JPS5834919A - Etching method using plasma chemical reaction - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an etching method using plasma containing halogen compounds and/or halogen molecules.

Conventionally, a) plasma containing a halogen compound and/l or halogen molecules is a semiconductor such as silicon crystal, amorphous silicon, or silicon oxide.

It is generally known to be effective in etching a wide range of materials, including insulators such as silicon nitride, and metals such as aluminum and molybdenum. Some of the materials have already been put into practical use. However, in the case of plasmas containing halogen compounds and/or halogen molecules, etching and deposition may proceed simultaneously in the reactor, and in the case of etching, the gases released by the etching jig and/or the halogen compounds and/or There have been problems such as contamination of the substrate and reactor with plasma polymerized polymers caused by halogen molecules, etc., and that the amount of etching per unit time varies depending on the position on the substrate surface.

The present inventors have conducted various studies in order to solve the above-mentioned problems. As a result, in plasma containing halogen compounds and/or halogen molecules, the electron temperature (hereinafter abbreviated as Te) in the vicinity of the object to be etched exceeds a certain value. The present invention was completed based on the knowledge that only etching can be progressed by controlling the value of .

That is, the present invention is characterized in that in a plasma containing a halogen compound and/or halogen molecules, the electron temperature near the object to be etched is measured with a probe, and the cough electron temperature is controlled to a constant value of 50,000 or higher. The present invention provides an etching method using a plasma chemical reaction.

The Te1l method used in the present invention is based on the probe method.

For example, there are a single probe method, a two probe method, a three probe method, etc. In all methods, preferably a heated probe is used. (Japanese Patent Application Laid-Open No. 54-115574) In the present invention, the vicinity of the object to be etched means a portion located within a distance of 500 times the mean free path of a neutral gas from the object to be etched.

The etching gas used in the present invention is a gas containing a halogen compound and /17't a halogen molecule. Preferably CF4. CCI F, , CCI, F, .

cct, , cct, F, CH2F, C2F6
, C2F4, etc.

In the present invention, the electron temperature near the object to be etched is controlled to 50,000 or higher, preferably 60,000 or higher, according to the above-mentioned Te measuring method.

If it is less than 50,000, deposition may occur and the uniformity of etching will be lost, which is not preferable. The upper limit of the electron temperature is determined from an economical point of view, and is, for example, up to about 100,000.

In order to raise the electron temperature near the object to be etched to 50,000 K9 or higher in the present invention, conventional discharge physics techniques may be used. It is preferable to make adjustments to satisfy the above conditions by adjusting the discharge power, changing the spacing and shape of the electrodes, and changing the position and shape of the sample stage on which the object to be etched is placed, but this method is not limited. do not have.

The plasma reactor used in the present invention may be of a cylindrical type or a Pelger type and is not particularly limited. Further, the discharge electrode may be of an inductive type or a capacitive type, or may be a microwave discharge.

It can be high frequency discharge, low frequency discharge, or direct current discharge.
There are no particular restrictions.

The Te1l constant device used in the present invention generally has a circuit as shown in FIG.

In the figure, l is a probe, 2 is a voltmeter, 3 is an ammeter, and 4 is a variable voltage power supply.

In this circuit, the current-voltage characteristics of the two probes 1, 1 are measured, a curve as shown in FIG. 2 is obtained, and Te is determined from this curve. The theoretical formula is Ymand T, 0KUDA
(J, Phys Soc, Japan-11,
57 (1956)), T, DOTE (RIKEN Report,
53, 62-69 (1977)). You can ask for help more easily than with the cough method.

Take the two-probe method as an example! ) 1113, the present invention will be described in detail.

In Fig. 3, 1 to 4 are symbols corresponding to Fig. 1, 5 is a high frequency power source, 6 is a coil, 7 is an object to be etched, T is a reaction vessel, person is a gas inlet, and B is an exhaust port. . A gas containing a halogen compound and /l or halogen molecules is flowed into the reaction vessel T from the input A of the above apparatus, and the electron temperature near the object to be etched is controlled to a constant value of 50,000 or higher. Perform etching.

According to the present invention, uniform etching can be performed while preventing contamination due to deposition.

Next, examples of the present invention will be described.

Example 1 Amorphous silicon was etched using hexafluoroethane (CzFsJ). The reaction apparatus was a tubular flow type as shown in FIG. 3, and plasma was excited by induction using a coil.

Etching was carried out by controlling the Te near the substrate to 70,000 and +/-03,000 KIC:I. As a result, uniform etching was possible as shown in FIG.

That is, the etching rate is constant near the substrate.

Except for the above, engineering was performed under the same conditions and method as in Example 1. As a result, as shown in FIG. 4, uniform etching was possible.

Example 4 Etching was carried out under the same conditions and method as in Example 1 except that tetrafluoromethane (CF4) was used as the etching gas. As shown in FIG. 4, etching was uniform. was completed.

Comparative Example 1 Etching was carried out under the same conditions and method as in Example 1, except that Te in Example 1 was changed to 45,000K and ±03,000K. As a result, as shown in FIG. 5, uniform etching could not be performed and powder deposition occurred due to polymerization.

That is, the etching rate is non-uniform near the substrate.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing the double globe method, Fig. 2 is a current-voltage characteristic curve, Fig. 3 is a conceptual diagram showing a cylindrical plasma reactor, and Fig. 4 shows the etching speed in Examples 1 to 4. FIG. 5 is a diagram showing the etching rate in Comparative Example 1. 1... Probe, 2... Voltmeter,
3...Current needle, 4...-Variable voltage power supply, 5...High frequency power supply, 6...Coil, 7...Object to be etched , T----00 reaction vessel, A...gas inlet, B...exhaust port. Fig. 1 Fig. 2 77' Fig. 3 Fig. 4/ Fig. 5 A certain uncle's middle 1c) L30 constant distance (cm)

Claims (1)

[Claims] In a plasma containing a halogen compound and /l or halogen molecules, the electron temperature near the object to be etched is measured with a probe, and the electron temperature is controlled to a constant value of 50,000'' or more. Etching method using chemical reaction.