Varian Associates

About: Varian Associates is a based out in . It is known for research contribution in the topics: Beam (structure) & Wafer. The organization has 2160 authors who have published 2591 publications receiving 46002 citations.

Method and apparatus for temperature measurements

Abstract: Remote measurement of temperature of a process chamber provided with a substrate exhibiting a temperature dependent band gap which substrate is illuminated by a source of continuous spectrum light with a spectrum which overlaps the band gap edge of the substrate. The light which exits the substrate is focused by a lens and is picked up by a fiber optic which takes it to a spectrometer where the spectrum is analyzed to ascertain the intensity versus wavelength histograph for exit rays in the wavelength region of the equivalent band gap of the substrate. The wavelength at the point of infection in the region of band gap edge of the substrate in the histograph of the wavelength versus intensity characteristic of exit rays determines the real time substrate temperature from predetermined calibration data which correlates the wavelength at the point of inflection to actual temperature of the substrates.

Characterization of surface-undoped In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As/InP high electron mobility transistors

Abstract: High-performance 0.3- mu m-gate-length surface-undoped In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As/InP high-electron-mobility transistors (HEMTs) grown by molecular beam epitaxy (MBE) have been characterized and compared with a surface-doped structure. At 18 GHz, the surface-undoped HEMT has achieved a maximum stable gain (MSG) of 19.2 dB compared to 16.0 dB for the surface-doped structure. The higher MSG value of the surface-undoped HEMTs is obtained due to the improved g/sub m//g/sub 0/ ratio associated with the surface-induced electric field spreading effect. Comparison of identical 0.3-*150- mu m-gate devices fabricated on surface-undoped and -doped structures has shown greatly improved gate leakage characteristics and much lower output conductance for the surface-undoped structure. It is demonstrated that the surface potential, modulated by different surface layer designs, affects the charge control in the conducting channel, especially the carrier injection into the buffer, resulting in excess output conductance. Several millimeter-wave coplanar waveguide (CPW) monolithic distributed amplifiers have been successfully fabricated by using the surface-undoped HEMT structure. A high gain per stage distributed amplifier with 170-dB+or-1-dB small-signal gain across a frequency band of 24-40 GHz, a W-band monolithic integrated circuit with 6.4-dB gain at 94 GHz, and a broad bandwidth distributed amplifier with 5-dB gain across a frequency band of 5 to 100 GHz have been demonstrated by using the surface-undoped structures. >

EUV scattering and flare of 10X projection cameras

Abstract: Two new Schwzschi1d cas have been fabricated f the exeme u1avio1et (EUV) lOx miostepper. The surface topography of the mirnrs was characterized over the full range of spatial frequencies both before and after multilayer coating. EUV scattering from the individual mirnrs was measured and compared with the surface profiloinetry. A knifeedge test was used to directly measure the flare of the assembled cameras. The flare measured in this way is in excellent agreement with the contrast of isolated printed lines and with the point spread function of the camera as determined by EUV interferometry. The measured flare of the camera is also in good agreement with the flare calculated from the combined surface profile measurements of the individual mirnrs. Consistent with the improvements made in the surface finish of the inirrcr subsirates, a significant reduction in the flare is observed as compared with previously existing cameras.