JPH04307734A - Ashing apparatus - Google Patents

Abstract

PURPOSE:To provide an ashing apparatus which causes little damage to a wafer and which can remove especially resist which has adhered to the side face or the rear face of the wafer. CONSTITUTION:A stage 7 which is provided with a heating means used to raise a substrate temperature is installed. The following are installed at the stage 7: a reflecting plate 5 used to irradiate the rear of a substrate 4; and a spacer 6 used to form a definite interval between the surface of the substrate 4 and the surface the reflecting plate 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ashing device that decomposes and removes a polymer film pattern such as a resist formed on a substrate by treating it with ultraviolet light and ozone gas.

0002

[Prior art and its problems] Generally, in the manufacturing process of semiconductor integrated circuits, a pattern of a photoresist film formed by exposure and development is used as a mask during etching, and it is necessary to remove it from the surface of the wafer after the etching process. There is. Ashing processing is performed as a method for removing this photoresist film.

Conventional ashing equipment uses a plasma ashing method in which after evacuating the processing chamber to a vacuum, a reactive gas is introduced, high frequency power is applied, plasma discharge is caused, and ashing is performed using the excited reactive gas. Common.

In this plasma ashing method, active radicals and ions promote reactions and enable high-speed processing, but on the other hand, since the wafer is exposed to plasma, the ions bombard the wafer and the amount of charge increases. There is so-called plasma damage such as this, and this becomes a problem as circuit patterns become finer.

On the other hand, an ashing method using ultraviolet light has also been known. In this method, a wafer having a resist layer is placed in a processing chamber, irradiation is performed through a window from an ultraviolet lamp at the top of the processing chamber, and an ashing gas is introduced into the processing chamber to act on the wafer, thereby performing ashing processing.

Unlike plasma ashing, this method causes less damage to the wafer, but the ashing speed is slow, the processing time is long, and the processing efficiency is low. Furthermore,
When placing a wafer coated with resist on the stage, the back side of the wafer is likely to become contaminated if placed directly, and since light and ozone gas do not penetrate sufficiently around the sides and back of the wafer, the side surfaces of the wafer that adhere when coating with a spin coater There were also disadvantages such as the resist on the back side was difficult to ash and could not be removed.

[0007]

[Means for Solving the Problems] The present invention has been made to address the problems of the prior art, and its purpose is to cause less damage to wafers, especially to the side surfaces and surfaces of wafers. An object of the present invention is to provide an ashing device that can also remove resist attached to the back surface.

To this end, the present invention provides an apparatus for ashing a polymer film on a substrate by irradiating ultraviolet rays and supplying a gas containing ozone, in which a stage equipped with a heating means for raising the temperature of the substrate is installed, The present invention provides an ashing device characterized in that the stage is provided with a reflector for illuminating the back side of the substrate and a spacer for forming a constant distance between the surface of the substrate and the surface of the reflector.

[0009]

[Operation] In the ashing device of the present invention, first, the
One wafer is carried in and placed on a stage that has been heated to a preset temperature. A predetermined amount of ozone-containing gas is supplied into the processing chamber from the opening of the gas supply pipe close to the wafer surface, and the processed waste gas is exhausted from the exhaust port to create a gas flow state.

When the wafer is irradiated with ultraviolet light from the lamp through the light-transmitting window of synthetic quartz glass, the polymer film on the surface of the wafer is ashed according to the following principle. A low-pressure mercury lamp made of synthetic quartz is used as the lamp. Wavelengths emitted from ultraviolet lamps: 254nm and 185nm
Light energy can break bonds in most organic compounds.

On the other hand, ultraviolet rays with a wavelength of 185 nm generate ozone O3 when absorbed by oxygen in the atmosphere. When ultraviolet light with a wavelength of 254 nm is absorbed by this ozone O3, excited oxygen atoms O* are generated. This excited oxygen atom O*, which has strong oxidizing power, reacts with free radicals and excited molecules of organic compounds generated by light irradiation to generate volatile substances such as CO2 and H2O. This is the principle of ashing, which decomposes and removes organic compounds.

