Decoupling Capacitor Circuit Using Series Deep Trench Capacitors
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Solution Overview
Problem
Traditional gate oxide capacitors occupy large die area and have insufficient voltage durability, making them unsuitable for high-voltage applications and limiting die integration in DRAM memory cells.
Innovation Solution
A decoupling capacitor circuit comprising multiple deep trench capacitors connected in series, with a voltage divider and push-pull circuits to evenly distribute voltage and maintain each capacitor within a predetermined voltage range, thereby increasing voltage tolerance and reducing die area occupation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate oxide capacitors are used for decoupling, then voltage durability is achieved, but die area occupation becomes excessively large
Solution Approach 1:
The patent divides a single high-voltage decoupling capacitor into multiple deep trench capacitors connected in series. Each deep trench capacitor can withstand a portion of the total voltage (e.g., 1.5V each for a 3.6V system), and their series connection achieves the required overall voltage durability while each individual capacitor occupies minimal die area, thus resolving the contradiction between voltage durability and die area occupation.
2Reliability
If multiple deep trench capacitors are connected in series to increase voltage tolerance, then voltage durability is improved, but voltage distribution uniformity deteriorates due to parasitic devices and leakage current
Solution Approach 1:
The patent incorporates control circuits that continuously monitor the voltage across each deep trench capacitor and provide feedback signals. Based on this feedback, the control circuits dynamically adjust the voltage distribution to compensate for variations caused by parasitic devices and leakage current, ensuring uniform voltage distribution across all series-connected capacitors and maintaining system reliability.
3Area of stationary object
If deep trench capacitors are used to reduce die area, then integration is improved, but voltage durability becomes insufficient for high-voltage applications
Solution Approach 1:
The patent uses multiple deep trench capacitors connected in series to achieve high voltage durability. Each deep trench capacitor is designed to withstand a fraction of the total operating voltage (e.g., 1.5V per capacitor for a 3.6V system). This segmentation allows the use of compact deep trench structures while collectively achieving the required voltage tolerance, thus resolving the contradiction between die area reduction and voltage durability.
Data Source
AI summary
The invention discloses a decoupling capacitor circuit, comprising a plurality of coupled deep trench capacitors connected in series and a plurality of push-pull circuits. The decoupling capacitor circuit controls the voltage across each deep trench capacitor via the push-pull circuit so that it will not be influenced by the defect (leakage current) of the deep trench capacitor or the bias voltage of the parasitic devices.