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Experimental study of UV-irradiated O 2 /H 2 gas phase cleaning for PMMA (Polymethylmethacrylate) removal is carried out in a load-locked reactor equipped with a UV lamp and PBN heater. UV enhanced O 2 /H 2 gas phase cleaning removes polymethylmethacrylate (PMMA) better at lower process pressure with higher content of H 2 . O 2 gas compete for UV (184.9 nm) absorption with PMMA producing O 3 , O( 1 D) and lower dissociation of PMMA. In our experimental conditions, etching reaction of PMMA at the substrate temperature between 75℃ and 125℃ had activation energy of about 5.86 kcal/mol indicating etching was controlled by surface reaction. Above the 180℃, PMMA removal was governed by a supply of reaction gas rather than by substrate temperature.

The electrical characteristics of p LDMOSFETs with uneven racetrack source (URS) and conventional racetrack source (CRS) before and after electrical DC stress were investigated to improve hot carrier immunity for PDP driver. The breakdown voltage of pLDMOSFET with URS in on-state was ahout 30% higher than that of p-LDMOSFET with CRS at on-state. The variations of threshold voltage (VI), maximum transeonductance (gnm.J, saturated drain current (lo~,l) of p-LDMOSFET with URS after electrical DC stress were much lower than those of p-LDMOSFET with CRS. The variation of specific-on resistance (&J of pLDMOSFET with URS after stress was much lower than that of pLDMOSFET with CRS. 0-7803-7876-8103W17.00 0 2003 IEEE

Structure and crystallization of low-pressure chemical vapor deposited silicon films using Si2H6 gasThe effect of CO and CO 2 addition to a CF 4 /O 2 plasma on the etching characteristics of a low-pressure chemical vapor deposition tungsten film has been studied in a reactive ion etching reactor. Mass spectrometry and optical emission spectroscopy were used to monitor gas phase species at various compositions of etching gas. The main role of CO is scavenging F and O atoms, while that of CO 2 is increasing the concentration of the O atom. The addition of a small amount of CO ͑1 sccm͒ to a CF 4 /O 2 plasma enhances the etch rate of tungsten. With the addition of CO 2 , the etch rate of tungsten increases until the flow rate increases up to 5 sccm. The selectivity of W to SiO 2 by adding CO and CO 2 are 3.2 and 4.1, respectively. These values are relatively high when compared with the maximum selectivity of 2 in a CF 4 /O 2 gas system.

This study characterizes an oxide etching process in a magnetically enhanced reactive ion etching (MERIE) reactor with a CHF3/CF4 gas chemistry. We use a statistical 24‐1 experimental design plus one center point to characterize the relationships between the process factors and etch responses. The factors that we varied in the design include RF power, pressure, and gas composition, and the modeled etch responses were the etch rate, etch selectivity to TiN, and uniformity. The developed models produced 3D response plots. Etching of SiO2 mainly depends on F density and ion bombardment. SiO2 etch selectivity to TiN sensitively depends on the F density in the plasma and the effects of ion bombardment. The process conditions for a high etch selectivity are a 0.3 to 0.5 CF4 flow ratio and a –600 V to –650 V DC bias voltage according to the process pressure in our experiment. Etching uniformity was improved with an increase in the CF4 flow ratio in the gas mixture, an increase in the source power, and a higher pressure. Our characterization of via etching in a CHF3/CF4 MERIE using neural networks was successful, economical, and effective. The results provide highly valuable information about etching mechanisms and optimum etching conditions.