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FAQ

The resists of the ma-P 1200 series exhibit a good etch resistance. E.g. ma-P 1200 gives very good results in dry etching (as with CF4 or high density SF6/O2 plasma). The etch rates of the resists strongly depend on the etching conditions. The etching equipment has an influence, the amount of open wafer surface to be etched, the etch gas composition and all other parameters such as pressure, temperature or voltage. ma-P 1200 resists show a good thermal stability. That enables the thermal stabilisation of the resists for the subsequent plasma etching. E.g. a hardbake is recommendable at 120°C in an oven (with a temperature ramp to minimize the pattern rounding). For that also a stronger prebake is necessary. In case of a 7.5 µm thick film of ma-P 1275 that would be a prebake at 110°C for 5 – 10 min on a hotplate. We cannot deliver any more detailed data. This is nearly impossible since etching conditions can differ very much from lab to lab.
Several reasons for the formation of bubbles in the resist are possible. Big bubbles could arise if the resist was shaken too much, or if the resist has undergone a bigger temperature change. They should disappear when the resist can “relax” a while (i.e. when the bottle is kept under constant climatic conditions in the cleanroom for some time). This applies mainly for resists of a higher viscosity. Bubbles occurring during the prebake of thick resist films are caused by the solvent evaporation. It is important to maintain a certain relaxation time between spin-coating and prebake to avoid this. Only high viscosity resists show this tendency. Smaller bubbles in the exposed area could have several reasons. Adjusting the respective process condition prevents the bubble formation:
  • The resist film isn´t dry enough, i.e. it wasn´t sufficiently softbaked (= prebaked).
  • The exposure dose was much too high. This is connected with a distinctly decreased developing time compared to the one at standard processing conditions.
  • c) Too much primer was used (HMDS on Si and SiO2).
  • d) The cleanroom conditions were out of the tolerances. Especially a too high humidity can cause bubble formation.

In general ma-P 1200 positive photoresists withstand strong acids very well. Tests have shown that 2.5 µm thick ma-P 1225 and 7.5 µm thick ma-P 1275, both processed under standard conditions, resist concentrated HCl at 45…50 °C for at least 10 minutes without any problems. No erosion of the resist film is observed.
Concentrated HF is challenging for all photoresists (cf. QUESTION 4).
Also strongly oxidising acids can cause some problems. The resist stability depends on the temperature and composition of the etchant in such cases.

HF etching is a very demanding. HF doesn´t attack the resist. But it can diffuse under the photoresist and lift it from below causing bad adhesion of the resist on the substrate. This is why a film thickness as high as possible should be chosen, and the resist should be hardened (stronger prebake + hardbake). Nevertheless it depends strongly on the HF concentration and the etch time to what extend the photoresist sustains the etching.
In the literature it is mentioned that ma-P 1200 is suitable for etching with buffered HF [*]. 

[*] A. Pozzato, S. Dal Zilio, G. Fois, D. Vendramin, G. Mistura, M. Belotti, Y. Chen, M. Natali, Microelectronic Eng. 83 (2006), 884-888, doi:10.1016/j.mee.2006.01.012

For lift-off processes a bi-layer resist system can be applied. E.g. LOR (a not photosensitive polymer provided by MicroChem Corp. for various film thicknesses) can be used as bottom layer. In a second step a positive resist e.g. from the ma-P 1200 series is applied as top layer. During the aqueous-alkaline development of the exposed areas of the positive resist film also the LOR film underneath is dissolved. The undercut profile in the bottom layer is adjusted by varying the development time and the prebake conditions for the LOR layer.
For some applications you can do the lift-off with a single-layer resist which does not give an undercut profile. E.g. the use of ma-P 1200 resist without an additional bottom layer would be sufficient – preferably with a somewhat higher film thickness to give sidewalls that can be reached by the stripper. The quality of the edges of the deposited metal layer is slightly worse than in a bi-layer process in this case.

We recommend to apply “Developer Concentrate” by DOW Electronic Materials for developing resists of the ma-P 1200 series on Al and Al containing substrates. You can purchase the developer from our company. The developer is based on metasilicate which practically doesn´t corrode Al.

[1]   W. Schrott, M. Svoboda, Z. Slouka, D. Šnita, Metal electrodes in plastic microfluidic systems, Microelectronic Engineering, 86 (2009), 1340-1342; 
doi: 10.1016/j.mee.2009.01.001
ma-P 1275 is used as mould for electroplating Au and Cu structures to be used in plastic microfluidic systems.

[2]   P.W. Leech, G.K. Reeves, A.S. Holland, Reactive ion etching of TiN, TiAlN, CrN and TiCN Films in CF4/O2 and CHF3/O2 Plasmas, Mater. Res. Soc. Symp. Proc. 890 (2006), 0890-Y08-13.1-6;doi: 10.1557/PROC-0890-Y08-13
ma-P 1205 is used as etch mask for plasma etching in the manufacture of stamps for imprint lithography.

[3]   G. Kaltsas, A. Petropoulos, K. Tsougeni, D. N. Pagonis, T. Speliotis, E. Gogolides, A. G. Nassiopoulou, A novel microfabrication technology on organic substrates – Application to a thermal flow sensor, Journal of Physics: Conference Series 92 (2007) 012046; doi:10.1088/1742-6596/92/1/012046
ma-P 1275 is used in a lift-off process with Pt deposition in the manufacture of a thermal flow sensor.

