Parameter extraction and 1/f noise in a surface and a bulk-type p-channel LDD MOSFET

channel LDD MOSFETs with a p+-poly gate and an n+-poly gate are investigated. The p+-poly gate forms a surface channel and the n +-poly gate a bulk channel. A new method is proposed to use an L-array for extracting the low field mobility pW, the mobility degradation coefficient 0, the channel length correction I’, and the parameters R, and R,, for the gate-voltage-dependent series resistance on the source side R,, = R,, + R,, / I$. A bulk channel device has a higher fiW value, a lower R,, and a smaller series resistance R,, on the drain side than a surface channel device. The 0 value and the gate-voltage-independent part of the series resistance R,, are about the same in both devices. Under the same external bias conditions, a surface channel MOSFET has a smaller current and a higher l/f current noise than a bulk channel device. The l/Jnoise parameter G( is found to be independent of the effective gate voltage and of the channel length for both devices. The bulk channel MOSFET shows a values of about 4 x lo-’ which are among the lowest values ever reported in literature. The a values in the surface channel devices are about two orders of magnitude higher than those in the bulk type. Comparing the d.c. characteristics and I if noise of both devices, an indication is given on how to reduce the l/f noise in a surface p-channel MOSFET