JP3901429B2 - Plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus for processing an object to be processed in a processing chamber in a vacuum atmosphere using plasma generated by irradiating a process gas with microwaves.
[0002]
[Prior art]
As a device for processing objects such as silicon wafers for semiconductor manufacturing and glass substrates for liquid crystal displays, plasma is generated by irradiating process gas with microwaves, and ions and active species from this plasma are used. There is a plasma processing apparatus that performs a dry etching process, an ashing process, or the like on a workpiece. Surface processing such as fine processing and thin film formation by plasma technology using this plasma processing apparatus has become indispensable for high integration of semiconductors, for example.
[0003]
There are several types of plasma processing apparatuses. For example, a microwave guided by a microwave waveguide is radiated from a slot antenna formed in the microwave waveguide, and the process gas in the vacuum vessel is microscopically radiated. There is a type in which plasma is generated by irradiating a wave, and a surface treatment such as fine processing by dry etching or thin film formation is performed on an object to be processed using this plasma.
[0004]
This type of plasma processing equipment is such that the plasma generated inside the vacuum vessel is brought into contact with the surface of the object to be processed, and surface treatment such as dry etching or ashing is performed by ions or active species in the plasma, and plasma generation In some cases, the region and the processing chamber are separated, and a downflow from the plasma is guided to the surface of the object to be processed to perform surface treatment such as dry etching or ashing.
[0005]
As another type of plasma processing apparatus, the process gas inside the discharge tube is irradiated with microwaves to generate plasma in the discharge tube, and the active species generated by this plasma are guided into the processing chamber. There is a type of apparatus that feeds the surface of the workpiece.
[0006]
The plasma processing apparatus described above includes a microwave transmitting member for introducing a microwave into a region where plasma is generated, and the microwave transmitting member is usually formed of quartz glass.
[0007]
[Problems to be solved by the invention]
In the plasma processing apparatus described above, when a process gas containing at least fluorine atoms is used, the quartz glass constituting the microwave transmitting member is etched. For this reason, it is necessary to replace the microwave transmitting member appropriately. Conventionally, however, the time until replacement (quartz life) is determined in advance and replaced when the time has passed.
[0008]
However, the etching rate of quartz glass varies greatly according to temperature, microwave power, processing time, and the like. When processing under constant conditions at all times, there is no major problem even if the microwave transmitting member is replaced by time management based on a predetermined quartz life, but when various processing conditions are used together, The predetermined quartz life is not always optimal. That is, the etching of the microwave transmitting member proceeds before the predetermined quartz life is reached and becomes unusable, or conversely, even though the predetermined quartz life is reached, There is a problem that it can be used continuously.
[0009]
Therefore, an object of the present invention is to provide a plasma processing apparatus capable of accurately detecting the lifetime of a microwave transmitting member made of quartz glass.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a plasma processing apparatus for processing an object to be processed in a processing chamber in a vacuum atmosphere using plasma generated by irradiating a process gas containing at least fluorine atoms with microwaves. The plasma generating region is separated from the processing chamber so that the plasma does not come into contact with the object to be processed. In the plasma processing apparatus , the microwave is introduced into the plasma generating region. a microwave transmitting member made of quartz glass, and a light detector for detecting light emission of SiF that the plasma generated in the region for generating the plasma is generated when the said microwave transmissive member Gae etching, the And monitoring means having a function of integrating the intensity of light emission of SiF detected by the light detection means.
[0011]
Preferably, the monitoring means further has a function of determining whether or not the integrated value of the light emission intensity of SiF exceeds a predetermined allowable limit value.
[0012]
Preferably, the monitoring means integrates the intensity of light emission of SiF in the wavelength range of 220 nm to 275 nm.
[0013]
Preferably, the light detection means detects the light emission of the SiF without distinguishing it from other light emission, and the light emission detected by the light sensor to distinguish the light emission of the SiF from other light emission. A spectroscope or a monochromator.
[0014]
Preferably, the light detection means includes an optical filter for separating the light emission of SiF from other light emission, and a photocell for detecting the light emission of SiF that has passed through the optical filter.
[0016]
Preferably, the microwave transmitting member is a discharge tube.
[0017]
Preferably, the microwave transmitting member is a window member that seals an opening of a vacuum vessel that forms the processing chamber therein.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plasma processing apparatus according to a first embodiment of the present invention will be described with reference to the drawings.
