TW201724164A - Plasma processing device and cleaning method thereof including a step for cleaning parts in a processing chamber and a step for cleaning a surface of a lifting push pin - Google Patents

Abstract

The present invention discloses a cleaning method of a plasma processing device, including a step for cleaning parts in a processing chamber and a step for cleaning a surface of a lifting push pin. The step for cleaning the parts in the processing chamber includes applying a radio frequency power source to a base, introducing reaction gas for cleaning into the processing chamber, and exciting the reaction gas for cleaning into cleaning plasma by the radio frequency power so as to perform plasma cleaning on each part of the processing chamber; the step for cleaning the surface of the lifting push pin includes applying AC power to a clamping electrode in a static chuck, grounding the base, introducing the reaction gas for cleaning into the processing chamber, forming partial DBD plasma in a passage of the lifting push pin by the reaction gas for cleaning, so as to perform partially-enhanced plasma cleaning on the surface of the lifting push pin. The sequence of the steps for cleaning parts in the processing chamber and cleaning the surface of the lifting push pin can be interchanged. The present invention uses a dielectric barrier discharge (DBD) method to form partial plasma around the lifting push pin, so as to effectively clean polymers attached to the lifting push pin.

Description

Plasma processing device and cleaning method thereof

The invention relates to a plasma processing device and a cleaning method thereof, in particular to a cleaning method capable of effectively cleaning a lifting thimble and a corresponding plasma processing device, and belongs to the technical field of plasma processing.

In the wafer etching process, the processing chamber often accumulates a large amount of polymers. In order to stabilize the processing of the cavity environment, it is common practice to periodically introduce oxygen to form oxygen plasma to remove the polymer for cleaning. The purpose of the cavity. However, regular oxygen plasma is difficult to clean to lift the ejector groove.

As shown in FIG. 1, the susceptor 101 is connected to the RF power source 103 by a matching circuit 102, the clamping electrode 104 is embedded in the electrostatic chuck 105, and the clamping electrode 104 is connected to the high voltage DC power source 106, and the lifting ejector 107 Vertically passes through the base 101 and the electrostatic chuck 105, and a gap (lifting ejector groove) is left between the base 101 and the electrostatic chuck 105, respectively. Since the diameter of the lifting ejector 107 is only a few mm, the oxygen plasma 108 hardly enters the lifting ejector groove, and the polymer 109 attached to the lifting ejector pin 107 is difficult to clean, causing degeneration of the surface of the lifting ejector pin 107. In the subsequent etching process, in the case of high-power radio frequency, it is easy to form a discharge in the lifting ejector groove, which causes defects such as lifting thimble damage and wafer yield drop.

An object of the present invention is to provide a plasma processing apparatus and a cleaning method thereof, which can form a localized plasma around a lifting ejector by means of a dielectric barrier discharge (DBD), and can effectively clean the polymer attached to the lifting ejector pin. Prevents discharge and damage of the lifting ejector groove due to the polymer during the etching process.

In order to achieve the above object, the present invention provides a plasma processing apparatus comprising: a processing chamber; a bottom portion of the processing chamber is provided with a base; an electrostatic chuck is disposed above the base, and the electrostatic chuck is used for carrying the wafer; Lifting the ejector pin, vertically passing through the base and the electrostatic chuck, and leaving a gap with the base and the electrostatic chuck respectively, the gap serves as a passage for the lifting thimble; the clamping electrode is embedded in the electrostatic chuck; the top of the processing chamber is provided There is an upper electrode corresponding to the clamping electrode, and the upper electrode is grounded; one of an alternating current power source or a high voltage direct current power source may be selectively applied to the clamping electrode, and when a high voltage direct current power source is applied to the clamping electrode, static electricity is generated on the clamping electrode. Suction is used to clamp the wafer on the fixed electrostatic chuck. When an AC power source is applied to the clamping electrode, the AC power source is used to generate a cleaning plasma in the channel of the lifting ejector pin.

Preferably, the output voltage of the high voltage DC power supply ranges from -9000V to 9000V.

Preferably, the output voltage of the AC power source has an amplitude of 100V to 20kV and a frequency of 1 kHz to 1 MHz.

