Dry Etch Planarization for Height Uniformity Across Device Regions
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Solution Overview
Problem
The chemical mechanical polishing method used in semiconductor manufacturing often fails to completely eliminate height differences between device regions due to the polishing loading effect, affecting product performance and yield.
Innovation Solution
A planarization method involving a first dry etching process with a higher etching rate for the photoresist layer than the material layer, followed by a second non-selective dry etching process with carbon fluoride, ensuring the top surfaces of the photoresist and material layers are even, thereby achieving uniform height across different device regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If chemical mechanical polishing method is used for planarization, then the process is simple and commonly used, but height differences between different device regions cannot be completely eliminated due to polishing loading effect
Solution Approach 1:
The planarization process is divided into multiple etching steps with different selectivities. The first etching process uses a photoresist layer with higher etching rate to selectively remove material from specific regions, while the second etching process uses a non-selective approach to achieve final planarity. This segmentation allows different regions to be treated differently to compensate for polishing loading effects.
Solution Approach 2:
The photoresist layer is selectively formed only in the first region where additional planarization is needed. This local application of the photoresist layer allows targeted etching to compensate for height differences in specific device regions without affecting other areas, directly addressing the polishing loading effect that creates regional height variations.
2Manufacturing precision
If multiple etching processes with different machines are used to achieve planarity, then height uniformity can be improved, but particle contamination and defects increase
Solution Approach 1:
Multiple etching processes with different selectivities are merged into a single etching machine. The first etching process (with photoresist layer having higher etching rate) and the second etching process (non-selective) are both performed in the same equipment, eliminating wafer transfer between machines and reducing particle contamination while maintaining the ability to achieve precise planarity.
Solution Approach 2:
The etching machine is designed to perform multiple functions by adjusting process parameters. The same equipment can execute both the selective first etching process and the non-selective second etching process, making the system universal and eliminating the need for multiple specialized machines, thereby reducing contamination risks.
3Productivity
If photoresist layer with higher etching rate is used in first etching process, then planarization efficiency is improved, but process complexity increases
Solution Approach 1:
The photoresist layer is formed in advance before the etching processes. This preliminary action prepares the structure for the first etching process, allowing the photoresist to serve as a sacrificial layer with controlled etching rate. The preliminary formation of this layer enables efficient material removal in the first etching step while maintaining process control.
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 height differences between device regions, enhancing product performance and yield by ensuring uniformity and planarity, while also reducing costs by allowing all etching processes to be performed in the same machine, minimizing particle contamination and defects.
Implementation Method 1
A first etching process is performed on the patterned photoresist layer, so that the top surface of the patterned photoresist layer and the top surface of the material layer in the second region have substantially the same height
Implementation Method 2
A second etching process is performed on the patterned photoresist layer and the material layer. In the second etching process, the etching rate of the patterned photoresist layer is substantially the same as the etching rate of the material layer
Data Source
AI summary
A planarization method including the following steps is provided. A substrate is provided. The substrate includes a first region and a second region. A material layer is formed on the substrate. The top surface of the material layer in the first region is lower than the top surface of the material layer in the second region. A patterned photoresist layer is formed on the material layer in the first region. A first etching process is performed on the patterned photoresist layer, so that the top surface of the patterned photoresist layer and the top surface of the material layer in the second region have substantially the same height. A second etching process is performed on the patterned photoresist layer and the material layer. In the second etching process, the etching rate of the patterned photoresist layer is substantially the same as the etching rate of the material layer.