Maskless Non-Planar Photolithography (3DML)
Lead Research Organisation:
Durham University
Department Name: Engineering and Computing Sciences
Abstract
Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.
People |
ORCID iD |
| A Purvis (Principal Investigator) | |
| Simon Johnson (Co-Investigator) |
Publications
G Williams
(2006)
Photolithography on 3-Dimensional Substrates
Purvis A
(2007)
Photolithographic patterning of bihelical tracks onto conical substrates
in Journal of Micro/Nanolithography, MEMS, and MOEMS
Richard McWilliam (Author)
(2009)
High fidelity microlithography patterns using computer generated holograms
Richard McWilliam (Author)
(2008)
3D Maskless Holographic Photolithography using SLMs
Williams G
(2008)
A photolithographic process for grossly non-planar substrates
| Description | Photolithography is widely used by the electronics industry to pattern the tracks on printed circuit boards and the tiny features on semiconductor devices. The technique is also now starting to be used for patterning features onto non-planar surfaces, such as spiral antennae, and for realising novel electrical interconnect schemes. Manufacture of the necessary holographic masks is a major time-impediment and cost in the development of 3d photolithography. The aim of this research project was to build a 3d photolithography instrument incorporating an active device to generate the mask, rather than requiring fixed masks. The active device is similar to that employed in the now ubiquitous data projector - namely a spatial light modulator (SLM), consisting of a large array of individually-addressable liquid crystal or micromirror pixels. Our initial prototype 3d lithography instrument was based on a commercial (planar) maskless lithography tool (SF100), which contained a micromirror SLM. We evaluated potential light sources for use with the SF100, including lasers and arc-lamps. The potential advantage of a tuned-coherence arc-lamp system was recognised, though optical power levels were very low. We chose instead a high-power laser diode module with a wavelength near the edge of the visible spectrum (100 mW, 405 nm). A 'tophat' intensity profile from the laser was generated using a refractive beam reshaper. Software was developed to control the xyz_ stages of the SF100 in synchronisation with the SLM. This initial system did not prove ideal for holographic lithography due to the following issues: precise off-axis illumination required; long working distance; mode-hopping of the laser module, coupled with the off-axis illumination, caused image instability; SLM's dynamic update process reduced image fidelity. The dynamic update issue was solved by the incorporation of a custom control board. The mode-hopping issue could be eliminated by use of a mode-locked laser module, but at the expense of reduced optical power. To overcome the issues with the micromirror-based instrument we switched to another modulation technology - based on a liquid crystal on silicon (LCoS) SLM (Pluto, Holoeye GmbH). The Pluto did not suffer from the image refresh problem and could be illuminated on-axis, thus eliminating the image instability. Moreover, this technology has the potential to modulate much more complex, multi-level phase patterns, rather than the binary amplitude patterns of the SF100, thus allowing a higher diffraction efficiency. We worked directly with Holoeye to satisfy our initial concerns about using the device with 405 nm illumination. Both analytically-derived line holograms and more general iterated holograms were used to generate the required lithographic patterns. Demonstration prototypes were created using varying exposure configurations and application designs. This included simple single lines over non-planar surfaces, 300 µm pitch buses of lines descending sloped substrates and non-planar antennae. The 3d maskless lithography instrument that we developed has become the mainstay of our on-going research and development. |
| Exploitation Route | We have developed a system for the rapid patterning of features onto non-planar substrates, such as sensors, antennae and novel integrated microsystems. The 3d lithographic instrument performs exposures onto the 3d substrate and associated chemical processes allow these light distributions to be converted into a final conductive pattern. By enabling 3d patterning, the 3d lithography instrument allows devices to be built with enhanced performance. For instance, non-planar antennae can have increased bandwidth, smaller dimensions and enhanced directionality in comparison to their flat counterparts. Furthermore, they could potentially be integrated directly onto product packaging, allowing the manufacture of novel integrated systems. This research has direct consequences for the manufacture of devices that require non-planar surfaces to be patterned. We are actively using the instrument in our on-going research and development activities. Durham and Sheffield have patented the holographic lithography technology approaches, developing a small patent portfolio. This portfolio consists of one granted patent (UK, USA and Europe, thus far); a new submission on maskless 3d holographic lithography and a further submission concerned with hologram design methods. The nature of this research was to produce an instrument capable of implementing photolithography on non-planar surfaces without the manufacture of a fixed mask. We have taken an existing (related) product and modified it to allow this, in conjunction with exploring related technologies. Taking either the instrument or the generated IP to our industrial partners are the exploitation routes with the most potential. Alternative exploitation routes which we have considered to commercialise the technology include selling licences and forming a spin-out company. We have made some enquiries at this stage but a key issue is identifying a willing entrepreneur for the project. The follow on fund grant has helped in this respect to generate publicity material describing the invention and its potential. |
| Sectors | Electronics |
| Description | Grant ended more than 5 years ago but actual outcomes are continued by a more recent award EP/G051887/1 We have linked the concept of creating 3D pools of light energy to the idea of lithography so as to create 3D structures. Theory, software and applications related. Beneficiaries: Industrial Electronics Manufacturers, Academics/Industry interested in Novel 3D Device Manufacture Contribution Method: It established a new and novel manufacture process. |
| Description | Follow-on Fund |
| Amount | £87,454 (GBP) |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 12/2008 |
| End | 12/2009 |
| Description | Sub-Micron 3D Holographic Lithography |
| Amount | £557,954 (GBP) |
| Funding ID | EP/G051887/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 08/2009 |
| End | 08/2012 |
| Description | GSPK Design Ltd |
| Organisation | GSPK Design |
| Country | United Kingdom |
| Sector | Private |
| Start Year | 2006 |
| Description | Intelligent Micro Patterning |
| Organisation | Intelligent Micro Patterning |
| Country | United States |
| Sector | Private |
| PI Contribution | Intelligent Micro Patterning |
| Start Year | 2006 |
| Title | 3D Maskless Lithographic Exposure Tool |
| Description | As outlined in the grant proposal, we have created a 3D maskless Lithographic exposure tool as a prototype from an existing maskless exposure tool. |
| Type Of Technology | New/Improved Technique/Technology |
| Year Produced | 2010 |
| Impact | pending. |
| Title | Conical Spiral Antenna |
| Description | We have developed a process which has allowed us to produce a conical spiral antenna as a demonstration of holographic lithography for a real application. |
| Type Of Technology | Physical Model/Kit |
| Year Produced | 2010 |
| Impact | demonstrator unit made |
| Title | Matlab based Iterative optimisation algorithm package developed in-house |
| Description | Matlab based Iterative optimisation algorithm package developed in-house |
| Type Of Technology | Software |
| Year Produced | 2010 |
| Impact | led to patent application |