Semiconductor Memory Device Input/Output Buffer Transistor Configuration
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Solution Overview
Problem
The existing semiconductor memory devices face challenges in reducing power consumption and maintaining high-speed operation due to the need for multiple transistor types with different oxide film thicknesses, leading to increased manufacturing complexity and potential performance deterioration.
Innovation Solution
The semiconductor memory device employs transistors with two optimized gate insulation film thicknesses: one for the memory cell array and peripheral circuits, and another for the input/output buffer, with adjusted threshold voltages to accommodate different power supply voltages, simplifying the manufacturing process and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three different kinds of transistors with different oxide film thicknesses are used for memory cell array, peripheral circuits, and input/output buffer, then each unit can have appropriate performance for its power supply voltage, but the manufacturing process becomes more complex with extra steps
Solution Approach 1:
The patent applies local quality by configuring transistors in the input/output buffer with a thinner oxide film thickness compared to the memory cell array transistors. This local differentiation allows the input/output buffer to operate efficiently at lower voltage (VDD) while the memory cell array maintains higher voltage (VPP) operation, optimizing performance for each specific circuit region without requiring three distinct transistor types throughout the entire device.
2Device complexity
If only two kinds of oxide film thicknesses are used to simplify manufacturing, then manufacturing complexity is reduced, but transistor performance for high-speed operation deteriorates
Solution Approach 1:
The patent employs parameter changes by adjusting the oxide film thickness parameter specifically for transistors in the input/output buffer region. By making the oxide film thinner in this specific region, the transistors can switch faster and operate at lower voltages, thereby improving overall device speed and reducing power consumption while maintaining compatibility with a simplified two-type manufacturing process.
3Use of energy by moving object
If transistors with thin oxide films are used for peripheral circuits to reduce power consumption, then power consumption is reduced, but the performance of input/output circuits suffers when using the same transistor type
Solution Approach 1:
The patent applies local quality by configuring transistors in the input/output buffer with a thinner oxide film thickness compared to the memory cell array transistors. This local differentiation allows the input/output buffer to operate efficiently at lower voltage (VDD) while the memory cell array maintains higher voltage (VPP) operation, optimizing performance for each specific circuit region without requiring three distinct transistor types throughout the entire device.
Data Source
AI summary
A semiconductor memory device with low power consumption and improved transfer rate of an input/output buffer at reduced manufacturing cost is provided. Thick-film transistors are used for a memory cell array 33, a row decoder 30, and a sense amplifier 32, surrounded by a bold broken line. Thick-film transistors having a threshold voltage lower than the aforementioned transistors are used for input buffers 11 to 13 and an input/output buffer 26, surrounded by a bold line. Thin-film transistors are used for a clock generator 16, a command decoder 17, a mode register 18, a controller 20, a row address buffer and refresh counter 21, a column address buffer and burst counter 22, a data control circuit 23, a latch circuit 24, a DLL 25, and a column decoder 31.