Creating high aspect ratio indium bumps requires a combination of high deposition rates and low substrate temperatures to balance the competing vertical and horizontal growth rates. 
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High Aspect Ratio Indium Bumps

Angstrom Engineering's® platforms have been designed to provide fine control of both variables to provide complete flexibility of the types of bumps you'd like to create. Paired with our proven automation and high-throughput capabilities, Indium Series™ becomes a workhorse evaporator for bump bond fabrication that is both easy to use and simple to maintain.

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alt = Interior of a deposition for perovskite materials. There are cooling systems and holders as well as wiring and connectors. It is a careful and precise process manufactured by Angstrom Engineering.
Film Thickness

With the base Indium Series™ platform, you can create films up to 20 μm from a single point source, in a single vacuum cycle. The deposition platform can be configured to deposit films up to 100 μm.

alt = 5-level load lock system used for rapid substrate insertion and minimizing pump down time in vacuum systems. This system expedites integration of substrates at multiple levels, enhancing productivity and efficiency in vacuum-based processes.
Superior Uniformity

Indium Series™ platforms include a motorized stage with adjustable source-to-substrate distances. For users that require highly controlled film thickness uniformity and lift-off geometry, users can adjust this distance to  > 680 mm. This will produce indium films with excellent thickness non-uniformity, and will minimize the edge-effect of the films.

alt = Close view of square-shaped indium bumps deposited on a substrate, showing the precision and uniformity achieved through indium bump deposition technology by Angstrom Engineering. The image highlights the complex pattern and consistent size of the bumps.
Source and Substrate Cooling

Due to Indium's low melting point, keeping the source and substrate fixturing cool is essential for growing textured indium films with small grain sizes and high shear strength. Indium Series™ utilizes a liquid-cooled substrate stage with the capability of fluid temperatures lower than -70° C, up to +150° C and includes a water-cooled shroud around the source to contain the deposition plume only to the substrate.

alt = Two views of stage movement in an Angstrom Engineering indium deposition machine. The left side shows the stage in a lowered position, while the right side displays it elevated. The vertical movement shown is significant in controlling the throw distance during the deposition process. The clean, metallic surroundings reiterate the precision of the engineering of the equipment
High Indium Deposition Rates

Highly stable and controllable indium depositions at rates between 1 to 100 Å/sec makes for very accurate and repeatable thickness termination. Even at extreme deposition rates, you can maintain indium bumps with excellent sheer strength, small grain size, and good lift-off yield. Finely tuned columnation control is achieved by utilizing throw distance and source aperture control.

Dr. Peter Lomax
University of Edinburgh, UK

We have an Angstrom Engineering sputter platform, as well as an electron beam evaporation tool. The software has made both systems, which are used for a wide range of materials, simple to use. Furthermore, the ability for the Angstrom team to remotely connect to the software and platform has been particularly useful.  We have been very impressed with the level of communication from Angstrom Engineering, who have kept us informed at all stages of the design and delivery process, offering advice on facilities when needed. Service and support have also been excellent, with very rapid turnaround when ordering materials, which have arrived as quickly as our UK-based vendors.