Process for sputtering copper in a self ionized plasma
First Claim
1. A method of sputter depositing copper onto a substrate, comprising the steps of:
- providing a chamber having a target principally comprising copper spaced from a pedestal for holding a substrate to be sputter coated by a throw distance that is greater than 50% of a diameter of the substrate;
rotating a magnetron about the back of the target, said magnetron including an inner magnetic pole of one magnetic polarity surrounded by an outer magnetic pole of an opposite magnetic polarity, a magnetic flux of said outer pole being at least 50% larger than the magnetic flux of said inner pole;
after a plasma has been ignited in the chamber, pumping said chamber to a pressure of no more than 5 milliTorr; and
applying at least 10 kW of DC power to said target normalized to a 200 mm wafer while said chamber is pumped to said pressure, to thereby sputter copper from said target onto said substrate.
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Abstract
A DC magnetron sputter reactor for sputtering copper, its method of use, and shields and other parts promoting self-ionized plasma (SIP) sputtering, preferably at pressures below 5 milliTorr, preferably below 1 milliTorr. Also, a method of coating copper into a narrow and deep via or trench using SIP for a first copper layer. SIP is promoted by a small magnetron having poles of unequal magnetic strength and a high power applied to the target during sputtering. The SIP copper layer can act as a seed and nucleation layer for hole filling with conventional sputtering (PVD) or with electrochemical plating (ECP). For very high aspect-ratio holes, a copper seed layer is deposited by chemical vapor deposition (CVD) over the SIP copper nucleation layer, and PVD or ECP completes the hole filling. The copper seed layer may be deposited by a combination of SIP and high-density plasma sputtering. For very narrow holes, the CVD copper layer may fill the hole.
79 Citations
21 Claims
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1. A method of sputter depositing copper onto a substrate, comprising the steps of:
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providing a chamber having a target principally comprising copper spaced from a pedestal for holding a substrate to be sputter coated by a throw distance that is greater than 50% of a diameter of the substrate;
rotating a magnetron about the back of the target, said magnetron including an inner magnetic pole of one magnetic polarity surrounded by an outer magnetic pole of an opposite magnetic polarity, a magnetic flux of said outer pole being at least 50% larger than the magnetic flux of said inner pole;
after a plasma has been ignited in the chamber, pumping said chamber to a pressure of no more than 5 milliTorr; and
applying at least 10 kW of DC power to said target normalized to a 200 mm wafer while said chamber is pumped to said pressure, to thereby sputter copper from said target onto said substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
said pressure is less than 2 milliTorr;
said throw distance is greater than 80% of said diameter of the substrate; and
said applying step applies said DC power relative to a grounded shield surrounding a space between said target and said support and further comprising providing an electrically floating shield extending from a side of said target between 3 and 5 cm from a front of said target toward said support.
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18. The method of claim 1, wherein said magnetron has an area of no more than ¼
- of the area of the target.
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19. A method of depositing copper into a hole formed in a dielectric layer of a substrate, comprising the steps of:
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a first step of sputter depositing into said hole a first copper layer in a first sputter reactor capable of ionized metal plating;
a subsequent second step of sputter depositing a second copper layer in a second sputter reactor capable of self-ionized plasma sputtering to form a copper layer on walls of said hole but not filling said hole; and
a third step of depositing a third copper layer onto said second copper layer. - View Dependent Claims (20, 21)
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Specification