Semiconductor Contact Hole Structure for Barrier Metal Thickness
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Solution Overview
Problem
Existing semiconductor devices face issues such as short-circuit failures and increased manufacturing costs due to the formation of contact holes that penetrate through conductive films, leading to insufficient barrier metal film thickness and gaps in the contact holes, which affect the reliability and electrical connectivity of power devices like IGBTs.
Innovation Solution
The solution involves forming a semiconductor device with a specific structure where the bottom of the contact hole is positioned within an insulating layer, ensuring a longer distance from the conductive film's lower surface to the hole's bottom, allowing for sufficient growth of the barrier metal film and conductive plug, thereby enhancing adhesion and reducing contact resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact hole is formed deeper to ensure sufficient barrier metal film thickness, then the reliability is improved, but the manufacturing precision deteriorates due to difficulty in controlling the etching depth
Solution Approach 1:
The patent introduces an intermediary layer (e.g., silicon nitride film or silicon oxynitride film) between the interlayer insulating film and the conductive film. This intermediary layer acts as a mediator that provides both etching selectivity for precise depth control and sufficient thickness to prevent substrate penetration, thereby resolving the contradiction between reliability and manufacturing precision.
2Manufacturing precision
If the contact hole is formed shallower to improve manufacturing precision, then the etching depth control is improved, but the reliability deteriorates due to insufficient barrier metal film thickness
Solution Approach 1:
The intermediary layer serves as a mediator that enables shallower etching while maintaining reliability. By providing etching selectivity, the intermediary layer allows precise control of the contact hole depth, and its sufficient thickness prevents the contact hole from penetrating through to the substrate, thus resolving the contradiction between manufacturing precision and reliability.
3Ease of manufacture
If the conductive film thickness is reduced to minimize step differences, then the ease of manufacture is improved, but the reliability deteriorates due to increased risk of contact hole penetration
Solution Approach 1:
The intermediary layer acts as a protective mediator between the conductive film and the contact hole. Even when the conductive film is made thinner to reduce step differences and improve planarization, the intermediary layer provides an additional safety margin that prevents contact hole penetration to the substrate, thereby resolving the contradiction between ease of manufacture and reliability.
4Reliability
If the contact hole is formed deeper to ensure adequate barrier metal film, then the electrical connectivity is improved, but the manufacturing complexity increases due to additional process steps
Solution Approach 1:
The intermediary layer enables adequate barrier metal film formation without requiring excessively deep contact holes. By providing etching selectivity, the intermediary layer allows the contact hole to be formed to an optimal depth that ensures sufficient barrier metal thickness while avoiding unnecessary depth that would increase manufacturing complexity, thus resolving the contradiction between reliability and device complexity.
Data Source
AI summary
A semiconductor device includes an insulating layer (IFL) on a semiconductor substrate (SUB), a conductive film (PL) on the insulating layer (IFL), an interlayer insulating film (IL) covering the conductive film (PL), a contact hole (CH1) in the interlayer insulating film (IL), the conductive film (PL) and the insulating layer (IFL), and a plug (PG1) embedded in the contact hole (CH1). A side surface of the interlayer insulating film (IL) is separated from a side surface of the conductive film (PL) to expose a part of an upper surface of the conductive film (PL), and a side surface of the insulating layer (IFL) is separated from the side surface of the conductive film (PL) to expose a part of a lower surface of the conductive film (PL). A distance (L1) from the lower surface of the conductive film (PL) to the bottom of the contact hole (CH1) is longer than a distance (L2) from the side surface of the conductive film (PL) to the side surface of the interlayer insulating film (IL).