JP2678479B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method of manufacturing a semiconductor device, and more particularly to improvement of a scribing process of a completed semiconductor wafer.

<Prior Art> In a conventional semiconductor wafer assembling process, gold is thickly deposited as a die bonding material on the back surface of the wafer. As a result, the wafer along the scribe line,
If it is half-cut, the chips after cutting are connected by gold in the later cracking process and cannot be divided well.

Therefore, the gold on the back surface of the wafer is patterned along the scribe line. That is, after depositing the back metal on the back surface of the wafer, a resist pattern is deposited on the back metal and the back metal is etched. Then, after removing the resist to expose the back metal, a predetermined heat treatment is performed.

That is, after exposing the back surface of the wafer along the scribe line, half-cutting and further cracking are performed.

The method of full-cutting the wafer from the surface and separating the chips is apt to cause the diamond cutter to be clogged with gold, resulting in a high cost.

The IC chip thus separated is then mounted on the base of the package. Then, by heating, a part of silicon and gold are melted to form an Au / Si eutectic alloy.

<Problems to be Solved by the Invention> However, in such a conventional semiconductor device manufacturing method, each step from resist application to peeling for etching after vapor deposition of the back metal and before heat treatment thereof is performed. However, in the resist stripping process, the back metal is also stripped off at the same time.

On the contrary, if the heat treatment for making ohmic contact with silicon is performed before etching after vapor deposition of this gold on the back surface of the wafer, the gold and silicon substrate react and etching is difficult and patterning cannot be performed well. Is.

Therefore, it is an object of the present invention to provide a method for manufacturing a semiconductor device which does not cause peeling of a back metal without increasing cost.

<Means for Solving the Problems> According to the present invention, a step of forming a groove along a scribe line on a back surface of a semiconductor wafer in which a plurality of chip portions are patterned, and the groove does not react with the semiconductor wafer and the back metal. A step of filling with a film of a material, a step of depositing the back metal on the back surface of the semiconductor wafer, a step of heating the back metal to react with the semiconductor wafer to alloy it, and a semiconductor filled in the groove A step of removing a film of a material that does not react with the wafer and the back metal to expose the back surface of the wafer along the scribe line; and a step of cutting the semiconductor wafer along the scribe line.
And a method for manufacturing a semiconductor device including the above.

<Operation> In the method of manufacturing a semiconductor device according to the present invention, first, a groove is formed along a scribe line on the back surface of a semiconductor wafer on which a plurality of chip portions are patterned. The depth of the groove and the method of forming the groove are appropriate.

Next, this groove is filled with a film of a material that does not react with the semiconductor wafer and the back metal, for example, an SOG film (hereinafter, in this section, the film of this material is simply referred to as an SOG film). The SOG film (spin-on glass film) is an inorganic SiO ₂ film formed by, for example, spin coating a solution in which silanol is dissolved in an organic solvent on the back surface of the wafer and then performing heat treatment. This SOG film does not deteriorate at a temperature of, for example, 400 ° C. during heat treatment, that is, it does not react with the silicon wafer and the back metal and is easily etched. Further, the SOG film is easy to apply. In this case, on the back side of the wafer
Other parts than the SOG film (scribe line) are exposed.

Next, a back metal (die bonding material) is deposited on the entire back surface of this semiconductor wafer. The back metal is gold, for example. Therefore, the back metal is also deposited on the SOG film to a predetermined thickness.

Next, the back metal is heated to react with the semiconductor wafer to alloy it. That is, in the portion where the back metal directly adheres to the back surface of the wafer, the back metal reacts with the wafer and alloys (Au / Si eutectic alloy). Therefore, the back metal of this portion cannot be easily peeled off by a normal process. However, the back metal deposited on the SOG film (SiO ₂ ) does not react with this SOG film and remains unalloyed. Further, the SOG film undergoes a large volume contraction upon heating, and the back metal not alloyed is depressed in the groove.

Further, the SOG film is removed to expose the back surface of the wafer along the scribe line. That is, not only the SOG film but also the unreacted portion of the back metal (in the gold state) is removed, and the groove on the back surface of the wafer is exposed along the scribe line. Unlike the alloy, the SOG film and the back metal can be easily removed by a normal etching process. For example, it can be easily removed with hydrofluoric acid.

Next, the semiconductor wafer is cut along the scribe line. For example, cutting or cutting from the wafer surface with a diamond saw. In this case, since the soft back metal is not attached to the front and back surfaces of the scribe line, it is possible to easily cut or cut.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.

