Hideo Ichinose

Application of polysilanes for deep-UV antireflective coating

Application of polysilanes for a deep UV (DUV) bottom anti- reflective coating (BARC), in order to resolve the problem posed by the insufficient anti-reflection with thin conventional organic BARC applied on transparent dielectric film, is described. The newly developed polysilane anti- reflective coating has the real part of refractive index, n equals 2.00, and the imaginary part, k equals 0.23 at 248 nm. The polysilane coating is immiscible with a chemically amplified photoresist, and is not removable during normal wet development of photoresist. Etching rate of the polysilane is 2 times faster than that of DUV resist during BARC etching, and lower than that of DUV resist during dielectric film etching. The polysilane layer is easily removed by ashing using O2 gas process. Using thick polysilane coating, it can realize both the suppression of the interface reflection between the resist and BARC and good critical dimension control on dielectric film.

Light-soaking effects on a-Si:H photodiodes deposited by the laminar-flow photo-CVD method

A 2/3-in, 2-Mpixel, STACK-CCD imaging sensor has been developed for HDTV solid-state imagers. A new a-Si:H photo-conversion layer, fabricated by the laminar-flow photo-chemical-vapor-deposition method, is overlaid on the vertical CCD scanning circuitry in the sensor. The photodegradation behavior of a-Si:H photodiodes is investigated in terms of dark-current density, electron /spl mu//spl tau/ product and transient photocurrent. These properties are degraded as a result of light-induced defects in the a-Si:H layer. The Staeblar-Wronski constants, C/sub sw/, are estimated to be 7.5/spl times/10/sup -7/ at no voltage and 1.1/spl times/10/sup -7/ at a reverse voltage of 6 V applied to the photodiode during light-soaking with an AM-1 lamp. The lifetime of the photodiode is determined by the degradation of the transient photocurrent, and is estimated to be about 2.2/spl times/10/sup 8/ h for 1 lx light exposure. The lifetime is considered to be improved compared with that of previous-type photodiode reported before (1.5/spl times/10/sup 7/ h for 1.5 lx light exposure) and clearly satisfies the needs for practical use of the device.

Light-annealing effect on a-Si:H photodiode with the Ar laser-irradiation

Abstract The light stability of a-Si:H photodiode is much improved by light-annealing treatment, which is produced by the Hg-sensitized photochemical vapor deposition method. The dark-current density of the photodiode with light-annealing (2 h, 180 °C) is about seven times smaller than that without light-annealing after Ar laser irradiation ( λ=514 nm , ∼6 W/cm2, 7 min). On the other hand, the photodegradation property of the photocurrent is not improved by light-annealing for a-Si:H single layer. Although the defects are produced by light-annealing around the mid-gap level of a-Si:H(i) film, the a-Si:H(i)/a-SiC:H(p) boundary of the photodiode is considered to be improved in the case. The electric field of a-Si:H(i) is considered to become strong, which decreases the dark-current density of the photodiode after Ar laser exposure.