Optical Plating Sensor for Wafer Holder Deposit Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor fabrication is the unwanted metal deposits on substrate holders during electroplating, which lead to manufacturing defects, low yields, and increased costs due to the scavenging of current from the wafer, causing non-uniform plating and thinner features.
Innovation Solution
An electroplating apparatus with a plating sensor and drip shield that detects the presence or absence of unwanted metal deposits on the substrate holder using a light source and sensor, allowing for timely detection and cleaning, and includes a dryer to prepare the sensor target area for accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electroplating is performed to deposit materials on semiconductor devices, then material deposition is achieved, but unwanted metal deposits form on the substrate holder
Solution Approach 1:
The patent extracts the detection function from the electroplating process by introducing a separate optical sensor system that monitors the substrate holder surface independently from the plating process, allowing unwanted deposits to be detected and removed without interfering with material deposition
Solution Approach 2:
The patent introduces an optical sensor as an intermediary between the electroplating process and the substrate holder, using light reflection properties to indirectly detect metal deposits without direct contact with the plating process or electrolyte
2Reliability
If substrate holder is not monitored, then manufacturing defects occur, but implementing detection system increases device complexity
Solution Approach 1:
The patent replaces complex mechanical inspection systems with a simpler optical sensing system that uses light sources and photodetectors to detect metal deposits based on changes in light reflection, reducing mechanical complexity while maintaining detection reliability
Solution Approach 2:
The substrate holder itself serves as part of the detection system by providing the surface whose optical properties change when deposits form, eliminating the need for separate reference standards or complex calibration systems
3Measurement precision
If manual inspection is used to detect metal deposits, then detection capability is limited, but automated detection increases manufacturing time
Solution Approach 1:
The patent enables continuous detection during the electroplating process by positioning optical sensors to monitor the substrate holder in real-time as it rotates or moves through the plating bath, eliminating idle inspection time and maintaining continuous manufacturing flow
Solution Approach 2:
The system performs preliminary detection of metal deposits before they reach critical levels that would cause manufacturing defects, allowing proactive cleaning or process adjustment that prevents rework and maintains production efficiency
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 solution enables immediate detection and removal of unwanted metal deposits, preventing manufacturing defects and ensuring uniform plating, thereby improving yield and reducing costs by maintaining the quality of semiconductor wafers.
Implementation Method 1
a plating sensor including a light source aimed at the sensor target area, where the plating sensor distinguishes between (i) areas on the sensor target area where unwanted metal deposits are present and (ii) areas on the sensor target area where unwanted metal deposits are absent
Data Source
AI summary
Methods and apparatus for detecting the presence or absence of unwanted metal deposits on a substrate holder of an electroplating apparatus are described herein. In various embodiments, a plating sensor is used to detect unwanted metal deposits. The plating sensor may be mounted relatively far away from the area that it measures (e.g., the sensor target area). For instance, the plating sensor may be on one side of the electroplating apparatus (in some cases mounted on a drip shield), and the sensor target area may be on the opposite side of the electroplating apparatus. In this way, the plating sensor can measure across the electroplating apparatus. This placement provides a relatively deep depth of focus for the plating sensor, and provides some physical separation between the plating sensor and the electroplating chemistry. Both of these factors lead to more reliable detection results.