JPH07106096A - Plasma processing device - Google Patents

Abstract

PURPOSE:To prevent the generation of peeling of a protecting layer of a high frequency antenna and the generation of crack of an insulating material to be loaded with the high frequency antenna at the time of generating plasma at a low voltage with a high frequency antenna to perform the plasma processing. CONSTITUTION:The outer peripheral surface of a high frequency antenna 6 made of spiral coil is coated with a protecting layer 60 made of corrosion-proof material, and the high frequency antenna 6 is placed on a cooling plate 7 made of, for example, ceramics inside of a chamber 2 having the air-tight structure. When high frequency power is applied to the high frequency antenna 6, heat is generated, but the antenna 6 is cooled by, for example, the cooling water through the cooling plate 7 to restrict the temperature rise thereof. Thermal stress generated in the interface between the antenna 6 and the protecting layer 60 is thereby restricted small to prevent the generation of peeling of the protecting layer 60.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a plasma processing apparatus.

[0002]

2. Description of the Related Art In the process of processing a semiconductor wafer, dry etching is carried out, for example, for the purpose of separating capacitors and elements or forming contact holes.
A parallel plate type plasma processing apparatus is known as a typical one of the conventional apparatuses for performing this dry etching.

FIG. 8 is a view showing a parallel plate type plasma processing apparatus. A mounting table 11 which also serves as a lower electrode is arranged in an airtight chamber 1, and a mounting table 11 is arranged above the mounting table 11 and faces it. The upper electrode 12 also serving as a gas supply unit is provided. Reference numeral 13 is an exhaust pipe.

In such a plasma processing apparatus,
First, the wafer W is mounted on the mounting table 11, and the gas supply unit 12
A process gas is introduced from the inside of the wafer W, and high-frequency power is applied between the electrodes 11 and 12 by the high-frequency power source E to generate plasma.
Etching is performed.

By the way, although the line width of the device pattern tends to become finer and finer, the pressure in the chamber when plasma is generated in the above-mentioned apparatus is 100 mTo.
It is rr to 1 Torr, and at such a high pressure, the mean free path of the ions is small, so that fine processing is difficult.
Further, although the diameter of the wafer is increasing, it is difficult to perform uniform processing on a large-diameter wafer because it is not possible to secure high uniformity of plasma distribution over a wide surface if the mean free path of ions is small. There are also problems.

Therefore, recently, as described in European Patent Publication No. 379828 and Japanese Patent Laid-Open No. 3-79025, the upper surface of the chamber 1 facing the mounting table 11 is made of an insulating material such as quartz glass. Along with
A planar coil is fixed to the outside of this insulating material, a high-frequency current is passed through this coil to form an electromagnetic field in the chamber 1, and electrons flowing in this electromagnetic field collide with neutral particles of the processing gas to generate plasma. A high frequency induction method for generating is under consideration.

According to this method, a substantially concentric circular electric field is induced according to the shape of the coil, and there is a plasma confinement effect, so that plasma is generated at a pressure considerably lower than that in the case of the conventional parallel plate type plasma processing apparatus. Therefore, the mean free path of the ions in the generated plasma is large, and thus the etching process using this plasma is suitable for microfabrication. Then, the plasma diffuses from the high density region to the low density region, but since the mean free path of the ions is large, the plasma density distribution is smooth, and the uniformity of the plasma in the plane parallel to the wafer plane is high,
The in-plane uniformity of plasma processing on a large-diameter wafer is improved.

[0008]

As described above, the high frequency induction method is noted as being suitable for the miniaturization of the line width of the pattern and the enlargement of the diameter of the wafer. There is a problem. For example, when a high frequency antenna is provided outside the chamber, it is necessary to shield the entire antenna in order to prevent radio interference, which increases the size and complexity of the device. Therefore, the present inventor is considering providing the antenna in the chamber, but if the antenna is stored in the chamber as it is, the antenna is corroded by the processing gas.

One of the measures to prevent the corrosion of the antenna is to coat the antenna with a corrosion resistant material. However, when high frequency power is applied to the antenna, it generates heat,
For example, the temperature is raised to about 100 ° C. When the antenna generates heat in this way, a large thermal stress is applied to the interface between the antenna and the coating material on the outer peripheral surface thereof due to the difference in thermal expansion coefficient, and the coating material may be peeled off.
If the coating material is peeled off, it may become particles and adhere to the wafer. Therefore, it becomes necessary to frequently replace the antenna.

