Deep Trench Formation via Single Liner Mask
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Solution Overview
Problem
Conventional methods for forming deep trench capacitors in DRAMs require two etching masks, increasing complexity and production costs.
Innovation Solution
A method using a single etching mask that combines a liner with selective etching processes to form a deep trench, involving a first etching process, liner deposition, second etching with the liner as a mask, selective wet etching, and post wet etching to achieve the desired trench dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional two-mask etching method is used, then deep trench with sufficient depth and surface area can be formed, but process complexity and production cost increase
Solution Approach 1:
The patent combines the protective layer and etching mask function into a single integrated structure. The liner layer is deposited to protect specific regions, and the same liner serves as the etching mask during subsequent etching processes, eliminating the need for separate protective layers and masks used in conventional methods.
Solution Approach 2:
The liner layer performs multiple functions: it protects the underlying structure during etching, serves as the etching mask defining the trench pattern, and enables both depth control and surface area enlargement through selective etching processes. This multi-functional approach replaces the conventional two-mask system.
2Manufacturing precision
If conventional two-mask method is used, then deep trench capacitor can be formed, but production cost increases
Solution Approach 1:
By merging the protective layer and etching mask into a single liner structure, the patent reduces the number of deposition and patterning steps required. This integration directly reduces material consumption, process time, and equipment usage, thereby lowering production costs while maintaining deep trench capacitor formation quality.
3Device complexity
If single etching mask method is used, then process simplification and cost reduction are achieved, but etching precision must be maintained
Solution Approach 1:
The liner layer is selectively deposited only in specific regions where protection is needed, creating local variations in etching resistance. This selective deposition allows precise control over which areas are etched and which are protected, maintaining etching precision despite using a single mask type.
Solution Approach 2:
The liner layer is deposited in advance before the etching process, pre-defining the protected regions and etching patterns. This preliminary action ensures that the single etching mask is properly positioned and configured to achieve the required etching precision throughout the subsequent depth and width enlargement 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
Simplifies the manufacturing process, reduces production costs, and achieves a deep trench with sufficient depth and surface area, suitable for advanced semiconductor applications.
Implementation Method 1
performing a first etching process to etch the top layer, the bottom layer and the substrate so as to form a recess
Implementation Method 2
performing a selective wet etching to remove the top layer
Implementation Method 3
selectively depositing a liner covering the top layer, the bottom layer and part of the substrate in the recess
Data Source
AI summary
A method for forming a deep trench includes providing a substrate with a bottom layer and a top layer; performing a first etching process to etch the top layer, the bottom layer and the substrate so as to form a recess; selectively depositing a liner covering the top layer, the bottom layer and part of the substrate in the recess; using the liner as an etching mask to perform a second dry etching to etch the recess unmasked by the liner so as to form a deep trench; performing a selective wet etching to remove the top layer; and performing a post wet etching to enlarge the deep trench.