Yoon-Moon Park

Highly Scalable Phase Change Memory with CVD GeSbTe for Sub 50nm Generation

first present a PRAM with confinement of chemically vapor deposited GeSbTe (CVD GST) within high aspect ratio 50 nm contact for sub 50 nm generation PRAMs. By adopting confined GST, we were able to reduce the reset current below ~260 muA and thermally stable CVD Ge2Sb2Te5 compound having hexagonal phase was uniformly filled in a contact while maintaining constant composition along with 150 nm depth. Our results indicate that the confined cell structure of 50 nm contact is applicable to PRAM device below 50 nm design rule due to small GST size based on small contact and direct top electrode contact, reduced reset current, minimized etch damage, and low thermal disturbance effect.

Integration Technology of 30nm Generation Multi-Level NAND Flash for 64Gb NAND Flash Memory

Multi-level NAND flash memories with a 38 nm design rule have been successfully developed for the first time. A breakthrough patterning technology of Self Aligned Double Patterning (SADP) together with ArF lithography is applied to three critical lithographic steps. Other key integration technologies include low thermal budget ILD process and twisted bit-line contact for excellent isolation between adjacent bit lines. Hemi-Cylindrical FET (HCFET) together with charge trapping memory cell of Si/SiO2 /SiN/Al2O3/TaN (TANOS) was found to be effective in sufficing various electrical requirements of 30 nm generation flash cells. Finally, MLC operation is successfully demonstrated with flash cells of 8 Gb density in which all the technologies aforementioned are combined.

Smallest Bit-Line Contact of 76nm pitch on NAND Flash Cell by using Reversal PR (Photo Resist) and SADP (Self-Align Double Patterning) Process

For the scaling down of design rule to develop the high density NAND flash device, the reduced active area forces to form a small bit-line contact with the low contact-resistance, as well as the low junction leakage current due to the borderless contact. In this paper, we propose a novel process to make 38 nm small size contact with 76 nm pitch by using the reversal PR (photo resist) and SADP (self-align double patterning) process. The methods to minimize the contact resistance and to suppress the junction leakage current were explained on NAND flash device with 38 nm node technology.