JPS6014203A - Color filter - Google Patents

Abstract

PURPOSE:To provide a color filter having excellent resistance to dyeing, adhesion between a base plate and a dye layer and colorless transparency to visible and near UV rays and to enable working by visible and near UV rays by using a specific polymer in combination with a transparent polymer layer. CONSTITUTION:A transparent copolymer formed by crosslinking the copolymer having the unit expressed by the formula I (R<1> is an alkyl group, R<2> is H or a methyl group), the unit expressed by the formula II(R<3> is H or a methyl group) and the unit expressed by the formula III(R<4> is H or a methyl group) with the diazo resin having the unit expressed by the formula IV(X is BF4<->, PF6<->, etc.) is used for a transparent polymer layer. Such polymer is constituted by using, respectively by mol%, the unit expressed by the formula I at 90-20, the unit expressed by the formula II at 3-60 and the unit expressed by the formula III at 3-20 and the diazo resin is used at 1-20pts.wt. by 100pts.wt. the copolymer. All of R<1>-R<4> are a methyl group and X of PF6<-> is preferably used. Such crosslinked polymer is used as a direct attachment type color filter for a solid-state image pickup element, etc. and has good resistance to dyeing, adhesion to a base plate and a dyed layer, colorless transparency, resistance to developing and coatability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color filter, and more particularly to a color separation color filter mounted on a color solid-state image sensor.

The methods for mounting color filters can be broadly classified into the following methods.

(1) For example, a color-separating organic color filter is manufactured directly on a solid-state image sensor, which is formed by providing a light detection section on a silicon wafer or the like (hereinafter referred to as a "direct-mounting type").

■ A solid-state image sensor and a color-separating organic color filter are manufactured separately, and the two are aligned and bonded together using a suitable adhesive (hereinafter referred to as "bonded type"). It is particularly useful for direct-mount color filters, which are considered to be excellent in mass production.

When manufacturing a direct-mounting color filter, a polymer layer (hereinafter referred to as a "flattening" layer) is usually used to flatten the surface of the solid-state image sensor and obtain a distortion-free color filter.
Apply. After that, a photosensitive material layer is formed on top of it to form a layer to be dyed, and then, ■ a patterned resist is provided on the layer to be dyed, and the exposed portion of the layer to be dyed is dyed to form the dyed layer. After formation, the resist is peeled off, and then the next dyed layer is formed in the same manner. (A method of dyeing a single layer to be dyed into multiple dyed parts.) ■ Expose the layer to be dyed in a predetermined pattern and develop. After dyeing the dyeable insulating layer, the next dyeing layer is formed thereon in the same manner.

The method (2) above has problems such as color bleeding at the boundaries of each dyed portion, and the method (2) is generally widely used.

In the color filter obtained by method (■) above,
The selection of a dye-resistant insulating layer is important.

The dye-resistant insulating layer serves as a dye-resistant layer for the dyed layer of the first color that has already been dyed during dyeing of the second and subsequent colors.
It plays an important role in preventing color bleeding between the dyed layers of the finished color filter over time. In addition, the stain-resistant insulating layer is basically required to have good stain resistance, adhesion to the substrate and the dyed layer, colorless transparency, development resistance, and coating properties.

However, it is difficult to select a material that satisfies all of these properties. That is, for example, a water-soluble photosensitive substance such as a mixture of gelatin, casein, grue, polyvinyl alcohol, etc. and dichromate is usually used as the layer to be dyed, and a water-soluble dye is used for dyeing. be done. Therefore, the stain-resistant insulating layer is required to be highly lipophilic from the perspective of stain resistance 1-1, but it is also required to be highly hydrophilic from the perspective of adhesion to the dyed layer. This is because contradictory properties such as these are required.

Furthermore, in the case of a direct-mounted color filter, it is directly connected to the color solid-state image sensor, so in order to extract electrical signals from the color solid-state image sensor, part of the dye-resistant insulating layer must be removed. Except for this, a so-called bonding pad section or the like must be formed. For this reason, a photosensitive resin is used as the dye-resistant insulating layer of a direct-mounted color filter, and bonding pads and the like are formed by exposing it to a desired pattern and developing it. However, when forming a dye-resistant insulating layer using this photosensitive resin,
When using a photosensitive resin that can use visible light and near-ultraviolet light as the exposure light source for processing, from the viewpoint of economy and operability, it absorbs visible light and near-ultraviolet light, so it is colorless and transparent. However, the stain-resistant insulating layer, which must transmit visible light and near-ultraviolet light as completely as possible, no longer fulfills its original role. For this reason,
Polymethyl methacrylate, which is expensive and can only be processed by electron beam exposure with poor productivity, has been used as the dye-resistant insulating layer, but it is still far from satisfactory in various respects.

