JP2003197608A - Method and apparatus for etching pyroelectric and high dielectric material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for etching a high dielectric substrate without generating a crack. <P>SOLUTION: The etching device is provided with a substrate tray 2 made of aluminum. The tray 2 is provided with; a receiving recess 2a, which is provided on the front face, for receiving a substrate 3 to be processed; a rear recess 2b which is formed on the rear side, i.e., at the position opposite to the receiving recess 2a; a peripheral contact surface 2c which is formed around the rear recess 2b, for contacting a substrate electrode; and a plurality of gas ducts 2d that extend from the rear recess 2b to the receiving recess 2a. The device is arranged such that the substrate 3 is fixed onto the tray 2 by clamp rings 7, and that cooling gas is made to flow onto the front face of the tray 2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching method and apparatus for processing a pyroelectric high dielectric constant material such as LiNbO ₃ or PZT which can be used in an optical modulator for an optical waveguide in plasma. .

[0002]

2. Description of the Related Art In a conventional etching apparatus of this type, the surface of a substrate electrode is covered with an anodic oxide film of 20 to 30 .mu.m in consideration of corrosion resistance, and a substrate pressing jig or a clamp material is made of alumina. The back surface of the holding jig or clamp remains the alumina base.

By the way, the main purpose of the substrate holding mechanism in the conventional etching apparatus has been to improve the thermal conductivity. Therefore, unlike a high dielectric constant material, there is no large gap between the surface potential and the back surface potential due to plasma irradiation, and high voltage (electrostatic) breakdown does not occur, so a substrate electrode structure that allows shape control and uniform etching I wish I had.
In the prior art, for example, using a metal mask, SiO
It is found that a slight undercut occurs when ₂ is etched. SiO ₂ does not react with active species in the plasma having no electric charge, and etching proceeds by ion bombardment. The mask metal is charged by the electric charge generated by a slight difference in the amount of ions and electrons reaching the surface, and a potential different from that inside the dielectric is generated. Therefore, it can be construed that the trajectory of the incident ions is bent by the action of the charges charged on the surface metal mask, resulting in undercut.

In the case of a dielectric material having a low dielectric constant, such a slight undercut occurs, but the problem of substrate crack does not occur. However, it has been confirmed in many experiments that a dielectric material having a high dielectric constant has a large amount of electric charges to reach electrostatic breakdown. In the experiments so far, when LiNbO ₃ was etched using Ar + C ₄ F ₈ plasma having a density of 10 ¹¹ cm ⁻³ , the substrate did not crack for 5 minutes, but cracked for 10 minutes. It was found that the cracking of the substrate was mainly due to uneven temperature and charge-up.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention provides an etching method and apparatus for eliminating the temperature unevenness and charge-up, which are the problems associated with the conventional apparatus as described above, and preventing the cracking of the substrate. The purpose is to do.

[0006]

To achieve the above object, according to the first aspect of the present invention, a gas is introduced into a vacuum chamber to form a high density plasma using microwaves or high frequencies. Then, in the etching device for processing the substrate by placing the substrate of the pyroelectric high dielectric material on the substrate electrode,
Form a receiving surface recess on the surface to receive the substrate to be processed,
A back surface recess is formed in the back surface portion corresponding to the substrate receiving surface recess, and a peripheral contact surface portion surrounding the back surface recess and contacting the substrate electrode is formed, and a plurality of gas flow passages penetrating from the back surface recess to the substrate receiving surface recess are formed. It has a substrate tray made of aluminum and is configured so that when it is mounted on the substrate electrode, the substrate is fixed on the substrate tray by a clamp ring and cooling gas can mainly flow to the surface side of the substrate tray. It is characterized by that.

The height from the concave portion on the back surface of the substrate tray to the peripheral contact surface portion is 5 to 100 μm, preferably 10 to 50 μm.
can be set to m.

