JP2008034734A - Method for supplying fluorine compound containing oxygen, and plasma treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stably supplying plasma treatment equipment with a fluorine compound containing oxygen having a property being easily polymerized at a room temperature, particularly tetrafluorofuran without substantially deteriorating the etching performance or the like of the fluorine compound, and to provide a plasma treatment method changing the fluorine compound containing oxygen supplied by such a method into a plasma and plasma-treating a substance to be treated. <P>SOLUTION: In the method for supplying the plasma treatment equipment with the fluorine compound containing oxygen, a polymer is pyrolyzed consisting of repeating units represented by formula C<SB>4</SB>F<SB>4</SB>O, the fluorine compound is obtained containing oxygen represented by formula: C<SB>4</SB>F<SB>4</SB>O, and the plasma treatment equipment is supplied with the obtained fluorine compound containing oxygen. In the plasma treatment method, the plasma treatment equipment is supplied with the fluorine compound containing oxygen by the supplying method, the fluorine compound containing oxygen is changed into the plasma in the equipment, and the substance to be treated is plasma-treated. A manufacturing method for a semiconductor device uses the plasma treatment method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for supplying an oxygen-containing fluorine compound as a plasma raw material to a plasma processing apparatus in dry etching or the like and a plasma processing method.

  Conventionally, saturated fluorocarbons such as carbon tetrafluoride and octafluorocyclobutane are widely known as dry etching gas and film forming gas used for semiconductor production. However, these gases have a very long life in the atmosphere of several thousand years or more, and adverse effects on global warming have been pointed out, and restrictions are imposed on their use. Therefore, various new fluorine-containing compounds have been proposed as alternatives.

  For example, a fluorine compound having a carbon-carbon double bond or triple bond in the molecule, hexafluoro-1,3-butadiene (Patent Document 1), hexafluoro-2-butyne (Patent Document 1), etc. An example of applying oxygen-containing fluorine compounds such as hexafluoropropene oxide (Patent Document 2); trifluoromethyl-trifluorovinyl ether (Patent Document 3) to dry etching of a silicon compound layer typified by silicon oxide; It has been reported.

  However, with the progress of higher integration and higher performance of semiconductor devices in recent years, technical requirements for dry etching gas and film forming gas used for manufacturing semiconductor devices have become more and more severe. There is a demand for the development of a dry etching gas that excels in quality and a film-forming gas that can form a film with higher quality and excellent adhesion.

JP-A-6-275568 WO02 / 39494 pamphlet JP-A-10-27781 JP-A-11-140441

In the above-mentioned Japanese Patent Application No. 2005-308363, the present applicant has the formula: C _x F _y O (x represents 4 or 5, y represents an integer satisfying y / x satisfying 1 to 1.5). It is disclosed that the oxygen-containing fluorine compound shown has excellent etching performance, and among such oxygen-containing fluorine compounds, an oxygen-containing fluorine compound having a low F / C ratio can impart particularly good workability. .

  Tetrafluorofuran is a typical example of the oxygen-containing fluorine compound having a low F / C ratio. In the literature (Journal of Chemical Society (C), 2146, 1970, hereinafter referred to as “Document A”). As pointed out, this compound has poor thermal stability and has the property of easily polymerizing at room temperature to form a polymer. Therefore, when the influence of the polymerization of tetrafluorofuran on the etching performance was examined, it was found that the performance could be lowered.

  Accordingly, the present invention provides a method for stably supplying an oxygen-containing fluorine compound having a property of being easily polymerized at room temperature, particularly tetrafluorofuran, to a plasma processing apparatus without substantially reducing the etching performance, etc. It is an object of the present invention to provide a plasma processing method in which the supplied oxygen-containing fluorine compound is converted into plasma and the object to be processed is subjected to plasma processing, and a semiconductor device manufacturing method using the plasma processing method.

  The present inventors first tried to add a compound such as a polymerization inhibitor for the purpose of preventing polymerization of tetrafluorofuran when supplying tetrafluorofuran to a plasma processing apparatus. However, the polymerization could not be sufficiently suppressed, and the etching performance and the like were lowered. Therefore, as a result of diligent studies on various methods, it was found that a gaseous monomer of the compound can be easily obtained by thermally decomposing a polymer of tetrafluorofuran, and the gaseous unit thus obtained is obtained. It has been found that excellent etching performance, film forming performance and ashing performance can be exhibited by supplying the polymer to the plasma processing apparatus, and the present invention has been completed.

