JPH0346327A - Dry etching - Google Patents

Abstract

PURPOSE:To reduce a dependence property of an etch rate of a silicon dioxide film on a contact hole diameter by a method wherein a selective ratio of the silicon oxide film to a resist is lowered in such a way that an aspect ratio of an opening part does not become large. CONSTITUTION:A selective ratio of silicon dioxide film to a resist is lowered in such a way that an aspect ratio of an opening part does not become large; thereby, a drop in an incident efficiency of ions is reduced. That is to say, an etching rate of the silicon dioxide film is proportional to the incident efficiency of the ions; when the incident efficiency is lowered, an etch rate is lowered; the incident efficiency of the ions depends on the aspect ratio; when the aspect ratio becomes large, the incident efficiency is worsened; although an etching rate of substratum Si depends on the incident efficiency of the ions, a CF polymer is hard to stick when the incident efficiency is worse and the etching rate of the Si is increased unlike the silicon oxide film. Consequently, it is possible to restrain a selective ratio to Si from being lowered when the incident efficiency of the ions is increased. Thereby, a dependence property of the selective ratio of the silicon oxide film and the substratum Si on a contact hole diameter (aspect ratio) is reduced.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an oxide film dry etching technique using a resist as a mask material used in the VLSI manufacturing process, and particularly relates to an oxide film dry etching technique that uses a resist as a mask material for the VLSI manufacturing process, and particularly relates to the selection ratio between silicon oxide film and silicon. The present invention relates to a dry etching method for reducing contact hole diameter dependence.

<Prior art and problems to be solved by the invention> Concerning etching to form fine contact holes using resist as a mask material.

The etching rate of silicon oxide film depends on the aspect ratio of the resist pattern.The higher the rare aspect ratio, the slower the etching rate.
The degree of dependence increases as the etching time increases. Furthermore, as the etching progresses, the aspect ratio increases, so the etching rate further decreases. Base Si
The etching rate depends on the aspect ratio of the resist+silicon oxide film, and increases as the rare aspect ratio increases, and the selectivity of the silicon oxide film to Si decreases as the aspect ratio increases. FIG. 2 shows the dependence of the SiO2 etch rate on the contact hole diameter when the aspect ratio of the resist pattern is changed, and FIG. 3 shows the dependence of the 5i-c phthalate on the contact hole diameter when the aspect ratio of the resist pattern is changed.

The present invention is aimed at solving the above-mentioned problems that occur during the VLSI manufacturing process, and is aimed at solving the above-mentioned problems that occur during the VLSI manufacturing process.
The present invention provides a method for increasing a contact hole in which the selectivity ratio with respect to the contact hole diameter (aspect ratio) is less dependent.

Means for Solving the Problems> The etching rate of a silicon oxide film is proportional to the ion incidence efficiency, and as the incidence efficiency decreases, the etching rate decreases. As shown in FIG. 2, the ion incidence efficiency depends on the aspect ratio, and as the aspect ratio increases, the incidence efficiency deteriorates.

The processing rate of the Si substrate also depends on the ion incidence efficiency, but unlike the silicon oxide film, if the incidence efficiency is poor, C
As the F polymer adheres, the etching rate of <<Si increases. From this, by increasing the ion incidence efficiency, it is possible to suppress a decrease in the selectivity to Si.

The dry etching method of the present invention is an etching method characterized by reducing the decrease in ion incidence efficiency by reducing the selectivity of the silicon oxide film to the resist to prevent the aspect ratio of the opening from increasing. It is.

Example An embodiment of the present invention will be described below.

Figure 4 shows the dependence of the etch rate of the silicon oxide film on the contact hole diameter when a 1.7 μm resist is patterned on a 0.6 μm silicon oxide film and etching is performed under the conditions of selectivity to resist of 1 and 2. Show your gender. Similarly, the fifth
The figure shows the etch rate of Si, and the figure in the figure shows the selectivity to Si.

Under the condition of selectivity of 1.0, the etch rate of the silicon oxide film and the resist are the same, so there is little change in the aspect ratio due to the progress of etching (Figure 6), so the dependence of the etch rate of the silicon oxide film on the contact hole diameter. is smaller than that in FIG. 2, and the decrease in the selectivity to Si is also small.

By further reducing the selectivity to resist.

It is possible to obtain conditions that are less dependent on the contact hole diameter.

<Effects of the Invention> As explained above, according to the present invention, changes in the aspect ratio are small by reducing the selectivity of the silicon oxide film to the resist to prevent the aspect ratio of the opening from becoming thick. Therefore, the dependence of the etch rate of the silicon oxide film on the contact hole diameter is smaller than that shown in FIG. 2, and the drop in selectivity to Si in the casing can be reduced, thereby improving the yield of VLSIs.

[Brief explanation of drawings]

Figure 1 shows the dependence of the Si selectivity on the contact hole diameter when the resist selectivity ratio is changed, and Figure 2 shows the contact hole diameter dependence of 5iO1 efthylate when the aspect ratio of the resist pattern is changed. Figure 8 shows the dependence of the Si etch rate on the contact hole diameter when the aspect ratio of the resist pattern is changed, and Figure 4 shows the dependence of the contact hole diameter of the 5in2 etch rate on the resist pattern when the selectivity to resist is changed. Figure 5 is a diagram showing the dependence of Si etch rate on contact hole diameter when the resist selectivity ratio is changed, and Figure 6 is a diagram showing the contact hole diameter dependence when the resist selectivity ratio is changed.
FIG. 3 is a diagram showing changes in aspect ratio due to the progress of etching in each case.

Claims (1)

[Claims] 1. In a silicon oxide film etching method in which a contact hole is processed using a resist as a mask material using a reactive ion etching device, the ion incidence efficiency is improved by lowering the selectivity of the silicon oxide film to the resist to reduce the aspect ratio. A dry etching method characterized by reducing the dependence of the selectivity between a silicon oxide film and silicon on a contact hole diameter by increasing the selectivity ratio between a silicon oxide film and silicon.