Dielectric member, structure, and substrate processing apparatus

A dielectric member that is attached to a lower surface of a stage is provided. The stage includes a base provided with a base channel through which a heat exchange medium passes. The dielectric member includes at least one first component including a passage that is connected to the base channel, and a second component surrounding the first component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based on and claims priority to Japanese Patent Application No. 2019-172298 filed on Sep. 20, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a dielectric member, a structure, and a substrate processing apparatus.

BACKGROUND

A substrate processing apparatus is known, in which a substrate placed on a stage is subjected to plasma processing.

Patent Document 1 describes an electrostatic chuck device in which a cushioning material is provided in the gap between electrode supports, to relieve stress caused by thermal expansion and thermal contraction.

RELATED ART DOCUMENT

Patent Document

SUMMARY

In one aspect, the present disclosure provides a dielectric member, a structure, and a substrate processing apparatus that prevent breakage due to thermal stress even if the temperature of a heat exchange medium supplied to a channel in a stage is changed.

In order to solve the above problem, according to one aspect, a dielectric member that is attached to a lower surface of a stage is provided. The stage includes a base provided with a base channel through which a heat exchange medium passes. The dielectric member includes at least one first component including a passage that is connected to the base channel, and a second component surrounding the first component.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, embodiments for carrying out the present disclosure will be described with reference to the drawings. In each drawing, elements having identical features are given the same reference symbols and overlapping descriptions may be omitted.

A substrate processing apparatus1according to an embodiment will be described with reference toFIG.1.FIG.1is a cross-sectional view illustrating an example of the substrate processing apparatus1according to the present embodiment.

The substrate processing apparatus1includes a chamber10. The chamber10provides an interior space10stherein. The chamber10includes a chamber body12. The chamber body12is generally cylindrical in shape. The chamber body12is formed of, for example, aluminum. A corrosion resistant film is provided on the inner wall of the chamber body12. The film may be formed of ceramic such as aluminum oxide and yttrium oxide.

A passage12pis formed in the side wall of the chamber body12. A substrate W is transferred between the interior space10sand the exterior of the chamber10through the passage12p. The passage12pis opened and closed by a gate valve12gprovided along the side wall of the chamber body12.

A support13is provided on the bottom of the chamber body12. The support13is formed of an insulating material. The support13is generally cylindrical in shape. The support13extends upward from the bottom of the chamber body12in the interior space10s. At the upper portion of the support13, a stage14is provided. The stage14is configured to support the substrate W in the interior space10s.

The stage14includes a lower electrode18and an electrostatic chuck20. The stage14may further include an electrode plate16. In the present specification, a set of the lower electrode18and the electrode plate16is referred to as a “base”. The electrode plate16is formed of a conductor such as aluminum, and is generally disc-shaped. The lower electrode18is disposed on the electrode plate16. The lower electrode18is formed of a conductor such as aluminum, and is generally disc-shaped. The lower electrode18is electrically connected to the electrode plate16.

The electrostatic chuck20is provided on the lower electrode18. A substrate W is placed on the upper surface of the electrostatic chuck20. The electrostatic chuck20includes a body and an electrode (not illustrated). The body of the electrostatic chuck20is generally disc-shaped, and is formed of a dielectric material. The electrode of the electrostatic chuck20is a film-like electrode provided within the body of the electrostatic chuck20. The electrode of the electrostatic chuck20is connected to a direct-current (DC) power supply20pvia a switch20s. When voltage from the DC power supply20pis applied to the electrode of the electrostatic chuck20, electrostatic attractive force is generated between the electrostatic chuck20and the substrate W. By the electrostatic attractive force, the substrate W is held by the electrostatic chuck20. Also, the electrostatic chuck20is provided with a heater (not illustrated).

An edge ring25is disposed on a periphery of the lower electrode18to surround the edge of the substrate W. The edge ring25improves in-plane uniformity of plasma processing applied to the substrate W. The edge ring25may be formed of silicon, silicon carbide, quartz, or the like.

