Ideal RESURF Geometries

Abstract

In order to maximize the OFF-state breakdown voltage (BV) of semiconductor devices, the slope of the electric field in the drift extension along the current flow direction (E x field) should be zero. This is achieved using the reduced surface field (RESURF) effect. This paper demonstrates a method to construct devices that obey Poisson's equation and satisfy the ideal RESURF condition giving zero slope in E x throughout the 2-D device region. The designs are obtained by shaping the device geometry and the boundaries and by applying the proper potentials at the boundaries. Using this method, ideal designs of the drift extension have been derived for devices based on graded doping, graded thickness, and graded fieldplate potential. In addition, 2-D solutions have been derived for periodic superjunction device geometries. A solution for devices that combine several types of field shaping is demonstrated. Finally, the effect of nonideal geometries on the BV in more realistic geometries is discussed.

Effective Concentration Profile: A Novel 1-D Analysis of the Variation of Lateral Thickness (VLT) Lateral Power Devices

“…This concept further stimulates the revolutionary techniques such as Variable of Lateral Diffusion (VLD) and Variable of Lateral Thickness (VLT). Both the VLD and VLT are featured as their ability to achieve an even surface electric field profile and the most desirable lateral BV characteristic [10]- [12]. Due to the linear doping profile of VLD, a lightly doped drift region near the PN junction is formed which inevitably causes severe local self-heating and on-state characteristic deterioration [7], [9].…”

Field-plate assisted RESURF power devices : gradient based optimalization, degradation and analysis

“…Finally, non-optimal design of the lateral electrode boundaries (Anode/Source, Cathode/Drain) introduces E x non-idealities that limit optimal lateral breakdown. Although not a big issue for the breakdown voltage ranges discussed here (>150 V), an in-depth discussion on electrode design is given in [60]. …”

“…One such an example is the use of deep trenches filled with a dielectric at the device boundary. For instance since the working principle of (bulk) superjunction RESURF is based on n/p pillar periodicity [31,60] it can be hypothesized that because of this potential boundary mirroring a non-ideal edge boundary will cause premature edge breakdown limiting breakdown in the entire superjunction configuration. Therefore in this type of device an optimized edge termination as for instance reported in [115] is essential.…”

“…Based on this, a generalized expansion that includes super junction based RESURF and the importance of curved contact electrodes is presented in [60].…”

“…(2.1) have to be changed to include non-constant boundary conditions. To fully optimize the potential distribution uniquely shaped terminal connections, as discussed in [60], might also be necessary.…”