JPS63207151A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form an opening section with an upper taper into an insulating film under the state, in which the whole surface is purified, positioning a diffuse transmitting body into an optical path reaching to an opening section in a semiconductor chip from a light source for laser light and etching the diffuse transmitting body. CONSTITUTION:The layer of a material having an etching rate slower than an insulating film is deposited onto the insulating film, and an opening section 6 is shaped and used as a mask. The board of an optical diffusing body, the plane of incidence of light of which is flattened and the plane of outgoing of which has fine irregularities, is positioned to the upper section of the mask, laser lights 8a are applied from an upper section, the insulating film is etched in an isotropic manner up to approximately half of thickness thereof, the residual insulating film in the opening section 6 is etched in an anisotropic manner with the exception of the optical diffusing body, and a conductor layer under the insulating film is exposed. The mask is removed, the insulating film is gotten rid of through etching from the surface until the thickness of the insulating film etched in the isotropic manner is reduced by approximately half, and an upper layer wiring being connected to the conductor layer and extending on the insulating film is formed. Accordingly, the opening section with a tapered section can be shaped into the insulating film under the state in which the whole surface is purified.

Description

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

[Conventional technology]

As ICs have become more highly integrated in recent years, interconnections have become increasingly finer, and the quality of interconnect layers due to step coverage has become a problem.

As a countermeasure for this, when forming an upper wiring layer to connect an internal element electrode or conductor contact by opening a hole in the insulating film on the surface of a semiconductor substrate, a taper is provided at the circumference of the upper edge of the opening. , it is necessary to improve the step coverage of the upper wiring layer.

Conventionally, to provide this taper, a mask was formed on the silicon oxide film using photolithography technology, and then NF
The reactive active species produced by applying laser light to the 3+82 reactive gas adsorbs to the surface of the opening in the silicon oxide film, resulting in an anisotropic etching reaction. Sexual wet etching was performed.

[Problem that the invention seeks to solve]

The conventional semiconductor device manufacturing method described above uses a wet etching process to form a taper at the upper edge of the opening in the insulating film, which may cause contamination or damage to the surface of the insulating film, which is a disadvantage of etching using laser light. There has been a problem in that it is difficult to form an insulating film that can be cleaned and has little damage.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device in which an opening having a tapered portion can be formed in an insulating film while the entire surface is cleaned.

[Means for solving problems]

A method for manufacturing a semiconductor device according to the present invention includes a step of forming a conductor layer to serve as an electrode or wiring of a semiconductor element through an insulating film having an opening on a semiconductor substrate. A step of depositing a layer of material whose etching rate is slower than the insulating film on top of the insulating film and forming an opening to serve as a mask; and a light diffusing object whose light incident surface is flat and whose light exit surface has fine irregularities. A process of isotropically etching the insulating film to about half its thickness by placing the plate above the mask and irradiating laser light from above, and removing the light diffusing object and etching the remaining part of the opening. a step of anisotropically etching the insulating film to expose the conductor layer under the insulating film, and removing the mask so that the thickness of the isotropically etched insulating film portion is reduced to about half. and a step of forming an upper layer wiring connected to the conductor layer and extending over the insulating film.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(d) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining one embodiment of the present invention.

As shown in FIG. 1(a), a silicon oxide film 2, a polycrystalline silicon layer 4, and a silicon oxide film 3 with a thickness of about 1 μm are superimposed on the surface of a semiconductor substrate 1, and a photoresist layer 5 is formed on the top layer. do.

Openings 6 are formed in the photoresist layer 5 by photolithography.

Next, as shown in FIG. 1(b), the laser beam 8a is generated in a reactive gas such as NF3-1-H2 through the ground glass plate 7 with a flat incident surface, and the diffused transmitted light 8b is generated through the opening. irradiate.

