JPS635532A - Plasma cleaning process - Google Patents

Abstract

PURPOSE:To shorten the cleaning time by means of making use of the fluctuation in light emitting spectrum intensity for detecting end point in case of gas plasma cleaning process. CONSTITUTION:The cleaning end point can be detected by end point detectors 6, 9 in terms of the light emitting spectrum intensity of reactive product in case of plasma cleaning process or the material consumed by the reaction to be fluctuated at the cleaning end point. Furthermore, the cleaning end point can be detected by the same wavelength using CO light emitting spectrum in the same wavelength as that used for detecting etching end point of silicon oxide film making use of the deceasing intensity of CO light emitting spectrum in case of O2 gas plasma cleaning process.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is useful for dry etching used in the manufacture of electronic components such as semiconductor devices, when deposits in a vacuum chamber are removed using gas plasma. The present invention relates to a plasma cleaning method.

Conventional technology In conventional dry etching equipment, 02 gas plasma cleaning is performed in order to remove deposits and reduce dust in the vacuum chamber. This is done using the time settings.

Problems to be Solved by the Invention However, with the above-mentioned time setting, it is unclear whether the removal of deposits in the vacuum chamber has been completed, and the reproducibility of etching becomes a problem. Furthermore, for time settings,
Under conditions where the reproducibility is significantly reduced due to deposits when the time is set for a long time, there is a problem in that productivity deteriorates due to the high frequency of 02 gas plasma cleaning.

Means for Solving the Problems The first aspect of the present invention is that in dry etching using a fluorocarbon gas, when cleaning deposits in a vacuum chamber with gas plasma, the end point is determined by a change in the intensity of the emission spectrum. It performs detection.

Further, a second aspect of the present invention is c that is used for detecting the end point of dry etching of a silicon oxide film.

The end point of etching is detected using the emission spectrum intensity, and the end point of O2 gas plasma cleaning is also detected by monitoring the CO emission spectrum intensity of the same wavelength.

Function The first aspect of the present invention is that during plasma IJ-ning, the emission spectrum intensity due to reaction products between deposits in the vacuum chamber and gas plasma, or substances consumed by the reaction, is reduced by IJ-ning. The end point is detected from the change at the end point of the process.

Further, in the second aspect of the present invention, a CO emission spectrum having the same wavelength as that used for detecting the end point of etching of a silicon oxide film is used as the emission spectrum of the first invention, and the CO emission spectrum is used for O22 gas plasma cleaning. The end point is detected at the same wavelength by utilizing the fact that the spectral intensity becomes weaker.

EXAMPLE A first example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a dry etching apparatus equipped with an end monitor for 02 cleaning in a first embodiment of the present invention. In the figure, 1 is an upper electrode, 2 is a silicon wafer as an object to be etched, 3 is a lower electrode, 4,
7 is quartz glass.

The end point detection device consists of a photodiode 6.8 equipped with an interference filter and end point detection devices 6, 9 each comprising an amplification and control circuit. Further, 10 is a vacuum chamber equipped with exhaust means.

In the dry etching process, a silicon oxide film (hereinafter referred to as Si○2) formed on silicon Uni-No-2 is etched with CHF3.
60 sheets were etched using a mixed gas of C2F6 and C2F6.

Next, Ko2 gas plasma cleaning was performed.

02 Wavelength during gas plasma cleaning: 7.2 nm
Figure 2 shows the change in the intensity of the emission spectrum of the ○ atom. Curve a in the figure represents the change in emission spectrum intensity of 0 atoms, ■ is the starting point of cleaning, and ■ is the ending point. As a result of detecting the end point of 02 gas plasma cleaning using the end point detection device and checking the inside of the chamber,
It was confirmed that the yellow-brown deposits had been removed.

In addition, regarding the end point detection of Q2 gas plasma cleaning using CO, after etching 60 sheets of St○2 formed on silicon wafer with a mixed gas of CHF3 and C2F6, the CO emission spectrum intensity at a wavelength of 483.5 nm was obtained. Figure 2 shows the changes in .

