JP6713298B2 - Plasma processing method and plasma processing apparatus - Google Patents

Description

Embodiments of the present invention relate to a plasma processing method and a plasma processing apparatus.

In the manufacture of a fine structure such as a semiconductor device or a photomask, plasma etching treatment (dry etching treatment) is performed on a substrate in which a plurality of layers are stacked. In general, the layers adjacent to each other in the stacking direction are made of different materials. Therefore, when the upper layer is removed, the emission spectrum of the light generated inside the plasma processing space changes. Therefore, there has been proposed a technique for detecting the end point of the etching process by detecting a change in the emission spectrum (see, for example, Patent Document 1).

However, when the substrate is formed of a single material or when the plasma etching process is terminated in the middle of the thickness of one layer, the amount of change in the emission spectrum before and after the process is small. Therefore, in such a case, the end point detection based on the change of the emission spectrum cannot be performed.
Therefore, it has been desired to develop a plasma processing method and a plasma processing apparatus capable of detecting the end point even when the amount of change in the emission spectrum is small.

JP, 09-36090, A

The problem to be solved by the present invention is to provide a plasma processing method and a plasma processing apparatus capable of detecting an end point even when the amount of change in emission spectrum is small.

The plasma processing method according to the embodiment is a plasma processing method in which the plasma etching process is terminated in the middle of the thickness of the object to be processed.
The plasma treatment method includes a step of etching the treated product with a reaction product generated from a gas, and an emission intensity of light of a specific wavelength generated in the plasma treatment space during etching of the treated product. Correlation between the step of obtaining , the obtained emission intensity, and the etching rate calculated from the emission intensity and the etching amount of the light of the specific wavelength obtained by continuously performing the etching treatment under the same conditions in advance. And a step of obtaining an etching rate from the relationship, and a step of detecting the etching end point based on the obtained etching rate.

According to the embodiments of the present invention, there are provided a plasma processing method and a plasma processing apparatus capable of detecting an end point even when the amount of change in emission spectrum is small.

FIG. 6 is a graph for illustrating the relationship between the etching time of the processed product 100 and the emission intensity when the processed product 100 is a quartz glass substrate and the etching process is performed up to the middle of the thickness of the quartz glass substrate. It is a graph figure for illustrating the relation between the number of processed object 100, and etching depth. FIG. 7 is a graph showing the relationship between the emission intensity at the peak wavelength of fluorine (703.7 nm) and the etching rate for each processed material 100. FIG. 6 is a graph showing the relationship between the emission intensity at the hydrogen peak wavelength (656.5 nm) and the etching rate for each processed material 100. 6 is a graph showing the relationship between the emission intensity at the peak wavelengths of oxygen and silicon fluoride and the etching rate for each processed material 100. FIG. It is a schematic cross section for illustrating the plasma processing apparatus 1 which concerns on 2nd Embodiment.

Embodiments will be exemplified below with reference to the drawings. In the drawings, the same components are designated by the same reference numerals, and detailed description thereof will be appropriately omitted.

(First embodiment)
The plasma processing method according to the first embodiment can be performed as follows, for example.
First, plasma is used to excite and activate a gas containing fluorine atoms to generate a reaction product.
The gas used for the plasma treatment may be a mixed gas of a gas containing a fluorine atom and a gas containing another atom. For example, it may be a mixed gas with an inert gas, helium, argon or the like.
The gas containing a fluorine atom can be, for example, CHF ₃ , CF ₄ , C ₄ F ₈ or the like.
The reaction products are radicals (neutral active species), ions, electrons and the like. The radical is, for example, a fluorine radical.
In this case, radicals contribute to chemical etching (isotropic etching) and ions contribute to physical etching (anisotropic etching).

Next, the generated reaction product descends inside the plasma processing space (for example, plasma processing space 22 described later) and reaches the surface of the processing object 100.
A film that serves as a mask is formed on the surface of the object to be processed 100 when it is etched, and the surface of the object to be processed 100 exposed from the opening of the film to be the mask is not etched. Done.
The processed object 100 may be formed of a single material, or the etching may be stopped in the middle of the thickness of one layer.
Further, the processed object 100 contains silicon oxide (SiO ₂ ) as a main component.
The processed object 100 can be, for example, a quartz glass substrate or the like.
The processed object 100 can be, for example, a quartz glass substrate used when manufacturing a template used for an imprint method or when manufacturing a Levenson-type phase shift mask. However, what is formed from the processed object 100 is not limited to a template, a Levenson-type phase shift mask, or the like.
Alternatively, the processed object 100 may be a semiconductor wafer containing silicon (Si) as a main component and having a trench hole formed therein, for example.

