| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a filter for filtration capable of forming a groove in which not only width but depth are accurately controlled.SOLUTION: An SOI base plate 25 comprises a lower silicon layer 23, an upper silicon layer 23 and an intermediate oxidation layer 24 sandwiched between the two silicon layers 23. An upper oxidation layer 26 of which thickness is adjusted to a predetermined value by application of thermal oxidation treatment for an adjusted treatment time is formed on an upper face of the SOI base plate 25. A mask film 27 including a flow passage opening 28 corresponding to a flow passage 13 before filtration and a flow passage 15 after filtration and slit openings 29 corresponding to respective filtration slits 14 is formed on the upper oxidation layer 26 of which thickness is adjusted. Wet etching treatment is applied to the SOI base plate 25 by ultrapure buffered hydrofluoric acid. By etching the upper oxidation layer 26 exposed at the flow passage opening 28 and the slit openings 29, a groove 30 and a groove 31 reaching the upper silicon layer 23 are formed. |
