JP2932278B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device including a step of cutting a semiconductor substrate into individual semiconductor chips by using a dicing blade.

[Related Art] As a pre-process of manufacturing a predetermined semiconductor device, there is a process of forming a PN junction on a semiconductor substrate and then dividing the semiconductor device into a predetermined size to obtain a semiconductor chip. There are various methods for dividing the semiconductor chip into individual semiconductor chips. As a typical method, there is a method shown in FIG. 3 and FIG. Although the dividing method shown in these figures is a method of dividing a diode chip, a similar method is implemented in other element chips such as a thyristor.

In the figure, after forming a PN junction 2 in a semiconductor substrate 1,
An anode electrode metal layer 3 is formed on the upper surface and a cathode electrode metal layer 4 is formed on the lower surface. As the above-mentioned anode electrode metal layer 3, a metal such as Ti-Ni-Au, Ni-Al is used, and as the cathode electrode metal layer 4, a metal such as Ni-Au, Cr-Ag, Ti-Ni-Au is used. in use.

After the formation of the anode electrode metal layer 3 and the cathode electrode metal layer 4, as shown in FIG. 3, a paste tape 5 is attached to the cathode electrode metal layer 4 side.

Next, rotate a dicing blade (not shown)
A cutting groove 6 is formed at a predetermined position.
The depth of the cutting groove 6 is approximately 1 / of the thickness of the semiconductor substrate 1.
Then, it is curved together with the glue tape 5 and is broken from the cutting groove 6. At this time, the fractured surface 7 is often broken along the crystal axis of the semiconductor substrate 1 as shown by a dotted line in FIG.

FIG. 4 shows another division method. In this division method, after the adhesive tape 5 is attached to the semiconductor substrate 1, the dicing blade is used to completely cut the semiconductor substrate 1 to the back surface.

[Problems to be Solved by the Invention] In the conventional method for dividing a semiconductor substrate shown in FIG. 3, since the fracture surface 7 is generally inclined, the center of the upper surface and the center of the lower surface of the semiconductor chip are shifted, The center cannot be reliably determined for positioning and fixing the semiconductor chip to another member in the next step. This has a greater effect as the dimensions of the semiconductor chip become smaller. In addition, in the conventional method of dividing a semiconductor substrate shown in FIG. 4, in order to eliminate the above-mentioned drawback, a dicing blade is used to completely cut the semiconductor substrate up to the back surface. Although this cutting method can be dimensionally divided into predetermined sizes, another problem arises. That is, in this method, when the dicing blade is rotated at a high speed to advance from the upper surface to the lower surface of the semiconductor substrate 1 and cut, at the peripheral edge of the lower end of the cutting groove 6 of the cathode electrode metal layer 4 on the rear surface side, The metal forming the cathode electrode metal layer 4 is separated from the semiconductor substrate 1.

FIG. 5 is a plan view of the semiconductor chip 8 showing this state. The peripheral portion 4a is peeled off, and only the hatched portion at the center becomes the electrode metal portion.

In such a case, when the size of the semiconductor chip 8 is large, the electrode metal portion is larger than the peeled portion in terms of the area ratio, so that the effect is not so large, but the size of the semiconductor chip 8 is small. Then, the area of the peeled portion becomes relatively large, which has a great influence. That is, in order to fix the electrode metal portion to another member by soldering, if the area is reduced, the adhesive strength is affected.

Therefore, as a countermeasure, a method of forming an uneven surface by sandblasting the surface of the semiconductor substrate 1 to increase the adhesion of the electrode metal has been adopted, but it has not been sufficient yet.

[Object of the Invention] The present invention has been made in order to solve the above-described problems, and when a semiconductor substrate is cut using a dicing blade, a peeled portion is formed on an electrode metal at a peripheral portion of each semiconductor chip. It is an object of the present invention to provide a method of manufacturing a semiconductor device which hardly causes the semiconductor device.

[Means for Solving the Problems] In a method of manufacturing a semiconductor device, the method includes a step of completely cutting a semiconductor substrate having both main surfaces from one main surface to another main surface with a dicing blade to obtain a semiconductor chip. A three-layer metal layer is formed on at least the other main surface of the semiconductor substrate, and among the three-layer metal layers, a first metal layer that is in contact with the semiconductor substrate is formed more than a second metal layer and a third metal layer. The method is characterized in that the method includes a step of forming the semiconductor substrate into a semiconductor chip by the dicing blade by using a soft metal.

