Capacitor Trench Oxide Removal for Needle-Shaped Silicon
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Solution Overview
Problem
The formation of needle-like elongated silicon structures during the MacEtch process in semiconductor wafers leads to cracks in dielectric layers and reduces withstand voltage characteristics due to electric field concentration, posing a risk of leakage failure in capacitors.
Innovation Solution
A method involving oxidation and oxide removal processes to eliminate needle-shaped silicon by forming an oxide on the recess inner surface and using a liquid to dissolve the oxide, followed by impurity doping and subsequent oxide removal to stabilize the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MacEtch method is used to form high aspect ratio trench, then etching efficiency is improved, but needle-shaped Si remains on bottom surface causing cracks and leakage failure
Solution Approach 1:
The patent applies preliminary action by performing oxidation treatment on the needle-shaped Si structures before forming the dielectric layer. The oxidation process converts the problematic needle-shaped Si into oxide that can be subsequently removed, preventing cracks and leakage failure in the dielectric layer while maintaining the etching efficiency benefits of the MacEtch method
Solution Approach 2:
The patent extracts the harmful needle-shaped Si structures from the trench bottom surface through an oxidation-removal process. The oxide formed from the needle-shaped Si is selectively removed using etchant, eliminating the source of cracks and electric field concentration while preserving the functional silicon structures
2Ease of manufacture
If needle-shaped Si remains on trench bottom, then etching process is simplified, but electric field concentration occurs reducing withstand voltage characteristics
Solution Approach 1:
The patent converts the harmful needle-shaped Si structures into beneficial oxide structures through controlled oxidation. The oxidation process transforms the problematic silicon into removable oxide, which is then selectively etched away, converting a manufacturing simplicity advantage into a reliability enhancement without significantly complicating the overall process
3Loss of time
If needle-shaped Si is present, then MacEtch process completes quickly, but cracks occur in dielectric layer during subsequent manufacturing
Solution Approach 1:
The patent performs preliminary oxidation treatment on the needle-shaped Si structures before dielectric layer formation. This preliminary action converts the needle-shaped Si into oxide that can be selectively removed, preventing subsequent cracks in the dielectric layer while adding minimal process time
Solution Approach 2:
The patent introduces an intermediary oxidation step that transforms the needle-shaped Si into a removable oxide intermediate state. This intermediary transformation allows for selective removal of the harmful structures while preserving the integrity of the subsequent dielectric layer formation process
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 method effectively removes needle-shaped silicon, preventing cracks and electric field concentration, thereby enhancing capacitor reliability and performance.
Implementation Method 1
oxidizing at least a bottom inner surface of the recess
Implementation Method 2
providing at least the bottom inner surface of the recess with a liquid capable of dissolving an oxide of a semiconductor substrate material
Data Source
AI summary
In general, according to one embodiment, there is provided a method of manufacturing a structure. The method includes forming a recess in a semiconductor substrate; oxidizing at least a bottom inner surface of the recess; and providing at least the bottom inner surface of the recess with a liquid capable of dissolving an oxide of a semiconductor substrate material.