Flash Memory Bit Line Contact Layout for Short-Circuit Prevention
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Solution Overview
Problem
The challenge of short circuits occurring between conductive contacts and bit lines in flash memory devices due to the larger top width of conductive contacts relative to the bottom width of bit lines as semiconductor designs shrink.
Innovation Solution
A method involving the formation of a bit line trench and via hole through an etching process in a dielectric layer with an etching stop layer, followed by filling the trench and via hole with a conductive material to create a self-aligned bit line and conductive contact, ensuring the top width of the conductive contact is not greater than the bottom width of the bit line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the top width of the conductive contact is formed to be larger than the bottom width of the bit line to facilitate alignment and landing, then the alignment and landing of the bit line on the conductive contact is facilitated, but short circuit occurs between the conductive contact and adjacent bit lines
Solution Approach 1:
The patent inverts the conventional dimensional relationship by making the top width of the conductive contact smaller than or equal to the bottom width of the bit line, rather than larger. This inversion prevents adjacent bit lines from shorting to the conductive contact while still achieving proper alignment and electrical connection through the self-aligned formation process.
Solution Approach 2:
The patent employs a self-aligned formation process where the bit line and conductive contact are formed simultaneously through a single etching process. The conductive contact is automatically positioned relative to the bit line without requiring separate alignment steps, eliminating the need for the conventional larger top width design while ensuring proper electrical connection.
2Volume of moving object
If the size of the flash memory design continues to shrink to increase integration density, then the device size is reduced, but short circuit is easily to occur between the conductive contact and bit line
Solution Approach 1:
The self-aligned formation process ensures that as device dimensions are scaled down, the conductive contact automatically maintains proper positioning relative to the bit line through the single etching process. This eliminates alignment errors that would otherwise be magnified at smaller dimensions, preventing short circuits even as the device size continues to shrink.
Solution Approach 2:
By inverting the dimensional relationship to make the conductive contact top width smaller than or equal to the bit line bottom width, the design creates inherent spacing that prevents short circuits during size scaling. This inverted geometry provides a built-in safety margin that becomes increasingly important as feature sizes are reduced to increase integration density.
Data Source
AI summary
The embodiments of the invention provide a semiconductor device including a substrate, a gate, a source/drain region, a first dielectric layer, an etching stop layer, a second dielectric layer, an additional dielectric layer, a conductive contact and a bit line. The gate is disposed on the substrate. The source/drain region is disposed in the substrate and on a side of the gate. The first dielectric layer is disposed on the gate. The etching stop layer is disposed on the first dielectric layer. The second dielectric layer is disposed on the etching stop layer. The additional dielectric layer is disposed in the second dielectric layer and the etching stop layer. The conductive contact penetrates through the first dielectric layer and is electrically connected to the source/drain region. The bit line penetrates through second dielectric layer, the etching stop layer and the additional dielectric layer to electrically connect to the conductive contact.