JP2000286239A - Plasma surface treating apparatus for semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption, and to reduce generation of noise when carrying out the surface treatment of a semiconductor substrate which is placed on the upper face of a lower electrode disc with plasma in a chamber. SOLUTION: In this processor, a lower electrode disc 5 is constituted of a metal electrode body 7 with high thermal conductivity positioned on the uppermost face, a heating body 9 incorporating a heater 8, and an insulator 10 with high thermal conductivity interposed between them. High frequency is impressed via conductor wiring 23 put through the insulator to the electrode body 7, and the lower electrode disc 5 is supported by a support body 11 fixed to the lower face of the heating body 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma surface treatment apparatus for performing a surface treatment, such as forming or etching various coatings, on a semiconductor substrate such as a silicon wafer by plasma. is there.

[0002]

2. Description of the Related Art In general, a plasma surface treatment apparatus of this type includes a lower electrode plate with a heater disposed at a lower portion in a chamber into which a processing gas is injected, and an upper electrode plate disposed at an upper portion in the same chamber. By applying a high frequency to the semiconductor substrate mounted on the upper surface of the lower electrode plate while heating it to a temperature of about 400 ° C., plasma is generated by a processing gas during this time, or the lower electrode plate is While the semiconductor substrate mounted on the upper surface is heated to a temperature of about 400 ° C., a high-frequency current is applied to the lower electrode board, and at the same time, the semiconductor substrate is ejected from the microwave emission means disposed in the upper part of the chamber. By doing so, plasma is generated in the meantime, and the surface of the semiconductor substrate is subjected to surface treatment such as formation of a film or etching with the plasma. Than it is.

In this case, in the conventional plasma surface treatment apparatus, the lower electrode board is entirely made of aluminum, and a hollow support whose lower end is closed by aluminum is formed on the lower surface thereof so as to extend downward. The support is attached to the upper surface of the bottom plate in the chamber by sandwiching an insulating heat insulating member such as a ceramic so that the lower end of the support is exposed outside the chamber. While supporting the lower electrode board,
A structure in which high-frequency wiring for the lower electrode panel, electric wiring for the heater, and thermometer wiring are connected to a portion of the support that is exposed outside the chamber, and a lower end of the support is projected outside the chamber. A metal bellows which is insulated and insulated from the elevating mechanism so that the lower end of the support is exposed to the lower surface of the elevating mechanism, and which is fitted on the support and configured to be stretchable. Is provided with one end fixed to the chamber and the other end fixed to the support, so that the lower electrode plate can be brought closer to the upper electrode plate or the microwave emission means above the lower electrode plate while keeping the chamber airtight. In addition, high-frequency wiring for the lower electrode panel, electrical wiring for the heater, and the like are provided on the portion of the support that is exposed from the lifting mechanism. And a configuration of connecting a thermometer wirings.

The reason why the lower electrode plate and its support are made of aluminum is that aluminum has excellent heat transfer and can reduce uneven heating of the semiconductor substrate on the upper surface of the lower electrode plate. This is because these are sufficiently resistant to corrosion by plasma, and even if corrosion occurs, this does not adversely affect the surface treatment of the moving substrate, and the lower electrode board is configured to be vertically movable. The reason is to facilitate the work of supplying the semiconductor substrate to the upper surface of the lower electrode plate and taking out the processed semiconductor substrate from the upper surface of the lower electrode plate, and between the upper electrode plate or the microwave emitting means. This is because the gap can be set to an optimum state according to various surface treatments.

[0005]

However, in the conventional plasma surface treatment apparatus, in addition to making the lower electrode board made of aluminum, the support is also made of aluminum, and the support is made of the lower part. Since it is configured to be fixed to the electrode board by welding or the like, the high frequency applied to the lower electrode board reaches the support body and generates plasma in this portion, so that power consumption is reduced. Not only does it increase, it also causes the plasma to be unstable with respect to the surface of the semiconductor substrate.
Since the high frequency extends to the support, noise due to the high frequency is generated in electric wiring to the heater disposed inside the support. There was a problem that a filter for erasing had to be provided.

