JPH0632814A - Method for removing impurity in resin for electronic part - Google Patents

Abstract

PURPOSE:To provide a process for the removal of impurities in a resin for electronic part and capable of easily decreasing the concentration of each metallic impurity element to <=0.1ppm. CONSTITUTION:An ultra-high purity positive-type resist composition having a metallic impurity element concentration of e.g. as low as several tens ppb can be produced by a process (I) to remove impurities from an impurity- containing resin for electronic part by a hot-water treatment and/or a dilute acid treatment of the resin to obtain a resin free from impurity and a process (II) to separate the purified resin while preventing the intrusion of impurities and to dry the separated resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing impurities in a resin for electronic parts, and particularly to a method for removing and reducing metallic impurities such as iron and sodium contained in the resin. The present invention relates to a method for removing impurities.

[0002]

2. Description of the Related Art In the manufacture of integrated circuits, for example, a negative resist made of cyclized isoprene rubber or a positive resist made of novolac resin is generally used for patterning active elements and the like. . And in recent years, with the increase in the degree of integration of integrated circuits,
It is becoming more and more common to use positive photosensitive resin with excellent resolution.

However, if metal-based impurities such as alkali metals and heavy metals are present (contained) in the photoresist resin, even if the amount thereof is extremely small, the withstand voltage of the insulating oxide film is high. It may cause defects and PN junction leak defects. That is, the very small amount of metallic impurities contained in the photoresist resin used in the ULSI manufacturing process has an important influence on the functional reliability of the finally manufactured USLI. Therefore, in this type of photoresist resin, it is desired to remove metallic impurities as much as possible.

In response to the above requirements, generally, a cleaning operation with pure water (normal temperature) in the procedure shown in FIG. 2 is carried out to remove / reduce impurities in the photoresist resin. Specifically, for example, a photoresist resin is dissolved in an organic solvent such as alcohol or acetone, and the resin solution 1 is dropped into a large amount of agitated pure water (normal temperature) to perform an agitation washing treatment 2. A method of precipitating / separating and separating only 3 and then drying 4 or dissolving the photoresist resin in a non-water-soluble solvent such as ethyl acetate or toluene, and washing the resin solution with pure water (room temperature) under vigorous stirring Examples include a method in which only impurities are extracted and removed by treatment, the insoluble solvent is removed, and a drying treatment 4 is performed. Then, in these cleaning operation methods, the above-mentioned cleaning operation is usually repeated to reduce the impurity concentration to an allowable range.

In the above description, the influence of metallic impurities in the photoresist resin and the means for removing / reducing the impurities have been exemplified. For example, the resin for encapsulating a semiconductor device, the resin for a protective film, or the interlayer insulation of multilayer wiring. Even in the case of resin for use, it is a problem that cannot be ignored in terms of the performance and functions required for the applied (used) device.

[0006]

Although the above-mentioned method of cleaning with pure water at room temperature can remove and reduce impurities contained in the resin, the efficiency of removing alkali metal elements and heavy metal elements is still low. Unfortunately, it was difficult to remove / reduce the concentration of each metallic impurity element to 0.1 ppm or less. In other words, by repeating the cleaning operation with pure water at room temperature, it is possible to relatively easily reduce the concentration of metallic impurity elements to some extent, but for example, after reaching a trace amount of about 1 ppm, the cleaning operation is performed. This is because even if the number of repetitions of is greatly increased, the removal / reduction rate of the metal-based impurity element concentration is relatively low, and a practical limit must be recognized.

The present invention has been made in view of such circumstances, and it is possible to easily remove and reduce impurities in the resin for electronic parts and the concentration of each metallic impurity element to 0.1 ppm or less. An object of the present invention is to provide a possible method for removing impurities in a resin for electronic parts.

[0008]

A method for removing impurities from a resin for electronic parts according to the present invention includes a resin for electronic parts containing impurities by at least one of hot water treatment and dilute acid treatment. It is characterized by comprising a step of removing impurities, and a step of separating the resin for electronic parts from which the contained impurities have been removed while preventing the intrusion of impurities and drying the resin.

