JP4167542B2 - Gas supply apparatus for plasma etching and plasma etching system and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for supplying a processing gas to an atmospheric pressure plasma etching apparatus, and in particular, silicon oxide is selectively used for an object to be processed (such as an electronic device or a crystal device such as a SAW filter) having silicon oxide and a metal. In particular, the present invention relates to a process gas supply method and apparatus suitable for plasma etching at normal pressure.
[0002]
[Prior art]
In general, an electronic device is configured by a combination of several kinds of materials such as an insulator, a semiconductor, and a conductor. In an etching process in manufacturing such a device, it is required to selectively etch only a specific material.
[0003]
For example, in the SAW filter, a comb-shaped conductive pattern made of Al is formed on a substrate made of quartz mainly composed of silicon oxide. The characteristics of the SAW filter are greatly influenced by the size of the step between the Al surface and the exposed surface of the quartz substrate. In order to adjust this step, crystal etching is performed. In addition, in electronic devices in which conductive patterns and oxide films made of Cu or Al are alternately stacked on a Si wafer, via holes are formed by etching the oxide film layer between them in order to connect the upper and lower patterns. There is a need to.
[0004]
In such etching, if the conductive pattern is also scraped, control becomes impossible and a high-quality product cannot be obtained.
[0005]
As an example applied to a device such as a semiconductor device, for example, in the etching means described in Patent Document 1, a pair of upper and lower parallel plate electrodes (counter electrodes) are arranged in a reaction chamber. Then, an object to be processed is set on the lower electrode, a processing gas is introduced into the reaction chamber at a low pressure, and a high frequency is applied between the electrodes. As a result, plasma is generated under low pressure to etch the object to be processed. As the processing gas, a gas obtained by adding less than 25% (for example, about 12.5%) of water vapor to a freon-based or chlorine-based main gas is used. This increases the etching rate.
[0006]
Further, the etching means described in Patent Document 2 introduces a halogen-based gas into a discharge unit under a pressure near atmospheric pressure and causes discharge to cause COF.₂A reactive gas such as By introducing this reactive gas and water or alcohol into the processing chamber, F^-, HF^2-Etc., and SiO2 of the object to be processed₂Is supposed to be etched.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 3-46326
[Patent Document 2]
JP 2000-58508 A
[0008]
[Problems to be solved by the invention]
Although the thing of patent document 1 has determined the addition amount of the water vapor | steam for raising an etching rate, since it is a process under pressure reduction, this cannot be applied to the process under a normal pressure as it is. In addition, the decompression process has a problem that it takes a lot of time for evacuation and throughput is poor.
The thing of patent document 2 is SiO under normal pressure.₂It is intended to etch SiO2 without damaging the metal electrode.₂The selective etching is not considered.
[0009]
The present invention has been made in view of such a situation, and damages a metal when performing plasma etching on a workpiece having silicon oxide to be etched and a metal that should not be etched under normal pressure. An object of the present invention is to provide a method and an apparatus for supplying a processing gas capable of reliably and selectively etching silicon oxide at a high etching rate.
[0010]
[Means for Solving the Problems]
  The present invention relates to an object to be processed having silicon oxide to be etched and a metal not to be etched.Near atmospheric pressurePlasma etchingDoA method comprising a hydroxyl group-containing compound with respect to a processing gas containing a halogen-based main gas.Additive component consisting ofIs added in a gas phase in an amount of 0.5 to 2.5 vol%, and the processing gas after the addition is supplied to the plasma etching apparatus.And turn into plasmaIt is characterized by doing. The present invention also provides an object to be processed having silicon oxide to be etched and a metal not to be etched.Near atmospheric pressurePlasma etchingSystemBecauseA gas supply device and a plasma etching device, wherein the gas supply device comprises:A processing gas supply source containing a halogen-based main gas; and an addition means for adding an additive component comprising a hydroxyl group-containing compound.Hydroxyl-containing compoundIn the gas phase, andHydroxyl-containing compound0.5 to 2.5 vol% is added to the processing gas excluding the gas, and the processing gas after the addition is supplied to the plasma etching apparatus.Is turned into plasmaIt is characterized by that. As a result, the etching process can be efficiently performed at a good etching rate. In addition, the silicon oxide to be etched can be selectively etched reliably, and the metal that should not be etched can be prevented from being damaged.
[0011]
The object to be processed in the present invention is an electronic device such as a crystal device such as a SAW filter. SiO₂The form is not particularly limited, and includes crystal, glass, oxide film, and the like. The metal includes simple metals used for general wiring such as Cu, Al, W, and ITO, or alloys thereof.
[0012]
Halogen main gas (etchant) is CF_Four, CHF_Three, C₂F₆PFC (perfluorocarbon), etc._Three, SF₆Etc. can be used. The processing gas may be a single gas consisting only of the main gas, and may be a halogen-based main gas and O.sub.2.₂You may use the mixed gas which consists of additional components, such as.
[0013]
  The additive component is water that is inexpensive and has good handleability (H₂O)May be used. As the hydroxyl group-containing compound, Lower alcohol (CH₃OH, C₂H₅C such as OH_nH_{2n + 1}OH (preferably n ≦ 6) may be used. For example, methanol (CH₃The binding energy of OH) is 85 kcal / mol, which is smaller than 120 kcal / mol of water,
Postscript OH radical (OH^*) Is more active.
[0014]
After the addition, the processing gas introduced to the atmospheric plasma etching apparatus (discharge plasma processing unit) is turned into plasma in the apparatus. As a result, silicon oxide (SiO₂) Can be selectively etched. For example, CF as the processing gas_FourAnd O₂As an additive component,₂When O is used, the reaction of these components occurs in the plasma space of the atmospheric pressure plasma etching apparatus, and COF₂Or F₂And HF, and these intermediate products and H₂F reacts with O^-And HF^2-Is generated. These ions are the SiO to be processed.₂Reacts with volatile SiF_FourAnd H₂SiF₆As a result, SiO₂Are selectively etched.
[0015]
Further, by placing an additive component made of water or a hydroxyl group-containing compound in the plasma space, OH radicals (OH^*) Can be generated. OH^*Has the strongest oxidizing power after fluorine. This OH^*For example, CF_FourF is highly reactive^*Can be generated. As a result, SiO₂The etching rate can be increased.
[0016]
Furthermore, the addition of water or a hydroxyl group-containing compound facilitates ionization. That is, for example, when water (dielectric constant: ε = 79) or ethanol (ε = 32.6) is added, the dielectric constant ε of the entire processing gas decreases, and it becomes easier to ionize.
