JP2674965B2 - Plasma etching equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma etching apparatus, and more particularly to a plasma etching apparatus used in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram of an example of a conventional plasma etching apparatus. As shown in FIG.
In this conventional example, a chamber 6 including an upper electrode 2 and a lower electrode 3 is provided corresponding to a wafer 1 to be etched.
A high-frequency power source 7, an ESC power source 8, an OFF switch 9 having a function of shutting off the high-frequency power source 7, a system controller 10, a He gas introducing line 11, and a pump 12 for drawing the He gas introducing line 11 into a vacuum. , A pressure controller 13 that controls the pressure of He gas via a pump 12, a pressure gauge 14 that monitors the He gas pressure, and a leak amount of the He gas pressure between the wafer 1 and the lower electrode 3 by the pressure gauge 14. And a pressure determiner 15 that monitors and determines whether the pressure is abnormal.

In FIG. 2, when an etching process is performed on the wafer 1, a high frequency power supply 7 is provided between an upper electrode 2 and a lower electrode 3 provided inside a chamber 6.
Due to this, a predetermined high frequency power is applied. By applying this high-frequency power, plasma 4 is generated inside the chamber 6, and the plasma 4 etches the object to be etched on the surface of the wafer 1 placed on the lower electrode 3. In this case, depending on the type of the object to be etched, it is necessary to apply high-frequency high-frequency power, whereby the wafer 1 is heated to a high temperature, and the resist used as a mask on the object to be etched is There is a problem of being altered by. In order to prevent the deterioration of the resist, for the purpose of cooling the wafer 1,
A means for improving the heat conduction between the wafer 1 and the lower electrode 3 is used.

As one of means for improving the heat conduction between the wafer 1 and the lower electrode 3, there is a method using electrostatic attraction. In the case of this method, in order to transfer the heat of the lower electrode 3 to the wafer 1, DC power is applied to the lower electrode 3 from the ESC power supply 8 to electrostatically adsorb the wafer 1 to the lower electrode 3. In addition, the lower electrode 3 for the wafer 1
He gas is introduced from the He gas introduction line 11 between the wafer 1 and the lower electrode 3 in order to improve the heat conduction of the gas. The introduced He gas is exhausted by the pump 12, and the pressure between the wafer 1 and the lower electrode 3 is constantly monitored by the pressure gauge 14. In the pressure determiner 15, the pressure of the He gas monitored by the pressure gauge 14 is controlled and adjusted by the pressure controller 13 so as to reach a preset predetermined pressure value.
Further, the pressure of the He gas is further controlled by the pressure controller 1
Exceeding the range of pressure control by 3, pressure gauge 1
If the pressure value monitored in step 4 deviates from the set pressure value, the pressure determiner 15 turns on the OFF switch 9 for the system controller 10.
The OFF signal for controlling the OFF is transmitted, the OFF switch 9 is turned off through the control action of the system controller 10, and the application of the high frequency power supplied from the high frequency power supply 7 to the lower electrode 3 is stopped. It

[0005]

In the above-described conventional plasma etching apparatus, even if the He gas is leaked between the wafer and the lower electrode during the etching process and the cooling effect on the wafer is lowered,
If the gas pressure is within the range that can be pressure controlled by the pressure controller, the etching process will continue to be performed longer than necessary, and at the completion of the etching process for all wafers, an abnormality due to that will occur. As a result, the situation is discovered, and there is a drawback that damage due to defective etching processing of the wafer is further expanded.

[0006]

A plasma etching apparatus according to the present invention is provided with an upper electrode and a lower electrode in a vacuum chamber, and a wafer to be etched is placed on the lower electrode by electrostatic attraction. He gas is introduced between the wafer and the lower electrode, and a predetermined high frequency power is applied between the counter electrodes composed of the upper electrode and the lower electrode to generate plasma, and the plasma is generated on the lower electrode. In a plasma etching apparatus that etches an etchant in the chamber, the pressure of He gas introduced between the wafer and the lower electrode is monitored so that the pressure of He gas reaches a predetermined reference set value. In the crossing state, by interrupting the high frequency power applied between the counter electrodes composed of the upper electrode and the lower electrode, A first etching stopping means for stopping the etching process, and detects the leakage of the He gas, and detects the leakage of the He gas from the upper electrode and the lower electrode when the leakage amount of the He gas exceeds a predetermined reference set value. It is characterized by further comprising a second etching stopping means for stopping the etching process on the wafer by cutting off the high frequency power applied between the opposing electrodes.

