JPH04240726A - Plasma dry etching device - Google Patents

Abstract

PURPOSE:To prevent the mixing and adhesion of foreign material for a semiconductor wafer by preventing a reaction product from adhering to the inner wall and the surface of each bellows of a reacting chamber as much as possible and removing the reaction product before peeling when it has adhered. CONSTITUTION:A bottom electrode (6) and a gate valve (17) are provided with dust proof tubes A (21), B (22) and a double tube (23). The device is provided with a labyrinth structure so as to prevent a reaction product from entering the surface and to prevent the peeled reaction product from the surface of each bellows from entering a reacting room. An insulating flange (20) is provided at the outer circumference of a top electrode (1) and the adhesion of the reaction product on the wall of a reacting chamber (2) is prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust-proof structure for a plasma dry etching apparatus used in a semiconductor manufacturing process.

0002

[Prior art] Volatile molecules are created by the reaction between reactive radical species such as fluorine atoms and chlorine atoms created in plasma and atoms in the solid, and are carried away, thereby scraping the solid surface. The phenomenon of plasma dry etching is well known and used as a semiconductor processing process.

FIG. 3 schematically shows a conventional apparatus for performing this type of plasma dry etching.

In the figure, a reaction chamber (2) is airtightly attached via an O-ring (7a) onto a vacuum container (7) whose interior is maintained in a high vacuum state.

[0005] An upper electrode (1) is disposed to penetrate from above the reaction chamber (2) into the interior thereof. Upper electrode (
An electrode plate (3) with a large number of gas holes (3a) is attached to the lower surface of the electrode plate (1). The gas hole (3) is inserted through the gas introduction hole (1a) formed inside the upper electrode (1).
A reaction gas is introduced into the reaction chamber (2) from a).

[0006] A lower electrode (6) is arranged parallel to and opposite to the upper electrode (1) at a constant interval.

A semiconductor wafer (5) to be processed is placed on the upper surface of the lower electrode (6), and a high frequency power source (19) is connected via a coaxial cable (19a).

[0008] When a voltage is applied from the high frequency power supply (19) with the upper electrode (1) grounded, both electrodes (
Plasma is generated in the plasma region (16a) between 1) and (6). As a result, the ions of the reaction gas are activated and reach the surface of the semiconductor wafer (5), etching the surface while generating reaction products.

[0009] Also, both bellows flanges (17b), (
A gate valve (17) formed by airtightly connecting a gate bellows (17d) is disposed between the valves (17c) and 17c). And the O mounted inside each bellows flange (17b), (17c)
A ring (17a) separates the reaction chamber (16) and the load lock chamber (9). The bellows rod (18) is
They are arranged in three equal parts on the circumference of the bellows flange (17b), and are connected to the connecting plate (
13). The connecting plate (13) is attached to the linear cylinder (12), and the connecting plate (13) is attached to the linear cylinder (12).
2) moves downward, the gate valve (17) opens downward, and the reaction chamber (16) and load lock chamber (9) are brought into the same pressure state. This gate valve (17) is connected to a semiconductor wafer (5).
) is used when putting in and taking out the lower electrode (6), and at this time the lower electrode (6) also descends to the lowest position (6a) shown by the broken line in the figure. The semiconductor wafer (5) is then taken out from the gate window (9a) by opening the gate shutter (8). Electrode bellows (4) hermetically coupled with the lower electrode (6)
is placed in the center to maintain airtightness from the outside. The lower electrode (6) is configured to be movable in the vertical direction by a cylinder (not shown) attached to the mechanism part (15) via an electrode bellows (4).

0010

In the configuration of the conventional apparatus described above, reaction products generated during etching scatter and directly adhere to the inner wall surface of the reaction chamber (2) and the surface of the bellows (4). And reaction chamber (2)
Reaction products adhering to the inner wall surface of the reactor are peeled off by convection due to pressure fluctuations during introduction of reaction gas, etc., and by external vibration.
Further, reaction products adhering to the surface of the bellows (4) are also mechanically peeled off by the expansion and contraction action of the bellows. The reaction product pieces peeled off in this way become foreign matter and enter the reaction chamber (2).
If they fly up and adhere to the surface of the semiconductor wafer (5), they cause pattern defects and reduce the yield of semiconductor devices.

[0011]

[Means for Solving the Problems] The present invention is designed to prevent reaction products from penetrating toward the surface of the bellows attached to the lower electrode and the gate valve, and to prevent the reaction products peeled from the bellows surface from reacting. To prevent the dust from entering the chamber, the dust-proof tube and double tube have a labyrinth structure, and an insulating flange is attached to the outer periphery of the upper electrode, leaving a gap such that the outer periphery of the insulating flange does not come into contact with the inner wall surface of the reaction chamber. This structure prevents reaction products from adhering to the upper wall of the chamber.

0012

[Operation] In the present invention, the reaction products around the lower electrode and the gate valve are difficult to enter the bellows surface due to the labyrinth structure of the dustproof cylinder and the double cylinder, and even if they do enter and adhere to the bellows surface and peel off. , it becomes difficult to get out into the reaction chamber.

[0013] Although reaction products adhere to the surfaces of the dust-proof cylinder and the double-walled cylinder, since the dust-proof cylinder does not expand and contract violently like a bellows, the reaction products are difficult to peel off.
Foreign matter flying up inside the reaction chamber is extremely reduced.

Furthermore, by creating a gap between the insulating collar attached to the upper electrode so that it does not come into contact with the inner wall surface of the reaction chamber, reaction products are less likely to enter the upper wall surface of the reaction chamber. Reaction products adhere to the surface of the insulating flange and the lower side wall of the reaction chamber, but since these are in the plasma region, a gas such as O2 or Cl2 is introduced to generate plasma in the same way as in etching processing, and the insulating flange is removed. Reaction products adhering to the surface and the lower side wall of the reaction chamber can be removed (this is called plasma cleaning).