[0017]
Thus, in the present invention, the amount of water or the hydroxyl group-containing compound added is in the range of 0.5 to 2.5 vol% with respect to the processing gas excluding the added component. With this flow ratio configuration, as described above, a high etching rate and a selective etching property of silicon oxide can be ensured. If it is less than 0.5 vol%, the etching rate cannot be improved. If it exceeds 2.5 vol%, the metal part of the object to be treated is damaged and the selective etching property of silicon oxide cannot be ensured.
In addition, since the value of 0.5-2.5 vol% is a trace amount, it may be considered as a numerical value with respect to the entire processing gas including the additive component (processing gas after addition).
[0018]
The means for adding water or a hydroxyl group-containing compound may be a method of injecting a bubbling treatment gas into the liquid raw material of the additive component, a method of bubbling the liquid raw material by heating or the like, and a method of mixing this with the processing gas, etc. Various methods may be used.
[0019]
When the additive component is obtained by vaporizing a liquid, it is preferable to control the condensation point (dew point) to be equal to or lower than the atmospheric temperature of the etching environment in the etching apparatus. Thereby, reliquefaction (condensation) of the additive component can be prevented. The above control may be performed using a dew point meter. A specular dew point meter is preferably used as the dew point meter because it can be controlled with high accuracy. Further, the pipe containing the additive component after vaporization may be heated to prevent reliquefaction in the pipe. As the heating means, a ribbon heater may be wound around the pipe, and the pipe (addition path) may be accommodated in a heating container (a constant temperature bath) as described later.
[0020]
In the case of adopting an addition structure by a bubbling method, the gas path from the supply source is branched into the first and second gas paths, and the addition means is a liquid raw material to be the additive component in the gas phase. A bubbling tank in which the downstream end of the first gas path faces the liquid raw material, an addition path extending from the bubbling tank and joining the second gas path, and the first and second processing gases. It is desirable to include a diversion ratio adjusting unit that adjusts the diversion ratio to the two gas passages so that the numerical range of addition (0.5 to 2.5 vol%) is satisfied. As a result, the amount added can be controlled to be surely within the above numerical range.
[0021]
Further, as a bubbling method, the carrier gas may be bubbled through the liquid raw material and then merged (mixed) with the processing gas. As carrier gas, O₂Or N₂Or a noble gas can be used. For example, O as carrier gas₂When this is used, it is involved in the reaction in the plasma etching apparatus as described above by being mixed into the processing gas together with the additive component. Such a carrier gas also functions as one component (additional component) of the processing gas.
[0022]
As an addition method using a thermostatic bath, the addition means includes a liquid storage part storing a liquid raw material to be an additive component of the gas phase, and an additive component vaporized from the liquid storage part in the numerical range (0.5 to 2.5 vol%), an addition amount control unit that makes the flow rate to satisfy, an addition path that extends from the addition amount control unit and merges with the gas path from the supply source, the liquid storage unit and the addition amount control unit, and It is desirable to provide a container (constant temperature bath) that accommodates the full length region including the junction portion of the addition path, and the inside of the container is maintained at a temperature higher than the vaporization temperature of the liquid raw material. As a result, it is possible to reliably prevent the additive component from the additive amount control unit from being liquefied before joining the processing gas, and to ensure that the additive component addition amount (flow rate ratio) is within the above range. As a result, a high etching rate and a selective etching property of silicon oxide can be reliably ensured. Here, the addition means may be configured to pass only the additive component through the addition path.₂Or the like (or an additional component of the processing gas also serving as a carrier gas) may be passed through the addition path.
[0023]
  A gas supply apparatus according to the present invention is a gas supply apparatus to a plasma etching apparatus that performs plasma etching on a workpiece having silicon oxide to be etched and a metal that should not be etched under the vicinity of atmospheric pressure,
A processing gas supply source containing a halogen-based main gas, and means for adding an additive component consisting of water or a hydroxyl group-containing compound,
A processing gas path is connected to the above supply source,
The addition means has an addition path for passing the additive component in the gas phase and merging with the processing gas path,
At the junction of the processing gas path and the addition path, the processing gas from the processing gas path and the gas phase additive component from the addition path merge, and the processing gas excluding the additive component A processing gas to which the additive component is added in an amount of 0.5 to 2.5 vol% is obtained, and the combined processing gas is supplied to the plasma etching apparatus,
  In the junction, the aboveprocessingGas passageChannel cross-sectional areaWhenthe aboveChannel cross-sectional area of addition channelWithThe ratio isThe gas flow rate in the processing gas path and the gas flow rate in the addition pathAbout equal to ratioIt is characterized by that.
Accordingly, the gas flow velocities of the processing gas passage and the addition passage that merge with each other can be made substantially equal, and the additive component can be smoothly mixed with the processing gas from the processing gas passage.
The adding means further includes a bubbling tank that stores the added component in a liquid state, and a diversion ratio adjusting unit, and a branch path branches from the processing gas path, and a downstream end of the branch path is the bubbling tank The flow rate adjusting unit adjusts the flow rate ratio of the gas from the supply source to the branch path to adjust the numerical value range (0.5 to 2.5 vol%). The addition path extends from the bubbling tank, and a gas mixture from the branch path and an additive component vaporized in the gas is passed through the addition path, and the flow path cross-sectional area ratio is However, the ratio of the flow rate of the processing gas in the processing gas passage between the branching portion of the branching passage and the junction portion may be substantially equal to the flow rate of the mixed gas in the addition passage.
The addition means stores the liquid storage portion in which the addition component is stored in a liquid state, and the addition component vaporized without being mixed with the other components of the processing gas from the liquid storage portion (0) 0.5 to 2.5 vol%) and a container for accommodating the addition amount control unit to be sent to the addition path, the liquid storage unit, the addition amount control unit, the addition path, and the junction. Further, the inside of the container may be maintained at a temperature higher than the vaporization temperature of the additive component.
In the case where only the additive component is passed through the addition path without using the carrier gas, the flow rate ratio between the processing gas path and the addition path is set to 100: r (0.5 ≦ r ≦ 2.5) by the addition amount control unit. Therefore, if the flow path cross-sectional area of the processing gas path is 100, the flow path cross-sectional area of the addition path is set to be substantially the above r.
[0024]
In the junction, in the downstream of one of the gas passages (“gas passage from the supply means” in the addition method using the thermostatic bath, “second gas passage” in the bubbling method) and the addition passage (preferably the addition passage). The end is accommodated inside the other path (preferably a gas path) so as to be coaxial with the other path and open in the downstream direction of the other path. It is desirable that the processing gas paths are connected in a straight line. Accordingly, the mixing can be performed more smoothly, the gas can be prevented from staying around the joining portion, and reliquefaction due to the stay can be reliably prevented. As a result, the flow rate ratio of the additive component in the processing gas after the addition can be more reliably within the range of 0.5 to 2.5 vol%. As a result, a high etching rate and a selective etching property of silicon oxide can be ensured more reliably.
