Pattern-dependent microloading and step coverage of silicon nitride thin films deposited in a single-wafer thermal chemical vapor deposition chamber

Abstract

Less than 10% pattern-dependent microloading and greater than 95% step coverage are required for low temperature deposition of Si3N4 spacer and etch stop films in advanced logic and dynamic random access memory semiconductor applications. A single-wafer chemical vapor deposition chamber was utilized to analyze pattern loading effect on 130 nm and 90 nm patterned wafers. With silane-ammonia chemistry as the focus, a variety of processing methods were employed utilizing continuous and cyclical deposition modes. In addition, methods to modify diffusion and/or reaction rates were studied, such as remote plasma excitation and carrier gas modifications. Finally, chemistry-related variables were evaluated by changing the Si-source precursor. It was concluded that process chemistry and specifically precursor is the most dominant factor determining pattern loading effect.

Pattern Density Dependency of the Underlying Layer on O3-Tetraethylorthosilicate (TEOS) Film Formation

“…14,15 Thus, the step coverage, gap-filling, and surface roughness of O 3 -TEOS film formation are significantly changed by surface conditions on underlying layers. Since O 3 -TEOS film formation is strongly affected by the underlying layer, and semiconductor processes are impacted by the underlying pattern density, which is generally observed in other processes, [16][17][18][19] it is essential to consider pattern density effects of the underlying layer on O 3 -TEOS film formation. Therefore, in this report, we investigated the characteristics of O 3 -TEOS film formation on pattern samples with various aspect ratios.…”

Plasma Enhanced Atomic Layer Deposition of SiN:H Using N2 and Silane

“…It should also be noted that just as for PECVD SiN:H, the PEALD SiN:H films properties could all be changed significantly by varying the ratio of high to low frequency RF power (22). Specifically, refractive index was observed to range from 1.7 -1.85, dielectric constant 6-6.8, density 2.5-2.9 g/cm 3 and intrinsic stress from compressive to tensile (19). Temperature is also an important process parameter for ALD.…”

“…Some of the key materials requirements for both applications include excellent conformality and step coverage, precise thickness control, high etch selectivity, good adhesion, and low dielectric constant. Silicon nitride deposited by either low pressure chemical vapor deposition (LPCVD) or plasma enhanced chemical vapor deposition (PECVD) is one material that meets many of these requirements and has been traditionally used in similar applications (3)(4)(5)(6)(7)(8)(9)(10). However for these new applications, use of LPCVD or PECVD is challenging due to exceeding either the allowed thermal budget (LPCVD), exhibiting low step coverage/bread loafing (PECVD), or unacceptable thickness control (both).…”