JP2009277890A - Etching method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase HF concentration of reactant gas, and to improve etching rate in plasma etching. <P>SOLUTION: Material gas containing fluorine content material and H<SB>2</SB>O or OH group content compound is passed through plasma space 5b of a generation portion 5 near atmospheric pressure, and then rectant gas containing HF and COF<SB>2</SB>or F<SB>2</SB>is generated. Etching is performed by transporting the reactant gas to the disposition portion 2 of a subject 9 to be processed using a transportation path 10. During the transit process, the reactant gas is condensed into a condensate by a condensing portion 7, and then the condensate is evoparated by a vaporation portion 8. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and apparatus for performing etching by spraying a reaction gas on an object to be processed.

For example, in Patent Document 1, a fluorine-containing gas (CF ₄ , SF ₆ , CHF _3, etc.) is irradiated with plasma under atmospheric pressure to generate a reaction gas containing HF, COF ₂ , F _2, etc., and this reaction gas Etching is carried out by spraying on the object to be processed. In order to prevent non-uniform etching, a heater is provided in the transport pipe and heated. Water is attached to the surface of the object to be processed, and COF ₂ or F ₂ is reacted with water to be changed to HF. Alcohol may be used instead of water.
JP 2000-58508 A (Claim 1, paragraphs 0014 and 0016)

When water or alcohol is adhered to the surface of the object to be processed, if the adhesion state is not uniform, the etching finish is deteriorated. However, uniform adhesion may be difficult depending on the surface state of the workpiece.
The present invention has been made in view of the above circumstances, and the object of the present invention is to convert the COF ₂ or F ₂ in the reaction gas generated by plasma into HF without impairing the processing quality, and finally the reaction gas. It is to increase the HF concentration and improve the etching rate.

In order to solve the above-described problems, an etching method according to the present invention passes a source gas containing a fluorine-containing source and a H ₂ O or OH group-containing compound (for example, alcohol) through a plasma space near atmospheric pressure, and HF and COF _2. Or a production step for producing a reaction gas containing F ₂ ;
A transporting step of transporting the reaction gas from the plasma space to an arrangement portion of an object to be processed;
Performing an etching step of bringing the reaction gas into contact with the object to be processed and etching the object to be processed;
The reaction gas is condensed during the transporting step to obtain a condensate, and then the condensate is vaporized.
According to this characteristic configuration, a condensate such as hydrofluoric acid is generated in the transport process. In this condensate, COF ₂ or F ₂ in the reaction gas dissolves into HF, and the HF concentration in the condensate increases. Thereafter, the condensate is vaporized to obtain a reaction gas having a high HF concentration. Thereby, it is possible to prevent the processing quality from being impaired and to increase the etching rate.

The condensation is preferably performed by cooling the reaction gas.
Thereby, the reaction gas can be reliably condensed and a condensate can be obtained reliably.

It is preferable that the HF concentration of the condensate exceeds the azeotropic concentration during the cooling.
This allows the condensate to grow until cooling is in progress (the HF concentration of the condensate reaches the azeotropic concentration). During this time, COF ₂ or F ₂ in the reaction gas dissolves in the condensate and becomes HF, and the HF concentration of the condensate gradually increases. Eventually, the HF concentration of the condensate reaches the azeotropic concentration. Therefore, the vaporization of the condensate becomes dominant thereafter, and the HF concentration of the reaction gas can be gradually increased.

The vaporization is preferably performed by heating the condensate.
Thereby, a condensate can be vaporized reliably.

It is preferable to repeat the condensation and the vaporization during the transporting process, and finally perform the vaporization.
Thereby, COF ₂ or F ₂ in the reaction gas can be sufficiently converted to HF, and the HF concentration can be sufficiently increased. By finally vaporizing, the reaction gas can be reliably supplied to the object to be processed in a gas state, and the processing quality can be sufficiently ensured.

The fluorine-containing raw material is selected from the group consisting of CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ , CHF ₃ , CH ₃ F, CH ₂ F ₂ , SF _6. At least one is preferred.
Thereby, the reaction gas containing HF and COF ₂ or F ₂ can be reliably generated. Note that the reaction gas also includes some raw material gas components including H ₂ O or OH group-containing compounds. During the transport process, a condensate such as hydrofluoric acid is generated by the H ₂ O or OH group-containing compound and HF.

