Electroless Plating Flow Layout for Uniform Wafer Film Thickness
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Solution Overview
Problem
Existing electroless plating apparatuses struggle to achieve uniform and high-quality metallic plating on semiconductor wafers due to non-uniform flow of plating liquid, leading to uneven film thickness and adherence of bubbles, which are difficult to prevent with conventional designs.
Innovation Solution
An electroless plating apparatus with a plating bath, reserve tank, and a supply pipe system that ensures uniform plating liquid flow by maintaining consistent intervals between semiconductor wafers and spouts, using adjustable spout angles and conical shapes to minimize bubble adherence and promote uniform film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the plating tank is upsized to reduce flow characteristic influence, then flow uniformity of plating liquid is improved, but equipment cost and apparatus size increase significantly
Solution Approach 1:
The patent divides the plating tank into multiple compartments with partition walls, creating multiple independent plating regions. This segmentation allows uniform plating without requiring a single large tank, thus maintaining flow uniformity while reducing overall apparatus size and cost.
Solution Approach 2:
The patent employs localized flow control structures including specific baffle configurations and air knife positioning in different regions of the plating tank. This local optimization of flow characteristics ensures uniform plating film formation without needing to upscale the entire apparatus.
2Manufacturing precision
If plating liquid is regularly exchanged to maintain film quality, then plating film quality is improved, but environmental load increases due to large amount of impurities in discarded liquid
Solution Approach 1:
The patent implements a liquid circulation and filtration system that recovers and reuses plating liquid. The system includes filters to remove impurities and by-products, allowing the plating liquid to be circulated multiple times rather than discarded after single use, thus reducing environmental load while maintaining film quality.
Solution Approach 2:
The patent establishes continuous circulation of plating liquid through the system with automated filtration and replenishment mechanisms. This continuous operation maintains consistent plating liquid quality without frequent complete exchanges, reducing waste generation while ensuring stable plating film formation.
3Manufacturing precision
If bubbles occur in plating liquid during electroless plating, then bubble adherence to plating surface causes uneven film thickness, but conventional designs cannot prevent this effectively
Solution Approach 1:
The patent converts the harmful effect of gas evolution into a beneficial flow mechanism. Air knives introduce controlled air streams that create upward flow in the plating liquid, which not only removes bubbles from the plating surface but also enhances liquid circulation and uniformity, transforming the gas by-product into a useful flow driver.
Solution Approach 2:
The patent utilizes pneumatic devices (air knives) to generate controlled air flows that interact with the plating liquid. This pneumatic-hydraulic interaction creates vertical circulation patterns that prevent bubble adherence and ensure uniform plating film formation through fluid dynamic control.
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 apparatus achieves uniform and high-quality metallic plating by ensuring consistent liquid flow and minimizing bubble adherence, resulting in films with predictable thickness and improved quality while reducing equipment size and environmental impact.
Implementation Method 1
a circulation pump for supplying the plating liquid of the reserve tank to the plating bath through the supply path
Implementation Method 2
a supply pipe of the plating liquid in which a plurality of spouts to erupt the plating liquid from the reserve tank to the plating bath are formed at regular intervals in an upper part
Implementation Method 3
In formation of the plating film of electroless plating, the plating film is formed by chemical reaction between plating liquid in which plated metallic ion is dissolved and metal (for example, aluminum) on surface of the semiconductor wafer
Data Source
AI summary
An electroless plating apparatus includes: a plating bath; a reserve tank; a retaining means for retaining a plurality of semiconductor wafers upright at regular intervals; a plating liquid circulating path; a circulating pump; a flowmeter and a plating liquid supply pipe having a plurality of spouts formed in an upper part thereof at regular intervals. The regular intervals at which the plurality of semiconductor wafers are retained upright by the retaining means are the same as the regular intervals at which the plurality of spouts are formed in the upper part of the plating liquid supply pipe. The plurality of spouts formed on the upper part of the plating liquid supply pipe may be positioned within the regular intervals between the plurality of semiconductor wafers being retained by the retaining means.