Further, since the support is made of aluminum having a high thermal conductivity similarly to the lower electrode board, the entire body is at substantially the same high temperature as the lower electrode board. The part that attaches to the bottom surface of the chamber and the part that attaches this support to the elevating mechanism must sandwich an insulating heat insulating member such as ceramic between them. There is also a problem that a seal body such as a gasket sandwiched between the seals is deteriorated at an early stage due to the heat described above, or adheres to a seal surface and becomes inseparable.

An object of the present invention is to provide a plasma surface treatment apparatus which solves these problems.

[0008]

In order to achieve this technical object, the present invention provides a chamber, a lower electrode board with a heater disposed in a lower part of the chamber, and a lower electrode board with a heater disposed in an upper part of the chamber. In the plasma surface treatment apparatus comprising an upper electrode plate or microwave emitting means and a support extending downward from the lower electrode plate, the lower electrode plate is made of a high thermal conductivity metal electrode body located on the uppermost surface. ,
A heating element having the built-in heating heater, and an insulator having a high thermal conductivity sandwiched therebetween, and applying high frequency to the electrode body via a conductor wiring penetrating the insulator;
The support is fixed to the lower surface of the heating body. ".

[0009]

Operation and effect of the present invention As described above, by interposing an insulator having a high thermal conductivity between an electrode body made of a metal having a high thermal conductivity and a heating body having a built-in heater, the heating element can be connected to the electrode body. In a state in which the heat transfer is good, the insulator can reliably prevent the high frequency applied to the electrode body from reaching the heating body and the support body, so that the power consumption can be surely reduced. In addition, it is possible to stabilize the plasma on the semiconductor substrate and to prevent generation of noise due to high frequency in electric wiring to the heater.

In addition, since the support is separated from the electrode body, it is necessary to make the support from aluminum in consideration of the relationship with the lower electrode board and corrosion by plasma as in the conventional case. In other words, in other words, regardless of the electrode plate required to have high thermal conductivity and plasma resistance, for example, a metal having a much lower thermal conductivity than aluminum, such as stainless steel or other non-rusting steel, is used. Therefore, the temperature of the mounting portion of the support with respect to the chamber or the elevating mechanism can be made lower than in the conventional case, and the durability of the seal body such as a gasket can be improved, and the seal body can be formed. Adhesion to the sealing surface can be reduced.

As described above, when the lower electrode board is constituted by the electrode body located on the uppermost surface, the heating body having a built-in heating heater, and the insulator having a high thermal conductivity interposed therebetween, the heating is not performed. In order to ensure better heat transfer from the body to the electrode body, the adhesion between the heating body and the insulator, and the adhesion between the insulator and the electrode body must be improved. Must be configured so that both the electrode body and the insulator and between the insulator and the heating body are fastened with a plurality of bolts.

However, in the case where both the electrode body and the insulator and between the insulator and the heating body are fastened with a plurality of bolts as described above, the connection between the three members is limited. Due to the difference in thermal expansion, warping deformation occurs in the electrode body, and as a result, processing unevenness occurs on the surface of the semiconductor substrate mounted on the upper surface thereof.

On the other hand, according to the present invention, as described in claim 2, both the electrode body and the heating body are loosely fitted in bolt holes formed therein and screwed to the insulator. It is proposed to provide a configuration in which each of the bolts is provided with a spring means for pressing the electrode body and the heating body against the insulator therebetween.

With this arrangement, the electrode body, the insulator, and the heating element are securely brought into close contact with each other by the spring means. The difference in thermal expansion can be absorbed by the gap between each bolt and the bolt hole in which it is loosely fitted, so that better heat transfer from the heating plate to the electrode plate can be ensured, It is possible to reliably reduce the occurrence of warpage of the electrode body, and hence the occurrence of processing unevenness on the surface of the semiconductor substrate placed on the upper surface thereof.