An etching apparatus according to the present invention is an apparatus for bringing a reaction gas containing HF and COF ₂ or F ₂ into contact with an object to be processed, and etching the object to be processed.
A source part containing a fluorine-containing raw material and a H ₂ O or OH group-containing compound (for example, alcohol) into a plasma under the vicinity of atmospheric pressure to generate the reaction gas;
An arrangement unit that arranges the workpiece away from the generation unit;
A transport path for transporting the reaction gas from the generation unit to the arrangement unit;
A condensing part that is provided in the middle of the transport path to obtain a condensate by condensing the reaction gas;
A vaporizing unit provided on the downstream side of the condensing unit of the transport path, and vaporizing the condensate;
It is provided with.
According to this characteristic configuration, the reaction gas is condensed in the condensing part in the middle of the transport path, and a condensate such as hydrofluoric acid is generated. In this condensate, COF ₂ or F ₂ in the reaction gas dissolves into HF, and the HF concentration in the condensate increases. Thereafter, the condensate is vaporized in the vaporization section. Thereby, a reaction gas having a high HF concentration can be obtained. As a result, it is possible to prevent the processing quality from being impaired and to increase the etching rate.

It is preferable that a cooling unit for cooling the transport pipe constituting the transport path is provided, and a part or all of the cooling unit is the condensing unit.
Thereby, the reaction gas can be reliably condensed and a condensate can be obtained reliably.

It is preferable that the flow path cross-sectional area of the transport pipe in the cooling section is a size that allows the condensate condensed on the inner wall to close the transport pipe.
When the condensate closes the transport pipe, the condensate is pushed by the upstream reaction gas. Therefore, the condensate can be reliably moved to the downstream side of the transport path. In addition, it is possible to ensure that the reaction gas contacts the condensate. Therefore, COF ₂ or F ₂ in the reaction gas can be surely dissolved in the condensate, and can be sufficiently HF-converted. As a result, the final HF concentration of the reaction gas can be sufficiently increased.

The length of the transport pipe in the cooling section is preferably such that the HF concentration of the condensate exceeds the azeotropic concentration in the middle of the transport pipe in the cooling section.
Thereby, the condensate can be grown up to the middle of the transport pipe in the cooling section. During this time, COF ₂ or F ₂ in the reaction gas dissolves in the condensate and becomes HF, and the HF concentration of the condensate gradually increases. Eventually, the HF concentration of the condensate reaches the azeotropic concentration in the middle of the transport pipe in the cooling section. Therefore, the vaporization of the condensate becomes dominant in the transport pipe on the downstream side of the location, and the HF concentration of the reaction gas can be gradually increased.

In the cooling section, a transport pipe constituting the transport path extends vertically, a transport path between the generation section and the cooling section is connected to an upper end portion of the transport pipe in the cooling section, and the transport pipe in the cooling section It is preferable that a transport path downstream from the cooling portion extends from the lower end portion to the arrangement portion.
Thereby, the condensate condensed on the inner wall of the transport pipe in the cooling section can move to the downstream side of the transport path not only by the fluid pressure of the reaction gas but also by gravity.

The cooling unit includes a cooling container that houses the transport pipe, and a refrigerant is passed between an inner peripheral surface of the cooling container and an outer peripheral surface of the transport pipe, and the cooling container and the transport pipe It is preferable that the portion accommodated in the cooling container and the refrigerant are transparent.
Thereby, the condensation state and the vaporization state in the transport pipe of the cooling unit can be visually confirmed.

In the cooling part, it is preferable that the transport path is branched into a plurality of branch transport paths. That is, it is preferable that a plurality of transport pipes constituting the transport path in the cooling unit are provided.
As a result, the reaction gas is divided into a plurality of transport pipes (branch transport paths). Therefore, the channel cross-sectional area of each transport pipe (branch transport path) can be reduced. Therefore, the condensate can easily block the inside of the transport pipe, and as a result, the final HF concentration of the reaction gas can be sufficiently increased as described above.