[0025]
The substantially normal pressure (pressure near atmospheric pressure) in the present invention is 1.333 × 10.^Four~ 10.664 × 10^FourSays the range of Pa. Among them, 9.331 × 10^Four~ 10.397 × 10^FourThe range of Pa is preferable because pressure adjustment is easy and the apparatus configuration is simple.
[0026]
The normal pressure plasma etching apparatus includes a processing unit (discharge device) that generates a plasma space under normal pressure (pressure condition near atmospheric pressure). The processing unit is provided with a pair of electrodes for forming a plasma space. A discharge plasma is generated by applying an electric field between the pair of electrodes. The discharge form is preferably glow discharge, but may be corona discharge, creeping discharge, or arc discharge.
[0027]
The pair of electrodes may have a parallel plate type counter electrode structure or a coaxial cylindrical electrode structure, and a combination of a roll electrode and a plate electrode, or a roll electrode and a curved plate electrode having a circular arc section along the roll electrode. There may be. Examples of the material of the electrode include simple metals such as iron, copper, and Al, alloys such as stainless steel and brass, and intermetallic compounds. The electrodes preferably have a structure in which the distance between the plasma spaces (between the electrodes) is constant in order to avoid occurrence of arc discharge due to electric field concentration.
[0028]
At least one of the pair of electrodes needs to have a solid dielectric disposed on the surface facing the other electrode. It is preferable that the solid dielectric is in close contact with the one electrode and completely covers the facing surface. If there is a portion where the electrodes directly face each other without being covered by the solid dielectric, arc discharge is likely to occur therefrom.
[0029]
The solid dielectric may be in the form of a sheet or film, or a film coated on the electrode surface by a thermal spraying method. The thickness of the solid dielectric is preferably 0.01 to 4 mm. If the solid dielectric is too thick, a high voltage may be required to generate discharge plasma, and if it is too thin, dielectric breakdown may occur when a voltage is applied, and arc discharge may occur.
[0030]
The material of the solid dielectric may be either organic or inorganic. For example, plastic such as polytetrafluoroethylene and polyethylene terephthalate, glass, metal oxide such as silicon dioxide, aluminum oxide, zirconium dioxide, and titanium dioxide, titanium Examples include double oxides such as barium acid.
[0031]
The relative dielectric constant of the solid dielectric is preferably 2 or more (25 ° C. environment, the same applies hereinafter). Specific examples of the solid dielectric having a relative dielectric constant of 2 or more include polytetrafluoroethylene, glass, and metal oxide film. Further, in order to stably generate a high density discharge plasma, it is preferable to use a solid dielectric having a relative dielectric constant of 10 or more. The upper limit of the relative dielectric constant is not particularly limited, but an actual material of about 18,500 is known. Examples of the solid dielectric having a relative dielectric constant of 10 or more include a metal oxide film mixed with 5 to 50% by weight of titanium oxide and 50 to 95% by weight of aluminum oxide, or a metal oxide film containing zirconium oxide. Can be mentioned.
[0032]
In the present invention, the distance between the electrodes is appropriately determined in consideration of the thickness of the solid dielectric, the magnitude of the applied voltage, the purpose of using plasma, etc., but is preferably 0.1 to 5 mm. If the distance between the electrodes is less than 0.1 mm, the gap may be too narrow and installation may be difficult. On the other hand, if it exceeds 5 mm, it is difficult to generate uniform discharge plasma. If it is the range of 0.5-3 mm, the stable discharge will be obtained and it is more preferable.
[0033]
An electric field such as a high frequency, a pulse wave, or a microwave is applied between the electrodes, but a pulse electric field is preferably applied. In particular, a pulse electric field having a rise time and / or a fall time of 10 μs or less is preferable. If it exceeds 10 μs, the discharge state tends to shift to an arc and becomes unstable, and it becomes difficult to maintain a high-density plasma state. The shorter the rise time and fall time, the more efficiently the ionization of the gas during plasma generation, but it is practically difficult to make it less than 40 ns. A more preferable range of the rise time and the fall time is 50 ns to 5 μs. Here, the rise time is a time during which the voltage (absolute value) continuously increases, and the fall time is a time during which the voltage (absolute value) continuously decreases.
[0034]
The electric field strength of the pulse electric field is preferably 10 to 1000 kV / cm, and more preferably 20 to 300 kV / cm. When the electric field strength is less than 10 kV / cm, it takes too much time for processing, and when it exceeds 1000 kV / cm, arc discharge tends to occur.
[0035]
The frequency of the pulse electric field is preferably 0.5 kHz or more. If it is less than 0.5 kHz, the plasma density is low, and the process takes too much time. The upper limit is not particularly limited, and may be 13.56 MHz which is commonly used, or may be a high frequency band such as 500 MHz which is used experimentally. In consideration of ease of matching with the load and handling, 500 kHz or less is preferable. By applying such a pulse electric field, the processing speed can be greatly improved.
[0036]
Moreover, it is preferable that one pulse duration in the said pulse electric field is 200 microseconds or less, and 3-200 microseconds is more preferable. If it exceeds 200 μs, it tends to shift to arc discharge. Here, one pulse duration means a continuous ON time of one pulse in a pulse electric field composed of repetition of ON / OFF.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an atmospheric pressure plasma etching system S1 according to the first embodiment of the present invention. The atmospheric pressure plasma etching system S1 includes an atmospheric pressure plasma etching gas supply device M1 and an atmospheric pressure plasma etching device 30 connected to the supply device M1. For example, an electronic device such as a SAW filter F is subject to etching ( Workpieces and workpieces). As is well known, the SAW filter F is made of quartz (SiO 2₂A comb-shaped metal pattern made of Al or the like is formed on the substrate made of The atmospheric pressure plasma etching system S1 is a SiO 2 of the SAW filter F under normal pressure.₂Is selectively etched.
[0038]
The atmospheric pressure plasma etching apparatus 30 of the system S1 includes a nozzle head 39 (electrode holder). As shown in FIG. 2, the nozzle head 39 includes a coaxial cylindrical electrode structure including a cylindrical outer electrode 31 and a columnar inner electrode 32 housed in the outer electrode 31. The opposing surfaces of these electrodes 31 and 32 are each covered with a solid dielectric (not shown). A power source 33 (electric field applying means) is connected to the inner electrode 32, and the outer electrode 31 is grounded. Thereby, the inner electrode 32 becomes an electric field application electrode (hot electrode), and the outer electrode 31 becomes a ground electrode (earth electrode). The polarities of the electrodes 31 and 32 may be reversed.
