Wafer Separation Using Pulsed Laser Ablation
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Solution Overview
Problem
Semiconductor devices with wafer thicknesses less than or equal to 100 μm are prone to damage during separation due to vibration on adhesive films when cut by high-speed cutting blades.
Innovation Solution
A manufacturing method involving the use of a pulsed laser beam to separate the wafer and adhesive film along crossing separation lines, eliminating the need for a cutting blade and minimizing contact with the devices, and expanding the dicing tape to increase spacing and facilitate device pickup with the adhesive film intact on the lower surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cutting blade is used to separate the wafer along separation lines, then the wafer can be separated into individual devices, but the devices may be damaged by vibration and impact when the wafer thickness is less than or equal to 100 μm
Solution Approach 1:
The patent replaces the mechanical cutting blade system with a laser processing system. The laser beam processes the wafer along the separation lines without physical contact, eliminating the vibration and impact problems that occur with mechanical blades when processing thin wafers (thickness ≤ 100 μm). This substitution maintains separation efficiency while significantly improving device integrity.
Solution Approach 2:
The patent introduces an adhesive film as an intermediary layer between the wafer and the support surface. This film allows the wafer to be firmly supported during laser processing, preventing vibration and movement, while enabling clean separation after processing. The intermediary layer solves the contradiction by providing stability during processing without causing damage to the thin devices.
2Length of moving object
If the wafer thickness is reduced to less than or equal to 100 μm, then the devices become more compact and suitable for modern electronics, but the devices become more susceptible to damage during separation
Solution Approach 1:
The patent replaces mechanical cutting with laser processing to handle thin wafers (thickness ≤ 100 μm). The laser beam provides contactless processing that does not transmit vibration or impact forces to the fragile thin devices, enabling safe separation of compact devices that would be too vulnerable to mechanical cutting methods.
Solution Approach 2:
The patent applies an adhesive film beforehand to the support surface before placing the thin wafer. This film provides cushioning and vibration damping during the laser processing of thin wafers, protecting the fragile devices from damage while allowing precise laser cutting along the separation lines.
3Ease of manufacture
If an adhesive film is mounted on the lower surface of each device, then the devices can be bonded to a die bonding frame, but the adhesive film may interfere with the separation process when using a cutting blade
Solution Approach 1:
The patent replaces mechanical blade cutting with laser processing to separate wafers that have adhesive films mounted on their lower surfaces. The laser beam can cleanly separate the wafer along the separation lines without disturbing the adhesive film, as the laser energy is focused on the wafer material itself rather than requiring mechanical force that would disrupt the bonded devices.
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 method prevents device damage by avoiding high-speed blade contact and allows for reliable separation and pickup of devices with wafer thicknesses as low as 100 μm without vibration or damage.
Implementation Method 1
a pulsed laser beam having an absorption wavelength is applied to the wafer along the separation lines of the wafer after mounting the adhesive film to the dicing tape, thereby separating the wafer into the individual devices and cutting the adhesive film
Implementation Method 2
an adhesive film for die bonding is mounted on the lower surface of each device
Data Source
AI summary
A manufacturing method for devices including a wafer supporting step of mounting an adhesive film to the lower surface of a wafer and attaching the wafer through the adhesive film to the upper surface of a dicing tape mounted on an annular frame, a laser processing step of applying a pulsed laser beam having an absorption wavelength to the wafer along separation lines formed on the upper surface of the wafer after mounting the adhesive film to the dicing tape, thereby separating the wafer into the individual devices and cutting the adhesive film, and a pickup step of expanding the dicing tape after performing the laser processing step to thereby increase the spacing between any adjacent ones of the individual devices, and peeling off to pick up each of the individual devices from the dicing tape in the condition where the adhesive film is mounted on the lower surface of each device.