Deep Trench Capacitor Corner Rounding to Reduce Tip Discharge
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Solution Overview
Problem
Existing deep trench capacitors in semiconductor devices face challenges with tip discharge due to sharp corners formed by shadow effects and ion scattering, leading to electrical overstress and device damage.
Innovation Solution
A trimming process is applied to form rounded corners on the semiconductor substrate adjacent to trenches, followed by a thermal oxidation process to create a dielectric liner, resulting in improved reliability of deep trench capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a deep trench capacitor is formed using conventional etching processes, then the capacitor structure is created, but sharp corners are formed due to shadow effects and ion scattering causing tip discharge and electrical overstress
Solution Approach 1:
A trimming process is performed before capacitor formation to remove sharp corners from the substrate adjacent to the trench. This preliminary action prevents tip discharge from occurring during subsequent capacitor fabrication and operation, eliminating the harmful effect before it can cause damage.
Solution Approach 2:
The trimming process converts the potentially harmful sharp corners into beneficial rounded corners. By intentionally modifying the geometry to have rounded corners, the design transforms what would be a source of tip discharge into a feature that enhances device reliability and prevents electrical overstress.
2Reliability
If existing capacitor structures are used to isolate active region segments, then isolation function is achieved, but reliability is insufficient due to tip discharge issues
Solution Approach 1:
The substrate is trimmed to create rounded corners before capacitor formation. This preliminary modification ensures that when the capacitor is formed and begins operation, the rounded corners prevent tip discharge and eliminate leakage current, thereby improving reliability from the outset.
Solution Approach 2:
The geometry parameter of the substrate corners is changed from sharp to rounded. This parameter change fundamentally alters the electrical field distribution, preventing concentration of electric field lines at corners and thereby eliminating tip discharge and associated harmful effects.
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
The rounded corners reduce tip discharge, enhancing the reliability and performance of deep trench capacitors by minimizing electrical overstress and leakage current.
Implementation Method 1
followed by a thermal oxidation process to create a dielectric liner
Data Source
AI summary
Semiconductor structures and methods are provided. An exemplary method according to the present disclosure includes forming a patterned hard mask over a semiconductor substrate, the patterned hard mask exposing a first portion of the semiconductor substrate and covering a second portion of the semiconductor substrate disposed adjacent to the first portion, wherein the second portion comprises an upper part in direct contact with the patterned hard mask and a lower part, performing a first etching process to recess the first portion and the lower part of the second portion to form a trench, performing a second etching process to trim the upper part of the second portion, after the performing of the second etching process, selectively removing the patterned hard mask, and forming a capacitor in and over the trench.