Pulsed Laser Singulation of Polymer Resin Substrates
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Solution Overview
Problem
Conventional methods for singulating integrated circuit wafers, such as diamond sawing and abrasive water jet technology, face issues like edge chipping, slow processing speeds, high costs, and limitations in cutting complexity, while laser singulation struggles with thermal effects and cost-effectiveness.
Innovation Solution
A laser ablation system using a pulsed laser with a repetition rate above 10 kHz, a buffer station with heating and gas injection, and a cutting jig with embedded trenches for precise cutting, along with vacuum pressure and compressed air for debris removal and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If diamond sawing is used to cut the wafer, then the wafer can be singulated into individual dies, but edge chipping, edge cracks, copper smear, and solder bridging occur
Solution Approach 1:
The patent replaces the mechanical diamond sawing system with a laser-based system. The laser beam cuts through the wafer and substrate material without physical contact, eliminating mechanical stress and friction that cause edge chipping, cracks, and copper smear. The laser energy is focused to a small spot size, enabling precise cutting along scribe grids while maintaining edge integrity.
Solution Approach 2:
The patent introduces an intermediary gas flow (inert gas or vacuum) between the laser beam and the wafer surface. This intermediary medium helps remove cutting debris and molten material from the cut zone, preventing solder bridging and edge contamination while allowing the laser to maintain precise control over the cutting path.
2Manufacturing precision
If mechanical sawing with water or wet chemical slurry is used, then some edge issues are avoided, but leakage during mechanical sawing occurs and processing is slow
Solution Approach 1:
The patent replaces the slow mechanical sawing process with a high-speed laser cutting system. The laser beam can rapidly traverse the wafer surface, cutting through multiple layers (wafer, substrate, encapsulant) simultaneously without the mechanical constraints of saw blade speed or feed rate. This achieves both high edge quality and high productivity.
Solution Approach 2:
The patent uses periodic pulsed laser operation rather than continuous irradiation. The laser emits short pulses at high repetition rates, allowing brief intervals for heat dissipation and material ejection between pulses. This periodic action prevents excessive heat accumulation and melting while maintaining rapid cutting speed, avoiding the leakage issues associated with continuous wet mechanical sawing.
3Ease of operation
If conventional laser techniques are used for singulation, then non-contact cutting is achieved, but thermal effects cause damage and cost-effectiveness is reduced
Solution Approach 1:
The patent employs pulsed laser operation with carefully controlled pulse duration and repetition rate. The periodic pulsing allows the material to cool between pulses, preventing excessive heat accumulation and thermal damage to sensitive structures. The duty cycle is optimized to remove material through ablation while limiting total heat input to avoid warping or melting of the wafer and substrate.
Solution Approach 2:
The patent optimizes multiple laser parameters including pulse width, repetition rate, power density, and scanning speed to minimize thermal effects. By adjusting these parameters, the laser energy is concentrated enough to cut through the materials efficiently but distributed enough in time and space to allow heat dissipation, preventing thermal damage while maintaining the non-contact advantage.
4Shape
If diamond sawing is used, then straight line cuts are achieved, but each scribe grid requires large width for alignment and tool width, consuming large portion of the semiconductor wafer
Solution Approach 1:
The patent replaces the physical saw blade with a focused laser beam that can be precisely positioned and directed. The laser spot size can be controlled to be much narrower than any mechanical saw blade, allowing cuts to be made with minimal kerf width. This reduces the space consumed by scribe grids while maintaining precise alignment and straight line cuts through digital positioning control.
5Manufacturing precision
If diamond sawing is used, then wafer cutting is achieved, but the cutting process is slow requiring more than an hour to scribe all scribe grids
Solution Approach 1:
The patent replaces the slow mechanical sawing process with a high-speed laser cutting system. The laser beam can rapidly traverse the wafer surface at speeds much higher than mechanical saws, and the focused energy allows immediate cutting without the need for slow, controlled mechanical feed rates. This achieves both high precision and high productivity, reducing singulation time from over an hour to a fraction of that time.
Solution Approach 2:
The patent enables continuous laser cutting operation where the laser beam continuously traverses the wafer surface along the scribe grids without interruption or repositioning delays. The laser system maintains constant cutting action across all scribe lines, eliminating the start-stop nature of mechanical sawing and achieving uninterrupted high-speed singulation while maintaining accurate cut placement.
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 achieves faster, more uniform singulation with narrower scribe lines, reducing thermal damage and maintaining high edge quality, while being cost-effective and efficient in processing speed.
Implementation Method 1
a method of singulation of a polymer resin or substrate into integrated circuits by a laser ablation process
Implementation Method 2
The laser can be a pulsed laser with a repetition rate of 10 kHz and above
Implementation Method 3
Vacuum pressure can be used to hold the polymer resin compound to the jig
Implementation Method 4
a source of compressed air or gas forces compressed air or gas in the direction of the laser
Implementation Method 5
The buffer station includes a heating plate
Implementation Method 6
optionally with a gas injector for emitting fast-cooling gas
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
The invention includes a system and method of using a laser for singulation of a polymer resin mold compound substrate into packages or chips by a laser ablation process. A metal jig used for holding the substrate includes trenches to allow the laser beam to penetrate during cutting. Built-in piping allows water to circulate in a base around the jig to cool the substrate during cutting. The laser beam can pass through a cutting nozzle along with compressed gas or air to cool the substrate and remove debris. A pulsed laser beam can be used in the cutting process, so that a combination of passes at different speeds and laser parameters can be achieved. This allows single pass singulation of units at high speed.