Next, the surface of the processed material 100 is etched by the reaction product reaching the surface of the processed material 100.
Next, the end point is detected and the etching process is ended.

Here, when the processed object 100 is formed of a single material such as a quartz glass substrate or when the etching process is ended in the middle of the thickness of one layer, the end point detection based on the change of the emission spectrum is performed. There is a problem that you can not do.

FIG. 1 is a graph for illustrating the relationship between the etching time of the processed object 100 and the emission intensity when the processed object 100 is a quartz glass substrate and the etching process is performed up to the middle of the thickness of the quartz glass substrate. ..
Note that the emission intensity in FIG. 1 is the emission intensity at the peak wavelength of light generated from fluorine atoms during plasma emission from the start to the end of etching. The peak wavelength refers to the wavelength that exhibits the strongest emission intensity in the emission spectrum of each atom.
As can be seen from FIG. 1, the amount of change in the emission intensity is small during the etching process of the arbitrary processed material 100.
It should be noted that during the etching process of the arbitrary processed material 100, the emission intensity at the peak wavelength of light generated from hydrogen atoms, the emission intensity at the peak wavelength of light generated from oxygen atoms, and the emission from silicon fluoride (SiF). The amount of change in the emission intensity at the peak wavelength of light is also small.
The same tendency can be seen when the processed product 100 is made of a single material or when the etching process is terminated in the middle of the thickness of one layer.
Therefore, when the processed object 100 is formed of a single material or when the etching process is terminated in the middle of the thickness of one layer, the end point detection is performed based on the change of the emission spectrum (emission intensity). I can't.

Furthermore, when the processed products containing silicon oxide as a main component are continuously subjected to the etching treatment in the same processing container, the etching amount decreases as the number of processed processed products 100 increases (the etching rate is It decreases).
In addition, "continuously performing the etching treatment" refers to performing the etching treatment on a plurality of processed products at a time interval within a predetermined time in the same processing container. The predetermined time is such a time that the internal temperature of the processing container changes to the temperature at the time of processing the first processed material 100 which starts continuous processing, and is, for example, about 2 hours.

FIG. 2 is a graph diagram for illustrating the relationship between the number of the processed object 100 and the etching depth. The number of the processed product 100 indicates the N-th number when a plurality of processed products are continuously processed.
As can be seen from FIG. 2, as the number of continuously processed objects 100 increases, the etching depth, that is, the etching amount decreases.
This means that the etching rate varies in the etching process.

It is considered that the fluctuation of the etching rate is mainly due to a change in the internal temperature of the processing container 2, a change in the amount of the reaction product attached to the processed object 100, the inner wall of the processing container 2, and the like.
For example, immediately after the start of processing, the internal temperature of the processing container 2 is low. The internal temperature of the processing container 2 refers to the inner wall of the processing container 2 and the inside of the processing container 2 such as a shield for protecting the inner wall from plasma damage and a member such as a mounting table on which the processing object is mounted. Is the temperature.
Then, when the processing is started, the internal temperature of the processing container 2 rises due to the radiant heat of the plasma generated in the processing container 2. Even after the processing is finished, it is difficult to cool the members in the processing container 2 by bringing the cooling medium into contact with the members, and the natural cooling is awaited. Therefore, even after the processing is completed, the internal temperature of the processing container 2 remains high for a predetermined time.
Then, when the processing of the next processed material 100 is started in this state, the processing is started in a state where the internal temperature of the processing container 2 is higher than when the processing of the previous processed material 100 is started.
Here, a large amount of reaction products generated by plasma adhere to a member having a relatively low temperature. Therefore, at the time of the N+1-th process, the N+1-th process product in the room temperature state is carried into the process container 2 in which the internal temperature at the N-th process is not sufficiently lowered, so that the N+1-th process product 100 The temperature is lower than the internal temperature of the processing container 2. That is, as the number of the processed products 100 processed continuously increases, the thermal difference between the processed products 100 and the internal temperature of the processing container 2 increases, and the reaction products easily adhere to the surface of the processed products 100. ..
Further, the more reaction products adhere to the surface of the processed material 100, the more hindered the etching of the processed material 100, and the lower the etching rate of the processed material 100. For this reason, the etching rate decreases as the number of processed products 100 that are continuously processed increases.

In this way, when the processed products containing silicon oxide as the main component are continuously subjected to the etching process, the etching rate changes for each processed product 100. Therefore, if the end point is detected based on the predetermined etching rate and the processing period, the dimensional accuracy of the etching depth becomes poor.

In this case, the etching rate can be stabilized by providing an idling time waiting for a decrease in the internal temperature of the processing container 2 between the Nth processing and the N+1th processing. However, since the idling time is required to be about 2 hours, the time required for a series of etching becomes long when a plurality of processed products are continuously processed.

