Backside Pick-Up Region Structure for Vertical DRAM Leakage Paths
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Solution Overview
Problem
Challenges exist in improving the quality, yield, performance, and reliability of dynamic random-access memory (DRAM) while reducing complexity, particularly in the design of vertical transistors for 4F2 DRAM cells.
Innovation Solution
A semiconductor device structure is designed with a substrate having a first and second surface, featuring an isolation structure with specific liner layers and a pick-up region on the substrate surface to provide a low-resistance path for drift currents, reducing electrical leakage from cosmic ray incidents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vertical transistor design is used for 4F2 DRAM cell, then device density and integration are improved, but electrical leakage and reliability issues worsen
Solution Approach 1:
The invention extracts and addresses the leakage problem by introducing a specific isolation structure with liner layers that separates and contains the leakage paths, allowing the vertical transistor design to maintain its high density while mitigating reliability issues through the dedicated isolation mechanism
Solution Approach 2:
The isolation structure with multiple liner layers acts as an intermediary element between the vertical transistor components, providing a controlled interface that prevents direct leakage paths while maintaining the compact vertical architecture needed for high device density
2Reliability
If isolation structure with multiple liner layers is implemented, then electrical leakage is reduced, but manufacturing complexity increases
Solution Approach 1:
The isolation structure is segmented into multiple functional liner layers, each with specific thickness and material properties, allowing the complex leakage prevention function to be divided into manageable segments that can be deposited and controlled independently through standard semiconductor fabrication processes
3Reliability
If upper portion thickness of second liner layer is increased, then drift current path is shortened, but manufacturing precision requirements increase
Solution Approach 1:
The invention optimizes the thickness parameter of the upper portion of the second liner layer to achieve the desired drift current path length, balancing the reliability improvement from shorter paths against the manufacturing precision requirements by selecting a thickness that is effective yet achievable with standard fabrication tolerances
Data Source
AI summary
A semiconductor device structure and method of manufacturing the same are provided. The semiconductor device structure includes a substrate, a first well region, a source/drain (S/D) feature, and a pick-up region. The substrate has a first surface and a second surface opposite to the first surface. The first well region abuts the second surface of the substrate and has a first conducive type. The S/D feature abuts the second surface of the substrate and has a second conductivity type different from the first conductivity type. The pick-up region abuts the first surface of the substrate and has the first conductivity type.