Vertical hall sensor of high sensitivity and excellent confinement fabricated on the (110) silicon substrate

Abstract

A vertical Hall sensors fabricated on a (110) silicon substrate with good sensitivity and carrier confinement was demonstrated. It is known that sensitivity of a Hall sensor is related to carrier confinement and the thickness of a Hall plate. However, traditional vertical Hall plates fabricated on a (100) silicon substrate have difficulty in achieving high aspect ratio of the depth (corresponding to the width of a Hall plate) to the width (corresponding to the thickness of a Hall plate) of an etched `wall' for carrier confinement. Wet etching tends to form sloped sidewalls due to the formation of V-grooves on (100) silicon substrates while drying etching takes much time to form deep trenches. Therefore we propose to fabricate vertical Hall plates fabricated on (110) silicon substrate in this paper. It is well known that deep vertical walls can be fabricated on (110) silicon substrates by TMAH an-isotropic etching, which means that vertical Hall plates with high aspect ratio can easily formed by this simple wet etching. Experimental results from the vertical Hall sensors on (110) substrates showed a sensitivity of 64.1 V/AT, which is higher than that obtained by micro-machined vertical Hall sensor on (100) substrate.