MEMS Logic Switches for Compact Non-Volatile SRAM Cells
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Solution Overview
Problem
Current MEMS-based non-volatile memory designs require CMOS devices for peripheral circuits and pass gates, limiting the use of MEMS-only designs, and existing nvSRAM technologies face challenges with speed, endurance, and cost due to large memory cell size and additional process steps.
Innovation Solution
Replacing transistors with MEMS switches in devices like FPGAs, NAND, and nvSRAM, allowing for MEMS-only designs without additional chip layers or FEOL process impacts, and utilizing MEMS switches in SRAM cells to reduce size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If CMOS devices are used for peripheral circuits and pass gates in MEMS-based NVM, then device functionality is achieved, but chip space efficiency is reduced and manufacturing complexity increases
Solution Approach 1:
The patent merges the functionality of CMOS transistors with MEMS switches by integrating the MEMS switch structure directly into the transistor architecture. The MEMS switch replaces the traditional transistor channel, combining mechanical switching with electronic circuit functionality into a single integrated structure, thereby reducing the need for separate CMOS devices and simplifying the overall chip structure.
Solution Approach 2:
The MEMS switch is designed to serve multiple functions: it acts as both the switching element and the memory storage mechanism. By making the MEMS device multi-functional, the patent eliminates the need for separate CMOS transistors for switching operations, thereby reducing device complexity and improving chip space utilization.
2Area of moving object
If MEMS switches replace transistors in SRAM cells, then memory cell size is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs parameter changes in the MEMS switch design, specifically optimizing the mechanical properties of the cantilever beam and the electrostatic actuation parameters. By carefully tuning these parameters, the patent achieves reliable switching behavior with reduced dimensions, allowing smaller memory cell area while maintaining acceptable manufacturing precision through parameter optimization rather than requiring extreme precision.
3Reliability
If additional process steps are added for nvSRAM functionality, then non-volatile storage capability is achieved, but production cost increases
Solution Approach 1:
The MEMS-based nvSRAM design utilizes the inherent mechanical properties of the MEMS switch structure to provide non-volatile storage. The cantilever beam's natural elasticity and the electrostatic actuation mechanism enable data retention without requiring additional complex process steps. The structure essentially serves itself by using its mechanical design to achieve the non-volatile functionality, thereby reducing production costs.
4Area of stationary object
If MEMS-only design is implemented, then chip space efficiency is improved, but interface design complexity between MEMS and CMOS increases
Solution Approach 1:
The patent introduces an intermediary read/write circuit that bridges the MEMS switch array and the external interface. This intermediary circuit handles the complex signal conditioning and data latching functions, allowing the MEMS-only memory array to communicate effectively with CMOS logic without requiring complex direct interfaces. The intermediary circuit simplifies the overall system design by isolating the interface complexity from the memory array itself.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables more efficient use of chip space, reduces memory cell size, and lowers production costs by integrating MEMS devices in BEOL processes, while maintaining fast read/write capabilities and non-volatile data storage.
Implementation Method 1
a first micro electromechanical device having a first contact electrode, a first pull-in electrode and a first cantilever electrode movable from a position in contact with the first contact electrode and a position spaced from the first contact electrode
Data Source
AI summary
Embodiments disclosed herein generally relate to switches that utilize micro-electromechanical systems (MEMS). By replacing transistors in many devices with switches such as MEMS switches, the devices may be used for logic applications. MEMS switches may be used in devices such as FPGAs, NAND devices, nvSRAM devices, AMS chips and general memory logic devices. The benefit of utilizing MEMS devices in place of transistors is that the transistors utilize more space on the chip. Additionally, the MEMS devices can be formed in the BEOL without having any negative impacts on the FEOL or necessitating the use of additional layers within the chip.