Phosphorus fugitive emission control
A method of processing and passivating an implanted workpiece is disclosed, wherein, after passivation, the fugitive emissions of the workpiece are reduced to acceptably low levels. This may be especially beneficial when phosphorus, arsine, germane or another toxic species is the dopant being implanted into the workpiece. In one embodiment, a sputtering process is performed after the implantation process. This sputtering process is used to sputter the dopant at the surface of the workpiece, effectively lowering the dopant concentration at the top surface of the workpiece. In another embodiment, a chemical etching process is performed to lower the dopant concentration at the top surface. After this sputtering or chemical etching process, a traditional passivation process can be performed.
1. A method of reducing gaseous emissions from an implanted workpiece, comprising:
performing a sputtering process after the workpiece has been implanted, wherein the sputtering process reduces a surface concentration of a dopant from a top surface of the implanted workpiece, wherein an amount of dopant that is removed from the top surface is such that gaseous emissions from the workpiece, when stored in a sealed enclosure for 10 days with 24 similarly processed workpieces, are less than 50 ppm; and
performing a passivation process after the sputtering process to form a passivation layer on the top surface of the implanted workpiece.
2. The method of claim 1 , wherein the sputtering process is performed using an inert gas.
3. The method of claim 2 , wherein the inert gas comprises argon.
4. The method of claim 2 , wherein the passivation process is performed using nitrogen or oxygen.
5. The method of claim 1 , wherein the sputtering process and the passivation process are performed in one plasma chamber.
6. The method of claim 1 , wherein the workpiece is implanted with phosphine, arsine or germane.
7. A method of reducing gaseous emissions from a workpiece, comprising:
implanting the workpiece with phosphine;
removing the phosphine from a top surface of the workpiece after implanting the workpiece, wherein an amount of phosphine that is removed from the top surface is such that gaseous emissions from the workpiece, when stored in a sealed enclosure for 10 days with 24 similarly processed workpieces, are less than 50 ppm; and
passivating the top surface of the implanted workpiece.
8. The method of claim 7 , wherein the phosphine is removed using a sputtering process.
9. The method of claim 7 , wherein the phosphine is removed using a chemical etching process.
10. The method of claim 7 , wherein the phosphine is removed using a combination of a sputtering process and a chemical etching process.