[0039]
An annular plasma space 30 a is formed between the outer electrode 31 and the inner electrode 32. A gas introduction port 30b is provided at the upper end portion (one end side of the plasma space 30a) of the outer electrode 31, and a gas outlet (nozzle port) 30c is provided at the lower end portion (the other end side). The SAW filter F to be processed is disposed below the gas outlet 30c.
The electrode structure is not limited to the coaxial cylindrical type, and may be a parallel plate type. The setting means 38 for the SAW filter F may be in the form of a table, and the filters F may be set one by one each time processing is performed. You may be able to send sequentially.
[0040]
The atmospheric pressure plasma etching gas supply device M1 of the system S1 will be described.
The gas supply device M1 includes a processing gas supply unit 1 and a humidification unit 2 (addition unit). The processing gas supply means 1 includes a plurality of gas storage portions (“processing gas supply sources” in the claims) separately storing a main gas and an additional gas constituting the processing gas. The humidification pretreatment gas pipe 5A (treatment gas path before the addition operation) is sent out at a flow rate. The main gas (etchant) that is the main component of the processing gas includes a halogen-based gas (for example, CF_Four) Is used. As an additional gas as an additional component of the processing gas, for example, O₂Is used. CF_FourAnd O₂The flow rate ratio of, for example, CF_Four: O₂= 3: 1. O₂That is, the additional gas is not essential for causing a plasma reaction for etching, and may not be included as a component of the processing gas.
[0041]
The humidifying means 2 has a water supply source 2X and an addition amount control unit 2Y. The water supply source 2X stores liquid phase water (a liquid raw material for a gas phase additive component). The water supply source 2X evaporates this water and sends it to the addition amount control unit 2Y.
[0042]
The addition amount control unit 2Y performs control so that the flow rate of water vapor (gas phase additive component) from the water supply source 2X becomes a predetermined value. This predetermined flow rate is set within a range of 0.5 to 2.5 vol% with respect to the processing gas from the supply means 1. Although this flow rate ratio is precisely relative to the processing gas excluding the water vapor (processing gas before humidification or addition operation), since it is a trace amount, the entire processing gas containing the water vapor (hereinafter referred to as “ It can be used for “humidified gas”. The flow rate can be controlled by controlling the dew point temperature based on the detected value of the dew point meter. An addition pipe 2C extends from the addition amount control unit 2Y. A ribbon heater 2H (tube heating means) is wound around the entire circumference of the addition tube 2C. The addition pipe 2C is joined to the pre-humidification gas pipe 5A.
[0043]
A humidified gas supply pipe 5B extends from this junction. The humidified gas supply pipe 5B is provided with a heater 5H (pipe heating means). The downstream end of the humidified gas supply pipe 5B is connected to the gas inlet 30b of the atmospheric pressure plasma etching apparatus 30.
[0044]
A method of etching the SAW filter F by the atmospheric pressure plasma etching system S1 having the above configuration will be described.
Processing gas (CF_Four+ O₂) Is sent from the supply means 1 to the pre-humidified gas pipe 5A. On the other hand, water vapor (H₂O) is added to the humidification pretreatment gas (CF) by the addition amount control unit 2Y._Four+ O₂) With respect to the predetermined flow rate ratio (0.5 to 2.5 vol%). The water vapor after the flow rate adjustment passes through the addition pipe 2C. At this time, since the addition pipe 2C is heated by the heating means 2H, it is possible to prevent water vapor from condensing (reliquefaction) on the inner surface of the addition pipe 2C. As a result, the flow rate ratio of water vapor can be reliably maintained at the predetermined value. Water vapor that has passed through the addition tube 2C is treated gas (CF) from the tube 5A._Four+ O₂) And added. As a result, the humidification gas (CF_Four+ O₂+ Small amount of H₂O), ie “addition post-treatment gas”.
[0045]
The humidification treatment gas is passed through the humidification gas supply pipe 5B. The tube 5B is heated by the heater 5H over its entire length. Thereby, it is possible to reliably prevent moisture in the humidification treatment gas from condensing on the inner surface of the tube 5B. As a result, the flow rate ratio of water vapor can be more reliably maintained at the predetermined value (0.5 to 2.5 vol%).
[0046]
Then, the humidification treatment gas is guided to the atmospheric pressure plasma etching apparatus 30 and is introduced into the plasma space 30a from the gas introduction port 30b of the nozzle head 39. On the other hand, an electric field (pulse electric field) is applied to the plasma space 30a by the power source 33, and glow discharge plasma (normal pressure plasma) is generated. As a result, the processing gas is discharged (plasmaized). That is, CF_Four, O₂And H₂COF from processing gas consisting of O₂, F₂, HF, OH^*Etc., and F^-, HF^2-, F^*Ions and radicals (active species) are generated.
[0047]
The discharge-treated (plasmaized) processing gas is blown out from the gas outlet 30c toward the upper surface (surface to be processed) of the SAW filter F. As a result, the ions and radicals are converted into SiOW of the SAW filter F.₂Reacts with volatile SiF_FourAnd H₂SiF₆Occurs. As a result, the SAW filter F SiO₂Can be etched. Since the water vapor in the processing gas is adjusted to be 0.5 vol% or more, the etching rate can be reliably increased and the etching process can be performed efficiently. In addition, since the water vapor in the processing gas is adjusted to 2.5 vol% or less, the metal pattern of the SAW filter F can be prevented from being damaged, and the SiO 2 can be surely removed.₂Only can be selectively etched. As a result, a good quality SAW filter F can be obtained.
[0048]
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 in the above-described embodiments, and the description will be simplified.
FIG. 3 shows an atmospheric pressure plasma etching system S2 according to the second embodiment of the present invention. This system S2 includes an atmospheric pressure plasma etching apparatus 30 and an atmospheric pressure plasma etching gas supply apparatus M2. Since the atmospheric pressure plasma etching apparatus 30 has the same configuration as that of the first embodiment, description thereof is omitted.
[0049]
The atmospheric pressure plasma etching gas supply device M2 of the system S2 employs a bubbling method as an adding means.
More specifically, the atmospheric pressure plasma etching gas supply device M2 includes a main gas supply unit 10X and a humidification unit 12A (addition unit). The main gas supply means 10 </ b> X includes a main gas tank 11 (main gas supply source) and a main gas mass flow controller (hereinafter referred to as “MFC”) 14. The main gas tank 11 contains CF as a halogen-based main gas which is a main component of the processing gas._FourIs stored. A main gas MFC 14 is connected to the tank 11. The MFC 14 is the main gas from the tank 11, that is, CF_FourIs weighed to achieve the desired flow rate. A main gas pipe 54 extends from the MFC 14.
