JPH0342507B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a large number of semiconductor pellets from a semiconductor wafer. BACKGROUND ART When manufacturing semiconductor devices such as transistors and diodes, as shown in FIG. , each semiconductor element 2 is cut and separated to produce a large number of semiconductor pellets. Here, the surface metal layer 3 is independent for each semiconductor element 2, but
The metal layer 4 on the back surface is formed uniformly and is often continuous. Moreover, when cutting between the semiconductor elements 2, 2, a dicing method is generally used in many cases. However, if the metal layer 4 on the back side is made of soft material such as silver, if an attempt is made to completely cut it with a dicing saw, the soft silver will clog the dicing blade, making dicing impossible. Therefore, as shown in FIG. 2, an adhesive tape 5 is pasted on the back surface of the semiconductor wafer 1.
After forming the dicing groove 6 with a predetermined remaining margin t from the surface, a bending force is applied to the semiconductor wafer 1 to break it 7 from the dicing groove 6 portion as shown in FIG. Through this process, a large number of semiconductor pellets are manufactured. However, if the semiconductor element 2 is small with dimensions of 1 mm□ or less, it is impossible to apply a large bending force to the semiconductor wafer 1, and the metal layer 4 on the back side is soft, so it is difficult to brake reliably. Therefore, a so-called average defect, in which a plurality of semiconductor pellets become connected by the metal layer 4, is likely to occur.

Therefore, after forming an insulating film along the scribe line of the semiconductor wafer and forming a solder layer over the entire surface, the solder layer is heated and melted, and the cohesive force of the molten solder is used to bind the solder layer on the insulating film. A method has been proposed in which the insulating film is brought into a continuous state and then immersed in a chemical that dissolves and removes the insulating film, thereby removing the insulating film together with the solder layer thereon (Japanese Patent Application Laid-Open No. 58862/1983).

However, this method has the problem that not only is it necessary to dissolve and remove the insulating film using chemicals, but also cleaning and removal of chemicals and drying steps are required, making the process complicated. DISCLOSURE OF THE INVENTION [Purpose] The present invention provides a method for reducing average defects without removing the insulating film as described above even when the dimensions of the semiconductor element are small and the metal layer on the back surface is made of a soft material such as silver. The purpose of the present invention is to provide a method for manufacturing a semiconductor device.

〔composition〕

This invention includes a process of forming a large number of semiconductor elements on a semiconductor wafer, a process of forming an insulating film at a position corresponding to each semiconductor element on the back surface of the semiconductor wafer, and a process of forming a soft metal layer on the entire back surface of the semiconductor wafer. By applying adhesive tape to the back side of the semiconductor wafer and then peeling it off, the metal layer on the insulating film is removed by utilizing the difference in adhesive strength between the metal layer and the semiconductor material and the insulating film. This method is characterized by including a step of forming a soft metal layer in a region other than the film forming portion, and a step of dicing the semiconductor wafer from a position corresponding to the insulating film.

〔effect〕

Since this invention has a hard insulating film on the back surface of the semiconductor wafer at a position corresponding to dicing, when the semiconductor wafer is half-cut and braked, the insulating film is reliably broken, and the semiconductor wafer can be completely cut by the dicing method. Even when cutting, dicing can be performed reliably without clogging the dicing blade. Moreover, since the insulating film is not removed by dissolving it with chemicals, subsequent cleaning and drying can be omitted, which not only simplifies manufacturing, but also saves on materials and utility costs, leading to lower costs. . Furthermore, by leaving an insulating film, it is possible to actively utilize this insulating film to create an optimal soldering pressure that is resistant to heat cycles between the semiconductor pellet and a heat sink such as a lead frame or stem. can be ensured. DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

4 to 9 show cross-sectional views of a semiconductor wafer at various stages of the method according to the invention.

First, an N ⁺ N ^- semiconductor wafer 1 is prepared, insulating films 8 and 9 such as oxide films are formed on both the front and back surfaces, a window hole is formed only in the insulating film 8 on the front side, and P is formed in the N ^- type region. A large number of semiconductor elements 2 are formed by selectively diffusing type impurities to form P-type regions (fourth
figure).

Next, by a well-known photo-etching method, windows 10 for ohmic contact are formed in the insulating film 8 on the front side, and the insulating film 9 on the back side is formed only at positions corresponding to between the semiconductor elements 2, 2. (5th
figure).

Subsequently, gold is vapor-deposited on the entire surface including the insulating film 8 on the front surface and the window hole 10 to form the metal layer 3, and gold is vapor-deposited on the entire surface including the insulating film 9 on the back surface to form the gold layer 4a. The metal layer 4 is formed by depositing silver on the gold layer 4a and laminating the silver layer 4b (FIG. 6).

Next, by pasting adhesive tape on both the front and back sides of the semiconductor wafer 1 and peeling it off, the metal layer 3
The metal layer 3 on the insulating films 8 and 9 is then
Then, the gold layer 4a is peeled off and the window hole 1 of the insulating film 8 is removed.
Metal layers 3 and 4 are formed between 0 and insulating films 9, 9 (FIG. 7).

Further, an adhesive tape 5 is pasted on the back side of the semiconductor wafer 1, and each semiconductor element 2, 2 is attached from the front side.
The intermediate portion is diced to form a dicing groove 6 with a remaining margin of approximately 60 to 80 μm (FIG. 8).

This semiconductor wafer 1 is placed face down on a rubber plate, etc., and a steel roller (not shown) is rolled over the adhesive tape 5 to apply a bending force to the semiconductor wafer 1, thereby forming a dicing groove. A break 11 is caused from the bottom of the semiconductor element 6 to the insulating film 9 on the back surface, and each semiconductor element 2 is separated (FIG. 9).

According to the above manufacturing method, the dicing groove 6
Since the hard insulating film 9 is formed on the back surface corresponding to the insulating film 9, the insulating film 9 is easily and reliably broken during braking, and no abnormality occurs.

In the above embodiment, the case where the semiconductor wafer 1 is half-cut with a predetermined remaining margin and then braked is performed, but it is also possible to completely cut the semiconductor wafer 1 including the insulating film 9 portion. In this case, since the insulating film 9 is hard, the dicing saw will not become clogged and can be easily and reliably completely cut.

[Brief explanation of drawings]

1 to 3 are cross-sectional views of a semiconductor wafer at various stages for explaining the conventional method. 4 to 9 are cross-sectional views of semiconductor wafers at various stages for explaining the method according to the present invention. 1... Semiconductor wafer, 2... Semiconductor element,
3, 4... Metal layer, 5... Adhesive tape, 6... Dicing groove, 8, 9... Insulating film, 11... Broken part.

Claims (1)

[Claims] 1. A step of forming a large number of semiconductor elements on a semiconductor wafer, a step of forming an insulating film at a position corresponding to each semiconductor element on the back surface of the semiconductor wafer, and a step of forming a soft metal over the entire back surface of the semiconductor wafer. The process involves forming a layer, and by applying an adhesive tape to the back surface of the semiconductor wafer and then peeling it off, the insulation is formed by utilizing the difference between the adhesive strength of the soft metal layer to the semiconductor material and the adhesive strength to the insulating film. A method for manufacturing a semiconductor device, comprising: removing a soft metal layer on a film and forming a soft metal layer in a region other than a portion where an insulating film is to be formed; and dicing a semiconductor wafer from a position corresponding to the insulating film.