WO2000043436A1

WO2000043436A1 - Polycarbonate resin for formed article, method for production thereof and container/carrier for semiconductor product using the same

Info

Publication number: WO2000043436A1
Application number: PCT/JP2000/000231
Authority: WO
Inventors: Shigeki Kuze; Kouichi Hara
Original assignee: Idemitsu Petrochemical Co., Ltd.
Priority date: 1999-01-21
Filing date: 2000-01-19
Publication date: 2000-07-27

Abstract

A polycarbonate resin having reduced contents of volatile matters, water-soluble chlorine-containing ion and sulfate ion which may be prepared by a process comprising kneading and extruding by means of a twin-screw extruder having a reduced pressure type vent and cooling the resultant extruded strand by use of a cooling water having a specified quality; and a container/carrier formed from the resin for a semiconductor product or a disk product. Also provided are a polycarbonate resin for a formed article, which does not cause a problem of staining of a surface or the like to a silicon wafer or a hard disk formed therefrom and a method for producing the resin; and a container/carrier formed from the polycarbonate resin for a semiconductor product such as a silicon wafer or a disk product such as a hard disk.

Description

Specification

Polycarbonate resin for molding, method for producing the same, and semiconductor product storage and transportation device using the same

Technical field

TECHNICAL FIELD The present invention relates to a molding polycarbonate resin, a method for producing the same, and a semiconductor product storage / transport tool using the same. More specifically, polycarbonate with a low content of volatiles, eluted chloride ions and sulfate ions, a production method for reducing the content of these impurities, and semiconductor products such as silicon wafers formed using the polycarbonate Or, it relates to a carrier that stores, cleans, dries, and transports disk products such as hard disks.

Background art

In the process of manufacturing semiconductor products such as silicon wafers, there is a process of cleaning and drying wafers. Usually, wafers are stored in cases (called “semiconductor product storage vehicles”) that store several tens of wafers. It is immersed in a washing tank containing ultrapure water, washed, taken out, dried, and moved and transported to the next circuit production process. Conventionally, thermoplastic materials such as polypropylene and polycarbonate have been used for such carriers.However, in response to requests such as increasing the diameter of the wafer itself and increasing the number of sheets to be stored, stronger rigidity and higher resistance have been achieved. In addition, it was necessary to reduce the amount of volatile and eluted substances originating from the transport equipment that cause surface contamination of wafers in a series of cleaning and drying steps, as they have impact properties. As with semiconductor products such as silicon and wafers, disk products such as hard disks also needed to reduce the amount of volatile and eluted substances originating from vehicles that caused surface contamination. Therefore, it has not been proposed to use a polyester resin as the material of the carrier (Japanese Patent Application Laid-Open No. 9-194578), but it is inherently low in impurities and has high rigidity and high impact resistance. Expectations have been raised for polycarbonate with its properties.

Wafer surface contamination causes exfoliation and swelling of the photosensitive resin used in the subsequent circuit fabrication process, poor etching, etc., as well as partial variations in circuit resistance, circuit defects, and service life in the final product device. It is said to be a distant cause of the shortening of life. It is also said that hard disks have defects in storage layers and shorter lives.

The present invention relates to a molding polycarbonate resin which does not cause surface contamination of a silicon wafer or a hard disk, a method for producing the same, and a silicon resin molded using the molding polycarbonate resin. The purpose is to provide storage and transportation tools for semiconductor products such as wafers or disk products such as hard disks.

Disclosure of the invention

The present inventors have intensively studied the above problems, and have used a storage and transport device made of polycarbonate resin in the washing and drying processes of semiconductor products such as silicon wafers or disk products such as hard disks. In the meantime, the present inventors have investigated impurities that cause surface contamination of semiconductor products, and based on the findings, completed the present invention having the following contents.

[1] A polycarbonate resin for molding that satisfies the following (1) to (3).

