JP2003163207A - Removing treatment method for remaining photo-resist - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method using discharge plasma capable of realizing a stable discharge state under an atmospheric condition and being treated in a simple device and a small amount of a treatment gas in removing treatment of a remaining photo-resist in a semiconductor manufacturing process. <P>SOLUTION: In the removing treatment method of the remaining photo-resist in the semiconductor manufacturing process, at least one opposite face of a pair of opposite electrodes is covered with a solid dielectric under a pressure in the neighborhood of an atmospheric pressure, and glow discharge plasma obtained by introducing the treatment gas containing 1-50 vol.% of oxygen and applying an electric field between the pair of the electrodes is brought into contact with an object to be treated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing residual photoresist, and more particularly to a method for removing residual photoresist in a semiconductor manufacturing process by atmospheric pressure plasma processing.

[0002]

2. Description of the Related Art Conventionally, in a resist removing process in a semiconductor manufacturing process, a kind of ash is chemically ashed into a resist film which is an organic substance by using active oxygen molecules or ozone molecules generated by using discharge or ultraviolet rays. Ashing treatment, which is a method of removing by utilizing the combustion phenomenon, is performed, but since low-pressure treatment is required, a vacuum chamber, a vacuum exhaust device, etc. must be installed, and the process is performed in a batch system. It took time, and the surface treatment device was expensive. Further, when a large-area substrate is processed by this method, a large-capacity vacuum container and a large-output vacuum evacuation device are required, so that the surface processing device becomes more expensive. Further, conventionally, as the ashing treatment by the plasma treatment, there is a method using atmospheric pressure plasma using helium, as proposed in, for example, Japanese Patent Laid-Open No. 7-99182, but helium gas is used in the natural world. There is a problem that the amount of existence is extremely small and it is expensive and the running cost is heavy.

[0003]

In view of the above problems, the present invention can realize a stable discharge state under atmospheric pressure conditions in a removal process of residual photoresist in a semiconductor manufacturing process, and a simple device. It is also an object of the present invention to provide a treatment method capable of removing treatment using discharge plasma that can be treated with a small amount of treatment gas.

[0004]

As a result of intensive studies to solve the above-mentioned problems, the present inventor has specified a processing gas in a discharge plasma processing method capable of realizing a stable discharge state under atmospheric pressure conditions. The inventors have found that by using a gas containing a proportion of oxygen, the residual photoresist can be efficiently removed, and the present invention has been completed.

That is, according to the first aspect of the present invention, at least one opposing surface of a pair of opposing electrodes is covered with a solid dielectric under a pressure in the vicinity of atmospheric pressure, and 1 to 1 is provided between the pair of electrodes.
A method for removing residual photoresist in a semiconductor manufacturing process, characterized in that glow discharge plasma obtained by introducing a processing gas containing 50% by volume of oxygen and applying an electric field is brought into contact with an object to be processed. .

A second invention of the present invention is the method for removing residual photoresist according to the first invention, wherein the oxygen-containing concentration of the processing gas is 1 to 10% by volume. is there.

Further, a third invention of the present invention is the residual photoresist removing process according to the first or second invention, wherein the processing gas is nitrogen or a mixed gas of argon and oxygen. Is the way.

A fourth aspect of the present invention relates to a method of bringing glow discharge plasma into contact with an object to be processed, in which the plasma generated between a pair of electrodes is applied to the object to be processed outside the discharge space of the electrodes. It is the method of spraying and processing, and is the removal processing method of the residual photoresist in any one of the 1st-3rd inventions characterized by the above-mentioned.

Further, in a fifth aspect of the present invention, the distance from the plasma outlet of the electrode to the object to be treated is 0.5 to 10 mm.
The method for removing residual photoresist according to the fourth invention is characterized in that

The sixth aspect of the present invention is characterized in that the flow velocity of the processing gas is 1 to 20 m / sec.
5 is a method for removing residual photoresist according to any one of the inventions to 5.