A flow passage (base channel)18fis provided within the lower electrode18. A heat exchange medium (e.g., refrigerant) is supplied to the flow passage18ffrom a chiller unit (not illustrated) provided outside the chamber10through a pipe22a. The heat exchange medium supplied to the flow passage18fis returned to the chiller unit via a pipe22b. In the substrate processing apparatus1, the temperature of the substrate W placed on the electrostatic chuck20is adjusted by heat exchange between the heat exchange medium and the lower electrode18and by a heater (not illustrated).

The substrate processing apparatus1is provided with a gas supply line24. The gas supply line24supplies heat transfer gas (e.g., He gas) from a heat transfer gas supply mechanism to a gap between the upper surface of the electrostatic chuck20and the bottom surface of the substrate W.

The substrate processing apparatus1further comprises an upper electrode30. The upper electrode30is provided above the stage14. The upper electrode30is supported on the top of the chamber body12via a member32. The member32is formed of an insulating material. The upper electrode30and the member32occlude the top opening of the chamber body12.

The upper electrode30may include a top plate34and a support36. The lower surface of the top plate34is exposed to the interior space10s, and defines the interior space10s. The top plate34may be formed of a low resistance conductor or semiconductor with low Joule heat generation. The top plate34has multiple gas discharge holes34apenetrating the top plate34in a thickness direction of the top plate34.

The support36removably supports the top plate34. The support36is formed of an electrically conductive material such as aluminum. Inside the support36, a gas diffusion chamber36ais provided. The support36has multiple gas holes36bextending downward from the gas diffusion chamber36a. The multiple gas holes36bcommunicate with the multiple gas discharge holes34a, respectively. A gas inlet36cis formed in the support36. The gas inlet36cis connected to the gas diffusion chamber36a. A gas supply line38is connected to the gas inlet36c.

Valves42, flow controllers44, and gas sources40are connected to the gas supply line38. The gas sources40, the valves42, and the flow controllers44constitute a gas supply section. Each of the valves42may be an open/close valve. Each of the flow controllers44is a mass flow controller or a pressure-controlled flow controller. Each of the gas sources40is connected to the gas supply line38via a corresponding open/close valve of the valves42and a corresponding flow controller of the flow controllers44.

In the substrate processing apparatus1, a shield46is removably provided along the inner wall surface of the chamber body12and the outer circumference of the support13. The shield46prevents reaction by-products from adhering to the chamber body12. The shield46is constructed by, for example, forming a corrosion resistant film on the surface of a member formed of aluminum. The corrosion resistant film may be formed of ceramic such as yttrium oxide.

A baffle plate48is provided between the outer side wall of the support13and the inner side wall of the chamber body12. The baffle plate43is constructed by, for example, forming a corrosion-resistant film (a film such as yttrium oxide) on the surface of a member formed from aluminum. Multiple through-holes are formed in the baffle plate48. An exhaust port12eis provided below the baffle plate48, at the bottom of the chamber body12. An exhaust device50is connected to the exhaust port12evia an exhaust pipe52. The exhaust device50includes a pressure regulating valve and a vacuum pump such as a turbomolecular pump.

The substrate processing apparatus1includes a first radio frequency power supply62and a second radio frequency power supply64. The first radio frequency power supply62is a power source that generates first radio frequency power. The first radio frequency power has a frequency suitable for generating a plasma. The frequency of the first radio frequency power is, for example, a frequency in the range of 27 MHz to 100 MHz. The first radio frequency power supply62is connected to the lower electrode18via a matcher66and the electrode plate16. The matcher66includes circuitry for causing the output impedance of the first radio frequency power supply62to match impedance of the load side (lower electrode18side). The first radio frequency power supply62may be connected to the upper electrode30via the matcher66. The first radio frequency power supply62constitutes an exemplary plasma generator.

The second radio frequency power supply64is a power source that generates second radio frequency power. The second radio frequency power has a frequency lower than the frequency of the first radio frequency power. In a case in which the second radio frequency power is used in conjunction with the first radio frequency power, the second radio frequency power is used as radio frequency power for biasing to draw ions into the substrate W. The frequency of the second radio frequency power is, for example, a frequency in the range of 400 kHz to 13.56 MHz. The second radio frequency power supply64is connected to the lower electrode18via a matcher68and the electrode plate16. The matcher68includes circuitry for causing the output impedance of the second radio frequency power supply64to match impedance of the load side (lower electrode18side).