In the etching apparatus of the present invention thus constructed, the cooling gas can be evenly flowed to the back surface and the front surface of the substrate tray on which the high dielectric substrate is mounted. On the other hand, it is possible to prevent the occurrence of temperature unevenness and thereby prevent the charge-up.

Further, according to the second aspect of the present invention, gas is introduced into the vacuum chamber to form high-density plasma using microwaves or high frequencies, and the pyroelectric high dielectric material is formed on the substrate electrode. In the etching method for processing the substrate by mounting the substrate of No. 2, a receiving surface recess is formed on the front surface for receiving the substrate to be processed, and the back surface recess is formed on the back surface corresponding to the substrate receiving surface recess on the front surface of the substrate tray. And a contact surface portion that surrounds the back surface recess and contacts the substrate electrode, and a substrate tray made of aluminum having a plurality of gas flow passages penetrating from the back surface recess to the substrate receiving surface recess is formed on the substrate electrode. It is characterized in that the substrate to be processed is mounted and the cooling gas is mainly flown to the surface side of the substrate tray.

In the etching method according to the present invention having such a structure, a cooling gas is mainly flown to the front side of the substrate tray supporting the substrate when the high dielectric substrate is etched, so that a good cooling efficiency is obtained. Will be able to.

In the method of the present invention, the leakage amount of the cooling gas supplied to the substrate tray may be set to 7 sccm or less so as to maintain the substrate temperature during processing at 100 ° C. or less.

In addition, the substrate placed on the substrate tray can be preferably held with a clamping force that does not give substantial mechanical stress to the substrate and can relieve the stress generated during the processing of the substrate. .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a main part of an etching apparatus according to an embodiment of the present invention used for etching a high dielectric substrate. In FIG. 1, 1 is a substrate electrode, which is made of aluminum and is arranged in a vacuum chamber (not shown). A substrate tray 2 is placed on the substrate electrode 1. On the surface of the substrate tray 2, a receiving surface concave portion 2a for receiving the substrate 3 of a pyroelectric high dielectric constant material such as LiNbO ₃ or PZT is formed, and the receiving surface concave portion 2a has the shape and the outer size of the substrate 3. The surface of the receiving surface concave portion 2a is configured to have high flatness and high smoothness, and a contact area with the substrate, which is an insulator, is as wide as possible. Further, on the back surface of the substrate tray 2, a back surface recess 2b is formed in a portion corresponding to the board receiving surface recess 2a, and this back surface recess 2b is defined by a peripheral contact surface portion 2c which contacts the board electrode 1. The peripheral contact surface portion 2c is formed with high flatness and high surface accuracy. Further, the substrate tray 2 is formed with a plurality of gas flow paths 2d penetrating from the back surface recess 2b to the substrate receiving surface recess 2a. The step difference between the bottom surface of the back surface recess 2b and the peripheral contact surface portion 2c on the back surface side of the substrate tray 2 is 5 to 100 μ from the viewpoint of obtaining good cooling efficiency by He gas.
m, preferably 10 to 50 μm.

As shown in the figure, the substrate electrode 1 is provided with a He gas passage 1a, and the outer end of the passage 1a is provided outside the vacuum chamber for mass flow meter 4 for adjusting the flow rate.
The He gas supply source 5 is connected via. Passage 1a
The inner end of the substrate is communicated with the back surface recessed portion 2b of the substrate tray 2, whereby the He gas is supplied from the He gas supply source 5 to the surface of the substrate tray 2 through the mass flow meter 4 and the passage 1a of the substrate electrode 1. Although it is made possible,
He gas can also be supplied to the back surface side.

A guide ring 6 for positioning the substrate tray 2 is arranged on the substrate electrode 1.
The substrate 3 placed on the substrate tray 2 positioned by the guide ring 6 is supported by the clamp ring 7 at three points in this embodiment. In this case, the substrate 3
The pressing force against should be set so as not to apply excessive mechanical stress to the substrate and to release the stress generated during the processing of the substrate. A high dielectric material such as alumina is generally a metal oxide as a constituent material of the clamp ring 7, and since alumina has a low etching rate and strong etching resistance, alumina is most suitable.

