Semiconductor Air Gap Formation via Nitride Protection
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Solution Overview
Problem
Conventional methods for forming air gaps in semiconductor devices, such as DRAM devices, often result in undesirable electrical coupling and reduced feature reliability due to etching of conductive materials, leading to electrical shorts and compromised performance.
Innovation Solution
A method involving the formation of semiconductive device structures with laterally alternating semiconductive pillars and digit lines, nitride caps, low-K dielectric material, and oxide dielectric material, followed by selective etching to create air gaps between digit lines, while using nitride dielectric materials to protect conductive features and maintain structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional etching methods are used to form air gaps, then air gaps can be created to reduce capacitive coupling, but conductive material is attacked and deposited in air gaps causing electrical shorts
Solution Approach 1:
A protective coating layer is applied to the conductive material before air gap formation. This intermediary layer prevents the etching chemistry from attacking the conductive material while allowing the air gap to be formed adjacent to it. The protective coating acts as a mediator that enables the air gap formation process without causing the harmful side effect of conductive material degradation and deposition.
Solution Approach 2:
The protective coating is applied in advance before the air gap etching process. This preliminary protective action prevents the harmful etching effect from occurring on the conductive material. By applying the protection beforehand, the method eliminates the risk of conductive material being attacked and deposited in the air gaps, thereby preventing electrical shorts while still allowing capacitive coupling reduction.
2Productivity
If feature dimensions are reduced to increase density, then integration level increases, but manufacturing precision requirements increase
Solution Approach 1:
The method changes the physical and chemical parameters of the etching process by using a protective coating on the conductive material. This parameter change allows for more precise control of the etching front, enabling the formation of air gaps with well-defined dimensions even at reduced feature sizes. The protective coating modifies the etching parameters to prevent unwanted material removal and deposition, thereby maintaining manufacturing precision while enabling higher feature density.
3Productivity
If spacing between digit lines is reduced to increase density, then integration level increases, but electrical coupling effects increase
Solution Approach 1:
The method extracts the dielectric material between adjacent digit lines to form air gaps. By removing the solid dielectric material and replacing it with air (or vacuum), the dielectric constant is reduced, which directly reduces the capacitive coupling between closely spaced digit lines. This extraction of material enables higher density interconnect structures while minimizing the harmful electrical coupling effects that would otherwise occur at reduced spacing.
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 enhances the reliability and performance of semiconductor devices by reducing capacitive coupling and preventing electrical shorts, while maintaining the integrity of conductive features and air gaps, thereby improving feature density and device durability.
Implementation Method 1
conventional processes of forming such air gaps can undesirably attack (e.g., etch) the conductive material (e.g., metal) of other features
Data Source
AI summary
A semiconductor device comprises semiconductive pillars; digit lines laterally between the semiconductive pillars; nitride caps vertically overlying the digit lines; nitride structures overlying surfaces of the nitride caps; redistribution material structures comprising upper portions overlying upper surfaces of the nitride caps and the nitride structures, and lower portions overlying upper surfaces of the semiconductive pillars; a low-K dielectric material laterally between the digit lines and the semiconductive pillars; air gaps laterally between the low-K dielectric material and the semiconductive pillars, and having upper boundaries below the upper surfaces of the nitride caps; and a nitride dielectric material laterally between the air gaps and the semiconductive pillars. Memory devices, electronic systems, and method of forming a semiconductor device are also described.