PLASMA PROCESSING APPARATUS

A plasma processing apparatus includes a plasma processing chamber; a substrate support; a lower electrode; an RF power supply; and an upper electrode assembly. The upper electrode assembly includes a gas diffusion plate; an insulating plate; and an upper electrode plate arranged between the gas diffusion plate and the insulating plate, and having a plurality of first through holes and a plurality of second through holes. The insulating plate includes an inner annular protrusion and an outer annular protrusion protruding downward from a lower surface of the insulating plate, and the insulating plate has a plurality of first gas introduction holes, a plurality of second gas introduction holes, and a plurality of third gas introduction holes.

TECHNICAL FIELD

The present disclosure relates to a plasma processing apparatus.

BACKGROUND

In Patent Document 1, there known a configuration of a capacitively coupled plasma processing apparatus including an electromagnet assembly disposed in the upper portion or on the upper side of a chamber. The capacitively coupled plasma processing apparatus of Patent Document 1 includes an upper electrode that also functions as a shower head. The configuration of the apparatus of Patent Document 1 prevents the processing speed of plasma processing performed in the plasma processing apparatus from increasing locally in a central portion of a substrate.

PRIOR ART DOCUMENT

Patent Document

SUMMARY

According to one embodiment of the present disclosure, a plasma processing apparatus including: a plasma processing chamber; a substrate support disposed inside the plasma processing chamber; a lower electrode disposed within the substrate support; at least one RF power supply coupled to the lower electrode; and an upper electrode assembly disposed above the substrate support, wherein the upper electrode assembly includes a gas diffusion plate having at least one first gas supply port for a first gas and at least one second gas supply port for a second gas; an insulating plate; and an upper electrode plate arranged between the gas diffusion plate and the insulating plate, and having a plurality of first through holes in communication with the at least one first gas supply port and a plurality of second through holes in communication with the at least one second gas supply port, wherein the insulating plate includes an inner annular protrusion and an outer annular protrusion protruding downward from a lower surface of the insulating plate, and wherein the insulating plate has a plurality of first gas introduction holes formed in the inner annular protrusion, each of the first gas introduction holes being in communication with the at least one first gas supply port through any of the plurality of first through holes, a plurality of second gas introduction holes formed in the outer annular protrusion, each of the second gas introduction holes being in communication with the at least one first gas supply port though any of the plurality of first through holes, and a plurality of third gas introduction holes formed outside the second gas introduction holes, each of the third gas introduction holes being in communication with the at least one second gas supply port through any of the plurality of second through holes.

DETAILED DESCRIPTION

In a semiconductor device manufacturing process, various plasma processes such as an etching process, a film-forming process, a diffusion process, and the like are performed on a semiconductor substrate (hereinafter simply referred to as “substrate”) supported by a substrate support by exciting a processing gas supplied into a chamber and generating plasma. These plasma processes are performed using, for example, a capacitively coupled plasma (CCP) processing apparatus including an upper electrode assembly as a gas diffuser that constitutes at least a portion of a chamber top portion (top plate).

For example, when performing an etching process using a mask in a plasma processing apparatus, it is known that the remaining film state of the mask or the like differs between the peripheral portion and the central portion of a substrate even during the same processing process. In order to prevent such unevenness in the remaining film state of the mask or the like on the substrate, for example, by-products (deposits) generated during the etching process and adhering to the upper electrode are required to be reduced by making uniform a processing gas or the like introduced from the upper electrode assembly as a gas diffuser or introducing an additive gas. By making the process uniform, it is expected that the remaining film state of the mask or the like can be made uniform and the etching process can be performed effectively.

Further, when an etching process is performed as a plasma process, the plasma density may differ between the peripheral portion and the central portion of the substrate, and the process may become non-uniform. Due to this, the size of etching holes may also become non-uniform, and for example, the size of etching holes at the peripheral portion of the substrate may be smaller than that at the central portion. In the plasma processing apparatus, it is known that additional gases are introduced in addition to the processing gas (etching gas) for various purposes such as protection of the inner wall or the like. It is presumed that the plasma density becomes non-uniform due to the influence of flow of these gases, and there is room for improvement in the arrangement and configuration of the gas introduction holes in the gas diffuser.

