Silicon Channel Isolation by Ion Implantation for Stress-Safe IC Layouts
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Solution Overview
Problem
Conventional Shallow Trench Isolation (STI) methods in integrated circuit layouts introduce lithography and stress proximity effects, which are detrimental for scaled standard cells and SiGe technology, while active isolation gates can lead to higher current leakage and parasitic capacitive load.
Innovation Solution
The process involves replacing active isolation gates with passive dielectric separations achieved through in-situ oxidation of silicon using oxygen or nitrogen ion implantation, eliminating the need for etching and preserving engineered mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Shallow Trench Isolation (STI) methods are used to isolate adjacent transistors, then electrical separation between transistors is achieved, but lithography and stress proximity effects are introduced that are detrimental for scaled standard cells and SiGe technology
Solution Approach 1:
The patent removes the silicon channel material from the isolation region through selective etching, extracting the problematic conductive element that causes both electrical leakage and stress proximity effects. This creates a void that is then filled with dielectric material, eliminating the source of harmful effects while maintaining electrical isolation.
Solution Approach 2:
The patent changes the material parameter in the isolation region from conductive silicon to insulating dielectric material. This parameter change transforms the isolation structure from one that provides electrical separation but causes stress proximity effects to one that provides both electrical isolation and stress relief, resolving the contradiction between electrical separation and harmful stress effects.
2Reliability
If active isolation gates are used to isolate transistors, then electrical separation is achieved, but current leakage increases and parasitic capacitive load is introduced
Solution Approach 1:
The patent uses a simple dielectric fill material in the isolation region that does not require active control or additional circuitry. This passive approach replaces complex active isolation gates with a straightforward material-based solution, eliminating parasitic capacitive loads and current leakage associated with active gate structures.
3Reliability
If etching techniques are used to obtain dielectric isolation, then electrical separation is achieved, but engineered mechanical stress is lost
Solution Approach 1:
The patent applies selective etching only to the isolation region while leaving the transistor channel regions intact. This segmented approach allows dielectric material to be introduced into isolation areas for electrical separation without affecting the engineered stress in the active transistor regions, thus resolving the contradiction between achieving electrical isolation and preserving mechanical stress.
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 provides superior electrical isolation between transistors, minimizes lithography and stress proximity effects, and maintains beneficial mechanical stress for SiGe-based technologies, thereby improving the performance and reliability of integrated circuits.
Implementation Method 1
directs a focused ion beam towards the silicon substrate to implant ions in the silicon substrate
Implementation Method 2
activate a reaction between silicon of the silicon substrate and the implanted ion to achieve formation of a dielectric material
Data Source
AI summary
A configuration to isolate ion implantation of silicon channels for placement of integrated circuit devices within an integrated circuit layout. The configuration layers a photolithographic mask having one or more openings on a silicon substrate. The configuration directs a focused ion beam towards the silicon substrate to implant ions in the silicon substrate at the one or more openings in the photolithographic mask. The configuration anneals the silicon substrate with the layered photolithographic mask to activate a reaction between silicon of the silicon substrate and the implanted ion to achieve an ionized formation in the silicon substrate.