grinding can be performed after the element formation as usual.

(4) By grinding the back surface of the semiconductor substrate and chamfering the peripheral portion on the back surface side at the same time, chipping and accompanying cracks can be reduced during the back surface grinding and in the subsequent post-processing steps. Both the back surface grinding and the chamfering of the semiconductor substrate can be performed within the conventional back surface grinding time.

(5) Since the grinding device can grind in a state in which the stage or the grinding member is tilted, the peripheral portion on the back surface side of the semiconductor substrate can be changed to the back surface without adding a new grinding member to the grinding device. It can be inclined and ground.

(6) In the method of manufacturing a semiconductor device, the peripheral portion of the back surface side of the semiconductor substrate is inclined and ground with respect to the rear surface, and then the inclined surface of the peripheral edge portion of the rear surface side is left and the rear surface is evenly formed. By including the step of grinding, it is possible to improve the manufacturing yield of thin package ICs and IC cards.

[0021]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

That is, after grinding the back surface side peripheral edge of the semiconductor substrate while inclining to the back surface, the back surface is evenly ground while leaving the inclined surface of the back surface side peripheral edge part, and after the back surface grinding. Since the remaining inclined surface of the peripheral portion on the back surface side has a chamfered shape, chipping and cracking can be prevented.

[0023]

[Brief description of drawings]

FIG. 1 is a manufacturing flow chart of a method of manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2A shows a cross section of a chamfered semiconductor substrate. FIG. 3B is a sectional view showing a state in which an inclined surface is formed at the peripheral edge of the back surface of the semiconductor substrate. (C) shows a cross-sectional view of a state in which the back surface of the semiconductor substrate is evenly ground with a part of the inclined surface remaining.

FIG. 3 is a diagram showing a main part of a grinding apparatus that is an embodiment of the present invention.

FIG. 4 is a manufacturing flow chart of a method of manufacturing a semiconductor device according to another embodiment of the present invention.

FIG. 5A shows a cross section of a chamfered semiconductor substrate. (B) is a cross-sectional view of the semiconductor substrate in a state where a chamfering process is performed simultaneously with the back surface grinding.

FIG. 6 is a diagram showing a main part of a grinding apparatus that is another embodiment of the present invention.

FIG. 7A shows a cross section of a chamfered semiconductor substrate. FIG. 6B is a cross-sectional view of the semiconductor substrate showing a state of conventional backside grinding. (C) is an enlarged view of the peripheral portion of the semiconductor substrate of (b).

[Explanation of symbols]

1 ... Semiconductor substrate, 1a ... Inclined surface, 2 ... Protective film, 3
…… Grinding device, 4 …… Stage, 5 …… Grinding stone, 6 …… Supporting body, 7 …… Grinding member, 8 …… Semiconductor substrate, 9 …… Protective film, 10 …… Grinding device, 11 …… Stage, 12 ... Support member, 13 ... Grinding stone, 14 ... Grinding member, 15 ... Spindle, 16 ... Chamfering grindstone, 17 ... Semiconductor substrate, 17a ... Grinding surface, 17b ... Sharp corner, 18 ... Protective film

Claims (6)

[Claims] 1. A method of grinding a semiconductor substrate, wherein the entire back surface of a semiconductor substrate is ground to reduce the thickness of the semiconductor substrate, the peripheral edge portion of the semiconductor substrate on the back surface side being inclined with respect to the back surface, and then ground. While leaving the inclined surface of the peripheral portion on the back surface side,
A method of grinding a semiconductor substrate, wherein the semiconductor substrate is made to have a desired thickness by uniformly grinding the back surface. 2. The method for grinding a semiconductor substrate according to claim 1, wherein the peripheral edge portion of the semiconductor substrate is chamfered in advance. 3. The method of grinding a semiconductor substrate according to claim 1, wherein the inclined surface of the peripheral portion on the back surface side is formed before forming an element on the semiconductor substrate. 4. A method of grinding a semiconductor substrate, wherein the entire back surface of the semiconductor substrate is ground to reduce the thickness of the semiconductor substrate, wherein the back surface of the semiconductor substrate is ground and the peripheral portion of the back surface side is chamfered. And a method for grinding a semiconductor substrate. 5. A stage for fixing and rotating a semiconductor substrate, and a grindstone attached to the surface of a support on a disk. The grinding face of the semiconductor substrate is ground by rotating in parallel with the stage. A grinding device configured to grind in a state in which the stage or the grinding member is tilted. 6. A method of manufacturing a semiconductor device, comprising the method of grinding a semiconductor substrate according to claim 1.