Via Hole Depth Detector Using Dual Wavelength Laser Detection
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Solution Overview
Problem
The challenge in semiconductor manufacturing is accurately detecting the depth of via holes in semiconductor wafers, as existing methods struggle to ensure that laser beam processing reaches the electrodes on the front surface without damaging them, leading to inefficiencies in productivity due to incomplete holes.
Innovation Solution
A via hole depth detector system utilizing dual detection laser beams with different wavelengths, combined with a synthetic beam splitter and focal point positioning, allows for precise detection of the top and bottom surfaces of the holes by calculating the ratio of light received by specific light receiving devices, enabling accurate determination of hole depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser beam processing is used to form via holes, then productivity is improved, but measurement precision of hole depth deteriorates
Solution Approach 1:
The patent introduces light receiving devices as intermediary components that detect reflected light from the via hole bottom surface. These devices act as mediators between the laser processing system and the depth measurement function, enabling indirect detection of hole depth through optical reflection characteristics without interfering with the laser processing productivity.
Solution Approach 2:
The patent replaces mechanical depth measurement methods with optical detection using light receiving devices. By substituting mechanical contact measurement with non-contact optical detection, the system maintains high productivity while achieving precise depth measurement through light reflection analysis from the via hole bottom surface.
2Object-affected harmful factors
If laser beam application is stopped early, then electrode damage is prevented, but via hole depth completeness deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where light receiving devices continuously monitor the reflection characteristics from the via hole bottom surface during laser processing. This real-time feedback information is used to determine when the via hole has reached the appropriate depth, enabling precise control of laser application to prevent both electrode damage and incomplete hole formation.
Solution Approach 2:
The patent employs preliminary detection of via hole depth characteristics before completing the laser processing. By detecting reflection patterns early in the process, the system can determine when to stop laser application, preventing both over-processing (electrode damage) and under-processing (incomplete holes) through advance knowledge of depth status.
3Device complexity
If single wavelength laser detection is used, then device complexity is reduced, but measurement precision of surface position deteriorates
Solution Approach 1:
The patent segments the detection function by using multiple light receiving devices that detect different characteristics of reflected light. Each device measures specific aspects of the optical field, and their combined measurements provide comprehensive surface position information, achieving high precision without requiring a single complex detection system.
Solution Approach 2:
The patent makes the light receiving devices multi-functional by enabling them to detect various parameters including surface position, via hole depth, and bottom surface characteristics using the same hardware components. This universal detection capability reduces overall device complexity while maintaining high measurement precision across multiple parameters.
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 efficiently detects the depth of via holes, allowing for re-processing of incomplete holes and improving productivity by ensuring accurate formation of holes reaching the electrodes, thus enhancing the semiconductor wafer manufacturing process.
Implementation Method 1
detects the height position of an illuminated portion of the workpiece based on the reflected light of the first detection laser beam
Data Source
AI summary
A via hole depth detector for detecting the depth of a via hole formed in a workpiece held on a chuck table, comprising: a first surface position detection means which comprises a first detection laser beam oscillation means for oscillating a first detection laser beam having a predetermined wavelength and detects the height position of an illuminated portion of the workpiece based on the reflected light of the first detection laser beam; a second surface position detection means which comprises a second detection laser beam oscillation means for oscillating a second detection laser beam having a wavelength different from the wavelength of the first detection laser beam and detects the height position of an illuminated portion of the workpiece based on the reflected light of the second detection laser beam; and a control means for obtaining the depth of the via hole formed in the workpiece based on a detection value obtained by the first surface position detection means and a detection value obtained by the second surface position detection means.