Internal Voltage Controller for Semiconductor Memory
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Solution Overview
Problem
Conventional semiconductor memory devices face challenges in generating a stable internal voltage due to variations in fabrication process conditions, such as PVT, leading to inconsistent reference voltage levels across memory chips, which affects reliability and requires manual adjustment in quality control processes.
Innovation Solution
An internal voltage controller is introduced, comprising a fuse ROM block, a bit counter for up/down counting, a decoder to activate switching signals, and a reference voltage selector to dynamically adjust the internal reference voltage, allowing for programmed increases or decreases in voltage levels to match process changes, thereby enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional internal voltage control devices are used, then device structure is simple, but internal voltage stability across process variations deteriorates
Solution Approach 1:
The patent implements dynamic adjustability of the internal reference voltage through a control signal that selects different voltage levels from a plurality of internally generated reference voltages. This allows the system to adapt to process variations (PVT conditions) by dynamically changing the reference voltage level, thereby maintaining internal voltage stability without requiring complex external calibration circuits.
Solution Approach 2:
The patent changes the parameter of reference voltage level by providing a control signal that selects among multiple internally generated reference voltages with different levels. This parameter adjustment compensates for process variations in fabrication, ensuring stable internal voltage output across different manufacturing conditions without increasing overall device complexity.
2Adaptability or versatility
If fixed reference voltage levels are used, then device complexity is reduced, but adaptability to process changes deteriorates
Solution Approach 1:
The patent provides a universal internal voltage control mechanism that can adapt to different process conditions by selecting from multiple internally generated reference voltage levels. The control signal enables a single device to serve multiple functions across different PVT conditions, making the system universally applicable without requiring device-specific external calibration for each process variation.
Solution Approach 2:
The system transitions from fixed reference voltage to dynamic selection among multiple reference voltage levels based on process conditions. The control signal enables real-time adaptation to process changes, allowing the device to maintain optimal performance across varying fabrication conditions without increasing external complexity.
3Manufacturing precision
If manual voltage trimming is performed for each chip, then voltage precision is improved, but manufacturing time increases
Solution Approach 1:
The patent generates multiple internally generated reference voltages with different levels during the manufacturing process before final device operation. These pre-generated reference voltages are stored within the device, eliminating the need for post-manufacturing manual trimming. The control signal selects the appropriate pre-prepared reference voltage level, achieving high precision while maintaining fast manufacturing throughput.
Solution Approach 2:
The device performs self-calibration by internally generating multiple reference voltage levels and selecting the appropriate one based on process conditions. This self-service mechanism eliminates the need for external manual trimming operations, achieving both high voltage precision and maintained manufacturing productivity without requiring additional external equipment or time-consuming calibration steps.
Data Source
AI summary
A device controls internal voltage. Increased reliability of a semiconductor memory device is obtained by increasing or decreasing a level of internal reference voltage according to change of the device. Fuse ROMs generate fuse signals having different levels according to a cutting condition of each fuse. A bit counter performs up/down counting operation in response to a count control signal after setting the fuse signals to initial values in response to a set signal and generates counter output signals which are higher or lower than the initial values by a counting number. A decoder decodes the counter output signals and activates one of switching signals. A reference voltage selector provides a trimming level of internal reference voltage in response to the switching signals and generating reference voltage.