JPH0364924A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the exertion of energy, accumulated on a metallic wiring by resultant heat and stress, from concentrating in the sides of an aluminum alloy by a method wherein the aluminum alloy is formed in such shape as only its surface is not covered with an insulating film but exposed and then only said surface is selectively coated with a high melting point metal so as to form a metallic wiring in the laminated layer structure. CONSTITUTION:A silicon substrate 1 is coated with an aluminum silicon alloy 3 which is the patterned with the same shape as a metallic wiring pattern. Next, after depositing a plasma oxide film 4, the whole surface is coated with a photoresist 5 and flattened. Next, the photoresist 5 and the plasma oxide film 4 are etched back under same etching conditions at the same etching rate thus exposing the surfaces of the aluminum silicon alloy 3. Finally, tungsten 6 is selectively formed on the surface of the aluminum silicon alloy 3 by low pressure CVD process to form a metallic wiring in the laminated layer structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing metal wiring for a semiconductor device.

[Conventional technology]

Conventionally, metal wiring made of aluminum alloy in semiconductor devices has had the problem that the aluminum alloy moves due to the stress of the passivation film, causing defects in the metal wiring and eventually breaking. Metal wiring has been formed using a laminated structure with aluminum alloy, and metal wiring with a laminated structure in which a high melting point metal is provided on an upper layer of an aluminum alloy has often been adopted.

The conventional manufacturing method of metal wiring with a laminated structure in which a high melting point metal is provided on the upper layer of this aluminum alloy is to place a predetermined semiconductor element, an insulating film, and a conductive opening on a silicon substrate.
An aluminum alloy and a high melting point metal are sequentially deposited, and then the high melting point metal and aluminum alloy are sequentially etched into a desired shape using photolithography technology and dry etching technology to form metal wiring. This method was used.

[Problem to be solved by the invention]

Problems with the above-mentioned conventional method for shaping metal wiring in a semiconductor device will be explained with reference to FIG.

First, an aluminum-silicon alloy 3 and a titanium-tungsten alloy 9 are successively deposited on a predetermined semiconductor element, a silicon oxide film, and a silicon substrate 1 provided with a 2° conductive opening. The titanium-tungsten alloy 9 and the aluminum-silicon alloy 3 are sequentially etched into a desired shape using dry etching technology to form metal wiring, and then a silicon oxide film 4 (hereinafter referred to as plasma oxide film 4) is formed by plasma CVD. 2) to cover the surface of the metal wiring.

In this method, the metal wiring has a laminated structure of the aluminum-silicon alloy 3 and the titanium-tungsten alloy 9 during the growth stage of the plasma oxide film 4. In comparison, the energy accumulated in the metal wiring due to heat and stress during the growth of the plasma oxide film 4 does not dissipate isotropically, and it tends to concentrate in the aluminum-silicon alloy 3 and dissipate laterally. If the side surfaces are not completely covered with a strong film, the aluminum-silicon alloy 3 may melt from the side surfaces of the metal wiring, or aluminum whiskers may grow, resulting in short circuits with adjacent metal wiring, as shown in Figure 3. It had the disadvantage of

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention is a method for manufacturing a metal wiring having a laminated structure of an aluminum alloy and a high melting point metal, after forming a shape in which only the upper surface of the aluminum alloy is exposed without being covered with an insulating film. The method includes a step of selectively depositing a high melting point metal only on the upper surface of the aluminum alloy to form a metal wiring having a laminated structure.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) to 1(e) are sectional views of main steps of an embodiment of the first invention.

First, as shown in FIG. 1 (a), a predetermined semiconductor element,
Silicon oxide film 2. Approximately 1.0 μm of aluminum-silicon alloy 3 is deposited on a silicon substrate 1 provided with a conductive opening by a sputtering method, and a metal wiring pattern is formed on the aluminum-silicon alloy 3 using ordinary photolithography and dry etching techniques. pattern into the same shape.

Next, as shown in FIG. 1(b), a plasma oxide film 4 having a thickness of about 1.2 μm is deposited by plasma CVD, and then a photoresist 5 is applied to flatten the surface.

Next, as shown in FIG. 1C, etching is performed under conditions where the photoresist 5 and the plasma oxide film 4 have the same etching rate to expose the upper surface of the aluminum-silicon alloy 3.

Thereafter, as shown in FIG. 1(d), tungsten 6 with a thickness of about 0.1 μm is selectively formed on the upper surface of the aluminum-silicon alloy 3 by low-pressure CVD using tungsten hexafluoride and silane gas. Then, a metal wiring having a laminated structure is formed.

Finally, again, a plasma oxide film 4 with a thickness of about 1.0 μm is applied.
a is grown, and the manufacturing process of a metal wiring having a laminated structure as shown in FIG. 1(e) is completed.

