JPS63102319A - High frequency electrode - Google Patents

Abstract

PURPOSE:To prevent the temperature rise of the substrate to be treated such as a semiconductor wafer by a method wherein the title electrode is provided with an electrode plate on which the substrate to be treated is retained, through the intermediary of an insulative layer covering the surface of the substrate to be treated and also high frequency electric power will be applied thereto, and the gas flow passage through which cooling gas will be supplied on the reverse side of said substrate to be treated, and the dielectric withstand voltage of the above-mentioned gas flow passage is made higher than the dielectric withstand voltage of said insulative layer. CONSTITUTION:The substrate to be treated such as a semiconductor wafer 14 is arranged on the surface of an insulative layer 12, high frequency power is applied across an electrode plate 11 and an opposing electrode or the like, the sputtering gas circulated in a treatment chamber is activated, and the surface of the wafer 14 is etched. At this time, the gas same as the sputtering gas circulated in the treatment chamber is supplied from a cooling gas feeding device 13 as cooling gas on the reverse side of the semiconductor wafer 14 using a gas flow passage 15. Accordingly, the semiconductor wafer 14 can be cooled with said gas. Also, by bringing the dielectric withstand voltage of the gas flow passage 15 higher than the dielectric withstand voltage of the insulative layer 12, the abnormal electric discharge by the self-biased voltage generating on the surface of the semiconductor wafer 14 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Field of Industrial Application) The present invention relates to a high-frequency electrode used for high-frequency etching of a substrate to be processed such as a semiconductor wafer.

(Prior Art) Generally, high-frequency electrodes are placed in processing chambers of semiconductor manufacturing equipment, and used for high-frequency etching, etc., in which substrates to be processed, such as semiconductor urchins, are etched using high-frequency power.

Figure 2 shows an example of such a conventional high-frequency electrode.
This figure shows a high-frequency electrode placed in a processing chamber of a semiconductor manufacturing apparatus that performs high-frequency etching. An insulator layer 2 covers the surface of the insulating layer 2.

A substrate to be processed, such as a semiconductor wafer 3, is placed on the surface of the insulator layer 2, and high-frequency power is applied between the electrode plate 1 and a counter electrode (not shown), and the high-frequency power is distributed into the processing chamber. The surface of the semiconductor wafer 3 is etched by activating the sputtering gas.

The insulator layer 2 is arranged on the surface of the electrode plate 1 because a self-bias voltage of several hundred to several kilovolts is applied to the surface of the semiconductor wafer 3 due to the difference in mobility between the ionized sputtering gas and the electrons. occurs, and if the insulator layer 2 were not present, this self-bias voltage would cause the characteristics of the semiconductor elements formed on the semiconductor wafer 3 to deteriorate due to the potential gradient.

(Problems to be Solved by the Invention) However, with the conventional high-frequency electrode described above, what is the problem? !
Because of the insulating layer such as quartz glass that covers the surface m1 of the F112 plate, heat dissipation from the substrate to be processed such as a semiconductor wafer becomes poor, and the temperature of the substrate to be processed increases. Therefore, it has an adverse effect on the substrate to be processed, such as adversely affecting the semiconductor devices formed on the semiconductor wafer. In order to prevent this, when gas is introduced to the back side of the substrate for cooling, the dielectric strength voltage of this gas flow path is generally a few Torr, which is relatively blind, and therefore becomes lower than the dielectric strength voltage of the insulating layer such as glass. A discharge occurs between the processed substrate and the ground via this gas flow path, resulting in the same state as if the insulating layer such as glass was electrically shorted, which leads to the deterioration of the semiconductor elements on the substrate as described above. There is a problem with becoming.

The present invention has been made in response to such conventional circumstances, and is capable of preventing temperature rises of substrates to be processed, such as semiconductor wafers, and alleviating the effects of temperature increases on substrates to be processed. The aim is to provide a high-frequency electrode without

[Structure of the Invention] (Means for Solving the Problems) That is, the high-frequency electrode of the present invention includes an electrode plate that holds a substrate to be processed through an insulating layer covering the surface and to which high-frequency power is applied, and an electrode plate to which high-frequency power is applied. A gas flow path for supplying cooling gas to the back surface of the processing substrate is provided, and the dielectric strength voltage of the gas flow path is higher than the dielectric strength voltage of the insulator layer.

(Function) In the high frequency electrode of the present invention, the substrate to be processed is held via an insulating layer covering the surface, and a gas flow path is formed on the back surface of the substrate to be processed to supply cooling gas. Can be cooled. In addition, since the dielectric strength voltage of the gas flow path is configured to be higher than the dielectric strength voltage of the insulator layer, the gas flow path becomes a discharge path and abnormal discharge occurs between the semiconductor wafer and the electrode plate. Never.

