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

摘要

The characteristics of silicon-nitride deposited at the temperature lower than 100 ℃ using an internal linear-type inductively coupled plasma were investigated as functions of the NH_3/SiH_4 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 NH_3/SiH_4 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 .150V and NH_3/SiH_4 ratio of 2 showed the lowest interface trap charge density of about 2 × 10~(11) cm~(-2). Under these conditions, the dielectric constant was as high as 7.2.