However, the plasma processing apparatus mentioned in Patent Document 1 has been developed with a focus on the plasma processing speed on the substrate, particularly in order to solve the problem that the processing speed becomes locally high at the center of the substrate. The related art mentioned in Patent Document 1 is mainly directed to a technique related to the lower electrode of a plasma processing apparatus and its vicinity, and is not directed to a technical idea regarding the process uniformity that focuses on the gas diffuser of the plasma processing apparatus. That is, when aiming to improve the uniformity of a plasma process on a substrate in a plasma processing apparatus, there is room for further improvement, particularly in the technique related to the gas diffuser and its vicinity.

Hereinafter, a plasma processing system according to one embodiment and a plasma processing method including an etching method according to the present embodiment will be described with reference to the drawings. In the specification and the drawings, elements having substantially the same functional configuration are designated by like reference numerals and redundant descriptions thereof will be omitted.

Plasma Processing System

First, a plasma processing system according to the present embodiment will be described.FIG.1is a vertical cross-sectional view schematically showing a configuration of the plasma processing system according to the present embodiment.

The plasma processing system includes a capacitively coupled plasma processing apparatus1and a controller2. The plasma processing apparatus1includes a plasma processing chamber10, a gas supply20, a power supply30, and an exhaust system40. Further, the plasma processing apparatus1includes a substrate support11and a gas introduction unit.

The substrate support11is arranged within the plasma processing chamber10. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber10. The gas introduction unit includes an upper electrode assembly13. The upper electrode assembly13is disposed above the substrate support11, and an insulating plate140whose lower surface is exposed to a plasma is disposed. In one embodiment, the upper electrode assembly13is disposed in an upper portion of the plasma processing chamber10, and is attached to, for example, a top plate10b(ceiling). An electromagnet unit15having coils15atherein is disposed on or above the plasma processing chamber10.

Inside the plasma processing chamber10, a plasma processing space10sdefined by the upper electrode assembly13, the top plate10b,the side wall10aof the plasma processing chamber10, and the substrate support11is formed. The plasma processing chamber10has at least one gas supply port for supplying at least one processing gas to the plasma processing space10s,and at least one gas discharge port for discharging gases from the plasma processing space10s.The side wall10ais grounded. The upper electrode assembly13and the substrate support11are electrically isolated from the plasma processing chamber10.

The substrate support11includes a main body111and a ring assembly112. The upper surface of the main body111has a central region111a(substrate support surface) for supporting a substrate (wafer) W, and an annular region111b(ring support surface) for supporting the ring assembly112. The annular region111bsurrounds the central region111ain a plan view. The ring assembly112includes one or more annular members. At least one of the one or more annular members is an edge ring.

In one embodiment, the main body111includes a base113and an electrostatic chuck114. The base113includes a conductive member. The conductive member of the base113functions as a lower electrode. The electrostatic chuck114is placed on the upper surface of the base113. The upper surface of the electrostatic chuck114has the aforementioned central region111aand annular region111b.

Although not shown, the substrate support11may include a temperature control module configured to adjust the temperature of at least one of the ring assembly112, the electrostatic chuck114, or the substrate W to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. Further, the substrate support11may include a heat transfer gas supply configured to supply a heat transfer gas (backside gas) to between the back surface of the substrate W and the upper surface of the electrostatic chuck114.

