JP2001015472A - Method and device for projecting ultraviolet ray - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly efficiently remove organic matters from an object to be treated by setting up the object in a space isolated from the outside air, and projecting ultraviolet rays having a specific wavelength or shorter upon the surface to be treated of the object while the oxygen concentration in the space is controlled within a specific range of rate. SOLUTION: On an elevating/lowering table 18 in a treatment chamber 15, a substrate 19 to be treated for cleaning up organic matters is placed. Then the distance between the substrate 19 and a lamp house 12 is adjusted to a prescribed value by elevating the table 18 by means of an elevating/lowering device 17. Successively, the oxygen concentration in the chamber 15 is adjusted to 1-10% and, when the concentration reaches 1-10%, organic matters are cleaned up by projecting vacuum ultraviolet rays emitted from a xenon excimer lamp 11 and having a wavelength of <=175 nm upon the substrate 19 for a prescribed period of time. Therefore, the organic matters can be removed highly efficiently by only using the ultraviolet rays.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for irradiating a processing surface of an object to be processed such as a semiconductor substrate or a liquid crystal display substrate with ultraviolet light to clean or modify organic substances attached to the surface. The present invention relates to an ultraviolet light irradiation method and apparatus.

[0002]

2. Description of the Related Art In a process of manufacturing an integrated circuit or a liquid crystal display, these substrates are repeatedly washed, and occupy a lot of time in the manufacturing process. In particular,
2. Description of the Related Art In a manufacturing process of an integrated circuit in which further miniaturization is advanced, an allowable level of contamination on a substrate surface is becoming increasingly severe. There are various types of this type of substrate surface contamination. For example, in an integrated circuit manufacturing process, organic substances, particles (fine particles such as dust), metal impurities, and natural oxide films (SiO ₂ ) are to be cleaned. I have.

At present, these methods for cleaning substrates include R
The mainstream is a wet (wet) cleaning method performed using a chemical solution generally called CA cleaning. In this method, a large number of chemicals are used to remove various contaminants. That is, in the wet cleaning method, organic substances are removed with sulfuric acid / hydrogen peroxide solution, particles (fine particles) are removed with ammonia / hydrogen peroxide solution, metal impurities are removed with hydrochloric acid / hydrogen peroxide solution, and a natural hydrofluoric acid solution is used. The oxide film is removed, and as a final step, rinsing is performed with ultrapure water, and the substrate cleaning is completed through these steps.

As described above, wet cleaning uses a large amount of various chemicals corresponding to each contamination, and is repeatedly performed in the manufacturing process, so that the amount of chemicals used is enormous. As the diameter of semiconductor substrates is further increased today, it is expected that the amount of chemicals used for wet cleaning will further increase in the future. In wet cleaning, such a large number of chemicals are used, so enormous costs are required including the treatment of chemicals after use, and from the viewpoint of environmental conservation, cleaning without using such chemicals is desired. ing.

[0005] From such a background, in recent years, a dry (dry) cleaning method has attracted attention as an alternative to the wet cleaning method. The dry cleaning method has the advantages that contamination of fine grooves and holes in the integrated pattern that cannot be removed by conventional wet cleaning can be removed, and that once removed contaminants can be prevented from reattaching. In the dry cleaning method, in order to cope with the various types of contamination, for example, removal of metal impurities by ultraviolet-excited chlorine gas, removal of a natural oxide film by ultraviolet-excited fluorine gas, removal of organic substances by combined use of ultraviolet irradiation and ozone gas, etc. The elemental technologies in are being studied.

The removal of organic substances in the dry cleaning method is as follows.
A method using both ultraviolet irradiation and ozone gas is known. In this method, the organic molecule bonds on the substrate surface are broken by using the radiation light from a low-pressure mercury lamp, and the cut molecules are oxidized and scattered and removed by ozone gas. This process is described below. Since the radiation of low-pressure mercury lamps mainly has wavelengths of 254 nm and 186 nm, "Basics and Applications of Ozone" (Hidetoshi Sugimitsu, Korin, P2
5, published in 1996).
The 42 nm light separates oxygen O ₂ , generates oxygen atoms, and recombines with the surrounding oxygen molecules to generate ozone O ₃ . That is,

O ₂ + hν (λ = 175-254 nm) →
O ( ³ P) + O ( ³ P) O ( ³ P) + O ₂ → O ₃

[0008] Ozone has a peak at a wavelength of about 254 nm and 2
It has an absorption band at 20 to 300 nm. Therefore, light having a wavelength of 254 nm emitted from low-pressure mercury is absorbed by the generated ozone and exhibits the following reaction.

O ₃ + hν (λ = 310 nm) → O ( ¹ D) + O ₂

The excited state oxygen atom O ( ¹
D), the oxidizing power of ozone O ₃ , and the effect of the breaking of the organic bond by photon energy at a wavelength of 186 nm result in the removal of the organic substance from the substrate surface. According to this principle, it is desirable to increase the ozone concentration in the atmosphere as much as possible in order to enhance the cleaning effect of the substrate.
However, the radiation of the low-pressure mercury lamp has a wavelength of 254n.
m is main, and the light intensity at a wavelength of 186 nm is small. For this reason, even if the lamp light is irradiated to the atmosphere, the amount of ozone generated is not sufficient. In practice, an ozone generator (also referred to as an ozone generator) is installed outside, and ozone gas is introduced from here. That is being done.

[0011]

However, in semiconductor substrates for integrated circuits that require extremely high cleanliness, organic matter contamination is worse than before cleaning because of the small amount of contaminants generated from the ozone generator. It is said that it is difficult to adapt to an actual manufacturing process.

Accordingly, an object of the present invention is to provide a method and an apparatus for irradiating an ultraviolet light capable of removing organic matter with only an ultraviolet light with high efficiency without requiring an ozone generator or the like.

[0013]

According to the present invention, there is provided an ultraviolet light irradiation method for irradiating a surface to be processed of an object to be processed with ultraviolet light to clean or modify the surface. The method includes the following steps. That is, the present invention is a step of arranging the object to be treated in a space shielded from outside air,
The method includes a step of controlling the oxygen concentration in the space to be 1% or more and less than 10%, and a step of irradiating ultraviolet light having a wavelength of 175 nm or less to the surface of the object to be processed.

Here, as the light source for irradiating the ultraviolet light having a wavelength of 175 nm or less, for example, a dielectric barrier discharge lamp filled with argon (wavelength 126 nm, hereinafter referred to as an argon excimer lamp), a dielectric barrier filled with krypton, etc. Either a discharge lamp (wavelength: 146 nm, hereinafter, referred to as a krypton excimer lamp) or a dielectric barrier discharge lamp containing xenon (wavelength, 172 nm, hereinafter, referred to as a xenon excimer lamp) can be used.

As shown in the above-mentioned "Basics and Applications of Ozone", oxygen has a large absorption in light having a wavelength of 130 to 175 nm, and oxygen O ₂ which has absorbed light in this range immediately becomes an oxygen atom O in a ground state. ( ³ P), excited oxygen atom O ( ¹
D). That is,

O ₂ + hν (130-175 nm) → O ( ¹
D) + O ( ³ P)

The excited oxygen atom O ( ¹ D) generated by the above reaction has a stronger oxidizing power than ozone O ₃ . However, as described above, when a conventional low-pressure mercury lamp is used, the generation of excited oxygen atoms is a secondary reaction according to the reaction formula, and ozone is mainly used for oxidizing organic substances on the surface of the processing object. And the effect of the excited oxygen atom is only used secondarily. On the other hand, in the method according to the present invention utilizing light of a wavelength 130～175Nm, excited oxygen atoms from the oxygen molecule O ₂ having a direct strong oxidizing power O ⁽¹ D) is generated, ozone, oxidation The force is not so high, and is generated by the recombination of the ground state oxygen atom O ( ³ P) and the oxygen molecule O ₂ .

