Modern semiconductor detectors developed for sensing charged particles in full depletion mode typically contain an inactive area near the edges of the device. This scheme allows for dicing the wafers with standard saw or laser-based singulation methods leading to conductive sidewall of the device due to large defect densities.
However, the existence of the up to 1 mm wide inactive band leads to efficiency gaps when a larger surface is covered with many such devices in a simple pavement arrangement. More complicated tiling construction scheme and support methods have to be used, and a larger amount of inactive material has to be present in a system. Researchers at UCSC in collaboration with the U.S. Naval Research Laboratory (NRL) have developed two methods for fabricating resistive semiconductor sidewalls in close proximity to the active area. The methods can be used to make compact sensor devices with minimal inactive periphery. The method could also be used for IC (integrated circuit) production, power electronics IC production, radiation detector (or sensor) production, imaging sensors, and solar cell production.
UCSC’s and NRL’s researchers have developed, prototyped and evaluated methods for fabricating resistive sidewalls that can be placed in a close proximity to an active region of the sensor with high electric field. The basic technology involved laser scribing of the sensor surface followed by cleaving and post-processing of the sidewall. The low defect density of the cleaved surface, followed by imposition of a proper interface charge creates the resistive sidewall. For n-type silicon an elevated temperature or UV light exposure is adequate to form the passivating oxide. PECVD (plasma enhanced chemical vapor deposition) is another way to form an oxide passivation. For p-type silicon an ALD (atomic layer deposition) deposition of alumina creates a negative interface charge, needed to passivate the edge. Sensors have been created with distance between the active area and the sidewall as small as 14 microns.
Applications
Method for Laser-Scribing of Semiconductor Devices with Advanced Sidewall Passivation
Advantages
Two methods for fabricating resistive semiconductor sidewalls in close proximity to the active area. The methods can be used to make compact sensor devices with minimal inactive periphery.
Intellectual Property Information
Patent Pending
Tech ID: 22521 / UC Case 2011-253-2