In order to eliminate the drawbacks of the conventional dye-resistant insulating layer as described above, the inventors of the present invention have conducted various studies and found that by combining special polymers, the dye-resistant insulating layer and the adhesion between the substrate and the dyed layer can be improved. sex,
The present invention has been completed by discovering a photosensitive resin that has excellent colorless transparency with respect to visible and near ultraviolet light, and which can be processed using visible and near ultraviolet light.

That is, the gist of the present invention is to provide a color filter consisting of at least a colored layer and a transparent polymer layer, in which the transparent polymer layer has the following formula (a): or a methyl group), a unit represented by the general formula (II) B (in the formula, R3 represents a hydrogen atom or a methyl group), and a unit represented by the general formula (In) 4 (in the formula, R4 represents a hydrogen atom or a methyl group.) A copolymer having a unit represented by (b) the general formula (I
V) (In the formula, or represents a halogen anion, BP?, pyp, or an organic sulfonic acid anion, and n represents 2 to 20.

) is an explanatory diagram showing an example of a process for an example of a color filter of the present invention.

In the figure, / is a silicon wafer, C is a photodetector, 3 is a protective film, Da is a flattening layer, left is a layer to be dyed, 6 is a mask, R is a dye-resistant insulating layer, g is a bonding pad, 9 is a The layer to be dyed and 10 indicate the surface layer.

In the case of a direct type color filter, the color filter is provided directly on the surface of the solid-state image sensor, and the solid-state image sensor that serves as the base is, for example, a silicon wafer as shown in Figure 1(a) with a photodetector section. A protective film 3 made of phosphor glass, quartz, or the like is provided on the upper surface of the protective film 3. The solid-state image sensor is also provided with a scanning line, a light-shielding film, etc., but these are omitted from the drawing.

The color filter of the present invention is formed on one surface of the solid-state image sensor as described above, and will be explained in the order of the steps.

First, a flattening layer is coated on the protective film 3 of the solid-state image sensor to a thickness of about 0.1 to .theta..mu.. As this flattening layer, it is preferable to use the same layer as the dye-resistant insulating layer 7 described later.

This layer flattens the surface of the photodetector, and the dyed f
fM ”% Easy to form stain-resistant insulation layer, etc.
However, color distortion caused by uneven thickness of the layer S to be dyed can be reduced. Next, predetermined bonding pads g and the like are formed on this planarization layer (FIG. 1(b)).

The material of this flattening layer, the method of processing the bonding pad, etc. will be described in detail later along with the explanation of the dye-resistant insulating layer 7.

Next, gelatin, casein, greens,
A mixture of a water-soluble polymer such as albumin or a synthetic polymer such as polyvinyl alcohol and a dichromate such as ammonium dichromate is applied to form a final photosensitive material layer constituting the layer to be dyed 3. (Figure 1 (C))
.

The remaining photosensitive material layer constituting the layer S to be dyed is usually O.
It is provided so that it becomes 1/~μμ.

Next, the remaining photosensitive material layer constituting the layer to be dyed S is exposed to light through a mask B having a predetermined pattern (FIG. 1(d)). Since the photosensitive material constituting the layer S to be dyed is usually made to have photosensitivity to tilIo to 3gθnm, exposure is performed using a high-pressure mercury lamp or the like having a wavelength in this range as a light source.

Next, it is developed with water to form a portion constituting the layer 5 to be dyed in a predetermined pattern (FIG. 1(e)), and then dyed with a seventh color dye having predetermined spectral characteristics according to a known method. Form the left stained layer.

Next, a photosensitive resin composition for forming the dye-resistant insulating layer 7 is coated (FIG. 1(f)). In the present invention, the dye-resistant insulating layer 7 is formed using the following general formula (I).
A copolymer having units represented by , (11) and (III) and a so-called diazo resin represented by general formula (IV) are used.