[0019]
As shown in FIG. 1, the plasma processing apparatus according to the present embodiment includes a vacuum vessel 1, and a processing chamber 2 for performing processing such as etching on the workpiece W inside the vacuum vessel 1. Is formed. The processing chamber 2 is provided with a stage 3 for placing the workpiece W thereon.
[0020]
The upper opening of the vacuum vessel 1 is sealed with a microwave transmission window member 5 made of quartz glass. The microwave transmission window member 5 is a microwave for introducing a microwave into a region where plasma is generated. A wave transmitting member is configured. Inside the vacuum vessel 1, a partition plate 4 is provided so that a region for generating plasma is separated from the processing chamber 2 so that the plasma does not come into contact with an object to be processed, and a hole formed in the partition plate 4. The active species in the plasma is supplied to the surface of the workpiece W through a down flow.
[0021]
A gas introduction port 6 for introducing a process gas containing at least fluorine atoms into the vacuum vessel 1 is formed on the side wall of the vacuum vessel 1. An exhaust port 7 for exhausting the inside of the vacuum vessel 1 is formed on the bottom wall of the vacuum vessel 1.
[0022]
Then, the microwave guided through the microwave waveguide 13 is radiated from the slot antenna 14, introduced into the vacuum vessel 1 through the microwave transmission window member 5, and irradiated with the process gas to generate plasma. Is done.
[0023]
Furthermore, the plasma processing apparatus according to the present embodiment includes the light detection means 8 for detecting the emission of SiF generated when the microwave transmission window member 5 is etched by the plasma. The optical filter 9 for separating the emitted light from the other emitted light, and a photodiode (photocell) 10 for detecting the emitted light of SiF that has passed through the optical filter 9. The optical filter 9 transmits light having a wavelength range of 220 nm to 275 nm, and thereby can detect light emitted from SiF separately from other light.
[0024]
The photodiode 10 is connected to the monitoring means 11, and this monitoring means 11 has a function of integrating the intensity of light emission of SiF detected by the light detection means 8. The monitoring unit 11 also has a function of determining whether or not the integrated value of the light emission intensity of SiF exceeds a predetermined allowable limit value determined in advance. An observation window for extracting emitted light is formed on the side wall of the vacuum vessel 1 by the light transmitting member 12.
[0025]
In the plasma processing apparatus according to the present embodiment, when the integrated value of the SiF emission intensity calculated by the monitoring unit 11 exceeds a predetermined allowable limit value, the microwave transmitting window member 5 is provided. Try to exchange.
[0026]
FIG. 2 is a graph showing the integrated value of the emission intensity of SiF with respect to the usage time of the plasma processing apparatus. Since the processing conditions are switched in the middle, the increasing rate of the integrated value changes in the middle. Thus, the change in the processing conditions is reflected in the increasing rate of the integrated value of the emission intensity of SiF.
[0027]
FIG. 3 shows the wavelength distribution of light incident on the optical filter 9, and the wavelength range from 220 nm to 275 nm corresponds to the emission of SiF. “T” in FIG. 3 indicates the continuous discharge time (seconds) from the start of discharge. However, T = 0 corresponds to immediately after the start of discharge, not before the start of discharge.
[0028]
As described above, according to the plasma processing apparatus according to the present embodiment, since the microwave transmitting window member 5 made of quartz glass is integrated with the emission intensity of SiF generated when etched by plasma, By confirming that the integrated value has exceeded a predetermined allowable limit value, it is possible to accurately detect the lifetime of the microwave transmission window member 5 even when the processing condition is switched halfway.
[0029]
Next, a plasma processing apparatus according to a second embodiment of the present invention will be described with reference to FIG.
[0030]
The plasma processing apparatus according to the present embodiment is a chemical dry etching apparatus, and as shown in FIG. 4, a microwave transmitting member for introducing microwaves into a region where plasma is generated is constituted by a discharge tube 20 made of quartz glass. Has been. A microwave waveguide 21 is connected to the discharge tube 20, and the microwave guided by the microwave waveguide 21 is irradiated to the process gas inside the discharge tube 20, thereby generating plasma. As the process gas, a gas containing at least fluorine atoms is used.
