JPH097998A - Plasma ashing apparatus - Google Patents

Abstract

PURPOSE: To treat a sample uniformly uniformly at high speed by appropriately setting a high density region of plasma generated in an ashing chamber, utilizing a microwave. CONSTITUTION: A microwave ashing apparatus has a microwave oscillator 1 to generate a microwave which is fed to an ashing chamber 4 through microwave propagating means 2 to which a resonator 24 to resonate the microwave in a specified mode is attached to feed a microwave having a microwave electric field intensity distribution where a high field intensity locates at the outer periphery area into the ashing chamber 4 from the resonator 24 to ash uniformly at high speed. Thus, the ashing rate of a wafer 10 being ashed can be uniform by increasing the density of the plasma located at the outer periphery in the chamber 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus and a plasma processing method, and more particularly to a plasma ashing processing apparatus suitable for performing high speed and uniform ashing on a wafer.

[0002]

2. Description of the Related Art A conventional plasma ashing processing apparatus is
For example, refer to the document “Semiconductor dry etching technology (Taku Tokuyama)
As described in “Editing, Publishing of Industrial Books, (1992), P195)”, counter electrodes are arranged above and below or to the left and right of a wafer to be subjected to ashing treatment, and the resist is removed by oxygen plasma or the like. The plasma during ashing must have a high density, and there is also a method that uses microwaves as a means of supplying energy to the ashing plasma. , It is possible to remove it in the form of carbon dioxide or water.
JP-A-5-267157 can be mentioned.

[0003]

In the conventional plasma processing apparatus, the microwave oscillated from the magnetron is introduced into the ashing processing chamber via the microwave waveguide, and the microwaves introduced into the ashing processing chamber are Energy is efficiently supplied to plasma in the upper part of the ashing processing chamber, and high-density plasma is generated in the ashing processing chamber. The plasma generated in the ashing chamber is transported to the wafer side where the ashing process is performed by diffusion. Therefore, in order to uniformly ash the wafer, the plasma density on the wafer to be subjected to the ashing treatment should be made as uniform as possible over a wide range, and in particular, the plasma density distribution should be such that the plasma density in the peripheral portion is larger than that in the central portion of the wafer. I have to

In the plasma ashing processing apparatus as in the above-mentioned prior art, the microwave mode or the like to be introduced into the ashing processing chamber has not been studied, and the emphasis has been only on creating high-density plasma. As a result, in order to evenly diffuse the generated plasma to the wafer, a plasma control plate or the like is arranged between the plasma chamber and the ashing processing chamber, and holes for uniformly diffusing the plasma are formed in the plasma control plate. It was provided. However, in this method, since the high density plasma is controlled and used for ashing, there is a problem that the plasma used for ashing is not efficiently generated with respect to the supplied energy.

The object of the present invention is to solve the above-mentioned problems of the prior art, and it is possible to set a high-density plasma region to be generated in the ashing processing chamber and to perform plasma processing at high speed and uniformly on the wafer. It is to provide an ashing processing device.

[0006]

SUMMARY OF THE INVENTION In the ashing processing apparatus, the above object is to provide a microwave propagation means for supplying the microwave generated by the microwave oscillator to the plasma generation space, thereby causing the microwave to resonate in a specific mode. It is achieved by attaching a chamber and using the microwave to plasmanize the processing gas to process the wafer.

[0007]

A resonator that resonates the microwave in a specific mode is attached while the microwave generated by the microwave oscillator is being supplied to the plasma generation space. By gradually changing the opening cross-sectional area from the resonator to the plasma generation space, it is possible to set the microwave mode introduced into the plasma generation space to a desired mode. For example, it is possible to supply the TE01 mode microwave having a ring-shaped strong electric field intensity of a desired size (radial direction) in the cross section of the microwave traveling direction to the plasma generation space. Thus, by making the portion having the highest microwave electric field strength ring-shaped, it is possible to generate high-density plasma having a distribution on the ring in the plasma chamber. Due to this plasma diffusion, it is possible to obtain a plasma distribution with improved uniformity from a medium height (convex) plasma distribution to a peripheral height (concave) plasma distribution on the wafer, which corresponds to the wafer ashing process. It becomes possible to perform processing with an optimal plasma distribution,
The wafer can be processed at high speed and uniformly.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a vertical sectional view of a plasma processing apparatus. In FIG. 1, reference numeral 1 is a magnetron that is a microwave oscillator, and oscillates a microwave of 2.45 GHz, for example. Reference numeral 2 is a microwave propagation means for propagating the microwave oscillated from the magnetron 1. In this case, the rectangular waveguide 21 and the circular rectangular conversion waveguide 2 are used.
2, the circular waveguide 23 and the resonator 24 to the magnetron 1
It is configured by sequentially connecting to. In this case, the rectangular waveguide 21 is set to have a size capable of propagating the microwave of the rectangular TE11 mode, and has a matching device 27 for matching the impedance of the microwave. In this case, the circular waveguide 23 is set to a size capable of propagating the microwave of the circular TE11 mode. The resonator 24 has a slit plate 25 between it and the reduction waveguide 26, and in this case, a plurality of slit holes radially arranged are formed as shown in FIG. In this case, the resonator 24 resonates the microwave having a high microwave electric field intensity in the outer peripheral portion of the outer peripheral portion, such as in the TE01 mode, and causes the slit plate 25 to generate microwaves in the outer peripheral portion of the outer peripheral portion in the TE01 mode. It is set to radiate microwaves with high wave field strength.

