Variable Speed Substrate Rotation for Electroless Plating Film Uniformity
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Solution Overview
Problem
Conventional batch-type processing apparatuses for electroless plating on semiconductor wafers face challenges in improving the reaction rate of the plating liquid, leading to longer processing times and uneven film formation due to limitations in substrate movement and film forming control.
Innovation Solution
A plating method and apparatus that involves a liquid displacement process, an incubation process, and a plating film growing process, where the substrate is rotated at different speeds to optimize the supply and growth of the plating film, with the first rotational speed being higher than the third, and the third higher than the second, to enhance the reaction rate and stability of the plating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate is not moved or moved only slightly in the batch-type processing apparatus, then the structure is simple, but the reaction rate of the plating liquid cannot be improved
Solution Approach 1:
The substrate is rotated at different rotational speeds during different stages of the plating process. The rotation speed is dynamically adjusted: first rotational speed during liquid displacement, second rotational speed during incubation, and third rotational speed during plating film growing. This dynamic adjustment improves the reaction rate while maintaining processability.
2Productivity
If the substrate is rotated at high speed throughout the plating process, then the reaction rate is improved, but the plating film uniformity deteriorates
Solution Approach 1:
The rotation speed is dynamically adjusted according to the plating stage: high first rotational speed for liquid displacement to ensure uniform distribution, lower second rotational speed for incubation to allow initial film formation, and optimized third rotational speed for plating film growing to maintain uniformity while improving reaction rate.
Solution Approach 2:
The plating process is divided into distinct periodic stages with different rotation speeds: liquid displacement process, incubation process, and plating film growing process. Each stage uses appropriate rotation speed to achieve its specific objective, ensuring both uniformity and reaction rate.
3Productivity
If conventional batch-type processing is used, then the apparatus structure is simple, but the plating time is long
Solution Approach 1:
The substrate rotation is implemented with variable speeds across different plating stages, transforming the static batch processing into a dynamic process that accelerates the reaction rate and reduces plating time while maintaining single-wafer processing simplicity.
Solution Approach 2:
The rotational speed parameter is changed across different process stages (first, second, and third rotational speeds), optimizing the plating reaction rate at each stage and reducing overall plating time without requiring complex multi-wafer processing equipment.
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 accelerates the stable growth of the plating film and reduces the plating time for a single substrate by effectively displacing and replenishing the plating liquid, improving the uniformity and efficiency of the electroless plating process.
Implementation Method 1
In the electroless plating process, in order to form a plating film by incurring an oxidation-reduction reaction in the vicinity of a surface of a wafer
Implementation Method 2
a liquid displacement process of performing a liquid displacement by supplying the plating liquid onto the substrate while rotating the substrate
Data Source
AI summary
A liquid displacement is performed by supplying a plating liquid onto a substrate 2 while rotating the substrate 2 at a first rotational speed in a state that a pre-treatment liquid remains on a surface of the substrate 2 (liquid displacement process (block S305)). Then, an initial film is formed on the substrate 2 by stopping the rotation of the substrate 2 or by rotating the substrate 2 at a second rotational speed while continuously supplying the plating liquid onto the substrate 2 (incubation process (block S306)). Thereafter, a plating film is grown by rotating the substrate 2 at a third rotational speed while continuously supplying the plating liquid onto the substrate 2 (plating film growing process (block S307)). Here, the first rotational speed is higher than the third rotational speed, and the third rotational speed is higher than the second rotational speed.