Method of magnetron sputtering and a method for determining a power modulation compensation function for a power supply applied to a magnetron sputtering source
View Patent ↗A method of magnetron sputtering, comprises rotating a magnet of a magnetron with an angular frequency ω, and, during sputtering of material from a source of the magnetron onto a substrate, periodically modulating a power level applied to the source with at least a component comprising a frequency f which is a harmonic of the angular frequency ω of rotation of the magnet other than the first harmonic.
1. A method of magnetron sputtering, comprising:
rotating a magnet of a magnetron with an angular frequency ω, and
during sputtering of material from a source of the magnetron onto a substrate, periodically modulating a power level applied to the source with at least a component comprising a frequency f which is a harmonic of the angular frequency ω of rotation of the magnet other than a first harmonic.
2. The method of claim 1 , wherein
the periodic modulation of the power level comprises one or more further components, each comprising a frequency f which is a harmonic of the angular frequency ω of rotation of the magnet and which is different to a first frequency.
3. The method of claim 1 , wherein
the periodic modulation has the form of a cosine with a phase shift, a sine with a phase shift or the sum of a cosine and a sine.
4. The method of claim 1 , wherein
the periodic modulation comprises a component having a first frequency f 1 , a first amplitude a 1 and a first phase shift δ 1 with respect to the angular frequency ω of the magnet, the first frequency f 1 being a harmonic of the angular frequency ω other than a first harmonic.
5. The method of claim 4 , wherein
the periodic modulation comprises a further component having a second frequency f 2 , a second amplitude a 2 and a second phase shift δ 2 with respect to the angular frequency ω of the magnet, the second frequency f 2 being a different harmonic of the angular frequency ω compared to the first frequency f 1 .
6. The method of claim 5 , wherein
the first frequency f 1 being one of the second, third and fourth harmonics of the angular frequency ω and the second frequency f 2 being one of the first, third and fourth harmonics of the angular frequency ω.
7. The method of claim 1 , wherein
the component of the periodic power modulation comprises an amplitude selected to compensate for a difference in the angular non-uniformity of the thickness measured for a film of the sputtered material deposited on a substrate using a single harmonic of the angular frequency, a zero phase shift and a pre-determined amplitude compared to a reference film of the sputtered material deposited on a substrate without modulation of the power supply.
8. The method of claim 1 , wherein
the component of the periodic power modulation comprises a phase shift selected to compensate for a difference in the angular non-uniformity of the thickness measured for a film of the sputtered material deposited on a substrate using a single harmonic of the angular frequency, a zero phase shift and a pre-determined amplitude compared to a reference film of the sputtered material deposited on a substrate without modulation of the power supply.
9. The method of claim 8 , wherein
the thickness is determined by Fourier integration or least squares approximation.
10. The method of claim 1 , wherein
the periodic modulation applied to the source is determined by applying a power modulation compensation function comprising an amplitude and phase shift, the power modulation compensation function being the vector sum of a reference power modulation and a differential power modulation,
the differential power modulation being determined by measuring the difference between the thickness of a first film of the sputtered material deposited on a substrate using a harmonic of the angular frequency, a first phase shift and a first amplitude and the thickness of a reference film of the sputtered material deposited on a substrate using a reference power modulation comprising said harmonic of the angular frequency, a reference phase shift and a reference amplitude.
11. The method of claim 1 , wherein
the periodic modulation applied to the source is determined by applying a power modulation compensation function comprising an amplitude and phase shift, the power modulation compensation function being determined by rotating a simulated two dimensional erosion profile of the magnetron at the harmonic frequency and calculating the non-uniformity of the thickness of the deposited film.
12. The method of claim 1 , wherein
in a first step the power level comprises a periodic modulation having a first frequency f 1 which is a harmonic of the angular frequency ω and in a second step the power level comprises a periodic modulation having second frequency f 2 , the second frequency f 2 being a different harmonic of the angular frequency ω compared to that of the first frequency f 1 .