Methods and structures for capping a structure with a protective coating
View Patent ↗A surface is placed into a deposition chamber. A tin layer is formed on the surface, in which forming the tin layer includes providing a precursor into the deposition chamber for a first time period, wherein the precursor comprises one of tetrakis (dimethylamino) tin (TDMASn) or tin tetrachloride (SnCl 4 ), providing an inert gas into the deposition chamber for a second time period, providing a hydrogen reactant into the deposition chamber for a third time period, and providing the inert gas into the deposition chamber for a fourth time period. The first, second, third, and fourth time periods form one atomic layer deposition (ALD) cycle. The surface may be an exposed surface of a lead free metal.
1. A method for forming tin on a surface, the method comprising:
placing the surface into a deposition chamber;
forming a tin layer on the surface, wherein the forming the tin layer comprises:
providing a precursor into the deposition chamber for a first time period, wherein the precursor comprises one of tetrakis (dimethylamino) tin (TDMASn) or tin tetrachloride (SnCl 4 );
after providing the precursor for the first time period, providing an inert gas into the deposition chamber for a second time period;
after providing the inert gas for the second time period, providing a hydrogen reactant into the deposition chamber for a third time period; and
after providing the hydrogen reactant for the third time period, providing the inert gas into the deposition chamber for a fourth time period.
2. The method of claim 1 , wherein the first, second, third, and fourth time periods form one atomic layer deposition (ALD) cycle.
3. The method of claim 2 , wherein the forming the tin layer further comprises:
repeating the forming the tin layer until the tin layer reaches a target thickness.
4. The method of claim 3 , wherein the target thickness is in a range of 5 to 200 Angstroms.
5. The method of claim 1 , wherein the surface is characterized as an exposed surface of a semiconductor substrate.
6. The method of claim 1 , wherein the surface is characterized as an exposed surface of a lead-free metal layer.
7. The method of claim 1 , wherein the surface is characterized as an exposed surface of a lead-free solder sphere.
8. The method of claim 1 , further comprising:
after the forming the tin layer, performing an anneal of the tin layer.
9. The method of claim 8 , further comprising:
prior to the forming the tin layer, performing a moisture removal bake on the surface.
10. The method of claim 1 , wherein the tin layer is devoid of oxide.
11. A method for forming tin on solder spheres of a ball grid array (BGA) device, the method comprising:
placing the BGA device into a deposition chamber;
forming a tin layer on the solder spheres, wherein the forming the tin layer comprises:
providing a precursor into the deposition chamber for a first time period, wherein the precursor comprises one of tetrakis (dimethylamino) tin (TDMASn) or tin tetrachloride (SnCl 4 );
after providing the precursor for the first time period, providing an inert gas into the deposition chamber for a second time period;
after providing the inert gas for the second time period, providing a hydrogen reactant into the deposition chamber for a third time period; and
after providing the hydrogen reactant for the third time period, providing the inert gas into the deposition chamber for a fourth time period.
12. The method of claim 11 , wherein the solder spheres of the BGA device are characterized as lead free.
13. The method of claim 12 , wherein the solder spheres comprise an alloy of tin, silver, and copper.
14. The method of claim 11 , wherein the first, second, third, and fourth time periods form one atomic layer deposition (ALD) cycle.
15. The method of claim 11 , wherein the forming the tin layer on the solder spheres further comprises:
repeating the steps of providing until the tin layer reaches a target thickness.
16. The method of claim 15 , wherein the target thickness is in a range of 5 to 200 Angstroms.
17. The method of claim 11 , further comprising:
after the forming the tin layer, performing an anneal of the BGA device.
18. The method of claim 11 , further comprising:
prior to the forming the tin layer, performing a moisture removal bake on the BGA device.