JPH04361529A - Microwave plasma generator - Google Patents

Abstract

PURPOSE:To enable plasma processing efficiency to be increased while a specimen to be finely processed by perpendicularly irradiating the specimen with the line of magnetic force and ions in the title microwave plasma generator provided with a reaction chamber producing plasma using microwaves and magnetic field. CONSTITUTION:The title microwave plasma producer is to be a cavity resonator-structured for exciting an electron cyclotron resonator between a surface 9 having microwave leading-in ports 8 of a waveguide 1 and the mounting surface 4a of a conductive supporting base 4 to mount a semiconductor wafer 3. In such a constitution, the plasma can be produced by the microwaves fed by the waveguide 1 and the magnetic field developed by the magnetizing step of the magnetic field developing coil 17 of a magnetic field formation means 2 so that the surface of the semiconductor wafer 3 may be perpendicularly irradiated with the ions contained in the plasma and the line of magnetic force A. Through the procedures, the plasma processing efficiency can be increased while enabling the semiconductor wafer 3 to be finely processed.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a microwave plasma device, and more specifically, a microwave plasma device that generates plasma using microwaves and a magnetic field to perform etching or film-forming processing on a sample such as a semiconductor wafer. It is related to.

0002

[Background Art] With the miniaturization and higher quality of semiconductor products in recent years, in the semiconductor manufacturing process, high-density plasma is generated using microwaves and a magnetic field generated by passing a current through a ring-shaped coil. Microwave plasma equipment is used for etching or film formation.

In a conventional microwave plasma device of this type, a microwave inlet is provided in a plasma generation chamber having a magnetic field generating means to form an electron cyclotron resonance cavity, and ions are extracted from the plasma generation chamber to generate a semiconductor in the reaction chamber. A device that irradiates a wafer with an ion beam (Special Publication Act 1982-
(Refer to Publication No. 13626), or by making the discharge tube that generates plasma by introducing microwaves into a structure that expands beyond the main discharge part from the direction of microwave introduction toward the sample, making it possible to perform plasma treatment over a wide area. (see Japanese Unexamined Patent Publication No. 59-202635), etc. are known.

0004

[Problems to be Solved by the Invention] However, the former, that is, the one described in Japanese Patent Publication No. 13626/1983,
Not only does the entire device become large because it has a plasma generation chamber and a reaction chamber, but in order to efficiently irradiate semiconductor wafers with ions from plasma using an electric field, a high voltage of around 1000 V is required, which increases the energy of the ions. The problem was that it was expensive. In order to solve this problem, it is possible to reduce power consumption by placing the sample in plasma, for example, but with such a structure, the microwaves are absorbed by the sample as heat, making the sample high temperature, which may lead to quality problems. There is a problem in that it causes a decrease in In addition, in the latter case, that is, the one described in JP-A No. 59-202635, the magnetic lines of force generated by passing a current through a ring-shaped coil are not perpendicular to the sample surface but are inclined, so that the sample surface is not affected by the etching process, for example. There is a problem in that the magnetic field is tilted in the direction of the magnetic field lines, making it impossible to perform perpendicular etching and making microfabrication difficult.

[0005] This invention was made in view of the above-mentioned circumstances, and it supplies a low-energy, high-density plasma to a sample.
The object of the present invention is to provide a microwave plasma apparatus that enables plasma processing without heating a sample by microwaves.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the microwave plasma device of the present invention generates plasma using microwaves introduced from a microwave introducing means and a magnetic field formed by a magnetic field forming means. In a microwave plasma apparatus comprising a reaction chamber, the reaction chamber is configured to generate electron cyclotron resonance between a surface of the microwave introduction means having a microwave introduction port and a surface of a conductive support on which a sample is placed. It has an exciting cavity resonator structure.

In the present invention, in order to form the reaction chamber composed of the microwave inlet and the support into an electron cyclotron resonant cavity structure, the wavelength may be an integral multiple of 1/2 of the wavelength of the microwave. Further, as long as the magnetic field lines and ions are irradiated perpendicularly to the sample placed on the support, the distance between the sample and the microwave inlet may be arbitrary, but it is preferable that the sample be placed on the support. The sample to be mounted is placed at 1/2 the wavelength of the microwave in the reaction chamber from the microwave inlet.
It is better to locate it in an area that is an integral multiple of .

[0008] The microwave introduction port may be a single opening as long as it introduces microwaves into the reaction chamber via a microwave introduction means connected to a microwave supply source, but is preferably a plurality of slits. It is better to form the In this case, as the microwave introduction means, for example, a rectangular waveguide having a plurality of microwave introduction ports or a radial waveguide having a plurality of microwave introduction ports in the radial direction can be used. Furthermore, the microwave may be supplied to the microwave introducing means either horizontally or vertically.

[0009]

[Operation] According to the microwave plasma apparatus of the present invention configured as described above, the reaction chamber is located between the surface of the microwave introduction means having the microwave introduction port and the surface of the support base on which the sample is placed. As a cavity resonator structure that excites electron cyclotron resonance at No heat is absorbed and overheating of the sample is prevented.

