JP5956299B2 - Manufacturing method of fine structure - Google Patents

Description

  The present invention relates to a method of manufacturing a microstructure having a movable part and a movable space that constitute a MEMS or the like.

  2. Description of the Related Art MEMS (Micro Electro Mechanical System) technology has been developed that produces a fine structure on a semiconductor substrate such as silicon or an insulator substrate such as glass. MEMS are being used in various fields such as various sensor fields, medical fields, and wireless communication fields.

  As an example of MEMS, it has been known that a MEMS switch having a fine switch structure manufactured by a micromachine technique obtains excellent characteristics as a high-frequency switch (see Non-Patent Document 1). This MEMS switch includes a fixed electrode and a movable electrode separated by a space. An electric switch operation is realized by displacing the movable electrode by an electrostatic force or the like, bringing the contact electrode fixed to the movable electrode into contact with the fixed electrode, and separating them. In such a MEMS switch, a low-resistance metal material or the like is used for the electrode in order to obtain a low loss. Further, it is required that the metal surface having a low resistance is exposed at a portion where the electrode contacts.

  The microstructure having a space between the electrodes as described above is generally formed by forming two electrodes spaced apart from each other using a sacrificial layer and then removing the sacrificial layer. Specifically, a sacrificial layer is formed on the lower electrode, an electrode is further formed thereon, and then the sacrificial layer is removed. By performing these processes, it is possible to form two electrode structures that are spaced apart from each other. As a material for the sacrificial layer, an organic resin is widely used. This is because the organic resin can be formed at a low temperature and can be easily patterned.

  As a method for removing the sacrificial layer made of the organic resin, the sacrificial layer is generally exposed to active oxygen and ashed. Specifically, there is a method of ashing by oxygen plasma irradiation (see Non-Patent Document 2). Further, there is a method of ashing by exposing the sacrificial layer to an ozone atmosphere while heating (see Patent Document 1).

  However, when the sacrificial layer is removed by these methods, polymer film or fine particles remain as a residue on the surface of the microstructure, impairing the mechanical operation of the microstructure, and increasing the contact resistance of the metal surface. The problem of letting it occur. The residue after ashing is, for example, silicon suboxide and the like, and is considered to be mainly derived from an adhesion aid added to improve the adhesion between the organic resin and the substrate.

As a method for removing the sacrificial layer while reducing the generation of residue by dry treatment so that the generation of the residue after ashing does not occur, for example, a mixed gas of oxygen gas and fluorocarbon gas is used. A method of performing plasma treatment is conceivable. In this treatment, fluorine radicals and the like are generated in addition to active oxygen, so that there is an advantage that silicon oxide remaining as a residue can be removed.

  However, the generation of fluorine radicals may cause chemical and physical damage due to excessive oxidation, etching, or the like on a fine structure made of an inorganic material. For this reason, it is not easy to apply the method of performing plasma treatment using a mixed gas of oxygen gas and fluorocarbon gas to the production of a fine structure.

  A processing method for removing the sacrificial layer by plasma processing using a mixed gas comprising an oxidizing gas, a fluorocarbon-based gas, and a reducing gas as a plasma species in order to prevent excessive oxidation and etching of such a fine structure. Has been proposed (see Patent Document 2). In this method, first, it becomes possible to remove the sacrificial layer without generating a residue due to fluorine radicals supplied from a fluorocarbon-based gas, and it is possible to prevent hindering the operation of the structure due to the residue. it can. In addition, since the sacrificial layer can be removed while reducing the oxidation of the fine structure with the reducing gas, the contact resistance of the electrode surface of the fine structure can be prevented from increasing due to damage such as oxidation. There is an advantage.

JP 2002-219695 A JP 2011-245565 A

G.M.Rebeiz and J.B.Muldavin, "RF MEMS switches and switch circuits", IEEE Microwave Magazine, Vol.2, No.4, pp.59-70, 2001. D. Hah, E. Yoon, and S. Hong, "A low-voltage actuated micromachinedmicrowave switch using torsion springs and leverge", IEEE Trans. Microwave Theory and Techniques, Vol.48, No.12, pp.2540-2545, 2000.

