Systems and methods for XRF detection

Abstract

The invention provides an XRF detection system and a corresponding method. The systems and methods relate to the detection of a sample. The system comprises: at least one X-ray radiation source providing X-ray radiation of a selected energy spectrum; an optical arrangement for focusing the X-ray radiation onto a selected inspection point of the sample; and at least one detector configured to detect radiation emitted from the sample and provide output data indicative of an emission spectrum from the sample; wherein the output data comprises data indicative of an L-line excitation fluorescence response of the sample.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to systems and methods for sample detection using X-ray fluorescence, and in particular to techniques for evaluating the composition of solder bumps in electrical circuits. BACKGROUND

[0002] Typical electronic circuits and circuit boards include various arrangements of connection points. In certain circuit boards, such connection points include solder bumps that are often utilized with Ag / Sn (silver-tin) material combinations. X-ray fluorescence (XRF) bump detection is a non-destructive testing technique that is primarily used in the electronics manufacturing industry to evaluate the quality and composition of solder bumps on circuit boards. The technique employs XRF technology to analyze the elemental composition of solder bumps, which is critical for forming reliable electrical connections in devices such as smartphones and computers.

[0003] During detection, an X-ray source directs X-rays at a selected location of a sample, often at a solder bump. Interaction of the X-ray radiation with the elements in the bump causes fluorescence, emitting secondary X-ray features of the specific elements present in the sample region. By measuring the intensity and energy of the emitted X-ray radiation, the XRF system can determine the composition and thickness of the material in each bump.

[0004] Typically, conventional XRF techniques utilize K-line excitation and detection of fluorescence to detect Ag / Sn bumps. The technique typically operates with excitation X-rays having an energy of about 50 keV for detection of fluorescence emissions having an energy of about 25 keV.

[0005] X-ray Fluorescence Analytical Background: X-Ray Fluorescence Phenomenon. (http: / / cais.uga.edu / wp-content / uploads / 2019 / 01 / XRF_Background.pdf) provides an overview of the basic principles behind XRF spectroscopy.

[0006] Imashuku, S. et al "Improvement of total reflection X-ray fluorescence spectrometer sensitivity by flowing nitrogen gas", Spectrochimia Acta Part B: Atomic Spectroscopy, volume 73, 75-78 (2012): Total reflection X-ray fluorescence (TXRF) has achieved remarkable success with simultaneous multi-element analysis capability, reduced background noise, no matrix effect, wide dynamic range, ease of operation, and trace analysis potential. Dynamic environmental monitoring and management urgently require simultaneous quantitative online analysis of trace heavy metals, and TXRF has potential in this field of application. However, it requires TXRF-based online analysis schemes and robust and fast quantitative methods, which have not been well explored. In addition, spectral overlap and background effects can lead to loss of accuracy or even false results during actual quantitative TXRF analysis. In this paper, an intelligent, multi-element quantitative method is proposed based on an established online TXRF analysis platform. In the intelligent quantitative method, all existing element-specific curves and a pre-estimated background curve in the entire spectral range are used to approximate the measured spectrum. A new hybrid algorithm, PSO-RBFN-SA, is designed to solve the curve fitting problem, which utilizes offline global optimization and fast online calculation. Experimental results confirm that simultaneous quantification of trace heavy metals including Cr, Mn, Fe, Co, Ni, Cu, and Zn is achieved on the online TXRF analysis platform, and both high measurement accuracy and computational efficiency are obtained.

