JPS59129282A - Heat-resistant adhesive sheet - Google Patents

Abstract

PURPOSE:To provide a heat-resistant adhesive sheet having uniform thickness, excellent sag resistance and alpha-ray screening effect and suitable for surface protection of highly integrated semiconductor circuit, etc., prepared by forming a silicone adhesive layer on a polyimide base film. CONSTITUTION:The adhesive sheet is a composite material of the total thickness of at least 30mum prepared by forming a silicone adhesive layer 20 on a polyimide base film 10. The adhesive sheet is applied to a semiconductor circuit 30 to protect it against alpha-ray emitted from a trace of radioactive substance (e.g. uranium or thorium) contained in screening material, etc. The method makes it possible to form an alpha-ray screening film in a shorter period of time with a higher efficiency of operation than the process in which a heat-resistant coating in solution is applied, followed by curing. In addition, the film (50) can be readily formed on a certain limited area only of the semiconductor circuit (30).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-resistant adhesive sheet that is used by being laminated onto the surface of a highly integrated semiconductor circuit.

In recent years, as semiconductor circuits have become more highly integrated, small amounts of radioactive substances such as uranium and T are contained in their sealants.
Alpha rays are emitted from thorium (h), which causes temporary malfunctions in semiconductor memories. Currently, as a method for mining semiconductor circuits from this alpha ray, a method called a so-called solution method or wet method is generally used, in which heat-resistant resin paint such as polyimide-based or silicone-based paint is coated on the semiconductor circuit in a solution state. .

However, this method requires temperature and time for curing after coating with a solution paint, which is also a cause of a significant decrease in productivity in semiconductor manufacturing. However, as shown in FIG. 1, the resulting resin film is extremely inconsistent in thickness.

In the figure, 1 is a semiconductor chinograph, and 2 is an α-ray shielding film obtained by coating. Here, there is a close proportional relationship between the thickness of the resin film provided on the semiconductor and the α-ray shielding effect, as shown in FIG.

That is, in order to shield alpha rays, a film thickness of 30μ or more, preferably 75μ or more is required, and in order to provide this thickness at parts a and 0 in FIG. The thickness must be set several times that amount. Still, there is a problem that occurs when such a thick coating is applied, as shown in Figure 3, "sagging" of the resin paint.This is the case in parts d and e in Figure 3, and this problem will be solved later. The viscosity of the resin paint decreases during the heat curing process, which results in a further increase in the viscosity of the resin paint.

The present invention has been made in view of the above circumstances, and provides a dry α-ray shielding film using an adhesive sheet instead of a coating.

That is, the present invention provides a heat-resistant composite material having a total thickness of at least 30 microns or more, which is a composite material in which a silicone adhesive layer is provided on a polyimide film base layer, and is used by laminating it on the surface of a highly integrated semiconductor circuit. The present invention will be described in detail below with reference to the drawings.

FIG. 4 is a cross-sectional view of a heat-resistant adhesive sheet according to the present invention laminated onto a semiconductor chip, in which 10 represents a polyimide film base material, 2o represents a silicone adhesive layer, and 30 represents a semiconductor chip.

FIG. 5 is a plan view of 9 adhesive sheets of the present invention pasted together. In the figure, 50 represents the adhesive sheet of the present invention, and 30 represents a semiconductor chip.

According to the adhesive sheet of the present invention, α can be applied only to the necessary parts of the semiconductor.
A line shielding film can be provided, and the adhesive sheet can be attached at any step in the semiconductor manufacturing process from after circuit formation to before packaging.

In addition, there is no problem of "thickness unevenness" of the shielding film and "sagging" of the resin paint as in the above-mentioned wet method, and there is no need for the heating process and the time required for curing the shielding film.

Furthermore, the composite of the polyimide fill base material and the Noricone adhesive according to the present invention not only has excellent heat resistance and α-ray prevention effect, but also has good processability and is extremely practical.

[Brief explanation of the drawing]

Figure 1 is a schematic side view of a conventional α-ray shielding film (layer) provided on a semiconductor chip, Figure 2 is a relationship between the thickness of the α-ray shielding film and the amount of α-ray transmission, and Figure 3 is a diagram showing the relationship between the thickness of the α-ray shielding film and the amount of α-ray transmission. FIG. 4 is a schematic cross-sectional view of the case where the heat-resistant adhesive sheet for α-ray shielding of the present invention is provided on a semiconductor chip; FIG.
The figure is a plan view thereof. 1.30...Semiconductor chip, 2...α-ray shielding film provided by coating, 10...Polyimide film base material, 20...Silicone adhesive layer. Patent Applicant Tomoekawa Paper Mills Co., Ltd. No. 11 Sword No. 21” No. +14 Gun No. Da 17

Claims (1)

[Claims] 7. A heat-resistant adhesive sheet used by laminating onto the surface of a highly integrated semiconductor circuit, characterized in that it is a composite material having a silicone adhesive layer on a polyimide film base material and having a total thickness of at least 30 μm. .