Here, when etching a processed material containing silicon oxide as a main component, plasma processing using a gas containing fluorine atoms is performed.
In this case, for example, when CHF ₃ is used as the gas containing a fluorine atom, CHF ₃ is decomposed to generate a fluorine radical, a hydrogen radical and the like.
The generated fluorine radicals react with silicon oxide to generate silicon fluoride and oxygen which are gases. Then, silicon fluoride and oxygen are desorbed from the object to be processed, so that etching proceeds.

Therefore, the inventor has found that the correlation between the etching intensity and the emission intensity at the peak wavelength of fluorine, the emission intensity at the peak wavelength of hydrogen, the emission intensity at the peak wavelength of oxygen, and the emission intensity at the peak wavelength of silicon fluoride. Studied the relationship.

3 to 5 show the emission intensity at the peak wavelength of each atom and the etching rate when a plurality of processed products were processed under the same conditions (pressure inside the processing container, gas type, gas flow rate, source power, bias power). It is a graph showing the relationship with.
FIG. 3 is a graph showing the relationship between the emission intensity at the peak wavelength of fluorine (703.7 nm) and the etching rate for each processed object 100.
FIG. 4 is a graph showing the relationship between the emission intensity at the peak wavelength of hydrogen (656.5 nm) and the etching rate for each processed material 100.
FIG. 5 is a graph showing the relationship between the emission intensity at the peak wavelengths of oxygen and silicon fluoride and the etching rate for each of the processed products 100.
Since the peak wavelength of oxygen is 777.2 nm and the peak wavelength of silicon fluoride is 777.0 nm, it is difficult to distinguish the emission intensity at the peak wavelength of oxygen from the emission intensity at the peak wavelength of silicon fluoride. .. Therefore, the emission intensity in FIG. 5 is the emission intensity at the peak wavelengths of oxygen and silicon fluoride.

3 to 5 show the case where CHF ₃ is used as the gas containing fluorine atoms. Therefore, FIG. 4 illustrates the relationship between the emission intensity at the peak wavelength of hydrogen and the etching rate. However, for example, when CF ₄ is used as the gas containing a fluorine atom, there is no hydrogen, and therefore there is no correlation illustrated in FIG. However, there is the correlation illustrated in FIGS. 3 and 5.
The R-squared value, which is the coefficient of determination of the approximate expression indicating the degree of correlation, is 0.9445 in the case of FIG. 3, 0.9021 in the case of FIG. 4, and 0 in the case of FIG. It was 0.9073. In this way, since the correlation between the emission intensity at the peak wavelength of fluorine (703.7 nm) and the etching rate is strongest, fluorine may be set as the detection wavelength.

As can be seen from FIGS. 3 to 5, there is a correlation between the emission intensity and the etching rate that can be represented by an approximate expression of a linear function.
Therefore, if the correlation between the emission intensity and the etching rate is obtained in advance, the etching rate at that time can be obtained from the emission intensity at any time.

In this case, the end point detection can be performed as follows.
First, the emission intensity of light of a specific wavelength generated in the plasma processing space is measured while etching the object to be processed.
For example, the light generated in the plasma processing space can be divided into desired wavelengths by using a spectroscope such as a prism, and the emission intensity can be measured at desired wavelengths by a photoelectric conversion element or the like.

Next, the etching rate is obtained from the measured emission intensity and the correlation between the emission intensity and the etching rate obtained in advance.
Next, the etching time, which is the time required to etch the desired etching amount, is calculated from the obtained etching rate and the desired etching amount (etching depth).
The end point of the etching process is detected using the determined etching time.
For example, the end point of the etching process is the time when the elapsed time of the etching process reaches the obtained etching time.
When the plurality of processed products 100 are continuously processed, the end point of the etching process is detected for each of the plurality of processed products 100.

Here, as described with reference to FIG. 1, the change amount of the emission intensity is small during the etching process of the arbitrary processed object 100.
Therefore, the end point can be detected by using the etching rate for the emission intensity at any time.

However, as can be seen from FIG. 1, the emission intensity fluctuates slightly. Therefore, if the etching rate with respect to the emission intensity at an arbitrary time point is used, an error may occur in the obtained end point time.
Therefore, it is preferable to obtain the average value of the emission intensity in a predetermined period and use the etching rate for the obtained average value of the emission intensity.
In this case, the light emission intensity can be measured at a predetermined time interval within a predetermined period, and the average value of the measured light emission intensities can be obtained.
Further, the period for obtaining the average value of the emission intensity is preferably at least half the period from the start of the etching process to the expected end point obtained by experiments or the like.
Further, when the fluctuation of the etching rate immediately after the start of the etching process is large, it is preferable to exclude the period between the start of the etching process and the predetermined period from the period for obtaining the average value of the emission intensity.
By doing so, it is possible to suppress the occurrence of an error in the timing of the obtained end point.

