JPH05198789A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To realize an ohmic junction, by combining a BPSG insulation film with a barrier metal. CONSTITUTION:A silicon oxide film is formed on the principal surface of a silicon substrate 1. After forming thereon a silicon oxide film BPSG4 including boron and phosphorus, a contact hole 7 is formed. Then, by injecting ions, an impurity diffusing layer 2 is formed near the surface of the silicon substrate 1. Subsequently, a first metallic film 5 is formed out of tungsten, etc., by a CVD method, etc. By these metals, no alloy and no spike phenomenon are generated in its junction plane to the silicon substrate, and an ohmic junction having a low resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a metal electrode when a BPSG film is used as an insulating film in a large scale integrated circuit (VLSI) device.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional metal electrode wiring structure in which a silicon thermal oxide film and a silicon oxide film (PSG) containing phosphorus (P) are used as an insulating film and aluminum containing silicon is used as a wiring metal film. A cross-sectional view of the above is shown, and the conventional method will be described below using this.

First, as shown in the figure, after a silicon oxide film (3) and a PSG film (8) are formed on the main surface of a silicon substrate (1), contact holes (7) are selectively formed by photolithography and etching. ) Is formed. Then, an impurity layer (2) is formed near the surface of the silicon substrate by using the ion implantation method and the thermal diffusion method. Finally, an aluminum alloy film (6) containing silicon is formed by using a sputtering method, a CVD method or the like, and heat treatment is performed to sinter this alloy film (6).

[0004]

In the conventional semiconductor device in which the PSG film is used as the insulating film, as shown in FIG. 4, the aspect ratio of the circuit pattern (the ratio of the film thickness to the patterning pitch) accompanying the miniaturization of the element is shown. ) Increases, it becomes necessary to raise the heat treatment temperature or increase the phosphorus content in order to achieve good planarization, but the former affects the impurity distribution in the device, and the latter deteriorates the moisture resistance. There is a problem. For this reason, BPSG, which has a lower viscosity at the conventional processing temperature, has been attracting attention as the next material. However, when BPSG is used as the insulating film and the conventional structure as shown in FIG.
As shown in FIG. 3, boron in the BPSG diffuses near the surface of the silicon substrate at the bottom of the contact hole or in the aluminum alloy film (6) containing silicon and promotes the movement of silicon in the aluminum. There has been a problem that a large amount of silicon (9) is deposited on the interface of the electrode by solid phase epitaxial growth, and the contact resistance increases by 1 to 2 digits. The present invention has been made to solve the above problems, and provides a method for manufacturing a semiconductor device having a good ohmic junction with a low resistance as well as a good planarization of a circuit pattern in a large-scale integrated circuit. The purpose is to provide.

[0005]

According to a method of manufacturing a semiconductor device according to the present invention, silicon is formed after forming a first metal film as a barrier metal in an element using a BPSG film as a second insulating film. By using the contained aluminum as the second wiring metal film, the deposition of silicon on the interface between the silicon substrate and the electrode is prevented.

[0006]

The BPSG film obtained by the method of manufacturing a semiconductor device according to the present invention is effective for flattening the unevenness on the circuit pattern having a large aspect ratio.
Of the second metal film suppresses the diffusion of boron in the BPSG film into the second metal film, and the second metal film is sandwiched between the second metal film and the silicon substrate. This prevents the phenomenon that the silicon in the film selectively undergoes solid phase epitaxial growth on the surface of the silicon substrate at the bottom of the contact hole.

[0007]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a semiconductor device according to an embodiment of the present invention. First, as shown in the figure, a silicon oxide film of about 1000 A (3) is formed on the main surface of the silicon substrate (1).
Is formed by thermal oxidation, and a silicon oxide film BPSG (4) containing phosphorus 5 to 10% and boron 2 to 5% is formed on top of it, and then contact holes (7) are selectively formed by photolithography and etching. Form. Next, an impurity diffusion layer (2) is formed near the surface of the silicon substrate by using an ion implantation method or a thermal diffusion method. Then, as the first metal film (5), any one of titanium-tungsten alloy, tungsten, titanium nitride, tantalum nitride, molybdenum silicide, tungsten silicide, titanium silicide, tantalum silicide, and Poly-Si film is sputtered by CV.
It is formed by using the D method or the like. These metals were selected as materials that do not cause alloy spike phenomenon at the bonding surface with the silicon substrate, can obtain ohmic bonding with low resistance, and can be a good diffusion barrier between aluminum and silicon. Finally, a film of aluminum containing silicon, an alloy of aluminum, silicon, copper, and aluminum alone is formed as the second metal film (6) by a sputtering method, a CVD method, or the like, and heat treatment is performed to form the metal film. Do the sintering. In large-scale integrated circuits, BP is used as an insulating film that also serves as a flat surface on the pattern surface.
When the SG film is used, by adopting the structure according to the manufacturing method shown in FIG. 1, boron in the BPSG is prevented from diffusing into the second metal film formed of aluminum containing silicon, and a silicon substrate is formed. It is possible to prevent the deposition of silicon on the interface of the metal electrode due to the solid layer epitaxial growth, and specifically, it is possible to obtain an ohmic contact of 10Ω or less even in the case of a 1 × 1 μm ² shape contact hole.
With this structure, it is also possible to use a simple substance of aluminum for the second metal film, and in this case, the first metal film functions to prevent the alloy spike phenomenon of silicon and aluminum.

[0008]

As described above, according to the method of manufacturing a semiconductor device of the present invention, by combining the BPSG insulating film and the barrier metal, the circuit surface is flat despite the miniaturization of the circuit pattern in a large-scale integrated circuit. There is an effect that excellent ohmic contact can be obtained while performing the oxidization.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional semiconductor device.

FIG. 3 is a diagram showing a state of silicon deposition on an interface between a metal film and a silicon substrate.

FIG. 4 is a diagram showing an increase in an aspect ratio of a circuit pattern with miniaturization of an element.

[Explanation of symbols]

 1 Silicon Substrate 2 Impurity Diffusion Layer 3 Oxide Film 4 BPSG Film 5 Barrier Metal Film 6 Metal Film 7 Contact Hole 8 PSG Film 9 Precipitated Silicon

Claims (1)

[Claims] 1. A manufacturing method for connecting an electrode wiring to an impurity diffusion layer of a silicon substrate of a semiconductor device, comprising: (1) forming a silicon oxide film containing boron and phosphorus on the silicon substrate; and (2). A step of selectively forming a contact hole in the silicon oxide film, and (3) a step of forming a first metal film on the impurity diffusion layer on the silicon oxide film and via the contact hole. 4) a step of forming an aluminum alloy containing silicon on the first metal film, wherein the first metal film is an alloy of titanium and tungsten, tungsten, titanium nitride film, tantalum nitride film, molybdenum silicide A method of manufacturing a semiconductor device, comprising any of tungsten silicide, titanium silicide, tantalum silicide, and polysilicon.