The major research directions include
	Fabrication of high-performance Ge-based devices on Si substrate 矽晶圓上高效能鍺元件之開發
	Research on crystalline high-κ dielectric for Si-based devices 結晶態高介電材質於矽基元件應用
	Development of high density MIM (metal-insulator-metal) capacitors 高品質金屬-絕緣層-金屬電容之開發
	Process development of high-efficiency Si-based solar cells 高效率矽晶太陽電池製程
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 Fabrication of high-performance Ge-based devices on Si substrate

Ø Despite great advancement in high-κ gate dielectrics, metal gates and strain engineering, the effort to pursue devices with higher performance never slows down. Due to the superior carrier mobility against Si, germanium (Ge) has received much attention and been regarded as a potential channel material to accommodate the ever-stringent scaling requirement for future technology nodes. Recently, the research on Ge-related technology has drawn intense attraction which can be evidenced by independent sessions in prestigious conferences or even independent conferences for the topic. Based on the process of forming an epitaxial Ge layer on Si substrate, our research team continues to explore new approaches to fulfill Ge devices with higher performance.

The main research contents include

(A) Passivation of Ge surface (鍺層表面鈍化)

(B) Integration of crystalline high-κ dielectrics into Ge MOS devices (結晶態高介電材質與鍺MOS元件之整合)

(C) Fabrication of nonvolatile memory on Ge layer (製作鍺為基礎之非揮發性記憶體)

 Research on crystalline high-κ dielectric for Si-based devices                                    

Ø Because of possessing relatively higher κ value than their amorphous counterparts, tetragonal/cubic ZrO₂ and HfO₂ have aroused considerable interest in the IC industry. Besides applying tetragonal ZrO₂ to aforementioned Ge-based devices, our research team has also dedicated to the integration of promising crystalline high-κ dielectrics into Si-based devices. In addition, we successfully master the technology to control the concentration of oxygen vacancies in the crystalline high-κ dielectrics by modulating process parameters. Dielectrics with low and high concentration of oxygen vacancies can be respectively applied to gate dielectrics for MOS devices and charge trapping layer for flash memory devices. We are one of the pioneering research teams in the world focusing on the application of crystalline high-κ dielectrics to electronic devices.

The main research contents include

(A) Crystalline ZrO₂ as the gate dielectric of MOS devices (以結晶態ZrO₂應用於MOS元件之閘極介電層)

(B) Crystalline ZrO₂ as the charge trapping layer of flash memory devices (以結晶態ZrO₂應用於快閃記憶體之電荷陷阱層)

  Development of high density MIM (metal-insulator-metal) capacitors

Ø MIM capacitors have been employed in a wide variety of electronic applications such as dynamic random access memory (DRAM), analog integrated circuits, and radio frequency (RF) circuits. As the technology advances, the ever higher capacitance density, lower leakage current as well as better reliability are required to facilitate the downscaling of the devices. To achieve this goal, many high-κ dielectrics have been investigated. In the past few years, our research team has successfully accomplished high-performance MIM capacitors by employing crystalline high-k dielectrics or some novel amorphous dielectrics as the insulator. Based on the results, we will continue investing in the development of innovative processes and materials to fulfill MIM capacitors with higher performance.

 Process development of high-efficiency Si-based solar cells

Ø A high conversion efficiency coupled with a low production cost is the key factor to popularize photovoltaic energy conversion. In a conventional Si-based crystalline solar cell, the emitter structure has a homogeneous doping profile and low sheet resistance (45-55 Ω/sq) to obtain low contact resistance and prevent metal penetration through the junction during the co-firing process. However, the emitter structure must be modified to obtain higher conversion efficiencies, since a highly doped emitter restricts the surface passivation and the response to short wavelength light, while increasing the surface recombination losses. A selective emitter that features lightly doped regions between the metal grids and heavily doped regions underneath the metal contact has been widely perceived as one of the most promising structures to realize high-efficiency cells. A single phosphorus diffusion has been developed through the selective thin SiN_x film formed by NH₃ plasma nitridation of the Si surface by our research team. In the next step, some down-conversion techniques will be integrated into our solar cells to further enhance its efficiency.