Epitaxy Blocker Alignment Features for Semiconductor Lithography
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Solution Overview
Problem
Existing semiconductor device formation techniques face challenges in aligning structured regions within regrown epitaxial layers, as the epitaxially regrown layer covers and obscures alignment features, making it difficult for processing equipment to distinguish them.
Innovation Solution
The formation of alignment features with vertically offset lateral surfaces and epitaxy blockers on their sidewalls prevents the regrowth of the epitaxial layer on these features, maintaining their visibility and integrity even after epitaxial regrowth, allowing for accurate positioning of masks and features on the regrown layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxial regrowth technique is used to improve electrical characteristics, then HEMT on-resistance is reduced, but alignment features become obscured and difficult to distinguish
Solution Approach 1:
The alignment feature structure is segmented into multiple components: a base alignment feature and an epitaxy blocker component. This segmentation allows the alignment feature to serve dual purposes - maintaining visibility for alignment while preventing unwanted epitaxial regrowth on its sidewalls.
Solution Approach 2:
The epitaxy blocker acts as an intermediary material deposited on the sidewalls of alignment features. This intermediary layer prevents direct contact between the regrowing epitaxial layer and the alignment feature sidewalls, thereby maintaining alignment feature distinguishability while allowing beneficial epitaxial regrowth elsewhere.
2Manufacturing precision
If epitaxial regrowth is performed to improve device performance, then manufacturing precision is improved, but alignment features are covered and become indistinguishable
Solution Approach 1:
The epitaxy blocker is deposited on the alignment feature sidewalls before the epitaxial regrowth process begins. This preliminary action ensures that when regrowth occurs, the alignment features remain visible and distinguishable, while still benefiting from the precision improvements of epitaxial regrowth.
Solution Approach 2:
The epitaxy blocker is applied locally only to the sidewalls of alignment features, not to the entire substrate. This local application maintains alignment feature visibility where needed while allowing epitaxial regrowth to proceed normally in other regions for improved device performance.
3Measurement precision
If alignment features are used for mask positioning, then positioning accuracy is improved, but the features are covered by regrown epitaxial layer
Solution Approach 1:
The functionality of preventing epitaxial regrowth is extracted from the alignment feature itself and implemented as a separate epitaxy blocker component on the sidewalls. This extraction allows the alignment feature to maintain its primary function of providing visible positioning references without being obscured by regrown material.
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 method ensures that alignment features remain clearly defined and recognizable, enabling precise alignment and positioning of masks and structures on the regrown epitaxial layer, improving the accuracy and reliability of semiconductor device formation.
Implementation Method 1
forming an epitaxy blocker on the first and second vertical sidewalls of each alignment feature. The epitaxy blocker prevents the type III-V semiconductor regrown layer from forming on the first and second vertical sidewalls of the one or more alignment features
Implementation Method 2
These alignment features provide a reference point from which to ensure that different masks are centered with respect to one another
Data Source
AI summary
A type III-V semiconductor substrate is provided. Semiconductor material is removed from the type III-V semiconductor substrate such that the type III-V semiconductor substrate comprises one or more alignment features extending away from a main lateral surface. Each of the alignment features includes a first lateral surface that is vertically offset from the main lateral surface, and first and second vertical sidewalls that extend between the first lateral surface and the main lateral surface. An epitaxy blocker is formed on the first and second vertical sidewalls of each alignment feature. A type III-V semiconductor regrown layer is epitaxially grown on a portion of the semiconductor wafer that includes the one or more alignment features. The epitaxy blocker prevents the type III-V semiconductor regrown layer from forming on the first and second vertical sidewalls of the one or more alignment features.