VFET Self-Aligned Contacts via Dummy Channel Region
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Solution Overview
Problem
The formation of self-aligned contacts in vertical field-effect transistor (VFET) devices is challenging due to the presence of rounded corners in active regions, which increases contact resistance and reduces the effectiveness of source/drain contacts.
Innovation Solution
A method involving the formation of a dummy channel region adjacent to the corners of the active region, followed by the creation of spacers and the conversion or removal of the dummy channel region to form self-aligned bottom source/drain contacts, ensuring consistent contact alignment and reduced contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dummy channel region is formed before the active region, then the corners of the active region have consistent shapes, but the manufacturing process complexity increases
Solution Approach 1:
The dummy channel region is formed in advance before the active region patterning step. This preliminary structure serves as a template that ensures all corners of the active region will have identical shapes after the subsequent patterning process, eliminating corner shape inconsistencies without requiring complex post-processing adjustments.
2Manufacturing precision
If spacers are formed on the dummy channel region, then self-aligned bottom source/drain contacts are achieved, but the device structure complexity increases
Solution Approach 1:
The spacers are formed on the dummy channel region to automatically define the position of the bottom source/drain contacts. The dummy channel region itself serves as the alignment reference, and the spacers self-align to its sides, creating precisely positioned contacts without requiring additional alignment steps or complex masking processes.
3Reliability
If the dummy channel region is removed or converted to form bottom source/drain contacts, then contact resistance is reduced, but material loss occurs
Solution Approach 1:
The dummy channel region, which was initially formed as a temporary structure for alignment purposes, is subsequently removed or converted into the bottom source/drain contact material. This approach eliminates the need to discard the dummy structure entirely - instead, it is transformed into a functional component, reducing material waste while achieving low-resistance contacts.
Data Source
AI summary
Integrated circuit devices and methods of forming the same are provided. The methods may include forming a dummy channel region and an active region of a substrate, forming a bottom source/drain region on the active region, forming a gate electrode on one of opposing side surfaces of the dummy channel region, and forming first and second spacers on the opposing side surfaces of the dummy channel region, respectively. The gate electrode may include a first portion on the one of the opposing side surfaces of the dummy channel region and a second portion between the bottom source/drain region and the first spacer. The methods may also include forming a bottom source/drain contact by replacing the first portion of the gate electrode with a conductive material. The bottom source/drain contact may electrically connect the second portion of the gate electrode to the bottom source/drain region.