The heat generation of the antenna also causes another problem when the antenna is provided outside the chamber. That is, the portion of the upper surface of the chamber where the antenna is arranged is made of an insulating material such as quartz.Since quartz has a low thermal conductivity, the portion in contact with the antenna is higher than other portions at the beginning of heat generation of the antenna. Since it heats up, a large thermal stress is generated, which causes a crack in the quartz, which may cause a serious accident by breaking the quartz.

The present invention has been made under the circumstances as described above, and an object thereof is to provide a high-frequency device for processing an object to be processed with plasma obtained by applying high-frequency power to a high-frequency antenna composed of a coil. When the antenna is provided in the chamber, it is intended to prolong the service life of the protective layer and the container that protect the high frequency antenna.

Another object of the present invention is to prevent damage to an insulator forming a part of the chamber facing the high frequency antenna when the high frequency antenna is provided outside the chamber.

[0013]

According to a first aspect of the present invention, a mounting table is provided in a chamber having an airtight structure, a processing gas is introduced into the chamber to generate plasma, and the object to be processed on the mounting table is generated by the plasma. In the plasma processing apparatus for processing the above, in order to apply a high frequency power to the high frequency antenna and a high frequency antenna which is provided in the chamber facing the mounting table and is composed of a planar coil whose outer peripheral surface is coated with a corrosion resistant material. And a cooling means for cooling the high frequency antenna.

According to a second aspect of the present invention, a mounting table is provided in a chamber having an airtight structure, a processing gas is introduced into the chamber to generate plasma, and the plasma is used to process an object to be processed on the mounting table. In, a high-frequency antenna consisting of a planar coil provided in the chamber facing the mounting table, and surrounding the high-frequency antenna,
An airtight container made of a corrosion-resistant material and at least a portion facing the mounting table is an insulating material, a high-frequency power supply unit for applying high-frequency power to the high-frequency antenna, and a cooling for cooling the high-frequency antenna. A plasma processing apparatus comprising:

According to a third aspect of the present invention, there is provided a plasma processing apparatus in which a mounting table is provided in a chamber having an airtight structure, a processing gas is introduced into the chamber to generate plasma, and the object to be processed on the mounting table is processed by the plasma. A high-frequency antenna composed of a planar coil provided outside the chamber so as to face the mounting table; an insulator that constitutes a wall of the chamber and is provided so as to face the high-frequency antenna; A high-frequency power supply unit for applying high-frequency power to the antenna, and a cooling means for cooling the high-frequency antenna are provided.

[0016]

According to the first aspect of the present invention, when the high frequency antenna is provided in the chamber, when the high frequency power is applied to the high frequency antenna, the high frequency antenna generates heat. However, since it is cooled by the cooling means, the high frequency antenna and the outer peripheral surface thereof. Since the thermal stress at the interface with the protective layer is suppressed, the protective layer can be prevented from peeling off, and in the case of the second aspect of the invention, the container accommodating the high frequency antenna can be prevented from cracking.

According to the third aspect of the invention, when the high frequency antenna is provided outside the chamber, it is cooled by the cooling means, so that the high frequency antenna is provided in the insulator which is a part of the chamber in which the high frequency antenna is mounted. The temperature rise of the part in contact with is suppressed and the insulator can be prevented from cracking.

[0018]

1 and 2 are a sectional view and a partially exploded perspective view showing a general structure of a plasma processing apparatus such as an etching apparatus according to an embodiment of the present invention. 2 in the figure
Is a chamber having an airtight structure made of, for example, aluminum except for a part of the upper surface thereof, and a mounting table 3 made of, for example, aluminum is arranged at the center bottom portion of the chamber 2.

The mounting table 3 is the mounting portion 3 which is the upper side portion.
1 and a support portion 32, which is a lower portion supporting the mounting portion 31, are separably coupled by a bolt 33, and an insulator 34 is provided between the support portion 32 and the chamber 2.
Is installed. The electrostatic chuck sheet 4 is provided on the upper surface of the placing unit 31 so as to cover the upper surface.
The electrostatic chuck sheet 4 is formed by coating a conductive film 41, which is an electrode for an electrostatic chuck sheet, made of, for example, a copper foil, with an insulating film 42 made of, for example, a polyimide film, from both sides. Is electrically connected to the external DC power source 43 via a switch 44.

