Semiconductor Contact Structure With Inclined Layer for Stable Au Plating
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Solution Overview
Problem
In semiconductor devices, the shape of the contact portion is not stabilized due to interruptions in coating caused by perpendicular inner walls and upper surfaces of insulating films, leading to etching of the contact layer during Au plating.
Innovation Solution
A shape stabilization layer with an inclined surface is formed on the contact layer in the peripheral portion of the opening, ensuring complete coverage by the underlying metal, preventing plating solution ingress and etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inner wall of the opening and the upper surface of the contact layer are made perpendicular to each other, then the manufacturing process is simplified, but the coating is interrupted in the peripheral portion causing clearance and instability of contact portion shape
Solution Approach 1:
The invention replaces the perpendicular (90-degree) corner configuration with an inclined surface having a specific angle range (45-60 degrees). This curvature modification eliminates the sharp corner where coating interruption occurs, allowing the underlying metal to form a continuous coating over the contact layer peripheral portion without interruption, thereby preventing clearance formation while maintaining manufacturing feasibility.
Solution Approach 2:
The invention introduces a shape stabilization layer as an additional functional layer composed of specific materials (InP, InGaAs, or InAlAs) that are selectively etched. This composite structure serves multiple functions: it provides a template for forming the inclined surface, ensures proper coverage by the underlying metal, and prevents plating solution ingress, thereby solving the coating continuity issue while maintaining processability.
2Device complexity
If a perpendicular configuration is used, then the structure is simpler, but plating solution enters through clearance and etches the contact layer causing shape instability
Solution Approach 1:
By modifying the geometric configuration from perpendicular to inclined (45-60 degrees), the invention eliminates the clearance pathway that allows plating solution ingress. The inclined surface ensures continuous coverage by the underlying metal, preventing direct contact between the plating solution and the contact layer, thus maintaining contact portion shape stability without significantly increasing structural complexity.
Solution Approach 2:
The shape stabilization layer acts as an intermediary barrier between the plating solution and the contact layer. This intermediate layer, formed with specific material composition, prevents direct interaction between the corrosive plating solution and the contact layer, thereby protecting the contact layer from etching while maintaining overall structural simplicity.
3Quantity of substance
If the underlying metal coating is interrupted, then material usage is reduced, but the contact layer becomes etched by plating solution leading to unstable contact portion shape
Solution Approach 1:
The inclined surface configuration (45-60 degrees) optimizes the coverage area of the underlying metal by eliminating the clearance zone present in perpendicular configurations. This geometric modification ensures continuous coating without interruption, providing complete protection against plating solution ingress while maintaining efficient material usage through precise angular control.
Solution Approach 2:
The invention changes the critical geometric parameter from a 90-degree perpendicular angle to an inclined angle range of 45-60 degrees. This parameter modification fundamentally alters the coating behavior, ensuring continuous coverage by the underlying metal and preventing clearance formation, thereby maintaining both material efficiency and contact portion shape stability.
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
The solution stabilizes the shape of the contact portion by ensuring uninterrupted coating and preventing etching during Au plating, resulting in a semiconductor device with improved contact layer integrity.
Implementation Method 1
A coverage of the underlying metal is improved by the inclined surface. Thus, a coating is not interrupted in the peripheral portion of the opening of the insulating film.
Implementation Method 2
A plating solution enters the insulating film from the clearance when an Au plating is formed, and the contact layer is etched in the peripheral portion of the opening.
Data Source
AI summary
An insulating film (10) having an opening (11) is formed on a contact layer (7). A shape stabilization layer (8) having an inclined surface (9) is formed on the contact layer (7) in a peripheral portion of the opening (11). An underlying metal (12) covers an upper surface of the contact layer (7) exposed through the opening (11) and the inclined surface (9). A plating (13) is formed on the underlying metal (12).