Near-Room-Temperature Soft Plasma Pulsed Deposition of SiCxNy from 1,3,5-tri(isopropyl)cyclotrisilazane

Abstract

The silicon-nitrogen material system, primarily in the form of silicon nitride (SiNx) and silicon silicon carbo-nitride (SiNxCy) (where 0<x<1.33 and 0<y<1) continues to witness tremendous research and development interest. This interest is driven by its highly desirable combination of physical, mechanical, electrical, and optoelectronic properties, making it one of the most useful materials in integrated circuitry (IC) applications. However, the drive towards more complex and smaller IC and hetero-device structures is significantly challenging established SiNx deposition methodologies. Low thermal exposure during fabrication of the device structures is becoming essential due to the complexity and thermally fragile nature of these structures, where temperature changes can induce undesirable reactions within substructures. Furthermore, with the thickness of films approaching atomic dimensions, thermally-induced migration, in addition to electromigration, can significantly alter film properties and performance. Another consideration is the desire to move towards more flexible substrates, such as plastic or polymer substrates, which typically cannot withstand the same process temperatures as traditional substrates, such as Si or GaN. Given these emerging thermal budget limitations, work by the present investigators has focused on the development and optimization of a remote plasma-activated ALD and/or pulsed CVD process for SiNxCy at exceptionally low temperatures as protective coatings on thermally and chemically fragile substrates such as polymers and plastics. In this presentation, results are presented for low temperature remote plasma-activated pulsed CVD (P-CVD) SiNxCy using 1,3,5-triisopropylcyclotrisilazane (C9H27Si3N3, TICZ) as source precursor. This presentation will provide the following: (i) the process window for deposition of SiNxCy through the P-CVD decomposition of TICZ as a single-source precursor without a co-reactant and using ammonia (NH3) as co-reactant; (ii) the lowest deposition temperature that can be achieved using this process; (iii) the chemical, compositional, morphological, and structural properties of the resulting films as function of processing parameters, with particular emphasis on film composition, density, etch rate, and structure (amorphous versus crystalline); (iv) the effects of the process on thermally and chemically fragile substrates, such as polymers and plastics; and (v) how to deposit good quality SiNxCy while maintaining the structural and chemical integrity of such substrates, including in particular at the film-substrate interface? The instantaneous growth of the SiNxCy film on multiple types of substrates during the remote plasma pulse of the P-CVD process was observed by in-situ, real-time, ellipsometry (an example is provided in Figure 1) and the resulting films were further analyzed by XPS and wet etch rate studies. Figure 1