阅读说明：本技术 晶片杯 (Wafer cup ) 是由 今村均 向井惠吏 于 2020-02-28 设计创作，主要内容包括：提供一种晶片杯,其为包含含有四氟乙烯单元和氟代(烷基乙烯基醚)单元的共聚物的晶片杯,其中,内表面的至少一部分的水接触角为80度以下。(Provided is a wafer cup comprising a copolymer containing a tetrafluoroethylene unit and a fluoro (alkyl vinyl ether) unit, wherein at least a part of the inner surface has a water contact angle of 80 degrees or less.)

1. A wafer cup comprising a copolymer containing tetrafluoroethylene units and fluoro (alkyl vinyl ether) units, wherein,

the water contact angle of at least a part of the inner surface is 80 degrees or less.

2. The wafer cup according to claim 1, wherein the content of the fluoro (alkyl vinyl ether) unit of the copolymer is 3.5 to 7.0 mass% with respect to the entire monomer units.

3. The wafer cup of claim 1 or 2 wherein said copolymer has a melt flow rate of 1g/10 min to 30g/10 min at 372 ℃.

Technical Field

The present invention relates to a wafer cup used in a semiconductor manufacturing process.

Background

Semiconductor manufacturing processes typically include a process in which a wafer is treated with water or reagents. As an apparatus used in such a treatment process, for example, patent document 1 describes a semiconductor cleaning apparatus including a wafer spin base such as a turntable for rotatably fixing a wafer to be cleaned on an upper surface, the wafer spin base being disposed in a wafer cup formed of a concave container.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2012 and 54269

Disclosure of Invention

Problems to be solved by the invention

The invention aims to provide a wafer cup which is difficult to generate friction electrification and peeling electrification.

Means for solving the problems

According to the present invention, there is provided a wafer cup comprising a copolymer containing a tetrafluoroethylene unit and a fluoro (alkyl vinyl ether) unit, wherein at least a part of an inner surface has a water contact angle of 80 degrees or less.

The content of the fluoro (alkyl vinyl ether) unit in the copolymer is preferably 3.5 to 7.0% by mass based on the total monomer units.

The melt flow rate of the above copolymer at 372 ℃ is preferably 1g/10 min to 30g/10 min.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a wafer cup in which frictional electrification and peeling electrification are less likely to occur.

Drawings

Fig. 1 is a sectional view of a wafer cup and a wafer processing apparatus using the same according to an embodiment of the present invention.

Fig. 2 is a diagram for explaining an evaluation method in the example of the present invention.

Detailed Description

The present invention will be described in detail with reference to specific embodiments, but the present invention is not limited to the embodiments described below.

The wafer cup of the present invention is a wafer cup comprising a copolymer containing a tetrafluoroethylene unit and a fluoro (alkyl vinyl ether) unit, wherein at least a part of the inner surface has a water contact angle of 80 degrees or less.

Here, fig. 1 is a cross-sectional view of a wafer processing apparatus according to an embodiment of the present invention. As shown in fig. 1, a wafer processing apparatus according to an embodiment of the present invention is an apparatus including: the wafer 40 is held by a chuck mechanism or the like on the wafer spin base 30 rotatable by the rotation mechanism 20, and the wafer 40 is rotated by rotating the wafer spin base 30 by the action of the rotation mechanism 20 while water or a reagent is supplied from the nozzle 50, thereby processing the wafer 40. In fig. 1, a configuration including one nozzle 50 for supplying water or a reagent is illustrated, but the number of nozzles 50 is not particularly limited, and may be 2 or more, and the nozzles 50 may be disposed at positions where water or a reagent is supplied to the lower surface side of the wafer 40.

In the wafer processing apparatus according to the embodiment of the present invention, as shown in fig. 1, a wafer cup 10 is provided so as to surround a wafer spin base 30 and a wafer 40. According to the wafer processing apparatus of the embodiment of the present invention, the wafer cup 10 surrounds the wafer spin base 30 and the wafer 40, and thus, when a part of the water or the reagent supplied to the wafer 40 is scattered from the wafer spin base 30 and the wafer 40, the wafer processing apparatus functions as a scattering suppressing member for suppressing the scattering of the water or the reagent to the outside.

In one embodiment of the present invention, the wafer cup of the present invention is suitably used as the wafer cup 10.

Here, the wafer cup 10 shown in fig. 1 and the wafer cup disclosed in patent document 1 are generally large-sized and require excellent chemical resistance, and therefore are manufactured by cutting a polytetrafluoroethylene block.

However, cutting of the polytetrafluoroethylene block requires a large time burden and an economical burden, and thus a new material and a new manufacturing method are required. As a method for producing a fluoropolymer molded article, a method of melt molding a melt-processable fluoropolymer is known.

On the other hand, it is known that: when a large molded article obtained by molding a fluoropolymer is used as a wafer cup, scattered water, reagents, and the like adhere to the wafer cup, and when these become droplets and flow on the surface of the wafer cup, the wafer cup is charged by frictional electrification or peeling electrification with the droplets. Specifically, it can be seen that: when the liquid droplets adhering to the wafer cup surface move on the wafer cup surface (for example, when the liquid droplets flow down on the wafer cup surface), frictional electrification or peeling electrification is caused by the movement, and the wafer cup is electrified. Once the fluoropolymer containing wafer cup is charged, the charge is not readily released. Therefore, the droplets flying toward the wafer cup are returned to the wafer in an electrostatically charged state by electrostatic repulsion, and a problem is caused by the electrostatic charging of the wafer cup, which is presumed to occur in the semiconductor device. Therefore, the countermeasure against static electricity in the production line in the semiconductor manufacturing process is an important issue that affects the "yield" of the production of semiconductor devices.

