JPS6046538B2 - Etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry etching method, and in particular to plasma etching used in the manufacture of semiconductor devices, an etching method improved to increase the etching speed and suppress deterioration of resist material. There is something about it.

Conventional plasma etching will be explained using a capacitance method as an example with reference to FIG. 1, which is a sectional view of an apparatus. In Fig. 1, 1 is an etching chamber, 2 is an electrode provided facing the outer wall of the etching chamber 1, 3 is a gas inlet, 4 is an exhaust port, 5 is a sample stage, and 6 is for etching semiconductor wafers, etc. This is a sample of A halogen compound such as carbon tetrafluoride (CF) is introduced into the etching chamber 1 through a gas inlet 3, and the inside of the etching chamber 1 is maintained at a low pressure while being evacuated from an exhaust port 4 with a vacuum pump.

Then, a high frequency of 13.56 MH2 is applied to the electrode 2 to generate plasma, and the sample 6 placed in the etching chamber 1 and partially protected by an organic resist material or the like is selectively etched. Compared to wet etching, such plasma etching causes less side etching and eliminates the problem of waste liquid treatment. The speed of cal etching varies depending on the material to be etched, and the etching speed is generally slow, which poses a problem in terms of workability. The present invention has been made in view of the above points, and involves generating plasma in a mixed gas atmosphere of carbon tetrafluoride and nitrogen monoxide.
Improves etching speed in plasma etching,
Furthermore, the purpose is to suppress deterioration of organic resist materials used in selective etching.

The present invention will be described below. FIG. 2 is an embodiment of the present invention, which explains plasma etching using the capacitance method.

1, 2, 4, 5, and 6 in FIG. 2 are the same as those explained in FIG. 7 and 8 are nitric oxide (No) and 4 respectively
There is an inlet for introducing carbon fluoride (CF0).

First, during etching, the exhaust port 4 of the etching chamber 1 is
No. and CF from gas inlet ports 7 and 8 while exhausting the air.
.

is introduced at the same time, plasma is generated by applying a high frequency of 13.56 MH2 to the electrode 2, and the sample 6 such as a silicon wafer is etched. FIG. 3 shows the results of investigating the relationship between the etching rate and NO concentration when silicon wafers are etched by such a method.

The power source used was 13.56MHz, 1300W. As is clear from this Figure 3, the etch rate is CF
As the mixing ratio of NO to 4 increases, the rate becomes faster and reaches a maximum around the NO concentration of about 40 mol%, at which time NO
It can be seen that the concentration has increased approximately 20 times compared to when the concentration was 0 molar. Further, at this time, the etching rate of the organic resist material that covered a part of the sample also increased, but the degree of increase was small and it was able to sufficiently serve as a mask for selective etching. Note that the plasma generation method can also be applied to the inductance method or any other plasma generation method, and although a silicon wafer has been described as a sample to be etched, it can also be applied to a silicon compound.

As described above, in the present invention, when etching silicon or a silicon compound, plasma is generated in a mixed gas atmosphere of carbon tetrafluoride and nitrogen monoxide, so that the role of the resist material is eliminated. This has the effect of increasing the etching rate without causing any damage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an apparatus for explaining conventional plasma etching, FIG. 2 is a schematic diagram of an example of an apparatus for explaining plasma etching of the present invention, and FIG. 3 is a schematic diagram of an apparatus for explaining conventional plasma etching. 1 is a diagram relatively showing the results of investigating the relationship between etch rate and NO concentration according to the present invention.

In the figure, 1 is an etching chamber, 2 is an electrode, 4 is an exhaust port,
7 is an inlet for nitrogen monoxide (NO), and 3 and 8 are inlets for carbon tetrafluoride (CF4).

Claims (1)

[Claims] 1. An etching method characterized by generating plasma in a mixed gas atmosphere of carbon tetrafluoride (CF_4) and nitrogen monoxide when etching silicon or a silicon compound.