Integrated Deep Shallow Trench Isolation Hard Mask Patterning
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Solution Overview
Problem
Existing methods for forming integrated deep and shallow trench isolation structures are not suitable for very deep trenches, as they require limiting the number or depth of deep trenches to avoid insufficient resist filling, which restricts the isolation capabilities needed for high-performance semiconductor applications.
Innovation Solution
A method involving a hard mask is used to form deep and shallow trenches simultaneously, where the hard mask is imprinted with specific patterns to define trench openings, allowing for flexible layout and simultaneous filling and planarization of both trench types without the need for extra resist, enabling deeper trenches without insufficient filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deep trenches are formed first and filled with resist plug before shallow trenches are patterned, then isolation characteristics are improved, but the number or depth of deep trenches must be limited to avoid insufficient resist filling
Solution Approach 1:
A hard mask layer is deposited and patterned before trench formation to predefine both deep and shallow trench locations. This preliminary patterning step ensures that subsequent etching and filling operations can proceed without resist filling constraints, as the hard mask provides a stable structural framework throughout the process sequence.
Solution Approach 2:
The trench formation process is segmented into distinct deep trench and shallow trench etching steps, each controlled by the pre-patterned hard mask. This segmentation allows independent optimization of each trench type's depth and filling without the constraints of sequential resist-based methods.
2Ease of manufacture
If shallow trench isolation is used, then manufacturing is simplified, but parasitic capacitance suppression is insufficient for high performance bipolar applications
Solution Approach 1:
The method merges deep trench isolation and shallow trench isolation into a single integrated structure. The hard mask is patterned to define both deep and shallow trench regions simultaneously, and both trench types are formed and filled in an integrated sequence, combining the superior parasitic capacitance suppression of deep trenches with the manufacturing simplicity of shallow trench processes.
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 allows for effective isolation of deep and shallow trenches, enhancing parasitic capacitance suppression and providing flexibility in trench layout, enabling both deep and shallow trench integration within the same device layouts, thus improving semiconductor device performance.
Implementation Method 1
depositing a hard mask on a multilayer structure
Implementation Method 2
etching into the film stack the first trench to a first depth and the second trench to a second depth
Data Source
AI summary
A method of forming an integrated deep and shallow trench isolation structure comprises depositing a hard mask on a film stack having a plurality of layers formed on a substrate such that the hard mask is deposited on a furthermost layer from the substrate, imprinting a first pattern into the hard mask to define an open end of a first trench, imprinting a second pattern into the hard mask to define an open end of a second trench, and etching into the film stack the first trench to a first depth and the second trench to a second depth such that the first trench and the second trench each define a blind aperture in the surface of the film stack.