A metal–insulator–silicon (MIS) capacitor with hemi-spherical grained poly atomic layer deposition (ALD) deposited Al2O3 and multi-layered chemical vapor deposition (CVD) TiN structure is fabricated. The impact of the deposition process and post treatment condition on the MIS capacitor's time-dependent dielectric breakdown (TDDB) performance is also studied. With an optimized process, it is confirmed by Auger electron spectroscopy and secondary ion mass spectrometry analysis that the Al(CH3)3/O3-based ALD Al2O3 dielectric film is carbon free and the hydrogen content is as low as 9 × 1019 cm−3. The top electrode TiN is obtained by multi-layered TiCl4/NH3 CVD deposited TiN followed by 120 s post NH3 treatment after each layer. This has higher diffusion barrier in preventing impurity diffusion through TiN into the Al2O3 dielectric due to its smaller grain size. As shown in energy dispersive X-ray analysis, there is no chlorine residue in the MIS capacitor structure. The leakage current of the capacitor is lower than 1 × 10−12 A/cm2. No early failures under stress conditions are found in its TDDB test. The novel MIS capacitor is proven to have excellent reliability for advanced DRAM technology.

Dynamic random access memory(DRAM)suffers from the bridge issue due to the WSix residue on gate sidewall,which is the bottleneck to enhancing the product's yield and reliability.Thus,the Si/W atomic ratio of WSix is optimized to 2.45 by using X-ray fluorescence(XRF)and scanning electron microscope(SEM).Analysis by transmission electron microscopy(TEM)and electronic testing shows that after 30 s rapid thermal annealing(RTA)at 1 000 ℃,the sheet resistance of WSi2.45 film is 12 Ω/cm2 and can be easily etched off.Electron beam scanning before the WSix film etching shows that about 84.7% of the surface particles and polymer residue can be effectively removed through a novel wet cleaning process by 15 min HF and 10 min sulfuric-peroxide mixture(SPM)with 300 W megasonic.With these integrated optimized processes,the yield loss due to the WSix residue on the 65 nm DRAM products can be reduced from the original 31.3% to 1.9%,which also serves as a good guideline for future advanced DRAM process development.