JP2000106298A - Plasma processing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain good seal performance between a plasma space and its outside, over a long period in an ECR(electron cyclotron resonance) plasma processing unit. SOLUTION: In a seal space, defined between a transmitted window 23 for a microwave and a vacuum chamber 2 in an ECR plasma processing unit, a first sealing member 61 is disposed which is formed of an excellent plasma-proof material, for example a perfluoro elastomer which serves as a kind of high plasma-proof property, and on its outside a second sealing member 62 is disposed, which is formed of a material having high surface-contact property and a low gas-permeating property, for example, a fluoro rubber or a perfluoro elastomer which serve as the kind of the high surface-contacting property and low gas-permeating property, and the good sealing performance is ensured by the second sealing member 62, and furthermore deterioration due to plasma is supressed by the first sealing material 61.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing apparatus using electron cyclotron resonance.

[0002]

2. Description of the Related Art Recently, as one of the techniques for performing film formation processing and etching using plasma, ECR which generates microwave discharge by using a cyclotron motion of electrons in a magnetic field and a resonance phenomenon of microwaves. (Electr
On-cyclotron Resonance) plasma processing methods have attracted attention. According to this method, high-density plasma under high vacuum can be generated by electrodeless discharge, so that high-speed surface treatment can be realized and there is no risk of contamination of a semiconductor wafer (hereinafter, referred to as a wafer). There is.

An example of a conventional plasma processing apparatus for performing the ECR plasma processing will be described with reference to FIG. 4 taking a film forming process as an example. This plasma processing apparatus includes a waveguide 1
The microwave supplied, for example, at 2.45 GHz supplied by the microwave oven 3 into the plasma generation chamber 1A of the aluminum vacuum vessel 1 is transmitted through a microwave transmission window 14 made of aluminum nitride (AlN).
And at the same time a predetermined size, for example 875
A Gaussian magnetic field is applied by the electromagnetic coil 10 to generate a plasma-generating gas, for example, Ar gas and O2 gas, at high density by interaction (resonance) between the microwave and the magnetic field. A reactive processing gas, eg, SiH4 gas, introduced from the side into the chamber 1B is activated to form active species, and sputter etching is performed on the surface of the silicon wafer W on the mounting table 11 to which the high frequency power supply unit 12 is connected. The deposition is performed simultaneously.
The contradictory sputter etching operation and deposition operation are controlled (controlled) such that the deposition operation is dominant in macro terms, and the deposition is performed as a whole.

In order to ensure the sealing performance of this device, it is necessary to pay particular attention to the sealing structure between the microwave transmitting window 14 and the vacuum vessel 1. That is, the portion to be sealed is exposed to the plasma, and the temperature of the microwave transmission window 14 is set to, for example, 2 by the transmission of the microwave and the plasma.
The temperature is raised to 00 ° C., and the sealing material is interposed between dielectrics such as metals and ceramics.

FIG. 5 shows a main part of a sealing structure between the microwave transmitting window 14 and the vacuum vessel 1 in a conventional plasma processing apparatus. Conventionally, an aluminum nitride plate constituting the microwave transmission window 14 is placed on the upper end of the vacuum vessel 1, and the upper end of the vacuum vessel 1 is connected to the microwave transmission window 14.
O-ring-shaped sealing material 15 is interposed at the contact portion with the lower surface of the OLED. As the material of the sealing material 15,
For example, fluororubber such as Viton (registered trademark of DuPont), perfluoroelastomer, metal material, resin material, ceramics, or a composite material composed of a metal material or a resin material and an elastic material has been studied.

[0006]

However, while Viton is most commonly used in semiconductor manufacturing equipment, Viton has the drawback of poor plasma resistance, and therefore has a short service life and is frequently replaced. There is a problem that it must be performed and a problem that it causes particles to be generated. Some perfluoroelastomers have good plasma resistance and also have better heat resistance than fluororubber, but the contact between the surface of the sealing material and the surface to be sealed (surface contact) and the material itself There is a disadvantage that the gas permeability is lower than that of fluororubber.

Further, metal materials and resin materials are excellent in plasma resistance, and furthermore, metal materials are excellent in heat resistance. However, in order to secure the sealing property, the surface roughness of the sealing surface (center line average roughness Ra) is required. However, there is a drawback that an accuracy of 0.8a or less is required, so that there is a problem that productivity is low and manufacturing cost is high. Furthermore, in order to ensure the sealing performance of ceramics, the surface roughness of the sealing surface requires precision, and in addition to the problem of poor productivity and high manufacturing cost, handling is also performed to prevent distortion and damage. In addition, there is a disadvantage that careful attention is required for storage. As described above, none of the seal materials that can be selected at present at present satisfy all of plasma resistance, heat resistance, sealability, and productivity.

