JP2005019763A - Dry etching device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry etching device, by which the occurrence of particles is prevented by early discovering the deterioration of a device part forming a surface protective film, an exchange cost is reduced, and a device operating-efficiency is improved. <P>SOLUTION: A spectroscope 22 detecting the emission spectrum of aluminum as the base material of gaseous diffusion plates 6, a treating section 23 converting the emission spectrum intensity of the spectroscope 22 into a voltage, a deterioration detecting section 24 detecting the deterioration of the device part by comparing an output from the treating section 23 with a specified value, and a display section 25 displaying the exchange of the device part in response to an output from the detecting section 24, are newly installed on the output side of a view port 17 for detecting the deterioration of the gaseous diffusion plates 6. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dry etching apparatus that etches a semiconductor wafer (hereinafter referred to as a wafer) using a plasma of a reactive gas in a vacuum processing chamber, and in particular, a dry etching apparatus having a function of accurately determining the presence or absence of deterioration of apparatus parts. The present invention relates to an etching apparatus.
[0002]
[Prior art]
In the manufacturing process of a semiconductor element, a dry etching apparatus using a reactive gas plasma is used to remove a predetermined film formed on the surface of a wafer. In such a dry etching apparatus, after the inside of the vacuum chamber is made high vacuum, a reaction gas is introduced, and a high frequency voltage is applied between the lower electrode and the upper electrode on which the wafer provided facing the inside of the vacuum chamber is placed. Then, plasma is generated between both electrodes, and the film to be etched is etched by a physical reaction by ion bombardment in the gas plasma and a chemical reaction by the active gas.
[0003]
Furthermore, in order to improve the etching accuracy and form a fine pattern, it has a function of accurately detecting the end point of etching. In such an etching end point determination method, the intensity change of the emission spectrum of plasma is observed through an observation window (hereinafter referred to as a viewport) provided in the side wall of the vacuum chamber, and the etching process with a desired film thickness is completed. It is to judge.
[0004]
Such a technique is disclosed in, for example, Japanese Patent Laid-Open No. 3-150723. FIG. 3 is a cross-sectional view showing a configuration of a conventional dry etching apparatus. A conventional dry etching apparatus 31 includes a vacuum chamber 33 for etching a wafer 32, a lower electrode 34 for adsorbing and holding the wafer 32, an upper electrode 35 disposed above the wafer 32, and a reaction gas uniformly on the wafer 32. A gas diffusion plate 36 provided on the upper electrode 35 is provided for guiding. The lower electrode 34 is connected to a high frequency power source 38 via a matching unit 37, and the upper electrode 35 is grounded. Further, a gas supply source 41 is connected to the gas supply pipe 39 at the upper part of the vacuum chamber 33 via a flow rate control valve 40 in order to supply a reaction gas, and a gas exhaust pipe 42 at the lower part of the vacuum chamber 33 is connected to the gas supply pipe 39. In order to exhaust the reaction gas, a vacuum pump 44 such as a turbomolecular pump, a mechanical booster pump, or a rotary pump is connected via a pressure control valve 43. Further, a deposition shield 45 for preventing the reaction gas from adhering to the side wall of the vacuum chamber 33 is detachably provided.
[0005]
Further, on the side wall of the vacuum chamber 33, a viewport 47 made of quartz glass for observing the plasma light 46 being reacted, a spectroscope 48 for detecting an emission spectrum of a specific gas from the viewport 47, and a spectroscope 48 A processing unit 49 that converts the emission spectrum intensity of the light into a voltage, an end point detection unit 50 that detects an end point of etching by comparing the output of the processing unit 49 with a predetermined value, and an etching process according to the output of the end point detection unit 50 The control part 51 which outputs the signal which complete | finishes is provided. In addition, temperature control means (not shown) is provided on the surface of the viewport 47 to prevent the reaction product from adhering to the surface of the viewport 47 during etching and reducing the transmittance of the plasma light 46. .
[0006]
Next, the operation of the conventional dry etching apparatus 31 will be described. First, the wafer 32 is placed on the lower electrode 34 in the vacuum chamber 33. Next, the pressure control valve 43 is opened and the vacuum pump 44 is operated to evacuate the vacuum chamber 33. When the pressure in the vacuum chamber 33 reaches a predetermined pressure, the flow control valve 40 is opened, and a reaction gas having a predetermined flow rate is supplied from the gas supply source 41 into the vacuum chamber 33. Subsequently, high-frequency power (13.56 MHz or the like) is supplied from the high-frequency power source 38 to the lower electrode 34 while impedance is controlled by the matching unit 37, and a predetermined etching process is performed.
