Electrostatic Chucking Carrier Wafer for Thin Substrate Handling
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Solution Overview
Problem
Conventional thin wafer handling and processing methods are inefficient and risky, as they require multiple steps, consume adhesives and cleaners, and risk damage to the device wafer due to the use of adhesives for bonding and debonding carrier wafers, especially when handling thin and large silicon wafers in extreme environments.
Innovation Solution
The use of an electrostatic chucking (ESC) carrier wafer that securely attaches to thin silicon or mold compound substrates using electrostatic charging forces, allowing for high-throughput processing without adhesives, enabling chip stacking, electrical coupling, and encapsulation while minimizing material costs and handling risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive bonding is used to attach carrier wafer to device wafer, then carrier wafer can be securely attached, but multiple process steps and materials (adhesive, debonder, cleaner) are required increasing complexity and cost
Solution Approach 1:
The patent removes the adhesive bonding step entirely from the carrier attachment process. Instead of using adhesive to bond the carrier wafer to the device wafer, the system uses electrostatic charging forces to attach the carrier wafer to the electrostatic chuck, eliminating the need for adhesive, debonder, and cleaner materials.
Solution Approach 2:
The patent replaces the mechanical adhesive bonding system with an electrostatic field-based attachment system. The carrier wafer is attached through electrostatic forces generated by the electrostatic chuck, substituting chemical bonding mechanisms with electrical field mechanisms.
2Strength
If adhesive bonding is used to attach carrier wafer, then carrier can be held firmly, but damage risk to device wafer increases during bonding and debonding operations
Solution Approach 1:
The patent extracts the harmful adhesive bonding and debonding operations from the process. By using electrostatic attachment, there is no chemical bonding to break, eliminating the mechanical stress and potential damage that occurs during adhesive removal from the delicate device wafer.
Solution Approach 2:
The patent separates the carrier attachment function from the device wafer itself. The carrier wafer attaches to the electrostatic chuck independently, allowing the device wafer to be processed without direct mechanical or chemical bonding that could cause damage.
3Ease of manufacture
If conventional adhesive bonding process is used, then carrier wafer can be attached and removed, but time consumption increases due to temperature cycling and multiple steps
Solution Approach 1:
The patent removes the time-consuming steps of adhesive application, alignment, bonding, and debonding from the process. The electrostatic attachment method allows for rapid carrier wafer attachment and removal without temperature cycling or multiple process steps.
Solution Approach 2:
The electrostatic chuck is prepared in advance by establishing the electrostatic field, allowing the carrier wafer to be quickly attached when needed. This eliminates the need for preliminary adhesive application and bonding steps.
4Weight of moving object
If wafer thickness is reduced to reduce weight and cost, then device performance improves, but handling difficulty and breaking risk increase
Solution Approach 1:
The patent introduces the electrostatic chuck as an intermediary between the thin device wafer and the handling system. The electrostatic field provides uniform support across the entire wafer surface, distributing stresses and preventing breakage that would occur with conventional mechanical handling of thin wafers.
Solution Approach 2:
The electrostatic attraction force acts as a counterbalancing force to the gravitational and handling-induced stresses on the thin wafer. The strong electrostatic field holds the wafer firmly in place, compensating for the reduced structural strength of thinner materials.
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 enables efficient and cost-effective handling and processing of thin substrates and mold compound wafers, reducing material costs and minimizing damage risks, while allowing for 2.5D and 3D IC packaging with high throughput and reduced adhesive usage.
Implementation Method 1
an electrostatic-chucking carrier wafer that securely attaches to thin silicon or mold compound substrates using electrostatic charging forces
Data Source
AI summary
Thin substrates and mold compound handling is described using an electrostatic-chucking carrier. In one example, a first part of a plurality of silicon chip packages is formed on a front side of a silicon substrate wafer at a first processing station. An a carrier wafer of an electrostatic chuck is attached over the front side of the silicon wafer. The substrate wafer is moved to a second processing station. A second part of the plurality of silicon chip packages are formed on a back side of the silicon wafer at a second processing station. The electrostatic chuck is then released.