Mask layers, material

After the etching, the masking layer is removed and a passivation layer 26 and detector electrodes 28 and 29 are provided. A plurality of detectors can be formed in the body. Alternatively, the whole surface of the p-type HgCdTe body can be converted into n-type material before individual detectors are formed by mesa-etching. 

A process for the production of photodiodes by a planar technique is presented in US-A-3988774 (Societe Anonyme de Telecommunication, France, 26.10.76). A thin transition layer is formed between the substrate and a dielectric masking layer necessary for local diffusion to increase the shunt resistance of the photodiodes. The shunt resistance is largely dependent on surface states of the material at the level of transition zone of n-type and p-type. 

Material of mask layers Chemical structuring Fabrication Use... 

One of the basic building blocks in MEMS processing is the ability to deposit thin films of materials in order for instance to make local zones conducting or insulating, or to use as masking layers. Film thicknesses fi om atomic layers up to several tens of /im can be achieved. The deposited film can subsequently be locally etched using the techniques described in sections 3.2. and 3.4.. MEMS deposition techniques can be classified in two groups [21] ... 

Photoimageable Discrete. In a photoimageable discrete process, resistive compositions have been dispersed in traditional solder mask-like materials, which are applied to the surface of an etched layer. Imaging and development leave the desired geometry resistor after the development step. 

The lithographic etching of highly stable materials remained a serious problem over the whole long tradition of etching. Patterning always requires mask layers. The... 

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