Ashable Hardmask Gap Fill for Multiple Patterning
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Solution Overview
Problem
Current double patterning technologies in semiconductor processing face inefficiencies due to the need for multiple masking steps, unstable masks, and inability to effectively form high aspect ratio features, particularly in line patterning, which increases costs and reduces throughput.
Innovation Solution
The method involves using ashable hardmasks (AHMs) deposited by a deposition-etch-ash process to eliminate steps in the double patterning process, enabling the formation of robust, durable masks for both single and two-dimensional patterning, and reducing etch steps, thereby improving efficiency and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional double patterning methods using spacers and masks are used, then patterning beyond optical limits is achieved, but the masks are poor, unstable and weak, unable to provide effective formation of high aspect ratio features
Solution Approach 1:
The patent changes the material parameters of the mask from conventional photoresist-based masks to ashable hardmask materials deposited by CVD or PECVD. This material parameter change provides masks with superior mechanical strength, stability, and ability to withstand high aspect ratio feature formation while maintaining patterning precision
Solution Approach 2:
The patent employs composite material structures including conformal dielectric layers over patterned AHM, and gap-fill AHM layers over conformal films. These composite structures provide both the stability needed for high aspect ratio features and the pattern fidelity required for precise patterning
2Manufacturing precision
If multiple masking steps are used in double patterning, then patterning beyond optical limits is achieved, but the number of process operations increases, reducing efficiency and throughput
Solution Approach 1:
The patent merges multiple masking operations into a single AHM-based patterning step. The AHM layer serves as both the pattern transfer mask and the etch mask, eliminating the need for separate spacer deposition and multiple mask steps, thereby improving throughput while maintaining patterning precision
Solution Approach 2:
The ashable hardmask layer performs multiple functions: it acts as the pattern definition layer, the etch protection mask, and the template for subsequent gap-fill operations. This multi-functionality reduces the total number of process steps while achieving the same patterning results
3Strength
If conformal film is deposited over patterned AHM, then mask robustness is improved, but additional etch steps are required to remove the conformal film, increasing process complexity
Solution Approach 1:
The patent changes the etch process parameters by using selective chemistry that targets the conformal dielectric material while preserving the AHM layer. This selective etching approach simplifies the overall process by removing the need for additional mask formation steps
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 results in stable, free-standing masks that can withstand high aspect ratios and are selectively etchable, enhancing patterning efficiency and reducing costs by eliminating unnecessary masking steps and improving mask robustness.
Implementation Method 1
The substrate is planarized by flowing oxygen (O2) and helium (He) at about 20 sccm and about 200 sccm, respectively, for about 30 seconds. The substrate may also undergo a two-step plasma etch process by flowing CF4 and Ar at about 5 sccm and about 100 sccm, respectively, for 10 seconds, and flowing CHF3 and CF4 at about 15 sccm and about 80 sccm, respectively, for 30 seconds.
Implementation Method 2
Subsequently, the substrate may be exposed to aqueous hydrofluoric acid solution including 1000 parts deionized (DI) water to 1 part anhydrous HF by volume, for about 30 seconds.
Implementation Method 3
the gap-fill AHM layer is deposited by (a) flowing a hydrocarbon using plasma enhanced chemical vapor deposition until a gap entry width between features in the pattern is reduced
Data Source
AI summary
Methods and apparatuses for multiple patterning using image reversal are provided. The methods may include depositing gap-fill ashable hardmasks using a deposition-etch-ash method to fill gaps in a pattern of a semiconductor substrate and eliminating spacer etching steps using a single-etch planarization method. Such methods may be performed for double patterning, multiple patterning, and two dimensional patterning techniques in semiconductor fabrication.