Theoretical Calculations For Sputtering Yield of Iron Bombarding by (H, D, T, He) Ions Enas A . Jawad Mustafa K. Jassim Huda M . Tawfeek Dept. of Physics /College of Education For Pure Sciences (Ibn Al-Haitham )/ University of Baghdad Received in : 20 March 2014 , Accepted in : 8 July 2014 Abstract Extended calculations for sputtering yield through bombed Iron – target by ( H,D ,T ,He ) ions plasma are accomplished .The calculations include changing the input parameters : the energy of ( H,D ,T ,He ) ions plasma, the hit target angle of Iron, change atomic mass of incident ion. The program TRIM is used to accomplish these calculations. The results show that sputtering yield is directly dependent on these parameters. It can change the incident angle of ( H,D ,T ,He ) ions and energy lead to a significant change in sputtering yield on the other hand. The sputtering yields are highly affected by changing of incident ion mass at fixed other target parameters. It can be shown from calculation that whenever increased incident ion mass increase sputtering yield, increases with incident ions energy and then begins to decline, sputtering will not occur , at incident ion energies below the threshold energy . In this study we found that the sputtering yield depends on incidence angle, incident ions energy and atomic mass of target. Key words: sputtering process, TRIM program, Hydrogen ions, Deuterium ions, Tritium ions, Helium ions, iron 144 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 Introduction Sputtering is a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic particles .Several possible processes may occur in a solid target material whose surface is bombarded by energetic particles. The colliding energetic particles may be single atoms, ions, or molecules, but the outcome of the collision is determined mostly by the kinetic energy of the incident particle [1,2]. Sputtering begins when an energetic particle strikes a target surface atom. This particle is predominantly called the incident, primary, or projectile particle. The energetic incident particle loses energy to the target through two mechanisms[3] : elastic nuclear collisions ( kinetic energy conserved , atom-on-atom “ billiard ” ball collisions ), and inelastic electronic loses ( electronic excitation , ionization and electron-electron collisions) . Sputtering processes are classified into three qualitative regimes. These regimes are distinguished by the behavior of the displaced atoms, which is a function of the energy transferred to them. Lattice atoms that are displaced by the ion are called primary knock-on atoms or PKAs [4].The PKAs can displace other atoms from the lattice creating secondary Knock - on atoms , tertiary knock - on atoms , and higher order knock-on atoms . Sigmund has identified three sputtering regimes that can be classified by the incident ion energy . 1.The single knock-on regime 2. The linear cascade regime 3. The spike regime in the single knock-on regime, collision cascades are not created. They are created by undergoing a collision with the primary particle and having a very small number of collisions which direct it toward the surface[5]. Sputtering occurs as the result of a series of elastic collisions within a collision cascade region. Of the simulation program which employs Sputtering process is a TRIM program. The name comes TRIM Program from the first letters of the phrase "Transport of Ion in Matter ", it is the most comprehensive, and included in the general program labeled SRIM. TRIM program is a Monte Carlo simulation method [6]. TRIM uses Monte - Carlo calculations to make detailed calculations of the energy transferred to every target atom collision . Incident ions and recoils are tracked through their slowing down process until their energy falls below a predetermined energy or they are so far from the surface that they are no longer candidates for sputtering [7,8]. In this research we use TRIM program to calculate the sputtering yield of Fe by ( H, D ,T , He ) ions ,when we change the most important input parameters in the sputtering process , such as kinetic energy of bombarding ions and incidence angle, also change the incident ion parameters such as mass. Theory Sputtering is quantified by the sputtering yield, Y, the mean number of atoms removed per incident particle, as stated in Eq. (1). A bombarding particle must have a kinetic energy above the sputtering threshold, Eth, is defined as the minimum kinetic energy of the bombarding particle for sputtering to occur [3]. (1) http://en.wikipedia.org/wiki/Atom http://en.wikipedia.org/wiki/Ejected http://en.wikipedia.org/wiki/Particle http://en.wikipedia.org/wiki/Monte_Carlo_method If the bombarding particle transfers kinetic energy greater than the lattice displacement energy, Ud, of the target atoms, surface damage takes place. The lattice displacement energy is the energy a target atom needs to move more than one atomic spacing away from its original lattice position [7]. The sputtering yield is dependent on properties of both the incident particle and the target as follows [9]: • Incident Particle Properties - energy. - mass. - incidence angle. • Target Properties - atomic mass. - surface binding energy. - surface texture . - crystal orientation. The definition sputtering yield is assumed that the number of atoms removed proportional with the number of incident particles while all the other factors remains constant and where the target a solid material, the package ions bombard energy E0 and incident angle θ0 , it leads to a series of elastic collisions when neglecting electronic excitation of the target [10]. the atom of target atoms will make movement recoil , after gaining energy of the collision process and can cause recoil movement of other atoms , which can be expressed as a sputtering yield [10]. (2) As that Λ is factor associated with target material, associated only with advantages target, such as the surface binding energy. Expression of equation FD(0,E0,θ0)is in numerical calculations [10]. (3) where α is the correction factor , which is a function of the mass ratio between bombarding target mass to the mass of the particle projectile M 2 / M1 , and N is atomic volume (atoms / volume), and θ0 is initial angle of incidence, and Sn(E0) is a nuclear stopping power, so it can be described sputtering yield [10]. (4) As ƞ is a generic parameter of energy. In order to accurately calculate the sputtering yield, it can be used for nuclear stopping cross-section, a given Sn(E0) equation [10]. (5) As the Z1 , Z2 their atomic numbers for each of the incident particle and material target is bombard respectively, and that ε its reduced energy , which is given by equation [10]. (6) The energy unit of the ion incident E is keV, and Sn(E0) limit the decline in the nuclear cross section. Pack of ions energy ε ≤ 30 it is described by equation [10]. 146 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 (7) Results and Discussion 1. Sputtering yield dependence on incidence angle. Figure (1) shows the relationship between sputtering yield and incidence angle for fixed width target 1000 Ao , and number of ions 5000, from light incidence ions ( H,D ,T ,He ) to a target of iron, at energy of incident ions is 0. 5 keV. The sputtering yield depends on the angle of incidence, measured from the surface normal. The sputter yield increases with the increase of angle of incidence (as the collision cascade moves closer to the surface) , reaches a maximum (typically between 55° and 80°, depending on the projectile target system), and decreases for glancing angles of incidence due to the increase of the particle reflection coefficient and the fitting process are subject to the following relationship from ( H,D ,T ,He ) respectively: y = p1z6 + p2z5 + p3z4 + p4z3 + p5z2 + p6z + p7 (8) As shown that p1 , p2,… … p6 are constants vary from one curve to another, the table (1) gives the values of these constants according to the different incident ions ( H,D ,T ,He ) angle (00 - 890 ) . Show in figure (1) a maximum sputtering yield for ( H, D ,T , He ) incident ions angle from a target of iron in 75o incident ion angle. Sputtering yield dependence on mass of incident ion. We notice from the figure (1) that the sputtering yield increases with the increase of mass incident ion. We observe that the sputtering yield (0.357 Atom/Ion in incident angle 75o)is the largest from Helium which has the biggest mass of incident ion, and less sputtering yield (0.012 Atom /Ion in incident angle 75o)from Hydrogen which is less than a mass of incident ion , the sputtering yield from Deuterium ions is 0.1 Atom / Ion in incident angle 75o, from Tritium ions is 0.175 Atom /Ion. between the four ions , we observe whenever increased incident ion mass increase sputtering yield. Effect of incident ions energy in