JP3336283B2 - Plasma etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma etching method for etching an oxide film using plasma generated in a vacuum vessel (for example, plasma generated by a magnetic field and a microwave electric field). The present invention relates to a plasma etching method suitable for obtaining a selectivity.

[0002]

2. Description of the Related Art Conventional plasma etching techniques are described in, for example, Hitachi Review Vol. 71 (1989); 5, P
As described in 33-38, a quartz discharge tube is provided in a waveguide for propagating microwaves, plasma is generated in the discharge tube by the action of an external magnetic field and a microwave electric field, and etching of a substrate is performed by the plasma. Is what you do.

[0003]

In the prior art, it is not always enough to consider the influence on the etching characteristics of the members constituting the vacuum vessel for generating plasma, particularly on the selectivity with the underlying silicon film. There was a problem that the etching rate of the oxide film was reduced in order to obtain a selectivity with respect to the underlying silicon film.

An object of the present invention is to provide a plasma etching method capable of suppressing a decrease in an etching rate of an oxide film in etching an oxide film and obtaining a high selectivity with respect to an underlying silicon film.

[0005]

In order to achieve the above object, a plasma etching method of the present invention converts a gas containing fluorine enclosed in a vacuum vessel into a plasma, and prepares a sample having an oxide film provided on a silicon film. A plasma etching method in which the sample is placed on a sample stage so as to be etched by the plasma, wherein the sample is placed in the vacuum vessel.
Provide an area around the sample placed on the table including the electrode cover.
Wherein by controlling the supply amount of the different RF power from the plasma generation to be fed, to adjust the ion incident energy incident on the electrode cover, the release of substances containing carbon or silicon is released from the electrode cover with Characterized in that the amount of the plasma generated is controlled independently of the amount of the plasma generated, and the amount of the fluorine ions or the fluorine atoms in the plasma is reduced by the reaction of the controlled release amount of the substance with the fluorine ions present in the plasma. It is.

[0006]

When silicon carbide is used as a member constituting a vacuum vessel and high-frequency power is applied to the silicon carbide, silicon (silicon) or carbon, which is a component of silicon carbide, is sputtered. In addition, carbon fluoride is generated by a reaction with fluorine ions present in the plasma. The reaction with the sputtered silicon (silicon) or carbon reduces fluorine ions or fluorine atoms, which are reactive species of silicon, and decreases the etching rate of the underlying silicon film. In addition, carbon fluoride generated by the reaction with fluorine ions is a reactive species that suppresses etching of the underlying silicon film and selectively etches the oxide film. Therefore, using silicon carbide in the members constituting the vacuum vessel, to suppress the decrease in the etching rate of the oxide film by applying a high-frequency power to the silicon carbide, the base sheet
A high selectivity with recon can be obtained.

[0007]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a schematic sectional view of a microwave plasma etching apparatus. The microwave plasma etching apparatus will be described with reference to FIG. The microwave oscillated from the magnetron 1 propagates through the waveguide 2 and is guided into the vacuum vessel 4 via the discharge tube 3 made of quartz. The etching gas 6 supplied from the etching gas supply device (not shown) is turned into plasma by the magnetic field generated by the magnetic field generating solenoid coil 5 and the microwave electric field. The substrate 8 mounted on the mounting electrode 7 is etched by the plasma. The pressure at the time of etching is controlled by a vacuum exhaust device (omitted in the figure). The energy of the ions incident on the substrate 8 is controlled by the high-frequency power supplied to the mounting electrode 7 from the high-frequency power supply 9. Further, silicon (silicon) or carbon as a constituent component is sputtered on the electrode cover 10 made of silicon carbide provided on the mounting electrode 7 by the high frequency power. In addition, carbon fluoride is generated by a reaction with fluorine ions present in the plasma.

Table 1 shows the etching rate of the oxide film and the selectivity of the underlying silicon when CHF ₃ is used as an etching gas and alumina and silicon carbide are used for the electrode cover 10.

[0010]

[Table 1]

Microwave power 1 kW Pressure 1.3 Pa High frequency power 150 W

[0012]

According to the present invention, a decrease in the etching rate of the oxide film can be suppressed, and a high selectivity with respect to the underlying silicon film can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a microwave plasma etching apparatus according to the present invention.

[Explanation of symbols]

3: discharge tube, 5: solenoid coil, 7: mounting electrode, 8
... board, 9 ... high frequency power supply, 10 ... electrode cover.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshie Sato 794, Higashitoyoi, Kazamatsu-shi, Yamaguchi Pref. Hitachi, Ltd. Kasado Plant (56) References JP-A-3-177020 (JP, A) JP-A Heihei JP-A-3-73524 (JP, A) JP-A-2-65131 (JP, A) JP-A-4-37124 (JP, A) JP-A-60-103619 (JP, A) JP-A-62-47130 (JP, A A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/3065 H05H 1/46

Claims (1)

(57) [Claims] 1. A method of plasma-forming a gas containing fluorine sealed in a vacuum vessel, and mounting a sample having an oxide film provided on a silicon film on a sample stage so as to be etched by the plasma. And before
Around the sample placed on the sample stage placed in the vacuum vessel
The use of the plasma generation is supplied in a region including the electrode cover by controlling the supply amount of the different radio frequency power, the electrode mosquito
The energy of ions incident on the bar is adjusted, and the amount of carbon or silicon-containing material released from the electrode cover is controlled independently of the amount of plasma generated. A plasma etching method characterized in that fluorine ions or fluorine atoms in the plasma are reduced by a reaction between the plasma ions and fluorine ions present in the plasma.