Reference numeral 4 is a chamber for forming a plasma generating space, and in this case, it is an ashing chamber which also serves as an ashing process. The ashing processing chamber 4 is a conductor, for example,
It is made of high-purity aluminum, etc., and the inner surface is treated with hard alumite, and it also functions as a microwave waveguide. The ashing process chamber 4 is formed by providing the quartz plate 3 between the ashing process chamber 4 and the waveguide 26, and separates the space on the waveguide 26 side and the process chamber space. The ashing chamber 4 is a vacuum chamber 5
Is connected to and connected to. A sample table 8 is supported on the bottom of the vacuum chamber 5 via an electrically insulating material. The sample stage 8 holds a wafer 10 to be subjected to processing such as ashing in a space formed by the ashing processing chamber 4 and the vacuum chamber 5. In this case, the arrangement surface of the wafer 10 is provided so as to face the quartz plate 3, and the porous plate 30 is attached between the wafer 10 and the quartz plate 3 for the purpose of preventing charge-up of the wafer.

In this case, the vacuum chamber 5 is provided with a gas supply means 12 capable of uniformly supplying the processing gas for the ashing process to the wafer 10 on the sample stage 8 from around the inner surface of the upper part of the ashing process chamber 4. In addition, the vacuum chamber 5 is connected to a vacuum evacuation means 11 capable of evacuating the interior of the vacuum chamber 5 to a predetermined pressure. A high-frequency power source 9, which is a power source for applying a bias voltage to the sample stage 8, is connected to the sample stage 8. In addition, reference numeral 28 partitions the vacuum chamber 5 into the ashing chamber 4
Is a gate valve that is connected to the above to form a processing chamber.

In the plasma processing apparatus configured as described above, the microwave emitted from the magnetron 1 is a rectangular waveguide 21, a matching box 27, a circular rectangular conversion waveguide 22,
It is guided to the microwave resonator 24 through the circular waveguide 23. The microwave guided to the resonator 24 is internally resonated in a specific microwave mode, and a waveguide 26 is emitted through a slit plate 25 that emits the specific mode.
Be led to. The microwave that has passed through the waveguide 26 is guided into the ashing processing chamber 4 via the quartz plate 3. The microwaves introduced into the ashing processing chamber 4 turn the processing gas in the ashing processing chamber 4 into plasma. At this time, the microwave generated from the magnetron 1 is introduced into the ashing processing chamber 4 through the microwave resonator 24 and the waveguide 26, so that the density of plasma generated in the ashing processing chamber 4 is increased. And the distribution is improved to be dense and uniform.

According to this embodiment, the microwave of a specific mode set by the resonator is introduced into the plasma processing chamber by using the waveguide, so that the high density distribution region of plasma is changed from the conventional middle-high state to the peripheral direction. Can be changed to an optimum position and a plasma state optimum for the ashing process can be created, so that the wafer can be uniformly processed and processed at high speed.

[0013]

According to the present invention, a microwave propagation means for supplying microwaves to the plasma generation space causes the microwave propagation means to resonate and radiate microwaves of a specific mode, and the resonator to reach the plasma generation space. By providing a waveguide that gradually changes the opening cross-sectional area, it is possible to appropriately set the high-density region of plasma generated in the ashing processing chamber,
There is an effect that the plasma on the wafer can be made into an optimum plasma state for the ashing process of the wafer and the wafer can be uniformly processed.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram showing details of a slit plate in the apparatus of FIG.

[Explanation of symbols]

1 ... Magnetron, 2 ... Microwave propagation means, 3 ... Quartz plate, 4 ... Ashing chamber, 5 ... Vacuum chamber, 8 ... Sample stage,
10 ... Wafer, 11 ... Vacuum exhaust means, 12 ... Gas supply means, 21 ... Rectangular waveguide, 22 ... Circular rectangular conversion waveguide, 23
... Circular waveguide, 24 ... Resonator, 25 ... Slit plate, 26
... Waveguide, 27 ... Matching device, 30 ... Perforated plate.

Claims (3)

[Claims] 1. A plasma generation space for performing an ashing process for removing a resist on a wafer after a treatment such as etching by plasma, a plasma generation device for supplying energy such as microwaves to the plasma generation space, An energy transfer device for transferring energy such as microwaves to the plasma generation space, an ashing processing chamber capable of maintaining the plasma generation space in a depressurized state, and a gas for performing ashing processing are supplied to the ashing processing chamber. A plasma processing apparatus comprising an ashing gas supply device, a sample table for holding a wafer to be ashed, and a vacuum exhaust device capable of decompressing the ashing chamber, wherein a plasma density distribution on the sample table in the ashing chamber is provided. Is configured to be higher in the outer peripheral portion than in the central portion. Plasma ashing processing equipment 2. The microwave according to claim 1, wherein a microwave is used as a plasma generator for supplying energy to a gas to be subjected to an ashing process, and a microwave oscillated by a microwave oscillator is introduced into a plasma generation space through a microwave propagation means. The microwave propagating means resonates the microwave propagating through the means in a specific mode, and the opening cross-sectional area of the space from the resonator to the plasma generation space is the propagation of the microwave. A plasma ashing processing apparatus comprising: a waveguide that gradually changes in a direction. 3. The plasma ashing processing apparatus according to claim 2, wherein the waveguide side of the resonator is a slit plate.