This study presented a technique to deposit high strength and highly conductive copper thin films on glass substrates at room temperature. In this work, Cu thin films with thicknesses ~500 nm have been deposited on glass substrate by thermal evaporation technique at room temperature. After deposition, these films have been annealed at 200 °C for 10 - 40 minutes. The thickness and annealing effect on the structural and morphological properties were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The results showed that by increasing thickness the copper films crystallinity in (111) direction had been increased. Also by varying the annealing time the significant changes were observed in the films crystallinity and surface morphology.
In computer and microelectronics industry, copper plays an important role in the newest development of chip design. Aluminum are replacing by copper which is used to be the conductor of choice in transistor systems [
Thermal evaporation technique has been used to deposit the Copper thin films on glass substrate. The glass substrate were used for copper thin film deposition and washed in a solution of 1/5/5 proportion of de-ionized water/oxygenated water/ammonia and dry in air. A Vecco EB-PVD apparatus was used at a rate of 0.1 Å/sec for copper deposition. Purity of copper stock was 4N and substrate temperature was set at 70˚C and 150˚C for discrete runs. For comparison a 99.9% copper foil was used. The base pressure of the thermal evaporation system was better at 1.6 × 10−6 mbar. The samples were heated at 200˚C for different time being. The film thickness was measured by using surface Profiler (Dektak-150) systems. The crystallographic structure of films was studied by X-ray diffraction (XRD) with CoKα (λ = 0.179 nm) using Philips X’pert PRO PW3040 instrument. The morphology of the samples was examined using Cam Scan mv2300 scanning electron microscope SEM.
Copper thin films are deposited by thermal evaporation technique. After growth of thin films, they are annealed at 200˚C for 10 - 40 minutes and make three samples. During the thickness measurement process a surface profiler named Dektak-150 is used to measure a total 6400 µm, 6800 µm and 6500 µm length of samle-1, sample-2 and sample-3 respectively.
Copper thin film was deposited onto glass substrate using thermal evaporation technique at deposition power of 1000 W. After deposition, two samples were heated about 10 min, 20 min and 40 min at 200˚C (Figures 2-4). X-ray diffraction was done on all the samples to examine microstructures. Indexing is the process of determining the unit cell dimensions from the peak positions. It is the first step in diffraction pattern analysis. To index a
powder diffraction pattern it is necessary to assign Miller Indices (h k l) to each peak [
XRD analysis of the prepared sample of copper thin film was done by a Goniometer (Ultima3 theta-theta gonio, under 40 kV/30 mA―X-ray, 2θ/θ―Scanning mode, Fixed Monochromator). Data was taken for the 2θ range of 10 to 70 degrees with a step of 0.02 degree. Data for some 2θ range has given in
Peak position, 2θ | 1000 × Sin2θ | 1000 × Sin2θ/46 | Reflection | Remarks |
---|---|---|---|---|
43.4630 | 137 | 3 | (1 1 1) | 12 + 12 + 12 = 3 |
50.6161 | 183 | 4 | (2 0 0) | 22 + 02 + 02 = 4 |
Indexing has been done in two different methods and data are in
The morphology of the surface and cross-section of relatively pure copper films was examined by scanning electron microscopy. We observed three thin films and for each film SEM images were taken with three different magnitudes like 3000x, 15,000xs and 30,000xs.
The microstructure of the films was substantially affected by the annealing temperature. When the film was annealed at 200˚C, the morphology did not change much but showed better uniformity in grain size. The grains had a homogeneous distribution on the surface, however, there were some new and bigger features shown
2θ | D | 1000/d2 | (1000/d2)/77.33 | h k l |
---|---|---|---|---|
43.4630 | 2.08216 | 230.65 | 2.98 | (1 1 1) |
50.6161 | 1.80193 | 307.98 | 3.98 | (2 0 0) |
Experimental diffraction angle (2θ in degrees) | Standard diffraction angle (2θ in degrees) JCPDS copper: 04-0836 |
---|---|
43.463 | 43.297 |
50.616 | 50.433 |
by red circle which was shown in
Copper thin films were deposited by thermal evaporation method on glass substrate and its structural and morphological analysis had been investigated. The films were annealed at 200˚C for different time XRD analysis, it had been investigated that the samples had crystalline structure with the preferred orientation direction in (1 1 1) plane increases with the annealing time. Heat treatments of the copper layers after deposition were another ways to increase the grain size of the small grains created by evaporation. The temperature during deposition was identified as the biggest influence on the microstructure of the evaporated material and in the current setup the substrate temperature was completely unknown. This study had revealed that copper thin film deposition via thermal evaporation was a cheap and fast method.
M. M.Alam,Md. Nasrul HaqueMia,R.Hasan,M.Shahinuzzaman,M. K.Islam,Khan. M. NasirUddin, (2015) Study of Structural and Morphological Properties of Vacuum Coated Copper (Cu) Metal Thin Film. Materials Sciences and Applications,06,753-759. doi: 10.4236/msa.2015.68077