Solid-State Image Sensor Cu Redistribution Layer Surface Roughness
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Solution Overview
Problem
The formation of a Cu redistribution layer in chip size packages during wafer-level processing results in noticeable surface roughness, which can lead to defects in the lithography process due to the oxidation and corrosion of copper wiring.
Innovation Solution
A solid-state image sensing device with a redistribution layer comprising a barrier layer and a plated power supply layer, where the crystallinity of the Cu film is controlled by depositing it at a substrate temperature of 60 degrees or more, and the Cu film is highly oriented to Cu(111) with a strength ratio of Cu(111)/Cu(200) ≥ 200, suppressing surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cu is used as a seed layer at the time of forming a Cu redistribution layer in a chip size package of a wafer level, then the oxidation/corrosion of copper wiring is suppressed, but noticeable surface roughness is generated on the Cu wiring
Solution Approach 1:
The patent changes the crystalline orientation parameter of the Cu film from conventional orientations to highly oriented Cu(111) with a strength ratio ≥200, and controls the substrate temperature during deposition at 60 degrees or more. These parameter changes suppress surface roughness while maintaining oxidation/corrosion resistance of the Cu wiring
Solution Approach 2:
The patent uses a composite structure consisting of a barrier layer and a plated power supply layer with controlled crystallinity. The barrier layer prevents oxidation/corrosion while the plated power supply layer with Cu(111) orientation provides smooth surface, combining the benefits of both materials to resolve the contradiction between reliability and manufacturing precision
2Reliability
If surface roughness is generated on the Cu wiring, then the oxidation/corrosion protection is maintained, but defects in mask alignment in lithography process occur
Solution Approach 1:
By changing the crystalline orientation parameter to highly oriented Cu(111) and controlling substrate temperature at 60°C or more during deposition, the patent achieves a smooth Cu wiring surface that prevents mask alignment defects in lithography while maintaining the oxidation/corrosion protection through the barrier layer structure
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
The controlled crystallinity of the Cu film effectively reduces surface roughness of the wiring surface, preventing defects and ensuring smooth lithography processes.
Implementation Method 1
The Cu film is deposited at a substrate temperature of 60 degrees or more
Implementation Method 2
The substrate temperature can be increased by heating the substrate temperature to 60 degrees or more
Implementation Method 3
The substrate temperature can be increased by applying bias to the substrate to cause sputter ions entering the substrate to have high energy
Data Source
AI summary
The present disclosure relates to a solid-state image sensing device, a manufacturing method, and an electronic apparatus, in which surface roughness on a wiring surface can be suppressed. In redistribution layer forming processing, a Ti/Cu film corresponds to a barrier layer and a seed layer is formed by Ti/Cu sputtering after opening a through-silicon via. At this point, actually, degassing heating, reverse sputtering, Ti deposition, and Seed-Cu deposition are sequentially performed. As a method of depositing a Seed-Cu film having high crystallinity in deposition of the Seed-Cu film, performing deposition by increasing a substrate temperature to a high temperature is one method, and the Seed-Cu film of Cu(111)/(200) is formed by performing deposition at the substrate temperature of 60 degrees or more, and Cu haze are suppressed. The present disclosure can be applied to a CMOS solid-state image sensing device used as an imaging device such as a camera.