Image readout efficiency

The image readout efficiency (a simple contrast function for lithographic resist) can be related to the ratio of the chemical or physical properties of the exposed to unexposed molecular weights. A relative comparison is given in Table VIII of various exposable compositions. 

In a positive resist the Image readout efficiency for a particular exposure dose is defined as the ratio... 

From Table XI, it can be seen that polymers have spectrum of doses necessary to obtain maximum readout efficiency. We will examine in the following example the imaging of a positive electron beam resist as a function of dose and molecular weight-solubility changes. 

In practical polymer systems the readout efficiency of the overall reaction depends on three other factors (1) the extent to which physical properties of the photopolymer composition are changed during conversion of monomer to polymer, (2) the ability of the image development system to discriminate these changes in properties and (3) the sensitivity of the process of use to detect these changes. 

MicroChannel plates are becoming widely used in spectroscopy and two dimensionaj imaging at EUV (100 - 1000 A) and soft X-ray wavelengths (10 - 100 A) for astronomy and microscopy. Although bare microchan-nel plates have low sensitivity (5% - 10% quantum detection efficiency) in this spectral region, use of photocathodes can increase substantially (to 30%-40%) microchannel plate performance. This, combined with the high spatial resolution (<50/rm), fast time response (<300 ps), and large effective area (up to 100 mm diameter) achievable with microchannel plates make the latter a very attractive and versatile tool. We discuss the properties of microchannel plates, photocathode materials, and various microchannel plate detector readout schemes that have been used for soft X-ray and EUV detection. 

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