Probe Pad Interconnection Structure for Controlled 3DIC Bonding
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Solution Overview
Problem
The semiconductor industry faces challenges in efficiently forming 3DIC structures with reduced interconnect lengths, which affects integration density, speed, and bandwidth.
Innovation Solution
The method involves forming a semiconductor structure with a pad structure having a probe mark recessed from the dielectric cap into the metal pad, a protective layer covering the pad structure, and a bonding structure with a bonding dielectric layer and a bonding metal layer that penetrates through the protective layer to contact the pad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bonding structure penetrates through the protective layer to contact the pad, then reliable electrical connection is achieved, but the risk of over-etching and damage to the pad increases
Solution Approach 1:
The probe mark is formed in advance on the pad structure before the bonding process. This preliminary marking defines the exact location where the bonding structure should penetrate, guiding the etching process to stay within safe boundaries and prevent over-etching that could damage the pad while ensuring reliable electrical connection.
2Measurement precision
If the probe mark is recessed from the dielectric cap into the metal pad, then accurate alignment for bonding is achieved, but the complexity of the fabrication process increases
Solution Approach 1:
The probe mark is created as a recessed feature during the pad formation process, serving as a pre-established alignment reference. This preliminary structural feature provides accurate positioning for subsequent bonding operations without requiring complex external alignment systems or multiple adjustment steps.
Solution Approach 2:
The probe mark structure serves dual purposes: it acts as both a mechanical feature for probe contact during testing and an alignment reference for the bonding process. This self-service feature eliminates the need for separate alignment marks, reducing fabrication complexity while maintaining high alignment precision.
3Reliability
If the bonding metal layer penetrates through multiple layers to contact the pad, then electrical connectivity is established, but the risk of damaging underlying structures increases
Solution Approach 1:
The probe mark recess is formed before the bonding metal layer deposition and penetration processes. This pre-formed recess acts as a controlled pathway that guides the bonding structure's penetration, ensuring it reaches the pad through a predetermined safe route and minimizing the risk of damaging surrounding or underlying structures while establishing reliable electrical connectivity.
Data Source
AI summary
Provided is a semiconductor structure including an interconnect structure, disposed over a substrate; a pad structure, disposed over and electrically connected to the interconnect structure, wherein the pad structure comprises a metal pad and a dielectric cap on the metal pad, and the pad structure has a probe mark recessed from a top surface of the dielectric cap into a top surface of the metal pad; a protective layer, conformally covering the top surface of the dielectric cap and the probe mark; and a bonding structure, disposed over the protective layer, wherein the bonding structure comprises: a bonding dielectric layer at least comprising a first bonding dielectric material and a second bonding dielectric material on the first bonding dielectric material; and a first bonding metal layer disposed in the bonding dielectric layer and penetrating through the protective layer and the dielectric cap to contact the metal pad.