JP6681228B2 - Etching apparatus and etching method - Google Patents

Description

  The present invention relates to a substrate etching apparatus and etching method. More specifically, it relates to an etching apparatus and an etching method for etching a substrate such as a wafer using radicals generated by irradiating UV light to excite a reactive gas.

  In the manufacturing process of semiconductor devices, etching of a substrate using plasma is performed. In the etching using plasma, there is a problem that ions generated in plasma damage the substrate. As a technique for avoiding this problem, Patent Document 1 describes a technique for etching silicon using radicals generated by irradiating a reactive gas with UV light.

FIG. 9 is a cross-sectional view showing a schematic configuration of the etching apparatus described in Patent Document 1. A gas inlet 5 for introducing a reactive gas and a vacuum pump 7 for controlling the pressure in the processing chamber 2 are connected to the processing chamber 2 having a space for etching the substrate W. The wafer W is placed on the susceptor 6 for the etching process. A light source 3 is arranged above the processing chamber 2, and a light transmission window 4 for transmitting UV light is arranged on the processing chamber 2 side of the light source 3. A vacuum is maintained in the processing chamber 2 by the vacuum pump 7 during the etching process. When a reactive gas such as CF ₄ gas is introduced into the processing chamber 2 through the gas inlet 5, the light source 3 irradiates the UV light transmitted through the light transmission window 4. The introduced CF ₄ gas is excited by UV light to generate F radicals. That due to the greater energy of the UV light than the binding energy of CF _4, CF ₄ excites, F radicals are generated by dissociating. The silicon of the wafer W is etched by the F radicals generated in the space above the wafer W in the processing chamber 2. At this time, the wafer W is also irradiated with UV light.

JP 2005-268598 A

  In the related art, when the wafer is etched by radicals generated by irradiation with UV light, the wafer is also irradiated with UV light. When the wafer is irradiated with UV light, defects may be induced in the wafer during the manufacturing process of the semiconductor device. As an example, in a CMOS device process, a dummy gate electrode made of a silicon material such as polysilicon is formed in a region to be a gate, and after etching the dummy gate electrode, a high dielectric constant gate insulating film and a low resistance metal film are formed. There is a process. If the wafer is irradiated with UV light when the dummy gate electrode is etched, the UV light penetrates into the silicon or silicon oxide film on the bottom of the dummy gate electrode and the sidewalls of the dummy gate electrode to induce defects. That is, since the energy of UV light is larger than the binding energy between silicon and silicon or the binding energy between silicon and oxygen, these bonds are distorted or broken. As a result, the fixed charge at the interface of the gate oxide film increases and the electrical characteristics deteriorate. When the low dielectric constant film around the dummy gate electrode is irradiated with UV light, the relative dielectric constant increases. If the relative permittivity increases, the inter-wiring capacitance of the device increases, which deteriorates the switching characteristics of the device.

  Therefore, the present invention aims to provide an etching device and an etching method for etching a substrate with radicals generated by irradiating a reactive gas with UV light while preventing UV light from reaching the surface of the substrate. And

In order to achieve the above object, the invention according to claim 1 is arranged such that a processing chamber for processing a substrate, a substrate holding portion for holding a substrate at a bottom portion of the processing chamber, and an upper portion of the processing chamber. A gas introduction part for introducing a reactive gas into the chamber, a UV light source arranged on the top surface of the processing chamber to emit UV light, and a window for transmitting the UV light from the UV light source to the processing chamber. A member, an exhaust port connected to the bottom of the processing chamber for depressurizing the inside of the processing chamber, and a plurality of gas dispersion plates having an opening located between the substrate holding unit and the gas introduction unit, And the positions of the openings that are opened in the respective gas dispersion plates of the plurality of gas dispersion plates are arranged at positions that do not overlap in the vertical direction, and the plurality of gas dispersion plates include a first gas dispersion plate and a first gas dispersion plate. 2 is a gas dispersion plate, and the first gas dispersion plate is There is an opening in a region from the center to a predetermined position, and the predetermined position is within a range of 30% or more and 60% or less of a radius of the first gas distribution plate, and the first gas distribution plate and the first gas distribution plate 2 spacing of the gas distribution plate is an etching apparatus according to claim der Rukoto than 10mm or less 2 mm.

