JPS6170722A - Method of working semiconductor substrate - Google Patents

Abstract

PURPOSE:To accurately form both main surfaces of a semiconductor substrate without using an expensive device by opening a through hole at the substrate by anisotropically etching, and forming the both main surfaces of the substrate with the hole as a working reference position. CONSTITUTION:Silicon nitride films 2a, 2b of approx. 1,000Angstrom of thickness formed both main surfaces 1a, 1b of a silicon substrate 1 having 100 azimuth and 400mum of thickness are provided, and at least two positions of the film 2a are multiple-exposed by a projecting exposure unit to forma square hole 3 for anisotropically etching. The substrate 1 is dipped in KOH aqueous solution of approx. 40% of concentration to etch the substrate 1. At this time, since the etching velocity at the 100 surface is as fast as aprox. 400 times as compared with the 111 surface, the etching in the vertical direction to the main surface of the substrate 1 becomes positive to form a through hole 4. The etching amount in the direction parallel to the main surface of the substrate 1 of approx. 400mum of thickness is too small to be ignored in the working of approx. 1mu.

Description

TECHNICAL FIELD The present invention relates to a method of processing a semiconductor substrate, and more particularly to a method of processing both main surfaces of a semiconductor substrate.

Frontal technology When forming an integrated circuit on a semiconductor substrate, a circuit pattern is formed on the main surface of the semiconductor substrate. There are two methods for forming this circuit pattern: a light exposure method using a photomask and a direct exposure method using an electron beam. In the direct exposure method using an electron beam, a registration mark for positioning is formed in advance on the main surface of the semiconductor substrate by etching or the like, and the mark is scanned with an electron beam to perform positioning when exposing the circuit pattern of each layer. In addition, in the light exposure method using a photomask, a target mark for multilayer alignment is provided along with the circuit pattern to be formed within the photomask. The two are aligned on the main surface of the semiconductor substrate.

Therefore, if it is desired to improve the degree of integration by forming circuit patterns on both branches of the semiconductor substrate, it is necessary to form positioning marks on both branches. At this point, a possible method for forming positioning marks with high precision on both branches of the semiconductor substrate is to physically drill through holes in the semiconductor substrate and use these through holes as positioning marks. . However, in such a method, chips of the semiconductor substrate are generated at a temperature of 10°C, and when these chips adhere to the processed surface of the semiconductor substrate, the scratches generated when the chips are removed from the processed surface require a viscosity of 10 μm or less. In some cases, it cannot be ignored. Furthermore, it is difficult to drill through holes with an accuracy of 10 μl or less by this physical means.

Therefore, after superimposing two photomasks with different processed surfaces, one of these two photomasks is moved relatively parallel to the surface of the photomask to set the position, and then the one A possible method is to form positioning marks on both sides by exposing the semiconductor substrate to light while sandwiching the semiconductor substrate between the two photomasks by moving the photomasks vertically. However, such a method has the disadvantage that it requires a complicated and effective double-sided exposure device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a processing method that allows high precision processing of both branches of a half-zero board without using expensive equipment.

The semiconductor substrate processing method according to the present invention forms a film on both branches of the semiconductor substrate that is less susceptible to anisotropic etching than the semiconductor substrate, and forms a film on one of the two branches of the semiconductor substrate. A portion of the film is removed to avoid exposing the main surface of the semiconductor substrate so that openings are formed in at least two locations in the film, and the semiconductor substrate is anisotropically etched to form through holes. It is characterized in that both branches are machined using the relative positions of the through holes J3 on both main surfaces as the machining reference positions.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 and FIG. 2 show half i3f,
FIG. 3 is a cross-sectional view of a kO plate, in which all common parts are designated by the same reference numerals. In Figure 1, plane orientation (100)
, both branches 1a of the silicon substrate 1 with a thickness of about 400 μm,
CV D (Chemical Vapor) to lb
A thickness of 100 mm formed by the Depoition method etc.
There are about 0 silicon nitride films 2a and 2b. At least two portions of the film 2a are subjected to multi-exposure by projection exposure type cutting to form rectangular openings 3 for anisotropic etching. The silicon substrate 1 is etched by immersing it in a KOl-1 aqueous solution having a concentration of about 40%. At this time, since the etching speed on the (100) plane is about 400 times faster than that on the (111) plane, etching in the direction perpendicular to the main surface of the silicon substrate 1 becomes dominant, and As shown in the figure
IjJ through holes 4 are formed. This etching f in the direction parallel to the main surface of the silicon substrate 1 with an rl radius of about 400 μm
il is so small that it can be ignored in machining with an accuracy of about 1 micron. Therefore, the main surfaces 1a, l of the silicon substrate 1
The positional deviation between the openings 5a, 5b and 5c, 5d formed as shown in FIGS. 3(A) and 3(B) is extremely small. Therefore, these openings 58-5
If a circuit pattern is formed on the main surfaces 1a and 1b of the semiconductor substrate using d as a processing reference mark for positioning, then the main surface 1
What is the relative position between the circuit patterns formed on a and 1b? :S accuracy will be set.

In addition, in the above example, U is used as an anisotropic etching liquid.
It was assumed that a KOH aqueous solution with a concentration of about 40% was used, and that the silicon substrate 1 had a thickness of about 400 μm and a nitride film was formed on both branches.
The concentration of the solution, the thickness of the silicon substrate 1, and the quality of the film formed on both branches may be any one of them, as long as the CC1 holes are formed by anisotropic etching.

Effects of the Invention As detailed above, in the method of processing a semiconductor substrate according to the present invention, a through hole is formed in the semiconductor substrate by anisotropic etching, and the holes of the appropriate amount are used as semi-positions to process both main parts of the semiconductor substrate. Since the surface is machined, it is possible to improve the precision of the processing position on both main surfaces of the semiconductor substrate and process both main surfaces to a high Mlfl without using an expensive headpiece. .

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a half-circular 9F board that has gone through each step in the process of forming processing reference marks for positioning according to the present invention, and FIG. FIG. 2 is a plan view of a semiconductor substrate having a JJ 'l'' mark.

Claims (2)

[Claims] (1) A film that is less susceptible to anisotropic etching than the semiconductor substrate is formed on both main surfaces of the semiconductor substrate, and at least two of the films formed on one of the two main surfaces of the semiconductor substrate A portion of the film is removed to expose the main surface of the semiconductor substrate so that an opening is formed at a location, and then the semiconductor substrate is etched with a large anisotropy of etching rate in a direction perpendicular to the main surface. A method of processing a semiconductor substrate, comprising forming a through hole by etching, and processing both main surfaces of the semiconductor substrate using the relative positions of the through holes on both main surfaces as a processing reference point. . (2) The method of processing a semiconductor substrate according to claim 1, wherein the step of removing a portion of the film is performed by multiple exposure.