JP2002353201A - Plasma monitoring device and plasma monitoring method - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To reduce the storage capacity of a data storage device to reduce cost, and to reduce malfunction due to the influence of noise such as a high-frequency power supply. Provided are a plasma monitoring device and method for a semiconductor device. The measuring unit is connected to a measuring unit for measuring a plasma impedance, and determines whether or not the level of the measured data satisfies a preset storage start level. A data acquisition start level judging unit 11 for judging the start of storage, and judging whether or not the level of the measurement data satisfies a preset storage end level, and based on the judgment result,
An acquisition end level judging unit 12 for judging the end of the measurement data is provided, and only the data at the time of plasma generation is stored without inputting a signal from the plasma generation power control device 4, and a minimum device configuration is required. I do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma monitoring method and a plasma monitoring apparatus, and more particularly, to a plasma monitoring of a plasma processing apparatus used for plasma processing in manufacturing a semiconductor device, a liquid crystal display device, and the like.

[0002]

2. Description of the Related Art In recent years, semiconductor wafers, especially silicon wafers, glass substrates for liquid crystal, and the like have been rapidly increasing in size.
For this reason, in plasma processing such as etching and film formation in the manufacture of semiconductor devices and liquid crystal display devices, uniform etching or film formation over the entire substrate has become a very important issue.

In particular, in the field of semiconductor devices, the miniaturization of semiconductor devices has been progressing with the increase in the integration of semiconductor devices. For this reason, high quality and highly reliable processing steps are required even in the field of etching or film formation. Therefore, there is a plasma processing using plasma as a method capable of performing relatively low-temperature processing and performing high-precision processing. Even in such plasma processing, it is necessary to always maintain a stable plasma state in order to perform high-precision processing. Therefore, conventionally, various methods have been proposed for monitoring a plasma state.

A conventional plasma state monitoring method will be described with reference to FIG. As shown in FIG. 3, a conventional plasma processing apparatus has an upper electrode 6 mounted on an upper portion of a chamber 3 which is a reaction chamber for generating plasma.
And a substrate 7 to be processed provided opposite to the upper electrode 6.
, A vacuum pump (not shown) for evacuating the chamber 3, a gas supply source (not shown) for supplying a desired gas into the chamber, the upper electrode 6 and the lower electrode A high-frequency power supply 1 for supplying a high-frequency voltage between the electrodes 2 and generating plasma is provided.

The lower electrode 2 is connected to a high-frequency power source 1 via a high-frequency matching device 5. By applying RF high-frequency (13.56 MHz) between the lower electrode 2 and the upper electrode 6, the lower electrode 2 is turned on. 3 is configured to excite plasma and perform surface treatment such as etching or film formation. Further, a sensor 8 for measuring the plasma impedance is mounted between the high-frequency power supply 1 and the lower electrode 2, and comprises a measuring unit 9 for measuring the plasma impedance and a storage unit 10 for storing the measured data. It is configured to indirectly monitor the plasma state by measuring the impedance measured at 8 and the electrical conductivity of the plasma.

As described above, by measuring the change in impedance, it is possible to detect abnormalities in the plasma state and detect changes in the process state such as the power supplied to the lower electrode 2 and the pressure of the reactive gas supplied to the chamber 3. Was.

The pressure inside the chamber 3 is maintained at a constant value, and a reactive gas is supplied. And high frequency power supply 1
When power is supplied from the substrate 3, plasma is generated in the chamber 3, and the non-processed substrate 7 is subjected to processing such as etching or film formation. The power supply from the high-frequency power supply 1 is supplied only when the processing target substrate 7 is being processed.
Power is not supplied when the substrate 7 to be processed is replaced or pressure is adjusted.

For example, even when the processing time per substrate 7 is about 1 minute, the takt time per substrate to be processed in the apparatus usually takes about 5 minutes in most cases, and most of the time is generated by plasma. Power is not being supplied.

However, when monitoring the plasma state of the conventional plasma apparatus, impedance data measured by the sensor 8 is stored as apparatus maintenance and management data for a certain period of time as data for monitoring the plasma state. Then, it was used for setting process conditions by performing data analysis and the like.

In the conventional plasma plasma monitoring method, a plasma is generated only when the substrate 7 such as a semiconductor wafer is processed. Therefore, a signal from the control device 4 is input to the plasma monitoring system. However, among the plasma impedance data, a method of storing and managing only data when plasma is generated has been adopted.

In such plasma processing, since plasma is generated only when a substrate to be processed such as a semiconductor wafer is processed, a signal from the apparatus is used when data is stored. Instead of determining whether to save or not to save, the plasma state is constantly monitored and saved as a time function, and when analyzing data, the operating state of the control device 4 that controls the power supply is referred to as saved data. ,
The method of extracting necessary data at the time of plasma generation has been adopted.

[0012]

As described above, the conventional plasma monitoring method requires a signal input section for inputting a signal indicating the operation state of the plasma processing apparatus of the plasma monitoring apparatus, and malfunctions due to the influence of noise from the high-frequency power supply. Could be.

In the conventional plasma state monitoring of the plasma apparatus, since the plasma state is constantly monitored and stored, a storage capacity including data other than the time of plasma generation is required. There has been a problem that the capacity has to be increased and the cost of the data storage device rises.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims at reducing the storage capacity of a data storage device, reducing the cost of the data storage device, and reducing malfunction due to the influence of noise such as a high-frequency power supply. And to provide highly reliable plasma monitoring.

[0015]

In order to achieve the above object, according to the present invention, without inputting a signal from a plasma generation power control device, a determination is made based on plasma impedance data, and only data at the time of plasma generation is used. By saving the information, an apparatus having a minimum necessary apparatus configuration and free from malfunction is provided.

That is, according to the first aspect of the present invention, there is provided a plasma impedance measuring means provided between a power supply for generating plasma and an electrode and configured to measure an impedance therebetween, and stores the data of the plasma impedance. Data acquisition means for performing, data acquisition start instruction means for instructing the data storage means to start acquisition of the plasma impedance data when a preset data acquisition start criterion is satisfied, and measurement to the data storage means. Data acquisition end instruction means for instructing the end of data storage.

Preferably, the data acquisition start instructing means instructs the data storage means to start data acquisition when a time satisfying a preset data acquisition level is equal to or longer than a preset time. It is characterized by being constituted.

Preferably, the data acquisition end instructing means sends the data acquisition end to the data storage means when a time satisfying a preset data acquisition end level is equal to or longer than a preset time. Is designated.

According to the invention, the plasma state is measured as plasma impedance. Since plasma has electrical conductivity, when plasma is generated, the electrical conductivity increases.As a result, the plasma impedance measured indirectly becomes smaller than before the plasma was generated. Whether or not it can be detected can be detected by measuring a change in the monitored plasma impedance.

Therefore, the present invention focuses on this point, and when the measured plasma impedance data satisfies a preset data acquisition start criterion without using an input signal from the power control device, the data storage means In response, the acquisition start instruction of the plasma impedance data is to be issued, whereby it is possible to acquire and store the minimum necessary measurement data,
It is possible to reduce an increase in storage capacity. In addition, since the data level is actually measured and whether or not the data level is stored is determined, malfunctions due to high frequency noise and the like are reduced, and highly reliable plasma monitoring can be performed.

Further, in the method of the present invention, when performing plasma treatment by exciting plasma in a closed vacuum chamber,
In a plasma processing method for performing plasma processing, a plasma impedance measuring step is provided between a power supply and an electrode for plasma generation and measures impedance between the electrodes in a plasma monitoring method for performing plasma processing while monitoring a plasma state. And, a start determination step of determining whether the data obtained in the plasma impedance measurement step satisfies a preset data acquisition start criterion, and only when the data acquisition start criterion is satisfied, The method includes a storage step of storing data, and a termination determination step of determining whether the data satisfies a preset data acquisition termination criterion. When the data acquisition termination criterion is satisfied, the data storage is terminated. Satisfies data acquisition criteria, including termination process Characterized in that to perform the data storage only when being.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the plasma monitoring apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a plasma processing apparatus using a plasma monitoring apparatus according to one embodiment of the present invention.

In this apparatus, as shown in FIG. 1, when the measured value of the data of the plasma impedance satisfies a preset data acquisition start criterion in the conventional plasma processing apparatus shown in FIG. The storage means is instructed to start acquiring the plasma impedance data, and when the measured value satisfies a preset termination criterion, the storage of the plasma impedance data is terminated, and the data storage period is measured. It is characterized in that it is determined according to the value of data, and reduces noise, eliminates unnecessary data storage, and simplifies the device configuration.

That is, as shown in FIG. 1, the conventional plasma processing apparatus is connected to a measuring unit 9 for measuring the plasma impedance, and determines whether the level of the measured data satisfies a preset storage start level. And a data acquisition start level judging unit 11 for judging the start of storage of the measured data based on the judgment result, and judging whether or not the level of the measured data satisfies a preset storage end level. Then, an acquisition end level judging unit 12 for judging the end of the storage of the measurement data based on the judgment result is added. The other configuration of the apparatus is the same as that of the conventional plasma processing apparatus shown in FIG. 2, and the upper electrode 6 attached to the upper part of the chamber 3 which is a reaction chamber for generating plasma.
And a substrate to be processed 7 provided opposite to the upper electrode 6.
, A vacuum pump (not shown) for evacuating the chamber 3, a gas supply source (not shown) for supplying a desired gas into the chamber, the upper electrode 6 and the lower electrode A high-frequency power supply 1 for supplying a high-frequency voltage between the electrodes 2 and generating plasma is provided. The lower electrode 2 is connected to the high-frequency power supply 1 via the high-frequency matching device 5, and applies RF high-frequency (13.56 MHz) between the lower electrode 2 and the upper electrode 6, so that the lower electrode 2 enters the chamber 3. It is configured to excite plasma to perform surface treatment such as etching or film formation.

Further, a sensor 8 for measuring the plasma impedance is mounted between the high-frequency power supply 1 and the lower electrode 2, and comprises a measuring section 9 for measuring the plasma impedance and a storage section 10 for storing the measured data. Then, the plasma state is detected by measuring the impedance measured by the sensor 8 and the electrical conductivity of the plasma. The pressure inside the chamber 3 is maintained at a constant value, and a reactive gas is supplied. High frequency power supply 1
When power is supplied from the, a plasma is generated in the chamber 3 and the substrate 7 to be processed is processed.
Power is supplied from the high-frequency power supply 1 only when the substrate 7 is being processed, and is not supplied when the substrate 7 is replaced or pressure is adjusted. Next, a processing method using the plasma processing apparatus will be described.

First, the substrate 7 to be processed is placed in the chamber, the chamber is evacuated, a desired reactive gas is supplied, and a voltage is applied between the upper electrode 6 and the lower electrode 2 from a high frequency power supply. , Generating plasma.

Here, the sensor 8 is disposed between the high-frequency power supply 1 and the lower electrode 2, and measures the plasma impedance. FIG. 2 shows the relationship between the measured plasma impedance and time. When plasma is generated, the impedance decreases, and when stabilized, the impedance level becomes a plateau state Pp.

The output of the sensor 8 is judged by a data acquisition level judgment unit composed of a data acquisition start level judgment unit 11 and a data acquisition end level judgment unit 12 via a measurement unit 9, and a preset data acquisition level ( Only when the value exceeds the start reference value Zs), storage of the measured data in the data storage unit is started.

That is, the data acquisition start level determining section 1
1 constantly monitors the plasma impedance measurement value Z measured by the measuring unit 9 and compares it with a preset start reference value Zs. When Z <Zs (1) is satisfied, that is, at time Ts The storage of the measurement data in the storage unit 10 is started.

On the other hand, the data acquisition end level judging section 12 calculates the plasma impedance measured value Z measured by the measuring section 9.
Is constantly monitored and compared with a preset end reference value Ze. When Z> Ze (2) is satisfied, that is, at time Te, the storage of the measurement data in the storage unit 10 is ended.

At all times, the data is determined by the data acquisition level determiner including the data acquisition start level determiner 11 and the data acquisition end level determiner 12, and the data is stored only while satisfying the desired impedance level. Since the data is not stored, the amount of data is significantly reduced, and the data is formed by actual measurement values. Therefore, the plasma can be monitored immediately without occurrence of a malfunction. Therefore, even if an abnormality occurs during the processing, the setting conditions can be immediately and easily improved, and the plasma processing can be terminated early or the plasma processing conditions can be corrected early.

According to the present invention, since the plasma state is measured by the plasma impedance, when the plasma is generated, the electrical conductivity is increased. As a result, the indirectly measured plasma impedance is lower than before the plasma generation. Utilizing the fact that it becomes smaller, it is possible to detect whether plasma is generated or not by the change in the monitored plasma impedance, so it is determined at the level of the plasma impedance without using the input signal from the power control device. Then, since it is possible to acquire and store the minimum required measurement data, the data storage amount is reduced, the apparatus can be simplified, and malfunctions are suppressed.

In the above embodiment, the end reference value Ze
When the measured value Z satisfies Z> Ze, the storage of the measured data in the storage unit 10 is immediately terminated. However, when the measured value Z satisfies Z> Ze, a predetermined time has elapsed. At first, the storage of the measurement data in the storage unit 10 may be ended. For example, even when the impedance value suddenly rises due to the turbulence of the plasma as shown by the dotted line E in the figure, the measured plasma impedance data satisfies Ze, and the operation ends, resulting in malfunction. Would.

However, if the process is terminated only when the time Tk is satisfied, the time T when the impedance data exceeds Ze is T <Tk because the power suddenly rises and drops immediately. Yes, and is not determined to be finished.

As described above, if the process is terminated only when the impedance data satisfies the time Tk, such a malfunction can be prevented, and more reliable monitoring can be performed.

[0036]

As described above, according to the present invention, the necessity of data storage depending on whether or not plasma is generated is as follows.
Since it is detected by the data level of the monitored plasma impedance itself, it is possible to acquire and store the minimum required measurement data without using an input signal from the power control device, including the plasma monitoring device The structure of the plasma apparatus can be simplified and the cost can be reduced, and the influence of high frequency noise superimposed on the signal input unit can be eliminated by eliminating external signal input to the plasma monitoring system.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a relationship between impedance data and time in a plasma monitoring method according to one embodiment of the present invention.

FIG. 3 is a diagram showing a conventional plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High frequency power supply 2 Lower electrode 3 Chamber 4 Control device 7 Substrate to be processed 8 Sensor 9 Measurement part 10 Storage part 11 Data acquisition start level judgment part 12 Data acquisition end level judgment part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/1333 505 H01L 21/205 H01L 21/205 H05H 1/00 A H05H 1/00 1/46 M 1 / 46 H01L 21/302 E (72) Inventor Osamu Amano 1006 Odoma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 2H088 FA30 HA01 2H090 HC03 HC18 HC20 JA06 JC06 JC09 4K030 CA04 CA06 FA03 KA30 KA39 LA15 LA18 5F004 AA16 BA04 BB13 BB18 BC08 CA09 CB07 5F045 AA08 BB08 EH14 EH19 GB08 GB15

Claims (4)

[Claims] 1. A plasma impedance measuring means disposed between a power supply for plasma generation and an electrode and configured to measure impedance therebetween, and a data storage means for storing measurement data of the plasma impedance Data acquisition start instruction means for instructing the data storage means to start acquiring the plasma impedance data when a preset data acquisition start criterion is satisfied; and ending the storage of the measurement data in the data storage means. And a data acquisition end instructing means for instructing the plasma monitoring. 2. The data acquisition start instructing means instructs the data storage means to start data acquisition when a time satisfying a preset data acquisition level is equal to or longer than a preset time. 2. The plasma monitoring device according to claim 1, wherein the plasma monitoring device is configured as follows. 3. The data acquisition end instructing means instructs the data storage means to end data acquisition when a time satisfying a preset data acquisition end level is equal to or longer than a preset time. 2. The plasma monitoring device according to claim 1, wherein the plasma monitoring device is configured to perform the operation. 4. A plasma processing method for performing plasma processing by exciting plasma in a closed vacuum chamber, wherein the plasma processing method performs the plasma processing while monitoring the plasma state. A plasma impedance measuring step disposed between a power supply and an electrode for measuring the impedance therebetween, and whether data obtained in the plasma impedance measuring step satisfies a preset data acquisition start criterion. And a storage step of storing the data only when the data acquisition start criterion is satisfied; and determining whether the data satisfies a preset data acquisition end criterion. A determination step, wherein the data acquisition end group When satisfied, and a termination step of terminating the data storage, plasma monitoring method being characterized in that to perform the data storage only when you are satisfied data acquisition criteria.