Phase Change Memory Bit Line Self-Alignment
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Solution Overview
Problem
The manufacturing process of phase change memory devices is complex due to the separate formation of phase change material layer patterns, upper electrodes, and bit lines, making correct alignment difficult and increasing the risk of errors.
Innovation Solution
A method is developed to simplify the manufacturing process by forming a phase change material layer that is self-aligned with the bit line, involving the creation of insulating interlayers, contacts, and etch back processes to form the phase change material layer pattern and bit line simultaneously, reducing the complexity and improving alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the phase change material layer pattern, upper electrode and bit line are formed separately, then each component can be optimized independently, but the manufacturing process becomes complicated and alignment accuracy deteriorates
Solution Approach 1:
The patent merges the formation of the phase change material layer pattern and the bit line into a single simultaneous patterning process. By forming both structures from the same material layer using the same photolithography and etching steps, the invention eliminates the need for separate formation processes, thereby simplifying the manufacturing process while ensuring perfect alignment between the phase change material layer pattern and the bit line.
Solution Approach 2:
The phase change material layer serves dual functions: it becomes both the phase change material layer pattern (after selective removal) and the source material for forming the bit line. This self-service approach where the same material layer provides both functional components eliminates the need for separate material deposition and formation steps, reducing process complexity while maintaining alignment accuracy.
2Productivity
If separate formation processes are used for phase change material layer pattern and bit line, then process flexibility is maintained, but manufacturing time and error risk increase
Solution Approach 1:
The invention combines the formation of the phase change material layer pattern and the bit line into a single integrated process sequence. Both structures are patterned and formed simultaneously using the same photolithography mask and etching process, which eliminates cumulative alignment errors that would occur with separate processes and reduces the total number of manufacturing steps, thereby improving both productivity and reliability.
Data Source
AI summary
A method of manufacturing a phase change memory device includes forming a lower electrode in a cell region of a substrate and a transistor in a peripheral circuit region of the substrate. A first insulating interlayer is formed on the substrate and covers the lower electrode and the transistor. A first contact is formed to penetrate through the first insulating interlayer to connect with the transistor. A second insulating interlayer is formed on the first insulating interlayer and the first contact. A first opening and a second opening are formed by partially removing the first and second insulating interlayers. A phase change material layer pattern is formed to partially fill the first opening. A bit line is formed to fill a remaining portion of the first opening, and a wiring is formed to fill the second opening. Accordingly, the manufacturing process may be simplified.