System and method for xrf inspection of solder bumps

Abstract

An XRF detection system and various methods are proposed. The system and methods are for sample detection. The system includes: at least one X-ray radiation source providing X-ray radiation of a selected energy spectrum; an optical configuration for focusing the X-ray radiation onto a selected detection point on 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 excited fluorescence response of the sample.

Description

Technical Field

[0001] This disclosure relates to a system and method for sample inspection using X-ray fluorescence, and also to a technique for evaluating solder bump composition in circuits. Prior Technology

[0002] Typical electronic circuits and circuit boards include various configurations of connection points. In some circuit boards, these connection points include solder bumps, often using an Ag / Sn (silver-tin) material combination. X-ray fluorescence (XRF) bump inspection is a non-destructive testing technique primarily used in the electronics manufacturing industry to assess the quality and composition of solder bumps on circuit boards. This technique uses XRF technology to analyze the elemental composition of solder bumps, which is crucial for forming reliable electrical connections in devices such as smartphones and computers.

[0003] During testing, an X-ray source directs X-rays to a selected location on the sample, typically the solder bumps. The interaction between the X-ray radiation and the elements within the bumps results in fluorescence, emitting secondary X-rays characteristic of 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 within each bump.

[0004] Generally, conventional XRF techniques use K-line excitation and fluorescence detection to detect Ag / Sn bumps. This technique typically operates with excitation X-rays of approximately 50 keV energy to detect fluorescence emission at approximately 25 keV energy.

[0005] Background of X-ray Fluorescence Analysis: 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, Vols. 73, 75-78 (2012): Total reflection X-ray fluorescence (TXRF) has achieved significant success, offering advantages such as simultaneous multi-element analysis capabilities, reduced background noise, absence of matrix effects, wide dynamic range, ease of operation, and potential for trace analysis. Dynamic environmental monitoring and management urgently require simultaneous quantitative online analysis of trace heavy metals, and TXRF shows promise in this application area. However, the need for TXRF-based online analysis protocols and robust and rapid quantitative methods has not been fully explored. Furthermore, spectral overlap and background effects can lead to loss of accuracy or even erroneous results during practical quantitative TXRF analysis. This paper proposes an intelligent multi-element quantitative method based on an established online TXRF analysis platform. In intelligent quantitative methods, the characteristic curves of all existing elements and the estimated background curves across the full spectral range are collected to approximate the measured spectrum. The novel hybrid algorithm PSO-RBFN-SA is designed to solve the curve fitting problem, featuring offline global optimization and rapid online computation. Experimental results demonstrate that the online TXRF analysis platform achieves simultaneous quantification of trace heavy metals, including Cr, Mn, Fe, Co, Ni, Cu, and Zn, while maintaining both high measurement accuracy and computational efficiency.

[0007] Menzel, M. et al., "Total reflection x-ray fluorescence analysis of airborne silver nanoparticles from fabrics," Analytical Chemistry, Vol. 86, pp. 3053-3059 (2014): Ag nanoparticles (NPs) are commonly used in consumer products due to their antibacterial properties, particularly in sportswear and cleaning fabrics. Airborne Ag NPs can be harmful to human health if inhaled. NPs are comparable in size to macromolecules and viruses and can penetrate deep into the lungs (e.g., alveoli), causing cell and tissue damage due to their large surface area. In this study, aerosols released from Ag NP-treated fabrics were collected using a low-pressure Berner impactor and analyzed by total reflection X-ray fluorescence (TXRF). We found that Ag NPs were mainly released in the form of larger particles, approximately 0.13 to 2 µm, which likely adhered to the fibrous material. Individual particles were identified using an electron microprobe. Detection of backscattered electrons indicated that the small spots on the particles were composed of heavier elements, most likely silver, 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 using a nitrogen atmosphere provided by a Picofox-box. This enabled linear calibration and quantification of Ag. The LOD was calculated at 0.2 ng (2.0 ppb). Following TXRF and scanning electron microscopy (SEM) / EDX analysis, the aerosol sample was dissolved in nitric acid and analyzed by ICPMS to successfully confirm the results obtained from the TXRF measurements. Summary of the Invention

[0008] For material analysis of Ag / Sn bumps in electronic circuit boards, conventional XRF techniques generally utilize the detection and analysis of K-lines. The excitation energy required to induce K-line fluorescence emission for these elements is relatively high and is generally correlated with the maximum energy of the X-ray source used. Furthermore, using such high energies (around 50 keV) for sample detection allows the excitation beam to penetrate the lower layer or substrate of the sample, providing output data indicating the material of the detection system. Additionally, several photons emitted from the lower layer of the sample can reach the detector. Moreover, the use of high-energy X-rays can induce Compton scattering at the energy corresponding to the K-line energy of the element being examined.