[0012] The present invention devises an ultraviolet irradiation method in order to efficiently remove resist attached to the side and back surfaces of the wafer during wafer heating. The stage, which is heated by a built-in heater, is equipped with a reflector to illuminate the side and back surfaces of the wafer, and a spacer to create a distance from the wafer.

[0013] As a result, the contact surface on the backside of the wafer becomes smaller and contamination on the backside of the wafer is reduced, and by providing a gap between the wafer and the stage having a reflector, the backside of the wafer is irradiated and the excited oxygen atoms O* are irradiated onto the backside of the wafer. This improved the ability to pass around the edges, increasing the efficiency of removing resist adhered to the side and back surfaces, and shortening the ashing time.

[0014]

Embodiment FIGS. 1 and 2 show configuration diagrams of an embodiment of the present invention.

The apparatus is divided vertically into a lamp chamber and a processing chamber by a synthetic quartz glass plate 3, and the lamp chamber mainly has a 185 nm beam.
A low-pressure mercury lamp 1 made of synthetic quartz that emits ultraviolet rays with a wavelength of 254 nm is arranged, and the wafer 4 is irradiated through the synthetic quartz glass window material. Further, a gas supply pipe 2 is arranged in the lamp chamber, with one end connected to an ozone generator and the other end connected to an opening provided in the glass window material, and ozone-containing oxygen gas is blown onto the wafer 4 from the opening. .

A stage 7 having a built-in heater controlled by a temperature control device is installed in the processing chamber. The stage 7 is provided with a reflector 5 and a spacer 6.

FIG. 1 shows the state when the wafer 4 is received, and FIG. 2 shows the stage 7 raised and the spacer 6 placed on the wafer 4.
is in a state of support. The gas is exhausted from the exhaust pipe 8.

Using the ashing device according to the present invention,
The results of a survey of wafer temperature and ashing are shown.

Resist Positive photoresist 1.0
μNPRΛ18SHI Wafer temperature 230℃ Wafer 6 inch Silicon wafer lamp Mainly 185nm and 245n
Low-pressure mercury lamp that emits ultraviolet rays of m. Ozone gas flow rate: 10 liters/min Stage spacer variable irradiation time from 0 to 4 mm
FIG. 3 shows the temperature relationship between the stage heating temperature (temperature control instruction value) which is constant for one minute and the wafer upper surface temperature (center position). This temperature difference gradually increases depending on the interval. When the spacing is 1.0 mm, the temperature is small at about 12°C, but when the spacing is 2.0 mm, it gradually increases to about 25°C, and the heating efficiency deteriorates. The result of resist ashing is wafer temperature 2
At 30 °C, the wafer surface is completely irradiated with 1 minute of irradiation.
．． 0 μm of resist could be removed. The resist that went around to the side and back surfaces of the wafer was removed in about 1.5 minutes when the spacer was 1 mm, but some remained even after 2.0 minutes when the spacer was not used. Therefore, in this example, the distance between the back surface of the wafer and the surface of the reflector is 0.1 to 1.
Approximately 0 mm is preferable.

[0020]

As described above, according to the present invention, by providing a reflector plate and a spacer on a stage equipped with a heating means in a dry ashing apparatus using ultraviolet rays and ozone gas, contamination on the back side of the wafer can be reduced, and contamination on the back side of the wafer can be improved. The resist could be removed efficiently and in a short time.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram for explaining one embodiment of the apparatus of the present invention, showing a state when the stage is lowered.

FIG. 2 is a diagram showing a state in which the stage is raised in the apparatus shown in FIG. 1;

FIG. 3 is a diagram showing the temperature difference between the wafer surface and the stage according to the apparatus of the present invention.

[Explanation of symbols]

1 Lamp 2 Gas supply pipe 3. Light transmitting plate 4 Wafer 5 Reflector plate 6 Spacer 7 Stage 8 Gas exhaust pipe

Claims (1)

[Claims] 1. An ashing device for ashing a polymer film on a wafer or a glass substrate by irradiating ultraviolet rays and supplying a gas containing ozone, wherein a stage is provided with a heating means for raising the temperature of the substrate to be processed. An ashing device characterized by further comprising a reflector for irradiating the back side of the substrate and a spacer for forming a constant interval between the back side of the substrate and the front surface of the reflector.