Next, a comparison will be made from the viewpoint of breaking the organic bond on the substrate surface by light. The photon energy of light can be obtained by the following equation.

[0019]

(Equation 1) Here, Planck's constant h = 4.14 × 10 ⁻¹⁵ [eV /
s], and the speed of light in vacuum c = 3 × 10 ⁸ [m / s].

From this equation, the emission wavelength of the low-pressure mercury lamp is 1
The photon energy at 86 nm is 6.7 [eV]. In contrast, the argon excimer lamp is 9.9 [e]
V], the krypton excimer lamp has a photon energy of 8.5 [eV], and the xenon excimer lamp has a photon energy of 7.2 [eV]. Is evident.

The inventor has further found that it is important to appropriately control the oxygen concentration in the atmosphere in which the object is placed in order to more efficiently clean and modify the object. I found it.

The vacuum by the use of ultraviolet light, oxygen molecules utilized directly excited state oxygen atoms absorption of O ₂ O
Generating a ⁽¹ D) is compared to a method using a low pressure mercury lamp, although good efficiency of cleaning or reforming is as described above, the distance from the light source of the absorption rate of the vacuum ultraviolet light Depends on. That is, the attenuation of light due to absorption is
Generally, it is represented by the following equation.

[0023]

(Equation 2)

Where I is the light intensity at the distance d, I
₀ is the light intensity when the distance is zero, and α is the absorption coefficient. The above equation shows that light decays exponentially with distance d, which indicates that the shorter the distance d, the higher the light intensity. However, it is clear that the distance between the vacuum ultraviolet light and the surface of the object to be processed is limited due to the structure of the apparatus, and therefore, the light can effectively reach the surface to be processed,
In addition, another method for effectively generating excited state oxygen atoms on the surface to be processed is essential.

In view of the above, the present inventor has determined that the most efficient generation of excited state oxygen atoms and the intensity of vacuum ultraviolet light applied to the surface of the object to be processed, It has been found that the oxygen concentration in the space where the object is placed should be controlled to 1% or more and less than 10%, more preferably 3% or more and less than 8%.

In this case, the oxygen concentration can be easily ensured by filling the space with a mixed gas of oxygen and nitrogen. That is, preferably, a mixed gas having an oxygen concentration expressed by oxygen gas flow rate / (oxygen gas flow rate + nitrogen gas flow rate) × 100 of 1 to 10% is introduced into the space where the object to be processed is installed. I do.

From another viewpoint, the inventor examined the intensity of the vacuum ultraviolet light applied to the surface of the object to be processed and a method for efficiently generating excited state oxygen atoms on the surface to be processed. The oxygen concentration in the space is 50% or less, the distance between the vacuum ultraviolet light and the surface of the object to be processed is 5 mm or less,
More preferably, it has been found that it is preferable to keep it at 3 mm or less.

The present invention also relates to an ultraviolet light irradiating apparatus for irradiating a surface to be processed of an object to be processed with ultraviolet light to clean or modify the surface. An ultraviolet light irradiation device according to the present invention includes a housing forming a space shielded from the outside air, and a wavelength of 175 nm.
A dielectric barrier discharge lamp that emits the following ultraviolet light toward the space, and the object to be processed in the space,
Holding means for holding the surface to be treated so as to receive ultraviolet light from the dielectric barrier discharge lamp; and an oxygen concentration in the space of 1% or more and less than 10%, preferably 3% or more and 8%.
Oxygen concentration control means for controlling the oxygen concentration to less than

In this case, the holding means can change the distance between the processing surface of the processing object and the light emitting surface of the dielectric barrier discharge lamp to an arbitrary distance of 5 mm or less.
It is preferable to hold the object.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on one embodiment shown in the drawings. FIG. 1 is a front view showing a schematic configuration of a vacuum ultraviolet light irradiation device according to the present invention. As shown in the figure, the vacuum ultraviolet light irradiation device 10 has a housing 10a having a processing chamber 15 in which a substrate 19 to be cleaned by the device is installed and a mechanism room 16 in which various mechanical components are installed. The housing 10a is mainly made of stainless steel, and is designed to prevent corrosion or the like.