It should be noted that a plasma may be generated using the second radio frequency power, without using a first radio frequency power. That is, a plasma may be generated using only single radio frequency power. In such a case, the frequency of the second radio frequency power may be greater than 13.56 MHz, for example 40 MHz. In this case, the substrate processing apparatus1may not include the first radio frequency power supply62and the matcher66. The second radio frequency power supply64constitutes an exemplary plasma generator.

In the substrate processing apparatus1, gas is supplied from the gas supply to the interior space10sto produce a plasma. Also, as the first radio frequency power and/or the second radio frequency power are supplied, a radio frequency electric field is generated between the upper electrode30and the lower electrode18. The generated radio frequency electric field generates a plasma.

The substrate processing apparatus1includes a power supply70. The power supply70is connected to the upper electrode30. The power supply70applies voltage to the upper electrode30to draw positive ions that are present, in the interior space10sinto the top plate34.

The substrate processing apparatus1may further include a controller80. The controller80may be a computer including a processor, a storage device such as a memory, an input device, a display device, an input/output interface of a signal, or the like. The controller80controls each part of the substrate processing apparatus1. An operator can perform input operations of commands to manage the substrate processing apparatus1, by using the input device of the controller80. The controller80can also display an operation status of the substrate processing apparatus1on the display device, further, a control program and recipe data are stored in the storage device. The control program is executed by the processor to cause the substrate processing apparatus1to perform various processes. The processor executes the control program, and controls each part of the substrate processing apparatus1in accordance with the recipe data.

The first radio frequency power and the second radio frequency power are applied from the bottom center of the electrode plate16, and are supplied to the lower electrode18while being transmitted through the surface of the electrode plate16. Thus, a dielectric plate (dielectric member)26is provided to cover the lower surface of the electrode plate16.

The dielectric plate26will be described further.FIG.2is an exploded perspective view of an example of the dielectric plate26. The dielectric plate26includes a plate body (second component)27and a block (first component)28. The dielectric plate26(plate body27and block28) is formed of a dielectric material, specifically formed of ceramic.

The plate body27includes a bottom plate portion100and a side wall portion110. The electrode plate16is disposed in a space formed by the bottom plate portion100and the side wall portion110. Multiple upright portions120each extending upward are formed on the bottom plate portion100. In a state in which the electrode plate16is disposed in the space formed by the bottom plate portion100and the side wall portion110, the upright portions120abut the electrode plate16. The plate body27is secured to the electrode plate16with the upright portions120. The plate body27includes an opening (second opening)130, which is formed substantially in the center of the bottom plate portion100. A power feeding rod (not illustrated) is passed through the opening130, one end of which is connected to the electrode plate16, and the other end of which is connected to the first radio frequency power supply62and/or the second radio frequency power supply64.

An opening (first opening)140for displacing the block28is formed in the plate body27at a location away from the center of the plate body27. In other words, the opening140for placing the block28is formed to avoid the opening130formed substantially in the center of the plate body27. This allows high frequency power to be supplied from the substantial center of the electrode plate16, thereby improving the circumferential uniformity of the high frequency power transmitted to the lower electrode18.

In the block23, flow passages28aand28bare formed. The heat exchange medium, which is supplied from the outside of the chamber10via the pipe22a, passes through the flow passage28a, and is supplied to one end of the flow passage18fin the lower electrode18. The heat transfer medium, which flows out of the other end of the flow passage18fin the lower electrode18, passes through the flow passage28band is drained out of the chamber10via the pipe22b.

The opening140is formed to be larger than the size of the block28. The block28is disposed within the opening140, and is secured to the electrode plate16. Between the block28and the opening140, a gap (e.g., 1 mm) is formed. Therefore, the sidewall of the block28is not in contact with the sidewall of opening140, and therefore thermal conduction is suppressed.

