Small signal analysis of source vapor control requirements for APCVD

A method for small signal operating point analysis of the stability of chemical source vapor flow from liquid source vapor generators (bubblers) is presented. The analytical technique allow's quantification of the relative effect of changes in the flow, pressure, and temperature operating conditions of the vapor generator on the vapor output of the generator. Application of the analysis to ({tetraethylorthosilicate/spl equiv/TEOS)+{trimethylphosphite/spl equiv/TMPi}+({trimethyl borate/spl equiv/TMB}+{O/sub 3//spl equiv/ozone) based atmospheric pressure chemical vapor deposition (APCVD) processes yields example stability criteria for the bubbler control parameters. Examination of 5-wt%-B/4-wt%-P BPSG pre-metal dielectric (PMD), and SiO/sub 2/ intermetal dielectric (IMD) processes show that variances in the bubbler temperature, /spl Delta/T, bubbler head space pressure, /spl Delta/P/sub HS/, and carrier nitrogen flow, /spl Delta/Q/sub N2/ affect the source vapor flow variance, /spl Delta/Q/sub /spl nu//, in the ratio of about 4.3:2.8:1 respectively. Film-doping and film-depth range-method uniformity specifications of /spl plusmn/0.1 wt% and /spl plusmn/2% require bubbler parameter control limits of: /spl Delta/T<0.25/spl deg/C, /spl Delta/P/sub HS//spl les/6 torr, and /spl Delta/Q/sub N2//spl les/0.3% of operating point flow.