How are guard rings used in IC layout to improve reliability and performance?
Guard rings improve the performance of silicon devices by isolating them from each other. They create a low resistance ring in the well or substrate around the device group. Guard rings improve the performance of silicon detectors by reducing electric fields at the edges of junctions, which helps in several ways:
Preventing Charge Buildup
The guard rings help prevent charge build up by other nearby devices. This ensures that the operation of the guarded device group is not influenced by unwanted charges.
Read also: Antenna Prevention Techniques in VLSI Design
Stabilizing Potential
Guard rings prevent fluctuating potentials from other devices from affecting the guarded group. By maintaining a stable potential, they enhance the reliability and performance of the devices.
Leakage Current Reduction
Guard rings reduce the leakage current in the main device, which enhances the detector’s performance. When guard rings are biased, they help in collecting carriers generated in the peripheral regions, preventing these carriers from increasing the leakage current in the main junction.
Read also: Guard rings, Wells, Deep N-well, Dummy devices – Analog Layout
High-Voltage Operation
Guard rings enable detectors to operate at higher voltages by reducing the electric field intensity at the junction edges. This reduction prevents breakdown and allows the detector to handle higher voltages without damage.
Spectroscopic Performance
Guard rings improve the spectroscopic performance of silicon detectors. When the guard rings are grounded, the extra peaks in the spectrum (caused by particles hitting the guard ring region) are minimized, resulting in a cleaner and more accurate measurement.
Guard rings ensure that each device operates independently and without interference from neighboring devices, leading to more consistent and reliable performance.
How are guard rings used in IC layout to improve reliability and performance(image source)
