Method for detecting surface defects on a substrate and device using said method

A method for detecting surface defects, on a substrate designed to be used in electronics, optoelectronics or analogue, the method comprising:

• projecting a pattern composed of an alternation of light fringes and dark bands on the substrate, so as to generate fringes reflected by the surface of the substrate;
• relatively displacing the pattern and the substrate along at least one direction, so as to displace the fringes of the pattern on the substrate, wherein the fringes of the pattern are parallel to each other and extend parallel to a second principal crystalline axis of the substrate;
• acquiring a sequence of at least three images of the pattern reflected by the substrate by a sensor, the images corresponding to displacement of the fringes of the pattern;
• determining the gradient of the surface of the substrate using displacements of fringes of the pattern, and
• determining the presence of a surface defect on the substrate using variations in the gradient of the surface of the substrate.

A method for detecting surface defects, on a substrate designed to be used in electronics, optoelectronics or analogue, the method comprising:

• projecting a pattern composed of an alternation of light fringes and dark bands on the substrate, so as to generate fringes reflected by the surface of the substrate;
• relatively displacing the pattern and the substrate along at least one direction, so as to displace the fringes of the pattern on the substrate;
• acquiring a sequence of at least three images of the pattern reflected by the substrate by a sensor, the images corresponding to displacement of the fringes of the pattern, wherein a first sequence of images is acquired by projecting a pattern for which the fringes are parallel to each other and extend parallel to the principal crystalline axis of the substrate, said fringes being displaced along a direction perpendicular to the direction of the fringes, and a second sequence of images is acquired by projecting a pattern for which the fringes are parallel to each other and extend parallel to the second principal crystalline axis of the substrate, said fringes being displaced orthogonally to the direction of said fringes;
• determining the gradient of the surface of the substrate using displacements of fringes of the pattern, and
• determining the presence of a surface defect on the substrate using variations in the gradient of the surface of the substrate.

A method for detecting surface defects, on a substrate designed to be used in electronics, optoelectronics or analogue, the method comprising:

• projecting a pattern composed of an alternation of light fringes and dark bands on the substrate, so as to generate fringes reflected by the surface of the substrate, wherein the substrate consists of a flat disk comprising a radial notch around its periphery, forming the reference point;
• relatively displacing the pattern and the substrate along at least one direction, so as to displace the fringes of the pattern on the substrate;
• acquiring a sequence of at least three images of the pattern reflected by the substrate by a sensor, the images corresponding to displacement of the fringes of the pattern;
• determining the gradient of the surface of the substrate using displacements of fringes of the pattern;
• determining the presence of a surface defect on the substrate using variations in the gradient of the surface of the substrate;
• and
• determining the position in space of defects determined from variations in the gradient of the surface of the substrate, wherein the position in space of the defects is determined by determining the points on the surface of the substrate with a radius of curvature greater than or equal to a given threshold value and/or with a spatial distribution statistically different from the average for the substrate.

A device for the detection of surface defects, on a substrate designed to be used in electronics, optoelectronics or analogue, comprising:

• means of projecting a pattern on said substrate composed of an alternation of continuous light fringes and dark bands;
• means of introducing relative displacement of the pattern and the substrate along at least one direction, at least one sensor capable of recording displacements of fringes reflected by the substrate;
• means of determining the gradient of the surface of the substrate using displacements of the fringes of the pattern;
• means of determining the presence of a surface defect on the substrate using variations in the gradient of the substrate surface;
• and
• means of generating a laminar flow of a fluid parallel to the surface of the substrate.

A device for the detection of surface defects, on a substrate designed to be used in electronics, optoelectronics or analogue, comprising:

• means of projecting a pattern on said substrate composed of an alternation of continuous light fringes and dark bands;
• means of introducing relative displacement of the pattern and the substrate along at least one direction, at least one sensor capable of recording displacements of fringes reflected by the substrate;
• means of determining the gradient of the surface of the substrate using displacements of the fringes of the pattern;
• means of determining the presence of a surface defect on the substrate using variations in the gradient of the substrate surface;
• and
• means of determining the position in space of defects on the surface of the substrate, wherein said means of determining the position in space of defects consist of an algorithm capable of calculating the abscissa and the ordinate of the substrate of each point on the surface of said substrate with a radius of curvature greater than or equal to a determined threshold value and/or with a spatial distribution statistically different from the average of the substrate, relative to a reference point on the substrate.