[0007] Menzel, M. et al, "Total reflection x-ray fluorescence analysis of airborne silver nanoparticles from fabrics" Analytical Chemistry volume 86, 3053-3059 (2014): Silver nanoparticles (NPs) are commonly applied to consumer products due to their antimicrobial properties, which are desirable in the fabrics of sportswear as well as in cloths used for cleaning. When airborne Ag NPs are inhaled, these NPs can pose a hazard to human health. NPs are comparable in size to macromolecules and viruses and are able to penetrate deeply into the lung (e.g., alveoli), where, due to their large surface area, they can cause damage to cells and tissues. In this study, aerosols released from fabrics treated with Ag NPs were collected using a low-pressure Berner impactor and analyzed with total reflection X-ray fluorescence (TXRF). It was found that Ag NPs were released mainly in the form of larger particles, mainly 0.13 pm to 2 pm, possibly attached to the fibrous material. Using electron microprobe, individual particles could be identified. The detection of backscattered electrons indicated small dots on the particles composed of a heavier element, most likely Ag, although the signal in energy dispersive X-ray spectroscopy (EDX) was below the limit of detection (LOD). To achieve the LOD necessary for Ag determination, the Ar peak was eliminated by a nitrogen atmosphere provided by a "Picofox cartridge." This enabled linear calibration and quantification of Ag. The LOD was calculated to be 0.2 ng (2.0 ppb). After TXRF and scanning electron microscope (SEM) / EDX analysis, the aerosol samples were dissolved in nitric acid and analyzed with ICPMS to successfully confirm the results obtained by TXRF measurements. SUMMARY

[0008] Conventional XRF techniques generally utilize the detection and analysis of K lines for material analysis of Ag / Sn bumps in electronic circuit boards. The excitation energy required to induce K-line fluorescence emission of these elements is relatively high and can generally be associated with the maximum energy of the X-ray source used. Additionally, the use of such high energies of about 50 keV to detect the sample can result in the excitation beam penetrating the underlying layers or substrate of the sample, providing output data indicative of the materials of the detection system. Additionally, multiple photons emitted from the underlying layers of the sample can reach the detector. Additionally, the use of high-energy X-rays can result in Compton scattering of energies corresponding to the K lines of the elements being examined.

[0009] More specifically, in XRF measurements, an X-ray beam is used to excite a sample to be analyzed. As described above, this excitation causes the sample to emit characteristic X-ray radiation of different energies corresponding to the elements present in the sample. When the sample contains elements from sulfur (S, Z = 16) and above in the periodic table, the X-ray excitation can either excite an electron from the inner shell, providing K-line excitation, or from the second innermost shell, providing L-line excitation. Thus, K-lines have higher energies than L-lines because the energy required to excite an electron from the inner shell is greater than the energy required to excite an electron from the outer shell.

[0010] Furthermore, to optimally excite an element, the X-ray beam needs to have an energy that is approximately twice the characteristic fluorescence energy. For example, to excite the K-line of tin (Sn) with a characteristic emission energy of 25.196 keV, the excitation X-ray beam typically needs to have an energy of about 50 keV. Similarly, to excite the K-line of silver (Ag) with a characteristic emission energy of 22.106 keV, the excitation X-ray beam typically needs to have an energy of about 44 keV.

[0011] Accordingly, the present disclosure provides a detection system and a detection method for detecting a sample. The techniques of the present disclosure are generally applicable to detecting a sample having one or more solder bumps, which are typically used in electronic circuit boards to solder various components to the board. Such solder bumps typically include silver (Ag) and tin (Sn). Detection of the solder bumps can be used to determine the thickness of the bumps and their material composition, thereby allowing for detection of mismatches between the circuit design and its actual structure, as well as identification of manufacturing defects.

[0012] The system generally includes at least one X-ray radiation source (X-ray tube) providing X-ray radiation of a selected energy spectrum, an optical arrangement for focusing the X-ray radiation onto a selected detection point of the sample, and at least one detector configured for detecting radiation emitted from the sample and providing output data indicative of the emission spectrum from the sample. In accordance with the present disclosure, the output data includes data indicative of the L-line excitation fluorescence response of the sample. For example, for Sn, the L-alpha line is 3.444 keV, and for Ag, the L-alpha line is 2.984 keV.

[0013] Typical X-ray sources used in detection systems operate at voltages up to 50 KV. Typically, to provide K-line excitation of Ag / Sn bumps, these X-ray sources are typically operated at their maximum energy output. One advantage of the techniques of the present disclosure relates to the ability to operate the X-ray source at lower energies for excitation of the L-lines. This makes the L-lines more suitable for analysis under standard XRF operating conditions, thereby ensuring better excitation. More specifically, energies of about 6.888 KV and 5.968 KV are required to excite the L-alpha lines of Sn and Ag, respectively, as described above.

