TWI554565B - Perfluoroelastomer composition - Google Patents

Description

Perfluoroelastomer composition

The present invention relates to a perfluoroelastomer composition suitable as a sealing material for sealing used in a device used in a thermal diffusion step or a plasma CVD step, and a molded article thereof.

The perfluoroelastomer molding system is used in a large amount in semiconductor manufacturing apparatuses and the like because of its superior chemical stability. The perfluoroelastomer molding system is suitably used in a thermal diffusion furnace or a plasma CVD apparatus or a plasma etching apparatus which requires heat resistance.

In general, a perfluoroelastomer molding system exhibits excellent chemical resistance and heat resistance by the stability and inactivity of a copolymerized perfluorinated monomer unit constituting a main portion of a polymer main chain. The perfluoroelastomer composition can be obtained by crosslinking the peroxide mainly using a peroxide and a co-crosslinking agent. Further, the perfluoroelastomer molded body can be improved in mechanical properties by blending carbon black as a filler.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: International Publication No. WO2000/000054

Patent Document 2: Japanese Patent Laid-Open No. 2011-32465

However, decomposition of fluorine occurs in the thermal diffusion step or the plasma CVD step. The decomposition products affect the sealing material used in the device such as the thermal diffusion furnace and the peripheral devices connected to the device, such as the exhaust device, causing problems such as deterioration of the sealing material.

An elastomer molded article comprising a carbon black filler having an impurity metal content of 300 ppm or less and an average particle diameter of 700 μm or less by an ashing analysis method is described in WO2000/042093. The crosslinkable elastomer composition of the cross-linking elastomer component is obtained by cross-linking molding, wherein the content of the impurity metal in the molded article by the ashing analysis method is 100 ppm or less, and the particle growth rate by the oxygen plasma irradiation It is 500% or less. In addition, it is described that the carbon black filler to be blended in the crosslinkable elastomer composition preferably has a specific surface area of 3 m ² /g or more and a DBP oil absorption of 15 ml/100 g or more from the viewpoint of workability. However, the elastomer molded article described in WO2000/042093 is used to suppress the generation of particles (impurity fine particles) from the elastomer molded article in a dry step such as plasma etching in the semiconductor manufacturing step, or to solve the problem. The problem of metal dissolution of the elastomer molded article used in the wet process such as washing is not the case of solving the resistance to the fluorine decomposition product.

In addition, it is described that the carbon black is blended in an amount of 5 to 60 parts by mass based on 100 parts by mass of the vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene-based copolymer rubber in JP-A-2011-32465. A rubber member obtained by cross-linking a rubber composition. The carbon black system preferably has a nitrogen specific surface area of 5 to 80 m ² /g and a DBP oil absorption of 150 ml/100 g or less from the viewpoint of mixing workability and formability. However, the rubber member of Japanese Laid-Open Patent Publication No. 2011-32465 is one in which the abrasive powder generated from the rubber member is less resistant to adhesion to the conveyed material and superior in resistance to phosphoric acid, hydrochloric acid, nitric acid, etc., and is not solved for the fluorine decomposition product. Tolerant.

Accordingly, an object of the present invention is to provide a perfluoroelastomer composition which exhibits excellent resistance to a fluorine-decomposed substance and a molded body thereof.

Based on the above-mentioned actual situation, the inventors of the present invention have conducted a careful study and found that, in the case of an elastomer molded article in which a perfluoroelastomer composition having a specific carbon black has been blended, it is shown to be thermally diffused. The present invention is completed by the superior resistance of the decomposition product of fluorine generated in the step or the plasma CVD step.

That is, the present invention provides a perfluoroelastomer composition containing a perfluoroelastomer component and a carbon black having a DBP oil absorption amount (A method) of 90 cm ³ /100 g or more and 600 cm ³ /100 g or less.

Moreover, the present invention provides an elastomer molded body obtained by cross-linking the above-described perfluoroelastomer composition.

The elastomer molded article of the present invention exhibits superior resistance to decomposition products of fluorine. Therefore, in the case where the elastomer molded article of the present invention is used as a sealing material for a device used in a thermal diffusion step or a plasma CVD step, it is possible to exhibit a sealing property which is stable over a long period of time.