[0050]
The humidifying means 12A of the gas supply device M2 includes a carrier tank 13A, a carrier MFC 15A, and a bubbling tank 17. The carrier tank 13A has, for example, O as carrier gas.₂Is stored. A carrier MFC 15A is connected to the tank 13A. The MFC 15A is a carrier gas from the tank 13A, that is, O₂The mass of the gas is measured to obtain a desired flow rate. A carrier introduction pipe 53 extends from the MFC 15A.
Carrier gas (O₂) Is finally the main gas (CF_FourAnd an additional component (additional gas) of the processing gas by being involved in the reaction in the atmospheric pressure plasma etching apparatus 30. Main gas (CF_Four) And carrier gas (O₂) Constitutes a “processing gas excluding added components”. These gas tanks 11 and 13A constitute a “processing gas supply source” in the claims.
[0051]
The bubbling tank 17 stores liquid phase water (liquid raw material of additive components). A carrier introduction tube 53 is inserted into the water. The downstream end of the carrier introduction pipe 53 is open in the water of the tank 17. An addition pipe 52 extends from the upper end of the bubbling tank 17 (above the water surface). A ribbon heater 2H for preventing condensation similar to that of the first embodiment is wound around the outer circumference of the addition pipe 52 over the entire length. The addition pipe 52 is joined to the main gas pipe 54 of the main gas supply means 10X. A humidified gas supply pipe 51 extends from this junction and is connected to the gas inlet 30 b of the atmospheric pressure plasma etching apparatus 30. The humidified gas supply pipe 51 is provided with a heater 5H.
[0052]
According to the gas supply device M2 of the atmospheric pressure plasma etching system S2, the main gas (CF_Four) Is sent from the tank 11 to the MFC 14 and weighed, and sent to the pipe 54 at a predetermined flow rate. Carrier gas (O₂) Is sent from the tank 13A to the MFC 15A, measured, and sent to the pipe 53 at a predetermined flow rate. This carrier gas is blown into the water in the bubbling tank 17 and bubbled, and water evaporates in the bubbles of the carrier gas. The carrier gas containing the water vapor (gas phase additive component) is merged with the main gas from the pipe 54 via the addition pipe 52. Thereby, water vapor is added to the main gas. This water vapor addition amount is adjusted to be 0.5 to 2.5 vol% with respect to the total flow rate of the main gas and the carrier gas (processing gas flow rate excluding water vapor). Thus, the humidification gas (CF_Four+ O₂+ Small amount of H₂O) is obtained. The humidified gas is supplied to the atmospheric pressure plasma etching apparatus 30 through the humidified gas supply pipe 51 to be converted into plasma, and is sprayed onto the SAW filter F. As a result, the SiO 2 of the SAW filter F can be selectively etched at a high etching rate, as in the first embodiment.
[0053]
FIG. 4 shows an atmospheric pressure plasma etching system S3 according to the third embodiment of the present invention. The system S3 includes an atmospheric pressure plasma etching apparatus 30 and an atmospheric pressure plasma etching gas supply apparatus M3. Since the atmospheric pressure plasma etching apparatus 30 has the same configuration as that of the above-described embodiment, the description thereof is omitted.
[0054]
  The atmospheric pressure plasma etching gas supply device M3 of the system S3 employs a more desirable mode of the bubbling method as the adding means.
  More specifically, the atmospheric pressure plasma etching gas supply device M3 includes a processing gas supply means 10 (processing gas source) and a humidification means 12 (addition means). The processing gas supply means 10 includes two processing gas component tanks 11 and 13 and two processing gas component MFCs 14 and 15. The main gas tank 11 contains a halogen-based main gas (CF) which is the main component of the processing gas.₄) Is stored, and the main gas MFC 14 (main gas flow rate control unit) measures the mass of the main gas from the tank 11 to obtain a desired flow rate, as in the second embodiment. The additional gas tank 13 has an additional gas (O) as an additional component of the processing gas.₂) And the additional gas MFC15 (additional gas flow rate control unit) measures the mass of the additional gas from the tank 13 to obtain a desired flow rate in the carrier tank 13A and the MFC 15A of the second embodiment. It is the same. The pipes from the outlet ports of the two MFCs 14 and 15 merge with each other to form one process gas pipe 50 (process gas path from the supply source) and extend from the process gas supply means 10. The processing gas pipe 50 is branched into first and second branch pipes 50a and 50b.(The branch path 50a is branched from the processing gas paths 50 and 50b.)
[0055]
The adding means 12 includes a bubbling tank 17 that stores water (liquid phase), and a branch valve 18 (a flow ratio adjusting unit) provided at a branch portion of the processing gas pipe 50. The downstream end of the first branch pipe 50a (first gas path) from the branch valve 18 is inserted into the water of the bubbling tank 17 and opened. The addition pipe 52 (addition path) from the bubbling tank 17 merges with another branch pipe 50b (second gas path) from the branch valve 18. A humidified gas supply pipe 51 (post-addition treatment gas path) extends from this junction to the atmospheric pressure plasma etching apparatus 30.
[0056]
The branch valve 18 can adjust the flow rate of the processing gas from the pipe 50 to the first branch pipe 50a and the flow rate to the second branch pipe 50b (that is, the diversion ratio of the pipes 50a and 50b). When the flow rate to the first branch pipe 50a is increased, the amount of water vaporized in the bubbling tank 17 increases. Conversely, when the flow rate to the first branch pipe 50a is reduced, the amount of water vaporized in the bubbling tank 17 is reduced. Thereby, it can set so that the amount of water vapor | steam addition to process gas may become the range of 0.5-2.5 vol% reliably. As a result, the SiO2 of the SAW filter F can be reliably selected and etched at a high etching rate.
Instead of the branch valve 18, a flow control valve is provided in each of the first and second branch pipes 50 a and 50 b or in any one of the first and second branch pipes 50 a and 50 b. Also good.
[0057]
FIG. 5 shows an atmospheric pressure plasma etching system S4 according to the fourth embodiment of the present invention. The system S4 includes an atmospheric pressure plasma etching apparatus 30 and an atmospheric pressure plasma etching gas supply apparatus M4. Since the atmospheric pressure plasma etching apparatus 30 has the same configuration as that of the above-described embodiment, the description thereof is omitted.
[0058]
The gas supply apparatus M4 for atmospheric pressure plasma etching of the system S4 employs the vaporizer 20 as an adding means (humidifying means).
More specifically, the atmospheric pressure plasma etching gas supply apparatus M4 includes a processing gas supply means 10 (processing gas source) and an addition means connected to the supply means 10, that is, a vaporizer 20. The processing gas supply means 10 includes two processing gas component tanks 11 and 13 and two processing gas component MFCs 14 and 15. The main gas tank 11 contains a halogen-based main gas (CF) which is the main component of the processing gas._Four) Is stored, and the main gas MFC 14 measures the mass of the main gas from the tank 11 to obtain a desired flow rate, as in the second and third embodiments. The additional gas tank 13 has an additional gas (O) as an additional component of the processing gas.₂) Is stored, and the additional gas MFC 15 measures the mass of the additional gas from the tank 13 to obtain a desired flow rate, as in the third embodiment. The pipes from the outlet ports of the two MFCs 14 and 15 merge with each other, and the gas pipe 50 after the merging and mixing is connected to the inlet port 21 described later of the vaporizer 20._INIt is linked to.