In addition, since the support and the electrode body are separated from each other by an insulator, plasma is basically not generated at the support, but the semiconductor substrate is provided at the support. When the plasma on the upper surface flows, there is a possibility that the support is corroded by the plasma.

On the other hand, according to the present invention, a perforated plate made of a corrosion-resistant metal plate having a large number of small holes is provided on the outside of the lower electrode board. It is proposed to arrange it so as to surround the entire circumference.

Thus, the plasma on the upper surface of the electrode body is neutralized when coming into contact with the perforated plate while flowing toward the gas outlet provided below the electrode body. When the support is made of a metal having much lower thermal conductivity and plasma resistance than aluminum, such as stainless steel or carbon steel, it is possible to reliably reduce the occurrence of corrosion by plasma in this, In other words, the support can be made of a metal having a low thermal conductivity, in a state where the occurrence of corrosion due to plasma can be reliably reduced.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment.

In FIG. 1, reference numeral 1 denotes a chamber having a processing gas outlet 3 at a lower portion thereof.
In the lower part, a lower electrode board 5 on which a semiconductor substrate 4 which is an object to be processed is mounted on the upper surface is provided, and an upper electrode board 6 is provided on the upper part thereof, and the upper electrode board 6 is hollow. so,
The processing gas supplied from the pipe 2 is jetted downward into the inside thereof, and a high frequency is applied to the lower electrode plate 5 and the upper electrode plate 6 so that the processing gas plasma is applied between the two electrode plates. Is generated, a surface treatment such as formation of a film or etching on the surface of the semiconductor substrate 4 is performed with the plasma. However, the upper electrode board 6 is attached to the chamber 1 via an insulator 35.

As shown in FIGS. 2 and 3, the lower electrode board 5 is provided with an electrode body 7 located on the uppermost surface, a heater 9 having the heater 8 built therein, and an insulator sandwiched therebetween. 10, the electrode body 7 is, for example,
The heating element 9 is made of, for example, a metal having corrosion resistance to plasma and high thermal conductivity such as aluminum or the like, and is made of non-rusting steel such as stainless steel.
Is made of an insulating material having a high thermal conductivity, such as a ceramic using aluminum nitride as a main raw material, that is, an aluminum nitride (AlN) ceramic or the like.

A hollow pipe-shaped support 11 protruding downward is integrally fixed to the lower surface of the heating body 9 by welding or the like, and a flange portion 12 integrally provided on the outer periphery of the lower end of the support 11 is provided. , Bottom plate 1a in the chamber 1
The lower electrode board 5 is supported on the chamber 1 by being mounted on the upper surface of the device with an insulating insulating member 40 such as an insulating ceramic interposed therebetween.

In this case, O-rings 13 for sealing are provided both between the flange portion 12 and the heat insulating member 40 and between the heat insulating member 40 and the bottom plate 1a. The airtightness is maintained, and the inside of the support 11 is opened to the atmosphere through an opening 14 formed in the bottom plate 1a.

The electrode body 7 is loosely fitted at a plurality of locations on the circumference of the electrode body 7 into a bolt hole 15 formed therein and screwed into a female screw hole 16 formed in the insulator 10. Bolts 17 are provided.
Is provided so that the electrode body 7 and the insulator 10 are in close contact with each other by the spring force of the disc spring 18, while the heating body 9 is provided at a plurality of locations on the circumference thereof.
By providing a bolt 21 which is loosely fitted in a bolt hole 19 formed in this hole and is screwed into a female screw hole 20 formed in the insulator 10, and a disc spring 22 is provided in each of the bolts 21, The heating element 9 and the insulator 10 are connected to the disc spring 2
The two springs are configured to be in close contact with each other.

