JP2001210495A - Plasma treatment device and plasma treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the potential difference at a base board placing surface of an electrode which places the treated base board, and to enable the treated base board to treat a plasma evenly. SOLUTION: A lower electrode 5 placing the treated base board 4 is formed in conical shape that the opposite side against the base board placing surface 5a reduces the diameter, and a high-frequency impressing part 5b is connected to the apex part of the one. By the above, as the distance from the high-frequency impressing part 5b becomes nearly even at the whole part of the base board placing surface 5a, a high-frequency 11 reaches the whole part of the base board placing surface 5a almost simultaneously, accordingly, the phase shift and the potential difference caused by the phase shift between center part and peripheral part of the base board placing surface 5a is reduced.

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 such as a dry etching apparatus, a sputtering apparatus, and a CVD apparatus used for manufacturing a semiconductor or a liquid crystal display device (LCD). The present invention relates to a plasma processing apparatus and a plasma processing method capable of improving the above uniformity.

[0002]

2. Description of the Related Art In recent years, in the manufacturing process of semiconductors and liquid crystal substrates, high integration and large diameter have been progressing, and technical requirements for plasma processing with further finer patterns have been increasing more and more. The technical requirements are, for example, in the case of a semiconductor etching process, achieving high selectivity to an etching mask and an underlying material layer, good shape controllability, a practical etching rate, low damageability, and good reproducibility. It is. Clearing these conditions on the entire surface of the wafer leads to an improvement in device yield and performance. For this purpose, it is necessary to perform the plasma processing uniformly over the entire surface of the wafer, and various methods have been conventionally used for that purpose.

As a conventional plasma processing apparatus, there is an etching apparatus as shown in FIG. In this etching apparatus, an upper electrode 22 is provided in an upper portion of a vacuum vessel 21, and a lower electrode 24 on which a substrate 23 is placed is provided below the upper electrode 22. The system is evacuated and controlled to a predetermined pressure while introducing a reaction gas 26 through a gas passage 22 a and a gas outlet 22 b formed in the upper electrode 22. Then, in this state, high-frequency power is applied from a high-frequency power supply 28 to the high-frequency application section 24a of the lower electrode 24 via the capacitor 27 to excite plasma in the vacuum vessel 21, and radicals existing in the plasma are excited.
The substrate 23 to be processed is etched by the ions.

[0004]

However, in a conventional plasma processing apparatus such as the above-described etching apparatus, as shown in the drawing, the lower electrode 24 on which the substrate 23 to be processed is mounted has an area of the substrate mounting surface 24b. The high-frequency applying portion 24a is set at the center of the lower surface or in the vicinity thereof, and is incident on the substrate 23 to be processed. No consideration was given to the fact that the energy of the ions to be processed differs between the central portion and the outer peripheral portion of the substrate 23 to be processed.

That is, in such a lower electrode 24, assuming that the difference between the distance L11 from the high-frequency applying portion 24a to the center of the substrate mounting surface 24b and the distance L12 from the outer peripheral portion is constant, the electrode thickness is constant. It becomes larger as the mounting surface 24b becomes larger in diameter. Therefore, the high-frequency wave reaching the substrate mounting surface 24b is viewed at the same time, and the high-frequency
The phase differs between the central portion and the outer peripheral portion of the substrate mounting surface 24b, and as a result, the substrate mounting surface 24b
Tend to be lower at the center and higher at the outer periphery. This is considered to be because interference is caused by high frequencies from other parts, and a standing wave is generated on the electrode depending on the size of the lower electrode 24. Then, due to the potential difference on the substrate mounting surface 24b, the energy of ions reaching the substrate 23 to be processed becomes non-uniform. This tendency becomes more remarkable as the size of the lower electrode 24 increases.

Therefore, even if uniform plasma is generated,
There is a problem that the plasma processing speed is not uniform in the surface of the substrate 23 to be processed. SUMMARY OF THE INVENTION The present invention solves the above-described problems, and can reduce a potential difference between an electrode on which a substrate to be processed is mounted on a substrate mounting surface, and can uniformly perform plasma processing on the substrate to be processed and a plasma processing method. The purpose is to provide.

[0007]

According to the present invention, in order to achieve the above object, the shape of the electrode is cone-shaped or cone-shaped so that the distance from the high-frequency application point to the substrate mounting surface is uniform over the entire surface of the substrate mounting surface. This is a shape close to that, whereby the high frequency of the same phase reaches the substrate mounting surface regardless of whether it is the inner peripheral portion or the outer peripheral portion.