Further, the end point detection can be performed as follows.
First, the emission intensity at a predetermined time point is measured.
Next, the etching rate at that time is obtained from the measured emission intensity and the correlation between the emission intensity and the etching rate obtained in advance.
Next, the etching amount (etching depth) is calculated from the calculated etching rate and the time from the start of etching to a predetermined time.

If the calculated etching amount (etching depth) does not reach the desired etching amount (etching depth), the etching amount (etching depth) is again set in the same manner after a predetermined time has passed from the predetermined time point. Ask.
When the obtained etching amount (etching depth) reaches a desired etching amount (etching depth), the etching process is terminated.
That is, the end point is when the obtained etching amount (etching depth) reaches the desired etching amount (etching depth).

As described above, the plasma processing method according to this embodiment may include the following steps.
A step of etching the processing object 100 with a reaction product generated from a gas containing a fluorine atom.
A step of obtaining the emission intensity of light of a specific wavelength generated in the plasma processing space while etching the processing object 100.
A step of obtaining an etching rate from the obtained emission intensity and the correlation between the emission intensity of light having a specific wavelength and the etching rate obtained in advance.
A step of detecting the end point based on the obtained etching rate.

In this case, the specific wavelength is any of the peak wavelength of fluorine, the peak wavelength of hydrogen, the peak wavelength of oxygen, and the peak wavelength of silicon fluoride.

Further, in the step of obtaining the light emission intensity of light of a specific wavelength, the light emission intensity at a plurality of time points can be obtained.
Next, in the step of obtaining the etching rate, the etching rate can be obtained from the obtained average value of the emission intensity at the plurality of time points and the above-mentioned correlation.

Further, in the step of detecting the end point, the etching time can be obtained from the obtained etching rate and the desired etching amount.
Then, the time when the elapsed time of the etching process in the step of etching the object to be processed 100 reaches the obtained etching time can be the end point of the etching process.

Further, in the step of obtaining the light emission intensity of light of a specific wavelength, the light emission intensity at a predetermined time can be obtained.
Next, in the step of obtaining the etching rate, the etching rate is obtained from the obtained emission intensity and the above-mentioned correlation.
Next, in the step of detecting the end point, the etching amount is obtained from the obtained etching rate and the time until a predetermined time point.
When the etching amount reaches the desired etching amount, the above-mentioned predetermined time point is set as the end point of the etching process.
If the etching amount does not reach the desired etching amount, after a predetermined time has elapsed from the above-mentioned predetermined time point, based on the emission intensity obtained again by the step of obtaining the emission intensity of light of a specific wavelength, etching is performed. Ask again for the amount.

According to this embodiment, accurate end point detection can be performed even when the amount of change in the emission spectrum is small.
Furthermore, since the processed object 100 containing silicon oxide as a main component is subjected to etching processing, accurate end point detection can be performed even when the etching rate varies.
As a result, even when the amount of change in the emission spectrum is small or the processed object 100 containing silicon oxide as a main component is subjected to the etching process, the accuracy of the etching depth can be significantly improved.
Further, even if the idling time is reduced, it is possible to detect the end point accurately, so that it is possible to improve the productivity.

(Second embodiment)
Next, the plasma processing apparatus 1 according to the second embodiment will be described.
FIG. 6 is a schematic cross-sectional view for illustrating the plasma processing apparatus 1 according to the second embodiment.
As shown in FIG. 6, the plasma processing apparatus 1 is provided with a processing container 2, a mounting unit 3, a power supply unit 4, a power supply unit 5, a decompression unit 6, a gas supply unit 7, a detection unit 8 and a control unit 9. ing.

The processing container 2 has a main body 20 and a window 21.
The main body 20 has a substantially cylindrical shape.
The main body 20 can be formed of, for example, a metal such as an aluminum alloy.
Further, the main body portion 20 is grounded.

The window portion 21 has a plate shape and is provided on the top plate of the main body portion 20.
The window portion 21 is made of a material that can transmit an electromagnetic field and is hard to be etched when an etching process is performed.
The window portion 21 can be formed of, for example, a dielectric material such as quartz.
The processing container 2 has an airtight structure capable of maintaining an atmosphere depressurized below atmospheric pressure.
Inside the processing container 2, a plasma processing space 22 which is a space for etching the processed material 100 is provided.