[0010] Furthermore, the sample placed on the support table is placed at one wavelength of the microwave in the reaction chamber from the microwave inlet.
By locating it in an area that is an integer multiple of /2, the microwave and electron behavior resonate to the maximum in the area of 1/4 wavelength of the microwave wavelength above the sample, and plasma is generated with maximum intensity. The maximum plasma generation position and the sample position can be separated by 1/4 of the microwave wavelength.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below in detail with reference to the drawings.

◎First Embodiment FIG. 1 is a cross-sectional view of a first embodiment in which the microwave plasma device of the present invention is applied to an etching device, and FIG. 2 is a partial cross-section of the microwave introducing means in the first embodiment. A perspective view is shown.

The microwave plasma apparatus of the present invention includes a rectangular waveguide 1 as a microwave introducing means, a magnetic field forming means 2, and a support base 4 on which a semiconductor wafer 3 as a sample (hereinafter referred to as wafer) is placed. The main part is composed of a reaction chamber 5 in which a reaction chamber 5 is arranged.

In this case, the reaction chamber 5 includes a box-shaped device main body 6 made of a non-magnetic material such as aluminum alloy or stainless steel, and a quartz glass that transmits microwaves in the upper opening of the device main body 6. A rectangular waveguide 1 disposed via 7 and a microwave inlet 8 of this rectangular waveguide 1
It has a cavity resonator structure that excites electron cyclotron resonance, which is composed of a surface 9 having a wafer 3 and a conductive support 4 having a surface 4a on which a wafer 3 is placed opposingly. That is,
A surface 9 having a microwave inlet 8 and a mounting surface 4 of the support base 4
When the distance to a is the microwave wavelength λg,
(λg/2)×n (integer), the reaction chamber 5 can have a cavity resonator structure that excites electron cyclotron resonance in TE mode or TEM mode. Therefore, since the wafer 3 is located on the microwave reflecting surface, it is possible to prevent the adverse effect of being heated by the microwave. The configuration is such that microwaves and electron behavior resonate at maximum in the region and plasma is generated at maximum intensity (see FIG. 3).

[0015] Also, in this reaction chamber 5, for example, Cl2
, SF6, CF4, etc. supply port 10a,
10b, and an exhaust port 11 connected to an exhaust means (not shown)
is provided so that the inside of the reaction chamber 5 can be maintained at a predetermined vacuum atmosphere. The quartz glass 7 is attached to the device main body 6 via an O-ring 12 to maintain a vacuum, and the exhaust port 11 is equipped with a filter 13 that does not allow microwaves to pass through, for example, in the form of a conductive mesh. It is provided.

As shown in FIG. 2, the rectangular waveguide 1 is formed in a flat hollow rectangular shape to be connected to a magnetron 14 which is a microwave supply source, and has a plurality of slit-shaped microwave introduction ports on its lower surface. 8, 8... are bored at appropriate intervals. Further, a microwave absorber 1a is provided at the tip of the rectangular waveguide 1, and the microwave absorber 1a prevents the reflected waves generated within the rectangular waveguide 1 from being returned to the magnetron 14. The waves are absorbed, and by cooling the absorber 1a, the rectangular waveguide 1 is prevented from being heated by the microwaves. Further, the opening of the microwave inlet 8 is, for example, 1 cm when the wavelength of the microwave in the rectangular waveguide 1 is λt.
×(λt/2).

The magnetic field generating means 2 includes upper and lower magnetic poles 15 and 16 arranged oppositely on the upper and lower sides of the device body 6, and magnetic field generating coils 17 and 17 wound around these magnetic poles 15 and 16, respectively. It is comprised of a yoke 19 made of a good magnetic material, such as soft iron, which connects the upper magnetic pole 15 and the lower magnetic pole 16 via a permanent magnet 18. Then, the frequency of the microwave is set to 2.45 GHz by the magnetic field forming means 2, for example.
At this time, a magnetic field of 875 Gauss is generated, and lines of magnetic force A perpendicular to the wafer 3 in the reaction chamber 5 can be obtained.

In the microwave plasma apparatus of the present invention constructed as described above, the magnetron 1 outside the apparatus is
The microwaves supplied from 4 to the rectangular waveguide 1 are introduced into the reaction chamber 5 from a microwave inlet 8. Further, by excitation of the permanent magnet 18 and the magnetic field generating coil 17 of the magnetic field forming means 2, a magnetic field of 875 Gauss is formed in the reaction chamber 5 when the frequency of the microwave is 2.45 GHz, for example. Then, the reactive gas supplied into the reaction chamber 5 is transferred to the wafer 3.
After efficiently generating plasma at a position λg /4 above the support base 4 on which the ions are placed, the ions in the plasma are
By irradiating the wafer 3 in the direction of , that is, in the direction perpendicular to the wafer 3, the wafer 3 can be etched vertically. In this case, if the high frequency power source 20 is connected to the support base 4 as shown by the imaginary line in FIG. can do well.