It is preferable that each of the plurality of transport paths branched (the branch transport path including the transport pipe) is provided with a throttle portion that reduces conductance.
As a result, the inside of some of the transport pipes (branch transport paths) in the cooling section is blocked by the condensate, and the flow resistance of the transport pipe (branch transport path) increases. Even so, it is possible to suppress or prevent the reaction gas from preferentially flowing into the transport pipe (branch transport path) that is not blocked.
It is preferable that the flow path resistance by the throttle portion is larger than the flow path resistance generated when the condensate blocks the flow path resistance. Thereby, even if a part of the transport pipes (branch transport paths) is blocked, the reaction gas can flow almost uniformly into the plurality of transport pipes (branch transport paths).
It is desirable to provide the throttle part in the upstream part of the cooling part or in the upstream part of the branch transport path. As a result, it is possible to prevent the condensate from being generated in the throttling part and the condensate formed on the upstream side from flowing into the throttling part, and the transport pipe ( It is possible to prevent the branch transportation route) from being completely blocked.

It is preferable that the vaporization unit includes a heating unit that heats the condensate.
Thereby, a condensate can be vaporized reliably.

It is preferable that a gas reservoir chamber for storing the reaction gas is interposed in the vicinity of the downstream end of the transport path.
Thereby, the HF concentration of the reaction gas supplied to the placement unit can be made constant, and the processing quality can be ensured reliably.

Here, the vicinity of atmospheric pressure (substantially normal pressure) refers to a range of 1.013 × 10 ^{4 to} 50.663 × 10 ⁴ Pa, and considering the ease of pressure adjustment and the simplification of the apparatus configuration, 333 × 10 ^{4 to} 10.664 × 10 ⁴ Pa (100 to 800 Torr) is preferable, and 9.331 × 10 ^{4 to} 10.9797 × 10 ⁴ Pa (700 to 780 Torr) is more preferable.

According to the present invention, COF ₂ or F ₂ in a reaction gas generated by plasma can be converted to HF without impairing the processing quality, and the final HF concentration of the reaction gas can be increased. As a result, the etching rate can be increased. Can be improved.

Hereinafter, a first embodiment of the present invention will be described.
As shown in FIG. 1, the workpiece 9 of this embodiment is, for example, a glass substrate for a liquid crystal display. A silicon oxide film 9 a is formed on the surface of the substrate 9. This silicon oxide film 9a is an object to be etched.

The etching apparatus 1 includes a workpiece placement unit 2 and a reaction gas supply system 3. The placement unit 2 is composed of a stage, and the workpiece 9 is placed on the top surface thereof.
The arrangement | positioning part 2 is not limited to a stage, You may be comprised by the roller conveyor etc.

The reaction gas supply system 3 includes a source gas supply source 4, a reaction gas generation unit 5, and a nozzle head 6.
The raw material gas of the raw material gas supply source 4 contains a fluorine-containing raw material and H ₂ O, and preferably further contains a carrier gas. The fluorine-containing raw material is selected from the group consisting of CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ , CHF ₃ , CH ₃ F, CH ₂ F ₂ , SF ₆ , these It is not limited to one of the compounds, and a mixture of two or more may be used. Here, CF ₄ is used as the fluorine-containing raw material. For example, Ar or N ₂ is used as the carrier gas. Here, Ar is used as the carrier gas. By using Ar, plasma generation described later is facilitated. The component ratio of the source gas is, for example, Ar: CF ₄ : H ₂ O = 0.9: 0.1: 0.03. Of course, this component ratio is an example and may be changed as appropriate.

A raw material supply path 4 a extends from the raw material gas supply source 4. The supply path 4a is heated to about 40 ° C. by a heater (not shown). This is to prevent condensation of about 3% of H ₂ O in the raw material gas passing through the supply path 4a. The supply path 4 a is connected to the reaction gas generation unit 5.

  The reactive gas generator 5 has a pair of electrodes 5a. Although detailed illustration is omitted, one of these electrodes 5a is connected to a power source, and the other is electrically grounded. An electric field is applied between the electrodes 5a by voltage supply from the power source, and plasma discharge is generated near atmospheric pressure. Thereby, the space between the electrodes 5a becomes a plasma space 5b near atmospheric pressure.

  The nozzle head 6 is arranged so as to face the arrangement unit 2. A blowing port 6 a and a suction port 6 b are formed on the surface facing the arrangement portion 2 of the nozzle head 6.

  An exhaust means (not shown) including a suction pump, an exhaust gas treatment facility, and the like is connected to the suction port 6b.

