Process for measuring the dimensions of a spacer

Claim 1

A process for measuring the dimensions of a spacer comprising: forming on a substrate an array of parallel stripes, each stripe having a rectangular cross section; forming spacers on the lateral edges of said parallel stripes, said spacers exhibiting, according to a cross section, a width l corresponding to the distance separating the edge of the stripe from the external edge of the spacer at their contact point with the substrate, and an angle θ formed, with the substrate plane, by the tangent to the external edge of the spacer at the substrate; during the manufacturing step of spacers or following this step, lighting the array through a monochromatic light beam, the diffracted light of which supplies a diffraction pattern comprised of a main light spot corresponding to the specular reflection and of a multiplicity of aligned and adjacent diffraction spots, the envelope of which exhibits a major lobe (L0) including the main spot and secondary lobes among which the first lobe (L1) is adjacent to the major lobe (L0); measuring the sum of light intensities (IL1) of a predetermined number of spots pertaining to said first lobe (L1); deducting therefrom the width l and angle θ of the spacer according to the following formulas: l=k1×IL1+k2 θ=k3×IL1+k4 wherein k1, k2, k3 and k4 are coefficients previously determined with spacers having known dimensions.