Papers by Keyword: Out-Gassing

Abstract: To remove the oxide layer, BOE (Buffered Oxide Etchant) is widely used solution in semiconductor fabrication process. When using the BOE solution in single type equipment, NH₃ ions are created by the chemical reaction. Because BOE is a mixture solution of NH₄F and HF. And created NH₃ ions make some problems during device fabrication process. As the device is shrinked, NH₃ ion control in process chamber becomes more important. We studied the thickness change caused by NH₃ ion.When backside cleaning process using the BOE solution, surface of backside was changed. And it affected the next poly layer deposition process. As a result, poly layer deposition thickness dispersion problem was occurred. We find that the difference between normal wafer and issued wafer about backside layer and fumed NH₃ ion is main factor of this problem. In this paper, we will explain the cause of poly thickness dispersion issue that occurred at poly film deposition and analyze measurement of cleaning conditions by NH₃ out-gassing.Key Words: Poly deposition thickness, NH₃⁺ ion, BOE(Buffered Oxide Etchant),APM(Ammonium Peroxide Mixture), Out-gassing

Abstract: Airborne Molecular Contamination (AMC) concentrations become critical during queue-time (between two successive process steps) when wafers are degassing inside Front Opening Unified Pod (FOUP), a confined environment [1]. In that case, AMC concentrations can reach maximum level.

Abstract: This paper presents a vacuum system design for extreme ultraviolet lithography (EUV) and studies the prediction of pump-down curves for vacuum chambers. Related basic theories include gas laws, conductance for several kinds of flow regimes, equivalent length for pipes, outgassing, diffusion, and permeation etc. The simulation program consists of a MFC module and a MATLAB module. The MFC module is used to input necessary parameters, including start and target pressure for pumping, volume and inner surface area of vacuum chambers, configuration of pumping lines, performance of vacuum pumps, and gas loads. The MATLAB module deals with the pump-down curve calculation based on related theories. The governing equation of the conservation of mass in a pumped vacuum chamber is derived from extended Temkin isotherm. The pump-down curve of vacuum chamber is predicted by four steps, including calculation of equivalent length for pipes, conductance of pipes, and effective pumping speed of pumps, and pump-down time. An empty vacuum chamber is used to test the developed program. The pump-down curve reaches 6.5E-8 torr with 42 hours pump-down time in experiment measurement, and the simulated curve reaches 5.79E-8 torr at the same time point. The developed program can predict pump-down curve with a good accuracy in the range from low vacuum pressure to high vacuum pressure.

Abstract: Outgassing, the evolution of gas from the material in a vacuum, is not only a source of micro contamination in a semiconductor or the flat display panel production process, but it also a limitation factor in the ultra clean process of nano-technology. The outgassing from the materials of satellites and spacecrafts must be controlled for increased safety and function because space is also a vacuum environment. Several methods are used in outgassing measurement in general, but there is no one method suitable for obtaining all outgassing data. The most suitable method for a particular application must be chosen by the experimenter or user. Three types of outgassing measurement systems were fabricated and characterized, ‘Throughput method,’ ‘Rate of Rise method’ and ‘Mass Loss Measurement method’. The outgassing rates of many kinds of materials were measured and characterized using these systems.