Here, a part of the diffused transmitted light 8b from the frosted glass 7 away from the aperture 6 is irradiated downward to the left and right light beams connecting with the lower edge corners of the aperture 6 of the photoresist layer 5. The diffused transmission hole 8b of the laser hole 8a is irradiated not only directly below the opening of the silicon oxide film 3 but also in the lateral direction.

Irradiation with the laser beam 8a in this HF3+H2 gas is performed isotropically so that the depth of etching of the silicon oxide layer 3 is about half of the thickness and the edge of the opening 6 of the photoresist layer 5 is shaped like an eaves. Then, an opening having a middle bottom portion 3b and a taper 9 is formed in the silicon oxide film 3.

Next, as shown in FIG. 1(c), the ground glass plate 7 is removed, and the polycrystalline silicon layer is anisotropically etched by irradiating the laser beam 8a in HF3+H2 gas using the photoresist layer 5 as a mask. 4 exposed portions 10 are formed.

Next, as shown in FIG. 1(d), after peeling off the N5 (photoresistor), the surface of the silicon oxide film 3 is coated to a thickness of 5 to 3
After removing approximately 0% and leaving a portion of the taper 9 at the circumferential portion of the edge of the opening 6, an aluminum wiring layer 10 is deposited and formed.

As the etching in this example, the light irradiation steps shown in FIGS. 1(b) to 1(C) were performed in a reactive gas of NH3+H2, and the portions of the silicon oxide film 3 that were isotropically irradiated from the openings 6 were Although the above etching was carried out, optical sputtering may also be carried out using a direct laser beam 8a.

〔Effect of the invention〕

As explained above, in the present invention, by placing a diffusive transmitter in the optical path from the laser light source to the opening of the semiconductor chip and performing etching, the entire surface is kept clean while the upper part of the insulating film is etched. This has the effect of forming a tapered opening.

[Brief explanation of the drawing]

FIGS. 1A to 1D are cross-sectional views of a semiconductor chip shown in the order of steps for explaining an embodiment of the present invention. 1... Semiconductor substrate, 2.3... Silicon oxide film, 3
b... Middle bottom portion, 4... N-type polycrystalline silicon layer, 5...
... Photoresist layer, 6... Opening portion, 7... Ground glass plate, 8a... Laser light, 8b... Diffuse transmitted light,
9...Taper, 10...Exposed portion, 11...Aluminum wiring layer. 1, 1, Indication of the case, Patent Application No. 040712, 1988, 2
Title of the invention Semiconductor device manufacturing method 3, relationship to the amendment person case Application Person Place
5-33-1 Shiba, Minato-ku, Tokyo Name (423)
) NEC Corporation Representative: Tadahiro Sekimoto 4, Agent Address: Sumitomo Sanda Building, 37-8 Shiba 5-chome, Minato-ku, Tokyo 108 Detailed explanation of the invention in the revised specification. Amend "Additionally, on the upper surface of the formed cylindrical opening" in the third to fourth lines of page 3 of the description of the amendment to "prior to the formation of the cylindrical opening" .

Claims (1)

[Claims] In a method for manufacturing a semiconductor device, which includes a step of forming a conductive layer to serve as an electrode or wiring of a semiconductor element through an insulating film having an opening on a semiconductor substrate, a conductor layer having an etching rate lower than that of the insulating film is formed on the insulating film. Depositing layers of slow material;
A step of providing an aperture to form a mask, and placing a plate of a light diffusing object whose light entrance surface is flat and whose light exit surface has minute irregularities above the mask and irradiating the laser beam from above. isotropically etching the insulating film to about half its thickness; and anisotropically etching the remaining insulating film in the opening, excluding the light diffusing object, to remove the remaining insulating film under the insulating film. exposing the conductor layer and removing the mask;
a step of etching away the recording from the surface until the thickness of the isotropically etched insulating film portion is reduced to about half; and a step of forming an upper layer recording connected to the conductor layer and extending over the insulating film. A method for manufacturing a semiconductor device, comprising: