ESD Diode Epitaxy Growth for Leakage Current Reduction
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Solution Overview
Problem
In the integration of ESD diode formation with FinFET processes, large epitaxy regions for anode and cathode pickup regions often result in significant leakage currents due to thickness variations, affecting electro-migration performance and ESD current discharge efficiency.
Innovation Solution
The method involves forming epitaxy regions from semiconductor fins with simultaneous growth and doping to achieve uniform thickness, decoupling the formation of p-type epitaxy regions from silicon germanium stressors, using silicon regions to act as large p-type epitaxy regions, and forming n-type pickup regions to reduce leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large epitaxy regions are formed by merging epitaxially grown pickup regions from neighboring fins, then large anode and cathode pickup regions are achieved for good electro-migration performance, but significant leakage currents are generated due to thickness variations
Solution Approach 1:
The patent segments the epitaxial growth process into two distinct stages: first forming thin epitaxy regions that merge to create large pickup regions, then performing a second epitaxial growth to uniformly increase the thickness of all regions. This segmentation resolves the contradiction by maintaining the large area benefit while eliminating the thickness variation problem through staged growth.
Solution Approach 2:
The patent performs preliminary epitaxial growth to form the basic large pickup regions before the final thickness enhancement step. This preliminary action establishes the large area structure needed for electro-migration performance, and the subsequent thickness uniformization step eliminates leakage currents without compromising the already-established large pickup region geometry.
2Productivity
If epitaxy regions are grown simultaneously from multiple fins, then large pickup regions are formed efficiently, but thickness uniformity is compromised leading to leakage currents
Solution Approach 1:
The patent divides the epitaxial growth into two sequential processes: a first growth phase that efficiently creates large merged pickup regions from multiple fins, and a second growth phase that uniformly increases thickness across all regions. This segmentation maintains the productivity benefit of simultaneous growth while achieving the precision needed for thickness uniformity.
Solution Approach 2:
The patent changes the epitaxial growth parameters between two stages: the first stage uses parameters optimized for lateral expansion and merging to form large regions efficiently, while the second stage uses parameters optimized for uniform vertical thickness increase. This parameter change resolves the contradiction between productivity and manufacturing precision.
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 leakage currents in ESD diodes by ensuring uniform thickness of epitaxy regions, preventing contact plug penetration through p-n junctions and enhancing ESD current discharge efficiency without additional process steps or lithography masks.
Implementation Method 1
perform an epitaxy growth to form an epitaxy region comprising silicon and substantially free from germanium
Data Source
AI summary
A method includes forming an ESD diode including performing an epitaxy growth to form an epitaxy region comprising silicon and substantially free from germanium. The epitaxy region is doped with a p-type impurity to form a p-type region, wherein the p-type region forms an anode of the ESD diode.