LDMOS Metal Field Plate Contact in STI for Drift Region Resistance
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Solution Overview
Problem
LDMOS transistors face limitations in achieving high output power with sufficient drain to source breakdown voltage and maximum power gain frequency, particularly in RF power amplifiers, due to challenges in doping profiles and electric field resistance.
Innovation Solution
The integration of a metal field plate contact within a shallow trench isolation structure in LDMOS transistors, which improves performance by attracting electrons and reducing resistance in the drift region, thereby enhancing transconductance, breakdown voltage, and reducing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LDMOS fabrication with ion implantation is used, then doping profile can be achieved, but electric field resistance and breakdown voltage are limited
Solution Approach 1:
A metal field plate contact is introduced as an intermediary element between the gate structure and the drift region. This metal contact extends into the shallow trench isolation structure and serves as a mediator to attract and control electrons in the drift region, thereby enhancing breakdown voltage without requiring complex multi-step ion implantation doping profiles.
Solution Approach 2:
The invention changes the electrical parameters of the drift region by introducing a metal field plate contact that modifies the electric field distribution. This parameter change approach allows achieving higher breakdown voltages and improved transconductance without altering the fundamental doping profile complexity of the LDMOS structure.
2Manufacturing precision
If multiple ion implantation sequences are used to achieve appropriate doping profile, then drift region performance improves, but manufacturing process complexity increases
Solution Approach 1:
The metal field plate contact acts as an intermediary that compensates for manufacturing precision requirements. By introducing this metal structure that extends into the shallow trench isolation, the system achieves precise electric field control and drift region performance without requiring extremely precise multi-sequence ion implantation processes.
Solution Approach 2:
Instead of relying solely on precise doping profiles achieved through multiple ion implantation sequences, the invention changes the approach by using a metal field plate contact to control electrical parameters. This reduces the need for complex fabrication processes while maintaining manufacturing precision through the metal structure's geometric control.
3Reliability
If metal field plate contact is integrated, then transconductance and breakdown voltage improve, but device structure complexity increases
Solution Approach 1:
The metal field plate contact serves multiple functions simultaneously: it acts as a gate contact for electrical connection, extends into the shallow trench isolation to control the electric field in the drift region, and attracts electrons to enhance transconductance. This multi-functionality reduces the need for separate structures, thereby limiting the increase in overall device complexity while achieving improved performance.
Solution Approach 2:
The metal field plate contact extends vertically into the shallow trench isolation structure, utilizing the third dimension (depth) to achieve its function. This dimensional approach allows the contact to influence the drift region electric field without requiring additional lateral structures, thereby improving transconductance and breakdown voltage with minimal increase in planar device complexity.
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 metal field plate contact effectively improves transconductance, reduces resistance, and increases breakdown voltage, leading to enhanced performance in RF power amplifiers by optimizing the doping profile and electric field distribution.
Implementation Method 1
improves performance by attracting electrons and reducing resistance in the drift region
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a transistor with a metal field plate contact and methods of manufacture. The structure includes: a gate structure on a semiconductor substrate; a shallow trench isolation structure within the semiconductor substrate; and a contact extending from the gate structure and into the shallow trench isolation structure.