  However, even in the conventional processing method using the above-described oxidizing gas, fluorocarbon-based gas, and reducing gas, damage that may be caused by oxidation or abnormal etching of the material of the fine structure may occur. It was.

  The present invention has been made to solve the above-described problems, and in the removal of the sacrificial layer, it is possible to suppress the occurrence of damage to the fine structure while suppressing the generation of residues. With the goal.

The fine structure manufacturing method according to the present invention includes a sacrificial layer forming step of forming a sacrificial layer made of an organic material on a substrate made of an inorganic material, and a fine layer made of an inorganic material in contact with a part of the sacrificial layer. Sacrificing by fine structure formation process for forming the structure, and dry etching using plasma of mixed gas in which only oxygen gas, carbon tetrafluoride gas, and carbon monoxide gas are mixed after forming the microstructure At least a sacrificial layer removing step for selectively removing the layer, wherein the sacrificial layer removing step is configured such that the partial pressure of the carbon monoxide gas is four times the partial pressure of the oxygen gas and the partial pressure of the carbon tetrafluoride gas. Dry etching is performed under the condition that the value divided by the smaller one is 0.94 or more.

  In the fine structure manufacturing method, in the sacrificial layer removing step, dry etching is performed under the condition that the value obtained by dividing the partial pressure of the carbon tetrafluoride gas by the partial pressure of the oxygen gas is 0.1 or more and 1.5 or less. It is good to do.

  In the fine structure manufacturing method, in the sacrificial layer removing step, the partial pressure of the carbon monoxide gas is divided by the smaller one of the partial pressure of the oxygen gas and four times the partial pressure of the carbon tetrafluoride gas. However, dry etching may be performed under the condition of 0.94 or more and 1.25 or less.

  In the above-described microstructure manufacturing method, a pretreatment step of removing a part of the sacrificial layer by dry etching using oxygen in an active state may be provided before the sacrificial layer removing step. In addition, before the sacrificial layer removal step, oxygen gas and carbon tetrafluoride under the condition that the value obtained by dividing the partial pressure of carbon tetrafluoride gas by the partial pressure of oxygen gas is 0.1 or more and 1.5 or less A pretreatment step of removing a part of the sacrificial layer by dry etching using plasma of the mixed gas may be provided.

  In the method for manufacturing a fine structure, the plasma may be generated by high-frequency discharge with a frequency of 13.56 MHz and a power of 200 W. Note that the microstructure includes an electrode made of gold. The sacrificial layer may be made of polybenzoxazole.

  As described above, according to the present invention, in the removal of the sacrificial layer, it is possible to obtain an excellent effect that the occurrence of damage to the fine structure can be suppressed while the generation of the residue is suppressed.

FIG. 1 is an explanatory diagram for explaining a manufacturing method of a fine structure according to Embodiment 1 of the present invention. FIG. 2 is a plan view showing the structure of the microstructure in the first embodiment of the present invention. FIG. 3 is a characteristic diagram showing the change in the etching rate of the sacrificial layer made of polybenzoxazole by the plasma treatment with respect to the change in the ratio of the CF ₄ gas partial pressure to the O ₂ gas partial pressure. FIG. 4 shows changes in the measured values of the etching rate of the sacrificial layer made of polybenzoxazole by plasma treatment (black circles) and Min (P _O2 , 4) with respect to the change in the ratio of the CF ₄ gas partial pressure to the O ₂ gas partial pressure. It is a characteristic figure which shows the curve (black square) which shows the change of * _PCF4 ). FIG. 5 is a graph showing the change in sheet resistance of a microstructure made of Au before and after being exposed to plasma treatment when the ratio of the CO gas partial pressure P _{CO to} Min (P _O2 , 4 × P _CF4 ) is changed. FIG. FIG. 6 is a characteristic diagram showing the change in the etching rate of the sacrificial layer with respect to the change in the CO gas partial pressure ratio with respect to Min (P _O2 , 4 × P _CF4 ). FIG. 7 is an explanatory diagram for explaining the manufacturing method of the fine structure according to the second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]
First, Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram for explaining a manufacturing method of a fine structure according to Embodiment 1 of the present invention. In FIG. 1, the state of the microstructure in each process is shown in a schematic cross section.