2-CH2-0-...(1)000R' (In the formula, R1 represents an alkyl group, and R2 represents a hydrogen atom or a methyl group.) , R' represents a hydrogen atom or a methyl group), a unit represented by 4 (in the formula, R4 represents a hydrogen atom or a methyl group), a unit 11- (in the formula, X represents a halogen anion, 'BP?, PF? or an organic sulfonic acid anion, and n represents λ~20.) In the present invention, the above general formulas CI), (II) and (I
A copolymer having a unit represented by II) and a copolymer having a unit represented by general formula (I
A composition with a diazo resin represented by V) is applied onto the dyed layer S (Fig. 1(f)), so that a predetermined pattern, that is, a portion forming a bonding pad portion, etc., is opaque to light. Exposure is performed using a mask 6 having a pattern etc. that has been made transparent (FIG. 1(g)). For exposure, a high-pressure mercury lamp or the like having a wavelength of about ylIo to 3 Onm, which is the photosensitive region of the diazo resin, may be used. In the exposed composition, the diazo part of the diazo resin in the composition is removed,
Positive ions are generated in the phenyl group and bond to the hydroxyl group portion of the unit represented by the general formula (DI) of the copolymer, and the copolymer is crosslinked by the diazo resin. At this time, the diazo part of the diazo resin comes off, so the crosslinking of the yellowish composition progresses.
= As it ages, it becomes substantially colorless and transparent. In addition, if the diazo part of the diazo resin remains, color will remain on the dye-resistant insulating layer, so exposure is carried out until the diazo part is almost completely removed. 7 is obtained. By eliminating the diazo moiety, absorption of visible light and near ultraviolet light by the dye-resistant insulating layer becomes extremely low.

In the present invention, the unit represented by the general formula (1) is preferably deO-coθmolti, more preferably 33 to ≠5
The unit represented by the general formula (II) is preferably 3 to 60 mol, more preferably the S-1IO mol, and the unit represented by the general formula (nl) is preferably 3 to 60 mol.
More preferably Koo Morchi! A ~/3 molar 〇 copolymer is used. The diazo resin represented by the general formula (IV) has a degree of polymerization (the value of n in the formula) from - to 0, preferably from 3 to 10. This diazo resin is preferably 7 to 7 parts by weight based on 700 parts by weight of the above copolymer.
20 parts by weight, more preferably 20 parts by weight, are used. In some cases, one or more other components may be further copolymerized in order to slightly change the physical properties. However, it is also possible to use the above copolymer by adding and mixing other polymers in an amount of about 70% by weight, and in this case, the added polymer is preferably a hydrophilic one.

When the number of units represented by the general formula (I) exceeds the above range, hydrophilicity decreases and adhesion to the dyed layer decreases. On the other hand, if the amount is less than the above range, the hydrophilicity increases, the dyeing resistance decreases, or the dye layer is eluted or peeled off during development during formation of the dyed layer. In addition, if the proportion of the units represented by the general formula (1) is less than the above value, the crosslinking property (image forming property) with the diazo resin will deteriorate, making it impossible to obtain an image, and conversely, if the proportion is greater than the above value, the resistance to Stainability is markedly reduced.

If the ratio of the diazo resin represented by the general formula (IV) as a crosslinking agent component to the copolymer is less than the above, the image forming properties will be poor; Long exposure times are required to break down and render the layer substantially colorless and transparent.

Next, by developing with an appropriate developer such as ethyl cellosolve, methyl ethyl ketone, or a mixture of these with benzyl alcohol or N-methylpyrrolidone, the unexposed areas corresponding to the bonding pad areas will be eluted. The processed dye-resistant insulating layer 7 (part of the filter) is exposed to light so that the diazo resin decomposes, resulting in a colorless and transparent dye-resistant insulating layer 7 (
Figure 7(h)). When the present photosensitive composition is used for the planarization layer, a transparent planarization layer with bonding pads etc. can be obtained by the same operation.

The copolymer used in the present invention has the following general formula (■), (VIL
It can be easily obtained by a known method of radical polymerizing the monomer represented by (■) using azobisisobutyronitrile, benzoyl peroxide, or the like as a radical initiator.

