Effect of Chemicals on Metal Contamination on Silicon Wafers

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: Resultssupporting

confidence: 91%

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

Ko²,

et al. 1999

J. Electrochem. Soc.

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

“…Diluted SC2 solution has many benefits as compared to standard RCA; not only it consumes less expensive chemicals but also results in lower particle levels. 7 In the industrial batch ALD process, throughput is increased by preheating the samples in a separate furnace prior to the film deposition. However, the effect of preheating on the passivation quality has not been studied before.…”

Section: Introductionmentioning

confidence: 99%

Effect of substrate pretreatments on the atomic layer deposited Al2O3 passivation quality

Bao¹,

Li²,

Gastrow³

et al. 2014

The authors show here that the passivation quality of Al2O3 is highly sensitive to the surface condition prior to the atomic layer deposition, affecting especially the thermal stability of the film. Pretreatments like diluted HCl bath or preheating at 200 °C both improved significantly the passivation quality and thermal stability of the films. In addition, the authors observed that a thin chemical SiO2 layer resulting from diluted HCl solves the blistering problem often encountered in H2O based atomic layer deposited process. Finally, the authors show that the chemical oxide protects the surface from contaminants, enabling long storage times in a dirty ambient between the cleaning and the film deposition.

Materials Science in Semiconductor Processing

“…Nevertheless, all of the detected metals are common colorants in plastics [64,65], which explains the presence of those elements in the inspected samples. Hence, 3-D printing filaments with natural color (i.e., without colorants) should be preferred for purposes, where metal contamination could be an issue, including semiconductor processing in cleanroom environments [66,67]. Figure 8 presents the relative changes in mass and dimensions of PLA, ABS, and PP samples in DIW and IPA.…”

Section: Elemental Analysismentioning

confidence: 99%

Compatibility of 3-D printed devices in cleanroom environments for semiconductor processing

Pasanen

Gastrow

Heikkinen

et al. 2019

3-D printing has potential to revolutionize manufacturing of customized low-cost scientific equipment, and numerous self-designed applications have already been realized and demonstrated. However, the applicability of 3-D printed devices to cleanrooms used for semiconductor processing is not as straightforward, as the controlled environment sets strict requirements for the allowed materials and items. This work investigates the opportunity to utilize 3-D printing in cleanrooms by analyzing three potentially suitable polymers (polylactic acid (PLA), acrylonitrile butadiene styrene (ABS) and polypropylene (PP)) for two applications that do not require particular chemical compatibility: a custom single wafer storage box and a wafer positioner for a metrology system. The designed equipment supplements commercial selection by introducing support for samples with non-standard shape or size and simultaneously reduces the price of often extensively expensive cleanroom equipment. The results show that the single wafer boxes 3-D printed from PLA and ABS generate as little particles as a commercial equivalent, whereas slightly more particles are found from a wafer stored in the self-printed PP box. Nevertheless, the number of particles on all wafers is in the same order of magnitude, indicating that 3-D printed boxes are not significant particle sources. The 3-D wafer positioner seems to cause a negligible particle increase on the manipulated wafer, while abrasion of the mechanical parts generate larger numbers of particles that may disperse in the environment. Regular cleaning of those parts is thus recommended, and applicability in a cleanroom environment will depend on the cleanliness constraints. Elemental analysis reveals that 3-D printed objects contain no other harmful metal impurities than those originating from colorants. Thus, 3-D printing filaments with natural color should be preferred for purposes, where metal contamination could be an issue, including semiconductor processing. Finally, 3-D printing filaments considered in this study are shown to be resistant to isopropanol and deionized water, which is critical for efficient cleaning for use of 3-D printed objects in cleanrooms. The results demonstrate that simple 3-D printed objects, such as wafer boxes or tweezers, are not notable contamination sources, and hence, are equally suitable for use in cleanrooms as the commercial equivalents.