Electrodeposition Homogenizing Device for Semiconductor Contact Metallization
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Solution Overview
Problem
Existing methods for electrodeposition of metal contact layers on semiconductor components in a wafer assemblage result in inhomogeneous deposition, with greater metal deposition at the edge than at the center of the wafer.
Innovation Solution
The method involves using a non-conductive homogenizing device to restrict access of electroplating liquid and metal ions to the contact areas, ensuring a more uniform deposition by applying a constant or pulsating DC voltage in an electroplating bath with a copper electrode, and using a sealing device for liquid-tight enclosure to prevent deposition on non-contact areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrodeposition is performed on a wafer assemblage without a homogenizing device, then the process is simple and fast, but the metal layer thickness is inhomogeneous with significant variation between edge and center areas
Solution Approach 1:
A non-conductive homogenizing device is introduced as an intermediary element between the electrodeposition system and the wafer. This device includes a homogenizing electrode positioned above the wafer surface that mediates the electric field distribution, ensuring uniform current density across all contact areas regardless of their position on the wafer, thereby achieving homogeneous metal layer thickness
Solution Approach 2:
The homogenizing device creates locally optimized electric field conditions at each contact area on the wafer. By positioning the homogenizing electrode to correspond with each contact area, the system ensures that each local region receives appropriate current density for uniform deposition, addressing the specific problem of edge-vs-center thickness variation
2Manufacturing precision
If electrodeposition is performed without restricting liquid access, then the process is simple, but metal deposits on non-contact areas resulting in inhomogeneous layer formation
Solution Approach 1:
The electroplating bath is segmented into distinct zones: a first region where metal ions are supplied to contact areas, and a second region where non-contact areas are enclosed and isolated. This segmentation prevents metal deposition on non-contact areas while maintaining simple electrodeposition processes
Solution Approach 2:
A sealing device with flexible or conformal sealing elements is used to enclose non-contact areas in a liquid-tight manner. The sealing structure adapts to the wafer surface geometry while preventing electroplating bath contact with non-contact areas, ensuring precise deposition control without complicating the manufacturing process
3Manufacturing precision
If no sealing device is used, then the apparatus is simpler, but electroplating bath contacts non-contact areas causing unwanted metal deposition
Solution Approach 1:
The sealing device acts as an intermediary barrier between the electroplating bath and non-contact areas. It selectively allows bath contact with contact areas while preventing contact with non-contact areas, achieving precise metallization control with minimal added complexity
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 achieves a homogeneous metal layer thickness variation of less than 5% across semiconductor components, with a copper contact layer thickness between 1 μm and 200 μm, ensuring precise and uniform metallization.
Implementation Method 1
applying a voltage, preferably a constant or pulsating DC voltage, to the electrode and to the contact device, as a result of which current flows between the electrode through the electroplating bath and the semiconductor component and the contact device and contact metal is thus deposited at the first contact areas
Data Source
AI summary
Method and apparatus for the electrodeposition of a contact metal layer on contact areas of semiconductor components in a wafer assemblage. The method comprises: a) providing a wafer having components having at least one pn junction; b) arranging a non-conductive homogenizing device with respect to the first surfaces of the components, and an electrical contact device at a second surface of the wafer; c) introducing the wafer into an electroplating bath having an electrode, wherein the surface thereof consists at least partly of a first contact metal, and wherein the first surface of the components is in contact with the electroplating bath; d) applying a voltage to the electrode and to the contact device, as a result of which current flows between the electrode and the contact device, through the electroplating bath and the component and contact metal is thus deposited at the first contact areas of the components.