Chip Active Layer Protection During Substrate Removal
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Solution Overview
Problem
The existing chip-to-plate transfer process for electronic chips, particularly those with type III-V materials, faces issues such as degradation of active layers and residue left from initial substrate removal during grinding, which affects the performance of image sensors due to spectrum absorption problems.
Innovation Solution
A method involving the formation of first and second dielectric encapsulation layers around the chips, followed by directional etching and selective chemical etching of the initial substrate, to protect the active layers during substrate removal, reducing residue and maintaining the integrity of the active layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the initial substrate is removed by grinding, then the active layer can be accessed, but the active layer is degraded and residues remain
Solution Approach 1:
The method applies preliminary protective actions by forming encapsulation layers around the electronic chips before the grinding process. The first encapsulation layer is formed, then grinding is performed, and a second encapsulation layer is formed to protect the edges during subsequent etching steps. This preliminary protection prevents the harmful effects of grinding on the active layer while still allowing substrate removal.
Solution Approach 2:
The encapsulation layers serve as intermediary protective structures between the grinding process and the active layer. These dielectric layers absorb the mechanical stress and protection needs, allowing the grinding process to remove the initial substrate without directly contacting and degrading the active layer. The encapsulation layers are selectively removed later through directional etching.
2Object-generated harmful factors
If the initial substrate is completely removed by grinding, then no residues remain, but the active layer is degraded
Solution Approach 1:
Protective encapsulation layers are formed before the grinding process to shield the active layer. The first encapsulation layer is deposited, then grinding removes the initial substrate completely without degrading the protected active layer. After grinding, a second encapsulation layer is formed to protect the chip edges during subsequent selective etching of any remaining substrate residues.
Solution Approach 2:
The encapsulation layers act as intermediary protective barriers during the grinding process. These dielectric layers absorb the mechanical impact and prevent direct contact between the grinding tool and the active layer, enabling complete substrate removal while maintaining active layer integrity. The encapsulation layers are later selectively removed through directional etching.
3Ease of manufacture
If directional etching is performed to expose the remaining substrate, then selective chemical etching can be performed, but the second encapsulation layer must be partially removed
Solution Approach 1:
The directional etching process applies local quality by selectively removing portions of the second encapsulation layer based on location. The etching is performed in a directional manner to expose the remaining substrate in specific areas while preserving the encapsulation layer in other areas where protection is still needed. This localized modification enables subsequent selective chemical etching without requiring complete removal of the protective layer.
Solution Approach 2:
The encapsulation layer removal is segmented into two distinct phases: first, directional etching removes portions of the second encapsulation layer to expose the substrate in specific areas; second, selective chemical etching removes the exposed substrate while the remaining encapsulation layer continues to protect other areas. This segmentation allows precise control over where substrate removal occurs.
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 effectively protects the active layers from degradation and minimizes substrate residues, ensuring the performance of electronic chips, especially image sensors, by using dielectric encapsulation layers and selective etching to remove the initial substrate efficiently.
Implementation Method 1
perform a directional etch of a portion of the second encapsulation layer, extending over the remaining portion of the initial substrate of each of the electronic chips
Implementation Method 2
perform a selective chemical etch of the remaining portion of the initial substrate of each of the electronic chips; step f) being carried out with a chemical etching agent allowing selective etching of the remaining portion of the initial substrate with respect to the second encapsulation layer and with respect to the dielectric layer
Data Source
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AI summary
A method for protecting active layers (1) of electronic chips (P), comprising the successive steps: a) using a stack comprising successively: - a support substrate (S1); - a hybrid bonding interface (IC); - electronic chips (P), each comprising successively an active layer (1), a dielectric layer (2) and an initial substrate; b) forming a first encapsulation layer (E1) around the electronic chips (P); c) performing a grinding operation so as to remove a portion of the initial substrate and retain a remaining portion; d) forming a second encapsulation layer (E2) around the electronic chips (P); e) performing a directional etching of a portion of the second encapsulation layer (E2), so as to: - superficially expose the remaining portion of the initial substrate; - retain the second encapsulation layer (E2) extending over the sides of the electronic chips (P);f) perform a selective chemical etching of the remaining portion of the original substrate.;