JPS61292920A - Plasma treater - Google Patents

Abstract

PURPOSE:To feed an introduced treating gas equally extending over a central section from a peripheral section to a plasma atmosphere, and to ensure the uniformity of the state of treatment regarding the whole material to be treated by providing plurality of through-holes to a second electrode by drilling. CONSTITUTION:When a wafer 1 is placed on a lower electrode 5 and the inside of a treating chamber 2 is evacuated, an etching gas is introduced from an introducing port 10a through a feed passage 10 for a holder 7 while voltage is applied to both electrodes 5, 6 thus generating a plasma etching reaction. The etching gas 9 flowed out to the back of the upper electrode 6 from the introducing port 10a flows through the upper space of the wafer 1 from a through-hole 11 group and an outer circumferential section. The sectional areas and density of the openings are set at small values in the peripheral section in the through-hole 11 group at that time, thus equalizing the concentration distribution of the etching gas in the upper space of the wafer 1 extending over the whole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a processing technology that utilizes a plasma reaction, particularly a dry etching technology that performs an etching process using a plasma reaction.
This invention relates to a technique that is effective when used to perform an etching process on a wafer.

[Background technology]

In the manufacturing of semiconductor devices, dry etching equipment is used to perform etching on thin films on wafers.The wafer is held by the lower electrode of parallel plate electrodes arranged above and below, and the plasma formed between the two electrodes and the upper electrode are used as dry etching equipment. A conceivable device is one configured to perform the etching process by an etching reaction with an etching gas introduced into the back space and supplied to the processing chamber.

However, in such dry etching equipment,
The etching gas introduced into the back space of the upper electrode is supplied from the outer periphery of the upper electrode into the plasma atmosphere, so that the concentration distribution of the etching gas differs between the periphery and the center, resulting in a wafer with a large diameter. The inventors have discovered that when the wafer becomes more uniform, it becomes difficult to ensure uniformity of the etching rate within the wafer from the periphery to the center.

As an example of dry etching technology,
"Electronic Materials November 1984 Special Edition" published by Kogyo Research Association Co., Ltd., November 20, 1984, P97-P101
There is.

[Purpose of the invention]

An object of the present invention is to provide a processing technique that can ensure uniformity of the processing state over the entire object to be processed, regardless of the size of the object.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, by opening a plurality of through holes in the second electrode through which the processing gas is introduced into the back space, the processing gas introduced into the back space of the second electrode flows into the plasma atmosphere from the periphery to the center through the through holes. It is designed to ensure the uniformity of the processing state over the entire object to be processed by supplying it evenly over the entire object.

〔Example〕

FIG. 1 is a vertical cross-sectional view showing a dry etching apparatus according to an embodiment of the present invention, FIG. 2 is a plan cross-sectional view taken along the line ■-■ in FIG. 1, and FIGS. 3, 4, and 5. are each schematic diagram for explaining the action.

In this embodiment, the dry etching apparatus is equipped with a processing chamber 2 for processing a wafer 1 as an object to be processed, and the processing chamber 2 has an opening 3 for inserting and removing the wafer 1 therein. The processing chamber 2 has an exhaust port 4 arranged on the bottom wall for evacuating the inside of the chamber.

In the lower and upper parts of the processing chamber 2, a lower electrode 5 and an upper electrode 6 as first and second electrodes are arranged horizontally so as to form parallel plate electrodes, and the upper and lower electrodes 6.5 A high frequency aRF is connected between them. The lower electrode 5 is configured to place and hold a wafer as an object to be processed. The upper electrode 6 has a solid shaft portion 6a removably inserted into a holder 7 made of an insulating material such as fluororesin, and is screwed with a bolt 8. The holder 7 is attached to the ceiling of the processing chamber 2. It is fixed in the center of the wall.

A gas supply path 10 is formed inside the holder 7 to supply an etching gas (for example, CF4, CCl4, etc.) 9 as a processing gas. Etching gas 9
It faces the back surface of the upper electrode 6 so as to introduce it into the back space of the upper electrode 6.

The upper electrode 6 is formed into a disk shape, and has a plurality of through holes 1.
1 is provided in each thickness direction.

The through holes 11 are formed in a substantially hollow cylindrical shape, and are opened in the upper electrode 6 so as to be arranged radially symmetrically with respect to the center thereof. As a result, the density of the opening cross-sectional area of the group of through holes 11 is greater in the center than in the periphery. It is desirable that the corners of the through hole 11 be chamfered to avoid concentration of the electric field.

Next, the action will be explained.

When the wafer 1 is placed on the lower electrode 5 and the inside of the processing chamber 2 is evacuated, the inlet 10a is opened through the supply path 10 of the holder 7.
Etching gas is introduced from both electrodes 5.
A voltage is applied to 6 to induce a plasma etching reaction.

