Planarized Ring Chuck Table for Wafer Edge Trimming
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Solution Overview
Problem
The existing edge trimming methods for wafers require time-consuming height measurement of the outer circumferential part before grinding processing, which prolongs the processing time.
Innovation Solution
A chuck table with a ring table that holds the wafer via a suction surface, allowing the wafer to be held and ground without the need for pre-measurement, using a base table with a ring table holding mechanism that includes a support surface and communicating ports for suction, and a controller to manage the grinding process, ensuring consistent distance between the abrasive stone and the wafer during rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If height measurement of the outer circumferential part is performed before grinding processing, then the grinding depth can be controlled accurately, but the processing time becomes long
Solution Approach 1:
The ring table's wafer suction surface is pre-planarized during manufacturing to a high precision level. This preliminary action eliminates the need for time-consuming height measurements before grinding, as the pre-established flat surface ensures consistent wafer positioning and grinding depth control throughout the process.
Solution Approach 2:
The ring table's pre-planarized surface serves itself by providing the necessary flatness reference for accurate grinding without requiring external measurement interventions. The built-in precision surface automatically compensates for positioning variations, making separate measurement steps redundant.
2Manufacturing precision
If the wafer suction surface is planarized by grinding, then the wafer can be held at a constant distance from the abrasive stone, but the ring table requires maintenance and replacement
Solution Approach 1:
The ring table is designed as a consumable component with a limited service life. When the wafer suction surface becomes worn or damaged beyond acceptable precision thresholds, the entire ring table is replaced rather than repaired. This approach is economically justified because the ring table represents a relatively small cost compared to the expensive wafer it processes, and replacement ensures consistent precision without complex maintenance procedures.
3Manufacturing precision
If the ring table is made of silicon to match the wafer material, then the grinding process can be optimized, but the ring table becomes more susceptible to damage
Solution Approach 1:
Only the critical wafer suction surface contact area of the ring table is made from silicon to optimize grinding performance and achieve the necessary nanometer-level flatness. The rest of the ring table structure uses more durable materials to provide mechanical strength and support. This localized material selection balances the conflicting requirements of precision and durability.
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 eliminates the need for height measurement, allowing for more efficient grinding processing by maintaining a constant distance between the abrasive stone and the wafer, thereby reducing processing time and improving efficiency.
Implementation Method 1
a ring table that sucks and holds a lower surface of the wafer by a wafer suction surface
Implementation Method 2
The wafer suction surface is planarized by grinding the wafer suction surface by the abrasive stone
Data Source
AI summary
A chuck table in an edge trimming apparatus includes a ring table that sucks and holds a lower surface of an outer circumferential part of the wafer by a wafer suction surface and a base table that holds the ring table in such a manner that the wafer suction surface is exposed. The base table includes a support surface that supports a lower surface of the ring table held by a ring table holding mechanism and a communicating port that is formed in the support surface and causes the wafer suction surface to communicate with a suction source. The ring table has a wafer suction hole having an opening in the wafer suction surface in such a manner as to be capable of connecting to the communicating port. The wafer suction surface is planarized by grinding the wafer suction surface by an abrasive stone.