JPS61113259A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable to prevent he generation of pinholes in the plasma CVD film by a method wherein the protrusion part on the surface of the substrate, whereon the plasma CVD film is formed, is removed by performing a dry etching using an etchback method and the surface of the substrate is flattened. CONSTITUTION:When a silicon oxide film 12 and an Al wiring layer 13 are formed on a substrate 11, a protrusion 13a to be called a hillock is generated. A resist 16 is applied over the whole surface of the Al wiring layer 13. Then, a dry etching is performed on the resist 16 and the protrusion 13a by an etchback method and a flattening of the Al wiring layer 13 is performed. Accordingly, when a plasma SiN film 14 is formed on the Al wiring layer 13 by a plasma CVD method in the following process, the surface of the plasma SiN film 14 also becomes flat and a positive-type resist, which is used as a mask when an etching is performed on the plasma SiN film 14, can be applied on the whole surface of the plasma SiN film 4 without exception. By said procedure, any pinhole is not generated in the plasma CVD film 14. As a result, the generation of failure such as short-circuit decreases sharply, and moreover, the moisture resisting characteristics, the insulation characteristics and the barrier characteristics to sodium ions and so forth are made to improve.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to plasma cVD (Chemical Vacuum
A method for manufacturing a semiconductor device in which a plasma CVD film is formed on the surface of a substrate by a pour deposition method, particularly for improving electrical insulation in a semiconductor device,
The present invention relates to a method for forming a protective film and an interlayer insulating film in a semiconductor device having a multilayer interconnection structure for the purpose of improving moisture resistance and preventing the intrusion of sodium ions (Na+).

Structure of the Conventional Example and Its Problems FIG. 1 is a sectional view showing the manufacturing process of a semiconductor device by a conventional method. In FIG. 1(a), an Al wiring 3 is formed,
This shows a cross section after heat treatment has been applied to the Al wiring 3 in order to stabilize it, and protrusions 3a called hillocks of about 1 to 2 μm are generated here and there. Figure 1 (bl
1 shows a cross section after forming a silicon nitride film 4 (hereinafter abbreviated as plasma SiN film) on Al wiring 3 by plasma CVD method. Here, since the plasma CVD method has good step coverage (film coverage), the projections 3a are completely covered. FIG. 1 (C1 is a diagram showing the resist 5 applied on the plasma SiN film 4. The resist 5 is applied with a spinner, but the resist is applied to the tip of the protrusion 3a with the same film thickness as the flat part. Next, after exposing and developing the resist 5,
Dry etching of the plasma SiN film 4 is performed using the resist 5 as a mask to open a contact hole.

However, as mentioned above, the tip of the protrusion 3a has a thin film of resist 5 or is not coated, so the tip of the protrusion 3a is
The plasma SiN film 4 at the tip of the protrusion 3a is etched away to form a pinhole as shown in FIG. After that, the resist 4 is removed and the second layer of Al wiring is performed, but if there is a pinhole, the first layer of Al wiring 3 and the second layer of Al wiring cannot be insulated, causing a short circuit. becomes.

In this way, in the conventional manufacturing method, the surface of the Al wiring was processed without flattening, so pinholes were formed in the Prader-r SiN film 4 due to the protrusions 3a formed on the Al wiring 3. As a result, when this process is applied to a semiconductor device with a multilayer interconnection structure, it causes short-circuit defects, lowers manufacturing yield, and deteriorates productivity. Further, when applied to a protective film of a semiconductor device, it has the disadvantage that it deteriorates the moisture resistance properties, insulation properties, and sodium ion barrier properties of the semiconductor device, and greatly reduces the reliability of the semiconductor device.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, the present invention provides a method for manufacturing a semiconductor device that makes it possible to prevent the occurrence of pinholes in a plasma CVD film in a semiconductor device.

Structure of the Invention The present invention is a method of flattening the surface of a substrate by removing protrusions on the surface of the substrate on which a VD film is to be formed using an etch-back method and dry etching, and then applying plasma to the substrate. By forming a CVD film, it is possible to apply the resist uniformly in the subsequent process, and as a result, the generation of pinholes in the plasma CVD film can be prevented.
It has the unique effect of reducing shot defects, improving moisture resistance properties, insulation properties, barrier properties against sodium ions, etc., and making it possible to improve the manufacturing yield of semiconductor devices.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a cross-sectional view of each step showing a method for manufacturing a semiconductor device in an embodiment of the present invention.