The upper end of the placing part 31 is the placing part 3 concerned.
1. Holes 51 for a plurality of backside gases (gases for heat conduction) that open on the upper surface of 1 are formed, and the lower ends of these holes 51 are, for example, through a ventilation chamber 52 and are used for backside gas. It communicates with the gas supply passage 53. Also, holes (not shown) are formed in the electrostatic chuck sheet 4 at positions corresponding to the holes 51, and backside gas from the holes 51 is transferred to the back surface of the wafer W through the holes of the electrostatic chuck sheet 4. It is designed to be sprayed. The gas supply passage 53 is connected to a gas supply source such as He gas (not shown) via a pressure regulator 54 such as a butterfly valve.

A pressure detector 55 for detecting the pressure of the backside gas is provided in the ventilation chamber 52, and the controller 56 included in the control system of the device of the present invention is based on the pressure detection value of the pressure detector 55. It has a function of adjusting the opening of the pressure regulator 54, for example, the butterfly valve, so that the pressure of the backside gas blown out from the hole 51 toward the back surface of the wafer W becomes a predetermined value, for example, 10 Torr.

An annular focus ring 21 that surrounds the wafer W is disposed on the placing portion 31. The focus ring 21 is made of an insulating material that does not attract reactive ions, and has a role of effectively attracting the reactive ions to the inner wafer W.

A coolant reservoir 35 for circulating a cooling medium for cooling the wafer W via the mounting table 3 is formed inside the support portion 32, and an inlet pipe 36A and an exhaust pipe 36B are formed therein. The cooling medium, such as liquid nitrogen, which is provided and supplied into the refrigerant reservoir 35 through the introduction pipe 36A is discharged to the outside of the apparatus through the discharge pipe 36B.

A high-frequency antenna 6 composed of a planar coil, for example, a spiral coil, is provided near the upper surface of the chamber 2 so as to face the mounting table 2. The high frequency antenna 6 is made of a conductive material such as aluminum, and its outer peripheral surface is covered with a protective layer 60 made of a corrosion resistant material such as aluminum oxide in order to prevent corrosion by the processing gas. As the corrosion resistant material, for example, fluororesin or ceramic may be used. Between both terminals (inner terminal and outer terminal) of the high frequency antenna 6, a high frequency power supply unit 61 for plasma generation is provided.
More via the matching circuit 62, for example 13.56MH
A high frequency voltage of z, 1 kw is applied. As a result, a high frequency power is supplied to the antenna 6 and the antenna 6
Plasma is generated in the space directly below.

On the lower surface side of the high frequency antenna 6, a cooling means for supporting and cooling the high frequency antenna 6, for example, a cooling plate 7 is provided. As shown in FIG. 2, the cooling plate 7 is attached to the chamber 2 via an attaching member 70 and is made of an insulating material such as ceramic and has a hollow plate body 71.
And a cooling medium pipe 72 made of an insulating material, for example, plastic, provided inside the plate body 71, and cooling water such as pure water flows from the outside of the chamber 2 to the cooling medium pipe 72.

Further, between the mounting table 3 and the ground, in order to apply a bias voltage having a frequency lower than the frequency of the high frequency voltage applied to the high frequency antenna 6 to the mounting table 3, for example, 400 KHz, the high frequency power supply section 22 is provided. Are connected. The chamber 2 is connected to the ground, so that an electric field is formed between the mounting table 3 and the chamber 2,
As a result, the perpendicularity of the reactive ions in the plasma in the chamber 2 to the wafer W is increased.

A gas supply pipe 2 having a temperature adjusting means 23a for adjusting the processing gas to a predetermined temperature, which is formed by combining a heating means and a cooling means on the upper side surface of the chamber 2.
3 is connected. The processing gas supplied from the gas supply pipe 23 into the chamber 2 varies depending on the type of processing. For example, in the case of etching processing, CHF ₃ or CF _{4 is used.}
Etching gas such as is supplied. Although only one gas supply pipe 23 is shown in the illustrated example, an appropriate number of gas supply pipes may be connected to the chamber 2 in order to allow the processing gas to flow uniformly.

On the bottom surface of the chamber 2, one ends of a plurality of exhaust pipes 24 are connected to the chamber 2 at equidistant positions in the circumferential direction. In the illustrated example, one ends of the two exhaust pipes 24 are symmetrically connected to the axis of the chamber 2. The other ends of the exhaust pipes 24 are connected to a common exhaust pipe 27 in which a pressure regulator 25 such as a butterfly valve and a vacuum pump 26 are interposed as shown in FIG. Further, in this embodiment, the exhaust system is provided with a pressure detecting portion provided in the chamber 2 so that the exhaust gas is gently exhausted at the initial stage of evacuation so that the particles are not wound up, and is exhausted rapidly after evacuation to some extent. The exhaust controller 29 is configured to adjust the pressure adjuster 25 based on the pressure detection value from 28.

