JPH0196931A - Plasma etching device - Google Patents

Abstract

PURPOSE:To enable etching rate within wafer surface to be uniform as much as possible by providing the first and second flat plate like electrodes which were arranged in parallel each other and by continuously changing the distance between electrodes at least at either periphery in reference to the direction between electrodes. CONSTITUTION:If the supply of echants is larger near the outer periphery of wafer, etching is performed by applying a highfrequency voltage between upper and lower electrodes 1 and 2 which were arranged opposing each other. In this case, since a taper like electrode part 10 is provided at the periphery of a lower electrode 2 where a wafer 3 is placed, an electric line of force 9 from the upper electrode 1 is pulled toward the side of the electrode part 10 and the density of the electric line of force 9 at the outer periphery becomes small. Namely, by properly setting the length L of the electrode part 10 and the taper angle theta, the density of the electric line of force 9 at the periphery can be varied and adjusted. And the larger the length L and angle theta are made, the smaller the density of the electric line of force 9 becomes. It allows the etching rate at the central part and outer periphery part on the surface of the wafer 3 to be equal as much as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of industrial fil] The present invention relates to a plasma etching apparatus used for etching a target object during the manufacture of semiconductor devices, and more particularly, to a plasma etching apparatus using a parallel plate electrode type. This invention relates to an improvement of a plasma etching apparatus.

[Conventional technology]

The basic configuration of a conventional parallel plate electrode type plasma etching apparatus of this type is shown in FIGS. 3(a) and 3(b).

That is, in the conventional parallel plate electrode type plasma etching apparatus shown in FIGS. 3(a) and 3(b), reference numeral 1 indicates an upper electrode (first planar electrode), and 2 indicates an electrode opposite to this upper electrode. A lower electrode (second planar electrode) is arranged and serves as a wafer stage, 3 is a wafer as an object to be etched placed on the lower electrode 2, and 4 and 5 are the upper and lower electrodes, respectively. Electrode wiring for electrodes 1 and 2, 6
is ground, 7 is a high-frequency power source for applying a high-frequency voltage between these upper and lower electrodes 1.2 to generate plasma;
Reference numeral 8 indicates an electrode interval between the upper and lower electrodes 1.2, and 8 indicates lines of electric force.

In this conventional example, the upper and lower electrodes 1 and 2 are opposed to each other.
In between, the upper and lower electrodes 1°2 structure is designed so that a DC bias is applied perpendicularly to the wafer 3, and the density of the electric lines of force 9 is such that the density of the electric lines of force 9 is Q' It is configured to be hung perpendicularly to the wafer to be processed.

However, in the case of this conventional configuration, the above-mentioned upper electrode 1
The lower electrode 2 is usually arranged in a vacuum chamber drawn by a vacuum pump, and a wafer 3 to be etched is placed on the lower electrode 2 to prepare. In this state, etching gas is introduced into the vacuum chamber, and the upper and lower electrodes 1 are connected to each other by a high frequency power source 7 under an appropriate pressure.

By applying a voltage between 2, each of these upper and lower electrodes 1.2
During this time, plasma is generated, and the ions and radicals in this plasma become etchants and are applied to the wafer 3, causing physical and chemical reactions, which usually cause the film on the wafer 3 to become etchant. The pattern can be selectively removed by etching.

[Problem that the invention seeks to solve]

The conventional parallel plate electrode type plasma etching apparatus is constructed as described above, and the density of the electric lines of force 9 applied perpendicularly to the wafer 3 is increased by the upper and lower electrodes 1.2 arranged to face each other. If the etchant supply and reaction applied to the wafer 3 become unbalanced, that is, when a so-called loading effect occurs, the uniformity of the etching rate within the wafer will change. This loading effect has an undesirable problem in that the etching process is disadvantageous.

Therefore, an object of the present invention is to make it possible to adjust the etching rate as uniformly as possible in view of the above-mentioned problems with the conventional apparatus. It is an object of the present invention to provide a plasma etching apparatus of this type.

[Means for solving problems]

In order to achieve the above object, the plasma etching apparatus according to the present invention includes a first flat electrode and a second flat electrode serving as a wafer stage, which are arranged facing each other in parallel. A plasma etching apparatus capable of applying a high frequency voltage between the electrodes, wherein the distance between the electrodes at the peripheral portion of at least one of the electrodes is continuously changed in the direction between the electrodes. be.

[For production]

That is, in this invention, a first flat electrode and a second flat electrode are provided that are arranged parallel to each other, and the distance between the electrodes at the peripheral portion of at least one of them is set in the direction between the electrodes. By applying a high frequency voltage between each of these electrodes, the density of electric lines of force can be reduced in areas where a large amount of etchant is supplied, and the etchant supply is also small. It is possible to increase the density of electric lines of force at a certain portion, thereby making it possible to correct the distribution of electric lines of force inside and outside the wafer, and as a result, correct the etching rate within the wafer plane as uniformly as possible.

〔Example〕

Hereinafter, first and second embodiments of the plasma etching apparatus according to the present invention will be described in detail with reference to FIGS. 1 and 2.

The first embodiment is an example in which the supply of ion or radical etchant generated by plasma increases as it approaches the outer periphery of the wafer, which is the object to be etched.
In contrast, the second embodiment is an example in which the supply of etchant decreases as the wafer approaches the outer periphery.

First, FIGS. 1(a) and 1(b) are a cross-sectional explanatory diagram schematically showing the general configuration of a plasma etching apparatus to which a first embodiment of the present invention is applied, and a plan view of each electrode viewed from above. In the configuration of the first embodiment shown in FIGS. 1(a) and (b), the same reference numerals as in the conventional configuration shown in FIGS. 3(a) and (b) represent the same or corresponding parts.

