June 20, 2006, Edison, NJ--Horiba Jobin Yvon has introduced a spectroscopic reflectometer capable of measuring the thickness of films deposited on large-area glass substrates up to 2.5 x 2.7 m in size. Based on spectroscopic reflectometry, the DigiScreen provides film thickness in less than one second. Already delivered to a major process-chamber manufacturer for quality control of flat-panel displays, the DigiScreen has been shown to be a reliable metrology tool that provides accurate film-thickness uniformity over hundreds of points with high throughputs.
The glass sample is manually loaded on a vertical large-area motorized stage tilted at an angle of 10º. A quartz tungsten-halogen light source coupled to an optical fiber is focused onto the sample giving a spot size of 2 mm in diameter; a second optical fiber collects the light reflected from the sample. A 2048-pixel CCD coupled with a high-resolution spectrograph measures the reflectance of the sample. Data is analyzed by spectroscopic ellipsometric software (called Delta Psi 2) developed at Horiba Jobin Yvon. The software package is designed for both production and research environments.
With a spectral range of 400 nm to 800 nm, the DigiScreen measures films thicknesses ranging from 100 nm to several microns. Materials such as SiN, SiON, a-Si(n+), a-Si(HDR, LDR), LTPS, c-Si, silane-based SiOx, and TEOS have been successfully characterized. Comparative measurements between the DigiScreen and another large-area mapping spectroscopic ellipsometer manufactured by Horiba Jobin Yvon give thickness values that agree to within 0.26%.