[0009] More specifically, in XRF measurements, an X-ray beam is used to excite the sample being analyzed. As indicated above, this excitation causes the sample to emit characteristic X-ray radiation at different energies corresponding to the elements present in the sample. When the sample contains elements from the periodic table, such as sulfur (S, Z=16) and above, the X-ray excitation can provide excitation from electrons in the inner shell, providing K-line excitation, or excitation from electrons in the second innermost shell, providing L-line excitation. Therefore, the K-line has a higher energy than the L-line because the energy required to excite electrons from the inner shell is greater than the energy required to excite electrons from the outer shell.

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

[0011] Therefore, this disclosure provides a testing system and method for inspecting a sample. The techniques disclosed herein are generally suitable for inspecting samples having one or more solder bumps, which are commonly used in electronic circuit boards for soldering various components to the board. Such solder bumps often include silver (Ag) and tin (Sn). The inspection of solder bumps can be used to determine the thickness and material composition of the bumps, allowing for the detection of mismatches between the circuit design and its actual structure, and the identification of manufacturing defects.

[0012] The system typically includes at least one X-ray radiation source (X-ray tube) that provides X-ray radiation of a selected energy spectrum; an optical configuration for focusing the X-ray radiation onto a selected detection point on the sample; and at least one detector configured to detect the radiation emitted from the sample and provide output data indicating the emission spectrum from the sample. According to this disclosure, the output data includes data indicating the L-line excited fluorescence response of the sample. For example, for Sn, the Lα series is at 3.444 keV, and for Ag, the Lα series is at 2.984 keV.

[0013] Typical X-ray sources used in detection systems operate at voltages of up to 50 kV. These X-ray sources are typically operated at their maximum energy output to provide K-line excitation of Ag / Sn bumps. One advantage of the technique disclosed herein concerns the ability to operate the X-ray source with lower energy requirements for L-line excitation. This makes L-lines more suitable for analysis under standard XRF operating conditions, ensuring better excitation. More specifically, approximately 6.888 kV and 5.968 kV of energy are required, respectively, to excite the Lα lines of Sn and Ag indicated above.

[0014] Generally, L-lines are feasible for analyzing heavy element systems and allow for optimal excitation of elements at relatively low voltages. However, simple detection using these energy lines can lead to inaccuracies due to the possibility of overlap with characteristic lines of other elements. For example, the Lα line of silver (Ag) has an energy of 2.984 keV and typically overlaps with the Kα line of argon (Ar) at 2.957 keV. Since argon is naturally present in atmospheric air, atmospheric conditions can affect the spectra obtained at these energies when samples are detected.

[0015] Therefore, this disclosure further provides a method of replacing the atmospheric gas composition described herein with a selected inert gas composition. This selected inert gas composition is used to eliminate normal air, and generally argon, to prevent it from affecting the detection results. For this purpose, the system may include an inert gas source (e.g., a gas tank and / or a pump) configured to allow a selected inert gas composition to flow to a region where the sample is located during detection. The selected inert gas composition comprises one or more materials, etc., whose energy levels are not aligned with the L-line peaks of the materials to be detected, thereby avoiding interference with the detection procedure. More specifically, in the detection of Ag / Sn bumps with the L-line energies detailed above, the selected inert gas composition may comprise molecular nitrogen (N2) and / or helium (He), both of which are chemically inert and have energy levels far removed from the Ag and Sn L-line levels. For example, N2 has a characteristic energy line at 0.392 keV, sufficiently far removed from the Lα lines of Ag and Sn.

[0016] Generally, the selected gas composition is also chosen to avoid any interaction with materials present on the wafer or machine's structural materials. Furthermore, the selected inert gas composition is chosen so that no special detectors are needed other than those used to detect L-line excitation. For example, the detection system may include one or more (e.g., four) polysiloxane drift detectors (SDDs).

[0017] In some embodiments, the detection system can operate within a sealed housing. Preferably, and during a detection operation, the system can provide the selected inert gas composition into the housing, providing overpressure conditions. This provides elimination, or at least significantly reduces, any interfering materials (such as Ar gas) from the housing.

[0018] Therefore, according to some embodiments, this disclosure provides the following examples:

[0019] Example 1: An XRF detection system for detecting a sample, the system comprising: at least one X-ray radiation source providing X-ray radiation of a selected energy spectrum; an optical configuration for focusing the X-ray radiation onto a selected detection point 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 excited fluorescence response of the sample.

[0020] Example 2: The XRF detection system of Example 1 further includes an inert gas source configured to allow a selected inert gas composition to flow through a radiation path between the at least one X-ray source, the sample, and the at least one detector, thereby eliminating interference associated with the excitation of components of the atmosphere.

[0021] Example 3: The XRF detection system of Example 2 further includes a housing in which the inert gas source is configured to provide overpressurized inert gas, thereby eliminating atmospheric gas composition from within the housing. In some examples, the inert gas system is directed to eliminate argon or other gases, preventing them from interacting with the X-ray beam in the system.

[0022] Example 4: An XRF detection system as in Example 2 or 3, wherein the selected inert gas composition is chosen to eliminate atmospheric conditions, thereby preventing it from interacting with the X-ray radiation provided by the at least one X-ray source.

