Word Line Protection Pillars for Better Local CDU Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor manufacturing methods face challenges in achieving uniformity of critical dimensions (CDU) for protection pillars, which protect word line active areas, leading to potential etching issues and inadequate protection.
Innovation Solution
A two-step photolithography process using distinct photomasks to define the shape of protection pillars, allowing individual tuning of parameters and forming rhombus-shaped structures that cover word lines and active areas, enhancing protection and reducing CDU issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single photolithography process is used to form protection pillars, then the manufacturing process is simple, but the local critical dimension uniformity is poor
Solution Approach 1:
The single photolithography process is segmented into multiple sequential photolithography processes (first, second, and third photolithography processes). Each process uses a different photomask (first photomask, second photomask, third photomask) to progressively define and refine the protection pillar structure, allowing independent optimization of each patterning step to achieve better overall critical dimension uniformity
2Manufacturing precision
If photomasks are aligned at different angles, then the protection pillar parameters can be precisely tuned, but the device complexity increases
Solution Approach 1:
The photomasks are deliberately aligned at different asymmetric angles relative to the word line structure. The first photomask, second photomask, and third photomask each have distinct angular orientations that create asymmetric patterning effects, allowing precise control over the protection pillar dimensions and shape by exploiting the asymmetric geometric relationships
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 improves local critical dimension uniformity and enhances protection of active areas under word lines, ensuring precise etching and improved structural integrity.
Implementation Method 1
A first photolithography process is performed to etch the hard mask stack by using a first photomask, wherein the first photomask is along a first direction. A second photolithography process is performed to etch the hard mask stack by using a second photomask, wherein the second photomask is along a second direction, and the second direction is different from the first direction.
Data Source
AI summary
The manufacturing method of a semiconductor device includes providing a word line structure and a hard mask stack on the word line structure. The word line structure includes an active area, a word line, an isolation structure and a protection layer, the word line covers a portion of the active area, the isolation structure is adjacent to the active area and the word line, and the protection layer covers the active area, the word line, and the isolation structure. A first photolithography process is performed to etch the hard mask stack by using a photomask along a first direction. A second photolithography process is performed to etch the hard mask stack by using a photomask along a second direction. A protection pillar covering the portion of the active area by etching the protection layer is formed by using the hard mask stack as a mask.