Semiconductor Memory Bit Line Coupling Reduction
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Solution Overview
Problem
Semiconductor memory devices face challenges in reducing coupling capacitance between bit lines, which affects device performance and reliability during programming operations.
Innovation Solution
The design includes a semiconductor memory device with a device isolation pattern defining active regions, insulation layers, and conductive structures that allow for the formation of bit lines at different heights and the use of landing plugs and contact plugs to reduce the aspect ratio of contact holes, thereby minimizing coupling capacitance and improving process margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bit lines are positioned at the same height, then the manufacturing process is simpler, but coupling capacitance between bit lines increases
Solution Approach 1:
The patent positions bit lines at different heights (different vertical dimensions) to reduce coupling capacitance. Specifically, first bit lines are formed at a first height and second bit lines are formed at a second height that is different from the first height, thereby reducing electromagnetic coupling between adjacent bit lines while maintaining a manufacturable process through multi-layer interconnect structures.
2Manufacturing precision
If contact hole aspect ratio is reduced, then manufacturing precision improves, but device area increases
Solution Approach 1:
The patent segments the contact path into multiple sections by introducing intermediate conductive structures and multiple interlayer dielectric layers. Instead of forming a single deep contact hole, the electrical connection is achieved through a series of shallower contact holes and conductive plugs distributed across multiple layers, reducing the aspect ratio of individual contact holes while maintaining electrical connectivity within a compact area.
3Object-affected harmful factors
If bit lines are separated vertically, then coupling capacitance is reduced, but device complexity increases
Solution Approach 1:
The patent employs a unified multi-layer interconnect architecture where conductive structures serve multiple functions: they act as bit lines for data transmission, as contacts for electrical connection to memory cells, and as part of the overall device isolation scheme. This multi-functional design reduces the need for separate specialized structures, thereby limiting the increase in device complexity despite the vertical separation of bit lines.
Data Source
AI summary
In one embodiment, a semiconductor memory device includes a substrate having first and second active regions. The first active region includes a first source and drain regions and the second active region includes a second source and drain regions. A first interlayer dielectric is located over the substrate. A first conductive structure extends through the first interlayer dielectric. A first bit line is on the first interlayer dielectric. A second interlayer dielectric is on the first interlayer dielectric. A contact hole extends through the second and first interlayer dielectrics. The device includes a second conductive structure within the contact hole and extending through the first and second interlayer dielectrics. A second bit line is on the second interlayer dielectric. A width of the contact hole at a bottom of the second interlayer dielectric is less than or substantially equal to a width at a top of the second interlayer dielectric.