Methods of producing plasma enhanced chemical vapor deposition silicon nitride thin films with high compressive and tensile stress

Abstract

Various methods of generating high stress in thin plasma enhanced chemical vapor deposition (PECVD) silicon nitride (SiN) films are reported. Besides the mainstream variation of plasma power and other process parameters, novel techniques such as creation of high density layers in multilayer PECVD structures or exposure of SiN films to ultraviolet radiation are shown to increase intrinsic film stress. Thin PECVD SiN films have been analyzed by a variety of analytical techniques including Fourier transform infrared spectroscopy, x-ray reflectivity (XRR), time of flight secondary ion mass spectrometry, and transmission electron microscopy to collect data on bonding, density, chemical composition, and film thickness. The level of bonded hydrogen as well as film density has been found to correlate with film stress. Creation of multilayer structures and high density layers help to build up more stress compared to a standard single layer film deposition. Both the density and number of layers in a film, characterized by XRR, affect the stress. Higher density layers affect diffusion profiles and show impurity oscillations corresponding to a multilayer film structure. Ultraviolet cure allows the film to achieve higher level of tensile stress at relatively low temperatures (400–500°C), comparable to the result of film high temperature annealing.

Dielectric Barrier, Etch Stop, and Metal Capping Materials for State of the Art and beyond Metal Interconnects

“…50,243 While exhaustive studies have not been reported, several studies of PECVD a-SiN:H have shown that UV curing leads to hydrogen loss, densification and a decrease in compressive stress (or increase in tensile stress). [244][245][246] Additional studies have shown that UV curing can also result in an increase in paramagnetic defect densities and leakage currents. 247 Integrated requirements.-Cu/metal diffusion resistance.-An obvious integrated requirement for any dielectric diffusion barrier / metal capping layer is to prevent diffusion of the metal wire into the surrounding ILD.…”

Characterization of wafer geometry and overlay error on silicon wafers with nonuniform stress

“…Details on creating and characterizing highly stressed silicon nitride films have been published elsewhere. 11 With these details and common etching processes, nearly any silicon processing line should be able to build similar ESM wafers.…”

Depth-resolved correlation between physical and electrical properties of stressed SiNx gate insulator films

“…The interesting finding is that the overall N-H absorption intensities are increased, as the SiN x films become more compressive. The amount ratio of Si-H and N-H bonding states could causes the physical change in film density [15]. As compared to the result of hydrogen contents in Fig.…”