The present invention has been earnestly studied and studied a method for removing and reducing a small amount of metal impurities contained in a resin for electronic parts such as a photoresist resin, and as a result, either hot water treatment or dilute acid treatment was conducted. When treated,
This is based on the finding that the concentration of metal impurity elements in the resin can be easily and surely reduced to 0.1 ppm or less, respectively.

In the present invention, the resin for electronic parts containing impurities to be treated may be a resist resin produced by any conventionally known method, for example, a rubber-based resin such as polyisoprene or polybutadiene. Examples thereof include resist resins, acrylic resist resins such as acrylic acid esters and methacrylic acid esters, and phenolic resist resins such as novolacs. Further, it is more effective when a resist resin whose contained impurity concentration sensitively affects the sensitivity or pattern profile, for example, a chemically amplified resist resin having a property of being sensitive to the environment is used as the object to be treated. .

Examples of such chemically amplified resist resin include phenol novolac resin type, cresol novolac resin type, xylenol novolac resin type, vinyl phenol resin, isopropenyl phenol resin,
Vinylphenol and acrylic acid, methacrylic acid derivatives,
Copolymer with acrylonitrile, styrene derivative, etc.,
There are copolymers of isopropenylphenol with acrylic acid, methacrylic acid derivatives, acrylonitrile, styrene derivatives, and the like. Specific examples include copolymers of poly (p-hinylphenol) and p-isopropenylphenol with nitrile. Polymer (copolymerization ratio 1: 1), p-isopropenylphenol / styrene copolymer (copolymerization ratio 1: 1), p-
Examples thereof include a copolymer of vinylphenol and methylmethacrylate (copolymerization ratio 1: 1) and a copolymer of p-vinylphenol and methylstyrene (copolymerization ratio 1: 1).

Further, in the above resist resin, for the purpose of controlling the solubility in a developing solution or imparting photosensitivity, an alkali metal compound or the like is used as a reaction reagent to give a hydroxyl group of a polymer such as acetoxy, formyloxy or methacrylanilide. , O-Nitrobenzyl, dihydropyridyl, o-quinonediazidosulfonic acid, acryloyl, diazonium, sulfonium, iodonium, organic halides and other photosensitive substituents, or tert-carboxylic acid
Butyl ester, tert-butyl carbonate and other protective groups having a tertiary carbon, cyclohexyl, sec-butyl group, isopropyl group and other secondary carbon protective groups,
It is suitable for treatment when it is substituted with a protecting group such as a trialkyl group, a phenylsilyl group, a tetrahydropyranyl group, and a methylmethoxy group.

The impurities contained in the resin for electronic parts include, for example, iron (Fe), sodium (Na),
Potassium (K), copper (Cu), etc. are mentioned. Among these metal impurities, for example, iron (2+ or 3+), sodium (1+), potassium (1+), copper (1+ or 2)
+) Is an ion display.

The hot water (pure water), the acid, the solvent, etc. used in the present invention need to be as pure as possible, and each has a metal impurity concentration of, for example, iron: 5 ppb.
Below, sodium: 10 ppb or less, potassium: 10 ppb or less, and copper: 5 ppb or less are desirable. The temperature condition when using hot water (pure water) for the required cleaning treatment is that the temperature is about 35 ° C or higher, preferably 40 ° C or higher, because the higher the temperature, the better the cleaning effect. Therefore, the effectiveness of hot water appears. It is necessary to set the upper limit temperature in a range that does not cause thermal decomposition of the resin to be treated, and it is generally preferable that the upper limit is 20 ° C. or lower than the thermal decomposition temperature of the resin to be treated. The amount of hot water (pure water) used is not particularly limited, but in order to achieve a more sufficient cleaning effect, it is desirable to select the amount equal to or more than the amount of resin to be treated.

