High Power Pulse Plasma Generators (HPPMS/HIPIMS/MPP)

for Material Processing Applications.

Zond, Inc / Zpulser, LLC.Mansfield, MA 02048 USA

Magnetron Sputtering

• Magnetron sputtering is a widely used PVD (Physical Vapor Deposition)

technique to deposit thin films. This technique is based on the generation

of a low pressure magnetically enhanced glow discharge – magnetron

discharge.

B B

Sputtering target surface

I(t) = {1+ γSS (E)}Ii

Jφ

Jφ - azimuthally rotating current density due to Hall effect (vE/B =(ExB)/B2 ),

JD - discharge current density running perpendicular to the magnetic field lines

JDJD

2

Magnetron Sputtered Films

• Columnar structure

• High stress

• Poor adhesion

• Low hardness

• Low level of ionization

of sputtered target material

Ta

Ti

Cr

Ti

Cr Cr

3

Magnetron Sputtering

• How to increase metal ion flux near the substrate?

– Unbalanced magnetron

– Special design HCM

– Secondary discharge between sputtering target and substrate

– Electrical bias on the substrate in order to control energy from the gas and sputtered

target material atoms (DC bias, RF bias, Pulsed bias).

– More ions flux – bias , Less ions flux – bias , Usually bias voltage ~ -(20 – 200) V

4

Voltage Current Characteristic for DC Magnetron

Id

Magnetron 0DC magnetron sputtering P ~ 10 – 100 W/cm2 , low level of ionization (low discharge current Id )

To increase level of ionization increase discharge current

High Voltage High Current High Power Short PulseHigh power pulse magnetron sputtering P ~ 0.3 -10 kW/cm2

Ud ≥ -1000V,Id ≥ 1000 A

Pulse duration ~ 50- 200 µsDuty cycle 1-10 %

500 V

40 A P = 20 kW (200 mm Wafer)

|Ud|300 V 700 V

Id ~ β( Ud)n

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High Power Pulse Magnetron Sputtering

• High Power Pulse Magnetron Sputtering is a relatively new technology.

– First paper was published in 1995, second in 1996, third in1999.

• This is the most cost effective way to generate metal ions during the

sputtering process.

• High level of ionization can be obtained at target power density in the

range of 0.3 – 3 kW/cm2 depends on applications

• Duty cycle of the pulse power generator usually is in the range of 5-20%.

• Typical Pulse duration ~ 50-200 µs

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High Power Pulse Magnetron Sputtering

(HPPMS/HIPIMS).

Modulated Pulse Power (MPP)

MPP(2)

HPPMS HIPIMS MPP(1)

MPP Plasma Generator (Zpulser Solo)

Output voltage pulse shape

Circuit diagram for Zpulser Solo

Voltage waveforms after solid state switch (IGBT)

before transformer

9

t, µs

600 V > Vch > 300 V

-600 V

+600 V Switch closed

Switch open

Voltage waveforms after transformer before diodes

bridge

10

t, µs

-1200 V

+1200 V

Voltage waveforms after diodes bridge

11

t, µs

-1200 V

Voltage waveform after LC circuit, output voltage

-1100 V

ton toff

T = (ton + toff)f = 1/(ton + toff)T

T

3µs< ton <18µs 6µs< toff <50µs f is in the range of 10-62.5 kHz

Vout = βDD = ton/(ton + toff)

PULSE

micro pulse

Micro pulse frequency and micro pulse width

modulations

12

t, µs

+1200 V

t, µs

V output

micro pulse

V output pulse consists of train of

micro pulses

HIPIMS (HPPMS) and MPP (Modulated pulse power)

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Pulse duration 100-3000 µs

Multistage voltage pulse

Max voltage -1100 V

Max Peak power 0.6 MW

Average Power 22 kW

Voltage oscillations

HIPIMS MPP

Pulse duration 50-200 µs ?

Rectangular voltage pulse

Max voltage –(1000 -2000) V?

Max Peak power 3 MW?

Average Power 20 kW?

Arc in HIPIMS/HPPMS

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In HIPIMS the ignition voltage is equal to discharge voltage!!!

Arc in HIPIMS can happened in the ignition stage or in high power stage

V

t

MPP controls the ignition stage and high power stage ( long medium power instead of short high power)

Micro pulse frequency and micro pulse width

modulations for control output voltage pulse

15

t, µs

+1200 Vt, µsmicro pulses

V output pulse consists of train of micro pulses

6 34 6 34 10 10 10 10 12 10 14 10 14 10 14

1st rise time V1

2nd rise timeV2

~(100 – 500) µs pre-ionization

High Peak Power

Micro pulse frequency and micro pulse width

modulations for control output voltage pulse

16

t, µs

+1200 Vt, µsmicro pulses

V output pulse consists of train of micro pulses

6 34 6 34 8 10 11 10 12 10 14 10 14 10 14

V2

~(100 – 500) µs pre-ionization

High Peak Power

High Power Pulse Magnetron Sputtering,

Zpulser Solo Plasma Generator (2)

(1) (2)

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Yellow line – discharge voltage, blue line – discharge current, Cr target (500 cm2)

200 A200 A

Voltage Pulse Shapes (Zpulser Solo)

18

(1) (2) (3)

(4) (5)

Yellow line – voltage, blue line-current(1) – (3) Cr target (80 cm2)(4) – (5) Resistive load

Plasma Photo in dc and MPP sputtering(Colorado School of Mine-ACSEL)

Conventional dc Magnetron Sputtering operated at 1.5 kW

MPPTM sputtering Pave=1.5 kW

MPPTM sputtering Pave=2.7 kW

MPPTM sputtering Pave=3.5 kW

MPPTM sputtering Pave=4.09 kW

MPP, Ta sputtering process

DC

MPP

0

20

40

60

80

100

120

140

200 250 300 350

Ta+ Ta+Ta+

Bias = - 30 V

Bias = -30 V

Inte

nsity

, cou

nts/

sec

Wavelength λ, nm

OES

CONCLUSION

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1. Zpulser plasma generator Solo/ Axia generates multistage negative voltage pulse with controllable voltage rise, duration and amplitude.

