Power Semiconductor Contact Structure for Self-Aligned JBS Ohmic Contacts
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Solution Overview
Problem
Existing junction barrier Schottky (JBS) diodes face challenges in accurately positioning the ohmic contact during manufacturing, leading to misalignment and leakage issues, which affect their performance and functionality.
Innovation Solution
The power semiconductor structure includes a substrate with an epitaxial layer, a groove, a doped region, and a contact member, where the contact member is positioned at a specific location using a self-alignment method through controlled thickness of a patterned mask, ensuring uniform lateral distances and interfaces, thereby reducing reverse leakage current and enhancing surge current handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used to form the contact member, then the manufacturing process is simple, but the contact member cannot be precisely positioned, leading to misalignment and leakage
Solution Approach 1:
The patent applies preliminary action by forming the doped region before forming the contact member. The doped region serves as a pre-positioned guide that determines the exact location where the contact member will be formed, ensuring precise alignment without requiring complex positioning steps during contact member formation. This preliminary doping step establishes the geometric constraints that guide subsequent manufacturing steps.
Solution Approach 2:
The patent introduces a dielectric layer as an intermediary element between the doped region and the contact member. This dielectric layer is conformally deposited and then selectively removed to expose the doped region, serving as a temporary mediator that protects surrounding areas while enabling precise contact member formation. The intermediary layer facilitates controlled material removal and deposition processes that achieve high positioning precision.
2Reliability
If the contact member is not precisely positioned, then the manufacturing process is easier, but reverse leakage current increases and performance deteriorates
Solution Approach 1:
The patent applies local quality by creating a doped region with specific electrical properties at a precise location beneath the contact member. This localized doping provides both the electrical function (low resistance ohmic contact) and the geometric function (positioning guide). The local modification of material properties through doping ensures that the contact member forms only at the intended location with correct electrical characteristics, preventing leakage paths.
Solution Approach 2:
The preliminary formation of the doped region establishes the exact position and dimensions for the contact member before the contact member itself is formed. This preliminary structural element ensures that when the contact member is subsequently formed, it automatically aligns with the predetermined position, guaranteeing proper electrical contact and preventing misalignment-induced leakage.
3Productivity
If conventional methods are used without self-alignment, then fewer process steps are required, but uniform lateral distances cannot be achieved, resulting in leakage
Solution Approach 1:
The dielectric layer acts as an intermediary that enables uniform lateral distancing. By conformally depositing the dielectric layer over the doped region and then selectively removing portions, the process creates precisely controlled gaps with uniform lateral distances between the contact member and surrounding structures. This intermediary approach achieves geometric precision that would be difficult to obtain through direct patterning methods.
Solution Approach 2:
The preliminary conformal deposition of the dielectric layer establishes a uniform thickness profile that serves as a template for subsequent selective removal. This preliminary uniform layer ensures that when material is removed to expose the doped region, the remaining structures maintain uniform lateral distances, achieving geometric precision without requiring complex real-time adjustment processes.
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 allows for precise placement of the contact member, reducing leakage and enabling the semiconductor structure to withstand higher voltages and currents without damage, suitable for high-voltage applications.
Implementation Method 1
implanting a dopant into the epitaxial layer exposed from the opening to form a doped region
Data Source
AI summary
A method of manufacturing a power semiconductor structure includes forming a groove extending from a surface of an epitaxial layer into the epitaxial layer. A doped region is formed in the epitaxial layer under the groove. A first dielectric layer is disposed on the epitaxial layer exposing the doped region from the groove. A second dielectric layer is disposed on the first dielectric layer, the doped region and a sidewall of the groove. A portion of the second dielectric layer disposed on the doped region is removed to expose a portion of the doped region, on which a contact material is disposed to form a contact member. The contact member may be formed on the portion of the doped region or partially surrounded by the doped region. A remaining portion of the first dielectric layer and the second dielectric layer is then removed. The groove is optional.