Masaru Moriwaki

Improved Metal Gate Process by Simultaneous Gate-Oxide Nitridation during W/WNx Gate Formation.

The improvement of gate dielectric reliability by simultaneous gate dielectric nitridation during W/WNx gate sputtering deposition was investigated. The time-to-breakdown (tbd) of the W/WNx gate metal-oxide-semiconductor (MOS) capacitor was improved compared to that of the W gate by increasing the N2 flow ratio (RN) during the reactive sputtering deposition of the WNx gate with an N2–Ar gas mixture. The surface nitridation of the gate dielectric of the W/WNx gate MOS capacitor was confirmed to occur simultaneously with the reactive sputtering deposition of the WNx layer. The improvement of the gate dielectric reliability was achieved by the nitridation, which terminated the dangling bonds formed in the gate dielectric surface during the metal gate sputtering process. Other characteristics of the W/WNx gate electrode were also demonstrated. The W/WNx gate provides low resistivity, a near-mid-gap work function and a good gate etch profile.

Influences of Residual Chlorine in CVD-TiN Gate Electrode on the Gate Oxide Reliability in Multiple-Thickness Oxide Technology

Influences of the chemical vapor deposition (CVD)-TiN gate process on gate oxide integrity have been studied. The gate leakage characteristic and reliability of the gate oxide were drastically degraded by 1000°C annealing for thick oxide as compared to for thin oxide. By X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS) analyses, the oxide degradation is confirmed to be due to the formation of a weak spot induced by out-diffusion of residual Cl from the TiN gate electrode into the gate oxide. Out-diffused Cl reacts with defects in the oxide during the high-temperature anneal and forms trap sites. The weak spot which acts as a leakage path appears to be the local spot which has a larger amount of Cl-related trap sites. Controlling of impurities in the CVD metal gate is a key for realizing future multiple-thickness gate oxide technology.

Effects of the sputtering deposition process of metal gate electrode on the gate dielectric characteristics

Abstract Effects of the N 2 -introduced reactive sputtering deposition of metal gate electrodes on the gate leakage current and the dielectric reliability of the W/WN x and W/TiN metal gate MOS capacitors are investigated. The gate dielectric characteristics of W gate MOS capacitor are degraded during the sputtering deposition of the gate electrode. However, the sputtering process-induced degradation of the dielectric characteristics is improved by increasing N 2 flow ratio during the deposition of WN x gate electrode. This improvement is considered to be due to the termination of the dangling bonds in the surface-damaged layer in the gate dielectric by the surface nitridation. The nitridation of ∼1.5 at.% is found to effectively improve both gate leakage characteristics and dielectric reliability of the W/WN x gate MOS capacitor to a level comparable to those of the poly-Si gate. The characteristics of W/WN x gate MOS transistors are also improved by the surface nitridation through the decrease of the gate leakage current. However, the surface nitridation enhances the electron trapping probability under substrate injection, which results in the lower activation energy of CVS– Q bd of metal gate MOS capacitors.

The metal gate MOS reliability with improved sputtering process for gate electrode

The impacts of the N/sub 2/ introduced reactive sputtering deposition of WN/sub x/ or TiN gate electrodes on the gate leakage current and the dielectric reliability of the metal gate MOS capacitors are investigated. The surface nitridation of the gate dielectric during the reactive sputtering deposition dramatically improves the gate dielectric characteristics, being comparable to those of the poly-Si gate. The activation energy of charge-to-breakdown (Q/sub bd/) of the metal gates is identical with that of the poly-Si gate under the gate injection stress. Under the substrate injection stress, however, the activation energy of the metal gates is lower than that of the poly-Si gate due to the enhanced electron trapping of the metal gates.

A 0.18 /spl mu/m Ti-salicided p-MOSFET with shallow junctions fabricated by rapid thermal processing in an NH/sub 3/ ambient

This paper reports a 0.18 /spl mu/m Ti-salicided p-MOSFET with shallow junctions fabricated by rapid thermal processing (RTP) in an NH/sub 3/ ambient and low energy boron implantation. It is found that the nitrogen atoms induced by the RTP in an NH/sub 3/ ambient diffuse into the substrate in source/drain regions and suppress the diffusion of boron ions. This new process allows the improved short channel effect in sub-0.2 /spl mu/m regime and the suppression of boron penetration for p-MOSFETs with 4-nm gate oxide. Moreover, this process provides high current drivability due to the low resistance at the silicide/p/sup +/-silicon interface and the low sheet resistance on Ti-silicided source/drain regions.