JPH10335309A - Plasma treating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treating system, capable of treating at all times at an optimum condition against the variation in the optimum condition during the plasma treatment. SOLUTION: This plasma etching system is constituted of a process changer 10 for a plasma-etching treatment, a monitor 38 with an emission spectrometer 40 for monitoring the compsn. of a plasma 18, e.g., the emitted intensity of 10 in the plasma 18 during the plasma etching in the process chamber 10, a main controller and a gas controller in a CPU 42 for controlling etching process parameters, e.g., the flow ratio of etching gases CF4 to CHF3 via mass flow controller 22, based on the monitored result, thus realizing the so-called in-situ monitoring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing system, and more particularly, to a plasma etching system (Plass processing system).
ma Etching System) and plasma enhanced CVD system (Plasma Enhanced Chemical Vapor Deposition System)
m).

[0002]

2. Description of the Related Art In a conventional plasma etching system, a pair of parallel plate type upper and lower electrodes are installed in a process chamber as a reduced pressure type reaction chamber, and a wafer is loaded on the lower electrode. It has become. A high frequency is applied to a gas supply control unit such as a mass flow controller for supplying a reaction gas into the process chamber, an exhaust unit such as a vacuum pump for exhausting a gas in the process chamber 10, and a lower electrode in the process chamber. A high-frequency oscillator or the like for generating plasma between the upper electrode and the like is provided.

[0005] An etch back process using such a plasma etching processing system is shown in FIGS.
This will be described with reference to FIG. On the silicon substrate 70, for example, A
After processing the l (aluminum) wiring layer 72, for example, C
Using a VD method, Si as an interlayer insulating film is
An O ₂ film (silicon oxide film) 74 is deposited. At this time,
The surface of the SiO ₂ film 74 has an uneven shape due to the step structure formed by the underlying silicon substrate 70 and Al wiring layer 72. Then, so as to fill the unevenness of the surface on the SiO ₂ film 74, low viscosity SOG (Spin On Glas
s) The film 76 is coated to a sufficient thickness (see FIG. 7).

Subsequently, in the reaction chamber of the conventional plasma processing system, the entire surface of the SOG film 76 is etched using, for example, a mixed gas of CF ₄ and CHF ₃ as an etching gas. At this time, the etching rate of the underlying SiO ₂ film 74 and the etching rate of the SOG film 76 are made equal beforehand, that is, the SiO ₂ film 74 and the SOG film 7
CF ₄ and C so that the etching selectivity to
The flow ratio of the mixed gas with HF ₃ is set in advance. In this manner, the entire surface of the SOG film 76 is etched to expose the surface of the underlying SiO ₂ film 74 (see FIG. 8).

Subsequently, the coexisting SOG film 76 and SiO
_The etching of the entire surface of the _second film 74 proceeds. At this time, S
The etching of the OG film 76 and the SiO ₂ film 74 is a condition set to proceed at the same rate, but it should both be flat etching without boundary would otherwise oxygen by etching the SiO ₂ film 74 Is generated, a change occurs in the etching selectivity, which is the ratio of the two etching rates. That is, the oxygen generated by the etching of the SiO ₂ film 74 affects the SOG film 7.
6 is increased, the SiO ₂ film 74 and the SO
The etching selectivity with the G film 76 becomes smaller than 1.

Accordingly, the surface of the SOG film 76 at the valley between the Al wiring layers 72 has a shape that is lower than the surface of the SiO ₂ film 74, and the flatness of the surface of the base is deteriorated. That is, S
Good flatness consisting of the OG film 76 and the SiO ₂ film 74 cannot be obtained (see FIG. 9).

