JP2008118015A - Focus ring and plasma processing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focus ring by which in-plane uniformity of etching is improved and which is prevented from being scraped by etching. <P>SOLUTION: High frequency power which is applied to a lower electrode 3 is prevented from being transmitted around a substrate B to be treated by an intermediate member 22 which is positioned between a lower member 21 and an upper member 23. The etching rate around the substrate B to be treated is suppressed and the in-plane uniformity of etching can be improved. Also, scraping of the focus ring 15 by etching can be prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a focus ring and a plasma processing apparatus, which are disposed so as to surround a substrate to be processed on a lower electrode on which a substrate to be processed for predetermined plasma processing is placed and a high frequency power is applied.

  Conventionally, fine etching processing is possible when design rules such as signal lines, scanning lines, or gate lines of various semiconductor devices and TFT (thin film transistor) liquid crystal devices used for an array substrate of a liquid crystal panel as a liquid crystal display device become fine. Dry etching is generally used.

  In such a dry etching apparatus for dry etching, an electrode for placing a substrate to be processed is disposed in a vacuum chamber, and a high frequency power source is connected to each of the electrodes. An etching gas supply pipe and a discharge pipe are connected to the vacuum chamber.

  In this dry etching apparatus, high-frequency power is applied to the electrodes in the vacuum chamber from a high-frequency power source, thereby generating plasma in the vacuum chamber and decomposing the etching gas to generate active species. Etching is performed by making ions enter the etching target film of the substrate to be processed formed on the substrate with the active species.

In such a dry etching apparatus, a focus ring is disposed around the lower electrode so that plasma is confined and plasma discharge is applied only to the substrate to be processed (see, for example, Patent Document 1).
JP 2005-277369 A

  However, in the above-described focus ring, the applied high-frequency power is transmitted through the focus ring, and the phenomenon that the etching rate of the peripheral portion of the substrate to be processed is likely to be faster than that of the central portion. The etching apparatus has a problem that this phenomenon appears remarkably.

  Further, the lower electrode application type dry etching apparatus has a problem that the focus ring is also etched when the power of the high frequency power is increased in a low pressure (high vacuum) state in the vacuum chamber.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a focus ring and a plasma processing apparatus that improve the in-plane uniformity of etching and prevent abrasion due to etching.

  The present invention is a focus ring that is disposed around a periphery of the substrate to be processed on a lower electrode on which a substrate to be processed for predetermined plasma processing is placed and high frequency power is applied, and a lower member; An intermediate member disposed on the upper part of the lower member, and an upper member disposed on the upper part of the lower member so as to cover the intermediate member.

  Then, the intermediate member positioned between the lower member and the upper member prevents the transmission of high-frequency power in the peripheral portion of the substrate to be processed.

  According to the present invention, the etching rate of the peripheral portion of the substrate to be processed can be suppressed, the in-plane uniformity of etching can be improved, and the focus ring can be prevented from being scraped by etching.

  The configuration of the focus ring according to the first embodiment of the present invention will be described below with reference to FIG.

  In FIG. 1, reference numeral 1 denotes a dry etching apparatus as a plasma processing apparatus. The dry etching apparatus 1 is a so-called parallel plate type reactive ion etching (RIE) type.

  That is, the dry etching apparatus 1 includes a vacuum chamber 2 as a processing chamber having a processing chamber R therein, and a lower electrode serving as a mounting table for the substrate B to be processed is provided in the processing chamber R in the vacuum chamber 2. 3 is provided at the lower portion, and a gas shower plate 4 as an upper electrode is provided above the lower electrode 3 so as to face the lower electrode 3 substantially in parallel. Further, a gas introduction part (not shown) is provided in the upper part of the vacuum chamber 2, and an etching gas can be introduced into the processing chamber R from the gas introduction part. 2 can be exhausted by exhaust parts 5 and 5 for exhaust provided in the lower part of 2. Further, an opening 7 through which the substrate to be processed B can be taken in and out is provided at the side of the vacuum chamber 2.

  The lower electrode 3 is made of, for example, a conductive material such as aluminum, and a holding mechanism (not shown) such as an electrostatic chuck for holding the substrate B to be processed is provided on the upper surface. The lower electrode 3 is electrically connected to a high frequency (RF) power source 11 as high frequency power application means, and is configured to be supplied with high frequency power of a predetermined frequency from the high frequency power source 11. In addition, a flow path (not shown) for controlling the temperature of the lower electrode 3 or the substrate to be processed B through which a heat medium such as helium gas supplied through the supply pipe 12 passes through the lower electrode 3. Is formed.

