Byoung-Don Kang

Characterization of Tantalum Nitride Thin Films Deposited on SiO2 ∕ Si Substrates Using dc Magnetron Sputtering for Thin Film Resistors

Tantalum nitride thin films were deposited on SiO 2 (600 nm)/Si substrates at various nitrogen/argon ratios [N 2 /(N 2 + Ar)] by dc magnetron sputtering. The structural and electrical properties of the films are investigated as a function of nitrogen/argon ratio at room temperature and at various deposition temperatures. The phase changes as Ta 2 N or TaN in the films were observed as nitrogen/argon ratio increases from 3 to 25%. The phase changes were associated with a change in the resistivity and TCR (temperature coefficient of resistance) of the films. TCR values of the films deposited at room temperature and different nitrogen contents were negative, and strongly decreased with the increase in nitrogen/argon ratio. The Ta 2 N films deposited at a nitrogen/ argon ratio of 3% show higher TCR values and thermal stability of the resistance in the 25-120°C temperature range. The Ta 2 N films deposited at a nitrogen/argon ratio of 3% and a temperature of 200°C showed a TCR value of -47 ppm/K, which is close to near-zero TCR in the range of deposition temperature.

Effect of the deposition temperature on temperature coefficient of resistance in CuNi thin film resistors

A constantan composition of Cu54Ni46 showing an near zero TCR value was obtained using a Ni power of 100W and a Cu power of 50W by dc magnetron cosputtering. The grain size increases and resistivity of the films decreases with increasing deposition temperature. The crystallinity of the films definitely influences the TCR value, which is an important parameter in resistor devices. The films deposited at 100°C exhibited a near zero TCR value of approximately 5ppm∕°C and the positive TCR values increased with increasing deposition temperature. The films deposited above 100°C do not exhibit irreversibility of the resistance with increasing deposition temperature.

Effect of Chromium Concentration on the Electrical Properties of NiCr Thin Films Resistor Deposited at Room Temperature by Magnetron Cosputtering Technique

NiCr films, 100 nm thick, were prepared on SiO 2 (600 nm)/Si substrates at room temperature as a function of chromium concentration by the cosputtering technique. The crystalline nature and electrical properties of the NiCr films were investigated as a function of chromium concentration. The films with a chromium concentration up to 39% showed a crystalline structure having a low resistivity, a high root-mean-square (rms) roughness, and positive temperature coefficient of resistivity (TCR) values. The films with a chromium concentration above 39% exhibited the amorphous structure with negative TCR values. The TCR values of the films with a chromium concentration of 39 and 42% are approximately +10 and -9 ppm/K, respectively. The TCR values approaching zero can be established by controlling the chromium concentration in the NiCr films.

Ti(N) thin film resistors for 20dB Π-type attenuator applications

The authors report the effect of the film thickness on electrical properties of Ti(N) film resistors. The applications of titanium nitride thin film resistor in Π-type attenuators are also characterized. As film thickness decreases from 100to30nm, the temperature coefficient of resistance significantly decreases from −60to−148ppm∕K, while the sheet resistance increases from 37to270Ω∕◻. The characterizations of 20dB attenuators using thin film resistors are improved in comparison with those using thick film resistors. The Π-type attenuators using Ti(N) thin film resistors exhibit an attenuation of −19.94dB and voltage standing wave ratio of 1.16 at a frequency of 2.7GHz.

Structural and Electrical Properties of NiCr Thin Films Annealed at Various Temperatures in a Vacuum and a Nitrogen Ambient for π -Type Attenuator Applications

NiCr thin films were prepared on SiO 2 /Si substrates using a magnetron co-sputtering technique and were annealed at various temperatures in a vacuum (3 X 10 -6 Torr) and a nitrogen ambient. The crystallinity of the films annealed in a vacuum ambient was higher than that of films annealed in nitrogen ambient. Samples annealed above 500°C in nitrogen ambient exhibited a second phase in the NiCr films. The incorporation of oxygen into the NiCr films produced the decrease of crystallinity and significantly influenced the temperature coefficient of resistance of the films.