[0014] Generally, it is possible to analyze heavy elements using the L lines, and can allow for optimal excitation of the elements at relatively low voltages. However, simple detection with these energy lines can result in inaccurate detection due to the potential for overlap with characteristic lines of other elements. For example, the L a line of silver (Ag) is at an energy of 2.984 keV, which is generally overlapped with the K a line of argon (Ar) at 2.957 keV. Since argon naturally exists in atmospheric air, detecting a sample under atmospheric conditions can affect the resulting spectrum at these energies.

[0015] Accordingly, the present disclosure also provides for replacing the atmospheric gas composition of the present application with a selected inert gas composition. The selected inert gas composition is used to eliminate ordinary air, and generally to eliminate argon gas, from affecting the detection results. To this end, the system can include an inert gas source, such as a gas tank and / or a pump, configured to flow the selected inert gas composition to the area in which the sample is located during detection. The selected inert gas composition includes one or more materials having energy levels that are not aligned with the L line peaks of the material to be detected, thereby avoiding interference with the detection process. More specifically, in the detection of Ag / Sn bumps having the L line energies detailed above, the selected inert gas composition can include molecular nitrogen (N2) and / or helium (He), which are chemically inert and have energy levels far from the L line energy levels of Ag and Sn. For example, N2 has a characteristic energy line at 0.392 keV, which is sufficiently distanced from the L a lines of Ag and Sn.

[0016] Generally, the selected gas composition is also selected to avoid any interaction with the materials present on the wafer or the structural materials of the machine. Additionally, the selected inert gas composition is selected to not require specific detectors other than the detector used to probe the L line excitation. For example, the detection system can include one or more (e.g., four) silicon drift detectors, SDDs.

[0017] In some embodiments, the detection system can operate within an enclosed housing. Prior to and during the detection operation, the system can provide the selected inert gas composition into the housing, thereby providing an overpressure condition. This provides for eliminating or at least significantly reducing any interfering materials, such as Ar gas, from the housing.

[0018] Accordingly, the present disclosure provides for the following embodiments, according to some embodiments:

[0019] Embodiment 1: An XRF inspection system for inspecting a sample, the system comprising: at least one X-ray radiation source providing X-ray radiation of a selected energy spectrum; an optical arrangement for focusing the X-ray radiation onto a selected inspection point of the sample; and at least one detector configured for detecting radiation emitted from the sample and providing output data indicative of an emission spectrum from the sample; wherein the output data comprises data indicative of an L-line excitation fluorescence response of the sample.

[0020] Embodiment 2: The XRF inspection system of embodiment 1, further comprising an inert gas source configured for flowing the selected inert gas composition in a radiation path between the at least one X-ray source, the sample, and the at least one detector, thereby eliminating interference associated with components of an excitation atmospheric composition.

[0021] Embodiment 3: The XRF inspection system of embodiment 2, further comprising a housing, wherein the inert gas source is configured to provide overpressure inert gas, thereby eliminating an atmospheric gas composition within the housing. In some examples, the inert gas is directed to eliminate interaction of argon or other gases with the X-ray beam in the system.

[0022] Embodiment 4: The XRF inspection system of embodiment 2 or 3, wherein the selected inert gas composition is selected to avoid interaction of atmospheric conditions with the X-ray radiation provided by the at least one X-ray source.

[0023] Embodiment 5: The XRF inspection system of any one of embodiments 2 to 4, wherein the selected inert gas composition consists of nitrogen (N2) and / or helium (He).

[0024] Embodiment 6: The XRF inspection system of any one of embodiments 1 to 5, wherein the at least one X-ray source is a polychromatic X-ray source providing a selected radiation energy spectrum.

[0025] Embodiment 7: The XRF inspection system of any one of embodiments 1 to 6, wherein the optical arrangement comprises a multi-capillary arrangement for focusing the X-ray radiation from the at least one X-ray source onto an illumination spot having a diameter in a range between 1 micrometer and 100 micrometers.

[0026] Embodiment 8: The XRF inspection system of any one of embodiments 1 to 7, wherein the optical arrangement comprises a Fresnel lens arrangement for focusing the X-ray radiation from the at least one X-ray source onto an illumination spot having a diameter in a range between 1 micrometer and 100 micrometers.

[0027] Example 9: The XRF detection system of any one of Examples 1-8, wherein the output data includes data indicative of sample fluorescent emissions in a range of energies between 0.054 KeV and 8 keV.

