Channel Hot Electron Injection Programming Method
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Solution Overview
Problem
Channel Hot Electron Injection (CHEI) programming in non-volatile memory cells faces inefficiencies due to longer programming time, higher power consumption, and lower reliability caused by the corner effect, which complicates circuit design and increases area requirements.
Innovation Solution
A method and device that utilize a write circuit and verification circuit to apply multiple variable pulses with predetermined amplitudes to maintain a consistent gate injection current during programming, with the verification circuit sensing conduction current and adjusting the programming operation to prevent channel hot hole injection and optimize programming efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed control line voltage is applied during programming, then circuit design is simple, but programming time is long and programming efficiency is low
Solution Approach 1:
The control line voltage is changed from a fixed value to a dynamically adjustable value that varies during the programming process. The voltage starts at an initial level and is progressively increased in multiple steps to maintain optimal programming conditions throughout the operation, thereby improving programming efficiency without significantly complicating the circuit design.
Solution Approach 2:
The control line voltage parameter is modified during the programming process by applying multiple voltage levels in sequence. This parameter change allows the system to maintain high gate injection current throughout programming, addressing the inefficiency of fixed voltage while avoiding the complexity of continuously adaptive circuits.
2Productivity
If control line voltage is increased to maintain high gate injection current, then programming efficiency improves, but power consumption increases
Solution Approach 1:
The control line voltage is applied in periodic steps rather than continuously at maximum level. The voltage is increased in discrete increments at specific intervals during programming, allowing the system to maintain high gate injection current when needed while reducing power consumption during other phases of the programming cycle.
Solution Approach 2:
The voltage level is dynamically adjusted to match the programming progress and requirements. By applying higher voltage only when and where needed to maintain optimal gate injection current, the system achieves high programming efficiency without sustaining maximum power consumption throughout the entire operation.
3Reliability
If control line voltage is increased to compensate for corner effect, then programming reliability improves, but circuit complexity and area increase
Solution Approach 1:
The control line voltage parameter is adjusted in multiple steps during programming to compensate for corner effects and ensure reliable programming across different transistor characteristics. This parameter modification approach achieves improved reliability without requiring complex circuit modifications to address corner effects.
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
This approach reduces programming time, lowers power consumption, and enhances reliability by maintaining a high gate injection current throughout the programming cycle, thereby improving the efficiency and reducing the risk of damage to memory transistors.
Implementation Method 1
Memory cells are typically programmed through Channel Hot Electron Injection (CHEI). CHEI occurs when channel carriers traveling from source to drain of a metal-oxide-semiconductor (MOS) transistor are heated due to drain-source voltage applied across the drain and the source. The hot electrons at the end of the channel have high energy, and are injected into a floating gate of the MOS transistor
Data Source
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AI summary
A nonvolatile memory device for reducing programming current and improving reliability comprises a memory cell array, a write circuit, and a verification circuit. The memory cell array comprises memory cells (10) arranged at crossing points of a bit-line and word-line matrix of the memory cell array. The write circuit provides multiple variable pulses to each word-line for programming. The multiple variable pulses have predetermined amplitude for keeping gate injection current roughly maximum while lowering conduction current during programming operation. The verification circuit senses variation of the conduction current during the programming operation, and disables the programming operation if the sensed conduction current during the programming operation reaches a predetermined value.