On the other hand, when a dilute acid aqueous solution is used for the required cleaning treatment, the acid concentration is selected and set in consideration of the stability of the resin to be treated against the acid. For example, in the case of a chemically amplified resist material having an acid crosslinkable or acid decomposable group,
It is set to about 0.1 to 0.5M. This kind of dilute aqueous acid solution is prepared by adding a required amount of at least one acid selected from high purity pure water such as nitric acid, hydrochloric acid, hydrofluoric acid, citric acid, tartaric acid and lactic acid. It can be prepared by making a solution. The cleaning treatment with the diluted acid aqueous solution may be carried out at room temperature, but by heating and maintaining the cleaning treatment system with the diluted acid aqueous solution at, for example, 40 ° C. or higher, the metal impurities can be removed and reduced more efficiently. obtain.

In any case, for example, chromium, zinc, and copper can be removed or reduced by adjusting the pH of the cleaning treatment system or selecting an organic solvent (cleaning treatment by dissolving the resin to be treated). .

In the present invention, a cleaning device (container or instrument) used in a series of operations such as the cleaning process, a separation device,
In order to avoid new sources of pollution such as a drying device, use materials that do not elute impurities, such as Teflon or synthetic quartz (or a composition coated with these), and consider the working environment (atmosphere) Of course.

[0018]

According to the above-mentioned method of the present invention, a resin for electronic parts containing impurities such as sodium and potassium,
First, contact with hot water (pure water) or a dilute acid aqueous solution is carried out to carry out a cleaning treatment. In the case of cleaning treatment with hot water (pure water), the activation energy is improved by the heat, and the easily contained elements such as sodium and potassium are quickly ionized and easily moved into the hot water. However, since it is separated from the resin, the removal and reduction of impurities in the resin for electronic parts can be achieved. In addition, even when washed with a dilute aqueous acid solution, the anions in the dilute aqueous acid solution react rapidly with impurities such as iron (2+ or 3+) and copper (1+ or 2+) cations. Is separated from the resin,
Removal and reduction of impurities in the resin for electronic parts are achieved.
Even in the cleaning treatment with this dilute aqueous acid solution, the activation energy is improved when heated, and the efficiency of removing and reducing impurities is increased. It should be noted that the efficiency of removing impurities is generally higher because the solution is more uniformly washed than the case where the resin to be treated is a powder.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples, and it is needless to say that the present invention can be appropriately modified and carried out without departing from the scope of the invention. is there.

Example 1 First, the impurity concentrations were Na: 20 ppm, K: 30 ppm, Fe: 10
100 g of m-cresol novolac resin containing ppm, Cr: 50 ppm, and Cu: 10 ppm was placed in a Teflon container and 0.5 M was added.
An aqueous acetic acid solution (500 g) was added, and the mixture was washed with vigorous shaking and stirring for 10 minutes while being heated (heated) and maintained at 60 ° C. Then, the resin component was collected by filtration using a Teflon filter, the washing treatment was performed again, and the resin component was collected by a Teflon filter. At this time, 2 l of pure water was used to sufficiently remove the acetic acid used for the cleaning treatment.

The resin component that had been washed and filtered was housed in a vacuum dryer and dried at 50 ° C. for 2 days to complete the removal of impurities from the resin. The impurity concentration in the resin powder thus treated for impurity removal was measured by a flameless atomic absorption spectrophotometer to find that Na: 10 ppb, K: 20
ppb, Fe: 50 ppb, Cr: 10 ppb, and Cu: 10 ppb were removed and reduced significantly.

100 g of m-cresol novolac resin
Was dissolved in 400 g of ethyl acetate to prepare a solution, which was washed with hot water under the conditions shown in Table 1 according to the above washing treatment conditions (Example 1a) and a washing treatment with hot water-normal temperature acid solution ( The results of Example 1b), washing with a hot water-hot acid solution (Example 1c), and washing with a hot acid solution (Example 1d) are shown in Table 2 together with the case of Example 1.

As can be seen from the above examples, the effect of removing impurities is higher when the cleaning treatment system is kept at a normal temperature (heated) than when the cleaning treatment system is set to room temperature, and when the cleaning is performed with hot water, sodium, The effect of removing potassium was great. Further, as shown in the flow chart of FIG. 1, in the above-mentioned embodiment, after the washing treatment step 5, the hot water washing step 6 is added, and then the filtration / separation step 7 and the drying treatment step 8 are performed, The removal / reduction of impurities was made more effective.