[0028] Example 10: The XRF detection system of any one of Examples 1-9, wherein the output data includes data indicative of sample fluorescent emissions in a range of energies between 2.5 keV and 3.2 keV.

[0029] Example 11: The XRF detection system of any one of Examples 1-10, further comprising a sample stage adapted to hold a sample and to selectively translate the sample, thereby enabling scanning of the sample for detection.

[0030] Example 12: A method for detecting solder bumps in a sample, the method comprising: directing at least one X-ray beam onto at least one illumination point on the sample; collecting fluorescent X-ray emissions from the sample and generating fluorescent emission data indicative of a level and energy range of fluorescent emissions; processing the fluorescent emission data and determining data regarding material content within one or more solder bumps from an emission peak indicative of L-line excitation of material in the sample.

[0031] Example 13: The method of Example 12, further comprising providing a selected inert gas composition onto the sample during detection, thereby reducing X-ray emissions from one or more components of an atmospheric composition in the fluorescent emission data.

[0032] Example 14: The method of Example 13, comprising detecting a sample within a housing and providing a selected inert gas composition under pressurized conditions within the housing, thereby eliminating an atmospheric gas composition within the housing.

[0033] Example 15: The method of Example 13 or 14, wherein the selected inert gas composition is selected to avoid interaction of a gaseous atmospheric condition with X-ray radiation provided by the at least one X-ray source.

[0034] Example 16: The method of any one of Examples 13-15, wherein the selected inert gas composition consists of nitrogen (N2) and / or helium (He).

[0035] Example 17: The method of any one of Examples 12-16, wherein directing at least one X-ray beam comprises directing a polychromatic X-ray beam having a selected radiation energy spectrum.

[0036] Example 18: The method of any one of Examples 12-17, wherein directing the at least one X-ray beam comprises directing the at least one X-ray beam through an optical arrangement comprising a multi-capillary arrangement and focusing the at least one X-ray beam onto an illumination spot having a diameter in a range between 1 micrometer and 100 micrometers.

[0037] Example 19: The method of any one of Examples 12-18, wherein the fluorescence emission data comprises data indicative of sample fluorescence emission having an energy in a range between 0.054 keV and 8 keV.

[0038] Example 20: The method of any one of Examples 12-19, wherein the fluorescence emission data comprises data indicative of sample fluorescence emission having an energy in a range between 2.5 keV and 3.2 keV.

[0039] Example 21: The method of any one of Examples 12-20, further comprising providing a sample on a sample stage adapted to hold the sample and selectively translating the sample, thereby scanning at least one region of the sample. BRIEF DESCRIPTION OF DRAWINGS

[0040] For a better understanding of the subject matter disclosed herein and to show how the same can be carried into practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings in which:

[0041] Figure 1 A detection system according to some embodiments of the present disclosure is schematically illustrated;

[0042] Figure 2 Energy states of an atom are exemplified and K and L excitation lines are illustrated;

[0043] Figure 3 Fluorescence response spectra of a material under atmospheric conditions and under N2 conditions are shown; and

[0044] Figure 4 A method for detecting a sample according to some embodiments of the present disclosure is exemplified. DETAILED DESCRIPTION

[0045] Reference is made to Figure 1 which schematically illustrates a system 100 for detecting a sample 50. The system 100 comprises at least one X-ray source 110; an optical arrangement 120 (e.g., a multi-capillary arrangement) configured for focusing an X-ray beam from the at least one X-ray source 110 onto a selected illumination spot on the sample 50; and one or more detectors 130, exemplified by detector 130a and detector 130b.

[0046] Typically, the system 100 can also include a sample mount 140 (e.g., a stepper) configured for mounting a sample 50 and translating the sample in at least two dimensions to enable scanning of the sample to detect different locations on the sample 50.

[0047] In some embodiments, the detection system 100 can include an enclosed housing 160. Additionally, in some embodiments, the detection system includes an inert gas purge arrangement 150 configured for flowing a selected inert gas composition PG into the housing. Two inert gas sources are illustrated as 150a and 150b. The selected inert gas composition is selected to purge atmospheric gases to eliminate interference of one or more atmospheric gases due to interaction with X-ray radiation at energy levels proximate to one or more energies associated with detecting the sample.

