Dual Trench Scheme for Preventing Punch-Through and Cross Talk Between Devices
Original Publication Date: 2003-Mar-10
Included in the Prior Art Database: 2003-Mar-10
Ronghua Zhu: AUTHOR [+5]
This publication proposes dual trench scheme in a deep trench isolated Smart Power Technology to prevent leakage, punch-through and cross-talk between devices.
Dual Trench Scheme for Preventing
Abstract --- This publication proposes dual trench scheme in a deep trench isolated Smart Power Technology to prevent leakage, punch-through and cross-talk between devices.
The minimum feature size of modern Smart Power Technologies has been reduced significantly in recent years to reduce the die size and cost. While the core of the device has been shrunk due to finer lithography, the size of device isolation remains almost the same since the isolation is still required to support high voltage. Deep trenches have been used to reduce the device isolation area. Packing density can be improved by ~ 50% for most of the devices due to the deep trench.
One of the key issues in deep trench isolation is the possible inversion on trench surface. Deep trench fabrication processes such as trench etching may introduce oxide charges. This will provide undesirable leakage path between devices. In addition, high voltage biasing on one device may causes inversion, accumulation or depletion on the device across the trench and causes cross-talk.
To address the problem, a channel stop has been introduced at the bottom of the trench  to block the leakage path. This not only complicates fabrication process due to implanting on the trench sidewall but also requires an extra masking step. Fu...