Compound Semiconductor X-Ray Detector Tiles With Low-Damage Dicing
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Solution Overview
Problem
Dicing compound semiconductor wafers, particularly those with a (111) oriented zinc blende crystal structure, often result in defects such as chipping and dislocations due to the activation of in-plane and out-of-plane slip systems, leading to increased surface currents and reduced charge collection efficiency in radiation detectors like X-ray detectors.
Innovation Solution
Dicing the wafers at an angle between 13° and 17°, specifically 15°, relative to the major orientation flat, suppresses out-of-plane slip systems and creates left-right anisotropy, minimizing defects on the tile edges and allowing for the production of detector tiles with minimal defects on all sides by using sacrificial tiles between active detector tiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dicing is performed along conventional directions (parallel to {110} planes), then manufacturing simplicity is maintained, but dicing damage including chipping and dislocations increases
Solution Approach 1:
The patent applies asymmetry by rotating the dicing direction by 13° to 17° relative to the conventional {110} plane orientation. This asymmetric angle breaks the symmetry of slip system activation, suppressing out-of-plane slip systems while maintaining in-plane slip control, thereby reducing dicing damage and improving edge quality without requiring completely new manufacturing equipment
Solution Approach 2:
The patent changes the dicing angle parameter from the conventional 0° (parallel to {110}) to a rotated angle of 13° to 17°. This parameter change fundamentally alters which slip systems are activated during dicing, suppressing harmful out-of-plane slip while maintaining manufacturing feasibility through standard dicing equipment
2Productivity
If dicing is performed to maximize tile yield, then productivity increases, but dicing damage and surface currents increase
Solution Approach 1:
By changing the dicing angle parameter to 13°-17° rotation from conventional orientations, the patent simultaneously achieves high tile yield and reduced dicing damage. The rotated angle suppresses out-of-plane slip systems that cause dislocations and chipping, thereby improving charge collection efficiency while maintaining productive manufacturing rates
3Reliability
If conventional dicing directions are used, then manufacturing simplicity is maintained, but leakage current and surface currents increase
Solution Approach 1:
The asymmetric rotation of 13° to 17° from conventional dicing orientations selectively suppresses out-of-plane slip systems that generate dislocations and chipping at tile edges. This reduction in structural defects directly decreases leakage current and surface currents, improving detector reliability while using standard dicing equipment
Solution Approach 2:
Changing the dicing angle parameter to a rotated orientation of 13°-17° fundamentally alters the slip system activation pattern during dicing. This parameter change reduces crystallographic defects that serve as leakage paths, thereby reducing leakage current and surface currents without requiring complex new manufacturing processes
Data Source
AI summary
A radiation detector tile includes a single crystal compound semiconductor tile having a zinc blende crystal structure, a (111) plane first major (i.e. prominent) surface and four side surfaces which are rotated by an angle of 13° to 17° to a {110} family of planes. The tile may be formed by dicing a (111) oriented wafer at directions which are rotated by an angle of 13° to 17° from <110> in-plane slipping directions to reduce or eliminate the side surface chipping and sub surface dislocation defects.