FIGS. 2(a) to 2(f) are sectional views of main steps of an embodiment of the second invention.

First, as shown in FIG. 2(a), after forming a silicon oxide film 2a with a thickness of about 1.5 μm on a silicon substrate 1 on which a predetermined semiconductor element is provided, a metal A groove having a depth of about 1.0 μm in the shape of a wiring pattern is formed using photolithography and dry etching.

Next, as shown in FIG. 2(b), the silicon oxide film 2a
A conductive opening reaching a desired semiconductor element is formed in the groove.

Next, as shown in FIG. 2(C), a molybdenum silicide 7 of about 5 Qnm is formed by a normal sputtering method, and then an aluminum-silicon alloy 3 is deposited by a bias sputtering method to cover the entire surface with aluminum. Covered with silicon alloy 3 and silicon oxide film 2a
Aluminum-silicon alloy 3 grooves and conductive openings
Fill with.

Next, as shown in FIG. 2(d), the silicon oxide film 2a
The aluminum-silicon alloy 3 is etched back until the molybdenum silicide 7 other than the grooves and conductive openings is exposed, and then the molybdenum silicide 7 exposed on the upper surface of the silicon oxide film 2a is removed by etching. At this stage, metal wiring made of only the aluminum-silicon alloy 3 is formed.

Next, as shown in FIG. 2(e), similarly to the embodiment of the first invention, a low pressure CVD method using tungsten hexafluoride and silane gas is used to selectively coat the upper surface of the aluminum-silicon alloy 3. Tungsten 6 with a thickness of about 0.1 μm
A metal wiring having a laminated structure is formed.

Finally, as shown in FIG. 2(f>), a PSG film 8 is deposited as a passivation film by the CVD method, thereby completing the manufacturing process of the metal interconnection having a laminated structure.

Note that, as an embodiment of the first and second inventions, a method for manufacturing a metal wiring having a one-layer stacked structure has been described;
It is clear that the present invention can be applied to metal wiring in the second and subsequent layers of multilayer wiring.

〔Effect of the invention〕

As explained above, the present invention provides a method for manufacturing a metal wiring having a laminated structure of an aluminum alloy and a high-melting point metal, after forming a shape in which only the top surface of the aluminum alloy is exposed without being covered with an insulating film. By selectively depositing a high-melting point metal only on the top surface of the aluminum alloy to form a metal wiring with a laminated structure, the subsequent glabella insulating film (BL) is formed into a metal wiring due to the heat and stress caused by the passivation film deposition process. Even if energy accumulation occurs,
Unlike the conventional example, the side surfaces of the aluminum alloy are covered with a strong insulating film, so that it is possible to prevent the stored energy from being concentrated on the side surfaces of the aluminum alloy. Therefore, there is no phenomenon in which the aluminum-silicon alloy 3 melts from the side of the metal wiring or shorts with adjacent metal wiring due to aluminum whisker growth, and highly reliable semiconductor devices can be manufactured easily. .

[Brief Description of the Drawings] Figures 1 (a) to (e) are sectional views of main steps of an embodiment of the first invention, and Figures 2 (a) to (f) are one implementation of the second invention. FIG. 3, which is a sectional view of the main steps in the example, is a sectional view for explaining the problems of the prior art. DESCRIPTION OF SYMBOLS 1... Silicon substrate, 2, 2a... Silicon oxide film, 3... Aluminum-silicon alloy, 4, 4a...
・Plasma oxide film, 5... Photoresist, 6...
Tungsten, 7...Molybdenum silicide, 8...
・PSG film, 9...Titanium-tungsten alloy.

Claims (2)

[Claims] (1) In a method for manufacturing a semiconductor device having a metal wiring in a laminated structure in which a high melting point metal is formed on the upper surface of an aluminum alloy, a step of forming an aluminum alloy wiring from an aluminum alloy and insulating the aluminum alloy wiring except for the upper surface thereof. A semiconductor device comprising a step of forming a structure covered with a film, and a step of selectively forming a high melting point metal on the upper surface of the aluminum alloy wiring to form the metal wiring of the laminated structure. manufacturing method. (2) A method for manufacturing a semiconductor device having a metal interconnection having a laminated structure in which a refractory metal is formed on the upper surface of an aluminum alloy, the step of forming an insulating film and forming a groove in the shape of the metal interconnection having the lamination structure; The method includes the steps of: filling the groove with an aluminum alloy to form an aluminum alloy wiring; and selectively forming a high melting point metal on the upper surface of the aluminum alloy wiring to form the laminated metal wiring. A method for manufacturing a featured semiconductor device.