Word Line Oxide Thickness Variation for Short Circuit Prevention
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Solution Overview
Problem
As semiconductor devices shrink, the gap between word line contacts becomes smaller, increasing the risk of short circuits, necessitating a larger short-circuit margin to prevent such failures.
Innovation Solution
The solution involves adjusting the cross-sectional dimensions of trenches and oxide films in the edge area of word lines to create a sufficient gap between word line contacts, ensuring electrical isolation and preventing short circuits while allowing for further device miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device size is reduced, then productivity and integration are improved, but the gap between word line contacts becomes smaller increasing short circuit risk
Solution Approach 1:
The patent applies different oxide film thicknesses at different locations: a first oxide film with a first thickness at the center area and a second oxide film with a second thickness greater than the first at the edge area. This local differentiation ensures sufficient gap maintenance at edge areas where short circuits are more likely, while allowing tighter spacing in center areas, thus resolving the contradiction between device scaling and short circuit prevention.
2Reliability
If word line contact gap is increased, then short circuit prevention is improved, but device area increases
Solution Approach 1:
Instead of uniformly increasing the gap across the entire device, the patent locally increases the oxide film thickness only at the edge areas where word line contacts are positioned. This localized approach provides enhanced short circuit prevention where needed while maintaining compact spacing in the center area, thus preventing unnecessary area increase.
Solution Approach 2:
The patent addresses the gap issue not by increasing the horizontal gap dimension between word line contacts, but by increasing the vertical dimension through thicker oxide films. This dimensional transition allows sufficient isolation margin without expanding the device footprint, resolving the contradiction between reliability and area.
Data Source
AI summary
Some embodiments of the disclosure provide an apparatus comprising: a word line array including a plurality of word lines each extending through a memory mat in a first horizontal direction, the plurality of word lines including first and second word lines arranged adjacent to each other in a second horizontal direction; and a word line contact of the first word line, the word line contact separated from the second word line by a gap. The first and second word lines each have a first oxide film at a center area of the word line array in the memory mat. The first and second word lines each have a second oxide film at an edge area of the word line array outside the memory mat, the second oxide film having a thickness greater than a thickness of the first oxide film.