1A to 1F are vertical cross-sectional views of the semiconductor device in each step for explaining the method of manufacturing the semiconductor device of the present invention. In these figures, the upper side is shown as the back surface of the wafer.

First, as shown in FIG. 1 (A), a plurality of chip parts
A semiconductor wafer 101 having a patterned 100 is prepared, and a groove 107 having a predetermined width and a predetermined depth is formed on a scribe line 105 on a back surface 103 of the wafer 101.

For example, after a photoresist having a predetermined thickness is deposited on the entire back surface 103 of the wafer, a groove 107 is formed along the scribe line 105 by using a predetermined etching process. The groove 10 is formed on the back surface 103 of the wafer along the scribe line 105.
In order to form 7, the alignment device above and below the wafer 101 may be used.

Next, as shown in FIG. 1 (B), the semiconductor wafer 10
The SOG film 111 is spin-coated on the back surface 103 of 1 and deposited to a predetermined thickness. The SOG film 111 fills the groove 107 and is deposited on the entire back surface 103 of the wafer.

Next, as shown in FIG. 1C, the back surface 103 of the wafer is polished or the like to remove the SOG film 111 by a predetermined thickness. As a result, each chip IC formation area 100
The back surface 103 of is exposed. Further, the SOG film 111 is formed in the groove 107.
Remains.

The SOG film 111 is formed of a substance that has not reacted with the back metal (die bonding material). For example, the silicon dioxide (SiO ₂ ) film 111 does not form a eutectic with gold which is the back metal even when heated at 400 ° C., for example.

Next, as shown in FIG. 1 (D), the semiconductor wafer 10
A back metal 113 is attached to the back surface 103 of 1. This back metal 113
For example, it is gold. The back metal 113 is deposited on the entire back surface 103 of the wafer. Therefore, the SOG film 111
The back metal 113 is also deposited on the top of the base metal to a predetermined thickness.

Next, as shown in FIG. 1 (E), the back metal 113 is heated and alloyed. As a result, in the portion 113A where the back metal 113 is directly adhered to the wafer back surface 103, the back metal 113A reacts with the silicon wafer 101 and alloys (Au / Si eutectic). However, the back metal 113B deposited on the SOG film 111 is
Gold (Au) that does not react with the SOG film 111 and does not alloy
Remains.

Further, the SOG film 111 causes the back metal 113B to be depressed in the groove 107 due to the volume contraction.

Further, as shown in FIG. 1 (F), the SOG film 111 in the trench 107 is removed using, for example, hydrofluoric acid. At this time, the unreacted portion 113B of the back metal 113 is also removed at the same time. That is, the bottom surface of the groove 107 is exposed, and thus the wafer back surface 103 is exposed along the scribe line 105.

Next, the semiconductor wafer 101 is cut along the scribe line 105 to form a groove at a predetermined depth from the surface.
For example, cutting with a diamond saw. In this case, since the soft back metal 113 is not applied to the scribe line portion 105 on the wafer back surface 103, the cutting can be easily performed.

In the half cut, after that, each chip 100 is separated by applying pressure with a roller while being stuck to the tape.

<Effect> As described above, according to the present invention, chips can be separated very easily. That is, it is possible to obtain a scribe process in which the back metal does not peel off without increasing the cost.

[Brief description of the drawings]

1 (A) to 1 (F) are vertical cross-sectional views of a semiconductor device showing respective steps according to an embodiment of a method for manufacturing a semiconductor device of the present invention. 100 …… chip, 101 …… wafer, 103 …… wafer backside, 105 …… scribe line, 107 …… groove, 111 …… SOG film (film of material that does not react with semiconductor wafer and back metal), 113 …… Back metal, 113B …… Alloyed back metal.

Claims (1)

(57) [Claims] 1. A step of forming a groove along a scribe line on the back surface of a semiconductor wafer having a plurality of chip portions patterned, and a step of filling the groove with a film of a material that does not react with the semiconductor wafer and the back metal. A step of depositing the back metal on the back surface of the semiconductor wafer, a step of heating the back metal to react with the semiconductor wafer to alloy it, and a material which does not react with the semiconductor wafer buried in the groove and the back metal. And a step of removing the film to expose the back surface of the wafer along the scribe line, and a step of cutting the semiconductor wafer along the scribe line. Manufacturing method.