The present invention has been made under such circumstances, and an object of the present invention is to provide a plasma processing apparatus capable of obtaining high sealing properties over a long period of time.

[0009]

According to the present invention, there is provided a plasma processing apparatus for processing an object to be processed by plasma generated in a vacuum vessel, wherein a first member and a second member forming a part of the vacuum vessel are provided. A first member made of a material having high plasma resistance, interposed between the first member and the second member, and provided for sealing between the plasma space and the outside. A sealing material, interposed between the first member and the second member, and provided on the outer side of the first sealing material to seal between the plasma space and the outside; A second sealing material having high surface contact and low gas permeability of the material itself.

According to the present invention, the seal between the plasma space and the outside is ensured by the second seal member, and the first seal member is exposed to plasma because of its excellent plasma resistance. In terms of the overall function of the two sealing materials combined, high sealing performance is obtained and a long service life is obtained. In the present invention, at least one of the first member and the second member is made of, for example, a dielectric.

Further, the plasma processing apparatus according to the present invention is provided with a vacuum vessel for treating a workpiece in a vacuum atmosphere and a part of the vacuum vessel for introducing microwaves into the vacuum vessel. A microwave transmission window, interposed between the microwave transmission window and the vacuum vessel, and provided for sealing between a plasma space defined by the vacuum vessel and the microwave transmission window and the outside; A first sealing member made of a material having high plasma resistance; and a first sealing member interposed between the microwave transmitting window and the vacuum vessel and for sealing between a plasma space and the outside. A second sealing material provided on the outer side of the sealing material and having high surface contact and low gas permeability of the material itself.

According to the present invention, in the ECR plasma processing apparatus, the seal between the vacuum vessel and the microwave transmitting window is ensured by the second seal material, and the first seal member is used.
Since the sealing material is excellent in plasma resistance, the deterioration due to exposure to plasma is small. Therefore, in terms of the overall function of both sealing materials, a high sealing property can be obtained and a long service life can be obtained.

[0013]

FIG. 1 shows an example of a plasma processing apparatus used in an embodiment of the present invention. This apparatus has a vacuum vessel 2 made of, for example, aluminum or the like. This vacuum vessel 2 is located above and communicates with a first cylindrical vacuum chamber 21 for generating plasma below the first vacuum chamber 21. The first vacuum chamber 21 is connected to a second vacuum chamber 22 having a larger diameter than the first vacuum chamber 21. The vacuum vessel 2 is grounded and has a zero potential.

An upper end of the vacuum vessel 2 is opened, and a microwave transmitting window 2 made of a material such as aluminum nitride (AlN), for example, aluminum nitride (AlN) is opened at this portion.
3 are provided. Vacuum container 2 and microwave transmission window 2
Numeral 3 is hermetically sealed by two sealing members 61 and 62 so as to maintain a vacuum state in the vacuum container 2. Outside the microwave transmission window 23, a waveguide 25 connected to a high frequency power supply unit 24 for generating microwaves of, for example, 2.45 GHz is provided. For example, microwaves guided by the waveguide 25 in the TE mode or converted into the TM mode by the waveguide 25 are guided into the first vacuum chamber 21 through the microwave transmission window 23. It is possible to do.

For example, near the upper end of the first vacuum chamber 21, that is, immediately below the microwave transmission window 23, a plurality of plasma generating gases (for example, Ar gas) are supplied into the first vacuum chamber 21. Of the first vacuum chamber 2
1 are provided to penetrate the side wall. The other end of the gas nozzle 31 is connected to a gas source (not shown), for example, an Ar gas source.

In the second vacuum chamber 22, a wafer mounting table 4 is provided so as to face the first vacuum chamber 21. The mounting table 4 is provided with an electrostatic chuck 41 on the surface thereof. The electrode of the electrostatic chuck 41 has a DC power supply (not shown) for attracting a wafer and a bias voltage for drawing ions into the wafer. The high frequency power supply unit 42 is connected so as to apply the voltage.

On the other hand, the upper part of the second vacuum chamber 22, ie, the first
For example, a ring-shaped film-forming gas supply unit 51 is provided in a portion communicating with the vacuum chamber 21.
A kind of film forming gas is supplied, and the mixed gas is supplied into the vacuum chamber 2 from the gas hole 54 on the inner peripheral surface.

