Semi-Rigid Frontside Tape for Low-Temperature Vacuum Processing
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Solution Overview
Problem
The challenge in microelectronics fabrication is performing vacuum processing on thin substrates without causing thermal gradients and wafer breakage, as existing rigid carrier solutions are complex and costly, and backside grind tape lacks stiffness and thermally decomposes at elevated temperatures, leading to air bubbles and increased thermal resistance.
Innovation Solution
A method involving a semi-rigid frontside tape with a UV-curable adhesive, where the tape is pre-cured to form gas escape paths and edge seals, allowing for sufficient stiffness and support during vacuum processing at elevated temperatures without the need for additional mechanical support, and maintaining contact with the wafer topography to prevent contamination and bubbling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If backside grind tape is applied to support thin wafers during vacuum processing, then handling and support are improved, but the tape lacks sufficient stiffness and thermally decomposes at elevated temperatures
Solution Approach 1:
The tape is pre-cured before vacuum processing to establish gas escape paths and adhesive bonds in advance. This preliminary action prevents bubble formation during subsequent heating and processing, allowing the tape to maintain its support function without requiring excessive stiffness or additional cooling mechanisms.
2Stability of the object's composition
If substrate cooling is applied to prevent tape thermal decomposition, then tape stability is improved, but air bubbles form between the tape and wafer, increasing thermal resistance
Solution Approach 1:
Gas escape paths are created in the adhesive layer before vacuum processing begins. This preliminary structuring of the adhesive allows trapped air and volatiles to escape during subsequent heating, preventing bubble formation and maintaining reliable thermal contact between the tape and wafer throughout the processing cycle.
Solution Approach 2:
The adhesive layer is designed with different properties at different locations: the bulk adhesive provides bonding and support, while specific regions contain gas escape paths that facilitate volatile removal. This local differentiation allows the tape to maintain both stability and thermal contact reliability simultaneously.
3Ease of operation
If rigid carrier solutions are used for vacuum processing, then support and handling are improved, but device complexity and cost increase
Solution Approach 1:
The patent employs a disposable tape system that is applied to the wafer frontside and removed after processing. This single-use approach eliminates the need for complex, expensive rigid carriers that must be reused and meticulously maintained. The tape provides sufficient support for the specific processing operation without requiring additional mechanical support structures.
Solution Approach 2:
The tape serves multiple functions simultaneously: it provides mechanical support for thin wafers, creates gas escape paths for volatile removal, maintains thermal contact during processing, and protects the wafer surface. This multi-functionality eliminates the need for separate rigid carrier systems and associated complexity.
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 approach enables low-temperature vacuum processing of thin wafers, reducing thermal gradients and wafer bowing, thus preventing breakage and allowing for efficient BSM deposition without the complexity and cost of rigid carrier solutions.
Implementation Method 1
A method involving a semi-rigid frontside tape with a UV-curable adhesive, where the tape is pre-cured to form gas escape paths and edge seals
Data Source
AI summary
Vacuum processing, such as a backside metallization (BSM) deposition, is performed on a taped wafer after a gas escape path is formed between a base film of the tape and the wafer frontside surface following backgrind. Venting provided by the gas escape path reduces formation of bubbles under the tape. The gas escape path may be provided, for example, by a selective pre-curing of tape adhesive, to breach an edge seal and place the wafer frontside surface internal to the edge seal in fluid communication with an environment external to the edge seal. With the thinned wafer supported by the pre-cured tape, BSM is then deposited while the wafer and tape are cooled, for example, via a cooled electrostatic chuck.