Key words㸸

Abstract

Key words㸸

㸯㸬ࡣࡌࡵ࡟

㸨

Doshisha University

㸨㸨

Okayama University

㸨㸨㸨

Okayama University of Science

㸨㸨㸨㸨

Sojo University

ప࢚ࢿࣝࢠ࣮࣮࢝࣎ࣥࢫࣃࢵࢱࣜࣥࢢ࡟㛵ࡍࡿ Xe ⵳✚ຠᯝ

๢ᣢ ㈗ᘯ

㸪࿴⏣ ඖ

㸪ⓒṊ ᚭ

㸪ᮧᮏ ဴஓ

㸪す⏣ ㏔㞝

Effect of accumulation of incident particles into a target material on sputtering under low-energy ion bombardment

By

Takahiro KENMOTSU

, Motoi WADA

, Toru HYAKUTAKE

, Tetsuya MURAMOTO

, Michio NISHIDA

Abstract

The sputtering yields of carbon have been measured during xenon ion bombardment under the threshold energy predicted by the theory at normal incidence. The theoretical threshold energy is 160.84 eV for the xenon–carbon combination. These experimental results are different from the semi-empirical formula proposed by Yamamura and Tawara. We have calculated the sputtering yields of carbon under the xenon ion bombardment with a Monte Carlo code ACAT which is based on the binary collision approximation. The yields of carbon calculated with ACAT are in good agreement with the semi-empirical formula, but differ from the experiments under low-energy xenon bombardment. This discrepancy is believed to be due to the accumulation of xenon onto graphite. The semi-empirical formula and the above ACAT results do not consider this accumulation. In order to quantify this effect, we have calculated with ACAT for the carbon – xenon composite material as a function of xenon concentration. The results of ACAT with 14%

xenon atoms in graphite are in good agreement with the experimental data.

Key words㸸Sputtering, Grid Erosion, Accumulation of Xe, JIEDI Tool.

㸯㸬ࡣࡌࡵ࡟

ᝨᫍ᥈ᰝᶵ"ࡣࡸࡪࡉ㸰" ࡢ࢖࢚࢜ࣥࣥࢪࣥ㛤Ⓨ࡟࠾࠸࡚ࠊࣉࣟ࣌ࣛࣥࢺ࡛࠶ࡿ࢟ࢭࣀࣥ࢖࢜ࣥ࡟ࡼࡿ࢖࢚࢜ࣥࣥࢪ࣭ࣥࢢ

ࣜࢵࢻࡢᦆ⪖ࡀၥ㢟࡜࡞ࡗ࡚࠸ࡿ㸬ᦆ⪖ࡢ୺࡞ཎᅉࡣࢫࣃࢵࢱࣜࣥࢢ࡛࠶ࡿ࡜⪃࠼ࡽࢀࡿ㸬ࢢࣜࢵࢻᮦᩱ࡟ࡣⅣ⣲ࡀ⏝࠸ࡽࢀ

࡚࠸ࡿࡀ㸪ࡇࡢࢢࣜࢵࢻᮦᩱࡢᦆ⪖ࡣ㐠㌿᫬㛫ࡀᩘ୓᫬㛫ࢆ㉺࠼ࡿࡣࡸࡪࡉࡢィ⏬࡟࠾࠸࡚ࡣ㸪࢖࢚࢜ࣥࣥࢪࣥࡢᑑ࿨ࢆᕥྑ

ࡍࡿせᅉࡢ୍ࡘ࡟࡞ࡿࡇ࡜ࡀண᝿ࡉࢀ㸪ᮦᩱᦆ⪖ࡢṇ☜࡞▱ぢࡀᚲせ࡜ࡉࢀࡿ㸬

⌧ᅾࡢ࡜ࡇࢁࡑࡢᦆ⪖ホ౯࡟ᒣᮧࡽ࡟ࡼࡗ࡚ᥦ᱌ࡉࢀࡓᆶ┤ධᑕ࡟ᑐࡍࡿࢫࣃࢵࢱࣜࣥࢢ཰㔞ࡢ༙⤒㦂ᘧ [1]࡞࡝ࡀ⏝࠸

ࡽࢀ࡚࠸ࡿࡀ㸪࢟ࢭࣀࣥ㸫Ⅳ⣲ࡢ⤌ࡳྜࢃࡏ࡟࠾࠸࡚㸪ධᑕ࢚ࢿࣝࢠ࣮ࡀ 100eV ௨ୗࡢప࢚ࢿࣝࢠ࣮㡿ᇦ࡛ᐇ㦂ࢹ࣮ࢱ࡜኱ࡁ

࡞㛤ࡁࡀࡳࡽࢀࡿ [2][3]㸬༙⤒㦂ᘧ࠿ࡽᑟ࠿ࢀࡿࢫࣃࢵࢱࣜࣥࢢࡢࡋࡁ࠸್ࡣ160.84 eV ࡜࡞ࡾ㸪ᐇ㦂࡛ࡣ㸪ࡋࡁ࠸್௨ୗࡢධ ᑕ࢚ࢿࣝࢠ࣮࡛ࢫࣃࢵࢱࣜࣥࢢࡀほ ࡉࢀ࡚࠸ࡿࡇ࡜࡟࡞ࡿ㸬ࡇࢀ࡟ᑐࡋ㸪࢟ࢭࣀࣥ㸫ࣔࣜࣈࢹࣥࡢ⤌ࡳྜࢃࡏ࡟࠾࠸࡚ࡣ㸪

༙⤒㦂ᘧࡣᐇ㦂ࢹ࣮ࢱ࡜ࡼࡃ୍⮴ࡍࡿ [3]㸬⌧ᅾࡲ࡛࡟㸪ࡇࡢࢫࣃࢵࢱࣜࣥࢢࡢ㐪࠸ࡢཎᅉ࡟ࡘ࠸࡚༑ศゎ᫂ࡉࢀ࡚࠸ࡿ࡜ࡣ

࠸࠼࡞࠸㸬ᮏሗ࿌࡛ࡣ㸪ࡇࡢホ౯ࡀ㞴ࡋ࠸࢟ࢭࣀࣥ㸫Ⅳ⣲ࡢ⤌ࡳྜࢃࡏ࡟࠾࠸࡚㸪⌮ㄽⓗ࡟ண᝿ࡉࢀࡿࡋࡁ࠸್௨ୗ࡛ࢫࣃࢵ

ࢱࣜࣥࢢࡀ㉳ࡇࡿ࣓࢝ࢽࢬ࣒ࢆࢫࣃࢵࢱࣜࣥࢢゎᯒࢥ࣮ࢻ ACAT [4] 㸪 ACAT-DIFFUSE [5] ࢆ⏝࠸࡚ゎᯒࢆ⾜ࡗࡓ㸬

（Presently, Yokohama National University）

㸰㸬ࢩ࣑࣮ࣗࣞࢩ࣭ࣙࣥࢥ࣮ࢻ

ࢫࣃࢵࢱࣜࣥࢢࡢゎᯒ࡟㛵ࡋ࡚㸪⌧ᅾࡲ࡛࡟㸰య⾪✺㏆ఝἲ࡜ࣔࣥࢸ࢝ࣝࣟἲࢆᇶ࡟ࡋࡓᗄࡘ࠿ࡢࢩ࣑࣮ࣗࣞࢩ࣭ࣙࣥࢥ

࣮ࢻࡀ㛤Ⓨࡉࢀ㸪ከࡃࡢ᭷⏝࡞ࢹ࣮ࢱࡀ⏕ᡂࡉࢀ࡚࠸ࡿ [6]㸬௦⾲ⓗ࡞ࡶࡢ࡟㸪 TRIM ࢥ࣮ࢻ [7]㸪ACAT ࢥ࣮ࢻ࡞࡝ࡀᣲࡆࡽࢀ

ࡿ㸬௨ୗ࡟௒ᅇゎᯒ࡟⏝࠸ࡓ ACAT ࢥ࣮ࢻ㸪 ACAT-DIFFUSE ࢥ࣮ࢻࡢ⡆༢࡞⤂௓ࢆ⾜࠺㸬

ACAT ࢥ࣮ࢻࡣ㸪๓㏙ࡢࡼ࠺࡟㸰య⾪✺㏆ఝἲ࡜ࣔࣥࢸ࢝ࣝࣟἲࢆ᥇⏝ࡋ࡚࠾ࡾ㸪ࢱ࣮ࢤࢵࢺࡣᅗ㸯࡛♧ࡉࢀࡿࡼ࠺࡟㸪 ࢱ࣮ࢤࢵࢺࢆ㸯㎶ R

㸦 N

㸪 N : ࢱ࣮ࢤࢵࢺࡢᩘᐦᗘ atoms/cm

㸧ࡢࣘࢽࢵࢺ࣭ࢭࣝ࡟ศ๭ࡋ㸪㸯ࡘࡢࣘࢽࢵࢺ࣭ࢭࣝ

࡟㸯ࡘࡢࢱ࣮ࢤࢵࢺཎᏊࢆࣛࣥࢲ࣒࡟㓄⨨ࡍࡿࡇ࡜࡛࢔ࣔࣝࣇ࢓ࢫ࣭ࢱ࣮ࢤࢵࢺࢆᙧᡂࡋ࡚࠸ࡿ㸬⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮࡜ࡋ࡚

ࡣ㸪ࢱ࣮ࢤࢵࢺࡢจ㞟࢚ࢿࣝࢠ࣮ࢆ⏝࠸ࡿ㸬

ACAT-DIFFUSE ࢥ࣮ࢻࡣ㸪ACAT ࢥ࣮ࢻ࡟ᣑᩓ᪉⛬ᘧࢆᩘ್ⓗ࡟ゎࡃ DIFFUSE ࣮ࣝࢳࣥࢆຍ࠼ࡓࡶࡢ࡛㸪ཎᏊ⾪✺࡞࡝

ࡢῶ㏿㐣⛬࡜ᣑᩓ࡞࡝ࡢ⇕ⓗ㐣⛬ࢆホ౯ࡍࡿࡇ࡜ࡀ࡛ࡁࡿ㸬ᅗ㸰࡟ ACAT-DIFFUSE ࢥ࣮ࢻࡢᴫᛕᅗࢆ♧ࡍ㸬

ACAT-DIFFUSE ࢥ࣮ࢻ࡛ࡣ㸪ᮏ᮶ྠ᫬㐍⾜ࡋ࡚࠸ࡿῶ㏿㐣⛬࡜⇕ⓗ㐣⛬ࢆ㸪⌧㇟ࡀ㉳ࡇࡿࢱ࢖࣒ࢫࢣ࣮ࣝࡀ኱ࡁࡃ␗࡞ࡿ

ࡇ࡜࠿ࡽ㸦ῶ㏿㐣⛬㸸10

⛊⛬ᗘ㸪⇕ⓗ㐣⛬㸸 10

⛊⛬ᗘ㸧 㸪ᅗ㸰࡟♧ࡍࡼ࠺࡟ῶ㏿㐣⛬࡜⇕ⓗ㐣⛬ࢆูࠎ࡟ホ౯ࡍࡿ㸬ᡭ㡰࡜

ࡋ࡚ࡣ㸪ࡲࡎ඲↷ᑕ㔞ȍࢆᚤᑠ㔞Ǽȍ࡟ศ๭ࡋ㸪Ǽȍࡀᅛయ⾲㠃࡟▐㛫ⓗ࡟↷ᑕࡉࢀࡿ࡜ࡋ࡚㸪ACAT ࣮ࣝࢳ࡛ࣥῶ㏿㐣⛬ࢆ

ホ౯ࡋ㸪ࡑࡢᚋǼȍ࡟ᑐᛂࡍࡿᚤᑠ᫬㛫Ǽ t 㸦 =ǻĭ/J 㸪 J 㸸ࣅ࣮࣒ࡢࣇࣛࢵࢡࢫ [cm-

s

] 㸧ࡔࡅ㸪 ACAT ࣮ࣝࢳ࡛ࣥᚓࡽࢀࡓධᑕ

⢏Ꮚࡢ῝ࡉศᕸ㸪᱁ᏊḞ㝗ศᕸ࡞࡝ࢆ⏝࠸࡚ᣑᩓࡢホ౯ࢆ⾜࠺㸬ࡑࢀࢆ஺஫࡟⾜࠺ࡇ࡜࡛ࢲ࢖ࢼ࣑࣭࢝ࣝࢩ࣑࣮ࣗࣞࢩࣙࣥࢆ

⾜࠺㸬

ᅗ㸯 ACAT ࣔࢹࣝ

ᅗ㸰 ACAT-DIFFUSE ࢥ࣮ࢻࡢᴫᛕᅗ R

㸸ධᑕ⢏Ꮚ 㸸ࢱ࣮ࢤࢵࢺཎᏊ

࣭࣭࣭࣭࣭

ACA T ACA T ACA T ACA T DIFFUSE DIFFUSE DIFFUSE

࣭࣭࣭࣭࣭

㸱㸬ゎᯒ⤖ᯝ

ᅗ㸱࡟ᆶ┤ධᑕࡢሙྜࡢ࢟ࢭࣀࣥ㸫Ⅳ⣲ࡢ⤌ࡳྜࢃࡏ࡟࠾ࡅࡿᐇ㦂ࢹ࣮ࢱ[2, 8-12]㸪ᒣᮧ➼࡟ࡼࡗ࡚ᑟ࠿ࢀࡓ༙⤒㦂ᘧ [1]

ཬࡧ ACAT ࢥ࣮ࢻࡢゎᯒ⤖ᯝࢆ♧ࡍ㸬ᅗࡼࡾ㸪 ACAT ࢥ࣮ࢻࡢィ⟬⤖ᯝࡣ㸪༙⤒㦂ᘧ࡟㏆࠸್ࢆ࡜ࡗ࡚࠸ࡿ㸬ࡑࢀ࡟ᑐࡋ㸪ᐇ 㦂ࢹ࣮ࢱ࡜ࡣ㸪኱ࡁ࡞㐪࠸ࡀぢࡽࢀࡿ㸬≉࡟㸪ప࢚ࢿࣝࢠ࣮㡿ᇦ࡛㸪ࡑࡢ㐪࠸ࡀ㢧ⴭ࡟࡞ࡗ࡚࠸ࡿ㸬 ͆ࡣࡸࡪࡉ㸰͇ࡢ࢖࢜ࣥ

࢚ࣥࢪ࣭ࣥࢢࣜࢵࢻ௜㏆࡛ࡢ࢟ࢭࣀࣥ࢖࢜ࣥࡢ࢚ࢿࣝࢠ࣮ࡀᩘⓒ eV ௨ୗ࡛࠶ࡿࡇ࡜ࢆ⪃៖ࡍࡿ࡜㸪ࡇࡢ㐪࠸ࡣ࢖࢚࢜ࣥࣥࢪ

ࣥ㛤Ⓨ࡟࠾࠸࡚኱ࡁ࡞ၥ㢟࡜࡞ࡿ㸬

⌮ㄽⓗ࡟ண᝿ࡉࢀࡿࢫࣃࢵࢱࣜࣥࢢࡢࡋࡁ࠸್௨ୗ࡛ࢫࣃࢵࢱࣜࣥࢢࡀ㉳ࡇࡿ୍ࡘࡢཎᅉ࡜ࡋ࡚㸪࢖࢜ࣥ↷ᑕ࡟ࡼࡿⅣ⣲

ᮦᩱ୰ࡢ࢟ࢭࣀࣥ࢖࢜ࣥ⵳✚ࡢᙳ㡪ࡀ⪃࠼ࡽࢀࡿ㸬ᐇ㝿㸪 Doener ➼࡟ࡼࡗ࡚࢟ࢭࣀࣥࣉࣛࢬ࣐ࢆⅣ⣲ᮦᩱ࡟↷ᑕࡋࡓሙྜ㸪↷

ᑕᚋࡢᮦᩱ୰࡟⣙ 14%ࡢ࢟ࢭࣀࣥࡀ⵳✚ࡋ࡚࠸ࡓࡇ࡜ࡀሗ࿌ࡉࢀ࡚࠸ࡿ [8]㸬ࢫࣃࢵࢱࣜࣥࢢ࡟ᑐࡍࡿධᑕ⢏Ꮚࡢᮦᩱ୰࡬ࡢ⵳

✚ࡢᙳ㡪࡟ࡘ࠸࡚ࡣ㸪ྠࡌ㉁㔞ࡢ⢏Ꮚྠኈࡀ᭱ࡶ࢚ࢿࣝࢠ࣮௜୚ຠ⋡ࡀ㧗࠸ࡓࡵ࡟ Xe ࡀ⵳✚ࡍࡿࡇ࡜࡟ࡼࡗ࡚㸪⾲㠃㏆ഐ࡟

௜୚ࡉࢀࡿ࢚ࢿࣝࢠ࣮ࡀቑຍࡍࡿࡇ࡜ࡀ⪃࠼ࡽࢀࡿ㸬ࡲࡓ㸪Ⅳ⣲ཎᏊࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮ࡀኚ໬ࡍࡿࡇ࡜ࡶྍ⬟ᛶ࡜ࡋ࡚⪃

࠼ࡽࢀࡿ㸬௒ᅇ㸪 Xe ⵳✚࡟ࡼࡿ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮ࡢኚ໬࡟ࡘ࠸࡚㸪ACAT ࢥ࣮ࢻࢆ⏝࠸࡚ゎᯒࢆ⾜ࡗࡓ㸬ࡇࡇ࡛㸪 ACAT ࢥ࣮ࢻࡣ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮࡜ࡋ࡚㸪ࢱ࣮ࢤࢵࢺཎᏊࡢจ㞟࢚ࢿࣝࢠ࣮ࢆ᥇⏝ࡋ࡚࠾ࡾ㸪Ⅳ⣲ᮦᩱ࡟ࡘ࠸࡚ࡣ 7.37 eV ࢆ⏝࠸

ࡓ㸬࢟ࢭࣀࣥ⵳✚࡟ࡼࡿ⾲㠃㏆ഐࡢ࢚ࢿࣝࢠ࣮௜୚ቑຍ࡟ࡘ࠸࡚ࡣ㸪௒ᚋACAT ࢥ࣮ࢻࢆ⏝࠸࡚ゎᯒࡍࡿணᐃ࡛࠶ࡿ㸬 ධᑕ⢏Ꮚࡢ⵳✚࡟ࡼࡗ࡚⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮ࡀኚ໬ࡍࡿຠᯝࢆ᳨ドࡍࡿࡓࡵ࡟㸪ḟᘧ࡛♧ࡉࢀࡿ㸰ඖ⣔ᮦᩱ AB ࡟ᑐࡍࡿ

⾲㠃⤖ྜࣔࢹࣝ [13]ࢆ ACAT ࢥ࣮ࢻ࡟᥇⏝ࡋゎᯒࢆ⾜ࡗࡓ㸬

ࡇࡇ࡛㸪U

ࡣᮦᩱ AB ୰ࡢ A ཎᏊࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮㸪U

ࡣᮦᩱ AB ୰ࡢ B ཎᏊࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮㸪U

ࡣ༢ཎ Ꮚᅛయ A ࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮㸪 U

ࡣ༢ཎᏊᅛయ B ࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮㸪 c

ࡣᮦᩱ AB ୰ࡢ A ཎᏊࡢ⃰ᗘ㸪 c

ࡣᮦᩱ AB

୰ࡢ B ཎᏊࡢ⃰ᗘ࡛࠶ࡿ㸬ᅗ㸲࡟㸪ࡇࡢࣔࢹࣝࢆ⏝࠸࡚Ⅳ⣲ᮦᩱ୰࡟࢟ࢭࣀࣥཎᏊࡀ⵳✚ࡋࡓሙྜࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮ࡢኚ

໬ࢆ♧ࡍ㸬ᅗ㸲ࡼࡾ㸪௒ᅇ᥇⏝ࡋࡓ⾲㠃⤖ྜࣔࢹ࡛ࣝࡣ㸪Ⅳ⣲ᮦᩱ୰࡟࢟ࢭࣀࣥࡀ⵳✚ࡍࡿࡇ࡜࡟ࡼࡾ㸪Ⅳ⣲ཎᏊࡢ⾲㠃⤖ྜ

࢚ࢿࣝࢠ࣮ࡀῶᑡࡋ࡚࠸ࡃࡇ࡜ࡀศ࠿ࡿ㸬 ᐇ㦂࡛ほ ࡉࢀࡓ 14 %ࡢ࢟ࢭࣀࣥࡀⅣ⣲ᮦᩱ୰࡟⵳✚ࡋࡓሙྜࡢⅣ⣲ཎᏊࡢ⾲㠃

⤖ྜ࢚ࢿࣝࢠ࣮ࢆồࡵࡿ࡜ 6.87 eV ࡜࡞ࡾ㸪࢟ࢭࣀࣥཎᏊࡢ⤖ྜ࢚ࢿࣝࢠ࣮ࡣ3.26 eV ࡜࡞ࡿ㸬ࡇࡇ࡛㸪༢ཎᏊᅛయࡢሙྜࡢ⾲

㠃⤖ྜ࢚ࢿࣝࢠ࣮࡜ࡋ࡚㸪ࡑࢀࡒࢀⅣ⣲㸸 7.37 eV 㸪࢟ࢭࣀࣥ㸸 0.16 eV ࢆ⏝࠸ࡓ㸬ࡇࡢ⤖ྜࣔࢹࣝࡣ 2 ✀㢮ࡢཎᏊࢆΰྜࡋࡓ ᅗ㸱 Xe

Ѝ C at 0

ࡢࢫࣃࢵࢱࣜࣥࢢ཰㔞

AB

AB A BB B B

AB B AA A A

2

1 U U

U

U c U c U

U c U c U

10

10

10

10

10

10

10

10

Rosenberg and Wehner [9]

Deltschew et al. [10]

Gruber et al. [2]

Williams et al. [11]

Funaki et al. [12]

Doener et al. [8]

ACATYamamura formula [1]

Threshold [1]

Sputt eri n g yie ld (atoms/i on )

Incident Energy (eV)

E

= 160.84 eV

ሙྜࡢ⤖ྜ࢚ࢿࣝࢠ࣮ࢆホ౯ࡍࡿᘧ࡛࠶ࡿࡢ࡛㸪ᕼ࢞ࢫ࡛࠶ࡿ࢟ࢭࣀࣥཎᏊ࡜Ⅳ⣲ཎᏊࡢ⤖ྜࡀᡂࡾ❧ࡘࡇ࡜ࡀ๓ᥦ࡜࡞ࡗ࡚

࠸ࡿ㸬ࡋ࠿ࡋ࡞ࡀࡽ㸪ᕼ࢞ࢫ࡛࠶ࡿ࢟ࢭࣀࣥཎᏊࡀ௚ࡢཎᏊ࡜⤖ྜࡍࡿ࡜࠸࠺ࡇ࡜ࡣ⪃࠼࡟ࡃࡃ㸪ࡇࡢࣔࢹࣝࢆࡑࡢࡲࡲ⌧ᅾ ࡢ⣔࡟㐺⏝ࡍࡿࡇ࡜ࡣ㐺ᙜ࡛࠶ࡿ࡜ࡣゝ࠸㞴࠸ࡀ㸪௒ᅇࡣ㸪࢟ࢭࣀࣥࡢ⵳✚࡟ࡼࡿ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮ࢆᐃ㔞ⓗ࡟ホ౯ࡍࡿࡓ

ࡵ࡟㸪ࡇࡢࣔࢹࣝࢆ⏝࠸࡚ィ⟬ࢆ⾜ࡗࡓ㸬

ᅗ㸳࡟ ACAT ࢥ࣮ࢻࢆ⏝࠸࡚㸪Ⅳ⣲ᮦᩱ୰࡟࢟ࢭࣀࣥཎᏊࢆ 14%⵳✚ࡉࡏࡓࢱ࣮ࢤࢵࢺ࡟࢟ࢭࣀࣥ࢖࢜ࣥࢆ↷ᑕࡋࡓሙ

ྜࡢ⤖ᯝࢆ♧ࡍ㸬ᅗࡼࡾ㸪࢟ࢭࣀࣥࡀ⵳✚ࡉࢀࡿࡇ࡜࡟ࡼࡗ࡚㸪Ⅳ⣲ཎᏊࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮ࡀῶᑡࡋ㸪ࢫࣃࢵࢱࣜࣥࢢࡢ ࡋࡁ࠸್௨ୗࡢప࢚ࢿࣝࢠ࣮㡿ᇦ࡟࠾࠸࡚ࡶࢫࣃࢵࢱࣜࣥࢢࡀ㉳ࡗ࡚࠸ࡿࡇ࡜ࡀ♧ࡉࢀࡿ㸬ࡲࡓ㸪Ⅳ⣲༢యࡢࢱ࣮ࢤࢵࢺࡢ ACAT ⤖ᯝ࡟ẚ࡭࡚ᐇ㦂ࢹ࣮ࢱ࡜ࡼࡃ୍⮴ࡋ࡚࠸ࡿ㸬༙⤒㦂ᘧ࡜ᅗ㸱࡛♧ࡋࡓ ACAT ࡢゎᯒ⤖ᯝࡣ㸪࡝ࡕࡽࡶࢱ࣮ࢤࢵࢺཎᏊ

࡜ࡋ࡚ࡣ㸪Ⅳ⣲ཎᏊࡢࡳࢆ⪃៖ࡋ࡚࠾ࡾ㸪ධᑕ⢏Ꮚࡢ⵳✚ࡢຠᯝࡣྲྀࡾධࢀࡽࢀ࡚࠸࡞࠸㸬࢟ࢭࣀࣥ㸫ࣔࣜࣈࢹࣥࡢࢫࣃࢵࢱ

ࣜࣥࢢ཰㔞ࡀ㸪༙ᐇ㦂ᘧ࡜ࡼࡃ୍⮴ࡍࡿࡢࡣ㸪ࣔࣜࣈࢹࣥ୰ࡢ࢟ࢭࣀࣥࡢᣑᩓࡀ㏿࠸ࡓࡵ࡟㸪ࢫࣃࢵࢱࣜࣥࢢ࡟㛵ಀࡍࡿ⾲㠃

㏆ഐ࡟⵳✚ࡍࡿࡢ࡛ࡣ࡞ࡃ㸪ࢱ࣮ࢤࢵࢺෆ㒊ࡢࡼࡾ῝࠸㡿ᇦ࡟ศᕸࡍࡿࡓࡵ࡟࢟ࢭࣀࣥࡢ⵳✚ࡢຠᯝࡀᑡ࡞࠸ࡓࡵ࡛࠶ࡿ࡜⪃

࠼ࡽࢀࡿ㸬

ࡑࢀ࡟ᑐࡋ࡚㸪Ⅳ⣲ᮦᩱࡣ㸪࢟ࢭࣀࣥࡢᣑᩓࡀ㐜࠸ࡓࡵ࡟㸪⾲㠃㏆ഐ࡟⵳✚ࡋ㸪ࢫࣃࢵࢱࣜࣥࢢ࡟ᙳ㡪ࢆཬࡰࡍ㸬Ⅳ⣲ᮦ

ᩱ୰ࡢ࢟ࢭࣀࣥࡢᣑᩓಀᩘ࡟ࡘ࠸࡚ࡣ㸪ᐇ㦂ࢹ࣮ࢱࡀ୙㊊ࡋ࡚࠾ࡾ㸪ṇ☜࡟Ⅳ⣲ᮦᩱࡢࢫࣃࢵࢱࣜࣥࢢࢆホ౯ࡍࡿࡓࡵ࡟ࡣ㸪

௒ᚋ㔜せ࡞ᇶ♏ࢹ࣮ࢱࡢ㸯ࡘ࡜࡞ࡿ࡜ᛮࢃࢀࡿ㸬ࡲࡓ㸪௒ᅇࡢゎᯒ⤖ᯝ࠿ࡽ㸪ධᑕ Xe ࡀᅛయ⾲㠃࡟⵳✚ࡍࡿࡇ࡜࡟ࡼࡾ㸪Ⅳ

⣲ཎᏊࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮ࡀῶᑡࡋ㸪ࡑࢀ࡟కࡗ࡚ࢫࣃࢵࢱࣜࣥࢢࡢࡋࡁ࠸್ࡶῶᑡࡍࡿ࡜࠸࠺ྍ⬟ᛶࡀ⪃࠼ࡽࢀࡿ㸬ࡋ࠿

ࡋ࡞ࡀࡽ㸪ᕼ࢞ࢫ࡛࠶ࡿ Xe ཎᏊࡀⅣ⣲ཎᏊࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮࡟࡝ࡢࡼ࠺࡟ᙳ㡪ࡍࡿ࠿ࡣ㸪⌧ᅾࡢ࡜ࡇࢁ୙࡛᫂࠶ࡿ㸬௒

ᅗ㸲 ࢟ࢭࣀࣥࡀⅣ⣲ᮦ࡟⵳✚ࡍࡿࡇ࡜࡟ࡼࡿⅣ⣲ཎᏊ㸪࢟ࢭࣀࣥཎᏊࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮ࡢኚ໬

ᅗ㸳 ࢟ࢭࣀࣥࢆ 14%Ⅳ⣲ᮦ࡟⵳✚ࡉࡏࡓሙྜࡢ ACAT ⤖ᯝ 10

10

10

10

10

10

10

10

Rosenberg and Wehner [9]

Deltschew et al. [10]

Gruber et al. [2]

Williams et al. [11]

Funaki et al. [12]

Doener et al. [8]

ACAT (Xe : 0%) ACAT (Xe : 14%) Yamamura_formula Threshold

Sputt er ing yie ld (atoms/ion)

Incident Energy (eV)

E

= 160.84 eV

ᅇ⏝࠸ࡓ⾲㠃⤖ྜࣔࢹ࡛ࣝࡣホ౯࡛ࡁ࡞࠸ྍ⬟ᛶࡶ⪃࠼ࡽࢀࡿ㸬

Ⅳ⣲୰ࡢ࢟ࢭࣀࣥࡢᣑᩓಀᩘࡀ⌧ᅾࡢ࡜ࡇࢁᮍ▱࡛࠶ࡿࡀ㸪ࡇࡢᣑᩓಀᩘཬࡧࢺࣛࢵࣉࢧ࢖ࢺࡢ⤖ྜ࢚ࢿࣝࢠ࣮ࢆࣇ࢕ࢵ

ࢸ࢕ࣥࢢࣃ࣓࣮ࣛࢱ࡜ࡋ࡚㸪 100 eV Xe

ĺ C at 0

࡟ࡘ࠸࡚㸪⾲㠃➨㸯ᒙࡢ࢟ࢭࣀࣥࡢ⵳✚㔞ࡀ 14% ࡜࡞ࡿࡼ࠺࡟Ỵࡵࡓᣑᩓಀ

ᩘࢆ⏝࠸࡚ ACAT-DIFFUSE ࢥ࣮ࢻ࡛㸪↷ᑕ࡟ࡼࡿⅣ⣲ᮦᩱ୰ࡢ࢟ࢭࣀࣥࡢ⵳✚࡜ࢫࣃࢵࢱࣜࣥࢢ཰㔞ࡢ᫬㛫ኚ໬ࢆゎᯒࡋࡓ

⤖ᯝࢆᅗ㸴㸪ᅗ㸵࡟♧ࡍ㸬ࡇࡇ࡛㸪Ⅳ⣲ᮦᩱ୰ࡢ࢟ࢭࣀࣥ࢖࢜ࣥࡢᣑᩓಀᩘࡣ D T 1 . 0 u 10

exp 0 . 55 kT ࡜ࡋࡓ㸬 k ࡣ

࣎ࣝࢶ࣐ࣥᐃᩘ࡛࠶ࡿ㸬ࡲࡓ㸪ࢱ࣮ࢤࢵࢺࡢ ᗘ T ࡣ 473 K㸪࢖࢜ࣥࣇࣛࢵࢡࢫࡣ 1.0×10

cm

࣭s

㸪ࢱ࣮ࢤࢵࢺ୰࡟ࡣ㸰✀㢮 ࡢࢺࣛࢵࣉࢧ࢖ࢺࢆ⪃៖ࡋ㸪ࢹ࢕ࢺࣛࢵࣉ࣭࢚ࢿࣝࢠ࣮ࡣࡑࢀࡒࢀ 0.8 eV 㸪 3.44 eV ࡜ࡋࡓ㸬

ᅗ㸴ࡼࡾ㸪௒ᅇࡢィ⟬࡛⏝࠸ࡓᣑᩓಀᩘ࡛ࡣ㸪↷ᑕ㸯⛊ᮍ‶࡛ᅛయ⾲㠃ࡢ࢟ࢭࣀࣥࡢ⵳✚㔞ࡀ 14% ⛬ᗘ࡟࡞ࡾ㸪ࡑࡢᚋࡣ

࡯ࡰ୍ᐃ࡜࡞ࡿ㸬ࢫࣃࢵࢱࣜࣥࢢ཰㔞࡟㛵ࡋ࡚ࡶ㸪Ⅳ⣲ࡢࢫࣃࢵࢱࣜࣥࢢ཰㔞ࡣ࡯ࡰ୍ᐃ࡜࡞ࡿ㸬࢟ࢭࣀࣥࡢ⵳✚㔞㸪⾲㠃ࡢ

⃰ᗘࡣࢱ࣮ࢤࢵࢺ ᗘ࡟౫Ꮡࡍࡿࡓࡵ㸪ࢫࣃࢵࢱࣜࣥࢢ཰㔞ࡢホ౯ࢆ⾜࠺ሙྜ㸪ࢱ࣮ࢤࢵࢺࡢ ᗘࡶὀពࡍࡿᚲせࡀ࠶ࡿ㸬

0.2 0.4 0.6 0.8 1

0 1 2 3 4 5

C Xe

R atio at top m ost la ye r

Time (s)

ᅗ㸴 Ⅳ⣲ᮦᩱ୰࡟࠾ࡅࡿ࢟ࢭࣀࣥࡢ⵳✚ࡢ᫬㛫ኚ໬

0 0.002 0.004 0.006 0.008 0.01 0.012

0 1 2 3 4 5

C Sputtering yield (atoms/ion) Xe

Time (s)