[0048] The techniques and systems of the present disclosure can relate to detection of one or more solder connections within an electrical or electronic circuit board. Typically, such solder connections can be formed from silver-tin (Ag / Sn solder). The systems of the present disclosure utilize X-ray excitation of one or more regions of a sample 50 with an X-ray beam IR, collection of a fluorescent response from the detected locations, and analysis of the collected fluorescent response FR energy spectrum to determine material composition and structural parameters of the detected regions. In accordance with the present disclosure, analysis of the fluorescent spectrum for probing and quantifying Ag / Sn solder regions utilizes a spectral range associated with L-line excitation of the material.

[0049] Figure 2 Energy levels of atoms are generally illustrated and K-line excitation and L-line excitation and corresponding fluorescent responses are illustrated. When the innermost shell (K excitation) or the second innermost shell (L excitation) electrons of a material in a sample are absorbed, the X-ray beam excites the material in the sample and causes the electrons to be released, leaving a vacancy. In the fluorescent response, electrons from higher energy states relax into the vacancy, releasing a photon of the corresponding energy difference.

[0050] As noted above, the energy required for K excitation of silver (Ag) is about 44 keV and the energy required for K excitation of tin (Sn) is about 50 keV. These energies are typically at the higher end of the spectrum for a typical X-ray tube used for detection. Alternatively, L excitation of tin (Sn) requires an energy of 6.888 keV and L excitation of silver (Ag) requires an energy of 5.968 keV. These lower energies are more readily achievable, eliminating interference associated with Compton scattering. Additionally, lower energy X-ray beams in the 5 keV to 7 keV range can be characterized by lower rates of penetration, enabling detection of Ag / Sn bumps while reducing contributions of background and the material matrix below the detection region.

[0051] The use of L excitation for the detection of Ag / Sn bumps can enable detection at reduced X-ray energies and has various advantages compared to K excitation based detection. However, the fluorescence data can include emissions from additional elements in these energy ranges. More specifically, the K a line of argon gas (Ar) is at 2.957 keV. Since argon gas is naturally present in atmospheric air, detecting a sample under atmospheric conditions can affect the resulting spectrum at these energies. Figure 3 (Imashuku, et al. Spectrochim Acta Part B At Spectrosc 73, 75-78 (2012)) illustrates the fluorescence spectra of various materials and shows the effect of XRF measurements under atmospheric conditions versus when the atmospheric environment is replaced with nitrogen gas (N2). As shown, argon gas (Ar) provides a relatively high fluorescence response when present, however in a nitrogen gas (N2) environment, the Ar peak is reduced.

[0052] Accordingly, to eliminate or at least significantly reduce environmental data that interferes with the collected fluorescence emissions, the system 100 can utilize an inert gas purge arrangement 150 as described above. The inert gas purge arrangement 150 (e.g., purge unit 150a and purge unit 150b) can include gas tanks and release valves, or can be connected to external gas sources, and can be configured to flow a selected inert gas composition at the detection space prior to and during detection of a sample. The selected inert gas composition is selected to provide an inert gas mixture that has X-ray fluorescence away from the L-line fluorescence response of materials to be detected, such as silver and tin, while being chemically inert to interactions with the sample of system elements. Typically, the selected inert gas composition can include one or more of nitrogen gas (N2) and / or helium gas (He).

[0053] To eliminate or at least significantly reduce atmospheric gas interference with the detection data, the inert gas purge arrangement 150 can be operated to provide the selected inert gas composition at a selected flow rate to provide an overpressure condition. The inert gas flow is provided for removal of atmospheric air mixture, reduction or even elimination of fluorescence response associated with argon gas excitation.

[0054] In some embodiments, the inert gas purge arrangement can be connected to external gas sources, for example via a wall mount. Such inert gas purge arrangements can include one or more of the following arrangements: suitable connectors, valves, flow meters, particulate filters, gas purifiers (e.g., for N2 and / or He gas), and release ports.

[0055] To achieve the overpressure condition of the selected inert gas composition, the system 100 can be placed within an enclosed housing 160. The enclosed housing 160 need not be completely sealed, however, the typical gas flow through the opening in the housing can determine the flow rate required to provide the overpressure condition within the housing 160 and the time required to sufficiently purge the atmospheric mixture from the housing.

