Laser Marking Device Pressing Unit for Warped Semiconductor Wafers
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Solution Overview
Problem
The warpage of semiconductor wafers due to increased size and decreased thickness leads to irregular marking quality and inconsistent line widths during laser marking, as the height deviation exceeds the focal depth of the laser beam, affecting the precision and reliability of the marking process.
Innovation Solution
A laser marking device with a pressing unit that includes a first contact pressing portion for the edge area and at least one non-contact second pressing portion for the middle area, maintaining a separation distance of about 50 μm, applies a pressure of 0.01 MPa to 0.5 MPa using gas ejection to compensate for height deviations, ensuring flatness and maintaining the integrity of semiconductor patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam is used to mark semiconductor chips on a wafer, then marking efficiency and productivity are improved, but marking precision deteriorates due to wafer warpage causing height deviation exceeding focal depth
Solution Approach 1:
A pressing unit is introduced as an intermediary device between the wafer and the laser marking system. This pressing unit applies controlled pressure to the wafer surface to correct warpage-induced height deviations, ensuring the wafer remains within the laser beam's focal depth during marking operations, thereby maintaining marking precision while preserving high productivity
Solution Approach 2:
The pressing unit dynamically adjusts pressing parameters (pressure, position) to compensate for wafer warpage. By changing the physical state of the wafer surface through controlled pressing, the system maintains optimal marking conditions without sacrificing the efficiency benefits of laser marking
2Productivity
If wafer size is increased and thickness is decreased to enable mass production, then productivity is improved, but warpage increases causing marking quality to deteriorate
Solution Approach 1:
The pressing unit applies preliminary counteracting pressure to the wafer surface before laser marking begins. This pre-pressing action compensates for the inherent warpage caused by large size and thin thickness, proactively correcting the flatness issue before it affects marking quality, thereby enabling mass production of large wafers without sacrificing stability
3Reliability
If coating material is applied to wafer surface for processing, then functional properties are improved, but warpage increases due to contraction during curing, worsening marking precision
Solution Approach 1:
The pressing unit performs preliminary pressing after coating material application and during the curing process. This timing allows the pressing action to counteract the contraction forces developing as the coating cures, preventing warpage from developing to levels that would compromise marking precision while still allowing the coating to achieve its functional properties
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 ensures reliable marking quality by flattening the warped wafer surface, maintaining the separation distance and pressure to prevent damage to semiconductor patterns, thereby improving the consistency and precision of laser markings even on warped substrates.
Implementation Method 1
at least one second pressing portion configured to press a middle area of the second surface in a non-contact manner to maintain a separation distance from the second surface within a certain distance
Data Source
AI summary
A laser marking device includes a laser emission unit configured to emit a laser beam to a first surface of an object to be processed, and a pressing unit configured to press a second surface that is opposite to the first surface of the object to be processed to make the first surface of the object to be flat. The pressing unit includes a first pressing portion configured to press an edge area of the second surface in a contact manner, and at least one second pressing portion configured to press a middle area of the second surface in a non-contact manner to maintain a separation distance from the second surface within a certain distance.