In order to cope with such deterioration of flatness,
In the SOG etch-back process using the conventional plasma processing system, when the etching of the entire surface of the SOG film 76 is started, a change in the etching selectivity between the two when the etching of the SiO ₂ film 74 is added thereafter is taken into consideration. In general, a method of setting a flow ratio of a mixed gas of CF ₄ and CHF ₃ in advance so that the etching rate of the SOG film 76 is slightly reduced is generally adopted. This allows
When simultaneously etching the coexisting SOG film 76 and SiO ₂ film 74, the etching selectivity of both becomes 1,
The flatness of the surface of the SOG film 76 and the surface of the SiO ₂ film 74 can be obtained.

[0008]

As described above, in the SOG etch-back process using the above-described conventional plasma processing system, when starting etching of the entire surface of the uppermost coating film, a subsequent interlayer insulating film is formed. It is necessary to set the flow ratio of the mixed etching gas in consideration of the change in the etching selectivity of both when the etching of the above is added, but the setting conditions are the coverage of the coating film, the coverage of the interlayer insulating film, or Since it varies depending on the device pattern and the like, the margin for setting the optimum condition is reduced. Therefore, there is a problem that it is difficult to stably obtain sufficiently good flatness.

Therefore, the present invention has been made in view of the above problems, and even if the optimum conditions fluctuate during the plasma processing, it is possible to always perform processing under the optimum conditions in response to the fluctuations. It is an object to provide a simple plasma processing system.

[0010]

The above object is achieved by the following plasma processing system according to the present invention. That is, the plasma processing system according to claim 1 includes a reaction chamber for performing plasma processing on a sample, a monitoring unit for monitoring the composition of plasma during the plasma processing in the reaction chamber, and a monitoring result of the plasma composition by the monitoring unit. And a control unit for controlling a processing parameter during the plasma processing based on the control information.

Thus, in the plasma processing system according to the first aspect, the monitoring unit monitors the composition of the plasma during the plasma processing, and the control unit controls the processing parameters during the plasma processing based on the monitoring result. Detects the change of the plasma composition even if the plasma composition changes during the plasma processing and the optimum conditions fluctuate, and controls the plasma processing parameters to meet the new optimum conditions after the fluctuations Therefore, plasma processing is always performed under optimum conditions. It should be noted that constantly monitoring the situation in the progress of the process in this way is also called in-process monitoring or in-situ monitoring.

According to a second aspect of the present invention, in the plasma processing system of the first aspect, the plasma processing is an etching process using a reactive gas plasma. By monitoring the composition of the plasma in the chamber and detecting a change in the composition of the plasma, it is possible to change the etching process parameters so as to respond to changes in the optimum conditions due to this change. Processing is performed.

Therefore, for example, in a flattening process using a back etch method, if a new underlying interlayer insulating film is added to the uppermost coating film to be etched during the etching process, the interlayer insulating film is formed by etching. Even if the etching selectivity between the coating film and the interlayer insulating film fluctuates due to the influence of an object, the composition of the plasma due to this product is monitored to detect the change, and the change in the etching selectivity due to the change in the plasma composition. By changing the etching process parameters so that the etching rate of the coating film and the etching rate of the interlayer insulating film become equal while suppressing the occurrence of the problem, it becomes possible to obtain good flatness including the coating film and the interlayer insulating film. .

In addition to the above-described case where the etching rate fluctuates due to the influence of a product generated by etching, the composition of the plasma generated by the product is monitored and the change is not limited to the case where the etching target is increased from the middle. Is detected, and an etching process parameter is changed so as to suppress a change in an etching rate due to a change in the composition of the plasma, whereby an optimum shape can be obtained.

According to a third aspect of the present invention, in the plasma processing system of the first aspect, the plasma processing is a CVD (chemical vapor deposition) processing of a thin film using a reactive gas plasma. This makes it possible to monitor the composition of the plasma during the plasma CVD process and detect its change, and to change the CVD process parameters so as to correspond to the change in the optimum condition due to this change. Plasma CV
D processing is performed.