By the way, the flow of the etching gas in the case where no through hole is formed in the upper electrode is as shown in Fig. 3, so that the concentration distribution of the etching gas 9 with respect to the wafer 1 is concentrated at the periphery and thin at the center. The inventor has discovered that this tendency tends to occur.

When plasma is formed under such an etching gas concentration distribution, the concentration distribution of the etching reaction active species follows the gas concentration distribution, resulting in variations in the etching rate for the wafer.

If variations occur in the etching rate, for example, if the etching end point detection section is set at the center of the wafer where the etching rate becomes small, a predetermined etching state Ao will be obtained at the center, as shown in FIG. However, in the periphery of the wafer where the etching rate is high, an over-etching state Ax occurs with respect to the predetermined etching state AO.

On the other hand, if the etching end point detection section is set at the wafer periphery where the etching rate is high, as shown in FIG. etching-like pQA
This results in an insufficient etching state A2 for o.

In FIGS. 4 and 5, 12 is a 5in2 film formed on the wafer 1, and 13 is a resist film for forming a backing.

However, in this embodiment, the etching rate is uniform over the entire wafer 1 due to the plurality of through holes 11 formed in the upper electrode 6, so that the etching condition is uniform from the periphery to the center of the wafer 1. become.

That is, the etching gas 9 flowing out from the inlet 10a to the back surface of the upper electrode 6 flows into the space above the wafer 1 from the group of through holes 11 and the outer periphery. At this time, since the opening cross-sectional area density of the group of through holes 11 is set to be small in the peripheral portion, the concentration distribution of the etching gas in the space above the wafer 1 becomes uniform over the entire area.

In this way, since the concentration distribution of the etching gas becomes uniform over the entire area, the concentration distribution of the species active in the etching reaction by the plasma also becomes uniform, so that the etching rate for the wafer also becomes uniform.

When the etching rate becomes uniform over the entire wafer, the etching state will be the same no matter where on the wafer the etching end point detection section is set, so a predetermined etching state can be uniformly obtained from the periphery to the center of the wafer. It turns out.

If the upper electrode 6 is contaminated or damaged, the upper electrode 6 is removed from the holder 7 and regenerated by cleaning or polishing, or replaced with a new one. In this case, since the upper electrode 6 is formed into a plate shape without covering the back space, recycling operations such as cleaning and polishing can be easily performed.

〔effect〕

(1) By opening a plurality of through holes in the second electrode through which the processing gas is introduced into the back space, the processing gas introduced into the back space of the second electrode is supplied to the plasma atmosphere through the through holes. , it is possible to make the concentration distribution of the processing gas uniform over the entire object to be processed.

(2) By uniformizing the concentration distribution of the processing gas with respect to the object to be processed, the concentration distribution of the reactive species can be made uniform, so that the processing state due to the reaction can be made uniform throughout.

(3) By ensuring the uniformity of the processing state of the objects to be processed, it is possible to cope with the increase in the size of the objects to be processed, and it is also possible to equalize the quality of the products after processing.

(4) By forming the second electrode into a plate shape without covering the back space, regeneration work such as cleaning and polishing can be easily performed, thereby improving maintenance workability and operating efficiency. can.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the second electrode is not limited to having a plate shape, but may be configured such that a cover is provided in the back space and the processing gas is introduced into the cover.

The shape, diameter, arrangement, opening cross-sectional area density, etc. of the through-holes formed in the second electrode may be appropriately set so that the concentration distribution of the processing gas with respect to the object to be processed is uniform throughout.

[Application field]

In the above explanation, the invention made by the present inventor was mainly applied to a parallel plate type dry etching apparatus, which is the background field of application. It can also be applied to

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a dry etching apparatus according to an embodiment of the present invention, FIG. 2 is a plan cross-sectional view taken along line 11 in FIG. 1, and FIGS. FIG. 1... Wafer (workpiece), 2... Processing chamber, 3...
・Inlet/outlet port, 4...Exhaust port, 5...Lower electrode (first electrode), 6...Upper electrode (second electrode), 7...Holder, 8...Volt, 9...・Etching gas (processing gas), 10... Supply path, 10a... Inlet, 11
...Through hole, 12...5ins film, 13...Resist film. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A first electrode that holds an object to be processed, a second electrode that forms plasma in cooperation with the first electrode, and an inlet that introduces a processing gas into the space behind the second electrode. and the second
A plasma processing device with multiple through holes in the electrode. 2. The plasma processing apparatus according to claim 1, wherein the through holes are opened so that the concentration distribution of the processing gas with respect to the object to be processed is uniform. 3. The plasma processing apparatus according to claim 1, wherein the second electrode has a plate shape with an open back space. 4. The plasma processing according to claim 1, wherein the second electrode is configured such that its rear space is covered and the processing gas is introduced into the space within the cover. Device. 5. The plasma processing apparatus according to claim 1, wherein the through-holes are set such that the density of the opening cross-sectional area of the group of through-holes is larger in the central part than in the peripheral part. .