Patent ID: 6150239
Filing Date: 2000-11-21
Classification: H01L,Y10S

Abstract:
A method for transferring an upper portion of a monocrystalline, first substrate to a second substrate, said method providing both a reduced level of hydrogen implantation dose requirement and a reduced splitting temperature requirement, said first substrate consisting of said upper portion and a lower portion, said lower portion constituting a majority of said first substrate and said upper portion having a surface which is essentially flat, said method consisting of the steps of:subjecting said surface to a hydrogen trap-inducing implantation of one or more elements at a hydrogen trap-inducing implantation temperature which is kept below that temperature at which implantation-induced hydrogen-traps are annealed, said one or more elements selected from that group consisting of aluminum, gallium, indium, and thallium, said at least one element having an element depth distribution after implantation in said first substrate, said element depth distribution having an element concentration maximum, said element concentration maximum essentially dividing said first substrate into said upper portion and said lower portion, said hydrogen trap-inducing implantation having a dose less than 5.times.10.sup.16 per square centimeter but greater than 1.times.10.sup.10 per square centimeter; said hydrogen trap-inducing implantation being carried out in conjunction with hydrogen implantation;subjecting said surface to a hydrogen implantation at a hydrogen implantation temperature, wherein said hydrogen implantation temperature is kept below that temperature at which implantation-induced hydrogen-traps are annealed, said hydrogen selected from that group consisting of normal hydrogen and deuterium, said hydrogen having a hydrogen depth distribution in said first substrate, said hydrogen distribution having a hydrogen concentration maximum, said hydrogen concentration maximum occurring essentially at said element concentration maximum, said hydrogen implantation being shorter in duration than that required to produce hydrogen-induced surface blisters, said hydrogen implantation being carried out in conjunction with hydrogen trap-inducing implantation;subjecting said first substrate to a sensitizing heat-treatment at a sensitizing temperature below that temperature at which implantation-induced hydrogen-traps are annealed, for a time sufficient to form microscopic, sub-surface microcracks essentially at said hydrogen concentration maximum and parallel to said surface but shorter than that required to produce hydrogen-induced surface blisters;bonding said surface of said first substrate to said second substrate to form a bonded structure by a bonding method chosen from anodic bonding and direct wafer bonding;subjecting said bonded structure to a transfer heat-treatment at a transfer temperature, for a time sufficiently long to grow hydrogen induced microcracks which overlap in a region adjacent to said maximum in said hydrogen concentration distribution and which are essentially parallel to said surface, whereby said upper portion of said first substrate is separated by splitting from said lower portion and transferred to said second substrate.