Thus, according to the first aspect of the present invention, there is provided a method for supplying an oxygen-containing fluorine compound to a plasma processing apparatus according to the following (1) to (4).
(1) A polymer comprising a repeating unit represented by the formula: C ₄ F ₄ O is thermally decomposed to obtain an oxygen-containing fluorine compound represented by the formula: C ₄ F ₄ O, and then the obtained oxygen-containing compound is obtained. A method for supplying an oxygen-containing fluorine compound to a plasma processing apparatus, comprising supplying an oxygen fluorine compound to the plasma processing apparatus.
(2) When supplying the oxygen-containing fluorine compound obtained by thermally decomposing the polymer to the plasma processing apparatus, the oxygen-containing fluorine compound is supplied at a concentration of 0.0001 to 0.02 mol / liter. (2) The supply method according to (1).
(3) The supply method according to (1) or (2), wherein the oxygen-containing fluorine compound is tetrafluorofuran.
(4) The supply method according to any one of (1) to (3), wherein the plasma processing apparatus is a plasma etching apparatus or a film forming apparatus using a plasma CVD method.

According to a second aspect of the present invention, there is provided the plasma processing method according to the following (5) to (8). (5) A polymer comprising a repeating unit represented by the formula: C ₄ F ₄ O is thermally decomposed to obtain an oxygen-containing fluorine compound represented by the formula: C ₄ F ₄ O, and then the obtained oxygen-containing compound is obtained. A plasma processing method, comprising: supplying an oxygen fluorine compound to a plasma processing apparatus; converting the oxygen-containing fluorine compound into plasma in the apparatus;
(6) When supplying the oxygen-containing fluorine compound obtained by pyrolyzing the polymer to the plasma processing apparatus, the oxygen-containing fluorine compound is supplied at a concentration of 0.0001 to 0.02 mol / liter. (6) The plasma processing method according to (5).
(7) The plasma processing method according to (5) or (6), wherein the oxygen-containing fluorine compound is tetrafluorofuran.
(8) The plasma processing method according to any one of (5) to (7), wherein the plasma processing apparatus is a plasma etching apparatus or a film forming apparatus using a plasma CVD method.

According to a third aspect of the present invention, there is provided a method for manufacturing a semiconductor device according to the following (9).
(9) A method for manufacturing a semiconductor device, wherein the plasma processing method according to any one of (5) to (8) is used.

  According to the present invention, an oxygen-containing fluorine compound having a property of being easily polymerized at room temperature can be stably supplied to a plasma processing apparatus without substantially reducing its etching performance and the like. The desired plasma treatment can be efficiently performed on the workpiece.

Hereinafter, the present invention will be described in detail.
1) Supplying method of oxygen-containing fluorine compound The method of supplying the oxygen-containing fluorine compound to the plasma processing apparatus of the present invention is a polymer comprising a repeating unit represented by the formula: C ₄ F ₄ O (hereinafter simply “polymer”). To obtain an oxygen-containing fluorine compound represented by the formula: C ₄ F ₄ O (hereinafter sometimes simply referred to as “oxygen-containing fluorine compound”). The obtained oxygen-containing fluorine compound is supplied to a plasma processing apparatus.

(1) as the polymer used in the polymer present invention have the formula: consist C 4 _F 4 repeating units represented by _O, by pyrolysis, the formula: C 4 _F 4 oxygenated fluorocarbon represented by _O If a compound is obtained as a gaseous monomer, it will not restrict | limit in particular. Specific examples of polymers used in the present invention include tetrafluorofuran polymer; tetrafluorocyclobutenone polymer; tetrafluoro-1-butyn-3-one polymer; tetrafluorofuran, tetrafluorocyclobut And polymers of at least two compounds selected from the group consisting of tenon and tetrafluoro-1-butyn-3-one. Among these, a tetrafluorofuran polymer is particularly preferable.
Any of these polymers can be appropriately produced by referring to a known method (for example, the method described in Document A). For example, in the case of tetrafluorofuran, Document A describes the structure of a polymer bonded at the 2nd and 5th positions of the furan ring as the estimated structure of the tetrafluorofuran polymer.