Further, as a method of making frictional electrification and peeling electrification difficult, a method using a carbon-based antistatic agent is considered, but if a carbon-based antistatic agent is used, there is a problem of contamination due to elution.

In contrast, the wafer cup of the present invention is a molded article used for the purpose of surrounding a wafer as a wafer processing apparatus for supplying water or a reagent to the wafer while rotating the wafer, for example, like the wafer cup 10 shown in fig. 1, the molded article containing a copolymer containing a tetrafluoroethylene unit and a fluoro (alkyl vinyl ether) unit, and having a water contact angle of at least a part of an inner surface (at least a part of a surface surrounding the wafer in the embodiment of fig. 1) adjusted to 80 degrees or less. In the wafer cup of the present invention, since the water contact angle of at least a part of the inner surface is adjusted to 80 degrees or less, frictional electrification and peeling electrification are less likely to occur, and thus the above-described problem can be appropriately solved.

The wafer cup of the present invention has a water contact angle of 80 degrees or less, and is preferably 70 degrees or less, more preferably 60 degrees or less, because the occurrence of frictional electrification and peeling electrification can be further suppressed, and the lower limit is not particularly limited, and is preferably 40 degrees or more in view of ease of production. The water contact angle may be a water contact angle with respect to at least a part of the surface surrounding the wafer, and may be a water contact angle with respect to the entire surface surrounding the wafer, or a water contact angle with respect to a portion of the surface surrounding the wafer where water or a reagent scattered from the wafer may adhere to the surface.

In the case where the wafer cup of the present invention is the wafer cup 10 used in the wafer processing apparatus shown in fig. 1, the water contact angle may be a water contact angle over the entire surface surrounding the surfaces of the wafer spin base 30 and the wafer 40, or a water contact angle with respect to a portion of the surface surrounding the wafer spin base 30 and the wafer 40 to which water or a reagent scattered from the wafer may adhere.

In the present invention, the water contact angle is measured using a contact angle meter.

The wafer cup of the present invention comprises a copolymer containing tetrafluoroethylene units (TFE units) and fluoro (alkyl vinyl ether) units (FAVE units) (hereinafter referred to as TFE/FAVE copolymer (or PFA)).

The TFE/FAVE copolymer is preferably a melt-processable fluororesin. In the present invention, melt processability means that a polymer can be processed by melting it using an existing processing apparatus such as an extruder or an injection molding machine. Therefore, the melt flow rate of the melt-processable fluororesin is usually 0.01g/10 min to 500g/10 min as measured by the measurement method described later.

The content of the FAVE-based monomer unit in the TFE/FAVE copolymer is preferably 1.0 to 10 mass%, more preferably 2.0 mass% or more, further preferably 3.5 mass% or more, particularly preferably 4.0 mass% or more, more preferably 8.0 mass% or less, further preferably 7.0 mass% or less, particularly preferably 6.5 mass% or less, and most preferably 6.0 mass% or less, based on the total monomer units. The amount of the above-mentioned FAVE-based monomer unit is determined by¹⁹F-NMR method.

The FAVE constituting the above-mentioned FAVE unit includes at least one selected from the group consisting of a monomer represented by the general formula (1) and a monomer represented by the general formula (2).

CF₂＝CFO(CF₂CFY¹O)_p-(CF₂CF₂CF₂O)_q-R^f (1)

(in the formula, Y¹Represents F or CF₃，R^fRepresents a perfluoroalkyl group having 1 to 5 carbon atoms. p represents an integer of 0 to 5, and q represents an integer of 0 to 5. )

CFX＝CXOCF₂OR² (2)

(wherein X's are the same or different and represent H, F or CF)₃，R²Represents a linear or branched fluoroalkyl group having 1 to 6 carbon atoms which may contain 1 to 2 at least one atom selected from the group consisting of H, Cl, Br and I, or a cyclic fluoroalkyl group having 5 or 6 carbon atoms which may contain 1 to 2 at least one atom selected from the group consisting of H, Cl, Br and I. )

Among these, the above FAVE is preferably a monomer represented by the general formula (1), more preferably at least one selected from the group consisting of perfluoro (methyl vinyl ether), perfluoro (ethyl vinyl ether), and perfluoro (propyl vinyl ether) (PPVE), and still more preferably PPVE.

The TFE/FAVE copolymer is not particularly limited, but is preferably a copolymer in which the molar ratio of TFE units to FAVE units (TFE units/FAVE units) is 70/30 or more and less than 99/1. The molar ratio is more preferably from 70/30 to 98.9/1.1, and still more preferably from 80/20 to 98.9/1.1. When the amount of the TFE unit is too small, mechanical properties tend to be deteriorated; when the amount of the TFE unit is too large, the melting point tends to be too high, and the moldability tends to be lowered.

The TFE/FAVE copolymer is preferably a copolymer in which a monomer unit derived from a monomer copolymerizable with TFE and FAVE is 0.1 to 10 mol% and a total of the TFE unit and the FAVE unit is 90 to 99.9 mol%.