The gas supply20may include at least one gas source21and at least one flow controller22. In one embodiment, the at least one gas source21includes a main gas source21aand an additive gas source21b.In one embodiment, the gas supply20is configured to supply at least one processing gas from each corresponding gas source21to the upper electrode assembly13via each corresponding flow controller22. The at least one processing gas includes a main gas and an additive gas. The main gas is an example of a first gas, and the additive gas is an example of a second gas. In one embodiment, the gas supply20includes a main gas supply20afor the main gas and an additive gas supply20bfor the additive gas. The main gas supply20ais configured to supply the main gas from the main gas source21ato a first gas supply port13cof the upper electrode assembly13via the flow controller22a.The additive gas supply20bis configured to supply the additive gas from the additive gas source21bto a second gas supply port14cof the upper electrode assembly13via the flow controller22b.Each flow controller22may include, for example, a mass flow controller or a pressure-controlled flow controller. In addition, the gas supply20may include one or more flow modulation devices that modulate or pulse the flow of at least one processing gas.

The power supply30includes an RF power supply31coupled to the plasma processing chamber10via at least one impedance matching circuit. The RF power supply31is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to the conductive member (lower electrode) of the substrate support11and/or the conductive member (upper electrode) of the upper electrode assembly13. Thus, plasma is formed from at least one processing gas supplied to the plasma processing space10s.Accordingly, the RF power supply31may function as at least a part of a plasma generator configured to generate a plasma from one or more processing gases in the plasma processing chamber10. Further, by supplying the bias RF signal to the lower electrode, a bias potential can be generated on the substrate W, and ion components in the formed plasma can be drawn into the substrate W.

In one embodiment, the RF power supply31includes a first RF generator31aand a second RF generator31b.The first RF generator31ais coupled to the lower electrode and/or the upper electrode via at least one impedance matching circuit, and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency within a range of 13 MHz to 160 MHz. In one embodiment, the first RF generator31amay be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are provided to the lower electrode and/or the upper electrode. The second RF generator31bis coupled to the lower electrode via at least one impedance matching circuit, and is configured to generate a bias RF signal (bias RF power). In one embodiment, the bias RF signal has a lower frequency than the source RF signal. In one embodiment, the bias RF signal has a frequency within a range of 400 kHz to 13.56 MHz. In one embodiment, the second RF generator31bmay be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to the lower electrode. In various embodiments, at least one of the source RF signal or the bias RF signal may be pulsed.

The power supply30may further include a DC power supply32coupled to the plasma processing chamber10. The DC power supply32includes a first DC generator32aand a second DC generator32b.In one embodiment, the first DC generator32ais connected to the lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to the lower electrode. In one embodiment, the first DC signal may be applied to other electrodes such as an attraction electrode within the electrostatic chuck114, and the like. In one embodiment, the second DC generator32bis connected to the upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the upper electrode. In various embodiments, at least one of the first or second DC signals may be pulsed. The first and second DC generators32aand32bmay be provided in addition to the RF power supply31, or the first DC generator32amay be provided in place of the second RF generator31b.

The exhaust system40may be connected to the gas discharge port10eprovided at the bottom of the plasma processing chamber10, for example. The exhaust system40may include a pressure regulation valve and a vacuum pump. The pressure regulation valve regulates the pressure inside the plasma processing space10s.The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

The controller2processes computer-executable instructions that cause the plasma processing apparatus1to perform various processes described in the present disclosure. The controller2may be configured to control each element of the plasma processing apparatus1to perform the various processes described herein. In one embodiment, a part or the entirety of the controller2may be included in the plasma processing apparatus1. The controller2may include, for example, a computer2a.The computer2amay include, for example, a processing part (CPU: Central Processing Unit)2a1, a memory part2a2, and a communication interface2a3. The processing part2a1may be configured to perform various control operations based on programs stored in the memory part2a2. The memory part2a2may include a RAM (Random Access Memory), a ROM (Read Only Memory), an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface2a3may communicate with the plasma processing apparatus1via a communication line such as a LAN (Local Area Network) or the like.

Upper Electrode Assembly

Next, the upper electrode assembly13as the gas diffuser described above and the constituent elements of the plasma processing apparatus1attached to the upper electrode assembly13will be described with reference toFIGS.1and2.FIG.2is an enlarged explanatory diagram showing a portion of the upper electrode assembly13.FIG.2shows, in an enlarged manner, a portion of the upper electrode assembly13(one side of the line-symmetrical shape) having a line-symmetrical shape with respect to the center in the width direction (center line O in the figure) of the top plate10bshown inFIG.1.