(Example) Hereinafter, one example of the high frequency electrode of the present invention will be described with reference to the drawings.

FIG. 1 shows a high frequency electrode according to an embodiment of the present invention, which is placed in a processing chamber of a semiconductor manufacturing apparatus that performs high frequency etching. This high-frequency electrode consists of an electrode plate 11 formed, for example, in the shape of a disk, and a quartz glass or the like in the shape of a disk, for example, approximately the same shape as the main peak plate 11.
It is composed of an insulating layer 12 that covers the surface of the insulating layer 12, and a gas passage 15 that is connected at one end to a cooling gas supply device 13 and supplies cooling gas to the back surface of the semiconductor wafer 14 disposed on the surface of the insulating layer 12. There is.

Further, the gas flow path 15 includes an external pipe 15a from the cooling gas supply device 13 to the high-frequency electrode, and from this external pipe 15a through the high-frequency electrode to the back surface of the semiconductor wafer 14 placed on the surface of the insulator layer 12. It is composed of an internal pipe 15b.

The external piping 15a is connected to the internal piping 15b at the periphery of the insulating layer 12, and the internal piping 15b passes through the insulating layer 12 from approximately the center of the insulating layer 12 to the surface of the insulating layer 12. is formed towards. Insulator N11
A recess 12a having a diameter slightly smaller than that of the semiconductor wafer 14 disposed on this surface is formed on the surface of the external piping 1.
5a and the internal pipe 15b, the cooling gas flows out from approximately the center of the insulating layer 12 toward the surface of the insulating layer 12, and the cooling gas flows inside the recess 12a and contacts the back surface of the semiconductor wafer 14 while flowing around the outer periphery of the semiconductor wafer 14. direction, and flows out into the processing chamber from between the insulator layer 12 and the semiconductor wafer 14 at the outer periphery.

Note that the gas flow path 15 is more insulated than the insulator layer 12 by 11iJ.
'$, the pressure is configured to be high. this is,
The gas flow path 15 serves as a discharge bus, and abnormal discharge occurs due to the self-bias voltage of several hundred to several kilovolts generated on the surface of the semiconductor wafer 14 due to the mobility difference between the ionized sputtering gas and electrons as described above. This is to prevent this from occurring.

In this way, in order to increase the dielectric strength voltage of the gas flow path 15, as shown in this embodiment, the internal piping 15b should not be brought into contact with the electrode plate 11, or the external piping 15a should have a bent part such as a coil shape. The length of the gas flow path 15 from the end of the gas flow path 15 on the semiconductor wafer 14 side to the portion that contacts another conductor is increased by providing a conductor. The diameter of the gas flow path 15 is reduced.

There are methods such as increasing the gas pressure of the cooling gas in the gas flow path 15, and the dielectric withstand voltage may be increased by combining these methods or by other methods.

In the high frequency electrode of this embodiment having the above structure, the insulator layer 12
A substrate to be processed, such as a semiconductor wafer 14, is placed on the surface of the
High frequency power is applied between the electrode plate 11 and a counter electrode (not shown), etc., and the high frequency power activates the sputtering gas flowing into the processing chamber to etch the surface of the semiconductor wafer 14. At this time, the same gas as the sputtering gas flowing into the processing chamber is supplied from the cooling gas supply device 13 to the back surface of the semiconductor wafer 14 through the gas flow path 15 as a cooling gas. Therefore, the semiconductor wafer 14 can be cooled by this gas, and an increase in the temperature of the semiconductor wafer 14 can be prevented from adversely affecting the semiconductor devices formed on the surface of the semiconductor wafer 14.

Furthermore, since the dielectric strength voltage of the gas flow path 15 is made higher than the dielectric strength voltage of the insulator rrj12, the gas flow path 15 becomes a discharge path, and abnormal discharge due to the self-bias voltage generated on the surface of the semiconductor wafer 14 is prevented. It is possible to prevent this from occurring.

[Effects of the Invention] As described above, the high-frequency electrode of the present invention can prevent the temperature of the substrate to be processed, such as a semiconductor wafer, from rising, and can make the surface of the semiconductor wafer potential floating. There is no adverse effect due to temperature rise.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a high-frequency electrode according to an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view showing a conventional high-frequency electrode. 11... Electrode plate, 12... Insulator layer,
14... Semiconductor wafer, 15... Gas flow path.

Claims (1)

[Claims] (1) An electrode plate that holds a substrate to be processed through an insulator layer covering the surface and to which high frequency power is applied, and a gas flow path that supplies cooling gas to the back surface of the substrate to be processed, the gas flow path A high-frequency electrode characterized in that the dielectric withstand voltage of the insulator layer is higher than the dielectric withstand voltage of the insulator layer.