(2) Thermal decomposition of polymer In the present invention, the polymer is thermally decomposed to obtain an oxygen-containing fluorine compound as a gaseous monomer. Here, the thermal decomposition of a polymer means that at least a part of the polymer is decomposed into its constituent unit monomer by heating the polymer to a predetermined temperature. There is no particular limitation on the degree of thermal decomposition as long as the gaseous monomer of the oxygen-containing fluorine compound can be obtained by thermal decomposition of the polymer in an amount that enables the desired plasma treatment.

  The thermal decomposition of the polymer can be easily performed by, for example, placing the polymer in a reaction vessel, placing the reaction vessel in an electric furnace, and increasing the temperature in the electric furnace to heat the polymer. .

  Although it does not specifically limit as a reaction container to be used, Since a polymer needs to be filled in a container, the container of the form which attached the flange to the upper part is preferable. For example, a reaction vessel (for example, a reaction vessel made of stainless steel) used in metal organic chemical vapor deposition (MOCVD) applications can be mentioned. Moreover, in order to supply the gaseous monomer generated by thermal decomposition to the plasma processing apparatus, a reaction vessel provided with a heat resistant valve is usually used.

  The method for raising the temperature in the electric furnace is not particularly limited, and a heater type, a heat medium type, an electromagnetic type, a dielectric type, and the like can be appropriately employed.

  The heating temperature of the polymer may be a temperature at which the polymer is thermally decomposed to produce an oxygen-containing fluorine compound as a gaseous monomer. The heating temperature is usually 350 to 600 ° C, preferably 400 to 500 ° C. Heating may be performed continuously to a desired temperature or intermittently. What is necessary is just to adjust a heating time and the pressure at the time of heating suitably according to the production amount of an oxygen-containing fluorine compound and the thermal decomposition efficiency of a polymer. Usually, the polymer may be heated under conditions of normal temperature (25 ° C.) and normal pressure (0.1 MPa).

In addition, the production | generation of the oxygen-containing fluorine compound from the polymer by thermal decomposition can be confirmed as follows.
The polymer is placed in a reaction vessel equipped with a valve, the reaction vessel is placed in an electric furnace, and the valve-out is connected to a glass trap cooled by a method such as immersion in a dry ice / acetone bath.
Next, the temperature in the electric furnace is raised and the reaction vessel is gradually heated to thermally decompose the polymer, and at the same time, the gas generated by the thermal decomposition is collected as a liquid in a glass trap.
The liquid substance collected in the glass trap is an oxygen-containing fluorine compound represented by the formula: C ₄ F ₄ O, and the production amount thereof is determined by gas chromatography analysis (GC analysis), gas chromatography It can confirm suitably by mass spectrometry (GC-MS analysis) and nuclear magnetic resonance spectroscopy (NMR analysis).

The obtained oxygen-containing fluorine compound represented by the formula: C ₄ F ₄ O has a ratio F / C of the number of fluorine atoms and carbon atoms of its constituent atoms of 1 and can be etched with good selectivity. It is useful as a gas or a film forming gas capable of forming a strong film.

  For example, tetrafluorofuran as a gaseous monomer by thermal decomposition of a polymer of tetrafluorofuran, and tetrafluorocyclobutenone as a gaseous monomer by thermal decomposition of a polymer of tetrafluorocyclobutenone. As a gaseous monomer, tetrafluoro-1-butyn-3-one is converted into tetrafluorofuran, tetrafluorocyclobutenone and tetrafluoro-1-butyne by thermal decomposition of a polymer of -1-butyn-3-one. Each constituent monomer component is obtained as a gaseous monomer by thermal decomposition of a polymer of at least two compounds selected from the group consisting of 3-one. Tetrafluorofuran is particularly preferred as the oxygen-containing fluorine compound as the gaseous monomer thus obtained.

  The structural formula of tetrafluorofuran is shown in formula (i), the structural formula of tetrafluorocyclobutenone is shown in formula (ii), and the structural formula of tetrafluoro-1-butyn-3-one is shown in formula (iii). .

(3) Supply of oxygen-containing fluorine compound to plasma processing apparatus In the present invention, an oxygen-containing fluorine compound obtained by thermally decomposing the polymer is supplied into the plasma processing apparatus.
When supplying the oxygen-containing fluorine compound to the plasma processing apparatus, an inert gas such as helium, neon, argon, or xenon may be mixed at an appropriate ratio as necessary. When the plasma processing apparatus is a plasma dry etching apparatus, oxygen-containing gas such as oxygen, ozone, carbon dioxide, carbon monoxide may be further mixed.