The perfluoroelastomer composition of the present invention (hereinafter simply referred to as "elastomer composition") contains a perfluoroelastomer component. The perfluoroelastomer component comprises (a) tetrafluoroethylene, (b) perfluoro(C ₁ -C ₅ alkyl vinyl ether) and/or perfluoro(C ₃ -C ₁₁ alkoxyalkyl vinyl ether) And (c) a copolymer of the hardened site monomers.

The perfluoroalkyl vinyl ether having a carbon number of 1 to 5 in the perfluoro(C ₁ -C ₅ alkyl vinyl ether) alkyl group of the component (b), specifically, a perfluoromethyl vinyl group Ether, perfluoroethyl vinyl ether, perfluoropropyl vinyl ether or the like is preferred, and perfluoromethyl vinyl ether is preferred.

Further, the perfluoroalkoxyalkyl vinyl ether having a total carbon number of 3 to 11 in the perfluoro(C ₃ -C ₁₁ alkoxyalkyl vinyl ether) side chain of the component (b), that is, The alkoxy group and the alkyl group have a total carbon number of 3 to 11 perfluoroalkoxyalkyl vinyl ether, and specifically, CF ₂ =CFOCF ₂ CF(CF ₃ )OC _n F _2n+1 (n) :1~5), CF ₂ =CFO(CF ₂ ) ₃ OC _n F _2n+1 (n:1~5), CF ₂ =CFOCF ₂ CF(CF ₃ )O(CF ₂ O) _m C _n F _{2n +1} (n: 1~5, m: 1~3), CF ₂ = CFO(CF ₂ ) ₂ OC _n F _2n+1 (n: 1~5), etc. These (b) components can be used singly or in combination of two or more.

Examples of the (c) hardening site monomer include a hardening site monomer containing iodine or bromine or a hardening site monomer containing a cyano group. Examples of the hardening site monomer containing iodine or bromine include CF ₂ =CF(CF ₂ ) _n I, CF ₂ =CF(CF ₂ ) _n Br, I(CF ₂ ) _n I and the like. Further, examples of the hardening site monomer containing a cyano group include a perfluorovinyl ether containing a cyano group, and examples thereof include CF ₂ =CFO(CF ₂ ) _n OCF(CF ₃ )CN(n: 2 to 4). , CF ₂ =CFO(CF ₂ ) _n CN(n:2~12), CF ₂ =CFO[CF ₂ CF(CF ₃ )O] _m (CF ₂ ) _n CN(n:2,m:1~5 ), CF ₂ =CFO[CF ₂ CF(CF ₃ )O] _m (CF ₂ ) _n CN(n:1~4,m:1~2), CF ₂ =CFO[CF ₂ CF(CF ₃ )O ] _n CF ₂ CF(CF ₃ )CN(n: 0~4). Among them, preferred is perfluoro(8-cyano-5-methyl-3,6-di -1-octene).

Further, the blending ratio is (a) tetrafluoroethylene of 50 to 75 mol%, preferably 60 to 75 mol%; (b) perfluoro(C ₁ -C ₅ alkyl vinyl ether) and/or Perfluoro(C ₃ -C ₁₁ alkoxyalkyl vinyl ether) is 49.8 to 25 mol %, preferably 39.8 to 25 mol %; (c) hardening site monomer is 0.2 to 5 mol % Preferably, it is 0.5 to 3 mol%.

DBP oil absorption amount of carbon black in the elastomer composition of the formulated preferably 90cm ³ / 100g or more and 600cm ³ / 100g or less, particularly preferably 95cm ³ / 100g or more and 400cm ³ / 100g or less, and still more preferably 95cm ³ /100g or more and 200cm ³ /100g or less. If the DBP oil absorption of the carbon black is less than 90 cm ³ /100 g, the surface becomes easily dissolved when the elastomer molded body is exposed to a fluorine gas heated to a high temperature. The DBP oil absorption refers to the amount of DBP (dibutylphthalic acid) absorbed by 100 g of carbon black (JIS K6221).