[0031]
Furthermore, the plasma processing apparatus according to the present embodiment includes the light detection means 22, which detects the light emission of SiF without distinguishing it from other light emission, and the light emission of SiF. In order to distinguish from the light emission, a spectroscope 24 that splits the light emission detected by the optical sensor 23 is provided. A monochromator may be provided in place of the spectroscope 24. The spectroscope 24 is connected to the monitoring means 25, and this monitoring means 25 has the same function as the monitoring means 11 in the first embodiment described above.
[0032]
In the plasma processing apparatus according to the present embodiment, as in the first embodiment described above, the integrated value of the emission intensity of SiF calculated by the monitoring unit 25 exceeds a predetermined allowable limit value determined in advance. In some cases, the discharge tube 20 is replaced.
[0033]
FIG. 5 is a graph showing the integrated value of the emission intensity of SiF with respect to the usage time of the plasma processing apparatus. Since the processing conditions are switched twice in the middle, the increase rate of the integrated value changes twice in the middle. In this way, the change in the processing conditions is reflected in the increasing rate of the integrated value of the emission intensity of SiF.
[0034]
As described above, according to the plasma processing apparatus according to the present embodiment, the intensity of light emission of SiF generated when the discharge tube 20 made of quartz glass is etched by plasma is integrated. By confirming that the predetermined allowable limit value has been exceeded, the life of the discharge tube 20 can be accurately detected even when the processing conditions are switched halfway.
[0035]
【The invention's effect】
As described above, according to the plasma processing apparatus of the present invention, the intensity of light emission of SiF generated when the microwave transmitting member is etched by plasma is integrated, so this integrated value is a predetermined allowable limit. By confirming that the value has been exceeded, it is possible to accurately detect the lifetime of the microwave transmitting member even when the processing conditions are switched halfway.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a plasma processing apparatus according to a first embodiment of the present invention.
FIG. 2 is a graph showing an integrated value of the emission intensity of SiF with respect to usage time of the plasma processing apparatus shown in FIG.
3 is a view showing a wavelength distribution of light incident on an optical filter of the plasma processing apparatus shown in FIG.
FIG. 4 is a diagram showing a schematic configuration of a main part of a plasma processing apparatus according to a second embodiment of the present invention.
5 is a graph showing an integrated value of the emission intensity of SiF with respect to the usage time of the plasma processing apparatus shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Processing chamber 3 Stage 4 Partition plate 5 Microwave transmission window member 8, 22 Photodetection means 9 Optical filter 10 Photodiode (photocell)
11, 25 Monitoring means 12 Light transmitting member 13, 21 Microwave waveguide 20 Discharge tube 23 Optical sensor 24 Spectrometer W Object to be processed

Claims (7)

A plasma processing apparatus for processing an object to be processed in a processing chamber in a vacuum atmosphere using a plasma generated by irradiating a process gas containing at least fluorine atoms with microwaves, wherein the region for generating plasma is In the plasma processing apparatus configured to be separated from the processing chamber so that the plasma does not contact the workpiece ,
A microwave transmitting member made of quartz glass for introducing microwaves into the region for generating the plasma,
Light detecting means for detecting the emission of SiF generated when the said microwave transmissive member Gae etching with plasma generated in the region for generating the plasma,
And a monitoring means having a function of integrating the intensity of light emission of SiF detected by the light detection means.   The plasma processing apparatus according to claim 1, wherein the monitoring unit further has a function of determining whether or not an integrated value of the intensity of light emission of SiF exceeds a predetermined allowable limit value.   The plasma processing apparatus according to claim 1, wherein the monitoring unit integrates the intensity of light emission of SiF in a wavelength range of 220 nm to 275 nm.   The photodetecting means is a photosensor that detects the emission of SiF without distinguishing it from other emission, and a spectrometer that separates the emission detected by the photosensor in order to distinguish the emission of SiF from other emission The plasma processing apparatus according to claim 1, further comprising: a monochromator.   The said light detection means has an optical filter for isolate | separating light emission of SiF from other light emission, and a photocell which detects light emission of SiF which permeate | transmitted the said optical filter, The Claim 1 thru | or 3 characterized by the above-mentioned. The plasma processing apparatus as described in any one of these. The microwave transmitting member is a plasma processing apparatus according to any one of claims 1 to 5, characterized in that a discharge tube. The microwave transmitting member, the plasma processing apparatus according to any one of claims 1 to 5, characterized in that a window member for sealing the opening of the vacuum container forming the treatment chamber therein.

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