The curves in the figure represent changes in the CO emission spectrum,
■ indicates the cleaning start point, and ■ indicates the end point. As a result of detecting the end point of 102 gas plasma cleaning using the end point detection device and checking the inside of the chamber, it was confirmed that the yellow-brown deposits were removed as in the end point detection using 0 atoms.

Although only the 02 gas plasma cleaning after S102 etching has been described above, the present invention can also be applied to 02 gas plasma cleaning after etching Si3N4°Sl. Detection of the end point of O2 gas plasma cleaning is as follows:
We used the wavelength 777.2 nm of 0 atoms, but there are other wavelengths of 777.2 nm.
94.8 nm can also be used.

For Go, a wavelength of 483.6 nm was used, but other wavelengths of 451.1 nm, 619.8 nm,
661,○en.

60B, Onm, 662. Can also be used with Onm.

Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 shows a dry etching apparatus equipped with an end monitor for 02 cleaning in a second embodiment of the present invention. In the figure, 4a is quartz glass, and the end point detection device is a photodiode 6a equipped with an interference filter.
and a circuit 6a for amplification and control.

Etching of silicon oxide film on silicon wafer 1
02 gas plasma cleaning was performed after each sheet. Etching of the silicon oxide film was performed using CHF3 and 02 mixed gas at 0.3 Torr and 3 COW, and 0 gas plasma cleaning was performed using 02 gas at 0.6 Torr and 3 COW.
It was held at 2 COW.

The end point detection device etches the silicon oxide film and
2 gas plasma cleaning end point at wavelength 483.5a
It was detected from the emission spectrum intensity of CO at m. Figure 4 shows the change in C○ emission spectrum intensity at a wavelength of 483.6 am.

Curves a, b, and c are d during etching of the oxide film.

e is the wavelength 483n during O2 gas plasma cleaning
There is a change in the CO emission spectrosil intensity of m.

Etching was performed on 50 sheets, and it was possible to detect the end point with good reproducibility, and at the same time, the reproducibility of the etching rate was also good, and dry etching with excellent uniformity could be performed.

Effects of the Invention As described above, the first invention of the present invention is capable of shortening the cleaning time by introducing changes in emission spectrum intensity to detect the end point during cleaning using gas plasma, and also makes it possible to reduce the time required to complete the removal of deposits. Since etching is performed after checking, it has the unique effect of improving the reproducibility of etching.

Furthermore, according to the second aspect of the present invention, the same waveform as the CO emission spectrum used for detecting the end point of the silicon oxide film is used for detecting the end point during 02 plasma cleaning. The end point detection device can shorten the cleaning time and improve etching reproducibility.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the dry etching apparatus used in the first embodiment of the present invention, FIG. 2 is a diagram showing the change in CO emission spectrum intensity over time during 02 gas plasma cleaning, and FIG. FIG. 4 is a schematic diagram of the dry etching apparatus used in the second embodiment of the present invention, and FIG. 4 is a diagram showing changes over time in the intensity of the CO emission spectrum in the second embodiment of the present invention. 4.4a, 7... quartz glass, 5,5a, 8.
...Photodiode, 8.6a, 9...
- End point detection device, 10... vacuum chamber. Name of agent: Patent attorney Toshio Nakao and one other person. r open (t)

Claims (5)

[Claims] (1) A plasma cleaning method characterized in that, in dry etching using a fluorocarbon-based gas, the end point of plasma cleaning for removing deposits in a vacuum chamber is detected by monitoring changes in emission spectrum intensity. (2) The plasma cleaning method according to claim 1, wherein the plasma cleaning is O_2 gas plasma cleaning. (3) Claim 1 is the plasma cleaning method according to Claim 2, wherein the emission spectrum is an O atom emission spectrum. (4) The plasma cleaning method according to claim 1 or 2, wherein the emission spectrum is a CO emission spectrum. (5) In dry etching using fluorocarbon gas, CO
O_2 performed by monitoring emission spectrum intensity changes and removing deposits in the vacuum chamber
A plasma screening method characterized in that the end point of gas plasma cleaning is detected by monitoring the same change in CO emission spectrum intensity as the end point of the dry etching of the silicon oxide film.