TSV Copper Migration Prevention via Segmented Barrier Films
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Solution Overview
Problem
The migration of copper ions during the fabrication of Through Silicon Via (TSV) in semiconductor devices leads to electrical characteristic deterioration and potential cracks in bit line contacts, due to stress and absorption in active regions of the semiconductor substrate.
Innovation Solution
A semiconductor device and method that includes a TSV with an oxide film and prevention films, where the prevention films are formed with materials having lower etch selectivity than the oxide film, covering the upper surface and sidewalls of the TSV, and a metal barrier film is used to prevent copper diffusion, with specific etching and deposition processes to create a sloped step configuration that enhances structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If TSV is exposed by repeated heat treatment during fabrication, then manufacturing process is simplified, but copper ions migrate and gather in active regions causing electrical characteristic deterioration
Solution Approach 1:
A prevention film made of copper-free material is introduced as an intermediary layer between the copper-filled TSV and the semiconductor substrate. This mediator prevents direct contact and migration pathways between copper ions and the active region, allowing heat treatment to proceed without causing copper migration into sensitive areas.
Solution Approach 2:
The TSV structure is segmented into distinct functional layers: the copper-filled via, a copper-free prevention film layer, and the oxide film layer. This segmentation isolates the copper material from direct exposure to heat treatment effects that would cause migration, while maintaining the electrical connection function.
2Ease of manufacture
If Cu ions migrate through oxide films, then TSV formation is achieved, but cracks occur in bit line contact deposited over active region
Solution Approach 1:
The prevention film acts as a physical barrier and intermediary layer that blocks copper ion migration pathways through the oxide film to the bit line contact. This prevents the accumulation of copper ions that would cause stress and cracking in the deposited bit line contact structure.
Solution Approach 2:
The prevention film is formed before depositing the bit line contact, preliminarily establishing a protective barrier that prevents copper migration before the contact is deposited. This preliminary protective action ensures the integrity of subsequently deposited layers.
3Reliability
If prevention films with lower etch selectivity than oxide film are used, then TSV isolation is improved, but etching process complexity increases
Solution Approach 1:
Different regions of the TSV structure have different etch selectivity requirements. The prevention film has lower etch selectivity for superior isolation, while the oxide film maintains higher etch selectivity for controlled processing. This local differentiation of properties optimizes both isolation performance and processability.
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
Prevents copper migration and reduces the risk of cracks, thereby improving the electrical characteristics and production yield of semiconductor devices by effectively isolating the TSV from the semiconductor substrate.
Implementation Method 1
an oxide film located over a lower sidewall of the TSV
Implementation Method 2
a first prevention film formed to cover an upper surface of the TSV, an upper portion of a sidewall of the TSV, and an upper surface of the oxide film
Data Source
AI summary
A semiconductor device and a method for fabricating the same are disclosed, which can prevent migration of copper (Cu) ion when forming a Through Silicon Via (TSV). The semiconductor device includes a through silicon via (TSV) formed to pass through a semiconductor substrate; an oxide film located at a lower sidewall of the TSV; and a first prevention film formed to cover an upper portion of the TSV, an upper sidewall of the TSV, and an upper surface of the oxide film.