Therefore, for example, in a CVD process for depositing a thin film on a semiconductor substrate, the deposition rate at the time when the nucleus of the first thin film is formed on the semiconductor substrate and the deposition rate of the thin film after the nucleus of the thin film has already been formed are deposited. Since the deposition rate is different from the deposition rate at the time of the deposition, the composition of the plasma during the plasma CVD process during this period is monitored to detect a change in the composition. The thickness of the thin film can be controlled with high accuracy by changing the CVD process parameters so that the deposition rate of the thin film becomes constant.

According to a fourth aspect of the present invention, in the plasma processing system according to the first aspect, the monitoring unit monitors the emission intensity of a specific element of the plasma during the plasma processing. Changes in the composition of the plasma during processing are easily detected. For example, in the planarization process using the back-etch method as described above, when the number of etching targets increases in the middle, the luminescence intensity of a specific element constituting a product formed by etching of a new target is monitored to change the luminescence intensity. And it can be detected that the etching selectivity fluctuates due to the influence of this product.

According to a fifth aspect of the present invention, in the plasma processing system according to the first aspect of the present invention, the monitoring unit monitors a mass spectrum of a gas composition during the plasma processing to specify the plasma. As in the case of monitoring the emission intensity of the element, a change in the composition of the plasma during the plasma processing is easily detected.

In the plasma processing system according to the first aspect of the present invention, the plasma composition changes during the plasma processing, and the optimum conditions fluctuate. The plasma processing parameters are adjusted to meet the new optimum conditions after the fluctuation. When controlling, the plasma processing parameters to be controlled include gas flow during plasma processing, gas supply stop,
Additional gas supply, high frequency, reaction chamber pressure, and sample temperature are appropriate.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing a plasma etching processing system according to one embodiment of the present invention. As shown in FIG. 1, in the plasma etching processing system according to the present embodiment, a pair of parallel plate-type upper electrodes 12 and lower electrodes 14 are installed facing each other in a process chamber 10 as a reduced-pressure reaction chamber. And
A wafer 16 is loaded on the lower electrode 14 and a plasma 18 is placed between the upper electrode 12 and the lower electrode 14.
Is caused to occur.

In the process chamber 10,
A reaction gas such as CF ₄ or CHF ₃ is supplied from a factory gas supply line 20 through an open / close valve 24 via a mass flow controller 22 as a gas supply control unit. Further, the gas and the like in the process chamber 10 pass through a pressure control butterfly valve 26 and an exhaust open / close valve 28, and pass through a vacuum pump 30 as an exhaust unit.
As a result, the gas is discharged to the factory exhaust line 32 and the inside of the process chamber 10 is maintained at a predetermined reduced pressure.

A high-frequency oscillator 34 having one end grounded is connected to the lower electrode 14 in the process chamber 10 via a capacitor 36.
4 applies a high frequency to the lower electrode 14,
A plasma 18 is generated between the first electrode and the upper electrode 12.

A monitor 38 as a monitoring unit and an emission analyzer 40 are provided.
8, the plasma 18 in the process chamber 10 is detected, and the result is analyzed by an emission analyzer 40 to monitor the emission intensity of a specific element in the plasma 18. Further, a vacuum gauge 42 is connected to and installed in the process chamber 10.
The pressure within 0 is measured.

An emission analyzer 40 as a monitoring unit is connected to a main controller 48 via a plasma signal converter 46 of a CPU (central processing unit) 44, and monitors the emission intensity of a specific element in the plasma 18 by monitoring. The CPU 4 outputs information on the detected change in the emission intensity.
2 to the main controller 48. The vacuum gauge 42 is also connected to the main controller 48 of the CPU 42, and transmits information on the measured pressure in the process chamber 10 to the main controller 48.

The main controller 4 of the CPU 42
8 is a gas controller 50, a high-frequency controller 5
2. Each is connected to the pressure controller 54.
Further, the gas controller 50 is connected to the mass flow controller 22 as a gas supply control unit, the high frequency controller 52 is connected to the high frequency oscillator 34, and the pressure controller 54 is connected to the pressure control butterfly valve 26.
, Respectively. Thus, the plasma 18
The mass flow controller 22, the high-frequency oscillator 34, and the butterfly valve 26 for controlling the pressure are controlled based on the change of the emission intensity of the specific element in the gas, the gas flow rate of the reaction gas during the plasma processing, the high frequency, the pressure in the reaction chamber, and the like. Are adapted to the optimum conditions.

