High aspect ratio microstructures and methods for manufacturing microstructures

摘要

PCT No. PCT/US94/10164 Sec. 371 Date Jul. 18, 1996 Sec. 102(e) Date Jul. 18, 1996 PCT Filed Sep. 9, 1994 PCT Pub. No. WO96/07954 PCT Pub. Date Mar. 14, 1996A method is disclosed for the manufacture of microstructures and devices. The method is relatively easy to implement, and has the capability to produce features having a resolution of ten microns or smaller with a high aspect ratio (60, 75, 100, 200, or even higher). A master mask, appropriately designed and fabricated, is used in an initial exposure step with visible light, ultraviolet light, x-rays, an electron beam, or an ion beam to make a "transfer mask" directly on the surface of the sample. It is not necessary to produce an expensive x-ray master mask, even if x-ray exposure of the sample is desired. There is no necessity for gap control during exposure of the resist through the transfer mask. The resulting structures may, if desired, have a higher aspect ratio than microstructures that have previously been produced through other methods. The "transfer mask" is not a unit separate from the sample, but is formed directly on the surface of each sample. A conventional-type master mask is used to form the "transfer mask" with visible light, ultraviolet light, x-rays, an electron beam, or an ion beam. The total cost is determined primarily by the cost of the master mask. Because the master mask can be a conventional-type optical mask, the high cost of producing a conventional x-ray mask can be avoided. The "master mask" is used to form a "transfer mask" on each sample individually. The patterned transfer mask comprises a thin layer of an absorber of the radiation to be used in the final exposure. For example, if the final exposure is to be performed with soft x-rays, the transfer mask may be formed from an x-ray absorber such as a patterned layer of gold. The transfer mask is then used in one or more separate exposures of the underlying resist. An analogous method may be used for radiation-assisted chemistry, such as etching or deposition, on the surface of a sample.