Carbon-Doped Silicon Nitride Etch Stop for Staircase Contact Depth Control
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Solution Overview
Problem
Conventional vertical memory arrays face challenges in forming electrical connections to both shallower and deeper conductive structures without overetching, particularly due to the presence of voids or grain boundaries, which increases processing complexity and cost.
Innovation Solution
The use of a carbon-doped silicon nitride etch stop material allows for the formation of contacts at different depths within the semiconductor device structure, preventing overetching by resisting etch chemistries and enabling precise control over opening depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an etch process is conducted to form openings down to the deeper conductive structures, then electrical connections to deeper conductive structures are achieved, but the openings to shallower conductive structures are overetched (punch through) into the conductive structures
Solution Approach 1:
An etch stop layer is introduced as an intermediary material between the conductive structures and the openings. This etch stop layer is selectively etched by the etch chemistry used to form openings to deeper conductive structures, allowing precise depth control. The etch stop layer acts as a mediator that enables the etch process to stop at the desired depth without punching through the shallower conductive structures, thus resolving the contradiction between achieving deep connections and preventing overetching.
2Manufacturing precision
If multiple masks are used to form openings with different depths, then punch through of shallower conductive structures is prevented, but additional processing acts, complexity, and cost are added to the overall process
Solution Approach 1:
The etch stop layer is extracted as a separate, dedicated functional layer specifically for depth control during opening formation. By extracting this depth-control function into a dedicated layer rather than relying on multiple masks, the process complexity is reduced while maintaining precise opening depth control. The etch stop layer can be formed once and then used to control depths for multiple openings, eliminating the need for repeated masking steps.
3Quantity of substance
If the number of tiers in the semiconductor devices increases and the conductive structures become thinner, then memory density is increased, but the likelihood of punch through increases and multiple masks are required
Solution Approach 1:
As memory density increases and conductive structures become thinner, the etch stop layer serves as a critical intermediary that provides a robust depth reference for opening formation. The etch stop layer compensates for the reduced thickness margins by providing a clearly defined etch termination point, enabling precise depth control even when working with thinner conductive structures in high-density configurations.
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 effectively reduces the likelihood of punch-through into conductive structures, simplifies the etching process, and decreases processing complexity and costs, while maintaining precise control over contact formation.
Implementation Method 1
The use of a carbon-doped silicon nitride etch stop material allows for the formation of contacts at different depths within the semiconductor device structure, preventing overetching by resisting etch chemistries
Data Source
AI summary
A semiconductor device structure that comprises tiers of alternating dielectric levels and conductive levels and a carbon-doped silicon nitride over the tiers of the staircase structure. The carbon-doped silicon nitride excludes silicon carbon nitride. A method of forming the semiconductor device structure comprises forming stairs in a staircase structure comprising alternating dielectric levels and conductive levels. A carbon-doped silicon nitride is formed over the stairs, an oxide material is formed over the carbon-doped silicon nitride, and openings are formed in the oxide material. The openings extend to the carbon-doped silicon nitride. The carbon-doped silicon nitride is removed to extend the openings into the conductive levels of the staircase structure. Additional methods are disclosed.