[0007]
Then, the etching target film formed on the wafer 32 is etched by the reaction gas, and the plasma light 46 generated when the film is gasified is guided to the spectroscope 48 through the view port 47. The spectroscope 48 detects an emission spectrum of a specific wavelength from the plasma light 46, converts the emission spectrum intensity into a voltage by the processing unit 49, and sends the output to the end point detection unit 50. The end point detection unit 50 compares the output of the processing unit 49 with a predetermined value. When the etching process proceeds and the output of the processing unit 49 reaches a predetermined value, the control unit 51 outputs a stop signal to the high frequency power supply 38, the flow rate control valve 40, and the pressure control valve 43, and the etching process is terminated. .
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 3-50723 (page 2, FIG. 1)
[0009]
[Problems to be solved by the invention]
However, the dry etching apparatus 31 described above has the following problems.
[0010]
During the etching process, not only the film to be etched but also the device parts are exposed to plasma, so that the base material of the device parts is etched to cause dust generation. In order to prevent this, a protective film is formed on the surface of the device component, and a device for improving the corrosion resistance against plasma has been devised. This device component includes, for example, a gas diffusion plate 36, which is made of aluminum as a base material and anodized (Al ₂ O ₃ ) as a surface protective film.
[0011]
However, when the plasma treatment is continued for a long time, the alumite that is the surface protective film is gradually etched, and the aluminum that is the base material is exposed. Since aluminum is highly reactive, it reacts easily with fluorine and chlorine contained in the reaction gas to generate particles mainly composed of aluminum fluoride (AlF ₃ ) and aluminum chloride (AlCl ₃ ) and adheres to the wafer 32. As a result, abnormal pattern formation, short circuit of wiring, and the like are caused, and the product yield is greatly reduced.
[0012]
For this reason, when it is determined that the surface protective film is lost and the gas diffusion plate 36 has deteriorated, it is necessary to replace it promptly. Conventionally, the number of processed wafers 32 and the discharge time are integrated and managed, and the gas diffusion plate 36 is replaced when a predetermined number of processed wafers and discharge time are exceeded. However, in recent years, the production form of semiconductor products has changed to multi-product production of individual processes instead of mass production of the same process as found in past DRAM production. Therefore, the dry etching conditions are not constant, and the RF power, the type of reactive gas, the pressure, etc. are different, so the deterioration rate of the equipment parts inevitably varies, and the conventional management based on the number of processed wafers 32 and the discharge time is different. Thus, it is impossible to accurately determine the presence or absence of deterioration of the device parts.
[0013]
Therefore, as a measure for maintaining quality, considering a certain margin, replacement was carried out early, so that a large amount of expenses were incurred for replacement or the equipment was stopped for a certain period of time for each replacement operation. There was a problem of reducing the rate.
[0014]
The present invention was conceived in order to solve the above problems, and by detecting the deterioration of device parts forming the surface protective film at an early stage, the generation of particles can be prevented and the replacement cost can be reduced. It is an object of the present invention to provide a dry etching apparatus which is reduced and the apparatus operation rate is improved.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, a dry etching apparatus according to claim 1 of the present invention includes an upper electrode and a lower electrode arranged to face each other at a predetermined interval in a chamber, and a reaction gas is supplied from the upper electrode. A dry etching apparatus which is introduced into a processing chamber and generates a plasma between both electrodes to process a film to be etched, and when a base material of an apparatus part forming a surface protective film is etched by the plasma. It is characterized by comprising detecting means for detecting the presence or absence of deterioration of the device parts by detecting the emission spectrum intensity generated. According to this configuration, by measuring the emission spectrum intensity of the base material of the device component, it is possible to monitor the degree of consumption of the surface protective film in the device component. As a result, it is possible to accurately determine the presence or absence of deterioration of the device components. As a result, the generation of particles from the device parts can be prevented and the product yield can be greatly improved. Furthermore, the replacement cost of apparatus parts can be reduced and the apparatus operation rate can be improved.
