Method for the transfer of thin layers of monocrystalline material to a desirable substrate

• US 5,877,070 A
• Filed: 05/31/1997
• Issued: 03/02/1999
• Est. Priority Date: 05/31/1997
• Status: Expired due to Term

• Current Assignee: Max Planck Society
• Original Assignee: Max Planck Society
• Inventors: Tong, Q.-Y., Goesele, Ulrich M.
• Primary Examiner(s): FOURSON III, GEORGE R
• Application Number:
  US08/866,951
• Time in Patent Office: 640 Days
• Field of Search: 438/406, 438/407, 438/458, 438/222, 117/915
• US Class Current: 438/458
• CPC Class Codes: H01L 21/76251 using bonding techniques
• CPC Class Codes: H01L 21/76254 with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond
• CPC Class Codes: Y10S 117/915 Separating from substrate

Abstract

A method for transferring of monocrystalline, thin layers from a first monocrystalline substrate onto a second substrate, which may have a substantially different coefficient of thermal expansion than the first substrate is realized by producing hydrogen-traps in the first substrate by a first implantation and then implanting hydrogen followed by a heat-treatment to weaken the connection between the implanted layer and the rest of the first substrate, then forming a strong bond between the implanted first substrate and the second substrate and finally using another heat-treatment in order to split the monocrystalline thin layer from the rest of the first substrate by the formation, growth and overlapping of hydrogen filled microcracks. In the case of substrates with different thermal expansion coefficients the heat-treatment for splitting must be and can be at a temperature lower than a critical temperature at which the bonded pair degrades due to the mechanical stresses caused by the different expansion coefficients of the bonded-pair structure. In an alternate approach only hydrogen implantation, wafer bonding and splitting steps are used under the additional condition that the hydrogen implantation temperature of must be higher than the temperature at which the transfer of the layer is accomplished.

Claims

1. A method for transferring an upper portion of a monocrystalline, first substrate to a second substrate, 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 an element at a hydrogen trap-inducing implantation temperature which is kept below that temperature at which implantation-induced hydrogen-traps are annealed, said element selected from that group consisting of boron, carbon, phosphorus, nitrogen, arsenic and fluorine, said element having an element depth distribution after implantation in said first substrate, said element distribution having a 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×

10¹⁶ per square centimeter but greater than 1×

10¹³ per square centimeter;

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,

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.

2. A method for transferring an upper portion of a first substrate to a second substrate according to claim 1, wherein said first substrate is a monocrystalline substrate with an epitaxial layer.

3. A method for transferring an upper portion of a first substrate to a second substrate according to claim 1, wherein at least one of said first and said second substrates possesses at least one thin surface layer selected from that group of surface layers consisting of polycrystalline surface layers and amorphous surface layers.

4. A method for transferring an upper portion of a first substrate to a second substrate according to claim 2, wherein at least one of said first and said second substrates possesses at least one thin surface layer selected from that group of surface layers consisting of polycrystalline surface layers and amorphous surface layers.

5. A method for transferring an upper portion of a first substrate to a second substrate according to claim 1 wherein said first substrate is monocrystalline and said first substrate is selected from that group consisting of silicon carbide, silicon, germanium, diamond, germanium, and alloys essentially of silicon and germanium with carbon.

6. A method for transferring an upper portion of a first substrate to a second substrate according to claim 1, wherein said second substrate is selected from that group consisting of silicon, oxidized silicon, glass, fused quartz, sapphire, and silicon carbide.

7. A method for transferring an upper portion of a first substrate to a second substrate according to claim 5, wherein said second substrate is selected from that group consisting of silicon, oxidized silicon, glass, fused quartz, sapphire, and silicon carbide.

8. A method for transferring and bonding an upper portion of a first substrate to a second substrate according to claim 4 wherein said epitaxial layer is selected from that group of epitaxial layers consisting of III-V compound epitaxial layers.

9. A method for transferring and bonding an upper portion of a first substrate to a second substrate according to claim 4 wherein said first substrate is selected from the group of germanium and silicon carbide and said epitaxial layer is selected from that group of epitaxial layers consisting of gallium arsenide and gallium nitride epitaxial layers.

10. A method for the transfer of an upper portion of a monocrystalline, first substrate to a second substrate, 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 implantation at a hydrogen implantation temperature, wherein said hydrogen implantation temperature is greater than 250 degrees centigrade, said hydrogen selected from the group consisting of normal hydrogen and deuterium, said hydrogen having a hydrogen concentration depth distribution in said first substrate, said hydrogen concentration depth distribution having a hydrogen concentration maximum, said depth concentration maximum essentially dividing said first substrate into said upper portion and said lower portion said hydrogen implantation being shorter in duration 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, said bonding selected from the group consisting of direct bonding and anodic bonding;

subjecting said bonded structure to a transfer heat-treatment treatment, said transfer heat-treatment treatment being carried out at a temperature which is less than said hydrogen implantation temperature for a sufficiently long time to grow hydrogen induced microcracks which overlap in a region adjacent to said maximum in said hydrogen concentration depth distribution 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.

11. A method for transferring an upper portion of a first substrate to a second substrate according to claim 10, wherein said first substrate is a monocrystalline substrate with an epitaxial layer.

12. A method for transferring an upper portion of a first substrate to a second substrate according to claim 10, wherein at least one of said first and said second substrates possesses at least one thin surface layer selected from that group of surface layers consisting of polycrystalline surface layers and amorphous surface layers.

13. A method for transferring an upper portion of a first substrate to a second substrate according to claim 11, wherein at least one of said first and said second substrates possesses at least one thin surface layer selected from that group of surface layers consisting of polycrystalline surface layers and amorphous surface layers.

14. A method for transferring an upper portion of a first substrate to a second substrate according to claim 10 wherein said first substrate is monocrystalline and said first substrate is selected from that group consisting of silicon carbide, silicon, germanium, diamond, germanium, and alloys essentially of silicon and germanium with carbon.

15. A method for transferring an upper portion of a first substrate to a second substrate according to claim 10, wherein said second substrate is selected from that group consisting of silicon, oxidized silicon, glass, fused quartz, sapphire, and silicon carbide.

16. A method for transferring an upper portion of a first substrate to a second substrate according to claim 10, wherein said hydrogen implantation temperature is greater than 200 degrees centigrade and less than 800 degrees centigrade and said first substrate is essentially silicon.

17. A method for transferring an upper portion of a first substrate to a second substrate according to claim 10, wherein said hydrogen implantation temperature is greater than 500 degrees centigrade and less than 1,100 degrees centigrade and said first substrate is essentially silicon carbide.

18. A method for transferring and bonding an upper portion of a first substrate to a second substrate according to claim 11 wherein said epitaxial layer is selected from that group of epitaxial layers consisting of III-V compound epitaxial layers.

19. A method for transferring and bonding an upper portion of a first substrate to a second substrate according to claim 13 wherein said epitaxial layer is selected from that group of epitaxial layers consisting of III-V compound epitaxial layers.

20. A method for transferring and bonding an upper portion of a first substrate to a second substrate according to claim 19 wherein said first substrate is selected from the group of germanium and silicon carbide and said epitaxial layer is selected from that group of epitaxial layers consisting of gallium arsenide and gallium nitride epitaxial layers.