JPH08130185A - Plasma ashing apparatus - Google Patents

Abstract

PURPOSE: To provide a plasma ashing apparatus which gives little damage to a wafer and shows a high ashing rate. CONSTITUTION: The outer circumference of the upper half part 2a (plasma generating chamber 4) of a plasma generating tube 2 is surrounded by a pair of outer electrodes 6a and 6b. A wafer stage 9 is so provided as to look into the bottom end opening 20 of a plasma reaction chamber 8. A reactive gas introducing inlet 3 is linked with the plasma generating chamber 4. Exhaust outlets 12 are provided near the circumference of the wafer stage 9. The pair of the outer electrodes 6a and 6b are respectively formed into strips and the strip electrodes 6a and 6b are spirally wound on the upper half part 2a of the plasma generating tube 2 with a predetermined pitch. A high frequency power supply 5 is connected to one 6a of the strip electrodes 6a and 6b and an earth is connected to the other electrode 6b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma ashing apparatus used for removing a photoresist film formed on the surface of a semiconductor wafer (hereinafter, simply referred to as a wafer), and more specifically, a single-wafer downflow type. Related to the plasma ashing device.

[0002]

2. Description of the Related Art A plasma ashing apparatus of this type is disclosed in, for example, Japanese Patent Laid-Open No. 63-260030, and FIG. 2 shows an example of the configuration of a conventional plasma ashing apparatus.

FIG. 2 is a schematic view of a main part of a conventional plasma ashing apparatus, in which a top half portion 2a is, as shown in FIG.
Plasma generation tube 2 including a plasma generation chamber 4 provided with a reaction gas inlet 3 in communication with each other, and a plasma reaction chamber 8 having a lower half portion 2b having an open lower end, and an outer periphery of the plasma generation chamber 4. A pair of external electrodes 6a and 6b provided so as to surround the wafer, a wafer stage 9 arranged so as to face the lower end opening 20 of the plasma reaction chamber 8, and at least the plasma generation tube 2 and the wafer stage 9. By making one of them relatively close to each other in the vertical direction, the wafer W mounted on the wafer stage 9 is inserted into the plasma reaction chamber 8 through the lower end opening 20 thereof to hermetically close the lower end opening 20 side, On the other hand, the plasma generating tube 2 and the wafer stage 9
Are relatively spaced in the vertical direction, so that the lower end opening 20 side is opened from inside the plasma reaction chamber 8 and the wafer W
An up-and-down moving unit (not shown) for carrying out the wafer and an exhaust port 12 provided near the periphery of the wafer stage 9 are provided. The pair of external electrodes 6a and 6b are each formed in a semi-cylindrical shape, and one electrode 6a is connected to a high frequency power source and the other electrode 6b is connected to a ground.

[0004]

In the above-mentioned conventional example, since the pair of external electrodes 6a and 6b are formed in a semi-cylindrical shape,
The charge-up becomes too large and the wafer is damaged. Further, if the applied power is reduced in order to reduce the damage on the wafer, the ashing rate decreases. The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a plasma ashing apparatus that causes less damage to a wafer and has a high ashing rate.

[0005]

Means adopted by the present invention for solving the above-mentioned problems are as follows. In the above-mentioned conventional plasma processing apparatus, a pair of external electrodes are formed in strips, respectively.
It is characterized in that these strip electrodes are spirally wound around the plasma generating chamber at a predetermined pitch, a high frequency power source is connected to one strip electrode, and a ground is connected to the other strip power source.

[0006]

According to the present invention, the pair of external electrodes are formed in a strip shape, and these strip electrodes are spirally wound around the plasma generating chamber at a predetermined pitch. A stable plasma can be obtained over a wide range along the strip electrodes. That is, a large amount of plasma radicals and ionized ions are generated in the plasma generation chamber with high density. Then, by controlling the processing parameters such as the supply amount of the reaction gas and setting the required amount of ion particle density to be high, the ratio of radicals and ionized ions on the wafer is appropriately set in the plasma reaction chamber to achieve low temperature processing. The photoresist film can be peeled off cleanly from the surface layer of the wafer, and low-damage processing can be realized.

[0007]

Embodiments of the present invention will now be described in more detail with reference to the drawings. FIG. 1 is a schematic view of a main part fractured view of a plasma ashing apparatus according to an embodiment of the present invention. This plasma ashing device has the same basic structure as the conventional example (FIG. 2). That is, the plasma generating tube 2 detachably mounted on the base 1 via the airtight seal 1a, and the plasma generating tube 2
A pair of external electrodes 6a and 6b attached so as to surround the outer periphery of the upper half small diameter portion 2a and the lower end opening 20 in the lower half large diameter portion 2b (plasma reaction chamber 8) of the plasma generating tube 2 are exposed. Provided on the wafer stage 9 and the plasma generation tube 2
And a wafer stage 9 for moving the wafer stage 9 and the wafer stage 9 in the vertical direction relative to each other.
And an exhaust port 12 opening around the periphery of the.

A plasma generating chamber 4 is provided inside the upper-half small-diameter portion 2a of the plasma generating tube 2, and a reaction gas inlet 3 is provided in communication with the plasma generating chamber 4. The pair of external electrodes 6a and 6b, which characterize the present invention, are formed in strips, and these strip-shaped electrodes 6a and 6b are arranged on the plasma generating tube 2 at a predetermined pitch, for example, at a pitch of 10 mm or less. It is spirally wound around the outer periphery of the half part 2a, and the high frequency power source 5 is connected to one of the strip electrodes 6a,
The ground is connected to the other strip electrode 6b. Further, the ground is connected to the wafer stage 9.

