JP2718328B2 - Microwave plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma processing apparatus used as an etching apparatus and a film forming apparatus using plasma generated by microwaves.

[0002]

2. Description of the Related Art A microwave plasma processing apparatus for generating plasma by electron cyclotron resonance excitation is disclosed in US Pat.
Highly active plasma can be generated at low gas pressure, high activity plasma can be generated, wide range of ion energy can be selected, large ion current can be obtained, and directionality and uniformity of ion flow are excellent. Research and development are being pursued as indispensable for the manufacture of devices and the like.

FIG. 2 is a longitudinal sectional view of a conventional microwave plasma processing apparatus using an electron cyclotron resonance excitation using a microwave configured as an etching apparatus. In the figure, reference numeral 31 denotes a plasma generation chamber. The plasma generation chamber 31 has a cooling water flow chamber 31a with a double surrounding wall, a microwave inlet 31c sealed with a quartz glass plate 31b in the center of the upper wall, and a microwave inlet 31c in the center of the lower wall. A plasma outlet 31d is provided at a position facing the microwave inlet 31c. One end of a waveguide 32 having the other end connected to a microwave oscillator (not shown) is connected to the microwave introduction port 31c, and a sample chamber 33 is provided so as to face the plasma outlet 31d. An exciting coil 34 is disposed concentrically with the chamber 31 and one end of the waveguide 32 connected to the chamber 31 so as to surround them.

In the sample chamber 33, a sample table 37 is provided at a position facing the plasma outlet 31d, and a sample S such as a wafer can be detached by itself or by a means such as electrostatic attraction. An exhaust port 33a is mounted on the lower wall of the sample chamber 33 and connected to an exhaust device (not shown). 31 g is a gas supply system connected to the plasma generation chamber 31, and 33 g is a sample chamber 33
And 31h and 31i are the cooling water supply and discharge systems.

In such an etching apparatus, a gas is supplied into the plasma generation chamber 31 through a gas supply system 31g after the inside of the plasma generation chamber 31 and the sample chamber 33 are set to a required degree of vacuum. Microwaves are introduced into the plasma generation chamber 31 through the microwave introduction port 31c while forming a magnetic field by the excitation coil 34, and the plasma is generated by resonantly exciting the gas using the plasma generation chamber 31 as a cavity resonator. The generated plasma has a divergent magnetic field whose magnetic flux density decreases as it goes toward the sample chamber 33 formed by the excitation coil 34.
Is projected around the sample S in the sample chamber 33, and the sample S in the sample chamber 33 is projected.
The surface is etched (JP-A-57-133)
No. 636).

In the above-mentioned conventional apparatus, the microwave introduction port 31c opened in the upper wall of the plasma generation chamber 31 is hermetically sealed by a quartz glass plate 31b which allows microwave transmission. 31b is disposed on the outer peripheral edge of the microwave inlet 31c so as to close the microwave inlet 31c, and is held by a stopper 32b in a state of overlapping with the flange 32a at the end of the waveguide 32. Therefore, when viewed from the side of the plasma generation chamber 31 functioning as a cavity resonator for microwaves, the inside of the microwave introduction port 31c is a space, and a step is formed between itself and the inner wall surface of the plasma generation chamber 31. There has been a problem that microwaves are reflected abnormally at the portion, and the uniformity of the plasma distribution is deteriorated due to this.

As a countermeasure against this, a microwave plasma processing apparatus as shown in FIG. 3 has been filed (Japanese Patent Laid-Open No. 63-318).
099). FIG. 3 which is a partial sectional view of such an apparatus.
In the above, a microwave transmitting material 48 is interposed in a microwave introduction port 31c opened to the plasma generation chamber 31 so as to be flush with the inner wall surface of the plasma generation chamber 31 so as to fill the microwave introduction port 31c. The other structure is substantially the same as the device shown in FIG.
The microwave transmitting material 48 is formed by providing a larger rectangular flange portion 48b on the upper end side of a disk portion 48a substantially equal to the diameter and the axial length dimension of the microwave introduction port 31c,
The disk portion 48a is closely fitted to the microwave introduction port 31c,
The flange 48b is abutted on the outer periphery of the microwave inlet 31c with an O-ring or the like (not shown) interposed therebetween so that the lower end surface of the disk portion 48a is flush with the inner wall surface of the plasma generation chamber 31. positioned.

In such a conventional apparatus, the plasma introduction port 31c opened in the upper wall of the plasma generation chamber 31 is filled with the microwave transmitting material 48 without any gap. Without abnormal reflection of
As a result, the microwave reflectance is reduced, and the generation of plasma is also made uniform. However, in such a conventional device, there is a difference in the diameter between the microwave inlet 31c and the plasma generation chamber 31, and the abnormal reflection of the microwave caused by the difference in the diameter cannot be eliminated. As a result, a complicated microwave electric field distribution is generated, and the uniformity of the plasma distribution is not sufficient.