Example 2 First, the impurity concentrations were Na: 100 ppm, K: 300 ppm, Fe: 10.
ppm, Cr: 4.0 ppm, Cu: 1.0 ppm tert-butoxycarbonylated hynylphenol resin 100 g ethyl acetate 400 g
Dissolve the solution in a Teflon container, add 500 g of 0.5 M acetic acid solution, and heat (heat) to 40 ° C.
While maintaining the state, it was washed by vigorously shaking and stirring for 10 minutes.
Then, the mixture was allowed to stand for 30 minutes to separate the resin solution and the acid aqueous solution into two layers, and the upper layer resin solution was separated. After distilling off the solvent (ethyl acetate) from this resin solution, the solution was made into a solution again with 400 g of acetone, and then dropped into 3 l of pure water for reprecipitation. The resin was collected by filtration, and the resin content collected by filtration was placed in a vacuum dryer.
Drying treatment was carried out at 0 ° C for 2 days to complete the removal of impurities in the resin. When the impurity concentration in the resin powder thus treated for impurity removal was measured by a flameless atomic absorption spectrometer, Na: 50 ppb, K: 300 ppb, Fe: 100 ppb, Cr:
It was significantly reduced and reduced to 20ppb and Cu: 10ppb.

The tert-butoxycarbonylated hynylphenol resin was not made into a solution but in the form of powder under the conditions shown in Table 1 according to the above-mentioned washing treatment conditions, hot water washing treatment (Example 2a), heat treatment Cleaning treatment with water-normal temperature acid solution (Example 2b), cleaning treatment with hot water-hot acid solution (Example 2)
c) and the result of performing the cleaning treatment with the hot acid solution (Example 2d) are shown in Table 2 together with the case of Example 2.

As can be seen from the above-described examples, the effect of removing impurities is higher when the cleaning treatment system is kept at room temperature (heating) than when the cleaning treatment system is set to room temperature, and when cleaning with hot water, sodium, The effect of removing potassium was great.

[0027]

[Table 1]

[Table 2] Examples 3 to 12 Various kinds of resins for electronic parts were washed under the conditions shown in Table 3 according to the above Examples 1 and 2 to remove and reduce the impurities contained therein. It was
On the other hand, for comparison, Table 3 also shows the processing conditions in the case of the conventional cleaning process using pure water (normal temperature). further,
The initial impurity concentration (ppm) and the impurity concentration (ppm) after the cleaning treatment (removal of impurities) are shown in Table 4, respectively.

In Table 1, the state a of the sample is the case of a 20% ethyl acetate solution, and resin A: tert-butoxycarbonylated vinylphenol resin Resin B: polyvinylphenol resin Resin C: tert-butoxycarbonylmethoxylated Vinylphenol resin Resin D: polyisopropenylated phenol resin Resin E: m-cresol novolac resin

[0029]

[Table 3]

[Table 4]

[0030]

As described above, according to the method for removing impurities according to the present invention, it is possible to easily remove / reduce each metallic impurity element in the resist resin to about 0.1 ppm or less. . That is, it is possible to prepare a high-purity resist resin with a removal efficiency that is 10 times or more as compared with the conventional method by a cleaning treatment for a short time without requiring complicated operations.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of a method for removing impurities from a resin for electronic parts according to the present invention.

FIG. 2 is a flowchart showing a conventional method for removing impurities from a resist resin.

[Explanation of symbols]

1, 1 '... Resist sample 2, 2' ... Cleaning (pure water ... normal temperature) step 3, 7 ... Resist sample separation step 4, 8
… Drying process 5… Washing (dilute acid water) process 6… Washing (hot water) process

Claims (1)

[Claims] 1. A step of removing at least one of a hot water treatment and a dilute acid treatment of an electronic component resin containing impurities to remove the contained impurities, and the electronic component resin from which the contained impurities have been removed. A method for removing impurities from a resin for electronic parts, comprising a step of separating while preventing impurities from entering and performing a drying treatment.