JPS6018144B2 - Manufacturing method of semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device in which a silicon oxide film is formed on a metal wiring layer to serve as an insulating layer.

Today, there has been significant progress in manufacturing technology for semiconductor devices, but the devices themselves are now required to meet stricter standards due to their characteristics.

In addition, with the aim of reducing costs, the element density of semiconductor chips has increased, and their structures have become extremely complex.In particular, the wiring structure on semiconductor substrates has become multi-layered wiring to increase the density of integrated circuits. It's starting to feel like we have to take care of it. A manufacturing problem associated with multilayer wiring structures is that when two wiring layers, such as aluminum, are formed, pinholes can form in the oxide film that insulates the two layers, causing electrical shorts. That was the point now.

A major cause of pinholes is the formation of protrusions in the underlying wiring body due to heating during the formation of the oxide film, and as shown in Figure 1 a, b, c, and d, the protrusions are generated on the substrate 1. When the aluminum wiring 2 is covered with an insulating layer 3 and further wiring layers are formed, the protrusion 2a of the aluminum wiring 2 is heated and grows when forming the insulating layer 3, and the glass mask 4
When etching the insulating layer 3 with the photoresist 5 in close contact with the photoresist 5, the photoresist 5 becomes thinner at the protrusion 2a, and unnecessary holes are formed as shown in FIG. In addition, the above aluminum wiring 2
Even if the protrusion 2a does not form a hole in the insulating layer 3, a similar phenomenon occurs when the second aluminum wiring 6 is provided on the insulating layer 3, as shown in FIG. 1d. There was a risk that this aluminum wiring 6 would break. Thus, a problem in manufacturing semiconductor devices is that protrusions are formed on the surface of the aluminum wiring layer by heat treatment, and this is directly linked to a decrease in the reliability of the semiconductor device, so improvements have been desired for a long time.

This invention was made in view of the above circumstances, and when forming a silicon oxide film, an oxide film is formed with a constant thickness at room temperature before heating during vapor phase growth, and when heated, an oxide film is formed on the surface of an aluminum wiring layer. It is an object of the present invention to provide a method for manufacturing a semiconductor device that can particularly improve the reliability of a semiconductor device having a multilayer wiring structure by preventing the formation of protrusions on the semiconductor device.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
FIG. 2 shows a manufacturing process in which an element is formed in a silicon substrate and a metal wiring layer made of aluminum is provided on the surface of the element. A P-type impurity diffusion layer 12 is formed on the N-type semiconductor substrate 11.
, 13 are formed, and in one of the diffusion layers 12, an N0 type impurity diffusion layer 14 is further formed. The surface of this substrate 11 is protected by an oxide film 16, and as shown in FIG. 2A, an aluminum wiring layer 16 is provided to electrically connect between the diffusion layers 13 and 14. Aluminum is used for the metal wiring layer because it is low cost and has excellent processability such as vapor deposition and etching.
FIG. 2b shows a step of further covering the aluminum wiring layer 16 formed on the oxide film 15 with a silicon oxide film.

Conventionally, such oxide films are made of silane (Si) and oxygen (02).
In this case, silicon hydroxide (Si(OH)4) was first dissolved in ethyl alcohol or ethyl acetate to form a Si02 film at room temperature. A containing organic solvent is prepared, and this solvent is uniformly applied to a thickness of 2000A or less using a spin coating device. A silicon oxide film is formed on the thus applied solvent to a desired thickness by a conventional vapor phase growth method. The first silicon oxide film 17, which is formed at room temperature, evaporates and solidifies the organic solvent before the second silicon oxide film 172 is grown in the vapor phase.
No protrusions are generated on the surface of the aluminum wiring layer 16 even when heated to 50 to 400 qo. FIG. 2c shows the silicon oxide film 1.
7, 172 by photoetching to form an electrical communication hole between the aluminum wiring layer 18 provided through the oxide film 17 and the wiring layer 16. The oxide film 17 separates and insulates the wiring layers 16 and 18 formed in two layers, and if the thickness of the first silicon oxide film 17 is 500A or more, a protrusion will form on the lower aluminum wiring layer 16. There is almost no risk of this occurring (see Figure 3).
. By the way, when a silicon-containing solvent is applied to form the first silicon oxide film 17 to a thickness of 5000 Å or more, there is a problem in that cracks are likely to occur on the surface, and when forming contact holes etc. by etching,
For example, if a surfactant-based etching solution is used, the etching rate is slower than that of the second silicon oxide film 172 grown by vapor phase growth, resulting in a decrease in etching accuracy, which may also cause breaks in the upper aluminum wiring layer 18. . The decrease in etching accuracy is due to the etching spreading in the lateral direction, and the first silicon oxide film 17. By setting the current to 2000A or less, there will be no actual problem. Note that the first silicon oxide film 17, which is formed at room temperature, is of course electrically insulating, but as an insulating layer it requires about 7000A, so as mentioned above, the second silicon oxide film 17 is electrically insulating. The film 172 is grown in a vapor phase. Further, the film thickness of the first silicon oxide film shown on the axis in FIG. 3 is not the thickness at the time of solvent application, but the thickness immediately before the formation of the vapor phase growth layer is started. According to the method shown in the above embodiment, when forming a multilayer wiring structure of a semiconductor device, no protrusions are generated on the surface of the lower aluminum wiring layer, so that the insulating properties of the silicon oxide film are maintained, and the wiring structure of the upper layer is The risk of layer breakage is also reduced.

As described above, in the method of this invention, the aluminum wiring layer is first coated at room temperature, and then the Si02 film is formed to the desired thickness by vapor phase growth, so it is possible to reliably form a multilayer wiring structure. It is possible to provide a method for manufacturing a semiconductor device that can increase the reliability of an integrated semiconductor device by increasing the size of the device, improving characteristics, increasing the yield rate, and so on.

[Brief explanation of the drawing]

Figures 1 a to d are cross-sectional explanatory diagrams showing the steps of the conventional method, and Figure 2
Figures a to c are cross-sectional explanatory views showing embodiments of the method of this invention;
FIG. 3 is a graph showing the density of protrusions generated when Si(OH)4 is applied onto an aluminum wiring layer. 11... N-type semiconductor substrate, 15... silicon oxide film, 16.
...Aluminum wiring layer, 17. ...first silicon oxide film, 172 ...second silicon oxide film. O 1 figure Soup 2 figure O 3 figure

Claims (1)

[Claims] 1. Forming a first patterned metal wiring layer on a semiconductor substrate via an insulating film, and applying a silicon-containing solvent that oxidizes at room temperature on this layer to a thickness of 500 to 2000 Å.
forming a first silicon oxide film with a thickness of , forming a second silicon oxide film on the first silicon oxide film by vapor phase growth, and a step of forming a photoresist film, a step of patterning the first and second silicon oxide films by photolithography using the photoresist film, and a step of patterning the first and second silicon oxide films on the patterned second silicon oxide film. 1. A method for manufacturing a semiconductor device, comprising the steps of: forming a second metal wiring layer.