Examples of monomers copolymerizable with TFE and FAVE include Hexafluoropropylene (HFP) and CZ³Z⁴＝CZ⁵(CF₂)_nZ⁶(in the formula, Z³、Z⁴And Z⁵Identical or different, represents H or F, Z⁶H, F or Cl, n is an integer of 2 to 10) and a process for producing the sameRadical monomer, and CF₂＝CF-OCH₂-Rf⁷(wherein Rf⁷A perfluoroalkyl group having 1 to 5 carbon atoms), and the like. Among them, HFP is preferable.

The TFE/FAVE copolymer is preferably at least one selected from the group consisting of a copolymer composed of TFE units and FAVE units alone and the TFE/HFP/FAVE copolymer described above, and more preferably a copolymer composed of TFE units and FAVE units alone.

The TFE/FAVE copolymer has a melting point of preferably 280 to 322 ℃, more preferably 290 ℃ or higher, and still more preferably 315 ℃ or lower. The melting point can be measured by using a differential scanning calorimeter [ DSC ].

The glass transition temperature (Tg) of the TFE/FAVE copolymer is preferably 70 to 110 ℃, more preferably 80 ℃ or higher, and still more preferably 100 ℃ or lower. The glass transition temperature can be measured by dynamic viscoelasticity measurement.

The TFE/FAVE copolymer has a Melt Flow Rate (MFR) at 372 ℃ of preferably 0.1g/10 min to 100g/10 min, more preferably 0.5g/10 min or more, further preferably 1g/10 min or more, further preferably 80g/10 min or less, further preferably 40g/10 min or less, and particularly preferably 30g/10 min or less. MFR is a value obtained using a melt flow index meter (manufactured by Anthraian Seiko Seisakusho Co., Ltd.) as the mass (g/10 min) of a polymer flowing out of a nozzle having an inner diameter of 2.1mm and a length of 8mm at 372 ℃ under a 5kg load per 10 min in accordance with ASTM D1238.

Since the TFE/FAVE copolymer is less likely to cause molding failure due to foaming caused by thermal decomposition of the functional group, the amount of the copolymer is 10 parts by weight⁶The carbon atoms preferably have a total of 0 to 1000 functional groups. Relative to each 10⁶The number of carbon atoms and functional groups is more preferably 0 to 700, still more preferably 500 or less, and still more preferably 300 or less.

The functional group is a functional group present at the end of the main chain or the end of a side chain of the TFE/FAVE copolymer, and a functional group present in the main chain or the side chain. The functional group is preferably selected from the group consisting of-CF ═ CF₂、-CF₂H、-COF、-COOH、-COOCH₃、-CONH₂and-CH₂At least one of the group consisting of OH.

For the identification of the kind of the functional group and the measurement of the number of the functional group, infrared spectroscopic analysis can be used.

The number of functional groups is specifically measured by the following method. First, the TFE/FAVE copolymer was melted at 330 to 340 ℃ for 30 minutes and compression-molded to produce a film having a thickness of 0.25 to 0.3 mm. The film was analyzed by fourier transform infrared spectroscopy to obtain the infrared absorption spectrum of the TFE/FAVE copolymer, and a differential spectrum from a background spectrum that was completely fluorinated without the presence of functional groups. From the absorption peaks of the specific functional groups appearing in the differential spectrum, each 1X 10 of the TFE/FAVE copolymer was calculated from the following formula (A)⁶Number of functional groups N of carbon atoms.

N＝I×K/t(A)

I: absorbance of the solution

K: correction factor

t: thickness of film (mm)

For reference, the absorption frequency, molar absorption coefficient and calibration coefficient for the functional groups in the present invention are shown in table 1. In addition, the molar absorption coefficient was determined from FT-IR measurement data of a low molecular model compound.

[ Table 1]

TABLE 1

Note that-CH₂CF₂H、-CH₂COF、-CH₂COOH、-CH₂COOCH₃、-CH₂CONH₂The absorption frequency ratios of (A), (B), (C) and (C) are shown in the table respectively₂H. -COF, -COOH free and-COOH bound, -COOCH₃、-CONH₂The absorption frequency of the optical fiber is lower by dozens of Keystone (cm-¹)。

Thus, for example, the functional number of-COF means a radical composed of-CF₂COF induced absorption frequency 1883cm-¹The number of functional groups determined from the absorption peak of (2) and-CH₂COF induced absorption frequency of 1840cm-¹The total number of functional groups obtained from the absorption peak of (1).

The number of the functional groups may be-CF ═ CF₂、-CF₂H、-COF、-COOH、-COOCH₃、-CONH₂and-CH₂The total number of OH groups.

The functional group is introduced into the TFE/FAVE copolymer by, for example, a chain transfer agent or a polymerization initiator used in the production of the TFE/FAVE copolymer. For example, in the case of using an alcohol as a chain transfer agent, or using a compound having-CH₂When a peroxide having an OH structure is used as a polymerization initiator, a-CH group is introduced into the main chain end of the TFE/FAVE copolymer₂And (5) OH. Further, the functional group is introduced into the end of the side chain of the TFE/FAVE copolymer by polymerizing a monomer having the functional group.

The TFE/FAVE copolymer can be produced by a conventionally known method such as emulsion polymerization or suspension polymerization, by appropriately mixing monomers to be the constituent units thereof and additives such as a polymerization initiator.

