Memory Hole Coating and Etching for High-Aspect-Ratio Diameter Alignment
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Solution Overview
Problem
In semiconductor memory cells, the aspect ratio of memory holes is increasing, leading to difficulties in aligning the diameter of the upper and lower portions, resulting in uneven etching and electrical characteristic dispersion due to poor penetration of etching liquids, especially in recesses with high aspect ratios.
Innovation Solution
A semiconductor device forming method involving the formation of a coating layer on the front surface of recesses, followed by selective etching with a chemical liquid to widen the diameter of the deep portion, using a partially packed bed and a water-repellent agent to control the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the aspect ratio of memory holes is increased to stack more memory cells, then the storage capacity is improved, but the etching liquid penetration becomes poor and diameter alignment between upper and lower portions deteriorates
Solution Approach 1:
A coating layer is formed on the front surface of the recess before the etching process. This preliminary action modifies the surface properties to control etching liquid distribution, ensuring that the etching liquid can properly reach and etch the deep portions of high aspect ratio recesses, thereby maintaining diameter alignment even as aspect ratio increases for higher storage capacity
Solution Approach 2:
The coating layer is applied selectively to the front surface region of the recess, creating a localized modification that affects etching liquid distribution. This local quality change allows the front surface to control liquid penetration into the deep recess, solving the diameter alignment problem without affecting the overall high aspect ratio structure needed for storage capacity
2Productivity
If the aspect ratio of recesses is increased for three-dimensional device structures, then the device integration density is improved, but the etching liquid distribution becomes uneven
Solution Approach 1:
The coating layer acts as an intermediary between the etching liquid and the recess surface. It mediates the interaction by controlling how the etching liquid distributes itself within the high aspect ratio recess, ensuring stable and uniform liquid distribution even when the recess geometry creates challenging access conditions for maintaining composition stability
3Device complexity
If conventional etching is used on high aspect ratio recesses, then the process simplicity is maintained, but the electrical characteristic dispersion increases
Solution Approach 1:
The coating layer formation is a preliminary step added before conventional etching. This preliminary action prepares the surface to ensure uniform etching throughout the high aspect ratio recess, preventing electrical characteristic dispersion while maintaining the simplicity of the overall etching process by using standard etching chemistry and equipment
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 allows for uniform adjustment of recess diameters in stacked structures, ensuring consistent electrical characteristics across memory cells by improving the penetration and distribution of etching liquids.
Implementation Method 1
forming a coating layer that selectively covers a portion of a recess provided in a stacked structure supported by a base member... the forming the coating layer includes supplying a water-repellent agent
Implementation Method 2
etching a deep portion, which is deeper than the coating layer, of the recess with a chemical liquid so as to widen a diameter of the deep portion of the recess
Data Source
AI summary
A semiconductor device forming method that includes a step for forming a coating layer and a step for performing etching. In the step for forming a coating layer, the coating layer is formed. The coating layer selectively covers a portion of a recess provided in a stacked structure supported by a base member. The portion of the recess is located on a front surface side of the recess. In the step for performing etching, a deep portion, which is deeper than the coating layer, of the recess is etched with a chemical liquid so as to widen a diameter of the deep portion.