As shown inFIG.2, the upper electrode assembly13constitutes a part or the entirety of the top plate10bof the plasma processing chamber10, and functions as a gas diffuser that diffuses and introduces at least one processing gas into the plasma processing space10s.The upper electrode assembly13includes a gas diffusion plate120, an upper electrode plate130, and an insulating plate140. The upper electrode plate130is disposed between the gas diffusion plate120and the insulating plate140. The gas diffusion plate120, the upper electrode plate130, and the insulating plate140are vertically stacked. The gas diffusion plate120has at least one first gas supply port13cfor the first gas and at least one second gas supply port14cfor the second gas. In addition, at least one gas diffusion space13b,which is a space for the main gas diffusion, may be formed in the gas diffusion plate120. Further, at least one gas diffusion space14b,which is a space for diffusing the additive gas, may be formed in the gas diffusion plate120. That is, the upper electrode assembly13includes the gas diffusion plate120, the upper electrode plate130, and the insulating plate140arranged in the named order from the top.

The gas diffusion plate120is formed of a first conductive material. In one embodiment, the first conductive material is Al (aluminum). The upper electrode plate130is formed of a second conductive material. The second conductive material is different from the first conductive material. In one embodiment, the second conductive material is Si (silicon). The insulating plate140is made of an insulating material. In one embodiment, the insulating material is quartz. The insulating plate140has a lower surface (plasma exposure surface) exposed to the plasma processing space10s.A plurality of first gas introduction paths13aare formed through the upper electrode plate130and the insulating plate140in the thickness direction (vertical direction) thereof. The first gas introduction paths13aare connected to the gas supply20via the gas diffusion space13band the gas supply port13c.Gas outlets13dare formed in the gas diffusion plate120. The main gas diffused in the gas diffusion space13bis introduced into the plasma processing space10sthrough the gas outlets13d,the first through holes13eformed inside the upper electrode plate130, and the gas introduction holes13fformed in the insulating plate140. That is, the first gas introduction path13ahas a gas outlet13d,a first through hole13e,and a gas introduction hole13f,and is configured to introduce the main gas from the main gas supply20ainto the plasma processing space10s.In one embodiment, the upper electrode plate130is disposed between the gas diffusion plate120and the insulating plate140. Further, the upper electrode plate130has a plurality of first through holes13eand a plurality of second through holes14e.The plurality of first through holes13eare in communication with at least one first gas supply port13cvia the gas diffusion space13bof the gas diffusion plate120and the gas outlet13d.The plurality of second through holes14eare in communication with at least one second gas supply port14cvia a gas diffusion space14band a gas outlet14dof the gas diffusion plate120.

The number and arrangement of the gas introduction paths are arbitrary, and other gas introduction paths may be provided in addition to the first gas introduction path13a.For example, as shown inFIG.2, a second gas introduction path14aincluding a gas outlet14d,a second through hole14e,and a gas introduction hole14fmay be provided. An additive gas different from the main gas may be introduced into the plasma processing space10sfrom the gas diffusion space14band the gas supply port14c.A mixed gas containing a plurality of types of gases may be introduced from the second gas introduction path14a.Although not shown inFIGS.1and2, a third gas introduction path and a fourth gas introduction path may be provided. Details of the number and arrangement of gas introduction paths (gas introduction holes) opened on the lower surface of the insulating plate140according to the present embodiment will be described later with reference to the drawings.

An electromagnet unit15having a coil15atherein is arranged at the upper portion or on the upper side of the plasma processing chamber10. In one embodiment, the electromagnet unit15is approximately circular in a plan view. The electromagnet unit15is configured to generate a magnetic field within the plasma processing chamber10by allowing a current to flow from an external current source (not shown) through the coil15a.The power supply30shown inFIG.1may be used as a power supply for the electromagnet unit15. Various configurations may be applied to the electromagnet unit15. For example, the configuration described in Patent Document1may be applied to the electromagnet unit15.