The wafer cup of the present invention may contain other components than the TFE/FAVE copolymer, if necessary. Examples of the other components include additives such as a crosslinking agent, a heat stabilizer, a foaming agent, a foam nucleating agent, an antioxidant, a surfactant, a photopolymerization initiator, an anti-wear agent, and a surface modifier.

In the present invention, the wafer cup is not particularly limited in size, and may be large. The wafer cup of the present invention may have, for example, a larger projected area than a wafer (semiconductor wafer) having a diameter of at least 300mm or at least 450 mm. The projected area of the wafer cup of the present invention is preferably 1000cm²Above, more preferably 1100cm²Above, 5000cm²The following. The shape of the wafer cup having a projected area within the above range is not particularly limited as long as it can surround the wafer, and may be a cylindrical shape, a wooden bowl shape, a box shape, a cage shape, or the like, as long as the projected area of the wafer cup is viewed from any directionThe maximum projected area in the product may be within the above range. In the case where the wafer cup of the present invention is an injection molded article obtained by injection molding, the projected area in the injection direction is preferably within the above range. The projected area in the injection direction is an area seen when the injection-molded article is viewed from the nozzle direction of the injection molding machine, that is, a projected area in the nozzle direction. Further, the injection-molded article having a projected area in the injection direction within the above range preferably has an injection area spread ratio of 3000 or more. The injection area ratio is an injection area spread ratio in a direction perpendicular to the injection direction, that is, a ratio of an opening area of the nozzle portion leading end to a projected area of the injection-molded article.

The wafer cup of the present invention is preferably a wafer cup for surrounding a wafer of a wafer processing apparatus that supplies water or a reagent to the wafer while rotating the wafer, and therefore, for example, an injection molded article having a cylindrical portion capable of surrounding a wafer (semiconductor wafer) having a diameter of at least 300mm or at least 450mm can be produced. The cylindrical portion of the injection-molded article is also preferably a portion surrounding a holding means such as a spin base, or a spin chuck for holding a wafer. In one embodiment shown in fig. 1, a wafer cup 10 comprising the wafer cup of the present invention has a cylindrical portion surrounding a wafer spin base 30 and a wafer 40. In the embodiment shown in fig. 1, the wafer cup 10 has a cylindrical shape having a cylindrical portion closed at the bottom, but the shape is not particularly limited, and may be a wooden bowl shape, a box shape, a cage shape, or the like.

In the present invention, the wafer processing apparatus is not particularly limited, and examples thereof include: a semiconductor cleaning device for cleaning a wafer with water or a reagent; a semiconductor manufacturing apparatus for forming a resist film by applying a resist; a semiconductor manufacturing apparatus for developing the resist film; in these apparatuses, water or a reagent is supplied onto the wafer while rotating the wafer. Alternatively, the wafer may be dried by spinning the wafer to spin off water or reagents from the wafer. Therefore, water or the reagent is scattered around the wafer. The wafer cup of the present invention can be used as the wafer cup 10 shown in fig. 1, and can be disposed around a wafer in such a manner that scattering of water or a reagent is suppressed. The wafer cup of the present invention is sometimes referred to as a cup shield, splash shield, or the like. The wafer cup of the present invention is less likely to generate frictional electrification and peeling electrification, and therefore, even if the wafer cup is provided so as to surround the wafer, the wafer is less likely to be electrified or charged droplets are less likely to be turned over onto the wafer. Therefore, it can contribute greatly to an improvement in the yield of semiconductor device fabrication. In particular, frictional electrification and peeling electrification are electrification caused by movement of droplets adhering to the surface of the wafer cup when the droplets move on the surface of the wafer cup, and the frictional electrification and peeling electrification are less likely to occur in the wafer cup according to the present invention, and as a result, the above-described problems can be effectively solved.

In the present invention, the wafer processing apparatus for supplying water or a reagent to the wafer while rotating the wafer may be an apparatus for performing a pre-process of a semiconductor, and the wafer cup of the present invention may be used as a member provided in an apparatus for performing a pre-process of a semiconductor, for example. As the semiconductor pre-process, the following process can be mentioned.

a. Cleaning process for cleaning silicon wafer as base plate "

b. "film formation Process" for Forming a thin film as a Circuit Material on a silicon wafer "

c. "resist coating process" for uniformly coating a photoresist (photosensitive liquid) "

d. Exposure Process for transferring Circuit Pattern "

e. "developing process" for dissolving exposed portion of photoresist "

f. "etching Process" for removing a thin film of a substrate exposed by a reagent or ion "

g. Ion implantation step for implanting impurities such as phosphorus to impart electrical characteristics to silicon "

h. "stripping procedure" for removing unwanted photoresist "

In order to perform the above-described steps, the wafer is processed by supplying water or a reagent to the wafer while rotating the wafer, and therefore, the wafer cup of the present invention can be suitably used as a wafer cup for surrounding the wafer in an apparatus used in the above-described steps.

The method for manufacturing the wafer cup of the present invention is not particularly limited, and the wafer cup can be manufactured appropriately by the method for manufacturing the wafer cup described below.

The method for manufacturing a wafer cup according to the present invention is a method for manufacturing a wafer cup including a copolymer (TFE/FAVE copolymer) including a TFE unit and a FAVE unit, and includes a step of performing a plasma treatment on at least a part of a surface thereof. In the method for manufacturing a wafer cup of the present invention, a surface having a small water contact angle can be formed by performing plasma treatment. Therefore, the plasma treatment can be performed over the entire surface thereof. Alternatively, when the wafer processing apparatus is used as a wafer cup for surrounding a wafer in a wafer processing apparatus for supplying water or a reagent to the wafer while rotating the wafer, or when the wafer processing apparatus is used as the wafer cup 10 shown in fig. 1, at least a part of a surface surrounding the wafer may be processed. Further, the plasma treatment may be performed on the entire surface of the surface surrounding the wafer, or may be performed on a portion of the surface surrounding the wafer where water or a reagent scattered from the wafer may adhere.

