Backside Power Rail Interconnect Using a SiGe Etch Stop
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Solution Overview
Problem
The formation of interconnect structures in semiconductor devices without an etch stop, such as silicon on insulator (SOI), introduces inefficiencies including increased manufacturing costs, yield losses, and misalignment issues, which can lead to reduced signaling speed performance.
Innovation Solution
Using a layer of silicon germanium as an etch stop to form the first portion of the interconnect structure, followed by removing it to form the second portion, which improves alignment and contact with the backside power rail structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an etch stop layer is not used in forming interconnect structures, then manufacturing process is simpler, but misalignment and yield losses increase
Solution Approach 1:
The patent introduces an etch stop layer as an intermediary element between the interconnect structure and the substrate. This layer serves as a reference plane that enables precise alignment during the etching process, thereby improving manufacturing precision without significantly complicating the overall manufacturing process
Solution Approach 2:
The etch stop layer is formed in advance before the interconnect structure etching process. This preliminary action establishes a stable reference surface that guides subsequent alignment and etching operations, preventing misalignment issues before they occur
2Ease of manufacture
If an etch stop layer is not used, then manufacturing cost is reduced, but yield losses increase
Solution Approach 1:
The etch stop layer acts as a protective intermediary that prevents damage to underlying structures during etching operations. By providing a controlled etching interface, it reduces defect formation and improves manufacturing yield, with the added cost offset by reduced waste and rework
Solution Approach 2:
The etch stop layer is designed as a sacrificial element that is removed after serving its alignment and protection function. This temporary structure enables improved yield during critical manufacturing steps, with the material cost being a small fraction of the value of prevented yield losses
3Device complexity
If an etch stop layer is not used, then device structure is simpler, but signaling speed performance decreases
Solution Approach 1:
The etch stop layer serves as an intermediary that enables precise formation of interconnect structures with optimal electrical characteristics. By ensuring accurate alignment and clean interfaces, it improves signal transmission quality and speed, with the additional layer being minimal in thickness and impact on overall 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
This approach enhances manufacturing efficiency and increases the likelihood of electrical contact, thereby improving the performance of semiconductor devices by reducing misalignment and yield losses.
Implementation Method 1
a first portion of the interconnect structure is formed using a layer of silicon germanium as an etch stop
Data Source
AI summary
Some implementations described herein provide a semiconductor device and methods of formation. The semiconductor device includes a transistor structure that is electrically connected to a metal layer. Described techniques include forming an interconnect structure that electrically connects the metal layer to a backside power rail structure. The techniques include forming a first portion of the interconnect structure using a layer of silicon germanium as an etch stop and, after removal of the layer of the silicon germanium, forming a second portion of the interconnect structure.