[0059]
The vaporizer 20 as the adding means includes a thermostatic chamber 21 (container), a water storage tank 22 (liquid storage unit) and a water vapor MFC 23 (addition amount control unit) accommodated in the thermostatic chamber 21. The thermostatic chamber 21 is thermally insulated from the outside. The constant temperature bath 21 incorporates a heater 40 (heating means in the bath). Thereby, the whole inside of the thermostatic chamber 21 is maintained at a constant temperature. This temperature is set to be higher (for example, 110 ° C.) than the vaporization temperature under normal pressure of water.
[0060]
  An inlet port 21IN for connection with the gas pipe 50 of the processing gas supply means 10 is provided on the outer surface of the thermostatic chamber 21. Inside the thermostatic chamber 21 is a pre-humidified gas pipe 25 (from a supply source) extending from the inlet port 21IN.processingGas path) is piped. An air control valve V25 is provided in the gas tube 25 before humidification.
[0061]
The water storage tank 22 in the thermostatic chamber 21 stores, for example, liquid phase pure water (liquid raw material to be added to the gas phase) having an electric conductivity of 0.1 μS / cm. In the tank 22 above the water surface, only water vapor (gas phase additive component) evaporated from water is present, and impure gas such as air is hardly contained. Inside the thermostatic chamber 21, a pre-metering steam pipe 24 extends from the upper end of the tank 22 toward the MFC 23. The steam pipe 24 has two air control valves V₂₄₁, V₂₄₂Are sequentially provided from the upstream side. Each valve V₂₄₁, V₂₄₂Ribbon heaters 41 and 42 (valve heating means) are wound around. These valves V₂₄₁, V₂₄₂A discharge pipe 29 extends from the water vapor pipe 24 between the discharge ports 21 disposed on the outer surface of the thermostatic chamber 21._EXIt is connected to. The exhaust pipe 29 has an air control valve V₂₉Is provided. A pressure sensor P is provided at the joint between the steam pipe 24 and the discharge pipe 29.₁Is provided. A purge port 21 is provided on the outer surface of the thermostatic chamber 21._PGThe purge port 21 is provided._PGA purge pipe 28 extending from the valve V₂₄₂It is connected to the steam pipe 24 on the downstream side. The purge pipe 28 includes an air control valve V.₂₈Is provided.
[0062]
The downstream end of the steam pipe 24 is connected to the inlet port of the steam MFC 23. The MFC 23 measures the mass of water vapor from the water vapor pipe 24 and thus from the water storage tank 22 to obtain a desired flow rate. Specifically, when the flow rate of the pre-humidification gas in the pre-humidification gas pipe 25 is 100, the flow rate of water vapor is adjusted to r (0.5 ≦ r ≦ 2.5).
[0063]
An addition pipe 26 (addition path, post-metering steam pipe) extends from the outlet port of the MFC 23. The downstream end of the addition pipe 26 is joined with the pre-humidified gas pipe 25. The full length region of the addition pipe 26 including the merging portion is accommodated in the thermostatic chamber 21. In addition pipe 26, air control valve V₂₆Is provided. Valve V₂₆A ribbon heater 43 (valve heating means) is wound around.
[0064]
Inside the thermostatic chamber 21, a humidified gas pipe 27 (post-treatment gas path after addition) extends from the junction of the pipes 25 and 26. The humidified gas pipe 27 is an outlet port 21 disposed on the outer surface of the thermostatic chamber 21._OUTIt is connected to. This outlet port 21_OUTA humidified gas supply pipe 51 extends from the gas inlet 30 b of the atmospheric pressure plasma etching apparatus 30. The point that the humidified gas supply pipe 51 is provided with the heater 5H is the same as in the above-described embodiment.
[0065]
The junction structure between the pipes 25 and 26 will be described in further detail.
As shown in FIG. 6, the pre-humidified gas pipe 25 and the humidified gas pipe 27 are configured by a single straight common gas pipe 20 </ b> P. The common gas pipe 20P has substantially the same cross-sectional area over the entire length. The downstream end of the addition pipe 26 is joined to the middle part of the common gas pipe 20P. The upstream side gas pipe 20P is provided as the pre-humidified gas pipe 25, and the downstream side gas pipe 20P is provided as the humidified gas pipe 27 with this joint as a boundary.
[0066]
The addition pipe 26 is much thinner than the common gas pipe 20P, that is, the gas pipe 25 before humidification. Specifically, the cross-sectional area A of the gas pipe 25 before humidification_{twenty five}Is 100, the channel cross-sectional area A of the addition pipe 26₂₆Is the same value (A) as the flow rate ratio “r” of water vapor to be adjusted by the MFC 23.₂₆= R). In FIG. 6, the diameter of the addition tube 26 is exaggerated. The addition pipe 26 penetrates the pipe wall of the common gas pipe 20P and enters the pipe 20P, and the pipe axis L of the pipe 20P._20XIt is bent in an L shape on the top. Thereby, the downstream end of the thin addition pipe 26 is coaxially formed with the thick common gas pipe 20P, and is opened toward the downstream humidified gas pipe 27 side.
[0067]
The operation of the atmospheric pressure plasma etching system S4 according to the fourth embodiment will be described with a focus on the gas supply device M4.
A purge gas such as nitrogen gas is previously purged from the purge port 21._PGThe inside of the pipes 24, 26 and the like is purged by feeding from the inside. Furthermore, the discharge port 21_EXAnd a vacuum pump is connected to suck and exhaust the unknown gas in the tank 22 and the pipes 24 and 26 above the water surface.
[0068]
Then, by turning on the heater 40, the temperature chamber 21 is heated to a desired temperature (for example, 110 ° C.) higher than the vaporization temperature of water. As a result, the water storage tank 22 and pure water therein are also heated. In this heating process, the valve V₂₄₁, V₂₉While opening valve V₂₄₂Keep closed. Thereby, the inside of the water storage tank 22 is maintained at a normal pressure. Also, the ribbon heaters 41 to 43 are turned on and the valves V of the steam pipes 24 and 26 are turned on.₂₄₁, V₂₄₂, V₂₆Are individually heated to a desired temperature (for example, 120 ° C.) higher than the internal space of the thermostatic chamber 21.
