Alignment Layer Mask Pits for Self-Aligned Gate Trench Formation
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Solution Overview
Problem
Current semiconductor devices face challenges in improving device characteristics, particularly in the alignment and formation of gate structures relative to field electrode structures, which affects the efficiency and yield of semiconductor manufacturing processes.
Innovation Solution
A method involving the formation of first trenches and an alignment layer with mask pits, where the sidewalls of the mask pits have a smaller tilt angle than the trenches, allowing for self-aligned gate trench formation using an auxiliary material as an etch mask, thereby reducing alignment tolerances and saving on photolithography processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography alignment methods are used, then manufacturing precision can be maintained, but device complexity and manufacturing time increase due to multiple alignment steps
Solution Approach 1:
The alignment layer with mask pits automatically defines the position of field electrode structures and gate structures through self-aligned formation. The mask pits serve as physical references that guide subsequent etching steps, eliminating the need for external photolithography masks and multiple alignment operations. This self-service mechanism achieves high alignment precision while simplifying the manufacturing process.
Solution Approach 2:
The alignment layer with mask pits is formed in advance before the field electrode structures and gate structures. This preliminary action establishes the geometric framework that determines the positions of subsequent structures, enabling self-aligned fabrication without requiring precise mask alignment during later processing steps.
2Manufacturing precision
If smaller tilt angle mask pits are used, then alignment precision improves, but manufacturing complexity increases
Solution Approach 1:
The tilt angle of mask pit sidewalls is optimized to be smaller than that of first trenches, creating a geometric relationship that naturally defines alignment references. This parameter change in the alignment layer structure enables high alignment precision while the mask pits can be formed using standard etching processes, maintaining ease of manufacture.
3Manufacturing precision
If auxiliary material is deposited in mask pits, then etch mask functionality is achieved, but manufacturing time increases
Solution Approach 1:
The deposition of auxiliary material in mask pits combines multiple functions: it creates the etch mask for gate trenches, defines the position of field electrode structures, and establishes alignment references for subsequent steps. This merging of functions achieves high gate structure alignment precision while consolidating multiple process steps into a single integrated operation.
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 the formation of semiconductor devices with improved alignment and reduced mesa width between field electrode structures, enhancing the trade-off between breakdown performance and on-state resistance, and eliminating the need for precise mask alignment, thus improving manufacturing efficiency and device performance.
Implementation Method 1
A gate trench for a gate structure is formed in a mesa section between the first trenches, wherein the auxiliary material is used as an etch mask
Data Source
AI summary
A semiconductor device includes a gate structure extending from a first surface of a semiconductor portion into a mesa section between neighboring field electrode structures and an alignment layer formed on the first surface. The alignment layer includes mask pits formed in the alignment layer in a vertical projection of the field electrode structures. Sidewalls of the mask pits have a smaller tilt angle with respect to the first surface than sidewalls of the field electrode structures. The gate structure is in the vertical projection of a gap between neighboring mask pits.