Method of bonding aluminum electrodes of two semiconductor substrates
A method of bonding aluminum (Al) electrodes formed on two semiconductor substrates at a low temperature that does not affect circuits formed on the two semiconductor substrates is provided. The method includes: (a) forming aluminum (Al) electrodes on the two semiconductor substrates, respectively, and depositing a metal alloy that comprises aluminum (Al) and copper (Cu) onto the aluminum (Al) electrodes; (b) arranging the aluminum (Al) electrodes of the two semiconductor substrates to face with each other; and (c) heating the aluminum (Al) electrodes at a temperature lower than the melting point of the deposited metal alloy, and applying a specific pressure onto the two semiconductor substrates. Accordingly, bonding can be carried out at a temperature lower than the melting point of an Al 0.83 Cu 0.17 alloy without having an effect on circuits formed on two semiconductor substrates, and can be selectively carried out at regions where pressure is applied.
1. A method for bonding aluminum (Al) electrodes of semiconductor substrates, comprising:
(a) forming first and second aluminum (Al) electrodes on first and second semiconductor substrates, respectively;
(b) depositing a metal alloy that comprises aluminum (Al) and copper (Cu) onto the first and second aluminum (Al) electrodes;
(c) arranging the aluminum (Al) electrodes of the first and second semiconductor substrates to face and overlap with each other such that the metal alloy deposited on the first aluminum (Al) electrode comes into contact with the metal alloy deposited on the second aluminum (Al) electrode; and
(d) heating the aluminum (Al) electrodes at a temperature lower than a melting point of the deposited metal alloy, and applying a specific pressure onto the two semiconductor substrates,
wherein the heating and applying a specific pressure of step (d) is performed after the depositing a metal alloy onto the first and second aluminum (Al) electrodes of step (b) and arranging the aluminum (Al) electrodes to face and overlap with each other of step (c) are performed.
2. The method according to claim 1 , wherein the metal alloy is an Al 0.83 Cu 0.17 alloy.
3. The method according to claim 1 , wherein the temperature in the (d) is lower than about 540° C.
4. The method according to claim 1 , wherein the forming first and second aluminum (Al) electrodes of step (a) includes forming the first and second aluminum (Al) electrodes to each have an oval shape in cross-sectional view; and
the depositing a metal alloy of step (b) includes forming the metal alloy to have a half-circle shape in cross-sectional view, and surrounding a part of the respective aluminum (Al) electrodes with the metal alloy.