JP2978620B2 - Ashing device for resist film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ashing apparatus for a resist film, and more particularly, to an ashing apparatus for removing an unnecessary resist film on a wafer by a light ashing process in a process of manufacturing a semiconductor device such as an LSI.

[0002]

2. Description of the Related Art Conventionally, in a process of manufacturing a semiconductor device such as an LSI, an ashing method using oxygen plasma has been put to practical use as a method of removing an unnecessary resist film on a wafer after etching or ion implantation. However, in the ashing method using oxygen plasma, charged particles in the plasma, such as electrons and ions accelerated by an electric field, collide with the wafer, and the reaction heat at that time damages the surface of the wafer, resulting in electrical damage to the semiconductor elements. There is a problem of so-called plasma damage in which characteristics are impaired. In particular, with the demand for higher integration of semiconductor elements, the influence of plasma damage on electrical characteristics cannot be ignored.

Recently, as an ashing method for removing a resist film without damaging a semiconductor element, a light ashing method using ultraviolet rays emitted from an ultraviolet lamp has been proposed. This optical ashing method is performed by placing a wafer on which a resist film is formed in a processing chamber, introducing ozone into the processing chamber, and irradiating the resist film on the wafer with ultraviolet rays from an ultraviolet lamp.

FIG. 5 is a schematic sectional view showing an example of a conventional (light) ashing apparatus. In the figure, 1 is a processing chamber, 2 is an ozone introduction pipe, 3 is a gas exhaust port, 4 is a wafer holding table for mounting and holding a wafer W to be processed,
Reference numeral 5 denotes an ultraviolet lamp for irradiating the resist film on the wafer W with ultraviolet light, 6 denotes an ultraviolet reflection mirror, and 7 denotes an ultraviolet transmission window. Ozone from the ozone introduction pipe 2 causes the processing chamber 1
The inside is filled with an atmosphere containing ozone.

As the ultraviolet lamp 5, a low-pressure mercury lamp is usually used. This low pressure mercury lamp has 25
It is a bright line spectrum light source having a large bright line spectrum at 3.7 nm. Ozone (O ₃ ) introduced into the processing chamber
Is excited by light having a wavelength of 253.7 nm to become activated oxygen (O ^* ). Then, when the activated oxygen comes into contact with the resist film on the wafer W, the resist film made of an organic compound is oxidized and decomposed, and removed as CO ₂ or H ₂ O or the like.

[0006]

However, ultraviolet rays emitted from a low-pressure mercury lamp, that is, 253.7 n
In the optical ashing method using light having a wavelength of m, the processing speed is very slow, about １ ／, as compared with the ashing method using oxygen plasma.

The reason why the ashing processing speed is low is as follows. (1) In FIG. 5, the wafer W held in the processing chamber 1
The so-called ozone layer is interposed in the gap between the upper resist film and the ultraviolet transmission window 7. However, light having a wavelength of 253.7 nm emitted from a low-pressure mercury lamp at a large ratio has a large absorption coefficient to ozone and is very well absorbed by ozone. Therefore, the 253. radiated from the low pressure mercury lamp.
Most of the light having a wavelength of 7 nm is immediately absorbed by ozone near the ultraviolet transmission window 7 and does not reach the resist film on the wafer W. (2) The activated oxygen generated by the excitation of ozone is:
The lifetime is very short, and most of the activated oxygen generated near the ultraviolet transmission window 7 is deactivated before coming into contact with the resist film to be removed. (3) Since light having a wavelength of 253.7 nm does not reach the resist film, activated oxygen is not generated in the vicinity of the resist film, and activated oxygen generated at a position distant from the resist film. Since most of them are immediately deactivated, the contact efficiency between the activated oxygen and the resist film becomes very low.

[0008] In order to solve this problem, the present inventors first produced activated oxygen by using an ultraviolet lamp having continuous spectrum emission in a wavelength region of 200 to 300 nm, and this activated oxygen produced A technology for performing ashing processing has been proposed (Japanese Patent Application No. Hei 3-297610).
No.). According to the above technology, the absorption coefficient to ozone is relatively small, 200 to 240 nm and 270 to 240 nm.
The activation light is generated near the resist film by the light having the wavelength of 300 nm. As a result, the contact efficiency between the activation oxygen and the resist film is increased, and the ashing process can be performed to some extent quickly.

