JPS62214622A - Formation of recession in semiconductor wafer - Google Patents

Abstract

PURPOSE:To enable recession to be formed in accurate depth by a method wherein a thin film comprising a material different from Si is formed on the monitor part on an Si substrate to epitaxially grow an Si layer in specified thickness on the Si substrate including the thin film and then the monitor part is etched to form recessions. CONSTITUTION:A thin film 2 for detecting etching terminal is formed on an Si substrate 1. Later, an Si epitaxial growing layer 3 in specified thickness is formed on the Si substrate 1 using Si vapor growing technology. Next, an etching mask with etching holes are formed on the parts directly opposing to the Si substrate 1 while the other etching hole 5 for monitor etching is formed on the part above the thin film layer 2. Furthermore, anisotropic etching process of Si vapor growing layer 3 such as reactive ion etching etc. is performed. At this time, a terminal detector such as a mass analyzer or a spectroscopic analyzer can be used so that the signal intensity at the etching time may be changed to detect the etching terminal. Through these procedures, the recessions in the depth around the thickness of Si epitaxial growing layer 3 can be formed and evaluated assuming the etching time as an unit terminal detecting time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for accurately forming recesses of a required depth in a semiconductor wafer in a semiconductor device manufacturing process.

[Conventional technology]

In recent years, in the manufacture of semiconductor integrated circuit devices, with the progress of various technologies such as microfabrication, the degree of integration has been significantly improved. In particular, the technology for forming fine recesses in silicon (Si) substrates has been developed to meet the needs of semiconductor devices and to improve the degree of integration, and various experiments have been conducted.

[Problem that the invention seeks to solve]

However, in the prior art, when forming a recess from the surface of a semiconductor wafer, there is no suitable technique for accurately setting the depth to a desired value, and the problem is that the depth becomes inaccurate.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for forming a recessed portion in a semiconductor wafer 1c having an accurately desired depth.

[Means for solving problems]

In the recess forming method according to the present invention, a thin film of a substance different from St is formed on a portion of the monitor on a Si substrate, and an St layer of a known thickness is epitaxially grown on the Si substrate including the thin film on the monitor. The recesses are formed by etching the parts, and based on the data obtained, practical recesses are formed in other parts with precision.

[Effect]

In this invention, when etching a part of the monitor to form a recess as described above, the etching rate is determined based on the time it takes for the etching to reach the thin film of a substance different from Si and the known thickness of the epitaxially grown silicon layer. If you know this and use this to form practical recesses in other parts, you can obtain recesses with accurate depth.

〔Example〕

FIG. 1 (at to (cl) is a cross-sectional view showing the state at the main process steps of a method according to an embodiment of the present invention.
As shown in FIG. A material layer is formed that allows different information to be obtained from the case of only the special number 81 substrate.

This can be done using thin film detonation techniques or photoetching techniques. Thereafter, a Si epitaxial growth layer (3) (single-crystal Si layer) of a required thickness is formed on the St substrate (1) using Si vapor phase growth technology. At this time, a polycrystalline St layer may be formed on the thin film layer (2). That is, if the growth rate ratio and etching rate ratio of the single crystal St layer and the polycrystalline Si layer are investigated, there will be no problem.

Next, as shown in FIG. ) is formed as an etching mask (6) 8.

Next, as shown in FIG. 1, the Si vapor phase growth layer [3] is anisotropically etched by reactive ion etching or the like. If an end point detector such as a mass spectrometer or spectrometer is used at this time, under the determined anisotropic etching conditions, the etching of the Sl vapor phase growth layer (3) will progress and the thin film layer (2 ), the signal intensity during etching changes and the end point of etching can be determined, so this etching time is taken as the unit end point detection time and the etching depth is approximately the same as the thickness of the Si shrimp growth layer (3). It can be used for forming and evaluating concave portions.

Therefore, when forming a deep recess several times the thickness of the Si epitaxial growth layer (3) on the St substrate (1), this unit end point detection time is used to continuously etch for several times the thickness. All you have to do is deal with it.

When forming such a recess, the preliminary check of anisotropic etching and the actual processing are performed in the same cycle, which reduces the factors of variation between etching cycles. It can be said that the depth of the recess is also monitored based on the thickness and etching time.

Further, in the above embodiment, a thin film layer for monitoring was provided in one part of the substrate on which the recess was to be formed, but after a thin film layer for monitoring for etching end point detection was formed on the entire surface of the Si substrate.

A Si vapor phase growth layer (a fused recrystallized Si layer is also possible if necessary) is formed to the required thickness, and a recess is formed using a dedicated monitor equipped with a patterned etching mask. The effects of the present invention will be greatly enhanced if the target substrate 1c is processed simultaneously within the actual etching cycle.

Therefore, a thin film layer (which can be used to detect the end point of etching) is formed on the Si substrate, and Si vapor phase growth is performed to the required thickness to form a molten recrystallized Si layer on the 8i substrate. It is also effective when forming a concave portion, and in particular, if the etching end point detection area can be expanded as much as possible, the effect of the present invention will be increased.

〔Effect of the invention〕

As explained above, in this invention, a monitor having a thin film layer for detecting the end point of etching is used to detect the end point of etching of the St epitaxial growth layer thereon, to know the etching rate, and to detect the end point of etching of the St epitaxial growth layer thereon. Since etching formation of the desired recess is controlled, recesses with accurate depth can be obtained.

[Brief explanation of drawings]

FIG. 1 (al), FIG. 1 (bl), and FIG. 1 (fcl) are cross-sectional views C showing the state at the main process steps of the method according to an embodiment of the present invention. First, i) is a silicon substrate; (2) is a thin film 1i for detecting the end point of etching, (3) is a silicon epitaxial growth layer, and (6) is an etsonization mask.rlThe same reference numerals in the drawings indicate the same or equivalent parts.

Claims (2)

[Claims] (1) When forming recesses by etching on the surface of a semiconductor wafer to be processed, which is made by epitaxially growing silicon on a semiconductor silicon substrate, a thin film layer for etching end point detection made of a substance different from silicon is formed on the semiconductor silicon substrate. The monitoring wafer on which the silicon epitaxial growth layer is formed and the semiconductor wafer to be processed are etched in a required pattern, and the time from the time until the etching reaches the etching end point detection thin film layer on the monitoring wafer. A method for forming a recess in a semiconductor wafer, comprising knowing an etching rate and forming a recess of a desired depth in the semiconductor wafer to be processed based on the etching rate. (2) A method for forming recesses in a semiconductor wafer according to claim 1, characterized in that the monitor wafer is formed in a part of the semiconductor wafer to be processed.