[0056] Generally, some detection systems operate to scan and generate output data indicative of the spectrum of fluorescent emissions at each scan location on the sample. Accordingly, in some embodiments of the present disclosure, the detection system 100 utilizes the inert gas purge arrangement 150 to provide a detection condition that enables the use of the L-line fluorescent response to probe and analyze the Ag / Sn solder regions while eliminating or at least significantly reducing the interference from the argon fluorescent response peaks. The output detection data can then be examined and analyzed to determine the composition and structural parameters of the sample including one or more Ag / Sn solder regions.

[0057] Further, in accordance with some embodiments, the present disclosure provides a method for detecting a sample. Figure 4 A method for a detection system in accordance with some embodiments of the present disclosure is exemplified. Specifically, the method includes providing a sample 4010 for detection, and generally placing the sample on a sample mount within the detection system. Generally, prior to the detection process, the present disclosure can include flowing 4020 a selected inert gas mixture (e.g., nitrogen and / or helium) into the detection system to purge the atmospheric gas mixture and eliminate or at least significantly reduce the presence of argon in the detection system to avoid argon peak interference with the detection results. After purging the atmospheric gas mixture, the method generally includes scanning and detecting the sample by XRF detection 4030. Scanning and detecting the sample generally includes, for each scan point, the detection can include irradiating the scan point with one or more X-ray beams (having a selected polychromatic or monochromatic energy range) 4032, collecting fluorescent emissions from the sample 4034 to generate output detection data for the respective scan location. Generally, the acts of irradiating the scan point with one or more X-ray beams 4032 and collecting fluorescent emission data 4034 can occur simultaneously or nearly simultaneously. Further, in some embodiments, the method can provide output data for each scan point immediately (act 4040). By scanning all selected regions of the sample, the detection process is performed until the scan of the sample is complete 4038.

[0058] The detection output data generally includes data regarding the spectrum and intensity of the fluorescent emissions for each scan point. The method includes providing the fluorescent data for analysis 4040, which can be done manually or using computer software. In some embodiments, the method can utilize the output of the fluorescent data for each scan point rather than generating the output data after the scan is complete.

[0059] Additionally, in some embodiments, the method includes analyzing the output detection data 4050 and determining the Ag / Sn solder connector 4060 based on a fluorescence peak associated with L-line excitation of the material of the sample.

[0060] As noted above, the L-line excitation of silver provides a peak at an energy of 2.984 keV and the L-line excitation of tin provides a peak at an energy of 3.444 keV. These energy peaks enable the energy of the interrogating X-ray beam to be reduced, where energies of 6 keV to 10 keV can be sufficient for L-line excitation. Additionally, the lower energy of the X-ray beam is typically characterized by a reduced penetration depth, thereby reducing interference from the substrate layers and the sample mount.

[0061] The inventors of the present disclosure conducted experiments to determine the effect of using an inert gas on detecting the L-line of Ag and / or Sn in a sample. Experimental data was collected using an X-ray detection system using a polychromator tube with a W anode (e.g., manufactured by MXR). The tube was operated at 50 kV and 950 mA using a multi-capillary arrangement (e.g., manufactured by XOS) with a focal spot of approximately 15 pm. The detection system also used a detector array manufactured by Amptek. The detection system was modified to support a flow of N2 gas onto the detection region to purge the measurement region and remove Ar.

[0062] Two sets of measurements were made on the 13 pm bump, each set consisting of 10 measurements of 60 seconds each. One set of measurements was made without N2 flow to obtain a reference point, and the second set of measurements was made with a flow of N2 at a rate of 2.5 L / min. Table 1 below summarizes the ten results from the different sets of measurements.

[0063] with a flow of N2 at a rate of 2.5 L / min. Table 1 below summarizes the ten results from the different sets of measurements.

[0064] Table 1

[0065]

[0066] From these results, the mean, standard deviation, and RSD were calculated, as shown in Table 2.

[0067] From the results, it can be seen that purging the detection region from unwanted gases using N2 was able to reduce the RSD by approximately 1.7%, in this example, from 8.85 to 7.18. When examining the Ar signal, it can be seen that the signal was reduced by 55%.