However, even in an ultraviolet lamp having continuous spectrum emission in a wavelength region of 200 to 300 nm, the emission spectrum distribution shows 253.7 nm.
Wavelength light occupies a large proportion, and the generation reaction of activated oxygen at a position away from the resist film to be removed is still performed. Therefore, a considerable amount of ozone is consumed due to the generation of activated oxygen that is not useful for the ashing process, and it is not possible to effectively use ozone. In addition, as a result of ozone being consumed for the generation of useless activated oxygen, the ozone concentration in the processing chamber is reduced, and the amount of useful activated oxygen generated in the vicinity of the resist film is reduced, thereby speeding up the processing. It cannot be achieved enough.

The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress the generation reaction of activated oxygen which is not useful for the treatment, thereby effectively utilizing ozone, and An object of the present invention is to provide a resist film ashing apparatus capable of increasing the contact efficiency between the activated oxygen and the resist film by increasing the amount of activated oxygen useful for the above, and performing the ashing process quickly.

[0011]

According to the present invention, there is provided a resist film ashing apparatus comprising: a processing chamber; an ozone introducing means for introducing ozone into the processing chamber; and a wafer holder for mounting and holding a wafer in the processing chamber. And an ultraviolet lamp for irradiating the resist film on the wafer with ultraviolet light, wherein between the wafer holding table and the ultraviolet lamp, 253 of the radiation light from the ultraviolet lamp is provided. A filter member for attenuating light having a wavelength around 0.7 nm is provided.

[0012]

In the ashing process by this ashing device, the light transmitted through the filter member out of the light emitted from the ultraviolet lamp is 25% in the spectrum distribution.
The light having a wavelength of 3.7 nm is attenuated. Accordingly, the generation reaction of activated oxygen that is not useful for the ashing process at a position distant from the resist film to be removed is suppressed, so that ozone can be effectively used. Also, in the spectrum distribution of light transmitted through the filter member, the ratio of ultraviolet rays having a relatively small absorption coefficient to ozone becomes relatively large, and the generation of useful activated oxygen near the resist film to be removed is efficiently performed. Often the result,
The contact efficiency between the activated oxygen and the resist film increases.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the ashing device of the present invention. In the figure, 10 is a processing chamber, 20 is an ozone introduction pipe, 15 is a gas exhaust port, 30
Numeral denotes a wafer holding table for mounting and holding the wafer W to be processed, 40 denotes an ultraviolet lamp for irradiating the resist film on the wafer W with ultraviolet light, 45 denotes an ultraviolet reflecting mirror, and 50 denotes an ultraviolet transmitting window.

The ozone introduction pipe 20 is for setting the inside of the processing chamber 10 to an atmosphere containing ozone. The other end of the ozone introduction pipe 20 is connected to an ozone generator (not shown). .

On the wafer holder 30, a wafer W having a resist film formed on its surface is placed and held.
A temperature control mechanism such as a heater or a water cooling pipe may be embedded in the wafer holder 30 as necessary.

The ultraviolet lamp 40 for irradiating the resist film on the wafer W with ultraviolet light preferably has a strong continuous spectrum emission in a wavelength region of 200 to 300 nm, and specifically, a high-pressure mercury lamp or a metal halide lamp. Etc. can be used.

The ultraviolet transmitting window 50 has a thickness of 200 to 240 nm.
And a light having a wavelength of 270 to 300 nm is efficiently transmitted and the absorption coefficient to ozone is large.
It also has a filter function for selectively attenuating light having a wavelength near m. Specifically, it can cut 50% or more of the light having a wavelength of 253.7 nm. The ultraviolet transmission window 50 having a filter function can be manufactured by depositing a dielectric multilayer film on a base material made of, for example, a quartz plate.

The lower surface of the ultraviolet transmission window 50 and the wafer holder 3
0 is preferably as small as possible as long as the laminar flow state of ozone supplied from the ozone introduction pipe 20 is not hindered.
It is about 5 mm.

