Method for permanent bonding of wafers

Abstract

A method for bonding of a first contact surface of a first substrate to a second contact surface of a second substrate according to the following steps: forming a reservoir in a surface layer on the first contact surface, at least partially filling the reservoir with a first educt or a first group of educts, contacting the first contact surface with the second contact surface for formation of a prebond connection, and forming a permanent bond between the first and second contact surface, at least partially strengthened by the reaction of the first educt with a second educt contained in a reaction layer of the second substrate.

Having described the invention, the following is claimed: 
     
         1 . A method for bonding of a first contact surface of a first substrate to a second contact surface of a second substrate, said method comprising:
 forming a reservoir in a surface layer of the first contact surface by exposing the first contact surface to N 2  gas and/or O 2  gas and/or Are gas and/or a forming gas comprising 95% Ar and 5% H 2 ;   at least partially filling the reservoir with one or more first educts;   forming a prebond connection by contacting the first contact surface with the second contact surface; and   forming a permanent bond between the first and second contact surface, said permanent bond being at least partially strengthened by reaction of the first educt with a second educt contained in a reaction layer of the second substrate.   
     
     
         2 . The method as claimed in  claim 1 , wherein the formation and/or the strengthening of the permanent bond takes place by diffusion of the first educt into the reaction layer of the second substrate. 
     
     
         3 . The method as claimed in  claim 1 , wherein the formation of the permanent bond takes place at a temperature between room temperature and 200° C. in an hour or less. 
     
     
         4 . The method as claimed in  claim 1 , wherein the permanent bond is an irreversible bond having a bond strength of greater than 1.5 J/m 2 . 
     
     
         5 . The method as claimed in  claim 1 , wherein, during the reaction of the first educt with the second educt, a reaction product having a molar volume that is greater than a molar volume of the second educt is formed in the reaction layer of the second substrate. 
     
     
         6 . The method as claimed in  claim 1 , further comprising plasma activating the surface layer on the first contact surface to form the reservoir,
 wherein reduced species of ions present during the plasma activating are located in the reservoir.   
     
     
         7 . The method as claimed in  claim 6 , wherein the reduced species are selected from the group consisting of: O 2 -, N 2 -, H 2 -, and Ar-ions. 
     
     
         8 . The method as claimed in  claim 1 , wherein the surface layer of the first contact surface is comprised of an amorphous material, and
 wherein the reaction layer of the second substrate is comprised of an oxidizable material.   
     
     
         9 . The method as claimed in  claim 1 , wherein a growth layer comprised of native silicon dioxide as a main component is disposed between the second contact surface and the reaction layer. 
     
     
         10 . The method as claimed in  claim 9 , wherein, before the forming of the permanent bond, the growth layer has an average thickness A between 1 angstrom and 10 nm. 
     
     
         11 . The method as claimed in  claim 1 , wherein the forming of the reservoir is performed in a vacuum. 
     
     
         12 . The method as claimed in  claim 1 , wherein the formed reservoir has an average thickness between 0.1 nm and 25 nm. 
     
     
         13 . The method as claimed in  claim 1 , wherein, immediately before the forming of the permanent bond, an average distance between the formed reservoir and the reaction layer of the second substrate is in a range of 0.1 nm and 15 nm. 
     
     
         14 . The method as claimed in  claim 1 , wherein the permanent bond is an irreversible bond having a bond strength that is twice as strong as a bond strength of the prebond connection. 
     
     
         15 . A method for bonding of a first contact surface of a first substrate to a second contact surface of a second substrate, said method comprising:
 forming a reservoir in a surface layer of the first contact surface, the formed reservoir has an average thickness between 0.1 nm and 25 nm;   at least partially filling the reservoir with one or more first educts;   forming a prebond connection by contacting the first contact surface with the second contact surface; and   forming a permanent bond between the first and second contact surface, said permanent bond being at least partially strengthened by reaction of the first educt with a second educt contained in a reaction layer of the second substrate.   
     
     
         16 . The method as claimed in  claim 15 , wherein the formation and/or the strengthening of the permanent bond takes place by diffusion of the first educt into the reaction layer of the second substrate. 
     
     
         17 . The method as claimed in  claim 15 , wherein the formation of the permanent bond takes place at a temperature between room temperature and 200° C. in an hour or less. 
     
     
         18 . The method as claimed in  claim 15 , wherein the permanent bond is an irreversible bond having a bond strength of greater than 1.5 J/m 2 . 
     
