JPH0462838A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent an aluminum interconnection from being brought into contact with an N-type diffusion layer for increasing a surge resistance by installing a polycide interconnection and a contact window between the aluminum interconnection and the N-type diffusion layer in an input protection network, one of semiconductor devices. CONSTITUTION:This semiconductor device is constituted of a p-type semiconductor substrate 1, an N-type diffusion layer 2, an insulating layer 3, contact windows 4 and an aluminum interconnection 5. The structure is the same as conventional semiconductor devices. The difference of this semiconductor device from the conventional ones is a polycide interconnection (a two-layer-structured interconnection with polysilicon in the lower layer and high-melting point metal such as tungsten silicide WSix in the upper layer) 6. The polycide interconnection 6 is connected to the N-type diffusion layer through the lower contact windows 4 while it is connected to the aluminum interconnection 5 through the upper contact windows 4. The polycide interconnection 6 and the lower contact windows 4 can be made only by modifying a part of a layout pattern of a multilayer interconnection used in a densely integrated semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor device capable of improving the surge withstand voltage of an input protection circuit.

Conventional technology Traditionally, semiconductor devices have improved their voltage resistance against surges by using input protection circuits to protect internal circuits from excessive static electricity (hereinafter referred to as surges) that enters from external sources such as the human body or machinery. I'm letting you do it.

A conventional input protection circuit for a semiconductor device will be described below. FIG. 2 is a cross-sectional view of important parts of an input protection circuit of a conventional semiconductor device. An N-type diffusion layer 2 is formed on the top of a P-type semiconductor substrate 1 by ion implantation (to a depth of about 0.2 microns). The potential of the P-type semiconductor substrate 1 is set to zero or lower. An interlayer insulating film 3 containing silicon oxide as a main component is formed on the N-type diffusion layer 2 by chemical vapor deposition. A contact window 4 is formed in the interlayer insulating film 3 by etching, and connects the aluminum wiring 5 to the N-type diffusion layer 3.

Problems to be Solved by the Invention However, in the above conventional structure, the P-type semiconductor substrate 1
When a surge voltage higher than the reverse junction breakdown voltage (usually about 12 to 15 ports) is applied to the PN junction between the aluminum wire 5 and the N-type diffusion layer 2, an excessive current flows, the temperature near the PN junction rises, and the aluminum wiring 5 Aluminum melts when it reaches its melting point (660.4 degrees). In turn, the N-type diffusion layer 3 is destroyed,
The aluminum wiring 5 reaches the P-type semiconductor substrate 1, and the P
This causes the inconvenience that the N junction is destroyed and the number of battery leaks in the input protection circuit increases rapidly.

Means for Solving the Problems In order to achieve this object, the semiconductor device of the present invention has a poly->noid wiring (polygon in the lower layer) below the contact window connecting the aluminum wiring of the input protection circuit and the N-type diffusion layer. Silicon, upper layer tungsten silicide W S r
It has a two-layer wiring structure with a high melting point metal such as x) and a contact window.

Effect: This structure prevents aluminum from melting when a surge voltage is applied and direct reaction between the N-type diffusion layer and aluminum, which is suppressed by the polycide wiring. The withstand voltage against surge, which was conventionally determined by the melting point of aluminum, has been changed by the melting point of polycide wiring (the melting point of the underlying polysilicon layer, 1414
°C, the melting point of the upper layer tungsten silicide is 3387 °C)
You can move up to "ni".

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

FIG. 1 shows a cross-sectional view of important parts of an input protection circuit of a semiconductor device in an embodiment of the present invention. Note that 1 is a P-type semiconductor substrate, 2 is an N-type diffusion layer, 3 is an interlayer insulating film, and 4 is a P-type semiconductor substrate.
5 is a contact window, and 5 is an aluminum wiring, which are the same as those of the conventional example. 6 is polycide wiring (
Polysilicon on the bottom layer, tungsten silicide W on the top layer
It is a two-layer wiring structure with high melting point metals such as Si, etc.
It is connected to the N-type diffusion layer through the contact window 4, and also connected to the aluminum wiring 5 through the upper contact window 4. Note that the polycide wiring 6 and the lower contact window 4 can be formed by only partially changing the layout pattern of the multilayer wiring used in highly integrated semiconductor devices.

Effects of the Invention The semiconductor device input protection circuit of the present invention prevents contact between aluminum and the N-type diffusion layer by providing the polycide wiring 6 and the contact window 4 between the connection between the aluminum wiring 5 and the N-type diffusion layer 2. This has the effect of raising the critical temperature for failure of the PN junction due to melting of aluminum to the melting point of polysilicon as the temperature rises when a surge is applied, that is, the surge withstand voltage is significantly increased.

Additionally, the layout area can be reduced compared to conventional products.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional semiconductor device. DESCRIPTION OF SYMBOLS 1... P-type semiconductor substrate, 2... N-type diffusion layer, 3... Interlayer insulating film, 4... Contact window, 5... ...Aluminum wiring, 6...
...Polycide wiring.

Claims (1)

[Claims] a first diffusion layer formed on a semiconductor substrate;
A first conductive layer having a melting point higher than that of at least aluminum is connected to the diffusion layer of the first conductive layer through a contact window of a first insulating film, and the first conductive layer is connected through a contact window of a second insulating film. A semiconductor device comprising an aluminum layer.