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. 2024 Oct 10;17(20):4953.
doi: 10.3390/ma17204953.

The Impact of Substrate Temperature on the Adhesion Strength of Electroplated Copper on an Al-Doped ZnO/Si System

Jiun-Yi Tseng  1 , Wen-Jauh Chen  1   2 , Ping-Hang Chen  1
Affiliations

The Impact of Substrate Temperature on the Adhesion Strength of Electroplated Copper on an Al-Doped ZnO/Si System

Jiun-Yi Tseng et al. Materials (Basel). .

Abstract

This research, which involved a comprehensive methodology, including depositing electroplated copper on a copper seed layer and Al-doped ZnO (AZO) thin films on textured silicon substrates using DC magnetron sputtering with varying substrate heating, has yielded significant findings. The study thoroughly investigated the effects of substrate temperature (Ts) on copper adhesion strength and morphology using the peel force test and electron microscopy. The peel force test was conducted at angles of 90°, 135°, and 180°. The average adhesion strength was about 0.2 N/mm for the samples without substrate heating. For the samples with substrate heating at 100 °C, the average peeling force of the electroplated copper film was about 1 N/mm. The average peeling force increased to 1.5 N/mm as the substrate heating temperature increased to 200 °C. The surface roughness increases as the annealing temperature of the Cu/AZO/Si sample increases. These findings not only provide a reliable and robust method for applying AZO transparent conductive films onto silicon solar cells but also underscore its potential to significantly enhance the efficiency and durability of solar cells significantly, thereby instilling confidence in the field of solar cell technology.

Keywords: Al-doped ZnO (AZO); adhesion strength; electroplated copper; textured silicon.

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Conflict of interest statement

Author Wen-Jauh Chen was employed by the company JBAO Technology Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Scheme 1
Scheme 1
Schematic drawing of the peel test.
Figure 1
Figure 1
The SEM images of (a) the as-deposited sample, (b) Cu/AZO/Si(100), and (c) Cu/AZO/Si(200).
Figure 2
Figure 2
SEM cross-sectional image of the EP-Cu/Cu/AZO/Si(RT) sample prepared by (a) cleavage of the test sample and (b) FIB.
Figure 3
Figure 3
Peel force diagrams for the (a) EP-Cu/Cu/AZO/Si(RT), (b) EP-Cu/Cu/AZO/Si(100), and (c) EP-Cu/Cu/AZO/Si(200) samples, which were tested at an angle of 135° with a constant speed of 30 mm/min.
Figure 4
Figure 4
The relationship between peel force and substrate heating at test angles of (a) 135°, (b) 90°, and (c) 180°.
Figure 5
Figure 5
The surface morphologies of the substrates after the peel test for the as-deposited EP-Cu/Cu/AZO/Si sample (a,b) and the samples annealed at 100 °C (c,d) and 200 °C (e,f). The arrow indicates the location of area 2 in Figure 5e.
Figure 6
Figure 6
SEM images for the (a) EP-Cu/Cu/AZO/Si(RT), (b) EP-Cu/Cu/AZO/Si(100), and (c) EP-Cu/Cu/AZO/Si(200) samples after peel test. The numbers 1, 2, and 3 in (a–c) represented the zones 1, 2, and 3 of morphology. EDS spectrum for (d) zone 1, (e) zone 2, and (f) zone 3.
See this image and copyright information in PMC

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