SUSCEPTOR, SUBSTRATE PROCESSING APPARATUS AND PROTECTION METHOD

A susceptor includes a base; a substrate placing member provided on the base; a bonding layer configured to bond the base and the substrate placing member; and a protection member disposed in a space which an outer peripheral surface of the bonding layer faces and allowed to deactivate a radical while having gas permeability.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No. 2019-009872 filed on Jan. 24, 2019, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The various aspects and embodiments described herein pertain generally to a susceptor, a substrate processing apparatus and a protection method.

BACKGROUND

Conventionally, there is known a substrate processing apparatus configured to perform a plasma processing on a substrate such as a semiconductor wafer. Such a substrate processing apparatus has, between a base and a substrate placing member, a bonding layer which bonds the base and the substrate placing member. The bonding layer is consumed by plasma, starting from an outer peripheral surface thereof. If the bonding layer is consumed and the outer peripheral surface thereof is thus diminished, a space is generated, and a temperature control in a portion where the space is generated becomes non-uniform, resulting in deterioration of uniformity of etching characteristics. As a resolution, to block introduction of the plasma and protect the bonding layer in this substrate processing apparatus, an O-ring is disposed in a gap, between the base and the substrate placing member, which the outer peripheral surface of the bonding layer faces (see, for example, Patent Document 1).

SUMMARY

In one exemplary embodiment, a susceptor includes a base; a substrate placing member provided on the base; a bonding layer configured to bond the base and the substrate placing member; and a protection member disposed in a space which an outer peripheral surface of the bonding layer faces and allowed to deactivate a radical while having gas permeability.

DETAILED DESCRIPTION

Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. In the various drawings, same or corresponding parts will be assigned same reference numerals.

Conventionally, there is known a substrate processing apparatus configured to perform a substrate processing such as a plasma processing on a substrate such as a semiconductor wafer. Such a substrate processing apparatus has, between a base and a substrate placing member, a bonding layer which bonds the base and the substrate placing member. The bonding layer is consumed by plasma, starting from an outer peripheral surface thereof. In the substrate processing apparatus, if the bonding layer is consumed and the outer peripheral surface thereof is thus diminished, a space is generated, and a temperature control in a portion where the space is generated becomes non-uniform, resulting in deterioration of in-surface uniformity of etching characteristics. As a resolution, to block introduction of the plasma and protect the bonding layer in this substrate processing apparatus, an O-ring is disposed in a gap, between the base and the substrate placing member, which the outer peripheral surface of the bonding layer faces (see, for example, Patent Document 1).

However, the O-ring may be protruded from this gap, between the base and the substrate placing member, which the outer peripheral surface of the bonding layer faces, as the O-ring is sucked when evacuation is performed. Further, the O-ring may be protruded from the gap, between the base and the substrate placing member, which the outer peripheral surface of the bonding layer faces, as a load caused by thermal expansion or thermal contraction of the base and the substrate placing member is applied to the O-ring. Furthermore, the O-ring may be protruded from the gap, between the base and the substrate placing member, which the outer peripheral surface of the bonding layer faces due to thermal expansion of the O-ring itself. If the O-ring is protruded, the plasma may enter the gap to reach the outer peripheral surface of the bonding layer. As a result, the bonding layer may be consumed by the plasma.

[Configuration of Plasma Processing Apparatus]

First, the substrate processing apparatus will be explained. The substrate processing apparatus is configured to perform a plasma processing on a substrate. An exemplary embodiment will be described for a case where the substrate processing apparatus is a plasma processing apparatus configured to perform a plasma etching on a semiconductor wafer (hereinafter, simply referred to as “wafer”) as the substrate.

FIG. 1is a schematic cross sectional view illustrating a configuration of a plasma processing apparatus100according to the exemplary embodiment. As depicted inFIG. 1, the plasma processing apparatus100has a processing chamber1which is hermetically sealed and electrically grounded. The processing chamber1is of a cylindrical shape and is made of, for example, aluminum. The processing chamber1confines a processing space in which plasma is formed. The processing chamber1is provided with an opening3through which the wafer W is carried into or out of the processing chamber1; and a gate valve4configured to be opened or closed via a hermetically sealing sealant. The sealant may be, but not limited to, an O-ring.