The seventh invention of the present invention is characterized in that the temperature of the object to be processed is 15 to 180 ° C.
The method for removing residual photoresist according to any one of the inventions.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, under a pressure near atmospheric pressure,
An apparatus for treating an object to be treated by applying an electric field between a pair of opposing electrodes in which at least one opposing surface of the opposing electrodes is covered with a solid dielectric and introducing a treatment gas between the electrodes to generate glow discharge plasma. Is a processing method for efficiently removing the residual photoresist on the substrate in the semiconductor manufacturing process by ashing and descum processing with plasma of a processing gas having a low oxygen content.

Examples of the electrodes include those made of simple metals such as copper and aluminum, alloys such as stainless steel and brass, and intermetallic compounds. The shape of the electrodes is not particularly limited, but it is preferable to have a structure in which the distance between the opposing electrodes is constant in order to avoid generation of arc discharge due to electric field concentration. As an electrode structure that satisfies this condition,
For example, parallel plate type, cylinder facing plate type, sphere facing plate type,
Examples include a hyperbolic opposed flat plate type and a coaxial cylindrical type structure.

The distance between the electrodes is determined by the thickness of the solid dielectric,
Although it is appropriately determined in consideration of the magnitude of the applied voltage, the purpose of utilizing plasma, etc., it is preferably 0.5 to 10 mm, more preferably 0.5 to 2.0 mm. If the distance between the electrodes is less than 0.5 mm, abnormal discharge is likely to occur, and if it exceeds 10 mm, the discharge is less likely to occur.

Further, in the electrode for generating plasma, the facing surface of at least one of the pair of electrodes is covered with a solid dielectric, and the electrode covered with the solid dielectric is in close contact with and in contact with the electrode. It is necessary to completely cover the opposing surface of. If there is a portion where the electrodes directly face each other without being covered with the solid dielectric, arc discharge easily occurs from there.

The solid dielectric may have a sheet shape or a film shape, and preferably has a thickness of 0.01 to 4 mm. If it is too thick, a high voltage may be required to generate discharge plasma, and if it is too thin, dielectric breakdown may occur when a voltage is applied and arc discharge may occur.

Examples of the material of the solid dielectric include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass, metal oxides such as silicon dioxide, aluminum oxide, zirconium dioxide and titanium dioxide, and double oxidation such as barium titanate. Things etc. are mentioned.

In particular, the relative dielectric constant under the environment of 25 ° C. is 1
If a solid dielectric material of 0 or more is used, a high density discharge plasma can be generated at a low voltage, and the processing efficiency is improved. The upper limit of the relative permittivity is not particularly limited, but as a practical material, about 18,500 is available and can be used in the present invention. A solid dielectric having a relative dielectric constant of 10 to 100 is particularly preferable. Specific examples of the solid dielectric having a relative dielectric constant of 10 or more include metal oxides such as zirconium dioxide and titanium dioxide, and complex oxides such as barium titanate.

In the present invention, an electric field of high frequency, pulse wave, microwave or the like is applied between the electrodes to generate plasma, but it is preferable to apply the pulse electric field.
In particular, the rise and / or fall time of the electric field is
An electric field of 10 μs or less is preferred. If it exceeds 10 μs, the discharge state easily shifts to an arc and becomes unstable, and it becomes difficult to maintain the high-density plasma state due to the pulsed electric field. Further, the shorter the rise time and the fall time are, the more efficiently the gas is ionized at the time of plasma generation, but it is actually difficult to realize a pulsed electric field having a rise time of less than 40 ns. More preferably 5
It is 0 ns to 5 μs. Note that the rising time referred to here means the time when the voltage (absolute value) continuously increases, and the falling time means the time when the voltage (absolute value) continuously decreases.

The electric field strength of the pulsed electric field is 10 to 10
It is preferably set to 00 kV / cm. If the electric field strength is less than 10 kV / cm, the treatment takes too long, and if it exceeds 1000 kV / cm, arc discharge is likely to occur.

The frequency of the pulsed electric field is 0.5 kHz.
The above is preferable. If it is less than 0.5 kHz, the plasma density is low and the treatment takes too long. The upper limit is not particularly limited, but is commonly used 13.56M
A high frequency band such as Hz or a test-use 500 MHz may be used. Considering the ease of matching with the load and the handling property, the frequency is preferably 500 kHz or less. By applying such a pulsed electric field, the processing speed can be greatly improved.