Effect of annealing temperature on structural and electrical properties of tantalum nitride thin film resistors deposited on SiO2∕Si substrates by dc sputtering technique

Tantalum nitride thin films were deposited on SiO2 (600 nm)/Si substrates at 200 °C and a nitrogen/argon flow ratio of 3% by dc sputtering technique and then were annealed at various temperatures in vacuum and nitrogen ambients. For the films annealed in both vacuum and nitrogen ambients, the effect of annealing temperature on structural and electrical properties of the films was systematically investigated. Crystallinity of the films was significantly improved as annealing temperature increased. Temperature coefficient of resistance (TCR) of the films was varied from a negative value to a positive value with increasing annealing temperature in both vacuum and nitrogen ambients. The variation of TCR with annealing temperature in both vacuum and nitrogen ambients was due to the improved crystallinity rather than a nitrogen concentration in the films. Irrespective of annealing temperature, the films annealed at various temperatures do not exhibit the irreversibility of resistance.

Structural and Electrical Properties of TiN x O y Thin-Film Resistors for 30 dB Applications of π -type Attenuator

Titanium oxyhonitride (TiN x O y ) thin films were deposited on SiO 2 /Si substrates using reactive dc magnetron sputtering and were then annealed at various temperatures in air ambient to incorporate oxygen into the films. The effect of annealing temperature on the structural and electrical properties of the films was investigated. The grain size of the films decreases with increasing annealing temperature. Crystallinity of the films is independent of annealing temperature in air ambient. Resistivity of the films increases remarkably as an annealing temperature increases and temperature coefficience of resistance (TCR) of the films varies from a positive value to a negative value. The films annealed at 350°C for 30 min exhibited a near-zero TCR value of approximately -5 ppm/K. The decrease of the grain size with increasing annealing temperature was attributed to an increase of oxygen concentration incorporated into the films during annealing treatment.

Effects of Nitrogen Concentration on Structural and Electrical Properties of Titanium Nitride for Thin-Film Resistor Applications

Titanium nitride thin films were deposited on SiO 2 /Si substrates at various nitrogen/argon flow ratios [N 2 /(N 2 + Ar)] using a radio frequency-reactive magnetron sputtering. The structural and electrical properties of the films deposited at room temperature are characterized as a function of nitrogen/argon flow ratio. The Ti(N) phases by a nitrogen incorporation into Ti lattice up to 5% were formed and TiN phases are observed as nitrogen/argon flow ratios increase above 7%. The resistivity and temperature coefficient of resistance (TCR) values of films are strongly influenced on the phases of Ti(N) and TiN formed by different nitrogen/argon flow ratios. A near-zero TCR value of approximately 9 ppm/K was observed for films deposited at nitrogen/argon flow ratio of 3%.

Effect of film thickness on the electrical properties of tantalum nitride thin films deposited on SiO2∕Si substrates for Π-type attenuator applications

Ta2N films were deposited on SiO2∕Si substrates using reactive dc magnetron sputtering, and were then annealed in a vacuum ambient. The structural and electrical properties of Ta2N films and their dependence on the film thickness (50–200nm) were characterized with respect to their application as Π-type attenuators. The root mean square roughness and temperature coefficient of resistance (TCR) increased with increasing film thickness. The near zero TCR value of the films is possible by controlling the annealing temperature or film thickness. The sheet resistance and TCR of 50nm thick Ta2N films are approximately 80Ω∕◻ and −24ppm∕K, respectively, and are suitable for 10dB applications in Π-type attenuators.

The Structural and Electrical Properties of CuNi Thin-Film Resistors Grown on AlN Substrates for Π -Type Attenuator Application

A constantan composition of Cu 5 4 Ni 4 6 showing a near-zero temperature coefficient of resistance (TCR) value was obtained on AlN substrates using a Ni power of 100 W and a Cu power of 50 W by dc magnetron cosputtering. The grain size increases and resistivity of the films decreases with increasing deposition temperature. The crystallinity of the films definitely influences the TCR value, which is an important parameter in resistor devices. The films deposited at 100°C exhibited a near-zero TCR value of approximately 7 ppm/°C and the positive TCR values increased with increasing deposition temperature. The films deposited above 100°C do not exhibit irreversibility of the resistance with increasing deposition temperature.