JPH0622220B2 - Resist ashing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a resist ashing method and apparatus for ashing and removing a resist film on a surface of an object to be processed in, for example, a wafer process for manufacturing a semiconductor device.

When performing ion implantation or etching in a wafer process in semiconductor device manufacturing, if it is limited to a local part of the wafer, it can be performed by using a resist film formed by applying a resist on the wafer and patterning it as a mask. Many.

In this case, it is necessary to remove the resist film used as a mask after ion implantation or etching.

In order to remove this resist film, a wet process using a liquid chemical has been conventionally applied, but with the miniaturization of patterns, there is less contamination of the wafer and the process is simpler than the wet process, that is, the resist process. The method of ashing (gasifying) and removing it has come to be adopted.

However, since the resist film may not be sufficiently removed by the current method of resist ashing, improvement of the method is desired.

[Conventional technology]

In the conventional resist ashing method, oxygen plasma is made to act on the resist film on the surface to be treated to ash (gasify) the resist film. That is, the polymer resin resist chemically reacts with atomic oxygen generated in oxygen plasma to lower the molecular weight, and further decomposes into carbon gas and water vapor by oxidation,
It uses the action of gasification.

The structure of the apparatus for carrying out this method is, for example, as shown in FIG. 3 (b) which is a side sectional view.

In the figure, 1 is a treatment chamber having a closed structure, 2 is a gas inlet for introducing oxygen into the treatment chamber 1, 3 is a gas outlet for discharging gas in the treatment chamber 1, and 4 is oxygen in the treatment chamber 1. Is a high-frequency coil that turns into plasma.

The resist film on the surface of the object to be processed S such as a wafer is ashed and removed by placing the object to be processed S on the boat 5 and putting it in the processing chamber 1, and then in the processing chamber 1 an oxygen atmosphere (for example, about 1 To).
rr)), and the oxygen is turned into plasma by the operation of the high frequency coil 4. Then, while the oxygen plasma is being applied, the supply of oxygen and the discharge of the gas containing the gas decomposed by the resist are continuously performed.

[Problems to be solved by the invention]

However, since the surface layer of the ashing resist film is altered during ion implantation used as a mask, the surface portion cannot be completely decomposed by the above-mentioned ashing method, and residues and decomposed substances are different. In some cases, a so-called deposit film, which becomes a foreign matter film, is generated on the surface after ashing, and the resist film may not be sufficiently removed.

In such a case, the treatment by the wet process is usually added as shown by the broken line in the process chart shown in FIG. There is a problem that the effect of switching cannot be fully exerted and the process becomes complicated.

Nevertheless, the use of the above resist ashing method has an advantage that the degree of contamination of the object S to be processed can be reduced because the amount of liquid chemicals is less contaminated than in the wet process from the beginning.

Further, when the resist film is used as an etching mask, the etching is shifting to dry etching due to the miniaturization of the pattern, and the surface layer of the resist film is also deteriorated. In the ashing of the resist film in this case, usually the above-mentioned residue and the deposition film are not generated, and the removal of the resist film is completed by a dry process, but the ashing takes a long time to improve the productivity. There is a problem of lowering.

[Means for solving problems]

The above problems are caused by placing an object to be treated, which is formed by depositing a resist film having a surface-altered layer formed by irradiation of charged particles, on an ozone-containing oxygen atmosphere, and irradiating the resist film surface with short wavelength ultraviolet rays. And ozone to act to gasify and remove at least the surface-altered layer of the resist film, and then to act oxygen-containing plasma on the object to be treated to gasify and remove the remaining resist film And a resist ashing method of the present invention having

Further, in carrying out this method, a processing chamber for accommodating an object to be processed and introducing oxygen, a mechanism for irradiating the object in the processing chamber with short-wavelength ultraviolet light, and a mechanism for converting oxygen in the processing chamber into plasma It is preferable to use the resist ashing apparatus of the present invention which comprises

[Action]

When an organic substance placed in an atmosphere containing oxygen is irradiated with short-wavelength ultraviolet light, the organic substance is covered with ozone generated by the ultraviolet light and the chemical bond is broken by the energy of the ultraviolet light, so that the organic substance is decomposed and gasified. It is known.
(For example, literature, cleaning design, 1984 Summer, P.21).

This action selectively acts on organic substances, is stronger than the action of oxygen plasma, and cannot be completely decomposed by the conventional resist ashing method. It fully decomposes and gasifies the residue and the deposition film described above. However, it takes a long time to gasify the entire resist film.

Therefore, the gasification (ashing) of the deteriorated layer or residue and the deposition film is performed by irradiating the short-wavelength ultraviolet light, and most of the resist film is ashed by the conventional method using oxygen plasma. It is possible to completely remove the resist film without significantly extending the film thickness.

By doing so, even if a residue or a deposition film is generated in the conventional resist ashing method, the subsequent treatment by the wet process is unnecessary, and the effect of switching to the dry process is sufficiently exerted. That is, it is possible to reduce contamination on the object to be processed and simplify the process.

