Agilent Analysis of Electroceramics Using Laser Ablation ICP-MS
Contents
1. Table 1 Laser ablation New Wave Research LUV266X Wavelength Pulse frequency Laser energy Ablation pattern Scan speed Laser warm up Laser Ablation and ICP MS Conditions 266 nm 10 Hz 2 mJ for Ferrite Raster 100 um spot diameter for Ferrite 50 um s for Ferrite 10s ICP MS Agilent 7500s RF power Carrier gas Plasma gas Integration time 100 10 4 Ss 1 E O XRF 5 E LA ICP MS 5 01 7 0 01 0 001 i il i MgO Si MnO CoO Cu NbyO5 Al 03 Cr203 Fe203 NiO Zn0 Sn09 Figure 1 Comparison of results of semiquantitative analysis using LA ICP MS and XRF analysis conducted on ferrite sample A 100 10 4 14 E C XRF S 01 H LA ICP MS 8 0 01 4 0 001 T T T T T i T T T T E T 1 1 MgO SiO MnO CoO Cu0 Nby05 Aly03 Cry03 Fe 03 NiO Zn0 Sn0 Figure 2 Comparison of results of semiquantitative analysis using LA ICP MS and XRF analysis conducted on ferrite sample B Number of masses 1200 W 1 15 L min 16 0 L min m z 2 to 260 0 05 s obtained via XRF with variations of only several percent Even for the trace components the differ ence from the reference value was within 10 The disparity among the three measurements was approximately 5 to 10 for the bulk elements and approximately 20 for the trace elements Using this analysis method it was possible to suppress the fluctuation in the sample introduction efficiency that is peculiar to LA ICP MS Table 3 shows2. methodology for the trace analysis of impurities will continue to evolve In addition environmental regulations are expected to become increasingly stringent which will impact on the need for reliable methods for the trace analysis of solids Therefore the demand for newer faster and more convenient methods of semiquantitative analysis such as the LA ICP MS technique discussed in this application note will continue to grow Using concentration conversion coefficients obtained from an aqueous standard and solid refer ence samples and by measuring all of the elements we found that LA ICP MS provides an effective tech nique for rapid semiquantitative analysis The tech nique can be applied to measurements across a wide dynamic range from bulk to trace components of materials Furthermore this method is not lim ited to electroceramics and can be applied to various other materials and substances www agilent com chem References 1 TDK Product Hotline Magazine 34 2000 2 M Oishi and K Fukuda 2003 J Mass Spectrom Soc Jpn 51 220 3 A J Campbell and M Humayun 1999 Analytical Chemistry 71 939 4 M D Norman N J Pearson A Sharma W L Griffin 1996 Geostandard Newsletter 20 247 5 J S Becker H J Dietze Fresenius J Anal Chem 365 429 1999 6 H Bratz and R Klemd Analysis of Rare Earth Elements in Geological Samples by Laser Abla tion ICP MS Agilent Technologies
3. the analysis values for all of the elements detected with the LA ICP MS measurement of ferrite sample A Table 3 A Comparison of the Principal Components and Trace Element Concentrations wt of Ferrite Sample A with the Concentrations Obtained from XRF The RSD for the LA ICP MS Indicates the RSD for the Three Measurements Elements XRF LA ICP MS Reference value Mean RSD MgO 0 27 0 26 11 0 Al 03 0 16 0 16 9 7 SiO 0 076 0 076 10 1 Cr20 0 030 0 031 4 1 MnO 0 30 0 28 0 8 Fe20 66 0 66 0 0 5 CoO Hi 0 004 3 1 NiO 13 8 13 6 2 8 Cu0 4 2 4 1 0 8 Zn0 15 1 15 5 2 3 Y 03 0 00004 18 9 ZrO 7 0 001 20 8 Nb O j 0 003 6 5 Mo0 0 004 8 6 In20 ji 0 00004 8 1 Sn0 0 004 14 7 Sb20 j 0 0002 17 0 Ba0 0 001 15 6 WO i 0 0004 4 1 Bi 03 j 0 0001 11 7 Not detectable Trace components such as V20 Y203 ZrO MoOs Sb203 BaO WOs and Biz20Os which could not be detected with XRF could be measured using the LA ICP MS Heavy elements could also be measured and have sub ppm DLs Although not included in our samples the technique offers good DLs for cadmium lead mercury and other elements which will be targeted by the RoHS directive so the pro posed method will be effective in the analysis of toxic metals The time required for analysis was 40 seconds per measurement and the total time for the three repiti tions including the time spent changing the sam ples was approximately 5 minutes Moreover no sample
