JPS61220332A - Etching end point judging equipment - 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 [Field of Application of the Invention] The present invention relates to an etching end point determination device, and in particular to an etching end point determination #l1 suitable for determining the etching end point of a wafer that is etched in a dry process.
It concerns ll.

[Background of the invention]

Conventional devices, such as those described in Japanese Unexamined Patent Publication No. 59-61036, compare the plasma light intensity that decreases with the completion of the etching reaction and the plasma light intensity that increases with the completion of the etching reaction. Methods for detecting the end point are known.

However, when trying to automatically compensate for the decrease in the amount of light due to an increase in the amount of processing of the material to be etched (for example, a wafer) using an electrical signal amplification circuit, in a high-speed etching process, the automatic compensation may not be completed in time for the detection of the end point pattern. This creates a problem in which reliable etching end point determination cannot be made.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an etching end point determination device that can perform etching end point determination with high reliability even in a high-speed etching process.

rSummary of the Invention] What has not yet been invented is a lighting means for collecting plasma light generated during the dry etching process of a sample, and a light for selectively extracting plasma light of a specific wavelength from the plasma light collected by the ti means. a wavelength selection means, a photoelectric nipping means for converting the amount of plasma light having the characteristic wavelength into an electric signal, an electric signal conversion means for converting the electric signal into a digital data value, and inputting the digital data value and a preset value. a comparison calculation means for performing a comparison calculation with the determined determination reference value to determine an end point, and at least two end point determination systems including at least the photoelectric conversion means, the electric signal conversion means, and the comparison calculation means are arranged in parallel. By performing end point determination and automatic output correction using separate end point determination systems, etching end point determination can be performed with high reliability even in high-speed etching processes. It is something.

[Embodiments of the invention]

An uninvented embodiment will be explained with reference to FIGS. 1 to 3.

In FIG. t7J1, in the processing chamber 10, a counter electrode 11 and a sample electrode 12 are arranged inwardly facing each other in the vertical direction. The counter electrode 11 is grounded. Sample type fi1
2 is connected to a high frequency power source 13. A gas introduction nozzle 14 is provided on the top wall of the processing chamber 10 . A gas introduction system (not shown) is connected to the gas introduction nozzle 14 . Processing room 1o! To borrow.

An exhaust nozzle 15 is provided. A vacuum exhaust system (not shown) is connected to the exhaust nozzle 15.

In the figure, an opening 16 is formed in the side wall of the processing chamber 10, corresponding to the space between the counter electrode 11 and the sample t*tz.

The opening 16 is provided with a transparent window lamp serving as a lighting means. The optical wavelength selection means 1, for example, the spectroscopes 21 and 21 are set to correspond to the beauty of the transmission window.

The photoelectric conversion means in this case are photoelectric converters 22.22' and amplifiers connected respectively to the photoelectric converters 22.22'.

n'. The photoelectric converter z, 22' is
They are connected to spectrometers 21 and 21', respectively. The electrical signal conversion means includes A/D converters 24, 24'''Ch, which are connected to amplifiers 23, 23', respectively.

Comparison calculation circuit 25.251, which is a comparison calculation means, A/
N terminals are connected to D converters 24 and 24' respectively. In this case, the spectrometer 21, 21', the photoelectric converter 22, 22', the amplifier Z (, 23', the A/D converter 24, 24', and the comparator circuit 25, 25') Judgment system ff
Two systems of i and ff are provided in parallel. The sequencer (equipment) gives a discharge start command to the high frequency power supply 13 and also gives an end point judgment start command to the comparison calculation circuit 25゜3.
Also, at the same time as the processing is completed, the comparison operation circuit 5. It has a function of receiving an end point detection signal from δ' and issuing a discharge stop command to the high frequency power source 13.

In FIG. 1, the sample mold [! The image is drawn with the surface to be processed facing upward. Thereafter, the inside of the processing chamber 10 is evacuated under reduced pressure and gas is introduced. This gas is turned into plasma by the Takaoka 1 discharge.
The surface of the wafer to be processed is etched by this plasma in a dry process. Plasma light is generated during this process.

