Multi-Level Etch Reference Feature for Precise Channel Exposure
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Solution Overview
Problem
Current semiconductor manufacturing methods face challenges in achieving precise control over material removal during multi-level etching, particularly for miniature dimension structures and crucial carrier channels, as dry etching can damage surfaces while wet etching lacks dimension control due to its isotropic nature.
Innovation Solution
A method involving a multi-level etch process that combines dry and wet etching operations, utilizing a reference feature to control the etching process, allowing for precise dimension control and reduced surface damage by using a masking layer with specific openings to differentiate between the reference and target features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching operation is used to provide controllable dimension of material removal, then manufacturing precision is improved, but surface damage occurs due to high energy atom/molecular bombardment
Solution Approach 1:
The etching process is divided into multiple sequential steps with different etching chemistries and conditions. The first etching step uses one chemistry to remove material, followed by a second step with different chemistry to complete the etch while protecting the surface. This segmentation allows each step to optimize for its specific function, achieving both dimension control and surface protection.
Solution Approach 2:
The patent changes etching parameters between steps, including gas composition, pressure, power, and temperature. By adjusting these parameters, the etching process transitions from a high-precision removal phase to a surface-healing phase, enabling both precise dimension control and reduced surface damage through parameter optimization at different stages.
2Object-affected harmful factors
If wet etching operation is used to provide milder approach and reduce surface damage, then surface damage is reduced, but dimension control becomes less controllable due to isotropic nature
Solution Approach 1:
The patent segments the wet etching process into multiple steps with different wet etching chemistries. The first wet etching step uses one chemistry for initial material removal, followed by a second wet etching step with different chemistry to achieve precise final dimensions. This segmentation allows each step to contribute differently to the overall etching, combining mild surface treatment with precise dimension control.
Solution Approach 2:
The patent employs composite etching approaches combining different wet etching chemistries in sequence. Each chemistry has different selectivity and etching rates, and by combining them, the process achieves both the mild surface treatment characteristics of wet etching and the precise dimension control needed for miniature structures.
3Productivity
If single-step etching is used to improve productivity, then productivity is improved, but process variation increases for miniature dimension structures
Solution Approach 1:
The etching process is segmented into multiple steps, each optimized for specific requirements. While this increases total process time compared to single-step etching, each step is highly controlled and repeatable, reducing cumulative process variation. The segmentation allows for intermediate measurements and adjustments, improving overall precision for miniature structures.
Solution Approach 2:
The patent incorporates feedback mechanisms between etching steps, where the outcome of one step informs the parameters of the next step. This feedback loop allows real-time adjustment to maintain consistent dimensions across wafers, reducing process variation while maintaining reasonable productivity through efficient step transitions.
Data Source
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AI summary
Present disclosure provides a method for multi-level etch. The method includes providing a substrate, forming a first reference feature over a control region of the substrate, forming an etchable layer over the first reference feature and a target region over the substrate, patterning a masking layer over the etchable layer, the masking layer having a first opening projecting over the control region and a second opening projecting over the target region, and removing a portion of the etchable layer through the first opening and the second opening until the first reference feature is reached. A semiconductor sensing device manufactured by the multi-level etch is also disclosed.