The vacuum ultraviolet light irradiation device 10 has a lamp house 12 provided with a xenon excimer lamp 11 inside a housing 10a. The excimer lamp 11 has a xenon gas sealed inside a double tube made of synthetic quartz glass, and applies a high voltage of 1 to 10 kV from the inside to the outside of the tube to emit a specific wavelength of gas. That can emit light.

The interior of the lamp house 12 is replaced with nitrogen gas having a low light absorption and a purity of 99.9% or more in order to minimize light attenuation due to oxygen in the air. In addition, a reflection mirror 13 is provided in the lamp house 12 in order to effectively use light from the xenon excimer lamp 11. The reflection mirror 13 is made of aluminum, and its inner peripheral surface is polished to increase the reflectance. Further, in order to prevent the reflectance from deteriorating with time, it is preferable to deposit magnesium fluoride or the like on the polished surface.

The vacuum ultraviolet light from the lamp house 12 is radiated to a processing chamber 15 separated by a light extraction window 14 made of synthetic quartz glass having a high light transmittance. In the present embodiment, the xenon excimer lamp 11 capable of emitting light with a wavelength of 172 nm is used as the excimer lamp. Calcium, magnesium fluoride,
Alternatively, it is preferable to use a crystal material such as lithium fluoride from the viewpoint of light transmittance.

The processing chamber 15 is sealed with a gasket and an O-ring, and is designed so that the gas filled in the processing chamber 15 does not leak out of the housing 10a and into the mechanism chamber 16. I have. Therefore, problems such as the influence on the human body due to the generated ozone and the like and the adverse effect on the mechanical components due to the highly oxidizing gas are avoided.

An elevating device 17 is installed in the mechanism room 16, and an elevating table 18 is located in the processing chamber 15. A substrate 19 on which a cleaning or modification process is performed is placed on the elevating table 18. With the lifting device 17
The substrate 19 on the lifting table 18 is the lamp house 1
2 so that the distance between the light extraction window 14 and the surface of the substrate 19 is at least 3 m.
It can be adjusted to m to 5 mm.

The substrate 19 to be cleaned or modified by the present apparatus is mainly a semiconductor wafer for manufacturing integrated circuits,
It is a compound semiconductor such as Si or GaAs. Semiconductor wafers vary in various states during the manufacturing process (for example, bare wafers, wafers coated with an oxide film or a metal film, etc.), but the apparatus according to the present invention can clean them regardless of the state of the wafers. is there. The present invention can also be used for cleaning a glass substrate for a liquid crystal display.

In the present invention, the inside of the processing chamber 15 in which the substrate 19 is installed is controlled to a predetermined oxygen concentration when the substrate 19 is cleaned or modified. In the present embodiment, the oxygen concentration in the processing chamber 15 is controlled by changing the flow rate ratio of a mixed gas of oxygen gas and nitrogen gas. The flow ratio of these gases is such that the oxygen concentration is 1
% To less than 10%, more preferably 3% to less than 8%. The details will be described later.
In this case, it is preferable to use a high-purity oxygen gas and a room gas having a purity of 99.9% or more.

That is, the oxygen gas and the nitrogen gas are introduced into the mass flow controllers 20 and 21 from a supply source such as a cylinder (not shown), and the flow rates are controlled here. The oxygen gas and the nitrogen gas whose flow rates are controlled by the respective mass flow controllers 20 and 21 are collected by the collecting manifold 22.
And introduced into the processing chamber 15 through the flow pipe 23. The flow pipe 23 is designed to uniformly supply the gas mixed in the collecting manifold 22 into the processing chamber 15. The specific configuration of the flow pipe 23 will be described later.

