Post-Passivation Interconnect Etching With Polymer Pad Protection
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Solution Overview
Problem
The existing semiconductor manufacturing processes face challenges in forming post-passivation interconnects (PPI) structures with precise control over the etching process, leading to issues such as over-etching of conductive pads and uneven opening formation, which can result in stress at the bottom corners of the PPI structures and affect their performance in thermal shock tests.
Innovation Solution
A method is introduced where a polymer layer is continuously deposited during the etching process to form an opening in the passivation layer and conductive pad, acting as a blocking layer to adjust the etching rate and prevent over-etching, resulting in a PPI structure with a desired configuration and reduced stress at the bottom corners, including a conductive pattern with specific sidewall angles and turning points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional etching process is used to form openings in the passivation layer, then the etching process can be completed, but over-etching of conductive pads occurs and the bottom corners of the PPI structures experience excessive stress
Solution Approach 1:
A polymer layer is introduced as an intermediary blocking layer during the etching process. This polymer layer is deposited conformally on the sidewalls and bottom of the opening, and it selectively blocks the etchant from attacking the conductive pad material, thereby preventing over-etching while allowing the etching to proceed through the passivation layer
Solution Approach 2:
The polymer layer is deposited in advance before the etching process completes. By performing the polymer deposition as a preliminary action during the etching process itself, the conductive pad is protected before excessive etching can occur, preventing the formation of stress-prone sharp corners
2Manufacturing precision
If the etching process is extended to ensure complete opening formation, then the opening can be fully formed, but the conductive pad integrity is compromised due to over-etching
Solution Approach 1:
The polymer layer serves as a protective intermediary that allows the etching process to continue until the opening is fully formed while preventing the etchant from damaging the conductive pad. The polymer blocks the etchant path to the conductive pad, enabling complete opening formation without compromising pad integrity
Solution Approach 2:
The polymer layer is self-forming during the etching process itself through continuous deposition. As the etching proceeds, the polymer deposits conformally on the exposed surfaces, automatically adjusting to protect the conductive pad while allowing the opening to form to the required depth
3Productivity
If the etching process is accelerated to improve manufacturing efficiency, then productivity increases, but control over etching rate decreases leading to uneven opening formation
Solution Approach 1:
The polymer deposition continues continuously during the etching process rather than being a separate pre-step. This continuous deposition ensures that the protective layer is constantly replenished and uniformly distributed throughout the etching process, maintaining both high etching rates and uniform opening formation
Solution Approach 2:
The polymer deposition rate provides feedback control for the etching process. As the etching progresses and the opening geometry changes, the polymer continues to deposit conformally, automatically adjusting the protection level to maintain uniform etching rates and prevent deviations in opening formation
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 allows for the formation of PPI structures with improved thermal shock performance by maintaining the conductive pad integrity and achieving a desired configuration, reducing the risk of over-etching and enhancing the structural reliability of semiconductor devices.
Implementation Method 1
a polymer layer is continuously deposited during the etching process to form an opening in the passivation layer and conductive pad
Data Source
AI summary
Semiconductor device and method of forming the same are disclosed. One of the semiconductor devices includes a semiconductor substrate, a passivation layer and a conductive pattern. The semiconductor substrate includes a conductive pad thereover. The passivation layer over the semiconductor substrate. The conductive pattern is penetrating through the passivation layer and electrically connected to the conductive pad, wherein a sidewall of the conductive pattern has at least one turning point.