JP2895328B2 - Semiconductor device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device. More specifically, the present invention relates to a method for manufacturing a semiconductor device which effectively removes or reduces burrs generated when cutting and separating each semiconductor chip from a semiconductor wafer.

[0002]

2. Description of the Related Art A semiconductor device is manufactured by forming a semiconductor circuit on a semiconductor substrate, and a large number of the same semiconductor device on which the same circuit is formed is used. Therefore, usually, a large number of identical semiconductor circuits are formed on a semiconductor wafer, and thereafter, the semiconductor wafer is diced into squares and cut and separated into semiconductor chips. Among these semiconductor devices, a semiconductor device in which a metal film for an electrode is formed on the entire back surface of a semiconductor substrate or the like is formed by forming a semiconductor circuit such as a pn junction in the state of a semiconductor wafer, and then performing an evaporation method on the entire surface. Such as Ni,
A metal film made of Ag or the like is formed. In this state, the semiconductor wafer is attached to a vinyl sheet or the like, and cut into individual semiconductor chips with a diamond cutter.

FIG. 2 shows an example of a semiconductor chip formed as described above. In FIG. 2, (a) is a cross-sectional explanatory view of a mesa diode, wherein 1 is, for example, an n ⁺ type semiconductor substrate, 1a is an n ⁻ type semiconductor crystal layer, and 2 is a p ⁺ type semiconductor crystal layer. A pn junction surface 3 is formed between the semiconductor crystal layers 1a and 2. In order to maintain the insulating characteristics of the exposed portion of the pn junction surface 3, the shoulder is etched in a mesa shape and a glass passivation film 4 is formed on the inclined portion. Further, metal films 5 and 6 made of Ni, Ag or the like are formed on the front surface of the p ⁺ type semiconductor crystal layer 2 and the back surface of the n ⁺ type semiconductor substrate 1, respectively, and cut and separated from the semiconductor wafer to form a mesa diode chip. Is formed.

FIG. 2B is a cross-sectional view illustrating a planar diode. Although the same portions as those of the mesa type diode in FIG. 2A are denoted by the same reference numerals, the planar type diode does not have an inclined portion formed on the shoulder, and a protective film 17 such as SiO ₂ is formed on the surface. The pn junction surface 3 and the two electrode films 5 and 6 are formed in the state of a semiconductor wafer, and are cut and separated by a diamond cutter or the like, except that the upper electrode 15 is formed by removing the portion. This is the same in that a semiconductor chip as shown in FIG.

In cutting and separating each semiconductor chip from the semiconductor wafer, the semiconductor wafer is attached to a vinyl sheet or the like, and is completely cut to the back surface of the semiconductor wafer by a diamond cutter or the like, or is completely cut to the back surface. There is a method of half dicing that leaves a little and does not split later. However, since the metal films 5 and 6 for electrodes provided on the front surface or the back surface of the wafer are rich in malleability and ductility, burrs are embedded in the adhered vinyl sheet even after full dicing. Further, even in the case of half dicing, the metal films 5 and 6 are hard to be broken, and the cracks are irregular, and burrs are generated.

[0006] Such burrs will cause poor characteristics such as insufficient adhesion to the lead frame and poor contact with the heat sink in a later process of assembling the semiconductor chip. No. Conventionally, in order to remove such burrs, etching has been performed after dicing.

[0007]

The conventional deburring method is as follows.
Since the entire semiconductor chip is immersed and dissolved in an etching solution, the metal film portion other than the burrs is also melted and thinned. Since the thickness of the metal film is usually about 2 to 8 μm and the length of the burr is about 30 to 40 μm, if the etching is performed until the burr becomes about 20 to 30 μm, the metal film portion also becomes thin to about 3 μm. Since this etching is performed together with a semiconductor chip having almost no burrs, the metal films of all the semiconductor devices are thinned.

As a result, loose (open) defects occur after assembling to a lead frame or the like, and in the case of solder assembling, the metal is diffused into the solder and the metal film is peeled off. For this reason, there is a problem that the yield is reduced due to the disconnection failure and the reliability is reduced.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and effectively removes or reduces burrs generated after cutting a semiconductor chip.
It is an object of the present invention to provide a method of manufacturing a semiconductor device in which a metal film for an electrode is not reduced at all, a disconnection failure is eliminated, and reliability is improved.

[0010]

A method of manufacturing a semiconductor device according to the present invention comprises the steps of (a) forming a plurality of identical semiconductor circuits on a semiconductor wafer and forming a metal film for an electrode on at least one surface side of the semiconductor wafer; (B) dicing the semiconductor wafer to cut and separate into semiconductor chips for each of the same semiconductor circuits, and (c) putting the separated semiconductor chips together with rubber pieces into a container and rotating the same with a turntable to cut the semiconductor chips. (D) separating and cleaning the semiconductor chip from the rubber piece.