Through a transmission window, this plasma light is e.g.

It reaches spectrometer B, where plasma light of a specific wavelength is selected and extracted. The amount of plasma light of this specific wavelength is converted into an analog electrical signal by a photoelectric converter n, and then amplified by an amplifier Z. This amplified analog electrical signal is converted into a digital data value by an A/D converter and inputted to a comparison calculation circuit 5. The comparison calculation circuit 5 performs a comparison calculation between the input digital data value and a preset input determination reference value, and as a result, an end point determination is performed. The etching end point determination in the high-speed knee I:F-ing process is performed as follows.

In FIGS. 1 to IJS diagrams, the end point of etching for the nth wafer is determined by the end point determination system, and automatic output correction in this case is performed by the end point determination system. In order to accurately correct the output level of the monitor waveform 51 to the standard level 52 in FIG. 3, a time corresponding to the correction section 61 is required. In a high-speed etching process, the etching time is short, and most of the etching time is required for correction. but.

In this case, as shown in Figure 2 and Figure 1g3, the end point determination and automatic output correction can be separated and performed in parallel, so even if the etching time is short, the end point determination interval ω in the monitor waveform (source) can be However, the end point can be determined with high accuracy without being hindered by the divine correct section 61. The etching end point of the n+1th wafer is determined by the end point determination system 3'.
In this case, automatic output correction is performed in the end point determination section. In this way.

By using the end point determination system %, 26' to alternately switch between etching end point determination and automatic output correction, the end point can be determined with high precision even when a large number of wafers are subjected to continuous error kinging in a high-speed etching process. It can be carried out. Switching in this case is performed by a command from the sequencer (9).

Fig. 4 shows another embodiment of the present invention, and the difference from Fig. 1 showing the above-mentioned embodiment is that the end point determination system 27.
PIk amplifier 23.23' and A/D converter 24.24'
and a comparison calculation circuit 25, 25', and a spectrometer 4. The point is that the photoelectric converter ρ is shared. In FIG. 4, the same devices and the like as in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted.

In the unimplemented example, a spectrometer is used as compared to the above-mentioned example.

Since the photoelectric converter is shared, the IJIlpt configuration can be simplified and the cost can be reduced.

In the above embodiment, the photoelectric conversion means is constituted by an optical W converter and an amplifier, but it goes without saying that these may be integrated. Furthermore, an analog filter may be used to smooth analog electrical signals, or a digital filter may be used to smooth digital data values.

〔Effect of the invention〕

As explained above, in the present invention, the end point determination and the automatic output correction are performed in separate end point determination systems, so that the etching end point can be determined with high reliability even in a high-speed etching process. There is an effect.

[Brief explanation of drawings]

mi diagram is a block configuration diagram showing an embodiment of the etching end point determination system according to the invention, FIG. 2 is a monitor diagram of the end point determination system in FIG. The monitor diagram and IJJ diagram for another end point determination system are block diagrams showing other embodiments of the etching end point determination apparatus according to the present invention. (9)...Transmission window, 21.21'...
Spectrometer, 22.22'...Photoelectric converter, Z3,
2B'...Amplifier, 24.24'...
A/D converter, 2), 25'... Comparison calculation circuit, 26. ff5', 27r'...End point judgment system O/Figure tail 21.21'-----Sumiku 22.22'...-Photoelectric texture 23.23'-m--Amplifier 26.26″・-Shogi row 2nd figure n, n:--One bottle PI Lin

Claims (1)

[Claims] 1. Lighting means for collecting plasma light generated during etching of a sample by dry process; light wavelength selection means for selectively extracting plasma light of a specific wavelength from the plasma light collected by the means; A photoelectric conversion means converts the amount of plasma light into an electric signal, an electric signal conversion means converts the electric signal into a digital data value, and performs a comparison operation between the digital data value and a preset input determination reference value. An etching end point determination system comprising at least two end point determination systems in parallel, each comprising a comparison calculation means for determining an end point, and comprising at least a front light distribution electrical conversion means, the electrical signal conversion means, and the comparison calculation means. Device.