  In the present invention, when supplying the oxygen-containing fluorine compound to the plasma processing apparatus, the concentration of the oxygen-containing fluorine compound is preferably 0.0001 to 0.02 mol / liter, more preferably 0.001 to 0.00. It is supplied at 02 mol / liter, more preferably 0.01 to 0.02 mol / liter. Here, the concentration of the oxygen-containing fluorine compound represents the amount of the oxygen-containing fluorine compound in the volume of the reaction vessel used for the decomposition of the polymer.

  If the concentration of the oxygen-containing fluorine compound is within the above range, the oxygen-containing fluorine compound obtained by pyrolysis can be effectively prevented from repolymerizing due to residual heat during the pyrolysis, and the compound to the plasma processing apparatus can be prevented. Thus, a desired plasma treatment can be achieved by maintaining the supply amount of the gas stably.

  As a method for adjusting the concentration of the oxygen-containing fluorine compound in the reaction vessel to a predetermined value, (α) the oxygen-containing fluorine compound generated by thermal decomposition is placed in the reaction vessel so that the concentration becomes a predetermined value. (Β) Filling the reaction vessel with an inert gas such as argon gas, helium gas or nitrogen gas and diluting the oxygen-containing fluorine compound generated by thermal decomposition with the inert gas And (γ) a method in which the methods (α) and (β) are combined.

  The method for supplying the oxygen-containing fluorine compound to the plasma processing apparatus is not particularly limited, and may be supplied to the plasma processing apparatus using a known method, for example, a mass flow controller. The supply rate of the oxygen-containing fluorine compound is not particularly limited, and may be appropriately adjusted so that a desired plasma treatment is performed.

Examples of the plasma processing apparatus used in the present invention include a plasma etching apparatus, a film forming apparatus using a plasma CVD method, and a plasma ashing apparatus.
There is no particular limitation on the plasma generation mode of the plasma processing apparatus. For example, a helicon wave method, a high frequency dielectric method, a parallel plate method, a magnetron method, a microwave method, and the like can be given. Among these, a helicon wave system, a high frequency induction system, or a microwave system plasma processing apparatus is preferable because plasma generation in a high-density region is easy.

  According to the supply method of the present invention, it is possible to suppress the formation of a polymer of an oxygen-containing fluorine compound that is easily polymerized near room temperature and stably supply it as a gas into the plasma processing apparatus. Can be efficiently performed.

  In addition, by adjusting the concentration of the oxygen-containing fluorine compound obtained by thermal decomposition to a predetermined concentration and supplying it, repolymerization due to residual heat during the thermal decomposition of the polymer is effectively prevented, and the oxygen-containing fluorine compound Therefore, a more stable supply to the plasma processing apparatus becomes possible, and the desired plasma processing can be performed more efficiently.

2) Plasma treatment method using oxygen-containing fluorine compound In the plasma treatment method of the present invention, a polymer comprising a repeating unit represented by the formula: C ₄ F ₄ O is thermally decomposed, and the formula: C ₄ F ₄ O After obtaining the oxygen-containing fluorine compound represented, the obtained oxygen-containing fluorine compound is supplied to a plasma processing apparatus, the oxygen-containing fluorine compound is converted into plasma in the apparatus, and the object to be processed is plasma-treated. Features. Here, the plasma treatment of the object to be processed specifically means that at least one process selected from the group consisting of etching, film formation, and ashing is performed on the object to be processed in a plasma atmosphere.

  A method for supplying the obtained oxygen-containing fluorine compound to the plasma processing apparatus after thermally decomposing the polymer to obtain a predetermined oxygen-containing fluorine compound is performed according to the above-described oxygen-containing fluorine compound supply method of the present invention. Just do it.

  Examples of the plasma processing method of the present invention include: (a) a plasma etching method using the oxygen-containing fluorine compound supplied to the plasma processing apparatus as a dry etching gas; and (b) the oxygen-containing fluorine supplied to the plasma processing apparatus. A film forming method by a plasma CVD method using a compound as a film forming gas; and (c) the oxygen-containing fluorine compound supplied to the plasma processing apparatus is activated by plasma discharge, for example, a chamber of a dry etching apparatus or a CVD apparatus. There is an ashing method for ashing and removing contaminants and the like inside.