[0068] Table 2

[0069]

[0070] Accordingly, the present disclosure provides a detection system and method that is suitable for identifying one or more elements (typically Ag / Sn solder connectors) using L-line excitation of elements of a sample. The system and method can utilize purging of air from a detection region to eliminate or at least significantly reduce contamination of detection data due to environmental materials (such as argon) having a fluorescent peak with an energy peak close to the L-line excitation peak of the sample material.

[0071] It should be noted that the various features described in the various embodiments can be combined in all possible technical combinations.

[0072] It is to be understood that the application in its application and aspects is not limited to the details of construction and the arrangement of components set forth in the above description or illustrated in the drawings. The application is capable of other embodiments and of being practiced and carried out in various ways. Accordingly, it is not intended that the application be limited, in its application, to the details of construction and the arrangement of components set forth above and in the drawings. Further, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and not of limitation. Therefore, those skilled in the art will appreciate that the conception upon which this disclosure is based can readily be used as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present disclosed subject matter.

[0073] Those skilled in the art will readily understand that various modifications and changes can be applied to the embodiments of the application described above without departing from the scope of the application as defined by the appended claims.

Claims

1. An XRF detection system for detecting samples, the system comprising: At least one X-ray radiation source, said at least one X-ray radiation source providing X-ray radiation of a selected energy spectrum; An optical arrangement for focusing the X-ray radiation onto selected detection points of the sample; and at least one detector configured to detect radiation emitted from the sample and provide output data indicating the emission spectrum from the sample; wherein the output data includes data indicating the L-line excitation fluorescence response of the sample.

2. The XRF detection system of claim 1, further comprising an inert gas source configured to allow a selected inert gas composition to flow in the radiation path between the at least one X-ray source, the sample, and the at least one detector, thereby eliminating interference associated with components of the excited atmospheric composition.

3. The XRF detection system of claim 2, further comprising a housing, wherein the inert gas source is configured to provide overpressured inert gas to eliminate the atmospheric gas composition within the housing.

4. The XRF detection system of claim 2, wherein the selected inert gas composition is selected to avoid interaction between atmospheric conditions and X-ray radiation provided by the at least one X-ray source.

5. The XRF detection system according to claim 2, wherein the selected inert gas composition comprises nitrogen (N2) and / or helium (He).

6. The XRF detection system according to any one of claims 1 to 5, wherein the at least one X-ray source is a multicolor X-ray source that provides a selected radiation spectrum.

7. The XRF detection system according to any one of claims 1 to 5, wherein the optical arrangement comprises a multi-capillary arrangement for focusing X-ray radiation from the at least one X-ray source onto an illumination point with a diameter in the range of 1 micrometer to 100 micrometers.

8. The XRF detection system according to any one of claims 1 to 5, wherein the output data includes data indicating sample fluorescence emission in the energy range between 0.054 keV and 8 keV.

9. A method for detecting solder bumps in a sample, the method comprising: At least one X-ray beam is directed to at least one illumination point on the sample; Fluorescent X-ray emission from the sample is collected, and fluorescence emission data indicating the level and energy range of fluorescence emission are generated; The fluorescence emission data is processed, and data regarding the material content within one or more solder bumps are determined based on the emission peaks of the L-line excitation indicating the material in the sample.

10. The method of claim 9, further comprising providing a selected inert gas composition to the sample during detection, thereby reducing X-ray emission from one or more components of the atmospheric composition in the fluorescence emission data.

11. The method of claim 10, the method comprising detecting the sample within the housing and providing the selected inert gas composition under pressurized conditions within the housing to eliminate the atmospheric gas composition within the housing.

12. The method of claim 10, wherein the selected inert gas composition is selected to avoid interaction between the gaseous atmospheric conditions and the X-ray radiation provided by the at least one X-ray source.

13. The method of claim 10, wherein the selected inert gas composition comprises nitrogen (N2) and / or helium (He).

14. The method according to any one of claims 9 to 13, wherein guiding at least one X-ray beam comprises guiding a multicolor X-ray beam having a selected radiation energy spectrum.

15. The method according to any one of claims 9 to 13, wherein the fluorescence emission data includes data indicating sample fluorescence emission with energies in the range of 0.5 keV to 8 keV.

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