The vacuum ultraviolet light irradiation device 10 further includes an ozone decomposition catalyst 24 and a vacuum pump 25. The ozone decomposition catalyst 24 decomposes the ozone gas generated in the processing chamber 15 by the irradiation of the vacuum gas with the mixed gas. As the ozone decomposition catalyst 24, for example, Act Catalis manufactured by Kobe Steel, Ltd. can be used. Vacuum pump 2
Reference numeral 5 is used for forcibly exhausting the ozone gas in the processing chamber 15 after the vacuum ultraviolet light irradiation processing. By driving the vacuum pump 25, the ozone gas in the processing chamber 15 is sucked into the ozone decomposition catalyst 24, decomposed there, and then exhausted out of the housing. Note that excited state oxygen atoms generated in the cleaning and reforming treatments have a very short life, and therefore are not discharged out of the housing and are safe.

FIG. 2 shows an embodiment of a flow pipe 23 used for introducing the mixed gas into the processing chamber 15, wherein FIG. 2A is a front view thereof, and FIG. It is the side view. In these figures, the substrate 19 is also shown, and the relative arrangement of the flow pipe 23 with respect to the substrate 19 is clarified. In the present embodiment, the flow pipe 23 is formed by forming exhaust holes 24a at predetermined intervals on the side surface side along the longitudinal direction of the cylindrical pipe. The mixed gas from the collecting manifold 22 is guided into the pipe from gas inlets 26 provided at both ends thereof, and is blown into the processing chamber 15 from each exhaust hole 24a. As a result, the mixed gas can be uniformly supplied to the surface of the substrate 19, and the efficiency of gas replacement in the processing chamber 15 is improved.
In one example, a flow pipe 23 was used in which a stainless steel seamless pipe having a diameter of 5 mm and exhaust holes 24 a having a diameter of 1 mm were opened at intervals of 10 mm. However, those skilled in the art will understand that the flow pipes that can be employed in the present invention are not limited to those having the above-described structure.
For example, instead of the large number of exhaust holes 24a, a slit may be formed along the longitudinal direction of the pipe to supply a mixed gas from the slit, or another existing mixed gas supply method may be used. May be used.

Next, a method of cleaning the substrate 19 with the organic substance using the vacuum ultraviolet light irradiation apparatus 10 will be described.
In the description, FIG. 3 will be referred to together with FIG. FIG.
It is a flowchart which shows each procedure of the ultraviolet light irradiation method which concerns on this invention. In the first step, a substrate 19 to be subjected to organic cleaning is set on the elevating table 18 in the processing chamber 15 (301). When installing the substrate 19, the substrate 19 can be carried into the processing chamber 15 and transferred to the elevating table 18 by using a handler or other transfer means (not shown). After the substrate 19 is loaded, the processing chamber 15 is sealed from the outside. Activating the lifting device 17 and moving the lifting table 18
And the distance WD between the substrate 19 and the lamp house 12 is increased.
Is adjusted to be a predetermined distance (302). In a preferred embodiment, the distance WD is adjusted to 5 mm or less, more preferably 3 mm or less.

Next, the oxygen concentration in the processing chamber 15 is adjusted to a predetermined value (303). That is, oxygen gas and nitrogen gas are introduced into the mass flow controllers 20 and 21, and the flow rates thereof are controlled here. The oxygen gas and the nitrogen gas whose flow rates have been controlled are mixed in the collecting manifold 22, and introduced into the processing chamber 15 through the flow pipe 23. In a preferred embodiment, the oxygen concentration in the processing chamber 15 is 1
% To less than 10%, more preferably 3% to less than 8%. When the oxygen concentration in the processing chamber reaches a predetermined value, the substrate 19 is irradiated with vacuum ultraviolet light for a predetermined time by the xenon excimer lamp 11, and the organic substance is washed (304).

