Method for forming conductive bumps by performing a reflow process
An electronic apparatus including a package substrate and a structure disposed on and electrically connected to the package substrate through conductive bumps is provided. The material of the conductive bumps includes a bismuth (Bi) containing alloy or an indium (In) containing alloy. In some embodiments, the bismuth (Bi) containing alloy includes Sn—Ag—Cu—Bi alloy. In some embodiments, a concentration of bismuth (Bi) contained in the Sn—Ag—Cu—Bi alloy ranges from about 1 wt % to about 10 wt %. Methods for forming the Sn—Ag—Cu—Bi alloy are also provided.
1 . A method, comprising:
providing a package substrate comprising first conductive pads;
forming alloy patterns comprising Sn and Cu on the first conductive pads respectively;
providing a structure comprising second conductive pads;
forming alloy patterns comprising Sn and Ag on the second conductive pads respectively;
forming alloy patterns comprising Sn and X on the alloy patterns comprising Sn and Ag, wherein X represents bismuth or indium;
bonding the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Cu under a first temperature, wherein the alloy patterns comprising Sn and Ag, the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Cu remain solid state during bonding the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Cu; and
performing a reflow process under a second temperature to form conductive bumps between the first conductive pads and the second conductive pads, wherein the second temperature is higher than the first temperature.
2 . The method as claimed in claim 1 , wherein during bonding the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Cu, an intermetallic compound (IMC) layer is generated between the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Cu.
3 . The method as claimed in claim 1 , wherein the alloy patterns comprising Sn and Cu are liquid state, the alloy patterns comprising Sn and X are solid state, and the alloy patterns comprising Sn and Ag are solid state when performing the reflow process.
4 . The method as claimed in claim 1 , wherein the alloy patterns comprising Sn and Cu, the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Ag are solid state when performing the reflow process.
5 . The method as claimed in claim 1 , wherein the alloy patterns comprising Sn and Cu, the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Ag are liquid state when performing the reflow process.
6 . The method as claimed in claim 1 , wherein a material of the conductive bumps comprises Sn—Ag—Cu—X alloy, and a concentration of X contained in the Sn—Ag—Cu—X alloy ranges from about 1 wt % to about 10 wt %.
7 . A method, comprising:
providing a package substrate comprising first conductive pads;
forming alloy patterns comprising Sn and X on the first conductive pads respectively, wherein X represents bismuth or indium;
providing a structure comprising second conductive pads;
forming alloy patterns comprising Sn and Ag on the second conductive pads respectively;
bonding the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Ag under a first temperature, wherein the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Ag remain solid state during bonding the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Ag; and
performing a reflow process under a second temperature to form conductive bumps between the first conductive pads and the second conductive pads, wherein the second temperature is higher than the first temperature.
8 . The method as claimed in claim 7 , wherein during bonding the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Ag, an intermetallic compound (IMC) layer is generated between the alloy patterns comprising Sn and X and the alloy patterns comprising Sn and Ag.
9 . The method as claimed in claim 7 , wherein the alloy patterns comprising Sn and X are solid state, and the alloy patterns comprising Sn and Ag are liquid state when performing the reflow process.
10 . The method as claimed in claim 7 , wherein the alloy patterns comprising Sn and X are liquid state, and the alloy patterns comprising Sn and Ag are liquid state when performing the reflow process.
11 . The method as claimed in claim 7 , wherein the alloy patterns comprising Sn and X are solid state, and the alloy patterns comprising Sn and Ag are solid state when performing the reflow process.
12 . A method, comprising:
forming Sn—Cu alloy patterns on first conductive pads of a first structure;
forming Sn—Ag alloy patterns on second conductive pads of a second structure;
forming Sn—X alloy patterns on the Sn—Ag alloy patterns, wherein X represents bismuth or indium;
pre-heating the Sn—X alloy patterns and the Sn—Cu alloy patterns under a first temperature, wherein the Sn—X alloy patterns remain solid state during pre-heating the Sn—X alloy patterns and the Sn—Cu alloy patterns; and
performing a reflow process under a second temperature to form conductive bumps between the first conductive pads and the second conductive pads, wherein the second temperature is higher than the first temperature.
13 . The method as claimed in claim 12 , wherein the Sn—Ag alloy patterns, the Sn—X alloy patterns and the Sn—Cu alloy patterns remain solid state during pre-heating the Sn—X alloy patterns and the Sn—Cu alloy patterns.
14 . The method as claimed in claim 12 , wherein the Sn—Cu alloy patterns are liquid state, the Sn—X alloy patterns are solid state, and the Sn—Ag alloy patterns are solid state when performing the reflow process.
15 . The method as claimed in claim 12 , wherein the Sn—Cu alloy patterns, the Sn—X alloy patterns and the Sn—Ag alloy patterns are solid state when performing the reflow process.
16 . The method as claimed in claim 12 , wherein the Sn—Cu alloy patterns, the Sn—X alloy patterns and the Sn—Ag alloy patterns are liquid state when performing the reflow process.
17 . The method as claimed in claim 12 , wherein a material of the conductive bumps comprises Sn—Ag—Cu—X alloy, and a concentration of X contained in the Sn—Ag—Cu—X alloy ranges from about 1 wt % to about 10 wt %.
18 . The method as claimed in claim 12 , wherein a concentration of silver (Ag) contained in the Sn—Ag alloy patterns ranges from about 1.0 wt % to about 2.5 wt %, and a thickness of the Sn—Ag alloy pattern ranges from about 20 micrometers to about 25 micrometers.
19 . The method as claimed in claim 12 , wherein a concentration of bismuth (Bi) contained in the Sn—Bi alloy patterns ranges from about 40 wt % to about 58 wt %, and a thickness of the Sn—Bi alloy patterns ranges from about 10 micrometers to about 15 micrometers.
20 . The method as claimed in claim 12 , wherein a concentration of copper (Cu) contained in the Sn—Cu alloy patterns ranges from about 0.4 wt % to about 1.1 wt %, and a thickness of the Sn—Cu alloy patterns ranges from about 35 micrometers to about 45 micrometers.