Fluoropolymers semiconductor industry

Fluoropolymers have received much attention for applications in various fields because of their excellent properties (1) such as high thermal stability, high chemical stability, low adhesion, biological suitability, low frictional resistance, and transparency at vacuum ultraviolet (VUV) region (2). Because of the sufficient transparency at 157 nm, fluoropolymers are used as a polymer for F2 and F2 immersion lithography for semiconductor industry (2). Polymethacrylates containing bi- and/or tri-alicyclic structures, which are major polymers in ArF resist (3), are too absorptive at 157 nm and cannot be used as a polymer in F2 and F2 immersion resist (2). 

In the present study, we investigated outgassing characteristics of fluoropolymers for semiconductor industry on exposure to 157 nm, and also investigated outgassing characteristics of PTFE on exposure to focused ion beam (FIB). Outgassed species from these fluoropolymer were detedted by in-situ quadrupole mass spectrometry. 

On exposure to 157 nm, scission of side chain and C-F bond plays an important roll in outgassing characteristics. Some fluoropolymers for semiconductor industry produce harmful outgassed species of HF which... 

Since the middle 1970 s, KYNAR resins have also been used for the manufacture of microporous and ultrafiltration membranes. KYNAR fluoropolymer was selected for this application because it is resistant to many chemicals both at room temperature and elevated temperature. Because PVDF is approved by the Federal Drug Administration (FDA) for articles or components of articles intended for repeated use in contact with food, KYNAR filters and fluid handling systems are being used by the chemical and the food industry and are also being used by the semiconductor industry as well as in biomedical applications The latter two applications require particularly inert materials that will not contaminate the fluid with trace contaminants, and KYNAR PVDF does meet these extreme purity requirements. 

From its onset, the semiconductor industry has relied on fluoropolymers as the material of construction for wet processing equipment, fluid transport systems, and wafer handling tools. Semiconductor manufacturing processes are extremely intolerant of particulate and chemical contamination which can, even in trace amounts, cause severe decreases in yields. Therefore, fluoropolymers purity and resistance to chemical attack have created an important role for plastics in the semicon industry. In the next section, we briefly review the chip manufacturing industry to provide the reader with a more in-depth understanding of the important role that fluoroplastics play in this industry. 

Table 15.5 summarizes the results of an extraction study on various fluoropolymer base resins and parts made from them. Extractions were conducted in an ultra-pure nitric acid at 10% by weight concentration. The acid was analyzed by ICP-MS for metal content. Table 15.5 shows the total metal and iron contents of different fluoropolymers. Iron was selectedl ] as the metal that would be most indicative of contamination from tooling used in the processing of the resins. Although this study was published in 1995, it is a good example of the relationship between the purity of resins and parts. In the last several years the absolute amount of metallic impurities has been reduced to concur with the semiconductor industry requirements (Table 15.2). 

PVDF components are used extensively in the high purity semiconductor market (low extractible values), pulp and paper industry (chemically resistant to halogens and acids), nuclear waste processing (radiation and hot acid applications), and the general chemical processing industry (chemical and temperature applications). Fluoropolymers have also met specifications for food and pharmaceutical processing industries. 

Applications of fluoropolymers are still growing, even decades after the discovery of the first plastic (polytetrafluoroethylene) in this family. The increasing use of fluoropolymers in such dynamic industries as wire and cable insulation, automotive, aerospace, oil and gas recovery, and semiconductor manufacture has led to significant material developments and trends in the last few years. New fluoropolymers have been introduced to the market (amorphous fluoroplastics, modified PTFE, low-temperature fluoroelastomers, and amine-resistant fluo-... 

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