Preferably, the clamping electrode is selectively connected to one of a high voltage direct current power source or an alternating current power source by a first relay.

Preferably, the plasma processing apparatus further includes a matching circuit coupled to the pedestal, the matching circuit includes a second relay for selectively connecting the susceptor to one of a ground or a radio frequency power source.

Preferably, when a radio frequency power source is applied to the susceptor, a high voltage direct current power source is applied to the clamping electrode, and an etching reaction gas is introduced into the processing chamber, the etching reaction gas is excited to etch the plasma to set The wafer is etched over the electrostatic chuck.

Preferably, when a radio frequency power source is applied to the susceptor, the first relay is turned off, and a cleaning reaction gas is introduced into the processing chamber, the cleaning reaction gas is excited to be a cleaning plasma to perform various components in the processing chamber. Plasma cleaning.

Preferably, when the base is grounded, an alternating current power source is applied to the upper electrode, and a cleaning reaction gas is introduced into the processing chamber, the cleaning reaction gas is excited to be a cleaning plasma, and a local dielectric barrier discharge is formed in the channel of the lifting ejector pin ( The DBD) plasma is subjected to a locally enhanced plasma cleaning of the surface of the lifting thimble.

In order to achieve the above object, the present invention further provides a cleaning method for a plasma processing apparatus. After the wafer etching is finished and removed from the processing chamber, the cleaning method includes a component cleaning step in the processing chamber and a cleaning step of lifting the surface of the lifting pin. The component cleaning step in the processing chamber applies a radio frequency power source to the susceptor to introduce a cleaning reaction gas into the processing chamber, and the RF power excites the cleaning reaction gas into a cleaning plasma to perform plasma on various components in the processing chamber. Cleaning. The cleaning step of lifting the thimble surface, applying an alternating current power to the clamping electrode in the electrostatic chuck, grounding the base, introducing a cleaning reaction gas into the processing chamber, and forming a local medium blocking in the channel of the lifting ejector by the cleaning reaction gas A discharge (DBD) plasma is used to locally enhance the plasma cleaning of the surface of the lifting thimble. The order of the component cleaning step in the processing chamber and the cleaning step of the lifting ejector surface can be reversed.

Preferably, applying an alternating current power to the clamping electrode is accomplished by a first relay coupled to the clamping electrode circuit, the first relay selectively connecting the clamping electrode to one of a high voltage direct current source or an alternating current source.

Preferably, the output voltage of the high voltage DC power supply ranges from -9000V to 9000V.

Preferably, the output voltage of the AC power source has an amplitude of 100V to 20kV and a frequency of 1 kHz to 1 MHz.

Preferably, grounding the pedestal is accomplished by a matching circuit coupled to the pedestal circuit, the matching circuit including a second relay that can selectively connect the susceptor to one of the ground or RF power sources.

A plasma processing apparatus and a cleaning method thereof according to the present invention have the advantage of forming a local DBD plasma in a channel of a lifting ejector by applying an alternating current power to a clamping electrode embedded in an electrostatic chuck in comparison with the prior art. Body, the lifting thimble achieves a locally enhanced cleaning effect; since the formed local DBD plasma generates a large number of chemically active particles or groups, it performs chemical cleaning on the surface of the lifting thimble and damages the surface of the lifting thimble. Small, does not affect other parts.

The invention will be further illustrated by the following detailed description of the preferred embodiments.

As shown in FIG. 2, a plasma processing apparatus includes: a processing chamber; a bottom 201 (a material made of aluminum) is disposed at a bottom of the processing chamber; and an electrostatic chuck 202 is disposed above the base 201, and the electrostatic chuck 202 is provided. For carrying the wafer; the lifting ejector 203 vertically passes through the base 201 and the electrostatic chuck 202, and has a gap with the base 201 and the electrostatic chuck 202 respectively, the gap serves as a passage for the lifting ejector 203; the electrostatic chuck 202 The clamping electrode 204 is embedded therein; the top of the processing chamber is provided with an upper electrode 205 corresponding to the clamping electrode 204, and the upper electrode 205 is grounded; the clamping electrode 204 can be optionally applied with an AC power source AC or a high voltage DC power source HV. In one of the cases, when the high voltage direct current power source HV is applied to the clamping electrode 204, an electrostatic attraction force is generated on the clamping electrode 204 for clamping and fixing the wafer on the electrostatic chuck 202, and an alternating current power source is applied to the clamping electrode 204. At AC, the AC power source AC is used to generate a cleaning plasma in the passage of the lifting ejector pin 203.