Further, one pulse duration in the above pulsed electric field is preferably 200 μs or less. If it exceeds 200 μs, arc discharge is likely to occur. Here, one pulse duration is ON, OF
It means the continuous ON time of one pulse in the pulse electric field composed of the repetition of F.

When the discharge plasma processing method of the present invention is used for normal pressure discharge plasma processing for generating glow discharge plasma under a pressure near atmospheric pressure, the effect can be sufficiently exhibited. The apparatus of the present invention is particularly advantageous in the atmospheric pressure discharge plasma treatment because it requires a higher voltage than the treatment under a low pressure.

Under the pressure near the atmospheric pressure is 1.333.
It refers to under a pressure of × 10 ^{4 to} 10.664 × 10 ⁴ Pa. Among them, the pressure adjustment is easy, and the device is simple.
The range of × 10 ^{4 to} 10.397 × 10 ⁴ Pa is preferable.
The time required for the discharge plasma treatment is appropriately determined depending on the magnitude of the applied voltage, the object to be treated, the mixed gas composition, and the like.

Means for bringing the plasma into contact with the object to be treated include, for example, (1) placing the object to be treated in the discharge space of the plasma generated between the opposing electrodes and bringing the plasma into contact with the object to be treated. And (2) there is a method (remote type) in which the plasma generated between the opposing electrodes is brought into contact with the object to be processed arranged outside the discharge space.

A specific method of the above (1) is a method of disposing an object to be processed between parallel plate type electrodes covered with a solid dielectric and bringing it into contact with plasma, which is an upper electrode having a large number of holes. , A method of treating with a shower-like plasma, a method of running a film-like base material in a discharge space, a container-like solid dielectric having an outlet nozzle on one electrode, and plasma from the nozzle on the other electrode. A method of spraying on the object to be processed placed in the above can be cited.

Further, as a specific method of the above (2),
An electrode structure in which an electric field is applied between a pair of opposing electrodes such as a parallel plate type electrode and a coaxial cylindrical type electrode, and plasma generated by introducing a processing gas between the electrodes is blown out from a long nozzle, a cylindrical nozzle, etc. Hereinafter, it may be referred to as a remote source.), And is a preferable method that does not damage the object to be processed by an electric field or the like by a discharge plasma processing method in which the object is disposed outside the discharge space.

A specific example using the above remote source will be described with reference to the drawings. FIG. 1 shows a plasma gas to be processed using a remote source in which an electric field is applied between a pair of opposing electrodes of a coaxial cylindrical electrode, and a processing gas is introduced between the electrodes to blow out generated plasma from a cylindrical nozzle. FIG. 3 is a schematic cross-sectional view of an example of a device for spraying on the surface. Note that the ash and the treated exhaust gas are sucked and removed by a donut-shaped gas suction port provided around the gas outlet nozzle. In FIG. 1, the processing gas is introduced into the cylindrical solid dielectric container 4 from the gas introduction port 5 in the direction of the arrow, and the cylindrical solid dielectric container 4
By applying an electric field between the electrode 2 arranged on the outer side and the inner electrode 3 arranged inside the cylindrical solid dielectric container 4, the gas is blown out from the gas blowout port 6 as plasma. On the other hand, the object to be processed 10 is carried and processed by the conveyor belt 11. The ash and the treated gas generated by the treatment are not removed from the exhaust gas cylinder 7 and reattached to the object to be treated 10 to prevent contamination. The conveyor belt 11 can change the degree of processing by using a belt whose feed speed can be arbitrarily adjusted, and can also be provided with a cooling or heating mechanism. In addition, the remote source may be provided with a nozzle standby mechanism that performs a preliminary discharge after applying a voltage between the electrodes and waits outside the object to be processed until the plasma stabilizes, as necessary. A -Z moving mechanism may be provided to sweep over the object to be processed.