Next, the operation of the above embodiment will be described.
First, an object to be processed, for example, a wafer W is loaded into the chamber 2 by a transfer arm (not shown) and placed on the electrostatic chuck sheet 4. Then, the vacuum pump 26 evacuates to a predetermined vacuum atmosphere via the exhaust pipe 24, and the gas supply pipe 23 supplies an etching gas such as CF ₄ gas into the chamber 2 to evacuate the exhaust pipe 24. Inside the chamber 2 by, for example, several mTorr to several tens mTorr.
While maintaining the degree of vacuum at r, a high frequency voltage is applied to the high frequency antenna 6 from the high frequency power supply unit 61. When a high-frequency current flows through the high-frequency antenna 6 by applying this high-frequency voltage, an alternating magnetic field is generated around the antenna conductor, and most of the magnetic flux passes through the center of the antenna in the vertical direction to form a closed loop. Such an alternating magnetic field induces an approximately concentric circular alternating electric field immediately below the antenna 6, and the electrons accelerated in the circumferential direction by the alternating electric field collide with neutral particles of the processing gas to generate gas. Is ionized to generate plasma. The surface of the wafer W is etched by the reactive ions in the plasma thus generated.

The high-frequency antenna 6 generates heat when high-frequency power is applied, but the heat is absorbed by the cooling plate 7 in contact with the high-frequency antenna 6, and as a result, the temperature rise of the high-frequency antenna 6 is suppressed. Here, the high-frequency antenna 6 and the protective layer 20 such as an aluminum oxide layer on the outer peripheral surface have different coefficients of thermal expansion, but since the temperature of the antenna 6 does not rise so much, the thermal stress generated at the interface is small, and therefore the protective layer cracks. It is possible to prevent the peeling and the generation of particles due to the high frequency antenna provided in the chamber 2.

As described above, in the present invention, the cooling means for the high-frequency antenna is not limited to the cooling plate, and as shown in FIG. 3, the high-frequency antenna 6 is made of a corrosion-resistant material and an insulating material, such as ceramic, which is airtight. You may use the cooling means accommodated in the container 73 and configured so that a refrigerant gas, for example, an inert gas is made to flow therethrough by the refrigerant introduction pipe 71 and the refrigerant discharge pipe 75.

Further, when the high frequency antenna 6 is provided inside the chamber 2 as described above, the chamber 2 can be used also as a shield body of the high frequency antenna 6 as compared with the case where the high frequency antenna 6 is provided outside the chamber 2. Although it is an advantageous structure, in the present invention, as shown in FIG.
For example, the insulator 20 made of quartz or the like is formed over a region wider than the region facing the mounting table 3, and the same cooling plate 7 as described above is placed on the insulator 20 and further placed thereon. The high frequency antenna 6 may be mounted. In this case, for example, since quartz has low thermal conductivity, cracks may occur if a large temperature distribution occurs in the initial stage of heat generation of the high frequency antenna 6, but since the cooling plate 7 is interposed between the high frequency antenna 6 and The temperature rise of the surface on the side opposite to the chamber 2 is suppressed, so that the insulator such as quartz can be prevented from cracking and the rupture accident of the chamber 2 can be prevented.

Here, an example of the means for supplying the processing gas will be described with reference to FIGS.
Is a ring body having an inner diameter slightly larger than the outer diameter of the high-frequency antenna 6, and the ring body 8 is made of a tubular body and has a large number of gas blowing holes 81 on its lower surface side.
Are formed in the circumferential direction. An upper end of an L-shaped support pipe 82 is coupled to the ring body 8, and a lower end of the support pipe 82 penetrates through the bottom wall to the outside of the chamber 2 and is lifted and lowered by a lifting mechanism 83 outside the chamber 2. It is configured to be possible. A gas supply pipe 84 for processing gas is inserted into the support pipe 82, and the inner end of the gas supply pipe 84 is open to the internal space of the ring body 8. Therefore, the processing gas is blown out from the gas blowing hole 81 of the ring body 8. With this structure, the in-plane uniformity of the gas flow on the wafer surface can be improved and the height of the ring body 8 can be increased. Can be changed, so that there is an advantage that the gas flow on the surface of the wafer W can be adjusted. Further, in order to quickly exhaust the reaction product due to the etching, the gas blowing holes and the exhaust holes may be arranged alternately in the ring body 8, for example.