  Although illustration is omitted, a moving means is connected to one of the nozzle head 6 and the arrangement portion 2 so as to move relative to each other. The moving direction coincides with the separation direction of the outlet 6a and the inlet 6b.

  The reactive gas generator 5 and thus the plasma space 5b are separated from the nozzle head 6 and the object placement portion 2. The plasma space 5 b and the outlet 6 a of the nozzle head 6 are connected by a transport path 10.

  A cooling unit 20 composed of a heat exchanger is provided at an intermediate portion of the transport path 10. The transport path 10 branches into a plurality of branch transport paths 18 near the entrance inside the cooling unit 20 and merges near the exit. A chiller 22 is attached to the cooling unit 20. A refrigerant is circulated between the cooling unit 20 and the chiller 22. For example, water is used as the refrigerant.

  FIG. 2 shows a specific structure of the cooling unit 20. The cooling unit 20 includes a cylindrical cooling container 21 extending in the vertical direction (vertical). The cooling container 21 is made of a transparent material such as acrylic. A distribution header 23 is provided at the upper end of the cooling container 21. A merge header 24 is provided at the lower end of the cooling container 21.

  An upstream side path 11 (a transport path between the generation unit 5 and the cooling unit 20) of the transport path 10 is connected to the introduction port 23 a of the distribution header 23. Inside the distribution header 23, a distribution path 12 constituting a part of the transport path 10 is formed. The distribution path 12 extends from the introduction port 23 a and branches into a plurality, and each branch path 12 a reaches the lower surface of the distribution header 23. Each branch passage 12a is provided with a throttle portion 19 such as an orifice. Accordingly, the conductance is reduced in the throttle portion 19 and the flow path resistance is increased. The flow path resistance by the throttle unit 19 is set so as to be larger than the flow path resistance generated when blocked by a condensate described later.

  A plurality of transport pipes 13 are accommodated inside the cooling container 21. Each transport pipe 13 has a straight tubular shape extending in the vertical direction (vertical). The transport pipe 13 is made of a transparent material having high hydrogen fluoride resistance. Here, a transparent Teflon (registered trademark) tube is used as the transport tube 13. A plurality of transport pipes 13 are arranged in parallel and spaced apart from each other. The upper end portion of each transport pipe 13 is supported by the distribution header 23. The branch path 12a of the distribution path 12 in the distribution header 23 and the upper end portion of the transport pipe 13 are connected one-to-one.

  The flow path cross-sectional area of the transport pipe 13 is sufficiently small so that the condensate described later can close the inside of the transport pipe 13. Specifically, the inner diameter of the transport pipe 13 is, for example, 4 mm or less, and preferably about 2 mm.

  The length of the transport pipe 13 is set so that the HF concentration of the condensate described later reaches the azeotropic concentration in the middle of the transport pipe 13 (for example, a point around the reference numeral 13p). Specifically, the length of the transport pipe 13 is about 1 m, for example. The length of the transport pipe 13 may be longer or shorter than 1 m as necessary.

The part above the middle part 13p of the transport pipe 13 in the cooling part 20 constitutes the condensing part 7.
The part below the middle part 13p of the transport pipe 13 in the cooling part 20 constitutes the vaporization part 8.

The lower end portion of each transport pipe 13 is supported by the merge header 24. Inside the merging header 24, a merging channel 14 constituting a part of the transportation path 10 is formed. The combined flow path 14 has branch paths 14a extending from the transport pipes 13, and these branch paths 14a are joined together.
The branch transport path 18 (FIG. 1) is constituted by the branch path 12a, the transport pipe 13, and the branch path 14a connected in a row.
The post-merging path 14 is connected to the outlet port 24 b of the merging header 24.

  A downstream path 15 (transport path downstream from the cooling unit 20) of the transport path 10 extends from the outlet port 24b. The downstream side path 15 extends to the nozzle head 6 and thus to the arrangement portion 2 (see FIG. 1).

  A coolant inflow port 21 a is formed on the side of the lower end of the cooling container 21. A refrigerant outflow port 21 b is formed on the side of the upper end of the cooling container 21. A refrigerant return path 26 extends from the outflow port 21b. As shown in FIG. 1, the refrigerant return path 26 is continuous with the intake port 22 b of the chiller 22. A refrigerant supply path 25 extends from the outlet 22 a of the chiller 22. As shown in FIG. 2, the refrigerant supply path 25 is continuous with the inflow port 21a.