  First, a sacrificial layer 102 is formed on a substrate 101 as shown in FIG. Here, for example, an opening 103 reaching the substrate 101 is formed in the sacrificial layer 102 (sacrificial layer forming step). For example, the substrate 101 may be made of silicon. The sacrificial layer 102 may be made of polybenzoxazole.

  For example, first, a photosensitive organic resin composed of polybenzoxazole is applied onto the substrate 101 to form a coating film. Next, the formed coating film is pre-baked under conditions of 120 ° C. and about 4 minutes. Next, the sacrificial layer 102 having the opening 103 is formed by patterning using a known lithography technique, and then the sacrificial layer 102 is cured by performing a heat treatment at about 310 ° C. The sacrificial layer 102 may be formed with a layer thickness of about 1 μm, for example. Examples of the organic resin include “CRC-8300” manufactured by Sumitomo Bakelite. To such an organic resin, an adhesion assistant is added to improve adhesion with the substrate 101 and a seed layer described later.

  Next, as shown in FIG. 1B, a seed layer 104 is formed on the sacrificial layer 102, on the side wall of the opening 103, and on the bottom of the opening 103. For example, the seed layer 104 has a laminated structure of a Ti layer and an Au layer. This laminated structure can be formed by sequentially laminating a Ti layer and a gold layer by sputtering or vapor deposition. For example, the Ti layer may be about 0.1 μm thick and the Au layer may be about 0.1 μm thick.

  Next, as shown in FIG. 1C, a resist pattern 105 is formed on the seed layer 104. The resist pattern 105 includes an opening region 106 at a location where a microstructure described later is formed. The seed layer 104 is exposed at the bottom of the opening region 106. For example, a well-known photoresist material is applied on the seed layer 104 to form a resist coating film having a thickness of about 2 m. Then, the resist pattern 105 can be formed by patterning the resist coating film by a known photolithography technique using a photomask having a predetermined pattern.

  Next, as shown in FIG. 1D, a metal pattern 107 is formed by depositing gold (Au) on the seed layer 104 exposed in the opening region 106 by a known electrolytic plating method. . For example, the metal pattern 107 may be formed with a film thickness of about 1.0 μm. Next, the resist pattern 105 is removed, and the seed layer 104 around the metal pattern 107 is exposed as shown in FIG.

  Next, the seed layer 104 exposed by removing the resist pattern 105 is removed by etching using the metal pattern 107 as a mask, and the remaining seed layer 104 and the metal pattern 107 are removed as shown in FIG. Then, the fine structure 108 is formed (fine structure forming step). Here, the microstructure 108 has a cantilever structure. The microstructure 108 includes a portion of the opening 103 of the sacrificial layer 102 as a support portion 181, and includes a beam portion 182 that is continuous with the support portion 181. The fine structure 108 is, for example, a movable electrode. The metal pattern 107 is formed with a thickness of about 1 μm, and the beam portion 182 has a thickness of about 1 μm.

  In the selective etching of the seed layer 104, for example, first, the upper Au layer may be removed by wet etching using an etching solution made of iodine, ammonium iodide, water, and ethanol. In this etching process, a part of the metal pattern 107 is also etched. Next, the lower Ti layer may be removed by wet etching using an aqueous hydrogen fluoride solution.

After the microstructure 108 is formed as described above, the sacrificial layer 102 is selectively removed by dry etching using a mixed gas plasma in which only oxygen gas, carbon tetrafluoride gas, and carbon monoxide gas are mixed. (Sacrificial layer removal step). By removing the sacrificial layer 102, a gap is formed between the beam portion 182 and the substrate 101. As shown in FIG. 1G and the plan view of FIG. As a result, a microstructure 108 having spaced beam portions 182 is obtained.

  Here, in the removal of the sacrificial layer 102 described above, the value obtained by dividing the partial pressure of the carbon monoxide gas by the smaller one of the partial pressure of the oxygen gas and four times the partial pressure of the carbon tetrafluoride gas is 0. Dry etching is performed under the condition of 94 or more. By the removal process of the sacrificial layer 102 under this condition, the occurrence of damage to the fine structure 108 can be suppressed with high reproducibility while the generation of the residue is suppressed.