Next, an SOG etch-back process using the plasma etching system shown in FIG.
This will be described with reference to FIG. Here, FIGS. 2 to 4 are process cross-sectional views for explaining the SOG etch-back process, FIG. 5 is a graph showing the relationship between the flow rate ratio of the reaction gas and the etching selectivity in the SOG etch-back process, and FIG. 5 is a graph showing a change in oxygen emission intensity in plasma monitored in an SOG etch-back process.

(1) Wafer Loading First, a wafer 16 is loaded on the lower electrode 14 in the process chamber 10. This wafer 16
As shown in FIG. 2, an SiO ₂ film 64 as an interlayer insulating film is deposited by using, for example, a CVD method on the entire surface of a substrate on which, for example, an Al wiring layer 62 is processed on a silicon substrate 60. And the surface of this SiO ₂ film 64 is
The uneven structure is formed by the step structure formed by the underlying silicon substrate 60 and the Al wiring layer 62. Furthermore, this Si
On the O ₂ film 64, so as to bury unevenness on the surface thereof,
The SOG film 66 having low viscosity is coated (applied) to a sufficient thickness.

(2) Start of Etching The vacuum pump 30 is operated and the pressure controller 54 controls the pressure control butterfly valve 26.
Is controlled so that the inside of the process chamber 10 reaches a predetermined degree of vacuum. Subsequently, the gas controller 50 controls the mass flow controller 22 to supply a predetermined flow rate of a reactive gas such as CF ₄ and CHF ₃ into the process chamber 10. Here, the flow rate ratio of the mixed gas of CF ₄ and (CF ₄ + CHF ₃ ) is preset to P ₀ in the graph of FIG. 5 as the initial flow rate condition of the reaction gas, and the etching rate of the SOG film and the SiO ₂ film The etching rate is made equal, that is, the etching selection ratio between the SiO ₂ film and the SOG film is set to 1 at the selection ratio indicated by the solid line in the graph.

Then, the high-frequency oscillator 34 is controlled by the high-frequency controller 52 to apply a high frequency of 13.56 MHz to the lower electrode 14 in the process chamber 10, and the plasma 1 is applied between the upper electrode 12 and the lower electrode 14.
8 is generated. Thus, the entire surface of the uppermost SOG film 66 of the wafer 16 loaded on the lower electrode 14 is started to be etched.

Simultaneously with the start of the etching, the plasma 18 generated in the process chamber 10 is detected by the monitor 38, and the result is analyzed by the emission analyzer 40 to monitor the emission intensity of oxygen in the plasma 18. Start. Then, information on a change in the emission intensity detected by monitoring the emission intensity of the specific element in the plasma 18 is transmitted to the main controller 48 of the CPU 42.

(3) Etching of SOG Film 66 The entire surface of the SOG film 66 is etched by plasma 18 of CF ₄ and CHF ₃ as an etching gas. As the overall etching of the SOG film 66 progresses,
As shown in FIG. 3, the surface of the underlying SiO ₂ film 64 is exposed. When the plasma 18 in the process chamber 10 in the etching process of the SOG film 66 is monitored by the monitor 38 and the emission analyzer 40, as shown in the graph of FIG. from the start time T0 to the emission intensity a ₁ in a short time rapidly increases, but then T ₁
Between to exposure time T ₂ of the SiO ₂ film 64 surface of the base is maintained at a constant emission intensity A _1.

(4) Simultaneous etching of SOG film and SiO ₂ film The exposed underlying SiO ₂ film 64 and this S ₂ film are etched by plasma 18 of CF ₄ and CHF ₃ as etching gas.
Simultaneous etching of the SOG film 66 remaining in the concave portion of the iO ₂ film 64 is performed.

