JPH0612764B2 - Microwave plasma processing equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a microwave plasma processing apparatus including means for controlling a reflected wave of microwaves.

(Prior art and its problems) In recent years, plasma processing apparatuses using microwaves have been used for thin film formation and thin film etching techniques. As an example thereof, the invention described in JP-A-57-177975 is known. The microwave processing technology shown here introduces microwaves into plasma to which a magnetic field of a predetermined strength is applied to cause electron cyclotron resonance motion, and the energy generated by this causes the gas in the plasma generation chamber to plasma And the substrate is processed with the ions.

Conventionally, a stub tuner, an EH tuner, or the like has been used as a matching device that matches the introduced microwave power so that it is completely absorbed by the load. I tried to control the reflected wave of the microwave by installing it in the wave tube.

However, the three-stub tuner and the EH tuner cannot completely control the reflected wave, and as shown in FIG.
A microwave reflected wave was generated when the microwave power was 1 Kw, and when the microwave reflected wave became large, the film formation rate could not be improved even if a power of 1 Kw or more was applied.

In the stub tuner, the microwave is lost due to discharge at the tip of the stub or heating of the waveguide, and heat is generated due to this loss, which is a safety problem. Furthermore, due to the structure of using three stubs, it was difficult to automate.

On the other hand, in the EH tuner, the microwave loss due to heating of the waveguide is small, but not only is it expensive due to the precision of the mechanism, but also the size and weight of the device are large, which causes a problem that the device becomes large. there were. Further, as in the case of the above three stub tuner, it was difficult to automate.

(Object of the Invention) In a microwave plasma processing apparatus in which a substrate processing chamber is arranged outside a plasma generation chamber, the present invention suppresses the generation of reflected waves of microwaves and allows the microwaves to be stably incident on the substrate at high speed. The purpose is to be able to process.

(Means for Solving Problems) A plasma generation chamber into which a predetermined microwave and a processing gas are introduced, and a magnetic field is set inside the plasma generation chamber to cause an electron cyclotron resonance phenomenon to generate a plasma of the processing gas. Having a magnetic field generating means for converting into a substrate and a substrate processing chamber in which the substrate to be processed is arranged, and the plasma is drawn into the substrate processing chamber by a plasma drawing member provided near the boundary between the plasma generation chamber and the substrate processing chamber, In a microwave plasma processing apparatus for processing a substrate by irradiating the substrate installed in a substrate processing chamber, the position of the plasma extraction member is moved to adjust the impedance when the microwave is introduced to match the microwave. The drawing member moving mechanism for performing

Further, as a preferred embodiment, a detector for monitoring the incident wave and the reflected wave of the microwave is provided, and the extraction member moving mechanism is composed of a motor, and the motor is electrically connected to the detector and the detector. Feedback is applied so that the plasma extraction member is located at a position where the reflected wave of the microwave monitored in step 1 is reduced.

Furthermore, as another preferred embodiment, the plasma extraction member is configured such that the pressure in the plasma generation chamber, the type of gas to be introduced,
Depending on the flow rate, the position is adjusted in advance so that a reflected wave of the microwave does not occur.

(Operation) With the above-described structure, the microwave is matched by adjusting the position of the plasma extraction member. As a result, the generation of reflected waves of microwaves is significantly suppressed, and the loss of microwave power can be greatly reduced compared to the conventional case.

(Embodiment) Next, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an embodiment of the present invention. This apparatus has a structure in which a plasma generation chamber 6 for generating plasma by electron cyclotron resonance and a substrate processing chamber 8 for processing a substrate are adjacent to each other. An air core solenoid coil 7 is wound around the plasma generating chamber 6. In addition, the plasma generation chamber 6 is provided with an introduction window 5 made of an insulating material such as quartz glass or ceramics, and the microwave transmitted from the microwave power source 3 through the waveguide 4 through the introduction window 5. A wave is introduced into the plasma generation chamber 6.

The waveguide 4 is provided with a microwave incident sensor 16 and a reflected wave sensor 17, respectively. Then, the values detected by these sensors are monitored by the detector 18 connected thereto. Further, a plasma extraction plate 11 for matching microwaves is movably provided near the boundary with the substrate processing chamber 8. A plasma extraction port 14 is formed in the central portion of the plate-shaped plasma extraction member 11, and the plasma generated in the plasma generation chamber 6 is introduced into the substrate processing chamber 8 through the plasma extraction port 14. Get burned. Reference numeral 13 is a motor as a drawing member moving mechanism that moves the position of the plasma drawing member 11, and is connected to the detector 18. In FIG. 1, the motor 13 as the drawing member moving mechanism is provided inside the substrate processing chamber 8, but it may be installed outside the apparatus. Also, reference numeral 15
Is a water cooling tube for cooling the plasma extraction member 11.

On the other hand, a vacuum exhaust device 1 is connected to the substrate processing chamber 8 adjacent to the plasma generation chamber 6. Further, the substrate holder 9 is fixedly provided so as to face the plasma outlet 14. Then, the substrate to be processed is loaded into the substrate processing chamber 8 from the outside by a transfer mechanism (not shown),
It is placed on the substrate holder 9 with the surface to be processed facing up.

Then, the vacuum evacuation device 1 is operated to evacuate the inside of the substrate processing chamber 8 to a predetermined pressure, and then the plasma generation chamber 6 and the substrate are passed through the gas introducing pipes 2 (a) and 2 (b). A predetermined gas is introduced into both of the processing chambers 8 to adjust and maintain the processing pressure.

