Contamination control in semiconductor industry using laminar barrier inerting technology

Laminar Barrier Inerting is a new and effective method of preventing air infiltration into semiconductor process equipment. Air infiltration during loading and unloading is a major source of contamination within semiconductor process furnaces. During these steps, cooler clean room air can replace hot process nitrogen due to buoyant forces. Many fabrication processes are quite sensitive to oxygen and moisture resulting from air infiltration. Praxair has developed, patented (patent number 5,210,959) and tested (in conjunction with Texas Instrument) Laminar Barrier Inerting (LBI) Technology which is capable of keeping oxygen and moisture levels down to ppm levels during furnace operations. With the present practice of having no nitrogen curtain or using certain nitrogen jets, the oxygen and moisture levels inside the furnace reach as high as atmospheric levels. By using Praxair´s improved LBI system, the furnace environment is kept clean at all times. Because of this application, the pre-process purge operations performed to clean the furnace can be shortened. In addition, having the process environment continuously controlled reduces product variability. Retrofitting the horizontal thermal reactors with the laminar barrier inerters at the furnace doors could potentially increase their life span. Finally, the LBI system can be used to cool the process wafers and therefore, decrease the growth of native oxide