One of the earliest articles that I shared in 1996, the first year of Micscape's publication, was entitled 'How Small Can You Write'. My interest in microwriting was piqued by studying a microphotograph slide that showed The Lord's Prayer (below left). This slide was in a box of slides circulated by the Postal Microscopical Society. The block of text was 0.38 x 0.28 mm with text 13 - 25 microns high which could be read comfortably with a 40X objective.
At a similar time the NCR Microform Bible presented on microfiche was also available and acquired one of these to study (below lower left and right). The block of text was 33 x 33 mm and contained the entire 1,245 pages of the King James bible. Each text character was ca. 8 microns high.
The article also noted with web links the technological advancements such as SCRIBE (Sub-nanometre Cutting and Ruling with an Intense Beam of Electrons) which could present the entire 29 vols. of Encyclopaedia Britannica on a pinhead. Also the pinnacle of microwriting, manipulating atoms to form characters by IBM Almaden's laboratory.
Recently I stumbled on a number of outlets that were offering 'nano bibles' etched on silicon chips using photolithography, the technique used to etch the multilayers of integrated circuits. This new form of microwriting revived my interest. Since the first article I had setup a Zeiss Photomicroscope with epi-DIC and seemed an interesting subject to explore by this technique. The outlets present the chip in the form of jewellery and to date despite enquiries have not found a supplier prepared just to sell the chip so selected the cheapest presentation form.
Initially I would have preferred not to interfere with the jewellery piece but found that the raised outer mount (below left) prevented an objective above 16X to be used where the text was small. My microscopic curiosity overcame this reticence and after a long unsuccessful struggle with various solvents resorted to removing the chip manually*. Being extremely brittle despite best efforts it did not survive completely intact but did not matter for narrow field microscopy studies. A neat pendant on its supplied silver necklace was fashioned from the remainder of the piece to be passed on. *On completion a technique that did not try which may be more successful is to heat the piece on a gas hob to carbonise the glue securing the chip in the open mount to powder.
The removed chip could now be studied by the 40/0.85 Zeiss Inko Epiplan objective and image shared below. A Zeiss Inko 80/0.95 dry Epiplan was also tried but the depth of field was so small that was less successful on presenting an area of text in focus in a single image. The maker's booklet supplied with the jewellery describes the process and materials used in its preparation.
Left. Stereo microscope view. This example presents the New Testament in Greek. The whole chip is 5 x 5 mm (in this case surrounded by a raised border as part of a pendant). The blocks of text for the chapters can be seen with each line of text continuous across the chip width. So the earlier books have the largest text blocks with smaller for the letters and larger again for Revelation.
Right. Zeiss 40/0.85 POL epi-DIC with lambda plate. 1.25X Optovar. There wasn't a striking delineation of colour under DIC as often seen with for example integrated circuits.
The outlet's website and informative booklet supplied notes the text is 600 nm wide (0.6 um) but offers rather contradictory information on how to read. It correctly notes the limit of a light microscope is 0.2 um (i.e. 3X smaller than the text on the chip) but remarks that a 'special Electron Microscope' is required to view the text. An EM would give a splendid image of course but an optical microscope with epi-objectives and axial lighting is readily capable of reading. Possibly also with standard medium mag objectives and side lighting if a good enough working distance if the chip unmounted or in a flush mount. The outlet's 'Technology' website page states the images shown were taken on a 'confocal mcroscope' but the image info' bars state a Zeiss GeminiSEM. The FAQ page is correct stating a 'professional microscope at 1000X' can be used to read if referring to an optical model.
This is very undemanding photolithography compared to the current state of the art although ca. ten times better reduction than the microfiche. With the drive to squeeze more circuitry on even smaller chips, 3-5 nm 'manufacturing process nodes' are now being used. Extreme UV (EUV) photolithography (wavelength 13.5 nm) is now used for the current most advanced chips, the UV created by firing a plasma at tiny droplets of vapourised tin. The UV is focussed through the larger photographic template onto the chip surface using reflective optics. A maker of these state of the art machines is ASML based in the Netherlands, the machines are massive. The technology involved is a fascinating read on their website.
So in due course when such chips become even cheaper, there maybe new claims to present the world's smallest bible, truly living up to its current genre name 'nano bible'!