Effect of DC Bias Voltage on the Characteristics of Low Temperature Silicon–Nitride Films Deposited by Internal Linear Antenna Inductively Coupled Plasma Source

The characteristics of silicon–nitride deposited at the temperature lower than 100 °C using an internal linear-type inductively coupled plasma were investigated as functions of the NH3/SiH4 ratio and ion bombardment energy applied to the substrate (dc bias voltage) for use as the gate dielectric material of flexible display devices. Decreasing the NH3/SiH4 ratio to 2 and increasing the dc bias voltage to -150 V decreased the Si–O bonding and increased the Si–N bonding, resulting in a more nitrogen-rich SiN x thin film. In addition, the capacitance-voltage measurement of the metal-insulator-semiconductor devices fabricated with the SiN x thin film deposited at various dc bias voltages showed a hysteresis curve in the cyclic voltage measurement and the increase of the dc bias voltage with decreasing hysteresis voltage. The interface trap density measured at a dc bias voltage of -150 V and NH3/SiH4 ratio of 2 showed the lowest interface trap charge density of about 2×1011 cm-2. Under these conditions, the dielectric constant was as high as 7.2.