  Further, a fitting recess 14 is cut out on the outer peripheral edge of the upper side of the lower electrode 3 so as to surround the peripheral edge of the substrate B to be processed. 15 is fitted.

  Here, the focus ring 15 includes a lower member 21 placed in the fitting recess 14, an intermediate member 22 disposed on the upper portion of the lower member 21, and an upper portion of the lower member 21 covering the intermediate member 22. The upper member 23 is disposed.

  The lower member 21 is formed in an annular shape with, for example, Teflon (registered trademark), which is a fluororesin as an insulator, and a lower fitting groove 25 is formed over the entire circumference in the center portion. The intermediate member 22 is fitted and held.

  The intermediate member 22 is formed in a ring shape by, for example, a conductor, the lower side is fitted into the lower fitting groove 25, and the upper side protrudes upward from the lower member 21. The intermediate member 22 may be either in a float state where it is not electrically grounded or in a state where it is electrically grounded.

  The upper member 23 is formed in an annular shape with ceramics as an insulator, for example, and an upper fitting groove 27 is formed around the entire periphery of the middle member 22 that protrudes upward from the lower member 21 and engages with the upper portion. ing. Therefore, the upper member 23 and the lower member 21 cover the entire intermediate member 22. Further, the upper surface of the upper member 23 is formed so as to be substantially flush with the upper surface of the lower electrode 3 in a state where the focus ring 15 is attached to the fitting recess 14.

  Only one of the lower fitting groove 25 of the lower member 21 or the upper fitting groove 27 of the upper member 23 may be provided as long as the intermediate member 22 can be covered. That is, the intermediate member 22 is disposed on the flat lower member 21, and the intermediate member 22 is fitted into the upper fitting groove 27 and covered with the upper member 23. Alternatively, the lower fitting groove 25 of the lower member 21 is covered. Alternatively, the intermediate member 22 may be fitted so that the upper side is substantially flush and covered with the flat upper member 23.

  The gas shower plate 4 diffuses the etching gas introduced from the gas introduction part on the substrate B to be processed, and is provided with a large number of air outlets (not shown) through which the etching gas passes.

  The exhaust parts 5 and 5 are provided downward from the outer peripheral edge of the lower electrode 3.

  The opening 7 faces a transfer device (not shown) that transfers the substrate B to be processed.

  Next, the operation of the first embodiment will be described.

  First, the substrate B to be processed is carried into the processing chamber R of the vacuum chamber 2 from the opening 7 via the transfer device, placed on the lower electrode 3, and the opening 7 is closed.

  Next, the processing chamber R is evacuated from the vacuum chamber 2 so as to have a predetermined degree of vacuum, and an etching gas is introduced into the processing chamber R from the gas introduction portion.

  Thereafter, high frequency power is supplied from the high frequency power source 11 to generate plasma in the processing chamber R, and the substrate B to be processed is etched by this plasma.

  At this time, the upper member 23 of the focus ring 15 has a higher impedance with respect to the high-frequency power supplied from the high-frequency power supply 11 than the substrate B to be processed. The plasma is confined in the focus ring 15 by the action of the electric field formed by the.

  At this time, since the substrate B to be processed is the same size as the lower electrode 3 or several mm larger than the lower electrode 3, the high frequency passes through the lower member 21.

  Further, the intermediate member 22 cuts off the high frequency power and prevents the high frequency power from passing through the upper member 23.

  When the predetermined etching is completed, the supply of the high frequency power from the high frequency power supply 11 is stopped to stop the etching process, the opening 7 is opened, and the substrate B to be processed is carried out of the processing chamber R by the transfer device. .

  As described above, according to the first embodiment, the intermediate member 22 that is a conductor located between the lower member 21 that is an insulator and the upper member 23 that is an insulator is used to form the substrate B to be processed. By preventing the transmission of high-frequency power applied to the lower electrode 3 in the peripheral portion, the etching rate of the peripheral portion of the substrate B to be processed can be suppressed, the in-plane uniformity of etching can be improved, and the focus by etching The ring 15 itself (upper member 23) can be prevented from being scraped.

