Multi-Stack Nanosheet Transistor Isolation With Dam Structures
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Solution Overview
Problem
The existing manufacturing process for high-density transistors is not suitable for nanosheet transistors, leading to potential electrical short circuits between multi-stack transistor structures.
Innovation Solution
A dam structure is formed between adjacent rows and columns of multi-stack transistor structures during manufacturing to electrically isolate them, preventing short circuits by controlling the spread of etchants and ensuring proper contact formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the existing manufacturing process for high-density transistors is used, then device density is improved, but electrical short circuits occur between multi-stack transistor structures
Solution Approach 1:
The patent divides the continuous array of multi-stack transistor structures into isolated units by forming dam structures between adjacent stacks. This segmentation prevents electrical short circuits while maintaining high device density by allowing close proximity arrangement of individual transistor stacks.
Solution Approach 2:
The dam structure acts as an intermediary element positioned between adjacent multi-stack transistor structures. This intermediate feature provides electrical isolation and prevents harmful electrical interactions while enabling the dense packing of transistor stacks that would otherwise be impossible.
2Reliability
If dam structures are formed to isolate multi-stack transistor structures, then electrical short circuit prevention is improved, but manufacturing process complexity increases
Solution Approach 1:
The dam structures are formed at an early stage in the manufacturing process, before subsequent processing steps. This preliminary action simplifies the overall manufacturing complexity by establishing the isolation framework early, allowing later steps to proceed without additional isolation concerns.
Solution Approach 2:
The dam structure serves multiple functions: it provides electrical isolation between transistor stacks, defines the boundaries for source/drain region formation, and serves as a reference for subsequent patterning steps. This multi-functionality reduces the need for separate structures for each function, thereby simplifying the overall manufacturing process.
3Manufacturing precision
If dam structures are formed early in manufacturing, then contact formation precision is improved, but device density may be reduced
Solution Approach 1:
The dam structures are positioned with precise local spacing to provide just enough isolation while maximizing the remaining space for transistor stacks. This local optimization of spacing allows contact formation precision to be improved without significantly compromising overall device density.
Data Source
AI summary
An array of multi-stack transistor structures is provided, wherein the multi-stack transistor structures are arranged in a plurality of rows and a plurality of columns in the array, wherein each of the multi-stack transistor structures includes two or more vertically arranged transistor stacks, and wherein a dam structure is formed between adjacent two rows in a same column so that a multi-stack transistor structure in one of the adjacent two rows is electrically isolated from a multi-stack transistor structure in the other of the adjacent two rows in the same column.