Wafer Laser Grooving and Etching for Clean Dicing
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Solution Overview
Problem
Existing methods for manufacturing semiconductor devices with adhesive films attached to the back-side surface can result in device breakage and lowered transverse rupture strength due to debris adhesion and surface denaturation when using pulsed laser beams for cutting.
Innovation Solution
A method involving laser beam-machined groove formation on the back-side of the wafer, followed by etching to remove denatured layers, and then attaching an adhesive film to the back-side surface for efficient rupture along individual devices using a dicing tape expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pulsed laser beam is used to cut the wafer from the face side, then the wafer can be divided into individual devices, but debris is generated and adheres to device surfaces, lowering device quality
Solution Approach 1:
The patent applies inversion by changing the irradiation direction from the conventional face-side to the back-side of the wafer. The laser beam is introduced from the back surface through the transparent or semi-transparent wafer material, allowing cutting to occur from the opposite direction. This prevents debris generation on the device surfaces while maintaining effective wafer division along the planned dividing lines.
Solution Approach 2:
The patent uses an intermediary approach by introducing a liquid medium (water or other liquids) between the laser beam and the wafer during processing. This liquid medium serves multiple functions: it cools the wafer during laser irradiation, prevents debris adhesion to the device surfaces, and facilitates cleaner cutting by washing away generated debris in real-time during the cutting process.
2Ease of manufacture
If a pulsed laser beam is used to divide the wafer, then cutting can be achieved, but the divided surfaces become denatured, resulting in lowered transverse rupture strength
Solution Approach 1:
The liquid intermediary medium not only prevents debris adhesion but also reduces thermal damage and denaturation of the divided surfaces. By providing continuous cooling and flushing during laser cutting, the liquid medium minimizes heat accumulation and thermal stress, thereby preserving the mechanical strength and reducing surface denaturation of the divided wafer regions.
Solution Approach 2:
The patent employs parameter changes by carefully controlling laser beam parameters (wavelength, pulse duration, intensity) and processing conditions (liquid flow rate, temperature, pressure) to optimize the cutting process. These parameter adjustments enable effective wafer division while minimizing thermal damage and preserving the transverse rupture strength of the divided surfaces.
3Productivity
If the adhesive film is adhered to the back-side surface and the assembly is cut by a cutting blade, then devices can be divided, but the devices may show irregular motions or breakage due to shock
Solution Approach 1:
The patent replaces the mechanical cutting blade system with a laser beam cutting system. This substitution eliminates the mechanical shock and physical contact that cause device breakage and irregular motions. The laser beam provides non-contact, vibration-free cutting that maintains device integrity while achieving effective division along the planned dividing lines.
Solution Approach 2:
The liquid intermediary medium provides cushioning and shock absorption during the laser cutting process, further protecting the devices from any residual vibrations or thermal shocks. The liquid medium stabilizes the processing environment and prevents sudden movements or breakage of the delicate devices during division.
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
Prevents debris adhesion and maintains device quality by avoiding surface denaturation, ensuring high transverse rupture strength and efficient manufacturing of devices with adhesive films attached to the back-side surface.
Implementation Method 1
irradiating the wafer with a laser beam, which has such a wavelength as to be absorbed in the wafer, from the back side of the wafer along the planned dividing lines, so as to form laser beam-machined grooves
Implementation Method 2
an etching step of etching the back-side surface of the wafer having been subjected to the laser beam-machined groove forming step, so as to remove denatured layers formed at processed surfaces of the laser beam-machined grooves
Data Source
AI summary
A method of manufacturing a device includes: a laser beam-machined groove forming step of irradiating a wafer with a laser beam from the back side of the wafer along planned dividing lines so as to form laser beam-machined grooves along the planned dividing lines; an etching step of etching a back-side surface of the wafer having been subjected to the laser beam-machined groove forming step, so as to remove denatured layers formed at processed surfaces of the laser beam-machined grooves; an adhesive film attaching step of attaching an adhesive film to the back-side surface of the wafer having been subjected to the etching step, and adhering the adhesive film side of the wafer to a surface of a dicing tape; and an adhesive film rupturing step of expanding the dicing tape so as to rupture the adhesive film along individual devices.