Single-Mask Staircase Etching Without Overhung Regions
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Solution Overview
Problem
Semiconductor devices with stacked layers face mechanical instabilities due to thickness differences and overhung regions in inverted staircase structures, leading to issues like delamination and fracturing during etching processes.
Innovation Solution
A single-mask stack etching method is employed to form staircase structures by sequentially etching silver, nickel, and titanium layers using isotropic etching operations, followed by rinsing and drying, which eliminates overhung regions and improves mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If inverted staircase structures are formed in stacked layers, then etching operations can be performed, but mechanical instabilities occur due to thickness differences and overhung regions leading to delamination and fracturing
Solution Approach 1:
The patent inverts the traditional staircase structure formation approach by creating an inverted staircase configuration during etching, then performing additional etching operations to remove overhung regions. This inversion allows the etching process to proceed while subsequently eliminating the mechanical instability causes through controlled material removal from the overhung portions.
Solution Approach 2:
The patent performs preliminary etching operations to form the inverted staircase structure before addressing the mechanical stability issue. By first establishing the etched structure and then systematically removing overhung regions in subsequent operations, the process enables etching to occur while pre-planning for the removal of instability-causing features.
2Manufacturing precision
If multiple masks are used to form precise staircase structures, then manufacturing precision improves, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent combines multiple etching operations into a unified process flow that uses a single mask. By merging the formation of the inverted staircase structure and the removal of overhung regions into one integrated process sequence, the method achieves precise staircase structures without requiring multiple separate masking steps, thereby reducing device complexity while maintaining manufacturing precision.
Solution Approach 2:
The single mask used in the patent serves multiple functions: it defines the initial etching pattern for the inverted staircase structure and continues to guide subsequent etching operations for removing overhung regions. This multi-functional use of a single mask eliminates the need for multiple specialized masks, reducing process complexity while maintaining precision.
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 enhances mechanical stability and manufacturing efficiency by forming staircase structures that reduce mechanical instabilities and allow for clearer in-process inspections, while using a single mask reduces costs compared to multi-mask techniques.
Implementation Method 1
each of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation comprise an isotropic etching operation
Data Source
AI summary
Methods, systems, and devices for semiconductor manufacturing are described. A stack of materials may be formed on a semiconductor substrate. The stack of materials may include a first material, a second material, and a third material. A first etching operation may be performed. The first etching operation may remove a first portion of the first material. A second etching operation may be performed. The second etching operation may remove a first portion of the second material. A third etching operation may be performed. The third etching operation may remove a first portion of the third material. A fourth etching operation may be performed. The fourth etching operation may remove a second portion of the second material. A fifth etching operation may be performed. The fifth etching operation may remove a second portion of the first material.