  Further, when the intermediate member 22 is not electrically grounded, the focus ring 15 itself is in a floating state, and a sudden potential change on the focus ring 15 is reduced, and the in-plane uniformity of etching of the substrate B to be processed is reduced. When the intermediate member 22 is electrically grounded, a sudden displacement change occurs in the focus ring 15 and the plasma can be concentrated on the substrate B to be processed. It can be prevented more reliably.

  In the first embodiment, for example, as in the second embodiment shown in FIG. 2, in addition to the high frequency power source 11, the dry etching apparatus 1 has a high frequency power having a predetermined frequency different from that of the high frequency power source 11. Even if a so-called two-wavelength superimposing type in which a high-frequency power source 29 as a high-frequency power application means capable of supplying a voltage is electrically connected to the lower electrode 3 has the same effects as those of the first embodiment. Is possible.

  Next, a third embodiment will be described with reference to FIG. In addition, about the structure and effect | action similar to said each embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  The dry etching apparatus 1 according to the third embodiment is of a so-called inductively coupled plasma discharge (ICP) type.

  That is, in the dry etching apparatus 1, instead of the gas shower plate 4, a ceramic top plate 31 that is an insulator and a dielectric 32 are disposed above the processing chamber R of the vacuum chamber 2. A coil 33 is disposed above the coil 33, and a high frequency power source 34 is electrically connected to the coil 33.

  Then, the substrate B to be processed is loaded into the processing chamber R of the vacuum chamber 2 from the opening 7 via the transfer device and placed on the lower electrode 3 to close the opening 7. The vacuum chamber 2 is evacuated to a predetermined degree of vacuum, an etching gas is introduced into the processing chamber R from the gas introduction portion, and high frequency power is supplied from the high frequency power supplies 11 and 34 to enter the processing chamber R. Plasma is generated and the substrate to be processed B is etched by this plasma.

  At this time, also in the third embodiment, the focus ring 15 is configured by disposing the intermediate member 22 as a conductor between the lower member 21 as an insulator and the upper member 22 as an insulator. Further, it is possible to prevent the high frequency power applied to the lower electrode 3 from being transmitted through the peripheral portion of the substrate B to be processed, and the same effects as those of the above embodiments can be obtained.

  In each of the above embodiments, the dry etching apparatus 1 can cope with various other forms.

  In addition to the above embodiments, the lower member 21, the intermediate member 22, and the upper member 23 are made of, for example, the lower member 21 and the upper member 23 made of ceramic, and the focus ring 15 is electrically floated with respect to the ground. The material to be appropriately selected, such as the case to be in a state, the above-described embodiments, or the structure in which the lower member 21 and the upper member 23 are made of ceramics, respectively, and the intermediate member 22 that is a conductor is electrically grounded It is possible to use.

It is explanatory drawing which shows the focus ring of the 1st Embodiment of this invention. It is explanatory drawing which shows the focus ring of the 2nd Embodiment of this invention. It is explanatory drawing which shows the focus ring of the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 2 Vacuum chamber as a processing chamber 3 Lower electrode
11, 29 High frequency power supply as means for applying high frequency power
15 Focus ring
21 Lower member
22 Intermediate member
23 Upper member B Substrate

Claims (6)

A focus ring that is placed on a lower electrode on which a substrate to be processed that performs a predetermined plasma treatment is placed and to which high-frequency power is applied, surrounding the substrate to be processed;
A lower member;
An intermediate member disposed at the top of the lower member;
A focus ring comprising: an upper member that covers the intermediate member and is disposed on an upper portion of the lower member. The lower member and the upper member are insulators;
The focus ring according to claim 1, wherein the intermediate member is a conductor. The lower member is a fluororesin;
The upper member is ceramic;
The focus ring according to claim 1, wherein the intermediate member is a conductor. The focus ring according to claim 1, wherein the upper member and the lower member are ceramics. The focus ring according to any one of claims 1 to 3, wherein the intermediate member is electrically grounded. A processing chamber;
A lower electrode disposed in the processing chamber and on which a substrate to be processed is placed;
The focus ring according to any one of claims 1 to 5, wherein the focus ring is disposed on the lower electrode so as to surround the substrate to be processed.
A plasma processing apparatus, comprising: a high-frequency power applying unit that applies high-frequency power to the lower electrode.

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