The coexisting SOG film 66 and Si
The plasma 18 in the process chamber 10 when simultaneously etching the O ₂ film 64 is monitored by the monitor 38 and the emission analyzer 4.
0, the emission intensity of oxygen in the plasma 18 is SiO 2 as shown in the graph of FIG.
Gradually increases from ₂ film 64 luminous intensity A ₁ exposure time T ₂ of the surface. The increase in the emission intensity of oxygen in the plasma 18 is caused by the generation of oxygen by the etching of the newly added SiO ₂ film 64.

If such a situation is left as it is, the above-mentioned FIGS.
As already described with reference to FIG. 9, oxygen generated by etching the SiO ₂ film 64 affects the SOG film 6.
6 is increased, the SiO ₂ film 64 and SO ₂
Since the etching selectivity with respect to the G film 66 is smaller than 1, the surface of the SOG film 66 at the valley between the Al wiring layers 62 has a shape lower than the surface of the SiO ₂ film 64, and S
The flatness of each surface of the OG film 66 and the SiO ₂ film 64 is deteriorated.

Therefore, when the emission intensity of oxygen in the plasma 18 increases from the emission intensity A ₁ and reaches the emission intensity A ₂ which is a predetermined trigger value, the information is transmitted to the emission analyzer 40.
To the main controller 48 of the CPU 42. Then, the mass flow controller 22 is controlled via the gas controller 50 to change the flow ratio of CF ₄ and (CF ₄ + CHF ₃ ) supplied into the process chamber 10 to P ₁ in the graph of FIG. Is made smaller than the etching rate of the SiO ₂ film. In this manner, the etching selectivity between the SiO ₂ film and the SOG film when the coexisting SOG film and the SiO ₂ film are simultaneously etched, as indicated by the dashed line in the graph, is set to 1.

Accordingly, after the time T ₃ at which the oxygen in the plasma 18 reaches the emission intensity A ₂ which is the predetermined trigger value, S ₃
The OG film 66 and the SiO ₂ film 64 are simultaneously etched at the same rate. That is, the SOG film 66 and the SiO ₂ film 64
The overall etching proceeds while the good flatness of each surface is maintained.

[0037] (5) the surfaces of the ends SOG film 66 and the SiO ₂ film 64 of the etching to proceed entirely etched remain flat state, as shown in FIG. 4, the thickness of the SiO ₂ film 64 remaining at time T ₄ Because became a predetermined thickness, and terminates the etching. That is,
The high-frequency controller 52 stops the oscillation of the high-frequency oscillator 34, and the gas controller 50 controls the mass flow controller 22 to stop the supply of the etching gas CF ₄ and CHF ₃ into the process chamber 10 and the N 2 (nitrogen) gas. Supply inert gas such as
The pressure in the process chamber 10 is made equal to the atmospheric pressure. At the same time as the completion of the etching, the process chamber 10 by the monitor 38 and the emission analyzer 40 is used.
The monitoring of the emission intensity of oxygen in the plasma 18 in the inside is stopped.

(6) Wafer Unloading The wafer 16 is unloaded from the lower electrode 14 in the process chamber 10. At this time, the Al wiring layer 62 on the silicon substrate 60 is covered with the SOG film 66 and the SiO ₂ film 64 as shown in FIG.
The surface of the SiO ₂ film 64 is well flattened.

As described above, according to the present embodiment, the SOG film 66 is coated to a sufficient thickness on the SiO ₂ film 64 having the unevenness due to the step structure of the base, and then the entire surface of the wafer 16 is etched by etching. S to flatten
In the OG etch-back process, a process chamber 10 for performing a plasma etching process, and a monitor 38 as a monitoring unit for monitoring the composition of the plasma 18 during the plasma etching process in the process chamber 10, for example, the emission intensity of oxygen in the plasma 18 And an emission analyzer 40, and a main controller 48 and a gas controller 50 of the CPU 42 for controlling an etching process parameter, for example, a flow rate ratio of the etching gases CF ₄ and CHF ₃ via the mass flow controller 22 based on the monitoring result. By using a plasma etching processing system, S
The etching of the entire surface of the OG film 66 proceeds, and the underlying SiO ₂
When the surface of the film 64 is exposed, the influence of oxygen generated by etching the new SiO ₂ film 64
Even if the etching selectivity between the O ₂ film 64 and the SOG film 66 fluctuates, information from the emission analyzer 40 indicates that the emission intensity of oxygen in the plasma 18 has increased to the emission intensity A ₂ which is a predetermined trigger value. It is transmitted to the gas controller 50 via the main controller 48,
By controlling the flow rate ratio of the etching gases CF ₄ and CHF ₃ via 0 through the mass flow controller 22, 0 is adjusted so that the etching selectivity of both the coexisting SOG film and the SiO ₂ film becomes 1 at the same time. Therefore, the entire surface of the SOG film 66 and the SiO ₂ film 64 are simultaneously etched at the same rate, so that good flatness can be obtained.

As described above, when the surface of the wafer 16 is planarized by the SOG etch-back process, even if the optimum conditions during the plasma etching process are changed, the plasma 18
By monitoring the emission intensity of oxygen in oxygen and detecting the change, a change in the optimum condition is detected, and the etching process parameters such as the etching gas CF ₄ and CHF ₃ are adjusted to meet the new optimum condition after the change. , And the plasma etching process is always performed under the optimum condition, so that the flattening margin can be expanded more than before.

Further, since the present invention is applied to the SOG etch-back process conventionally used as the flattening process, sufficient back data accumulated so far can be utilized. In this regard, new planarization techniques that do not store enough data, such as CM
This is superior to the case where P or damascene is adopted.

Further, the present invention can be applied to a so-called resist etch-back process in which a resist film is used instead of the SOG film.
The same effects as in the case of the present embodiment in which the present invention is applied to the etch-back process can be obtained.

Further, the plasma etching processing system according to the present embodiment can be dealt with by partially modifying the existing plasma etching processing system, and a next-generation system requiring expensive capital investment is introduced. Since it is not necessary, an increase in the manufacturing cost of the semiconductor device can be suppressed.

In the above embodiment, the emission intensity of oxygen in the plasma 18 is monitored for each SOG etch-back process for flattening the surface of the wafer 16, and the etching process parameters are adjusted so as to correspond to fluctuations in the optimum conditions. However, when mass production is performed under the same conditions, the etching process parameters may be controlled based on the temporal change of the emission intensity of oxygen in the plasma 18 shown in the graph of FIG.

In the above embodiment, the plasma is generated by applying a high frequency to the parallel plate electrodes. However, the present invention is not limited to this plasma generation mechanism. For example, the plasma is generated by a microwave and a magnetic field. Microwave plasma generation mechanism and helicon (helico) which is a kind of electromagnetic wave propagating along the magnetic field
n) Helicon plasma generation mechanism that generates plasma by interaction between waves and electrons, ICP (Inductively Coupled Plasma) generation mechanism that generates plasma by accelerating electrons by induced electric field generated by high-frequency induction magnetic field, etc. May be used.

Further, in the above embodiment, the SOG etch-back process for simultaneously etching the coexisting SOG film 66 and the SiO ₂ film 64 at the same rate over the entire surface has been described. The present invention can be applied not only to the process but also to one type of thin film etching process. In this case, instead of monitoring the emission intensity of oxygen generated by the etching of the SiO ₂ film 64 to be etched from the middle as in the above-described embodiment, the plasma composition during the plasma etching process is changed to the plasma composition. What is necessary is just to monitor the emission intensity of the product element in the plasma generated by etching one type of thin film and detect the change. Then, by controlling the etching processing parameters so as to suppress the fluctuation of the etching rate based on the result, it becomes possible to obtain the optimum thin film shape.

The present invention can also be applied to an etching process for three or more types of multilayer thin films. In this case as well, the change may be detected by monitoring the emission intensity of the product element in the plasma generated by etching the three or more types of multilayer thin films. Then, by controlling the etching process parameters based on the result, it becomes possible to enlarge the process window of three or more types of multilayer thin films. Accordingly, the response to the processing of a multilayer thin film having a high etching selectivity required with miniaturization of a semiconductor device is expanded.

In the plasma etching system according to the above embodiment, the monitor 38 and the emission analyzer 40 are installed as monitoring units to monitor the emission intensity of a specific element in the plasma 18, for example, oxygen. Instead, a method of monitoring the mass spectrum of the gas composition in the plasma may be used. In this case, similarly to the case of the above embodiment, a change in the composition of the plasma during the plasma processing can be easily detected. However, as the monitoring unit, a mass analyzer is provided instead of the emission analyzer 40 or the like.

Further, in the above embodiment, the etch-back process for flattening the surface of the wafer 16 using the plasma etching processing system has been described. The present invention can also be applied to a thin film CVD process using plasma. In this case, instead of the plasma etching processing system according to the above embodiment, a process chamber for performing a plasma CVD process on a wafer, and a composition of a plasma during the plasma CVD process in the process chamber, for example, an emission analyzer or a mass spectrometer Monitoring unit, such as a vessel, and the CVD being processed based on the monitoring result
Plasma CVD having a CPU gas controller, a wafer temperature controller, and the like for controlling processing parameters
Use a processing system. And this plasma CVD
Depending on the processing system, for example, when depositing a thin film on a silicon substrate, the deposition rate when the first thin film nucleus is formed on the silicon substrate and when depositing the thin film after the thin film nucleus has already been formed Therefore, the composition of the plasma during the plasma CVD process during this period is monitored to detect a change in the composition, and a change in the deposition rate is suppressed based on the result to constantly adjust the deposition rate of the thin film. By controlling the CVD processing parameters to be constant, it is possible to control the thickness of the thin film with high precision.

[0050]

As described above, according to the plasma processing system of the present invention, the following effects can be obtained. That is, according to the plasma processing system of the first aspect, the monitoring unit monitors the composition of the plasma during the plasma processing, and the control unit controls the processing parameters during the plasma processing based on the monitoring result. Even if the optimum conditions fluctuate due to changes in the plasma composition during processing,
Since a change in the composition of the plasma can be detected and the plasma processing parameters can be controlled to conform to the new optimum conditions after the change, the plasma processing can always be performed under the optimum conditions. In addition, this plasma processing system can be coped with by partially modifying an existing plasma processing system, and it is not necessary to introduce a next-generation system that requires expensive capital investment. It is possible to suppress an increase in manufacturing cost.

According to a second aspect of the present invention, there is provided the plasma processing system according to the first aspect, wherein the plasma processing is an etching processing using a reactive gas plasma. The composition of the plasma is monitored to detect a change in the composition of the plasma, and it is possible to change the etching processing parameters so as to respond to the change in the optimum conditions due to the change. Therefore, the plasma etching processing is always performed under the optimum conditions. be able to. Therefore, for example, in a flattening process using a back etch method, when a new underlying interlayer insulating film is added to the uppermost coating film as an etching target in the middle of the etching process, the influence of the product due to the etching of the interlayer insulating film is exerted. Even if the etching selectivity between the coating film and the interlayer insulating film fluctuates, the composition of the plasma due to this product is monitored to detect the change, and the change in the etching selectivity due to the change in the plasma composition is suppressed. Control the etching parameters so that the etching rate of the coating film becomes equal to the etching rate of the interlayer insulating film, thereby obtaining good flatness and expanding the flattening margin more than before. Becomes possible. Also, by applying the present invention to a multilayer thin film etching process, it is possible to expand a process window of the multilayer thin film. The response can be expanded.