Though not shown inFIG. 1, a load lock chamber is connected to the processing chamber1via the gate valve4, and a transfer device is provided in the load lock chamber. The transfer device is configured to carry the wafer W into or out of the processing chamber1.

An exhaust opening19for decompressing the processing chamber1is formed in a lower portion of a sidewall of the processing chamber1. The exhaust opening19is connected to a non-illustrated vacuum exhaust device via an opening/closing valve such as, but not limited to, a butterfly valve. The vacuum exhaust device may be, for example, a rotary pump or a turbo molecular pump.

Further, a susceptor2configured to support the wafer W thereon is provided within the processing chamber1. The susceptor2includes a base10and an electrostatic chuck (ESC)9.

The base10has a substantially columnar shape and is made of a conductive metal such as, but not limited to, aluminum. The base10serves as a lower electrode. The base10is supported by a base supporting table5. The base supporting table5has a substantially columnar shape and is made of a conductive metal such as, but not limited to, aluminum. The base supporting table5has therein a cooling jacket6which stores a cooling medium therein. The cooling jacket6is provided with a path71through which the cooling medium is introduced into the cooling jacket6; and a path72through which the cooling medium is discharged from the cooling jacket6. The path71and the path72are hermetically formed through a bottom surface of the processing chamber1. A coolant having a preset temperature is supplied into the cooling jacket6to be circulated therein via the paths71and72from a chiller70. Accordingly, the base supporting table5and the base10are controlled to a preset temperature.

The following description will be provided for a case where the cooling jacket6is provided within the base supporting table5. However, the exemplary embodiment is not limited thereto. By way of example, the cooling jacket6may be provided within the base10.

The base10is connected to a high frequency power supply12via a matching device11. The high frequency power supply12is for plasma formation and is configured to supply a high frequency power having a preset frequency (e.g., 13.56 MHz or 40 MHZ) to the base10of the susceptor2.

The electrostatic chuck9is made of, by way of example, ceramic (having a linear thermal expansion coefficient of about 7.1×10−6(cm/cm/° C.)). The electrostatic chuck9has therein an electrode plate9band a heater9a. A top surface of the electrostatic chuck9is of a flat disk shape, and this top surface is configured as a placing surface on which the wafer W is placed. The electrode plate9bis connected to one end of a conductive line25, and the other end of the conductive line25is connected to a power feed rod26. The conductive line25is enclosed by an insulating member such as Teflon (registered trademark) embedded in the base10. The power feed rod26is made of, but not limited to, copper and is configured to supply a high voltage ranging from about 200 V to about 3 KV. The power feed rod26penetrates the bottom surface of the processing chamber1hermetically while being insulated from the processing chamber1, and is connected to a DC power supply27via an electronic switch28. The electronic switch28is turned ON or OFF in response to a non-illustrated control signal that controls the apparatus. As a DC voltage is applied to the electrode plate9bfrom the DC power supply27, the wafer W is attracted to the electrode plate9bby a Coulomb force. The electrostatic chuck9is an example of a substrate placing member.

Further, an edge ring21is disposed on a peripheral portion of the electrostatic chuck9to surround the wafer W placed on the placing surface of the electrostatic chuck9. The edge ring21is made of, by way of example, quartz. Further, the edge ring21is also called a focus ring.

The base10and the electrostatic chuck9are bonded by a bonding layer20. A protection member22is disposed in a space which an outer peripheral surface of the bonding layer20faces. The protection member22is a member configured to protect the bonding layer20from the plasma. Structures of the bonding layer20and the protection member22will be elaborated later.

Further, through holes16are formed through the base10, the base supporting table5, the bonding layer20and the electrostatic chuck9. A pusher pin15which is electrically grounded via a resistor or an inductance is provided in each through hole16. The pusher pin15is connected to an air cylinder18as a vertical moving mechanism via an expansible/contractible bellows17which seals the processing chamber1hermetically. The pusher pin15is moved up and down by the air cylinder18when the wafer W is transferred from/to the transfer device of the load lock chamber, and when the wafer W is brought into contact with or separated from the electrostatic chuck9.