  The invention according to claim 2 is the etching apparatus, wherein the opening diameter of the plurality of gas dispersion plates is 0.02 mm or more and 0.3 mm or less.

The invention according to claim 3 is the etching apparatus, wherein the opening diameter of the second gas dispersion plate is smaller than the opening diameter of the first gas dispersion plate.

The invention according to claim 4 is the etching apparatus, wherein the plurality of gas dispersion plates are made of a ceramic such as aluminum oxide or yttrium oxide.

The invention according to claim 5 is the etching apparatus in which the reactive gas is SF ₆ or NF ₃ .

The invention according to claim 6 is the etching apparatus, wherein the window member is made of quartz or quartz coated with yttrium oxide.

According to a seventh aspect of the present invention, there is provided an etching apparatus in which the substrate holding portion is provided with a heating mechanism for heating the substrate.

Invention according to claim 8, comprising an etching method using the etching apparatus according to any one of claims 1 to 8, wherein the step of placing the substrate on the substrate holder, said processing chamber Depressurizing by exhausting gas from the exhaust port connected to the bottom of the processing chamber; introducing the reactive gas from the gas introducing unit; and irradiating the reactive gas with the UV light from the UV light source. And a step of etching the semiconductor substrate by supplying radicals generated by irradiating the reactive gas with the UV light onto the substrate, the etching method comprising:

  According to the etching apparatus and the etching method of the present invention, radicals are supplied to the substrate while preventing UV light from reaching the substrate. Since the substrate is etched by the radicals, the substrate is not damaged and the relative dielectric constant of the low dielectric constant film is not increased.

It is sectional drawing which shows schematic structure of the etching apparatus which concerns on embodiment. It is the top view which looked at the lamp house concerning an embodiment from the window member side. It is a top view showing a schematic structure of the 1st gas distribution board concerning an embodiment. It is a top view which shows schematic structure of the 2nd gas dispersion plate which concerns on embodiment. It is sectional drawing which expanded the opening area of the 1st gas dispersion plate and 2nd gas dispersion plate which concern on embodiment. It is sectional drawing which shows schematic structure of the etching apparatus which concerns on the modification of embodiment. It is a schematic sectional drawing of a device structure before and after etching. It is a flow chart for explaining the flow of processing of an embodiment. It is a top view which shows schematic structure of the etching apparatus which concerns on a prior art.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments described below.

FIG. 1 is a sectional view of an etching apparatus according to an embodiment of the present invention.
The etching apparatus 1 according to the first embodiment includes a processing chamber 10, a lamp house 12 containing a UV light source 11, a gas introducing unit 16 for introducing a reactive gas into the processing chamber 10, and an inside of the processing chamber 10. And an exhaust port 19 connected to a vacuum pump (not shown) for reducing the pressure.

  The processing chamber 10 has a cylindrical shape. A wafer holder 17 that holds a wafer W is installed at the bottom of the processing chamber 10, and a first gas dispersion plate 14 and a second gas dispersion plate 15 are installed above the wafer holder 17. The first gas dispersion plate 14 and the second gas dispersion plate 15 are located between the gas introduction part 16 and the wafer holder 17, and the space between the window member 13 and the first gas dispersion plate 14. And a space between the first gas dispersion plate 14 and the second gas dispersion plate 15 and a space between the second gas dispersion plate 15 and the wafer holder 17. A heater 18 for heating the wafer W is built in the wafer holder 17.

  A UV light source 11 that emits UV light is installed in the lamp house 12. A window member 13 is provided at the bottom of the lamp house 12. The UV light emitted from the UV light source 11 passes through the window member 13 and is applied to the wafer W in the processing chamber 10.

  FIG. 2 is a plan view of the lamp house 12 viewed from the window member 13 side. The lamp house 12 is surrounded by a housing 12a made of metal such as stainless steel, and only the window member 13 that is a region for irradiating UV light is made of a material such as quartz that transmits UV light. As the UV light source 11, rod-shaped excimer lamps are arranged at equal intervals. When the UV light source 11 emits UV light, the window member 13 uniformly irradiates the wafer W in the processing chamber 10 with the UV light.

  An opening is formed in the upper partition wall of the processing chamber 10, and the gas introducing unit 16 is connected to the opening. The gas introduction unit 16 introduces the reactive gas used for etching into the processing chamber 10 with its flow rate controlled by a flow rate control device (not shown). An opening is formed in the partition wall at two locations on the outer periphery of the bottom of the processing chamber 10, and an exhaust port 19 is connected to the opening. The exhaust port 19 is connected to a vacuum pump (not shown) to reduce the pressure inside the processing chamber 10 to a predetermined degree of vacuum.

In the etching apparatus 1 of this embodiment, the wafer W is transferred by a transfer system (not shown) and placed and held on the wafer holder 17. A vacuum pump (not shown) is operated for etching the wafer W, and the inside of the processing chamber 10 is decompressed from the exhaust port 19 which is connected to the processing chamber 10 for communication. NF ₃ is introduced into the processing chamber 10 as a reactive gas from the gas introduction unit 16 which is connected to the processing chamber 10 for communication. The introduced NF ₃ is irradiated with UV light in the space between the lamp house 12 and the first gas dispersion plate 14.

The UV light source 11 used in the etching apparatus 1 of this embodiment may be any one that emits UV light having a photon energy larger than the binding energy (6.6 eV) of NF ₃ . UV light of greater photon energy than the binding energy of NF ₃ is irradiated to the NF ₃ was introduced into the processing chamber 10 from the gas inlet 16 through the window member 13. Energy of UV light irradiated is NF ₃ to greater than the binding energy of NF ₃ is excited. The excited NF ₃ is dissociated and F radical is generated. A commercially available UV light source 11 that emits UV light having a photon energy larger than the binding energy (6.6 eV) of NF ₃ can be used. For example, a xenon excimer lamp (photon energy 7.2 eV), a krypton excimer lamp (photon energy 8.5 eV), an argon excimer lamp (photon energy 9.8 eV) can be used. In addition to NF ₃ , SF ₆ (binding energy of 3.8 eV) can be used as the reactive gas used. The types of reactive gas used are not limited to these.

  The window member 13 in the etching apparatus 1 of this embodiment needs to be a material that does not absorb the UV light and transmits it well, in order to allow the UV light of the UV light source 11 to pass through the processing chamber 10 without being attenuated. Therefore, the material of the window member 13 is preferably quartz, which hardly absorbs UV light. Alternatively, quartz whose surface is coated with yttrium oxide having high transmittance can be used.

  As shown in FIG. 1, the gas dispersion plate used in the etching apparatus 1 of this embodiment is provided with the first gas dispersion plate 14 and the second gas dispersion plate 15 from the side close to the gas introduction part 16. . The material used for the gas dispersion plate is preferably a ceramic such as aluminum oxide or yttrium oxide in order to prevent a reaction due to F radicals.

  As shown in FIG. 3, the first gas dispersion plate 14 is a circular flat plate and has a plurality of openings in the radial direction from the center. The first gas dispersion plate 14 is for efficiently exciting the reactive gas introduced from the gas introduction unit 16 into the processing chamber 10 in the space between the window member 13 and the first gas dispersion plate 14. Is.

  Therefore, it is necessary to secure a residence time for the reactive gas to be sufficiently excited in the space between the window member 13 and the first gas dispersion plate 14, and for the radicals generated in the space to be the first After passing through the opening of the gas dispersion plate 14 of No. 2, it is necessary to pass through the opening of the second gas dispersion plate 15 and be uniformly supplied onto the wafer W.

  For example, when etching a 300 mm silicon wafer, the diameter of the gas dispersion plate can be 320 mm. The thickness of the gas dispersion plate is 3 mm. However, the diameter of the gas distribution plate may be larger than this, and the thickness may be larger than this.

  As shown in FIG. 3, in the first gas dispersion plate 14, openings 14a having an inner diameter of 0.1 mm are formed in a disk having an outer diameter of 320 mm at 5 mm intervals from the center to a position 50% of the radius in the radial direction. . In FIG. 3, the intervals and the number of openings are outlined.

  The opening of the first gas dispersion plate 14 should be as small as possible because a sufficient residence time for exciting the reactive gas in the space between the window member 13 and the first gas dispersion plate 14 is required. Is desirable. However, an inner diameter of 0.1 mm is preferable due to processing restrictions for manufacturing. If the opening diameter is too large, UV light may not be blocked. As a result of earnest study, the opening diameter is preferably 0.02 mm or more and 0.3 mm or less.

  Further, if the opening of the first gas dispersion plate 14 is formed on the entire surface, the etching uniformity of the wafer W is deteriorated. The flow of the F radicals passing through the opening of the first gas dispersion plate 14 spreads to the outer periphery, so that the etching amount in the outer peripheral region of the wafer W becomes large, which causes a problem in uniformity. It has been found that it is preferable to form the opening from the center of the first gas dispersion plate 14 to the position of 50% of the radius in the radial direction, that is, to the intermediate position of the first gas distribution plate 14. As a result of earnest studies, it is preferable that the area forming the opening is 30% or more and 60% or less of the radius in the radial direction from the center.

  The F radicals that have passed through the openings of the first gas dispersion plate 14 are supplied to the wafer W through the openings of the second gas dispersion plate 15. At this time, UV light also passes through the opening of the first gas dispersion plate 14. Most of the UV light that has passed through the opening of the first gas dispersion plate 14 is shielded by the second gas dispersion plate 15 so that the wafer W is not irradiated with the UV light. Details will be described later.

  As shown in FIG. 4, the second gas dispersion plate 15 has an opening formed on the entire surface. The opening diameter of the second gas dispersion plate 15 is smaller than the opening diameter of the first gas dispersion plate 14, and 0.05 mm is suitable when the opening diameter of the first gas dispersion plate 14 is 0.1 mm. The openings of the second gas dispersion plate 15 are opened over the entire surface with an opening diameter of 0.05 mm and a gap between the openings of 5 mm. In FIG. 4, the spacing and number between the openings are outlined.

  In order to uniformly supply the F radicals that have passed through the openings of the first gas dispersion plate 14 onto the wafer W through the openings of the second gas dispersion plate 15, the first gas dispersion plate 14 and the second gas dispersion plate In the space between the plates 15, it is effective to have the conductance as much as possible and pass through the opening of the second gas dispersion plate 15.

  Further, although the openings of 0.05 mm are arranged at equal intervals in FIG. 4, the density of the openings may be increased in the outer peripheral region. The condition for uniformly supplying the F radicals onto the wafer W also depends on the supply amount of the reactive gas and the degree of pressure reduction in the processing chamber 10. For this reason, the interval and arrangement between the openings of the first gas dispersion plate 14 and the second gas dispersion plate 15 are not limited to the above.

  The positional relationship between the opening of the first gas dispersion plate 14 and the opening of the second gas dispersion plate 15 will be described with reference to FIG. FIG. 5 is an enlarged sectional view of the opening regions of the two gas dispersion plates. The arrow indicates the traveling direction of UV light. FIG. 5a is a comparative example for the present invention.

FIG. 5a shows a case where the positions of the openings of the first gas dispersion plate 14b and the positions of the openings of the second gas dispersion plate 15b overlap in the vertical direction. FIG. 5B shows a case where the positions of the openings of the first gas dispersion plate 14 and the positions of the openings of the second gas dispersion plate 15 of the present invention are formed at positions that do not overlap in the vertical direction.

As shown in FIG. 5a, when the position of the opening of the first gas dispersion plate 14b and the position of the opening of the second gas dispersion plate 15b overlap in the vertical direction, the UV light incident perpendicularly to the opening Obviously, UV light that is obliquely incident easily passes through the opening of the second gas dispersion plate 15b.

  On the other hand, in the case of FIG. 5B in which the positions of the openings of the first gas dispersion plate 14 and the positions of the openings of the second gas dispersion plate 15 are formed so as not to overlap in the vertical direction, the incident light is perpendicular to the openings. It can be seen that both the UV light and the obliquely incident UV light are shielded by the second gas dispersion plate 15. As shown in FIG. 5b, in the present invention, UV light is shielded by the first gas dispersion plate 14 and the second gas dispersion plate 15, so that radicals are prevented from reaching the wafer W while reaching the wafer W. Supplied.

