Bonded Wafer Interface Detection Using Vertical Radiation Scanning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During semiconductor fabrication, the thinning process of bonded wafers can cause damage due to applied forces, particularly at the gaps along the perimeter of the wafer interface, leading to peeling or damage of dielectric layers, as existing methods for determining the seal path are inaccurate due to the quality of beveled edges and captured images.
Innovation Solution
A method using a radiation source and sensor to determine the position of the interface between bonded workpieces by scanning electromagnetic radiation along a vertical axis and measuring intensity, allowing for accurate determination of the interface position independent of edge quality or image clarity, thereby improving the accuracy of seal formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional image-based methods are used to determine the seal path, then the process is simple to implement, but the measurement precision is poor due to beveled edge quality and image clarity issues
Solution Approach 1:
The patent replaces traditional mechanical/image-based measurement systems with a radiation-based detection system. Instead of using cameras to capture images of beveled edges, the system uses a radiation source to emit radiation and a sensor to detect radiation intensity variations, thereby determining the interface position between bonded wafers with higher precision.
Solution Approach 2:
The patent introduces radiation as an intermediary medium to detect the interface position. The radiation source emits radiation that passes through or reflects off the wafer interface, and the sensor detects intensity variations caused by the interface, allowing precise determination of the seal path without direct mechanical contact or image capture of difficult-to-visualize edges.
2Reliability
If the seal path is determined inaccurately, then the device complexity remains low, but the reliability of the wafer bond deteriorates due to damage during thinning process
Solution Approach 1:
The patent implements a feedback mechanism where the radiation sensor continuously measures radiation intensity at different positions, and the system adjusts the determined seal path based on these measurements. The maximum radiation intensity point identifies the precise interface location, ensuring accurate seal placement that maintains wafer bond reliability during subsequent thinning processes.
3Measurement precision
If radiation scanning is used to determine interface position, then the measurement precision improves, but the use of energy increases due to radiation source operation
Solution Approach 1:
The patent applies partial action by scanning radiation only along the necessary vertical axis at the wafer perimeter rather than performing comprehensive full-wafer scanning. The radiation source emits radiation selectively at positions where interface determination is needed, reducing overall energy consumption while maintaining measurement precision.
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 reduces errors in seal path determination, enhancing the structural integrity of the wafer bond and minimizing damage during the thinning process by accurately positioning the seal along the wafer perimeter.
Implementation Method 1
generating electromagnetic radiation that is directed toward a perimeter of the pair of bonded workpieces and toward a radiation sensor that is arranged behind the perimeter of the pair of bonded workpieces
Data Source
AI summary
The present disclosure relates to a method and an associated process tool. The method includes generating electromagnetic radiation that is directed toward a perimeter of a pair of bonded workpieces and toward a radiation sensor that is arranged behind the perimeter of the pair of bonded workpieces. The electromagnetic radiation is scanned along a vertical axis. An intensity of the electromagnetic radiation that impinges on the radiation sensor is measured throughout the scanning. Measuring the intensity includes recording a plurality of intensity values of the electromagnetic radiation at a plurality of different positions along the vertical axis extending past top and bottom surfaces of the pair of bonded workpieces. A position of an interface between the pair of bonded workpieces is determined based on a maximum measured intensity value of the plurality of intensity values.