(A) Plasma etching method In this specification, plasma etching refers to an operation of etching a fine pattern on an object to be processed (substrate to be etched) in an atmosphere in which gaseous oxygen-containing fluorine compound molecules are turned into plasma.

  Examples of the substrate to be etched include a glass substrate, a silicon single crystal wafer, a substrate such as gallium arsenide, and the like that includes a thin film layer of a material to be etched.

  Preferable specific examples of the material to be etched include a silicon oxide film; a TEOS film, a BPSG film, a PSG film, and an SOG film; an HSQ (Hydrogen silsesquioxane) film; an MSQ (Methyl silsesquioxane) film; Or a porous film of the above film, but a silicon oxide film is particularly preferred.

In plasma etching, a plasma having a high density region of usually 10 ¹⁰ ions / cm ³ or more is generated as plasma to be irradiated during etching. In particular, by setting the plasma density to 10 ¹⁰ to 10 ¹³ ions / cm ³ , a high etching rate and high selectivity can be ensured, and a finer pattern can be formed.

  As the plasma etching apparatus, the same plasma processing apparatus as mentioned in the section of the supply method of the present invention can be used.

  It is not necessary to select a special range for the pressure at the time of plasma etching. In general, the plasma reaction gas of the present invention is preferably added to the inside of the etching chamber in an etching apparatus degassed to a vacuum. It introduce | transduces so that it may become -1.3kPa, Most preferably, it may be 0.0001-0.13kPa.

The ultimate temperature of the substrate to be etched during plasma etching is preferably 0 to 300 ° C, more preferably 60 to 250 ° C, and particularly preferably 80 to 200 ° C.
The substrate temperature may or may not be controlled by cooling or the like. The etching treatment time is generally 10 seconds to 10 minutes, but in the present invention, high-speed etching is possible, and it is preferable to improve the productivity by 10 seconds to 3 minutes.

  When the oxygen-containing fluorine compound is used as an etching gas, an inert gas selected from the group consisting of helium, neon, argon, xenon, and krypton is used to control the concentration of etching species generated in plasma and the control of ion energy. Gas may be added. These inert gases can be used alone or in combination of two or more.

  As the addition amount of the inert gas, the total amount of the inert gas with respect to the oxygen-containing fluorine compound is preferably 2 to 200 in terms of volume ratio (total amount of inert gas / oxygen-containing fluorine compound amount). It is particularly preferable to be 150.

Further, O ₂ or O ₃ may be added to alleviate the etching stop. When O ₂ or O ₃ is added, the total amount of O ₂ and O ₃ with respect to the oxygen-containing fluorine compound is 0.1 to 50 in a volume ratio (total amount of O ₂ and O ₃ / oxygen-containing fluorine compound amount). Preferably, 0.5-30 is more preferable.

Furthermore, one or more of CO and CO ₂ may be added to the oxygen-containing fluorine compound gas in order to improve the selectivity with respect to a mask such as a resist or polysilicon. The total amount of CO and CO ₂ with respect to the oxygen-containing fluorine compound is preferably from 5 to 150, particularly preferably from 10 to 100, as a volume ratio (total amount of CO and CO ₂ / oxygen-containing fluorine compound amount).

(B) Film-forming method by plasma CVD method In this specification, the plasma CVD method refers to a technique in which the oxygen-containing fluorine compound is activated and polymerized by plasma discharge to form thin fluorocarbon films on the surfaces of various objects to be processed. .

The process of forming the fluorocarbon film is not always clear, but it is considered that the oxygen-containing fluorine compound is decomposed under the discharge dissociation conditions and polymerizes to form a fluorocarbon film.
The thickness of the resulting fluorocarbon film is usually in the range of 0.01 to 10 μm.

Specifically, as a method of the plasma CVD method, a conventionally known method, for example, a method described in JP-A-9-237783 can be employed.
As plasma generation conditions, a high frequency (RF) output of 10 W to 10 kW, an object temperature of 0 to 500 ° C., and a reaction chamber pressure of 0.005 to 13.3 kPa can be employed.

  Examples of the apparatus used for the plasma CVD method include the same apparatus as the plasma processing apparatus described in the section of the supply method of the present invention.