A ring-shaped main electromagnetic coil 26 as a magnetic field forming means is arranged close to the outer periphery of the side wall defining the first vacuum chamber 21 as a magnetic field forming means, and is disposed below the second vacuum chamber 22. On the side is a ring-shaped auxiliary electromagnetic coil 27
Is arranged. Exhaust pipes 28 are respectively connected to the bottom of the second vacuum chamber 22 at, for example, two positions symmetric with respect to the central axis of the vacuum chamber 22.

FIG. 2 shows an example of a sealing structure between the vacuum vessel 2 and the microwave transmitting window 23. The sealing structure is configured such that the microwave transmitting window 2
3, a flange portion 62 is provided at a position below the first vacuum chamber 21 along the inner periphery of the first vacuum chamber 21 toward the central axis of the vacuum chamber 21, and the microwave transmission window 23 is provided on the flange portion 62. , A first sealing member 61 is interposed at a contact portion between the lower surface of the microwave transmitting window 23 and the upper surface of the flange portion 62, and further inserted into the upper end portion of the vacuum vessel 2. A double seal structure is provided in which a second seal member 62 is interposed between the side end surface of the vacuum chamber 23 and the inner peripheral surface near the upper end of the vacuum vessel 2.

The first seal member 61 is made of a material having excellent plasma resistance, for example, a material having high plasma resistance among various perfluoroelastomer. The first seal member 61 is formed in a ring shape with a cross-sectional shape of, for example, a circle. For example, a groove 63 is formed in the vicinity of the inner peripheral end of the flange portion 62 along the inner end thereof. It is fitted inside.

The second seal member 62 has high surface contact (there is little gap between surfaces), low gas permeability (it is difficult for gas to pass through the material itself), and excellent heat resistance. It is made of a material such as fluororubber or a variety of perfluoroelastomer, which has high surface contact, low gas permeability, and high heat resistance, and has a cross-sectional shape of, for example, a circular ring. . The second seal member 62 is arranged outside the first seal member 61.

In both the vacuum vessel 2 and the microwave transmitting window 23, the surface roughness (center line average roughness Ra) of the portion where the first sealing material 61 contacts and the portion where the second sealing material 62 contacts. In each case, for example, about 1.6a is sufficient. This is because when the inventor examined the sealing performance by setting the surface roughness (center line average roughness Ra) of the contact portions of the sealing materials 61 and 62 to 1.6a, the sealing performance was good. Is based on The sealability was confirmed by a leak measurement using a He leak detector. Therefore, high surface contact can be obtained without polishing the portion to increase the accuracy of the surface roughness.

The lower end of the waveguide 25 is placed on the upper end of the vacuum vessel 2 having such a double seal structure and on the peripheral edge of the microwave transmitting window 23 and is fixed to the vacuum vessel 2. The wall near the lower end of the waveguide 25 and the vacuum vessel 2
A flow path is formed inside one or both of the walls near the upper end of the sealing material 6, and a coolant, for example, cooling water is caused to flow through the flow path.
1, 62 may be cooled. In particular, if the second sealing member 62 is cooled, the second sealing member 6
No. 2 may be made of a material having at least high surface contact and low gas permeability.

Next, a method of forming an interlayer insulating film made of, for example, a CF film on the wafer W to be processed by using the above-described apparatus will be described. First, a gate valve (not shown) provided on the side wall of the vacuum vessel 2 is opened, and a wafer W having, for example, an aluminum wiring formed on a surface thereof is carried in from a load lock chamber (not shown) by a transfer arm (not shown) and placed on the mounting table 4. The wafer W is electrostatically attracted by the electrostatic chuck 41.

Subsequently, after closing the gate valve to seal the inside, the inside atmosphere is evacuated from the exhaust pipe 28 and evacuated to a predetermined degree of vacuum.
A plasma generating gas, for example, an Ar gas is introduced into the vacuum chamber 21 of FIG.
2, a CF-based film-forming gas is introduced at a predetermined flow rate.

Then, the inside of the vacuum vessel 2 is maintained at a predetermined process pressure, and 13
A bias voltage of 56 MHz and 1500 W is applied, and the surface temperature of the mounting table 4 is set to about 400 ° C.

The high-frequency (microwave) of 2.45 GHz from the high-frequency power supply unit 24 reaches the ceiling of the vacuum vessel 2 through the waveguide 25, passes through the microwave transmission window 23, and the first. It is introduced into the vacuum chamber 21. On the other hand, vacuum vessel 2
Inside, a magnetic field from the upper part of the first vacuum chamber 21 to the lower part of the second vacuum chamber 22 is formed by the electromagnetic coils 26 and 27. For example, the intensity of the magnetic field becomes 875 gauss near the lower portion of the first vacuum chamber 21, and electron cyclotron resonance is generated by the interaction between the magnetic field and the microwave. Is done. The plasma flow flowing from the first vacuum chamber 21 into the second vacuum chamber 22 activates the CF-based gas supplied thereto to form active species, and forms a CF film on the wafer W. .