[0011]

According to the present invention, after the semiconductor chip is cut into pieces, the semiconductor chip is mixed with a rubber piece, placed in a container, and rotated, so that the rubber piece and the semiconductor chip are rubbed with each other, and particularly protrude like burrs. The rubbed part is scraped off with a piece of rubber. In addition, since the semiconductor chip is rubbed with a rubber piece, the flat portion of the semiconductor chip is not damaged, and the metal film of the semiconductor chip and other semiconductor substrates are not affected at all. Therefore, only burrs can be effectively removed or reduced.

[0012]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory view of a step of removing burrs according to one embodiment of the present invention.

As described in the conventional example, a large number of identical semiconductor circuits are formed in a matrix on a semiconductor wafer, a metal film for electrodes made of Ag or Ni having a thickness of 2 to 8 μm is provided, and a vinyl sheet is formed. To each semiconductor chip (for example, 0.3 to 1.
3 mm × 0.3 to 1.3 mm). Dicing may be full auto dicing or half dicing.

About 5% of the semiconductor chips cut and separated in this way have burrs of 30 to 40 μm at the cut portions of the metal film. The semiconductor chip and the rubber piece are mixed into a pot carrier, which is a container made of polyethylene or polyester (see FIG. 1A). 100,000 semiconductor chips
Approximately 3 million pieces, the size of the rubber piece is 1/1 to 10 times the size of the semiconductor chip, and the amount is 1
About 5 times, the shape is cubic or rectangular parallelepiped, and the hardness varies depending on the metal film material. For example, ASTM D
According to 2240 Shore A, 30-70 for Ag material,
In the case of Ni material, it is preferably about 30 to 40. The stirring container is a deburring container made of polyethylene or polyester, for example, a pot carrier for stirring is used.

Next, the pot carrier 3 on which the semiconductor chip 1 and the rubber piece 2 are mixed is placed on the turntable 4 and the number of rotations is 50.
Spin at ~ 200 rpm for 1 minute to 1 hour.

Next, the pot carrier 3 is lowered from the turntable 4 and the semiconductor chip 1 and the rubber piece 2 are separated. This separation can be easily achieved by passing through a mesh. After that, by cleaning the semiconductor chip 1 with an organic solvent, large burrs are removed or a clean semiconductor chip reduced to small burrs of 20 μm or less can be obtained. The semiconductor device is completed by bonding this semiconductor chip to a lead frame or enclosing it in a glass tube together with a heat sink.

In the state of a semiconductor chip cut and separated by dicing from a semiconductor wafer, burrs of 30 to 40 μm are generated, and the rate of characteristic failure such as bonding failure is about 5%. But 2
%, But according to the present invention, the size of the burrs is 20 μm or less, and the defect rate due to burrs is 0.5%.
%, And the metal film and the semiconductor substrate, which are the electrodes, are not damaged at all. Therefore, there is no failure due to long-time use, and the reliability has been greatly improved. Was about 5%).

[0018]

According to the present invention, since burrs generated by dicing a semiconductor wafer having a metal film on at least one surface are removed by rubbing with a rubber piece, only the burrs are scraped off, and the metal on the electrode portion is removed. The membrane is not damaged at all.

As a result, the yield of bonding of the semiconductor chip is improved, the reliability of the semiconductor device is greatly improved, and the deburring man-hour is only required to be mixed in the deburring container and mounted on the turntable. There is an effect that it does not increase and can be reduced in cost as compared with the conventional etching.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a deburring step as an example of a method for manufacturing a semiconductor device of the present invention.

FIG. 2 is an explanatory cross-sectional view of a semiconductor chip showing burrs generated on the semiconductor chip by a conventional method of manufacturing a semiconductor device.

[Explanation of symbols]

 Reference Signs List 1 semiconductor chip 2 rubber piece 3 pot carrier

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/304 H01L 21/301

Claims (1)

(57) [Claims] (A) forming a plurality of identical semiconductor circuits on a semiconductor wafer and forming a metal film for an electrode on at least one surface side of the semiconductor wafer; and (b) dicing the semiconductor wafer into the same semiconductor circuit. (C) putting the separated semiconductor chip together with a rubber piece into a container and rotating it on a turntable to remove or reduce burrs at the cut part; A method of manufacturing a semiconductor device, wherein a chip is separated from a rubber piece and washed.