Semiconductor Chip Redistribution Via Corrosion Prevention
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Solution Overview
Problem
The photolithography process for forming a redistribution layer on semiconductor chips often results in corrosion or damage to aluminum connection pads due to contact with chemical agents, leading to inefficiencies and increased defect rates in the manufacturing process.
Innovation Solution
A method is introduced where a passivation layer covers the connection pads, and via holes are formed through an insulating layer without removing the passivation layer initially, thereby blocking contact between chemical agents and the pads, and a redistribution via is filled with a conductive material to form a redistribution layer, preventing corrosion without the need for a metal cap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If photolithography process is used to form redistribution layer on connection pad, then redistribution function is achieved, but connection pad corrosion occurs due to chemical agent contact
Solution Approach 1:
A metal cap layer is introduced as an intermediary between the chemical agents (developer, cleaning solution) and the aluminum connection pad. This cap layer acts as a protective mediator that prevents direct contact and corrosion while allowing the photolithography process to proceed normally on the redistribution layer.
Solution Approach 2:
The metal cap layer is formed in advance before the photolithography process that uses chemical agents. This preliminary protective action prevents the harmful effect of chemical agent contact with the connection pad before the corrosion can occur.
2Ease of operation
If passivation layer is removed to form via hole, then connection pad exposure is achieved, but chemical agent contact and corrosion occur
Solution Approach 1:
The metal cap layer serves as an intermediary protective layer that remains in place during via hole formation. It allows the via hole to be formed through the passivation layer and insulating layer while preventing chemical agents from reaching and corroding the connection pad underneath.
Solution Approach 2:
The metal cap layer is formed preliminarily before the via hole formation process. This preliminary action ensures that when the passivation layer is removed to create the via hole, the connection pad is already protected from subsequent chemical agent exposure.
3Object-affected harmful factors
If metal cap process is added to prevent corrosion, then connection pad protection is improved, but manufacturing complexity increases
Solution Approach 1:
The metal cap formation process is merged with the existing photolithography and sputtering processes. The same equipment and process steps used for forming the redistribution layer are also used to form the metal cap layer, eliminating the need for separate dedicated capping equipment or processes.
Solution Approach 2:
The metal cap layer serves multiple functions: it acts as a protective barrier against corrosion, provides a planar surface for subsequent processing, and can serve as an additional conductive layer. This multi-functionality reduces the need for separate protective measures and simplifies the overall process.
4Reliability
If additional capping process is implemented, then corrosion prevention is achieved, but process time and cost increase
Solution Approach 1:
The metal cap formation is combined with the existing redistribution layer formation process. Both layers are deposited using the same sputtering equipment in sequence, eliminating the need for separate processing steps and reducing overall manufacturing time.
Solution Approach 2:
The metal cap is formed preliminarily before the photolithography and via hole formation steps. This timing allows the protective layer to be in place during potentially corrosive chemical processes, preventing the need for later remediation or additional protective measures that would extend process time.
Data Source
AI summary
The method of manufacturing a connection structure of a semiconductor chip includes: preparing a semiconductor chip having a first surface having a connection pad disposed thereon and a second surface opposing the first surface and including a passivation layer disposed on the first surface and covering the connection pad; forming an insulating layer on the first surface of the semiconductor chip, the insulating layer covering at least a portion of the passivation layer; forming a via hole penetrating through the insulating layer to expose at least a portion of the passivation layer; exposing at least a portion of the connection pad by removing the passivation layer exposed by the via hole; forming a redistribution via by filling the via hole with a conductive material; and forming a redistribution layer on the redistribution via and the insulating layer.