JPS63155751A - Insulating substrate for semiconductor device - Google Patents

Abstract

PURPOSE: To maintain sufficiently high insulation and, moreover, eliminate electric short-circuit between wirings caused by aluminum migration by a method wherein an insulating layer which is formed directly on a silicon substrate and composed of an aluminum oxide film is provided. CONSTITUTION:An aluminum oxide film 2 is formed as an insulating layer on the surface of a silicon substrate 1 by a sputtering method to form an insulating substrate. Aluminum wiring layers 3 of 3 mum thickness are formed on the aluminum oxide film 2 of the insulating substrate by an ion plating method with a metal mask. Further, a semiconductor element 4 is mounted on the aluminum oxide film 2 at a required position with silver paste 5 and electrodes of the semiconductor element 4 are connected to the aluminum wiring layers 3 by aluminum wires 6 to form a thin film micromodule. Therefore, as the film made of aluminum oxide which is stable and highly insulating compound is employed as the insulating layer on the silicon substrate, the aluminum migration from the aluminum wirings can be restricted and electric short-circuit between aluminum wirings can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an insulating substrate for a semiconductor device in which an insulating layer is formed on a silicon substrate.

[Conventional technology]

Currently, insulating substrates in which a silicon dioxide film or a silicon nitride film is formed as an insulating layer on a silicon substrate are generally used as substrates for thin film micromodules, thin film fundensor arrays, thin film resistor arrays, and the like.

The reason why silicon substrates are used as such insulating substrates is that due to advances in silicon wafer manufacturing technology, silicon substrates with no surface defects, excellent smoothness, and high surface cleanliness can now be obtained at low cost. Here are some things that have happened.

Further, with regard to insulating the surface of a silicon substrate, advances in semiconductor device manufacturing technology have made it easier to form an insulator layer. That is, the silicon dioxide film is formed by, for example, an anodic oxidation method in an oxidizing solution, a thermal oxidation method using oxygen plasma, or the like. The silicon nitride film is formed by a chemical vapor deposition method using silane and ammonia, a thermal nitriding method using ammonia, or the like.

On the surface of the insulator layer of the silicon substrate on which the insulator layer of silicon dioxide or silicon nitride has been formed in this way, a wiring layer of gold or aluminum is formed, and then a semiconductor element is mounted.
Further, a semiconductor device such as a thin film micro module is constructed by internally connecting with bonding wires made of aluminum or the like. Further, thin film passive elements made of Ta2O or the like with gold or aluminum electrodes are directly formed on the surface of the insulating layer of this silicon substrate to form a thin film fundensor array or a thin film resistor array.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional insulating substrate, since the insulating layer is a silicon dioxide film or a silicon nitride film, sufficient insulation cannot be ensured, and in particular, the insulation resistance 10 required for mounting a power device. Ω or more” 2 and dielectric breakdown voltage 2
It was not possible to satisfy the insulation property of 00 V or more. There have also been attempts to increase the thickness of the silicon dioxide film or silicon nitride film in order to improve insulation, but as the thickness increases, cranks are more likely to occur in the film due to increased internal stress, making it difficult to put it into practical use. It was Zheng.

Furthermore, recently aluminum, which has excellent bonding properties, is increasingly being used as a material for wiring layers.
When a high voltage is applied between these aluminum wires, the aluminum of the wires migrates on the surface or inside of the silicon dioxide film or silicon nitride film, causing an electrical short circuit between the wires.0 In view of the above-mentioned conventional problems, the present invention has been devised to ensure sufficiently high insulation properties as an insulating substrate used in thin-film micromodules, etc., which have become increasingly dense and high-output in recent years, and also to provide insulation between wiring lines due to aluminum migration. The object of the present invention is to provide an insulating substrate for semiconductor devices that can prevent electrical short circuits.

[Means for solving problems]

The insulating substrate for a semiconductor device of the present invention is characterized by having an insulating layer made of a 1 cum aluminum oxide film formed directly on a silicon substrate.

