JPH0551670B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a reactive ion etching method and a reactive ion etching method that can improve its selectivity and productivity, and can suppress the occurrence of an overhang phenomenon. The present invention relates to an ion etching method and apparatus.

[Technical background of the invention and its problems]

In general, MoSi ₂ film is one of the high-melting point metal silicides that is highly expected to be used as an electrode and wiring material for VLSI and has been extensively studied. Since this MoSi ₂ film is used for VLSI, it naturally has to be microfabricated, and for this reason, the applicant
For a long time, we have been researching and developing _the method of etching this MoSi ₂ film using a reactive ion etching method (hereinafter simply referred to as etching). We have been considering etching the material using a material (which is considered to be a material).

By the way, when using this method, the vapor pressure of MoCl ₅ has a very strong temperature dependence, and a change of 40°C causes a change of about 10 times the vapor pressure. That is, when etching is performed by increasing the temperature of the substrate to be etched, the etching rate of MoSi ₂ changes greatly, as shown in the graph of FIG. On the other hand, the etching rate of the resist that serves as a mask during etching has almost no temperature dependence.

From this, from the viewpoint of etching selectivity between MoSi ₂ and resist and productivity, it is considered desirable to perform etching while raising the temperature of the substrate to be etched. Therefore, when the applicant conducted etching by raising the substrate temperature, it was confirmed that both the selectivity and productivity were improved.

However, it was found that when over-etching was performed, an overhang phenomenon occurred in the MoSi ₂ film, as shown in FIG. That is, in FIG. 2, 1 is the substrate and 2 is the material to be etched.
MoSi ₂ film, 3 is a resist which is a mask,
The left end surface of the MoSi ₂ film shows an overhang phenomenon in which the upper part protrudes more forward than the lower part.

It has been confirmed that such an overhang phenomenon appears more prominently as the temperature of the substrate 1 is higher, and almost disappears when the substrate temperature is lowered.

As described above, from the viewpoint of selectivity and productivity, it is necessary to raise the substrate temperature, but from the viewpoint of overhang, it is necessary to lower the substrate temperature, and mutually contradictory temperature conditions are required.

[Purpose of the invention]

In view of these points, it is an object of the present invention to provide a reactive ion etching method and apparatus thereof, which can improve selectivity and productivity, and can effectively prevent the occurrence of overhang phenomena. With the goal.

[Summary of the invention]

This object is achieved according to the invention by etching the material to be etched at two electrode temperatures, high and low, with a temperature difference of 30° C. or more.

[Embodiments of the invention]

FIG. 3 shows a first embodiment of the present invention, in which an etching electrode 12 and an over-etching electrode 13, which are electrically insulated from the container 11, are installed in a vacuum container 11.
A substrate 14 to be etched is placed on the substrates 2 and 13. Further, each electrode 12, 13 is provided with a high frequency power source 15, 16 and a temperature regulator 17, 18 for controlling the temperature of each electrode 12, 13, respectively. Then, the substrate to be etched 14
is first placed on a hot etching electrode 12 by a transport mechanism (not shown) to perform etching, and then transferred onto an over-etching electrode 13 to perform over-etching.

Next, the operation of the embodiment described above will be explained.

For etching, the substrate 14 to be etched is first taken into the vacuum chamber 11 from the outside by a transport mechanism (not shown) and placed on the etching electrode 12 whose temperature is controlled at 60.degree. Then, approximately 90% of the MoSi ₂ film thickness is etched.

Next, the substrate 14 to be etched is moved and placed on the overetching electrode 13 whose temperature is controlled at 30 DEG C., and overetching is performed to complete the etching process.

According to this embodiment, since etching is performed at a high electrode temperature and then overetching is performed at a low electrode temperature, it is possible to improve the etching selectivity between MoSi ₂ and resist and productivity. Moreover, the overhang phenomenon occurring in the MoSi ₂ film can be effectively prevented.

In the above embodiment, one etching electrode 12 was provided for one overetching electrode, but the number of etching electrodes 12 was changed so that the etching time and overetching time could be balanced. You can increase it.

FIG. 4 shows a second embodiment of the present invention, in which an electrode 19, on which a substrate to be etched 14 is placed on the upper surface, is electrically insulated from the vacuum container 11. It is located. As shown in the figure, this electrode 19 includes a high frequency power source 20, a temperature controller 21 that controls the temperature of the electrode 19 to 60°C, and a temperature controller 2 that controls the temperature of the electrode 19 to 30°C.
2 are respectively provided, and both the temperature regulators 21 and 22 are adapted to be switched by three-way knobs 23 and 24.

Next, the operation of the embodiment described above will be explained.

When etching, first
3 and 24 to control the temperature of the electrode 19 to 60° C. using the temperature controller 21. And this electrode 19
The material to be etched 1 is transported by a conveyance mechanism (not shown above).
Place 4.

After approximately 80% of the MoSi ₂ film thickness on the material to be etched 14 has been etched, the three-way tips 23 and 24 are switched to the temperature controller 22 side, and over-etching is performed with the temperature of the electrode 19 at 30°C, completing the etching process. let The graph in FIG. 5 shows this state.

Also, in this embodiment, as in the first embodiment described above, it is possible to improve the etching selectivity between MoSi ₂ and resist and productivity, and to effectively suppress the overhang phenomenon that occurs in the MoSi ₂ film. can be prevented.

〔Effect of the invention〕

As explained above, in the present invention, since etching is performed at two or more different electrode temperatures, the etching selectivity and productivity between MoSi ₂ and resist can be improved, and moreover, it is possible to improve the etching selectivity and productivity of the MoSi ₂ film. This can effectively prevent the overhang phenomenon.

[Brief explanation of drawings]

Figure 1 shows the reactive ion etching method.
A graph showing the relationship between the etching rate of the MoSi ₂ film and the electrode speed. Fig. 2 is an explanatory diagram showing the overhang phenomenon that occurs in the MoSi ₂ film. Figs. 3 and 4 each show examples of the present invention. The cross-sectional view, FIG. 5, is a graph showing the relationship between etching time and electrode temperature in the etching method using the apparatus shown in FIG. 11... Vacuum container, 12... Etching electrode,
13... Over-etching electrode, 14... Material to be etched, 17, 18, 21, 22... Temperature controller, 19... Power supply, 23, 24... Three-way socket.

Claims (1)

[Scope of Claims] 1. A reaction in which a material to be etched is placed on an electrode placed in a reactive gas, a voltage is applied to the electrode to cause a gas discharge, and the material to be etched is etched by the discharge gas. 1. A reactive ion etching method, characterized in that the material to be etched is etched at two electrode temperatures, high and low, with a temperature difference of 30° C. or more. 2. The reactive ion etching method according to claim 1, wherein the material to be etched is etched at the high electrode temperature and then over-etched at the low electrode temperature. 3. In a reactive ion etching apparatus in which a material to be etched is placed on an electrode placed in a reactive gas, a voltage is applied to the electrode to cause a gas discharge, and the material to be etched is etched by the discharge gas. . A reactive ion etching device, characterized in that the electrode is constituted by a plurality of electrode bodies, and the temperature of the electrode body can be set to two temperatures, a high temperature and a low temperature, with a temperature difference of 30° C. or more. 4 Claim 3, characterized in that the temperature of the electrode can be adjusted according to the etching process.
Reactive ion etching apparatus as described in .