Wafer Cutting Depth Control via Regional Height Measurement
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Solution Overview
Problem
Existing wafer processing methods face challenges in forming cut grooves without exfoliating low-k films, especially when test element groups are present, as they require preliminary registration of positions and can result in shallow cutting if not accurately measured.
Innovation Solution
A wafer processing method that involves holding the wafer, measuring surface heights in regions, setting the lowest height as the surface height for each region, and cutting with a cutting blade based on these measurements to form cut grooves without preliminary registration of structures, ensuring the low dielectric constant insulator film is not left on the streets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the cutting-in depth of the cutting blade is increased to remove the low-k film on the streets, then the low-k film removal is improved, but exfoliation of the low-k film is generated
Solution Approach 1:
The wafer surface is divided into multiple regions, and height measurements are taken at multiple points within each region. The minimum height value from these measurements is used to determine the cutting depth, effectively segmenting the measurement process to capture the lowest point accurately and prevent both over-cutting and under-cutting.
Solution Approach 2:
Height measurements are performed before the cutting operation to determine the appropriate cutting depth. This preliminary measurement action allows the system to adjust the cutting blade height in advance, ensuring that the cutting depth is optimized for each specific wafer surface condition, thereby preventing low-k film exfoliation while achieving complete removal.
2Object-affected harmful factors
If the cutting-in depth of the cutting blade is decreased to prevent exfoliation of the low-k film, then low-k film exfoliation is reduced, but the low-k film on the streets cannot be removed sufficiently
Solution Approach 1:
The wafer surface is divided into multiple regions, and height measurements are taken at multiple points within each region. The minimum height value from these measurements is used to determine the cutting depth, effectively segmenting the measurement process to capture the lowest point accurately and prevent both over-cutting and under-cutting.
Solution Approach 2:
Height measurements are performed before the cutting operation to determine the appropriate cutting depth. This preliminary measurement action allows the system to adjust the cutting blade height in advance, ensuring that the cutting depth is optimized for each specific wafer surface condition, thereby preventing low-k film exfoliation while achieving complete removal.
3Measurement precision
If the positions of TEGs are preliminarily registered to measure height accurately, then measurement precision is improved, but processing time is increased
Solution Approach 1:
The system performs height measurements at multiple points across the wafer surface without requiring preliminary registration of TEG positions. The measurement process itself is self-sufficient, collecting data from multiple locations and using the minimum value to determine cutting depth, thereby eliminating the time-consuming registration step while maintaining measurement accuracy.
Solution Approach 2:
The wafer surface is divided into multiple regions, and height measurements are taken at multiple points within each region. The minimum height value from these measurements is used to determine the cutting depth, effectively segmenting the measurement process to capture the lowest point accurately and prevent both over-cutting and under-cutting.
4Manufacturing precision
If the positions of TEGs are preliminarily registered to avoid shallow cutting, then cutting accuracy is improved, but erroneous registration causes shallow cutting and time is wasted
Solution Approach 1:
The system performs height measurements at multiple points across the wafer surface without requiring preliminary registration of TEG positions. The measurement process itself is self-sufficient, collecting data from multiple locations and using the minimum value to determine cutting depth, thereby eliminating the time-consuming registration step while maintaining measurement accuracy.
Solution Approach 2:
The wafer surface is divided into multiple regions, and height measurements are taken at multiple points within each region. The minimum height value from these measurements is used to determine the cutting depth, effectively segmenting the measurement process to capture the lowest point accurately and prevent both over-cutting and under-cutting.
Data Source
AI summary
A wafer processing method for forming cut grooves in streets of a wafer provided with a plurality of devices includes a holding step ST1 of holding the back surface side of the wafer by a holding surface of a chuck table, a measurement step ST2 of partitioning the front surface of the wafer held by the chuck table into a plurality of regions and measuring the surface height of the streets in each of the regions, a region-basis height setting step ST3 of setting the lowest surface height in each region as the surface height of the wafer in each region, and a cutting step ST4 of forming cut grooves in the front surface of the wafer while setting, on a region basis, a tip position of a cutting blade, based on the surface height of the wafer set in the region-basis height setting step ST3.