JP2007095985A - Electrode for plasma processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce generation of abnormal discharge even with high voltage bias applied to work on a semiconductor integrated circuit at high speed, to inhibit the occurrence of working defects due to generation of foreign matters, and to stably apply the high voltage bias. <P>SOLUTION: A structure having a spirally worked groove around its outer periphery is inserted, and the groove around the outer periphery is used as an inlet guide for cooling gas. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus used for processing a semiconductor integrated circuit, and more particularly to an electrode structure used for a dry etching apparatus.

  Semiconductor integrated circuits have been miniaturized in response to the demand for higher density, and there has been a growing demand for structural use of vertical spaces. For this reason, it has become necessary to apply a high bias to the etching apparatus to increase the processing speed. A high voltage is applied to the electrodes in order to apply a high voltage to the wafer, but high voltage resistance has been required for the support mechanism, the sensor frame, and the refrigerant supply mechanism.

  In particular, a refrigerant gas supply mechanism such as He introduced to reduce the thermal resistance between the wafer and the electrode is likely to cause discharge because the supply line pressure is maintained at a low discharge start voltage of several kPa. The plasma generated by the discharge causes the abnormality of the apparatus such as deterioration of the material of the supply system due to heat or leakage of the electrostatic adsorption current supplied while being superimposed on the bias voltage.

Various structural measures are taken to prevent the occurrence of abnormal discharge in the cooling gas supply line. In order to improve the withstand voltage of the cooling gas introduction line, there are known a method in which a so-called nested structure is combined and a flow path is bent in a complicated manner and a porous body is inserted.
Further, Patent Document 1 discloses a plasma provided with an annular groove that allows a cooling medium to flow through a plurality of holes penetrating an electrode, and a plurality of radial grooves that allow the cooling medium to flow through the annular groove. An electrode for an etching apparatus is described.
JP 2005-39098 A

Since these methods are difficult in terms of manufacturing cost, withstand voltage, and cleaning of foreign matter accumulated in the flow path, foreign matter is ejected from the back of the wafer into the processing chamber during the etching process, resulting in processing defects. There was a problem that the structural material of the flow path deteriorated easily due to the occurrence of abnormal discharge.
The present invention aims to solve these problems.

  In the present invention, a cylindrical body made of an insulating material and spirally grooved on the outer periphery is provided in the middle of the supply path, and a member inserted into an insulating material in which a cylindrical hole is processed is provided. A high relative permeability material such as ferrite is inserted inside.

  According to the present invention, a semiconductor integrated circuit can be produced with a high yield using a large-diameter wafer.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a sectional view of the electrode cooling gas supply structure of the plasma processing apparatus according to the first embodiment of the present invention.
In FIG. 2, reference numeral 201 denotes a cylindrical inner insulator, and the outer periphery thereof is spirally grooved as shown in FIG. Reference numeral 203 denotes a base material that supports a high-voltage portion that is supplied with high-frequency power from the electrode and becomes a high voltage. Reference numeral 204 denotes a base plate that is connected to the chamber and supports the electrode itself. On the other hand, 204 is kept at a ground potential of 0V. Reference numeral 202 denotes an insulating plate that insulates between the holes. A hole for inserting the inner insulator 201 is provided. A 0-ring groove for sealing is formed vertically around the hole. The cooling gas He is guided from the introduction hole 207 of the base plate 204 to the space 206 provided below the inner insulator 201 above, and passes through a groove 201 ′ provided in the outer peripheral portion of the inner insulator 201 to form a spiral shape. To the cooling gas introduction hole 207 ′ provided in the base material 203 through a space 206 ′ between the base material 203 and the upper surface of the inner insulator 201, and passes through another flow path to a predetermined portion of the electrode. Inflow.

  The electric field generated by applying a high voltage to the electrode is generated in the direction from the base material 203 toward the base plate 204, but the spiral groove structure is a full width (about 2 mm in the embodiment) with respect to the electric field direction of the bias voltage. In order to cut off the electric field, it is possible to suppress the proliferation of charged particles due to the collision of the accelerated electrons, and to obtain the effect of causing the generated charged particles to disappear due to the collision with the wall. In addition, an accidental surge voltage plays a major role in starting discharge, but the spiral groove 201 ′ acts as an inductance against a high-speed current generated by the generation of the surge voltage, and generates a reverse voltage to generate a current amount. Limiting the start of discharge. For this reason, in Example 1, the number of turns of the spiral groove 201 'was set to six.

  In the second embodiment of the present invention, a high magnetic permeability material 205 such as ferrite is provided in the inner insulator 201. In the second embodiment, by providing the high permeability material 205 such as ferrite, the effect of inhibiting the start of discharge can be increased, and the probability of occurrence of abnormal discharge can be further reduced. In addition, this structure works not only for bias voltage but also for leakage of high-frequency source power to the electrode that generates plasma in the chamber. Show the effect.

  In the third embodiment of the present invention, this cooling gas introduction mechanism is incorporated in the etching apparatus shown in FIG. The results of confirming the effect are shown in FIGS.