[0008]

According to the first aspect of the present invention, an electrode for mounting a substrate to be processed is disposed inside a vacuum vessel, and plasma is generated by high-frequency power applied between the electrode and a counter electrode. In the plasma processing apparatus for processing the substrate to be processed, the electrode is formed in a cone shape having a diameter reduced on a side opposite to the substrate mounting surface, and a high-frequency application unit to which high-frequency power is applied is provided at the top. Features.

According to the above configuration, since the distance from the high-frequency application section uniformly approaches the entire surface of the substrate mounting surface, the high-frequency waves arrive at substantially the same time over the entire surface of the substrate mounting surface. Of the high-frequency phase between the central portion and the outer peripheral portion, and the potential difference resulting therefrom can be reduced, and the plasma processing can be performed uniformly. As the cone shape, various shapes such as a conical shape, a triangular pyramid shape, a quadrangular pyramid shape, and a shape close thereto are possible.

According to a second aspect of the present invention, in the configuration of the first aspect, a non-uniform dielectric constant portion is formed inside the cone-shaped electrode. With the above configuration, the high frequency wave reaches the substrate mounting surface by changing the speed and direction at the non-uniform dielectric constant portion, and the phase shift of the high frequency in the central portion and the outer peripheral portion of the substrate mounting surface becomes smaller. .

According to a third aspect of the present invention, in the configuration of the second aspect, the non-uniform dielectric constant portion is a void portion. According to the above configuration, the high frequency wave reaches the substrate mounting surface while changing the speed and direction at the portion having the non-uniform dielectric constant.

According to a fourth aspect of the present invention, a substrate to be processed is mounted on a substrate mounting surface of a cone-shaped electrode provided inside a vacuum vessel, and is provided on the top of the electrode while supplying a reaction gas. And applying the high-frequency power to the high-frequency applying unit and transmitting the high-frequency power to the substrate mounting surface, and processing the substrate to be processed by the plasma generated between the high-frequency applying unit and the counter electrode.

With the above structure, the high-frequency wave propagates over a substantially uniform distance from the high-frequency applying section to each position on the substrate mounting surface and arrives at the same time, so that the central portion and the outer peripheral portion of the substrate mounting surface are separated from each other. , The potential difference caused by the phase shift of the high frequency can be reduced, and the plasma processing can be performed uniformly.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. (Embodiment 1) An RIE (reactive ion etching) apparatus in a dry etching step will be described as a plasma processing apparatus according to Embodiment 1 of the present invention.

In FIG. 1, reference numeral 1 denotes a vacuum container, and 2 denotes a vacuum pump for evacuating the vacuum container 1. Reference numeral 3 denotes an upper electrode provided inside the vacuum vessel 1, reference numeral 4 denotes a substrate to be processed such as a semiconductor silicon wafer or a liquid crystal substrate,
Reference numeral 5 denotes a lower electrode placed on the insulating plate 6 so as to face the upper electrode 3.

The upper electrode 3 has a gas passage 3a inside and a plurality of gas outlets 3b on the lower surface, and communicates with an external gas supply source (not shown) at a gas supply port 3c. I have. 7 is a ground for the upper electrode 3.

The lower electrode 5 is made of ceramic or the like, is provided with an electrostatic chucking electrode on the substrate mounting surface 5a, has a substantially truncated conical shape with a reduced diameter on the side opposite to the substrate mounting surface 5a, and has a central top portion. A high-frequency power supply 9 is connected to the high-frequency application unit 5b via a matching device such as a capacitor 8.

The operation of the above configuration will be described. The target substrate 4 is placed on the substrate setting surface 5a of the lower electrode 5 and electrostatically attracted. Next, the air in the vacuum vessel 1 is exhausted by the vacuum pump 2, and the reaction gas (etching gas) 10 supplied from the gas supply source is supplied to the inside of the vacuum vessel 1 through the gas supply port 3c, the gas passage 3a, and the gas outlet 3b. While controlling to a predetermined pressure. Thereafter, high-frequency power is applied from a high-frequency power source 9 to a high-frequency application unit 5b of the lower electrode 5 via a capacitor 8 to excite plasma in the vacuum chamber 1, and radicals and ions present in the plasma cause the substrate 4 to be processed.
Is etched.

At this time, the high frequency 11 applied to the lower electrode 5 from the high frequency power supply 9 with the high frequency applying section 5b as an application point reaches the substrate mounting surface 5a through the inside and the surface of the lower electrode 5.