In this case, good coating properties can be obtained by dissolving both the starting material and the produced polymer well, and performing the reaction in a solvent with a not too large 15-radical chain transfer constant, such as dimethyl sulfoxide, methanol, detradrD fufunffi, etc. A polymer exhibiting the following properties can be easily obtained. The intrinsic viscosity is usually 0. / ~3.
0 dl/11 preferably 0.3~. 2. Sat/11
Those are preferably used.

Diazo resin (IV) can also be easily synthesized by a known method of polycondensing diazonium diphenylamine and paraformaldehyde with an acidic catalyst. The average degree of polymerization is usually from Co to 0, preferably from 1 to /S.

R@R1 (V) (■) 4 (■) Next, a photosensitive material 16- for forming a layer to be dyed is provided on the stain-resistant insulating layer 7 in the same manner as described above, and subjected to fog light and development. Then, a predetermined pattern of the layer to be dyed is formed. Then, the second dyed layer 9 is formed by dyeing with a first color dye having predetermined spectral characteristics (FIG. 7(1)).

This operation may be repeated to form another layer to be dyed with the dye-resistant insulating layer interposed therebetween.

As the layer to be dyed, three types of primary colors of red, green, and blue may be used, and three types of complementary colors of cyan, green, and yellow may be used. In this case, for example, the first yellow layer to be dyed may be formed so as to partially overlap the first cyan layer to be dyed, and the third color green may be obtained in the overlapped portion.

Usually, a surface layer 10 is provided on the uppermost layer to be dyed to smooth the surface or protect the dyed layer.The surface layer 10 has the following properties: strength, transparency, and adhesion with the intermediate layer and the dyed layer. Processability of bonding pad portions and the like is required, and any material that satisfies these requirements may be used, and the photosensitive parabolite described above may be used.

The surface layer IO is usually 0. The film is formed so as to have a film thickness of / to -μ, and is further exposed and developed to form a predetermined bonding pad, etc. (FIG. 1(j)).

As described above, the color filter of the present invention can be obtained, but the flattening layer or stain-resistant insulating layer of the color filter of the present invention has perfect stain resistance and has good adhesion to the substrate or the dye layer. The image quality is good, and therefore clear images can be obtained.

In the present invention, the above-mentioned special photosensitive composition is used as the flattening layer and/or the dye-resistant insulating layer, but in the present invention, at least one layer made of the above-mentioned photosensitive composition is provided, and the others are Other resin layers can also be used, and may be selected and determined as appropriate depending on the application. However, in view of the physical properties of the photosensitive composition, it is preferable to use the flattening layer as well as the dye-resistant insulating layer. Other photosensitive resins include polyglycidyl methacrylate, polymethyl methacrylate,
Various compounds such as polymethyl isopropenyl ketone, methyl methacrylamide, polyhexafluorobutyl methacrylate, polybutene-/-sulfone, etc. can be used.

The present invention will be explained in more detail with reference to Examples below.

Synthesis example methyl methacrylate, ? q, b 1! (o, trt
o mol), methacrylic acid/ri, Og (0.20 mol)
, cohydroxyethyl methacrylate t, A g (0,
O47 moles) to dimethyl sulfoxide 330 m7! Azobisisobutyronitrile/62 as a solubilizing initiator
Add g and under nitrogen atmosphere! The reaction was carried out at rθ°C for 3 hours. After reaction/! ;Dropped into water of 1 to precipitate the polymer, F
After drying separately, dissolve in tetrahydrofuran (THF) in the room and use the resulting solution /,! ; Add dropwise to n-hexane from Step 1 and reprecipitate. The zero yield of drying the resulting polymer under reduced pressure was 67%.

When the reduced viscosity η sp/c was measured in a THF solution at 30° C. and a concentration of 0.2117 di, it was 0.3.7.

191 This example is a synthesis example of the polymers used in Examples 3 and 7, but the polymers used in other Examples were also synthesized in the same manner.