An inert gas selected from the group consisting of helium, neon, argon, xenon, and krypton may be added to control the concentration of active species generated in the plasma and promote dissociation of the source gas. These inert gases can be used alone or in combination of two or more.
As the addition amount of the inert gas, the total amount of the inert gas with respect to the oxygen-containing fluorine compound is preferably 2 to 200 in terms of volume ratio (total amount of inert gas / oxygen-containing fluorine compound amount). More preferably, 150.

  Furthermore, for the purpose of promoting dissociation of the plasma reaction gas and reducing damage to the object to be processed, ultraviolet irradiation by a low-pressure mercury lamp or the like can be performed, or ultrasonic waves can be irradiated to the object to be processed and the reaction space.

  The object to be treated is not particularly limited, but functions such as insulation, water repellency, corrosion resistance, acid resistance, lubricity, light anti-reflection, etc. in the semiconductor manufacturing field, electronic / electrical field, precision machine field, and other fields Articles and members that require properties, preferably articles and members that require insulating properties in the semiconductor manufacturing field and electronic and electrical field, and substrates used in these fields are particularly preferred.

Specific examples of preferable substrates include silicon films such as a single crystal silicon film, a polycrystalline silicon film, and an amorphous silicon film; a silicide film made of tungsten, molybdenum, titanium, tantalum, or the like; SiN, SiON, SiO ₂ , BSG (boron- Silicate glass), PSG (phosphorus-silicate glass), BPSG (boron-phosphorus-silicate glass), AsSG (arsenic silicate glass), SbSG (antimony silicate glass), NSG (nitrogen-silicate glass), PbSG (lead-silicate glass) ) And SOG (spin on glass); conductive films such as TiN and TaN; gallium-arsenide substrates; diamond-like carbon films and aluminum plates; soda lime glass; alumina films; zirconium oxide films; Ceramics consisting of aluminum nitride and aluminum oxide; and the like.

(C) Ashing Method In this specification, ashing (also referred to as plasma ashing) refers to a dry etching apparatus or a CVD that uses a gas containing the oxygen-containing fluorine compound and activates the oxygen-containing fluorine compound by plasma discharge. This refers to the ash removal of contaminants in the chamber of the apparatus. Further, it means removing contaminants on the surface of an object to be processed by dry etching or CVD with active species, and further polishing and planarizing the surface of the object to be processed with active species. It is particularly preferably used for removing unnecessary polymer components deposited in the chamber, removing an oxide film from the semiconductor device substrate, and removing the resist from the semiconductor device.

  In plasma ashing, generation of active species by plasma decomposition is necessary, and plasma reaction conditions for that purpose are appropriately selected.

  According to the plasma processing method of the present invention described above, the oxygenated fluorine compound that is easily polymerized near room temperature is suppressed from being polymerized, and is stably supplied to the plasma processing apparatus without substantially reducing the etching performance or the like. In the apparatus, the desired plasma treatment of the object to be processed can be performed efficiently.

  In addition, by adjusting the concentration of the oxygen-containing fluorine compound obtained by thermal decomposition to a predetermined concentration, repolymerization due to residual heat during the thermal decomposition of the polymer is effectively prevented, and the oxygen-containing fluorine compound is converted into plasma. It can supply more stably to a processing apparatus and can perform the desired plasma processing of a to-be-processed object more efficiently.

Therefore, by using the plasma processing method of the present invention, it is possible to efficiently manufacture a high-performance semiconductor device with high integration, high density, and large diameter. Specifically, in the manufacturing process of the semiconductor device, at least one process selected from the group consisting of etching, film formation, and ashing is performed on the substrate according to the plasma processing method of the present invention, that is, the formula: C ₄ A polymer composed of repeating units represented by F ₄ O is thermally decomposed to obtain an oxygen-containing fluorine compound represented by the formula: C ₄ F ₄ O, and then the obtained oxygen-containing fluorine compound is converted into a plasma processing apparatus. In the apparatus, the oxygen-containing fluorine compound is turned into plasma and the treatment is performed to manufacture a semiconductor device. The semiconductor device can be manufactured according to a known method, for example, a method described in JP-A-2002-9014, except that the plasma processing method of the present invention is performed.

  EXAMPLES Hereinafter, although an Example demonstrates embodiment of this invention concretely, this invention is not restrict | limited by these Examples. Unless otherwise specified, “parts” and “%” represent “parts by weight” and “% by weight”, respectively.

