JPH0669357A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To easily perform the control of the shape and dimension of a through hole to be opened in an interlayer insulating film, and shorten the term of construction. CONSTITUTION:This manufacture includes the process of applying photoresist 3 on the interlayer insulating film 2 provided on lower-layer wiring 1, the process of performing the first exposure, where the focus and the quantity of light are adjusted, for the photoresist 3, in the place to open a through hole, the process of developing the photoresist 3 and removing the area being exposed in the first and second exposure, and the process of etching a tapered through hole 4 by anisotropically etching the interlayer insulating film 2, with this photoresist 3 as a mask.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a tapered through hole for electrically connecting an upper wiring and a lower wiring.

[0002]

2. Description of the Related Art In a conventional semiconductor device, a tapered through hole is provided in an interlayer insulating film for electrically connecting an upper wiring and a lower wiring. An example of a conventional manufacturing method of such a tapered through hole is shown in FIG. First, as shown in FIG. 2A, an interlayer insulating film 2 is deposited on the lower wiring 1 by the CVD method once or twice to about 8000 Å, and then a photoresist 3 for patterning is applied. Next, as shown in FIG. 2B, the photoresist 3 in the through-hole forming portion is opened by the photolithography technique.

Then, as shown in FIG. 2C, a mortar-shaped tapered portion is formed on the interlayer insulating film 2 by wet etching or isotropic dry etching using the photoresist 3 as a mask. Then, as shown in FIG. 2D, the through holes are formed in the interlayer insulating film 2 by dry etching using the photoresist 3 as a mask as it is. Thereafter, although not shown, the upper wiring is sputtered and the upper wiring is patterned by the photolithography technique.

[0004]

In such a conventional method of manufacturing a semiconductor device, wet etching (or isotropic dry etching) is used when forming a tapered through hole, so that the variation in etching rate is reduced. The shape and size of the parts were easily affected, and it was difficult to control these shapes and dimensions as designed. In addition, there is a problem that the construction period becomes long because it is a two-step etching process of wet etching and dry etching. An object of the present invention is to provide a method of manufacturing a semiconductor device in which the shape and size of a through hole can be easily controlled and the construction period can be shortened.

[0005]

According to the present invention, there is provided a step of applying a photoresist on an interlayer insulating film provided on a lower layer wiring, and a step of adjusting a focus and a light amount to the photoresist at an opening portion of a through hole. The step of performing the exposure of 1;
A step of performing a second exposure on the same portion under normal conditions, a step of developing the photoresist to remove the regions exposed by the first and second exposures, and a step of using the photoresist as a mask The method includes anisotropically etching the interlayer insulating film and forming a tapered through hole.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention in the order of steps. First, as shown in FIG. 1A, a film thickness of 8000 is formed on the lower layer wiring 1.
An interlayer insulating film 2 of about Å oxide film is grown by the CVD method, and then a photoresist 3 is applied. Next, the photoresist 3 is exposed by an exposure device. As a first exposure step, by using a technique such as defocusing or reducing the light amount as compared with the case of the normal exposure condition, the process shown in FIG.
As described above, the mortar-shaped region is exposed to the photoresist 3, and then the second exposure step is performed under normal conditions according to the design value of the through hole. Then, when the photoresist 3 is developed, as shown in FIG. 1C, the shallow mortar-shaped portion is removed by the first exposure step on the surface side, and the second exposure step is performed over the entire thickness. The tapered aperture window 3a is opened by removing the portion of the through hole as designed.

Then, using this photoresist 3 as a mask, the etching shape of anisotropic dry etching depends on the photoresist shape, and the etching rate ratio is 1 :.
By etching the inter-layer insulation film 2 to 1 as shown in FIG. 1 (d), the mortar portion 4a is opened on the front surface side and the equal-diameter portion 4b is opened over the entire thickness in the same manner as the photoresist shape. A perforated tapered through hole 4 is formed. After that, though not shown, this through hole 4
An upper layer wiring is sputtered in a region including a and patterned by a photolithography technique. As described above, by controlling the shape of the photoresist 3 in the exposure and development steps, it becomes possible to form the tapered through hole by one dry etching.

It should be noted that, by adding a step of baking the photoresist 3 at a high temperature of about 140 ° C. after the developing step of the photoresist 3 of FIG. 1C, the side surfaces of the tapered portion and the through hole portion are made smoother. Can be

[0009]

As described above, according to the present invention, by performing the first and second exposures on the photoresist, a mortar-shaped opening having a uniform diameter is formed over the entire surface, Since the interlayer insulating film is anisotropically etched using this photoresist as a mask, the tapered through hole can be controlled accurately. In addition, a tapered through hole can be formed by one-time etching, which has the effect of shortening the construction period.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the manufacturing method of the present invention in the order of steps.

FIG. 2 is a cross-sectional view showing a conventional manufacturing method in process order.

[Explanation of symbols]

 1 Lower layer wiring 2 Interlayer insulating film 3 Photoresist 4 Tapered through hole 4a Mortar part 4b Equal diameter part

Claims (1)

[Claims] 1. A semiconductor device having a multilayer wiring structure in which a lower wiring and an upper wiring are electrically connected to each other through through holes formed in an interlayer insulating film, and a photoresist is formed on the interlayer insulating film after forming the interlayer insulating film. A step of applying, and a step of performing a first exposure in which the focus and the amount of light are adjusted on the photoresist at the opening portion of the through hole,
A step of performing a second exposure on the same portion under normal conditions, a step of developing the photoresist to remove the regions exposed by the first and second exposures, and a step of using the photoresist as a mask A method of manufacturing a semiconductor device, comprising a step of anisotropically etching an interlayer insulating film and forming a tapered through hole.