JPS6376436A - Etching method for silicon carbide - Google Patents

Abstract

PURPOSE:To improve the selective ratio against an SiO2 film and a silicon nitride film which are made etching rate and a stopper in comparison with the case wherein a conventional Freon series gas is used by using an SiCl4 + Cl2 series gas for the etching of SiC by RIE. CONSTITUTION:A mixed gas of SiCl4 and Cl2 is used as an etchant for the etching of silicon carbide by reactive ion etching. For example, a stopper film 13 such as silicon nitride is grown on a substrate 11, a contact hole is opened, an SiC film 12 is grown and patterned by providing a resist 15 on the film 12. This is mounted on a susceptor 22 in RIE equipment 21, an SiCl4 + Cl2 series gas which is an etchant gas is supplied in the RIE equipment 21 from an introduction pipe 25 and etched by exposing the SiC film 12 in plasma 28. In this case, SiCl4:Cl2 can be set within 10:1 and the pressure within the RIE equipment can be set within 0.01-0.05 Torr.

Description

[Detailed Description of the Invention] [Summary] In the etching of silicon carbide (SiC), the etching rate (etching speed) and 5i021 as a stopper
The selectivity to the R1 silicon nitride film is improved.

[Industrial application field]

The present invention relates to a method for etching SiC, and relates to a method using a chlorine-based gas, whereas conventionally a freon-based etchant gas (hereinafter simply referred to as gas) has been used for etching SiC.

[Conventional technology]

SiC exhibits high values of hardness and heat resistance (melting point 2800 degrees), so in the past it was used for special purposes such as abrasives, but as a semiconductor material it is not thermally or chemically stable. It is a material that has attracted attention because it can be used under high temperature and strong impact conditions, and because it has a large energy interval and can form a PN junction.

Conventionally, for etching SiC, SF6+lle,
Freon-based gases such as NF 3+ 02 and Ch + 02 are used. Etching of SiC will be explained with reference to FIG. 2. A stopper film is grown on the substrate 11, a contact hole is made, SiC is grown, and the SiC is patterned using lithography technology.
C by reactive ion etching (Reac-t
ive ion etching), the etching is stopped by the stopper film, and the portion surrounded by the dotted line 12 is etched.

[Problem that the invention seeks to solve]

In the RIH of SiC using the above-mentioned Freon gas, the etching rate is not higher than 1000 etching/min. Since SiC is a material with a stable structure as described above, an etching rate of this order is unavoidable, but the problem is the selectivity with the stopper. For example, the selectivity ratio of 5i02/SiC is smaller than 1, and in that case, the 5i02 film is The problem is that the 5iOz film is difficult to act as a stopper because it is etched more quickly than the SiC film. When silicon nitride is used instead of 5i02, the selection ratio is also less than 1, and even if silicon nitride is used, there is a problem as a stopper.

The present invention was created in view of these points.
In etching using C as a stopper such as conventional silicon nitride, the selectivity between the stopper and SiC is improved compared to Freon gas.

[Means for solving problems]

FIG. 1 is a sectional view of an embodiment of the present invention, in which 21 is an RIE device, 22 is a susceptor, 23 is a counter electrode plate, 24 is a grounded RF generator, 25 is a gas introduction pipe, and 26 is an exhaust system. , 27 is a cooling system, and 28 is a plasma.

In the present invention, in the RIE of SiC using a silicon nitride film or the like as a stopper, 5iCJ! is an etchant gas. ,, +C22 gas is introduced from the introduction pipe 25 through RI.
B is supplied into the device 21 to etch the SiC film 12.

[Effect]

The SiC film 12 is exposed to plasma 28 in the RIB device 21, and 5iCE! Each time u+Ce2 is introduced and activated, the 2 gas etches SiC.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

The inventor investigated the literature regarding etching of SiC, but could not find any literature indicating the use of gas other than Freon gas.

As mentioned above, satisfactory results were not obtained in experiments using Freon-based gas.

Therefore, an experiment was conducted using a new gas other than Freon-based gas, and the results described below were obtained using the above-mentioned chlorine-based gas.

5iCJ as an etchant gas! , 4+α2 gas, Si length q and CJI! The supply source No. 2 was connected to the gas introduction pipe 25 as shown in FIG. 1, and RIB was carried out under the following conditions. Note that a silicon nitride film was used as the stopper.

5iCf! +: 200 SCCM uncle 2:
505CCM Pressure crab inside RIE device 21 0.05 TorrRF
Power: 400 W (13,56 MHz) In the RIH of SiC performed under such conditions, the etching rate was 2000 etching/min, the selectivity to silicon nitride was 2, and the silicon nitride film could not act as a stopper. confirmed.

In addition, SiJ:Zheng 2 is within the range of 10:1, and RIB
It has also been confirmed that the pressure within the device can be set within the range of 0.01 to 0.05 Torr.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view showing etching of a SiC film. 1 and 2, 11 is a substrate, 12 is a SiC film, 13 is a stopper, 21 is an RIB device, 22 is a susceptor, 23 is a counter electrode plate, 24 is an RF oscillator, 25 is a gas introduction pipe, 26 27 is an exhaust system, 27 is a cooling system, and 28 is a plasma. Agent Patent attorney Akifusu Kuki Agent Patent attorney Yoshio Suga
figure

Claims (1)

[Claims] Silicon by reactive ion etching
Silicon tetrachloride gas (SiC) is used for etching carbide.
1_4) and chlorine gas (Cl_2) as an etchant.