Composite Bit Line Spacer Structure for Low-Capacitance Deposition
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Solution Overview
Problem
The challenge in semiconductor manufacturing is achieving uniform deposition of low-K spacers on different substrate surfaces while maintaining distance between metal features, leading to issues like parasitic capacitance and current leakage.
Innovation Solution
A method involving the formation of multiple spacer layers, including insulating nitride and SiCO layers, with a plasma oxidation process to modify the SiCO layer, ensuring uniform thickness and adherence, thereby reducing parasitic capacitance and current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low-K spacer materials are used to reduce parasitic capacitance between metal features, then the dielectric constant is reduced, but processing problems increase preventing further improvement
Solution Approach 1:
The patent uses a composite spacer structure consisting of multiple layers with different materials and dielectric constants. The first spacer layer has a first dielectric constant, the second spacer layer has a second dielectric constant different from the first, creating a composite structure that optimizes both electrical performance and processability. This composite approach allows tuning of overall dielectric properties while maintaining manufacturing feasibility.
Solution Approach 2:
Different portions of the spacer structure have different material compositions and dielectric constants tailored to specific locations. The first and second spacer layers are positioned at different locations relative to the bit line structure, with each layer having optimized properties for its specific function. This local differentiation allows reduction of parasitic capacitance in critical areas while maintaining ease of manufacture in other regions.
2Manufacturing precision
If uniform deposition of spacer material is achieved on different substrate surfaces, then deposition uniformity is improved, but maintaining distance between metal features becomes difficult
Solution Approach 1:
The spacer structure is segmented into multiple discrete layers (first spacer layer, second spacer layer) rather than using a single continuous material layer. Each layer can be deposited with controlled thickness and material properties, allowing uniform deposition on different substrate surfaces while the combined structure maintains the required distance between metal features. The segmentation enables independent optimization of each layer's deposition parameters.
Solution Approach 2:
The patent transitions from a single-dimensional spacer thickness control to a multi-dimensional approach by stacking multiple spacer layers vertically. Each layer contributes to the overall spacer height and lateral extent, providing additional degrees of freedom for controlling the distance between metal features. This vertical stacking allows uniform deposition on inclined or complex substrate surfaces while maintaining precise lateral spacing.
3Loss of time
If multiple spacer layers with different dielectric constants are used to reduce parasitic capacitance, then RC time delays are reduced, but device complexity increases
Solution Approach 1:
The patent extracts and separates the spacer function into distinct layers with different material properties rather than using a single homogeneous spacer material. The first spacer layer and second spacer layer are formed as separate entities with different dielectric constants, allowing each layer to be optimized for specific electrical performance requirements. This extraction of functionality reduces RC time delays by creating low-capacitance regions where needed.
Solution Approach 2:
The patent changes the dielectric constant parameter across different spacer layers to optimize electrical performance. The first spacer layer has a first dielectric constant and the second spacer layer has a second dielectric constant, creating a gradient or stepped structure that reduces parasitic capacitance and RC time delays. This parameter variation is implemented in a controlled manner that manages device complexity through systematic material selection and layer configuration.
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 method maintains spacer layer uniformity and reduces parasitic capacitance, improving semiconductor performance by minimizing RC time delays and current leakage.
Implementation Method 1
An oxidation process is performed on the second spacer layer, thereby forming an oxidized portion and a remaining portion in the second spacer layer
Implementation Method 2
the oxidation process is a plasma oxidation process. the plasma oxidation process includes O2 and H2N2 plasma oxidation process
Data Source
AI summary
A method of manufacturing a semiconductor structure includes the following steps. A bit line structure is formed over a substrate. A first spacer layer is formed on a first sidewall of the bit line structure. A second spacer layer is formed on a second sidewall of the first spacer layer. A third spacer layer is formed on a third sidewall of the second spacer layer. An oxidation process is performed on the second spacer layer, thereby forming an oxidized portion and a remaining portion in the second spacer layer, in which the oxidized portion is between the remaining portion and the third spacer layer. A fourth spacer layer is formed on a fourth sidewall of the third spacer layer.