JPH04171817A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To perform selective etching on the surface of a semiconductor substrate so as to reduce the etching time of the substrate by irradiating the semiconductor substrate with a large-size laser beam in a gaseous atmosphere through a mask which partially intercepts the laser beam. CONSTITUTION:A mask 2 is provided on the way of a collimated large-size argon laser beam l. The argon laser beam 3 passed through the mask 2 is made incident to a silicon substrate 4 placed in a Cl2 gas atmosphere. Thus the same etching pattern as the pattern of the mask 2 is formed on the substrate 1. Therefore, the device for etching the semiconductor substrate can be simplified, because the etching time can be reduced and the need of a complicated scanning mechanism can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to optically assisted etching using a laser beam.

[Conventional technology]

In reactive ion etching using gas plasma, radicals (thermal molecules, electrons, ions, etc.) in the reaction chamber inherently have a wide energy distribution, so it is difficult to limit the reaction formula and it is difficult to understand the elementary processes. . Changing external parameters (discharge pressure, gas pressure, applied bias, etc.) can in some cases completely change the reaction process within the system, so optimal conditions must be found empirically.

Whether the target is at negative self-bias potential or at ground potential, collisions by positive ions are inevitable due to the plasma potential (always positive with respect to ground potential). Due to the energy distribution of the incident ions, irradiation damage due to high-energy particles is inevitable.

On the other hand, in "photochemical reactions" called laser-assisted etching, photoexcited etching, or photoenhanced etching, by selecting the excitation wavelength, only specific molecules in the reaction gas can be excited, or the degree of excitation can be controlled depending on the type of molecule. Therefore, selectivity for chemical reactions can be realized.

The photodissociation process of molecules is controlled by their light absorption spectra, so if the light source is monochromatic, the number of chemical reactions will not increase much. The controllability of the reaction process is better than with plasma reactions.

Furthermore, since reactive molecules are ionized by one-photon or multi-photon absorption, reactive ion etching with less damage may be realized by controlling the energy of photogenerated ion species using an external electric field.

Regarding laser anost etching using conventional technology,
This will be explained with reference to FIG.

A laser beam 6 is irradiated onto a silicon substrate 4 placed in C12 gas.

By scanning the laser beam 6, N Si+2C12→S
The area hit by the laser is etched by the iCi 4 reaction.

[Problem to be solved by the invention]

In conventional laser assisted etching, a laser beam with a spot size of 5 to 20 OA and 1 mφ is scanned over the entire surface of a silicon substrate (wafer), so there is a problem in that the process required for each wafer is long.

[Means to solve the problem]

The method of manufacturing a semiconductor device of the present invention selectively etches the surface of a semiconductor substrate by irradiating the semiconductor substrate with a large-diameter laser beam through a mask that partially blocks the laser beam in a gas atmosphere.

〔Example〕

A first embodiment of the present invention will be described with reference to FIG.

A mask 2 is located in the middle of a collimated large-diameter argon laser beam 1.

The argon laser beam 3 that has passed through the mask 2 is C72
The light is incident on the silicon substrate 4 placed in the gas.

In this way, an etching pattern identical to the pattern drawn on the mask 2 can be formed on the silicon substrate 4.

Next, a second embodiment of the present invention will be described with reference to FIG.

As in the first embodiment, a mask 2 is located in the middle of a large-diameter argon laser beam 1 that is collimated to 4.

The argon laser beam 3 that has passed through the mask 2 is SiH
4 enters a silicon substrate 4 covered with a silicon dioxide film 5 in the gas.

In this way, the silicon dioxide film 5 can be etched on the silicon substrate 4 in accordance with the pattern of the mask 2.

〔Effect of the invention〕

Etching time can be shortened by combining a large diameter laser beam with a mask that blocks it.

Furthermore, a complicated scanning mechanism is not required, and the apparatus can be simplified.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a first embodiment of the present invention, Fig. 2 is a sectional view showing a second embodiment of the invention, and Fig. 3 is a sectional view showing laser assisted etching according to the prior art. . 1... Large diameter argon laser beam, 2... Mask, 3... Incident argon laser beam, 4...
Silicon substrate, 5... silicon dioxide film, 6... argon laser beam.

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor device, comprising selectively etching a surface of a semiconductor substrate by irradiating the semiconductor substrate with a large-diameter laser beam through a mask in a gas atmosphere.