Schottky Diode Anode Encircling P-Type Region
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Solution Overview
Problem
Current cobalt silicide Schottky diodes integrated into BiCMOS fabrication processes exhibit higher leakage currents in reverse bias due to generation-recombination sites in silicon, which is undesirable for most circuit applications.
Innovation Solution
The integration of a floating p-type region encircling the cobalt silicide anode in the Schottky diode, formed without additional fabrication steps, which prevents metal silicide formation and creates depletion regions that reduce leakage current by removing charge generated by these sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If cobalt silicide is formed on silicon Schottky diode surface, then low voltage drops in forward biased operation are achieved, but higher leakage currents in reverse bias operation occur due to generation-recombination sites
Solution Approach 1:
An intermediate p-type region is introduced between the n-type cathode and the cobalt silicide anode. This p-type region acts as a mediator that prevents direct interaction between the n-type silicon and metal silicide, thereby eliminating generation-recombination sites while maintaining the Schottky junction's forward conduction properties
Solution Approach 2:
The doping type parameter is changed from n-type to p-type in the region adjacent to the metal silicide anode. This parameter change transforms the electrical characteristics of the junction, creating a p-n junction that suppresses reverse leakage current through depletion region formation while preserving forward bias performance
2Object-generated harmful factors
If p-type doped region is added to encircle the anode, then leakage current is reduced by removing charge generated by generation-recombination sites, but device complexity increases
Solution Approach 1:
The p-type region formation is merged with existing fabrication processes such as ion implantation or diffusion steps that are already used for creating other doped regions in the device. By combining multiple functions into a single process step, the patent reduces fabrication complexity while achieving the desired leakage current reduction
Solution Approach 2:
The p-type doped region serves multiple functions: it eliminates generation-recombination sites to reduce leakage current, creates a depletion region to block reverse current, and can be formed using standard fabrication processes. This multi-functionality reduces the need for additional specialized process steps
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 configuration effectively reduces leakage current in reverse bias operation by eliminating charge generation sites, enhancing the current-voltage relationship and performance of Schottky diodes.
Implementation Method 1
creates depletion regions that reduce leakage current by removing charge generated by these sites
Data Source
AI summary
An integrated circuit includes a Schottky diode having a cathode defined by an n-type semiconductor region, an anode defined by a cobalt silicide region, and a p-type region laterally annularly encircling the cobalt silicide region. The resulting p-n junction forms a depletion region under the Schottky junction that reduces leakage current through the Schottky diodes in reverse bias operation. An n+-type contact region is laterally separated by the p-type region from the first silicide region and a second cobalt silicide region is formed in the n-type contact region. The silicided regions are defined by openings in a silicon blocking dielectric layer. Dielectric material is left over the p-type region. The p-type region may be formed simultaneously with source/drain regions of a PMOS transistor.