JPH0722401A - Plasma etching apparatus - Google Patents

Abstract

PURPOSE:To achieve the improvement of detecting accuracy and monitoring at all the time at an in-process level for the leakages from a vacuum system and a gas feeding system and to prevent the defective product caused by leaking. CONSTITUTION:A light-emission analyzer 20 can separate the light emitting wavelength in plasma. A high-frequency power supply 13, an evacuation system and a gas control system are controlled with an operation control part 24 by using the output signal from a comparison judging circuit 22, which judges the presence or absence of the leakages in a vacuum container and a gas feeding system based on the result of the output signals from a memory circuit 23 and a light-emission analyzer. In the memory circuit 23, the preset plasma light-emission intensity ratio and light-emitting wavelength of gas are stored. Thus, the improvement of the detecting accuracy of the minute leakages in a vacuum container 1 and the gas feeding system and the monitoring at all the time at an in-process level are achieved. This is effective for early detection of abnormality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma etching apparatus, and in particular, in a semiconductor wafer manufacturing process, a resist pattern selectively exposed by a photomask is used as a mask for plasma-forming various thin films such as an underlying insulating film and wiring metal. The present invention relates to a plasma etching apparatus that performs an etching process by using.

[0002]

2. Description of the Related Art Conventionally, in a plasma etching apparatus used for manufacturing a semiconductor device, as shown in FIG. a support electrode for mounting a wafer 12 provided with the high frequency power source 13 (e.g. 13.56MH _Z) is applied between the cathode 4 and anode 3 which is a counter electrode, to generate plasma between the electrodes, gas plasma It has an emission analyzer 20 which is configured to etch the film to be etched by a physical reaction due to ion bombardment and a chemical reaction with an active gas, and which detects the end point of the film to be etched.

Generally, in the etching process, it is essential to maintain the process performance such as the cross-sectional shape after etching, the surface appearance, the etching rate, and the selection ratio with the base with high accuracy. For this purpose, the vacuum container 1 and Control and early detection of leaks in the valve 17 and gas piping in the gas supply system are extremely important control items.

Therefore, in the measurement and management of the leak in the plasma etching apparatus of the prior art, the ultimate vacuum degree in the vacuum container 1 is automatically measured by the vacuum gauge 2 provided in the vacuum container 1 and the pressure is set below the set pressure. In this case, a vacuum degree monitoring function that issues an alarm has been put to practical use, but because gas is being supplied during etching processing, the ultimate vacuum cannot be monitored, and automatic measurement is performed only during the etching processing interval time. The current situation is that monitoring is being carried out. Also, regarding the above measurement, outgas from the side wall of the vacuum container 1 and the vacuum gauge 2
Therefore, it is difficult to detect a minute leak in the vacuum container 1, the air operation valve 17 of the gas supply system, and the gas pipe.

[0005]

The above-mentioned conventional plasma etching apparatus is provided with a mechanism for measuring the ultimate vacuum degree and the leak rate by means of a vacuum gauge provided in the vacuum container, but it can be measured only in the vacuum container. Since it is not present, it is difficult to detect external leaks, minute leaks, etc. in the gas supply system valves and gas pipes.
Since it is necessary to once draw a high vacuum in the vacuum container, measurement can only be performed at wafer processing intervals. Further, it is difficult to detect a minute leak due to the influence of outgas after the etching and the precision of the vacuum gauge.

An object of the present invention is to provide a plasma etching apparatus capable of improving the detection accuracy and constantly monitoring in-process level with respect to leaks in a vacuum system and a gas supply system, and preventing product defects due to leaks. To do.

[0007]

The plasma etching apparatus according to the present invention includes a storage circuit for storing a preset plasma emission intensity ratio and emission wavelength of a gas and an emission analyzer which are newly added to the conventional plasma etching apparatus. It has a comparison / determination circuit that determines the presence / absence of a leak in the process chamber and the gas supply system based on the output signal strength, and a calculation control unit that enables control of the high frequency power supply, the vacuum exhaust system, and the gas control unit.

[0008]

The present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of an embodiment of the present invention and a diagram of an emission spectroscopic unit system.

A pair of electrodes, that is, an anode 3 as a counter electrode and a cathode 4 as a support electrode on which a wafer 12 is mounted are provided in the vacuum container 1 in a state of being electrically insulated by an insulating member 5 so as to face each other. Has been. A high frequency power supply 13 is connected to the cathode 4 via a matching unit 14. There is an etching gas exhaust port 6 directly connected to the dry pump 9 and the turbo pump 8 in order to make the inside of the vacuum container 1 a vacuum, and the gate valve 7 is opened to exhaust the inside of the vacuum container 1.

Further, the anode 3 and the cathode 4 are temperature controllers 1
Temperature control is performed by 0 and 11.

When an external leak occurs in the air operation valve 17 and the mass flow controller 18, the atmosphere is mixed in the gas supply system and is supplied into the vacuum container 1.

The gas mixed in the atmosphere in the vacuum chamber 1 is oscillated by the high frequency power source 13 by the high frequency, and the freely moving positive and negative charged particles coexist in the electrically neutral plasma state to emit light.