As described above, the ultraviolet light having a wavelength of 172 nm emitted from the xenon excimer lamp emits light from the processing chamber 15.
The oxygen O ₂ in the inside is dissociated into an oxygen atom O ( ³ P) in a ground state and an oxygen atom O ( ¹ D) in an excited state. The excited oxygen atoms O ( ¹ D) generated here have stronger oxidizing power than ozone O ₃ .
In addition, ozone O ₃ is secondarily generated by the recombination of the ground state oxygen atom O ( ³ P) and the oxygen molecule O ₂ , and the generated ozone O ₃ is also dissociated by the vacuum ultraviolet light to generate excited oxygen. Generate the atom O ( ¹ D). Furthermore, the wavelength 172n
The photon energy of light at m is about 7.2 eV, which is greater than the binding energy of many organics. Therefore, the chemical bond of the organic compound is easily broken, and the generated active oxygen species reacts with the organic compound to generate volatile oxides such as CO ₂ and H ₂ O, which are volatilized and removed.

After a lapse of a predetermined time, the irradiation of the vacuum ultraviolet light by the xenon excimer lamp 11 is terminated, and the ozone gas in the processing chamber 15 is decomposed and removed (305). That is, ozone in the processing chamber 15 is sucked by the vacuum pump 25 and introduced into the ozone decomposition catalyst 24, where the ozone is decomposed,
Exhaust outside the device. Through the above steps, the substrate 19 is subjected to a cleaning process, and is delivered to the next processing step.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The inventor studied the oxygen concentration in the processing chamber and the distance between the semiconductor wafer and the lamp house (hereinafter referred to as WD) when the semiconductor wafer was washed with an organic substance using the vacuum ultraviolet light irradiation apparatus 10. . As a result, the oxygen concentration in the processing chamber is increased from 1% to less than 10%, more preferably 3%.
It has been found that a high cleaning effect can be obtained by controlling the amount to be less than 8%. Similarly, by maintaining the oxygen concentration in the space at 50% or less and maintaining the distance between the vacuum ultraviolet light and the surface of the object to be treated at 5 mm or less, and more preferably at 3 mm or less, a high degree of cleaning effect can be obtained. It was found that it could be obtained. Hereinafter, the results of these studies based on the examples will be described.

In the embodiment, a bare wafer from which a natural oxide film on silicon has been removed is subjected to processing. In addition, a general contact angle measurement method was used as an organic substance evaluation method for evaluating the cleaning degree of the wafer surface. The surface of a bare wafer without a natural oxide film is hydrophobic, and shows a high value when the contact angle is measured. The surface of the wafer is oxidized by irradiation with vacuum ultraviolet light,
An iO ₂ film is formed. This film is hydrophilic and has a small contact angle. Therefore, by measuring the contact angle, it is possible to evaluate the degree of progress of the formation of the SiO ₂ film, that is, the acid north velocity. In the case of this embodiment, since the hydrophobic surface of SiO ₂ is introduced to make it hydrophilic, this treatment can be said to be a surface modification. Will be appreciated by those skilled in the art.

In order to control the oxygen concentration in the processing chamber 15, oxygen gas and nitrogen gas are used.
Mass flow controller 2 so that liter / min
0 and 21 were controlled. The oxygen concentration was determined from the following.

Oxygen concentration = oxygen flow rate / (oxygen flow rate + nitrogen flow rate) × 100

For example, an oxygen flow rate of 0.5 liter / mi
n, when the nitrogen flow rate was 19.5 liter / min, the oxygen concentration was determined to be 2.5% from the above formula. Thus, the total flow rate was set to 20 liter / min, the oxygen concentration was changed from about 0% to about 100%, and the mixed gas was introduced to control the inside of the processing chamber to each oxygen concentration. The volume of the processing chamber is about 10 liters.

