selective etching of cell walls. Anodic alumina is a very suitable material for microchannel plates due to presense of natural microchannels . Diameters of these channels lie in the range of 0.02 – 0.5 mm, channels of greater diameter can be easily produced by means of additional processing based on the presence of intrinsic microchannel structure. It is possible to produce MCPs with channel diameters 0.2 – 8 mm and thickness 40 – 150 mm.
Potential advantages of aluminum oxide technology
The main advantage of aluminum oxide MCP technology is formation of microchannel structure by means of group methods (instead of individual dragging of fibers with consequent agglomeration). It provides considerable reduction of prices of MCP production. Possibility to use standard microelectronics technological processes on all stages of MCP production also helps to further reduce prices. Group methods of microchannel structure formation allows also to produce MCP of significantly larger area than it’s possible with conventional technology. Channel diameters cam be made considerably smaller (down to submicron region), which increases resolution and ability to work in strong magnetic fields.
Brief description of the method of alumina MCP production
Fig. 4. MCP with etched channels
We have developed a procedure of anodic alumina MCP production [20 - 22] which consists of next stages:
· growing of anodic alumina of necessary thickness;
· separation of alumina plate from aluminum substrate;
· deposition of photolithographic mask;
· protection of nonoperational surface;
· etching of alumina through protective mask in multicomponent acidic and alkaline etchants;
· liberation of MCP matrix;
· annealing of MCP matrix.
MCP produced with that procedure is shown on the fig. 4. Fig. 5 presents magnified picture of one of the channels of that MCP.
Fig. 5. Magnified view of the etched channel of anodic alumina MCP
Anodic aluminum oxide is typical dielectric, so it’s necessary to create conductive and emissive coating on the walls of MCP channels to use it as electron multiplier. It can be done by deposition of oxide films with