A perforated silicon body is described, which is made of an upper silicon plate (2) and a lower silicon plate (3). A liquid can be injected through the injection holes (4) in the upper silicon plate (2). Recesses, which form air channels (8), are made in the lower silicon plate (3). By a particular arrangement of the air channels (8), it is possible to influence the sputtering and the beam angle of the liquid flow entering through the injection holes (4). <IMAGE>
