Co-fabricated Bulk and SOI Devices with Variable Dielectric Thickness
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Solution Overview
Problem
Co-fabricating bulk semiconductor and SOI devices poses challenges due to non-planar topography, which affects downstream processes and often requires an additional mask for contact formation.
Innovation Solution
A method is developed to form different dielectric thicknesses for co-fabricated bulk and SOI devices by providing a starting semiconductor structure with blanket dielectric and semiconductor layers, removing common portions to expose the substrate, forming isolation material in openings, and creating a thicker dielectric layer over the substrate, all without using a mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If co-fabrication of bulk and SOI devices is performed, then device integration is achieved, but non-planar topography is created affecting downstream processes
Solution Approach 1:
The substrate is divided into two distinct regions: a first region with SOI devices having a thin dielectric layer and a second region with bulk devices having a thick dielectric layer. This segmentation allows each region to be optimized independently while co-existing on the same substrate, resolving the topography conflict through spatial separation.
Solution Approach 2:
Different dielectric layer thicknesses are applied to different regions of the substrate based on local device requirements. The first region receives a thin dielectric layer suitable for SOI devices, while the second region receives a thick dielectric layer suitable for bulk devices, allowing each region to have the quality needed for its specific device type.
2Reliability
If non-planar topography is created, then device functionality is achieved, but additional masks are required for contact formation
Solution Approach 1:
The substrate is divided into two distinct regions: a first region with SOI devices having a thin dielectric layer and a second region with bulk devices having a thick dielectric layer. This segmentation allows each region to be optimized independently while co-existing on the same substrate, resolving the topography conflict through spatial separation.
Solution Approach 2:
The solution transitions from a single-planar surface to a multi-level structure by creating regions with different dielectric thicknesses. This dimensional variation allows different device types to coexist while maintaining planarity at each local region, eliminating the need for additional masks for contact formation.
3Manufacturing precision
If additional masks are used, then contact formation accuracy is improved, but manufacturing process complexity increases
Solution Approach 1:
The substrate is divided into two distinct regions: a first region with SOI devices having a thin dielectric layer and a second region with bulk devices having a thick dielectric layer. This segmentation allows each region to be optimized independently while co-existing on the same substrate, resolving the topography conflict through spatial separation.
Solution Approach 2:
A single masking process is designed to work for both SOI and bulk device regions simultaneously. The masking layer is configured to pattern contacts for both device types in one operation, making the process universal and eliminating the need for separate masking steps for different device regions.
Data Source
AI summary
Bulk semiconductor devices are co-fabricated on a bulk semiconductor substrate with SOI devices. The SOI initially covers the entire substrate and is then removed from the bulk device region. The bulk device region has a thicker dielectric on the substrate than the SOI region. The regions are separated by isolation material, and may or may not be co-planar.