  In addition to removing the sacrificial layer 102, in addition to the above-described conditions, dry etching is performed under the condition that the value obtained by dividing the partial pressure of the carbon tetrafluoride gas by the partial pressure of the oxygen gas is 0.1 or more and 1.5 or less. By doing so, a practical etching rate (etching rate) can be obtained, and the sacrificial layer 102 can be removed more rapidly.

  In the above-described removal of the sacrificial layer 102, the value obtained by dividing the partial pressure of the carbon monoxide gas by the smaller one of the partial pressure of the oxygen gas and the partial pressure of the carbon tetrafluoride gas is 0.00. In addition to the condition of 94 or more, a value obtained by dividing the partial pressure of carbon monoxide gas by the smaller one of the partial pressure of oxygen gas and four times the partial pressure of carbon tetrafluoride gas is 1.25 or less. Also by performing dry etching under conditions, a practical etching rate (etching rate) can be obtained, and the sacrificial layer 102 can be removed more rapidly.

  Note that the dry etching described above may be performed by plasma treatment using discharge at a high frequency of 13.56 MHz. At this time, if the high-frequency power is 200 W or more, active oxygen, fluorine radicals, and the like are excessively generated, and the microstructure 108 may be oxidized or abnormally etched. Therefore, the high frequency power should be 200 W or less.

  Hereinafter, the dry etching process of the sacrificial layer using oxygen, carbon tetrafluoride, and carbon monoxide will be described in more detail.

  As mentioned above, oxidation and abnormal etching of the materials of microstructures are suppressed by plasma treatment using a mixed gas of oxidizing gas, fluorocarbon-based gas, and reducing gas as plasma species. It is known that the sacrificial layer can be removed without generating a residue.

  However, in this etching method, fluctuations in the etching rate of the organic resin (sacrificial layer), oxidation of the inorganic material (fine structure), abnormal etching, etc. may occur, and the fine structure may be damaged. There was found. As a result of intensive studies by the inventors, it has been found that the above-described problems occur according to the partial pressure ratio of the oxidizing gas, the fluorocarbon-based gas, and the reducing gas, and the generation state varies greatly. For example, although the fine structure is not damaged depending on the selection of the partial pressure ratio, the etching rate is low, and depending on the selection of the partial pressure ratio, the etching rate is high, but the material of the fine structure is oxidized and abnormal etching occurs. The problem that occurred.

In response to these situations, the inventors use O ₂ gas, CF ₄ gas, and CO gas as oxidizing gas, fluorocarbon-based gas, and reducing gas, and in addition, generate residues according to these gas conditions. It has been found that the oxidation and abnormal etching of a fine structure made of an inorganic material are suppressed with good reproducibility.

FIG. 3 is a characteristic diagram showing changes in the etching rate of the sacrificial layer made of poly-benzobisoxazole by plasma treatment with respect to changes in the ratio of the CF ₄ gas partial pressure to the O ₂ gas partial pressure. The vertical axis is normalized based on the maximum value of the etch rate. The sacrificial layer is formed by thermosetting polybenzoxazole by heat treatment at 310 ° C.

As shown in FIG. 3, the etch rate, when O ₂ gas only _{(P CF4 / P O2 = 0} ), and CF ₄ gas only low in the case of the ratio of CF ₄ gas partial pressure to the O ₂ gas partial pressure When the value is 0.25, the maximum value is taken.

The reason for taking such an etch rate distribution is considered as follows. In the case of plasma processing using only O ₂ gas, as the surface of the sacrificial layer is etched by O radicals (O ^* ) generated by plasma, a residue derived from the adhesion assistant is generated as described above. Since this residue covers the surface of the resin (sacrificial layer), it is considered that etching does not proceed easily and the etching rate is low.

On the other hand, in the case of plasma processing using only CF ₄ gas, residues such as silicon suboxide can be removed by F radicals (F ^* ) generated by the plasma, but the organic resin itself cannot be removed. It is considered low.

