Backside Decoupling Capacitor Layout for Latch-Up Isolation
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Solution Overview
Problem
The continuous miniaturization of transistors and increasing density on chips has led to increased susceptibility to latch-up phenomena, which can cause catastrophic failure due to inadvertent creation of low-impedance paths between power supply rails, triggered by electrical conditions such as overshoot and undershoot, and reduced robustness against parasitic PNPN structures in CMOS technology.
Innovation Solution
Implementing a spacer liner and shallow trench isolation over the backside contact to isolate N-well regions, forming backside decoupling capacitors that enhance capacitor density without sacrificing space, thereby preventing latch-up and stabilizing power integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistor density is increased and miniaturization is continued, then computational power and energy efficiency are enhanced, but susceptibility to latch-up phenomena increases
Solution Approach 1:
The device is segmented into distinct regions with different doping types (n-type and p-type regions separated by isolation structures). This segmentation prevents the formation of continuous parasitic PNPN paths that cause latch-up, while still allowing high-density transistor integration on the chip.
Solution Approach 2:
Isolation structures act as intermediary elements between n-type and p-type regions. These intermediaries block the formation of parasitic PNPN structures, preventing latch-up phenomena while maintaining the benefits of high-density integration.
2Area of stationary object
If decoupling capacitor density is increased to improve power integrity, then chip area is reduced, but latch-up risk increases due to closer spacing of doped regions
Solution Approach 1:
The chip layout is segmented into isolated n-type and p-type regions separated by isolation structures. This segmentation allows decoupling capacitors to be placed in available spaces without creating continuous parasitic paths, maintaining both high capacitor density and latch-up immunity.
Solution Approach 2:
Different regions of the chip have different local properties - n-type regions for nMOS devices, p-type regions for pMOS devices, and isolation structures in between. This local quality differentiation allows optimal placement of decoupling capacitors while preventing latch-up.
3Productivity
If n-type and p-type doped regions are placed close together to save space, then device density is improved, but parasitic PNPN structures are formed enabling latch-up
Solution Approach 1:
The harmful parasitic PNPN structures are extracted or prevented by introducing isolation structures between n-type and p-type regions. This removal of the harmful formation mechanism allows high device density without latch-up risk.
Solution Approach 2:
Isolation structures serve as intermediary barriers between closely spaced n-type and p-type regions. These intermediaries prevent the direct interaction that would form parasitic PNPN structures, enabling high device density while eliminating latch-up pathways.
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
The solution effectively prevents latch-up and enhances decoupling capacitor density, improving power integrity and reliability of semiconductor devices by reducing voltage fluctuations and noise, optimizing space utilization, and contributing to enhanced performance and reliability of electronic systems.
Implementation Method 1
a spacer liner and shallow trench isolation over the backside contact to isolate N-well regions
Implementation Method 2
forming backside decoupling capacitors that enhance capacitor density
Data Source
AI summary
A semiconductor device includes a passive device including a passive device including a first backside contact, a shallow trench isolation (STI) above the first backside contact and covering a top surface and an upper half of sidewalls of the first backside contact, and an interconnection layer covering a bottom surface of the first backside contact.