Multi-Layer Hard Mask Etching for Critical Dimension Bias Recovery
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Solution Overview
Problem
In the manufacturing of integrated circuits, the critical dimension of patterns in photoresist layers is affected by various factors, leading to significant changes in electrical performance due to aberrations caused by photo tools, especially as device sizes decrease, resulting in dramatic shifts in critical dimensions during the pattern transfer process.
Innovation Solution
A method involving the use of multiple hard mask layers with different critical dimensions and etching selectivity ratios to maintain uniformity in pattern transfer, where the second hard mask layer is patterned and used to etch the first hard mask layer, ensuring the critical dimensions are substantially equal across regions, with an etching process power of about 1000 W and selectivity ratio greater than 15, and the ability to recover small shifts in critical dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the critical dimension of the device is decreased to improve device integration, then device density increases, but the aberration caused by photo tools strongly affects the appearance of the critical dimension leading to dramatic changes in electrical performance
Solution Approach 1:
The patent divides the single mask layer into multiple mask layers (first hard mask layer and second hard mask layer) with different etching selectivity ratios. This segmentation allows each layer to be patterned independently, enabling compensation for critical dimension variations through the etching process, thus resolving the contradiction between high device integration and critical dimension accuracy.
Solution Approach 2:
The patent changes the etching parameters by using multiple mask layers with different etching selectivity ratios (where the ratio of etching rate of second hard mask layer to first hard mask layer is greater than 15). This parameter change enables automatic recovery of critical dimension bias shifts during the etching process, maintaining manufacturing precision even as device critical dimensions decrease.
2Device complexity
If a single hard mask layer is used to simplify the process, then process complexity is reduced, but the critical dimension bias shift cannot be automatically recovered during pattern transfer
Solution Approach 1:
The patent segments the mask structure into multiple layers (first hard mask layer and second hard mask layer) with different etching selectivity characteristics. This segmentation enables the etching process to automatically compensate for critical dimension bias shifts, achieving uniform critical dimensions across different regions without requiring complex additional process steps.
Solution Approach 2:
The multi-layer hard mask structure enables self-service during the etching process. The different etching selectivity ratios cause the pattern to self-adjust and automatically recover critical dimension bias shifts during etching, eliminating the need for external intervention or complex process control to maintain critical dimension uniformity.
3Manufacturing precision
If the etching selectivity ratio of the second hard mask layer to the first hard mask layer is increased to improve pattern transfer accuracy, then the process window increases, but the process parameters become more difficult to control
Solution Approach 1:
The patent changes the etching process parameters by establishing a specific etching selectivity ratio relationship between the two hard mask layers (ratio greater than 15). This parameter change creates a process window that automatically recovers critical dimension bias shifts, improving pattern transfer accuracy while the selectivity ratio itself serves as a controllable parameter that guides the etching process.
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 recovers critical dimension bias shifts and increases the process window for pattern transfer, ensuring uniformity and accuracy of pattern dimensions, even with shifts as small as 10 nm or less than 10% of the original, by maintaining high etching selectivity and power during the process.
Implementation Method 1
an etching process is performed to pattern the first hard mask layer by using the patterned second hard mask layer as a mask
Data Source
AI summary
The invention is directed to a method for patterning a material layer. The method comprises steps of providing a material layer having a first hard mask layer and a second hard mask layer successively formed thereon and then patterning the second hard mask layer. Thereafter, an etching process is performed to pattern the first hard mask layer by using the patterned second hard mask layer as a mask, and the etching process is performed with a power of about 1000 W. Next, the material layer is patterned by using the patterned first hard mask layer as a mask.