Furthermore, a power supply terminal 23 and a pipe-shaped temperature detector 24 made of a heat-resistant insulating material such as aluminum nitride (AlN) ceramic are provided inside the support 11 and these are connected to each other. A connection hole that is fixed to the heating element 9 with sealing materials 25 and 26 that are both heat-insulating and insulating, and that the upper end of the power supply terminal 23 penetrates through the insulator 10 and is drilled in the lower surface of the electrode body 7. 27, which is removably inserted into the inside 27, and is inserted into the small screw 28 from the upper surface of the electrode body 7.
To electrically connect to the electrode body 7 and apply a high frequency to the electrode body 7 via the power supply terminal 23, while the temperature detector 24 After penetrating the insulator 10, the upper end is removably inserted into a connection hole 29 formed in the lower surface of the electrode body 7, and then is fastened to this with a small screw 30 inserted from the upper surface of the electrode body 7. Thereby, the temperature detector 24 is fixed to the electrode body 7, the thermocouple 31 is inserted into the temperature detector 24, and the temperature at the electrode body 7 is measured. Although not shown, electrical wiring to the heater 8 is also provided inside the body 11.

As described above, the lower electrode board 5 has a three-layer structure of the uppermost electrode body 7, the heating body 9 with the heater 8, and the insulator 10 interposed therebetween. Since the aluminum nitride (AlN) ceramic is made of aluminum nitride (AlN) ceramic, the aluminum nitride (AlN) ceramic has a high heat transfer coefficient close to that of aluminum while having high electrical insulation. The insulator 10 can reliably prevent the high frequency applied to the electrode body 7 from reaching the heating body 7 and the support body 11 in a state where the heat transfer is improved.

Further, since the support 11 is separated from the electrode body 7, the support 11 is made of a metal having a high heat transfer coefficient such as aluminum in relation to the lower electrode board as in the prior art. In other words, the support 11 is made of a material having a much higher thermal conductivity than aluminum, such as stainless steel or other non-rusting steel, regardless of the electrode plate 7 requiring high thermal conductivity. Therefore, the temperature of the mounting portion of the support 11 to the chamber 1 can be made lower than in the conventional case.

Further, the electrode body 7 and the insulator 10, and the insulator 10 and the heater 9 are connected to each bolt 1
Under the condition that the springs of the disc springs 18 and 22 provided on the electrodes 7 and 21 are securely in contact with each other, the difference in thermal expansion between the three members of the electrode body 7, the insulator 10 and the heating body 9 is calculated as follows. Since the bolts 17 and 21 and the bolt holes 15 and 19 into which the bolts 17 and 21 are loosely fitted can be absorbed by a gap, better heat transfer from the heating plate 9 to the electrode plate 7 can be ensured. In spite of this, the occurrence of warpage of the electrode body 7 can be reliably reduced.

In addition, on the outer side of the lower electrode plate 5, a perforated plate 32 formed by drilling a large number of small holes in an aluminum plate is arranged so as to surround the entire periphery of the lower electrode plate 5. This is supported in a state of being electrically connected to one or both of the electrode body 7 and the heating body 9 by the ring bodies 33 and 34.

This makes it possible for the plasma on the upper surface of the electrode body 7 to be neutralized when coming into contact with the perforated body 32 while flowing toward the processing gas outlet 3 provided below the same. The support 1
When 1 is made of a metal having much lower thermal conductivity than aluminum, such as stainless steel or carbon steel, it is possible to reliably reduce the occurrence of plasma-induced corrosion in this.

The upper end of a power supply terminal 23 for applying a high frequency to the electrode body 7 is removably inserted into a connection hole 27 formed in the electrode body 7 and fastened with small screws 28. With such a configuration, the electrical connection of the power supply terminal 23 to the electrode body 7 can be reliably performed in a small space, and the upper end of the temperature detector 24 is further connected to the electrode body 7. Is inserted into a connection hole 29 formed in the lower surface of the device, and is fastened with a small screw 30, and a thermocouple 31 is inserted into the temperature detector 24. To
The detection by the thermocouple 31 can be performed accurately while maintaining the vacuum and maintaining the electrical insulation.

