Wafer Protective Sheet Lamination Over Stepped Device Surfaces
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Solution Overview
Problem
The protective sheet used to prevent damage to wafers during processing is prone to breaking when brought into contact with the wafer's front surface by atmospheric pressure, especially due to steps formed between devices and streets on the wafer surface.
Innovation Solution
A wafer processing method that involves filling the recessed streets with water, disposing a protective sheet on the wafer, and using a vacuum chamber to press-fit the protective sheet to the wafer's peripheral marginal area before bringing it into contact with the front surface using atmospheric pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protective sheet is brought into close contact with the front surface of the wafer by atmospheric pressure using the vacuum chamber, then the protective sheet covers the front surface, but the protective sheet is broken in a fiber form at the parts where steps are formed
Solution Approach 1:
The recessed streets are filled with water before the protective sheet is brought into contact with the wafer front surface. This preliminary action creates a cushioning effect that prevents the protective sheet from being directly subjected to atmospheric pressure at the step locations, thereby avoiding fiber-form breakage while still allowing the sheet to cover the front surface effectively
Solution Approach 2:
Water is introduced as an intermediary substance between the protective sheet and the wafer front surface. The water fills the recessed streets and acts as a mediator that distributes the atmospheric pressure uniformly, preventing direct contact between the protective sheet and the sharp edges of the steps that would cause breakage
2Manufacturing precision
If the protective sheet is pressed against the peripheral marginal area in the vacuum chamber, then the protective sheet is press-fitted to the peripheral area, but the protective sheet enters deep into the recessed area when atmospheric pressure is applied
Solution Approach 1:
The recessed streets are filled with water before atmospheric pressure is applied. This preliminary filling prevents the protective sheet from being forced deep into the recessed areas by atmospheric pressure, as the water occupies the recessed spaces and prevents the sheet from deforming into them
Solution Approach 2:
Water is used as a hydraulic medium to counteract the atmospheric pressure effect. By filling the recessed streets with water, the system utilizes fluid pressure to balance the atmospheric pressure applied to the protective sheet, preventing unwanted deformation and maintaining precise positioning
3Reliability
If the protective sheet is broken due to steps on the front surface, then the protective sheet cannot protect the wafer, but the electrode pad is deformed during peeling off
Solution Approach 1:
The recessed streets are filled with water before the protective sheet is applied. This preliminary action prevents the protective sheet from breaking at the step locations, thereby maintaining the sheet's protective function and simultaneously preventing electrode pad deformation during the peeling process
Solution Approach 2:
Water is introduced to counteract the harmful effect of atmospheric pressure on the protective sheet. By preemptively filling the recessed streets with water, the system prevents the sheet breakage that would otherwise occur, thereby preventing the subsequent harmful effect of electrode pad deformation during peeling
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 prevents the protective sheet from breaking due to atmospheric pressure and avoids deformation of electrode pads during the peeling process, ensuring a successful wafer processing outcome.
Implementation Method 1
a decompression step of decompressing an inside of the vacuum chamber
Implementation Method 2
the vacuum chamber is opened to the atmosphere, and the protective sheet is brought into close contact with the front surface of the wafer by the atmospheric pressure
Data Source
AI summary
A wafer processing method includes a wafer accommodating step of accommodating a wafer in a vacuum chamber, a protective sheet disposing step of disposing a protective sheet on a front surface of the wafer, a decompression step of decompressing the inside of the vacuum chamber, after the wafer accommodating step and the protective sheet disposing step, a press-fitting step of pressing the protective sheet against a peripheral marginal area of the wafer in the vacuum chamber to press-fit the protective sheet to the peripheral marginal area, after the decompression step, and a conveying-out step of opening the vacuum chamber to atmosphere to bring the protective sheet into close contact with the front surface of the wafer by atmospheric pressure and conveying out the wafer, after the press-fitting step.