JPH02185024A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To apply a conductive layer for a wiring positively along a taper, and to ensure coverage sufficiently by evaporating the conductive layer for the wiring onto the side face of an opening section under the state in which a tapered conductive layer is left. CONSTITUTION:The surface of a phosphate glass layer 8 is coated with a photo- resist 10, and the pattern of a contact hole is formed. The phosphate glass layer 8 and an SiO2 film 6 are etched while using the photo-resist 10 as a mask, and an opening section 9 is shaped. A conductive layer 12 is anisotropic-etching through RIE, and the conductive layer 12 is left only on the sidewall section of the opening section 9. Aluminum is evaporated again, and a conductive layer 14 for a wiring is shaped onto aluminum. The side face of the opening section 9 is formed to a tapered shape by the conductive layer 12 in the opening section 9 at that time. Accordingly, aluminum is applied positively and continuously, thus ensuring sufficient coverage.

Description

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

[Background Art] In the manufacturing process of a semiconductor device, there is a step of wiring conductive regions such as a base and an emitter formed on a semiconductor substrate. This process is performed by contact patterning an insulating layer on the surface of a semiconductor substrate. First, a wiring pattern is formed on the surface of the insulating film using a photoresist, and then, using the photoresist as a mask, the insulating layer in the conductivity type region is etched to form an opening. After that, a conductive layer for wiring such as aluminum is deposited, and then unnecessary portions are removed.

Isotropic etching is generally used for etching the insulating layer to form openings. wet
When using isotropic etching such as taper etching, the shoulder portion of the opening in the insulating layer becomes slightly sagging.
It becomes tapered.

Therefore, when depositing the aluminum layer, the aluminum layer is deposited smoothly along the gentle shoulder portion, and there is no discontinuity in the aluminum layer.

That is, sufficient aluminum coverage is obtained.

Contact reflow may also be performed to smooth the shoulder portion of the opening by heat treatment.

[Problems to be Solved by the Invention] However, in the case of isotropic etching as described above, since the shoulder of the opening is smoothly dropped, the area occupied by the opening becomes large. Therefore, 1
There is a problem in that it is difficult to form fine contacts on the order of micrometers, and the integration density cannot be improved.

Furthermore, when contact reflow is performed, there is a problem that phosphorus is auto-doped into the insulating layer due to heat treatment.

In order to solve the above problems, it is also possible to employ anisotropic etching using reactive ions. According to this method, the shoulder of the opening does not sag, so the opening can be made smaller. However, during vapor deposition of aluminum, it becomes difficult for vapor deposition particles to adhere to the inside of the opening. That is, coverage of the aluminum cannot be ensured, and in some cases, a problem arises in that the aluminum is not continuous inside the opening.

SUMMARY OF THE INVENTION An object of the present invention is to provide a manufacturing method capable of solving the above-mentioned problems and forming a small opening while ensuring coverage of a conductive layer for wiring.

[Means for Solving the Problems] A method for manufacturing a semiconductor device according to the present invention includes a step of forming an opening in an insulating film on a surface of a semiconductor substrate by anisotropic etching, and forming an opening on the opening and the insulating film by vapor deposition. The method includes a step of forming a conductive layer, a step of performing anisotropic etching to leave the conductive layer only near the side walls of the opening, and a step of forming a conductive layer for wiring by vapor deposition on the opening and the insulating film.

[Function] In the present invention, the wiring conductive layer is deposited with a tapered conductive layer left on the side surface of the opening.

Therefore, the wiring conductive layer is reliably deposited along this taper.

Furthermore, since anisotropic etching is used, the area of the opening can be kept small.

Furthermore, since no heat treatment is performed, autodoping and the like do not occur.

[Example] A method for manufacturing a semiconductor device according to an example of the present invention is described in a first embodiment.
Shown in Figures A, B, C, and D. Here, a conductive region (source, drain, etc.) 4 is formed on the surface of a semiconductor substrate 2, and an SiO□ film 6, which is an insulating film, and a phosphor glass layer 8 are formed on top of these. do. A description will be given assuming that wiring is provided in this conductive region 4.

First, a photoresist lO is applied to the surface of the phosphor glass layer 8 to form a contact hole pattern. Next, as shown in FIG. 1A, the phosphor glass layer 8.5iO8 film 6 is etched using this photoresist lO as a mask to form an opening 6.

This etching is performed by anisotropic etching.

After removing the photoresist IO, aluminum is deposited to form a conductive layer 12. FIG. 1B shows this state. The thickness of this conductive layer 12 is 1 μm.
That's about it.

Next, the conductive layer 12 is anisotropically etched by RIH. As a result, as shown in FIG. 1C, the conductive layer 12 is left only on the sidewall portion 4 of the opening 9.

Thereafter, aluminum is deposited again to form a wiring conductive layer 14 thereon (see first diagram).

At this time, since the side surfaces of the opening 9 are tapered by the conductive layer 12, the aluminum can be deposited continuously and ensure sufficient coverage.

In addition, although aluminum was used as the wiring conductive layer 14 in the above embodiment, other conductive metals may be used.

[Effects of the Invention] In the method for manufacturing a semiconductor device according to the present invention, a conductive layer for wiring is deposited with a tapered conductive layer left on the side surface of the opening. Therefore, the conductive layer for wiring is reliably deposited along this taper, and sufficient coverage is ensured.

Further, since the opening is formed and the conductive layer remains on the side wall of the opening by anisotropic etching, the area of the opening can be kept small, and fine contacts of about 1 μm can be formed.

Furthermore, since no heat treatment is performed, problems such as autodoping do not occur.

[Brief explanation of the drawing]

FIGS. 1A to 1D are cross-sectional views showing the manufacturing process of a semiconductor device according to an embodiment of the present invention. 2... Semiconductor substrate 6... 5in2 film 8... Phosphorus glass layer 9... Opening 10... Photoresist 12... Conductive layer 14... Conductive layer for wiring

Claims (1)

[Claims] (1) A step of forming an opening in an insulating film on the surface of a semiconductor substrate by anisotropic etching. A step of forming a conductive layer by vapor deposition on the opening and the insulating film. Performing anisotropic etching and forming an opening on the side walls of the opening. A method for manufacturing a semiconductor device, comprising: a step of leaving a conductive layer only in the vicinity; and a step of forming a conductive layer for wiring by vapor deposition over the opening and the insulating film.