Effects of Nitrogen, Methane, and Oxygen on Structure and Electrical Properties of Thin Tantalum Films

Abstract

An investigation was made of tantalum films sputtered in argon containing individual small amounts of nitrogen, methane, and oxygen. With argon alone, 1000-Å bcc tantalum films deposited on glass substrates heated to 400°C had a specific resistivity four times the bulk value, with the increase attributable to a reactive gas residual pressure of 10−6 to 10−5 Torr. The mixed argon-nitrogen experiments produced initially hcp Ta2N, and at higher pressures an fcc phase attributed to a new TaN structure. With methane only fcc TaC was obtained, while with oxygen an amorphous phase began to grow initially, and at higher pressures was dominant with a structure identical to anodically formed Ta2O5. The nitrides and carbide have specific resistivities from 200–300×10−6 Ω cm, and temperature coefficients between +3×10−4 and −2×10−4 deg−1. With increasing oxygen content, the specific resistivity increases approximately exponentially; the positive temperature coefficient decreases, becomes zero before the precipitation of Ta2O5, and then increases negatively at a rapid rate at the appearance of Ta2O5.

Anatomy of a Nanoscale Conduction Channel Reveals the Mechanism of a High‐Performance Memristor

“…The two stable phases of the Ta-O bulk system in equilibrium are insulating Ta 2 O 5 and conductive Ta(O) solid solution, which may accommodate up to 20% oxygen based on atomic composition. [ 64 ] When the oxygen composition goes above the solubility limit in an amorphous thin fi lm (indicated by the horizontal orange dashed line in Figure 4 b), the Ta 5 + oxidation state starts to appear as observed by XPS [ 62 ] and hopping conduction gradually becomes the dominant electron and R is resistance) heating in the high-resistance OFF state with poor thermal conductivity.…”

Plasma‐Enhanced CVD Synthesis and Structural Characterization of Ta2N3

“…[1] Another modification of tantalum mononitride, the δ-phase with a face-centered cubic B1 NaCl-type structure, was observed by Gerstenberg and Calbick [16] in thin films; it was also recently synthesized from the ε-phase by shock compression.…”

Sputtering in Mercury Ion Thrusters

“…factor of 10 (s!r.,ilar to results observed ln thru,ters wit:, a NO-.N2 systerr) to 110 change at all for Au 3'1d Ag-0 2 systems The latter result is similar to that obtained in the thruster tests with increasing argon and mercury backgrourd pressure 3 It should be pointed out that dep0s1tlon datn usually underestiMate the magnitude of t',e chance of the sputtering rat~ of the metal target As ~I u .. n ioo fig 4. tbe effect has been reported in the lip.rature at pressures considerably higher than those found in FL!,s 1 to 3. This is ilIOSt probably due to the high"r (nergy of the lons employed in tbose studlCS.…”