The operation of the illustrated apparatus thus configured will be described. A substrate placed on a substrate tray prepared in a loading chamber (not shown) is carried onto the substrate electrode 1 and positioned by the guide ring 6, and the peripheral contact surface portion 2c on the back surface side of the substrate tray 2 is moved to the substrate electrode 1 It is held in close contact with the surface of. He gas from the He gas supply source 5 to the rear surface and the front surface of the substrate tray 2 via the mass flow meter 4 and the passage 1a of the substrate electrode 1 was 1730 Pa.
The substrate tray 2 is set to a desired cooling temperature. In this case, preferably, the He gas introduced from the He gas supply source 5 through the mass flow meter 4 and the passage 1a of the substrate electrode 1 mainly flows along the front side of the substrate tray 2, that is, between the substrate 3 and the substrate tray 2. (Leaks)
Thus, the back surface side of the substrate tray 2, that is, the back surface of the substrate tray 2 and the substrate electrode 1 are retained but do not substantially flow (not leak).

FIG. 3 shows the result of measurement of the leakage amount of He gas in the substrate tray 2 under the following conditions. The pressure of He gas introduced into the substrate tray 2 from the He gas supply source 5 through the mass flow meter 4 and the passage 1a of the substrate electrode 1 was set to 1730 Pa, and LiNb was discharged without plasma discharge.
The O ₃ substrate was placed on the substrate tray 2 and measured.

Next, 100 sccm of a mixed gas of Ar and C ₄ F ₈ was introduced into a vacuum chamber (not shown),
The pressure in the vacuum chamber was set to 0.33 Pa, a high frequency power of 600 W was applied to a plasma forming induction coil (not shown), and a high frequency bias power of 350 W was applied to the substrate electrode 2.
It was applied and etched. As a result, the leakage amount of He gas in the substrate tray 2 is kept at 7 sccm or less during the etching time of 30 minutes, whereby the temperature of the substrate 3 is maintained at about 100 ° C. or less, and the temperature rise due to heat inflow during etching is suppressed. It was possible to suppress the thermal stress due to this, and it was possible to carry out etching for 30 minutes without causing substrate cracking.

FIG. 2 shows an essential part of an etching apparatus according to another embodiment of the present invention. Portions corresponding to those in FIG. 1 are denoted by the same reference numerals. In the structure shown in FIG. 2, instead of providing a step on the peripheral portion on the back surface side of the substrate tray 2, an annular cushioning material 8 having a thickness of 40 μm is attached. The other structure is substantially the same as that of the embodiment shown in FIG.

[0020]

As described above, in the etching apparatus according to the present invention, the receiving surface concave portion for receiving the substrate to be processed is formed on the front surface, and the rear surface concave portion is formed in the rear surface portion corresponding to the substrate receiving surface concave portion. A substrate tray made of aluminum that forms a peripheral contact surface portion that surrounds the back surface recess and contacts the substrate electrode, and that has a plurality of gas flow passages that penetrate from the back surface recess to the substrate receiving surface recess, and that has a substrate tray on the substrate electrode. When mounted, the substrate is fixed on the substrate tray by a clamp ring, and the cooling gas is mainly supplied to the surface side of the substrate tray. There is an effect that unevenness and charge-up due to it can be suppressed, and high dielectric processing can be performed without causing substrate cracking.

Further, in the etching method according to the present invention, the receiving surface recess for receiving the substrate to be processed is formed on the front surface, and the back surface recess and the back surface are formed on the surface of the substrate tray corresponding to the substrate receiving surface recess. It should be processed on the substrate electrode by using a substrate tray made of aluminum that forms a contact surface portion that surrounds the concave portion and is in contact with the substrate electrode, and forms a plurality of gas flow passages that penetrate from the rear surface concave portion to the substrate receiving surface concave portion. By mounting the substrate and flowing the cooling gas mainly along the surface side of the substrate tray, good cooling efficiency for the substrate is obtained, so that the substrate can be maintained at a substantially uniform temperature during processing. It is possible to suppress temperature unevenness and charge-up due to the temperature unevenness, and it is possible to perform high dielectric processing without causing substrate cracking.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a main part of an etching apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing the main parts of an etching apparatus according to another embodiment of the present invention.

