Multilayer Stair Insulation to Prevent NAND Substrate Warping
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Solution Overview
Problem
Warping of a semiconductor substrate occurs due to the difference in linear expansion coefficients between the insulator layer covering the stair part and the semiconductor substrate in semiconductor devices like NAND flash memory.
Innovation Solution
A semiconductor device configuration that includes a stacking part with stacked conductor layers, a stair part with conductor layers extended in a stair shape, a first insulating film covering the stair part, a second insulating film with a larger linear expansion coefficient covering the first insulating film, and a contact penetrating through both insulating films to connect with the conductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single insulator layer is used to cover the stair part, then the device structure is simple, but warping occurs due to mismatch in linear expansion coefficients between the insulator and semiconductor substrate
Solution Approach 1:
The patent applies composite materials by forming a first insulating film made of oxide silicon and a second insulating film made of oxide silicon containing carbon. These two different insulating materials are stacked to create a composite insulator structure that balances thermal expansion stresses, preventing substrate warping while maintaining device reliability.
Solution Approach 2:
The patent changes the material parameters of the insulating films by selecting oxide silicon for the first film and oxide silicon containing carbon for the second film. This parameter change in composition allows adjustment of linear expansion coefficients to match and balance thermal expansion between layers, eliminating warping issues.
2Reliability
If multiple insulating films with different materials are stacked, then warping is prevented by balancing thermal expansion, but the device structure becomes more complex
Solution Approach 1:
The patent modifies material parameters by incorporating carbon into oxide silicon for the second insulating film. This compositional parameter change adjusts the linear expansion coefficient to balance thermal stresses, preventing warping while keeping the structural complexity manageable through a straightforward two-layer stack.
3Reliability
If the linear expansion coefficient of the insulator layer is made larger to match the substrate, then thermal stress is balanced, but the insulator material selection becomes more restricted
Solution Approach 1:
The patent uses composite materials strategy by combining oxide silicon with carbon-containing oxide silicon in a stacked configuration. This approach provides flexibility in material selection, as each layer can be independently optimized for specific properties while collectively achieving thermal expansion matching, thus maintaining adaptability.
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 configuration effectively prevents warping of the semiconductor substrate by balancing the thermal expansion stresses between the insulating films and the substrate, ensuring stable device performance.
Implementation Method 1
warping potentially occurs to a semiconductor substrate due to the difference between the linear expansion coefficient of the insulator layer covering the stair part and the linear expansion coefficient of the semiconductor substrate
Data Source
AI summary
A semiconductor device includes: a stacking part in which the plurality of conductor layers are separately stacked in a z direction; a stair part that is arranged alongside the stacking part in a y direction and in which the plurality of conductor layers are extended in the y direction in a stair shape; a first insulating film covering at least part of the stair part; a second insulating film covering at least part of the first insulating film and different from the first insulating film; and a contact connected with one of the plurality of conductor layers and penetrating through the first insulating film and the second insulating film. The linear expansion coefficient of the second insulating film is larger than the linear expansion coefficient of the first insulating film.