Photolithographic mask

This technique is used to transfer a computer-generated pattern onto a substrate. Here, a film of photoresist is spin-coated onto the substrate and exposed to UV light through a photolithographic mask the light exposure transfers the desired pattern to the photoresist. Depending on whether the resist material is positive or negative , the photoresist... 

To determine the effect of spot size, various photolithographic masks were used to create arrays of square patterns at spot widths from 80 to 1145 p. The Kjjpp ( 1 standard deviation) did not vary over the spot size range of 80 to 1145 p under constant flow conditions at fixed levels of antigen concentration, and little effect of variation in spot size was noted on mean binding. 

Fig. 1. Light-directed synthesis of polynucleotide probe arrays. Exposure to light through a photolithographic mask is used to remove protecting groups from surface sites in pre-defined regions of a functionalized glass substrate. A solution of an activated polynucleotide building block is then applied, which reacts specifically in the exposed regions of the substrate. Repeated cycles of illumination-deprotection and monomer coupling are used to construct a two-dimensional array of probe sequences...

Micro-arrays can be manufactured in two different ways, by synthesis in situ or by delivery. In the in situ synthesis approach, nucleic acids are synthesized directly on a chip surface. This is made possible by a light-directed chemical synthesis technology developed by scientists at Affymetrix. By using different sets of photolithographic masks, scientitsts can define the chip exposure sites and, thereby, the sequence of the oligonucleotides. In this way, arrays can be synthesized with up to 400,000 different oligonucleotides in an area of 1.6 cm. Every spot contains about... 

Bulk micromachining relies on several etching techniques and creates projections of planar photolithographic masks in 3 dimensions. Surface micromachining relies on sacrificial layer and wafer bonding techniques. It creates true 3D structures as a stack of 2D patterned layers. Hence, it is more correct to refer to both micromachining techniques as two and a half dimensional (2% D). 

Figure 5.9 Novel fabrication process for the second generation of micromachined electrospray emitter tips silicon support wafer (blue), 200 nm thick nickel etch-release layer (white) which is patterned using a HN03-based wet etch, negative photoresist SU-8 which forms the micro-nib support layer and tip which hosts the capillary slot (gold) and single photolithographic masking layer which defines the reservoir and tip (black).

Fig. 12.20. Fabrication of single grain boundaries. The lines indicate the CuOg planes of the aligned a-axis region on a PBCO buffer layer and the shaded areas show the c-axis region on the bare substrate. The black pattern is the photolithographic mask used for defining the four measurement lines the BPF and the twist grain boundaries, and the [010] and [001] leads in the a-axis film.

With the same number of chemical steps, the diversity and number of peptides synthesized using light-directed, spatially addressable chemical synthesis depends, among other factors, on the patterns of photolithographic masks used for each photodeprotection. Different masking strategies can be used. 

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