Example/~7 Methyl methacrylate, methacrylic acid, and methacrylic acid obtained by the synthesis example and having the composition shown in Table/ are placed on a solid-state image sensor substrate consisting of a large number of photodetectors and a drive circuit for driving them. Co-hydroxyethyl copolymer and 3-7
A flattening layer was formed by spin coating a solution of diazo resin with a degree of polymerization of about 0 (solvent ethyl cellosolve/N-methylpyrrolidone = 8/2 (volume ratio) mixed solvent) to a film thickness of μ. A final resin layer was formed. The applied resin layer was yellowish. A mask having a predetermined pattern such as bonding pads was passed through the resin layer forming the flattening layer, and a mask aligner MA10 model (manufactured by Mikasa) equipped with a high-pressure water pan was used to pass the mask through the resin layer forming the flattening layer.
After exposure with an energy amount of 00 millijoules/crll, the film was developed with ethyl cellosolve at 20° C. for 20 minutes. The resulting flattened layer, which had undergone processing such as bonding pad portions, lost its yellowish color and was a transparent layer.

Next, on this flattening layer, an aqueous solution of gelatin-ammonium dichromate (IO", weight ratio 2.5) was applied to a film thickness of /μ
A photosensitive material layer was formed by spin coating to form a layer to be dyed. The photosensitive material layer forming the layer to be dyed was exposed through a mask having a predetermined pattern to an energy amount of λ00 milj joules/cll using the same device as above, and then developed with water at 15° C. for 7 minutes. The gelatin film was then heated at 7.10° C. for 73 minutes to harden the gelatin film.

Kayanol Yellow Ns whose pH was adjusted to Da with acetic acid
'I! It was immersed at i° C./minute for dyeing treatment to form a layer to be dyed.

Next, a photosensitive composition having the same composition as the planarizing layer is coated with a film thickness of 0.
It was applied by spin coating to a thickness of 5 μm, exposed and developed in the same manner as the flattening layer to form a transparent, dye-resistant insulating layer with bonding pads and other processed parts.

Next, a gelatin-ammonium dichromate layer was formed on this stain-resistant insulating layer in the same manner as described above, exposed and developed in the same manner as described above, and then the pH was adjusted with acetic acid in the evening.
Diaclone Turquis Blue GF (manufactured by Mitsubishi Chemical Industries ■) (Diaclone is a registered trademark of Mitsubishi Chemical Industries ■) approximately 0
．． A dyeing layer was formed by dyeing with a 3% aqueous solution at 7.5° C./minute.

Next, as a protective film, the same photosensitive composition as the planarization layer was applied by spin coating to a film thickness of O, Sμ, exposed and developed under the same conditions as above, and processed for bonding pads, etc. A solid-state color imaging device was obtained in which a transparent surface layer 4 was formed and a color filter was directly attached.

The characteristics of the obtained color filter were evaluated as follows. The evaluation results are shown in Table 1. The same resin composition used to form the flattening layer was coated on the 〇0 stain-resistant phosphorus glass plate to a thickness of /μ, and it was exposed and developed under the conditions shown in the examples. The light transmittance at a wavelength of A20 nm was measured.

Next, the layer was immersed in an aqueous solution of Diaclone Turquoise Blue GF under the same conditions as the dyeing conditions for the layer to be dyed shown in the examples, and the light transmittance at a wavelength of A 20 nm was measured. The stain resistance was evaluated based on the percentage of transmittance. The evaluation criteria are as follows.

○: Section 93 or above △: 9. ! t-90chi×: ? After measuring the light transmittance of the transparent phosphor glass, the same resin composition as that used to form the flattening layer on the phosphor glass was applied to a thickness of /μ, under the conditions shown in the example. After exposure and development, the light transmittance was measured again, and the transparency was evaluated by calculating the percentage of the light transmittance after forming the flattening layer relative to the light transmittance of the phosphor glass. The evaluation criteria are the same as the evaluation of stain resistance.

0 A flattening layer is provided on the phosphor glass in the same manner as in the case of transparency evaluation, and adhesive tape (cellophane tape) is firmly adhered to the surface of this flattening layer using finger pressure, and this is peeled off. Adhesion was evaluated. Further, a dyed layer of gelatin was formed on the top surface of the flattening layer in the same manner as in the example, and the adhesive strength was evaluated using an adhesive tape in the same manner as above. The evaluation criteria are as follows.

○: No peeling at all × D: Peeling is observed at some parts 0 When forming a flattening layer on imageable phosphor glass/θμ line/
Exposure and development were performed using a mask having a pattern of spaces, and the quality of development of this pattern was evaluated. The evaluation criteria are as follows.

○: A line/space of 10μ can be resolved.

×: Unable to resolve.

