Translucent Tape Mounting for Laser-Marking Warped Semiconductor Substrates
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Solution Overview
Problem
Semiconductor wafers with high warpage pose challenges for laser-marking, leading to vacuum errors, reduced yield, and increased manufacturing costs due to difficulties in maintaining a seal and degrading laser resolution on uneven surfaces.
Innovation Solution
A method involving the use of a translucent tape to mount semiconductor substrates or dies with bumps, grinding the back surface to reduce thickness, forming a laminate layer, and laser-marking this layer while the tape remains applied, allowing for accurate marking and subsequent removal of the tape to minimize warpage and enhance processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser-marking is performed on wafers with high warpage, then manufacturing process continues, but vacuum errors occur and laser resolution degrades
Solution Approach 1:
A flat carrier substrate is introduced as an intermediary between the warped wafer and the laser-marking system. The wafer is mounted on the flat carrier, which provides a stable, planar surface that maintains vacuum integrity and ensures consistent laser resolution during marking, while allowing the warped wafer itself to remain unchanged
Solution Approach 2:
The problem is shifted from the wafer surface dimension to the carrier substrate dimension. By transferring the wafer to a flat carrier, the marking process occurs on a different dimensional plane (the carrier surface) that is inherently flat, thereby eliminating warpage-related issues without requiring the wafer itself to be flattened
2Productivity
If laser-marking is performed on wafers with high warpage, then manufacturing process continues, but vacuum seal cannot be maintained
Solution Approach 1:
The flat carrier substrate serves as a mediator that provides a sealable surface for the vacuum system. The carrier's flat surface allows proper sealing with the vacuum chuck, while the wafer mounted on top can retain its warped shape without affecting vacuum integrity
Solution Approach 2:
The vacuum sealing function is separated from the wafer surface and transferred to the carrier substrate surface. This dimensional separation allows the vacuum system to interact with the flat carrier rather than the warped wafer, ensuring reliable sealing while maintaining manufacturing continuity
3Stability of the object's composition
If tape is applied to mount semiconductor substrates, then substrate stability improves, but tape must be removed afterward adding process steps
Solution Approach 1:
The tape is used as a temporary, disposable mounting medium that serves its purpose during the laser-marking process and is then easily removed. The low cost and simple removal process of the tape make the additional step acceptable, as it enables stable processing of warped substrates
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 approach enables successful laser-marking of wafers with high warpage by reducing flex and improving surface flatness, maintaining vacuum integrity and increasing laser resolution, thus reducing manufacturing errors and costs.
Implementation Method 1
laser-marking the laminate layer
Implementation Method 2
laser-marking the laminate layer
Data Source
AI summary
A semiconductor device has a semiconductor die with a plurality of bumps formed on contact pads disposed over its active surface. An encapsulant is formed over the semiconductor die. An interconnect structure is formed over the semiconductor die and encapsulant. The semiconductor die is mounted to a translucent tape with the bumps embedded in the translucent tape. The translucent tape has layers of polyolefin, acrylic, and polyethylene terephthalate. A back surface of the semiconductor die undergoes backgrinding to reduce die thickness. The tape undergoes UV curing. A laminate layer is formed over the back surface of the semiconductor die. The laminate layer undergoes oven curing. The laminate layer is laser-marked while the tape remains applied to the bumps. The tape is removed after laser-marking the laminate layer. Alternately, the tape can be removed prior to laser-marking. The tape reduces die warpage during laser-marking.