Atmospheric Plasma Head for Integration into Third Party Equipment
The OEM version of the Ontos Plasma Head is available for integration into third party equipment. The Plasma Curtain is available in several widths (down to 10mm) to enable optimization of the gas consumption on smaller devices or to adapt to larger devices.
Atmospheric Plasma. How does it work?
Ontos 7 utilizes an internal glow-discharge plasma which creates a high density stream of reactive gas radicals. As the gas flows down out of the internal plasma zone, the high-energy species (ions and hot electrons) recombine in a few microseconds, and the gas cools rapidly. But the chemically active radicals created by the plasma are still present in the downstream gas flow. It is this stream of neutral but highly reactive radicals that react with the surface of your substrate to modify the surface, chemically.
Because all of the high-energy charged plasma particles have recombined by the time the gas stream exits the aperture, the reactions on the surface are accomplished without any bombardment. This means that your substrate will NOT be subjected to sputtering damage or electric field discharge – this is very important for sensitive surfaces!
Ontos7 Atmospheric Plasma does not require a process chamber or controlled ambient. Typically, the gas aperture is spaced only a millimeter or two above your substrate. The gas flow exiting the aperture displaces the atmosphere in the space between the plasma head and the substrate. This creates an exclusion zone filled only with the downstream gas, and allows the chemical surface reactions to proceed without interference from room air.
For a comparison of Ontos7 Atmospheric Plasma to vacuum plasma systems and competing atmospheric plasma systems ⇒ Download PDF.
Do you have a surface problem ?
Process engineers know that native oxides and organic contamination on surfaces can disrupt subsequent processes such as solder bonding, wire bonding, thin film deposition, hybrid assembly, etc. Traditional methods of surface preparation, such as wet etching, fluxing, or vacuum plasma treatment, all have their drawbacks.
Atmospheric Plasma System for Surface Preparation
Ontos provides the process engineer with a new alternative – a rapid atmospheric process which reduces native oxidation and organic contamination.
Passivation of the surface against re-oxidation can also be performed – this process creates a few monolayers of modified surface that resist reaction and diffusion of oxygen – and yet is thin enough that it does not interfere with subsequent processes.
Ontos provides a simple, effective, clean surface modification method which does not require the throughput- robbing vacuum chamber associated with traditional plasma systems. Additionally, Ontos7 performs this surface modification without ion bombardment and without the cross-contamination issues often associated with conventional plasma systems.
Ontos is capable of handling both reducing or oxidizing chemistries.
- With reducing chemistry, it removes both native oxides and residual organics, and it is capable of passivating treated surfaces against re-oxidation. These attributes make Ontos7 the ideal surface preparation for semiconductor interconnect bonding.
- With oxidizing chemistry, oxygen radicals are introduced to the substrate surface to remove organics, or grow a controlled thin oxide layer on semiconductors.
Ontos performs these surface modification processes with only activated benign gasses (no halogens, no flammables, no toxics) in a low-energy atmospheric environment, making the system OSHA and EPA-friendly.
Clean and Green
Ontos patents and patents pending processes and equipment provide these benefits without the use of acids, toxics, fumes, vacuum chambers, pumps, liquids, or hazards. Ontos utilizes commonly available semiconductor-grade gasses and an atmospheric plasma source to provide local chemistry right at the surface of your part, with zero hazardous by-products or waste.
- Uniquely‐designed atmospheric plasma source with 25mm‐wide process zone (smaller or larger width available upon request). The glow discharge‐type plasma is entirely contained inside the source.
- 300 W RF generator has a wide‐range auto‐tune network, system computer control and monitoring of forward and reflected power. Safety interrupts.
- 3 Mass Flow controllers provide precise digital control of gas to the plasma source. A 4th MFC is user definable.
- Fully automatic process control with ergonomically‐mounted touchscreen display. Software developed in LabVIEW™. Menu‐driven interface with user configurable recipe libraries.
- Power: 110‐220VAC single‐phase, 15A.
- Gases: 4 channels of gas supply by ¼” stainless or Teflon tubing; Swagelok compression fittings. (All gases are non‐toxic, non‐flammable.)
- Exhaust: 1-3 cfm.
- Lab vacuum: 20‐25” Hg for stage vacuum.
- Simple apparatus – no vacuum chamber.
- Ultra-clean processing.
- Plasma is contained entirely within the process head, never contacting the chip/wafer.
- Downstream radical chemistry only.
- No exposure to: arc discharges, ions, bombardment, re-deposition, or spalling particulates.
- CMOS safe, Detector safe.