The gas diffusion plate120may be provided with a coolant flow path (not shown) through which a heat transfer fluid such as brine or gas circulates to and from a chiller outside the apparatus. The coolant flow path adjusts the temperature of the insulating plate140whose temperature fluctuates due to plasma heat input, for example. For example, the coolant flow path may be provided inside the upper electrode plate130, or a metal plate having the coolant flow path may be provided at an upper portion of the gas diffusion plate120.

The insulating plate140is disposed to cover the lower surface of the upper electrode plate130. At least two annular protrusions protruding downward are formed on the lower surface of the insulating plate140. In one embodiment, as shown inFIG.2, an inner annular protrusion142and an outer annular protrusion144are formed on the lower surface of the insulating plate140. Both the inner annular protrusion142and the outer annular protrusion144have an annular shape in a plan view. In a plan view, the diameter of the inner annular protrusion142is smaller than the diameter of the outer annular protrusion144. In a plan view, a part or the entirety of the outer annular protrusion144may overlap with the central region111a(substrate support surface) of the substrate support11for supporting the substrate W.

As described above, the plurality of gas introduction paths (e.g., the gas introduction paths13aand the gas introduction paths14a), and the corresponding gas introduction holes (e.g., the gas introduction holes13fand the gas introduction paths14f) are formed in the insulating plate140. The detailed positional relationship and arrangement configuration of the plurality of gas introduction holes and the inner annular protrusion142and the outer annular protrusion144formed on the lower surface of the insulating plate140will be described below. The insulating plate140may have not only the gas introduction holes13fand14f,but also gas introduction holes175having an arbitrary arrangement configuration as described later.

First Embodiment of Insulating Plate

FIG.3Ais a schematic explanatory diagram showing a configuration of an insulating plate140according to a first embodiment, and is an enlarged view of a part thereof (one side of the line-symmetrical shape). Further,FIG.3Bis a schematic plan view of the insulating plate140according to the first embodiment. As shown, in the insulating plate140, an inner annular protrusion142and an outer annular protrusion144protruding downward from the lower surface are formed in the named order from the inside. In one embodiment, a radial width W2of the outer annular protrusion144may be greater than a radial width W1of the inner annular protrusion142. In one embodiment, a protrusion dimension H2of the outer annular protrusion144may be greater than a protrusion dimension H1of the inner annular protrusion142. By making the width and protrusion dimension of the outer annular protrusion144greater than the width and protrusion dimension of the inner annular protrusion142, the area to be scraped away when manufacturing the insulating plate140is reduced, and the workability is improved.

In one embodiment, one or both of the inner annular protrusion142and the outer annular protrusion144have a substantially rectangular shape. The “substantially rectangular shape” referred to herein may be, for example, a so-called round shape with rectangular chamfered lower corners in a cross-sectional view, as shown inFIG.3A. In one embodiment, one or both of the inner annular protrusion142and the outer annular protrusion144may have a substantially semicircular shape in a cross-sectional view.

By forming the inner annular protrusion142and the outer annular protrusion144on the insulating plate140, the region where the inner annular protrusion142and the outer annular protrusion144are formed has a larger member thickness than other regions. This increases the plasma density near the center of the plasma processing space10s,i.e., the central portion of the substrate W, thereby improving the uniformity of a plasma process.

