Word Line Height Offset for Contact Margin in Semiconductor Arrays
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Solution Overview
Problem
The shrinking gap between word lines in semiconductor devices poses challenges in maintaining critical dimension (CD) and overlay requirements for conductive contacts, leading to insufficient process margins.
Innovation Solution
Designing the second section of word lines in the pick-up region with a different level height from the first section in the cell region, enhancing the gap and spacing between conductive contacts, thereby reducing CD and overlay requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the gap between word lines is shrunk to increase device density, then the horizontal area is reduced, but the critical dimension and overlay requirements for conductive contacts become much stricter
Solution Approach 1:
The patent introduces a vertical dimension change by forming the second section of the word line at a different level height than the first section. This vertical offset creates additional spacing between the conductive contact and adjacent word lines in the vertical direction, effectively compensating for the reduced horizontal gap between word lines and relaxing the critical dimension and overlay requirements.
Solution Approach 2:
The patent applies local quality by creating a specific structural configuration where only the second section of the word line in the pick-up region has a different level height, while the first section in the cell region maintains its original level. This localized structural modification针对性地 addresses the contact formation area without affecting the overall word line functionality.
2Productivity
If the gap between conductive contact and adjacent word lines is shrunk, then the device layout becomes more compact, but the process margin for conductive contact is insufficient
Solution Approach 1:
The patent resolves this contradiction by utilizing the vertical dimension to create spacing. The second section of the word line is formed at a different level height, which increases the vertical distance between the conductive contact and adjacent word lines. This allows for more compact horizontal layout while maintaining adequate process margin through the vertical offset.
Solution Approach 2:
The different level height of the second section acts as an intermediary spatial buffer between the conductive contact and adjacent word lines. This vertical offset serves as a protective margin that prevents potential short circuits or process variations from affecting device reliability, while still allowing compact horizontal packaging.
Data Source
AI summary
The disclosure provides a semiconductor structure and a method for forming the same. The semiconductor structure includes a substrate including a cell region and a pick-up region adjacent to the cell region, word lines embedded in the substrate, arranged in a first direction, extending in a second direction crossing the cell region and the pick-up region, and each including a first segment in the cell region and a second segment in the pick-up region, an insulation layer embedded in the substrate on each word line and, and a conductive contact on the second segment of each word line. The first segment includes a first top surface contacting the insulation layer. The second segment includes a second top surface contacting the conductive contact and a third top surface contacting the insulation layer. The second top surface has a level height different from a level height of the first top surface.