(1) The weight of the volatile gas generated when the polycarbonate resin is heat-treated at 108 ° C for 30 minutes is 0.3 ppm or less,

(2) When polycarbonate resin is eluted with pure water at 23 ° C for 1 minute The weight of chloride ions eluted is 50 ppb or less, and

(3) The weight of the sulfate ion eluted when the polycarbonate resin is eluted with pure water at 23 ° C for 1 minute is 50 ppb or less.

[2] Polycarbonate powder is kneaded and extruded using a twin-screw extruder having a plurality of decompression vents, and the extruded strands have a chloride ion concentration and a sulfate ion concentration of 50 ppm by weight or less, respectively. The method for producing a polycarbonate resin for molding according to the above [1], wherein the method comprises cooling using a certain cooling water.

[3] A semiconductor product or disk product storage / transport tool molded using the polycarbonate resin for molding described in [1] above.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail below.

[1] The first invention of the present invention is a low-impurity-containing polycarbonate represented by the following (1) to (3) ′.

(1) The weight of the volatile gas generated when the polycarbonate resin is heat-treated at 108 ° C for 30 minutes is 0.3 ppm or less, preferably 0.2 ppm or less,

(2) When the polycarbonate resin is eluted with pure water at 23 ° C for 1 minute, the weight of the eluted chloride ion is 50 ppb or less, preferably 40 ppb or less.

(3) The weight of the sulfate ion eluted when the polycarbonate resin is eluted with pure water at 23 ° C for 1 minute is 50 ppb or less, preferably 40 ppb or less.

In the present invention, the amount of volatile gas from the molding polycarbonate resin is half. It is measured under typical conditions in the drying process of conductor products, and is the weight of volatile gas generated when a resin burette sample is heat-treated at a temperature of 108 for 30 minutes. It is specified by the measured value.

That is, the sample was heated at a heating temperature of 108 ° C for 30 minutes while flowing a stream of hemi-gas, and the volatile components were adsorbed on the adsorbent Tenax-TA at 130 ° C, and then the adsorbed volatile components were removed. Desorb for 2 minutes at ° C and measure by gas chromatography.

[Measurement conditions for gask mouth chromatography]

• Column: HP—5 MS

• Force ram temperature: 55 ° C (3 minutes) hold → 10 ° C / min temperature rise → 27 5 ° C (9 minutes) hold

'' Injection temperature: 280 t

'Detector: F ID (280 ° C)

• Quantitation: Quantify all peaks as heptane

The volatile gas is presumed to be, for example, methylene chloride derived from a solvent used for producing polycarbonate by the interfacial polymerization method, and also gas due to contamination at the time of pellet production.

As will be described later, in a polycarbonate that has been conventionally used for a semiconductor product or a disc product storage and transportation device, the generated weight of the volatile gas was 0.4 to 0.5 ppm. If the generated weight of this volatile gas exceeds 0.3 ppm, it is difficult to avoid contamination of semiconductor products or disc products.

In the present invention, chlorine eluted from the polycarbonate resin for molding is used. The amounts of sulfate and sulfate ions were measured under typical conditions in the washing process of semiconductor products, and a sample of resin pellets was purified using a Millipore ultrapure water production system Mi11iQ system. Using water (specific resistance: 18ΩΩ or more), measure the weight of the eluted chloride and sulfate ions by ion chromatography.

That is, a resin bottle sample is put into a polypropylene sample bottle that has been thoroughly washed with pure water for measurement, then 25 milliliters of pure water at 23 ° C is added, and after sealing, at 23 ° C Elution was performed for 1 minute. The eluted water was subjected to ion chromatography (IC700, manufactured by Yokogawa Electric Corporation) to measure the weight of chloride ions and the weight of sulfate ions.

If the weight of each of the eluted chloride ions and sulfate ions exceeds 50 ppb, it is difficult to avoid contamination of semiconductor products.

According to the knowledge of the present inventors, the chlorine ions and the sulfate ions are mainly derived from dissolved substances in strand cooling water at the time of pellet production.

