Low-temperature polysilicon (LTPS) and indium-gallium-zinc oxide (IGZO) have stood out as the respective channel materials for implementing thin-film transistors (TFTs) in small mobile and next-generation flat-panel displays (FPDs). Along with the evolution from traditional rigid, bulky devices to thin, lightweight, and portable devices, low-temperature processed TFTs are attracting attention beyond FPDs, such as applications requiring flexible electronics.

Complementary integrated circuits are known to offer high computing efficiency, dissipate less power, and require less layout area. Overcoming the high leakage current of LTPS and the immature technology for implementing p-type metal-oxide (MO) TFTs, monolithic integration of p-type LTPS and n-type MO TFTs has attracted much attenti...[ Read more ]

Low-temperature polysilicon (LTPS) and indium-gallium-zinc oxide (IGZO) have stood out as the respective channel materials for implementing thin-film transistors (TFTs) in small mobile and next-generation flat-panel displays (FPDs). Along with the evolution from traditional rigid, bulky devices to thin, lightweight, and portable devices, low-temperature processed TFTs are attracting attention beyond FPDs, such as applications requiring flexible electronics.

Complementary integrated circuits are known to offer high computing efficiency, dissipate less power, and require less layout area. Overcoming the high leakage current of LTPS and the immature technology for implementing p-type metal-oxide (MO) TFTs, monolithic integration of p-type LTPS and n-type MO TFTs has attracted much attention. Such integration presents several incompatibility issues regarding materials and processes, for example, hydrogen cross-contamination, contact treatment, and metallization. Approaches for resolving these issues are addressed in this dissertation.

Fluorination is investigated as a solution for protecting MO TFTs exposed to hydrogen-containing processes. The improved resilience against hydrogen-induced degradation of a fluorinated IGZO TFT is consistent with reduced incorporation of hydrogen in the active layer of the TFT. An alternative fluorination process involving a non-oxidizing pre-annealing is also proposed to further enhance the device performance. Furthermore, MO TFTs combined with aluminum oxide and silicon nitride as the respective hydrogen diffusion barrier and passivation layer are studied as another solution. The resulting TFTs demonstrate negligible deterioration upon subsequent exposure to either hydrogen or environmental stress.

A stacked-interconnect scheme is proposed to solve the integration issues arising from contact treatment and metallization. The utility of this scheme is reflected in a narrow distribution of both the specific contact resistance and the performance of the fabricated TFTs. Complementary digital and analog circuit blocks using top-gate p-type LTPS and bottom-gate n-type IGZO TFTs are designed, fabricated, and characterized.