In the production method of the present invention, the TFE/FAVE copolymer is used, whereby not only the water contact angle of the resulting wafer cup can be sufficiently reduced, but also an effect that a small water contact angle can be maintained for a long time can be obtained. The reason is not clear, but is considered to be due to: by the plasma treatment, not only hydrophilic functional groups are generated on the wafer cup surface, but also polymer molecules near the surface are crosslinked, and the generated hydrophilic functional groups are fixed on the wafer cup surface. In general, polar functional groups generated at the surface have a higher surface free energy (since the dispersion force component decreases, but the dipole force component and the hydrogen bond component increase, in total, and increase) than the bulk (bulk) or the atmosphere, and the surface free energy is more stable when submerged inside the wafer cup, so that molecular motion called internal inversion of polar groups occurs. In particular, in the case of a semi-crystalline polymer such as a TFE/FAVE copolymer, if the crystallinity is low, the polymer chain in the amorphous portion is relaxed and molecular motion is likely to occur, and thus internal inversion is also likely to occur. In the production method of the present invention, by using a TFE/FAVE copolymer and applying a specific plasma treatment condition, polymer molecules on the surface are crosslinked, and molecular motion of hydrophilic functional groups formed on the surface is suppressed, and it is estimated that a small water contact angle can be maintained for a long time.

On the other hand, even if the same perfluoropolymer is used, if another perfluoropolymer not containing a FAVE unit, such as Polytetrafluoroethylene (PTFE) or TFE/HFP copolymer (FEP), is used, it is presumed that the crosslinking of the polymer molecules does not proceed smoothly, and even if a hydrophilic functional group is formed, the polymer molecules disappear at an early stage.

The TFE/FAVE copolymer used in the production method of the present invention includes the same TFE/FAVE copolymer contained in the wafer cup of the present invention, and preferably the same TFE/FAVE copolymer contained in the wafer cup of the present invention.

For forming a surface with a smaller water contact angle, it is preferred to use a TFE/FAVE copolymer having a specific FAVE unit content. The content of the FAVE-based monomer unit in the TFE/FAVE copolymer is preferably 1.0 to 10 mass%, more preferably 2.0 mass% or more, further preferably 3.5 mass% or more, particularly preferably 4.0 mass% or more, more preferably 8.0 mass% or less, further preferably 7.0 mass% or less, particularly preferably 6.5 mass% or less, and most preferably 6.0 mass% or less, based on the total monomer units.

In addition, in order to form a surface having a smaller water contact angle, a functional group-containing TFE/FAVE copolymer is preferably used. By using a functional group-containing TFE/FAVE copolymer, it is presumed that introduction of a hydrophilic functional group by plasma treatment and crosslinking reaction proceed smoothly. It is also presumed that the hydrophilic functional group can be maintained for a long time by introducing the hydrophilic functional group and crosslinking polymer molecules in the vicinity of the surface of the wafer cup. The number of functional groups in this case is preferably 1 or more.

The functional group that the TFE/FAVE copolymer used in the production method of the present invention may have includes the same TFE/FAVE copolymer contained in the wafer cup of the present invention, and preferably the same TFE/FAVE copolymer contained in the wafer cup of the present invention. The number of functional groups may be the same as the number of TFE/FAVE copolymers contained in the wafer cup of the present invention.

The plasma treatment in the manufacturing method of the present invention may be performed as follows: the plasma irradiation treatment can be performed by applying a voltage to the discharge electrode while introducing a gas into a gap between the molded article constituting the wafer cup and the discharge electrode, and performing a plasma irradiation treatment on the surface of the molded article by a plasma gas generated between the molded article constituting the wafer cup and the discharge electrode.

The plasma treatment in the production method of the present invention is preferably a vacuum plasma treatment or an atmospheric pressure plasma treatment because a surface having a smaller water contact angle can be formed efficiently, and is more preferably an atmospheric pressure plasma treatment because the treatment can be performed easily for a short time under normal pressure, the discharge state is very stable and homogeneous, and the spatial uniformity of the generated radicals is high.

The treatment time of the atmospheric pressure plasma treatment is preferably 5 seconds or more, more preferably 10 seconds or more, and preferably 50 seconds or less, more preferably less than 50 seconds, further preferably 45 seconds or less, further preferably 40 seconds or less, further preferably 35 seconds or less, particularly preferably 30 seconds or less, and most preferably 25 seconds or less, because a surface having a smaller water contact angle can be formed efficiently. On the other hand, in the case of vacuum plasma, the processing time is about several tens of seconds to 10 minutes depending on the kind of gas, the degree of vacuum, the size of the chamber, the distance between electrodes, and the like.

In the production method of the present invention, it is preferable that the molded article heated to a surface temperature of 150 ℃ or higher is subjected to plasma treatment. In the present invention, the surface temperature at the time of plasma treatment is the highest temperature of the surface of the molded article during plasma irradiation. If the surface temperature during plasma treatment is too low, the contact angle of the obtained wafer cup cannot be sufficiently lowered, or the molecular mobility of polymer molecules present in the vicinity of the surface of the wafer cup cannot be sufficiently increased, and the crosslinking reaction of polymer molecules in the vicinity of the surface cannot be promoted, so that a small water contact angle cannot be maintained for a long time.