In the apparatus of the above embodiment, the photoresist film formed on the surface of the wafer W is removed as follows. First, the plasma generating tube 2 is lifted from the position shown in FIG. 1 by a vertical moving means (not shown), then an unprocessed wafer W is transferred onto the wafer stage 9 by a wafer transfer arm (not shown), and the plasma generating tube 2 is again moved. Is lowered by a vertical moving means (not shown), an unprocessed wafer W is inserted from the lower end opening 20 to hermetically close the lower end opening 20 side of the plasma reaction chamber 8 of the plasma generation tube 2, and then suction is performed from the exhaust port 12. While decompressing the inside of the plasma generating tube 2 and introducing a mixed gas of, for example, CF ₄ (5% by volume) and O ₂ (95% by volume) as a reaction gas G from the reaction gas introducing tube 3, one strip electrode The high frequency power source 5 is connected to 6a, and the ground is connected to the other strip electrode 6b.

Then, in the plasma generating chamber 4, a stable plasma can be obtained over a wide range along the pair of spiral belt-shaped electrodes 6a and 6b. That is, in the plasma generation chamber 4, a large amount of plasma radicals and ionized ions are generated with high density. In the plasma reaction chamber 8, the plasma radicals and ionized ions reach the surface of the wafer W by suction from the exhaust port 12, react with the photoresist film, and the photoresist film is ashed and removed. When the processing of the wafer W is completed, the plasma generating tube 2 is raised by the vertical moving means (not shown), whereby the lower end opening 20 of the plasma reaction chamber 8 of the plasma generating tube 2 is opened to the atmosphere, and the processed wafer W is shown. Not carried out from the wafer stage 9 by the substrate transfer arm.

By controlling the processing parameters such as the supply amount of the reaction gas G and setting the required amount of ion particle density to be high, the ratio of radicals on the wafer W to ionized ions in the plasma reaction chamber 8 is increased. It can be set appropriately. Incidentally, in this embodiment, due to the use of high frequency power source 13.56MH _Z to a pair of strip electrodes 6a · 6b forming a spiral, while suppressing the temperature rise of the wafer W during processing, high dose ion implantation It is possible to cleanly remove the photoresist film which has been deteriorated from the surface layer of the wafer, and to realize low-damage processing. Further, in the above embodiment, it is possible to achieve an ashing rate of 4.1 μm / min or more.

In the above embodiment, the pair of external electrodes 6a and 6b are shown as having two strips for the sake of simplicity, but these strip electrodes 6a and 6b should be made up of more strips. You can also Further, although the wafer stage 9 is connected to the ground in the above embodiment, it is not always necessary to connect it to the ground. Further, in the above embodiment, the upper half 2a of the plasma generating tube 2 has a small diameter and the lower half 2b has a large diameter. However, the upper half 2a and the lower half 2 are illustrated.
b may have the same diameter and can be carried out by appropriately changing it.

[0013]

According to the present invention, the pair of external electrodes are formed in a strip shape, and these strip electrodes are spirally wound around the plasma generating chamber at a predetermined pitch. A stable plasma can be obtained over a wide range along the pair of strip electrodes, the photoresist film can be cleanly stripped from the wafer surface layer at low temperature processing, low damage processing can be realized, and the ashing rate is further increased. be able to.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part fractured view of a plasma ashing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a main part broken view of a plasma ashing apparatus according to a conventional example.

[Explanation of symbols]

2 ... Plasma generation tube, 2a ... Upper half of plasma generation tube,
2b ... Lower half of plasma generating tube, 3 ... Reactant gas inlet, 4 ... Plasma generating chamber, 5 ... High frequency power source, 6a and 6b
... a pair of external electrodes, 8 ... Plasma reaction chamber, 9 ... Wafer stage, 12 ... Exhaust port, 20 ... Lower end opening of plasma reaction chamber, W ... Wafer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H01L 21/304 341 D H05H 1/46 L 9216-2G (72) Inventor Sadao Hiraku Kyoto Prefecture Kyoto 322 Furukawa-cho, Fukumi-ku, Fushimi-ku, Japan Rakusai Factory, Dainippon Screen Mfg. Co., Ltd.

Claims (1)

[Claims] 1. A plasma generating tube comprising: a plasma generating chamber having a reaction gas inlet in communication with the upper half thereof; and a plasma reaction chamber having a lower end opened in the lower half thereof; A pair of external electrodes provided so as to surround the outer periphery of the generation chamber, a wafer stage disposed so as to face the lower end opening of the plasma reaction chamber, and at least one of the plasma generation tube and the wafer stage are opposed to each other. In a plasma ashing apparatus comprising a vertical moving means for moving vertically in the vertical direction, and an exhaust port provided in the vicinity of the periphery of the wafer stage, a pair of external electrodes are formed in a strip shape, and these strip electrodes are formed. It was constructed by spirally winding it around the outer circumference of the plasma generation chamber at a predetermined pitch, connecting a high frequency power source to one strip electrode and connecting the ground to the other strip electrode. Plasmapheresis ashing apparatus according to symptoms.