At each oxygen concentration, the semiconductor wafer was irradiated with vacuum ultraviolet light from a xenon excimer lamp 11 for cleaning. The irradiation time of the vacuum ultraviolet light on the semiconductor wafer was changed from 0 seconds to about 30 seconds. After washing under each condition, one drop of pure water was dropped on the wafer, and the contact angle was measured. The distance W between the semiconductor wafer surface and the lamp house 12
D adopted three types of 3 mm, 4 mm, and 5 mm.
Under these conditions, the inside of the processing chamber 15 was controlled to each oxygen concentration, and the value of the contact angle with respect to the vacuum ultraviolet light irradiation time was measured.

From the results obtained by the above method, the relationship of the value of the contact angle to the irradiation time of the vacuum ultraviolet light was regressed by the following equation.

[0052]

(Equation 3)

Here, c is a contact angle after irradiation of vacuum ultraviolet light for t seconds, and c0 is a contact angle before irradiation (when not washed). FIG. 4 shows a value obtained for α at each oxygen concentration, where α obtained here is a coefficient representing the cleaning ability. In the figure, W
D indicates the distance between the lamp house and the surface of the semiconductor wafer.

The oxygen concentration in the atmosphere is about 20%. In the figure, near the oxygen concentration of 20%, the cleaning capacity coefficient was 0.34 when the WD was 3 mm, and 0.1 when the WD was 5 mm. On the other hand, the cleaning ability coefficient was very high in the range of oxygen concentration of 1 to 10%, particularly in the range of 5 to 8%, and was 0.47 when WD was 3 mm and 0.18 when WD was 5 mm. When the oxygen concentration is 0%, the light intensity of the vacuum ultraviolet light applied between the wafer surfaces is the highest, but the cleaning ability is close to zero because excited state oxygen atoms are not generated.

As can be seen from the derivation method, the cleaning capacity coefficient represents the time efficiency of cleaning and reforming, and the cleaning capacity coefficient has a linear relationship with the actual cleaning time. is there. From these results, it was clarified that by controlling the oxygen concentration of the substrate installation atmosphere to 1 to 10%, cleaning or reforming can be performed at a speed about 1.4 times faster than the cleaning method in the air.

It has been conventionally known that the smaller the WD, the more exponentially the cleaning performance is improved.
From the results, it was found that, when the oxygen concentration was 50% or less, the WD was improved beyond the index ratio in the range of 5 mm or less.

The embodiments and examples of the present invention have been described with reference to the drawings. However, it is apparent that the present invention is not limited to the above-described embodiments and examples, and that changes, improvements, and the like can be made based on the claims. In the above embodiment, a nitrogen gas is used to create a mixed gas, but an argon gas, a helium gas, or the like can be used in addition to the nitrogen gas.

[0058]

As described above, according to the present invention, the oxygen concentration of the atmosphere in which an object to be processed such as a semiconductor wafer is set to 1
By irradiating vacuum ultraviolet light at a control of 10% to 10%, cleaning and reforming can be performed by a dry method with higher efficiency than irradiation treatment in the atmosphere. According to the method of the present invention, the object to be treated can be washed and reformed with extremely high efficiency, so that an ozone generator is not required and contamination due to the use is avoided.

Also, by controlling the oxygen concentration in the atmosphere to 50% or less and irradiating the object to be treated with vacuum ultraviolet light at a distance of 5 mm or less, the efficiency is extremely high as compared with the irradiation treatment in the atmosphere. Cleaning and reforming can be performed by a dry method. Efficiency of the cleaning and reforming contributes to a reduction in the cost of a semiconductor device or a liquid crystal display incorporating a semiconductor wafer to be processed.

In order to improve the efficiency of the cleaning and the reforming, in the method of the present invention, the oxygen concentration of the atmosphere in which the object is placed is adjusted, and the distance between the light source and the object is adjusted. As it suffices, its realization is extremely easy, and no additional equipment and associated costs and labor are required.

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of a vacuum ultraviolet light irradiation device according to an embodiment of the present invention.

FIGS. 2A and 2B show an embodiment of a flow pipe for introducing a mixed gas into a processing chamber. FIG. 2A is a front view thereof, and FIG. 2B is a side view thereof.