Then, a microwave of 2.45 GHz passes from the microwave generator 3 through the waveguide 4 and is introduced into the plasma generation chamber 6 through the introduction window 5. The incident microwave is detected by the incident sensor 16 and monitored by the detector 18.

On the other hand, a current is supplied from the plasma generating power source 12 to the air-core solenoid coil 7 to generate a magnetic field of 875G. As a result, electron cyclotron resonance is caused in the plasma generation chamber 6, and the energy introduced at this time turns the gas introduced into the plasma generation chamber 6 into a high density plasma. Then, this plasma is drawn out toward the substrate processing chamber 8 from the plasma drawing port 14 at the central opening of the plasma drawing member 11, and the substrate 1 placed on the substrate holder 9 is pulled.
When it reaches 0, the substrate 10 is subjected to processing such as thin film formation by this plasma.

In the present embodiment, matching of the microwaves introduced into the plasma generation chamber 6 is performed by moving the plasma drawing member 11 to a predetermined position by a motor 13 as a drawing member moving mechanism.

That is, the microwave reflected wave sensor 1 provided in the waveguide 4 is moved while the plasma drawing plate 11 is moved in the plasma generating chamber 6 by the motor 13 as the drawing member moving mechanism.
The plasma drawing member 11 is stopped when the electric power of the reflected wave becomes minimum while monitoring with the detector 18 via 7.

However, the plasma extraction member 11 that can be matched
The position of depends on the type of gas, and also shifts depending on the gas flow rate and the processing gas pressure. Therefore, feedback is provided between the plasma extraction member 11 and the power detector 18 so that the plasma extraction member 11 automatically moves according to the value of the reflected wave so that matching can be achieved under the above conditions. There is.

On the other hand, when the type of gas, the gas flow rate, and the processing gas pressure are predetermined, the plasma extraction member 11 may be moved to a predetermined position by manual operation.

As described above, it was confirmed by experiments that the microwaves can be stably and efficiently introduced into the plasma generation chamber 6 because the microwaves can be matched by moving the plasma extraction member 11.

That is, FIG. 2 shows the microwave power of the film formation rate when N ₂ gas was introduced into the plasma generation chamber 6 side and SiH ₄ gas was introduced into the substrate processing chamber 8 side and the processing pressure was 5 × 10 ^−4. This is a graph showing the dependency graph. According to this, if the microwave is stably introduced, that is, if there is no reflected wave of the microwave, the film formation rate is proportional to the microwave power.

Furthermore, FIG. 3 shows that N = 200 mm in the plasma generation chamber.
₂ shows the value of the reflected wave when the gas is introduced and the plasma extraction member 11 is moved.

The abscissa represents t as shown in FIG.
2 shows the distance between the top part of the plasma extraction member 11 and the plasma extraction member 11. It can be seen from FIG. 3 that the value of the microwave reflected wave is remarkably reduced when the plasma extraction member 11 is located at each of the points t ₁ and t ₂ .

Although the present embodiment has been described with respect to film formation, it can be applied to etching and similar results can be obtained. In the case of etching, either an ion flow method using a divergent magnetic field or an acceleration method using a grid may be used. In the case of the acceleration type, either a DC or AC electric field can be applied to the grid. Further, in either case of film formation or etching, a DC or AC electric field can be applied to the substrate holder.

(Advantages of the Invention) The present invention has the structure and operation as described above, and can stably introduce high microwave power into the plasma generation chamber without being affected by reflected waves, thus improving the substrate processing speed. Can be made.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus showing an embodiment of the present invention, FIG. 2 is a graph of microwave power dependence of film forming rate in the film forming apparatus of this embodiment, and FIG. Graph showing the value of the reflected wave of the microwave when
FIG. 4 is a microwave power dependence graph of the film forming rate in the conventional film forming apparatus. 3 ... Microwave generation power source, 6 ... Plasma generation chamber, 7
...... Air core solenoid coil, 8 ... Substrate processing chamber, 10 ...
... Substrate, 11 ... Plasma drawing member, 13 ... Motor as drawing member moving mechanism, 14 ... Plasma drawing port, 18 ... Detector.

Claims (3)

[Claims] 1. A plasma generating chamber into which a predetermined microwave and a processing gas are introduced, and a magnetic field generating means for setting a magnetic field inside the plasma generating chamber to cause an electron cyclotron resonance phenomenon to generate a plasma of the processing gas. And a substrate processing chamber in which a substrate to be processed is placed, and the plasma is drawn into the substrate processing chamber by a plasma drawing member provided near the boundary between the plasma generation chamber and the substrate processing chamber and installed in the substrate processing chamber. In the microwave plasma processing apparatus for irradiating the processed substrate to process the substrate, the position of the plasma extraction member is moved to adjust the impedance when the microwave is introduced, and the extraction member is moved to perform microwave matching. A microwave plasma processing apparatus having a mechanism. 2. A detector for monitoring an incident wave and a reflected wave of microwaves, wherein the pull-out member moving mechanism is composed of a motor, and the motor is electrically connected to the detector. The microwave plasma processing apparatus according to claim (1), wherein feedback is applied so that the plasma extraction member is located at a position where the reflected wave of the monitored microwave is reduced. 3. The plasma extraction member is adjusted in advance to a predetermined position so that a reflected wave of microwave is not generated according to the pressure in the plasma generation chamber, the type of gas to be introduced, and the flow rate. A microwave plasma processing apparatus according to claim (1).