Hyun-Seok Lim

Highly Reliable 256Mb PRAM with Advanced Ring Contact Technology and Novel Encapsulating Technology

Advanced ring type technology and encapsulating scheme were developed to fabricate highly manufacturable and reliable 256Mb PRAM. Very uniform BEC area was prepared by the advanced ring type technology in which core dielectrics were optimized for cell contact CMP process. In addition, relatively high set resistance was stabilized from encapsulating Ge2Sb2Te5 (GST) stack with blocking layers, thus giving rise to a wide sensing window. These advanced ring type and encapsulating technologies can provide great potentials of developing high density 512Mb PRAM and beyond

Highly reliable vertical NAND technology with biconcave shaped storage layer and leakage controllable offset structure

The performance and reliability of 3-D NAND cells fabricated by TCAT (Terabit Cell Array Transistor) technology have been improved significantly via a damascened metal gates and a controlled offset between BL contact and select transistor. The damascened metal gate providing sufficiently low resistance is achieved by adopting a novel metal process. Highly suppressed disturbance property is achieved by the appropriate offset which reduces the leakage current through the select transistor. It is proved that the TCAT NAND is a manufacturable technology in terms of reliability as well as performance in a channel hole with a diameter of 90nm.

Effects of CVD-W process on electrical properties in sub 2× nm flash devices

The physical and electrical properties of chemical vapor deposition (CVD) tungsten (W) are evaluated in terms of W nucleation layer (SiH₄ and B₂H₆ reduction). Moreover effects of W nucleation layer on contact resistance (Rc) for sub 2× nm device are also studied. The results show that electrical properties of W thin films are varied with nucleation layers. Our results reveal that W reductions gases determine the grain sizes of W films which influence both electrical and surface properties of W films. It also has been investigated that effect of boron (B) atoms in B₂H₆ reduction W layer on P⁺ Rc. Out-diffused B atoms from P⁺ junction into silicide layer during post thermal process are compensated by B of B₂H₆ reduction W layer, which result in no degradation of P⁺ Rc despite of dopants loss at the contact interfaces. We reveal that tungsten nucleation layers are correlated with physical and electrical properties of W films and device performance.