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of 90 V. The data of

the normalized current fluctuations indicate that Ti-silicide emitter has the most stable current. Our experiment shows that Ti-silicide is most promising among these three materials due to its low work function, uniform surface, and the stable characteristics. INTRODUCTION In vacuum microelectronics, the stability of emission current and low turn-on voltage are key factors for practical applications. In order to obtain stable and large field emission current, various materials such as molybdenum, silicon, and diamond-like-carbon have been studied for field emitter tips[I-3]. Among various materials, Si-base materials have attracted a considerable interest due to its compatibility with silicon processing. Among Si-base materials, polycrystalline silicon(poly-Si) has several merits. It has the possibility of low temperature process and integration with active devices for display application. Silicide material is known to be chemically stable, and has low work function compared with single crystalline silicon(Si). Such characteristics as silicide may make it possible for silicide field emitter to have improved turn-on voltage and the emission current stability[4]. Although poly-Si

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Mat. Res. Soc. Symp. Proc. Vol. 509 ©1998 Materials Research Society

and silicide materials have certain advantages over Si, there have been few attempts employing poly-Si and Ti-silicide tip. In this work, we fabricated poly-Si, Si, and Ti-silicide field emitter arrays employing in-situ vacuum encapsulated lateral field emitter structures[5]. We compared the characteristics of these devices to each other focusing on turn-on voltage, emission current density, and emission current stability.

EXPERIMENT The schematic fabrication sequences of the poly-Si lateral field emitter is shown in Fig. 1. We used a Si wafer which was deposited with 5000A thick nitride and 500A thick oxide as starting material for poly-Si emitter. For Si and Ti-silicide emitter, we used SIMOX(Separation by IMplantation of Oxygen) wafers which have a 4000A thick buried oxide layer and a I 100A thick Si layer. 1000A thick amorphous Si was deposited for poly-Si field emitter, and for Tisilicide emitter, 300 A thick titanium was deposited on a SIMOX wafer and annealed at 800 V for 60 minutes so that titanium silicide layer was made. The 1000 A thick amorphous Si and 1100 A thick Si layer were doped with POC13 resulting in N+ poly-Si layer and N+ Si layer. The active layers of poly-Si, Si, and Ti-silicide emitter are N+ poly-Si, N+ Si, and titanium silicide layer respectively. The other sequences of fabrication are all the same to that of the poly-Si field emitter. Then, 3000 A thick oxide was deposited on the active layers(N+ poly-Si, N+ Si, and Tisilicide layer respectively). Patterning as shown in Fig. I (b) was performed and the 3000 A thick oxide, active layers and 500A thick oxide were etched with anisotropic RIE(Reactive Ion Etch) etching and then the active layers were over-etched with SF6 plasma in order to make the microcavity. (F