JPS6297328A - Plasma etching method - Google Patents

Abstract

PURPOSE:To facilitate matching and to obtain a matching state rapidly by applying a high-frequency power source to the respective electrodes in order after matching the respective electrodes by applying a high-frequency power source to each electrodes. CONSTITUTION:The output of a second high-frequency power source 8 is applied to an electrode 7 through a second matching box 9. A plasma is generated in an etching chamber 1 by this application and when the matching signal generated by attaining matching by the matching box 9 is accepted by an applying device 5, the applying device 5 is changed over automatically so that the output of a first high-frequency power source 6 is applied to an upper electrode 2 through a first matching box 4. When the applying device 5 accepts the matching signal generated by attaining matching by this application by the matching box 4, the applying device 5 is changed over automatically so that the output of the high-frequency power source 8 is applied to the electrode 7 through the matching box 9.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a semiconductor i! The present invention relates to a plasma etching method used in an i-device manufacturing process, and particularly to a method of matching the plasma in a chamber with the high-frequency power source when applying the high-frequency power source to each of a plurality of electrodes in one chamber.

[Technical Background of the Invention 1] In recent years, as semiconductor devices have become more sophisticated, advanced microfabrication techniques have become required, and plasma etching apparatuses have come into wide use. For example, in a conventional plasma etching apparatus having a parallel plate type electrode structure in the etching chamber, etching gas is introduced while reducing the pressure inside the etching chamber, one electrode is grounded, and the other electrode is connected to a high frequency power supply ( Normally 13.56M)lz
) is applied to generate plasma between both electrodes, and the semiconductor wafer placed on either electrode is subjected to an etching process.

Incidentally, as microfabrication techniques with high etching accuracy have become required, research into parameters that affect etching gases has progressed, and it has become necessary to control plasma more precisely. In this case, it is necessary not only to accurately control the parameters that determine the plasma state (usually the type of etching gas, flow rate, pressure, and power of the high-frequency power supply), but also to increase the degree of freedom of control by using electrodes other than parallel plate electrodes. A third electrode is provided, and the third electrode is connected to the same frequency (13,56M) I2) or a different frequency (for example 400 KHz or 100KH) as the high frequency power source.
z) A method of applying another high frequency power source has been considered.

[Problems with the Background Art] However, when multiple high-frequency power sources corresponding to the multiple electrodes as described above are simultaneously applied, the impedance of the plasma in the etching chamber is difficult to stabilize. There is a problem in that the power of the reflected wave that returns oscillates and abnormal discharge occurs in a part of the chamber, making it difficult to achieve matching and prolonging the time it takes to reach a matching state.

LObject of the Invention The present invention has been made in view of the above circumstances, and it is possible to prevent abnormal discharge from occurring in the chamber when applying high frequency power to each of a plurality of electrodes, to facilitate matching, and to quickly perform matching. 5, which provides a plasma etching method by which a matching state can be obtained.

[Summary of the Invention] That is, in the plasma etching method of the present invention, when applying a high frequency power to each of a plurality of electrodes to which high frequency power is to be applied in an etching chamber of a plasma etching apparatus, the high frequency power is applied to each of the electrodes. The method of sequentially performing matching on each electrode is also characterized in that a high frequency power source is sequentially applied to each electrode.

In this way, by applying high frequency power to each electrode one after the matching is completed, one
Abnormal discharge does not occur in the chamber when 31 is applied, making it easier to perform matching, and shortening the time required to reach the matching state.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

The drawing schematically shows an example of a triode type plasma etching apparatus used in the method of the present invention, which is similar to the etching chamber of a conventional parallel plate diode type plasma etching apparatus. A third IT is provided. That is, 1 is an etching chamber, 2 and 3 are parallel plate type upper and lower electrodes, and in this example, the lower electrode 3 is grounded, and the upper electrode 2 is connected to a first matching box (matching box) outside the etching chamber 1. After passing through the circuit) 4, it is connected to a first high frequency type 16 for supplying, for example, 100 KHz, via an application device 5 having a variable high frequency path function. Reference numeral 7 denotes a cylindrical or polygonal cylinder-shaped third electrode provided along the side wall of the etching chamber 1.

8 is a second high-frequency power supply for supplying normal 13.56 M) Iz, and its output passes through the application device 5 and then
The third electrode 7 in the etching chamber 1 can be supplied through the matching box 9 . Note that 10 is a coaxial cable for high-frequency power supply, and 11 is a material to be etched (for example, a semiconductor wafer) placed on the lower electrode 3.
, 12 is an exhaust port, and 13 is a Freon etching gas, for example, which is supplied to the etching chamber 1 from an external gas source.

Next, a method of applying the high frequency power sources 6 and 8 when performing plasma etching using the above apparatus will be explained. The application device @5 first converts the output of the second high-frequency power source 8 into the second
The voltage is applied to the third electrode 7 without passing through the matching box 9 . As a result of this application, plasma is generated in the etching chamber 1, and when the applying device 5 receives a matching signal generated by matching in the second matching box 9, the applying device 5 converts the first high-frequency type 16 is automatically switched to be applied to the upper electrode 2 via the first matching box 4. By this application, the matching signal generated by the matching in the first matching box 4 is transmitted to the applying device 5.
, the application device 5 receives the second high frequency type iN! 8 is automatically switched to be applied to the third electrode 7 via the second matching box 9. Thereafter, the application device 5 automatically repeats the above-described operations of power application, matching detection, and power switching a preset number of times. Finally, the application device 5 cancels the power supply switching and switches the current power supply (for example, the second high-frequency power supply 8) to the power supply that is currently being applied.
All power sources are applied by applying a power source (first high frequency power #!6) different from the power source.

Up)! According to this method, by sequentially applying power and matching to two electrodes, abnormal discharge does not occur in the etching chamber 1 when power is applied, and matching becomes easier. , the time it takes to reach the matching state can be saved. Incidentally, until the power of the reflected wave returning to the power supply side when power is applied becomes stable at 5% or less of the power saving of the traveling wave (defined as a matching state), the conventional method (using multiple power supplies from the beginning) The simultaneous application method required about 10 seconds, but the method of this example only took about 2 to 3 seconds.

In addition, in the method of the above embodiment, h is supplied from two power sources.
However, if the method of the present invention is applied to the case where power of the same frequency is supplied from two or a common power supply, the same '211I power as in the above embodiment can be obtained. The result is 1!'?

[Member 21] As described above, according to the plasma etching apparatus of the present invention, when applying high frequency power to each of a plurality of electric ships, a continuous discharge is generated in the chamber. This does not occur, making it easier to match, and quickly achieving a matching state.

[Brief explanation of drawings]

The drawing is an explanatory diagram of the configuration of a plasma etching apparatus used in an embodiment of the plasma etching method of the present invention. 1... Etching chamber, 2, 3, 7...
...Electric meat, 4,9...Munching box, 5
...Mark 1111 device, 6.8...High frequency power supply.

Claims (2)

[Claims] (1) When applying high frequency power to multiple electrodes to which high frequency power is to be applied in the etching chamber of a plasma etching device, apply high frequency power to each electrode to ensure matching. A plasma etching method characterized by sequentially applying a high frequency power source to each electrode. (2) The plasma etching method according to claim 1, wherein the frequency of the high-frequency power source applied to each electrode is different for each electrode.