According to a third aspect of the present invention, there is provided the plasma processing system according to the first aspect, wherein the plasma processing is a thin film CVD processing using a reactive gas plasma. Is monitored by monitoring the composition of the plasma, and C is adjusted so as to cope with a change in the optimum condition due to the change.
Since it becomes possible to control the VD processing parameters,
Plasma CVD processing can always be performed under optimal conditions. Therefore, for example, in a plasma CVD process for depositing a thin film on a semiconductor substrate, the deposition rate when the first thin film nucleus is formed on the semiconductor substrate and the thin film after the thin film nucleus has already been formed are deposited. Even if the deposition rate is different from that at the time, the composition of the plasma at that time is monitored to detect the change, and the fluctuation of the deposition rate due to the change of the composition of the plasma is suppressed, so that the deposition rate of the thin film is always increased. By controlling the CVD process parameters so as to be constant, the thickness of the thin film can be controlled with high precision.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a plasma etching processing system according to an embodiment of the present invention.

FIG. 2 is a process sectional view (part 1) for describing an SOG etch-back process using the plasma etching processing system shown in FIG. 1;

FIG. 3 is a process sectional view (part 2) for describing the SOG etch-back process using the plasma etching processing system shown in FIG. 1;

FIG. 4 is a process sectional view (part 3) for describing an SOG etch-back process using the plasma etching processing system shown in FIG. 1;

FIG. 5 is a graph showing a relationship between a flow rate ratio of a reaction gas and an etching selectivity in an SOG etchback process.

FIG. 6 is a graph showing a change in oxygen emission intensity in plasma monitored in an SOG etch-back process.

FIG. 7 is a process sectional view (part 1) for describing an SOG etch-back process using a conventional plasma etching processing system.

FIG. 8 is a process sectional view (part 2) for describing the SOG etch-back process using the conventional plasma etching processing system.

FIG. 9 is a process sectional view (part 3) for describing the SOG etch-back process using the conventional plasma etching system.

[Explanation of symbols]

10 Process chamber, 12 Upper electrode, 14 Lower electrode, 16 Wafer, 18 Plasma, 20 Factory gas supply line, 22 Mass flow controller, 24
Open-close valve, 26 ... Butterfly valve for pressure control, 28 ... Open-close valve for exhaust, 30 ... Vacuum pump, 32 ... Factory exhaust line, 34 ...
High frequency oscillator, 36 ... capacitor, 38 ... monitor, 40
... Emission analyzer, 42 ... Vacuum gauge, 44 ... CPU, 46 ... Plasma signal converter, 48 ... Main controller, 50 ...
Gas controller, 52 ... High frequency controller, 54 ...
Pressure controller, 60: silicon substrate, 62: Al wiring layer, 64: SiO ₂ film, 66: SOG film, 70: silicon substrate, 72: Al wiring layer, 74: SiO ₂ film, 76
... SOG film.

Claims (6)

[Claims] 1. A reaction chamber for performing plasma processing on a sample, a monitoring unit for monitoring plasma composition during plasma processing in the reaction chamber, and a monitoring unit for monitoring plasma composition based on a result of monitoring the plasma composition by the monitoring unit. A plasma processing system, comprising: a control unit that controls a processing parameter. 2. The plasma processing system according to claim 1, wherein the plasma processing is an etching processing using a reactive gas plasma. 3. The plasma processing system according to claim 1, wherein the plasma processing is a chemical vapor deposition of a thin film using a reactive gas plasma. 4. The plasma processing system according to claim 1, wherein the monitoring unit monitors the emission intensity of a specific element of the plasma during the plasma processing. 5. The plasma processing system according to claim 1, wherein the monitoring unit monitors a mass spectrum of a gas composition during the plasma processing. 6. The plasma processing system according to claim 1, wherein the control unit controls a gas flow rate during plasma processing, a gas supply stop, a gas supply addition, a high frequency, a pressure in the reaction chamber, and a temperature of the sample. Controlling at least one of the following.