Etching of Oxides - Electrochemistry of Silicon and Its Oxide - page 146

4.5. DEPOSITED OXIDES
The etch rate of CVD oxide is generally higher than that of thermal oxide as
shown in Fig. 4.2 and Fig. 4.19. 491 It is strongly affected by the formation conditions
as, for example, shown in Fig. 4.20. 784 It has been found that the etch rate of the LPCVD
oxide in diluted HF solution is lower than conventional CVD film. 397 In addition
to the formation conditions, the etch rate of CVD oxides is determined by (1) type and
concentration of the dopant, (2) condition of the postdeposition treatment, and (3) com-
position of etching solution. 148,397,452,912
Figures 4.21 and 4.22 show the etch rates of doped oxides, and
silicate glasses, in BHF solutions. 148 For P- and As-doped oxides the etch rate
monotonically increases with increasing doping concentration whereas for B-doped