In the production method of the present invention, the surface temperature of the molded article subjected to the plasma treatment can be measured using THERMO paper (THERMO LABEL) manufactured by japan oil research and development industries.

The upper limit of the surface temperature at the time of plasma treatment is preferably not more than the melting point of the TFE/FAVE copolymer, from the viewpoint of suppressing thermal deformation of the molded article constituting the wafer cup. The surface temperature at the time of plasma treatment is more preferably 155 ℃ or higher, more preferably 280 ℃ or lower, and further preferably 240 ℃ or lower. If the surface temperature during plasma processing is too high, the shape of the resulting wafer cup may be damaged.

Further, since PTFE has non-melt processability, the shape of the molded article does not change greatly even if the surface is raised to a very high temperature. Therefore, by utilizing this property of PTFE, for example, when a PTFE molded article having irregularities on the surface is subjected to plasma treatment, the surface can be smoothly melted only by raising the temperature to a very high temperature. On the other hand, since TFE/FAVE copolymers generally have melt processability, if the surface temperature at the time of plasma treatment is made very high, the shape of the original molded article may be damaged.

The method of controlling the surface temperature during plasma treatment is not particularly limited, and examples thereof include a method of controlling the surface temperature under plasma treatment conditions, a method of controlling the surface temperature by an external heating device, and the like. For example, in the case of the atmospheric pressure plasma processing, the temperature can be naturally raised to a desired temperature range by adjusting the power density or the processing time. When a molded product of TFE/FAVE copolymer is subjected to atmospheric plasma treatment for a long time, the temperature naturally rises to a temperature higher than the melting point, and the shape of the molded product may be damaged. In addition, when a pulse modulation frequency is used or vacuum plasma treatment is used, since it is difficult for the plasma treatment to increase the surface temperature of the molded article, a method of raising the surface temperature of the molded article to 140 to 240 ℃ by an external heating device and then performing the plasma treatment, a method of providing a heating means in a plasma treatment apparatus and heating, or the like is suitably used. Examples of the heating means include a heater, a hot plate heater having an electric heating coil built therein, and a halogen lamp.

The structure of the electrode used for the plasma treatment is not particularly limited, and is preferably a structure suitable for the shape of the obtained wafer cup. The material of the high-voltage side electrode and the ground side electrode is not particularly limited as long as it is an electrically conductive material, and in the case of a metal, an alloy such as stainless steel, brass, carbon steel, and super steel, copper, aluminum, or the like may be used, and these may be used alone or in an appropriate combination. Alternatively, a material obtained by applying a transparent conductive material such as copper, gold, or a metal oxide to the surface of a non-conductive plastic or ceramic and then performing a conductive treatment may be used.

The plasma treatment may use a reactive gas or a mixed gas of a reactive gas and an excited gas. Examples of the reactive gas include air, hydrogen, oxygen, ammonia, water vapor, and methane. Examples of the excited gas include argon, helium, and nitrogen. Examples of the mixed gas include a mixed gas of oxygen and argon, and a mixed gas of oxygen and nitrogen. The volume ratio of the reactive gas to the excited gas (reactive gas/excited gas) may be in the range of 0.5/100 to 1.5/100. The oxygen concentration in the gas used may be in the range of 0.0005 vol% to 0.3 vol%.

In particular, when oxygen is used, a hydrophilic functional group is formed on the surface of the molded article, and it can be expected that the water contact angle is sufficiently lowered. However, if the oxygen amount is too large for the excited gas such as helium or argon, the electric energy for maintaining the discharge may increase. When the electric energy is increased, the surface of the molded article may be damaged, and the water contact angle may be increased. Therefore, when a mixed gas of oxygen and an excited gas is used for the plasma treatment, the volume ratio of oxygen to excited gas (oxygen/excited gas) is preferably in the range of 0.5/100 to 1.5/100.

Helium as an excited gas is known to be activated by being excited to a high level in plasma by emission spectrometry, and He and O are known to be activated₂Capable of efficiently dissociating oxygen by reactionLike process gases, are prone to generate atomic oxygen (penning effect).

The plasma treatment may be performed by a batch method, or may be performed by a continuous method such as treatment using a conveyor mechanism.

Next, the processing conditions in the case of the atmospheric pressure plasma processing will be described. Examples of the reaction apparatus used for the atmospheric pressure plasma treatment include a flow tube type of an external electrode, a bell jar type of an internal electrode, and the like.

The voltage frequency of the high-frequency power source used for the atmospheric pressure plasma treatment is preferably 50Hz to 2.45 GHz. In addition, as the high frequency for stably generating a uniform plasma space, 13.56MHz is recommended. The power density per unit area of the electrode is usually 5W/cm²～50W/cm²Preferably 10W/cm²～30W/cm²When the molded article is heated at a certain high voltage, the crosslinking reaction of the polymer molecules tends to be easily progressed. The pressure during the atmospheric plasma treatment may be in the range of 500hPa to 1300hPa (375 Torr to 975 Torr).

The distance between the electrode used for the atmospheric plasma treatment and the molded article is preferably 0.5mm to 5mm, more preferably 1mm to 5mm, because a desired effect can be obtained even at a relatively low voltage and the safety and economy are excellent.

