화학오염이 반도체 청정환경과 사진공정에 미치는 영향
(The) Effects of Molecular Chemical Contamination on the Photolithography Process in Semiconductor Production
화학오염 반도체 청정환 사진공정;
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The history of semiconductor can be considered as the history of innovative improvement of integration technologies which have driven the rapid industrial growth. Recent rapid technical development on GIGA DRAM(Giga Dynamic random access memory) has also required the technical supports and innovational technical improvement. In technical point of view, as the width of circuit dropped down to nano-scale, the semiconductor fabrication environment has needed more than current particle contamination controls. In addition, since airborne molecular contminants became a threatening factor which causes pattern abnormality and characteristic changes, the chemical contamination control issue has been very critical. Due to this fact, close examination on contaminants in a clean room where people mostly try to improve the fabrication inferiority, occurrence control and section cleanness become basic elements for very small scale (micro to nano) manufacturing and quality in a semiconductor fabrication line. Representative substances of chemical contamination are acid, alkali, VOC(Volatile Organic Compound) and NH_(3) (ammonia) which affect semiconductor progress significantly. Among those contamination materials, basic gas such as NH_(3) is known to cause surface contamination disorder like circuit width obstruction, membranous inner pressure drop, and lens uncleanness during photo resist development which is the weakest step of the semiconductor progress. Consequently, in order to fabricate extremely minute semiconductor progress in a stable manner, a fine detection and analysis steps for chemical contamination must be taken. Especially it is proved that a good control of NH_(3) is critical because NH_(3) causes several problems while forming the extremely minute pattern. Therefore it can be indicated that analyzing the causes of occurrences and active exclusions are very important research subjects to minimize the effects of NH_(3). In this report, we detected severa1 contaminants from the outside air and analyzed the differences of the density levels in respective progress steps. Also we have researched the contaminants related to semiconductor manufacturing processes in a long term, analyzed the data, considered the causes and preparations, and indicated the decrease in chemical contamination. So as to understand the chemical contamination density of NH_(3) which is the most important component and the effects of NH_(3) in photo process, the artificial atmosphere density in experimental chamber has been created and experiments were made under the circumstance. As the result of the experiments, the causes of chemical contamination which causes the progress abnormality and designate the control area of chemical contamination could be detected. Also this research could propose the waiting time for basic progress to manufacture the extremely minute progress below 100 nm and standard for NH_(3) density control in a clean room. Moreover, the installation of adsorption filter at the ventilator in a clean room could so1ve the chemical contamination problem. we could successfully acquire the condition for the extremely minute progress simultaneously. This result can be expected to be related to the development of frequently asked element technologies such as the isolation from contaminants, section contamination control of manufacturing equipment, the research for AMC(Airborne molecular contaminants) types, and the methods of contamination control for long run.
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