method for testing a variety of on a single halbleiterscheibe produced simultaneously the same semiconductor components with pn transition

摘要

1332586 Testing semi-conductor components SIEMENS AG 5 Aug 1971 [18 Aug 1970] 36754/71 Heading G1U [Also in Division H1 In a method of simultaneously producing plural identical semi-conductor components each having at least one p n junction in the face of a single wafer and thereafter subdividing the wafer, the individual components are tested by bringing the wafer face in contact with an electrolytic bath Fig.1 (not shown) capable of anodic oxidation wherein a potentiometrically controlled direct current is applied between a cathode and the rear face of the wafer, which is retained and contacted by a suction tube. An insulant layer protects the blocking junctions intermediate the front and rear of the wafer from the electrolyte. A control voltage appears between the faces of the wafer, and the fronts of the elements whose breakdown voltage is in defect of this are anodically oxidized or have material removed therefrom so as to permit recognition, by colour change or removal of electrode material; and satisfactory elements remain unchanged. The rear of the wafer may have a common electrode if it comprises plural zones inset to a common n zone. If however plural n zones are inset to a common p zone, plural contacts are applied to the individual zones of the rear surface with current reversal, the common zone is immersed, and oxidation or removal occurs on that surface in positions opposed to faulty components. Alternatively the wafer may be the cathode to a solution of a salt of the contact electrode metal, and metal deposition occurs on the faulty components; or the p n junctions of the system may receive alternating current excitation whose peak approximates the required current tolerance, when deposition will occur in satisfactory components; the wafer surface being connected to form a negative electrode and the junctions biased in the sense of current flow. In e.g. an array of planar diodes Fig.2 (not shown) formed by diffusion of p type zones into a n type wafer through apertures of a S i O 2 mask, the p zones contact the electrolyte while the n zone is negatively connected in relation to the p zone. A shortcircuited element is coated with metal on negative halfwaves which is removed on positive halfwaves, while an intact element is reverse biased during positive halfwaves so that the metal remains deposited. Negative peaks exceed the diode diffusion voltage while positive peaks do not exceed its breakdown voltage. A. C. may be superimposed on positive D.C. by connecting a rectifier across an A. C. fed potentiometer with negative peak voltage exceeding the applied direct voltage to metallize those elements whose reverse voltage exceeds the positive direct voltage; the sum of which with the positive peak does not exceed the reverse voltage.