Aluminum oxide<Ato) film with silicon (Si)
For forming thin film on the substrate surface, conventional thin film forming methods such as vapor deposition and sputtering methods that are already known can be used, but it is possible to obtain good adhesion to the substrate by ionizing the vaporized raw material. Ion processes such as sputtering and ion blating are preferred.

[Effect]

In the insulating substrate of the present invention, the silicon substrate ff(3)
', L) Since the insulator layer on the surface is made of aluminum oxide,
As an insulator layer, it is thermally and chemically stable, and even when deposited, it has a homogeneous structure.
An insulator layer satisfying high insulation properties with Ω or more and dielectric breakdown voltage of 200V or more can be obtained.

The thickness of the aluminum oxide film is 1x104x to 5x1.
A range of 0A is preferable; if the film thickness is less than 1XloA, it is difficult to stably obtain the above-mentioned high insulation properties;
This is because if it exceeds 0 A, the film formation cost increases and the internal stress of the film increases, making it easy for cracks to occur in the film.

Even when a wiring layer is formed using aluminum or an aluminum alloy, the bonding properties at the interface between the wiring layer and the insulating layer are good because the wiring layer is directly under an insulating layer made of aluminum oxide, which is the same aluminum compound. The aluminum of the wiring layer does not migrate on the surface or inside of the insulator layer, and electrical short circuits between aluminum wirings can be prevented, making it possible to mount high-output devices and conduct high-density wiring.

〔Example〕

A specific example of the present invention will be explained with reference to the drawings.

An insulating layer is formed on the surface of a silicon substrate 1 cut out from a silicon wafer to a thickness of 5.5 mm by sputtering.
An insulating substrate was manufactured by forming an aluminum oxide film 2 of oxxo, (.The insulation resistance in the thickness direction of this aluminum oxide film 2 was 1.8×10 Ω, and the dielectric breakdown voltage was 34
It was 0v.

An aluminum wiring layer 3 having a thickness of 3 μm was formed on the aluminum oxide film 2 of this insulating substrate by the ion blasting method using a metal mask.

Furthermore, a semiconductor element 4 is mounted on a predetermined position on the aluminum oxide film 2 using a silver paste 5, and the electrodes of the semiconductor element 4 and the aluminum wiring layer 3 are internally connected with an aluminum wire 6 to form a thin film micro as shown in the drawing. Manufactured the module.

(Effects of the Invention) According to the present invention, since aluminum oxide, which is a stable and highly insulating compound, is used as the second insulating layer of the silicon substrate, it can provide sufficient insulation for mounting power devices even though it is a thin insulating layer. Resistance 1 o 12 Ω or more and breakdown voltage 200 V
It is possible to provide an insulating substrate for semiconductor devices having the above-mentioned high insulation properties.

In addition, the aluminum oxide insulator layer suppresses the migration of aluminum from the aluminum interconnect layer, so there is a possibility that the aluminum oxide insulator layer will inhibit the migration of aluminum from the aluminum interconnect layer. High-density wiring is possible with short-circuits and total short-circuits of If%.

The insulating substrate for semiconductor devices of the present invention is particularly effective for thin film micromodules, thin film passive element arrays, etc., which are becoming increasingly denser and more output.

[Brief explanation of the drawing]

The drawing is a sectional view showing a specific example of a thin film micromodule using the insulating substrate for semiconductor devices of the present invention. 1. Silicon substrate 2. Aluminum oxide film 3.
Aluminum wiring layer 4...Semiconductor element 5...Silver paste 6...Aluminum wire 4 Oxide element

Claims (2)

[Claims] (1) An insulating substrate for a semiconductor device characterized by having an insulating layer made of an aluminum oxide film formed directly on a silicon substrate. (2) The thickness of the aluminum oxide film is 1×10^4 Å to 5
The insulating substrate for a semiconductor device according to claim (1), characterized in that the thickness is ×10^5 Å.