Self-Aligned Backside Etching for Dense Semiconductor Contacts
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Solution Overview
Problem
As semiconductor devices undergo miniaturization, existing etching processes face challenges in achieving precise control and increased density, leading to issues with parasitic capacitance and device performance.
Innovation Solution
The implementation of self-aligned backside etching and trimming processes using spacers formed along semiconductor fins as masks, which allows for more accurate etching of gate structures and epitaxial source/drain regions, accompanied by the use of low-k dielectric materials and air gaps to reduce parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used for gate structures and epitaxial source/drain regions, then manufacturing simplicity is maintained, but etching precision and device integration density deteriorate
Solution Approach 1:
The patent applies preliminary action by forming spacer structures on the sidewalls of fins before the etching process. These spacers serve as pre-positioned masks that define the etch boundaries, enabling precise etching of gate structures and epitaxial source/drain regions. The spacers are formed in advance and remain in place during subsequent etching steps, ensuring accurate pattern transfer without requiring complex real-time control.
Solution Approach 2:
The patent uses spacer structures as intermediary elements between the fin structures and the etching process. These spacers act as mediating masks that translate the fin geometry into precise etch patterns for gate and source/drain regions. The intermediaries enable complex patterning by serving as temporary reference structures that guide the etching process.
2Area of moving object
If feature sizes are reduced to increase integration density, then device capacity increases, but etching accuracy and device performance deteriorate
Solution Approach 1:
The spacer structures are formed in advance with precise dimensions that define the target feature sizes. By pre-forming these spacers with controlled thickness and position, the patent establishes accurate etch boundaries before the actual etching occurs. This preliminary definition of dimensions enables consistent small feature sizes while maintaining etching accuracy through the self-aligned nature of the process.
Solution Approach 2:
The spacer structures serve as self-aligned masks that automatically define the etch patterns based on their own geometry. The spacers' positions and dimensions directly determine the gate and source/drain region boundaries without requiring additional alignment steps or external reference structures. This self-service mechanism ensures high precision even at reduced feature sizes.
Data Source
AI summary
Methods of performing backside etching processes on source/drain regions and gate structures of semiconductor devices and semiconductor devices formed by the same are disclosed. In an embodiment, a semiconductor device includes a first transistor structure; a first interconnect structure on a front-side of the first transistor structure; and a second interconnect structure on a backside of the first transistor structure, the second interconnect structure including a first dielectric layer on the backside of the first transistor structure; a contact extending through the first dielectric layer to a source/drain region of the first transistor structure; and first spacers along sidewalls of the contact between the contact and the first dielectric layer, sidewalls of the first spacers facing the first dielectric layer being aligned with sidewalls of the source/drain region of the first transistor structure.