JPS6376435A - Dry etching control method - Google Patents

Abstract

PURPOSE:To improve the uniformity of etching by controlling the etching conditions due to the results of monitoring the plasma light emission intensity at the center and the periphery of a material to be etched. CONSTITUTION:In dry etching equipment 1 wherein etching is carried out by using low temperature gas plasma 5, the etching conditions are controlled by the results of monitoring the plasma light emission intensity at the center and the periphery of a material 3 to be etched. For example, the emission spectrum 7 of the specific chemical species in the plasma 5 is condensed by a condenser lens 8 through an observation window 4, light intensity is converted to an electric signal 13 by a photodetector 12 after spectrully analyzed in a spectroscope 11 by passing an optical fiber 9 and the electric signal is processed by control equipment 14. The lens 8 and the optical fiber 9 are attached to scanning equipment 10, which moves in all directions by the signal from the control equipment 14. A high-frequency power source 6 is so adjusted to make the light emission intensity ratio of the center and the end of a wafer within a set range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dry etching method used for manufacturing semiconductor devices, etc., and particularly relates to a dry etching control method suitable for controlling etching uniformity. .

[Conventional technology]

In a dry etching apparatus using parallel plate electrodes, the electric field strength on the electrode side where the material to be etched is placed differs between the center and the outer periphery. For this reason, there is a problem in that the etching rate of the material to be etched differs between the central part and the peripheral part, resulting in non-uniform etching. Therefore, it is necessary to control the electric field distribution in order to obtain uniform etching, but since it is difficult to directly monitor the electric field distribution, the problem is what kind of observation data should be used to perform this control. . The commonly used etching control is not to obtain uniformity of etching, but merely to observe the plasma using, for example, emission spectroscopy to determine the end point of etching.

Incidentally, there is a method for monitoring plasma during etching, for example, Japanese Patent Laid-Open No. 57-207850.

[Problem that the invention seeks to solve]

Conventionally, no consideration has been given to preventing the occurrence of etching defects due to changes in the plasma state, and thus problems have arisen in the etching process of sea urchins, which are becoming increasingly larger in diameter.

An object of the present invention is to provide a dry etching control method that improves etching uniformity.

[Means for solving problems]

The above purpose is to monitor the local luminescence intensity in the plasma,
This is achieved by controlling the plasma conditions and etching state based on the monitoring results.

[Effect]

Among the luminescent chemical species in plasma, there are chemical species that have a correlation with electric field distribution. Therefore, by monitoring the distribution of the emission intensity of this chemical species in the plasma and controlling the plasma conditions using the monitored electric field, it is possible to uniformly control the electric field distribution. As a result, the uniformity of etching is improved.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is an overall configuration diagram of the dry etching control device. In FIG. 2, a pair of parallel plate electrodes 2.2' are arranged in the dry etching device 1, high frequency power is supplied from a high frequency power supply 6 to the lower electrode 2°, and the electrode is placed 2° above the lower electrode. The etched material 3 is etched by the plasma 5. The emission spectrum 7 of a specific chemical species in the plasma 5 passes through the observation window 4 and is focused by a condensing lens 8, passes through an optical fiber 9, enters a spectroscope 11, and is separated into spectra. It is converted into a signal 13 and processed by a control device 14. A lens 8 and an optical fiber 9 for condensing the emission spectrum 7 in the plasma 5 are attached to a scanning device 10.
It moves forward, backward, left and right in response to signals from the control unit 114, and can illuminate localized strong winds within the plasma 5. The local luminescence intensity within the plasma 5 is controlled by the control device 1.
Processed in 4.

FIG. 1 is a control processing 7o chart in the control device 14. In this control process, as shown in Figure 3+a+ and [b], based on the correlation between the emission intensity shown by the solid line and the electric field intensity shown by the dotted line, the emission intensity ratio between the center and edge of the wafer is within a certain range. At certain times (Figure 3 (a)), the electric field strength is assumed to be normal, and when it is outside the setting range (Figure 3 (b)).
) is considered abnormal.

First, in step 1 of FIG. 1, the luminescence distribution is determined by continuously measuring the signal input via the optical fiber 9. Next, the luminescence intensity ratio A of the electrode center part and the electrode peripheral part is determined. In step 2) and step 3, the intensity ratio is compared with the set value B.

If the determination result in step 30 is A■B, that is, if it is determined that the intensity ratio A is normal, the execution of this program is ended without adjusting the high frequency power source 6.

If the judgment result in step 3 is A)B, that is, the luminescence intensity at the center of the electrode is stronger (too much) than at the periphery of the electrode, proceed to step 4 to reduce the high frequency power, and then proceed to this program. Terminates execution.

If the judgment result in step 50 is A (B), that is, the emission intensity at the periphery of the electrode is stronger than at the center of the electrode (as shown in FIG. 3(b)), proceed to step 5 and increase the high frequency power. Click (and exit this program.

In this way, in this example, the radio frequency power is determined by the emission intensity ratio. Because of this control, the electric field distribution becomes uniform and the uniformity of etching is improved.

〔Effect of the invention〕

According to the invention, it is possible to monitor the electric field distribution in the plasma without contact, which makes it possible to control the electric field distribution.
Etching uniformity can be improved and productivity can be improved.

[Brief explanation of the drawing]

Fig. 1 is a 7o-chart of a dry etching control method according to an embodiment of the present invention, Fig. 2 is an overall configuration diagram of a dry etching control device, and Fig. 3 +4) and Tb) are plasma diagrams in normal and abnormal conditions. It is a graph showing monitoring results. 1- Dry etching device 3... Material to be etched, 6... High frequency power supply, 8
...Condensing lens, 9.-Optical fiber, 10.-Scan device, 14.-Control device. Representative Patent Attorney Masaru Ogawa Male 6th Luck 1st “Az” %5 [F] ←Wafer 4 Renchu-U=High L-

Claims (1)

[Claims] 1. A dry etching control method in a dry etching apparatus that performs etching using low-temperature gas plasma, which comprises controlling the etching state based on the results of monitoring the plasma emission intensity at the center and periphery of the material to be etched.