Memory Device Layout with Dummy Pickup Structures
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Solution Overview
Problem
In semiconductor manufacturing, particularly for memory devices using FinFETs, achieving structural symmetry and consistent operating performance is challenging due to the need for precise layout of N-pickup and P-pickup structures to provide substrate voltages to P-type and N-type well regions, which complicates the design and manufacturing process.
Innovation Solution
A memory device layout is designed with alternating and interleaving N-pickup and P-pickup structures along specific directions, accompanied by dummy pickup structures, to ensure symmetrical distribution of substrate voltages across N-type and P-type well regions, utilizing polysilicon lines and fin structures on a substrate with dielectric layers to maintain structural symmetry and performance consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If N-pickup and P-pickup structures are positioned to provide substrate voltages to N-type and P-type well regions, then substrate voltage distribution is achieved, but structural symmetry and layout complexity are compromised
Solution Approach 1:
The patent intentionally introduces asymmetry through dummy pickup structures to compensate for the inherent asymmetry in the pickup structure layout. The dummy structures are positioned to create a symmetrical overall appearance, even though the functional pickup structures themselves are asymmetrically arranged to optimize voltage distribution to well regions.
Solution Approach 2:
Dummy pickup structures are created as copies of the actual pickup structures. These dummy structures replicate the physical form and electrical characteristics of functional pickup structures, allowing them to serve as electrical placeholders that maintain symmetry without providing active voltage distribution function.
2Reliability
If pickup structures are arranged to maintain structural symmetry, then operating performance consistency is improved, but layout design complexity increases
Solution Approach 1:
The patent uses dummy pickup structures to create a symmetrical overall layout appearance. The dummy structures are placed in positions that balance the visual and structural symmetry, even though the functional pickup structures remain asymmetrically positioned to optimize their electrical connection to specific well regions.
Solution Approach 2:
Different regions of the layout are assigned different functions: actual pickup structures in regions where voltage distribution is needed, and dummy pickup structures in regions where symmetry is needed but voltage distribution is not required. This local differentiation allows each part to optimize its specific function.
3Area of moving object
If FinFET structures are used to reduce transistor size, then device area is reduced, but manufacturing precision requirements increase
Solution Approach 1:
Dummy pickup structures serve as electrical placeholders that maintain the physical and electrical characteristics needed for FinFET manufacturing. By providing these dummy structures, the patent ensures that the manufacturing process can proceed with standard precision requirements, as the dummy structures occupy the necessary space and provide appropriate electrical boundaries without requiring additional precision for functional voltage distribution.
Solution Approach 2:
The dummy pickup structures are designed to maintain equipotential regions similar to functional pickup structures. This ensures that during manufacturing, the electrical environment remains consistent across the device, allowing FinFET structures to be manufactured with standard precision without encountering unexpected electrical variations that would arise from asymmetric pickup structure arrangements.
Data Source
AI summary
A memory device includes a pickup area extending along a first direction. The pickup area includes at least one N-pickup structure, distributing along an N-pickup line extending at the first direction. At least one P-pickup structure distributes by alternating with the N-pickup structure at the first direction and interleaves with the N-pickup structure at a second direction. The second direction is perpendicular to the first direction. Dummy pickup structure distributes along the first direction, opposite to the P-pickup structure with respect to the N-pickup line. Further, a cell area is beside the pickup area. The SRAM cells in the cell area form cell rows extending along the second direction. Each SRAM cell covers one N-type well region along the second direction and two P-type well regions along the second direction to sandwich the N-type well region. The N-pickup/P-pickup structures respectively provide first/second substrate voltage to the N-type/P-type well regions.