Extracting Concentrations from Arbitrary Shaped Well Regions

Introduction

It is often the case when simulating charged coupled devices (CCDs) or image sensors, that a designer wishes to know how many electrons or holes are contained within an arbitrary shaped n or p-well region for a given bias point or after exposure to light for a certain time and intensity.

The arbitrary shaped well will be defined by a metallurgic junction following all the process steps, usually simulated with the process simulator, ATHENA.

This article is for designers who feel that making the usual presumption that the well is rectangular in shape, will result in too great an error in the answer. If the well approximates to a rectangular shape, the usual area “Probe” statement will suffice. However, if the well has a very arbitrary shape, in order to obtain accurate numbers, we have to perform a numerical integration over the whole well shape. This numerical integration can be calculated using a series of extract statements inside a “LOOP” statement in the “Deckbuild” run time environment.