JPH04307726A - Ashing apparatus - Google Patents

Abstract

PURPOSE:To provide an ashing apparatus which causes little damage to a wafer and whose ashing rate is fast. CONSTITUTION:A lamp chamber and a substrate treatment chamber are partitioned by a light-transmitting flat plate 4. The following are arranged in the lamp chamber: a low-pressure mercury lamp 1 which is a face light-source shape made by bending a straight tube, which uses a water-cooling system and whose output is high; and a gas supply pipe 3 connected to a gas outflow port installed at the light-transmitting flat plate 4. A stage 6 provided with a heating means used to raise the temperature of a substrate 5 is arranged in the treatment chamber.

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 resist film pattern formed on a wafer or glass substrate by treating it with ultraviolet light and ozone gas.

0002

[Background Art and its Problems] Generally, in the manufacturing process of semiconductor integrated circuits, a photoresist film pattern formed by exposure and development is used as a mask during etching, and is removed from the surface of a semiconductor wafer after the etching process. There is a need. 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 may impact the wafer and the amount of charge may increase. This causes so-called plasma damage, which becomes a problem as circuit patterns become finer.

On the other hand, an ashing method using ultraviolet light has also been known. A wafer having a resist layer is placed in the processing chamber, and ashing processing is performed by irradiating the wafer with a resist layer through a window from an ultraviolet lamp located above the processing chamber, and by introducing ashing gas into the processing chamber. Unlike plasma ashing, this method causes less damage to the wafer, but has the problem that the ashing speed is slow, the processing takes time, and the processing efficiency is low. Conventionally used ultraviolet lamps have a lamp power of 1w per arc length.
The ashing speed was slow due to the low intensity of the ultraviolet light, which was a straight tube or U-tube shaped lamp with a low output of less than cm2. Furthermore, in order to uniformly illuminate a certain area, it was necessary to line up a plurality of lamps, which was economically disadvantageous.

[0006]

[Means for Solving the Problems] The present invention has been made to address the problems of the prior art, and its purpose is to provide high output with less damage to wafers and a fast ashing rate. An object of the present invention is to provide an ashing device using an ultraviolet lamp.

For this purpose, the present invention provides an apparatus for ashing a polymer film on a wafer by irradiating ultraviolet rays and supplying a gas containing ozone, in which a lamp chamber and a wafer processing chamber are separated by a light-transmitting flat plate. The lamp chamber is equipped with a low-pressure mercury lamp that is a surface light source made of a bent straight tube and has a high output using a water-cooling method, and a gas supply pipe connected to a gas outlet provided on a flat plate. An object of the present invention is to provide an ashing apparatus characterized by having a stage equipped with a heating means for heating a wafer. Note that a high-output lamp is defined as a lamp with a lamp power per arc length of 2
Those with a power output of 1 w/cm or more will be referred to as low-output lamps, and those with a power output of 1 w/cm or less will be referred to as low-output lamps.

[0008]

[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 transmission window of synthetic quartz glass, the polymer film on the wafer surface is ashed according to the following principle.

As the lamp, a low-pressure mercury lamp made of synthetic quartz having a lamp output per arc length of 2 W/cm or more is suitable. Wavelength emitted from ultraviolet lamp: 254
Light energy in the nm and 185 nm wavelengths 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. In order to increase the speed of ashing, it is important to increase the ozone concentration and the temperature of the substrate to be processed, as well as to increase the intensity of ultraviolet rays.

[0011] Conventionally, low-pressure mercury lamps have had a relatively low output per arc length of 1 W/cm or less. Generally, when the lamp power is increased in an attempt to increase the output of a low-pressure mercury lamp, there is a problem in that the coldest point of the lamp increases and the radiation efficiency at 185 nm and 254 nm necessary for ashing decreases. In order to maintain radiation efficiency at a high level, the coldest point must be controlled within the range of 40 to 60°C. In the present invention, high output was achieved by attaching an aluminum block to the wall of the discharge tube near the lamp electrode and bringing this block into contact with the radiator of the water cooling board.

