Determination of silicon traces in process chemicals for semiconductor production by ETAAS

Ko²,

et al. 1999

J. Electrochem. Soc.

The radioactive tracer technique was applied to investigate the out-diffusion of manganese and zinc impurities from deep-ultraviolet (DUV) photoresist. Two important process parameters, viz., baking temperature and the type of substrate (i.e., bare silicon, polysilicon, oxide, or nitride), were evaluated. Our results indicated that diffusion ratios were all below 6%, irrespective of the substrate type and baking temperature. The substrate type did not appear to strongly affect the metallic impurity out-diffusion from DUV photoresist. However, solvent evaporation was found to have a significant effect on impurity diffusion. A new model, together with a new parameter, was proposed to describe the out-diffusion behavior of impurities from DUV photoresist. This model could explain the diffusion ratio of metallic impurities in photoresist layers under various baking conditions. The effectiveness of various wet cleaning recipes in removing metallic impurities such as manganese and zinc was also studied. It was found that (i) bath life due to temperature change can considerably affect the cleaning efficiency, and (ii) hot water immersion can effectively dissolve the impurities from the wafer surface.

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Characterization and Modeling of Out‐Diffusion of Manganese and Zinc Impurities from Deep Ultraviolet Photoresist

Ko²,

et al. 1999

J. Electrochem. Soc.

“…Multiple injection technique has been applied to in situ preconcentration of several metals such as nickel, 15,16 manganese, 16 cobalt, 16 iron, 16 copper, 16,17 molybdenum, 18,19 cadmium, 20,21 lead, 22 silicon 23 and chromium. 16,24 With this procedure, limits of detection in the ng L 21 level have been reached.…”

Section: Introductionmentioning

confidence: 99%

Arsenic determination in naphtha by electrothermal atomic absorption spectrometry after preconcentration using multiple injections

Rebouças

Ferreira

Neto

2003

J. Anal. At. Spectrom.

Naphtha is a petroleum fraction containing C4-C15 hydrocarbon compounds and is used as feedstock for petrochemical processes which are affected profoundly by trace amounts of arsenic. A simple method for arsenic determination in naphtha using electrothermal atomic absorption spectrometry with polarized Zeemaneffect background correction was developed. Multiple injections were used for direct preconcentration in the graphite tube, eliminating sample pretreatment. Doehlert experimental designs were used to find the best settings for the furnace program parameters. Modifier concentration, number of multiple injections and sample volume were also optimized with the same multivariate approach. With three 45 mL sample injections, ashing temperature 1200 uC, atomization temperature 2700 uC and ashing time 60 s, a detection limit of 0.5 mg L 21 and a characteristic mass of 61 pg were achieved, using 3000 mg L 21 Pd(NO 3 ) 2 as the chemical modifier. The relative signal standard deviation was found to be 9.0% at the 2.3 mg.L 21 level. Results from several naphtha test samples showed arsenic levels typically below 3.0 mg L 21 . The high degree of automation of the proposed method minimized technician sample handling allowing its application for routine analysis. This procedure has been used for arsenic determination in naphtha feeds processed in the Braskem Petrochemical (Salvador, Bahia, Brazil).

“…Evaluation of the ratios of metallic impurities migrating from deep ultraviolet (DUV) bottom antireflective coating (BARC) or photoresist (PR) into the underlying substrate during lithographic processing (e.g., baking) requires various analytical methods − for determining the impurity concentration in the resist layer and in the underlying substrate. Among these analytical methods, the radioactive tracer technique − has been proven to be very suitable for studying element migration in materials, environment, and biochemistry.…”

mentioning

confidence: 99%

Evaluation of Metal Migration and Determination of Trace Metals after Microwave Digestion for Lithographic Materials

1999

Anal. Chem.

The radioactive tracer technique was applied to investigate the migration of cesium and zinc impurities from bottom antireflective coating (BARC) and photoresist (PR) into underlying substrate. The effects of normal baking temperatures and substrate types were studied. Our results indicated that BARC has higher migration ratios than PR, irrespective of the substrate types and normal baking temperatures. The substrate type did not appear to strongly affect the metal migration ratios. However, water and/or solvent evaporation due to temperature change was found to have a significant effect on metal migration. The diffusion profiles of BARC and PR were depicted based on diffusion equations and the migration ratios. Both the UV/visible spectrometric and the gravimetric methods were successfully implemented to evaluate the feasibility of closed-vessel microwave digestion efficiency for BARC and PR samples. By following the established microwave digestion method and the inductively coupled plasma mass spectrometer (ICPMS) determination, the detection limits obtained for multielements were in the ppb and sub-ppb levels. Except for calcium, the spike recoveries of metals ranged from 91 to 132% and 87 to 125% for BARC and PR, respectively. The analytical results were found to be in reasonably good agreement with the literature values.