JPH0493029A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a stabilized inner insulating film and prevent poor connection between upper and lower wirings by applying microwaves to a coating formed on an inner insulating film. CONSTITUTION:A silicon oxide film 2 is formed on a silicon substrate 1. Aluminum is deposited on the oxide film and selectively etched into aluminum interconnections 3. A plasma oxide film 4 is formed over the surface, including the interconnections 3. A solution composed mainly of a silicon compound is applied to the surface of the oxide film 4, and this coating is heated by microwaves from a magnetron. As a result, the movement of water molecules is enhanced, and the coating, even portions on the sides of the aluminum interconnections, enhances moisture removal and turns into a stable silica film 5. A plasma oxide film 6 is deposited over the surface and etched to form a through hole 7. Aluminum is deposited on the surface, including the through hole, and the aluminum is selectively etched to form aluminum interconnections 9.

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 a semiconductor device having multilayer wiring.

[Conventional technology]

In order to reduce unevenness that occurs in the wiring area of a semiconductor device having multilayer wiring, a technique has been adopted in which an insulating film is formed using a coating method on a part of an interlayer insulating film and the surface is flattened.

FIGS. 2(a) to 2(c) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining a conventional method of manufacturing a semiconductor device.

As shown in FIG. 2(a), an aluminum layer with a thickness of 0.6 μm is placed on the silicon oxide film 2 provided on the silicon substrate.
Aluminum wiring 3 is provided as a lower layer wiring by depositing the silicon oxide film (hereinafter referred to as plasma oxide film) 4 to a thickness of 0.5 μm using the plasma CVD method and selectively etching it. Deposited to a thickness of .

Next, a coating film is formed on the plasma oxide film 4 by applying a solution containing a silicon compound such as silanol as a main component to a thickness of 0.15 μm, and heated at a temperature of about 400°C for 2 hours.
A heat treatment is performed for 0 minutes to cause a dehydration reaction and form a silica film 5.

Here, since the thickness of the coating film is thick at the stepped portions on the side surfaces of the aluminum wiring 3, the water cannot be sufficiently dehydrated and an unstable silica film 5a remains.

Next, as shown in FIG. 2(b), a plasma oxide film 6 with a thickness of 0.5 μm is formed on the silica film 5, and a plasma oxide film 6 on the aluminum wiring 3 is formed on the silica film 5. The plasma oxide film 4 is sequentially etched to form through holes 7.

Next, as shown in FIG. 2C, an aluminum layer for forming upper layer wiring is deposited to a thickness of 1.0 μm on the surface including the through holes 7 by sputtering. Here, since the substrate temperature is heated to about 300° C. in order to improve step coverage, the surface of the aluminum wiring 3 is oxidized by moisture released from the unstable silica film 5a, and an alumina insulating film 8 is formed. There is. Next, aluminum wiring 9 is formed by selectively patterning the aluminum layer.

[Problem to be solved by the invention]

As described above, in the conventional semiconductor device manufacturing method, it is difficult to convert the coating film provided on the stepped portion of the side surface of the lower layer wiring into a sufficiently stable insulating film, and an unstable insulating film remains. This area became a source of moisture during subsequent heat treatment, forming an alumina insulating film on the surface of the lower layer aluminum wiring, resulting in a problem of poor contact between the upper layer wiring and the lower layer wiring. .

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention includes the steps of: selectively providing a lower layer wiring on an insulating film provided on a semiconductor substrate; forming a first interlayer insulating film on a surface including the lower layer wiring; forming a coating film for forming an insulating film on the first interlayer insulating film to smooth the surface; and forming a second interlayer insulating film by subjecting the coating film to a dehydration reaction by microwave induction heating. a step of selectively etching the first and second interlayer insulating films on the lower wiring to form an opening, and electrically connecting the surface including the opening with the lower wiring. The method includes a step of selectively providing two-layer wiring.

〔Example〕

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

FIGS. 1(a) to 1(c) are cross-sectional views of a semiconductor chip shown in order of steps for explaining an embodiment of the present invention.

First, as shown in FIG. 1(a), silicon oxide M2 is provided on a silicon substrate 1, and an aluminum layer for forming lower wiring is deposited on the silicon oxide film 2 to a thickness of 0.6 μm. Aluminum wiring 3 is formed by selectively etching. Next, a plasma oxide film 4 is formed to a thickness of 0.5 μm on the surface including the aluminum wiring 3. Next, a solution containing a silicon compound such as silanol as a main component is applied onto the plasma oxide film 4 by a spin method to a thickness of 0.15 mm.
A coating film of μm was formed, and the 2
, the coating film is heated with a 45 GHz microwave. 2.4
Since the 5 GHz microwave activates the movement of water molecules, the coating film thickly accumulated on the stepped portions of the side surfaces of the aluminum wiring 3 is sufficiently dehydrated to form a stable silica film 5 on the entire surface.

Next, as shown in Figure 1(b), a film with a thickness of 0.5 μm was applied to the entire surface.
A plasma oxide film 6 of 6.m is deposited on the aluminum wiring 3. Silica film 5 Plasma oxide film 4
Through holes 7 are formed by selectively and sequentially etching.

Next, as shown in FIG. 1(c), an aluminum layer with a thickness of 1.0 μm is deposited on the surface including the through hole 7, and this is selectively etched to connect the aluminum wiring 3 of the through hole 7. An aluminum wiring 9 is formed.

Note that by repeating the above steps, it is also possible to apply the present invention to multilayer wiring of three or more layers.

In addition, although only microwave induction heating was used in the heating process of the coating film, other heating methods (lamp heating, heater heating, etc.)
May be used in combination with

〔Effect of the invention〕

As explained above, the present invention uses induction heating using microwaves on the coating film formed on the first interlayer insulation crotch to activate the movement of water molecules in the stepped portion and to prevent the water from accumulating in the stepped portion on the side surface of the lower wiring. Even thick coatings are sufficiently dehydrated, so
A stable interlayer insulating film can be formed. the result,
Even when the substrate is heated to improve the step coverage of the aluminum layer for forming the upper layer wiring after forming the through holes, no alumina insulating film is formed on the surface of the lower layer aluminum wiring, and there is a good gap between the upper layer wiring and the lower layer. This has the effect that a semiconductor device having multilayer wiring with electrical contact can be realized.

DESCRIPTION OF SYMBOLS 1...Silicon substrate, 2...Silicon oxide film, 3゜9...Aluminum wiring, 4,6...Plasma oxide film,
5...Silica film, 5a...Unstable silica film, 7...Through hole, 8...Alumina insulating film.

Claims (1)

[Claims] A step of selectively providing a lower layer wiring on an insulating film provided on a semiconductor substrate, a step of forming a first interlayer insulating film on a surface including the lower layer wiring, and a step of forming an insulating layer on the first interlayer insulating film. a step of forming a coating film for film formation and smoothing the surface; a step of dehydrating the coating film by microwave induction heating to form a second interlayer insulating film; and a step of forming a second interlayer insulating film on the lower wiring. and a step of selectively etching the second interlayer insulating film to provide an opening, and a step of selectively providing an upper layer wiring electrically connected to the lower layer wiring on the surface including the opening. A method for manufacturing a semiconductor device, characterized in that: