JP2863412B2 - Method for analyzing trace elements in metals and semiconductors - Google Patents
Method for analyzing trace elements in metals and semiconductorsInfo
- Publication number
- JP2863412B2 JP2863412B2 JP5094584A JP9458493A JP2863412B2 JP 2863412 B2 JP2863412 B2 JP 2863412B2 JP 5094584 A JP5094584 A JP 5094584A JP 9458493 A JP9458493 A JP 9458493A JP 2863412 B2 JP2863412 B2 JP 2863412B2
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- Japan
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- concentration
- sample
- temperature
- trace
- less
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 235000013619 trace mineral Nutrition 0.000 title claims description 30
- 239000011573 trace mineral Substances 0.000 title claims description 30
- 238000000034 method Methods 0.000 title claims description 26
- 229910052751 metal Inorganic materials 0.000 title claims description 21
- 239000002184 metal Substances 0.000 title claims description 21
- 239000004065 semiconductor Substances 0.000 title claims description 13
- 150000002739 metals Chemical class 0.000 title claims description 7
- 230000008018 melting Effects 0.000 claims description 8
- 238000002844 melting Methods 0.000 claims description 8
- 238000003887 surface segregation Methods 0.000 claims description 7
- 239000011159 matrix material Substances 0.000 claims description 6
- 238000001304 sample melting Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 description 26
- 238000005259 measurement Methods 0.000 description 17
- 238000005204 segregation Methods 0.000 description 17
- 238000011088 calibration curve Methods 0.000 description 14
- 238000004458 analytical method Methods 0.000 description 12
- 238000009616 inductively coupled plasma Methods 0.000 description 11
- 239000000463 material Substances 0.000 description 8
- 238000011002 quantification Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 238000004445 quantitative analysis Methods 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 229910052737 gold Inorganic materials 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 229910052698 phosphorus Inorganic materials 0.000 description 4
- 238000004677 spark ionization mass spectrometry Methods 0.000 description 4
- 238000004544 sputter deposition Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 229910052717 sulfur Inorganic materials 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 238000010894 electron beam technology Methods 0.000 description 3
- 238000004993 emission spectroscopy Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000000516 activation analysis Methods 0.000 description 2
- -1 and conversely Substances 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 239000012776 electronic material Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000000682 scanning probe acoustic microscopy Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 238000005211 surface analysis Methods 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910052790 beryllium Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 239000012770 industrial material Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 238000003947 neutron activation analysis Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000001420 photoelectron spectroscopy Methods 0.000 description 1
- 238000004451 qualitative analysis Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000013077 target material Substances 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 238000004876 x-ray fluorescence Methods 0.000 description 1
Landscapes
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
- Investigating And Analyzing Materials By Characteristic Methods (AREA)
Description
【0001】[0001]
【産業上の利用分野】本発明は、高純度金属ならびに半
導体材料中の微量元素の定量方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining high-purity metals and trace elements in semiconductor materials.
【0002】[0002]
【従来の技術】高純度金属中の微量添加元素の定量方法
において、幾つかの方法が実用されている。すなわち、
原子吸光法、発光分光分析法、蛍光X線分析、高周波誘
導結合プラズマ発光分析法(ICP発光分析法)等があ
る。いずれの場合においても、検出限界はppm 程度であ
り、10ppm 以下の定量には精度の上で問題がある場合
が多い。また、特にC,O,N,Cl,S等の微量元素
を定量する場合には表面の汚染の影響を十分考慮する必
要がある。更に原子吸光法、発光分光分析法、ICP発
光分析法においては、試料を非破壊状態で測定すること
は困難である。また発光分光分析のうち、検出感度が比
較的高いグリムグロー放電法は、数mm径の平面を持つ試
料が必要である等、試料形状の制約も多い。蛍光X線測
定においては、Naより軽い元素を測定するのは難し
い。2. Description of the Related Art Several methods have been put to practical use for quantifying trace added elements in high-purity metals. That is,
Atomic absorption, emission spectroscopy, fluorescent X-ray analysis, high frequency inductively coupled plasma emission analysis (ICP emission analysis), and the like. In any case, the detection limit is on the order of ppm, and the determination of 10 ppm or less often has a problem in accuracy. In particular, when quantifying trace elements such as C, O, N, Cl, and S, it is necessary to sufficiently consider the influence of surface contamination. Furthermore, it is difficult to measure a sample in a nondestructive state by the atomic absorption method, the emission spectrometry, and the ICP emission analysis. Also, among emission spectroscopy, the Grimm glow discharge method, which has a relatively high detection sensitivity, requires a sample having a plane with a diameter of several mm, and there are many restrictions on the sample shape. In fluorescent X-ray measurement, it is difficult to measure an element lighter than Na.
【0003】定量下限を1ppm とする分析方法として
は、化学分析法、放射化分析、スパークソース質量分析
(SSMS)、2次イオン質量分析装置(SIMS)等
が挙げられるが、化学分析法では、試料が比較的多量に
必要であること、また操作中の汚染、定量感度等の点で
問題がある。放射化分析法は最も高感度といえるが、熱
中性子放射化分析は原子炉を必要とするのであまり一般
的とはいえない。また、SSMS,SIMS等も試料調
整が困難で、また全ての元素が定量できるわけではな
い。SIMSはSSMSと比べて精度はよく、局所分析
には優れているが、逆に平均的な組成を求めるには問題
がある。[0003] Analytical methods for setting the lower limit of quantification to 1 ppm include chemical analysis, activation analysis, spark source mass spectrometry (SSMS), and secondary ion mass spectrometer (SIMS). There are problems in that a relatively large amount of sample is required, contamination during the operation, and quantitative sensitivity. Activation analysis is the most sensitive, but thermal neutron activation analysis is less common because it requires a reactor. Also, SSMS, SIMS and the like are difficult to prepare samples, and not all elements can be quantified. SIMS has higher accuracy and better local analysis than SSMS, but has a problem in obtaining an average composition.
【0004】[0004]
【発明が解決しようとする課題】上述のように高純度金
属中の微量元素の定量方法は、10ppm オーダー以下の
微量元素の定量化には種々の制約がある。特に、この種
の測定においては、試料形状に制約があり、蛍光X線分
析以外は非破壊で測定することは不可能である。金属材
料、半導体材料ともに、近年の材料の高機能化に伴い、
微量元素の高精度での制御がより重要となってきた。た
とえば、半導体素子の製造に用いられるAl配線膜や高
融点金属等は通常スパッタ法により成膜されるが、その
ターゲット材料はppm 以下の不純物量に制御され製造さ
れている。またスパッタ中の残留ガス原子の取り込みに
ついても厳密な制御が必要である。また高性能オーディ
オ機器の配線、ケーブル等に使用される高純度Cuは、
99.999以上のものが使用されるようになってき
た。As described above, the method for quantifying trace elements in high-purity metals has various limitations in quantifying trace elements of the order of 10 ppm or less. In particular, in this type of measurement, the shape of the sample is limited, and it is impossible to perform nondestructive measurement other than X-ray fluorescence analysis. Both metal materials and semiconductor materials have recently become highly functional,
High-precision control of trace elements has become more important. For example, an Al wiring film, a high melting point metal, and the like used in the manufacture of a semiconductor device are usually formed by a sputtering method, and the target material is manufactured by controlling the impurity amount to less than ppm. Strict control is also required for the capture of residual gas atoms during sputtering. High-purity Cu used for wiring and cables of high-performance audio equipment is
More than 99.999 are being used.
【0005】一方、半導体実装材料として使用されてい
る、ボンディングワイヤ等もその一例であり、破断強度
や伸びといったワイヤ特性を調節するために、高純度金
属(Au)に100ppm 以下の微量元素たとえばBe,
Ca等を添加することによって用いられる。また、コン
デンサー箔に使用されている、高純度アルミニウム等、
他の電子材料、半導体材料に関しても同様に高金属中に
微量元素を添加することによってその特性を制御した
り、逆に金属中に含まれる不純物が導電性や耐食性等に
悪影響を及ぼしたりする。[0005] On the other hand, a bonding wire used as a semiconductor mounting material is also an example. In order to adjust wire characteristics such as breaking strength and elongation, a high-purity metal (Au) contains trace elements of 100 ppm or less, for example, Be. ,
It is used by adding Ca and the like. In addition, high-purity aluminum, etc. used for capacitor foil,
Similarly, the characteristics of other electronic materials and semiconductor materials are controlled by adding a trace element to a high metal, and conversely, impurities contained in the metal adversely affect conductivity, corrosion resistance, and the like.
【0006】また鉄鋼材料においても近年は、C,P,
S,N,B,O,H等の元素の高精度での制御がより重
要になってきている。たとえば深絞り鋼では、Cを10
ppm程度に制御することでその特性が著しく向上し、ま
たP,Sn,Sbは鉄鋼中で粒界に%オーダーで偏析し
て粒界脆化を引き起こすことが知られているが、バルク
中の濃度を10ppm 程度以下に低減することにより、低
温靭性、耐水素脆性が改善される。In recent years, in steel materials, C, P,
It is becoming more important to control elements such as S, N, B, O, and H with high accuracy. For example, in deep drawn steel, C is 10
It is known that the properties are remarkably improved by controlling to about ppm, and P, Sn, and Sb are segregated in the order of% at the grain boundaries in the steel to cause grain boundary embrittlement. By reducing the concentration to about 10 ppm or less, low-temperature toughness and hydrogen embrittlement resistance are improved.
【0007】本発明は、高純度金属中の微量元素を、pp
m オーダーの精度をもって定量化し、試料形状による制
約が少なく、同時に試料は非破壊で用いることができる
定量方法を提供するものである。According to the present invention, trace elements in high-purity metals are
The purpose of the present invention is to provide a quantification method in which quantification is performed with m-order accuracy, the sample shape is less restricted, and the sample can be used nondestructively.
【0008】[0008]
【課題を解決するための手段および作用】本発明は鉄鋼
材料、工業用材料、電子材料、半導体材料等中に10pp
m オーダー以下で存在する、特に材料特性に影響の大き
い微量元素が、真空中で加熱されることによって表面に
%オーダーで偏析することに着目したものであり、表面
分析装置内の真空で試料を加熱することにより、微量元
素を表面に高濃度に偏析させ、その濃度を測定すること
により、逆にバルク中の微量元素の濃度を決定する定量
法である。SUMMARY OF THE INVENTION The present invention relates to a steel material, an industrial material, an electronic material, a semiconductor material, etc.
It focuses on the fact that trace elements that exist on the order of m or less, and particularly have a significant effect on material properties, segregate on the surface in% order when heated in vacuum. This is a quantitative method in which a trace element is segregated to a high concentration on the surface by heating and the concentration of the trace element in the bulk is determined by measuring the concentration.
【0009】以下に本発明を詳細に説明する。微量元素
の制御が重要なこのような元素のほとんどは、その含有
量は微量にもかかわらず、粒界や表面に偏析しやすいと
いう特徴がある。すなわちバルク中ではppm 〜数10pp
m であっても、特定の加熱条件では表面に%オーダー存
在することが多い。またバルク中の濃度と表面濃度との
関係は加熱条件すなわち温度、時間、試料表面状態が同
一で、且つ加熱雰囲気が高真空中であれば一定である。
従ってその関係をあらかじめ決定して検量線を作成して
おけば、表面濃度の測定により、バルク濃度の決定が可
能となる。Hereinafter, the present invention will be described in detail. Most of these elements, for which control of trace elements is important, have a feature that they are easily segregated at grain boundaries and surfaces, even though their contents are very small. That is, ppm to several tens of pp in bulk
Even if m 2, it often exists on the surface in% order under specific heating conditions. The relationship between the concentration in the bulk and the surface concentration is constant if the heating conditions, that is, the temperature, time, and surface condition of the sample are the same and the heating atmosphere is in a high vacuum.
Therefore, if the relationship is determined in advance and a calibration curve is created, the bulk concentration can be determined by measuring the surface concentration.
【0010】すなわち本発明は、表面を清浄に仕上げた
金属、または半導体を10-7Torr以下の高真空の表面分
析装置内で一定温度に加熱して、異種元素の表面偏析濃
度を測定することにより、金属中及び半導体に含まれる
異種元素濃度を定量する微量元素定量法であり、特に固
溶限が小さい場合には、微量元素の濃度範囲としては含
有量がその元素の最大固溶量以下であることが好まし
い。That is, according to the present invention, a metal or semiconductor whose surface has been cleaned is heated to a constant temperature in a high vacuum surface analyzer of 10 -7 Torr or less to measure the surface segregation concentration of different elements. This is a trace element determination method that determines the concentration of different elements contained in metals and semiconductors. Particularly when the solid solubility limit is small, the content of the trace element is not more than the maximum solid solution amount of the element. It is preferred that
【0011】また表面に偏析して高濃度化するのはマト
リックス金属と微量元素の原子半径の比が0.9以下ま
たは1.1以上で顕著となるので、検出感度が上がり好
ましい。具体例としては、マトリックス金属として、C
u,Au,Al,Ag,Fe,Si,Ni,Ti,P
t,Co等が挙げられ、微量元素としては、B,C,
N,O等のガス元素、Li,Be,Al,P,S,C
a,Ti,Mn,Au,Ag,In,Sn,Si,S
b,Mo,Fe等の元素、またアルカリ金属、遷移金属
等の定量にも適用できる。The segregation on the surface to increase the concentration becomes significant when the ratio of the atomic radius between the matrix metal and the trace element is 0.9 or less or 1.1 or more. As a specific example, as a matrix metal, C
u, Au, Al, Ag, Fe, Si, Ni, Ti, P
t, Co, etc., and the trace elements include B, C,
Gas elements such as N and O, Li, Be, Al, P, S, C
a, Ti, Mn, Au, Ag, In, Sn, Si, S
The present invention can also be applied to the determination of elements such as b, Mo, and Fe, and alkali metals and transition metals.
【0012】表面分析法としてはオージェ電子分光法
(AES法)、光電子分光法(XPS法)等を用いるこ
とができる。加熱装置としては、分析装置の真空チャン
バー内もしくは、高真空分析チャンバーに連結し、高真
空を維持したまま分析室に試料を移動できる構造の高真
空チャンバー内に、加熱ステージを設置する。加熱が高
真空でない場合あるいは加熱後分析までの間に、ガス雰
囲気中にさらされると、偏析元素がガス元素と反応して
バルク濃度と表面濃度の関係が一定でなくなったり、表
面へのガス原子の吸着で表面偏析濃度を測定することが
困難となる。As the surface analysis method, Auger electron spectroscopy (AES method), photoelectron spectroscopy (XPS method) or the like can be used. As a heating device, a heating stage is installed in a vacuum chamber of the analyzer or in a high vacuum chamber connected to the high vacuum analysis chamber and capable of moving a sample to the analysis chamber while maintaining a high vacuum. If heating is not performed in a high vacuum or if it is exposed to a gas atmosphere before the analysis after heating, the segregated elements will react with the gas elements and the relationship between the bulk concentration and the surface concentration will not be constant, It becomes difficult to measure the surface segregation concentration by adsorption.
【0013】加熱機構としては、電子ビーム、電熱線、
ランプ加熱等を用いる方法が挙げられが、電子ビームの
エネルギーがオージェ電子の低エネルギー領域に影響を
及ぼすことがあるので、電熱線、ランプ加熱等の機構を
用いるのが望ましい。The heating mechanism includes an electron beam, a heating wire,
Although a method using lamp heating or the like is mentioned, since the energy of the electron beam may affect the low energy region of Auger electrons, it is desirable to use a mechanism such as a heating wire or lamp heating.
【0014】試料は、ディスク状に切り出し、効率よく
加熱するために、裏面は試料ホルダーに密着するように
平面研磨することが好ましい。測定面である表面は表面
凹凸が強度ピークに及ぼす影響を取り除くために鏡面研
磨し、更に研磨歪を取り除くために約1μm程エッチン
グを施し、次に加工歪を取り除くために、10-3Torr以
下の真空中で十分に焼鈍することが好ましい。焼鈍加熱
温度は融点の1/2以上且つ4/5以下の温度が好まし
い。融点の1/2以下では、研磨歪を十分にとることが
困難で、また4/5以上では、試料表面の蒸発により、
成分が変化する可能性がある。このように調整した試料
を、加熱ステージに取り付け、まず表面上に付着してい
る不純物や酸化物を除去し表面を清浄にするために、イ
オンスパッタリングを施す。次に真空中で加熱を行いな
がら、もしくは加熱後急冷して常温で表面に偏析した微
量原子濃度を測定する。Preferably, the sample is cut into a disk shape and the back surface is polished so as to be in close contact with the sample holder in order to heat the sample efficiently. The surface, which is the measurement surface, is mirror-polished to remove the influence of surface irregularities on the intensity peak, and further etched to about 1 μm to remove polishing strain, and then 10 -3 Torr or less to remove processing strain It is preferable to sufficiently anneal in a vacuum. The annealing heating temperature is preferably not less than 1/2 and not more than 4/5 of the melting point. Below 1/2 of the melting point, it is difficult to obtain sufficient polishing strain, and above 4/5, evaporation of the sample surface causes
Ingredients may change. The sample thus adjusted is attached to a heating stage, and first, ion sputtering is performed to remove impurities and oxides attached to the surface and clean the surface. Next, the concentration of the trace atoms segregated on the surface is measured at room temperature while heating or quenching after heating in vacuum.
【0015】測定時の真空度は、チャンバー内の残留ガ
スが表面へ吸着し、微量元素の偏析のバランスを変化さ
せるのを防ぐために、10-7Torr以下に保持することが
好ましい。一定条件の試料加熱を測定チャンバーに連結
した真空チャンバーで行い、高真空を維持したまま測定
室に移動させ、常温で測定を行うこともできる。加熱温
度の範囲は、試料融点(絶対温度)の1/4且つ50℃
(323K)以上で、融点の4/5以下が好ましい。マ
トリックス金属の融点の1/4以下では、表面に微量元
素が拡散して濃化するのに非常に長時間を要し実際的で
ない。また融点の1/4以上で、且つ拡散して表面に十
分濃化する場合でも、その温度が50℃以下であると、
室温で保持した場合の拡散が無視できなくなり、測定精
度に問題を生じる可能性が高い。また試料の融点4/5
以上では試料が揮発し、チャンバー内を汚染する恐れが
ある。加熱保持時間は微量元素の表面偏析濃度が平衡に
達するに十分な時間が望ましい。測定面積は特定結晶方
位からの表面偏析エネルギーへの影響を無視できるよう
に、結晶粒の大きさより十分に大きい範囲を用いる。The degree of vacuum during the measurement is preferably maintained at 10 -7 Torr or less in order to prevent the residual gas in the chamber from adsorbing to the surface and changing the balance of segregation of trace elements. The sample can be heated under a constant condition in a vacuum chamber connected to the measurement chamber, moved to the measurement chamber while maintaining a high vacuum, and measured at room temperature. The heating temperature range is 1/4 of the sample melting point (absolute temperature) and 50 ° C.
(323K) or more and preferably 4/5 or less of the melting point. If the melting point of the matrix metal is 1/4 or less, it takes a very long time for the trace elements to diffuse and concentrate on the surface, which is not practical. Further, even when the temperature is 1/4 or more of the melting point, and even when it is diffused and sufficiently concentrated on the surface, if the temperature is 50 ° C. or less,
Diffusion when kept at room temperature cannot be ignored, and there is a high possibility that a problem will occur in measurement accuracy. The melting point of the sample is 4/5.
In this case, the sample may volatilize and contaminate the inside of the chamber. The heating and holding time is desirably a time sufficient for the surface segregation concentration of the trace element to reach equilibrium. The measurement area is set to a range sufficiently larger than the crystal grain size so that the influence of the specific crystal orientation on the surface segregation energy can be ignored.
【0016】つぎに本発明による、表面での平衡偏析濃
度とバルク濃度の関係から微量元素を分析する方法につ
いて具体的に説明する。表面平衡偏析濃度をXsとしバ
ルク濃度をXbとするとその関係は Xs/(1−Xs)=Xb exp(A/T) (1) もしくは両辺の対数をとり ln(Xs/(1−Xs))=lnXb+A/T (1′) となる。図1にその関係を示す。Next, a method of analyzing a trace element from the relationship between the equilibrium segregation concentration on the surface and the bulk concentration according to the present invention will be specifically described. Assuming that the surface equilibrium segregation concentration is Xs and the bulk concentration is Xb, the relationship is Xs / (1−Xs) = Xb exp (A / T) (1) or ln (Xs / (1−Xs)) = LnXb + A / T (1 '). FIG. 1 shows the relationship.
【0017】Aはマトリックス金属と微量元素の種類に
より決まる定数、Tは絶対温度(K)である。定数Aを
あらかじめ求める方法としては、濃度が既知の試料を一
定温度に加熱して、その温度で濃度が一定になったこと
を確かめ、平衡濃度を測定する。温度を3水準以上変化
させて表面平衡濃度を測定して、(1′)式の左辺と1
/Tの直線の傾き(アレニウス・プロット)からAを求
める(図2)。A is a constant determined by the type of the matrix metal and the trace element, and T is the absolute temperature (K). As a method of obtaining the constant A in advance, a sample having a known concentration is heated to a constant temperature, and it is confirmed that the concentration has become constant at that temperature, and the equilibrium concentration is measured. The surface equilibrium concentration was measured by changing the temperature by at least three levels, and the left side of equation (1 ′) was
A is determined from the slope of the straight line of / T (Arrhenius plot) (FIG. 2).
【0018】各マトリックス金属と微量元素について、
Aを求めておくと、濃度未知のものについては試料を加
熱して、その時の温度Tと平衡表面濃度Xsを測定する
ことでバルク濃度を求めることができる。また濃度既知
の標準試料が3種類以上ある場合には同一温度に加熱し
て、それぞれ表面濃度が平衡に達していることを確認
し、表面平衡濃度とバルク濃度の関係を検量線として作
成しておくことが好ましい(図3)。未知試料は同一温
度、時間加熱し表面濃度を測定し検量線からバルク濃度
を求めることができる。For each matrix metal and trace element,
Once A is determined, the bulk concentration can be determined by heating the sample for those whose concentration is unknown and measuring the temperature T and the equilibrium surface concentration Xs at that time. If there are three or more standard samples with known concentrations, heat them to the same temperature, confirm that the surface concentration has reached equilibrium, and create the relationship between the surface equilibrium concentration and the bulk concentration as a calibration curve. Preferably (FIG. 3). The unknown sample can be heated at the same temperature for the same time, the surface concentration measured, and the bulk concentration determined from the calibration curve.
【0019】[0019]
【実施例】次に実施例により詳細に説明する。 (実施例1)記載の表面での平衡偏析濃度とバルク濃度
の関係からAu中Beを定量した。表面分析法として、
オージェ電子分光法を用いた。試料はあらかじめ99.
999%AuにBeを220at.%(10wt.%)添加した
ものであり、直径5mm、厚さ2mmに切り出し、表面を鏡
面研磨した後、加工歪みを取り除くために、750℃で
4時間、真空中(<10-7Torr)で焼鈍後、冷却した。
オージェ電子分光装置は(AQM 808)を用い、電
子線加速電圧5kV、試料電流値1μA、真空度5×10
-9Torrで測定した。Next, an embodiment will be described in detail. (Example 1) Be in Au was quantified from the relationship between the equilibrium segregation concentration on the surface and the bulk concentration described in (Example 1). As a surface analysis method,
Auger electron spectroscopy was used. Sample is 99.
999% Au with Be added at 220 at.% (10 wt.%), Cut out to a diameter of 5 mm and a thickness of 2 mm, mirror-polished the surface, and vacuumed at 750 ° C. for 4 hours to remove processing distortion. After annealing at a medium temperature (<10 −7 Torr), it was cooled.
Auger electron spectrometer (AQM808) was used, electron beam acceleration voltage 5 kV, sample current value 1 μA, vacuum degree 5 × 10
Measured at -9 Torr.
【0020】試料表面をあらかじめAr雰囲気中でスパ
ッタしてクリーニングした後、試料温度を300℃〜8
50℃の範囲で変化させ、それぞれの温度において、B
eの表面偏析が平衡に達したことを、ピーク高が加熱保
持時間に対して変化しなくなったことから確認し、Be
表面偏析濃度を測定した。測定中の温度調整は熱電対を
用いて行った。このようにして求められるBeの濃度を
加熱温度の逆数T-1に対してアレニウス・プロットした
結果、直線関係が得られた。直線の傾きより(1)式中
のAを求め、具体的にAu中Beの分量分析を行った。After the sample surface has been cleaned by sputtering in an Ar atmosphere in advance, the sample temperature is set to 300 ° C. to 8 ° C.
In the range of 50 ° C., at each temperature, B
It was confirmed that the surface segregation of e reached equilibrium from the fact that the peak height did not change with respect to the heating holding time.
The surface segregation concentration was measured. Temperature adjustment during the measurement was performed using a thermocouple. As a result of the Arrhenius plot of the concentration of Be determined in this manner against the reciprocal of the heating temperature T −1 , a linear relationship was obtained. A in the equation (1) was determined from the slope of the straight line, and the quantitative analysis of Be in Au was specifically performed.
【0021】Au中にBeを60at.ppm(3wt.ppm)添
加し、試料を作製し、同一溶解試料から10個切り出
し、5個の試料はAES内で500℃で加熱した後
(1)の関係式を利用し、バルク中のBe濃度を求め
た。また残りの5個は、比較としてICP法から、バル
ク濃度の測定を行った。その結果を以下に示す。Be was added to Au at 60 at. Ppm (3 wt. Ppm) to prepare a sample, and 10 samples were cut out from the same dissolved sample, and five samples were heated at 500 ° C. in AES, and then, The Be concentration in the bulk was determined using the relational expression. For the remaining five samples, the bulk concentration was measured by the ICP method for comparison. The results are shown below.
【0022】 Au−60at.ppmBe AES ICP 1 60.5 61 2 60.3 59 3 59.9 60 4 59.9 59 5 60.0 60 ―――――――――――――――――――――――――― 平均 60.12 59.8 (at.ppm) 本発明における測定値とICP法の測定値と比較して同
程度の値が得られた。また、本測定法においては表面は
高濃度しているのでAESの感度が十分であり、10pp
m 程度で精度の高い定量が可能である。加熱時の真空を
10-7以上に保持することにより、5時間内では吸着酸
素の影響がないことを確認した。Au-60 at. Ppm Be AES ICP 1 60.5 61 2 60.3 593 3 59.9 60 4 59.9 59 5 60.0 60 ――――――――――――――― ――――――――――― Average 60.12 59.8 (at.ppm) Compared with the measured value in the present invention and the measured value by the ICP method, the same value was obtained. In this measurement method, since the surface has a high concentration, the sensitivity of AES is sufficient, and 10 pp.
High precision quantification is possible at about m. By maintaining the vacuum at the time of heating at 10 -7 or more, it was confirmed that there was no influence of adsorbed oxygen within 5 hours.
【0023】(実施例2)Ni中にAuを0.5at.%
(0.23wt.%)、0.75at.%(0.35wt.%)、1
at.%(0.46wt.%)添加した試料を用いて、AES加
熱実験を行い、表面での平衡偏析濃度とバルク濃度の関
係から検量線の作成を行った。試料温度を500℃〜1
000℃の範囲で変化させ、それぞれの温度において、
0〜1000eVのエネルギー範囲でスペクトルを測定し
た。Auピーク、及びNiピークの高さの比I(Au)
/I(Ni)を縦軸に、温度を横軸にとった図を作製す
ると図4に示すような結果が得られた。次に800℃に
おける、バルク濃度を縦軸に、ピーク強度比I(Au)
/I(Ni)を横軸にとると、図5に示すような直線の
検量線が得られた。Example 2 0.5 at.% Of Au in Ni
(0.23 wt.%), 0.75 at.% (0.35 wt.%), 1
An AES heating experiment was performed using a sample to which at.% (0.46 wt.%) was added, and a calibration curve was created from the relationship between the equilibrium segregation concentration on the surface and the bulk concentration. Sample temperature 500 ℃ ~ 1
In the range of 000 ° C, and at each temperature,
The spectrum was measured in the energy range from 0 to 1000 eV. Ratio of height of Au peak and Ni peak I (Au)
When a diagram was prepared with / I (Ni) on the vertical axis and temperature on the horizontal axis, the results shown in FIG. 4 were obtained. Next, the peak intensity ratio I (Au) is plotted on the vertical axis at the bulk concentration at 800 ° C.
Taking / I (Ni) on the horizontal axis, a linear calibration curve as shown in FIG. 5 was obtained.
【0024】未知濃度試料を用いて、800℃で加熱保
持後、AuとNiのピーク強度比を測定した結果、0.
75という値を得た。図5の検量線よりこの時のバルク
濃度は0.728at.%であると定量できた。更に、同一
の試料を用いてICP測定を行った結果、0.73at.%
となりよい一致がみられた。After heating and holding at 800 ° C. using an unknown concentration sample, the peak intensity ratio between Au and Ni was measured.
A value of 75 was obtained. From the calibration curve of FIG. 5, it was determined that the bulk concentration at this time was 0.728 at.%. Further, as a result of ICP measurement using the same sample, 0.73 at.
Good agreement was found.
【0025】(実施例3)Pt中にCを0.25at.%
(0.015wt.%)、0.50at.%(0.03wt.%)、
1at.%(0.06wt.%)添加し、化学分析により、それ
ぞれの濃度の誤差が5%以内に納まっていることを確認
した試料を用いて、表面での平衡偏析濃度とバルク濃度
の関係からPt中Cの定量分析を行った。試料温度を8
00℃〜1100℃の範囲で変化させ、それぞれ任意の
温度において、0〜1000eVのエネルギー範囲でスペ
クトルを測定した。測定ピークは、Pt(237eV)、
C(272eV)を選択した。C(272eV)ピーク、及
びPt(237eV)ピークの高さの比I(C)/I(P
t)を縦軸に、温度を横軸にとった図を作製すると図6
に示すような結果が得られた。次に900℃におけるバ
ルク濃度を縦軸に、ピーク強度比I(C)/I(Pt)
を横軸にとると、図7に示すような直線の検量線が得ら
れた。Example 3 0.25 at.% Of C in Pt
(0.015 wt.%), 0.50 at.% (0.03 wt.%),
1at.% (0.06wt.%) Was added, and the relationship between the equilibrium segregation concentration on the surface and the bulk concentration was measured using a sample that was confirmed by chemical analysis that the error of each concentration was within 5%. , The quantitative analysis of C in Pt was performed. Sample temperature 8
The spectrum was measured in a range of 00 ° C. to 1100 ° C., and at an arbitrary temperature in an energy range of 0 to 1000 eV. The measured peak was Pt (237 eV),
C (272 eV) was selected. C (272 eV) peak and Pt (237 eV) peak height ratio I (C) / I (P
t) is plotted on the vertical axis and the temperature is plotted on the horizontal axis.
The result as shown in FIG. Next, the vertical axis represents the bulk concentration at 900 ° C., and the peak intensity ratio I (C) / I (Pt)
Is plotted on the horizontal axis, a linear calibration curve as shown in FIG. 7 was obtained.
【0026】ICP法により、あらかじめCの濃度が
0.3at.%(0.018wt.%)と確認された試料を用い
て、AES真空内において900℃で加熱を行い、Pt
(237eV)ピーク、及びC(272eV)ピークの高さ
の比I(C)/I(Pt)を測定した。測定の結果I
(C)/I(Pt)=1.15となった。図7に示した
検量線から試料中のC濃度は、0.31at.%であるとい
う結果が得られた。ICP法による測定と比較して精度
よい一致が得られた。従って本法を用いてPt中Cの微
量定量を行った結果、精度よく測定可能なことが明らか
となった。Using a sample in which the concentration of C was previously confirmed to be 0.3 at.% (0.018 wt.%) By the ICP method, the sample was heated at 900 ° C. in an AES vacuum to obtain Pt.
The ratio I (C) / I (Pt) of the (237 eV) peak and the C (272 eV) peak height was measured. Measurement result I
(C) / I (Pt) = 1.15. From the calibration curve shown in FIG. 7, the result that the C concentration in the sample was 0.31 at.% Was obtained. Accurate matching was obtained as compared with the measurement by the ICP method. Therefore, as a result of performing a trace amount quantification of C in Pt using this method, it became clear that measurement was possible with high accuracy.
【0027】(実施例4)Co中にCを0.05at.%
(0.01wt.%)、0.1at.%(0.02wt.%)、0.
15at.%(0.03wt.%)添加し、化学分析により、そ
れぞれの濃度の誤差が5%以内に納まっていることを確
認した試料を用いて、表面での平衡偏析濃度とバルク濃
度の関係から定量分析を行った。試料温度を650℃〜
800℃の範囲で変化させ、0〜1000eVのエネルギ
ー範囲でスペクトルを測定した。測定ピークは、Co
(775eV)、C(272eV)を選択した。Cピーク、
及びCoピークの高さの比I(C)/I(Co)を縦軸
に、温度を横軸にとった図を作製すると図8に示すよう
な結果が得られた。次に700℃におけるバルク濃度を
縦軸に、ピーク強度比I(C)/I(Co)を横軸にと
ると、図9に示すような直線の検量線が得られた。(Example 4) 0.05 at.% Of C in Co
(0.01 wt.%), 0.1 at.% (0.02 wt.%), 0.1 at.
15at.% (0.03wt.%) Was added, and the relationship between the equilibrium segregation concentration on the surface and the bulk concentration was determined using a sample whose concentration error was confirmed to be within 5% by chemical analysis. Quantitative analysis was performed. Sample temperature 650 ° C ~
The spectrum was measured in the energy range of 0 to 1000 eV while changing the temperature in the range of 800 ° C. The measured peak is Co
(775 eV) and C (272 eV). C peak,
FIG. 8 shows a result in which the vertical axis represents the ratio I (C) / I (Co) of the heights of the Co peaks and the horizontal axis represents the temperature. Next, by taking the bulk concentration at 700 ° C. on the vertical axis and the peak intensity ratio I (C) / I (Co) on the horizontal axis, a linear calibration curve as shown in FIG. 9 was obtained.