FIG. 3 is a flowchart showing each procedure of an ultraviolet light irradiation method according to the present invention.

FIG. 4 is a graph showing a relationship between a cleaning ability coefficient and an oxygen concentration.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 vacuum ultraviolet light irradiation device 10 a housing 11 xenon excimer lamp 12 lamp house 13 reflection mirror 14 light extraction window 15 processing chamber 16 mechanism room 17 elevating device 18 elevating table 19 substrate 20, 21 mass flow controller 22 assembly manifold 23 flow pipe 24 ozone Decomposition catalyst 24a Exhaust hole 25 Vacuum pump 26 Gas inlet

Claims (11)

[Claims] 1. An ultraviolet light irradiation method for irradiating a surface to be processed of an object to be processed with ultraviolet light for cleaning or modifying the object, wherein the object to be processed is disposed in a space shielded from outside air. And controlling the oxygen concentration in the space to be 1% or more and less than 10%, and irradiating ultraviolet light having a wavelength of 175 nm or less to the surface of the object to be processed. Irradiation method. 2. An ultraviolet light irradiation method for irradiating a surface to be processed of an object to be processed with ultraviolet light for cleaning or modifying the object, wherein the object to be processed is arranged in a space shielded from outside air. Controlling the oxygen concentration in the space to 50% or less, and irradiating ultraviolet light having a wavelength of 175 nm or less to the surface of the object to be processed at a distance of 5 mm or less. UV light irradiation method. 3. An ultraviolet light irradiation method for irradiating a surface to be processed of an object to be processed with ultraviolet light for cleaning or modifying the object, wherein the object to be processed is arranged in a space shielded from outside air. Controlling the oxygen concentration in the space to 1% or more and less than 10%; and irradiating ultraviolet light having a wavelength of 175 nm or less to the surface of the object to be processed at a distance of 5 mm or less; UV irradiation method comprising: 4. In the step of controlling the oxygen concentration,
4. The ultraviolet light irradiation method according to claim 1, wherein the oxygen concentration in the space is controlled to 3% or more and less than 8%. 5. In the step of controlling the oxygen concentration,
A method according to claim 1, wherein the space is controlled to a predetermined oxygen concentration by filling the space with a mixed gas of oxygen and nitrogen.
5. The ultraviolet light irradiation method according to 2, 3 or 4. 6. The ultraviolet light irradiation method according to claim 2, wherein, in the step of irradiating the ultraviolet light, the ultraviolet light is applied to a surface of the object to be processed at a distance of 3 mm or less. . 7. The method of claim 1, wherein the ultraviolet light is generated by a dielectric barrier discharge lamp.
7. The ultraviolet light irradiation method according to 5 or 6. 8. An ultraviolet light irradiation apparatus for irradiating a surface to be processed of an object to be processed with ultraviolet light for cleaning or modifying the same, comprising: a housing forming a space shielded from outside air; A dielectric barrier discharge lamp that emits ultraviolet light having a wavelength of 175 nm or less toward the space; and a processing object in the space, the processing surface of which receives ultraviolet light from the dielectric barrier discharge lamp. An ultraviolet light irradiation device comprising: holding means for holding; and oxygen concentration control means for controlling the oxygen concentration in the space to 1% or more and less than 10%. 9. The ultraviolet light irradiation apparatus according to claim 8, wherein the oxygen concentration control means controls the oxygen concentration in the space to be 3% or more and less than 8%. 10. The ultraviolet device according to claim 8, wherein the oxygen concentration control means controls the inside of the space to a predetermined oxygen concentration by filling the space with a mixed gas of oxygen and nitrogen. Light irradiation device. 11. The holding means holds the work so that the distance between the work surface of the work and the light emitting surface of the dielectric barrier discharge lamp can be changed to an arbitrary distance of 5 mm or less. 11. The ultraviolet light irradiation device according to claim 7, 8, 9, or 10.