sputtering yield : Sputtering will not occur , at incident ion energies below the threshold energy . The sputter yield exhibits a threshold below which the amount of energy transferred to the target atoms is too small for them to overcome the surface barrier. with the increase of energy of the projectiles the sputter yield increases, reaches an maximum and decreases again. This decrease at higher energies is caused by the increasing depth of the collision cascade, moving away from the surface. Whereas the collision kinetics is governed by the mass ratio of target atom mass to projectile mass , each element has its specific surface binding energy. Figure (2) shows the relationship between sputtering yield and hydrogen ion energy from iron target using the equation (7), figures (3 ,4 and 5 ) from (H, D ,He) ion respectively , sputtering yield increases with incident ions energy and then begins to decline ,the reason for this is attributable to the incident ions of high energy because it does not happen sputtering , but implemented ions from the target. sputtering will not occur , at incident ion energies below the threshold energy[11] , illustrates the comparison from four light ion using the equation(7) , in figure (6). Figures (7,8,9) show the relationship between sputtering yield and ion energy from (H, D, He) respectively using the calculator [12 ]. figures (10,11,12) show the relationship between sputtering yield and (H, T, He) ion energy respectively using the equation (9) [ 13 ]. 147 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 f (E) = k *exp(-β/(E-Eth) - ɤ *(log(E/Emax)2)) (9) As that k, β, Eth , ɤ , Emax are constants vary from one curve to another, the table (2) gives the values of these constants according to the different incident ions ( H,T ,He ) angle (00 - 890 ) . in all previous figure a maximum sputtering yield for ( H,D ,T ,He ) ions incident energy from a target of iron in 1000 eV. Conclusions The calculations are carried using simulation program TRIM , to study sputtering yield of iron target , when the bombarding ion ( H,D ,T ,He ) to change input parameters to pack incident ions as well as to see how the effect of outputs sputtering yield , in this study we found that the best angles for these incident ions when close to the angle 800 , sputtering yield increases with increase of mass incident ion , sputtering yield increases with incident ions energy and then begins to decline ,we found in this study that sputtering yield depends on incidence angle , incident ions energy, mass of incident ion . A maximum sputtering yield for ( H, D ,T , He ) incident ions angle from a target of iron in 75o incident ion angle. And for ( H,D ,T ,He ) ions incident energy from a target of iron in 1000 eV. Reference 1. Sigmund , P. (1969) Theory of sputtering . I. Sputtering yield of amorphous and polycrystalline target", physical review, (148), (2), 383 – 416. 2. Leon, I. Maissel and Reinhard Glang,(1970). Handbook of Thin FilmTechnology. New York ,McGraw-Hill Book Company. 3. Kirk, A. Zoerb,( 2007), Differential Sputtering yield of refractory metals by ion bombardment at normal and oblique incidences ,Colorado State University . 4. Michael Nastasi, James W. Mayer, and James K. Hirvonen. (1996) Ion-Solid Interactions: Fundamentals and Applications", Cambridge University Press, Cambridge Solid State Science Series. 5 .Betz, G. and Wien, K. ( 1994), Energy and Angular Distributions of Sputtered Particles, International Journal of Mass Spectrometry and Ion Processes, 140, 3, 1-110. 6. Ziegler ,J . F.; Biersack J. P. and Ziegler , (2012) SRIM: The Stopping and Range of Ions in Matter, Chester, Md. : SRIM Co. [2012], ©2008. 7. Ziegler .J.F and SRIM (2003), (Program and Documentation). http:/ /www.srim.org. 8. Biersack .J.P. and Eckstein .W.,( 1984) Sputtering studies with Monte Carlo program TRIM.SP". Journal of Applied Physics ,120, 34,73–94, 9. Behrisch, R. ( 1981),“Introduction and Overview ,Sputtering by Particle Bombardment I, ed. Behrisch, R., Springer-Verlag, Berlin,97,20, 1-8, 10. Guping ,D.; Tingwen ,X. and Yun, L . (2012) , Preferential sputtering of Ar processing SiO2 mirror, The 6th SPIE International symposium on ion advanced optical manufacturing and testing technologies ,Volume 8416 11. MatsuAnmi ,N.; Yamamura ,Y.and Itikawa ,Y. (1983) Energy Dependence of Sputtering Yield of Monatomic Solid ",Institute of plasma physic , Nagay university ,Japan. 12. Matsunami ,N. ;Yamamura,Y.; Itikawa ,Y.; Itoh ,N.; Kazumata ,Y.; Miyagawa, S.; Morita .K.; Shimizu ,R. and Tawara ,H. (2007) Calculator Based on empirical equations for sputter yields at normal incidence, in Energy Dependence of the Sputtering Yields IAP/TU Wien Surface Physics Group 13. IGOR Pro, Copyright 2007 Wave Metrics, Inc.http://www.wavemetrics.com/. 148 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 http://proceedings.spiedigitallibrary.org/volume.aspx?conferenceid=2891&volumeid=14860 http://www.iap.tuwien.ac.at/www/index http://www.tuwien.ac.at/ http://www.iap.tuwien.ac.at/www/surface/index Table No. (1): Constants fitting equation (8) Plotted in Figure (2) from Light incidence ions (H, D, T, He) from target of iron Table No. (2): Constants fitting equation (9) Plotted in Figure (10,11,12) from Light incidence ions (H, T, He) from target of iron ion P1 P2 P3 P4 P5 P6 P7 H 0.0013194 -0.00036 -0.003946 -0.001372 0.000194 0.003247 0.016444 D 0.012484 -0.00907 -0.052439 0.010669 0.051213 0.017962 0.067294 T -0.007421 -0.00374 0.0048303 -0.021024 0.012207 0.065199 0.12223 He -0.013084 -0.03480 0.0013172 0.034915 0.0245 0.067529 0.2769 ion k β Eth ɤ Emax H 0.059979 487.74 145.37 0.35826 75 T 0.18632 260.84 24.678 0.4394 160 He 0.42886 300.22 1.9516 0.59477 650 149 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 Figure No.(1): Relationship between sputtering yield and incidence angle from Light incidence ions (H, D, T, He) from target of iron Figure No.(2): Relationship between sputtering yield and hydrogen ion energy from iron target . 150 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 Figure No. (3): Relationship between sputtering yield and Deuterium ion energy from iron target 151 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 Figure No. (4) :Relationship between sputtering yield and Tritium ion energy from iron target Figure No (5): Relationship between sputtering yield and Helium ion energy from iron target. 152 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 Figure No. (6): Illustrates the comparison from four light ion . Figure No. (7): relationship between sputtering yield and hydrogen ion energy from iron target 153 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 Figure No. (8): relationship between sputtering yield and Deuterium ion energy from iron target Figure No (9): Relationship between sputtering yield and Helium ion energy from iron target 154 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 Figure No. (10): Relationship between sputtering yield and hydrogen ion energy from iron target Figure No. (11): Relationship between sputtering yield and Tritium ion energy from iron target 155 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 Figure No. (12): Relationship between sputtering yield and Helium ion energy from iron target 156 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014 طة حزمة من احسابات نظریة لحاصل ترذیذ (الرش) سطح من الحدید بواس الدیوتیریوم و التریتیوم والھلیوم ایونات الھیدروجین و ایناس احمد جواد مصطفى كامل جاسم ھدى مجید توفیق جامعة بغداد )/ابن الھیثم ( كلیة التربیة للعلوم الصرفة /قسم الفیزیاء 2014تموز 8، قبل البحث في : 2014اذار 20استلم البحث في : الخالصة الھیدروجین و بالزما ایونات طة قصفارذیذ(الرش) لھدف من الحدید بواسلقد أنجزت حسابات لعملیة الت مل الحسابات على تغییر معلمات اإلدخال لكل من طاقة ایونات الھیدروجین تش. ت الدیوتیریوم و التریتیوم والھلیوم حاصل في.وزاویة سقوطھا على ھدف من الحدید ، و كتلة االیونات وتأثیرھا الدیوتیریوم و التریتیوم والھلیوم و على اٌ مباشر اٌ ین النتائج إن حاصل الترذیذ یعتمد اعتمادتب النجاز الحسابات. TRIMف برنامج وظّ الترذیذ . لقد تؤدي إلى تغیر محسوس في نتائج حاصل الترذیذ . ونات البالزما وطاقتھاسقوط ای ر زاویةن تغیإإذ ھذه المعلمات یتأثر حاصل الترذیذ بشدة عن طریق تغییر كتلة االیون الساقط بثبوت وكتلة االیون لھ تأثیر مباشر في حاصل الترذیذ. یذ . الزیادة معلمات الھدف االخرى . تظھر من الحسابات التي اجریناھا انھ كلما زادت كتلة االیون الساقط زاد حاصل الترذ في طاقة االیون الساقط تبدا باالنخفاض . الترذیذ الیحدث عندما تكون طاقة االیون الساقط اقل من طاقة العتبة. في ھذه الدراسة وجدنا أن حاصل الترذیذ یعتمد على زاویة السقوط ، طاقة االیون الساقط و الكتلة الذریة لمادة الھدف. . ، الحدید الھلیوم ،التریتیوم ،الدیوتیریوم ،ایونات الھیدروجین ، TRIM برنامجرذیذ ،: حاصل الت الكلمات المفتاحیة 157 | Physics @a@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ÚÓ‘Ój�n€a@Î@Úœäñ€a@‚Ï‹»‹€@·rÓ:a@Âig@Ú‹©@Ü‹127@@ÖÜ»€a@I2@‚b«@H2014 Ibn Al-Haitham Jour. for Pure & Appl. Sci. Vol. 27 (2) 2014