  FIG. 1 shows a schematic cross-sectional view of a plasma etching apparatus using UHF-ECR which is Embodiment 3 of the present invention. Here, reference numeral 101 denotes a vacuum processing chamber, and a quartz window 102 is disposed above the vacuum processing chamber 101 and below the antenna 107 in order to pass an electric field from an antenna 107 described later into the vacuum processing chamber 101. The electrode 103 is disposed below the vacuum processing chamber 101 so as to face the quartz window 102, and a wafer 104 on which a semiconductor integrated circuit is to be formed is placed thereon to generate a bias voltage. A high frequency power source 105 is connected. The electrode 103 is connected to a pipe 106 for supplying a cooling gas for cooling the wafer 104 by conducting heat to the electrode 103, and is connected to the back surface of the wafer 104 through the cooling gas supply mechanism 113 in the electrode. Supplied. The antenna 107 is connected to the upper surface of the quartz window 102 and introduces an electric field from the UHF power source 110 into the vacuum processing chamber 101. The solenoid coil 108 forms a magnetic field in the vacuum processing chamber 101. The gas dispersion plate 109 is disposed above the electrode 103 so as to face the wafer 104, and the gas supplied from the mass flow controller 111 is dispersed and uniformly introduced into the vacuum processing chamber 101 from a plurality of through holes provided according to the etching recipe. .

The configuration shown in FIG. 2 is a cooling gas supply path and connection structure forming part of the cooling gas supply mechanism 113.
Here, the test results in the case of using the conventional nested structure as the cooling gas supply mechanism and the supply mechanism described in FIG. 2 according to the first embodiment of the present invention will be described.

  FIG. 3 shows the abnormal discharge resistance against the bias voltage. The horizontal axis of the graph shows the bias voltage between the peaks, and the vertical axis shows the peak current value of the electrostatic chucking power source supplied superimposed on the bias voltage. It is a thing. In the case of the conventional method, the current value increases at 2.5 kV or more and discharge is generated in the cooling gas supply flow path. However, in the case of using the structure of the present invention, the bias voltage is within the range of 4 kV. Thus, it can be seen that there is no sudden increase in current, and that no abnormal discharge has occurred even in the cooling gas supply path penetrating or connected to the high voltage portion.

  FIG. 4 is a graph showing a trend of the processing defect occurrence ratio with respect to the number of processed wafers. In the case of the conventional nesting structure, sporadically generated foreign substances exceed the management allowable value, but those using the cooling gas supply structure according to the present invention have a stable transition with the number of foreign substances below the management value. In the nested structure, so-called stagnation tends to occur in the flow of pressurized air used for cleaning performed by opening to the atmosphere, and foreign matters remaining in these places move during processing, and the wafer back surface is moved by the flow of cooling gas. It seems that it was caused by dropping on the wafer surface. Regarding the number of defects, the porous material also shows the same tendency as that of the nested structure. Similarly, it is considered that sufficient cleaning is difficult to perform for the blow-off cleaning.

  As described above, as described in each embodiment, even when a high bias voltage is applied by using the present invention, the occurrence of abnormal discharge can be prevented, and the number of processing defects can be suppressed to a low level. Semiconductor elements can be produced stably and with high yield.

Sectional drawing of the plasma processing apparatus explaining Example 3 of this invention. Sectional drawing of the electrode cooling gas supply structure of the plasma processing apparatus of Example 1 and Example 2 of this invention. It is a figure which shows the withstand voltage performance by this invention. The figure which shows the foreign material generation | occurrence | production suppression performance by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Vacuum processing chamber 102 Quartz window 103 Electrode 104 Wafer 105 High frequency power supply 106 Piping 107 Antenna 108 Solenoid coil 109 Gas distribution plate 110 UHF power supply 111 Mass flow controller 113 Cooling gas supply mechanism 201 Inner insulator 201 'Spiral groove
202 Insulating plate 203 Support base material 204 Base plate 205 High magnetic permeability material 206 Lower space of inner insulator 207 Base plate introduction hole 207 ′ Support base material introduction hole

Claims (5)

  The insulating material that insulates between the high-voltage applying portion and the ground potential portion has an opening, and the insertion insulating material spirally grooved in the outer peripheral portion is formed in the opening portion, and the surface of the outer peripheral portion and the The electrode for plasma processing apparatuses which has the insulating material structure inserted so that the surface of an opening part may contact | connect.   2. The electrode for a plasma processing apparatus according to claim 1, wherein the insulating material structure is a flow path for wafer cooling gas.   The electrode for a plasma processing apparatus according to claim 1, wherein the interpolating insulator has a high magnetic permeability material.   The electrode for a plasma processing apparatus according to claim 2, wherein the interpolated insulator has a high magnetic permeability material.   The insulating material that insulates between the high-voltage applying portion and the ground potential portion has an opening, and the insertion insulating material spirally grooved in the outer peripheral portion is formed in the opening portion, and the surface of the outer peripheral portion and the An electrode for a plasma processing apparatus having an insulating material structure inserted so that the surface of the opening is in contact, and a piping for introducing a cooling gas connected to a wafer cooling gas flow path of the insulating material structure A plasma processing apparatus.

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