Method for forming a through silicon via (TSV)
View Patent ↗A method of forming a through silicon via includes forming a via opening in a substrate using a hard mask, wherein a polymer is formed in the via opening. A first wet clean removes a first portion of the polymer and forms a first carbon containing oxide along portions of the sidewalls. A first ash process modifies the first carbon containing oxide and removes a second portion of the polymer. A first wet etch removes the modified first carbon containing oxide and a third portion of the polymer. A second ash process forms a second carbon containing oxide along at least a portion of the sidewalls. A second wet etch process removes the second carbon containing oxide and a fourth portions of the polymer. A third ash process forms a third carbon containing oxide along portions of the sidewalls and removes any remaining portions of the polymer.
1. A method of forming a through silicon via (TSV), the method comprising:
forming a hard mask over a semiconductor substrate, wherein the hard mask has a mask opening;
forming a via opening in the semiconductor substrate using the hard mask, wherein:
the via opening comprises a bottom and sidewalls;
a portion of the hard mask overhangs the via opening; and
a polymer comprising silicon, carbon, and fluorine is formed along at least a portion of the bottom of the via opening;
performing a first wet clean to remove a first portion of the polymer and form a first carbon containing oxide along portions of the sidewalls by pulling silicon and carbon from the substrate;
performing a first ash process to modify the first carbon containing oxide and to remove a second portion of the polymer;
performing a first wet etch process to remove the modified first carbon containing oxide and a third portion of the polymer;
performing a second ash process to form a second carbon containing oxide along at least a portion of the sidewalls by pulling silicon and carbon from the semiconductor substrate;
performing a second wet etch process to remove the second carbon containing oxide and a fourth portion of the polymer; and
performing a third ash process to form a third carbon containing oxide along portions of the sidewalls by pulling silicon and carbon from the substrate and removing any remaining portions of the polymer.
2. The method of claim 1 , wherein performing the first wet etch process further comprises etching the hard mask to make the mask opening larger.
3. The method of claim 2 , wherein performing the second wet etch process further comprises etching the hard mask to make the mask opening larger.
4. The method of claim 1 , further comprising forming an adhesive layer and conductive fill within the via opening.
5. The method of claim 4 , further comprising removing a portion of the semiconductor substrate.
6. The method of claim 1 , wherein the polymer is also formed along at least a portion of the sidewall of the via opening.
7. The method of claim 1 , wherein performing the first wet etch process and the second wet etch process comprise using dilute hydrofluoric acid.
8. The method of claim 1 , wherein performing a first wet clean comprises using piranha, hydrofluoric acid, and ammonium hydroxide.
9. The method of claim 1 , further comprising performing a second wet clean to remove the third carbon containing oxide and form a chemical oxide along the sidewalls and bottom of the via opening.
10. The method of claim 9 , wherein performing a second wet clean comprises using piranha, hydrofluoric acid, and ammonium hydroxide.
11. The method of claim 1 , wherein the hard mask comprises multiple layers.
12. The method of claim 1 , wherein the first, second and third carbon containing oxides comprise silicon and oxygen.
13. A method of forming a through silicon via (TSV), the method comprising:
forming a hard mask over a semiconductor substrate;
forming a via opening in the semiconductor substrate using the hard mask, wherein:
the via opening comprises a bottom and sidewalls; and
a polymer comprising silicon, carbon, and fluorine is formed along at least a portion of the bottom of the via opening;
performing a wet clean to remove a first portion of the polymer and form a first carbon containing oxide along portions of the sidewalls by pulling silicon and carbon from the substrate;
performing an ash process to remove a second portion of the polymer;
performing a wet process to remove a third portion of the polymer; and
repeating the steps of performing an ash process and performing a wet process a predetermined number of times;
forming an oxide along the sidewalls and bottom of the opening;
forming an adhesion layer and a conductive fill in the via opening; and
removing a portion of the semiconductor substrate.
14. The method of claim 13 , wherein the predetermined number of times is one time.
15. The method of claim 14 , wherein the hard mask has a mask opening and the first wet etch process further comprises etching the hard mask to make the mask opening larger.
16. The method of claim 15 , wherein performing the second wet etch process further comprises etching the hard mask to make the mask opening larger.
17. The method of claim 16 , wherein the polymer is formed along at least a portion of the sidewall of the via opening.
18. The method of claim 17 , wherein performing the first wet etch process and the second wet etch process comprise using dilute hydrofluoric acid.
19. The method of claim 18 , wherein forming an oxide along the sidewalls and bottom of the opening comprises performing a wet process.
20. A method of forming a through silicon via (TSV), the method comprising:
forming a hard mask over a semiconductor substrate;
forming a via opening in the semiconductor substrate using the hard mask, wherein:
the via opening comprises a bottom and sidewalls; and
a polymer comprising silicon, carbon, and fluorine is formed along at least a portion of the bottom of the via opening;
performing a first wet clean using piranha, hydrofluoric acid and ammonium hydroxide to remove a first portion of the polymer and form a first carbon containing oxide along portions of the sidewalls by pulling silicon and carbon from the substrate;
performing a first ash process to modify the first carbon containing oxide and to remove a second portion of the polymers;
performing a first wet etch process using dilute hydrofluoric acid to remove the modified first carbon containing oxide and a third portion of the polymer;
performing a second ash process to form a second carbon containing oxide along at least a portion of the sidewalls by pulling silicon and carbon from the semiconductor substrate;
performing a second wet etch process using dilute hydrofluoric acid to remove the second carbon containing oxide and a fourth portions of the polymer;
performing a third ash process to form a third carbon containing oxide along portions of the sidewalls by pulling silicon and carbon from the substrate and removing any remaining portions of the polymer;
performing a second wet clean piranha, hydrofluoric acid and ammonium hydroxide to remove the third carbon containing oxide and form a chemical oxide along the sidewalls and bottom of the via opening;
forming an adhesion layer and a conductive fill in the via opening; and
removing a portion of the semiconductor substrate.