! In Figure 2, 11 is a substrate made of silicon, and 12 is a substrate whose surface is oxidized by heat treatment and has a thickness of approximately 50 mm.
A silicon oxide film 13 is formed by a sputtering method and is made of aluminum and has a thickness of about 1 μm. After being processed into a thin film conductor circuit in a photo application process, the silicon oxide film 12 Approximately 400'C in order to improve adhesion and stabilize the thin film conductor circuit.
A7 heat treated in an atmospheric furnace? It's the wiring. 13a is a protrusion called a hillock formed on the surface of the Al wiring 13 after heat treatment, and 14 is a plasma S made of silicon nitride.
The iN film 16 is a positive resist with a thickness of approximately 3 μm used to remove the protrusion 13a by an etch-back method and planarize the surface of the AA' wiring 13. Here, the etch-back method means that the resist 16 and the protrusion 13a are etched at approximately the same etching speed, that is, the etching selection ratio is approximately 1.
This is a method of removing a.

FIG. 2(a) is a diagram showing a cross section after a silicon oxide film and an Al wiring 13 are formed on the substrate 11 and then heat-treated. The protrusions 13a called hillocks had an average height of 1.8 μm. FIG. 2(b) is a diagram showing a cross section after applying the resist 16 to a thickness of about 3 μm using a spinner.
A cross-sectional resist 16 is applied to the entire surface of the Al wiring 13 including the protrusions 13a. Next, dry etching is performed under etching conditions such that the etching speed of the resist 16 and the protrusion 13a are approximately the same, that is, the etching selection ratio is approximately 1. In this example, a parallel plate electrode type dry etching apparatus was used, and dry etching was performed with low temperature plasma of a mixed gas of carbon tetrachloride (CC14) and oxygen (O2), and water washing was performed immediately after dry etching. Note that FIG. 2(c) shows a cross section after performing the above-mentioned etch-back method using a power source with a high frequency power frequency of 13.56 MH2.

As a result, the l wiring 13 was flattened.

Therefore, if a plasma SiN film is then formed on the Al wiring 13 by the plasma CVD method as shown in FIG. 2 (cl),
The surface of the plasma SiN film 14 also becomes flat.

Therefore, when forming a contact window, it is possible to completely coat the entire surface with an organic material that serves as a mask for etching the plasma SfN film 14, that is, a positive resist. CVD film 14
As a result, the number of short-circuit defects was drastically reduced, and the moisture resistance, insulation properties, and nitrogen properties such as sodium 17ium ions were improved, and the manufacturing yield of semiconductor devices was improved.

In this embodiment, the material of the Al wiring 13 is aluminum, but it may be an aluminum alloy containing at least a small amount (within 3%) of silicon. Furthermore, in this embodiment, the protrusions 13a are caused by hillocks generated by heat treatment, but they may also be caused by roughness on the surface of the aluminum thin film caused by clusters or the like when forming the aluminum thin film by sputtering. It's okay.

In this example, the aluminum thin film was formed by a sputtering method, but it may also be formed by a vacuum evaporation method or an ion blating method.

Furthermore, in this embodiment, the material of the resist containing nitride was made positive by the plasma CVD method, but it may be made of a negative resist.

Effects of the Invention As described above, according to the present invention, plasma CVD1
By forming the plasma CVD film after removing the protrusions on the surface of the base material on which the film is to be formed by an etch-back method, it is possible to reduce the occurrence of pinholes in the plasma CVD film. As a result, it is possible to reduce stain h defects in semiconductor devices, improve moisture resistance properties, insulation properties, barrier properties such as sodium ions, and greatly improve the manufacturing yield of semiconductor devices.The practical effects are as follows: There is something called a dog.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of each step showing a conventional method of manufacturing a semiconductor device, and FIG. 2 is a cross-sectional view of each step of a method of manufacturing a semiconductor device according to the present invention. 11...Silicon JIS, 12...Silicon oxide film, 13...Al wiring, 14...
...Plasma 5iNli, 16...Mountain/Resist, 1
3a... Protrusion. Name of agent: Patent attorney Toshio Nakao (1st person)
figure

Claims (1)

[Claims] When forming a plasma CVD film on a base material, the protrusions on the surface of the base material are removed by dry etching using an etch-back method to flatten the surface of the base material, and then a plasma CVD film is formed on the base material. A method for manufacturing a semiconductor device that includes a process of