Kaori Tai

Novel Channel-Stress Enhancement Technology with eSiGe S/D and Recessed Channel on Damascene Gate Process

Novel channel-stress enhancement technology on damascene gate process with eSiGe S/D for pFET is demonstrated. It is found for the first time that the damascene gate process featured by the dummy gate removal is more effective in increasing channel strain than the gate-1st process as an embedded SiGe stressor technique is used. Furthermore, an additional channel recess related to the damascene process is shown to enhance channel strain, resulting in a 14% Ion improvement at Ioff = 100 nA/um. We propose combining these strain techniques with high-k/metal gate stacks for low-power and high-performance pFETs.

Extreme High-Performance n- and p-MOSFETs Boosted by Dual-Metal/High-k Gate Damascene Process using Top-Cut Dual Stress Liners on (100) Substrates

Extreme high-performance n- and pFETs are achieved as 1300 and 1000 uA/um at Ioff = 100 nA/um and Vdd = 1.0 V, respectively, by applying newly proposed booster technologies. The combination of top-cut dual-stress liners and damascene gate remarkably enhances channel stress especially for shorter gate lengths. High-Ion pFETs with compressive stress liners and embedded SiGe source/drain are performed by using ALD-TiN/HfO2 damascene gate stacks with Tinv = 1.4 nm on (100) substrates. On the other hand, nFETs with tensile stress liners are obtained by using HfSix/HfO2 damascene gate stacks with Tinv =1.4 nm.

High Performance Dual Metal Gate CMOS with High Mobility and Low Threshold Voltage Applicable to Bulk CMOS Technology

We have developed a dual metal gate CMOS technology with HfSi_x for nMOS and Ru for pMOS on HfO₂ gate dielectric. These gate stacks show high mobility (100% of universal mobility for electron, 80% for hole at high fields) down to T_inv of 1.7 nm and symmetrical low V_t equivalent to poly-Si/SiO₂. As a result, high drive currents of 780 muA/mum and 265 muA/mum at I_off = 1 nA/mum are achieved for V_dd = 1.0 V in L_g = 60 nm nMOS and pMOS, respectively We have applied the mobility enhancement technology to the Ru/HfO₂ pMOS by utilizing (110)-substrate. As a result, an excellent drive current of 400 muA/mum (151% improvement over (100)-p⁺poly-Si/SiO₂) is achieved

High Performance pMOSFET with ALD-TiN/HfO2 Gate Stack on (110) Substrate by Low Temperature Process

We have developed a high performance pMOSFET with ALD-TiN/HfO2 gate stacks on (110) substrate using gate last process at low temperature. High work function and low gate leakage current are obtained. An extremely high mobility equivalent to P+poly-Si/SiO2 on (110) substrate (171 cm2/Vs at 0.5 MV/cm) is achieved with ALD-TiN/HfO2 on (110) substrate in the thinner Tinv region of 1.7 nm. Vth roll-off characteristics are well controlled down to 50 nm. A high drive current of 380 uA/um at I off = 1 uA/um is achieved at Vdd = 1.0 V. The drive current of ALD-TiN/HfO2 gate stack on (110) substrate is improved 1.4 times compared with (100) substrate and 2.4 times compared with P+poly-Si/SiO2 on (100) substrate

Fragile porous low-k/copper integration by using electro-chemical polishing

A fragile porous ultra-low-k (k=2.2) silica was successfully integrated at trench level in damascene copper by applying our previously reported [1] electro chemical polishing (ECP) technique for Cu. After removing Cu by ECP, the barrier (WN) was removed by low pressure (LP) CMP (<1 psi). Practical polishing rates were obtained for WN in LP-CMP, because of higher chemical sensitivity of WN compared to Ta(N). Compatibility of CVD barrier to porous low-k, excellent barrier performance in aggressive features and lower via resistance were achieved by a newly developed CVD/PVD stacked WN barrier.

High Performance and High Reliability Dual Metal CMOS Gate Stacks Using Novel High-k Bi-layer Control Technique

The impacts of interfacial layer (IFL) thickness and crystallinity of HfO2/IFL bi-layer on electrical properties were clarified using synchrotron radiation photoemission spectroscopy (SRPES) and electrical measurements of nFETs (HfSix/HfO2) and pFETs (Ru/HfO2) including BTI. It was found that crystallization of HfO2 causes significant degradation in electron mobility and PBTI, whereas the impacts on hole mobility and NBTI are negligible. The SRPES measurement revealed that the crystallization temperature depends on HfO2 thickness. We also found that the IFL thickness is the dominant factor for both electron mobility and PBTI. Therefore, a careful optimization of the HfO2/IFL bi-layer is indispensable. We proposed a novel technique for controlling the bi-layer thickness and demonstrated dual metal CMOS devices with high mobility and high reliability even by a post high-k process lower than 500degC for the very first time.