Comparative Example: A flattening layer was formed using only polymethyl methacrylate (BR-g3 manufactured by Mitsubishi Plastics Corporation) under the same conditions as in Example, and a layer to be dyed was formed on it, but the adhesion was poor. However, it peeled off and was not able to be dyed. The results are shown in Table 1.

Comparative Example λ Using only polymethacrylic acid, a 0.1% aqueous solution of the same as in Example (manufactured by Nippon Kakuri Co., Ltd.) '7! ;' When dyed at C1/min, the flattened layer dissolved and peeled off.

Comparative Example 3 Diazo resin g wt% was added to methyl methacrylate and methacrylic acid copolymer (methyl methacrylate HI, methacrylic acid HI & %), a flattening layer was formed under the same conditions as in Example, and exposed. At this time, an attempt was made to form a bonding pad portion using a mask, but the image quality was not sufficient for processing. The results are shown in Table 1.

Comparative Example 1 Using cohydroxyethyl polymethacrylate, g wt % of diazo resin was added thereto, a flattening layer was formed in the same manner as in Example, and the bonding pad portion was processed by exposure and development. . Next, on this planarization layer, Example/
Form the layer to be dyed in the same way as shown in , and after patterning “
o, i of Kayanol Yellow NSG' (manufactured by Nippon Kayaku Co., Ltd.)
% aqueous solution at 7°C for 1 minute, the flattened layer was also stained.The results are shown in Table 1.

Comparative Examples 5 to 6 Using a copolymer of methyl methacrylate and co-hydroxyethyl methacrylate, g wt % of diazo resin was added thereto, a flattening layer was formed in the same manner as in Example, and a bonding pad portion was formed. Although the layer to be dyed was formed and dyed in the same manner as in Example 1, it was not possible to achieve both adhesion to the layer to be dyed and dyeing resistance. Results first
Shown in the table.

[Brief explanation of drawings]

FIGS. 1(a) to (,+) are explanatory diagrams showing an example of the manufacturing process of a direct-mounted color filter. Al agent is a silicon wafer, λ is a photodetecting part, 3 is a protective film, Da is a flattening layer, S is a layer to be dyed, 6 is a mask, ri is a dye-resistant insulation Il#, za is a bonding pad, 9 indicates the layer to be dyed, and /θ indicates the surface layer. Attendees: Mitsubishi Chemical Industries, Ltd. Representative: Chief patent attorney - (and 7 others) = 30- 2 2 1 Telegraph display Patent Application No. 122517 of 1980 2 Title of invention Color filter 3 Case of person who makes amendments Relationship with Patent applicant (596) Mitsubishi Chemical Industries, Ltd. 4 Agent Address: 5, Mitsubishi Chemical Industries, Ltd., 2-5-2 Marunouchi, Chiyoda-ku, Tokyo 100 Date of amendment order: October 25, 1980 (shipped) (Japanese) 6 Drawings subject to amendment 7 Contents of amendment as per the attached sheet 2

Claims (4)

[Claims] (1) In a color filter consisting of at least a colored layer and a transparent polymer layer, the transparent polymer layer has (a) general formula (I) 2 (wherein R' represents an alkyl group, and R2 represents a hydrogen atom or a methyl a unit represented by the general formula (II) 3 (in the formula, R' represents a hydrogen atom or a methyl group), and a unit represented by the general formula (m) 4 ULJtJUM2LiM,OR (formula (b) General formula 1'1V) (wherein, X is a halogen anion, BFT. PF? or an organic sulfonic acid) Indicates an anion, n is -~
20 is shown. ) A color filter characterized by being a transparent polymer layer crosslinked with a diazo resin having units represented by: (2) The copolymer has units represented by general formula (1) of qo-, 2o molar, units represented by general formula (It) of 3 to 60 molar, and units represented by general formula (III) of 3~. A color filter according to claim (1), characterized in that it is a copolymer consisting of 20 molar ratios. (3) The color filter according to claim 1 or 2, wherein the diazo resin is used in an amount of 7 to θ parts by weight per 100 parts by weight of the copolymer. (4) In the general formula (1), R1 and R2 are methyl groups, in the general formula (II), R3 is a methyl group, and the general formula (l[[
), R4 is a methyl group, and in general formula (IV),
The color filter according to any one of claims (1) to (3), wherein is ◯PF or an organic sulfonic acid anion.