Dual-Mode Phase Change Memory for Optical Electrical Programming
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Solution Overview
Problem
Phase change memories require improved programming methods to enhance their functionality and efficiency, as existing technologies are limited in their ability to effectively switch between amorphous and crystalline states for data storage.
Innovation Solution
A phase change memory that can be both optically and electrically programmed, utilizing a variable resistor phase change material that can be altered by electrical signals or laser light to change its resistance states, allowing for dual-mode programming and reading capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phase change memory uses traditional electrical programming only, then the memory can be programmed, but the programming speed and versatility are limited
Solution Approach 1:
The phase change memory cell is designed to support both electrical programming and optical programming modes. The same memory cell can be programmed using electrical signals to transition between amorphous and crystalline states, or using optical signals (laser) to achieve the same state transitions. This multi-functionality enables the memory to operate in different programming modes depending on the application requirements, thereby improving both speed and versatility.
Solution Approach 2:
The invention changes the programming parameter from purely electrical (voltage/current) to include optical parameters (light intensity, laser power). By introducing optical programming capability, the system can switch between different programming methodologies - electrical programming for certain operations and optical programming for others - thus resolving the contradiction between programming speed and versatility.
2Productivity
If phase change memory uses optical programming only, then the memory can be programmed with high speed, but the device complexity increases
Solution Approach 1:
The memory device is designed with universal functionality to accommodate both electrical and optical programming. The same physical structure (phase change material between electrodes) supports both programming methods, eliminating the need for separate dedicated memory cells for each mode. This approach manages device complexity by sharing the same fundamental structure while adding optical programming capability.
Solution Approach 2:
The phase change material itself acts as an intermediary that mediates between electrical and optical programming methods. It responds to both electrical signals (current pulses) and optical signals (laser light), converting both forms of energy into the necessary thermal effects to achieve phase transitions. This intermediary property allows the system to manage complexity by using a single material system that supports multiple programming approaches.
3Reliability
If phase change material is heated to high temperatures for programming, then the state transitions are achieved, but the power consumption increases
Solution Approach 1:
The invention changes the heating parameter by introducing optical heating as an alternative to electrical heating. Optical programming uses laser light to directly heat the phase change material, achieving state transitions with potentially lower energy consumption compared to traditional electrical programming. The system can select the optimal heating method based on the specific programming operation, thereby managing power consumption while maintaining reliable state transitions.
Solution Approach 2:
The programming process uses periodic or pulsed heating action rather than continuous heating. Both electrical and optical programming methods employ pulsed current or pulsed laser exposure to achieve the necessary thermal effects for phase transitions. This periodic action allows the material to cool between pulses, reducing overall energy consumption while maintaining accurate and reliable state transitions through the cumulative effect of repeated pulsing.
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 efficient and versatile data storage by allowing both optical and electrical programming, improving the speed and accuracy of state transitions between amorphous and crystalline states, and enabling single-bit or multi-bit storage with reduced power consumption.
Implementation Method 1
Phase change memories use phase change materials, i.e., materials that may be electrically switched between a generally amorphous and a generally crystalline state
Implementation Method 2
The interface 28 may also develop optical signals that may be used to alter the state of the memory cell 14. For example, in one embodiment, an optical mirror system 12 may control the application of laser light to specific cells within the memory cell 14
Implementation Method 3
An electrical current may flow through a portion of the memory material 24 in response to the applied voltage potentials, and may result in heating of the memory material 24
Data Source
AI summary
A phase change memory may be configured to enable both optical and electrical accessing of the memory. In one embodiment, each cell may be electrically accessed by a laser beam, and at the same time each cell may be electrically accessed by electrical addressing signals.