In processing the substrate W, in order to change the temperature of the substrate W (temperature of the stage14), it is required to change the temperature of the heat exchange medium supplied to the flow passage18fof the lower electrode18. For example, if the temperature of the heat exchange medium is supplied at a first temperature (for example, 0° C.), the temperature of the base and the dielectric plate26will become approximately equal to the first temperature in a steady state. Here, if the temperature of the heat exchange medium supplied is changed to a second temperature (for example, 150° C.) higher than the first temperature, heat is rapidly propagated in the base formed of metal (for example, aluminum), and the temperature difference in the base becomes small.

In contrast, the dielectric plate26formed of dielectric has lower thermal conductivity than the base. Therefore, unlike the dielectric plate26according to the present embodiment, if the flow passages28aand28bare formed in the plate body27, the temperature rises near the flow passages28aand28bthrough which the high-temperature heat exchange medium passes, but the temperature does not rise at the outer periphery of the dielectric plate26. Therefore, thermal stress concentration may occur due to temperature differences in the dielectric plate26.

In the dielectric plate26illustrated inFIG.2, the block28having the flow passages28aand28bis provided separately from the plate body27. When a high temperature heat exchange medium flows through the flow passages28aand23b, the temperature of the block28increases. Here, the block28is formed to be smaller than the plate body27and has a smaller heat capacity than the plate body27. Therefore, heat in the heat exchange medium is propagated throughout the block28. This can suppress occurrence of non-uniform temperature distribution in the block28, and occurrence of thermal stress concentration can be avoided.

Further, because a gap is provided between the opening140of the plate body27and the block28, sudden temperature rise near the opening140of the plate body27can be suppressed. Thus, occurrence of non-uniform temperature distribution in the plate body27can be reduced to suppress thermal stress concentration.

Also, as the opening140is larger than the block28, even if thermal expansion of the block28occurs, generation of stress that attempts to expand the opening140is prevented. Thus, stress generation in the plate body27due to thermal expansion of the block28can be suppressed, and stress concentration can be suppressed.

Also, by supplying a high temperature heat exchange medium to the flow passage18fof the lower electrode18through the block28, the temperature of the lower electrode18rises and the temperature of the electrode plate16also rises. Then, heat is transferred to the plate body27from the upright portions120, which are in contact with the electrode plate16. Because heat is transferred from the electrode plate16to the plate body27as described above, the plate body21is prevented from being heated locally. This reduces stress concentration due to thermal stress.

As described above, the structure including the stage14and the dielectric plate26can suppress stress concentration caused by temperature differences in the dielectric plate26, and deformation and breakage of the dielectric plate26is prevented, even if the temperature of the heat exchange medium is changed rapidly. Also, the substrate processing apparatus1, which includes the dielectric plate26according to the present embodiment, can expand a temperature range of a heat exchange medium, supplied to the flow passage18f. Therefore, in the substrate processing apparatus1, processes each being performed at different substrate temperatures (different temperatures in the stage14) can be applied to the substrate W. In addition, even if the temperature of the heat exchange medium is changed rapidly, deformation or breakage of the dielectric plate26can be suppressed. Therefore, time required for switching the temperature of the heat exchange medium can be reduced.

The dielectric member (dielectric plate26), the structure including the stage14and the dielectric plate26, and the substrate processing apparatus have been described above. However, the present invention is not limited to the above-described embodiment, and various modifications and enhancement can be made within the scope of the gist of the present disclosure described in the claims.

In the above-described embodiment, a case in which only a single block28separate from the plate body27is provided in the dielectric plate26has been described, but the dielectric plate26is not limited to the case. For example, there may be a case in which a substrate W to be placed on the stage14is divided into multiple zones (e.g., concentric zones), and temperature of the substrate W is controlled in each of the zones. In such a case, for each of the zones, a different flow passage18fis formed in the lower electrode18. In a case in which multiple flow passages18fare formed in the lower electrode18as described above, blocks28may be provided in the respective flow passages18f. Also, multiple openings140may be formed in the plate body27for the respective blocks28. Accordingly, even if the heat exchange medium having a different temperature is supplied to each of the flow passages18f, occurrence of non-uniform temperature distribution can be suppressed in each of the blocks28, so that thermal stress concentration can be suppressed.