DIODE ZENER ENTERREE ET PROCEDE DE FABRICATION

L'INVENTION CONCERNE LA TECHNOLOGIE DES SEMI-CONDUCTEURS.UNE DIODE ZENER ENTERREE CONFORME A L'INVENTION COMPREND NOTAMMENT UNE REGION DE TYPE N FAIBLEMENT DOPEE3, DES MOYENS10 ISOLANT CETTE REGION PAR RAPPORT A TOUTE AUTRE REGION DE TYPE N FAIBLEMENT DOPEE SUR LE SUBSTRAT, UNE PREMIERE REGION DE TYPE P FORTEMENT DOPEE11 QUI COMPORTE UNE PARTIE INTERIEURE DOPEE DE FACON11 QUI COMPORTE UNE PARTIE PERIPHERIQUE DOPEE DE FACON RELATIVEMENT FAIBLE, UNE SECONDE REGION DE TYPE P12, 18 DONT UNE PARTIE AU MOINS CHEVAUCHE LA PARTIE PERIPHERIQUE DE LA PREMIERE REGION DE TYPE P, ET UNE REGION DE TYPE N FORTEMENT DOPEE21 QUI, EN ASSOCIATION AVEC LA PREMIERE REGION DE TYPE P, FORME UNE JONCTION PN ENTERREE30 QUI EST LA JONCTION ACTIVE DE LA DIODE ZENER.APPLICATION A LA FABRICATION DES CIRCUITS INTEGRES. A subsurface zener diode is formed in an N- epitaxial region formed on a P type substrate. The N- epitaxial region is isolated by a P+ isolation region. An N+ buried layer region is disposed between a portion of the N- epitaxial region and the P type substrate. A first P+ region is formed in the middle of the N- epitaxial region at the same time as the P+ isolation regions. Second and third adjacent P+ regions also are formed in the N- epitaxial region adjacent to and slightly overlapping the first P+ region, all three P+ regions terminating at the N+ buried layer. An N+ region, formed during an emitter diffusion operation, has first and second opposed edges centered within the overlapping portions of the first, second, and third P+ regions. Two other opposed edges of the N+ region extend beyond the other edges of the first P+ region, forming N+N- contacts to the N- epitaxial region, enabling it to be reverse biased without an additional N+ contact region and a corresponding metal conductor. Masking alignment tolerances in the direction of the N+N- overlap are eased, increasing overall processing yields.