A method of etching the silicon oxide film 9a of the workpiece 9 using the etching apparatus 1 configured as described above will be described.
[Reaction gas generation process]
The source gas (Ar + CF ₄ + H ₂ O) of the supply source 4 is introduced into the interelectrode space 5b of the reaction gas generation unit 5 through the supply path 4a. In the interelectrode space 5b, the temperature of the gas is quickly heated to about 100 ° C. The interelectrode space 5b becomes a plasma space near atmospheric pressure by applying an electric field. Thereby, the source gas is turned into plasma (including decomposition, excitation, activation, radicalization, and ionization), and a reaction gas containing HF and COF ₂ is generated. The reaction gas also includes a raw material gas component that has not been decomposed in the plasma space 5b, and thus also includes H ₂ O.
For example, when the component ratio of the source gas is Ar: CF ₄ : H ₂ O = 0.9: 0.1: 0.03, HF in the reaction gas is about 0.77 vol%, and COF ₂ is about ₂ vol. % And H2O is about 1.23 vol%. The reaction gas may further contain F ₂ or the like.

[Transportation process]
The reaction gas generated in the plasma space 5 b is transported to the nozzle head 6 and thus to the placement portion 2 by the transport path 10. The reaction gas is condensed in this transport process and then vaporized, which will be described in detail later.

[Etching process]
The reaction gas that has reached the nozzle head 6 by the transport path 10 is blown out from the blowout port 6a and contacts the object 9 on the placement unit 2. Thereby, HF in the reaction gas reacts with the silicon oxide film 9a, and the silicon oxide film 9a is etched.
The treated gas is sucked and discharged from the suction port 6b.

The transportation process will be described in detail.
The reaction gas generated in the plasma space 5 b is introduced into the introduction port 23 a of the cooling unit 20 through the upstream side path 11. The reaction gas is about 100 ° C. when generated in the plasma space 5b, but is cooled by air while passing through the upstream side passage 11, and is about 30 ° C. near the introduction port 23a. This reaction gas is evenly divided by the distribution path 12 and introduced into the upper end of each transport pipe 13.

The reaction gas flows downward in each transport pipe 13.
On the other hand, the refrigerant (water) cooled by the chiller 22 is supplied from the port 21 a to the inside of the cooling container 21 through the supply path 25. The temperature of the refrigerant is about 19 ° C., for example. The refrigerant cools each transport pipe 13 while flowing upward between the inner peripheral surface of the cooling container 21 and the outer peripheral face of each transport pipe 13, and then returns to the chiller 22 through the return path 26. With this refrigerant, the inner wall of each transport pipe 13 becomes about 20 ° C. Therefore, in the upper part of each transport pipe 13 (region of the condensing part 7), H ₂ O of the reaction gas is condensed on the inner wall, HF is dissolved therein, and a hydrofluoric acid condensate is formed. The condensate that has just condensed is in the form of a number of fine drops, and the inner wall of the transport pipe 13 becomes cloudy. At this time, the HF concentration of the condensate is lower than the azeotropic concentration (about 38 wt%). HF in the reaction gas further dissolves in the condensate and COF ₂ and F ₂ dissolve and react to change to HF. Thereby, the HF density | concentration of a condensate becomes high. Since the condensate composed of many fine droplets has a relatively large surface area, the contact efficiency with the reaction gas is good. Therefore, the reaction rate of HF conversion of COF ₂ and F _{2 in} the reaction gas can be increased.

  As the condensation of the reaction gas proceeds, the condensate grows gradually and the droplet diameter increases. When the droplet diameter of the condensate becomes a certain size, the condensate is moved downward (downstream of the transport path 10) by the flow of the reaction gas and gravity. Since Teflon (registered trademark), which is a material of the transport pipe 13, is hydrophobic, a part of the condensate that has moved downward is hardly left in the original place. Many fine droplet-like condensates are newly formed on the inner wall of the transport pipe 13 after the large condensate has moved.

The condensate eventually becomes large enough to close the transport pipe 13. By making the flow path cross-sectional area of the transport pipe 13 sufficiently small, the transport pipe 13 can be reliably closed when the condensate has grown a little. When the transport pipe 13 is closed, the gas pressure above the condensate increases greatly. This ensures that the condensate is pushed downward. At the same time, COF ₂ and F ₂ in the reaction gas are reliably brought into contact with the condensate. This further increases the HF concentration of the condensate.

