DC Characteristics Optimization of a Double G-Shield 50 V RF LDMOS

Abstract EN

An N-type 50 V RF LDMOS with a RESURF (reduced surface field) structure of dual field plates (grounded shield, or G-shield) was investigated.

The effect of the two field plates and N-drift region, including the junction depth and dopant concentration, on the DC characteristics was analyzed by employing the Taurus TCAD device simulator.

A high BV (breakdown voltage) can be achieved while keeping a low R DSON (on-resistance).

The simulation results show that the N-drift region dopant concentration has an obvious effect on the BV and R DSON and the junction depth affected these values less.

There is an optimized length for the second field plate for a given dopant concentration of the N-drift region.

Both factors should be optimized together to determine the best DC characteristics.

Meanwhile, the effect of the first field plate on the BV and R DSON can be ignored.

According to the simulation results, 50 V RF LDMOS with an optimized RESURF structure of a double G-shield was fabricated using 0.35 µm technologies.

The measurement data show the same trend as the TCAD simulation, where a BV of 118 V and R DSON of 26 ohm·mm were achieved.