Polycarbonate with a small amount of impurities as described above is significant as a material with further improved quality as a material for molding semiconductor product storage and transportation tools.

[2] A second invention of the present invention relates to a method for producing a molding polycarbonate resin having a low impurity content according to the above [1], and comprising a plurality of decompressing vents for polycarbonate powder. Using a twin-screw extruder, kneading, extruding, and extruding the strand are performed using cooling water having a chloride ion concentration and a sulfate ion concentration of 50 ppm by weight or less, respectively. Is achieved. That is, it is effective to use a twin-screw extruder with two or more decompression vents as a pellet granulator as a method for reducing the volatile gas described in (1) of [1] above. Preferably, three or more decompression vents are provided.

Volatile gas separated in the kneader is removed from the decompression vent, but a decompression vent is provided at the center of the kneader and at the exit of the kneader near the die, and a third and fourth decompression vent is appropriately arranged. It is preferable to use a type that has a good mixer and has a twin-screw kneader because it has a large degassing effect of volatile gas.

The molding conditions of such a twin-screw kneader with a multi-vacuum vent differ depending on the properties of the raw material polycarbonate powder to be charged.For example, with a twin-screw kneader having a diameter of 7 mm ηιιηφ, the It is performed at 350 ° C and an extrusion speed of 250 kg hours. Further, if necessary, the amount of volatile gas can be reduced by once passing the raw material polycarbonate pellets through the kneader again through the kneader.

Such pelletizers are usually installed in the final step of the polycarbonate manufacturing process, and various additives (antioxidants, weathering agents, etc.) are also added as appropriate during granulation. You. The present applicant has proposed a technique for further promoting the reduction of volatile gas by adding water by using the addition mechanism or the like (Japanese Patent Publication No. 5-276647). It can also function effectively for the above problems.

Conventionally, a single-screw kneader with a single vent has been used, and as described above, the generated weight of volatile gas is 0.4 to 0.5 ppm, and according to the method of the present invention, 10 minutes is required. It can be reduced to 1 or less.

Furthermore, the elution chloride ion and sulfur described in (2) and (3) of [1] above To reduce the amount of acid ions, it is effective to limit the quality of the extruded strand cooling water. That is, the hot strand exiting the dice of the twin-screw kneader passes through a water tank filled with cooling water, is cooled, and is supplied to a strand cutter. This cooling water is regarded as a source of contamination of the above-mentioned elution chloride ion and sulfate ion, and pure water is used so that the elution amount under each predetermined condition is 50 ppb or less. The purity level of such cooling water may be such that each ion concentration is not more than 50 ppm by weight, preferably not more than 40 ppm by weight. However, this limit value is very industrially significant because it generally causes cost increase. In addition, in order to maintain the storage state of the produced pellets, it is preferable to use clean pellet storage bags (for example, Elcon clean inner bags manufactured by Showa Pax Co., Ltd.).

[3] The third invention of the present invention is a molded article application invention using the molding polycarbonate resin having a low impurity content of the above [1], and is used for storing silicon wafers and hard disks. It can be suitably used for a carrier. A typical silicon wafer storage and transport tool for these semiconductor products usually has a structure in which 1 to 25 wafers each having a diameter of 150 to 30 Omm are arranged and stored with a gap therebetween.

The present invention will be further described in detail using examples.

The test methods used in the examples are as follows.

(1) Simple evaluation method for hard disk surface contamination

The obtained pellet is placed on a hard disk and left at 60 ° C and 80% RH (room temperature and humidity) for 96 hours. Check the corners and corrosion status visually.

The result of the observation is shown as good or bad.