In this embodiment, the output voltage range of the high voltage DC power supply HV is -9000V~9000V; the output voltage of the AC power supply AC has an amplitude of 100V-20kV and a frequency of 1 kHz to 1 MHz.

In a preferred embodiment of the present invention, one of the AC power source AC or the high voltage DC power source HV can be selectively applied to the clamping electrode 204, and the first relay 208 is provided by a circuit connection. The first relay 208 can The clamping electrode 204 is selectively connected to one of the high voltage direct current power source HV or the alternating current power source AC; in a preferred embodiment of the invention, the matching circuit 209 is further connected to the base 201, and the matching circuit 209 includes the second relay. 2091, the second relay 2091 can selectively connect the susceptor 201 to one of the ground or radio frequency power sources RF.

In the etching process of the present invention, the clamping electrode 204 is selectively connected to the high voltage DC power source HV by the first relay 208. At this time, the high voltage DC power source generates an electrostatic attraction force on the surface of the electrostatic chuck through the clamping electrode 204. The wafer is attached to the upper surface of the electrostatic chuck. When the RF power source RF is applied to the susceptor 201 and the etching reaction gas is introduced into the processing chamber, the electric field excited by the RF power source between the upper electrode 205 and the susceptor excites the etching reaction gas into an etch plasma. The etched plasma etches the wafer fixed over the electrostatic chuck 202.

After the etching process is completed, the connection of the first relay 208 to the high-voltage DC power source is disconnected, the electrostatic attraction between the electrostatic chuck and the wafer is released, and the wafer is lifted to a certain height by the lifting ejector pin 203, and is disposed in the processing chamber. The robot in the outdoor section removes the wafer out of the processing chamber. Since the reaction by-products are deposited in various parts of the processing chamber during the etching process, affecting the process characteristics of the components, in order to ensure the consistency of the processing environment of the subsequent wafers, after each wafer is etched, The processing chamber needs to be cleaned. The method of cleaning the processing chamber is to introduce a cleaning reaction gas into the processing chamber, and apply a radio frequency power source RF to the susceptor 201. The RF power source excites the cleaning reaction gas into a cleaning plasma, and exposes the cleaning chamber to the cleaning plasma. The parts in the area are cleaned. The above cleaning method can achieve cleaning of most parts in the reaction chamber. However, for some parts that are difficult to clean, such as lifting thimbles, since the lifting thimble needs to be restored to the original position after the wafer is removed, the lifting thimble is located. The channel diameter is small, usually only a few millimeters, and it is difficult to clean the deposit attached to the lifting ejector by cleaning the plasma.

In order to effectively clean the lifting ejector, in the present invention, the susceptor 201 is grounded, the alternating current power source AC is applied to the clamping electrode 204, and the cleaning reaction gas is introduced into the processing chamber, and the alternating current is applied to the clamping electrode. The power source discharges in the narrow channel where the lifting ejector is located, dissociates the cleaning gas into a dielectric barrier discharge (DBD) plasma, and the DBD plasma is in the channel memory where the lifting ejector is located to face the surface of the lifting ejector pin 203. A locally enhanced plasma cleaning is performed.

In combination with the plasma processing apparatus described above, in order to thoroughly clean the components inside the plasma processing apparatus, the present invention discloses a cleaning method of the plasma processing apparatus, including the steps of cleaning the surface of the lifting thimble and the steps of cleaning the components in the entire processing chamber. .

Cleaning the surface of the lifting ejector comprises the steps of: applying an alternating current power to the clamping electrode in the electrostatic chuck, grounding the base, introducing a cleaning reaction gas into the processing chamber, and the cleaning reaction gas is excited to clean the plasma, A local DBD plasma is formed in the passage of the lifting thimble to locally enhance the plasma cleaning of the surface of the lifting thimble.

