Ju-seon Goo

A New, Low-Thermal-Budget Planarization Scheme for Pre-Metal Dielectric Using Electron-Beam Cured Hydrogen Silsesquioxane in Device

Employing an electron-beam (E-beam) cured hydrogen silsesquioxane (HSQ) based inorganic spin-on-glass as a pre-metal dielectric (PMD) material, we developed a simple planarization process with low thermal budget and good planarity in stacked capacitor dynamic random access memory (STC DRAM) device. We observe the basic E-beam cured HSQ film characteristics such as Fourier-transform infrared absorption spectra (FTIR), wet etch rate, film shrinkage, refractive index (RI), X-ray photoelectron spectroscopy (XPS), and electron spin resonance spectroscopy (ESR) in non-patterned wafer. No degradation of device characteristics such as Vth change, hot carrier hardness, and gate oxide quality has been observed. This process resulted in lower leakage current and higher capacitance for Ta2O5 capacitor as well as better planarization performance compared with the conventional undoped silicate glass (USG) etch back process. These results show that E-beam curing process as a low thermal budget PMD scheme would be a promising process for high capacitor dielectric materials.

A highly manufacturable, low-thermal budget, void and seam free pre-metal-dielectric process using new SOG for beyond 60nm DRAM and other devices

New PMD (Pre-Metal Dielectric) process by employing polysilazane based inorganic SOG (spin-on-glass) is suggested for future VLSI devices. Compared with conventional SOG materials, the film made from new SOG has higher wet etch resistance, which is critical in achieving deformation-free contact profile. Additional advantages of using this new SOG process are excellent gap-fill capability upto an aspect ratio (A/R) of 20 and lower thermal budget than BPSG reflow process. Neither detrimental effect of new SOG PMD process on electrical characteristics nor device performance such as refresh characteristic, compared to HDPCVD SiO/sub 2/ was observed, indicating this is a PMD process of choice for the future devices.

Application of HSQ (hydrogen silsesquioxane) based SOG to pre-metal dielectric planarization in STC (stacked capacitor) DRAM

We investigated a new planarization process by employing a flowable HSQ (hydrogen silsesquioxane) based inorganic SOG (spin-on-glass) for pre-metal dielectric material, in order to develop a simple planarization process with low thermal budget and good planarity in STC (stacked capacitor) DRAM devices. We implemented this process in 256 Mb DRAM devices, and achieved lower TaO leakage current and better Al-reflow characteristics as well as better planarization performance than those of conventional BPSG process. Degradation of device characteristics such as Vth change or hot-carrier hardness were not observed.

Modeling of stress-dependent wet etch characteristic for P-SOG STI process

Recently, spin-on-glass (SOG) oxide has been used as an important technology to overcome the gap-filling limit of conventional high density plasma (HDP) oxide in shallow trench isolation (STI) process. One of them, a novel polysilazane spin-on-glass (P-SOG) film shows a complex mechanical behavior during an annealing process and an abnormal etch loading effect in the wet process. These unique properties of P-SOG film give many opportunities to stress engineering. This paper proposed the simulation methodology to predict mechanical stresses in STI process by modeling the volumetric shrinkage phenomena of P-SOG and wet etch rate which is dependent on hydrostatic pressure. By interfacing a commercial FEM code, ABAQUS and in-house topography simulator, each of which has a portion of necessary models regarding P-SOG, we can predict the mechanical stress distribution on the various STI structures with real process profiles

A Novel and Low Thermal Budget Planarization Scheme for Pre-Metal Dielectric Using Electron-Beam Cured HSQ (Hydrogen Silsesquioxane) in STC (Stacked Capacitor) DRAM

_ We investigated a new planarization process by employing an E-beam (electron-beam) cured HSQ (hydrogen siliesquioxane) based inorganic SOG (spirron-glass) ftlr pie-metal -dielectric material, in order to develop a simple planarization process with loy lhgrmal budget and good planarity in STC (stacked capacitor) DRAryI devices, and achieved lower leakage current and higher capacitance for TanO, capacitor as well as better planarization _performance than those of conventional USG etch bdck process. No degradation of device characteristics such as Vth change or hot carrier hardness, and gate oxide quality has been observed.