BPSG Films Research Articles

The APCVD Growth of PSG and BPSG Films Using Tertiarybutylphosphine as a Phorphorus Dopant

The use of a less hazardous alternative to phosphine gas, tertiarybutylphosphine (TBP), has been investigated for the growth of phosphosilicate and borophosphosilicate films in an atmospheric pressure chemical vapor deposition reactor (APCVD). Data on film growth rate, composition, stress properties, and refractive index are reported. The results indicate that TBP serves as a viable alternative to phosphine gas in the APCVD growth of doped silicate glasses.

Effects of borophosilicate film post-growth treatments on the flow angle

The flow angle is an important characteristic of borophosphosilicate (BPSG) films. In this work the effects of chemical compositions and various film post-growth treatments, namely delay time, deionized water rinse and flow ambients, on the flow angle are explored with the help of Fourier transform IR spectroscopy and electron spectroscopy for chemical analysis. The spectral analysis shows that the effects of the various treatments on the flow angle possibly result from the chemical changes that occur on film surfaces. It is found that the BPSG films absorb moisture during delay and deionized water rinse. The absorbed moisture enhances the silicate bonding characteristics and causes the boron oxide to be transformed into boron hydroxide. These phenomena give rise to a larger flow angle. Details of all the effects will be discussed and appropriate film post-growth treatments for obtaining BPSG films with good flow properties will be presented.

Removing the Barriers to Next Generation'S Dielectric Films: In Situ Void-Free Planarized Films

ABSTRACTIn the next generation of semiconductor devices, minimum dimensions will be smaller, aspect ratios (height to width) of devices features will be larger, and BPSG dielectrics will be challenged to deal with these changes. A new process, which integrates deposition, flow, and anneal of BPSG films, and allows void-free filling of high-aspect-ratio trenches with excellent surface planarization, is presented in this paper. Scanning electron micrographs are used to show the extent of film coverage and planarization. Additional characterization includes ion chromatography, ellipsometry, stress measurements, and breakdown field measurements.

Low Pressure Chemical Vapor Deposition of Borophosphosilicate Glass Films Produced by Injection of Miscible DADBS‐TMB‐TMP Liquid Sources

This study is a follow‐up of earlier work in which the concept of injecting miscible liquid precursors into an LPCVD reactor was implemented for the preparation of BPSG films from a mixture of tetraethylorthosilicate (TEOS), trimethyl‐borate (TMB), and trimethylphosphite (TMP). The depletion effects encountered in the use of TMP are circumvented here by the substitution of diacetoxyditertiarybutoxysilane (DADBS) for TEOS. The choice of this less thermally stable precursor allows for a decrease in deposition temperature from approximately 700° down to 500°C. In this lower temperature regime, BPSG deposits are shown to be uniform in terms of both thickness and composition across a wide isothermal zone. Variations in the proportion of the liquid phase indicate that a solution consisting by volume of 44.3% DADBS, 48.2% TMB, and 7.5% TMP yield BPSG films close to the desired composition (i.e., 4 w/o B and 4 w/o P). Typical BPSG films produced by this process are shown to exhibit good compositional uniformity, perfectly conformal step coverage, and desirable flow profiles at temperatures and phosphorus concentrations significantly lower than previously achieved with phosphosilicate glass films.

A New LPCVD Technique of Producing Borophosphosilicate Glass Films by Injection of Miscible Liquid Precursors

This study introduces a new, simple, and viable LPCVD technique based on the injection of miscible liquid precursors. The preparation of BPSG films from liquid mixtures of TEOS, TMB, and TMP is used here as a prime example for implementing this concept. The relationship between starting solution composition and resulting film composition is investigated to provide guidelines for achieving desired stoichiometries. Variations in growth rate and composition are examined to assess the relative effects of deposition temperature, total pressure, solution composition, and injection rate. At the high boron and phosphorus levels (≳4 weight percent), the reaction chemistry associated with the use of TMP is seen to produce severe depletion effects. At optimum deposition conditions, select properties of BPSG films are investigated. The results indicate high compositional uniformity within the film, a dielectric constant value in close agreement with that of thermally grown, , conformal step coverage even in the case of severe aspect ratios, and desirable flow profiles at temperatures and phosphorus concentrations significantly lower than those being currently achieved with phosphosilicate glass films.