A detection window 20d is fitted in the main body portion 20, and the detection portion 8 described later detects the emission intensity of light of a specific wavelength generated inside the processing container 2 through the detection window 20d.
The main body 20 is provided with a carry-in/carry-out port 20a for carrying in and carrying out the processed product 100.
The carry-in/carry-out port 20a can be airtightly closed by a gate valve 20b. The gate valve 20b has a door 20b1 and a seal member 20b2.
The seal member 20b2 can be, for example, an O-ring.
The door 20b1 is opened/closed by a gate opening/closing mechanism (not shown).
When the door 20b1 is closed, the seal member 20b2 is pressed against the wall surface near the loading/unloading port 20a, and the loading/unloading port 20a is hermetically closed.

The mounting portion 3 is provided inside the processing container 2 and on the bottom surface of the processing container 2 (main body 20).
The mounting part 3 mounts the processed material 100 containing silicon oxide as a main component.
The mounting portion 3 has an electrode 30, a pedestal 31, and an insulating ring 32.
The electrode 30 is provided below the plasma processing space 22. The upper surface of the electrode 30 is a mounting surface for mounting the processed object 100.
The electrode 30 can be formed of a conductive material such as metal.

The pedestal 31 is provided between the electrode 30 and the bottom surface of the main body 20.
The pedestal 31 is provided to insulate the electrode 30 and the main body 20 from each other.
The pedestal 31 can be formed of, for example, a dielectric material such as quartz.

The insulating ring 32 has a ring shape and is provided so as to cover the side surface of the electrode 30 and the side surface of the pedestal 31.
The insulating ring 32 can be formed of, for example, a dielectric material such as quartz.

The power supply unit 4 has a power supply 40 and a matching unit 41.
The power supply unit 4 is a so-called bias control high-frequency power supply. That is, the power supply unit 4 is provided to control the energy of the ions drawn into the processing object 100 placed on the placing unit 3.
The electrode 30 and the power source 40 are electrically connected via a matching unit 41.

The power supply 40 applies high frequency power having a relatively low frequency (for example, a frequency of 13.56 MHz or lower) suitable for attracting ions to the electrode 30.
The matching device 41 is provided between the electrode 30 and the power supply 40. The matching device 41 includes a matching circuit and the like for matching between the impedance on the power source 40 side and the impedance on the plasma P side.

The power supply unit 5 has an electrode 50, a power supply 51, and a matching unit 52.
The power supply unit 5 is a high frequency power supply for generating the plasma P. That is, the power supply unit 5 is provided to generate high-frequency discharge in the plasma processing space 22 to generate the plasma P.
In the present embodiment, the power supply unit 5 serves as a plasma generation unit that generates the plasma P inside the processing container 2.
The electrode 50, the power supply 51, and the matching unit 52 are electrically connected by wiring.

The electrode 50 is provided outside the processing container 2 and on the window portion 21.
The electrode 50 may have a plurality of conductors that generate an electromagnetic field and a plurality of capacitors (capacitors).

The power source 51 applies high frequency power having a frequency of about 100 KHz to 100 MHz to the electrode 50. In this case, the power source 51 applies high frequency power having a relatively high frequency (for example, a frequency of 13.56 MHz) suitable for generating the plasma P to the electrode 50.
Further, the power source 51 may change the frequency of the high frequency power to be output.

The matching device 52 is provided between the electrode 50 and the power supply 51. The matching device 52 includes a matching circuit and the like for matching between the impedance on the power supply 51 side and the impedance on the plasma P side.

The plasma processing apparatus 1 is a dual frequency plasma etching apparatus having an inductively coupled electrode on the upper part and a capacitively coupled electrode on the lower part.
However, the plasma generation method is not limited to the exemplified one.
The plasma processing apparatus 1 may be, for example, a plasma processing apparatus that uses inductively coupled plasma (ICP) or a plasma processing apparatus that uses capacitively coupled plasma (CCP).

The decompression unit 6 has a pump 60 and a pressure control unit 61.
The decompression unit 6 decompresses the inside of the processing container 2 to a predetermined pressure.
The pump 60 can be, for example, a turbo molecular pump (TMP) or the like.
The pump 60 and the pressure control unit 61 are connected via a pipe.

The pressure control unit 61 controls the internal pressure of the processing container 2 to a predetermined pressure based on the output of a vacuum gauge or the like (not shown) that detects the internal pressure of the processing container 2.
The pressure control unit 61 can be, for example, an APC (Auto Pressure Controller) or the like.
The pressure control unit 61 is connected to an exhaust port 20e provided in the main body unit 20 via a pipe.

