| 摘要 |
<p>A silicon wafer (2-8) having surface structures of different depths or heights on one or both sides, e.g. for use as an integral part of a micropump is produced by a particular process. In order to reduce the number of photolithographic steps in a production process requiring several etching or growing steps, the starting wafer (3) comprises a central layer (8) which is covered on both sides with oxide layers (9a, 10) of different thicknesses. In a first process phase both oxide layers (9a, 10) receive surface cavities (12, 12a) which, on the side of the thinner layer (9b) completely traverse the latter, whereas they do not reach the central layer (8) on the side of the thicker oxide layer (10a). While a first etching or growing operation on the central layer (8) is carried out on the wafer (5) which only affects the side of the central layer (8) which carries the thinner layer (9a) while the other side is still entirely covered by the thicker layer (10a, 10c), the second etching or growing step on the central layer (8) is carried out after the thicker layer (10a) has been reduced such as to expose the central layer (8) at the initially formed cavities (12a). Thus, the depressions (14) formed at the side of the initially thicker oxide layer during this second etching step on the central layer are less deep, or in the case of a growing process the first deposits are less high than the depressions (13) or deposits formed on the other side during both etching or growing steps.</p> |
