Semiconductor Alignment Mark Formation via Segmented Epitaxy
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Solution Overview
Problem
Current semiconductor device fabrication processes face inefficiencies in forming alignment marks during multistep epitaxial processes, particularly in reproducing trench structures across multiple epitaxial layers, which affects alignment precision and layer formation.
Innovation Solution
A method involving the formation of trench structures with varying widths and depths in different sections of a semiconductor body, where a first epitaxial layer completely fills narrower trenches and a second epitaxial layer reproduces the wider trenches as alignment marks, ensuring precise alignment and layer growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single epitaxial growth process is used to form semiconductor layers, then the process is simple and fast, but it cannot form both planar surfaces and residual trench structures for alignment marks
Solution Approach 1:
The single epitaxial growth process is segmented into two separate growth processes. The first growth process forms the first epitaxial layer with controlled thickness to fill narrower trenches while leaving wider trenches partially filled. The second growth process forms the second epitaxial layer that completely fills the remaining trench space. This segmentation allows each growth process to be optimized for its specific purpose, achieving both efficiency and precision.
Solution Approach 2:
The first epitaxial layer is formed as a preliminary structure before the second epitaxial layer. The first growth process preliminarily fills the trenches to a controlled level, creating a foundation that enables the second growth process to form the alignment marks. This preliminary action allows the system to achieve the final precision goal through a staged approach.
2Manufacturing precision
If wider trenches are formed in the second section to create alignment marks, then alignment precision is improved, but the epitaxial layer cannot maintain a planar surface in the first section
Solution Approach 1:
Different trench width specifications are applied to different sections of the semiconductor body. The first section contains narrower trenches that are completely filled by the first epitaxial layer, maintaining a planar surface. The second section contains wider trenches that are partially filled, creating residual trench structures for alignment marks. This local differentiation allows each section to serve its specific function while maintaining overall system integrity.
Solution Approach 2:
The first epitaxial layer is grown to a thickness that is sufficient to completely fill the narrower trenches in the first section but insufficient to completely fill the wider trenches in the second section. This partial filling action intentionally leaves residual trench structures in the second section, which serve as alignment marks, while maintaining planarity in the first section.
3Shape
If the first epitaxial layer completely fills all trenches, then surface planarity is achieved, but alignment marks cannot be formed
Solution Approach 1:
The trench structures are designed with different local qualities - narrower trenches in the first section and wider trenches in the second section. This local differentiation ensures that when the first epitaxial layer is grown to a specific thickness, it completely fills the narrower trenches (achieving planarity) while leaving the wider trenches partially filled (creating alignment marks).
Solution Approach 2:
The first epitaxial layer growth is controlled to perform a partial action - it completely fills some trenches (those in the first section) but intentionally leaves other trenches (those in the second section) partially filled. This controlled partial filling creates the residual trench structures that serve as alignment marks, solving the contradiction between planarity and alignment mark formation.
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 enables efficient multistep epitaxial processes by maintaining alignment accuracy and allowing for the formation of thick, planar epitaxial layers with residual trenches that serve as effective alignment marks, enhancing the precision and reliability of semiconductor device fabrication.
Implementation Method 1
forming a first epitaxial layer in a first epitaxial growth process
Implementation Method 2
forming a second epitaxial layer on top of the first epitaxial layer in a second epitaxial growth process
Data Source
AI summary
Disclosed is a method. The method includes forming a trench structure with at least one first trench in a first section of a semiconductor body; forming a second trench that is wider than the first trench in a second section of the semiconductor body; and forming a semiconductor layer on a surface of the semiconductor body in the first section and the second section and in the at least one first trench and the second trench such that the semiconductor layer has a substantially planar surface above the first section and a residual trench remains above the second section. Forming the semiconductor layer includes forming a first epitaxial layer in a first epitaxial growth process and a second epitaxial layer on top of the first epitaxial layer in a second epitaxial growth process.