In the case of the plasma treatment in which O ₂ gas and CF ₄ gas are mixed, both O ^* and F ^* are generated by the plasma, and the removal of the organic resin by O ^* and the removal of the residue by F ^* progress simultaneously. It is considered to proceed without obstacles.

In such an etching mechanism, the etching reaction rate is limited by the smaller concentration of O ^* and F ^* supplied. As shown in FIG. 4, the inventors plotted the smaller one of the partial pressure P _O2 of O ₂ gas and four times the partial pressure of CF ₄ gas P _CF4 (black square) in FIG. It was found that the results agree well with the experimental results shown (black circles). In the following, “the smaller of O ₂ gas partial pressure P _O2 and four times the CF ₄ gas partial pressure P _CF4 ” is expressed as “Min (P _O2 , 4 × P _CF4 )”. I decided to.

As shown in FIG. 4, the curve (black square) indicating the change in Min (P _O2 , 4 × P _CF4 ) is in good agreement with the change in the measured value of etching rate (black circle). Here, in the region 401 where “0.1 ≦ P _CF4 / P _O2 ≦ 1.5” in FIG. 4, the etch rate is about half or more of the maximum value. If the etching rate exceeds half of the maximum, it can be said that the sacrificial layer can be etched efficiently.

FIG. 5 shows the sheet resistance change of the microstructure made of Au before and after being exposed to the plasma treatment when the ratio of the CO gas partial pressure P _{CO to} Min (P _O2 , 4 × P _CF4 ) is changed. Yes. Here, the ratio of O ₂ gas and CF ₄ gas in the O ₂ / CF ₄ mixed gas was set to P _O2 : P _CF4 = 4: 1 at which Min (P _O2 , 4 × P _CF4 ) was maximized. In the region where the CO gas partial pressure P _co is “0.94> P _co / Min (P _O2 , 4 × P _CF4 )”, the sheet resistance of the microstructure composed of Au changes greatly before and after etching. This indicates that the microstructure is damaged.

On the other hand, in the region 501 where “0.94 ≦ P _co / Min (P _O2 , 4 × P _CF4 )”, the sheet resistance of the microstructure before and after etching hardly changes. For this reason, “0.94 ≦ P _co / Min (PO ₂ , 4 × P _CF4 )” is a condition that can suppress the oxidation and abnormal etching of the material of the fine structure while suppressing the generation of the residue. I can say that.

As can be seen from the above, in plasma processing using a mixed gas of oxygen (O ₂ ) gas, carbon tetrafluoride (CF ₄ ) gas, and carbon monoxide (CO) gas as a plasma species, “0.94” ≦ P _co / Min (P _O2 , 4 × P _CF4 ) ”, the sacrificial layer can be etched away without generating a residue in a state where oxidation and abnormal etching of the fine structure are suppressed. Can do. If this condition is combined with the above-mentioned gas condition of “0.1 ≦ P _CF4 / P _O2 ≦ 1.5”, the oxidation and abnormal etching of the fine structure are suppressed and more quickly and efficiently. In addition, the sacrificial layer can be etched without generating a residue.

FIG. 6 shows how the etching rate of the sacrificial layer varies when the CO gas partial pressure ratio is changed with respect to Min (P _O2 , 4 × P _CF4 ). The vertical axis is normalized based on the maximum value of the etch rate in the region 501 described above. As shown in FIG. 6, the etch rate of the sacrificial layer decreases as the CO gas partial pressure is increased.

Here, in the region 601 where “0.94 ≦ P _co / Min (PO ₂ , 4 × P _CF4 ) ≦ 1.25”, the oxidation and abnormal etching of the fine structure can be suppressed, and the etching rate is the maximum value. It is a region that is about half or more of the above. As described above, if the etching rate exceeds half of the maximum, it can be said that the sacrificial layer can be efficiently etched. Therefore, “0.94 ≦ P _co / Min (P _O2 , 4 × P _CF4 ) It can be said that ≦ 1.25 ”is a condition in which the sacrificial layer can be etched efficiently and quickly without generating a residue in a state where oxidation and abnormal etching of the microstructure are suppressed.

