JPS6167245A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent disconnection of a wiring inside an opening part of a contact hole, by providing an upwardly tapered insulative coating on the side wall of the opening part, and installing a metal film inside the opening part. CONSTITUTION:To form a pattern of contact holes for wiring, first and second insulator films 3, 4 are formed on the surface of a semiconductor substrate 1. A photoresist 5 is coated on the surface of the insulator film 4, and a contact hole pattern is formed in the photoresist 5 to etch the insulator films 3 and 4. After the photoresist 5 has been removed, a coating 7 having silicon oxide as a principal component is formed inside an opening part 6 in such a manner that the coating 7 has a mortar-shaped cross-section. After the coating 7 has been sintered, it is subjected to isotropic etching so that a tapered coating 7 remains on the side wall of the opening part 6. Thereafter, wiring patterning is effected according to an ordinary technique.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a semiconductor device and a method for manufacturing the same.

(Prior Art) In the manufacturing process of a semiconductor device, there is a step of providing wiring to conductive regions such as a base and an emitter formed on a semiconductor substrate. This is done by contact patterning the insulating layer on the surface of the semiconductor substrate. In this patterning, 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. A wiring material such as aluminum is then deposited and the unnecessary portions are etched away.

Usually, a dry or wet etching method is used for etching. According to this etching method, the shoulder portion of the opening in the insulating layer becomes slightly sagging and tapered, so that when the wiring material is vapor deposited, the wiring material is applied smoothly along the shoulder portion of the opening. This is extremely convenient.

On the other hand, in recent years, there has been a demand for increased integration density in this type of semiconductor device. However, if the shoulder portion of the opening for the wiring pattern becomes tapered and tapered, the area occupied by the opening increases accordingly. Therefore, the integration density will be reduced by that amount.

In order to improve this, it is conceivable to adopt an anisotropic etching method instead of the conventional etching method.

This is an etching method that uses reactive ions, and in the example above, if this etching method is used to etch the openings in the wiring patterning of the insulating layer, the shoulders of the openings will not sag, i.e. It becomes possible to form an opening portion without forming a tapered shape.

However, although this etching method is advantageous in that it does not cause droop on the shoulders of the openings, during the subsequent vapor deposition for wiring patterning, the evaporation particles may damage the interior of the openings, especially on the sides thereof. It becomes difficult to adhere to the boundary between the wall surface and the bottom surface. Therefore, in some cases, the formed wiring is not continuous inside the opening,
Sometimes it is discontinued. Of course, even when anisotropic etching is not used, a similar problem occurs when a contact hole is formed so as not to cause droop in the shoulder portion of the opening.

(Problems to be Solved by the Invention) This invention provides that, in contact patterning for wiring, even if an opening is formed so that no droop is formed in the shoulder area for the purpose of reducing the area of the opening, The purpose is to reliably prevent wiring interruption within the opening.

(Means for Solving the Problems) This invention provides the following method: After opening a contact hole in an insulating film,
An insulating paint is applied within the opening and spun off so that the insulating paint becomes a mortar within the opening, which is then suitably heat treated and then isotropically coated. The insulating film made of the insulating paint is etched by an etching method or the like, so that the side surfaces of the openings are tapered upwardly by the insulating film made of the paint. After this, patterning for wiring is performed.

(Function) The side surfaces of the opening are tapered due to the insulating film, so when wiring patterning is performed here, the vapor-deposited metal particles will be reliably deposited along the tapered side surfaces.
Therefore, it is possible to reliably prevent the formed wiring from becoming discontinuous and being interrupted.

(Embodiment) An embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 indicates a semiconductor substrate, and 2 indicates a conductivity type region formed on the surface thereof, such as a base region, an emitter region, etc. Here, wiring patterning for the conductivity type region 2 will be explained as an example. During contact patterning for wiring, a first insulating film 3 made of a thin silicon oxide film or the like is formed on the surface of the semiconductor substrate 1. When a second insulating film 4 such as phosphorous glass made of silicon oxide doped with phosphorus is formed, a photoresist 5 is applied to the surface of the insulating film 4, and a contact hole pattern is formed thereon. Then, using this photoresist as a mask, the insulating film is etched. It goes without saying that the etching at this time is preferably anisotropic as described above. FIG. 1 shows the contact patterning as described above, in which numeral 6 indicates openings formed in the insulating films 3 and 4.

As mentioned above, when using the anisotropic etching jig, the width of the opening 6 can be made much narrower than when using isotropic etching. The steps up to now are not particularly different from conventional methods.

According to the present invention, after the photoresist 5 is removed, a coating 7 containing silicon oxide as a main component is formed inside the opening 6 so as to have a dovetail-shaped cross section. This target 7 is, for example, a silicon compound (RnSi (O
H) 4n) and additives (diffusion impurities, glass forming agents, organic binders) dissolved in an organic solvent are used. Actually, the solution may be applied to the surface of the insulating film 4 by a spin-on method. FIG. 2 shows this coating state.

After the coating 7 is fired, the coating 7 in the opening 6 is etched by isotropic etching, for example, dry etching. Specifically, for example, the coating 7 having the composition described above may be etched using a buffered fluorine-based etching solution. By this etching, the coating 7 is left in a tapered shape on the side wall of the opening 6, thereby forming the side surface of the opening 6 into a tapered shape. FIG. 3 shows this state.

As will be understood from now on, the coating 7 on the surface of the insulating film 4 is also removed by etching, but when the etching process is performed to make the side surface of the opening 6 tapered by the coating 7,
The shoulder portion of the opening 7 is also partially etched along this taper.

After this, wiring patterning is performed according to the usual technique. That is, a wiring material such as aluminum is deposited, and unnecessary portions are removed by etching to form a predetermined wiring (see FIG. 4). 8 indicates a metal film for wiring. At this time, since the side surface of the opening 6 is tapered by the coating 7, the vapor-deposited particles of the wiring material continue from the surface of the coating 7 to the bottom of the opening 6 without any interruption. It becomes coated. That is, the opening 6
This makes it possible to reliably prevent wiring breakage inside.

(Effects of the Invention) As detailed above, according to the present invention, even if the width of the opening for the contact hole for wiring is formed to be extremely narrow, the wiring within the opening can be made as compared to the conventional one. This has the effect that there is no possibility that the line will be interrupted and the line will become disconnected.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing manufacturing steps according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view showing an embodiment of the present invention. 1... Semiconductor substrate, 2... Conductivity type region, 3.4...
・Insulating film, 5... resist, 6... opening, 7...
・Insulating paint, 8...Metal film for wiring

Claims (2)

[Claims] (1) An insulating film is provided in an upwardly tapered shape on the side wall of an opening of a contact hole for wiring formed in an insulating film on the surface of a semiconductor substrate, so that the side surface of the opening is tapered, and A semiconductor device in which a metal film for wiring is placed inside an opening. (2) forming a contact hole opening in an insulating film on the surface of a semiconductor substrate by an anisotropic etching method;
a step of attaching an insulating paint to the side wall of the opening by spin-on to form a coating with a dovetail-like cross section;
etching the side surface of the opening into a tapered shape;
A method for manufacturing a semiconductor device comprising the step of forming a metal film for wiring by vapor deposition on the side surface of the tapered opening.