The step of cleaning the components in the entire processing chamber includes: applying a radio frequency power source to the susceptor, introducing a cleaning reaction gas, and exciting the cleaning reaction gas into a cleaning plasma to perform plasma cleaning on various components in the processing chamber. At this time, the first relay connected to the clamping electrode is in an off state.

The plasma processing apparatus disclosed in the present invention can perform an etching process and a cleaning process, and the steps of cleaning the lifting thimble step and cleaning the components in the processing chamber can be interchanged, and both cleaning steps are completed at the end of the etching process. It is carried out after removing the processing chamber.

Since the clamping electrode 204 is contained in the electrostatic chuck 202, the electrostatic chuck 202 forms a dielectric barrier layer; if a cleaning reaction gas (oxygen) is introduced into the processing chamber, the clamping electrode 204 and the susceptor 201 are A typical DBD discharge is formed, and the oxygen atom or ozone atom generated by the oxygen discharge has strong oxidizing property, and the polymer 207 adsorbed on the lifting ejector pin 203 can be effectively cleaned. Due to the locality of the DBD discharge, the DBD plasma 206 is only Will form in the groove without affecting other parts.

The working process of the plasma processing apparatus of the present invention is as follows: an etching step; applying a high voltage direct current power source to the clamping electrode, applying a radio frequency power source to the susceptor, and introducing an etching reaction gas into the processing chamber, the etching reaction gas Excited as an etch plasma, the wafer disposed above the electrostatic chuck can be etched; after the etching process is completed, the high-voltage DC power supply connected to the clamping electrode is disconnected, and the wafer is removed after clamping. After the etching is completed, the wafer is taken out, and then the cleaning reaction gas is introduced into the processing chamber; the components in the entire processing chamber are cleaned: the RF power supply is continuously applied to the susceptor, and the cleaning reaction gas is excited to clean the plasma. Plasma cleaning is performed on each component in the processing chamber, and the first relay connected to the clamping electrode is in an off state; and the frequency of the alternating current power source selected by the invention is less than 1 MHz, and a plasma generated by discontinuous discharge is generated. Body, and the plasma density is low, the sheath effect is weak, so that the interaction between the clean plasma and the lifting thimble surface is active particles. The chemical reaction is mainly based on the physical damage to the surface of the lifting thimble.

The step of separately cleaning the surface of the lifting thimble: grounding the base, applying an alternating current power to the clamping electrode, the cleaning reaction gas is excited to clean the plasma, and forming a local DBD plasma in the channel of the lifting ejector to face the surface of the lifting ejector Performing locally enhanced plasma cleaning; wherein the step of cleaning the components in the entire processing chamber is interchangeable with the step of separately cleaning the surface of the lifting thimble; that is, the surface of the lifting ejector can be cleaned before cleaning the components in the processing chamber; or The components in the processing chamber are first cleaned and then the surface of the lifting thimble is cleaned.

Although the present invention has been described in detail by the preferred embodiments thereof, it should be understood that the foregoing description should not be construed as limiting. Various modifications and alterations of the present invention will be apparent to those skilled in the <RTIgt; Therefore, the scope of the invention should be limited by the scope of the appended claims.

101, 201‧‧‧ Pedestal
102, 209‧‧‧ matching circuit
103‧‧‧RF power supply
104, 204‧‧‧Clamping electrode
105, 202‧‧‧ Electrostatic chuck
106‧‧‧High voltage DC power supply
107, 203‧‧‧ lifting thimble
108, 206‧‧‧ Plasma
109, 207‧‧‧ polymer
205‧‧‧Upper electrode
208‧‧‧First relay
2091‧‧‧Second relay

Fig. 1 is a schematic view of a plasma processing apparatus in the prior art. Fig. 2 is a schematic view showing a plasma processing apparatus in the present invention.

