GaN Substrate Contact Diode for In-Process Charging Control
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Solution Overview
Problem
Conventional approaches to in-process charging control in GaN technologies on Si substrates are complex and limit scaling due to the need for deep and large area substrate connections, which incur significant area penalties and process complexity, especially in high-frequency RF applications.
Innovation Solution
The use of deep implants to connect an in-process substrate charging control structure to the substrate instead of traditional etch and metal fill processes, reducing complexity and area penalties, and enabling more aggressive lateral scaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional deep and large area substrate connections are used for charging protection, then charging control is achieved, but device complexity and area occupancy increase significantly
Solution Approach 1:
The patent changes the physical parameters of the substrate connection by using selectively doped regions with different conductivity types (n-type and p-type) instead of conventional metal fills. This allows the formation of diode structures that provide charging protection through controlled current flow paths, reducing the need for large area connections while maintaining protection functionality.
Solution Approach 2:
The patent replaces the mechanical/physical system of deep etching and metal fill processes with a semiconductor doping-based system. By using ion implantation and thermal diffusion to create doped regions, the solution eliminates complex mechanical fabrication steps while achieving the same electrical connection and protection function through controlled material properties.
2Reliability
If conventional deep and large area substrate connections are used for charging protection, then charging control is achieved, but die area is significantly reduced due to keep-away limits
Solution Approach 1:
The patent transitions from a two-dimensional planar connection approach to a three-dimensional vertical structure by creating deep doped regions that extend through the substrate thickness. This allows the charging protection function to be achieved with a smaller footprint on the device surface, as the protective diode structures utilize the vertical dimension of the substrate rather than requiring large lateral areas.
Solution Approach 2:
By changing the electrical parameters through selective doping, the patent creates low-resistance pathways vertically through the substrate without requiring large lateral connections. The doped regions provide sufficient current carrying capacity for charging protection while occupying minimal surface area, thereby increasing the effective die area available for functional circuitry.
3Reliability
If conventional deep and large area substrate connections are used, then charging protection is provided, but manufacturing cost increases due to area penalties
Solution Approach 1:
The patent creates doped regions that serve multiple functions: they provide charging protection through diode action, establish electrical connections to the substrate, and define active device regions. This multi-functionality eliminates the need for separate dedicated protection structures, reducing overall manufacturing complexity and cost while maintaining reliable charging protection.
Solution Approach 2:
The patent merges the charging protection function with the substrate connection function by using the same doped regions for both purposes. The selectively doped n-type and p-type regions simultaneously create the diode structure for protection and provide the low-resistance electrical pathway to the substrate, consolidating multiple functions into a single integrated structure that reduces manufacturing steps and cost.
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 solution effectively addresses the complexity and scaling limitations of conventional methods by allowing for efficient substrate charging control without the area and cost penalties of deep, large area substrate connections, enhancing the reliability and density of RF front-end technologies.
Implementation Method 1
Instead, deep implants are used to connect an in-process substrate charging control structure to the substrate
Data Source
AI summary
A substrate contact diode is disclosed. The substrate contact includes a first type substrate implant tap in a substrate, a second type epitaxial implant in an epitaxial layer that is on the substrate, and a first type epitaxial region above the second type epitaxial implant. A contact electrode that extends upward from the top of the first type epitaxial region to the surface of an interlayer dielectric that surrounds the contact electrode.