The gas supply unit 7 supplies the gas G1 to the plasma processing space 22 inside the processing container 2.
The gas supply unit 7 includes a gas storage unit 70, a gas control unit 71, and an opening/closing valve 72.
The gas storage unit 70 stores the gas G1 and supplies the stored gas G1 to the inside of the processing container 2.
The gas storage unit 70 can be, for example, a high-pressure cylinder that stores the gas G1. The gas storage unit 70 and the gas control unit 71 are connected via a pipe.

The gas control unit 71 controls the flow rate, pressure, and the like when the gas G1 is supplied from the gas storage unit 70 to the inside of the processing container 2.
The gas control unit 71 can be, for example, an MFC (Mass Flow Controller) or the like.
The gas control unit 71 and the open/close valve 72 are connected via a pipe.
The opening/closing valve 72 is connected to a gas supply port 20c provided in the processing container 2 via a pipe.
The on-off valve 72 controls supply and stop of the gas G1.
The on-off valve 72 can be, for example, a 2-port solenoid valve or the like.
The function of the opening/closing valve 72 may be provided in the gas control unit 71.

The gas G1 may generate radicals that can chemically etch the object to be processed 100 when excited and activated by the plasma P.
The gas G1 can be a gas containing a fluorine atom. The gas G1 can be, for example, CHF ₃ , CF ₄ , C ₄ F ₈ or the like.

The detection unit 8 detects the emission intensity of light of a specific wavelength generated inside the processing container 2 while the processing object 100 is being etched.
The detection unit 8 divides the light generated inside the processing container 2 into desired wavelengths and measures the emission intensity for each desired wavelength.
The detector 8 may include a spectroscope 80 and a converter 81.
The spectroscope 80 separates the light having a specific wavelength from the light generated inside the processing container 2. The spectroscope 80 can be provided with, for example, a prism. The wavelengths to be separated are, for example, 703.7 nm corresponding to the peak wavelength of fluorine, 656.5 nm corresponding to the peak wavelength of the peak wavelength of hydrogen, 777.2 nm corresponding to the peak wavelength of oxygen, and the peak wavelength of silicon fluoride. 777.0 nm, which corresponds to

The converter 81 converts the emission intensity of light of a specific wavelength separated by the spectroscope 80 into an electric signal. The conversion unit 81 can include, for example, a photoelectric conversion element, an amplifier, an analog-digital converter, and the like.

The control unit 9 includes a calculation unit such as a CPU (Central Processing Unit) and a storage unit such as a memory.
The control unit 9 controls the operation of each element provided in the plasma processing apparatus 1 based on the control program stored in the storage unit. Since a known technique can be applied to a control program for controlling the operation of each element, detailed description thereof will be omitted.

The control unit 9 controls, for example, a gate opening/closing mechanism (not shown) provided in the gate valve 20b to cause the gate opening/closing mechanism (not shown) to open and close the door 20b1.
The control unit 9 controls, for example, the power supply 40 and the matching device 41 to cause the power supply 40 and the matching device 41 to apply high-frequency power to the electrode 30.
The control unit 9 controls, for example, the power source 51 and the matching unit 52 to cause the power source 51 and the matching unit 52 to apply high-frequency power to the electrode 50.
For example, the control unit 9 causes the pressure control unit 61 to reduce the pressure inside the processing container 2 to a predetermined pressure based on the output of a vacuum gauge or the like (not shown) that detects the internal pressure of the processing container 2.
The control unit 9 controls, for example, the gas control unit 71 to control the flow rate and pressure of the gas G1 supplied to the plasma processing space 22.
The control unit 9 controls, for example, the on-off valve 72 to cause the on-off valve 72 to supply and stop the supply of the gas G1.

Furthermore, the calculation unit provided in the control unit 9 calculates the etching rate from the output from the detection unit 8 and the above-described correlation between the emission intensity and the etching rate stored in the storage unit. The end point time is calculated based on the calculated etching rate.
For example, first, during the etching process using the plasma P, the spectroscope 80 provided in the detection unit 8 separates light having a specific wavelength from the light generated inside the processing container 2.
Next, the conversion unit 81 provided in the detection unit 8 converts the emission intensity of the light of the specific wavelength separated by the spectroscope 80 into an electric signal.

Next, the calculation unit provided in the control unit 9 calculates the etching rate from the electric signal from the conversion unit 81 and the correlation between the emission intensity and the etching rate stored in the storage unit, The timing of the end point is calculated based on the calculated etching rate.

The specific wavelength can be any of the peak wavelength of fluorine, the peak wavelength of hydrogen, the peak wavelength of oxygen, and the peak wavelength of silicon fluoride.

