DRAM Bit Line Nitride Dielectric Parasitic Capacitance
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Solution Overview
Problem
In current dynamic random access memory (DRAM) devices, the parasitic capacitance between the bit line and capacitor contact increases due to shrinking feature sizes and longer bit lines, leading to a decrease in the amplified signal, making it difficult to sense and read the signal from the discharged capacitor effectively.
Innovation Solution
A method involving the formation of bit line structures on a semiconductor substrate with trenches, a conformal oxide layer, and a photoresist material layer with higher etch selectivity to create capacitor contact holes, followed by the deposition of a nitride layer, which reduces parasitic capacitance by acting as a dielectric with a lower dielectric constant than oxide, thereby increasing the amplified signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If feature size is shrunk to increase DRAM capacity, then storage density is improved, but parasitic capacitance between bit line and capacitor contact increases
Solution Approach 1:
A nitride layer is introduced as an intermediary material between the bit line and capacitor contact. This nitride layer has a lower dielectric constant than the surrounding oxide materials, thereby reducing the parasitic capacitance (BL-CC capacitance) between the bit line and capacitor contact while allowing continued scaling for higher DRAM capacity.
2Quantity of substance
If bit line length is increased to meet capacity requirements, then storage density is improved, but parasitic capacitance of the bit line increases
Solution Approach 1:
The nitride layer acts as a dielectric intermediary with lower permittivity, reducing the capacitive coupling along the extended bit line length. This allows the bit line to be longer for higher capacity while minimizing the parasitic capacitance accumulation.
3Manufacturing precision
If distance between bit line and capacitor contact is reduced to shrink feature size, then manufacturing precision is improved, but parasitic capacitance increases
Solution Approach 1:
The nitride layer is positioned between the bit line and capacitor contact to provide electrical isolation with reduced capacitive coupling. Its lower dielectric constant compensates for the reduced physical distance, maintaining low parasitic capacitance even as feature sizes shrink and spacing decreases.
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
The solution effectively decreases parasitic capacitance between the bit line and capacitor contacts, enhancing the amplified signal strength and improving the sensing capability of the DRAM device.
Implementation Method 1
deposition of a nitride layer, which reduces parasitic capacitance by acting as a dielectric with a lower dielectric constant than oxide
Data Source
AI summary
A semiconductor device and a method for manufacturing the same are provided. The method includes forming a plurality of bit line structures on a semiconductor substrate, wherein there is a plurality of trenches between the bit line structures. The method also includes forming a first oxide layer conformally covering the bit line structures and the trenches, and forming a photoresist material layer in the trenches and on the first oxide layer, wherein the photoresist material layer has an etch selectivity that is higher than that of the first oxide layer. The method further includes removing the photoresist material layer to form a plurality of capacitor contact holes between the bit line structures, and forming a capacitor contact in the capacitor contact holes.