In order to solve such a problem, a microwave transmitting material is interposed also on the plasma generation chamber 31 side as shown in FIG.
A microwave plasma processing apparatus as shown in FIG. In FIG. 4 which is a longitudinal sectional view of such a device, not only the microwave transmitting material 48 is interposed in the microwave introduction port 31c, but also the end of the plasma generation chamber 31 facing the microwave introduction port 31c has a microwave The transmission material 49 is interposed. The other configuration is substantially the same as that of the apparatus shown in FIGS. 2 and 3, and the corresponding parts are denoted by the same reference numerals. With such a configuration, the uniformity of the microwave electric field intensity in the plasma generation chamber 31 is improved, and abnormal reflection of the microwave due to the difference in diameter between the microwave inlet 31c and the plasma generation chamber 31 is suppressed. And
A uniform plasma distribution is obtained.

[0010]

However, in the conventional apparatus as described above, since the microwave transmitting material for introducing the microwave is in contact with the plasma over a wide area, the propagation of the microwave is limited to the plasma. Is strongly influenced by the state of the microwave, and the microwave matching failure, which is considered to be caused by the impedance mismatch, occurs frequently, causing a change in the plasma emission intensity, making it difficult to generate a stable plasma. There was a problem and there was room for improvement.

The present invention has been made in view of the above circumstances, and has improved impedance matching, improved microwave matching, can generate stable plasma, and has excellent reproducibility in etching or film forming processing. It is an object of the present invention to provide a microwave plasma processing apparatus capable of performing the following.

[0012]

According to the present invention, there is provided a microwave plasma processing apparatus comprising a plasma generation chamber having an opening for introducing a microwave, wherein the microwave plasma processing apparatus is flush with an inner wall surface of the plasma generation chamber. A microwave transmitting material formed in a shape that fills the microwave introducing port so that the microwave transmitting material has a cross section substantially equal to the inner cross section of the plasma generation chamber at a predetermined distance, respectively. And a plasma generation chamber.

[0013]

According to the microwave plasma processing apparatus of the present invention, the microwave transmission material at the microwave introduction port and the microwave transmission material at the end of the plasma generation chamber are interposed via a space having an optimum distance, so that the plasma is generated. The impedance matching is improved, the microwave matching is improved, and a stable plasma is generated.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment.

FIG. 1 is a longitudinal sectional view of a microwave plasma processing apparatus according to the present invention (hereinafter referred to as the apparatus of the present invention). In FIG. 1, reference numeral 1 denotes a plasma generation chamber, 2 denotes a waveguide, and 3 denotes etching or forming. A sample chamber 4 in which a sample S on which a film is to be placed is arranged indicates an excitation coil.

The plasma generation chamber 1 has a double cylindrical structure with a cooling water flow chamber 1a having a double surrounding wall, and is formed so as to constitute a cavity resonator for microwaves. The center of the upper wall is provided with a microwave inlet 1c, and the center of the lower wall is provided with a plasma extraction window 1d at a position facing the microwave inlet 1c. One end of the waveguide 2 is connected to the microwave introduction port 1c, and a sample chamber 3 is disposed facing the plasma extraction window 1d, and further connected to the plasma generation chamber 1 and the periphery thereof. An exciting coil 4 is provided around one end of the waveguide 2.

The other end of the waveguide 2 is connected to a microwave oscillator (not shown) so that the generated microwave is introduced into the plasma generation chamber 1. The exciting coil 4 is connected to a DC power supply (not shown), which forms a magnetic field by passing a DC current, generates a plasma by introducing microwaves into the plasma generation chamber 1, and A divergent magnetic field having a lower magnetic flux density is formed toward the sample chamber 3 side, and the generated magnetic field causes plasma generated in the plasma generation chamber 1 to be projected into the sample chamber 3. The sample chamber 3 is provided with an exhaust port 3a connected to an exhaust device (not shown) on the bottom wall facing the plasma extraction window 1d. 7 are arranged,
The sample S is placed on the sample stage 7 so as to face the plasma extraction window 1d.
Are arranged. 1g is a gas supply system connected to the plasma generation chamber 1, 3g is a gas supply system connected to the sample chamber 3, and 1h and 1i are supply and discharge systems of cooling water.