4. used as a means of qualitative analysis although it is also used in quantitative analysis Typical applications include the determination of trace elements in iron 3 and the characterization of geological samples 4 5 6 At the same time however the elements involved in these analyses are trace components and few stud ies have been conducted on assays that included everything from principal to trace components Advantages of the technique include e Measurement speed There is no need to draw the sample chamber into a vacuum so sample measurements can be carried out rapidly e High sensitivity and wide dynamic range Gases and micro particles generated by laser ablation are introduced directly into the ICP MS for measurement enabling high sensitivity analy sis Moreover the ICP MS has a wide dynamic range enabling a broad spectrum of analysis ranging from principal component elements to impurity elements e Local analysis is possible The laser beam is narrow and a charged coupled device CCD camera can be attached enabling local analysis of specific subsections of the sample e Changing the analysis field The area being ana lyzed can be modified by changing the diameter of the laser beam e Analyzing a wide range of samples Almost any sample can be fused and ablated using the fourth higher harmonic 266 nm or fifth higher harmonic 213 nm of an Nd YAG laser or using an excimer laser 193 nm e Measuring
5. Analysis of Electroceramics by Laser Ablation ICP MS e Application e J e o e e ee a J o e e Semicondutor J e e Author Masahiro Oishi and Keiichi Fukuda Materials Analysis Center Technology Group TDK Corporation Japan Abstract TDK is one of the leading electronic component manufac turers supporting the advance of cell phones personal computers and car electronics As the electroceramic chip parts used in these devices become smaller thinner and lighter new analytical methodology is needed to meet the demand for faster more sensitive methods of quanti tative analysis of solid materials In addition environmen tal regulations are expected to become increasingly stringent which will impact on the need for reliable methods for the trace analysis of solids To meet these challenges researchers at TDK have developed a method based on laser ablation inductively coupled plasma mass spectrometry which offers simultaneous quantitative analysis of major and minor elements with high sensitiv ity spatial resolution of 10 pm robustness and rapid analysis The results are based on a new normalization method which can compensate for the sample introduc tion rate differences between samples or between differ ent sites The technique is applicable to the simultaneous analysis of major minor and trace elements in electroce ramics as well as other sample types in other industry sectors Introd
6. alues for all ele ments were converted to the equivalent oxide 8 Using the sum of the oxide conversion values of the detected elements standardization was per formed and the standardized semiquantitative values were determined For an example of semiquant factor calculations see Table 2 Oxide conversion was carried out at this time because electroceramics are primarily oxides Table 2 Semiquant SQ Factor Calculation Case 1 SO Factor SQ Factor of LA of nebulizer Fe 100 200 Co 1000 Ni 2000 4000 Coefficient k of Fe is 100 200 0 5 Coefficient k of Ni is 2000 4000 0 5 Coefficient k of Fe and Ni is same Co SQ factor is 1000 x 0 5 500 Case 2 SQ Factor SQ Factor of LA of nebulizer Fe 100 200 Co 1000 Ni 3000 4000 Cu 2000 Zn 4000 4000 Coefficient k of Fe is 100 200 0 5 Coefficient k of Ni is 3000 4000 0 75 Coefficient k of Zn is 4000 4000 1 0 Co SQ factor is 1000 x 0 5 0 75 2 625 Cu SQ factor is 2000 x 0 75 1 0 2 1750 Using the above method results in the following advantages e Elements not contained in the solid reference sample can be measured e Standardization processing makes it possible to correct the sample introduction efficiency between samples or for each of the measure ments thus minimizing disparities and offset from the true values Using this method of analysis we investigated the possibilities of semiquantitative analysis of an area measur
7. eas with spots compared with the results obtained using XRF analysis The calculated semiquantitative values for the normal areas of the BaTiO disk using LA ICP MS were approximately equal to the results for the disk as a whole as obtained using XRF Analysis of the black spots an area of several micrometers on the BaTiO disk indicated significant disparities in the amounts of MgO MnO and Y 0s Figure 3 illustrates the analysis of the spots compared to the normal areas of the BaTiO disk It is thought that the spots on the BaTiO disk were caused by aggregation of Figure 4 CCD image of the BaTiO disk prior to laser irradiation MgO MnO and Y20 Figures 4 and 5 show a CCD image of the BaTiO disk before and after LA ICP MS analysis and as the photographs illus trate there was very little damage to the sample with the laser diameter set at 10 um As described above our analyses indicate that the LA ICP MS method of semiquantitative analysis is effective as a means of local analysis of areas measuring several tens of micrometers in diameter Figure 5 CCD image of the BaTiO disk after laser irradiation showing minimal damage laser diameter was 10 pm Conclusions Not only are electroceramics becoming smaller and more heavily layered but the boards themselves are becoming more hybridized as capacitors and mag netic elements begin to share space on the same board To keep apace with these developments
