A Study on the Properties of WS $i_{x}$ Thin Film with Formation Conditions of Polycide

폴리사이드 형성 조건에 따른 WS $i_{x}$ 박막 특성에 관한 연구

  • 정양희 (여수대학 전기공학과) ;
  • 강성준 (여수대학 반도체ㆍ응용물리학과) ;
  • 김경원 (하이닉스반도체)
  • Published : 2003.09.01

Abstract

We perform the physical analysis such that Si/W composition ratios and phosphorus distribution change in the W/S $i_{x}$ thin films according to phosphorus concentration of polysilicon and W $F_{6}$ flow rate for the formation of WS $i_{x}$ polycide used as a gate electrode. We report that these physical characteristics have effects on the contact resistance between word line and bit line in DRAM devices. RBS measurements show that for the samples having phosphorus concentrations of 4.75 and 6.0${\times}$10$^{2-}$ atoms/㎤ in polysilicon, by applying W $F_{6}$ flow rates decreases from 4.5 to 3.5 sccm, Si/W composition ratio has increases to 2.05∼2.24 and 2.01∼2.19, respectively. SIMS analysis give that phosphorus concentration of polysilicon for both samples have decreases after annealing, but phosphorus concentration of WS $i_{x}$ thin film has increases by applying W $F_{6}$ flow rates decreases from 4.5 to 3.5 sccm. The contact resistance between word line and bit line in the sample with phosphorus concentration of 6.0 ${\times}$ 10$^{20}$ atoms/㎤ in polysilicon is lower than the sample with 4.75 ${\times}$ 10$^{20}$ atoms/㎤ After applying W $F_{6}$ flow rates decreases from 4.5 to 3.5 sccm, the contact resistance has been improved dramatically from 10.1 to 2.3 $\mu$ $\Omega$-$\textrm{cm}^2$.

Keywords

Tungsten hexafluoride (W $F_{6}$ );Dichlorosiliane (Si $H_2$C $l_2$);Tungsten Silicide (WS $i_{x}$ );Contact Resistance

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