Wafer Thinning with Laser-Formed Separation Layer and Edge Protection
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Solution Overview
Problem
The existing methods for grinding semiconductor wafers to achieve thinner thickness result in material waste, increased tool wear, and higher damage risk, particularly at the chamfered or rounded peripheral edges, leading to chipping and cracks, and are inefficient for hard materials like silicon carbide.
Innovation Solution
A substrate processing method involving the application of a protective sheeting to the front side of the substrate, followed by cutting and laser beam processing to form a flush circumferential edge and a modified layer inside the substrate, reducing the need for extensive grinding and minimizing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If extensive grinding process is applied to achieve target thickness, then wafer thickness is reduced, but material waste increases and damage risk increases
Solution Approach 1:
The method applies preliminary actions by forming a modified layer inside the wafer at a predetermined depth before the final thinning process, and by pre-processing the peripheral edge to create a relief structure. These preliminary modifications enable subsequent separation and thinning with minimal material removal, directly reducing wafer material waste while achieving the target thickness.
2Length of stationary object
If extensive grinding process is applied to achieve target thickness, then wafer thickness is reduced, but grinding time increases
Solution Approach 1:
The invention replaces the traditional mechanical grinding system with a laser-based modification system. By using laser beams to form modified layers inside the wafer and create separation planes, the process eliminates the need for extensive mechanical grinding, dramatically reducing processing time while achieving the same thinning objective.
3Length of stationary object
If extensive grinding process is applied to achieve target thickness, then wafer thickness is reduced, but tool wear increases
Solution Approach 1:
The invention substitutes mechanical grinding tools with laser beams for the critical thinning operations. The laser forms modified layers and separation planes through optical energy rather than mechanical contact, completely eliminating wear on grinding wheels and other mechanical tools while maintaining precise thickness control.
4Length of stationary object
If extensive grinding process is applied to achieve target thickness, then wafer thickness is reduced, but damage occurrence increases
Solution Approach 1:
The method applies preliminary protective actions by forming a modified layer at a predetermined depth that serves as an internal support structure during subsequent processing. The peripheral edge is also pre-processed to create a relief structure that prevents stress concentration. These preliminary modifications significantly reduce the risk of chipping, cracking, and other damage during thinning and handling.
Solution Approach 2:
The modified layer formed inside the wafer acts as a cushioning structure that absorbs and distributes mechanical stresses during subsequent processing steps. This internal support structure prevents stress concentration at critical locations, particularly at the peripheral edges, thereby preventing damage before it can occur during handling or further processing.
5Length of stationary object
If chamfered or rounded peripheral edge is ground to smaller thickness, then wafer thickness is reduced, but edge strength decreases leading to chipping
Solution Approach 1:
The method applies preliminary modification to the peripheral edge region by forming a modified layer that extends to the edge and by creating a relief structure that reinforces the edge geometry. This preliminary reinforcement maintains edge strength even as the overall wafer thickness is reduced, preventing the knife-edge effect and subsequent chipping that occurs with conventional grinding.
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 reduces material loss, tool wear, and damage risk while enabling precise separation of substrate layers with enhanced handling and reduced contamination, making it suitable for hard materials like silicon carbide.
Implementation Method 1
applying a laser beam from the back side of the substrate to form a modified layer inside the substrate in a predetermined depth
Data Source
AI summary
The present disclosure relates to a substrate processing method for processing a substrate having a front side and a back side. A device area is formed on the front side of the substrate. The method comprises the steps of applying a protective sheeting to the front side of the substrate, processing the protective sheeting and the substrate from the front side using a cutting device to form a circumferential wherein at edge, the circumferential edge the processed protective sheeting and the processed substrate are flush in a thickness direction of the substrate, and applying a laser beam from the back side of the substrate to form a modified layer inside the substrate in a predetermined depth.