Bit Line Contact Patterning With Dual-Tone Development
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Solution Overview
Problem
The existing lithography-etch-lithography-etch (LELE) approach for forming trenches in DRAM structures can deform the first pattern and damage the target layer, leading to reduced pattern correctness and adverse effects on subsequent manufacturing processes due to direct contact with etchants or chemical solvents.
Innovation Solution
A dual-tone development method involving a first exposure and developing process using a positive-tone developer, followed by a second exposure and developing process using a negative-tone developer, with complementary masks to form a target pattern, which is then used for etching to create trenches, reducing the number of steps and maintaining pattern correctness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the LELE approach is used to form trenches, then the pattern complexity can be increased, but the first pattern may be deformed and the target layer may be damaged due to direct contact with etchants or chemical solvents
Solution Approach 1:
The patent introduces an intermediary protective layer between the first pattern and the etchant/chemical solvent. This protective layer prevents direct contact, thereby preventing deformation of the first pattern and damage to the target layer while still allowing the complex patterning to be achieved through the LELE approach
2Manufacturing precision
If the LELE approach is used to form trenches, then more precise patterning can be achieved, but the number of process steps increases and the manufacturing complexity increases
Solution Approach 1:
The patent combines multiple functions into fewer process steps. By introducing the protective layer and optimizing the sequence of operations, the patent achieves precise patterning while reducing the overall number of process steps compared to the traditional LELE approach
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
This method effectively reduces the steps required for trench formation, prevents pattern deformation, and maintains pattern correctness by using a dual-tone development approach with complementary masks, enhancing the precision and reliability of the manufacturing process.
Implementation Method 1
performing a first exposure process to expose the photosensitive layer to actinic radiation through a first mask; performing a second exposure process to expose the intermediate pattern to the actinic radiation through a second mask
Data Source
AI summary
The present application provides a method of fabricating bit line contacts. The method includes steps of depositing an insulative layer and a sacrificial layer on the substrate; forming a photosensitive layer on the sacrificial layer; performing a first exposure process to expose the photosensitive layer to actinic radiation through a first mask; performing a first developing process to form an intermediate pattern on the sacrificial layer; performing a second exposure process to expose the intermediate pattern to the actinic radiation through a second mask; performing a second developing process to form a target pattern on the sacrificial layer; performing a first etching process to remove portions of the sacrificial layer exposed by the target pattern; performing a second etching process to form a plurality of trenches in the insulative layer; and depositing a conductive material into the plurality of trenches to form the bit line contacts.