The gas flow rate in the atmospheric pressure plasma treatment may be 50 cc/min to 500 cc/min (normal pressure). More preferably 10 cc/min to 400 cc/min (normal pressure).

Next, the processing conditions when the vacuum plasma processing is performed will be described. The voltage frequency used for the vacuum plasma treatment is preferably 5Hz to 15 MHz. As a vacuum apparatus used for vacuum plasma treatment, a rotary pump is preferable because of its high efficiency. The pressure during the vacuum plasma treatment is usually 0.01 to 10 torr (1.3 to 1330Pa), preferably 0.1 to 2 torr (13.3 to 266Pa), because the discharge is stable and a sufficient treatment rate can be obtained.

The gas flow rate in the vacuum plasma treatment may be 5 cc/min to 50 cc/min (normal pressure). The gas flow rate can be adjusted using a needle valve. Other processing conditions may be the same as the preferable processing conditions of the atmospheric pressure plasma processing.

The production method of the present invention preferably further comprises a step of obtaining a molded article constituting the wafer cup by molding the TFE/FAVE copolymer. The step of obtaining a molded article is preferably performed before the step of performing plasma treatment.

As a method for molding the TFE/FAVE copolymer, a method of heating the TFE/FAVE copolymer to a melting point or higher to melt the copolymer and molding the copolymer can be used. The method for molding the above-mentioned TFE/FAVE copolymer is not particularly limited, and known methods such as extrusion molding, injection molding, transfer molding, inflation molding, and compression molding may be mentioned. These molding methods may be appropriately selected according to the shape of the obtained wafer cup.

Examples of the method for molding the above-mentioned TFE/FAVE copolymer include known methods such as extrusion molding, injection molding, transfer molding, inflation molding and compression molding. Among these molding methods, injection molding is preferable because a large wafer cup can be easily manufactured.

In the manufacturing method of the present invention, when a molded article constituting a wafer cup is obtained by injection molding, after the injection molded article is obtained by injection molding, the injection molded article is supplied to a plasma processing apparatus and is subjected to plasma processing. As a plasma processing method for performing plasma processing, for example, there are known: a method of performing plasma processing under atmospheric pressure using an atmospheric pressure plasma processing apparatus (for example, japanese patent laid-open No. 5-309787); a method of performing plasma treatment under an ammonia atmosphere (for example, mitsubishi electric wire industry press, No. 7, 2007, pages 78 to 84); and the like. In the injection-molded article supplied to the plasma processing apparatus, a voltage is applied to the discharge electrode while introducing a gas into a gap between the injection-molded article and the discharge electrode, and plasma irradiation treatment can be performed on the inner surface of the injection-molded article surrounding the wafer by using a plasma gas generated between the inner side of the injection-molded article and the discharge electrode. In this case, the entire inner surface of the injection-molded article may be subjected to plasma treatment, a part of the inner surface of the injection-molded article may be subjected to plasma treatment, and a part where water or a reagent scattered from the wafer may adhere may be subjected to plasma treatment. The plasma treatment may be performed in a discharge vessel provided with an external electrode, and may be a direct type using dielectric discharge, or a remote type in which a plasma-activated gas is ejected in a jet manner.

While the embodiments have been described above, it should be understood that various changes in form and details may be made therein without departing from the spirit and scope of the claims.

Examples

Next, embodiments of the present invention will be described with reference to examples, but the present invention is not limited to these examples.

The respective numerical values of the examples were measured by the following methods.

(melting Point)

The temperature was determined as the temperature corresponding to the maximum value in the heat of fusion curve when the temperature was raised at a rate of 10 ℃ per minute using a differential scanning calorimeter [ DSC ].

(MFR)

The mass (g/10 minutes) of a polymer discharged from a nozzle having an inner diameter of 2.1mm and a length of 8mm at 372 ℃ under a load of 5kg per 10 minutes was determined using a melt flow index meter (manufactured by Antahou Seiki Seisaku-Sho Ltd.) according to ASTM D1238.

(content of monomer Unit)

The content of each monomer unit is as follows¹⁹F-NMR method.

(number of functional groups)

The sample is melted at 330 ℃ to 340 ℃ for 30 minutes, and then compression molding is performed to produce a film with a thickness of 0.25mm to 0.3 mm. By means of Fourier transform infrared spectrometer (FT-IR (trade name: 1760X, manufactured by PerkinElmer Co., Ltd.)]The film was scanned 40 times and analyzed to obtain an infrared absorption spectrum, resulting in a differential spectrum with a background spectrum that was completely fluorinated without the presence of functional groups. From the differential spectrumThe absorption peak of the specific functional group appearing in (A) was calculated from the following formula (A) for each 1X 10 of the sample⁶Number of functional groups N of carbon atoms.

N＝I×K/t (A)

I: absorbance of the solution

K: correction factor

t: thickness of film (mm)

For reference, the absorption frequency, molar absorption coefficient and calibration coefficient for the functional groups in the present invention are shown in table 2. In addition, the molar absorption coefficient was determined from FT-IR measurement data of a low molecular model compound.

[ Table 2]

TABLE 2

(Water contact Angle)

The measurement was carried out at room temperature using a contact angle meter (model FACEOTACT-ANGLEMETERCA-D, manufactured by Kyowa interface science).

