Semiconductor Sidewall Passivation via Chemical Etching
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Solution Overview
Problem
Radiation detectors face challenges with inactive areas in border regions due to mechanical damage from dicing and the need for guard rings, which limits their performance and increases costs with time-consuming and costly trench micro-fabrication processes.
Innovation Solution
A method of singulating semiconductor devices by controlling interface charge on sidewalls through scribing, cleaving, and coating with passivation materials, which reduces the need for guard rings and inactive areas by creating a fixed charge density that interacts with charge carriers, allowing for closer proximity to active structures and minimizing peripheral inactive regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dicing is performed using a diamond blade to separate semiconductor devices, then individual devices can be separated, but mechanical damage is generated on the cut surface leading to damaged silicon regions that promote electric breakdowns
Solution Approach 1:
The patent extracts the harmful mechanical dicing process and replaces it with a chemical etching process using KOH solution. This removes the diamond blade cutting step that causes mechanical damage, while still achieving device separation through selective etching along scribed lines.
Solution Approach 2:
The patent substitutes the mechanical dicing system (diamond blade) with a chemical etching system (KOH solution). The mechanical cutting action is replaced by chemical dissolution, which etches along crystallographic planes to create clean separation without mechanical damage to the silicon lattice.
2Reliability
If guard rings are used to protect active regions from dicing damage and to separate active from border regions, then electrical performance is improved, but the inactive area increases reducing the active detection area
Solution Approach 1:
The patent removes the guard ring structure entirely by using chemical etching to create a clean separation between devices. The etched edges naturally provide electrical isolation without requiring additional guard ring structures, thus eliminating the inactive area associated with guard rings while maintaining electrical performance.
Solution Approach 2:
The chemical etching process creates self-isolating device edges by removing silicon along the scribed lines. The etched edges naturally form electrical isolation barriers without requiring separate guard ring structures, allowing the device to self-isolate and maximizing the active detection area.
3Reliability
If trench micro-fabrication is performed using RIE or DRIE to form active edges, then edge protection is achieved, but the process becomes time-consuming and costly
Solution Approach 1:
The patent uses a simple, inexpensive KOH chemical etching process instead of complex and expensive RIE or DRIE equipment. The KOH etching is a mature, low-cost process that achieves sufficient edge protection without requiring the sophisticated plasma equipment and long processing times of reactive ion etching methods.
Solution Approach 2:
The patent changes the etching methodology from physical/sputter-based RIE or DRIE to chemical dissolution-based KOH etching. This parameter change in the etching mechanism provides adequate edge protection with simpler equipment, lower cost, and reduced processing time while still achieving the necessary device separation and edge definition.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the inactive area around semiconductor devices, enhancing electrical performance, reducing leakage currents, and enabling more efficient production of radiation detectors with reduced peripheral defects, thus improving the overall efficiency and cost-effectiveness of detector arrays.
Implementation Method 1
the passivation material is disposed to provide a fixed charge density at a semiconductor interface of the sidewalls, and the fixed charge density interacts with charge carriers in the bulk of the material
Implementation Method 2
using a coating process to coat the sidewalls of the cleaved semiconductor device with a passivation material
Data Source
AI summary
A method of singulating semiconductor devices in the close proximity to active structures by controlling interface charge of semiconductor device sidewalls is provided that includes forming a scribe on a surface of a semiconductor devices, where the scribe is within 5 degrees of a crystal lattice direction of the semiconductor device, cleaving the semiconductor device along the scribe, where the devices are separated, using a coating process to coat the sidewalls of the cleaved semiconductor device with a passivation material, where the passivation material is disposed to provide a fixed charge density at a semiconductor interface of the sidewalls, and where the fixed charge density interacts with charge carriers in the bulk of the material.