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Technique of creation of Si/SiO2/metal structures using swift heavy ion tracks


Creation of latent tracks by Swift Heavy Ions (SHI)

Si/SiO2 substrate

Latent SHI tracks

SHI irradiation

Au26+, Xe17+,

Au26+, Xe17+
Energy 350 MeV,
Fluence 5х108 cm-2



The interaction of high energy ions with matter are formed disordered region in the matter. The degree of damage depend on the type and energy irradiating ion. At low energies of irradiation are formed unit defects in the surficial region. At intermediate energies are formed elongated defect region. At high energies are formed latent tracks on the entire thickness of the polymer film.


On slides below are shown accelerators for irradiation of the polymer by swift heavy ions.
Ion Beam Technology Centre "ISL" (Helmholtz Zentrum Berlin fuer Materialen and Energy) (Berlin Germany):

The "BIBER" chamber


Accelerator centre "GSI Helmholtzzentrum fuer Schwerionenforshung" (Darmstadt, Germany):

The "UNILAC" accelerator
Cassette for swift heavy ions irradiation



Etching of SHI tracks

Latent SHI tracks

Etched SHI tracks (pores)

Etching (HF)


Nanopores in polymer films after etching of latent tracks. Examples of nanopores for different types of polymer films: polyethylene terephthalate (PET) and polyimide (PI). The size and shape of pores have set up by parameters of irradiation and etching.

Irradiation Ar, 1 GeV => etching NaOH, 45 oC => cylindrical tracks (pores).

Irradiation Kr, 350 MeV => etching NaOCl, 70 oC => hyperbolic tracks (pores).


Advantages of the technology tracks of swift heavy ions in a flexible polymer films:

  • simplicity and more cheaper technology
  • decrease number of manufacture operations
  • devices flexibility and possibility mounting on the figurine surfaces
  • mechanical durability to various types of deformations
  • low mass-energy relation


SHI track can be transformed into a pore, if the etching rate along the track (VT) is larger than the bulk etching rate (VB), which is a rate of etching of unirradiated material beyond the SHI track area. The VT/VB ratio depends of the density of radiation damage in a latent track. Therefore a selective etching procedure of a latent track is possible if VT/VB > 1. Moreover, this parameter determines a form of the etched track.


Time characteristics of parameters of forming pores.

Dependence of SiO2 layer thickness(x), upper pore diameter (○), lower pore diameter (○) and pore depth (Δ) on the etching duration in 1.35 % HF


Pores obtained as a result of the etching.

Images of scanning electron microscopy (SEM) of surface and cross-section of the Si/SiO2 structure with pores



Metals (Ni, Cu) deposition in pores

Etching SHI tracks (pores)

Pores filled with Cu and Ni

Deposition of metals


Depending on the method of filling nanopores can create different types of nanostructures.

Examples of filled nanopores:


Deposition of metals in pores has been carried out electrochemically from a liquid phase (electrodeposition). This method makes it possible to vary such structural parameters as cluster dimensions, layer thickness, sequence of layers and morphology of deposited material by means of a change of deposition time as well as a potential on the electrode.


Specific characteristics of the method:
A large degree of the pores filling control by means of a change of deposition time at the constant potential.

SEM images of Si/SiO2/Metal structure surface  at a various deposition time values



Areas of work