According to the ashing process using the ashing apparatus of this embodiment, the light transmitted from the ultraviolet ray transmitting window 50 out of the ultraviolet ray lamp 40 or the ultraviolet reflecting mirror 45 has 253.7 in its spectral distribution.
nm wavelength light is attenuated, and the ratio of the 200-240 nm wavelength light and the 270-300 nm wavelength light becomes relatively large. Then, 2 which has a large absorption coefficient to ozone
By attenuating the light having a wavelength of about 53.7 nm, the generation reaction of activated oxygen near the ultraviolet transmission window 50 is suppressed, and effective use of ozone can be achieved. Also,
In the spectral distribution of the light transmitted through the ultraviolet transmitting window 50, the absorption coefficient to ozone is relatively small, from 200 to 24.
Since the proportions of light having wavelengths of 0 nm and 270 to 300 nm become relatively large, useful activated oxygen is efficiently generated in the vicinity of the resist film. As a result, the contact efficiency between the activated oxygen and the resist film is increased. Thus, the ashing process can be performed quickly.

<Experimental Example> An ashing process was performed by using the ashing apparatus having the above configuration, and the processing speed was measured. Here, as the resist, “TSMR-890
0 "(manufactured by Tokyo Ohka Kogyo Co., Ltd .: 1.65 μm in film thickness). As the ultraviolet lamp 40, a high-pressure mercury lamp (illuminance: 100 mW /
cm ₂ ) and the ozone concentration in the processing chamber 10 was 8%. The processing speed of this ashing device is about 4 μm /
Minutes. FIG. 3 shows the spectral distribution of light irradiated on the resist film by this ashing apparatus.

On the other hand, for comparison, the processing speed was measured under the same conditions using an ashing apparatus having an ultraviolet transmission window made of a quartz plate that efficiently transmits light in the wavelength region of 200 to 300 nm. The processing speed by this ashing device was about 3 μm / min. FIG. 4 shows the spectral distribution of light irradiated on the resist film by the ashing apparatus.

The embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments. For example, as shown in FIG. 2, light in the wavelength region of 200 to 300 nm is efficiently transmitted. An ultraviolet transmitting window 60 made of a quartz plate is used, and a filter member 70 for attenuating light having a wavelength of around 253.7 nm is separately provided between the ultraviolet transmitting window 60 and the wafer holder 30. You may. A filter member for attenuating light having a wavelength of around 253.7 nm may be provided between the ultraviolet lamp 40 and the ultraviolet transmission window 60.

[0023]

According to the ashing apparatus of the present invention, the effective use of ozone can be achieved, and useful activated oxygen can be efficiently generated. As a result, the contact efficiency between the activated oxygen and the resist film can be reduced. It is possible to perform the ashing process promptly.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an ashing device of the present invention.

FIG. 2 is a schematic sectional view showing another example of the ashing device of the present invention.

FIG. 3 is a diagram showing a wavelength distribution of light irradiated on a resist film by the ashing apparatus of the present invention.

FIG. 4 is a diagram showing a wavelength distribution of irradiation light to a resist film by an ashing apparatus used for comparison.

FIG. 5 is a schematic sectional view showing an example of a conventional optical ashing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Processing chamber 15 Exhaust port 20 Ozone introduction pipe 30 Wafer holder 40 Ultraviolet lamp 45 Ultraviolet reflection mirror 50 Ultraviolet transmission window 60 Ultraviolet transmission window 70 Filter member

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-60-225427 (JP, A) JP-A-64-4024 (JP, A) JP-A-1-157528 (JP, A) JP-A 59-225 33830 (JP, A) Hira 1-84427 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/027

Claims (1)

(57) [Claims] A processing chamber; an ozone introducing means for introducing ozone into the processing chamber; a wafer holding table for mounting and holding a wafer in the processing chamber; and an ultraviolet lamp for irradiating a resist film on the wafer with ultraviolet light. In a resist film ashing apparatus comprising: a filter member for attenuating light having a wavelength of about 253.7 nm among light emitted from the ultraviolet lamp is provided between the wafer holder and the ultraviolet lamp. An ashing apparatus for a resist film.