FIG. 2 shows that a plasma gas is generated by using a remote source in which an electric field is applied between a pair of opposed electrodes of parallel plate type electrodes and a processing gas is introduced between the electrodes to blow out the generated plasma from a long nozzle. It is a typical sectional view of an example of a device which sprays on a processed object. The ash and the treated exhaust gas are sucked and removed by the gas suction port provided around the gas outlet nozzle. In FIG. 2, the processing gas is introduced from the gas introduction port 5 in the direction of the arrow into the discharge space 9 formed between the parallel plate electrodes 2 and 3 whose opposite faces are covered with the solid dielectric 4, By applying an electric field between the electrode 2 and the electrode 3, it is blown out from the gas blowout port 6 as plasma. On the other hand, the object to be processed 10 is carried and processed by the conveyor belt 11. The ash and the treated gas generated by the treatment are removed from the exhaust gas cylinder 7 provided outside the electrode and are not reattached to the object to be treated 10 and contaminated. The conveyor belt 11 can change the degree of processing by using a belt whose feed speed can be arbitrarily adjusted, and can also be provided with a cooling or heating mechanism. In addition, the remote source may be provided with a nozzle standby mechanism that performs a preliminary discharge after applying a voltage between the electrodes and waits outside the object to be processed until the plasma stabilizes, as necessary. A -Z moving mechanism may be provided to sweep on the substrate to be treated.

From the above characteristics, the treatment method of the present invention is an ashing treatment for organic contaminants such as removal of residual photoresist existing on the surface of the object to be treated of the semiconductor element, a silicon wafer substrate, and a glass substrate. By using it for the descum treatment of the photoresist residue, the surface treatment can be performed very effectively. Further, it can be used for dry etching, improvement of adhesion of organic film, reduction of metal oxide, surface modification and the like.

The processing gas in the residual photoresist removing process of the present invention is a gas containing 1 to 50% by volume of oxygen, and preferably a gas containing 1 to 10% by volume of oxygen. The gas containing oxygen may be an inert gas, but nitrogen or argon is preferable. If the oxygen concentration is less than 1% by volume, the treatment capacity will decrease, and if it exceeds 50% by volume, the treatment effect will not change.

Conventionally, the treatment in the presence of helium has been carried out under a pressure near atmospheric pressure, but according to the method of applying an electric field under atmospheric pressure of the present invention, compared with helium. Stable treatment in inexpensive argon or nitrogen gas is possible, and high density plasma can be generated even when the oxygen content is particularly small.

The flow velocity of the processing gas introduced into the remote source is preferably 1 to 20 m / sec, more preferably 5 to 10 m / sec. Flow rate of processing gas is 1m / s
If it is less than ec, the treatment effect is small, and if it exceeds 20 m / sec, the effect is not changed.

The object to be treated by the residual photoresist in the present invention is a liquid crystal display substrate, a photomask, a glass substrate on which wiring is drawn with photoresist, or a silicon wafer substrate on which wiring is drawn with photoresist. And so on. The processing method of the present invention is
It is very effective for scum removal processing and ashing processing on these substrates.

In the scum removing process and the ashing process, the temperature of the object is preferably 15 to 180.
The treatment capacity can be improved by heating to 90 ° C, more preferably 90 to 150 ° C. If the temperature of the object to be treated is lower than 15 ° C, the effect is small, and if it exceeds 180 ° C, the resist is deteriorated and becomes defective.

The method of heating the object to be processed is not particularly limited as long as it can uniformly and quickly heat the object to be processed, but a sheet heater or the like can be preferably used.

In the atmospheric pressure discharge using the pulsed electric field of the present invention, it is possible to cause the discharge directly to the atmospheric pressure between the electrodes without depending on the gas species at all, and to simplify the electrode structure and discharge. It is possible to realize high-speed processing with the atmospheric pressure plasma device and the processing method according to the procedure. Further, processing parameters such as cleaning rate can be adjusted by parameters such as pulse frequency, voltage, and electrode interval.

[0038]

EXAMPLES The present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 A descum treatment was carried out using the apparatus shown in FIG. It has a water cooling function inside, and the surface is coated with alumina to a thickness of 0.5 mm, 500 mm x 50 mm x thickness 40
mm parallel plate electrode made of SUS304, 0.8m
A remote source installed at intervals of m was used. As the object to be processed, a positive resist was formed on the surface 37
A 0 mm × 470 mm × 8 mm thick Cr-coated glass base material was used, and a position of 5 mm (base material-electrode distance) immediately below the plasma outlet of the remote source was conveyed at a transport speed of 100 m.
It was moved at m / min. As the processing gas, N ₂ / O ₂ =
Using a mixed gas of 98/2 (volume%), a rise time of 5 μs, a voltage of 16 kV _PP , and a frequency of 50 kHz between the electrodes.
The pulsed electric field was applied to perform the descum treatment. As a result, the descum treatment was uniformly performed on the entire surface of the substrate, and the scum width was reduced by 80% by the atmospheric pressure plasma treatment, which was effective.

