Copper Adhesion to Polymers via Nitrogen Plasma Conditioning
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Solution Overview
Problem
In semiconductor manufacturing, metal films deposited onto polymer surfaces using conventional physical vapor deposition techniques often exhibit poor adhesion due to the inherent non-conduciveness of polymeric layers, which can lead to peeling or separation of the metal layers from the substrate.
Innovation Solution
A two-step metal deposition process involving a nitrogen and argon gas mixture is used to improve adhesion, where a low-power nitrogen-containing plasma treatment creates an adhesion layer on the polymeric surface, followed by a higher power copper deposition step with a dominant argon gas mixture, resulting in enhanced metal layer adhesion and increased copper concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional physical vapor deposition techniques are used to deposit metal films onto polymer surfaces, then the deposition process is simple and fast, but the adhesion of metal layers to polymeric surfaces is poor
Solution Approach 1:
The patent applies preliminary action by introducing a nitrogen plasma treatment step before the main copper deposition process. This pre-treatment modifies the polymer surface by embedding nitrogen species and increasing surface energy, creating a more adhesive surface for subsequent metal deposition. The preliminary conditioning of the surface ensures better adhesion before the actual metal layer is deposited.
Solution Approach 2:
The patent uses an intermediary approach by depositing a thin adhesion layer (such as chromium, nickel, or titanium) between the polymer surface and the copper layer. This intermediate layer acts as a mediator that bonds to both the polymer substrate and the copper, solving the adhesion problem without requiring complex modifications to the polymer itself or the deposition process.
2Reliability
If a two-step deposition process with nitrogen plasma treatment is used, then adhesion is improved, but the processing time and complexity increase
Solution Approach 1:
The patent merges the plasma treatment and metal deposition steps into a single continuous process within the same vacuum chamber. By combining these operations without breaking vacuum or transferring the substrate between chambers, the total processing time is minimized while still achieving the adhesion benefits of plasma treatment. The nitrogen plasma conditioning and copper deposition occur sequentially in one uninterrupted workflow.
3Productivity
If high power deposition is used from the beginning, then deposition rate is high, but adhesion to polymeric surface is poor
Solution Approach 1:
The patent applies periodic action by using a two-stage deposition process with different power levels. The first stage uses low power with nitrogen plasma to prepare the surface for adhesion, while the second stage uses high power for rapid copper deposition. This periodic variation in power delivery ensures both good adhesion and high overall deposition rate, optimizing both reliability and productivity.
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 process significantly improves the adhesion of metal layers to polymeric surfaces, ensuring strong bonding and preventing peeling, particularly in applications like EMI shielding for integrated circuit packages, by altering the surface energy and embedding nitrogen species in the polymeric layer.
Implementation Method 1
a nitrogen and argon gas mixture may be used during a lower power deposition step to promote adhesion between the polymeric layer and the metal layer. Nitrogen-containing species, including but not limited to, atomic nitrogen (N), diatomic nitrogen (N2), atomic nitrogen ions (N+), diatomic nitrogen ions (N2+), metastable nitrogen (N*, N2*), etc., may impact, interact and/or embed in the polymeric layer
Implementation Method 2
Nitrogen-containing species, including but not limited to, atomic nitrogen (N), diatomic nitrogen (N2), atomic nitrogen ions (N+), diatomic nitrogen ions (N2+), metastable nitrogen (N*, N2*), etc., may impact, interact and/or embed in the polymeric layer to change the surface conditions or energy
Implementation Method 3
In semiconductor manufacturing, metal films may be sputtered by physical vapor deposition (PVD) process onto a variety of surfaces such as silicon, passivation coatings, other metals, and polymer coatings among others
Implementation Method 4
metal films may be sputtered by physical vapor deposition (PVD) process
Data Source
AI summary
Techniques disclosed herein a method and system for conditioning a polymeric layer on a substrate to enable adhesion of a metal layer to the polymeric layer. Techniques may include conditioning the polymeric layer with nitrogen-containing plasma to generate a nitride layer on the surface of the polymeric layer. In another embodiment, the conditioning may include depositing a CuN layer using a lower power copper sputtering process in a nitrogen rich environment. Following the condition process, a higher power copper deposition or sputtering process may be used to deposit copper onto the polymeric layer with good adhesion properties.