  Here, the distance between the first gas dispersion plate 14 and the second gas dispersion plate 15 is also important. If the distance between the first gas dispersion plate 14 and the second gas dispersion plate 15 is too wide, the UV light passing through the opening of the first gas dispersion plate 14 spreads and is formed at a position where it does not overlap in the vertical direction. The second gas dispersion plate 15 passes through the opening. Therefore, it is desirable that the distance between the first gas dispersion plate 14 and the second gas dispersion plate 15 be as small as possible. However, the F radicals that have passed through the openings of the first gas dispersion plate 14 must spread to the entire surface of the second gas dispersion plate 15 in the space between the first gas dispersion plate 14 and the second gas dispersion plate 15. I have to. Therefore, it has been found that the distance between the first gas dispersion plate 14 and the second gas dispersion plate 15 is preferably 5 mm. In this case, F radicals can pass while blocking UV light. As a result of earnest study, the distance between the first gas dispersion plate 14 and the second gas dispersion plate 15 is preferably 2 mm or more and 10 mm or less.

  The etching apparatus 1 includes a wafer holder 17 having a heater 18 for heating the wafer W. The heater 18 is not limited in its method and may be a commercially available one. It is desirable to heat the wafer W because the reaction rate of silicon etching by F radicals increases as the temperature increases. The heating temperature is preferably 50 ° C to 100 ° C, but is not limited to this.

An etching apparatus according to a modified example of the embodiment will be described. FIG. 6 is a sectional view of an etching apparatus 1A according to a modification of the embodiment of the present invention. This modified example is the same as the modified example except that the gas distribution plate has three plates.

  As shown in FIG. 6, the third gas dispersion plate 20 is arranged further on the wafer W side of the second gas dispersion plate 15. The positions of the openings of the third gas dispersion plate 20 are formed so as not to overlap the positions of the openings of the second gas dispersion plate 15 in the vertical direction. The opening diameter of the third gas distribution plate 20 and the distance between the openings may be the same as the opening diameter of the second gas distribution plate 15 and the distance between the openings.

  By disposing the third gas dispersion plate 20 further on the wafer W side of the second gas dispersion plate 15, the UV light can be shielded more reliably. Since the UV light is shielded by the first gas dispersion plate 14, the second gas dispersion plate 15, and the third gas dispersion plate 20, radicals are supplied to the wafer W while preventing the UV light from reaching the wafer W. It The distance between the third gas dispersion plate 20 and the second gas dispersion plate 15 is preferably 5 mm, which is the same as the distance between the first gas dispersion plate 14 and the second gas dispersion plate 15, and is 2 mm or more and 10 mm or less. Preferably there is.

Next, as the etching of the wafer W by the etching apparatus 1A having the above-described configuration, the etching of the dummy gate electrode in the CMOS device process will be described. FIG. 7 shows a schematic cross-sectional view of the device structure before and after etching the dummy gate electrode.

  FIG. 7a shows a state before etching, in which a low dielectric constant silicon oxide film 72 is formed as an interlayer insulating film on a silicon substrate 71. After patterning the silicon oxide film 72 with a mask (not shown), a dummy gate electrode 73 made of polysilicon is formed. FIG. 7b shows the state after the dummy gate electrode 73 is etched by the F radical.

  The procedure for etching the dummy gate electrode 73 will be described with reference to FIG. FIG. 8 is a flowchart for explaining the processing flow of the embodiment of the present invention.

  The wafer W is transferred by a transfer system (not shown) and placed on the wafer holder 17 (step S1). At this time, the inside of the processing chamber 10 is at atmospheric pressure.

  Next, while the wafer W is held by the wafer holder 17, a vacuum pump (not shown) is operated to reduce the pressure inside the processing chamber 10 through the exhaust port 19 (step S2). The degree of pressure reduction is preferably about 6.67 Pa, and the allowable range is 1.33 to 40.02 Pa.

After the pressure inside the processing chamber 10 is reduced, NF ₃ as a reactive gas is supplied from the gas introduction unit 16 into the space between the window member 13 and the first gas dispersion plate 14 of the processing chamber 10 (step S3). ). The supply amount of NF ₃ is preferably 50 sccm. The allowable range is 30 sccm to 100 sccm.

The NF ₃ is supplied into the processing chamber 10 from the gas introduction unit 16 and at the same time, the UV light source 11 is turned on and the UV light transmitted through the window member 13 is applied to the NF ₃ (step S4).

When a xenon excimer lamp is used as the UV light source 11, its energy is 7.2 eV and is larger than the binding energy of NF ₃ , which is 6.6 eV, so that NF ₃ is excited and dissociated to generate an F radical ( Step S5).