In the above explanation, since the quartz plate 7 is brought into contact with the surface 9 of the rectangular waveguide 1 having the microwave inlet 8, the position where the maximum plasma intensity is generated is located at the support base where the microwave amplitude is greatest. Above (1/4)×λg of 4 and (3
/4)×λg, but as shown in FIG. 4, if the quartz plate 7 is placed above the wafer 3 at a position (1/2)×λg, the reactive gas can be turned into plasma. The maximum intensity position is at one position (1/4) x λg above the support table 4, and the plasma is generated in a planar shape on the wafer 3, making it possible to perform good etching. Note that etching the wafer 3 in the plasma generating section is not suitable for vertical etching because the directionality of ions and radicals is random. Note that in FIG. 4, other parts are the same as those in FIG. 1, so the same parts are given the same reference numerals and the explanation thereof will be omitted.

◎Second Embodiment FIG. 5 is a sectional view of a second embodiment in which the microwave plasma apparatus of the present invention is applied to an etching apparatus, and FIG.
FIG. 7 is a partially sectional perspective view of the microwave introducing means in the second embodiment.

The second embodiment uses a waveguide that supplies microwaves from the vertical direction. That is, as shown in FIG. 7, the waveguide attached to the upper opening of the device main body 6 via the quartz glass 7 is a radial waveguide 21 having a plurality of slit-shaped microwave introduction ports 8, 8, . . . in the radial direction. This is the case where a coaxial cable 23 connected to a magnetron (not shown) is connected to an opening 22 formed at the center of the upper part of the radial waveguide 21. In this case, the yoke 19 that connects the upper and lower magnetic poles 15 and 16 is arranged into four symmetrical sections with respect to the vertical center of the device, forming a plurality of magnetic circuits. It is configured so that a magnetic field can be obtained.

[0022]A microwave absorber 1a is attached around the radial waveguide 21, similar to the rectangular waveguide 1. Further, in the second embodiment, other parts are the same as those in the first embodiment, so the same parts are given the same reference numerals and the explanation thereof will be omitted.

Although the above embodiment describes the case where a microwave plasma device is applied to an etching device, it is not necessarily applied only to an etching device, but can also be applied to other devices that require plasma processing, such as a plasma CVD device, etc. It can also be used for

[0024]

[Effects of the Invention] As explained above, according to the microwave plasma apparatus of the present invention, which is constructed as described above, the following effects can be obtained.

1) According to the microwave plasma apparatus according to claim 1, the reaction chamber is located between the surface of the microwave introduction means having the microwave introduction port and the surface of the conductive support base on which the sample is placed. Because of the electron cyclotron resonance cavity structure, the support plate serves as a reflection plate for the cavity that excites electron cyclotron resonance, so the microwaves are not absorbed by the sample as heat, preventing overheating of the sample. can be prevented. In addition, since the position of the surface where the maximum intensity of plasma is generated can be set at a position 1/4 of the microwave wavelength away from the surface of the support base on which the sample is placed, high-density plasma can be used to can be processed.

2) According to the microwave plasma apparatus according to claim 2, the sample placed on the support stand is located in an area from the microwave inlet to an integral multiple of 1/2 of the wavelength of the microwave in the reaction chamber. This makes it possible to prevent the adverse effects of microwaves on the sample, and to perform plasma processing on the sample even more efficiently.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of a microwave plasma device of the present invention.

FIG. 2 is a partially cross-sectional perspective view showing microwave introducing means in the first embodiment.

FIG. 3 is a schematic cross-sectional view showing the placement position of a sample in the present invention.

FIG. 4 is a sectional view showing another form of the first embodiment.

FIG. 5 is a sectional view showing a second embodiment of the microwave plasma device of the present invention.

FIG. 6 is a plan view of FIG. 5;

FIG. 7 is a partially cross-sectional perspective view showing microwave introduction means in a second embodiment.

[Explanation of symbols]

1 Rectangular waveguide (microwave introducing means) 2 Magnetic field forming means 3 Semiconductor wafer (sample) 4 Support table 4a Placement surface 5 Reaction chamber 8 Microwave inlet 9 Surface with microwave inlet 15 Upper magnetic pole 16 Lower magnetic pole 17 Magnetic field Generation coil 19 Yoke

Claims (2)

[Claims] 1. A microwave plasma device comprising a reaction chamber that generates plasma using microwaves introduced from a microwave introducing means and a magnetic field formed by a magnetic field forming means, wherein the reaction chamber is connected to the microwave introducing means. A microwave plasma device characterized by having a cavity resonator structure that excites electron cyclotron resonance between a surface having a microwave inlet and a surface of a conductive support on which a sample is placed. [Claim 2] The sample placed on the support table is placed at a distance of 1/1 of the wavelength of the microwave in the reaction chamber from the microwave inlet.
2. The microwave plasma apparatus according to claim 1, wherein the microwave plasma apparatus is located in an area that is an integral multiple of 2.