In addition, the support 11 is made hollow,
By opening this inside to the atmosphere, this support 1
In the case where the conductor wiring 23 and the electric wiring to the heater 8 are provided in the inside of the device 1, the occurrence of a discharge phenomenon during this can be reduced.

Next, FIG. 4 shows a second embodiment.

In the second embodiment, the support 11 projecting downward from the lower surface of the lower electrode board 5 having a three-layer structure of the electrode body 7, the insulator 10, and the heater 9 is attached to the bottom plate 1a in the chamber 1. It penetrates and projects downward, and this projecting end is attached to an elevating body 37 that is guided up and down by a guide shaft 36 so as to move up and down by a cylinder 38, while the support body 11 is fitted. A metal bellows 39 which is configured to be expandable and contractable is provided with one end fixed to the chamber 1 and the other end fixed to the support body 11 so as to maintain airtightness in the chamber 1. The configuration is
This is the same as in the first embodiment.

That is, the present invention can be applied to a plasma surface treatment apparatus of a type in which the lower electrode body 5 is moved up and down from outside the chamber 1.

The spring means in each of the bolts 17 and 21 is not limited to the disc springs 18 and 23 in the above embodiment, but may be other spring means such as a spring washer or a coil spring. Further, the present invention is not limited to the above-described embodiment, in which the upper electrode plate 6 is disposed above the lower electrode plate 5 and plasma is generated between the two electrodes. At the top of 5, for example,
It is also applicable to a type in which a microwave emitting means such as a radial line slot antenna is arranged and a plasma is generated between the lower electrode board 5 by ejecting the microwave downward. Of course.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing a first embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional front view showing a main part (lower electrode panel) of FIG.

FIG. 3 is a view showing a disassembled state of FIG. 2;

FIG. 4 is a longitudinal sectional front view showing a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chamber 5 Lower electrode board 6 Upper electrode board 7 Electrode body 8 Heater 9 Heating body 10 Insulator 11 Support body 15, 19 Bolt hole 17, 21 Bolt 18, 22 Disc spring 23 Conductor wiring 24 Temperature detector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/302 C F term (Reference) 4K030 CA04 FA02 KA12 KA14 KA17 KA46 4K057 DA20 DM01 DM02 DM06 DM09 DM29 DN01 5F004 AA00 BA04 BA06 BA11 BB18 BB26 BB29 BC08 5F045 DP01 DP02 DP03 DQ10 EB03 EF05 EF20 EH04 EH08 EH12 EH13 EH14 EK07 EM02

Claims (3)

[Claims] 1. A chamber, a lower electrode plate with a heater disposed in a lower portion of the chamber, an upper electrode plate or microwave emitting means disposed in an upper portion of the chamber, and a downwardly directed electrode from the lower electrode plate. A lower surface of the lower electrode plate, an electrode body made of a metal having a high thermal conductivity located on the uppermost surface, a heating body having the built-in heater, and a high heat conduction sandwiched therebetween. A high-frequency insulator applied to the electrode body through a conductor wiring penetrating the insulator, while the support is fixed to the lower surface of the heater. For plasma surface treatment equipment. 2. The apparatus according to claim 1, wherein each of said electrode body and said heating body is provided with a plurality of bolts which are loosely fitted in bolt holes formed therein and screwed to said insulator. A plasma surface treatment apparatus for a semiconductor substrate, wherein a bolt is provided with spring means for pressing an electrode body and a heating body against an insulator therebetween. 3. A perforated plate made of a corrosion-resistant metal plate having a large number of small holes formed outside the lower electrode board, as defined in claim 1. A plasma surface treatment apparatus for a semiconductor substrate, characterized in that: