22P053
Discharge plasma to produce EUV
by using a rotating magnetic field of 13.56MHz
13.56MHzの回転磁場による放電プラズマを用いた極端紫外（EUV）光の生成
Tatsuya Shimizu1, Yukio Miyake1, Yusuke Ohashi1 , Hodaka Osawa1, Masami Ohnishi1,Waheed Hugrass2
清水 辰哉1, 三宅 由喜夫1，大橋 祐介1，大澤 穂高1，大西 正視1, Waheed Hugrass2
12

Kansai Univ. 3-3-35, Yamanote-cho, Suita-shi, Osaka 564-8680, Japan,Univ. Tasmania. School of Computing and Information Systems, Univ. Tasmania, Launceston,Tasumania 7250, Australia
1
関西大学 〒564-8680 大阪府吹田市山手町3-3-35、2タスマニア大学 オーストラリアタスマニア7250

The 13.56 MHz rotamak is studied for the purpose of producing the Xe plasma which radiates EUV lightfor the semiconductor lithography. The resonant conditions to maximize the antenna current are obtained in
the circuits including the impedance of the antenna, the cable length and the internal impedance of thepower supply. The current more than 40 A is realized and the small rotamak plasma is produced.

1. Introduction
Present day semiconductor technology iscapable of manufacturing transistors with 65
nm features. The production of next
generation chips with feature as small as 22nm
is crucial to the successful development ofextreme ultraviolet (EUV) photolithography.
Two methods such as Discharge ProducedPlasma (DPP) and Laser Produced Plasma(LPP) have been studied for the sake ofproducing EUV.1)-3) A ‘debris’, however, isproduced along with the EUV. The rotamak
has produced the clean EUV more than 66W
by the Xe plasma with the diameter 70 mm byusing the oscillator with 200 kHz and 75 kW.4)
The smaller plasma formation is studied by
13.56 MHz oscillator and the smaller chamberin order to satisfy the condition for thelithography.
2. Experimental facility
The facility is shown in the diagram given by
Fig.1.

RF Power
SupplyTuner 1

3. Tuning the circuit and Current in the antenna
The frequency 13.56 MHz is high enough toinclude the cable length connecting the power
supply and the antenna in obtaining the resonantcondition of the circuit. Figure 3 shows the current
versus tuning capacitance for the various cable
lengths. The maximum current is obtained in thecable length 0.75 m. When tuning the circuit bychanging the capacitance the currents are 40 A andpossess 90 degree phase difference. The input
power 1.2 kW is supplied to each antenna.

RMF
Antenna 1

0.75m
0.70m
0.65m

700
600

Phase
Shifter

Amplifier 2

Fig.2. Photography of vacuum chamber withantenna of rotating magnetic field.

Tuner 2RMF
Antenna 2

V o lt V [m V ]Amplifier 1

couple antennas attach directly on the glass
vacuum chamber as shown in Fig.2.

500

0.80m

400
300

Fig.1. Diagram of experimental facility.

20050

The power supply branches two circuits
consisting of the amplifier and tuner and theantenna. The phase shifter gives the phasedifference of 90 degree to the currents. Two60

7080

90

Capasitance C[pF]

Fig.3. Current versus tuning capacitance for thevarious cable lengths.

Figure 4 shows the Xe plasma produced in thechamber with the diameter 16 mm. The strong lightis emitted, but no EUV is observed by thephotodiode.

Fig.4. Xe plasma produced in the chamber with theinner diameter 16 mm.

4. Conclusions
The plasma is formed by 13.56 MHz oscillators
which are 90 degree out of phase. The antenna
currents are more than 40A. The axial magnetic
field is now being applied for reducing the electronloss. The higher electron temperature will beobtained to observe the EUV radiation.
References[1] B. Santo: IEEE Spectrum 44 (2007) No.8, 12.
[2] S.R. Das: IEEE Spectrum 45 (2008) No.3, 14.
[3] S.F. Home et al.: Proc. SPIE 6151 (2006) 61510P.
[4] W. Hugrass, et al. Jpn. J. Appl. Phys. 49 (2010)
016201.