[0012] Depending on the size of the substrate to be processed, the discharge section has a shape and system in which the tube is bent to approximate a surface light source so that the surface is subjected to uniform irradiation conditions. As a result, the processing speed of ashing can be increased and the processing can be performed uniformly, and since only one lamp is required, it is also economically advantageous. Also,
The ashing rate can be further increased by heating the wafer on a stage adjusted to a set temperature and blowing ozone gas.

[0013]

Embodiment FIG. 1 shows a configuration diagram of an embodiment of the present invention. The processing chamber is divided into upper and lower parts by synthetic quartz glass plates with opening holes in some parts, and the lower part has a built-in heater that is controlled by a temperature control device and has a mechanism that allows it to rotate at a predetermined speed. A stage 6 is arranged, and a wafer 5 whose surface is coated with resist is placed on the stage 6 and heated by a heater of the stage 6.

[0014] In the upper lamp chamber, a 165 x 165 straight tube with a power per arc length of 4 w/cm was installed.
One high-output low-pressure mercury lamp 1 made of synthetic quartz and having a lamp power of 400 W and a light emitting area of mm2 is arranged, and the wafer 5 is irradiated through a synthetic quartz glass plate 4 serving as a window material. Lamp 1 has an aluminum block attached near the electrodes, and this block is brought into contact with water cooling board 2, achieving a high output lamp power of 4w/cm per arc length.

[0015] Also, one side of the lamp chamber is equipped with an ozone generator 8.
There is a gas supply pipe 3 which is connected to one end and the other end connected to an opening provided in a glass plate of the window material. This structure allows ozone gas to be blown onto the wafer.

To explain the operation of the ashing apparatus shown in FIG. 1, first, a heater built into the stage 6 is controlled by a temperature control device, and the wafer 5 is heated to a temperature of 100 to 300, for example.
A single flat-shaped low-pressure mercury lamp with a high output of 400 W that heats up to a temperature range of 254 nm and 185 nm
The wafer surface is irradiated with high-intensity ultraviolet light of m2.

Oxygen gas containing ozone supplied from the ozone generator 8 is regulated in flow rate, is blown onto the wafer surface from the opening, and is exhausted through the gas exhaust pipe 7 by the exhaust device.

Using the ashing apparatus of the present invention, the ashing rate was investigated under the following conditions. [A condition] Resist Positive photoresist 1.5
μNPRΛ18SHI Wafer temperature
250℃ ozone flow rate 10 liters/min Lamp 165 x 165 mm2 surface shape 400 W lamp power Lamp power per arc length 4 W/cm high output synthetic quartz low pressure mercury lamp Number of lamps 1 lamp Irradiation time 1 minute comparison For this reason, we similarly investigated the ashing rate using a low-output, low-pressure mercury lamp. [Condition B] Lamp: U-tube-shaped 110W lamp Power: Low-output synthetic quartz low-pressure mercury lamp with lamp power of 1W/cm per arc length Number of lamps: 4 Other conditions are the same as Condition A.

Comparing the resist ashing rates, the ashing rate under condition A according to the present invention was approximately twice that under condition B using a low output lamp.

[0020]

As described above, according to the present invention, by using a high-output low-pressure mercury lamp, the ashing rate of the ashing device can be greatly increased. By using lamps, lamp maintenance costs could be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the device of the present invention.

[Explanation of symbols]

1 Lamp 2 Water cooling board 3 Gas supply pipe 4. Light-transparent flat plate 5 Wafer 6 Stage 7 Gas exhaust pipe 8 Ozone generator

Claims (1)

[Claims] 1. An ashing device for ashing a polymer film on a wafer or a glass substrate by ultraviolet irradiation and supply of ozone-containing gas, wherein a lamp chamber and a substrate processing chamber are separated by a light-transmitting flat plate; A low-pressure mercury lamp, which is a surface light source made of a bent straight tube and has a high output using a water-cooling method, and a gas supply pipe connected to a gas outlet provided on a light-transmitting flat plate are arranged. , an ashing apparatus characterized in that a stage equipped with a heating means for raising the temperature of the substrate is arranged in the processing chamber.