Word Line Lead-Out Layout With T-Shaped Contact Hole
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Solution Overview
Problem
As semiconductor devices integrate at higher levels, the reduced size of word lines and spaces between them increases contact resistance, leading to decreased current flow and reduced charging and discharging speeds of storage capacitors.
Innovation Solution
A word line lead-out structure is designed with a contact hole and metal line configuration where the contact hole covers the word line and the metal line covers the contact hole, optimizing the contact area to reduce resistance, and a method involving groove formation, deposition, and etching processes to create a T-shaped contact hole and aligned metal lines for improved electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the integration level of semiconductor device is improved and the size of word line is reduced, then the area of word line lead-out structure is reduced, but the contact resistance between word line lead-out structure and word line is increased
Solution Approach 1:
The contact hole is designed to extend in the Y-axis direction (perpendicular to word line direction) to cover the word line, transitioning from a simple point contact to a multi-dimensional structure. This dimensional extension increases the contact area without increasing the footprint area in the X-axis direction, thereby reducing contact resistance while maintaining high integration level
Solution Approach 2:
The word line lead-out structure is segmented into distinct functional regions: the contact hole region that covers the word line, the metal line region that extends outward, and the connection region where they interface. This segmentation allows optimization of each region independently, with the contact hole optimized for low resistance contact and the metal line optimized for current distribution
2Reliability
If the contact area between contact hole and metal line is increased, then the contact resistance is reduced, but the device integration is affected
Solution Approach 1:
The contact hole extends in the vertical dimension (Y-axis) to cover the word line, increasing contact area without proportionally increasing the horizontal footprint. This dimensional strategy allows larger contact area for lower resistance while maintaining compact device integration
Solution Approach 2:
The contact hole width is locally increased in the region covering the word line to maximize contact area, while the metal line width is optimized for current carrying capacity in the lead-out region. This local quality optimization ensures low contact resistance where needed without unnecessarily increasing overall device area
Data Source
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AI summary
The present application relates to a word line lead-out structure and a method for preparing the same. A word line extending along an X-axis direction is formed on a substrate. A contact hole covering the word line along a Y-axis direction is formed, the X-axis direction being perpendicular to the Y-axis direction. A metal line covering the contact hole is formed, the contact hole being located between the word line and the metal line and being contact with the word line and the metal line. The contact area of the contact hole and the metal line is larger than that of the contact hole and the word line.