  When the inside of some of the plurality of transport pipes 13 is blocked with a condensate, the flow path resistance of the pipes 13 increases. However, since the restriction 19 is provided in each branch passage 12a, it is possible to suppress or prevent the reaction gas from the upstream passage 11 from flowing preferentially to the transport pipe 13 that is not blocked. Since the flow path resistance due to the throttle portion is larger than the flow path resistance generated when blocked by the condensate, it is possible to ensure that the reaction gas flows evenly through the plurality of transport pipes 13. Since the throttle part 19 is provided on the upstream side of the transport pipe 13, no condensate is generated in the throttle part 19, and the condensate formed on the upstream side does not flow into the throttle part 19. Therefore, it is possible to prevent the transport pipe 13 from being completely clogged by the condensate having a viscosity much higher than that of the gas.

In the vicinity of the middle portion 13p of the transport pipe 13, the HF concentration of the condensate reaches the azeotropic concentration. At this point, the condensate stops growing.
In the portion below the middle portion 13p of the transport pipe 13 (region of the vaporization portion 8), the HF concentration of the condensate exceeds the azeotropic concentration. Therefore, the condensate gradually vaporizes and becomes smaller. Even if the azeotropic concentration is exceeded, COF ₂ or F ₂ may be dissolved in the condensate, so that the HF concentration of the condensate continuously increases. Therefore, vaporization of the condensate is further promoted. The condensate having a high HF concentration is vaporized and returned to the gas phase, thereby increasing the HF concentration of the reaction gas. Thus, at the lower end of the transport pipe 13, the condensate almost disappears and a reaction gas having a high HF concentration is obtained.

  It is preferable that the reaction gas flows through the transport pipe 13 for at least 1 second. Therefore, when the supply flow rate of the reaction gas is 1 L / min, the number of transport pipes 13 is preferably about six.

  Since the cooling container 21, the refrigerant (water), and the transport pipe 13 are transparent, the condensed state and the vaporized state in the transport pipe 13 can be visually observed. When vaporization in the lower part of the transport pipe 13 is not sufficient and a condensate remains at the lower end of the transport pipe 13, the transport pipe 13 may be lengthened.

The reaction gas exiting from the lower end of each transport pipe 13 is merged by the merge channel 14 and led out to the downstream side channel 15 via the lead-out port 24b. The HF concentration of the reaction gas at the outlet port 24b is, for example, about 2.8 vol%, and the H ₂ O concentration is, for example, about 0.215 vol%. The COF ₂ concentration decreases to about 1 vol%, for example. The temperature of the reaction gas at the outlet port 24b is about 20 ° C., for example.

  As described above, in the etching apparatus 1, the HF concentration of the reaction gas is increased during the transport process by the transport path 10, so that the etching rate of the workpiece 9 can be increased. In addition, since the condensate disappears and becomes only gas when the reaction gas is led out from the cooling unit 20, the uniformity of processing can be improved and the processing quality can be ensured.

Next, another embodiment of the present invention will be described. In the following embodiments, the same reference numerals are given to the drawings for the same configurations as those already described, and the description thereof is omitted.
FIG. 3 shows a second embodiment of the present invention. In this embodiment, the heating unit 30 is provided in the heated path 16 on the downstream side of the cooling unit 20 in the transport path 10. The heating unit 30 is configured by, for example, a ribbon heater or the like provided on the outer periphery of a tube that configures the heated path 16.
The heating unit 30 constitutes the vaporization unit 8 together with the lower part of the cooling unit 20 (a region where the HF concentration of the condensate exceeds the azeotropic concentration).
A downstream path 15 extends from the heated path 16 and is connected to the nozzle head 6.

  The second embodiment is suitable when the condensate cannot be completely vaporized in the transport pipe 13. The condensate that could not be vaporized is pushed out by the reaction gas, led out from the lower end of the transport pipe 13, and sent to the path 16 in the heating unit 30. This condensate is heated by the heating unit 30. Thereby, a condensate can be vaporized reliably. Thereby, it can prevent reliably that a condensate is sprayed on the to-be-processed object 9, and process quality can be improved.