Example 2 An ashing process was performed using the apparatus shown in FIG. It has a water cooling function inside, and the surface is coated with alumina to a thickness of 1.0 mm, 250 mm x 30 mm x thickness 2
Using 0 mm SUS304 parallel plate electrodes, 2.0
A remote source installed with a space of mm was used.
As the object to be processed, a 200 mmφ silicon wafer having a 200 nm positive resist formed on the surface was used, and 3 mm directly below the plasma outlet of the remote source (base material-
The position of (distance between electrodes) was moved at a transportation speed of 50 mm / min. As the processing gas, a mixed gas of N ₂ / O ₂ = 90/10 (volume%) was used, and the rising time was 5 μm between the electrodes.
Then, an ashing process was performed by applying a pulsed electric field of s, a voltage of 20 kV _PP and a frequency of 35 kHz. As a result, the ashing treatment was uniformly performed on the entire surface of the wafer, and the photoresist remaining rate was 4%. The photoresist residual rate is a value calculated by the following formula. Photoresist residual rate (%) = remaining film thickness / initial film thickness

Examples 3 to 4 Wafers were ashed in the same manner as in Example 2 except that the mixing ratio of N ₂ and O _{2 in} the processing gas was changed.
The results are shown in Table 1.

Comparative Example 1 A wafer was ashed in the same manner as in Example 2 except that 100% N ₂ gas was used as the processing gas. The results are shown in Table 1.

[0043]

[Table 1]

[0044]

According to the present invention, since residual photoresist removal processing such as ashing processing and descum processing used in the semiconductor manufacturing process can be processed under normal pressure, it can be processed with high density plasma, and even for large samples. It can respond and can perform continuous processing. Therefore, it is a processing method with very good productivity. Furthermore, the processing can be inlined and speeded up. This makes it possible to shorten the processing time and reduce the cost. Especially, in the remote source type processing device, by scanning the plasma processing unit,
Large-sized substrate ashing, local partial ashing,
Since it is possible to deal with complicated shapes, etc., it is possible to develop into various applications that were impossible or difficult in the past.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a discharge plasma processing method of the present invention.

FIG. 2 is a diagram showing another example of the discharge plasma processing method of the present invention.

[Explanation of symbols]

1 power supply (high voltage pulse power supply) A few electrodes 4 Solid dielectric 5 gas inlet 6 gas outlet 9 discharge space 7 Exhaust gas collection cylinder 9 discharge space 10 Processing object 11 Conveyor belt

Claims (7)

[Claims] 1. A process gas containing oxygen in an amount of 1 to 50% by volume is coated between at least one of opposing electrodes of a pair of opposing electrodes with a solid dielectric under a pressure near atmospheric pressure. A method for removing residual photoresist in a semiconductor manufacturing process, characterized in that glow discharge plasma obtained by introducing and applying an electric field is brought into contact with an object to be processed. 2. The oxygen-containing concentration of the processing gas is 1 to 10
The residual photoresist removal treatment method according to claim 1, wherein the residual photoresist is in volume%. 3. The method for removing residual photoresist according to claim 1, wherein the processing gas is nitrogen or a mixed gas of argon and oxygen. 4. The method of bringing glow discharge plasma into contact with an object to be processed is a method in which plasma generated between a pair of electrodes is sprayed onto an object to be processed arranged outside the discharge space of the electrodes. The method for removing residual photoresist according to claim 1, wherein the residual photoresist is removed. 5. The method for removing residual photoresist according to claim 4, wherein the distance from the plasma outlet of the electrode to the object to be processed is 0.5 to 10 mm. 6. The method for removing residual photoresist according to claim 1, wherein the flow rate of the processing gas is 1 to 20 m / sec. 7. The method for removing residual photoresist according to claim 1, wherein the temperature of the object to be processed is 15 to 180 ° C.