The insulating plate140has a plurality of first gas introduction holes150formed in the inner annular protrusion142. Each first gas introduction hole150is in communication with at least one first gas supply port13cvia any of the plurality of first through holes13e.In one embodiment, the first gas introduction holes150are arranged at equal intervals in the circumferential direction along the circumference of a first circle having a first diameter. The first gas introduction holes150may be formed near the inner wall151of the inner annular protrusion142. When the inner annular protrusion142has a round shape or a substantially semicircular shape in a cross-sectional view, a gas flow toward the inside of the plasma processing space10sis formed by forming the first gas introduction holes150near the inner wall151. The first gas introduction holes150are in communication with the gas outlets (e.g., the gas outlets13dshown inFIG.2) of the gas diffusion plate120to introduce the main gas into the plasma processing space10s.In one embodiment, the first gas introduction holes150overlap with the substrate support surface111aof the substrate support11in a plan view (seeFIGS.10and11).

The insulating plate140has a plurality of second gas introduction holes160formed in the outer annular protrusion144. Each second gas introduction hole160is in communication with at least one first gas supply port13cvia any of the plurality of first through holes13e.In one embodiment, the second gas introduction holes160are arranged at equal intervals in the circumferential direction along the circumference of a second circle having a second diameter larger than the first diameter. The second gas introduction holes160are in communication with the gas outlets (e.g., the gas outlets13dshown inFIG.2) of the gas diffusion plate120to introduce the main gas into the plasma processing space10s.In one embodiment, the second gas introduction holes160overlap with the substrate support surface111aof the substrate support11in a plan view (seeFIGS.10and11).

The insulating plate140has a plurality of third gas introduction holes170formed outside the second gas introduction holes160. Each third gas introduction hole170is in communication with at least one second gas supply port14cvia any of the plurality of second through holes14e.In one embodiment, the third gas introduction holes170are arranged at equal intervals in the circumferential direction along the circumference of a third circle having a third diameter larger than the second diameter. The third gas introduction holes170may be formed in the outer proximal end portion171of the outer annular protrusion144. The third gas introduction holes170are in communication with the gas outlets (e.g., the gas outlets14dshown inFIG.2) of the gas diffusion plate120to introduce the additive gas into the plasma processing space10s.In one embodiment, the third gas introduction holes170do not overlap with the substrate support surface111aof the substrate support11in a plan view (seeFIGS.10and11).

In one embodiment, as shown inFIGS.3A and3B, the insulating plate140may include additional gas introduction holes175in addition to the first gas introduction holes150, the second gas introduction holes160, and the third gas introduction holes170. The arrangement and number of the gas introduction holes175are arbitrary. For example, the gas introduction holes175may be formed inside the inner annular protrusion142and between the inner annular protrusion142and the outer annular protrusion144as shown in the figures.

Although an example of the positional relationship and arrangement of the inner annular protrusion142and the outer annular protrusion144formed on the insulating plate140and the gas introduction holes has been described with reference toFIGS.3A and3B, the present disclosure is not limited thereto.

Second Embodiment of Insulating Plate

FIG.4is a schematic explanatory diagram showing a configuration of an insulating plate140according to a second embodiment. As shown inFIG.4, in one embodiment, the third gas introduction holes170may be located outside the outer annular protrusion144.

Third Embodiment of Insulating Plate

FIG.5is a schematic explanatory diagram showing a configuration of an insulating plate140according to a third embodiment. As shown inFIG.5, in one embodiment, the third gas introduction holes170may be provided in the outer annular protrusion144.

Fourth Embodiment of Insulating Plate

FIG.6is a schematic explanatory diagram showing a configuration of an insulating plate140according to a fourth embodiment. As shown inFIG.6, in one embodiment, the third gas introduction holes170may be provided in the outer annular protrusion144. Each of the third gas introduction holes170may have an upper end inlet170aand a lower end outlet170bwhich are located at different positions in the radial direction. That is, the shape of the third gas introduction holes170may be arbitrarily designed according to the width of the outer annular protrusion144in the radial direction.