- Fast process – continuous throughput capable.
- Non-toxic, dry process. OSHA- and EPA-friendly.
- Very effective at removing organic contamination films and loose particles.
- Reduces native oxides on metallic surfaces: In, Ni, Cu, solders.
- Can add surface passivation against re-oxidation – removal not required.
ONTOS Plasma Head Main Specifications
- Chip/wafer is scanned under compact process head.
- 25mm wide process zone (rastered), Smaller or larger head available upon request.
- Typical recommended scan rate: 1-5 mm/sec.
- Process runs in room ambient.
- Programmable control of plasma.
- Easy touch-screen controller.
- Typical power to internal plasma source: 60-100 Watts.
- Made in U.S.A.
Surface Preparation for Bonding:
- SnAg, SAC, Cu, Ni, Ag, In, Au – reflow or TC bonding.
- Au-to-Au (demonstrated as low as 100°C).
- Cu-to-Cu (demonstrated as low as 250°C).
- SiO2–to–SiO2 (demonstrated at Room Temp.)
Photoresist residue removal:
- Removes all traces of post-development PR residue.
- Replaces Oxygen RIE or UV-Ozone– reduce oxides on exposed metals instead of growing them!
- Activates photoresist surface for excellent wetting during aqueous processes.
- Removes organic contamination without damaging sensitive mask materials. (EUVL-safe!)
- Enables extreme wetting for aqueous cleaning processes – spot-free.
Native oxide removal from semiconductor surfaces:
- Epi preparation.
- Remove uncontrolled air oxidation and organics.
- Capable of dangling bond passivation with Nitrogen, Oxygen, or Hydrogen.
- Zero bombardment damage.
Organic contamination removal prior to adhesive bonding:
- Very effective at removing organics, including Silicones.
- Activates surfaces for better wicking and adhesion.
Pre-plating surface preparation
- De-scums photoresist or laser-etched pattern.
- Reduces oxides from plating base.
- Activates resist surface, sidewalls, and plating base for optimum wetting.
- Even in very small geometries.
Surface Preparation for Interconnect Bonding
Ontos7 Atmospheric Plasma was developed to eliminate hydrocarbon contamination and reduce surface oxides to promote metal-to-metal bonding. The initial development was carried out on Indium to Indium compression bonding at room temperature or for reflow bonding .
The system is also capable of passivating the exposed metal surfaces against re-oxidation. This passivation is performed at the atomic level on the surface and therefore can be left in place during subsequent bonding without affecting interconnect adhesion or conduction. Consistent bonding is enabled at reduced temperatures and bond forces, compared to other surface preparation techniques.
- The presence of organics and native sub-oxides inhibit Indium-to-Indium adhesion.
- The “Skin” must be split by excessive deformation to get In-In contact (white lines above)
- This results in poor hybrid reliability
AFTER ONTOS TREATMENT
- Proper surface preparation removes organics and native sub-oxides.
- Enables instant bonding with the slightest contact.
- Results in ideal metallurgical bond with high reliability
- For applications such as 3D integration, flip chip, and other die interconnection processes, a variety of metals is used to form an electrical and mechanical bond between the two components. Native oxides and organic contamination, however, quickly form on most common bond materials, hindering the integrity of the joint and adversely affecting long-term reliability.
- This surface preparation approach has been applied to Sn, Ag, Cu, Au, Sn, In, Ni, and other metals with excellent results.
Surface activation for direct bonding.
- SiO2–to–SiO2 (demonstrated)
- Au-to-Au (demonstrated)
- Cu-to-Cu (working on it)
Semiconductor and Metal Surface Activation
With oxidizing chemistry, Ontos7 can passivate sensitive semiconductor surfaces without damaging them, and can prepare ultra-clean, ultra-activated surfaces for direct bonding: die-to-die, die-to-wafer, or wafer-to-wafer.
Ontos7 Atmospheric Plasma also produces highly activated surfaces for improved wetting, wicking, and adhesion. Activation has been demonstrated on Sn, Ag, Cu, Au, In, Ni, Al, Ti, Si, SiO2, Si3N4, Al2O3, photoresist, and FR composites.
The contact angle photos below for Tin-Silver are typical for all of the materials we have tried to date:
With reducing chemistry, comparable surface activation can be achieved while avoiding the oxidation of metal surfaces. This can be extremely useful in preparing photoresist-patterned wafers for subsequent aqueous processes such as plating, etching, anodic oxidation, etc.
Publication: ESTC 2016 paper titled ” Utilization of atmospheric plasma to improve copper plating processes”