  FIG. 4 shows a third embodiment of the present invention. In this embodiment, a plurality (two here) of cooling units 20 and a plurality (two here) of heating units 30 are alternately arranged in a line along the transport path 10. A cooling unit 20 is disposed at the uppermost stage. A heating unit 30 is arranged at the lowest level.

In the third embodiment, condensation and vaporization are repeated in the reaction gas transport process. Therefore, COF ₂ and F _{2 that} have not been converted to HF in the preceding cooling unit 20 come into contact with the condensate again in the subsequent cooling unit 20. As a result, COF ₂ and F ₂ in the reaction gas can be sufficiently HFed, and the HF concentration of the final reaction gas can be further increased. As a result, the etching rate can be further increased.

  FIG. 5 shows a fourth embodiment of the present invention. This embodiment is a modification of the third embodiment (FIG. 4). The heating unit 30 is omitted from the transportation path 10 of the third embodiment, and the tubes constituting the heated path 16 are exposed to the air atmosphere. It is a thing. The heated path 16 is heated and vaporized by the heat (room temperature) of the atmospheric air.

  FIG. 6 shows a fifth embodiment of the present invention. In this embodiment, a gas reservoir chamber 40 is provided between the heating unit 30 at the final stage and the nozzle head 6. The heated path 16 in the final stage heating unit 30 is connected to the gas reservoir chamber 40 through the gas reservoir path 17. The gas reservoir chamber 40 is composed of a large capacity tank or the like. A downstream path 15 extends from the gas reservoir chamber 40 and is connected to the nozzle head 6.

  Further, in the fifth embodiment, the transportation path 10 in the cooling unit 20 is not branched into a plurality of parts and is configured by one transportation pipe 13A. The inner diameter of the transport pipe 13A is larger than that of the above-described embodiment (FIGS. 1 to 5).

  Therefore, relatively large condensates can be formed in some places on the inner wall of the transport pipe 13A. When a large and high HF concentration condensate enters the heating unit 30, the HF concentration of the reaction gas rapidly increases due to the vaporization. Therefore, the HF concentration of the reaction gas becomes unstable at the outlet of the heating unit 30.

  The reaction gas exiting from the heating section 30 at the final stage is temporarily stored in the gas storage chamber 40 through the path 17. In the gas reservoir chamber 40, reaction gases having different HF concentrations are mixed and become uniform. Therefore, the reaction gas can be always supplied to the workpiece 9 (see FIG. 1) at a constant HF concentration, and the processing quality can be ensured.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, the workpiece 9 is not limited to a glass substrate but may be a semiconductor wafer or a continuous resin sheet.
The etching target is not limited to silicon oxide, but may be silicon nitride or silicon (amorphous silicon, polysilicon, single crystal silicon, etc.). When etching silicon, an oxidizing reaction component such as ozone may be added to the reaction gas.
As a component of the source gas, alcohol (OH group-containing compound) may be used instead of H ₂ O.
The reaction gas in the cooling unit 20 may be cooled by air cooling.
The transportation path 10 in the cooling unit 20 and the heating unit 30 may not be vertically (vertical), may be horizontal, or may be oblique.
In 3rd Embodiment, although the number of the cooling parts 20 and the heating parts 30 is two each, it is not restricted to this, Three or more may be sufficient. The same applies to the fourth and fifth embodiments.
Two or more embodiments may be combined with each other. For example, the gas reservoir chamber 40 of the fifth embodiment may be provided also in a structure in which the transportation path 10 of the first to fourth embodiments branches into a plurality of parts in the cooling unit 20.

  The present invention can be used for manufacturing a semiconductor substrate and a flat panel display (FPD), for example.

