Semiconductor Interconnect Patterning with Spacers and Line Cuts
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Solution Overview
Problem
As semiconductor devices continue to shrink, traditional photolithography equipment struggles to achieve the desired pitch and accuracy for manufacturing, leading to manufacturing challenges and increased costs due to difficulties in aligning etch masks and maintaining precise patterns.
Innovation Solution
A patterning process involving the use of spacers and a sacrificial material to pattern an underlying mask layer, which is then used to pattern a target layer in a single step, allowing for the formation of fine pitch interconnect lines with line cuts, reducing manufacturing complexity and increasing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional photolithography equipment is used, then manufacturing process is simpler, but manufacturing precision deteriorates due to inability to achieve desired pitch and alignment accuracy
Solution Approach 1:
The patterning process is divided into multiple stages: forming mandrels, depositing spacers, removing mandrels, and forming sacrificial material. Each stage achieves a specific function, collectively enabling fine pitch patterning that exceeds traditional photolithography capabilities while maintaining process manageability through modular steps
Solution Approach 2:
Spacer material and sacrificial material are introduced as intermediary elements. The spacers serve as temporary structures that define the final pattern geometry, while the sacrificial material is used to create line cuts. These intermediaries enable precise pattern transfer without requiring direct photolithography at the target pitch scale
2Manufacturing precision
If multiple patterning steps are used to achieve fine pitch, then manufacturing precision improves, but manufacturing time and complexity increase
Solution Approach 1:
The spacer structures are formed in advance with precise dimensions through conformal deposition. This preliminary structuring establishes the final pattern geometry before etching, eliminating the need for multiple alignment steps and reducing overall manufacturing cycle time while maintaining high precision
Solution Approach 2:
Multiple functions are combined into single process steps where possible. For example, the spacer formation simultaneously defines feature pitch and serves as an etch mask. The sacrificial material formation combines line cut definition with pattern transfer, reducing the number of separate processing steps required
3Length of moving object
If photolithography is pushed to theoretical limits, then pitch reduction is achieved, but reliability deteriorates due to process window narrowing
Solution Approach 1:
The patent replaces optical lithography with a deposition-based self-aligned patterning approach. Conformal spacer deposition and anisotropic etching create patterns with dimensions determined by film thickness and etch selectivity rather than optical resolution, achieving smaller features with larger process windows and improved robustness
Solution Approach 2:
The patterning mechanism transitions from optical parameter control (wavelength, numerical aperture) to material parameter control (film thickness, deposition conformality, etch selectivity). This parameter transformation enables precise feature size control through physical dimensions of deposited layers rather than optical diffraction limits, improving process reliability
Data Source
AI summary
Semiconductor devices and methods of forming semiconductor devices are provided. A method includes forming a first mask layer over a target layer, forming a plurality of spacers over the first mask layer, and forming a second mask layer over the plurality of spacers and patterning the second mask layer to form a first opening, where in a plan view a major axis of the opening extends in a direction that is perpendicular to a major axis of a spacer of the plurality of spacers. The method also includes depositing a sacrificial material in the opening, patterning the sacrificial material, etching the first mask layer using the plurality of spacers and the patterned sacrificial material, etching the target layer using the etched first mask layer to form second openings in the target layer, and filling the second openings in the target layer with a conductive material.