[0015] As a result, it is possible to maintain a clean state in which little foreign matter is thrown up in the reaction chamber.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Incidentally, in the drawings, the same reference numerals are given to the same components as those of the conventional device, and the explanation thereof will be omitted.

FIG. 2 is a sectional view of the apparatus of the present invention, and FIG. 3 is a schematic perspective view of the double cylinder in FIG. 2.

In the figure, a ring-shaped insulating collar (20) is fixed to the electrode plate (3), and a cutout hole (20a) is made in the center of the ring-shaped insulating collar (20) so as not to block the gas hole (2a). The outer periphery thereof is held in a gap such that it does not come into contact with the lower side wall (2c) of the reaction chamber (2).

A dustproof tube A (2) is provided on the outer periphery of the lower electrode (6).
1) is attached, and its surface is similar to that of a semiconductor wafer (
5), and the other end side covers a part of the electrode bellows (4). Dustproof cylinder B (22
) is fixed to the inner periphery of the gate valve (17) and covers the bellows rod (18) and the gate bellows (17b). The lengths of the dustproof cylinders A (21) and B (22) are such that even if the lower electrode (6) and gate valve (17) move to the lowest end (the position when loading and unloading the semiconductor wafer (5)), The dimensions are set so that it does not touch the bottom surface.

The general structure of the double cylinder (23) is shown in FIG. 2, and it is arranged in a labyrinth structure between the dustproof cylinders A (21) and B (22). Tube (23b
) and outer cylinder (23c) are dustproof cylinders A (21) and B (22
) is set at a gap that does not touch each wall surface. Also,
The exhaust notch hole (23a) is set to a size that does not reduce the exhaust speed in the reaction chamber (2).

By attaching the insulating collar (20) to the electrode plate (3), the upper wall surface (
2b), reaction products are less likely to adhere to the upper side wall (2a).

[0022] The surface of the insulating collar (20) and the reaction chamber (
Although reaction products adhere to the lower side wall (2c) in 2), since this is in the plasma region, O2 or C
By introducing a gas such as 12-based gas and generating plasma in the same manner as in the etching process, reaction products adhering to each wall surface can be removed (this is called plasma cleaning).

Upper wall surface (2b) in reaction chamber (2)
The reason why reaction products are not allowed to adhere to the upper side wall (2a) is that plasma discharge does not occur in this area, so reaction products adhering to the wall surface cannot be removed.

[0024] Furthermore, by providing the dust-proof tubes A (21), B (22), and the double tube (23), reaction products are prevented from entering around the gate bellows (17b) and electrode bellows (4). A labyrinth structure is formed, which makes it difficult for the bellows to move, and the rate of reaction products adhering to the surface of each bellows is extremely low.

Although the reaction products adhere to the walls of the dust-proof cylinder A (21), dust-proof cylinder B (22), and double cylinder (23), they do not expand and contract violently like bellows, so the reaction products do not becomes difficult to peel off. As is clear from the figure,
These dustproof tube A (21), dustproof tube B (22), double tube (
23) has a structure that allows easy removal, so it can be removed periodically and reaction products adhering to the surface outside the apparatus can be easily removed by cleaning or the like.

[0026] As a result, adhesion of reaction products to the inner wall of the reaction chamber (2) and the surfaces of each bellows is significantly suppressed, and a clean state with less foreign matter flying up inside the reaction chamber can be maintained.

In this embodiment, a parallel plate type plasma dry etching apparatus has been described, but it is also applicable to other etching apparatuses, sputtering apparatuses, CVD apparatuses, etc.

[0028]

As explained above, according to the present invention, by providing the insulating flange, the dust-proof tube, and the double tube, reaction products generated during etching can be prevented from adhering to the inner wall surface of the reaction chamber and the surfaces of each bellows. This makes it possible to significantly reduce the proportion of foreign matter being thrown up, and it is possible to maintain the inside of the reaction chamber in a clean state with less foreign matter flying up. Thereby, it is possible to effectively prevent foreign matter from adhering to the surface of the semiconductor wafer during etching, thereby improving the quality and yield of semiconductor devices.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the schematic configuration of the device of the present invention.

FIG. 2 is a perspective view showing the structure of the double cylinder in FIG. 1;

FIG. 3 is a sectional view showing a schematic configuration of a conventional device.

[Explanation of symbols]

1 Upper electrode 2 Reaction chamber 5 Semiconductor wafer 6 Lower electrode 20 Insulating collar 21 Dustproof tube A 22 Dustproof tube B 23 Double tube

Claims (1)

[Claims] [Claim 1] A parallel plate plasma dry etching apparatus consisting of an upper electrode and a lower electrode in which a substrate to be etched is placed in a reaction vessel in which a high vacuum can be maintained by a vacuum gate valve. A ring-shaped insulating flange is attached, and the outer periphery of the insulating flange is provided with a gap that does not touch the inner wall of the reaction vessel.A cylindrical dust-proof cylinder is attached to the outer periphery of the lower electrode that moves up and down and the inner periphery of the gate valve. A double cylinder consisting of a double structure of an inner cylinder and an outer cylinder is installed between the electrode and the dustproof cylinder attached to the gate valve, and the gap between the dustproof cylinder and the dustproof cylinder is such that it does not come into contact with the dustproof cylinder. A plasma dry etching device characterized in that the outer cylinder of the cylinder has a notched hole for exhaust.