[0016]
Further, the dry etching apparatus according to claim 2 is the dry etching apparatus according to claim 1, wherein the detection means is an observation means for observing plasma light during etching processing, and light emission of a specific wavelength from the plasma light. Spectroscopic means for taking out a spectrum, processing means for converting emission spectrum intensity from the spectroscopic means into voltage, deterioration detecting means for detecting deterioration of apparatus parts by comparing the output of the processing means with a predetermined value, and It is characterized by comprising display means for displaying the replacement of device parts in accordance with the output of the deterioration detection means. According to this configuration, by comparing the emission spectrum intensity of the base material of the device component with a predetermined value, it is possible to monitor the degree of wear of the surface protective film on the device component. Thereby, even when the RF power, the type of reaction gas, the pressure, and the like, which are dry etching conditions, are different, it is possible to accurately determine the presence or absence of deterioration of the device components. As a result, the generation of particles from the device parts can be prevented and the product yield can be greatly improved. Furthermore, the replacement cost of apparatus parts can be reduced and the apparatus operation rate can be improved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing the structure of the dry etching apparatus of the present invention. The dry etching apparatus 1 of the present invention includes a vacuum chamber 3 for etching a wafer 2, a lower electrode 4 for adsorbing and holding the wafer 2, an upper electrode 5 disposed above the wafer 2, and a reaction gas to the semiconductor wafer 2. A gas diffusion plate 6 provided on the upper electrode 5 is provided for uniform guidance. The lower electrode 4 is connected to a high-frequency power source 8 through a matching unit 7, and the upper electrode 5 is grounded. Further, a gas supply source 11 is connected to the gas supply pipe 9 at the upper part of the vacuum chamber 3 through a flow rate control valve 10 in order to supply a reaction gas, and a gas exhaust pipe 12 at the lower part of the vacuum chamber 3 is connected to the gas supply pipe 9. In order to exhaust the reaction gas, a vacuum pump 14 such as a turbomolecular pump, a mechanical booster pump, or a rotary pump is connected via a pressure control valve 13. A deposition shield 15 for preventing the reaction gas from adhering to the side wall of the vacuum chamber 3 is detachably provided.
[0018]
Further, on the side wall of the vacuum chamber 3, a viewport 17 made of quartz glass for observing the plasma light 16 being reacted, a spectroscope 18 for detecting an emission spectrum of a specific gas from the viewport 17, and a spectroscope 18 A processing unit 19 that converts the emission spectrum intensity of the light into a voltage, an end point detection unit 20 that detects an end point of etching by comparing the output of the processing unit 19 with a predetermined value, and an etching process according to the output of the end point detection unit 20 The control part 21 which outputs the signal which complete | finishes is provided.
[0019]
Furthermore, in the dry etching apparatus 1 of the present invention, in order to detect the deterioration of the gas diffusion plate 6 which is one of the apparatus parts, an aluminum which is a base material of the gas diffusion plate 6 is newly provided on the output side of the viewport 17. A spectroscope 22 that detects the emission spectrum of the light, a processing unit 23 that converts the emission spectrum intensity of the spectroscope 22 into a voltage, and a deterioration detection that detects the deterioration of the device parts by comparing the output of the processing unit 23 with a predetermined value. And a display unit 25 that displays the replacement of the device parts in accordance with the output of the deterioration detection unit 24.
[0020]
Next, the operation of the dry etching apparatus 1 of the present invention will be described. First, the wafer 2 is placed on the lower electrode 4 in the vacuum chamber 3. Next, the pressure control valve 13 is opened, the vacuum pump 14 is operated, and the vacuum chamber 3 is evacuated. When the pressure in the vacuum chamber 3 reaches a predetermined pressure, the flow control valve 10 is opened and a predetermined flow rate of reaction gas is supplied from the gas supply source 11 into the vacuum chamber 3. Subsequently, high-frequency power (13.56 MHz or the like) is supplied from the high-frequency power source 8 to the lower electrode 4 while controlling impedance by the matching unit 7, and a predetermined etching process is performed.
[0021]
Then, the etching target film formed on the wafer 2 is etched by the reaction gas, and the plasma light 16 generated when the film is gasified is guided to the spectroscope 18 through the view port 17. The spectroscope 18 detects an emission spectrum of a specific wavelength from the plasma light 16, converts the emission spectrum intensity into a voltage by the processing unit 19, and sends the output to the end point detection unit 20. The end point detection unit 20 compares the output of the processing unit 19 with a predetermined value and monitors the progress of the etching process.
[0022]
In the present invention, the progress of the etching process is monitored, and at the same time, the newly provided spectrometer 22 detects the emission spectrum (396 nm) of aluminum that is the base material of the gas diffusion plate 6 from the plasma light 16, and the processing unit 23. After the emission spectrum intensity is converted into voltage, the output is sent to the deterioration detection unit 24. The deterioration detection unit 24 monitors the deterioration state of the gas diffusion plate 6 by comparing the output of the processing unit 23 with a predetermined value.
[0023]
FIG. 2 is a diagram showing the relationship between the emission spectrum intensity I of aluminum, which is the base material of the gas diffusion plate 6, and the number P of wafers to be processed. Until processed sheets P reaches P _1, since the surface of the gas diffusion plate 6 is covered with anodized, the emission spectrum intensity I of the aluminum is stable at a low level I _1. However, the etching process proceeds, the number of processed P exceeds P _1, anodized aluminum surface of the gas diffusion plate 6 is gradually etched, to expose the aluminum base material is exposed to aluminum direct plasma 16. As a result, the emission spectrum intensity I of aluminum increases rapidly.
[0024]
When the alumite etching progresses and the aluminum emission spectrum I reaches a preset level I ₂ , the deterioration detector 24 detects the deterioration of the gas diffusion plate 6, and the display unit 25 detects the gas diffusion plate 6. Display exchanges. Next, the inside of the vacuum chamber 3 is returned to atmospheric pressure, and the deteriorated gas diffusion plate 6 is removed and replaced with a new gas diffusion plate. Thereafter, a new wafer is loaded, the inside of the vacuum chamber 3 is evacuated, and the etching process is performed again.
[0025]
In the dry etching apparatus of the present invention, the emission spectrum of the film to be etched formed on the wafer 2 is monitored through the same view port 16, and at the same time, the emission spectrum of aluminum constituting the gas diffusion plate 6 is monitored. Therefore, the end point determination of the etching process and the deterioration determination of the gas diffusion plate 6 can be performed simultaneously. As a result, if it is determined that the gas diffusion plate 6 has deteriorated, it can be replaced immediately, the generation of particles from the gas diffusion plate 6 can be prevented, and the product yield can be improved. Further, it is not necessary to perform early replacement considering a certain margin as in the conventional case, so that the cost for replacement can be reduced and the operating rate of the apparatus can be improved. Further, since the end point detection and the deterioration detection can be simultaneously performed by one viewport 17, it is not necessary to modify the dry etching apparatus, and there is a cost merit.
[0026]
In the present embodiment, the case where the deterioration of the gas diffusion plate 6 is determined as one of the device components has been described. However, any device component having a surface protective film may be used. It can also be used for diagnosis.
[0027]
The base material of the device parts may be stainless steel or the like in addition to aluminum, and the coating material may be fluororesin or the like in addition to anodized. By appropriately changing the spectrometer 21 according to the type of the base material, it becomes possible to detect emission spectra of various wavelengths.
[0028]
【The invention's effect】
As described above, according to the dry etching apparatus of the present invention, the emission spectrum intensity of the film to be etched is measured during the etching process to detect the end point of etching, and at the same time, the emission spectrum intensity of the base material of the apparatus component is detected. Thus, the presence or absence of deterioration of the device parts can be determined early from the strength change. Thereby, it is possible to prevent particles generated by etching the device parts. As a result, problems such as abnormal pattern formation and short circuits of wiring in the product can be solved, and the reliability and yield of the product can be greatly improved.
[0029]
In addition, it is possible to accurately determine the replacement timing of the device parts, which has a great effect on the cost reduction for the replacement and the improvement of the operation rate of the device.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the configuration of a dry etching apparatus according to the present invention. FIG. 2 is a view showing the relationship between the emission spectrum intensity of aluminum and the number of wafers processed. Figure [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dry etching apparatus 2 of this invention Wafer 3 Vacuum chamber 4 Lower electrode 5 Upper electrode 6 Gas diffusion plate 7 Matching device 8 High frequency power supply 9 Gas supply pipe 10 Flow rate control valve 11 Gas supply source 12 Gas exhaust pipe 13 Pressure control valve 14 Vacuum Pump 15 Depot shield 16 Plasma light 17 Viewport 18 Spectrometer 19 Processing unit 20 End point detection unit 21 Control unit 22 Spectrometer 23 Processing unit 24 Degradation detection unit 25 Display unit 31 Conventional dry etching apparatus 32 Wafer 33 Vacuum chamber 34 Lower electrode 35 Upper electrode 36 Gas diffusion plate 37 Matching unit 38 High frequency power supply 39 Gas supply pipe 40 Flow control valve 41 Gas supply source 42 Gas exhaust pipe 43 Pressure control valve 44 Vacuum pump 45 Depot shield 46 Plasma light 47 Viewport 48 Spectrometer 49 Processing 50 End point detection unit 51 Control unit

Claims (2)

An upper electrode and a lower electrode, which are arranged to face each other at a predetermined interval in the chamber, are provided, a reaction gas is introduced into the processing chamber from the upper electrode, and plasma is generated between the two electrodes to process the film to be etched. In a dry etching apparatus, detecting means for detecting presence or absence of deterioration of the apparatus component by detecting an emission spectrum intensity generated when the base material of the apparatus component forming the surface protective film is etched by the plasma A dry etching apparatus comprising: An observation means for observing the plasma light during the etching process; a spectroscopic means for extracting an emission spectrum of a specific wavelength from the plasma light; and a processing means for converting the intensity of the emission spectrum from the spectroscopic means into a voltage. A deterioration detecting means for detecting deterioration of the device parts by comparing the output of the processing means with a predetermined value, and a display means for displaying the replacement of the device parts according to the output of the deterioration detecting means. The dry etching apparatus according to claim 1.

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