Wafer Edge Trimming With a Sacrificial Layer to Prevent Chipping
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Solution Overview
Problem
Current wafer edge trimming methods, particularly multi-stage cutting processes, lead to increased production time and reduced throughput due to the need for multiple stages and stress distribution, which can cause microcracks and chipping during the cutting process.
Innovation Solution
A one-step wafer edge trimming process using a sacrificial layer and a diamond blade with a constant feed rate greater than 5 degrees per second, allowing for a single-stage edge removal without intermittent tool changes, thereby reducing stress concentration and improving productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-stage cutting process is used to distribute stress and reduce chipping, then manufacturing precision is improved, but productivity deteriorates due to increased trimming time
Solution Approach 1:
A sacrificial layer is formed on the rear surface of the wafer before the edge trimming process. This preliminary action provides stress compensation during cutting, allowing a single-stage high-speed trimming process to achieve edge quality previously only attainable through multi-stage processes, thereby resolving the contradiction between manufacturing precision and productivity
2Productivity
If feed rate is increased to improve productivity, then production throughput is improved, but manufacturing precision deteriorates due to increased cutting forces causing microcracks and chipping
Solution Approach 1:
The sacrificial layer is deposited in advance on the wafer surface before cutting. This preliminary preparation creates a stress-compensating structure that allows the blade to cut at high feed rates without generating harmful microcracks, thus enabling both high productivity and high manufacturing precision simultaneously
Solution Approach 2:
The sacrificial layer acts as an intermediary between the cutting blade and the wafer substrate. It absorbs and distributes cutting stresses, preventing direct stress transmission to the wafer that would cause chipping, thereby allowing high feed rates to be used without sacrificing edge quality
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
The one-step process effectively minimizes chipping and microcracking while significantly enhancing production throughput by completing edge trimming in less than 72 seconds with a single blade pass.
Implementation Method 1
performing an one-step wafer edge trimming process to remove an outer edge region of the sacrificial layer and the second wafer in one-step cut using a blade
Implementation Method 2
subjecting a rear surface of the second wafer to a first grinding process, thereby thinning the second wafer to a first thickness
Data Source
AI summary
A wafer processing method is disclosed. A second wafer is bonded to a first wafer. The rear surface of the second wafer is subjected to a first grinding process, thereby thinning the second wafer to a first thickness. A sacrificial layer is formed on the rear surface of the second wafer. A one-step wafer edge trimming process is then performed to remove an outer edge region of the sacrificial layer and the second wafer in one-step cut using a blade. The sacrificial layer is removed from the rear surface of the second wafer.