JPS62279637A - Plasma etching apparatus - Google Patents

Abstract

PURPOSE:To enable substrates to be always etched uniformly under various etching conditions, by dividing an upper or lower electrode into a group of electrodes and adjusting high-frequency voltages applied to respective electrodes of the group so as to correct deviation in electric field. CONSTITUTION:Upper electrodes 1, 2 and 3 are connected respectively to independent high-frequency power sources, so that high-frequency voltages are applied between a lower electrode 10 and the respective upper electrodes. A substrate 12 to be etched is disposed on the electrode 10. While an etching chamber is evacuated through evacuation exhaust paths 8, a desired etching gas is introduced into the chamber through an etching gas introduction path 7. The substrate is etched with the gas in the plasma state. During this process, any deviation in electric field may be corrected by adjusting the high-frequency voltages applied to the electrodes 1, 2 and 3. Consequently, the substrate 12 always can be etched uniformly under various etching conditions.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a plasma etching apparatus that etches a semiconductor substrate or a film formed on a semiconductor substrate using plasma. be.

(Prior Art) A conventional plasma etching apparatus will be explained with reference to FIG. FIG. 2 is a sectional view of an etching chamber of a conventional plasma etching apparatus. In the figure, 21 is an upper electrode, 22 is an upper electrode support and terminal, 23 is an etching gas introduction path,
24 is a vacuum exhaust path, 25 is an etching chamber outer wall, 26 is a lower electrode, 27 is an insulating bushing, and 28 is a substrate to be etched.

In a conventional parallel plate type plasma etching apparatus in which two upper and lower plate electrodes 21 and 26 face each other as shown in FIG. 2, a substrate to be etched 28 is placed on a lower electrode 26,
While evacuating the etching chamber through the vacuum exhaust path 24, a desired etching gas is introduced through the etching gas introduction path 23, and a high frequency voltage is applied between the electrodes 21 and 26 to turn the gas into a plasma state. Etching is performed using plasma discharge.

(Problems to be Solved by the Invention) However, with the configuration of the plasma etching apparatus described above, when trying to obtain desired etching characteristics, particularly a desired cross-sectional shape or a desired etching rate for the substrate to be etched, it is difficult to achieve uniform etching. The properties may not always be good. In such cases, the spacing between the electrodes or the method of introducing gas is adjusted to improve the uniformity of the etching rate or to slightly change the desired characteristics. However, when trying to determine etching conditions using this method,
Adjustment takes a long time, and one device cannot be used under many different etching conditions.

The present invention provides a plasma etching apparatus that can always perform uniform etching even under a wide variety of etching conditions.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a set of divided electrodes in which one of the parallel plate type first electrode and the second electrode to which a high frequency voltage is applied is divided into two electrodes. It has a solid structure and is equipped with a configuration that changes the high frequency voltage supplied to each divided electrode to make the etching rate uniform.

(Function) The uniformity of the etching rate depends on the distribution of the density of active species that contribute to etching in the plasma.

The density of active species in plasma is biased due to various causes, and one of the causes is bias in the electric field.

In the present invention, one electrode is an assembly of divided electrodes, and the high frequency voltage applied to each divided electrode is adjusted to correct the bias of the electric field. Uniform etching is always possible.

(Embodiment) An embodiment of the plasma etching apparatus of the present invention will be described with reference to FIG. FIG. 1(a) is a plan view of an electrode according to an embodiment of the present invention, and FIG. 1(b) is a sectional view of an etching chamber according to an embodiment of the present invention. Figure 1(a) and Figure 1(b)
1, 2.3 are lower electrodes, 4.5.6 are upper electrode supports and terminals, 7 is an etching gas introduction path, 8 is a vacuum exhaust path, 9 is an outer wall of the etching chamber, 10 is a lower electrode, 11
is an insulating bushing.

12 is a substrate to be etched.

Separate high-frequency power sources are connected to each of the upper electrodes 1, 2.3, and a high-frequency voltage is applied between them and the lower electrode 10, respectively. A substrate to be etched 12 is placed on the lower electrode lo.
is installed, and while the etching chamber is evacuated by evacuation from the vacuum exhaust path 8, a desired etching gas is introduced from the etching gas introduction path 7 to make the gas into a plasma state, and etching is performed by this plasma discharge.

In this case, the upper electrodes 1°2 and 3 are divided concentrically.
By adjusting the high frequency voltage applied to each of the two to correct the bias of the electric field, it is possible to always uniformly ett the substrate 12 to be etched.

Here, the upper electrodes 1 and 2.3 do not necessarily have to be on the high-frequency voltage application side; instead, the high-frequency voltage can be applied to the lower electrode 10, and the upper electrodes 1 and 2.3 can be grounded through separate capacitances. You can. Furthermore, the structure of the upper electrodes 1, 2.3 and the structure of the lower electrode 10 may be exchanged, and the substrate 12 to be etched may be placed on the divided electrode. Furthermore, the method of dividing the electrodes, the method of introducing etching gas, or the method of evacuation may not be the same as in this embodiment.

(Effects of the Invention) According to the present invention, uniform etching can always be performed under a wide variety of etching conditions, making it easy to change etching conditions in multiple stages and perform stepwise etching of multilayer films. Since over-etching can be suppressed to a very low level, damage to the underlying layer is also very small, and defects occurring in the etching process can be extremely reduced. Furthermore, since the problem of uniformity is almost solved, the degree of freedom in the process is increased, and precision machining becomes easier.

[Brief explanation of the drawing]

1(a) is a plan view of an electrode according to an embodiment of the present invention, FIG. 1(b) is a sectional view of a plasma etching chamber according to an embodiment of the present invention, and FIG. 2 is a conventional plasma etching chamber. FIG. 1.2.3...Upper double positive, 4,5.6...Upper electrode support and terminal, 7...Etching gas introduction path, 8...Vacuum exhaust path, 9...Etching chamber Outer wall, 1o...lower electrode, 11...insulating bushing, 12...substrate to be etched. Patent applicant: Matsushita Electronics Co., Ltd. Fig. 1 1.2.3...7-in electrical cavity 4.5.6...'L Wanryu cypress J kilometer wall and 7... Engineering' cover installation Figure 1 (b) 8, AtJ41-1 kidney 9... 11 walls 10... 1,000 saya 1 (Yζ 11... evening le old) 1.・/Fugu 12 ・
21-h Nakadenden 22hiY? Dragon-dyed branch 6 heirs 5 23 2. Dengue sword, 141 people, 24 nine emperors, 141 people, 25 degrees, outer wall 26-1000

Claims (2)

[Claims] (1) A divided electrode group having first and second electrodes facing each other in a plasma etching chamber, in which the second electrode is divided into two or more parts and are mutually independent, and each of the divided electrodes and the first electrode A plasma etching apparatus characterized by applying independent high frequency voltages between the two. (2) Each of the divided electrodes of the second electrode is grounded via an independent capacitance, and a constant high-frequency voltage is applied between the first electrode and the ground. 1) The plasma etching apparatus described in item 1).