The carbon black nitrogen adsorption specific surface area to be blended in the elastomer composition is 50 m ² /g or more and 1300 m ² /g or less, preferably 60 m ² /g or more and 1000 m ² /g or less, and particularly preferably 65 m ^{2 .} /g or more and 200 m ² /g or less. If the specific surface area of the nitrogen of the carbon black is less than 50 m ² /g, the surface becomes easily dissolved when the elastomer shaped body is exposed to a fluorine gas heated to a high temperature. In addition, the nitrogen adsorption specific surface area means the specific surface area (JIS K 6217) obtained from the nitrogen adsorption amount by the S-BET type.

Examples of such carbon black include furnace black or acetylene black such as SAF carbon black, ISAF carbon black, HAF carbon black, and FEF carbon black. Among them, acetylene black is preferred from the viewpoint of excellent resistance to fluorine gas.

The carbon black is blended in an amount of 5 parts by weight or more (more preferably 10 parts by weight or more) or 30 parts by weight or less, and particularly preferably 12 parts by weight or more and 25 parts by weight or less based on 100 parts by weight of the perfluoroelastomer component. More preferably, it is 14 parts by weight or more and 20 parts by weight or less. When the blending amount of the carbon black is less than 5 parts by weight with respect to 100 parts by weight of the perfluoroelastomer component, the surface of the elastomer molded body is easily dissolved when exposed to a fluorine gas heated to a high temperature.

In the elastomer composition of the present invention, as the optional component, various additives corresponding to the requirements of the application can be formulated. Examples of such various additives include stabilizers, plasticizers, lubricants, processing aids, and the like. Moreover, the blending amount of each of the additives can be appropriately determined within a range that does not impair the effects of the present invention.

The elastomer composition of the present invention contains a crosslinking agent. The crosslinking agent to be formulated in the elastomer composition of the present invention can be appropriately selected depending on the kind of the crosslinking group of the elastomer. As the crosslinking reaction, for example, all-oxide cross-linking, polyol cross-linking, polyamine cross-linking, and three Hand over, Well-known cross-linkings such as azole cross-linking, imidazole cross-linking, thiazole cross-linking, and radiation cross-linking.

The amount of the crosslinking agent is usually 0.05 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the perfluoroelastomer component. When the blending amount of the crosslinking agent is less than 0.05 part by weight, the elastomer is not sufficiently crosslinked, and when it exceeds 10 parts by weight, the physical properties of the crosslinked product are deteriorated.

The elastomer composition of the present invention is useful as a molding material for various molded bodies. Further, the elastomer composition of the present invention can be used in particular in the case of a molded article for sealing in a thermal diffusion furnace of a semiconductor wafer. The elastomer composition of the present invention may be a general kneading machine for an elastomer, for example, a hot-melt roll, a Bancher mixer, a kneader, or the like, and the above components such as a perfluoroelastomer component, the carbon black, and a crosslinking agent. It is mixed and prepared.

The elastomer molding system of the present invention is obtained by cross-linking an elastomer composition. In other words, the obtained kneaded material is formed into a predetermined shape, for example, an O-ring or the like, and heated to be crosslinked, whereby the perfluoroelastomer molded body of the present invention can be obtained. The crosslinking conditions may be in accordance with a known method. For example, it may be placed in a mold and held under pressure at 120 to 220 ° C for 1 to 60 minutes to carry out compression crosslinking, followed by 120 to 260 ° C. The furnace is kept for 0.5 to 50 hours, thereby performing the method of crosslinking the hot furnace.

When the elastomer molded article of the present invention is used as a sealing material for sealing (for example, an O-ring) as a thermal diffusion furnace for a semiconductor wafer, the effects of the present invention can be remarkably exhibited. A thermal diffusion furnace for a semiconductor wafer is a material for performing a heat diffusion of impurities toward a wafer in a semiconductor wafer manufacturing process, and is, for example, an impurity diffusion device of Japanese Laid-Open Patent Publication No. Hei 6-45294. Also, thermal diffusion of semiconductor wafers The furnace system includes, for example, an exhaust device around the heat diffusion furnace. When the elastomer molded body of the present invention is used as a sealing material for such a thermal diffusion furnace as, for example, an O-ring, even if it is exposed to a high-temperature fluorine gas generated by a thermal diffusion furnace, the O-ring surface does not dissolve. After the damage, it can show a stable sealing function after a long time.

