Semiconductor Substrate Joining via Polymer Alignment Key
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Solution Overview
Problem
The existing methods for joining semiconductor substrates often result in alignment errors and defects due to thermal expansion and metal layer re-flow during the joining process, which can lead to defects in the semiconductor device.
Innovation Solution
A method involving the formation of an alignment key on one semiconductor substrate and corresponding protrusions and recesses on the other, with the alignment key positioned at the recess during joining, using a photosensitive polymer material and ensuring its thickness is greater than the metal layers to prevent re-flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal layers are formed on semiconductor substrates before joining, then the semiconductor device functionality is improved, but the metal layers may re-flow during joining due to heat or pressure causing defects
Solution Approach 1:
The patent applies preliminary action by forming protrusions on the substrate surface before depositing metal layers. These pre-formed protrusions create physical barriers that prevent metal layer re-flow during subsequent joining processes, while still allowing the metal layers to be formed for device functionality.
Solution Approach 2:
The protrusions act as intermediary structures between the substrate and metal layers. They provide a mechanical barrier that mediates the interaction between heat/pressure during joining and the metal layers, preventing direct contact and re-flow while maintaining electrical connectivity where needed.
2Productivity
If optical measurement method is used for alignment of semiconductor substrates, then the joining process can be completed, but fine alignment errors may still be generated
Solution Approach 1:
The patent replaces the optical measurement alignment system with a mechanical alignment system using protrusions and recesses. The protrusions on one substrate fit into corresponding recesses on the other substrate, providing direct mechanical alignment that eliminates fine alignment errors inherent in optical methods.
Solution Approach 2:
The invention changes the alignment parameter from optical field-of-view measurements to direct mechanical contact geometry. By designing protrusions with specific dimensions and shapes that complement corresponding recesses, the alignment precision is determined by mechanical fit rather than optical resolution limits.
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 effectively prevents metal layer re-flow and alignment errors, ensuring accurate joining of semiconductor substrates without defects, thereby enhancing the reliability of semiconductor devices.
Implementation Method 1
forming an alignment key on a first semiconductor substrate... The alignment key may be formed of a photosensitive polymer material
Data Source
AI summary
A method of joining semiconductor substrates includes: forming an alignment key on a first semiconductor substrate; forming a first protrusion and a second protrusion, and an alignment recess positioned between the first protrusion and the second protrusion on a second semiconductor substrate; forming a first metal layer and a second metal layer on the first protrusion and the second protrusion, respectively; and joining the first semiconductor substrate and the second semiconductor substrate, in which the alignment key is positioned at the alignment recess when the first semiconductor substrate and the second semiconductor substrate are joined.