3D Unipolar Logic Circuit Vertical Stacking Low Power
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Solution Overview
Problem
Conventional CMOS logic integrated circuits face challenges in reducing stand-by power consumption, limiting the widespread adoption of unipolar logic, and as feature sizes shrink, the cost per transistor increases, making it difficult to achieve further density and performance improvements using traditional methods.
Innovation Solution
The development of novel unipolar circuits with vertical structures that employ capacitors for precharge and bootstrap operations, and clocked gate designs to minimize power loss, along with ultra-short transistor channel lengths fabricated without lithography, enabling low stand-by power and high density integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If unipolar logic is used to reduce manufacturing cost, then manufacturing cost decreases, but stand-by power consumption increases
Solution Approach 1:
Capacitors are employed to enable a precharge state, where nodes are precharged to specific voltage levels before logic operations. This preliminary action ensures that unipolar logic circuits can maintain low stand-by power by avoiding continuous current flow while preserving logic states through capacitive storage.
Solution Approach 2:
The patent changes the voltage parameters and operating modes of unipolar logic circuits by implementing clocked gate designs and bootstrap techniques. These parameter changes allow the circuit to operate in modes that minimize stand-by power consumption while maintaining compatibility with low-cost unipolar transistor fabrication.
2Quantity of substance
If feature size is reduced to increase transistor density, then transistor density increases, but cost per transistor increases
Solution Approach 1:
The patent transitions from planar 2D circuit layouts to three-dimensional vertical structures. By stacking transistor layers and routing signals vertically through multiple interconnection layers, the design achieves high transistor density without requiring proportional reductions in lateral feature sizes, thereby avoiding the exponential cost increases associated with advanced lithography nodes.
Solution Approach 2:
Multiple transistor layers and interconnection layers are nested vertically within a three-dimensional structure. Each layer contains complete logic gates and interconnects, with layers stacked one above another. This nesting approach packs more transistors into a given footprint without requiring smaller lateral dimensions, thus maintaining manufacturing cost effectiveness.
3Quantity of substance
If vertical structures are used to increase density, then integration density increases, but manufacturing complexity increases
Solution Approach 1:
The patent employs universal building blocks and standardized layer structures that can be replicated across the wafer. Each vertical stack follows a consistent pattern of transistor layers and interconnection layers, allowing manufacturing processes to be standardized and automated. This universality reduces manufacturing complexity despite the increased density achieved through vertical structures.
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
These designs achieve low stand-by power, high speed, and increased density compared to conventional silicon CMOS circuitry, allowing for true monolithic 3D integrated circuits with reduced costs and improved performance.
Implementation Method 1
capacitors are employed to enable a precharge state
Implementation Method 2
a clocked gate design utilizes a clock at each gate to bootstrap the voltage so there's no loss due to threshold voltage drop
Data Source
AI summary
Apparatus and associated methods related to a three dimensional integrated logic circuit that includes a columnar active region. Within the columnar active region resides an interdigitated plurality of semiconductor columns and conductive columns. A plurality of transistors is vertically arranged along each semiconductor column, which extends from a bottom surface of the columnar logic region to a top surface of the columnar logic region. The plurality of transistors are electrically interconnected so as to perform a logic function and to generate a logic output signal at a logic output port in response to a logic input signal received at a logic input port. Each of the plurality of conductive columns is adjacent to at least one of the plurality of semiconductor columns and extends along a columnar axis to one or more interconnection layers at the top and/or bottom surfaces of the columnar active layer.