8. ely cou pled plasma mass spectrometry ICP MS Inorganic analysis of micro portions is generally performed using an electron probe micro analyzer EPMA or an energy dispersive X ray analyzer attached to a scanning electron microscope The XRF enables convenient analysis of major ele ments and minor components XRF measurement targets include bulk particle and thin film sam ples The technique is extremely effective in char acterizing unknown samples however conducting high sensitivity analysis requires a larger measure ment diameter and is relatively slow When mea surements are required at lower LODs than is possible via XRF analysis the sample is usually dissolved using acid or fused with alkali and then dissolved and analyzed using ICP AES or ICP MS Drawbacks associated with these methods include the additional time required for sample dissolu tion the risk of sample contamination during sample preparation and the fact that local analy sis of solids is not possible In many cases microfield analysis EPMA which has an element mapping function is used However EPMA requires some sample preparation and because the sample chamber is contained within a vacuum time is required before measurements can be per formed In addition analysis cannot be performed at a sufficiently high level of sensitivity with typical detection limits DL at ppm levels Thus conventional methods of analysis have fallen short of
9. f the vari ous elements contained in the NIST glass are calcu lated ahead of time Then the actual test sample is analyzed and the semiquantitative values for the actual test sample are determined from the data obtained using the concentration conversion coef ficients However when NIST glass is used the sample introduction efficiency is different for the material being measured in many cases This increases the error in the semiquantitative values When a standard sample that is similar to the material being tested is used as the standard sample there are also problems such as the sample introduction efficiency being different depending on the location being analyzed Given these challenges with the semiquantitative analysis of electroceramics we developed a method in which the semiquantitative values are standardized in order to suppress fluctuation of the sample introduction efficiency Moreover in order to reduce the error of the semiquantitative values a solid reference sample was used that was similar to the material being measured To carry out standardization however it was necessary to measure all of the elements and determine the semiquantitative values In other words it was necessary to calculate the concentration conver sion coefficients k for all of the elements Because the solid reference sample contained only some of the components of the electroceramic it was not possible to calculate the concentration conver
10. ing several mm on a ferrite bulk sample In addition we attempted analysis of a spot ona barium titanium oxide BaTiO disk to determine whether we could apply this method of analysis to local analysis of an area measuring several tens of um Semiquantitative Analysis of Ferrite Bulk Samples Ferrite is a typical magnetic material for electroce ramics and is used for a wide range of compo nents from bulk shaped parts such as transformer coils and deflecting yoke coils to chip shaped parts such as chip beads Two types of ferrite samples with different compositions were used The sam ples were manufactured in house and measured 2 0 cm in length 1 0 cm in width and 0 5 cm in height For a solid reference sample we used a nickel copper zinc NiCuZn ferrite sample and calculated the concentration conversion coeffi cient Table 1 shows the measurement conditions used in the test A 100 um beam diameter at 2 mJ output energy and repetition rate of 10 Hz was used The measurement was carried out over the entire mass range m z 2 260 and the integra tion time for the various masses was set at 0 05 s with measurements being performed three times To compare the analysis values the same sample was analyzed using XRF The results measured using the LA ICP MS for the two types of ferrite samples are shown in Figures 1 and 2 respectively There was excellent agreement between the principal composition and the reference values
