Avoiding blistering in Al2O3 deposited on planar and black Si

Abstract

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Impact of doping and silicon substrate resistivity on the blistering of atomic-layer-deposited aluminium oxide

“…A negative correlation between large blister size and high blister density, similar to the results obtained here for varying substrate resistivities, has been shown for blistered Al2O3 stack systems deposited by spatial ALD and was attributed to a competition between lateral and vertical diffusion of hydrogen at the Si interface depending on post-anneal temperature, but no link to substrate doping was mentioned [32]. In absolute values, the blistered surface area has been reported with similar values, from 0.1 to 4 % depending on substrate treatment and post-anneal temperature [6,32], which are not in contradiction to the values between 0 and 0.35 % determined here. These values may seem rather low in general, but depending on the final desired properties and application of the Al2O3 film, blisters may be harmful even when not covering larger surface areas.…”

“…An unwanted property reported for ALD thin films, especially for Al2O3 films deposited from trimethylaluminium (TMA) and water precursors, is the formation of local delamination sites, referred to as "blisters". Increased blistering has been found to correlate with degraded surface passivation and decreased open-circuit voltage (Voc) in silicon solar cells [6,7,8,9]. In a complex segmented device, such as a pixel detector, ruptured blisters present a severe risk of short-circuits between elements in the detector, which may render the device non-functional [10].…”

“…In addition, blistering is affected by modification of the silicon substrate surface by oxidation [20], chemical cleaning [21], or plasma treatment [6].…”

AC-coupled n-in-p pixel detectors on MCz silicon with atomic layer deposition (ALD) grown thin film

“…A negative correlation between large blister size and high blister density, similar to the results obtained here for varying substrate resistivities, has been shown for blistered Al 2 O 3 stack systems deposited by spatial ALD and was attributed to a competition between lateral and vertical diffusion of hydrogen at the Si interface depending on post-anneal temperature, but no link to substrate doping was mentioned. [113] In absolute values, the blistered surface area has been reported with similar values, from 0.1 to 4 % depending on substrate treatment and post-anneal temperature [101,113], which are not in contradiction to the values between 0 and 0.35 % determined here. These values may seem rather low in general, but depending on the final desired properties and application of the Al 2 O 3 film, blisters may be harmful even when not covering larger surface areas.…”

“…Increased blistering has been found to correlate with degraded surface passivation and decreased open-circuit voltage (V oc ) in silicon solar cells. [101,102,103,104] In a complex segmented device, such as a pixel detector, ruptured blisters pose a severe risk of short-circuits between elements in the detector, which may render the device non-functional. An example of blistering between segments can be seen in Fig.…”