Method and structure for die bonding using energy beam
Disclosed is a die-bonding method which provides a target substrate having a circuit structure with multiple electrical contacts and multiple semiconductor elements each semiconductor element having a pair of electrodes, arranges the multiple semiconductor elements on the target substrate with the pair of electrodes of each semiconductor element aligned with two corresponding electrical contacts of the target substrate, and applies at least one energy beam to join and electrically connect the at least one pair of electrodes of every at least one of the multiple semiconductor elements and the corresponding electrical contacts aligned therewith in a heating cycle by heat carried by the at least one energy beam in the heating cycle. The die-bonding method delivers scattering heated dots over the target substrate to avoid warpage of PCB and ensures high bonding strength between the semiconductor elements and the circuit structure of the target substrate.
1. A die-bonding structure comprising:
a target substrate having:
a supporting base; and
a circuit structure formed on one side of the supporting base and having:
a glass plate formed on the supporting base;
a transparent conductive layer formed on the glass plate;
a metal layer formed on the transparent conductive layer;
at least one bonding-reinforced circuit layer formed on the metal layer; and
multiple electrical contacts formed on the bonding-reinforced circuit layer;
multiple semiconductor elements attached to a carrier plate and spaced apart from each other by gaps, each semiconductor element having a pair of electrodes aligned with two corresponding electrical contacts of the circuit structure of the target substrate; and
a beam generator generating at least one energy beam for joining and electrically connecting the at least one pair of electrodes of every at least one of the multiple semiconductor elements and the corresponding electrical contacts aligned therewith in a heating cycle by heat carried by the at least one energy beam in the heating cycle.
2. The die-bonding structure as claimed in claim 1 , wherein each of the multiple semiconductor elements is a light-emitting diode (LED) with the pair of electrodes and multiple light-emitting layers stacked to each other.
3. The die-bonding structure as claimed in claim 1 , wherein the target substrate includes one of a printed circuit board (PCB), a flexible PCB, a glass circuit board, and a backplane with thin-film transistor (TFT) circuits or pulse width modulation (PWM) driving circuits.
4. The die-bonding structure as claimed in claim 3 , wherein the circuit structure of the target substrate is a one of a TFT liquid crystal display (LCD) circuit and an Active Matrix Organic Light Emitting Diode (AMOLED) circuit.
5. The die-bonding structure as claimed in claim 1 , wherein each of the at least one bonding-reinforced circuit layer of the circuit structure of the target substrate comprises:
a bonding layer formed on the metal layer; and
a eutectic metal layer formed on the bonding layer and having the multiple electrical contacts formed thereon.
6. The die-bonding structure as claimed in claim 5 , wherein the transparent conductive layer is formed of indium tin oxide (ITO), indium zinc oxide (IZO) or indium gallium zinc oxide (IGZO), the metal layer is formed of molybdenum, aluminum or aluminum neodymium (ALNd), the bonding layer is formed of titanium, titanium nitride, layers of titanium nitride and titanium stacked to each other, or layers of titanium nitride, titanium and titanium nitride sequentially stacked to each other, and the eutectic metal layer is formed of copper or gold.
7. The die-bonding structure as claimed in claim 5 , wherein the bonding-reinforced circuit layer of the circuit structure of the target substrate further comprises:
an auxiliary bonding layer formed on the eutectic metal layer; and
a wetting layer formed on the auxiliary bonding layer and having the multiple electrical contacts formed thereon.
8. The die-bonding structure as claimed in claim 7 , wherein the transparent conductive layer is formed of indium tin oxide (ITO), indium zinc oxide (IZO) or indium gallium zinc oxide (IGZO), the metal layer is formed of molybdenum, aluminum or aluminum neodymium (ALNd), the bonding layer is formed of titanium, titanium nitride, layers of titanium nitride and titanium stacked to each other, or layers of titanium nitride, titanium and titanium nitride sequentially stacked to each other, the eutectic metal layer is formed of copper or gold, the auxiliary bonding layer is formed of titanium, titanium nitride, layers of titanium nitride and titanium stacked to each other, or layers of titanium nitride, titanium and titanium nitride sequentially stacked to each other, and the wetting layer is formed of gold or silver.
9. The die-bonding structure as claimed in claim 1 , further comprising a backside reflector formed between the supporting base and the circuit structure of the target substrate.
10. The die-bonding structure as claimed in claim 9 , wherein
the supporting base includes the glass plate; and
the backside reflector includes:
a reflective layer formed on the supporting base of the target substrate; and
an insulating dielectric layer formed on the reflective layer, wherein the circuit structure of the target substrate is formed on the insulating dielectric layer.
11. The die-bonding structure as claimed in claim 9 , wherein
the supporting base includes the glass plate; and
the backside reflector includes:
a reflective layer formed on the supporting base of the target substrate;
a treated film formed by oxidizing or nitriding a top portion of the reflective layer; and
an insulating dielectric layer formed on the treated film, wherein the circuit structure of the target substrate is formed on the insulating dielectric layer.
12. The die-bonding structure as claimed in claim 11 , wherein the reflective layer is formed of aluminum, the treated film is formed of metal oxide or metal nitride, and the insulating dielectric layer is formed of silicon dioxide.
13. The die-bonding structure as claimed in claim 1 , wherein when the beam generator is placed next to the multiple semiconductor elements, heat carried by the at least one energy beam in the heating cycle transfers to the at least one pair of electrodes of the every at least one of the multiple semiconductor elements and the corresponding electrical contacts aligned therewith through the at least one of the multiple semiconductor elements.
14. The die-bonding structure as claimed in claim 1 , wherein when the beam generator is placed next to the target substrate, heat carried by the at least one energy beam in the heating cycle transfers to the at least one pair of electrodes of the every at least one of the multiple semiconductor elements and the corresponding electrical contacts through the target substrate.
15. The die-bonding structure as claimed in claim 1 , wherein the at least one energy beam generated by the beam generator includes one energy beam applied to heat and electrically connect the pair of electrodes of one of the multiple semiconductor elements and two corresponding electrical contacts of the target substrate in the heating cycle, and the heating cycle is in a range of 0.01 second to 1 second.
16. The die-bonding structure as claimed in claim 1 , wherein the at least one energy beam generated by the beam generator includes one energy beam applied to heat and electrically connect the pairs of electrodes of at least two of the multiple semiconductor elements and the corresponding electrical contacts of the target substrate in the heating cycle, and the heating cycle is in a range of 0.01 second to 1 second.
17. The die-bonding structure as claimed in claim 1 , wherein each of the at least one energy beam is a laser beam producing one of ultraviolet (UV) light, visible light and infrared (IR) light.