The analysis conditions adopted below are as follows.
(1) Gas chromatography analysis (GC analysis)
Apparatus: HP-6890 (manufactured by Hewlett-Packard Company)
Column: Neutrabond-1 (60 m × ID 0.25 μm, 1.5 μmdf)
(Manufactured by GL Sciences)
Column temperature: 40 ° C. (10 minutes) → [Raise temperature at 20 ° C./min]→240° C. (10 minutes)
Injection temperature: 200 ° C
Carrier gas: Nitrogen gas detector: FID

(2) Gas chromatograph mass spectrometry (GC-MS analysis)
GC part: HP-6890 (manufactured by Hewlett-Packard Company)
Column: Neutrabond-1 (60 m × ID 0.25 μm, 1.5 μmdf)
(Manufactured by GL Sciences)
Column temperature: 40 ° C. (10 minutes) → [Raise temperature at 20 ° C./min]→240° C. (10 minutes)
Injection temperature: 200 ° C
Carrier gas: Nitrogen gas Detector: FID
MS part: 5973 NETWORK (manufactured by Hewlett-Packard Company)
Detector: EI type (acceleration voltage: 70 eV)

(3) NMR analysis apparatus: ¹⁹ F-NMR apparatus (JNM-ECA-500, manufactured by JEOL Ltd.)

(Production Example 1) Preparation of tetrafluorofuran and polymer thereof (a) Synthesis of tetrafluorofuran This compound was synthesized according to Document A. While maintaining a SUS316 reaction tube with a stirrer filled with 2500 parts of cobalt trifluoride (manufactured by Synquest) at a temperature of 120 ° C., the tetrahydrofuran (manufactured by Wako Pure Chemical Industries) was gasified at a rate of 1 part / min. It was supplied under a nitrogen stream (50 ml / min) to react a total of 50 parts. The gas coming out of the reaction tube was bubbled with water filled in the washing bottle to remove acid gas. The reaction product coming out of the washing bottle was collected by a glass trap (filled with sodium fluoride pellets) cooled to -78 ° C.

  As a result of performing GC analysis and GC-MS analysis on the reaction mixture collected in the glass trap, it was found that this mixture contained 83% hexafluorofuran, 39% pentafluorofuran, and 27% tetrafluorofuran (83 parts). )Met.

(B) Preparation of tetrafluorofuran polymer A glass four-necked reactor equipped with a stirrer, a dropping funnel and a rectifying column (7 theoretical plates) was charged with potassium hydroxide (purity 85%, Wako Pure Chemical Industries, Ltd.). 200 parts) was charged and heated to 150 ° C. to melt potassium hydroxide. When the potassium hydroxide was melted, the stirring blade was rotated with a stirrer, and 80 parts of the mixture containing tetrafluorofuran obtained in the above (a) was dropped from the dropping funnel over 30 minutes. The reaction was continued while dropping, and when the top temperature of the rectifying column reached 17 to 18 ° C, the extraction of the product was started and collected in a glass receiver cooled to -30 ° C. The yield was 11 parts (yield 11%).

When the GC analysis of the obtained product was performed, the purity was 98.5%. Furthermore, when GC-MS analysis and NMR analysis were performed, it was confirmed that the target product was tetrafluorofuran (liquid material).
The spectrum data of the obtained tetrafluorofuran are shown below.
GC-MS (EI-MS): m / z 140, 112, 93
¹⁹ F-NMR (CFCl ₃ , CDCl ₃ ): -137.3 (2F), -196.2 (2F)

  Subsequently, the obtained tetrafluorofuran was left standing in a stainless steel container for 3 days at room temperature to obtain a white powdery tetrafluorofuran polymer.

(Example 1)
Example 1 was performed using an apparatus having the configuration shown in FIG.
Into a 0.5 L SUS316 container (1) with a heat-resistant valve (7), 1.28 g of the polymer of tetrafluorofuran (C ₄ F ₄ O) obtained in Production Example 1 was charged. Set in the furnace. The valve-out was connected to the plasma etching apparatus (10) via a mass flow controller (MFC) (6). The substrate (8) was placed in the chamber (4) of the plasma etching apparatus (10). In the figure, the arrow indicates the direction of gas flow.

  As the substrate (8), a silicon oxide film having a thickness of about 2 μm is formed on a silicon substrate, and a photoresist is coated and exposed to a thickness of 4000 mm to form a 0.13 μm resist pattern. What was done was used.

