ABSTRAm
Scan angle [ deg] Scan angle flucluation [%I]A h4EMS electromagnetic optical scanner for horizontal scanning in a laser scanning microscope has btxn developed. Although few MEMS actuators have been commercialized to date, it has successfully satisfied all the specifications including not only the fundamentals such as resonant fiquency and maximum scan angle but also the ones for the commercial produd such as scanning stability and reliability. It will be commercialized as a part of our product, OLSll00 (Fig. l), in the second half of FY 2001.2.1 -16 (changeable)
For improvement of metal-oxide-semiconductor structure performance such as leakage current, we have developed a new hydrogen supplying process. The process consists of depositing a phosphorous-doped 5i02 film and an Al layer on wafers completed with a conventional polysilicon gate, postmetallization-annealing the structure in N2/H2 at 420°C, and then removing the Al layer and the 5i02 film by wet etching. In this study, the hydrogen process and metal-oxide-semiconductor structures fabricated by the process have been widely investigated in comparison with a conventional postmetallization process and a fluorination process. Also, this hydrogen process has actually been applied to fabricate charge modulation device image sensors, which consist of metal-oxide-semiconductor transistors as photosites and complementary metal-oxide-semiconductor peripheral circuits. It is concluded that the new hydrogen supplying process produces much more hydrogen than in the conventional post metallization anneal. Hydrogen is uniformly distributed in the oxide with high concentration. This process greatly reduces the density of Si-5i02 interface states to a low level. Donor-type states related to atomic hydrogen do not seem to be formed consequently by hydrogen transformation into a stable form. However, the process causes the metal-oxide-semiconductor structure to be more susceptible to hot-carrier degradation. Therefore, the complementary metal-oxide-semiconductor peripheral circuit in the charge modulation device image sensor has been covered with an SiN film to suppress the diffusion of hydrogen into the near-interface region in the oxide. We attained a very low leakage current of 1.4 nA/cm2 at 60°C and the same lifetime of hot carrier degradation with past devices.
InfroductionPerformance and reproducibility of metal-oxide-semiconductor (MOS) devices strongly depend on the Si-5i02 interfacial characteristics. In the particular, in the image sensors that consist of MOS structure as photosites, the leakage current generated at the Si-5i02 interface states limits the noise performance of an image sensor.1 It is very important to reduce the density of Si-5i02 interface states.It is well known that atomic hydrogen is produced at Al5i02 interfaces.2 The hydrogen which diffuses through the 5i02 to the Si-5i02 interface reacts with silicon dangling bonds and reduces the density of interface states. This hydrogen production at the Al-5i02 interface occurs during the postmetallization anneal (PMA) step. For Al gate MOS structures, the anneal temperature of PMA has strong effects on the kinetics of hydrogen contribution to the density of interface states.3'4 At lower temperatures, a longer anneal time decreases density, while at higher temperatures above 380°C, density has a minimum value at a certain anneal time. This is because there are two competing hydrogen reactions at the Si-5i02 interface during the PMA step. One is the reaction of atomic hydrogen with interface states and the other is a thermal dissociation of the passivated states....
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