In the apparatus of the present invention, quartz glass and ceramic (Al ₂ O) are provided in the microwave introduction port 1c and in the end of the plasma generation chamber 1 facing the microwave introduction port 1c.
₃ , BN), and microwave transmitting materials 8 and 9 made of a heat-resistant polymer material (Teflon, polyimide) or the like. The microwave transmitting material 8 is connected to the microwave inlet 1c.
A circular flange portion 8b larger than this is provided on the upper end side of the disk portion 8a substantially equal to the diameter and the axial length dimension of the disk portion 8a, and the disk portion 8a is tightly fitted to the microwave introduction port 1c. The portion 8b is brought into airtight contact with the outer periphery of the microwave inlet 1c with an O-ring or the like (not shown) interposed therebetween. In this state, the lower end surface of the disk portion 8a is flush with the inner wall surface of the plasma generation chamber 1. It is located to be. Further, the microwave transmitting material 9 is formed in a disk shape having a predetermined thickness substantially equal to the diameter of the plasma generation chamber 1, and is tightly fitted and fixed to the upper end of the plasma generation chamber 1. A spacer made of the same material as the microwave transmitting material 9 is provided between the peripheral portion of the microwave transmitting material 9 and the upper wall of the plasma generation chamber 1.
10 (thickness Dmm), the microwave transmitting material 8 and the microwave transmitting material 9 are positioned at a distance of Dmm by the interposition of the spacer 10, and a long distance is provided between the two materials 8, 9. There is a space 11 of Dmm.

Thus, in such an apparatus of the present invention,
The sample S is placed on the sample stage 7 in the sample chamber 3, and the inside of the plasma generation chamber 1 and the sample chamber 3 is set to a required degree of vacuum. Then, gas is supplied through the gas supply pipes 1g and 3g. It is supplied into the sample chamber 3, and a DC current flows through the exciting coil 4 in such a state, and a microwave is generated through the waveguide 2, the microwave transmitting material 8, the space 11, and the microwave transmitting material 9. Introduce into room 1. As a result, the gas is efficiently ionized to generate plasma, and the generated plasma is introduced into the sample chamber 3 by the divergent magnetic field formed by the exciting coil 4, activating the gas in the sample chamber 3 and the sample S An etching process or a film forming process is performed on the surface.

Next, the result of examining the matching state of microwaves by changing the separation distance Dmm between the microwave transmitting material 8 and the microwave transmitting material 9 will be described. Experiments were performed on Cl ₂ -based plasma used for etching polycrystalline silicon, and the gas pressure was 1.4 mTorr, 5.0 mTorr, 7.
0mTorr and microwave power (Pμ) to 1.0
The quality of the matching was confirmed by changing it within the range of ~ 2.0 kW. The results of this experiment are shown in Tables 1 to 4. First
The table shows the case of D = 0 mm, that is, the apparatus (the conventional apparatus shown in FIG. 4) in which the microwave transmitting substances 8 and 9 are brought into close contact with each other (Tables 2, 3 and 4). Each shows the case of the device of the present invention in which the microwave transmitting substances 8 and 9 are interposed at a fixed distance, and D = 1 mm, D = 2 mm, and D =
The result at the time of 3 mm is shown. In each table,
Indicates that the matching is good, Δ indicates that there is plasma hunting, and X indicates that the matching is poor.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

In the conventional apparatus shown in Table 1, gas pressure = 5
Although a poor matching was confirmed in the range of ７7 mTorr and Pμ = 1.8-1.9 kW, such a remarkable poor matching was not confirmed in the apparatus of the present invention shown in Tables 2, 3, and 4. Therefore, in the device of the present invention in which the microwave transmitting materials 8 and 9 are interposed at a certain distance, the matching characteristics are improved as compared with the conventional device in which the microwave transmitting materials 8 and 9 are interposed in close contact. ing. Also, the second, third,
From the results shown in Table 4, it was found that there was an optimum distance in the separation distance between the microwave transmitting substances 8 and 9, and that D = 2 mm was optimum in this embodiment. However, D may be adjusted according to the shape or material of the microwave transmitting material.

In the above-described embodiment, the configuration in which the apparatus of the present invention is applied to an etching apparatus or a film forming apparatus has been described. However, the present invention is not limited to this, and may be applied to, for example, a sputtering apparatus. is there.

[0027]

As described above, in the microwave plasma processing apparatus of the present invention, the microwave transmitting material is interposed at a predetermined distance over the entire cross section of the microwave introduction port and the end of the plasma generation chamber. Therefore, the present invention improves the impedance matching with plasma, improves microwave matching, can generate stable plasma, and can perform etching or film formation with good reproducibility. It has excellent effects.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a microwave plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a conventional microwave plasma processing apparatus.

FIG. 3 is a partial longitudinal sectional view of a conventional microwave plasma processing apparatus.

FIG. 4 is a longitudinal sectional view of a conventional microwave plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma generation room 1c Microwave introduction port 1d Plasma extraction window 2 Waveguide 3 Sample room 4 Exciting coil 7 Mounting table 8, 9 Microwave transmitting material 10 Spacer 11 Space S Sample

Claims (1)

(57) [Claims] 1. A microwave plasma processing apparatus having a plasma generation chamber having an open microwave introduction port, wherein the microwave is formed so as to fill the microwave introduction port so as to be flush with an inner wall surface of the plasma generation chamber. A microwave plasma, wherein a microwave transmitting material and a microwave transmitting material having a cross section substantially equal to the inner cross section of the plasma generation chamber are arranged at a predetermined distance in the microwave inlet and the plasma generation chamber, respectively. Process equipment.