The detection unit 8 can also detect the emission intensity at a plurality of time points.
The control unit 9 can calculate the etching rate from the detected average values of the emission intensity at a plurality of time points and the correlation described above.
Then, the control unit 9 calculates the etching time from the calculated etching rate and the desired etching amount, and sets the time point at which the elapsed time of the etching process reaches the calculated etching time as the end point of the etching process. be able to.
When the elapsed time of the etching process reaches the end point of the etching process, the control unit 9 controls the power supply 41 and the power supply 51 to stop the application of the high frequency power to the electrodes 30 and 50, and controls the gas supply unit 7. Then, the introduction of the gas G1 is stopped and the etching process is terminated.

The detection unit 8 can also detect the emission intensity at a predetermined time.
The control unit 9 calculates the etching rate from the detected emission intensity and the above-mentioned correlation, and calculates the etching amount from the calculated etching rate and the time until a predetermined time point.
Then, when the calculated etching amount reaches the desired etching amount, the control unit 9 sets the above-mentioned predetermined time point as the end point of the etching process.
In addition, when the calculated etching amount does not reach the desired etching amount, the control unit 9 based on the emission intensity detected again by the detection unit 8 after a lapse of a predetermined time from the above-mentioned predetermined time point. , The etching amount is calculated again. After that, the calculation is repeated until the calculated etching amount reaches a desired etching amount.
The detection of the end point of the etching process can be performed in the same manner as described above, and thus detailed description thereof will be omitted.

Next, the operation of the plasma processing apparatus 1 will be illustrated.
The door 20b1 of the gate valve 20b is opened by a gate opening/closing mechanism (not shown).
The processed product 100 is carried into the processing container 2 from the carry-in/carry-out port 20a by a carrying unit (not shown). The processed article 100 carried in is placed on the placing section 3.
A region containing silicon oxide as a main component is exposed on the surface of the object 100 to be etched.

The transport unit (not shown) is retracted to the outside of the processing container 2.
The door 20b1 of the gate valve 20b is closed by a gate opening/closing mechanism (not shown).
The decompression unit 6 decompresses the inside of the processing container 2 to a predetermined pressure. At this time, the pressure control unit 61 controls the internal pressure of the processing container 2 to be a predetermined pressure based on the output of a vacuum gauge or the like (not shown) that detects the internal pressure of the processing container 2.

Next, the gas G is supplied from the gas supply unit 7 to the plasma processing space 22 in the processing container 2.
In this case, the gas G can be a gas containing fluorine atoms. Therefore, the reaction product produced contains fluorine radicals. The gas containing a fluorine atom can be, for example, CHF ₃ , CF ₄ , C ₄ F ₈ or the like.

Next, the power source 51 applies high frequency power having a predetermined frequency (for example, a frequency of 13.56 MHz) to the electrode 50. Further, high frequency power having a predetermined frequency (for example, a frequency of 13.56 MHz or less) is applied to the electrode 30 by the power supply 41.

In this case, for example, the internal pressure of the processing container 2 is 0.2 Pa, the gas G is CHF ₃ , the flow rate of the gas G is 20 sccm, the power applied to the electrode 50 is 700 W, and the power applied to the electrode 30 is It can be 110W.

Since the electrode 50 constitutes an inductively coupled electrode, an electromagnetic field is introduced into the processing container 2 through the window 21. Therefore, the plasma P is generated in the plasma processing space 22 by the electromagnetic field introduced into the processing container 2. The gas G is excited and activated by the generated plasma P to generate a reaction product. The generated reaction product descends in the plasma processing space 22 and reaches the surface of the processing object 100, where etching processing is performed.

Next, the spectroscope 80 provided in the detection unit 8 separates the light of a specific wavelength from the light generated inside the processing container 2.
Next, the conversion unit 81 provided in the detection unit 8 converts the emission intensity of the light of the specific wavelength separated by the spectroscope 80 into an electric signal.

Next, the calculation unit provided in the control unit 9 calculates the end point of the etching process from the electrical signal from the conversion unit 81 and the correlation between the emission intensity and the etching rate stored in the storage unit. To do.
Next, the control unit 9 ends the etching process based on the calculated end point of the etching process. That is, when the end point is detected, the control unit controls the power source 41 and the power source 51 to stop the application of the high frequency power to the electrodes 30 and 50, and controls the gas supply unit 7 to stop the introduction of the gas G1. The etching process is terminated.

The embodiments have been illustrated above. However, the present invention is not limited to these descriptions.
A person skilled in the art appropriately modified the above-described embodiment is also included in the scope of the present invention as long as it has the features of the present invention.
For example, the shape, size, material, arrangement, number, etc. of each element included in the plasma processing apparatus 1 are not limited to those illustrated, but can be changed as appropriate.
Further, each element included in each of the above-described embodiments can be combined as much as possible, and a combination of these elements is also included in the scope of the present invention as long as including the features of the present invention.

