Rectangular Spacer Formation via Selective Etching
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Solution Overview
Problem
Existing spacer technologies in integrated circuit manufacturing often result in spacers with non-uniform profiles, leading to curved sidewalls and varying widths, which can affect the precision and reliability of transistor formation and metal connections.
Innovation Solution
A method involving the formation of a conformal spacer layer with a protection layer, where the horizontal portions of the protection layer are selectively etched, allowing for the preservation of vertical spacer portions, resulting in spacers with a rectangular profile and uniform width, achieved through specific etching processes and gas selections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional spacer formation methods are used, then the manufacturing process is simple, but the spacer profile becomes non-uniform with curved sidewalls and varying widths
Solution Approach 1:
The spacer formation process is segmented into multiple distinct steps: forming a conformal spacer layer, depositing a protection layer, selectively removing horizontal portions of the protection layer, and selectively etching horizontal portions of the spacer layer. This segmentation allows each step to be optimized independently, achieving uniform rectangular profiles while maintaining process control.
Solution Approach 2:
The protection layer is deposited on the spacer layer before any etching occurs, serving as a preliminary protective measure. This preliminary action enables selective removal of only the desired horizontal portions while preserving the vertical portions, ensuring uniform spacer profiles before the actual spacer etching takes place.
2Length of moving object
If spacer width is reduced below photolithography limits, then pitch size is reduced, but maintaining uniform width becomes difficult with conventional methods
Solution Approach 1:
The patent replaces photolithography-based patterning with a deposition and selective etching approach. By forming spacers through conformal deposition followed by selective removal of horizontal portions, the method achieves sub-photolithography pitch sizes with superior width uniformity, bypassing the resolution limits of optical systems.
Solution Approach 2:
The patent changes the fundamental parameters of spacer formation from lithography-defined patterns to deposition thickness-controlled dimensions. By controlling the conformal deposition thickness and the selective etching parameters, uniform spacer widths at reduced pitch sizes are achieved, transitioning from optical parameter control to material deposition parameter control.
3Manufacturing precision
If selective etching of horizontal portions is performed, then vertical profiles with uniform width are achieved, but additional process steps are required
Solution Approach 1:
The protection layer serves a dual function: it protects the vertical portions of the spacer during etching while also defining the horizontal portions to be removed. This self-service approach, where the protection layer simultaneously provides protection and patterning information, reduces the need for additional separate patterning steps, improving manufacturing efficiency despite the added deposition step.
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 approach ensures spacers with vertical profiles and uniform widths, enhancing the precision of transistor formation and reducing pitch sizes below photolithography limits, thereby improving the reliability and uniformity of integrated circuit structures.
Implementation Method 1
the horizontal portions of the protection layer are selectively etched, allowing for the preservation of vertical spacer portions
Data Source
AI summary
A method includes forming a spacer layer on a top surface and sidewalls of a patterned feature, wherein the patterned feature is overlying a base layer. A protection layer is formed to contact a top surface and a sidewall surface of the spacer layer. The horizontal portions of the protection layer are removed, wherein vertical portions of the protect layer remain after the removal. The spacer layer is etched to remove horizontal portions of the spacer layer, wherein vertical portions of the spacer layer remain to form parts of spacers.