AMC AND CLEANROOM MATERIALS
Cleanroom Environment Testing for Metallic, Ionic, and Organic Contamination
Airborne molecular contamination (AMC) is a concern for any high-technology manufacturing process, especially in the microelectronics industry. Contamination-free manufacturing is a viable goal and can only be achieved through careful evaluation of the manufacturing environment.
Multiple sources of contamination exist in cleanrooms:
- cleanroom construction materials
- daily operational materials
- fab tools and equipment
- carriers, pods, shippers, mini-environments
- processing and cleaning chemicals/solvents
Metallics, ionics (cations and anions), and organic contamination in the cleanroom environment are common causes of production yield loss. These contaminants are classified in SEMI F21-1102 as airborne molecular contaminants (AMC) and may cause problems relating to:
- formation of films and particles resulting in poor adhesion, wetting, electrical shorts and current leakage, and degraded gate oxide integrity;
- lithography defects;
- hazing of optics, masks, and wafers;
- counter doping;
- corrosion of instruments, wiring, hard drive disks and heads, and substrates.
Metallic and Ionic Contamination
ChemTrace offers a unique ultra-high purity air sampler (MR-3000) to monitor metallic and ionic contamination in cleanroom air. The unit is self-contained and consists of a cleanroom compatible housing, vacuum pump (oil free), pre-cleaned PFA bubblers, PFA tubing, and a flow meter. A dilute acid solution is used in the bubblers to capture metallics, and ultrapure DI water is used to capture ionics.
After the air is sampled for a predetermined amount of time, the bubblers containing the solution are returned to ChemTrace. Analysis is conducted by inductively coupled plasma mass spectrometry (ICP-MS); a variety of trace metals may be monitored in one scan. Detection limits will vary from element to element, but typically range from 0.5 to 0.005 ng/L of air. Charged solutions for anion and cation testing are analyzed using ion chromatography (IC). Low detection sensitivity is achieved by efficient pre-concentration of the sample, use of improved background suppression and separation column, and completion of testing in a controlled cleanroom environmental with chemical filters.
Standard trace metals monitored
Al, As, Sb, Ba, Be, Bi, B, Cd, Ca, Cr, Co, Cu, Ga, Ge, Fe, Pb, Li, Mg, Mn, Mo, Ni, K, Na, Sr, Sn, Ti, V, Zn, Zr, and W
Standard anions and cations monitored
Anions and cations to include F-, Cl-, NO2-, Br -, NO3-, SO42-, PO43-, Li+, Na+, NH4+, K+, Mg2+, Ca2+
The presence of organic contaminants in cleanroom air can be minimized through careful selection of cleanroom materials, finishes, and assembly techniques, as well as by using ChemSorb filtration in the make-up air. In addition, critical materials should be evaluated to characterize chemical outgassing and determine if the chemical compounds released have potential for jeopardizing the manufacturing processes. ChemTrace performs screening tests for these types of materials using dynamic headspace analysis by thermal desorption gas chromatography mass spectrometry (ATD GC-MS) and outgassing at 50°-120°C.
Organic air sampling is performed using a specialized unit fitted with an organic adsorbent tube. Detection specificity for an organic contaminant of interest is optimized by using an appropriate adsorbent material. After sampling, the adsorbent tube is capped and returned together with the control tube to ChemTrace for analysis using ATD GC-MS for speciation and semi-quantitation of C7-C30 chained organics.
Cleanroom Materials Analysis
Contamination caused by cleanroom materials and consumables such as gloves, wipers, wafer containers, wafer wand tips, filter media, adhesive, paints, fire retardants, and sealants are frequently overlooked. In fact, the decision to replace these materials is often unwisely based on cost, and without considering the impact on integrated circuit processes.
ChemTrace offers testing of cleanroom materials and components to various standards, such as:
- IEST-RP-CC031.2: Method for characterizing outgassed organic compounds from cleanroom materials and components
- IEST-RP-CC005.3: Method for evaluating gloves and finer cots used in cleanrooms and other controlled environments
- IEST-RP-CC004.3: Method for evaluating wiping materials used in cleanrooms and other controlled environments
Electronics and Nanotechnology
For more information, please contact us
Technology Center and Principal Laboratory
44050 Fremont Blvd
Fremont, California 94538
12130 NE Ainsworth Circle Suite 210
Portland, Oregon 97220