At this time, since the lower electrode 7 has a truncated cone shape, the distance from the high-frequency application unit 5b to the substrate mounting surface 5a is, for example, L1 up to the center and L1 up to the outer periphery.
2 and the difference between the two electrodes L1 and L2 is smaller than that of the conventional disk-shaped lower electrode. For this reason, unlike the conventional disc-shaped lower electrode, high-frequency waves having substantially the same phase are transmitted to the entire surface of the substrate mounting surface 5a, and the potential on the substrate mounting surface 5a increases in uniformity. Further, the influence of high-frequency interference and standing waves from other positions is reduced.

As a result, the uniformity of the ion energy reaching the target substrate 4 is improved, and the target substrate 4 is uniformly plasma-processed. (Embodiment 2) As shown in FIG. 2, the plasma processing apparatus according to Embodiment 2 of the present invention is the same as the RIE apparatus described in Embodiment 1 except that the lower electrode 5 has a diamond-shaped void inside. 12 is formed.

According to this configuration, the high frequency 11 is applied to the gap 1
2 and arrives at the substrate mounting surface 5a, the distance from the high-frequency application section 5b to the substrate mounting surface 5a becomes more uniform over the entire surface of the substrate mounting surface 5a.
A high frequency wave having substantially the same phase is transmitted to the entire surface of a.

As a result, the uniformity of the ion energy reaching the substrate 4 to be processed is further improved, and the substrate 4 to be processed is more uniformly plasma-processed. In the above, RI
The E apparatus has been described as an example.
The same effect can be obtained in other plasma processing apparatuses such as a (chemical vapor deposition) apparatus by using the above-described electrodes. Even when the substrate 4 to be processed is installed in the vertical direction, the same effect can be obtained by using the electrodes having the above-described shapes.

The shape of the gap 12 may be variously changed, such as a spindle type, so that high-frequency waves having substantially the same phase are transmitted to the entire surface of the substrate mounting surface 5a. Alternatively, a material having a different dielectric constant from the outer peripheral portion may be arranged. For example, a ceramic or a fluid (water, ethylene glycol, or the like) is arranged in a portion corresponding to the gap portion 12,
The outer periphery can be aluminum.

[0025]

According to the present invention, as is apparent from the above description, the electrode on which the substrate to be processed is mounted is formed in a cone shape, and the high frequency application section is provided on the top thereof, so that the transmission from the high frequency application section is achieved. Thus, the potential due to the high frequency is made more uniform over the entire surface of the substrate mounting surface than before, so that uniform energy can be incident on the entire surface of the substrate to be processed, and plasma processing can be performed uniformly.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of a plasma processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view illustrating a schematic configuration of a plasma processing apparatus according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing a schematic configuration of a conventional plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Vacuum pump 3 Upper electrode 4 Substrate to be processed 5 Lower electrode 5a Substrate installation surface 5b High frequency application part 9 High frequency power supply 10 Reaction gas 11 High frequency 12 Void

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/31 H01L 21/302 C (72) Inventor Masaki Suzuki 1006 Ojidoma, Kazuma, Osaka Matsushita Electric Industrial Incorporated F term (reference) 4K030 CA04 CA06 DA04 FA03 KA15 LA15 LA18 4K057 DA16 DA20 DD03 DM03 DM06 DM08 DN01 5F004 AA01 BA04 BA06 BB29 BD04 BD05 5F045 AA08 BB02 DP02 EH04 EH08 EH13

Claims (4)

[Claims] 1. A plasma processing apparatus in which an electrode for mounting a substrate to be processed is disposed inside a vacuum vessel, and plasma is generated by high-frequency power applied between the electrode and a counter electrode to process the substrate to be processed. 3. The plasma processing apparatus according to claim 1, wherein the electrode is formed in a cone shape having a reduced diameter on a side opposite to the substrate mounting surface, and a high-frequency application unit to which high-frequency power is applied is provided at the top. 2. The plasma processing apparatus according to claim 1, wherein a non-uniform dielectric constant portion is formed inside the cone-shaped electrode. 3. The plasma processing apparatus according to claim 2, wherein the non-uniform dielectric constant portion is a void. 4. A substrate to be processed is mounted on a substrate mounting surface of a cone-shaped electrode provided inside a vacuum vessel, and a high-frequency application section provided on the top of the electrode is supplied with a reactive gas while supplying a reactive gas. A plasma processing method, comprising applying electric power to propagate to a substrate mounting surface, and processing a substrate to be processed by plasma generated between the substrate and a counter electrode.