[0069]
When the inside of the thermostatic chamber 21 and the water storage tank 22 reaches equilibrium at a desired 110 ° C., the water in the tank 22 is at 100 ° C. As a result, water evaporates and vaporizes, and the inside of the tank 22 above the water surface is filled with saturated water vapor. Here, the valve V of the steam pipes 24 and 26₂₄₁, V₂₄₂, V₂₆open. (Valve V₂₈, V₂₉Is closed. Thus, saturated steam is sent from the tank 22 through the pre-metering steam pipe 24 to the MFC 23. At this time, since the steam pipe 24 is also heated to 110 ° C., water vapor does not condense (reliquefy) on the inner peripheral surface of the steam pipe 24. Furthermore, valve V₂₄₁, V₂₄₂Is heated to a higher temperature of 120 ° C.₂₄₁, V₂₄₂It is possible to reliably prevent condensation in the interior.
[0070]
In parallel, the valve V of the gas pipe 25 before humidification_{twenty five}And CF of tank 11_FourThe gas is sent to the MFC 14 and O in the tank 13₂Send gas to MFC15. At this time, the two processing gases MFC 14 and 15 of the original gas supply means 10 cooperate with each other to generate CF._FourAnd O₂The flow rate ratio is predetermined (CF_FourGas is O₂The flow rate is adjusted to 3 times the flow rate of the gas.
The steam MFC 23 is composed of these CFs._FourAnd O₂The water vapor is sent out to the addition tube 26 while adjusting the flow rate of the water vapor so that the flow rate of the water vapor is r times 100 minutes (0.5 ≦ r ≦ 2.5).
[0071]
Since the addition pipe 26 is kept at a high temperature of 110 ° C. over its entire length, water vapor does not condense on the inner peripheral surface of the addition pipe 26. As a result, the flow rate ratio of water vapor can be reliably maintained as it is. Furthermore, valve V₂₆Is heated to a higher temperature of 120 ° C.₂₆Condensation does not occur inside, and the accuracy of the flow rate ratio of water vapor can be further increased.
[0072]
Then, the water vapor flows into the pipe 20 </ b> P and merges with the humidified pretreatment gas from the pipe 25. At this time, the flow rate of water vapor coming out of the tube 26 is equal to the flow rate of the humidification pretreatment gas outside the tube 20P due to the relationship between the flow rate ratio and the flow path cross-sectional area of the tubes 25 and 26. Thereby, water vapor can be stably mixed with the processing gas. Moreover, since the downstream end opening of the addition pipe 26 faces the humidified gas pipe 27 on the downstream side, the steam flux φ₁Is the gas flux φ of the humidified gas pipe 27₂It can be absorbed more smoothly by being sucked into the inside. Furthermore, since the downstream end of the addition pipe 26 is accommodated coaxially in the common gas pipe 20P, water vapor can be mixed more uniformly. Thereby, it is possible to prevent the water vapor from locally staying around the joining portion, and it is possible to reliably prevent the condensation of water vapor due to the stay.
[0073]
As a result, it is possible to obtain a highly accurate humidification gas (post-treatment gas). This humidified gas is passed through the humidified gas pipe 27 and the gas supply pipe 51. Since the water vapor partial pressure in the humidified gas gas is extremely small, no condensation occurs on the tubes 27 and 51. Then, as in the first embodiment, the humidification processing gas is supplied to the atmospheric pressure plasma etching apparatus M3 to be turned into plasma and sprayed onto the surface to be processed of the SAW filter F. As a result, it is possible to efficiently etch only SiO 2 at a high etching rate, and to obtain a high-quality SAW filter F.
[0074]
According to the vaporizer 20, since the heating means for vaporization in the water storage tank 22 and the heating means for preventing condensation in the pipes 24 and 25 are constituted by the common heater 40, the number of parts can be reduced. In addition, the configuration can be simplified.
[0075]
The present invention is not limited to the above embodiment, and various modifications can be made.
For example, a gas phase hydroxyl group-containing compound (for example, alcohol) may be used as an additive component instead of water vapor, that is, gas phase water. Also in this case, the addition amount of the gas phase hydroxyl group-containing compound is set to 0.5 to 2.5 vol% of the processing gas.
The atmospheric pressure plasma etching apparatus 30 is a so-called remote system in which the workpiece is disposed outside the plasma space between the electrodes, but a so-called direct-type atmospheric pressure in which the workpiece is disposed in the plasma space between the electrodes. A plasma etching apparatus may be used.
Naturally, the object to be processed is not limited to the SAW filter.₂A multilayer laminated device in which a via hole is to be formed in a layer and other various electronic devices can be processed.
In the third embodiment, the structure of the joining part of the second branch pipe 50b and the addition pipe 52 is the same as the structure of the joining part of the pre-humidification gas pipe 25 and the addition pipe 26 of the fourth embodiment shown in FIG. It may be configured.
In the fourth embodiment, the addition means (vaporizer 20) is configured to pass only the additive component made of water vapor through the addition tube 26.₂Or the like, and may be passed through the addition pipe 26 on a carrier gas (an additional component of the processing gas).
[0076]
【Example】
Examples of the present invention will be described.
<Example 1>
Using a system similar to FIG.₂It was investigated what change was observed in the gas component of the plasma space by the addition of O). The measurement was based on Fourier transform infrared spectroscopy (FT-IR). The results are shown in FIG. As is apparent from the figure, OH is added by adding water.^*As a result, the oxidation action was improved and the F source increased.
[0077]
<Example 2>
Etching was performed using the same system as in FIG. 5 under the following conditions.
[Processing conditions]
Etching environment: ambient temperature 24.8 ° C., relative humidity 24% Rh
Target: Crystal (SiO₂) SAW filter with Al pattern formed on the substrate
Process gas components and flow rate: CF_Four= 30 ccm, O₂= 10ccm
Water addition amount: CF_FourAnd O₂1.5 vol% with respect to the total flow rate (= 40 ccm)
Gas supply pipe temperature: 50 ° C
Discharge condition: Applied voltage V_pp= 9 kV, pulse frequency = 20 kHz
Processing time: 20 sec
Result, SiO₂The etching rate was 80 nm / min. There was no damage to the Al pattern.
[0078]
<Example 3>
Using the system of FIG.₂Depending on the amount of addition of O)₂It was investigated how the etching rate changed. The etching environment, processing target, processing gas component and flow rate, discharge conditions, and processing time were the same as in Example 2, and the gas supply tube temperature was set to a little over 100 degrees. In addition, the flow path cross-sectional area ratio in the junction part of the pipes 25 and 26 was made constant irrespective of the gas flow rate ratio in these pipes.
The results are shown in FIG. The etching rate rose around the addition amount of 0.5 vol%, and the etching rate increased as the addition amount increased. However, when the added amount exceeds 2.5 vol%, the Al pattern is damaged.
