Semiconductor Hard Mask Removal via Wet Etch
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Solution Overview
Problem
In semiconductor memory devices, increasing the height of capacitor columns to enhance capacitance leads to increased hard mask material thickness, resulting in loss of semiconductor support structure pillar materials during dry etching, particularly the nitride lattice, which compromises the structural integrity and efficiency of the memory device.
Innovation Solution
A method involving a wet etch process is used to remove the silicon liner material and hard mask material, with the remaining hard mask material serving as protection for the nitride lattice, reducing liner and pillar loss, and eliminating the need for additional buffer material, thereby maintaining the stability of the semiconductor support structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of capacitor columns is increased to enhance capacitance, then the storage capacitance is improved, but the thickness of hard mask material increases causing loss of nitride lattice during dry etching
Solution Approach 1:
A silicon liner material is introduced as an intermediary layer between the hard mask material and the nitride lattice. During the wet etch process, the silicon liner is selectively removed while the hard mask remains as a protective intermediary, preventing direct contact and potential damage to the nitride lattice. This mediator approach allows for the removal of excessive hard mask material without compromising the underlying nitride structure.
Solution Approach 2:
The patent changes the etching parameters by switching from a dry etch process to a wet etch process for removing the silicon liner material. This parameter change enables selective removal of the silicon liner while preserving the nitride lattice, as the wet etch chemistry is specifically tailored to etch silicon at a different rate than nitride. This parameter transformation resolves the material loss issue.
2Productivity
If dry etch is used to remove hard mask material and silicon liner, then the etching process is efficient, but loss of semiconductor support structure pillar materials occurs
Solution Approach 1:
The patent changes the etching parameter from dry etch to wet etch for the silicon liner removal step. This parameter transformation maintains etching efficiency while improving selectivity and reducing collateral damage to the nitride lattice. The wet etch process parameters are optimized to achieve comparable productivity with enhanced structural preservation.
Solution Approach 2:
The silicon liner material serves as a beforehand cushioning layer that is deliberately placed between the hard mask and the nitride lattice. During the wet etch process, this cushioning layer is selectively removed, having already served its protective function. This prior cushioning approach prevents direct exposure and potential damage to the nitride lattice during the etching process.
3Reliability
If additional buffer material is deposited to account for etch loss, then the structural integrity is maintained, but the device complexity increases
Solution Approach 1:
The patent extracts and removes the silicon liner material through selective wet etching, eliminating the need for additional buffer material deposits. By taking out the problematic silicon liner that causes etch loss, the process simplifies the overall fabrication sequence. This extraction approach maintains structural integrity without adding the complexity of buffer material deposition and subsequent removal steps.
Solution Approach 2:
The silicon liner material is deliberately discarded through selective wet etching, as it serves its protective function and then becomes a sacrificial element. By discarding this temporary protective layer, the process avoids the need for complex buffer material management. The liner is recovered in the sense that its removal precisely defines the final structure without requiring additional compensatory materials.
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 reduces liner loss and maintains the nitride lattice, enhancing the structural integrity and capacitance of the semiconductor support structure, allowing for increased capacitor height and improved storage capacitance without sacrificing material stability.
Implementation Method 1
A method involving a wet etch process is used to remove the silicon liner material and hard mask material
Data Source
AI summary
Methods, apparatuses, and systems related to removing a hard mask are described. An example method includes patterning a silicon hard mask on a semiconductor structure having a first silicate material on a working surface. The method further includes forming a first nitride material on the first silicate material. The method further includes forming a second silicate material on the first nitride material. The method further includes forming a second nitride material on the second silicate material. The method further includes an opening through the semiconductor structure using the patterned hard mask to form a pillar support. The method further includes forming a silicon liner material on the semiconductor structure. The method further includes removing the silicon liner material using a wet etch process.