(Example)

The invention is further illustrated by the following examples, which are merely illustrative and are not intended to limit the invention.

(Example 1) (Manufacture of elastomer)

In a stainless steel pressure cooker with a capacity of 500 ml, 200 ml of distilled water, 2.5 g of ammonium perfluorooctanoate and Na ₂ HPO _{4 were added} . After 12H ₂ O 4.4 g, the inside was replaced with a nitrogen gas, followed by depressurization. After cooling the high temperature pot to 50 ° C, 32 g of tetrafluoroethylene, 68 g of perfluoromethyl vinyl ether, and perfluoro-8-cyano-5-methyl 3,6-di were added. After 6.4 g of 1-octene was heated to 80 ° C, 0.75 g of sodium sulfite and 3.75 g of ammonium persulfate were added, respectively, and polymerization was started as an aqueous solution of 25 ml. After the polymerization was continued for 20 hours, the unreacted gas was purged, and the aqueous latex formed thereon was taken out, salted out with a 10% aqueous solution of sodium chloride, and dried to obtain a ternary of crumb rubber. It is a copolymer of 44 g. As a result of infrared absorption analysis, the ternary copolymer has 62 mol% of tetrafluoroethylene, 37 mol% of perfluoromethyl vinyl ether, and perfluoro-8-cyano-5-methyl 3,6-di 1--1 ^- octene (characteristic absorption of cyano group 2268 cm ^-1 ) 1.0 mole % copolymerization composition.

(Manufacture of O-ring)

100 parts by weight of the elastomer obtained by the above production method, and 1 part by weight of the crosslinking agent 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, using an open roll 5 parts by weight of "carbon black A" was kneaded, and then heat-treated at 190 ° C for 30 minutes, and once subjected to crosslinking, followed by heat treatment at 240 ° C for 48 hours, and secondary crosslinking was carried out to form . The shape of the formed body is made into an O-ring (AS568B-214). Further, the carbon black is calculated based on JIS K 6217 (1997), and the DBP oil absorption amount and the nitrogen adsorption specific surface area are calculated, and the value is a manufacturer type record value. The obtained O ring system was subjected to the following fluorine gas exposure test to evaluate the resistance to high temperature fluorine gas. The results are shown in Table 1.

"Carbon Black A";

"DENKABLACK" (manufactured by Electric Chemical Industry Co., Ltd.; acetylene black) DBP oil absorption 190cm ³ /100g, nitrogen adsorption specific surface area 69m ² /g

(fluorine gas exposure test)

The O-ring of the AS568B-214 size (diameter D: 3.53 mm) was cut into a linear body having a circular cross section, and a test piece obtained by cutting out a line having a length L of 10 mm was obtained (refer to FIG. 1). . Then, the test piece was set in a chamber, and after introducing a 20%-concentration fluorine gas (80% nitrogen) to a pressure of 500 torr, the chamber was heated to 250 ° C for 2 hours.

(evaluation method)

The surface and end faces of the O-ring after the fluorine gas exposure test were observed. In the case of the O-ring which is dissolved by the high-temperature fluorine gas, the dissolution system is generated at the corner portion of the end face of the O-ring as shown in Fig. 2(B), and the end face gradually approaches the spherical surface as the dissolution proceeds. Therefore, the resistance to high-temperature fluorine gas is evaluated by measuring the radius R of the corner portion of the end face of the O-ring. The radius R of the corner portion is photographed by the O-ring of the test along the X-X line of Fig. 2(A), and is obtained by image processing. Therefore, as the radius (mm) is larger, the resistance to high-temperature fluorine gas is deteriorated, and as the smaller, the resistance to high-temperature fluorine gas becomes excellent.

