It is shown that continuous or intermittent ion bombardment during deposition can change the growth mode of thick deposits formed by sputtering or evaporation. The columnar morphology commonly found when deposits exceed 1 μ in thickness can be disrupted and the deposit densified by negatively biasing the deposit and subjecting it to ion bombardment during growth. This effect is found to occur in a number of metal systems and may be attributed to resputtering during growth. In the case of sputter deposited tantalum, the density of 6-μ thick films can be increased from 14 g/cm3 at 0 deposit bias to 16.3 g/cm3 at −500-V bias. The macroscopic stress in the deposited film is also shown to be a function of the deposit bias. It is proposed that this growth habit modification may also be obtained in sputter deposited nonmetallic materials and chemical vapor deposits by ion bombarding the deposit during growth.

Energetic ion bombardment of metal and ceramic deposits during deposition is shown to affect the morphology, structure, stochiometry, and physical properties of the resulting deposit. The bombardment of the growing deposit tends to eliminate the columnar growth morphology normally encountered in thick-crystalline deposits. Generally, in metals it is found that internal stress, density, and gas content increase with increasing ion bombardment energy, but in some cases there is a decrease at high energies, possibly due to heating. In the case of sputter-deposited glass films, it is found that ion bombardment affects the stoichiometry, the coefficient of thermal expansion, and the strain point of the glass. Specific data are presented for thick (> 1 μ) rf sputter-deposited Corning 1720 glass and also sputter-deposited and electron-beam ion-plated chromium deposits with both a dc and a rf substrate bias.

Frequency and temperature dependence of the microwave elastic properties and the velocities of propagation are reported for BaMnF4. A sharp anomaly in attenuation indicates that a crystallographic phase transition occurs at T=255°K.

The coefficient of thermal expansion (CTE) of 5~ thick rf sputter-deposited Corning 1720 glass films was measured using a cantilever beam technique. The films were rf-bias sputtered in an argon (Ar films) and an argon-5% oxygen (Ar/O2 films) gas mixture. The Ar films deposited with a low substrate bias (+30, 0, and --50V) exhibited an erratic CTE on initial heating but were well behaved after a 600~ air anneal. High bias (--100, --200V) Ar films and Ar/O2 films showed no erratic behavior on initial heating. Chemical analysis indicated no significant change in the minor constituents of the sputtered glass, but neutron activation analysis showed a progressively greater oxygen depletion with increasing negative bias for both the Ar and Ar/O2 films. Etch rates were shown to increase with increasing negative bias. It is suggested that the structural changes that occur in some glass films at temperatures far below the strain point of the bulk glass (670~ are due to a combination of intrinsic stress and a high concentration of defects. Surface coverage by the sputterdeposited glass films is discussed.

1271 not N2, as the carrier gas. (iii) The deposition rate increases initially with XPH3 at all temperatures studied. A maximum rate at XPH3 ~ 0.8 is observed in the Ar system, but not the N2 system. (iv) Deposition of high P~O5 content films, i.e., at XpH3 > 0.5, appears to be inhibited by the presence of N2. AcknowledgmentThe authors would like to thank P. Sargent for technical assistance and M. McConnell for performing the microprobe analysis.Publication costs of this article were partially assisted by the General Electric Company.