Semiconductor Cell Trench Structures with Recessed Contacts
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Solution Overview
Problem
Existing semiconductor device manufacturing methods face challenges in reliably creating narrow semiconductor mesas and small distances between cell trench structures while maintaining low costs and high precision.
Innovation Solution
The method involves forming first and second cell trench structures with buried electrodes and insulator layers in a semiconductor substrate, patterning a capping layer to create openings that expose the insulator layers, and removing the insulator layers to form recesses between the mesas and electrodes, allowing for the deposition of conductive material to form contact structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithographic masking methods are used to define cell trench structures and contact structures, then manufacturing precision can be maintained, but the distance between neighboring cell trench structures cannot be reduced and mesa width cannot be narrowed
Solution Approach 1:
The method uses self-aligned processes where the contact structure formation is automatically positioned relative to the cell trench structures through the insulator layer exposure, eliminating the need for separate photolithographic alignment steps. This self-service approach enables narrower mesas and smaller distances between structures while maintaining precision.
Solution Approach 2:
The invention transitions from planar 2D photolithographic patterning to 3D self-aligned patterning by using the insulator layer thickness as a dimensional reference. The opening width in the capping layer is deliberately made larger than the insulator layer thickness to ensure proper exposure and self-alignment, enabling reduced dimensions in the lateral plane.
2Manufacturing precision
If multiple photolithographic masks are used to define placement and size of cell trench structures and contact structures, then placement precision is maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The method merges the contact structure definition process with the cell trench structure formation process. By using a single capping layer opening that simultaneously defines both structures through self-alignment, the number of separate photolithographic masking steps is reduced, simplifying the manufacturing process while maintaining precision.
Solution Approach 2:
The capping layer opening serves multiple functions: it defines the contact structure position, exposes the insulator layer for recess formation, and establishes self-alignment between different structures. This multi-functional approach reduces the number of dedicated process steps required.
3Reliability
If conventional methods are used to form contact structures, then manufacturing reliability is maintained, but narrow mesas and small distances between cell trench structures cannot be achieved
Solution Approach 1:
The method performs preliminary actions by forming the insulator layer between the cell trench structures before defining the contact structures. This preliminary insulator layer formation establishes a reference that guides subsequent contact structure formation, enabling reliable narrow mesa fabrication. The capping layer opening is also preliminarily designed with width larger than insulator thickness to ensure proper exposure.
Data Source
AI summary
First and second cell trench structures extend from a first surface into a semiconductor substrate. The first cell trench structure includes a first buried electrode and a first insulator layer between the first buried electrode and a semiconductor mesa separating the first and second cell trench structures. A capping layer covers the first surface. The capping layer is patterned to form an opening having a minimum width larger than a thickness of the first insulator layer. The opening exposes a first vertical section of the first insulator layer at the first surface. An exposed portion of the first insulator layer is removed to form a recess between the semiconductor mesa and the first buried electrode. A contact structure is in the opening and the recess. The contact structure electrically connects both a buried zone in the semiconductor mesa and the first buried electrode and allows for narrower semiconductor mesa width.