The molded article subjected to plasma irradiation was subjected to measurement of the water contact angle of the surface treated with plasma irradiation after 1 day from the plasma irradiation.

(electric quantity)

A split pipe having a length of 50mm was produced by cutting a tubular molded article in half in the longitudinal direction, and as shown in fig. 2, the split pipe 60 was inclined at an angle θ of 60 ° with respect to a ground-insulating aluminum plate 70 having a length of 120mm × a width of 120mm × a thickness of 1.5mm so that the height h of the lower end was 70 mm. Then, as shown in FIG. 2, pure water was dropped drop by drop into the groove portion at the upper end of the double-split tube 60 by using a syringe 90 under a condition of 50. mu.L/1 drop, and 10 drops were dropped in total.

By this operation, the dropped water droplets slide down on the groove portions of the split-tube 60, and the split-tube 60 is negatively charged by frictional electrification and peeling electrification while the water droplets falling from the split-tube 60 are positively charged. Due to the positively charged water droplets falling on the aluminum plate 70, free electrons in the aluminum plate 70 move to the side of the water droplet falling surface (upper surface in fig. 2), and as a result, the side of the back surface (lower surface in fig. 2) of the aluminum plate 70 is positively charged by electrostatic induction. At this time, the electric charge amount to the open pipe 60 can be determined by measuring the electric potential on the back side of the aluminum plate 70 with a digital low potential measuring instrument (KSD-3000 manufactured by spring motor). That is, when the total charge amount of 10 droplets of water is + Q, the aluminum plate 70 insulated from the ground receives a charge of + Q, and the absolute value of the charge potential is equal at this time, so that the charge amount on the surface of the double-walled tube 60 is-Q. Therefore, the potential and the charge amount of the split pipe 60 can be obtained by measuring the potential of the aluminum plate 70. In the measurement of the potential of aluminum plate 70, probe 80 provided on the back surface (the surface opposite to the surface on which the water droplet is dropped) side of aluminum plate 70 at a position distant from aluminum plate 70 by a distance d of 10mm was used.

In comparative examples 3 and 5, sheet-like molded articles were used instead of the split tube 60, and the charge amount was measured in the same manner as described above.

In this example, the charge amount was measured for the open tube 60 and the sheet-like molded article, but it can be said that the charge amount does not depend on the shape of the molded article.

(reduction ratio of charged amount)

From the measurement results of the charge amount, the reduction rate of the charge amount was calculated by the following equation.

Charge amount reduction rate (%) (charge amount/charge amount of untreated product) × 100

In comparative examples 1 and 2 and examples 1 to 4, the result of comparative example 1 was used as an untreated product, and in comparative examples 3 and 5, the result of comparative example 3 was used as an untreated product.

Comparative example 1

A TFE/PPVE copolymer 1 (composition ratio (mass%) of TFE to PPVE: 96.5/3.5), melting point: 308 ℃, MFR: 2.0g/10 min, number of functional groups 6 (one/C10)⁶Respectively) were molded to obtain a tubular molded article having an outer diameter of 12mm and an inner diameter of 10 mm. The resulting tubular molded article was evaluated for physical properties. The results are shown in Table 3.

Comparative example 2

The tubular molded article obtained in the same manner as in comparative example 1 was inserted into a double spiral electrode (high frequency power source 13.56MHz) of an atmospheric pressure plasma processing apparatus, and a mixed gas of oxygen and argon (volume ratio (O) of oxygen to argon)₂1/100/Ar) was introduced into the tubular molded article continuously at a gas flow rate of 300 cc/min, and a power density of 20W/cm was applied²The plasma treatment was performed for 3 seconds.

The tubular molded article after the plasma treatment was evaluated for various physical properties. The results are shown in Table 3. In this example, a method using a double spiral electrode is adopted, but a method corresponding to the shape and size of a molded product may be adopted.

Examples 1 to 4

Plasma treatment was carried out in the same manner as in comparative example 2 except that the plasma treatment conditions were changed to the conditions shown in table 3, and the tubular molded articles after the plasma treatment were evaluated for various physical properties. The results are shown in Table 3.

Comparative example 3

A TFE/PPVE copolymer 2 (composition ratio (mass%) of TFE to PPVE: 95.5/4.5), melting point: 306 ℃, MFR: 13.0g/10 min, functional group number 484 (one/C10)⁶One) was molded to obtain a sheet-like molded article having a thickness of 1mm and a square width of 50 mm. The resulting sheet-like molded article was evaluated for physical properties. The results are shown in Table 3.

Example 5

The sheet-like molded article obtained in the same manner as in comparative example 3 was heated to 190 ℃ by external heating means, and then set in a vacuum plasma processing apparatus (high-frequency power supply 13.56MHz) equipped with a pair of electrodes parallel to each other, and ammonia gas was continuously introduced into the processing apparatus at a gas flow rate of 20 cc/min so that the pressure in the processing apparatus was kept at 5.5Pa, and applied at a power density of 20W/cm²The plasma treatment was performed for 20 seconds.

The sheet-like molded article after the plasma treatment was evaluated for various physical properties. The results are shown in Table 3.

[ Table 3]

TABLE 3

The charge amount reduction rate was defined as the charge amount without plasma treatment (i.e., charge amount reduction rate (%) (charge amount/charge amount of untreated material) × 100)

Description of the symbols

10 … wafer cup

20 … rotary mechanism

30 … wafer spin base

40 … wafer

50 … nozzle