11. preparation was carried out when the mea surements were taken In our opinion this semi quantitative LA ICP MS method satisfies the requirements for electroceramics analysis in terms of speed convenience and high sensitivity Semiquantitative Analysis of Spots on a BaTiO disk Next we investigated whether the technique could be applied to feature local analysis of a dielectric material A 1 cm diameter BaTiO disk manufac tured in house was used BaTiO is a major compo nent of chip capacitors Depending on the elements added to BaTiOs the baking conditions and other parameters black spots sometimes appear on the surface during manufacture The LA ICP MS quanti tative technique described above was used to char acterize both these spots and normal areas on the BaTiO disk The following laser conditions were used in this measurement beam diameter of 10 um at 10 Hz and 0 02 mJ In addition for comparison purposes we analyzed the entire disk using XRF The results are shown in Figure 3 104 2 14 5S v h Z S 5 o4 V o 0 014 0 001 T T T if T T T MgO TiO MnO SrO Y 03 ZrO BaO HfO Figure 3 O Concentration with XRF Areas with no spots LA ICP MS Hs Spot areas LA ICP MS Y Indicates higher concentration of MgO MnO and Y 0 in the spot regions of the disk A comparison of results obtained using the LA ICP MS for semiquantitative analysis of areas of the BaTiO disk with no spots and ar
12. publication 5988 6305EN www agilent com chem icpms For More Information For more information on our products and services visit our Web site at www agilent com chem icpms For more information about semiconductor mea surement capabilities go to www agilent com chem semicon Agilent shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material Information descriptions and specifications in this publication are subject to change without notice Agilent Technologies Inc 2004 Printed in the USA April 8 2004 5989 0321EN z Agilent Technologies
13. s primarily in electrical and electronic devices and in recent years environment related regulations pertaining to electrical and electronic devices have grown increasingly stringent worldwide Two new environmental regulations that will take effect in the European Union EU in 2006 are the directive on Waste Electrical and Electronic Equipment WEEE and Restriction on the Use of Certain Haz ardous Substances RoHS The WEEE directive is associated with the disposal of waste electrical and electronic equipment while RoHS restricts the use of certain hazardous substances present in electrical and electronic equipment The proposal for the RoHS directive will prohibit the use of mer cury cadmium lead hexavalent chromium and other toxic substances from electrical and elec tronic equipment Also in Japan there are pres sures on the electronics industry to eliminate lead and to restrict the use of other toxic substances In this application note laser ablation inductively coupled plasma mass spectrometry LA ICP MS was used to analyze electroceramics A method was developed that enables rapid convenient and highly sensitive compositional analysis Further details were described in a previous report 2 Inorganic Analysis of Electroceramics The techniques generally used for the inorganic analysis of electroceramics are X ray fluorescence XRF inductively coupled plasma atomic emis sion spectroscopy ICP AES or inductiv
14. samples of various shapes Bulk par ticle thin film and other types of samples can be measured However a smoother sample field that has no bumps or projections achieves more stable results Some disadvantages include e Problems with stability The efficiency with which samples can be introduced varies for each sample so analysis values are sometimes not stable e Quantitative analysis is difficult Quantitative analysis of solutions by ICP MS is carried out using a method of calibration that uses external standards or standard addition However in the case of LA ICP MS internal standards are diffi cult to add to solid materials The internal stan dardization can be used if there are principal component elements for which the concentra tions are already known but then the method cannot be applied in all types of analysis Semiquantitative Analysis Because quantitative analysis using external stan dards is difficult via LA ICP MS generally the con centration conversion coefficient is calculated separately for each element being measured and semiquantitative analysis is performed In this case either National Institute of Science and Technology NIST 611 612 613 or 614 glass which contains multi elements or a manufactured standard that is similar to the material being tested is used for calculating the concentration conversion coefficient k If NIST glass is used the concentration conversion coefficients o
