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Thin-Film Application Methods: Vapor Deposition vs. Sputtering

Published Date
Author Cadence PCB Solutions

Key Takeaways

  • Thin-film deposition is a process within electronic design that transforms solid materials into thin, functional layers on substrates.

  • Vapor deposition is a technique that converts solid materials into a gaseous state and then deposits them as a thin film on substrates. Sputtering is a deposition technique where material atoms are ejected from a solid target and then deposited as a thin film on nearby substrates.

  • Both deposition techniques are used in ICs.

Image of the inside of a vacuum chamber with magnetron sputtering device

Magnetron Sputtering System

Within the realm of electronics design, a process called thin-film deposition transforms raw materials into functional components for things such as microchips, optical lenses, and photovoltaic panels. For Integrated Circuit (IC) manufacturing and packaging, the most applicable methods of thin-film deposition are Vapor Deposition and  Sputtering. 

Aspect

Vapor Deposition

Sputtering

Deposition Method

Sublimation or evaporation of raw material

Physical ejection of raw material atoms through ion bombardment

Film Quality

High-quality, dense film with precise thickness control

Excellent uniformity, good for film consistency

Material Compatibility

Accommodates a broad range of materials

Versatile, but some materials may not sputter effectively

Temperature Requirements

High temperatures limit its compatibility with some substrates

Low temperatures make it compatible with most substrates

Cost-Effectiveness

Generally more expensive due to the need for precise control

Generally less expensive than most vapor deposition methods

Throughput

Varies; some methods offer high deposition rates

Often boasts a higher deposition rate

Thin-Film Deposition Methods 

Vapor Deposition and Sputtering are generally the most applicable thin-film application methods for ICs. 

Vapor Deposition Techniques

Whether through sublimation, evaporation, or chemical reaction, vapor deposition is a process by which a raw material is transformed into a gaseous state and subsequently deposited onto a substrate, forming a thin film of the material on the substrate's surface. There is an array of techniques, but physical vapor deposition and chemical vapor deposition are two of the most prominent.

  • Physical Vapor Deposition (PVD): Thermal evaporation removes raw material from a solid source. The vaporized material is then transported to the substrate, where it condenses into a solid film. PVD is widely favored for its ability to produce high-quality, dense films and is frequently used in applications where precise control over film thickness is paramount.

  • Chemical Vapor Deposition (CVD): Chemical reactions between gaseous precursors deposit a solid material on the substrate through variations like laser CVD, atomic layer deposition, etc. CVD’s superior conformal coating capabilities make it suitable for complex 3D structures, integrated circuits, and protective coatings.

Sputtering Techniques

Sputtering is a process by which a solid material is bombarded with high-energy ions, ejecting molecules onto a nearby substrate to form a thin film. Within the range of sputtering techniques, there are two prominent variations.

  • Magnetron Sputtering: Magnetic fields near the target material enhance plasma confinement and ensure a more efficient, stable sputtering process. Magnetron sputtering is known for its ability to produce uniform, high-quality films with superior adhesion.

  • Ion Beam Sputtering: Ions are accelerated and focused into the target material, dislodging atoms or molecules that subsequently deposit on the substrate. Ion beam sputtering offers exceptional precision and control, making it suitable for applications demanding extreme film quality, such as optical coatings.

Comparing Methods: Vapor Deposition vs. Sputtering

The needs of the situation are what determine which thin-film deposition method is the best. If application precision and high-quality film are the goal, then vapor deposition is the most appropriate method of thin-film application. Vapor deposition is best for:

  • Semiconductor devices and integrated circuits

  • Optical coatings on corrective lenses

  • Protective coatings on tools and wear components

If application uniformity and substrate compatibility are the goal, then sputtering is the most appropriate method of thin-film application. Sputtering is best for:

  • Anti-reflective coatings and other optical applications

  • Microelectronics

  • Decorative coatings on watches, jewelry, and other items

As It Relates to Integrated Circuits

Both techniques play pivotal roles in ICs. Generally, vapor deposition is best suited for processes in IC manufacturing and sputtering is best suited for IC packaging.

Vapor Deposition in IC Manufacturing:

IC Aspect

Vapor Deposition Applicability

Dielectric Layers

Vapor deposition creates insulating layers between the metal interconnects in ICs to ensure electrical isolation between the conductive parts of the semiconductor device

Gate Oxides

Thermal oxidation—a subset of vapor deposition—creates the gate oxide layer in MOSFETs, which is fundamental to the transistor's operation

Barrier Layers

In advanced ICs, chemical vapor deposition (CVD) creates barrier layers which prevent metal diffusion into the silicon

Sputtering in IC Packaging:

IC Aspect

Sputtering Applicability

Under Bump Metallization (UBM)

Sputtering deposits the UBM, a conductive layer for the solder bump to adhere to in flip-chip technologies

Seed Layers for Electroplating

A thin seed layer of metal must be laid down prior to electroplating. Sputtering is ideal for applying seed layers

Passivation Layers

Sputtering creates robust passivation layers that protect the IC from environmental damage

Allegro X Advanced Package Designer

In manufacturing your integrated circuits and other devices using vapor deposition or sputtering–precision and efficiency are paramount. Similarly, in packing ICs, Cadence's Allegro X Advanced Package Designer offers the cutting-edge tools you need to navigate this intricate landscape effectively. Allegro X streamlines the design of complex electronic packages, ensuring seamless integration with your deposition techniques.