Processing stacked substrates
Representative implementations provide techniques for processing integrated circuit (IC) dies and related devices, in preparation for stacking and bonding the devices. The disclosed techniques provide removal of processing residue from the device surfaces while protecting the underlying layers. One or more sacrificial layers may be applied to a surface of the device during processing to protect the underlying layers. Processing residue is attached to the sacrificial layers instead of the device, and can be removed with the sacrificial layers.
1. A method of forming a microelectronic assembly, comprising:
providing a substrate having an exposed conductive wiring layer level with or below a bonding surface of the substrate;
coating the conductive wiring layer with one or more protective sacrificial layers;
bonding a handle substrate to the one or more protective sacrificial layers using a temporary bonding layer;
processing the substrate while the handle substrate is bonded to the substrate;
removing the handle substrate;
removing the temporary bonding layer;
exposing the substrate, the one or more protective sacrificial layers, and a residue of the temporary bonding layer to a wet etchant for a preselected duration of time, the wet etchant decomposing at least one protective sacrificial layer, wherein the wet etchant comprises a complexing agent adapted to suppress dissolution of the conductive wiring layer; and
washing said at least one protective sacrificial layer and the residue of the processing from the conductive wiring layer.
2. The method of claim 1 , further comprising exposing the substrate, the one or more protective sacrificial layers, and the residue to an oxygen plasma radiation for a preselected duration to modify the moisture absorption characteristics of the one or more protective sacrificial layers, prior to exposing the substrate, the one or more protective sacrificial layers, and the residue to the wet etchant.
3. The method of claim 1 , further comprising coating a surface of the substrate opposite the conductive wiring layer with an organic or inorganic protective layer.
4. The method of claim 1 , wherein the processing includes removing a portion of the substrate from a surface of the substrate opposite the conductive wiring layer while the handle substrate is bonded to the substrate.
5. The method of claim 1 , wherein one or more of the protective sacrificial layers comprises an inorganic silicon dioxide (SiO2), boron doped silicon dioxide (B—SiO2), or phosphorus doped silicon dioxide (P—SiO2) material.
6. The method of claim 1 , wherein the one or more protective sacrificial layers comprises an organic protective layer over the conductive wiring layer and an inorganic protective layer over the organic protective layer, the organic protective layer adapted to protect the conductive wiring layer from degradation due to removal of the inorganic protective layer and the residue.
7. The method of claim 1 , wherein the wet etchant comprises a buffered oxide etchant (BHF) or hydrofluoric acid (HF).
8. The method of claim 1 , wherein the one or more of the protective sacrificial layers is applied using spin coating, plasma physical vapor deposition (PVD), or using an electrophoretic process.
9. The method of claim 1 , wherein the substrate is singulated before removal of the sacrificial protective layer.
10. The method of claim 1 , wherein the substrate is singulated after removal of the sacrificial protective layer.
11. The method of claim 1 , wherein the conductive wiring layer is not degraded, roughened, or corroded by exposure to the wet etchant.
12. A method of forming a microelectronic assembly, comprising:
providing a substrate having an exposed wiring layer level with or below a bonding surface of the substrate;
coating the wiring layer with one or more protective sacrificial layers;
processing the substrate;
exposing the substrate, the one or more protective sacrificial layers, and a residue of the processing to a wet etchant for a preselected duration of time, the wet etchant decomposing at least one protective sacrificial layer;
washing said at least one protective sacrificial layer and the residue of the processing from the wiring layer, wherein the wet etchant comprises a complexing agent adapted to suppress dissolution of the conductive wiring layer; and
stacking the substrate on another substrate through a direct bonding of the wiring layer of the substrate and a surface of the other substrate.
13. The method of claim 12 , wherein processing the substrate further comprises:
bonding a temporary substrate to the one or more protective sacrificial layers using a temporary bonding layer;
processing the substrate while the temporary substrate is bonded to the one or more protective sacrificial layers; and
removing the temporary substrate and the temporary bonding layer.
14. The method of claim 12 , further comprising removing a residue of the processing by removing the one or more protective sacrificial layers.
15. The method of claim 12 , further comprising removing a residue of the processing without degrading, roughening, or corroding the wiring layer with the wet etchant.
16. The method of claim 12 , further comprising removing a residue of the processing without exposing the wiring layer to the wet etchant.
17. The method of claim 12 , further comprising singulating the substrate prior to removing one or more of the protective sacrificial layers.
18. A method of forming a microelectronic assembly, comprising:
providing a substrate having an exposed conductive wiring layer level with or below a bonding surface of the substrate;
coating the conductive wiring layer with one or more protective sacrificial layers;
bonding a handle substrate to the one or more protective sacrificial layers using a temporary bonding layer;
processing the substrate while the handle substrate is bonded to the substrate;
removing the handle substrate;
removing the temporary bonding layer;
exposing the substrate, the one or more protective sacrificial layers, and a residue of the temporary bonding layer to an oxygen plasma radiation for a preselected duration to modify the moisture absorption characteristics of at least one of the one or more protective sacrificial layers;
exposing the substrate, the one or more protective sacrificial layers, and the residue of the temporary bonding layer to a wet etchant for a preselected duration of time, the wet etchant decomposing at least one protective sacrificial layer, wherein the one or more protective sacrificial layers comprises an organic protective layer over the conductive wiring layer and an inorganic protective layer over the organic protective layer, the organic protective layer adapted to protect the conductive wiring layer from degradation due to removal of the inorganic protective layer and the residue; and
washing said at least one protective sacrificial layer and the residue of the temporary bonding layer from the conductive wiring layer.
19. The method of claim 18 , further comprising selectively removing the protective sacrificial layer while protecting an underlying layer below.
20. A method of forming a microelectronic assembly, comprising:
providing a substrate having an exposed conductive wiring layer level with or below a bonding surface of the substrate;
coating the conductive wiring layer with one or more protective sacrificial layers;
processing the substrate;
exposing the substrate, the one or more protective sacrificial layers, and a residue of the processing to a wet etchant for a preselected duration of time, the wet etchant decomposing at least one protective sacrificial layer, wherein the wet etchant comprises a complexing agent adapted to suppress dissolution of the conductive wiring layer.
21. A method of forming a microelectronic assembly, comprising:
providing a substrate having an exposed conductive wiring layer level with or below a bonding surface of the substrate;
coating the conductive wiring layer with an organic sacrificial protective layer over the conductive wiring layer and an inorganic sacrificial protective layer over the organic sacrificial protective layer, the organic sacrificial protective layer adapted to protect the conductive wiring layer from degradation due to removal of the inorganic sacrificial protective layer;
processing the substrate;
exposing the substrate, the inorganic sacrificial protective layer, and a residue of the processing to a wet etchant for a preselected duration of time, the wet etchant decomposing at least the inorganic sacrificial protective layer without degrading, roughening, or corroding the conductive wiring layer.