(Example 2)

An O ring was produced in the same manner as in Example 1 except that the following "carbon black B" was used instead of "carbon black A". Further, the carbon black is calculated based on JIS K 6217 (1997), and the DBP oil absorption amount and the nitrogen adsorption specific surface area are calculated, and this value is a manufacturer type record value. The obtained O ring system was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Further, an image of the radius of the corner portion of the end face of the test body after the fluorine gas exposure test was obtained is shown in Fig. 3. In Fig. 3, the black portion is a test body, and the white portion is a circular shape attached by image processing having a radius of a corner portion.

"Carbon Black B";

"SHIYOUBLACKIP1500" (SAF carbon black) (manufactured by Cabot) DBP oil absorption 123cm ³ /100g, nitrogen adsorption specific surface area 180m ² /g

(Example 3)

An O ring was produced in the same manner as in Example 1 except that the following "carbon black C" was used instead of "carbon black A". Further, the carbon black is calculated based on JIS K 6217 (1997), and the DBP oil absorption amount and the nitrogen adsorption specific surface area are calculated, and this value is a manufacturer type record value. The obtained O ring system was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Further, an image of the radius of the corner portion of the end face of the test body after the fluorine gas exposure test was obtained is shown in Fig. 4. In Fig. 4, the black portion is a test body, and the white portion is a circular shape attached by image processing having a radius of a corner portion.

"Carbon Black C";

"旭#70" (HAF carbon black) (made by Asahi Carbon Co., Ltd.) DBP oil absorption 101cm ³ /100g, nitrogen adsorption specific surface area 77m ² /g

(Example 4)

An O ring was produced in the same manner as in Example 1 except that 15 parts by weight of "carbon black A" was used instead of 5 parts by weight of "carbon black A". The obtained O ring system was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Further, an image of the radius of the corner portion of the end face of the test body after the fluorine gas exposure test was obtained is shown in Fig. 5.

(Example 5)

An O ring was produced in the same manner as in Example 2 except that 15 parts by weight of "carbon black B" was used instead of 5 parts by weight of "carbon black B". The obtained O ring system was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Moreover, it will be used to obtain the radius of the corner of the end face of the test body after the fluorine gas exposure test. The image is shown in Figure 6.

(Example 6)

An O ring was produced in the same manner as in Example 3 except that 15 parts by weight of "carbon black C" was used instead of 5 parts by weight of "carbon black C". The obtained O ring system was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Further, an image of the radius of the corner portion of the end face of the test body after the fluorine gas exposure test was obtained is shown in Fig. 7. In Fig. 7, the black portion is a test body, and the white portion is a circle attached by image processing having a corner portion radius.

(Comparative Example 1)

An O ring was produced in the same manner as in Example 1 except that the following "carbon black D" was used instead of "carbon black A". Further, the carbon black is calculated based on JIS K 6217 (1997), and the DBP oil absorption amount and the nitrogen adsorption specific surface area are calculated, and this value is a manufacturer type record value. The obtained O ring system was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Further, an image for determining the radius of the corner portion of the end face of the test body after the fluorine gas exposure test is shown in Fig. 8. In Fig. 8, the two circles are attached by image processing having a corner radius.

"Carbon Black D";

"旭#50" (SRF-HS-HM carbon black) (made by Asahi Carbon Co., Ltd.) DBP oil absorption 63cm ³ /100g, nitrogen adsorption specific surface area 23m ² /g

(Comparative Example 2)

In addition to replacing 5 parts by weight of "carbon black A", the following "carbon black E" 15 weight is used. An O ring was produced in the same manner as in Example 1 except for the parts. Further, the carbon black is calculated based on JIS K 6217 (1997), and the DBP oil absorption amount and the nitrogen adsorption specific surface area are calculated, and this value is a manufacturer type record value. The obtained O ring system was similarly evaluated for fluorine gas resistance. The results are shown in Table 1. Further, an image of the radius of the corner portion of the end face of the test body after the fluorine gas exposure test was obtained is shown in Fig. 9. In Fig. 9, the two circles are attached by image processing having a corner radius.