A multiple number of through holes13afor uniformly supplying a heat transfer medium to a rear surface of the wafer W is formed through the base10and the electrostatic chuck9. The through holes13aare connected to a gas storage room13which allows a pressure of a He gas applied to the through holes13ato be uniform. The gas storage room13is connected to a supply line14through which the heat transfer medium is introduced into the processing chamber1from the outside. The heat transfer medium may be, but not limited to, a He gas as an inert gas. However, the heat transfer medium may not be limited thereto, and any of various kinds of gases may be used.

An upper electrode50is disposed above the base10. The upper electrode50is electrically grounded. A processing gas is supplied into the upper electrode50through a gas supply line51. This processing gas is discharged toward the wafer W through a multiple number of small holes52radially arranged in a bottom wall of the upper electrode50. Here, as the high frequency power supply12is turned ON, plasma of the discharged processing gas is formed between the upper electrode50and the wafer W.

An overall operation of the plasma processing apparatus100having the above-described configuration is controlled by a controller90. The controller90includes a process controller91having a CPU and configured to control individual components of the plasma processing apparatus100; a user interface92; and a storage93.

The user interface92includes a keyboard through which a process manager inputs commands to manage the plasma processing apparatus100, a display which visually displays an operational status of the plasma processing apparatus100, and so forth.

The storage93stores therein a control program (software) for implementing various processings performed in the plasma processing apparatus100under the control of the process controller91or a recipe including processing condition data, etc. In response to an instruction from the user interface92or the like, a necessary recipe is retrieved from the storage93and executed by the process controller91, so that a required processing is performed in the plasma processing apparatus100under the control of the process controller91. The control program or the recipe including the processing condition data, etc. may be used while being stored on a computer-readable recording medium (e.g., a hard disk, a CD, a flexible disk or a semiconductor memory), or may be used on-line by being transmitted through, e.g., a dedicated line, whenever necessary.

[Configuration of Major Components of Susceptor]

Now, referring toFIG. 2, a configuration of major components of the susceptor2will be described.FIG. 2is a schematic cross sectional view illustrating an example configuration of the major components of the susceptor2in the plasma processing apparatus100ofFIG. 1. As depicted inFIG. 2, the susceptor2includes the base10and the electrostatic chuck9disposed on the base10.

The base10is of a substantially columnar shape and has a thermally sprayed film10aon a front surface thereof. The thermally sprayed film10acovers the front surface of the base10such that the front surface of the base10is not exposed to the inside of the processing chamber1. The thermally sprayed film10ais made of, by way of non-limiting example, Al2O2or Y2O3. The base10has a protruding portion10cat a peripheral portion thereof, and a height of this protruding portion10cis higher than that of a central portion10bof the base10.

The electrostatic chuck9is disposed on the central portion10bof the base10. The electrostatic chuck9has the disk shape having the flat top surface, and this top surface is configured as the placing surface on which the wafer W is placed. Further, a gap61extending in a longitudinal direction is provided between an outer peripheral surface of the electrostatic chuck9and an inner peripheral surface of the protruding portion10cof the base10.

The edge ring21is disposed at the peripheral portion of the electrostatic chuck9to surround the wafer W placed on the placing surface of the electrostatic chuck9. The edge ring21is disposed at the peripheral portion of the electrostatic chuck9such that a bottom surface of the edge ring21is spaced apart from a top surface of the protruding portion10cof the base10. That is, a gap62, which extends in a transversal direction and is connected to the gap61, is formed between the bottom surface of the edge ring21and the top surface of the protruding portion10cof the base10. Accordingly, since a labyrinth path ranging from the gap62to the gap61is built, the plasma is suppressed from reaching the gap61.

