Abstract: A proximity effect correction method for electron beam lithography suitable for high voltages and/or very dense patterns applies both backscatter and forward scatter dose corrections. Backscatter dose corrections are determined by computing two matrices, a "Proximity Matrix" P and a "Fractional Density Matrix" F. The Proximity Matrix P is computed using known algorithms. The elements of the Fractional Density Matrix are the fractional shape coverage in a mesh of square cells which is superimposed on a pattern of interest. Then, a Dose Correction Matrix D is computed by convolving the P and F matrices. The final backscatter dose corrections are assigned to each shape either as area-weighted averages of the D matrix elements for all cells spanned by the shape, or by polynomial or other interpolation of the dose correction field defined by the D matrix. The D matrix also provides a basis for automatic shape fracturing for optimal proximity correction.

Abstract: There is disclosed a temporary structure for use in exhibition stands and the like, comprising a framework comprising rectangular frame units each comprising two parallel vertical tubes and two horizontal spars, each in the form of an H with a much elongated cross member and much shortened uprights each of which provides two plugs, respectively above and below the cross member, two said plugs of each said horizontal spar being engaged in respective sockets afforded by the ends of respective ones of the two vertical tubes of the respective frame unit.In an extended structure each horizontal spar may form the lower spar of one such rectangular frame unit and the upper spar of an adjoining lower frame unit. Spring collets may be fitted around the plugs and within the sockets in which the plugs are inserted the colletts having cutting edges to score the socket walls, and having internal projections fitting in recesses in the plugs whereby a firm non-rotatable connection can be obtained.