Flow-Shaping Element for Electroplating Uniformity
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Solution Overview
Problem
Radial non-uniformity of electrodeposited metal thickness on semiconductor wafers during electroplating due to varying fluidic environments at the center and edge portions of rotating substrates, caused by turbulent electrolyte flow and terminal effects.
Innovation Solution
An electroplating apparatus with a flow-shaping element featuring spatially segregated channels, where a majority of channels are not perpendicular to the substrate's plating face, particularly in the central region, to mitigate radial non-uniformity by controlling electrolyte flow and reducing the terminal effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If channels in the flow-shaping element are perpendicular to the plating face, then electrolyte transport is simplified, but radial non-uniformity of metal thickness increases due to turbulent flow at edges and shorter exposure time
Solution Approach 1:
The flow-shaping element is divided into multiple zones with different channel orientations. The first zone contains channels at a first angle (e.g., more perpendicular) while the second zone contains channels at a second angle (e.g., less perpendicular), allowing each zone to address specific flow characteristics in different radial regions of the substrate
Solution Approach 2:
Different regions of the flow-shaping element are assigned different channel angles optimized for their specific location. Edge regions use channels with angles that reduce turbulence, while center regions use channels that maximize exposure time, creating locally optimized flow conditions throughout the plating surface
2Productivity
If the substrate rotates at high speed, then productivity increases, but radial non-uniformity worsens due to reduced electrolyte exposure time at channel locations
Solution Approach 1:
The system dynamically balances substrate rotation speed with electrolyte flow characteristics. By optimizing channel angles and flow rates, the system maintains effective electrolyte-substrate interaction even at high rotation speeds, allowing productivity improvement without sacrificing uniformity
Solution Approach 2:
The channel angles are specifically designed to modify electrolyte flow parameters (velocity, direction, exposure time) to compensate for the reduced interaction time caused by high-speed substrate rotation, maintaining plating uniformity across the radial direction
3Manufacturing precision
If electrolyte flow rate is increased, then plating uniformity improves, but turbulence at edge regions increases causing radial non-uniformity
Solution Approach 1:
The flow-shaping element implements location-specific channel configurations where edge regions use channels angled to reduce turbulence while center regions use channels optimized for maximum flow delivery. This allows high overall flow rates while maintaining laminar flow characteristics at turbulence-prone edge locations
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
Significantly improves radial uniformity of electroplated metal thickness across the wafer substrate, reducing thickness variation to less than 5% and achieving uniformity in high-speed electroplating processes.
Implementation Method 1
The plate introduces an additional resistance into the plating cell which leads to reduction of terminal effect
Implementation Method 2
the channels allow for transport of the electrolyte through the flow-shaping element during electroplating from the opposing surface to the substrate-facing surface
Implementation Method 3
a plating chamber configured to contain an electrolyte and an anode while electroplating metal onto a substantially planar substrate
Data Source
AI summary
The uniformity of electroplating a metal (e.g., copper) on a semiconductor wafer is improved by using an electroplating apparatus having a flow-shaping element positioned in the proximity of the semiconductor wafer, wherein the flow-shaping element is made of a resistive material and has two types of non-communicating channels made through the resistive material, such that the electrolyte is transported towards the substrate through both types of channels. The first type of channels is not perpendicular to the plane defined by a plating face of the substrate. The second type of channels is perpendicular to the plane defined by the plating face of the substrate. The channels of the first and second type are substantially spatially segregated. In one embodiment a plurality of channels of the first type are located in the central portion of the flow-shaping element and are surrounded by a plurality of channels of the second type.