Tilted Plasma Etching Overlay Correction With Wafer Rotation
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Solution Overview
Problem
The challenge in integrated circuit (IC) manufacturing is the non-uniform etch rates during plasma etching, leading to overlay measurement errors between circuit patterns of different layers, which affect the precision and alignment of the etched structures.
Innovation Solution
The implementation of tilted angle plasma etching, controlled by adjusting the flow rate of etching gases and applying electric or magnetic fields to induce a plasma beam angle, along with a rotating stage to compensate for non-uniform etch rates, ensuring uniform etching across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching is performed with a plasma beam, then the geometric shapes are produced on the substrate, but the etch rates are non-uniform across the substrate
Solution Approach 1:
The substrate is rotated during plasma etching to dynamically change the relative position between the plasma beam and different regions of the substrate. This rotation ensures that all areas receive relatively uniform plasma exposure over time, compensating for the inherently non-uniform plasma distribution and achieving uniform etch rates across the entire substrate surface.
2Manufacturing precision
If tilted angle plasma etching is used to fine-tune the shapes, then the alignment precision is improved, but the overlay measurement errors increase due to non-uniform etch rates
Solution Approach 1:
Rotating the substrate during tilted angle plasma etching ensures uniform plasma distribution across all regions, eliminating the non-uniform etch rates that cause overlay measurement errors. This dynamic approach maintains the alignment precision benefits of tilted angle etching while achieving uniform etching throughout the substrate.
3Manufacturing precision
If the plasma beam is applied at a tilted angle, then the etching locations are controlled for exact shapes, but the etch rate becomes non-uniform across different locations
Solution Approach 1:
The substrate rotation dynamically redistributes the plasma beam exposure across different locations during tilted angle etching. This ensures that while the tilted angle provides precise location control for shape formation, the rotation compensates for location-specific etch rate variations, achieving uniform etching across the entire substrate.
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 reduces overlay measurement errors by maintaining consistent etch rates and alignment accuracy between circuit patterns, enhancing the precision of IC fabrication.
Implementation Method 1
The geometric shapes may be produced by plasma etching, e.g., by plasma etching with a plasma beam, of a top layer on the substrate
Implementation Method 2
applying electric or magnetic fields to induce a plasma beam angle
Implementation Method 3
applying electric or magnetic fields to induce a plasma beam angle
Data Source
AI summary
In a method of patterning an integrated circuit, test layer thickness variation data is received when a test layer with a known thickness disposed over a test substrate undergoes tilted angle plasma etching. Overlay offset data per substrate locations caused by the tilted angle plasma etching is determined. The overlay offset data is determined based on the received thickness variation data. The overlay offset data is associated with an overlay between first circuit patterns of a first layer on the semiconductor substrate and corresponding second circuit patterns of a second layer disposed over the first layer on the substrate. A location of the substrate is adjusted based on the overlay offset data during a lithography operation to pattern a resist layer over the second layer. The second layer is patterned based on the projected layout patterns of the reticle and using the tilted angle plasma etching.