Structural Member Blocks HF Acid Intrusion in Semiconductor Fabrication
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Solution Overview
Problem
In semiconductor device fabrication, the use of hydrofluoric acid for etching can cause separation between the silicon oxide film and structural members, leading to reduced yield and product lifespan due to hydrofluoric acid intrusion along their interface.
Innovation Solution
A method involving the formation of a silicon oxide film with opening portions and a structural member less prone to etching by hydrofluoric acid, which extends onto the silicon substrate, blocking the acid's intrusion and preventing separation during wet etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a structural member is provided on a silicon oxide film, then the structural member protects the silicon oxide film surface, but hydrofluoric acid intrudes along the interface between the silicon oxide film and the structural member, causing separation
Solution Approach 1:
The patent applies preliminary action by forming opening portions in the silicon oxide film before providing the structural member. This allows the structural member to extend down to the silicon substrate, creating a configuration where the interface between the silicon oxide film and structural member is exposed and does not form a closed pathway for hydrofluoric acid intrusion, thereby preventing separation before it can occur
Solution Approach 2:
The patent applies segmentation by dividing the silicon oxide film into regions with opening portions. This segmentation creates discontinuities in the interface between the silicon oxide film and structural member, blocking the continuous pathway that would otherwise allow hydrofluoric acid to intrude and cause separation
2Reliability
If the structural member reaches the silicon substrate in the opening portion, then unevenness is provided in the surface and hydrofluoric acid intrusion is blocked, but the fabrication process becomes more complex
Solution Approach 1:
The opening portions are formed in the silicon oxide film before the structural member is deposited. This preliminary action simplifies the overall process by eliminating the need for subsequent steps to create similar openings in the structural member, reducing fabrication complexity while achieving the reliability benefit
Solution Approach 2:
The structural member serves multiple functions: it protects the silicon oxide film surface, provides mechanical support, and blocks hydrofluoric acid intrusion by extending to the silicon substrate through the opening portions. This multi-functionality reduces the need for additional separate structures or processes
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 suppresses the separation of structural members from the silicon oxide film, enhancing the fabrication process by maintaining structural integrity and reducing defects.
Implementation Method 1
Wet etching using hydrofluoric acid is performed, on the silicon substrate on which the silicon oxide film and the structural member have been provided
Data Source
AI summary
A silicon oxide film having at least one opening portion is formed, on a silicon substrate. A structural member formed of a material less prone to be etched by hydrofluoric acid than a silicon oxide film is formed, wherein the structural member is provided on the silicon oxide film and reaches the silicon substrate in the opening portion. Wet etching using hydrofluoric acid is performed, on the silicon substrate on which the silicon oxide film and the structural member are provided. The interface between the silicon oxide film and the structural member is exposed to hydrofluoric acid, in performing the wet etching.