[Operation] In the method of manufacturing a semiconductor device according to the present invention, a multilayer metal layer is formed on the other main surface side of a semiconductor substrate, and a first metal layer in contact with the semiconductor substrate is formed of aluminum metal. Since the soft metal layer such as a layer and the second layer are made of a metal harder than the metal layer of the first layer, the mechanical stress generated when each semiconductor chip is cut using a dicing blade is subjected to the above-mentioned soft metal layer. It can be absorbed by a certain first layer. Therefore, a peeled portion is hardly formed on the peripheral portion of each semiconductor chip.

Example An example of the present invention will be described below with reference to the drawings.

In FIG. 1, in a semiconductor substrate 1, as in the conventional case,
A PN junction 2 is formed, and an anode electrode metal layer 3 is formed on one main surface side. Then, a cathode electrode metal layer 40 is formed on the other main surface side of the semiconductor substrate 1, that is, on the lower surface in the drawing. The cathode electrode metal layer 40 has the following configuration in the present invention.

That is, in the conventional electrode metal layer, since the metal of the first layer is hard, the mechanical stress such as the pressing and vibration of the dicing blade causes the mechanical stress of the semiconductor substrate and the electrode when cut with the dicing blade. It is considered that it acted on the boundary with the metal and caused peeling.

Therefore, in the present invention, the first layer 41 is formed of a soft metal. In this embodiment, the first layer 41 is an A1 layer, and the second layer 42 thereon is a Ni layer, which is a metal harder than the first metal layer. Further, the third layer 43 thereon was an Au layer. Then, the third layer 43 was attached to the glued tape 5 and cut into individual semiconductor chips using a dicing blade.

FIG. 2 is a plan view showing one of the semiconductor chips 8 cut individually. As is apparent from this figure, according to the method of manufacturing a semiconductor device of the present invention, the semiconductor chip 8
The peeled portion is hardly seen in the peripheral edge portion 4a of FIG. 5, and the area of the hatched cathode electrode metal layer 4 can be increased. Since the first layer 41 of the cathode electrode metal layer 4 is formed of a soft metal such as an Al layer, the first layer 41 can absorb the mechanical stress caused by the dicing blade, and the semiconductor substrate 1 and the cathode electrode This is considered to be because the influence of the mechanical acting force on the boundary with the metal layer 4 can be reduced. Further, since the metal of the second layer is made harder than the metal of the first layer, the adhesion of the metal to the dicing blade can be reduced.

In the above embodiment, the first electrode layer 4
Although the layer is an Al layer, it is needless to say that various soft metals such as gold, silver, and alloys thereof can be used.

[Effects of the Invention] In the present invention, as the electrode metal layer formed on the other main surface side of the semiconductor substrate as described above, the first layer is formed of a soft metal, so that a dicing blade is used. When the semiconductor chip is cut into individual semiconductor chips, the first layer can absorb the mechanical stress caused by the dicing blade. Therefore, the peeled portion is hardly formed at the peripheral edge portion of the cut semiconductor chip, and the area of the central electrode metal portion can be increased. As a result, when the semiconductor chip is solder-fixed to another member, the shortage of the bonding area due to the shortage of the bonding area does not occur.
There is an excellent effect that a semiconductor device with a high yield can be finally manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor substrate for explaining a method of manufacturing a semiconductor device according to the present invention, FIG. 2 is a plan view showing one of the individual semiconductor chips obtained by the method of the present invention, and FIG.
FIG. 4 is a sectional view of a semiconductor substrate for explaining a conventional method of manufacturing a semiconductor device, and FIG. 5 is a plan view showing one of individual semiconductor chips obtained by the above-described conventional method. . DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate 2 ... PN junction part 3 ... Anode electrode metal layer 4,40 ... Cathode electrode layer 5 ... Glue tape 6 ... Cutting groove 7 ... Fracture surface 8 ... Semiconductor chip 41 ... 1st layer, 42 ... 2nd layer 43 ... 3rd layer

Claims (1)

(57) [Claims] 1. A method of manufacturing a semiconductor device, comprising the steps of: completely cutting a semiconductor substrate having both main surfaces from one main surface to another main surface with a dicing blade to obtain a semiconductor chip; A three-layer metal layer is formed on the other main surface, and among the three-layer metal layers, a first metal layer in contact with the semiconductor substrate is formed of a metal softer than the second and third metal layers. And a step of cutting the semiconductor substrate into semiconductor chips by the dicing blade.