Sufficient time for the NF ₃ introduced from the gas introduction unit 16 to be dissociated in the space between the window member 13 and the first gas dispersion plate 14 is secured, so that the F radical generation efficiency is increased. The generated F radicals pass through the opening of the first gas dispersion plate 14 and then spread over the entire surface in the space between the first gas dispersion plate 14 and the second gas dispersion plate 15 to form the second gas. It passes through the opening of the dispersion plate 15. Since the opening is formed on the entire surface of the second gas dispersion plate 15, the F radicals passing through the opening of the second gas dispersion plate 15 are formed on the entire surface of the space between the second gas dispersion plate 15 and the wafer holder 17. It spreads uniformly and is supplied onto the wafer W. The F radicals supplied onto the wafer W react with the dummy gate electrode 73 made of polysilicon according to the following reaction formula.
(Chemical formula 1)
Si + 4F ^* → SiF ₄ ↑
That is, the F radical (F ^* ) reacts with Si to become SiF ₄ , and SiF ₄ is removed from the wafer W because it is sublimated (step S6).

Since the UV light is not irradiated onto the wafer W and is etched by the F radicals, the wafer W is not damaged and the relative dielectric constant of the low dielectric constant silicon oxide film 72 which is an interlayer insulating film is not increased. .

  In the above embodiment, the case where the number of gas dispersion plates is two and the number of gas distribution plates is three has been described, but the number of gas dispersion plates is not limited to these. Further, in the above-mentioned embodiment, the thickness of the gas dispersion plate has been described as 3 mm, but it may be thicker than this. By increasing the thickness, the effect of blocking UV light obliquely entering the opening of the gas dispersion plate is enhanced.

W wafer 1 , 1A etching apparatus 10 processing chamber 11 UV light source 12 lamp house 13 window member 14 first gas dispersion plate
14a Opening 15 Second gas dispersion plate 16 Gas introduction part 17 Wafer holder 18 Heater 19 Exhaust port 20 Third gas dispersion plate 71 Silicon substrate 72 Silicon oxide film 73 Dummy gate electrode

Claims (8)

A processing chamber for processing the substrate,
A substrate holder for holding a substrate on the bottom of the processing chamber,
A gas introducing unit disposed at the upper part of the processing chamber, for introducing a reactive gas into the processing chamber,
A UV light source that is disposed on the top plate surface of the processing chamber and emits UV light;
A window member that transmits the UV light from the UV light source to the processing chamber;
An exhaust port connected to the bottom of the processing chamber for reducing the pressure inside the processing chamber,
A plurality of gas dispersion plates having an opening located between the substrate holding part and the gas introduction part,
Equipped with
The positions of the openings opened in the respective gas dispersion plates of the plurality of gas dispersion plates are arranged at positions that do not overlap in the vertical direction ,
The plurality of gas dispersion plates includes a first gas dispersion plate and a second gas dispersion plate, and the first gas dispersion plate has an opening in a region from a center to a predetermined position, position wherein a first 60% or less than 30% of the radius of the gas distribution plate, and wherein the first spacing is 10mm or less der Rukoto least 2mm of the gas distribution plate second gas distribution plate Etching equipment characterized by.   The etching apparatus according to claim 1, wherein an opening diameter of the plurality of gas dispersion plates is 0.02 mm or more and 0.3 mm or less. The opening diameter of the second gas distribution plate, the etching apparatus according to any one of claims 1 to 2, characterized in that less than the opening diameter of the first gas distribution plate. It said plurality of gas dispersion plates, etching apparatus according to any one of claims 1 to 3, characterized in that it is composed of a ceramic such as aluminum oxide or yttrium oxide. The reactive gas is an etching apparatus according to any one of claims 1 to 4, characterized in that the SF ₆ or NF _3. Said window member, the etching apparatus according to any one of claims 1 to 5, characterized in that it consists of quartz coated with silica or yttrium oxide. Etching apparatus according to any one of claims 1 to 6, further comprising a heating mechanism for heating the substrate to the substrate holder. A etching method using the etching apparatus according to any one of claim 1 to 7
Placing the substrate on the substrate holder,
Depressurizing the processing chamber by exhausting it from the exhaust port connected to the bottom of the processing chamber;
A step of introducing the reactive gas from the gas introduction part,
Irradiating the reactive gas with the UV light from the UV light source;
Etching the semiconductor substrate by supplying radicals generated by irradiating the reactive gas with the UV light onto the substrate;
An etching method comprising:

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