Reverse Mask Patterning for Uniform Trench Recess Depths
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Solution Overview
Problem
Existing methods for forming trench structures in semiconductor devices often result in non-uniform recess depths, leading to unpredictable device performance and potential failures due to variations in the thickness of photosensitive material, which complicates the formation of uniform dimensions across a workpiece.
Innovation Solution
A method involving the use of a reverse mask to pattern the photosensitive material, allowing for improved control over recess depth by etching away the material uniformly across trenches, independent of initial thickness variations, ensuring consistent dimensions and reducing the need for additional lithography steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography methods are used to pattern photosensitive material, then the process is simple and direct, but the recess depth becomes non-uniform due to variations in resist thickness
Solution Approach 1:
The patent applies inversion by using a reverse mask that has the opposite pattern of the desired trench structure. Instead of directly patterning the photosensitive material to create trenches, the reverse mask prevents etching in areas where material should remain, thereby creating the trench pattern through negative space. This eliminates dependence on resist thickness variations and achieves uniform recess depths.
Solution Approach 2:
The reverse mask serves as an intermediary element between the lithography process and the final trench structure. Rather than directly transferring the trench pattern through conventional photolithography, the reverse mask mediates the process by defining areas to be protected from etching, thus indirectly creating the desired trench pattern with improved uniformity.
2Manufacturing precision
If additional lithography steps are added to achieve uniform recess depths, then manufacturing precision improves, but productivity decreases
Solution Approach 1:
The patent merges the masking function with the etch protection function into a single reverse mask layer. By combining these functions, the process achieves uniform recess depths without requiring multiple separate lithography and etching steps, thereby maintaining productivity while improving precision.
Solution Approach 2:
The reverse mask performs multiple functions simultaneously: it defines the trench pattern, protects underlying structures from etching, and ensures uniform recess depths across the substrate. This multi-functionality eliminates the need for additional specialized steps, maintaining high fabrication throughput.
3Reliability
If conventional direct patterning is used, then the process is straightforward, but device reliability decreases due to unpredictable performance from non-uniform trenches
Solution Approach 1:
By inverting the patterning approach using a reverse mask, the method achieves uniform trench depths that ensure predictable device performance. The inversion strategy transforms a simple but unreliable direct patterning process into a more robust method where the reverse mask geometry directly controls the final trench uniformity, improving reliability.
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 achieves uniform recess depths in trench structures, enhancing the predictability and performance of semiconductor devices by eliminating the dependence on resist-thickness variations, thereby preventing device failures and optimizing usable surface area.
Implementation Method 1
removing the layer of photosensitive material from over the workpiece
Implementation Method 2
removing the layer of photosensitive material from over the workpiece
Data Source
AI summary
Methods of fabricating semiconductor devices and structures thereof are disclosed. In a preferred embodiment, a method of fabricating a semiconductor device includes providing a workpiece having a plurality of trenches formed therein, forming a liner over the workpiece, and forming a layer of photosensitive material over the liner. The layer of photosensitive material is removed from over the workpiece except from over at least a portion of each of the plurality of trenches. The layer of photosensitive material is partially removed from over the workpiece, leaving a portion of the layer of photosensitive material remaining within a lower portion of the plurality of trenches over the liner.