1 is a schematic configuration diagram of an etching apparatus according to a first embodiment of the present invention. It is a longitudinal cross-sectional view which shows the detailed structure of the cooling part of the said etching apparatus. It is a schematic block diagram which shows the transport path of the etching apparatus which concerns on 2nd Embodiment of this invention. It is a schematic block diagram which shows the transport path of the etching apparatus which concerns on 3rd Embodiment of this invention. It is a schematic block diagram which shows the transport path of the etching apparatus which concerns on 4th Embodiment of this invention. It is a schematic block diagram which shows the transport path of the etching apparatus which concerns on 5th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Etching apparatus 2 Processed object arrangement | positioning part 3 Reaction gas supply system 4 Raw material gas supply source 4a Raw material gas supply path 5 Reaction gas production | generation part 5a Electrode 5b Plasma space 6 Nozzle head 6a Outlet 6b Suction port 7 Condensing part 8 Vaporization part 9 Processed object 9a Silicon oxide film 10 Transport path 11 Upstream path (transport path between generating section and cooling section)
12 Distribution path 13 Transport pipe 13A in cooling section Transport pipe 13p in cooling section Location where HF concentration in transport pipe reaches azeotropic concentration 14 Combined flow path 15 Downstream path 16 Heated path 17 Gas storage path 18 Branch transport path 19 Restriction section 20 Heat exchanger (cooling part)
21 Cooling vessel 21a Refrigerant inflow port 21b Refrigerant outflow port 22 Chiller 23 Distribution header 23a Inlet port 24 Merge header 24b Outlet port 25 Refrigerant supply path 26 Refrigerant return path 30 Heating unit 40 Gas reservoir chamber

Claims (16)

A production step of passing a raw material gas containing a fluorine-containing raw material and a H ₂ O or OH group-containing compound through a plasma space near atmospheric pressure to generate a reaction gas containing HF and COF ₂ or F ₂ ;
A transporting step of transporting the reaction gas from the plasma space to an arrangement portion of an object to be processed;
Performing an etching step of bringing the reaction gas into contact with the object to be processed and etching the object to be processed;
An etching method comprising condensing the reaction gas during the transporting step to obtain a condensate, and then vaporizing the condensate.   The etching method according to claim 1, wherein the condensation is performed by cooling the reaction gas.   The etching method according to claim 2, wherein an HF concentration of the condensate exceeds an azeotropic concentration during the cooling.   The etching method according to claim 1, wherein the vaporization is performed by heating the condensate.   5. The etching method according to claim 1, wherein the condensation and the vaporization are repeated during the transportation step, and the vaporization is finally performed. The fluorine-containing raw material is selected from the group consisting of CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ , CHF ₃ , CH ₃ F, CH ₂ F ₂ , SF _6. 6. The etching method according to claim 1, wherein there is at least one. An apparatus for bringing a reaction gas containing HF and COF ₂ or F ₂ into contact with an object to be processed and etching the object to be processed,
A source part containing a fluorine-containing raw material and a H ₂ O or OH group-containing compound is converted into plasma under the vicinity of atmospheric pressure to generate the reaction gas,
An arrangement unit that arranges the workpiece away from the generation unit;
A transport path for transporting the reaction gas from the generation unit to the arrangement unit;
A condensing part that is provided in the middle of the transport path to obtain a condensate by condensing the reaction gas;
A vaporizing unit provided on the downstream side of the condensing unit of the transport path, and vaporizing the condensate;
An etching apparatus comprising:   The etching apparatus according to claim 7, further comprising a cooling unit that cools the transport pipe that forms the transport path, wherein a part or all of the cooling unit is the condensing unit.   9. The etching apparatus according to claim 8, wherein a flow path cross-sectional area of the transport pipe in the cooling unit is such that the condensate condensed on the inner wall can block the transport pipe.   The length of the transport pipe in the cooling section is such that the HF concentration of the condensate exceeds the azeotropic concentration in the middle of the transport pipe in the cooling section. Etching equipment.   In the cooling section, a transport pipe constituting the transport path extends vertically, a transport path between the generation section and the cooling section is connected to an upper end portion of the transport pipe in the cooling section, and the transport pipe in the cooling section The etching apparatus according to any one of claims 8 to 10, wherein a transport path downstream from the lower end portion extends to the arrangement portion.   The cooling unit includes a cooling container that houses the transport pipe, and a refrigerant is passed between an inner peripheral surface of the cooling container and an outer peripheral surface of the transport pipe, and the cooling container and the transport pipe The etching apparatus according to claim 8, wherein a portion accommodated in a cooling container and the refrigerant are transparent.   The etching apparatus according to claim 8, wherein the transport path is branched into a plurality of parts in the cooling unit.   14. The etching apparatus according to claim 13, wherein each of the plurality of transport paths branched is provided with a throttle portion for reducing conductance.   The etching apparatus according to claim 7, wherein the vaporization unit includes a heating unit that heats the condensate.   The etching apparatus according to claim 7, wherein a gas reservoir chamber for accumulating the reaction gas is interposed in the vicinity of a downstream end of the transport path.

Images