[Embodiment 2]
Next, Embodiment 2 of the present invention will be described with reference to FIG. FIG. 7 is an explanatory diagram for explaining the manufacturing method of the fine structure according to the second embodiment of the present invention. In FIG. 7, the state of the fine structure in each step is shown in a schematic cross section. Note that the process described with reference to FIG. 7A is the same as the process described with reference to FIG. 1F. In the second embodiment, the process will be described with reference to FIGS. The manufacturing process in the first embodiment is the same.

  Also in the second embodiment, the seed layer 104 and the metal pattern are formed in the same manner as in the first embodiment described with reference to FIGS. 1A to 1F, as shown in FIG. The fine structure 108 is formed by the step 107 (fine structure forming step).

  In the second embodiment, after the microstructure 108 is formed on the sacrificial layer 102 as described above, a part of the sacrificial layer 102 is removed by dry etching without using a reducing gas, as shown in FIG. ), A part of the sacrificial layer 121 is left (pretreatment step).

  Here, the treatment for removing a part of the sacrificial layer 102 may be performed by dry etching using active oxygen such as ozone or oxygen plasma. In the case of using ozone, the sacrificial layer 102 may be exposed to an ozone atmosphere while being heated. This treatment is performed by using a well-known ozone asher or the like. In the treatment using oxygen plasma, a general plasma etching apparatus may be used.

  Further, the treatment for removing a part of the sacrificial layer 102 may be performed by dry etching using plasma of a mixed gas of oxygen gas and carbon tetrafluoride. In this case, as described with reference to FIG. 4, the oxygen gas and the four fluorines under the condition that the value obtained by dividing the partial pressure of the carbon tetrafluoride gas by the partial pressure of the oxygen gas is 0.1 or more and 1.5 or less. A mixed gas with carbonized carbon may be used. By setting this condition, more rapid processing is possible.

After removing a part of the sacrificial layer 102 as described above, the sacrificial layer 121 remaining by dry etching using plasma of a mixed gas obtained by mixing only oxygen gas, carbon tetrafluoride gas, and carbon monoxide gas. Are selectively removed (sacrificial layer removal step). By removing all the sacrificial layer 102 (sacrificial layer 121) in this way, a gap is formed between the beam portion 182 and the substrate 101, as shown in FIG. 7C and the plan view of FIG. Thus, the microstructure 108 including the beam portion 182 supported by the support portion 181 and separated from the substrate 101 is obtained.

  Also in this dry etching process, the value obtained by dividing the partial pressure of carbon monoxide gas by the smaller one of the partial pressure of oxygen gas and four times the partial pressure of carbon tetrafluoride gas is 0.94 or more. Dry etching is performed under conditions. With this condition, in the removal of the sacrificial layer 121, the occurrence of damage to the fine structure 108 can be suppressed with high reproducibility in a state where generation of residues is suppressed.

  Further, in the removal of the remaining sacrificial layer 121, in addition to the above-described conditions, the value obtained by dividing the partial pressure of carbon tetrafluoride gas by the partial pressure of oxygen gas is 0.1 to 1.5. When dry etching is performed, a higher etching rate (faster etching rate) can be obtained, and the remaining sacrificial layer 121 can be removed more quickly.

  Further, in the removal of the remaining sacrificial layer 121 described above, a value obtained by dividing the partial pressure of the carbon monoxide gas by the smaller one of the partial pressure of the oxygen gas and the partial pressure of the carbon tetrafluoride gas is four times. In addition to the condition of 0.94 or higher, the value obtained by dividing the partial pressure of carbon monoxide gas by the smaller one of the partial pressure of oxygen gas and four times the partial pressure of carbon tetrafluoride gas is 1.25. Also by performing dry etching under the following conditions, a higher etching rate (faster etching rate) can be obtained, and the remaining sacrificial layer 121 can be removed more rapidly.

  In addition, according to the second embodiment described above, since part of the sacrificial layer 102 is removed in the pretreatment step that does not use a reducing gas, all the sacrificial layer 102 is made of oxygen gas, carbon tetrafluoride gas. , And carbon monoxide gas, the sacrificial layer 102 can be removed more quickly than in the first embodiment in which the gas is removed by dry etching using a mixed gas.

