Surface-Inhibited ALD for Void-Free Dielectric Gap Fill
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Solution Overview
Problem
Existing semiconductor device fabrication processes face challenges in depositing high-quality dielectric films in gaps, often resulting in voids and seams due to difficulties in achieving uniform deposition across narrow and high-aspect-ratio features.
Innovation Solution
The use of atomic layer deposition (ALD) processes with a reaction inhibitor, such as nitrogen trifluoride (NF3), is introduced during the plasma operation to inhibit deposition at the top of the gap, allowing for void-free bottom-up gap fill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition processes are used to deposit dielectric films in gaps, then deposition can proceed uniformly across the substrate, but voids and seams form in the films due to difficulty in achieving uniform deposition in narrow and high-aspect-ratio features
Solution Approach 1:
The patent applies local quality by introducing a reaction inhibitor that selectively affects different regions of the gap. The inhibitor is introduced at the top opening of the gap and diffuses downward, creating a concentration gradient where the top region experiences inhibition while the bottom region remains active for deposition. This local differentiation enables void-free bottom-up gap fill while maintaining overall film quality.
Solution Approach 2:
The reaction inhibitor is introduced before the deposition process begins and during the deposition process, creating a preliminary protective effect at the top of the gap. This preliminary anti-action prevents excessive deposition at the top region that would otherwise create voids and seams, allowing the deposition to proceed uniformly from the bottom up.
2Ease of manufacture
If deposition is allowed to proceed uniformly throughout the gap, then the deposition process is simple, but voids and seams form due to inability to control deposition distribution in high-aspect-ratio features
Solution Approach 1:
The reaction inhibitor acts as an intermediary substance that mediates between the deposition process and the gap geometry. By introducing this intermediary, the patent achieves controlled deposition distribution in high-aspect-ratio features without significantly complicating the overall deposition process. The inhibitor naturally diffuses and distributes itself according to the gap geometry, providing automatic adaptation.
Solution Approach 2:
The patent changes the chemical environment parameter by introducing the reaction inhibitor, which alters the deposition rate locally. This parameter change enables control over deposition uniformity in high-aspect-ratio features while maintaining a relatively simple deposition process using standard ALD or CVD equipment.
3Reliability
If a reaction inhibitor is introduced during plasma operation to inhibit deposition at the top of the gap, then void-free bottom-up gap fill is achieved, but the process complexity increases
Solution Approach 1:
The reaction inhibitor serves multiple functions simultaneously: it inhibits deposition at the top of the gap, prevents void and seam formation, and enables bottom-up gap fill. By using a single substance with multiple functions, the patent achieves reliable void-free deposition without proportionally increasing process complexity.
Solution Approach 2:
The reaction inhibitor is introduced in advance and during the deposition process to pre-establish the conditions for void-free gap fill. This preliminary action prevents the formation of defects before they occur, rather than requiring complex post-processing or monitoring systems to detect and correct issues.
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 enables effective void-free bottom-up gap fill, mitigating seam formation and preventing voids by selectively inhibiting deposition at the top of the gap while allowing deposition to proceed unimpeded at the bottom, resulting in a more favorable sloped profile.
Implementation Method 1
exposing the substrate to a co-reactant plasma to drive a reaction between the first reactant and the co-reactant to form a film in the gap
Implementation Method 2
exposing the substrate to a reaction inhibitor during at least part of (c)... the reaction inhibitor selectively inhibits deposition of the film at the top of the gap
Data Source
AI summary
Atomic layer deposition (ALD) of dielectric material in gaps that facilitates void-free bottom-up gap fill can involve flowing a reaction inhibitor during the ALD process. In some embodiments, the reaction inhibitor is flowed during at least part of a plasma operation of a plasma-enhanced ALD (PEALD) process.