[0079]
Subsequently, water vapor (H₂The frequency characteristics of the SAW filter were examined in the case of etching with the addition amount of O) of 2.0 vol% and the case of etching with 3.0 vol%. The results are shown in FIG. 9 and FIG. In these figures, the broken line is the frequency characteristic before etching, and the solid line is the frequency characteristic after etching. As shown in FIG. 9, when the addition amount was 2.0 vol%, the center frequency could be shifted without destroying the characteristic waveform. This is because the substrate quartz (SiO₂) Is the proof that only selective etching was possible. On the other hand, as shown in FIG. 10, when the addition amount is 3.0 vol%, the waveform is broken and the function as a filter cannot be maintained. This is evidence that the Al pattern has been damaged.
[0080]
<Comparative Example 1>
Etching was performed under the same conditions as in Example 2 except that the same system as in FIG. 4 was used and the amount of water vapor added was 0.2 vol%. As a result, the Al pattern was not damaged, but the etching rate was 1 nm / min or less, and measurement was difficult.
[0081]
<Comparative example 2>
In Comparative Example 1, the etching was performed while changing the water vapor addition amount to 15 vol%. As a result, the etching rate was 100 nm / min, but the Al pattern was damaged and became defective.
[0082]
【The invention's effect】
As described above, according to the present invention, the etching process can be efficiently performed at a good etching rate. In addition, the silicon oxide to be etched can be selectively etched reliably, and the metal that should not be etched can be prevented from being damaged.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an atmospheric pressure plasma etching system according to a first embodiment of the present invention.
FIG. 2 is a side sectional view schematically showing an electrode structure of the system.
FIG. 3 is a schematic configuration diagram of an atmospheric pressure plasma etching system according to a second embodiment of the present invention.
FIG. 4 is a schematic configuration diagram of an atmospheric pressure plasma etching system according to a third embodiment of the present invention.
FIG. 5 is a schematic configuration diagram of an atmospheric pressure plasma etching system according to a fourth embodiment of the present invention.
FIG. 6 is a cross-sectional view of a joining portion of a gas pipe and a steam pipe in the system of the fourth embodiment.
FIG. 7 is a graph showing measurement results of the effect of water addition according to Example 1 of the present invention.
FIG. 8 is a graph showing the measurement result of the etching rate with respect to the amount of water vapor added according to Example 3 of the present invention.
FIG. 9 is a graph showing frequency characteristics of a SAW filter processed with a water vapor addition amount of 2.0 vol%.
FIG. 10 is a graph showing frequency characteristics of a SAW filter processed with a water vapor addition amount of 3.0 vol% as a comparative example.
[Explanation of symbols]
S1, S2, S3, S4 atmospheric pressure plasma etching system
M1, M2, M3, M4 Gas supply equipment for atmospheric pressure plasma etching
30 Atmospheric pressure plasma etching equipment
Process gas supply means including 1X process gas supply source
11, 13 Gas tank (Supply source of processing gas)
2,12,12 Humidification means (addition means)
17 Bubbling tank
18 Branch valve (Diversion ratio adjuster)
20 Vaporizer (addition means)
21 Thermostatic bath (container)
22 Water storage tank (liquid storage part)
23 Water vapor MFC (addition control unit)
25 Gas tube before humidification in the vaporizer (from the source)processingGas path)
26 Addition pipe (addition path)
27 Humidification gas pipe (addition post-treatment gas path)
50 Process gas pipe (from source)processingGas path)
50a First branch pipe (first gas passage, Branch)
50b Second branch pipe (second gas passage, Process gas path between branch and merge)

Claims (5)

A gas supply device to a plasma etching apparatus for plasma etching a workpiece having silicon oxide to be etched and a metal not to be etched under atmospheric pressure ,
A processing gas supply source containing a halogen-based main gas, and means for adding an additive component consisting of water or a hydroxyl group-containing compound,
A processing gas path is connected to the above supply source,
The addition means has an addition path for passing the additive component in the gas phase and merging with the processing gas path,
At the junction of the processing gas path and the addition path, the processing gas from the processing gas path and the gas phase additive component from the addition path merge, and the processing gas excluding the additive component A processing gas to which the additive component is added in an amount of 0.5 to 2.5 vol% is obtained, and the combined processing gas is supplied to the plasma etching apparatus,
In the junction, the ratio of the cross-sectional area of the processing gas path to the cross-sectional area of the addition path is substantially equal to the ratio of the gas flow rate in the processing gas path and the gas flow rate in the addition path. A gas supply apparatus for plasma etching characterized by the above. The adding means further includes a bubbling tank that stores the added component in a liquid state, and a diversion ratio adjusting unit, and a branch path branches from the processing gas path, and a downstream end of the branch path is the bubbling tank The diversion ratio adjusting unit is arranged in the liquid in the inside so that the numerical range of the addition is satisfied by adjusting the diversion ratio of the gas from the supply source to the branch path, and from the bubbling tank to the above An addition path extends, and a gas mixture from the gas from the branch path and the additive component vaporized in the gas is passed through the addition path.
The flow path cross-sectional area ratio is substantially equal to the ratio between the flow rate of the processing gas in the processing gas path between the branching portion of the branching path and the merging portion and the flow rate of the mixed gas in the addition path. The gas supply apparatus for plasma etching according to claim 1 . The addition means stores a liquid storage part that stores the additive component in a liquid state, and an additive component that is vaporized from the liquid storage part without being mixed with other components of the processing gas.
An addition amount control unit that sends to the addition channel at a flow rate that should satisfy the numerical value range of addition, and further includes a container that accommodates the liquid storage unit, the addition amount control unit, the addition channel, and the merging unit. The gas supply apparatus for plasma etching according to claim 1, wherein the inside of the container is maintained at a temperature higher than the vaporization temperature of the additive component . A system for plasma etching a workpiece having silicon oxide to be etched and a metal that should not be etched under atmospheric pressure,
A gas supply device and a plasma etching device;
The gas supply device includes a supply source of a processing gas containing a halogen-based main gas and a means for adding a hydroxyl group-containing compound, and the addition means gasses the hydroxyl group-containing compound to the treatment gas from the supply source. In addition, 0.5 to 2.5 vol% is added to the processing gas excluding the hydroxyl group-containing compound, and the processing gas after the addition is supplied to the plasma etching apparatus to be converted into plasma. Plasma etching system . A method of plasma etching a workpiece having silicon oxide to be etched and a metal not to be etched under atmospheric pressure,
A feature is that a hydroxyl group-containing compound is added in a gas phase in an amount of 0.5 to 2.5 vol% with respect to a processing gas containing a halogen-based main gas, and the processing gas after the addition is supplied to a plasma etching apparatus to form plasma. A plasma etching method .

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