The base10and the electrostatic chuck9are bonded by the bonding layer20. The bonding layer20bonds the electrostatic chuck9and the base10and allows a heat transfer between the electrostatic chuck9and the base10. The outer peripheral surface of the bonding layer20faces the gap61between the inner peripheral surface of the protruding portion10cof the base10and the outer peripheral surface of the electrostatic chuck9.

The protection member22is disposed in the space which the outer peripheral surface of the bonding layer20faces, that is, in the gap61between the inner peripheral surface of the protruding portion10cof the base10and the outer peripheral surface of the electrostatic chuck9. The protection member22is formed of a member capable of deactivating radicals and having gas permeability.

In the plasma processing apparatus100, however, when the plasma etching is performed, the radicals in the plasma may go around the edge ring21to enter the gap61. As a result, the bonding layer20is consumed, starting from the outer peripheral surface thereof. In the plasma processing apparatus100, if the bonding layer20is consumed and the outer peripheral surface thereof is thus diminished, a space is formed at a portion of the outer peripheral surface of the bonding layer20. In the plasma processing apparatus100, a temperature control of the electrostatic chuck9at the portion where the space is formed becomes non-uniform, so that in-surface uniformity of etching characteristics is deteriorated.

For this reason, conventionally, maintenance is performed regularly in the plasma processing apparatus100. For example, in the plasma processing apparatus100, as the bonding layer20is consumed, there is performed maintenance of re-forming the bonding layer20by replacing the electrostatic chuck9. In the plasma processing apparatus100, however, if the maintenance is required in a short period of time, the work of the maintenance is increased, resulting in an increase of maintenance cost of the plasma processing apparatus100. Furthermore, in the plasma processing apparatus100, if the maintenance is required in the short period of time, a downtime during which the plasma processing cannot be performed is increased, resulting in deterioration of productivity.

In view of this, in the plasma processing apparatus100, the protection member22capable of deactivating the radicals and having the gas permeability is disposed in the gap61, as depicted inFIG. 2. The protection member22may be made of a porous body having a multiple number of pores distributed in an irregular manner. The protection member22may be formed of a fabric material such as a mesh, a non-woven fabric, twisted threads or a woven fabric, or a sponge or the like, or formed by combining the fabric material and the sponge.

In the plasma processing apparatus100according to the present exemplary embodiment, the protection member22made of a mesh material is disposed in the gap61. The protection member22is formed by winding, for example, a fluorine-containing resin material in a mesh shape. The fluorine-containing resin material may be, by way of non-limiting example, Teflon (registered trademark).

FIG. 3is a diagram illustrating an example structure of the protection member22made of the mesh material. As depicted inFIG. 3, the protection member22has a mesh-shaped structure in which a multiple number of pores are distributed in an irregular manner, and has a property allowing the radicals to collide with inner wall surfaces of the multiple number of pores to thereby deactivate the radicals.

In the plasma processing apparatus100according to the present exemplary embodiment, by disposing the protection member22made of the mesh material in the gap61, the consumption of the bonding layer20can be suppressed. It is deemed to be because a density of the radicals around the outer peripheral surface of the bonding layer20is reduced as the mesh material deactivates the radicals so that a pace of the consumption is decreased.

The protection member22is disposed in the gap61in a compressed state. Accordingly, diameters of the multiple number of pores in the protection member22are reduced, so that the deactivation of the radicals is accelerated. Therefore, the consumption of the bonding layer20can be suppressed more efficiently.

[Assembly Sequence of Susceptor]

Now, an assembly sequence of the susceptor2according to the present exemplary embodiment will be explained. First, the base10and the electrostatic chuck9are bonded by the bonding layer20. Then, the protection member22capable of deactivating the radicals and having the gas permeability is disposed in the space (for example, in the gap61shown inFIG. 2) which the outer peripheral surface of the bonding layer20faces. Then, the assembly of the susceptor2shown inFIG. 2is completed. Here, the process of placing the protection member22in the space which the outer peripheral surface of the bonding layer20faces is an example of a protection method of protecting the bonding layer20.