The second etching stopping means is
A He optical sensor that is installed in the chamber and monitors the emission intensity of the He wavelength of plasma light generated during the etching process on the wafer to detect the leakage amount of the He gas from the chamber; External storage means for storing a reference set value regulated for the amount of leakage,
Upon receiving a detection signal of the leak amount of the He gas output from the He optical sensor, the leak amount of the He gas is compared and compared with a reference set value stored in the external storage device. In a state where the leak amount exceeds the reference set value, a He leak detecting unit that generates and outputs a predetermined control signal, and a control signal output from the He leak detecting unit are received, and the chamber is supplied from the high frequency power source. And a system control unit that functions to cut off the supply circuit of the high frequency power to.

[0008]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. As shown in FIG. 1, according to the present embodiment, a chamber 6 including an upper electrode 2 and a lower electrode 3 corresponding to a wafer 1 to be etched, and a He gas leaked when installed in the chamber 6. A He optical sensor 5 for detecting the high frequency, a high frequency power source 7, an ESC power source 8, an OFF switch 9 having a function of cutting off the supply of the high frequency power source 7 and the ESC power source 8 to the chamber 6, and a system controller 10.
And He gas introduction line 11 and He gas introduction line 1
Between the wafer 1 and the lower electrode 3, a pump 12 for drawing 1 into a vacuum, a pressure controller 13 for controlling the He gas pressure via the pump 12, a pressure gauge 14 for monitoring the He gas pressure, and a He gas pressure between the wafer 1 and the lower electrode 3. Pressure gauge 15 for monitoring the leakage amount of the pressure gauge 14 to make an abnormality determination of the pressure.
And a He leak detection device 16 for detecting a leak of He gas
And an external storage device 17.

In FIG. 1, a wafer 1 to be etched is placed on a lower electrode 3 inside a chamber 6 in order to efficiently transfer heat of the lower electrode 3 to the wafer 1. By applying DC power from the ESC power source 8 to the lower electrode 3, the wafer 1 is electrostatically attracted to the lower electrode 3. In addition, in order to further improve the heat conduction of the lower electrode 3 to the wafer 1, as in the case of the conventional example, H is provided between the wafer 1 and the lower electrode 3.
He gas is introduced from the e-gas introduction line 11. When the wafer 1 is subjected to the etching process in this way, as in the case of the conventional example described above, between the upper electrode 2 and the lower electrode 3 provided inside the chamber 6,
A predetermined high frequency power is applied by the high frequency power supply 7. By applying this high-frequency power, plasma 4 is generated inside the chamber 6, and the plasma 4 causes the lower electrode 3 to be generated.
The object to be etched on the surface of the wafer 1 placed on the upper part of the wafer is etched. In this case, the alteration of the resist due to the application of high-frequency high-frequency power causes the wafer 1 to be electrostatically adsorbed to the lower electrode 3 as described above, and
By introducing the He gas between the wafer 1 and the lower electrode 3, the heat conduction is improved and avoided.

In FIG. 1, as described above, the wafer 1
In order to improve heat conduction of the lower electrode 3 to the lower electrode 3, a He gas introduction line 1 is provided between the wafer 1 and the lower electrode 3.
He gas is introduced from No. 1, and the introduced He gas is exhausted by the pump 12 and the pressure between the wafer 1 and the lower electrode 3 is constantly monitored by the pressure gauge 14. In the pressure determiner 15, the pressure of the He gas monitored by the pressure gauge 14 is controlled and adjusted by the pressure controller 13 so as to reach a preset predetermined pressure value. And, further, the pressure of He gas is
When the pressure value monitored by the pressure gauge 14 exceeds the set pressure value by exceeding the value in the range in which the pressure control by the pressure controller 13 is possible, the pressure determiner 15 causes the system controller 10 to notify the system controller 10. On the other hand, OF
An OFF signal for controlling ON / OFF of the F switch 9 is transmitted, the OFF switch 9 is turned off through the control action of the system controller 10, and the high frequency power supplied to the lower electrode 3 from the high frequency power supply 7 is supplied. The application of electric power is stopped.

