JPH0525172B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for easily determining the chemical reaction ability of an etching solution for etching an oxide layer of a semiconductor wafer.

Conventional examples and their problems Current semiconductor devices using silicon as the basic material are
They are manufactured by using silicon oxide films in various forms. Therefore, a process of etching the oxide film is often used. Control of the etching solution used here is an important element of process control.

Normally, the process is often proceeded without accurately examining the reaction ability of the etching solution.

In that case, the etching speed of the oxide film changes depending on the reaction capacity of the solution. However, in order to stabilize the process and manufacture semiconductor devices with good reproducibility, it is necessary to adequately control the etching solution.

Purpose of the Invention The present invention provides a method for chemically etching an oxide film.
It provides a method by which the performance of the etching solution can be determined.

Structure of the Invention The present invention provides an etching ability monitor pattern of an etching solution formed in steps with different thicknesses of oxide films on a semiconductor substrate, and etches the etching ability monitor pattern by etching the etching ability monitor pattern. This is an etching solution testing method characterized in that the processing ability of the etching solution is determined by detecting a change in the interference color that occurs, and thereby the processing ability of the etching solution can be determined quickly and reliably. , it becomes easier to manage the etching process of the oxide film on the semiconductor substrate.

Description of examples The present invention will be explained in detail by way of examples.

Oxide films 2 of different thicknesses formed on a silicon substrate 1 as shown in the cross-sectional view of FIG. 1 exhibit interference colors depending on the thickness of the oxide film. The interference color produced by white light reflected from the interface of an oxide film is used to determine the thickness of the oxide film in a normal process environment.
For example, it is known that the interference colors of oxide films of 1000 Å and 2500 Å are purple and red, respectively. In the present invention, oxide films having different thicknesses are formed in a stepwise manner, and the interference colors generated in each step are utilized. By immersing this substrate in the etching solution used in the process for a certain period of time, substrates with different oxide film thicknesses are etched according to the chemical reaction ability of the etching solution. The oxide film etching speed over a certain period of time can be easily and accurately confirmed by continuously observing changes in interference color on a single substrate.

As shown in FIG. 2, if the etching solution has sufficient chemical reaction ability, the trend A can be observed. Here, it is possible to compare a plurality of different oxide films, so it is possible to accurately see the chemical reaction ability. The trend B indicates that the liquid capacity is deteriorating, and it becomes possible to immediately decide to judge the liquid capacity.

Effects of the Invention That is, in the present invention, since the thickness of the oxide film is formed in a stepped manner, changes in a plurality of interference colors caused by etching of the oxide film can be observed simultaneously and at extremely close positions.

This means that it has a plurality of monitors and can be used as a highly accurate etching monitor. In addition, since the present invention forms an oxide film having multiple thicknesses, even if one or two of them are damaged for some reason and do not show a normal interference color, other normal oxidation By using a membrane and detecting its interference color, the ability of the etching solution can be accurately determined.

As described above, in the present invention, since oxide films of different thicknesses formed on a single semiconductor substrate have different interference colors, the interference colors change greatly when the etching speed differs, so the etching time is monitored using a sensor. It also becomes easier.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a semiconductor substrate having different oxide film thicknesses according to the present invention, and FIG. 2 is a characteristic diagram showing the relationship between changes in oxide film thickness and etching time. 1...Silicon substrate, 2...Oxide film.

Claims (1)

[Claims] 1. An etching ability monitor pattern of an etching solution formed in steps with different thicknesses of oxide films on a semiconductor substrate is prepared, and a change in interference color caused by etching of the etching ability monitor pattern is measured. 1. A method for inspecting an etching solution, comprising: detecting the etching solution to determine the throughput of the etching solution.