Patent ID: 6551903
Filing Date: 2003-04-22
Classification: H01L,Y02E,Y02P,Y10S

Abstract:
A method for forming a connection region for making electrical connection to a first doped semi-conductor region of a thin film semi-conductor device located beneath at least a second doped semi-conductor region of opposite dopant type, the method including the steps of:forming the first semi-conductor region with a predominant first dopant type of first dopant polarity, such that there is an excess number of dopant atoms of the first dopant type with respect to dopant atoms of a second dopant type of opposite dopant polarity in the first semi-conductor region; forming at least the second semi-conductor region over the first semi-conductor region with a predominant dopant type of the second dopant polarity, such that there is an excess number of dopant atoms of the second dopant polarity with respect to dopant atoms of the first dopant polarity in the second semiconductor region and where, in the connection region, the excess number of dopant atoms of the predominant second dopant polarity per unit area of the film in the second semi-conductor region is lower than the number of excess dopant atoms of the predominant first dopant type per unit area of the film in the corresponding first semi-conductor region; heating a column of semi-conductor material passing through the second semi-conductor region and into the first semi-conductor region in an area of the connection region of the semi-conductor device where a contact to the first semi-conductor region is required, the heating step causing the material in the first and second semi-conductor regions to increase in temperature whereby dopant mobility is increased and dopant atoms of the first dopant polarity migrate from the first semi-conductor region to the second semi-conductor region to locally change the dopant polarity of the predominant dopant type in the second semi-conductor region.