Fifth Embodiment of Insulating Plate

FIG.7is a schematic explanatory diagram showing a configuration of an insulating plate140according to a fifth embodiment. In one embodiment, the insulating plate140has a plurality of fourth gas introduction holes180formed at an inner proximal end portion181of the outer annular protrusion144, as shown inFIG.7. Each fourth gas introduction hole180is in communication with at least one first gas supply port13cvia any of the plurality of first through holes13e.In one embodiment, the fourth gas introduction holes180are arranged at equal intervals in the circumferential direction along the circumference of a fourth circle having a fourth diameter larger than the first diameter and smaller than the second diameter. The fourth gas introduction holes180may be provided at the inner proximal end portion181of the outer annular protrusion144. These fourth gas introduction holes180are in communication with the gas outlets (e.g., the gas outlets13dshown inFIG.2) of the gas diffusion plate120to introduce the main gas into the plasma processing space10s.

Sixth Embodiment of Insulating Plate

FIG.8is a schematic explanatory diagram showing a configuration of an insulating plate140according to a sixth embodiment. As shown inFIG.8, in one embodiment, an additional outer annular protrusion186protruding downward from the lower surface of the insulating plate140may be formed further radially outward of the outer annular protrusion144. In one embodiment, a radial width W3of the additional outer annular protrusion186may be greater than the width W2of the outer annular protrusion144. A protrusion dimension H3of the additional outer annular protrusion186may be greater than the protrusion dimension H2of the outer annular protrusion144. The third gas introduction holes170may be formed at an outer proximal end portion188of the additional outer annular protrusion186.

Seventh Embodiment of Insulating Plate

FIG.9is a schematic explanatory diagram showing a configuration of an insulating plate140according to a seventh embodiment. As shown inFIG.9, in the insulating plate140according to the sixth embodiment, the third gas introduction holes170may be provided in the additional outer annular protrusion186.

Substrate Processing Method Using Plasma Processing Apparatus

Next, an example of a method for processing the substrate W in the plasma processing apparatus1configured as described above will be described. In the plasma processing apparatus1, various plasma processes such as an etching process, a film-forming process, a diffusion process, and the like are performed on the substrate W.

First, the substrate W is loaded into the plasma processing chamber10and placed on the electrostatic chuck114of the substrate support11. Next, a voltage is applied to the attraction electrode of the electrostatic chuck114, whereby the substrate W is attracted and held on the electrostatic chuck114by an electrostatic force.

When the substrate W is attracted and held by the electrostatic chuck114, the inside of the plasma processing chamber10is then depressurized into a vacuum environment. Next, a processing gas is supplied from the gas supply20to the plasma processing space10svia the upper electrode assembly13. Further, the source RF power for plasma generation is supplied from the first RF generator31ato the upper electrode or the lower electrode, thereby exciting the processing gas and generating plasma. In addition, the bias RF power may be supplied to the lower electrode from the second RF generator31b.Then, in the plasma processing space10s, the substrate W is subjected to a plasma process by the action of the generated plasma.

At this time, a magnetic field is generated within the plasma processing space10sby the electromagnet unit15. Further, as described above, by forming the inner annular protrusion142and the outer annular protrusion144on the insulating plate140, it is possible to improve the uniformity of the plasma process. In addition, when an additive gas is introduced into the plasma processing space10sin addition to the main gas during the plasma process, by appropriately designing the arrangement of the gas introduction holes, and the like, it is possible to prevent the additive gas from going around toward the center of the substrate W.

When finishing the plasma process, the supply of the source RF power from the first RF generator31aand the supply of the processing gas from the gas supply20are stopped. If the bias RF power is being supplied during the plasma process, the supply of the bias RF power is also stopped.

Next, the attraction and holding of the substrate W by the electrostatic chuck114is stopped, and static electricity is removed from the substrate W and the electrostatic chuck114after the plasma process. Thereafter, the substrate W is detached from the electrostatic chuck114, and the substrate W is unloaded from the plasma processing apparatus1. In this way, a series of plasma processes are completed.

Actions and Effects of the Technique of the Present Disclosure

In the embodiments described above, for example, the inner annular protrusion142and the outer annular protrusion144as shown inFIGS.3A and3Bare formed on the lower surface of the insulating plate140. This increases the plasma density in a specific region of the plasma processing space10s,for example, in the central portion of the substrate W, and improves the uniformity of the plasma process. That is, it is possible to improve the uniformity of the plasma process on the substrate W.