FIG. 3 is a graph showing the measurement results of He gas leakage in the substrate tray.

[Explanation of symbols]

1: Substrate electrode 1a: gas passage 2: Substrate tray 2a: Recessed surface recess 2b: recess on the back surface 2c: Surrounding contact surface 2d: Gas flow path 3: Substrate of pyroelectric high dielectric constant material 4: Mass flow meter 5: He gas supply source 6: Guide ring 7: Clamp ring

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[Procedure amendment]

[Submission date] January 21, 2002 (2002.1.2
1)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

Continued front page    (72) Inventor Toshio Kato             1220-14 Suyama, Susono, Shizuoka Al             Back Fuji Susono Factory (72) Inventor Takeshi Igarashi             1220-14 Suyama, Susono, Shizuoka Al             Back Fuji Susono Factory (72) Inventor Koji Maeba             1220-14 Suyama, Susono, Shizuoka Al             Back Fuji Susono Factory F-term (reference) 2H079 AA02 DA03 DA04 JA07                 5F004 BA20 BB21 BB25 BB28 BC03                       CA02 CA04 DA00 DA22 DB13

Claims (5)

[Claims] 1. An etching apparatus for processing a substrate by introducing a gas to form high-density plasma using microwaves or high frequencies, placing a substrate of a pyroelectric high dielectric material on a substrate electrode, and processing the substrate. Forming a receiving surface recess on the front surface for receiving the substrate to be processed, forming a back surface recess in a portion of the back surface corresponding to the substrate receiving surface recess, and a peripheral contact surface part surrounding the back surface recess and contacting the substrate electrode, It has a substrate tray made of aluminum having a plurality of gas flow passages penetrating from the recess on the back surface to the recess on the receiving surface of the substrate. When the substrate tray is mounted on the substrate electrode, the substrate is fixed by the clamp ring on the substrate tray and mainly An apparatus for etching a pyroelectric high dielectric material, characterized in that a cooling gas is made to flow to the surface side of the. 2. The pyroelectric high-dielectric etching apparatus according to claim 1, wherein the height from the recessed portion on the back surface of the substrate tray to the peripheral contact surface portion is 5 to 100 μm. 3. A substrate is processed by introducing a gas into a vacuum chamber to form high-density plasma using microwaves or high frequencies, placing a substrate of a pyroelectric high dielectric material on a substrate electrode. In the etching method, a receiving surface recess is formed on the surface to receive the substrate to be processed, and a back surface recess is formed in the back surface portion corresponding to the substrate receiving surface recess on the surface of the substrate tray.
Formed on the substrate electrode by using a substrate tray made of aluminum that forms a contact surface portion that surrounds the back surface recess and contacts the substrate electrode, and forms a plurality of gas flow passages that penetrate from the back surface recess to the substrate receiving surface recess A method for etching a pyroelectric high-dielectric, characterized in that a substrate to be mounted is mounted and cooling gas is caused to flow mainly along the surface side of the substrate tray. 4. The substrate temperature during processing is set to 100 sccm by setting the leakage amount of the cooling gas supplied to the substrate tray to 7 sccm or less.
The method for etching a pyroelectric high dielectric material according to claim 3, wherein the etching temperature is maintained at a temperature of not higher than 0 ° C. 5. A substrate to be placed on a substrate tray is held by a clamping force that does not apply substantial mechanical stress to the substrate and can release stress generated during processing of the substrate. The method for etching a pyroelectric high dielectric material according to claim 3.