DESCRIPTION OF SYMBOLS 1 plasma processing apparatus, 2 processing container, 3 mounting part, 4 power supply part, 5 power supply part, 6 decompression part, 7 gas supply part, 8 detection part, 9 control part, 22 plasma processing space, 30 electrodes, 40 power supply, 50 electrodes, 51 power supply, 100 processed products, G gas, P plasma

Claims (11)

A plasma treatment method for terminating the plasma etching treatment in the middle of the thickness of the object to be treated,
Etching the processed material with a reaction product generated from gas,
A step of obtaining an emission intensity of light of a specific wavelength generated in the plasma processing space while etching the processing object,
From the obtained emission intensity, and the correlation between the emission rate of the light of the specific wavelength obtained by continuously performing the etching process in advance under the same conditions and the etching rate calculated from the etching amount , from The step of determining the etching rate,
Based on the obtained etching rate, the step of detecting the end point of the etching,
And a plasma treatment method. The processed product contains silicon oxide as a main component,
The plasma processing method according to claim 1, wherein the gas contains fluorine atoms. The plasma processing method according to claim 2, wherein the specific wavelength is any one of a peak wavelength of fluorine, a peak wavelength of hydrogen, a peak wavelength of oxygen, and a peak wavelength of silicon fluoride. In the step of obtaining the emission intensity of light of the specific wavelength, the emission intensity at a plurality of time points is obtained,
The plasma processing method according to any one of claims 1 to 3, wherein in the step of obtaining the etching rate, the etching rate is obtained from the obtained average value of emission intensity at a plurality of time points and the correlation. .. In the step of detecting the end point,
From the obtained etching rate and the desired etching amount, the etching time is obtained,
The plasma processing method according to any one of claims 1 to 4, wherein a time point when the elapsed time of the etching process in the step of etching the object to be processed reaches the determined etching time is an end point of the etching process. In the step of obtaining the emission intensity of the light of the specific wavelength, the emission intensity at a predetermined time point is obtained,
In the step of obtaining the etching rate, the obtained emission intensity and the correlation, the etching rate is obtained,
In the step of detecting the end point,
From the obtained etching rate and the time until the predetermined time point, the etching amount is obtained,
When the etching amount reaches a desired etching amount, the predetermined time point is taken as the end point of the etching treatment,
If the etching amount does not reach the desired etching amount, based on the emission intensity obtained again by the step of obtaining the emission intensity of the light of the specific wavelength after the passage of a predetermined time from the predetermined time point. The plasma processing method according to claim 1, wherein the etching amount is obtained again. A processing container,
A mounting portion provided inside the processing container for mounting a processed product containing silicon oxide as a main component,
A decompression unit for decompressing the inside of the processing container,
A plasma generating unit for generating plasma inside the processing container,
Inside the processing container, a gas supply unit for supplying a gas containing a fluorine atom,
When etching the processing object, a detection unit for detecting the emission intensity of light of a specific wavelength generated inside the processing container,
From the detected emission intensity and the correlation between the emission intensity of the light of the specific wavelength and the etching rate calculated from the etching amount obtained by continuously performing the etching process in advance under the same conditions , and A control unit that calculates an etching rate, and based on the calculated etching rate, calculates a timing of the end point of the etching,
And a plasma processing apparatus. The plasma processing apparatus according to claim 7, wherein the specific wavelength is any one of a peak wavelength of fluorine, a peak wavelength of hydrogen, a peak wavelength of oxygen, and a peak wavelength of silicon fluoride. The detection unit detects the emission intensity at a plurality of time points,
9. The plasma processing apparatus according to claim 7, wherein the control unit calculates the etching rate from the average value of the emission intensity at the detected plurality of time points and the correlation. The control unit calculates the etching time from the calculated etching rate and the desired etching amount, and the elapsed time of the etching process is the end point of the etching process at the time when the calculated etching time is reached. The plasma processing apparatus according to any one of claims 7 to 9. The detection unit detects the emission intensity at a predetermined time point,
The control unit is
Calculate the etching rate from the detected emission intensity and the correlation,
From the calculated etching rate and the time to the predetermined time point, the etching amount is calculated,
When the etching amount reaches a desired etching amount, the predetermined time point is taken as the end point of the etching treatment,
When the etching amount does not reach the desired etching amount, the etching amount is calculated again based on the emission intensity detected again by the detection unit after a predetermined time has elapsed from the predetermined time point. The plasma processing apparatus according to claim 7.

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