ᅗ㸵 ࢫࣃࢵࢱࣜࣥࢢ཰㔞ࡢ᫬㛫ኚ໬

㸲㸬ࡲ࡜ࡵ

ᝨᫍ᥈ᰝᶵ͆ࡣࡸࡪࡉ㸰͇ࡢ࢖࢚࢜ࣥࣥࢪࣥ㛤Ⓨ࡟࠾࠸࡚ၥ㢟࡜࡞ࡗ࡚࠸ࡿ࢟ࢭࣀࣥ࢖࢜ࣥ࡟ࡼࡿⅣ⣲ᮦᩱࡢᦆ⪖ࢆࢫࣃ

ࢵࢱࣜࣥࢢゎᯒࢥ࣮ࢻACAT㸪ACAT-DIFFUSE ࢆ⏝࠸࡚ゎᯒࢆ⾜ࡗࡓ㸬

⌮ㄽⓗ࡟ண᝿ࡉࢀࡿࢫࣃࢵࢱࣜࣥࢢࡢࡋࡁ࠸್௨ୗࡢప࢚ࢿࣝࢠ࣮࡛ࡢࢫࣃࢵࢱࣜࣥࢢࡣ㸪࢟ࢭࣀࣥࡀⅣ⣲ᮦᩱ࡟⵳✚ࡍ

ࡿࡓࡵ࡟ᘬࡁ㉳ࡇࡉࢀࡿ࡜⪃࠼ࡽࢀࡿ㸬࢟ࢭࣀࣥࡢ⵳✚࡟ࡼࡗ࡚㸪Ⅳ⣲ཎᏊࡢࢫࣃࢵࢱࣜࣥࢢ཰㔞ࡸ⾲㠃࡟௜୚ࡉࢀࡿ࢚ࢿࣝ

ࢠ࣮ࡢቑຍࡀྍ⬟ᛶ࡜ࡋ࡚⪃࠼ࡽࢀࡿ㸬 ACAT ࢥ࣮ࢻ⏝࠸࡚ゎᯒࢆ⾜ࡗࡓ⤖ᯝ㸪ධᑕ࢟ࢭࣀࣥࡢ⵳✚࡟ࡼࡿ⾲㠃⤖ྜ࢚ࢿࣝࢠ

࣮ࡢῶᑡ࡟కࡗ࡚㸪ࢫࣃࢵࢱࣜࣥࢢࡢࡋࡁ࠸್ࡀῶᑡࡍࡿࡇ࡜ࡀ♧ࡉࢀࡓ㸬௒ᅇ⏝࠸ࡓ⾲㠃⤖ྜࣔࢹࣝ࡟࠾࠸࡚ࡣ㸪࢟ࢭࣀࣥ

ཎᏊ࡜Ⅳ⣲ཎᏊࡢ⤖ྜࢆ⪃៖ࡋ࡚࠾ࡾ㸪ᕼ࢞ࢫ࡛࠶ࡿ࢟ࢭࣀࣥཎᏊࡀ௚ࡢཎᏊ࡜⤖ྜࡍࡿࡇ࡜ࡣ⪃࠼࡟ࡃ࠸ࡓࡵ㸪௒ᚋ࢟ࢭࣀ

ࣥࡢ⵳✚࡟ࡼࡿⅣ⣲ཎᏊࡢ⾲㠃⤖ྜ࢚ࢿࣝࢠ࣮࡟㛵ࡋ࡚㸪ࡉࡽ࡟㐍ࡵࡓ㆟ㄽࡀᚲせ࡛࠶ࡿ㸬⌧ᅾ㐍ࡵ࡚࠸ࡿࢫࣃࢵࢱࣜࣥࢢᐇ 㦂࡟ࡼࡗ࡚Ⅳ⣲ཎᏊࡢ⤖ྜ࢚ࢿࣝࢠ࣮ኚ໬ࢆ ᐃࡍࡿணᐃ࡛࠶ࡿ㸬ࡲࡓ㸪࢟ࢭࣀࣥ⵳✚࡟ࡼࡿ⾲㠃㏆ഐࡢ࢚ࢿࣝࢠ࣮௜୚ቑຍ

࡟ࡘ࠸࡚ࡶ㸪 ACAT ࢥ࣮ࢻࢆ⏝࠸࡚ゎᯒࡍࡿணᐃ࡛࠶ࡿ㸬

ࡉࡽ࡟㸪࢟ࢭࣀࣥࡢ⵳✚ࢆホ౯ࡍࡿࡓࡵ࡟ࡣ㸪࢟ࢭࣀࣥࡢⅣ⣲ᮦᩱ୰ࡢᣑᩓಀᩘ࡞࡝ࡢᇶ♏ⓗ࡞ࢹ࣮ࢱࡀ୙㊊ࡋ࡚࠾ࡾ㸪 ࢫࣃࢵࢱࣜࣥࢢࡢṇ☜࡞ホ౯ࢆ⾜࠺ࡓࡵ࡟ࡣ௒ᚋ㔜せ࡟࡞ࡗ࡚ࡃࡿ࡜ᛮࢃࢀࡿ㸬ࡉࡽ࡟㸪ᅛయ⾲㠃㏆ഐࡢ࢟ࢭࣀࣥࡢ⵳✚㔞ࡣ ࢱ࣮ࢤࢵࢺࡢ ᗘ࡟౫Ꮡࡍࡿࡓࡵ㸪ࢫࣃࢵࢱࣜࣥࢢ཰㔞ࡶ ᗘ౫Ꮡᛶࢆᣢࡘࡇ࡜ࡀ⪃࠼ࡽࢀࡿ㸬ࡇࡢࢫࣃࢵࢱࣜࣥࢢࡢ ᗘ౫ Ꮡᛶࡶ௒ᚋ᳨ウࡍࡿᚲせࡀ࠶ࡿ࡜ᛮࢃࢀࡿ㸬

ཧ⪃ᩥ⊩

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[2] Gruber, J. R., “Low-Energy Sputter Erosion of Various Materials in a T5 Ion Thruster”, IEPC-01-307, 2001.

[3] ⓒṊ ᚭ㸪す⏣㏔㞝㸪๢ᣢ㈗ᘯ㸪ᮧᮏဴஓ㸪࢖࢚࢜ࣥࣥࢪࣥຍ㏿ࢢࣜࢵࢻ࡟࠾ࡅࡿࢫࣃࢵࢱࣜࣥࢢゎᯒ࡟ྥࡅ࡚㸪Ᏹᐂ⯟

✵◊✲㛤Ⓨᶵᵓ≉ู㈨ᩱ㸪JAXA-SP-06-019㸪2007.

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[5] Yamamura, Y, “Computer Studies of Reemission and Depth profiles for Herium on Molybdenm”, pp. 17-26., 1987.

[6] Yamamura, Y. , Itikawa, Y. and Itoh, N., “Angular Dependence of Sputtering Yields of Monoatomic Solds”, Inst. Plasma Physics, Nagoya Univ., IIPJ-AM-26, 1983.

[7] Biersack, J. P. and Haggmark, L. G., “A Monte Carlo Computer Program for Transport of Energetic Ions in Amorphous Targets”, Nucl. Instrum. & Methods 1174, pp. 257-269. 1980.

[8] Doerner, R. P., Whyte, D. G., Goebel, D. M., “Sputtering yield measurements during Low Energy Xenon Plasma Bombardment”, J. Appl. Phys., 993, pp. 5819-5823, 2003.

[9] Rosenberg, D. and Wehner, G. K., “Sputtering Yields for Low Energy He+-, Kr+-, and Xe+-Ion Bombardment”, J. Appl.

Phys., Vol. 33, No. 5, pp. 1842-1845, 1962.

[10] Deltschew, R., Tartz, M., Plicht, V., Hartmann, E., Neumann, H., Leiter, H. J. and Esch, J., “Sputter Characteristics of Carbon-Carbon Compound Material”, IEPC-01-118, 2001.

[11] Williams, J. D., Johnson, M. L. and Williams, D. D., “Differential Sputtering Behavior of Pyrolytic Graphite and Carbon-Carbon Composite Under Xenon Bombardment”, AIAA-2004-3788, 2004.

[12] Funaki, I., Nishiyama, K., Kuninaka, H., Toki, K., Shimizu, Y. and Toki, H., “20mN-class Microwave Discharge Ion Thruster”, IEPC-01-103, 2001.

[13] Kelly, R., “An Attempt to Understand Preferential Sputtering”, Nucl. Instrum. & Methods 1149, pp. 553-558. 1978.