Photolithography process for repetitive patterns over a large area

摘要

The invention relates to a photo-etching process for the production of superimposed etch patterns using a small number of masks in order to reduce the costs. This invention is especially applicable to the production of colour display screens for beam-indexation tubes. These screens comprise three patterns of colour-luminophore strips R, G(V), B separated by a pattern of opaque strips N; a pattern of indexation strips I is also provided. Although the pattern of indexation strips has a pitch Pi which can be one or two or three or four times the pitch Pn of the opaque array (network), whereas the pitch of the colour luminophores is three times that of the opaque array, all the patterns are etched using a single mask having openings of width LM equal to the width Li of the narrowest strips (in practice the indexation strips), these openings of the single mask having a spacing pitch PM equal to the lowest common multiple of the pitches of all the patterns to be produced, in this case 6Pn. Exposure is then carried out in several steps for each layer to be photo-etched. The cost of a single mask is very low compared to the cost of several very precisely registered (matched) masks. <IMAGE>