  Note that the dry etching described above may be performed by plasma treatment using discharge at a high frequency of 13.56 MHz. At this time, if the high-frequency power is 200 W or more, active oxygen, fluorine radicals, and the like are excessively generated, and the microstructure 108 may be oxidized or abnormally etched. Therefore, the high frequency power should be 200 W or less.

  As explained above, according to the present invention, the sacrificial layer is divided by dividing the carbon monoxide gas partial pressure by the smaller one of the partial pressure of oxygen gas and four times the partial pressure of carbon tetrafluoride gas. Since the removed value is removed by dry etching under the condition that the value becomes 0.94 or more, the occurrence of damage to the fine structure can be suppressed while the generation of the residue is suppressed.

  The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious. For example, in the above-described embodiment, the case where the fine structure is mainly composed of Au has been described. However, the structure is not limited to this, and the fine structure may be made of other metal materials or inorganic materials such as semiconductors such as silicon. The same applies to those made of materials. The same applies to the substrate, and the substrate is not limited to silicon, and the same applies even if the substrate is composed of other inorganic materials such as SiC and compound semiconductors. Further, the sacrificial layer is not limited to polybenzoxazole, but may be composed of other organic materials (organic resins).

  DESCRIPTION OF SYMBOLS 101 ... Substrate, 102 ... Sacrificial layer, 103 ... Opening, 104 ... Seed layer, 105 ... Resist pattern, 106 ... Opening region, 107 ... Metal pattern, 108 ... Fine structure, 181 ... Supporting part, 182 ... Beam part.

Claims (8)

A sacrificial layer forming step of forming a sacrificial layer made of an organic material on a substrate made of an inorganic material;
A microstructure forming step of forming a microstructure made of an inorganic material in contact with a part of the sacrificial layer;
Sacrificial layer removal for selectively removing the sacrificial layer by dry etching using a mixed gas plasma in which only oxygen gas, carbon tetrafluoride gas, and carbon monoxide gas are mixed after forming the microstructure. Comprising at least a process,
In the sacrificial layer removal step, the value obtained by dividing the partial pressure of carbon monoxide gas by the smaller one of the partial pressure of oxygen gas and four times the partial pressure of carbon tetrafluoride gas is 0.94 or more. A method for producing a fine structure, characterized in that the dry etching is performed under conditions. In the manufacturing method of the fine structure according to claim 1,
In the sacrificial layer removing step, the dry etching is performed under a condition that a value obtained by dividing a partial pressure of carbon tetrafluoride gas by a partial pressure of oxygen gas is 0.1 or more and 1.5 or less. Manufacturing method of structure. In the manufacturing method of the fine structure according to claim 1,
In the sacrificial layer removing step, the value obtained by dividing the partial pressure of the carbon monoxide gas by the smaller one of the partial pressure of the oxygen gas and the partial pressure of the carbon tetrafluoride gas is 0.94 or more. A method for manufacturing a fine structure, wherein the dry etching is performed under a condition of 25 or less. In the manufacturing method of the fine structure according to any one of claims 1 to 3,
Before the sacrificial layer removal step, a method for manufacturing a microstructure is provided, which includes a pretreatment step of removing a part of the sacrificial layer by dry etching using oxygen in an active state. In the manufacturing method of the fine structure according to any one of claims 1 to 3,
Before the sacrificial layer removal step, the value obtained by dividing the partial pressure of the carbon tetrafluoride gas by the partial pressure of the oxygen gas is 0.1 to 1.5. A method of manufacturing a microstructure, comprising a pretreatment step of removing a part of the sacrificial layer by dry etching using plasma of mixed gas. In the manufacturing method of the fine structure according to any one of claims 1 to 5,
The plasma is generated by high-frequency discharge with a frequency of 13.56 MHz and a power of 200 W. In the manufacturing method of the fine structure according to any one of claims 1 to 6,
The method for manufacturing a fine structure, wherein the fine structure includes an electrode made of gold. In the manufacturing method of the fine structure according to any one of claims 1 to 7,
The sacrificial layer is made of polybenzoxazole, and is a method for manufacturing a microstructure.

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