     
         19 . The method as claimed in  claim 15 , wherein, during the reaction of the first educt with the second educt, a reaction product having a molar volume that is greater than a molar volume of the second educt is formed in the reaction layer of the second substrate. 
     
     
         20 . The method as claimed in  claim 15 , further comprising plasma activating the surface layer on the first contact surface to form the reservoir,
 wherein reduced species of ions present during the plasma activating are located in the reservoir.   
     
     
         21 . The method as claimed in  claim 20 , wherein the reduced species are selected from the group consisting of: O 2 -, N 2 -, H 2 -, and Ar-ions. 
     
     
         22 . The method as claimed in  claim 15 , wherein the surface layer of the first contact surface is comprised of an amorphous material, and
 wherein the reaction layer of the second substrate is comprised of an oxidizable material.   
     
     
         23 . The method as claimed in  claim 15 , wherein a growth layer comprised of native silicon dioxide as a main component is disposed between the second contact surface and the reaction layer. 
     
     
         24 . The method as claimed in  claim 23 , wherein, before the forming of the permanent bond, the growth layer has an average thickness A between 1 angstrom and 10 nm. 
     
     
         25 . The method as claimed in  claim 15 , wherein the forming of the reservoir is performed in a vacuum. 
     
     
         26 . The method as claimed in  claim 15 , wherein the average thickness of the formed reservoir is between 0.1 nm and 20 nm. 
     
     
         27 . The method as claimed in  claim 15 , wherein, immediately before the forming of the permanent bond, an average distance between the formed reservoir and the reaction layer of the second substrate is in a range of 0.1 nm and 15 nm. 
     
     
         28 . The method as claimed in  claim 15 , wherein the permanent bond is an irreversible bond having a bond strength that is twice as strong as a bond strength of the prebond connection. 
     
     
         29 . A method for bonding of a first contact surface of a first substrate to a second contact surface of a second substrate, said method comprising:
 forming a reservoir in a surface layer of the first contact surface by smoothing the first contact surface;   at least partially filling the reservoir with one or more first educts;   forming a prebond connection by contacting the first contact surface with the second contact surface; and   forming a permanent bond between the first and second contact surface, said permanent bond being at least partially strengthened by reaction of the first educt with a second educt contained in a reaction layer of the second substrate.   
     
     
         30 . The method as claimed in  claim 29 , wherein the smoothing of the first contact surface comprises exposing the first contact surface to plasma. 
     
     
         31 . The method as claimed in  claim 30 , wherein the plasma is generated with an activation frequency between 10 and 600 kHz and/or a power density between 0.075 W/cm 2  and 0.2 W/cm 2 . 
     
     
         32 . The method as claimed in  claim 29 , wherein the first contact surface is smoothed by a viscous flow of a material of the surface layer of the first contact surface. 
     
     
         33 . The method as claimed in  claim 29 , wherein, during the reaction of the first educt with the second educt, a reaction product having a molar volume that is greater than a molar volume of the second educt is formed in the reaction layer of the second substrate. 
     
     
         34 . The method as claimed in  claim 29 , wherein a hydrophilicity of the first contact surface is increased by increasing a number of silicon hydroxyl compounds in the surface layer of the first contact surface. 
     
     
         35 . The method as claimed in  claim 29 , wherein the formation and/or the strengthening of the permanent bond takes place by diffusion of the first educt into the reaction layer of the second substrate. 
     
     
         36 . The method as claimed in  claim 29 , wherein the surface layer of the first contact surface is comprised of an amorphous material, and
 wherein the reaction layer of the second substrate is comprised of an oxidizable material.   
     
     
         37 . The method as claimed in  claim 29 , wherein a growth layer comprised of native silicon dioxide as a main component is disposed between the second contact surface and the reaction layer. 
     
     
         38 . The method as claimed in  claim 37 , wherein, before the forming of the permanent bond, the growth layer has an average thickness A between 1 angstrom and 10 nm. 
     
     
         39 . The method as claimed in  claim 29 , wherein the forming of the reservoir is performed in a vacuum. 
     
     
         40 . The method as claimed in  claim 29 , wherein the formed reservoir has an average thickness between 0.1 nm and 25 nm. 
     
     
         41 . The method as claimed in  claim 29 , wherein, immediately before the forming of the permanent bond, an average distance between the formed reservoir and the reaction layer of the second substrate is in a range of 0.1 nm and 15 nm. 
     
     
         42 . The method as claimed in  claim 29 , wherein the permanent bond is an irreversible bond having a bond strength that is twice as strong as a bond strength of the prebond connection.