In the present embodiment, in the course of the above etching process, the He leak detection device 16 receives the output of the He optical sensor 5 installed in the chamber 6 to constantly detect the He gas leakage. The leak amount is monitored, and the leak amount of the He gas detected by the He leak detection device 16 is compared and collated with the set value of the allowable leak amount set in the external storage device 17 in advance. If the leak amount exceeds the set value,
From the He leak detection device 16 to the system controller 10
A control signal for controlling ON / OFF of the OFF switch 9 is sent to the OFF switch 9 and the OFF switch 9 is controlled by the system controller 10 in response to the control signal.
Is turned off, application of the high frequency power supplied from the high frequency power supply 7 to the lower electrode 3 is stopped, and the etching process is stopped. Therefore, as seen in the conventional plasma etching apparatus, an excessive etching process on the wafer 1 that occurs when the pressure can be controlled by the pressure controller 13 is effectively avoided, and etching defects can be prevented in advance. You can

[0013]

As described above, according to the present invention, the He light sensor for monitoring the emission intensity of the He wavelength corresponding to the plasma light during the etching process is installed in the chamber, and the He gas by the He light sensor is installed. When the leakage amount of the wafer exceeds a predetermined set value, by stopping the supply of the high frequency power to the chamber, it is possible to effectively avoid the excessive etching process on the wafer and prevent the etching failure from occurring. The effect is that you can do it.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a configuration diagram showing a conventional example.

[Explanation of symbols]

 1 Wafer 2 Upper Electrode 3 Lower Electrode 4 Plasma 5 He Optical Sensor 6 Chamber 7 High Frequency Power Supply 8 ESC Power Supply 9 OFF Switch 10 System Controller 11 He Gas Introducing Line 12 Pump 13 Pressure Controller 14 Pressure Gauge 15 Pressure Judge 16 He Leak Detection Device 17 External storage device

Claims (2)

(57) [Claims] 1. An upper electrode and a lower electrode are provided in a vacuum chamber, a wafer to be etched is placed on the lower electrode by electrostatic adsorption, and He gas is introduced between the wafer and the lower electrode. Then, a plasma is generated by applying a predetermined high-frequency power between the opposing electrodes composed of the upper electrode and the lower electrode, and the object to be etched on the wafer surface on the lower electrode is etched in the chamber. In the etching apparatus, the pressure of the He gas introduced between the wafer and the lower electrode is monitored, and when the pressure of the He gas exceeds a predetermined reference set value, the He gas is removed from the upper electrode and the lower electrode. First etching stopping means for stopping the etching process on the wafer by cutting off the high frequency power applied between the opposing electrodes And having,
By detecting the leakage of the He gas and shutting off the high frequency power applied between the counter electrodes composed of the upper electrode and the lower electrode when the leakage amount of the He gas exceeds a predetermined reference set value. A plasma etching apparatus further comprising a second etching stopping means for stopping the etching process on the wafer. 2. The second etching stop means is installed in the chamber, and monitors the emission intensity of the He wavelength of the plasma light generated during the etching process on the wafer to monitor the He gas from the chamber. A He light sensor for detecting a leak amount, an external storage means for storing a reference set value regulated in advance for the He gas leak amount, and a detection of the He gas leak amount output from the He light sensor. Upon receiving the signal, the leak amount of the He gas is compared with the reference set value stored in the external storage device, and predetermined control is performed in a state where the leak amount of the He gas exceeds the reference set value. A He leak detection unit that generates and outputs a signal and a control signal output from the He leak detection unit are received, and high frequency power is supplied from the high frequency power source to the chamber. 2. The plasma etching apparatus according to claim 1, wherein the plasma etching apparatus comprises at least system control means that functions to shut off the supply circuit.