  The temperature of the electric furnace was gradually increased and finally reached 420 ° C. The generated tetrafluorofuran gas (tetrafluorofuran concentration: 0.016 mol / liter) was adjusted by a mass flow controller (MFC) (6) to a flow rate of 30 sccm and introduced into the chamber (4). As inert gas, Ar was supplied from the cylinder (2) at a flow rate of 500 sccm, and oxygen gas was supplied from the cylinder (3) at a flow rate of 30 sccm, respectively, and the pressure in the system was maintained at 0.01 kPa. The flow rates of inert gas and oxygen gas were also adjusted by a mass flow controller (MFC) (6).

Next, etching was performed under the conditions of a microwave power source power of 1200 W (2.45 GHz) and a substrate bias power of 1000 W (800 KHz). Note that the plasma density during etching was 10 ¹¹ ions / cm ³ .

  When etching is performed, the etching rate of the silicon oxide film is 590 nm / min at the center and 520 nm / min at the edge, and the etching rate of the resist is 37 nm / min at the center and 49 nm / min at the edge. The ratio was 15.9 at the center and 10.6 at the edge.

(Example 2)
In Example 1, except that the plasma etching apparatus (10) was changed to a film forming apparatus by the plasma CVD method, a film was formed by operating in the same manner as in Example 1 to generate gas by thermal decomposition. A silicon oxide film wafer having aluminum deposited on a part of the surface was used as a substrate, and a microwave CVD film forming apparatus was used as a film forming apparatus by plasma CVD, and film formation was performed under the following conditions.

Tetrafluorofuran (C ₄ F ₄ O) gas flow rate: 80 sccm
Argon flow rate: 300 sccm
Pressure: 0.013 kPa
RF output (frequency 2.45 GHz): 1500 W
Shower head temperature: 280 ° C
Substrate temperature: 200 ° C
Chamber wall temperature: 300 ° C

  By treating under the above conditions, a fluorocarbon film having a thickness of 0.2 μm could be formed on the silicon oxide film wafer. This film was fine and uniform with no voids, and had good adhesion to the substrate.

It is a schematic diagram of an example of the apparatus for enforcing the plasma processing method of Example 1. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reaction container, 2 ... Cylinder filled with inert gas, 3 ... Cylinder filled with oxygen gas, 4 ... Chamber, 5 ... High frequency generator, 6 ... Mass flow controller (MFC), 7 ... Heat-resistant valve, 8 ... Substrate, 10 ... plasma etching equipment

Claims (9)

A polymer comprising a repeating unit represented by the formula: C ₄ F ₄ O is thermally decomposed to obtain an oxygen-containing fluorine compound represented by the formula: C ₄ F ₄ O, and then the obtained oxygen-containing fluorine compound. Is supplied to the plasma processing apparatus. A method for supplying an oxygen-containing fluorine compound to the plasma processing apparatus.   When supplying the oxygen-containing fluorine compound obtained by thermally decomposing the polymer to a plasma processing apparatus, the oxygen-containing fluorine compound is supplied at a concentration of 0.0001 to 0.02 mol / liter. The supply method according to claim 1.   The supply method according to claim 1 or 2, wherein the oxygen-containing fluorine compound is tetrafluorofuran.   The supply method according to claim 1, wherein the plasma processing apparatus is a plasma etching apparatus or a film forming apparatus using a plasma CVD method. A polymer comprising a repeating unit represented by the formula: C ₄ F ₄ O is thermally decomposed to obtain an oxygen-containing fluorine compound represented by the formula: C ₄ F ₄ O, and then the obtained oxygen-containing fluorine compound. Is supplied to a plasma processing apparatus, the oxygen-containing fluorine compound is converted into plasma in the apparatus, and the object to be processed is plasma-processed.   When supplying the oxygen-containing fluorine compound obtained by thermally decomposing the polymer to a plasma processing apparatus, the oxygen-containing fluorine compound is supplied at a concentration of 0.0001 to 0.02 mol / liter. The plasma processing method according to claim 5.   The plasma processing method according to claim 5 or 6, wherein the oxygen-containing fluorine compound is tetrafluorofuran.   The plasma processing method according to claim 5, wherein the plasma processing apparatus is a plasma etching apparatus or a film forming apparatus using a plasma CVD method. A method for manufacturing a semiconductor device, comprising using the plasma processing method according to claim 5.

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