15. sion coefficients k for all of the elements In this case a concentration conversion coefficient k aqua was calculated by measuring the SPEX multi element standard solution XSTC 1 7 8 13 This value was then corrected to take account of the element being present in the solid rather than in solution to give a k aqua value The k aqua values were used as the concentration conversion coefficient k for the calculations The procedure for semiquantitative analysis of the electroceramic test sample is described below 1 Using pneumatic nebulization aqueous stan dards containing SPEX XSTC 1 7 8 13 were measured over the entire mass range m z 2 to 260 amu 2 Semiquantitative factors SF were calculated for the elements in the aqueous standard 3 Using LA ICP MS a solid standard was measured across the entire mass range m z 2 260 4 For those elements where the concentration is known semiquantitative factors SF were calculated in the solid standard 5 For those elements that occur in both the aque ous and solid standard and for which SF values were calculated the coefficient k was generated 6 The k coefficient can be used to convert SF values obtained using the aqueous standard into those useful for solid standards SF obtained by pneumatic nebulization ICP MS x coefficient k This way SF values of elements that are not in the solid standard could be generated 7 The concentration conversion v
16. the mark with regard to speed conve nience sensitivity dynamic range and microfield analysis In contrast LA ICP MS enables local analysis of solid samples while maintaining the high sensitivity of ICP MS ICP MS also offers a wide linear dynamic range For example the work ing analytical range of the Agilent 7500 ICP MS extends to nine orders with very high sensitivity In addition the detection circuit used in the 7500 Series ICP MS means acquisition speed is not com promised when analyzing higher concentration ele ments and ensures that transient signals from a laser ablation pulse can be measured over such a wide dynamic range This is a key advantage in the determination of trace and major elements in inclusions where the analyte signal is very short lived and analyte concentrations vary widely This report summarizes investigations into the possibility of applying a new LA ICP MS method to compositional and impurities analysis of electroceramics Analysis Using Laser Ablation ICP MS Evaluation of LA ICP MS LA ICP MS is widely used to determine inorganic elements in solid samples A laser is used to irradi ate the solid sample and to generate microparticles The particles are carried on a steady gas stream to the ICP MS where the sample is ionized and mea sured Thus solid samples can be analyzed directly without preprocessing and element analysis can be performed at a high level of sensitivity LA ICP MS is often
17. uction All ceramics including electroceramics can be defined as polycrystalline nonmetallic materials By using precisely controlled compositions and additives their unique electrical dielectric piezo electric optical and magnetic properties can be optimized for use in many key technologies such as communications electronics and automation For example dielectric materials are used in chip capacitors whereas magnetic materials are used in transformer coils using ferrite chip beads and other components Currently there is a drive to make electroceramics lighter and more compact and to achieve thinner packages higher compositeness and lower levels of power consumption 1 For instance ceramic capacitors are one form of electroceramics that are in high demand They were initially comprised of a single layer but with developments in multi layering and chip technology larger capacity and more compact capacitors are now widely used The ability to make multilayer ceramic chip capacitors smaller lighter and thinner has contributed greatly to the propagation of mobile devices such as cellular telephones As these materials continue to become smaller and thinner there is an increased need to conduct composition analysis at lower limits of detection LOD Furthermore the need for fast high sensitivity analysis is not restricted to the production and processing industry Electroceramics are used A j Agilent Technologie
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Agilent Analysis of Electroceramics Using Laser Ablation ICP MS