Wafer Laser Processing Inert Atmosphere Phosphorus Diffusion
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Solution Overview
Problem
Laser processing of wafers with phosphorus compound substrates and metal electrodes generates foreign matter due to elemental diffusion, which reacts with air components and degrades device characteristics, making it difficult to remove simultaneously with the protective film.
Innovation Solution
A wafer processing method involving the formation of a water-soluble protective film, followed by laser irradiation, and subsequent application of a chemical with an amino group to suppress foreign matter generation, specifically by reacting with diffused phosphorus to form a water-soluble compound that can be easily removed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser processing is performed on a wafer with phosphorus compound substrate and metal electrodes, then the wafer can be divided into devices, but foreign matter is generated due to elemental diffusion and reaction with air components
Solution Approach 1:
An inert gas atmosphere (nitrogen or carbon dioxide) is introduced as an intermediary environment during laser processing to prevent the reaction between diffused phosphorus elements and air components (oxygen, nitrogen, water vapor). This mediator eliminates the harmful chemical reaction that generates foreign matter on metal electrodes, while allowing the laser processing to proceed effectively.
Solution Approach 2:
The patent creates an inert atmosphere by filling the processing chamber with nitrogen or carbon dioxide gas before and during laser processing. This inert environment prevents oxidation and reaction of the diffused phosphorus with air components, thereby suppressing foreign matter generation on the metal electrodes while maintaining high productivity in wafer division.
2Manufacturing precision
If a protective film is applied and cleaned after laser processing, then debris can be removed, but foreign matter generated during processing cannot be effectively removed
Solution Approach 1:
The inert gas atmosphere is introduced before laser processing begins and maintained throughout the entire processing duration. This preliminary action prevents foreign matter formation at the source, eliminating the need for subsequent removal steps and ensuring device characteristics are maintained without compromising surface cleanliness.
3Ease of operation
If the protective film is cleaned immediately after laser processing, then debris can be removed, but the cleaning process cannot remove foreign matter with low generation rate
Solution Approach 1:
The patent converts the potentially harmful reaction between phosphorus and air into a beneficial outcome by using the inert gas atmosphere to suppress the reaction entirely. This prevents foreign matter formation, transforming what would be a cleaning challenge into a prevention solution, thereby improving both ease of operation and reducing harmful factors.
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
Effectively reduces foreign matter generation on the wafer surface, particularly on metal electrodes, thereby maintaining device characteristics and simplifying the removal process.
Implementation Method 1
a chemical having an amino group to the wafer, and a removing step of cleaning and removing a compound that is generated on the wafer by the supplying of the chemical and contains phosphorus
Implementation Method 2
forming a water-soluble protective film on a surface of the wafer
Implementation Method 3
laser processing of irradiating the wafer with a laser beam along the streets on the wafer to form grooves in the wafer surface
Implementation Method 4
an element (for example phosphorus) configuring the wafer is liberated and diffused due to the laser processing
Data Source
AI summary
Disclosed herein is a wafer processing method in which laser processing is carried out on a wafer along streets. The wafer processing method includes a step of holding the wafer by a chuck table, a protective film forming step of forming a water-soluble protective film on a surface of the wafer, a laser beam irradiating step of irradiating the wafer with a laser beam along the streets after the protective film forming step, a step of supplying a chemical having an amino group to the wafer, and a removing step of cleaning and removing a compound that is generated by the supplying of the chemical having an amino group and contains phosphorus.