Maria Galiano

High Aspect Ratio Trench Filling Using Two‐Step Subatmospheric Chemical Vapor Deposited Borophosphosilicate Glass for <0.18 μm Device Application

As a premetal dielectric, borophosphosilicate glass (BPSG) has been widely used for device planarization. In order to meet the stringent gap filling requirements as the device evolves toward smaller feature sizes, the current BPSG deposition process using ozone/tetraethoxysilane chemistry was fully characterized to explore its extendibility for achieving high aspect ratio gap filling. Based on the characterization results, a two-layer film deposition process was developed to accommodate the gap filling capability as well as the system throughput. Without stretching the thermal budget, the current process is able to achieve void-free gap filling at a >6:1 aspect ratio, 0.06 μm width, even with reentrant profile. Other film properties, including film stress, moisture absorption, dopant profile and flow, were also studied extensively. Postdeposition film reflow can be performed using either conventional furnace or rapid thermal annealing, the reflowed profile depends on annealing temperature as well as ambient gases. A low thermal budget can be maintained using a steam anneal.

Shallow Trench Isolation for the 45-nm CMOS Node and Geometry Dependence of STI Stress on CMOS Device Performance

In the present work, a high aspect ratio process (HARP) using a new O3/TEOS based sub atmospheric chemical vapor deposition process was implemented as STI gapfill in sub-65-nm CMOS. Good gapfill performance up to aspect ratios greater than 10:1 was demonstrated. Since the HARP process does not attack the STI liner as compared to HDP, a variety of different STI liners can be implemented. By comparing HARP with HDP, the geometry dependence of nand p-FET performance due to STI stress is discussed

Gap Fill and Film Reflow Capability of Subatmospheric Chemical Vapor Deposited Borophosphosilicate Glass

This work presents a systematic process characterization of subatmospheric chemical vapor deposited (SACVD) borophosphosilicate glass (BPSG). The effects of deposition pressure, ozone concentration, ozone flow, and dopant concentration on the film reflow profile and film properties are presented. Our results indicate that a decrease in the deposition pressure from atmospheric conditions to 200 Torr provides more than a 200% increase in SACVD BPSG deposition rate without affecting film quality. Phosphorous is incorporated in the stable form of P 2 O 5 at all deposition pressures. Higher ozone concentrations improve SACVD BPSG film reflow and film properties. Moreover, at higher dopant concentrations, both film shrinkage and stress-temperature hysteresis decrease.

Stress-Temperature Behavior of O 3 -TEOS Sub-Atmospheric CVD (SACVD) Oxide Films Deposited on Various Oxide Underlayers

A systematic evaluation of the stress-temperature behavior of O 3 -TEOS Sub-Atmospheric CVD (SACVD) oxide films used in IMD applications was performed in order to elucidate the surface dependence and mechanical stability of these films when deposited on different oxide underlayers such as PECVD TEOS-based, Silane-based, and thermally grown oxides. SACVD films were deposited at 360°C using different O 3 :TEOS molar flow ratios. The results obtained in this study indicate that the stress-temperature behavior of SACVD films deposited on PECVD Silane-based and TEOS-based oxides using N 2 O as the oxidizing agent is similar to that of the SACVD films deposited on silicon. However, a large stress hysteresis is obtained when SACVD films are deposited on PECVD TEOS-O 2 and thermally grown oxide underlayers. This large stress hysteresis results from the surface dependence effects of the SACVD oxides on thermally grown and PECVD TEOS-O 2 oxide underlayers. Also, this stress hysteresis can be reduced or eliminated by treating the oxide underlayer surface with an in-situ Ar, He, or N 2 plasma. Furthermore, it was also found that the SACVD oxides deposited using higher O 3 :TEOS molar flow ratios are chemically and mechanically more stable.