SOI Contact Plug Width Variation for Fabrication Complexity
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Solution Overview
Problem
Current fabrication processes for semiconductor devices on silicon-on-insulator (SOI) substrates are complex and costly, particularly in forming contact plugs that connect active devices and backside contact plugs across the substrate, lacking a simple and cost-effective method.
Innovation Solution
A method involving a substrate with a first and second semiconductor layer, an insulating layer, and an interlayer dielectric (ILD) layer, where contact holes are formed using a mask layer and patterned resist to create first and second contact plugs with varying widths, allowing for the formation of conductive layers that connect active devices and the substrate, utilizing etching processes and chemical mechanical polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current fabrication processes are used to form contact plugs on SOI substrates, then electrical connectivity between active devices and substrate is achieved, but the fabrication process becomes complex and costly
Solution Approach 1:
The contact plug formation process is segmented into distinct stages: forming openings through the insulating layer, depositing conductive material, and creating varying width profiles. This segmentation allows each stage to be optimized independently, simplifying the overall complex fabrication process while ensuring reliable electrical connectivity.
Solution Approach 2:
The contact plugs are designed with varying width profiles where the width changes at different depths. The upper portion has a different width than the lower portion, allowing optimization of electrical connectivity at the substrate interface while maintaining proper alignment and isolation at upper levels. This local quality variation resolves the complexity issue by providing tailored geometry for specific functional requirements.
2Adaptability or versatility
If multiple different sizes of contact plugs are formed, then both active device connection and backside contact connection are achieved, but manufacturing complexity increases
Solution Approach 1:
A single fabrication process is designed that can produce contact plugs of varying widths and depths by adjusting process parameters such as etch depth, deposition thickness, and mask patterns. This universal process handles both active device contact plugs and backside contact plugs without requiring separate manufacturing lines, thereby maintaining ease of manufacture while achieving the needed adaptability in contact plug dimensions.
Solution Approach 2:
The manufacturing process utilizes parameter changes during fabrication - such as varying etch depth, conductive layer thickness, and pattern dimensions - to create contact plugs of different sizes from the same process flow. By changing parameters rather than creating entirely different processes, the patent maintains manufacturing simplicity while achieving the required versatility in contact plug configurations.
3Reliability
If contact plugs with varying widths are formed, then electrical connectivity and structural requirements are met, but additional fabrication steps are required
Solution Approach 1:
The varying width profile of contact plugs is established during the preliminary opening formation and conductive material deposition stages, rather than requiring additional shaping steps later. By performing the width variation action preliminarily during standard process steps, the patent achieves reliable electrical connectivity without sacrificing fabrication efficiency through extra dedicated steps.
Solution Approach 2:
The formation of varying width contact plugs is merged with standard fabrication steps such as opening formation, conductive layer deposition, and planarization. Rather than treating width variation as a separate operation, it is combined with existing process steps, thereby maintaining productivity while achieving the structural requirements for reliable electrical connectivity.
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 method simplifies the fabrication of semiconductor devices by enabling efficient formation of contact plugs with varying widths, reducing complexity and cost, while ensuring effective electrical connectivity between active devices and the substrate, enhancing the manufacturing process for SOI substrates.
Implementation Method 1
utilizing etching processes
Implementation Method 2
utilizing etching processes and chemical mechanical polishing
Data Source
AI summary
A semiconductor device includes: a substrate having a first semiconductor layer, an insulating layer, and a second semiconductor layer; an active device on the substrate; an interlayer dielectric (ILD) layer on the active device; a first contact plug adjacent to the active device; and a second contact plug in the ILD layer and electrically connected to the active device. Preferably, the first contact plug includes a first portion in the insulating layer and the second semiconductor layer and a second portion in the ILD layer, in which a width of the second portion is greater than a width of the first portion.