The emission analyzer 20 capable of separating the N ₂ emission wavelength of the plasma emission described above is set in advance to the N ₂ emission wavelength (for example, 380 nm) and monitored during the plasma etching process.

The preset plasma emission intensity ratio of N ₂ gas and emission wavelength (for example, 380 nm) are set in the memory circuit 23. When a leak occurs, the emission wavelength intensity of N ₂ in plasma increases as compared with the normal state.

The increased emission wavelength intensity signal is judged to be abnormal when the signal converted into a voltage by the photomultiplier tube 21 is increased by more than the set signal of the memory circuit 23 and the set signal by the comparison / judgment circuit 22. A signal indicating that there is a leak is sent to the arithmetic control circuit 24, and the operations of the high frequency power supply 13, the gate valve 7, the mass flow controller 18, and the air operation valve 17 are stopped.

According to the present embodiment thus constructed,
It is possible to detect a minute leak even during the plasma etching process in which the gas is supplied into the vacuum container 1.

Another embodiment of the present invention will be described below. FIG. 2 is a sectional view of another embodiment of the present invention, and FIGS. 3 and 4 are detailed explanatory views of this embodiment.

In the first embodiment, as described with reference to FIG. 3, N ₂ was used as the process gas in the plasma etching process.
In the case of using, the N ₂ emission wavelength intensity is generated in plasma emission, and even if a leak occurs, it overlaps with the emission wavelength intensity of N _{2 in} the atmosphere, and it is difficult to detect a minute leak. There was a flaw.

In the second embodiment, in order to remedy the above-mentioned problems, in addition to the technique of the first embodiment, a plurality of emission analyzers 20 are mounted, and leak detection is possible even when N ₂ of the process gas is used. It was done.

The second embodiment of the present invention has a plurality of emission analyzers 20a to 20n capable of separating emission wavelengths of plasma. Both the external leak and the internal leak of the valve 17 can be detected by obtaining the respective wavelength intensities as shown below.

For example, in the case of external leakage, the wavelength of the emission analyzer 20b is set to O ₂ (for example, 602 nm),
When the detected signal increases the value in which the plasma emission intensity ratio of O ₂ and the emission wavelength (for example, 602 nm) are stored in the storage circuit 23 in advance in the comparison / determination circuit 22 by more than the set signal, it is determined to be abnormal. Control each unit as in the first embodiment.

Further, in the case of a gas used only in a specific process, for example, CF ₄ , the wavelength of the emission analyzer 20n is set to F (690 nm), and when the signal not normally detected increases by more than the set signal, it is abnormal. Then, a signal with an internal leak is sent to the arithmetic control circuit 24, and the same control as in the first embodiment is performed.

[0024]

As described above, according to the present invention, by providing means for detecting a leak of the plasma etching apparatus during plasma etching, not only in the vacuum container,
There is an effect that it is possible to constantly detect a leak in the valve of the gas supply system and the gas pipe with high accuracy, and it is also possible to detect an internal leak in the valve. Therefore, a minute leak from the gas supply system can be detected early and accurately.

Further, since etching in the submicron order level corresponding to high integration of LSI will be required in the future, even if a minute leak occurs, the product will be greatly affected.

Therefore, the highly accurate leak detection mechanism as in the present invention has the effect of greatly improving the performance of the plasma etching apparatus.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of another embodiment of the present invention.

FIG. 3 is an output example of the comparison circuit of the first embodiment.

FIG. 4 is an output example of a comparison circuit of the second embodiment.

FIG. 5 is an explanatory diagram showing a configuration of an example of a conventional plasma etching apparatus.

[Explanation of symbols]

 1 Vacuum container 2 Vacuum system 3 Anode 4 Cathode 5 Insulation member 6 Etching exhaust port 7 Gate valve 8 Turbo pump 9 Dry pump 10 Temperature controller 11 Temperature controller 12 Wafer 13 High frequency power supply 14 Matching device 15 Earth 16 Earth 17 Air op valve 18 Mass flow Controller 19 Gas supply source 20 Emission analyzer 21 Photomultiplier tube 22 Comparison judgment circuit 23 Storage circuit 24 Arithmetic control circuit

Claims (2)

[Claims] 1. A support electrode for mounting a semiconductor wafer, which is placed in a vacuum container, a counter electrode provided to face the support electrode, a high-frequency power source for generating plasma between the electrodes, and a vacuum container. In a plasma etching apparatus comprising a vacuum exhaust system for exhausting a gas, a gas control system for controlling a process gas in a vacuum container, and an emission analyzer capable of separating emission wavelengths in plasma, a preset gas is used. A storage circuit for storing the plasma emission intensity ratio and the emission wavelength, a comparison determination circuit for performing a comparison determination of the output signal intensity from the emission analyzer, and a high frequency power supply and a vacuum exhaust system based on the output signal result from the comparison determination circuit. A plasma etching apparatus having an arithmetic control unit capable of controlling a gas supply system. 2. A control which has a storage circuit for storing the preset plasma emission intensity ratios and emission wavelengths of a plurality of gases, and automatically controls the wavelength setting of the emission analyzer according to the signal set by the storage circuit. The plasma etching apparatus according to claim 1, further comprising a circuit.