In the above-described embodiment, the plurality of gas introduction holes are provided in each of the protrusions such as the inner annular protrusion142, the outer annular protrusion144, and the additional outer annular protrusion186formed on the lower surface of the insulating plate140, or in the proximal end portion of each of the protrusions. Thus, the gas distribution of the main gas and the additive gas introduced into the plasma processing space10scan be suitably changed, and the uniformity of the plasma process on the substrate W can be improved. For example, by providing the third gas introduction holes170outside the second gas introduction holes160, the additive gas introduced from the third gas introduction holes170can be prevented from going around toward the vicinity of the central portion of the substrate W.

For example, as shown inFIG.10, when the third gas introduction holes170are formed in the outer proximal end portion171of the outer annular protrusion144(seeFIGS.3A,3B and7), the additive gas or the mixed gas introduced therethrough flows toward the vicinity of the peripheral edge portion of the substrate W and the outside thereof, as indicated by P1in the figure. That is, the outer wall of the outer annular protrusion144serves as a wall, and the additive gas or the mixed gas is prevented from going around toward the vicinity of the central portion of the substrate W, which makes it possible to improve controllability of the gas flow.

Further, as shown inFIG.11, when the second gas introduction holes160are formed in the outer annular protrusion144(seeFIGS.3A to9), the flow PI of the additive gas or the mixed gas introduced from the third gas introduction holes170is blocked by the flow P2of the processing gas introduced from the second gas introduction holes160, and is prevented from going around toward the vicinity of the central portion of the substrate. Further, the first gas introduction holes150are provided in the inner annular protrusion142. The flow P3of the processing gas introduced therefrom prevents the gas flows P1and P2from going around toward the vicinity of the central portion of the substrate W.

Further, for example, as shown inFIG.12, by providing the inner annular protrusion142and the outer annular protrusion144, as indicated by P4in the figure, the flow of the processing gas introduced from any gas introduction hole175formed between these protrusions is not concentrated near the central portion of the substrate W. Further, as shown inFIG.13, the second gas introduction holes160are formed in the outer annular protrusion144to introduce the processing gas as indicated by P5in the figure. This can prevent the processing gas (P4in the figure) introduced from any gas introduction hole175formed between the protrusions from escaping outward due to the gas curtain effect. That is, due to the presence of walls and the gas curtain effect accompanying the formation of the protrusions, radicals (neutral particles) are concentrated in the central portion of the substrate W, thereby improving the uniformity of the plasma process.

In the above-described embodiment, the case has been described in which the protrusions such as the inner annular protrusion142and the outer annular protrusion144are formed on the lower surface of the insulating plate140included in the upper electrode assembly13, and the plurality of gas introduction holes are provided. However, the technique of the present disclosure is not limited thereto. The technique of the present disclosure is applicable to an exposed surface exposed to plasma (hereinafter also simply referred to as an exposed surface) of the upper electrode assembly13included in the plasma processing apparatus1.

When the upper electrode assembly13has an exposed surface as a plasma exposure surface, for example, on its lower surface, the exposed surface may have the following configuration. That is, in one embodiment, the inner annular protrusion142and the outer annular protrusion144protruding downward may be formed on the exposed surface. In one embodiment, the plurality of first gas introduction holes150in communication with at least one first gas supply port13cmay be formed in the inner annular protrusion142of the exposed surface. In addition, in one embodiment, the plurality of second gas introduction holes160in communication with at least one first gas supply port13cmay be formed in the outer annular protrusion144of the exposed surface. Further, in one embodiment, the plurality of third gas introduction holes170in communication with at least one second gas supply port14cmay be formed outside the second gas introduction holes160of the exposed surface.

According to the present disclosure in some embodiments, it is possible to improve the uniformity of a plasma density distribution by partially changing the distribution of a gas introduced into a plasma processing chamber.