Stacked Semiconductor Structure With Dummy Channel Leakage Barrier
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Solution Overview
Problem
The formation of stacked semiconductor devices with complex structures and high-aspect ratios leads to challenges such as current leakage from the source/drain regions into the substrate, adversely affecting device performance.
Innovation Solution
The use of a dummy channel stack and a barrier layer to prevent or reduce current leakage by aligning the source/drain regions and ensuring coplanarity, thereby avoiding substrate patterning and enhancing device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If substrate patterning is performed to form source/drain regions in stacked semiconductor devices, then device density and integration are improved, but current leakage into the substrate occurs due to misalignment and non-coplanarity
Solution Approach 1:
A dummy channel stack is formed in advance on the substrate before the actual channel stack is created. This preliminary structure serves as a template that guides subsequent patterning steps, ensuring that source/drain regions are correctly aligned with the channel stack. The dummy channel stack is later removed after serving its alignment purpose, having already prevented current leakage issues.
Solution Approach 2:
The dummy channel stack acts as an intermediary element between the substrate and the final device structure. It mediates the alignment process by providing a physical reference structure that ensures source/drain regions will be properly positioned and coplanar with the channel stack, thereby preventing current leakage without requiring direct patterning of the substrate at this stage.
2Object-affected harmful factors
If complex patterning steps are used to ensure source/drain alignment, then current leakage is reduced, but manufacturing complexity and process steps increase
Solution Approach 1:
Instead of directly patterning the substrate with complex steps, a simplified copy or replica (the dummy channel stack) is created first. This copy contains the necessary alignment information and can be formed using simpler processes. The dummy channel stack is then used as a mask or template to transfer the pattern to the actual channel stack, reducing the complexity of subsequent steps while maintaining alignment precision.
3Ease of manufacture
If source/drain regions are formed without dummy channel stack, then manufacturing steps are reduced, but misalignment causes current leakage into substrate
Solution Approach 1:
The dummy channel stack is formed as a preliminary structure before the actual device fabrication. This preliminary action establishes the correct geometric reference for source/drain region formation, ensuring proper alignment and coplanarity. The simplicity of forming this temporary guide structure outweighs the added manufacturing steps, as it prevents reliability issues from misalignment.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
Provided is a stacked semiconductor device which includes: a substrate; a 1st source/drain region on the substrate; and a 2nd source/drain region vertically above the 1st source/drain region, the 2nd source/drain region vertically overlapping a 1st portion, among the 1st portion and a 2nd portion, of the 1st source/drain region, wherein a 1st portion of a top surface of the substrate vertically below the 1st portion of the 1st source/drain region and a 2nd portion of the top surface of the substrate vertically below the 2nd portion of the 1st source/drain region are coplanar or aligned.