According to the above-described embodiment, the first sealing member 61 made of a material having high plasma resistance is provided between the microwave transmitting window 23 and the vacuum vessel 2 and further has a surface contact outside thereof. Since the second sealing material 62 having high heat resistance, low gas permeability and excellent heat resistance is provided,
Vacuum container 2 and microwave transmitting window 2
3 and the first sealant 61 is excellent in plasma resistance, so that deterioration due to exposure to plasma is small. Therefore, a high sealing property between the plasma space and the outside can be obtained for a long time. If a seal material made of a material having a high surface contact property and a low gas permeability is arranged outside a seal material made of a material having high plasma resistance, the two seal materials are arranged on the same plane. You may.

In the above, according to the present invention, an exhaust pipe may be connected from the side of the bottom of the vacuum chamber, or an electromagnetic coil for forming a magnetic field may be provided beside the waveguide. In addition, the present invention is not limited to the sealing portion between the vacuum vessel 2 and the microwave transmission window 23, that is, the sealing portion between the metal and the dielectric. Also applicable to Further, the substrate to be processed is not limited to a wafer, and may be a glass substrate for a liquid crystal display.

The present invention is not limited to the apparatus used for the film forming process, but may be any of various apparatuses for processing a substrate to be processed using plasma, for example, an ICP (Induct) as shown in FIG.
Also, the present invention can be applied to a plasma processing apparatus using an active coupled plasma. In this ICP plasma processing apparatus, a plasma space is formed by a dome-shaped container 71 and a chamber 72, and an electric field and a magnetic field are applied from a coil 73 wound around the dome-shaped container 71 to a processing gas introduced from a gas supply nozzle 74. The plasma is generated by the application, and the processing of the wafer W on the mounting table 75 is performed using the generated plasma. Note that in FIG.
The reference numeral 6 indicates an exhaust pipe.

The dome-shaped container 71 and the chamber 7 of this device
2, the surface contact is high, the gas permeability is low, outside the first sealing material 77 made of a material having high plasma resistance, for example, a perfluoroelastomer (however, a material having high plasma resistance). A second sealing material 78 made of a material having excellent heat resistance, for example, fluoro rubber or perfluoroelastomer (having high surface contact, low gas permeability and high heat resistance) is disposed. As a result, not only a high sealing property between the plasma space and the outside is obtained for a long period of time, but also the degree of freedom in selecting the material of the dome-shaped container 71 is widened, and for example, a sintered body can be used. can get.

[0032]

As described above, according to the present invention, the first sealing material has excellent plasma resistance, and the second sealing material has high surface contact and low gas permeability. High sealing performance between the plasma space and the outside can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a plasma processing apparatus used in an embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a sealing structure between a vacuum vessel and a microwave transmitting window in the plasma processing apparatus.

FIG. 3 is a schematic view showing another example of the plasma processing apparatus according to the present invention.

FIG. 4 is a schematic view of a conventional plasma processing apparatus.

FIG. 5 is a cross-sectional view showing a seal structure between a plasma space and the outside in a conventional plasma processing apparatus.

[Explanation of symbols]

 W Semiconductor wafer 2 Vacuum container 23 Microwave transmission window 61, 77 First sealant 62, 78 Second sealant

Claims (3)

[Claims] 1. An apparatus for processing an object to be processed by plasma generated in a vacuum vessel, comprising: a first member and a second member forming a part of the vacuum vessel; the first member and the second member. A first sealing material interposed between the first member and the second member, the first sealing member being made of a material having high plasma resistance and provided for sealing between the plasma space and the outside; The first member is interposed between the first member and the first member and seals between the plasma space and the outside.
A second seal member provided on the outer side of the seal member and having high surface contact and low gas permeability of the material itself. 2. The plasma processing apparatus according to claim 1, wherein at least one of said first member and said second member is made of a dielectric. 3. A vacuum container for processing an object to be processed in a vacuum atmosphere, a microwave transmission window provided in a part of the vacuum container for introducing microwaves into the vacuum container, and Interposed between the wave transmission window and the vacuum vessel,
A first sealing member made of a material having high plasma resistance, provided for sealing between the outside and a plasma space defined by the vacuum container and the microwave transmitting window; and the microwave transmitting window. And between the vacuum container,
And a second seal member having a high surface contact property and a low gas permeability of the material itself, provided on the outer side of the first seal member for sealing between the plasma space and the outside;
A plasma processing apparatus comprising: