JPS633456B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a beam lead type semiconductor device, and more particularly, to a beam lead type semiconductor device in which defective nitride film formed between a semiconductor substrate and a beam lead prevents poor contact between the two. .

Generally, the structure of a beam lead type semiconductor device is as shown in FIG. Elements are formed on the surface layer (lower surface side) of a semiconductor substrate 1, and an oxide film 2 is formed on the semiconductor substrate 1 during element formation and the like.
Then, on the oxide film 2, dirt from the outside, such as
An insulating film such as a nitride film 3 is formed to prevent deterioration of device characteristics from Na ions and the like. The thickness of the nitride film 3 is
It is around 1000Å. Then, wiring is formed on the nitride film 3. In the wiring formation, first, a base wiring of titanium, platinum, etc. is formed, and then a gold wiring 4 with a thickness of several μm is formed by gold plating or the like (hereinafter, this gold wiring will be referred to as a first gold wiring). Further, a gold wiring 5 having a thickness of several tens of micrometers is formed for the beam lead portion (hereinafter, this gold wiring will be referred to as a second gold wiring). When a beam lead type semiconductor device is assembled on a mounting board, the distance between the semiconductor substrate 1 and the beam lead part is very narrow due to mechanical pressure, which may cause poor contact. It is designed to be exposed to the outside.

Generally, the shape is such that the entire surface is exposed on the edge line of the semiconductor substrate 1 as shown in FIG. 2a, or only the beam lead portion is exposed as shown in FIG. 3a. At this time, the distance of the nitride film from the edge of the semiconductor substrate 1 is designed to be about several tens of micrometers, but because chemical etching is used to separate each element, the etching is not linear but wavy. In particular, when the element size is large and the number of beam leads increases, the nitride film 3 is exposed from the semiconductor substrate 1 for all beam lead parts, which further increases the variation.

Separation of each element is performed from the back surface (upper side in FIG. 1) of the semiconductor substrate 1 by adhering and fixing the elements to a quartz plate or the like and then chemically etching them. After that, the characteristics of each element are inspected to select only good elements.

When removing the element, melt the wax on the quartz plate and suck it up from side A in Figure 1 using a vacuum suction machine. Then, in order to remove the wax adhering to the element, an organic solvent is sprayed from the B side in FIG. 1 to clean it and complete the manufacturing.

The conventional drawbacks will be explained below.

As mentioned above, the thickness of the nitride film 3 is about 1000 Å, so the longer the distance of the nitride film 3 exposed outside the semiconductor substrate 1 during the wax cleaning, the larger the area that is hit by the organic solvent and the stronger the pressure. Therefore, the percentage of defects was large. For example, the structure in Figure 2a is like Figure 2b, and the structure in Figure 3a is like Figure 3b.
It becomes like this. If the device is assembled onto a mounting board with the nitride film 3 missing, the risk of contact between the semiconductor substrate 1 and the beam lead due to mechanical pressure during assembly increases, resulting in a serious quality problem. .

In the present invention, in order to eliminate the above-mentioned drawbacks, in order to prevent the organic solvent from directly hitting the nitride film during wax cleaning, an umbrella is provided in the umbrella-shaped inner area created by the formation of the first gold wiring and the second gold wiring on the side surface of the beam lead. The purpose of the present invention is to provide a beam lead type semiconductor device of high quality by forming a chemical film.

A feature of the present invention is that in a beam lead type semiconductor device, a nitride film formed between a semiconductor substrate and a beam lead is exposed to the outside from an edge of the semiconductor substrate at least in the beam lead extraction portion, and is shaped like an umbrella. On the side surface of the beam lead having a structure, a nitride film exposed from the edge of the semiconductor substrate is formed in an umbrella-shaped inner region of the side surface of the beam lead, and This is a beam lead type semiconductor device in which a recess is provided at the bottom of the nitride film exposed from the end.

Examples of the present invention will be described below.

FIG. 4 is a sectional view corresponding to the view from side C in FIG. 1, which shows the conventional structure (the structure of the nitride film is shown in FIG. 3), and FIG. 5 shows the embodiment of the present invention. Further, FIG. 6 is a view of the embodiment of the present invention corresponding to the view from side A in FIG. 1.

Since the second gold wiring formed on the first gold wiring 4 has a gold film thickness of more than 10 μm, it bulges in the lateral direction and has an umbrella-like structure. Therefore, a nitride film 3 that is exposed outside the semiconductor substrate 1 and is formed on the beam lead is formed in the inner region (distance E) of the umbrella-like structure of the beam lead, and a nitride film 3 is formed on the beam lead's extraction portion. 3 has a structure with a depression F.

If the structure of the nitride film 3 is made in this way, the nitride film 3 will be hidden behind the second gold wiring, and the organic solvent during the wax cleaning will not directly hit the nitride film 3. In addition, if the recess F is excessively etched due to variations in etching of the semiconductor substrate 1 for element isolation, the exposed area of the nitride film from one line of the semiconductor substrate other than the beam lead area will become large, and this will cause the area of the beam lead extraction area to become large. There is a risk of defects including the nitride film. However, by providing the depression F, the nitride film at the beam lead extraction portion is no longer affected. In other words, if the line of the nitride film other than the beam lead part is depressed and lowered to point F, there is a risk that the function of the internal elements will be impaired if the semiconductor substrate 1 is etched excessively. It is necessary to provide
This function is made possible by extending the nitride film line between the beam leads from the recess F, and it is possible to prevent etching of the semiconductor substrate 1 from proceeding beyond the recess F.

Also, the semiconductor substrate 1 of the nitride film 3 on the beam lead
If the distance exposed from the substrate is increased, there will be some margin for variations in etching, but it will also be necessary to increase the element size, so the structure of the present invention is considered to be optimal.

As explained above, if the nitride film is structured according to the present invention, defects in the nitride film will hardly occur, and contact between the semiconductor substrate and the beam lead will also be eliminated. This makes it possible to simplify the visual inspection, improve the yield, and bring about great effects in terms of manufacturing and reliability.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a typical beam-lead semiconductor device, and FIGS. 2a and 3a are parts of a conventional beam-lead semiconductor device viewed from the back side (side A in FIG. 1). The structure of the nitride film is shown, and FIGS. 2b and 3b show an example in which a part of the nitride film is missing. FIG. 4 is a cross-sectional view of a conventional beam lead type semiconductor device as seen from the lead side (C side in FIG. 1). 5 and 6 are embodiments of the present invention, the former being a sectional view seen from the same direction as FIG. 4, and the latter being a partial view of the beam lead section seen from the back side. In the figure, 1... semiconductor substrate, 2... oxide film, 3... nitride film, 4... first gold wiring, 5...
Second gold wiring, A, B, C...Indicates the direction with an explanation of the appearance, D...Distance of the nitride film extending outside the second gold wiring, E...Second gold wiring extending outside the first gold wiring This is the distance to the wiring.

Claims (1)

[Claims] 1. The nitride film formed between the semiconductor substrate and the beam lead is exposed to the outside from the edge of the semiconductor substrate at least in the beam lead extraction portion, and the nitride film is exposed on the side surface of the beam lead having an umbrella-like structure. A nitride film exposed from the edge of the semiconductor substrate is formed in an umbrella-shaped inner region on the side surface of the beam lead, and
A beam lead type semiconductor device, characterized in that a depression is provided in the bottom of the nitride film exposed from the edge of the semiconductor substrate at the beam lead extraction portion.