【0028】ICP法により、あらかじめCの濃度が
0.09at.%(0.018wt.%)と確認された試料を用
いて、AES真空内において700℃で加熱を行い、C
o(775eV)ピーク、及びC(272eV)ピークの高
さの比I(C)/I(Co)を測定した。測定の結果I
(C)/I(Co)=1.40となった。図9に示した
検量線から試料中のC濃度は、0.088at.%であると
いう結果が得られた。ICP法による測定と比較してよ
い一致が得られた。従って本法を用いてCo中Cの微量
定量を行った結果、精度よく測定可能なことが明らかと
なった。Using a sample in which the concentration of C was previously confirmed to be 0.09 at.% (0.018 wt.%) By the ICP method, heating was performed at 700 ° C. in an AES vacuum,
The height ratio I (C) / I (Co) of the o (775 eV) peak and the C (272 eV) peak was measured. Measurement result I
(C) / I (Co) = 1.40. From the calibration curve shown in FIG. 9, the result that the C concentration in the sample was 0.088 at.% Was obtained. Good agreement was obtained compared to the measurement by the ICP method. Therefore, as a result of performing a trace amount quantification of C in Co using the present method, it was revealed that measurement was possible with high accuracy.
【0029】[0029]
【発明の効果】以上のように、本発明によれば、金属、
半導体中に含まれる微量濃度の不純物でも、表面に%オ
ーダーで偏析することを利用すれば、高精度且つ非破壊
な定量分析が可能なことが確認できた。また、本発明は
微量元素の簡便な定性分析方法としても用いることが可
能である。As described above, according to the present invention, metal,
It has been confirmed that high-precision and non-destructive quantitative analysis can be performed by using segregation on the surface in the order of% even for a trace concentration of impurities contained in a semiconductor. The present invention can also be used as a simple qualitative analysis method for trace elements.
【図1】微量元素の表面平衡偏析濃度の温度依存性を示
す模式図である。FIG. 1 is a schematic diagram showing the temperature dependence of the surface equilibrium segregation concentration of a trace element.
【図2】l/温度に対するアレニウス・プロットであ
る。FIG. 2 is an Arrhenius plot versus 1 / temperature.
【図3】表面平衡偏析濃度からバルク濃度を求める検量
線である。FIG. 3 is a calibration curve for obtaining a bulk concentration from a surface equilibrium segregation concentration.
【図4】Ni中Auの表面平衡偏析濃度の温度依存性を
示す図である。FIG. 4 is a diagram showing the temperature dependence of the surface equilibrium segregation concentration of Au in Ni.
【図5】Ni中Auの表面平衡偏析濃度からバルク濃度
を求める検量線である。FIG. 5 is a calibration curve for obtaining a bulk concentration from a surface equilibrium segregation concentration of Au in Ni.
【図6】Pt中Cの表面平衡偏析濃度の温度依存性を示
す図である。FIG. 6 is a diagram showing the temperature dependence of the surface equilibrium segregation concentration of C in Pt.
【図7】Pt中Cの表面平衡偏析濃度からバルク濃度を
求める検量線である。FIG. 7 is a calibration curve for obtaining a bulk concentration from a surface equilibrium segregation concentration of C in Pt.
【図8】Co中Cの表面平衡偏析濃度の温度依存性を示
す図である。FIG. 8 is a diagram showing the temperature dependence of the surface equilibrium segregation concentration of C in Co.
【図9】Co中Cの表面平衡偏析濃度からバルク濃度を
求める検量線である。FIG. 9 is a calibration curve for obtaining a bulk concentration from a surface equilibrium segregation concentration of C in Co.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6,DB名) G01N 31/00 G01N 33/20 H01J 37/252──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 6 , DB name) G01N 31/00 G01N 33/20 H01J 37/252
Claims (3)
体を10-7Torr以下の高真空の表面分析装置内で、試料
融点(絶対温度)の1/4且つ50℃(323K)以
上、融点の4/5以下に加熱して、該金属または半導体
に微量に含有されている異種元素の表面偏析濃度を測定
し、表面での平衡偏析濃度とバルク濃度の関係から、金
属中及び半導体に含まれる微量異種元素濃度を定量する
金属、及び半導体中の微量元素分析方法。1. A metal or semiconductor whose surface has been cleaned is cleaned in a high vacuum surface analyzer at 10 −7 Torr or less, at a temperature of 4 of the sample melting point (absolute temperature) and 50 ° C. (323 K) or more. Is heated to 4/5 or less of the above, and the surface segregation concentration of the different element contained in the metal or the semiconductor in a trace amount is measured. For determining trace element concentration in trace metals and trace elements in semiconductors.
研磨し、更に融点の1/2以上、4/5以下の温度に真
空中で加熱して表面を清浄に仕上げた試料を使用する請
求項1記載の微量元素の分析方法。2. A sample whose surface is mirror-polished, chemically polished to 1 μm or more, and further heated to a temperature of not less than 1 / of the melting point and not more than 4/5 in vacuum to finish the surface cleanly. Item 7. The method for analyzing trace elements according to Item 1.
である微量元素の原子半径の比が0.9以下または1.
1以上である請求項1記載の微量元素の分析方法。3. The ratio of the atomic radii of a matrix metal and a trace element which is a heterogeneous element to be determined is 0.9 or less.
2. The method for analyzing trace elements according to claim 1, wherein the number is one or more.
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JP5094584A JP2863412B2 (en) | 1993-04-21 | 1993-04-21 | Method for analyzing trace elements in metals and semiconductors |
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JP2863412B2 true JP2863412B2 (en) | 1999-03-03 |
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