Epitaxial growth of Cu(001) thin films onto Si(001) using a single-step HiPIMS process

Abstract

We report on a new route to grow epitaxial copper (Cu) ultra-thin films (up to 150 nm thick) at ambient temperature on Si(001) wafers covered with native oxide without any prior chemical etching or plasma cleaning of the substrate. It consists of a single-step deposition process using high power impulse magnetron sputtering (HiPIMS) and substrate biasing. For a direct current (DC) substrate bias voltage of −130 V, Cu/Si heteroepitaxial growth is achieved by HiPIMS following the Cu(001) [100]//Si(001) [110] orientation, while under the same average deposition conditions, but using conventional DC magnetron sputtering, polycrystalline Cu films with [111] preferred orientation are deposited. In addition, the intrinsic stress has been measured in situ during growth by real-time monitoring of the wafer curvature. For this particular HiPIMS case, the stress is slightly compressive (−0.1 GPa), but almost fully relaxes after growth is terminated. As a result of epitaxy, the Cu surface morphology exhibits a regular pattern consisting of square-shaped mounds with a lateral size of typically 150 nm. For all samples, X-ray diffraction pole figures and scanning/transmission electron microscopy reveal the formation of extensive twinning of the Cu {111} planes.

Role of ionization fraction on the surface roughness, density, and interface mixing of the films deposited by thermal evaporation, dc magnetron sputtering, and HiPIMS: An atomistic simulation

“…These results are in agreement with the recent experimental comparison of Cu films deposited on Si with a native oxide using dcMS and HiPIMS. 58 At identical conditions, only Cu deposited by HiPIMS can pass through the native oxide and form epitaxial film. Fig.…”

“…28 The existence of stacking fault areas has also been verified experimentally by polar mapping of the (111) planes in the epitaxial Cu deposited by thermal evaporation 59 and HiPIMS. 58 Also we have recently demonstrated experimentally the existence of twin boundaries in epitaxial Ni 80 Fe 20 (at. %) film deposited with both dcMS and HiPIMS.…”

Combining Electrosynthesis with Thermolysis: A Safe/Scalable Route to Multinary Oxide Semiconductor Films

“…Note that a preferred orientation of the (111) plane was observed, consistent with reported XRD data for copper thin films. [31,32]…”

Phase separation within NiSiN coatings during reactive HiPIMS discharges: A new pathway to grow NixSi nanocrystals composites at low temperature

“…Indeed, reactive HiPIMS discharges, even in the absence of an applied substrate bias, are well-known to provide ion-assisted growth, where the deposited flux is composed to a large fraction of metal ions having an average kinetic ion energies of 15-20 eV and a neutral sputtered flux with a kinetic energy of 2 eV. 57,58 The use of a continuous substrate bias, here -100V, can provide additional kinetic energy (+100 eV) to the incident ions species at the substrate surface, resulting in a higher adatom mobility during the film growth and ultimately leads to a reduction of intracolumnar as well as intercolumnar porosity, as shown by Petrov et al 47 Under such conditions, dense Ni 1-x Si x N y films can be grown even in the absence of substrate heating, which corresponds to zone 3 in the extended structure zone diagram, where energetic ion bombardment is taken into account. 59 Films grown with very low N content, i.e.…”