Reverse Tone STI Formation for Uniform Semiconductor Active Regions
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Solution Overview
Problem
Existing STI formation processes in semiconductor wafers result in non-uniform thicknesses of STI regions, particularly between large and small areas, leading to inconsistencies in integrated circuit device formation.
Innovation Solution
A method involving the formation of a hard mask, patterning, and epitaxial growth of active regions within defined STI regions, where the STI regions are formed by filling spaces between patterned hard mask and pad oxide layers with a dielectric material, and then removing the hard mask to grow semiconductor material in these spaces using epitaxy, thereby reversing the conventional trench etching and filling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional trench etching and filling process is used to form STI regions, then STI regions can be formed to define active regions, but the thicknesses of STI regions are not uniform between large and small areas
Solution Approach 1:
The patent inverts the conventional STI formation sequence by first forming the dielectric material layer and patterned hard mask, then etching trenches, and finally filling with semiconductor material. This reversal of the traditional etch-then-fill approach to fill-then-etch enables uniform STI thickness across different area sizes while maintaining process feasibility
2Productivity
If conventional STI formation process is used, then trenches can be filled with dielectric material, but excess process steps and material removal are required
Solution Approach 1:
The patent performs preliminary actions by first depositing the dielectric material layer and forming the hard mask pattern before etching the trenches. This preliminary structuring allows subsequent steps to proceed more efficiently and eliminates the need for final CMP polishing, reducing the total number of process steps
Solution Approach 2:
The hard mask material is temporarily used to define the STI region boundaries during the formation process, then selectively removed after serving its patterning function. This temporary use and subsequent removal of the hard mask simplifies the overall process by eliminating the need for additional planarization steps
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 ensures more uniform thickness of STI regions across different areas, reduces process steps, and enhances the quality of active regions, allowing for consistent formation of integrated circuit devices like transistors and FinFETs.
Implementation Method 1
An epitaxy is performed to grow epitaxy regions in the spaces, wherein the epitaxy regions are grown from the semiconductor substrate
Data Source
AI summary
A method includes forming a hard mask over a substrate, patterning the hard mask to form a first plurality of trenches, and filling a dielectric material into the first plurality of trenches to form a plurality of dielectric regions. The hard mask is removed from between the plurality of dielectric regions, wherein a second plurality of trenches is left by the removed hard mask. An epitaxy step is performed to grow a semiconductor material in the second plurality of trenches.