"Carbon Black E";

"SurmaxMT N990" (MT carbon black) (manufactured by Cancarb) DBP oil absorption 43cm ³ /100g, nitrogen adsorption specific surface area 10m ² /g

As shown in Table 1 and FIG. 5 to FIG. 7, the perfluoroelastomer composition containing 15 parts by weight of carbon black having a DBP oil absorption of 90 cm ³ /100 g or more based on 100 parts by weight of the elastomer component is obtained. The molding systems of Examples 4 to 6 showed little dissolution even when exposed to a high-temperature fluorine gas atmosphere for a predetermined period of time. This system is considered to be a carbon black having a DBP oil absorption of 90 cm ³ /100 g or more. Since the structure is developed and the interaction with the perfluoroelastomer is strong, even if it is exposed to a high-temperature fluorine gas, the melting of the elastomer can be stopped. Further, as shown in Table 1 and Figs. 3 and 4, the perfluoroelastomer composition containing 5 parts by weight of carbon black having a DBP oil absorption of 90 cm ³ /100 g or more is obtained based on 100 parts by weight of the elastomer component. The molding systems of Examples 1 to 3 did not observe a large amount of dissolution even when exposed to a high-temperature fluorine gas atmosphere for a predetermined period of time. On the other hand, the molding systems of Comparative Examples 1 and 2 obtained from the perfluoroelastomer composition containing carbon black having a DBP oil absorption of 43 cm ³ /100 g or 63 cm ³ /100 g were as shown in Figs. 8 and 9 A large amount of dissolution can be observed.

(industrial availability)

In the elastomer molded article of the present invention, since it exhibits superior resistance to a decomposition product of fluorine, a sealing material for sealing which is a thermal diffusion furnace for a semiconductor wafer in which a fluorine decomposition product is produced can be suitably used.

D‧‧‧ diameter of the test body

Length of L‧‧‧ test body

R‧‧‧ Radius of the corner where it is dissolved

Fig. 1 is a view showing the shape of a test body supplied to a fluorine gas exposure test, (A) is a perspective view, (B) is a front view, and (C) is a side view.

2 is a view showing the shape of a test body after the fluorine gas exposure test of Comparative Example 1, (A) is a front view, and (B) is a view as viewed along the line X-X in FIG. 2(A).

Fig. 3 is a process image for obtaining the radius of the corner portion of the cross section of the second embodiment.

Fig. 4 is a process image for obtaining the radius of the corner portion of the section of the third embodiment.

Fig. 5 is a process image for obtaining the radius of the corner portion of the section of the fourth embodiment.

Fig. 6 is a process image for obtaining the radius of the corner portion of the section of the fifth embodiment.

Fig. 7 is a process image for obtaining the radius of the corner portion of the cross section of the sixth embodiment.

Fig. 8 is a process image for obtaining the radius of the corner portion of the cross section of Comparative Example 1.

Fig. 9 is a process image for obtaining the radius of the corner portion of the cross section of Comparative Example 2.

Claims (3)

One perfluorinated elastomer composition, which system contains the perfluoroelastomer component and a nitrogen adsorption specific surface area of 50m ² / g or more and 180m ² / g or less, DBP oil absorption (A method) of 101cm ³ / 100g or more and 190cm ³ a carbon black of less than 100g; wherein the perfluoroelastomer component is a perfluoroalkyl vinyl group having (a) 50 to 75 mol% of tetrafluoroethylene and (b) an alkyl group having 1 to 5 carbon atoms a copolymer of ether and/or side chain having a total carbon number of 3 to 11 of 49.8 to 25 mol%, and (c) a hardening site monomer; The blending amount is 5 parts by weight or more and 30 parts by weight or less based on 100 parts by weight of the perfluoroelastomer component. The perfluoroelastomer composition of claim 1, wherein the carbon black is acetylene black. The perfluoroelastomer composition of the first or second aspect of the invention, wherein the carbon black is contained in an amount of 5 parts by weight or more and 30 parts by weight or less based on 100 parts by weight of the perfluoroelastomer component.