In order to carry out this resist ashing method, the step of irradiating short wavelength ultraviolet rays and the step of applying oxygen plasma may be performed by different devices, but by using the device of the present invention, both steps are performed. Since they can be processed by the same device, the frequency of manual handling of the object to be processed is reduced, and the effect of reducing contamination on the object to be processed is further increased.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals denote the same objects throughout the drawings.

FIG. 1 (a) is a process diagram of resist film removal according to an embodiment of the resist ashing method of the present invention, and FIG. 1 (b) shows a structure of an embodiment of a resist ashing apparatus used in the method. FIG. 2 is a side sectional view showing a step of removing a resist film according to another embodiment of the same method.

FIGS. 1 (a) and 1 (b) are views corresponding to FIGS. 3 (a) and 3 (b) showing a conventional process and apparatus, respectively.

All the steps shown in FIG. 1 (a) are dry processes, and are included in the resist ashing method of the present invention.

That is, in the first step, the object to be processed is placed in an atmosphere containing oxygen, ozone is generated by the ultraviolet rays while irradiating the object to be processed with short-wavelength ultraviolet light, and the surface of the object to be processed used for ion implantation or dry etching. Is a step of ashing the altered layer of the resist film, and the second step is a step of ashing the resist film after the altered layer is removed by a conventional resist ashing method.

According to this method, the resist film is surely gasified in each step, and no residue or deposit film is generated in the resist film used as the mask for ion implantation, and therefore the subsequent wet process is not necessary.

Also, in the resist film used as a mask for dry etching, the time required for ashing is about 1 / th that of the conventional method.
Shorten to 2.

The device for carrying out this method is, for the reasons stated above,
It is desirable that the first step and the second step can be performed, and the apparatus shown in FIG. 1 (b) is one example.

This apparatus is basically an apparatus in which an ultraviolet ray emitting tube 6 for irradiating an object S to be treated with short wavelength ultraviolet rays is added to the apparatus shown in FIG. 3 (b).

The arc tube 6 is a tube-shaped arc tube, for example, a low pressure mercury lamp, which is suitable for emitting short-wavelength ultraviolet rays that ozoneize oxygen and is wound around the outside of the processing chamber 1 in a coil shape. Further, the processing chamber 1 is made of, for example, quartz glass in order to transmit this ultraviolet ray.

When the resist film on the surface of the object S to be processed such as a wafer is ashed by this apparatus, the object S to be processed is boat 5 as shown in the drawing.
By arranging them in parallel with each other and putting them in the processing chamber 1,
The entire surface of the resist film can be irradiated with the ultraviolet rays from the arc tube 6. The oxygen pressure in the processing chamber 1 may be, for example, about 1 Torr, as is conventional. Then, the arc tube 6 may be turned on in the first step, and the high frequency coil 4 may be operated in the second step. Therefore, in this apparatus, it is not necessary to touch the object S to be processed between the first and second steps.

The process shown in FIG. 2 is similar to the process shown in FIG.
All steps are dry processes and are included in the resist ashing method of the present invention.

That is, in this step, the order of the first and second steps shown in FIG. 1 (a) is reversed, and irradiation with short wavelength ultraviolet rays is performed after the conventional resist ashing method is performed. The UV irradiation in this case is performed to remove the residue and the deposition film in the resist film used as the mask for ion implantation. Instead of the conventional wet process, the residue and the deposition film are completely replaced with gas to remove the wet film. Eliminates the need for processing.

It can be easily understood that this method can be carried out by the apparatus shown in FIG. 1 (b) even if the explanation is omitted.

〔The invention's effect〕

As described above, according to the configuration of the present invention, the resist ash that completely dry-processes the resist film used for ion etching and shortens the ashing time for the resist film used for dry etching. And a device suitable for carrying out the method can be provided,
For example, there is an effect that it is possible to improve the quality and productivity of resist film removal in a wafer process for manufacturing a semiconductor device.

[Brief description of drawings]

In the drawings, FIG. 1 (a) is a process diagram of resist film removal by an embodiment of the resist ashing method of the present invention, and FIG. 1 (b) is an embodiment of a resist ashing apparatus used in the method. FIG. 3 is a side sectional view showing the structure, FIG. 2 is a process drawing of a resist film removal by another embodiment of the same method, and FIG. 3 (a) is a process drawing of a resist film removal by a conventional resist ashing method. FIG. 1B is a side sectional view showing the structure of an example of a resist ashing apparatus used in the method. In the figure, 1 is a processing chamber, 2 is a gas inlet, 3 is a gas outlet, 4 is a high-frequency coil, 5 is a boat, 6 is an ultraviolet light emitting tube, and S is an object to be treated.

Claims (1)

[Claims] 1. An object to be treated having a resist film having a surface-altered layer formed by irradiation of charged particles deposited on the surface thereof is placed in an ozone-containing oxygen atmosphere, and the surface of the resist film is irradiated with short wavelength ultraviolet rays. And ozone to act to gasify and remove at least the surface-altered layer of the resist film, and then to act on the object to be treated with oxygen-containing plasma to gasify and remove the remaining resist film. A method for ashing resist.