201‧‧‧Base

202‧‧‧Electrical chuck

203‧‧‧ lifting thimble

204‧‧‧Clamping electrode

205‧‧‧Upper electrode

206‧‧‧ Plasma

207‧‧‧ polymer

208‧‧‧First relay

209‧‧‧Matching circuit

2091‧‧‧Second relay

Claims (13)

A plasma processing apparatus comprising: a processing chamber; a bottom portion of the processing chamber is provided with a base; an electrostatic chuck is disposed above the base, the electrostatic chuck is used for carrying a wafer; Passing through the base and the electrostatic chuck, and leaving a gap with the base and the electrostatic chuck, the gap serves as a passage for the lifting ejector; the clamping electrode is embedded in the electrostatic chuck; the processing chamber The top of the top is provided with an upper electrode corresponding to the clamping electrode, and the upper electrode is grounded; the clamping electrode is selected to be applied with one of an alternating current power source or a high voltage direct current power source, and the high voltage direct current power source is applied to the clamping electrode An electrostatic attraction force is generated on the clamping electrode for clamping and fixing the wafer on the electrostatic chuck. When the alternating current power source is applied to the clamping electrode, the alternating current power source is used for the lifting ejector pin. A cleaning plasma is generated in the channel. The plasma processing apparatus of claim 1, wherein the high voltage direct current power source has an output voltage ranging from -9000V to 9000V. The plasma processing apparatus according to claim 1, wherein the output voltage of the alternating current power source has an amplitude of 100V to 20kV and a frequency of 1 kHz to 1 MHz. The plasma processing apparatus of claim 1, wherein the clamping electrode is selectively connected to the high voltage direct current power source or the alternating current power source by a first relay. The plasma processing apparatus of claim 4, further comprising a matching circuit connected to the base, the matching circuit comprising a second relay for selectively connecting the base to One of the ground or RF power supplies. The plasma processing apparatus of claim 5, wherein a radio frequency power source is applied to the susceptor, the high voltage direct current power source is applied to the clamping electrode, and an etching reaction gas is introduced into the processing chamber. The etching reaction gas is excited as an etch plasma to etch the wafer disposed above the electrostatic chuck. The plasma processing apparatus according to claim 5, wherein a radio frequency power source is applied to the susceptor, the first relay is turned off, and a cleaning reaction gas is introduced into the processing chamber, and the cleaning reaction gas is The excitation is to clean the plasma to plasma clean the various components within the processing chamber. The plasma processing apparatus according to claim 5, wherein the base is grounded, the alternating current power is applied to the upper electrode, and the cleaning reaction gas is introduced into the processing chamber, the cleaning reaction gas is excited to The plasma is cleaned and a local dielectric barrier discharge (DBD) plasma is formed in the channel of the lift pin to locally enhance plasma cleaning of the surface of the lift pin. A cleaning method for a plasma processing apparatus, after the wafer etching is finished and removed from the processing chamber, the cleaning method includes a component cleaning step in the processing chamber and a cleaning step of lifting the thimble surface; and cleaning the components in the processing chamber a step of applying a radio frequency power source to the susceptor, introducing a cleaning reaction gas into the processing chamber, and exciting the cleaning reaction gas into a cleaning plasma to perform plasma cleaning on the components in the processing chamber; a cleaning step of the surface of the thimble, applying an alternating current power to the clamping electrode in the electrostatic chuck, grounding the base, introducing a cleaning reaction gas into the processing chamber, and forming a partial medium in the channel of the lifting ejector by the cleaning reaction gas A barrier discharge (DBD) plasma is used to locally enhance plasma cleaning of the surface of the lifting ram; the component cleaning step in the processing chamber and the cleaning step of the lifting thimble surface are sequentially replaceable. The cleaning method of the plasma processing apparatus according to claim 9, wherein the applying the alternating current power to the clamping electrode is realized by a first relay connected to the clamping electrode circuit, the first relay The clamping electrode is selectively connected to one of a high voltage direct current power source or the alternating current power source. The cleaning method of the plasma processing apparatus according to claim 10, wherein the output voltage of the high voltage direct current power source ranges from -9000V to 9000V. The cleaning method of the plasma processing apparatus according to claim 9 or 10, wherein the output voltage of the alternating current power source has an amplitude of 100 V to 20 kV and a frequency of 1 kHz to 1 MHz. The method of cleaning a plasma processing apparatus according to claim 10, wherein the grounding of the base is performed by a matching circuit connected to the base circuit, the matching circuit comprising a second relay, A second relay can selectively connect the base to one of the ground or the RF power source.