The present invention relates to an ultrasound transducer device comprising at least one cMUT cell (30) for transmitting and/or receiving ultrasound waves, the cMUT cell (30) comprising a cell membrane (30a) and a cavity (30b) underneath the cell membrane. The device further comprises a substrate (10) having a first side (10a) and a second side (10b), the at least one cMUT cell (30) arranged on the first side (10a) of the substrate (10). The substrate (10) comprises a substrate base layer (12) and a plurality of adjacent trenches (17a) extending into the substrate (10) in a direction orthogonal to the substratesides (10a, 10b), wherein spacers (12a) are each formed between adjacent trenches (17a). The substrate (10) further comprises a connecting cavity (17b) which connects the trenches (17a) and which extends in a direction parallel to the substrate sides (10a, 10b), the trenches (17a) and the connecting cavity (17b) together forming a substrate cavity (17) in the substrate (10). The substrate (10) further comprises a substrate membrane (23) covering the substrate cavity (17). The substrate cavity (17) is located in a region of the substrate (10) underneath the cMUT cell (30). The present invention further relates to a method of manufacturing such ultrasound transducer device.