2. Zpulser plasma generator Solo/ Axia generates voltage pulse with voltage oscillations with frequency 10-62.5 kHz. And amplitude 5-30 %.

3. The presence of voltage oscillations enhance plasma stability and ionization.

4. Voltage oscillations induced by specific operation of the Zpulser plasma generator.

5. The presence of the voltage oscillations is beneficial for ionization and plasma stability.

6. The separation of ignition voltage and discharge voltage significantly reduces amount of Arcs particular for reactive sputtering.

HIPIMS/HPPMS Plasma Generator (Zpulser Cyprium)

Output voltage pulse shape

Circuit diagram for Zpulser Cyperium

Voltage waveforms after diodes bridge

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t, µs

-1200 V

Voltage waveform after LC circuit, output voltage pulse

-1100 V

ton toff

T = (ton + toff)f = 1/(ton + toff)T

T

3µs< ton <18µs 6µs< toff <1000µs f is in the range of 10-62.5 kHz

Voutput = βDD = ton/(ton + toff)

PULSE

micro pulse

Voltage waveform after LC circuit, output voltage pulse

24

-1100 V T

3µs< ton <18µs 6µs< toff <1000µs f is in the range of 10-62.5 kHz

Voutput = βDD = ton/(ton + toff)

PULSE

Voffset < 0V

Voffset > 0 V+ V

t

t

+ V

Magnetron Discharge Afterglow (1)

Te, Ne

t, µs

Tafterglow

T(duty cycle)

∆T

U = − 2000 V U = − 2000 V

∆Tafterglow ~ 10 – 50 µs∆T(duty cycle) ~ 10000 µs

∆T(duty cycle) >> ∆Tafterglow(HPPMS, HIPIMS)

∆∆∆∆T(duty cycle) ≤ ∆∆∆∆Tafterglow ?

200 µs 200 µs

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Magnetron Discharge Afterglow (2)

Te, Ne

t, µs

Tafterglow

T(duty cycle)

U = − 2000 V U = − 2000 V

∆Tafterglow ?∆T(duty cycle) ~ 5 -500 µs ?

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Cyprium Pulse Plasma Generator (3)

1. New High Power Pulse Plasma Generator was developed.2. Pulse duration (voltage oscillation) is in the range of 5-20 µs.3. Output voltage up to 1700 V, peak power 1.2 MW. 4. Voltage oscillations amplitude (40-100 %), control of rise time, fall

time and frequency.

ID, A

VD, V

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Plasma Generator (4)(Cyprium plasma generator)

-1100 V

Vd

Id

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Voltage and Current Waveforms for Cu Discharge (1)(Cyprium plasma generator)

Influence of voltage oscillations frequency on discharge current(f1 = 12241 kHz, f2 = 41667 kHz)

I,(A)

U, (V)

f1f2

25 µs

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Voltage and Current Waveforms for Cu Discharge (2)(Cyprium plasma generator)

-800 V

150 A

1050 A

Id = Id (frequency, kHz)

Zond/Zpulser

Voltage Current Characteristic for Cu Discharge.

(Cyprium plasma generator)

0

100

200

300

400

500

0 500 1000 1500 2000

f2

f1

Discharge Voltage, V

Dis

char

ge C

urre

nt, A

(f1 = 12241 kHz, f2 = 41667 kHz)

Ppeak = 540 kW(~ 7 kW/cm2)

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Voltage and Current Waveforms for C Discharge(Solo and Cyprium plasma generators)

~800 V

~30 A~200 A

~520 V

(2) Cyperium plasma generator(1) Solo plasma generator

Deposition Rate ~ 7.5 µm/hour (1250 Å/min), Paverage = 5kW, Hardness ~ 40 GPa (different conditions)

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Voltage and Current Wave forms for single oscillation

Zond/Zpulser

- 1700 V

-1000 V

200 A

Reactive Sputtering of Al2O3 films

(Cyprium plasma generator)

0

50

100

150

200

390 395 400

Ar = 100 sccmO2 = 0 sccm

O2 = 0 sccm

λ, nmIn

tens

ity, c

ount

s/se

c

O2 = 8 sccm

O2= 14 sccm

Ar = 100 sccmO2 = 15 sccm

P peak ~105 kW(1.5 kW/cm2 )V peak ~ - 760 VI peak ~ 140 A

Deposition rate ~13 µm/hour

~ 100 A

∆

Ar = 100 sccm

O2 = 8 sccm

~800 V

~100 A

~900 V

~ 140 A

~760 V

Al+390.06 nm

Al394.4 nm

Al396.15 nm

CONCLUSION (1)

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1. Zpulser plasma generator Cyperium generates multi frequency negative voltage oscillations with controllable voltage rise, duration and amplitude in one pulse.

2. Zpulser plasma generator Cyperium generates voltage pulse with voltage oscillations with frequency 10-62.5 kHz. And amplitude 30-100 %.

3. The presence of the voltage oscillations is beneficial for ionization and plasma stability.

4. Maximum output voltage 1700 V, current 550 – 800 A, average power 22 kW.

Perfect for high power pulse reactive nitride/ oxide magnetron sputtering processes

CONCLUSIONS (2)

1. High Power Pulse Magnetron Technology – the most cost effective method to

generate ions.

2. Three different high power pulse plasma generators:

Thank you for your attention

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