| 摘要 |
PURPOSE: A method for fabricating a semiconductor device having a thin film transistor is provided to prevent hydrogen atoms trapped in a polysilicon layer from diffusing outward during a reliability test and thereby to improve characteristics of the thin film transistor. CONSTITUTION: To form a thin film transistor, the first polysilicon layer(202), a gate oxide(203) and the second polysilicon layer(204) are successively formed and patterned on an underlying layer(201). The first interlayer dielectrics(205,206) are formed on the thin film transistor and then annealed with hydrogen. Next, a titanium layer(207) and a titanium nitride layer(208) are formed as barrier metal, and the first metallization layer(209) is formed thereon. Thereafter, the second interlayer dielectrics(210,211,212), the second metallization layer(213), and a protective layer(214) are formed. Particularly, the titanium nitride layer(208) is deposited through two steps, namely, a low and a high pressure steps. Therefore, the titanium nitride layer(208) deposited in twice can prevent the diffusion of hydrogen atoms trapped in the second polysilicon layer(204).
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