That is, in this first embodiment as well, the reference numeral 1 is an upper electrode (first planar electrode), and the reference numeral 2 is a lower electrode (second planar electrode) that is arranged opposite to the upper electrode 1 and serves as a wafer stage. The peripheral part of the lower electrode 2 has a length indicated by 11 and a taper angle θ indicated by 12 so that the distance between the electrodes and the upper electrode 1 changes continuously in the direction between the electrodes. A raised tapered electrode portion IO is provided.

Further, 3 is a wafer as an object to be etched placed on the lower electrode 2, 4 and 5 are electrode wirings for the upper and lower electrodes 1 and 2, 6 is the ground, and 7 is the upper and lower electrodes. A high frequency power supply is used to generate plasma by applying a high frequency voltage between the electrodes 1 and 2, 8 is an electrode interval between the upper and lower electrodes 1 and 2, and 9 is a line of electric force.

As described above, the configuration of the first embodiment is an example applied to the case where the supply of etchant increases closer to the outer periphery of the wafer.
Plasma is generated by applying a high frequency voltage between the upper and lower electrodes 1.2 which are arranged to face each other, and the desired etching is performed. Since the tapered electrode part lO is provided at the peripheral part, the electric lines of force 8 from the upper electrode l are connected to this electrode part lO.
On the side of the tapered electrode part 10, and furthermore, in the outer peripheral part of the wafer 3 where a large amount of etchant is supplied, the tapered electrode part l
As a result, the density of the electric lines of force 8 at the outer peripheral portion can be reduced as expected.

In other words, by appropriately setting the length of the tapered electrode portion IO and the taper angle θ, it is possible to change and adjust the density of the electric lines of force 8 at the periphery of the wafer 3. Now, as the length and taper angle θ of the tapered electrode portion 10 are increased, the density of the electric lines of force 8 becomes smaller.

Therefore, in the case of the configuration of the first embodiment, even if more etchant is supplied closer to the outer periphery of the wafer 3, the presence of the tapered electrode portion 10 on the lower electrode 2 side causes the electricity at the outer periphery to increase. Since the density of the lines of force 9 is reduced, it is possible to make the etching rates as equal as possible on the central and outer peripheral sides of the wafer 3.

Next, in the second embodiment shown in FIGS. 2(a) and 2(b), contrary to the first embodiment, a tapered electrode portion 1G is provided on the outer circumferential portion of the upper electrode 1 side. In the case of this second embodiment configuration, electric lines of force 8. from the upper electrode 1 are provided. In particular, since the electric lines of force 9 from the tapered electrode portion 10 are attracted to the lower electrode 2 side, and further to the outer circumference of the wafer 3 where less etchant is supplied, the density of the electric lines of force 3 can be reduced to a certain level. This means that it can be made larger at the same outer periphery in time.

Therefore, in the case of the configuration of the second embodiment, even if the supply of etchant decreases as the closer to the outer periphery of the wafer 3, the presence of the tapered electrode portion 10 on the upper electrode 1 side causes the electricity at the outer periphery to decrease. Since the density of the lines of force 8 is increased, this also makes it possible to make the etching rates as equal as possible on the central and outer peripheral sides of the wafer 3.

〔Effect of the invention〕

As detailed above, according to the present invention, the first flat electrode and the second flat electrode serving as the wafer stage are arranged facing each other in parallel, and a high frequency voltage is applied between each of these electrodes. In the plasma etching apparatus, a first flat electrode and a second flat electrode are arranged facing each other in parallel, and a gap between the electrodes is provided in the peripheral area of at least one of the first and second flat electrodes. Since the distance is configured to change continuously in the direction between the electrodes, when a high frequency voltage is applied between each of these electrodes to generate plasma, the electricity will increase in the area where a large amount of etchant is supplied. It is possible to reduce the density of lines of force and increase the density of lines of electric force in areas where there is little etchant supply, correcting the lines of electric force inside and outside the wafer according to the etching conditions, and eventually improving etching within the wafer plane. The rate can be adjusted appropriately and the uniformity of the etching process can be greatly improved.
Moreover, specifically, the first. Since the configuration is such that only one of the second electrodes is provided with a tapered electrode portion, it has excellent features such as being relatively easily applicable to devices currently in use.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are cross-sectional explanatory views schematically showing the general configuration of a first embodiment of a plasma etching apparatus according to the present invention, a plan view of each electrode viewed from above, and FIG. 2(a). ) and (b) are cross-sectional explanatory views schematically showing the general configuration of the second embodiment of the above plasma etching apparatus, and a plan view of each electrode viewed from above, and FIG. FIG. 2 is an explanatory cross-sectional view schematically showing the general structure of an etching device, and a plan view of each electrode viewed from above. 1... Upper electrode (first planar electrode), 2...
Lower electrode (second planar electrode), 3... wafer, 4
．． 5... Electrode wiring, 7... High frequency power supply, 8...
... Electrode spacing, 3... Lines of electric force, 10... Tapered electrode portion. Agent Masuo Oiwa

Claims (3)

[Claims] (1) A first flat electrode and a second plate-shaped electrode that becomes a wafer stage.
In a plasma etching apparatus in which flat plate electrodes are arranged facing each other in parallel and a high frequency voltage can be applied between each of these electrodes, the distance between the electrodes at the peripheral part of at least one of the electrodes is A plasma etching apparatus characterized in that the plasma etching apparatus is configured to continuously change the direction between the electrodes. (2) Claims characterized in that a tapered electrode portion is formed in the peripheral portion of the first flat electrode toward the second flat electrode at a predetermined taper angle. The plasma etching apparatus according to item 1. (3) Claims characterized in that a tapered electrode part is formed in the peripheral part of the second flat electrode at a predetermined taper angle toward the first flat electrode. The plasma etching apparatus according to item 1.