(Example 1)

Feed 30 kg of raw polycarbonate (KD190, manufactured by Idemitsu Petrochemical Co., Ltd.) to a twin-screw kneader with a triple vent (Toshiba Machine TEM70B) and extrude at a cylinder temperature of 280 ° C. Kneading while degassing at a speed of 250 kg and extruding, cooling the strand cooling water to have a chlorine ion concentration (weight ratio) of 20 ppm and a sulfate ion concentration (weight ratio) of 22 ppm. A pellet was created by passing a strand through the aquarium. 2 g of this pellet sample was taken, and the volatile content was measured by the gas chromatography-analytical method described above. Separately, 25 g of a pellet sample was taken, and the amounts of eluted chloride ions and sulfate ions were measured by the ion chromatography analysis method described above. Tables 1 and 2 show the measurement results. Further, using the obtained pellets, a test was carried out by the above-mentioned simple evaluation method of the surface dirt of the hard disk, and the evaluation results are shown in Table 3.

(Example 2)

In Example 1, in addition to the raw material polycarbonate, 3 kg of pure water was added immediately before the second vent of the extruder, and the cylinder temperature was 280 ° C, the extrusion speed was 250 kg hours, and water and polycarbonate were used. A pellet was prepared and evaluated in the same manner except that the contact time with the net was 2.0 seconds, and kneading and extrusion were performed while removing gas. The evaluation results are shown in Tables 1, 2 and 3.

(Example 3)

The pellet sample prepared in Example 2 was again applied to a kneader under the same conditions to prepare a pellet, and thereafter, the same evaluation was performed. Table 1 shows the evaluation results. The results are shown in Tables 2 and 3.

[Comparative Example 1:]

In Example 1, a twin-screw extruder with a triple vent was replaced with a single-screw extruder with a single vent (TMG65, Nippon Placon Co., Ltd.), and a pellet was created in the same manner and evaluated. The evaluation results are shown in Tables 1, 2 and 3.

(Comparative Example 2)

Example 2 was repeated in the same manner as in Example 2 except that the quality of the strand cooling water was changed as shown in Table 2. The evaluation results are shown in Tables 1, 2 and 3.

Table 1 ExtruderConditions Volatile gas volume

Example 1 Trif. Twin-screw extruder with unit

Example 2 Trif. Twin screw extruder with water + water addition 0.0 3 0

Example 3 The sanfu of Example 2. Knead again 0. 0 1 7

Comparative Example 1 Single screw extruder with sink "0.45"

Comparative Example 2 Trif. Twin screw extruder with water + water addition 0.08 0

Table 2

Table 3

As shown in Examples 1 to 3, the effect of reducing the amount of volatile matter by the method of the present invention is one digit lower than that of Comparative Example 1 of the conventional example. Compared with Example 1, the effect of adding water was confirmed in Example 2 in which water was added, and in Example 3, the effect of reduction by repetition was confirmed.

On the other hand, by limiting the water quality of strand cooling water to a certain level, The amount of chlorine ions and sulfate ions can be reduced sufficiently.

Finally, as a result of the hard disk dirt evaluation test, the surface dirt of the hard disk was obtained in Comparative Example 1 and Comparative Example 2 in which the amount of volatile gas was large or the amount of eluted chloride ions or sulfate was large. Compared to the case where the pellets were used, the cases where the low pellets shown in Examples 1-3 of the present invention were used were less.

Industrial applicability

Polycarbonate resin for molding that does not cause surface contamination etc. of silicon wafers and hard disks, its manufacturing method, and semiconductor products such as silicon wafers and hard disks molded using the molding polycarbonate resin Provide a storage and transportation device for disk products.

Claims

结 P 冃

1. A polycarbonate resin for molding that satisfies the following (1) to (3).

(2) The weight of chloride ion eluted when the polycarbonate resin is eluted with pure water at 23 ° C for 1 minute is 50 ppb or less, and

2. Kneading and extruding the polycarbonate powder using a twin-screw extruder having a plurality of decompression vents, and cooling the extruded strand with a chloride ion concentration and a sulfate ion concentration of 50 wt ppm or less, respectively. 2. The method for producing a polycarbonate resin for molding according to claim 1, wherein the method comprises cooling using a resin.

3. A semiconductor product or disk product storage and transportation device molded using the polycarbonate resin for molding according to claim 1.