Wafer Division via Dry Etching and Curved Pressing
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Solution Overview
Problem
Existing methods for processing wafers with films on their back surface, such as dry etching, struggle to effectively divide the workpiece without causing defects or lowering the flexural strength, especially when the number of planned dividing lines increases.
Innovation Solution
A processing method involving a sheet sticking step, protective film formation, mask pattern creation, dry etching to form grooves along planned dividing lines, and using a pressing member with a curved edge to divide the film along these grooves, ensuring precise and efficient separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cutting apparatus is used to divide the wafer, then the processing can be completed, but the wafer is mechanically chipped and defects occur, and flexural strength lowers
Solution Approach 1:
The patent replaces the mechanical cutting system with a chemical etching system. Instead of using a rotating cutting blade that mechanically chips the wafer, the invention uses dry etching to chemically remove material along planned dividing lines, thereby eliminating mechanical damage while maintaining processing capability
Solution Approach 2:
The patent introduces a sheet as an intermediary element that is stuck to the back surface of the wafer. This sheet serves as a mediator that transmits pressing force uniformly during the etching process, enabling precise control of the chemical etching while preventing direct mechanical contact that would cause chipping
2Reliability
If a laser processing apparatus is used to divide the wafer, then mechanical chipping is suppressed and flexural strength is maintained, but the processing time becomes longer when the number of dividing lines increases
Solution Approach 1:
The patent applies preliminary action by sticking the sheet to the back surface of the wafer before performing the etching process. This preliminary preparation enables the subsequent dry etching to proceed efficiently across the entire wafer surface simultaneously, rather than processing each dividing line sequentially as with laser methods
Solution Approach 2:
The patent replaces the sequential laser processing system with a parallel chemical etching system. The dry etching process can simultaneously etch multiple dividing lines across the wafer at once, dramatically reducing processing time while maintaining the reliability benefits of non-mechanical separation
3Productivity
If dry etching is used to process the whole wafer at a time, then processing time does not increase with larger wafer diameter or smaller device size, but the method cannot properly divide wafers with metal films on the back surface
Solution Approach 1:
The patent introduces the sheet as an intermediary that enables dry etching to work effectively with metal films. The sheet adheres to the back surface of the wafer (including areas with metal films) and provides a uniform pressing interface, allowing the chemical etching process to penetrate and divide the workpiece even in the presence of metal films that would otherwise resist etching
Solution Approach 2:
The patent changes the physical state and properties of the workpiece interface by introducing the sheet. This modification alters how the etching process interacts with the workpiece, enabling the chemical etching to proceed through or around metal film layers by changing the contact parameters between the etching environment and the workpiece surface
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 allows for the reliable and efficient division of wafers with films, reducing processing time and preventing defects, compared to traditional cutting or laser methods, while maintaining the integrity of the workpiece.
Implementation Method 1
an adhesion step of heating the sheet or the workpiece to cause the sheet to adhere to the workpiece
Implementation Method 2
an etching step of carrying out dry etching for the substrate from the front surface side on which the mask pattern is formed and forming etching grooves along the planned dividing lines
Data Source
AI summary
A processing method of a workpiece for processing the workpiece including a substrate and a film made on a back surface of the substrate is provided. The processing method includes a sheet sticking step of sticking a sheet to the film, a protective film forming step of forming a protective film that covers the front surface side of the substrate, a mask pattern forming step of removing a part corresponding to planned dividing lines in the protective film and forming a mask pattern on the front surface side, an etching step of carrying out dry etching for the substrate from the front surface side and forming etching grooves and a film dividing step of dividing the film along the etching grooves by pressing the workpiece by an edge of a tip part of a pressing member having the tip part in which the edge has a curved shape.