DRAM Capacitor Mold Segmentation for CMP Stability
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Solution Overview
Problem
Current methods for forming semiconductor devices, particularly DRAM cell capacitors, face challenges in reliably and stably creating scaled-down components with effective chemical mechanical polishing (CMP) processes, leading to issues with protrusion removal and electrode formation.
Innovation Solution
A method involving the formation of a mold structure with multiple layers and support layers, followed by masking and etching to create conductive patterns with protrusions, which are then removed using CMP to achieve planarization and expose the upper support layer, ensuring stable electrode formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CMP processes are used to form scaled-down cell capacitors, then manufacturing simplicity is maintained, but reliability and stability of electrode formation deteriorate due to protrusion removal issues
Solution Approach 1:
The mold structure is divided into multiple distinct layers: a first mold layer, a first support layer, a second mold layer, and a second support layer. Each layer serves specific functions in the electrode formation process, allowing for controlled etching and support during CMP operations to improve reliability without excessive overall complexity.
Solution Approach 2:
The support layers are formed in advance before the actual electrode formation CMP process. These pre-formed support layers provide structural support during the CMP operation, preventing protrusion removal issues and ensuring stable electrode formation before the final polishing step occurs.
2Manufacturing precision
If mask layer thickness is reduced to enable proper etching, then etching precision is improved, but mask layer stability deteriorates making protrusion removal difficult
Solution Approach 1:
The mask layer is segmented into different thickness regions: a first mask portion with a first thickness and a second mask portion with a second thickness greater than the first. This allows the thinner first mask portion to provide precise etching control where needed, while the thicker second mask portion maintains stability and prevents premature removal during CMP operations.
Solution Approach 2:
Different portions of the mask layer are given different thicknesses based on their specific functional requirements. The first mask portion has reduced thickness for precise etching in specific areas, while the second mask portion maintains greater thickness for structural stability and controlled removal timing during the CMP process.
3Reliability
If conductive patterns are formed to fill holes and mask openings, then electrode connectivity is improved, but protrusion formation occurs requiring additional CMP steps
Solution Approach 1:
The support layers are formed in advance to provide structural support before the conductive material is deposited and before the CMP process occurs. This preliminary support structure prevents excessive protrusion formation during CMP, making the protrusion removal step easier and more controlled while maintaining good electrode connectivity.
Solution Approach 2:
The first and second support layers act as cushioning structures formed beforehand to protect against excessive protrusion formation during the CMP process. These support layers absorb some of the polishing action, reducing the severity of protrusions that form on the conductive patterns and making subsequent protrusion removal easier and more uniform.
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 approach enables reliable and stable formation of DRAM cell capacitors with improved reliability and capacitance by ensuring the conductive patterns are properly planarized and supported, preventing defects like leaning or collapsing.
Implementation Method 1
A chemical mechanical polishing process is performed to remove the protrusions of the conductive patterns
Data Source
AI summary
A method of forming a semiconductor device includes forming a mold structure on a substrate, forming a first mask layer having a deposition thickness on the mold structure and patterning the first mask layer to form first mask openings which expose the mold structure. The mold structure is etched to form holes that penetrate the mold structure. The first mask layer is thinned to form mask portions having thickness smaller than the deposition thickness. Conductive patterns are formed to fill the holes and the first mask openings. The first mask layer including the mask portions is etched to expose the mold structure. The conductive patterns include protrusions. A chemical mechanical polishing process is performed to remove the protrusions of the conductive patterns.