As stated above, since the plasma processing apparatus100according to the present exemplary embodiment has the labyrinth path, the protection member22is disposed in the gap61which is an end of the labyrinth structure or a vicinity thereof. Accordingly, the radicals passing through the labyrinth path can be deactivated efficiently. Here, however, even if the plasma processing apparatus100does not have the labyrinth path, the radicals can still be deactivated by disposing the protection member22in the space which the outer peripheral surface of the bonding layer20faces.

Further, in case that the protection member22does not have the gas permeability, like the O-ring, the protection member22may be protruded from the gap61if a gas existing between the protection member22and the bonding layer20is sucked in by the evacuation of the processing chamber1. Thus, it is desirable that the protection member22has the gas permeability to allow the gas existing between the protection member22and to bonding layer20to pass therethrough. In this way, the problem in which the protection member22is protruded from the gap61is avoided, so that the plasma can be suppressed from entering the gap61and reaching the outer peripheral surface of the bonding layer20.

In addition, it is desirable that the protection member22has elasticity so that it extends and contracts in a direction in which the thermal expansion or the thermal contraction of the base10and the electrostatic chuck9is absorbed. Accordingly, the problem, in which the protection member22is protruded from the gap61as the load of the thermal expansion or the thermal contraction of the base10and the electrostatic chuck9is applied to the protection member22, can be avoided, so that the plasma can be suppressed from entering the gap61and reaching the outer peripheral surface of the bonding layer20.

The plasma processing apparatus100according to the present exemplary embodiment as described above includes the base10; the electrostatic chuck9which is disposed on the base10and on which the wafer W as the plasma processing target is placed; the bonding layer20configured to bond the electrostatic chuck9and the base10; and the protection member22. The protection member22is disposed in the gap61, and is formed to be capable of deactivating the radicals while having the gas permeability. Accordingly, in the plasma processing apparatus100, the consumption of the bonding layer20by the plasma can be suppressed. As a result, in the plasma processing apparatus100, the work of the maintenance of the bonding layer20can be reduced, so that the maintenance cost of the plasma processing apparatus100can be reduced. Furthermore, in the plasma processing apparatus100, the downtime during which the plasma processing cannot be performed is also reduced, so that the deterioration of the productivity can be suppressed.

Furthermore, it should be noted that the above-described exemplary embodiments are illustrative in all aspects and are not anyway limiting. The above-described exemplary embodiments may be omitted, replaced and modified in various ways without departing from the scope and the spirit of claims.

By way of example, if a gap which the bonding layer20faces exists between the central portion10bof the base10and the electrostatic chuck9, the protection member22may be disposed in this gap.FIG. 4is a diagram illustrating an example where the protection member22is disposed in a gap between the base10and the electrostatic chuck9. The outer peripheral surface of the bonding layer20shown inFIG. 4is located at an inner position than the outer peripheral surface of the electrostatic chuck9in a radial direction. As a result, the gap which the bonding layer20faces is formed between the central portion10bof the base10and the electrostatic chuck9. The protection member22is disposed in this gap, between the central portion10bof the base10and the electrostatic chuck9, which the bonding layer20faces.

Further, even if the protruding portion10cdoes not exist at the peripheral portion of the base10, the protection member22can still be disposed in the gap, between the base10and the electrostatic chuck9, which the bonding layer20faces.FIG. 5is a diagram illustrating another example where the protection member22is disposed in the gap between the base10and the electrostatic chuck9. The outer peripheral surface of the bonding layer20shown inFIG. 5is located at an inner position than the outer peripheral surface of the electrostatic chuck9in the radial direction. Thus, the gap which the bonding layer20faces is formed between the base10and the electrostatic chuck9. Further, the base10shown inFIG. 5has a disk shape with the flat top surface, and the electrostatic chuck9is disposed on the central portion of the top surface of the base10and the edge ring21is disposed on the peripheral portion of the top surface of the base10. That is, the base10does not have the protruding portion10c(seeFIG. 2andFIG. 4) at the peripheral portion thereof. Even in this case, the protection member22is disposed in the gap, between the base10and the electrostatic chuck9, which the bonding layer20faces.

According to the present disclosure, consumption of the bonding layer by plasma can be suppressed.