Variable Resistance Switch for High Voltage Programming
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Solution Overview
Problem
In integrated circuit semiconductor devices, rapidly applying a high programming voltage to word lines can cause stress and non-uniform programming due to the accumulation of resistance and capacitance along the word line, leading to differing programming behavior for cells further from the voltage source.
Innovation Solution
A circuit with a charge pump and decoding circuitry that uses a variable resistance switch to progressively apply the high voltage, controlled by a mini-pump's clock frequency, allowing for controlled ramping of the voltage to match the device's characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high voltage is supplied rapidly to the word line, then programming speed is improved, but device stress increases and programming uniformity deteriorates
Solution Approach 1:
The patent applies a variable resistance switch (transistor 205) that dynamically changes its resistance value during the voltage transition. The switch transitions from a high resistance state to a low resistance state, creating a progressive voltage ramp rather than an instantaneous step change. This dynamic resistance adjustment allows the voltage to be applied at a controlled rate, reducing device stress while maintaining programming speed.
Solution Approach 2:
The patent changes the resistance parameter of the switch circuit over time. By controlling the switch to transition from high resistance to low resistance, the voltage rise time is controlled. This parameter change enables the system to balance between programming speed and device stress by adjusting how rapidly the voltage is applied to the word line.
2Productivity
If high voltage is supplied rapidly to the word line, then programming speed is improved, but programming uniformity across cells deteriorates
Solution Approach 1:
The variable resistance switch dynamically adjusts resistance during the voltage application process, creating a controlled ramp that ensures uniform voltage distribution across all cells in the word line. This dynamic adjustment prevents the voltage from rising too quickly, which would cause non-uniform programming in cells located at different positions along the word line.
Solution Approach 2:
The switch circuit prepares the voltage transition in advance by controlling the resistance profile before the full voltage is applied to the word line. This preliminary control of the voltage ramp ensures that when programming begins, all cells receive a uniform voltage transition, improving programming consistency across the entire word line.
3Manufacturing precision
If a variable resistance switch is used to control voltage rise time, then programming uniformity is improved, but device complexity increases
Solution Approach 1:
The variable resistance switch (transistor 205) is controlled by the same control logic that manages the charge pump operation. The switch automatically transitions from high to low resistance as part of the normal programming sequence, eliminating the need for separate control circuits. This self-service approach reduces overall device complexity while maintaining programming uniformity.
Solution Approach 2:
The switch circuit serves multiple functions: it controls the voltage rise time for uniform programming, protects against device stress, and integrates with the existing control logic. By making the switch multi-functional, the patent reduces the need for additional dedicated circuits, thereby minimizing the increase in device complexity.
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 enables more uniform programming by controlling the rise time of the programming voltage, reducing stress on device components and improving programming consistency across the word line.
Implementation Method 1
the switch circuit is of a variable resistance to progressively pass the high voltage in response to a control signal
Implementation Method 2
a charge pump circuit to generate a high voltage
Data Source
AI summary
A circuit for supplying a high voltage to load is described. An example of such a circuit could be used in the peripheral circuitry of a non-volatile memory device for supplying a program voltage from a charge pump to a selected word line. The circuit includes a charge pump that generates the high voltage and decoding circuitry that is connected to receive this high voltage and selectively apply it to a load. The decoding circuitry receives the high voltage through a switch, where the switch is of a variable resistance that progressively passes the high voltage in response to a control signal. In a particular example, the switch includes a transistor connected between the charge pump and the decoding circuitry, where the control gate of the transistor is connected to the output of a second charge pump that is connected to receive the high voltage and a settable clock signal as its inputs.