As a means for supplying the processing gas, as shown in FIG. 7, a cylindrical gas supply chamber 92 having a gas blowing hole 91 on the lower surface is provided at the upper part of the chamber 2 and the gas supply chamber is provided. Gas mixing chamber 9 communicating with 92
3 may be provided, and a plurality of (two in the illustrated example) gas supply pipes 94 may be connected to this gas mixing chamber 93, which makes it possible to mix the processing gas with high uniformity.

The cooling plate 7 may be provided on the upper surface side instead of the lower surface side of the high frequency antenna 6 to support the high frequency antenna 6 separately, or a Peltier element may be used. Good. Furthermore,
Although the example of the etching treatment has been described as the plasma treatment, the present invention can be applied to other plasma treatment apparatuses such as a plasma CVD apparatus, a plasma ashing apparatus, and a plasma sputtering apparatus, and a semiconductor wafer is used as an object to be treated. However, it may be an LCD substrate or the like.

[0036]

According to the first aspect of the present invention, when the high frequency antenna is provided in the chamber, when the high frequency power is applied to the high frequency antenna, the high frequency antenna generates heat.
Since this is cooled, the thermal stress at the interface between the high-frequency antenna and the protective layer on the outer peripheral surface of the high-frequency antenna is suppressed, so that the protective layer can be prevented from peeling, the high-frequency antenna has a long service life, and particles are suppressed from occurring. To be

According to the second aspect of the present invention, when the high frequency antenna is provided in the corrosion-resistant and insulating container and protected from the processing gas, the container accommodating the high frequency antenna can be prevented from cracking.

According to the third aspect of the invention, when the high frequency antenna is provided outside the chamber, it is cooled by the cooling means, so that the high frequency antenna is provided in the insulator which is a part of the chamber in which the high frequency antenna is mounted. The temperature rise of the part in contact with is suppressed, the crack of the insulator can be prevented, and the rupture accident of the chamber can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a schematic exploded perspective view showing the outline of the overall configuration of the embodiment of the present invention.

FIG. 3 is a schematic sectional view showing another embodiment of the present invention.

FIG. 4 is a sectional view showing a part of still another embodiment of the present invention.

FIG. 5 is a perspective view showing an example of a means for supplying a processing gas.

6 is a bottom view of the ring body for gas supply shown in FIG. 5. FIG.

FIG. 7 is a sectional view showing still another embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a conventional plasma processing apparatus.

[Explanation of symbols]

 2 chamber 23, 84 processing gas supply pipe 24 exhaust pipe 3 mounting table 4 electrostatic chuck sheet 53 backside gas gas supply path 6 high frequency antenna 61 high frequency power supply 60 protective layer 7 cooling plate 72 cooling medium pipe W semiconductor wafer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01Q 9/27

Claims (3)

[Claims] 1. A mounting table is provided in an airtight chamber,
In a plasma processing apparatus for introducing a processing gas into the chamber to generate plasma, and processing the object to be processed on the mounting table by the plasma, the plasma processing apparatus is provided in the chamber facing the mounting table, and the outer peripheral surface is made of a corrosion-resistant material. A high-frequency antenna composed of a planar coil covered with a protective layer, a high-frequency power supply unit for applying high-frequency power to the high-frequency antenna, and a cooling unit for cooling the high-frequency antenna. A plasma processing apparatus characterized by the above. 2. A mounting table is provided in an airtight chamber,
In a plasma processing apparatus for introducing a processing gas into the chamber to generate plasma, and processing the object to be processed on the mounting table by the plasma, a planar coil provided in the chamber facing the mounting table is used. And a high-frequency antenna surrounding the high-frequency antenna, which is made of a corrosion-resistant material,
And at least a portion facing the mounting table is an airtight container made of an insulating material, a high-frequency power supply unit for applying high-frequency power to the high-frequency antenna, and a cooling unit for cooling the high-frequency antenna. A plasma processing apparatus characterized by the following. 3. A mounting table is provided in an airtight chamber,
In a plasma processing apparatus for introducing a processing gas into the chamber to generate plasma, and processing the object to be processed on the mounting table by the plasma, a planar coil provided outside the chamber facing the mounting table. A high-frequency antenna including: a wall portion of the chamber; an insulator provided to face the high-frequency antenna; a high-frequency power supply unit for applying high-frequency power to the high-frequency antenna; and a cooling of the high-frequency antenna. A plasma processing apparatus, comprising: