FLW by Goldberg and Bohringer

Flw. Ken Goldberg and Karl Bohringer, 1996 

Material: silicon. Dimensions: 60 x 80 x 10 micrometers.

A 1/1 millionth scale model of Frank Lloyd Wright’s Fallingwater, fabricated from silicon using ultra high precision lithography. Courtesy catharine clark gallery, san francisco, ca.

Microphotography of Frank Lloyd Wright’s tiny masterpiece

“Why Fallingwater? Wright employed the cantilever: a horizontal structure for distributing force, “the true earth-line of human life” (Wright). Minature cantilevers are used to measure forces in devices etched from silicon. Examples of current research can be found at many labs including UC BerkeleyCornell and UCLA”.

“How it was made:

The flw silicon 3D structure was fabricated using a process known as SCREAM, Single Crystal Reactive Etching And Metallization. The process began by scanning in Frank Lloyd Wright’s floorplans from a book. These are then imported into a software package that we use to generate a proportional but simplified 3D model of the building with its cantilevered balconies. This model is then used by the computer to create a sequence of optical masks.


Once the masks are ready, a wafer of purified silicon is treated with a light-sensitive chemical known as photo-resist. In a clean room laboratory, the masks are then used to expose selected areas of the wafer to ultraviolet light, which renders the photoresist susceptible to dissolving in a developer solution. The first mask corresponds to the top floor of the building.The exposed areas of the wafer are washed clean with deionized water, and then a reactive ion etch is applied to the wafer. The etch occurs in a vacuum chamber where chlorine radicals are accelerated by electrostatic fields during a plasma discharge. The ions remove the silicon in unprotected areas, leaving only the patterns defined by the photoresist. The etch cuts deep into the bulk silicon, creating 3-dimensional structures. The lithographic procedure is then repeated with the next mask, etching downward from the top floor to each lower floor. Each etching procedure takes several hours including the lithography and cleaning steps. A final plasma etch with sulfur-fluoride ions is used to undercut the silicon, creating the suspended cantilevers in 48 copies of the completed structures”.



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