[4]   J.-C. Galas, D. Bartolo, V. Studer, Active connectors for microfluidic drops on demand, New J. Phys. 11 (2009) 075027; 
doi:10.1088/1367-2630/11/7/075027
After reflow ma-P 1275HV is used as mask for moulding PDMS in the fabrication of active microfluidic connectors.

Element 32
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Resist Alliance

micro resist technology is a single entry point for specialty chemicals used in micro and nano manufacturing in Europe. The portfolio of in-house products is complemented by the strategic sales of associated products that are manufactured by our international partners. Here we act as a high-service distributor and offer European medium-sized companies a wide range of complementary products from a single source, which can be used for both established and innovative production and manufacturing processes.

DuPont Electronic Solutions (formerly DOW Electronic Materials / Rohm and Haas Europe Trading ApS)

We offer products for semiconductor technologies, advanced packaging and dry film resists from our partner DuPont, with whom we have been working for more than 20 years.

Kayaku Advanced Materials, Inc. (formerly MicroChem Corp.)

We offer photoresists and specialty chemicals for MEMS and microelectronic applications from our partner Kayaku Advanced Materials, with whom we have been working for more than 20 years.

DJ MicroLaminates, Inc.

We offer dry film resists for MEMS, microfluidics and packaging applications from our partner DJ MicroLaminates, with whom we have been cooperating for over two years.

Dry Films

Dry films are ready-to-use polymer films as laminate foil with a high accuracy of the film thickness and excellent adhesion behaviour on various substrates. They are very simple in handling, photo-structurable and both as cut sheets and as roll material available.

  • Available in different film thicknesses
  • UV-crosslinking as negative photoresist
  • Feasibility of high aspect ratios
  • Vertical sidewalls
  • Multi lamination possible – up to 6 layer  complex multi-layer designs
  • High chemical resilience

 

  • Application as permanent material for optical application (e.g. lenses, wave guides …), in micro fluidics

Functional materials for inkjet-printing

Special designed functional materials from the product groups Hybrid Polymers, Photoresists, and Nanoimprint Polymers for the deposition and alternative patterning using inkjet printing process

  • Available in different viscosities (adjustable)
  • Suitable in commercial inkjet printing devices
  • Focused on high reliability of droplet generation
  • UV-curable formulations

 

  • Usable as a permanent material for optical application (e.g. lenses, wave guides, optical couplers, diffractive elements, …)
  • Packaging material in the micro electronic
  • Deposition / patterning on substrates with surface topography
  • Imprint material for nano-structuring with high dose accuracy

Nanoimprint Resists

Nanoimprint Lithography (NIL) is a straight forward, low cost, and high throughput capable technology for the fabrication of nanometer scaled patterns. Main application fields are photonics, next generation electronics, as well as bio- and sensor applications.

micro resist technology GmbH has provided tailor-made resist formulations for nanoimprint lithography (NIL) since 1999. The unique key features of our products are outstanding film forming and imprinting performance beside excellent pattern fidelity and plasma etch stability. Besides our highly innovative material developments in close contact to industrial needs, our strength is the ability to adjust our materials in film thickness as well as addressing certain needs of the specific use cases within the formulation. Our nanoimprint resists are mostly applied as an etch mask for pattern transfer into various substrates, like Si, SiO2, Al or sapphire.

Our portfolio covers materials for the classical thermal NIL (T-NIL), in which a thermoplastic polymer is used, as well as UV-NIL, in which a liquid formulation is photo crosslinked upon photo exposure. With our technological expertise and know-how we are able to find the right material for your process and applications. Please contact us for your technical support!

Hybrid Polymers

micro resist technology offers a broad portfolio of UV-curable hybrid polymer products for micro-optical applications. Their excellent optical transparency and high thermal stability makes them perfectly suitable for the production of polymer-based optical components and waveguides. The main fields of application are micro lenses, diffractive optical elements (DOE), gratings, and single-mode or multi-mode waveguides.

OrmoComp®: DE 30 210 075 433; IR 1 091 982 ; TW 100030626; OrmoClear®: DE 30 210 075 434; IR 1 091 359 ; TW 100030628; OrmoStamp®: DE 30 210 075 435; IR 1 092 621 ; TW 100030629; OrmoPrime®: DE 30 210 075 436

Positive Photoresists

Positive Photoresists for UV lithography (mask aligner, laser, greyscale exposure) and e-beam lithography

  • Variety of viscosities for 0.1 µm – 60 µm film thickness in one spin-coating step
  • Effective for broadband, g-line, h-line or i-line exposure, laser direct writing at 350…450 nm and e-beam lithography
  • No post exposure bake
  • Easy removal
     
  • For pattern transfer: Etch mask, mould for electroplating, mould for UV moulding
  • Use in microsystems technology, microelectronics, micro-optics – manufacture of e.g. MEMS, LEDs, ICs, MOEMS, fiber optics telecommunications devices, flat panel displays

Negative Photoresists

Photoresists for UV (mask aligner, laser)/ DUV and e-beam lithography

  • Effective for broadband and i-line, Deep UV, e-beam exposure, or laser direct writing @ 405 nm
  • Lift-off resists with tunable pattern profile, high temperature stability up to 160 °C
  • Variety of viscosities for different film thicknesses in one spin-coating step
     
  • For pattern transfer: Physical vapour deposition (PVD) and single  layer lift-off, etch mask, mould for electroplating
  • For permanent applications: Polymeric waveguides
  • Use in microsystems technology, microelectronics, micro-optics  – manufacture of e.g. LEDs, ICs, MEMS, flat panel displays, fiber optics telecommunications devices