[0023] Example 5: An XRF detection system as described in any of Examples 2 to 4, wherein the selected inert gas composition consists of nitrogen (N2) and / or helium (He).

[0024] Example 6: An XRF detection system as described in any of Examples 1 to 5, wherein the at least one X-ray source is a multicolor X-ray source that provides a selected radiation spectrum.

[0025] Example 7: An XRF detection system as described in any of Examples 1 to 6, wherein the optical configuration includes a multi-capillary configuration for focusing X-ray radiation from the at least one X-ray source onto an illumination point having a diameter between 1 micrometer and 100 micrometers.

[0026] Example 8: An XRF detection system as described in any of Examples 1 to 7, wherein the optical configuration includes a Fresnel lens configuration 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.

[0027] Example 9: An XRF detection system as described in any of Examples 1 to 8, wherein the output data includes data indicating the fluorescence emission of a sample with an energy range between 0.054 keV and 8 keV.

[0028] Example 10: An XRF detection system as described in any of Examples 1 to 9, wherein the output data includes data indicating the fluorescence emission of a sample with an energy range between 2.5 keV and 3.2 keV.

[0029] Example 11: An XRF detection system as described in any of Examples 1 to 10, further comprising a sample station adapted to hold the sample and to selectively displace the sample so as to scan 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 to at least one illumination point on the sample; collecting fluorescent X-ray emission from the sample and generating fluorescent emission data indicating the level and energy range of the fluorescent emission; processing the fluorescent emission data and determining data related to the material level within one or more solder bumps based on the emission peak of an L-line excitation indicating the material in the sample.

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

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

[0033] Example 15: The method of Example 13 or 14, wherein the selected inert gas composition is chosen such that atmospheric conditions are absent, thus preventing it from interacting with the X-ray radiation provided by the at least one X-ray source.

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

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

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

[0037] Example 19: The method of any one of Examples 12 to 18, wherein the fluorescence emission data includes data indicating the fluorescence emission of a sample with an energy range between 0.054 keV and 8 keV.

[0038] Example 20: The method of any one of Examples 12 to 19, wherein the fluorescence emission data includes data indicating the fluorescence emission of a sample with an energy range between 2.5 keV and 3.2 keV.

[0039] Example 21: The method of any one of Examples 12 to 20 further includes providing the sample on a sample stage, the sample stage being adapted to hold the sample and selectively shift the sample, thereby scanning at least one region of the sample. Simple Explanation of the Diagram

[0040] To better understand the subject matter disclosed herein and to illustrate how it can be carried out in practice, embodiments will now be described with reference to the accompanying drawings, by means of only non-limiting examples, in which: Figure 1 schematically illustrates a detection system according to some embodiments of the present disclosure; Figure 2 schematically illustrates a detection system according to some embodiments of the present disclosure; Figure 3 shows the fluorescence response spectra of the material under atmospheric conditions and under N2 conditions; and Figure 4 illustrates a method for detecting a sample according to some embodiments of the present disclosure. Implementation

[0041] Referring to FIG1, a system 100 for detecting a sample 50 is schematically illustrated. The system 100 includes: at least one X-ray source 110; an optical configuration 120 (e.g., a multi-capillary configuration) configured to focus an X-ray beam from at least one X-ray source 110 onto a selected illumination point on the sample 50; and one or more detectors 130, of which detectors 130a and 130b are illustrated.

[0042] Generally, system 100 may also include sample mount 140 (e.g., stepper) configured to mount sample 50 and shift the sample in at least two dimensions to enable sample scanning to detect different positions on sample 50.

[0043] In some embodiments, the detection system 100 may include a sealed housing 160. Furthermore, in some embodiments, the detection system includes an inert gas purging configuration 150 configured to allow a selected inert gas composition PG to flow into the housing. Two inert gas source systems are exemplified as 150a and 150b. The selected inert gas composition is chosen to purge atmospheric gases to eliminate interference from one or more atmospheric gases, thus preventing them from interacting with X-ray radiation at near one or more energy levels associated with sample detection.

[0044] The techniques and systems disclosed herein are applicable to the detection of one or more solder joints within electrical or electronic circuit boards. Generally, such solder joints are formed using silver-tin (Ag / Sn solder). The system disclosed herein utilizes X-ray excitation by an X-ray beam IR from one or more regions of a sample 50, collects fluorescence responses from the detection location, and analyzes the energy spectrum of the collected fluorescence responses FR to determine the material composition and structural parameters of the detection region. According to this disclosure, fluorescence spectral analysis for the detection and quantification of Ag / Sn solder regions utilizes a spectral range associated with the L-line excitation of the material.

[0045] Figure 2 roughly illustrates atomic energy levels and illustrates K-line excitation and L-line excitation with individual fluorescence reactions. When an electron in the innermost shell (K-excitation) or the second innermost shell (L-excitation) absorbs an X-ray beam, the X-ray beam excites the material in the sample, causing electrons to be released and leaving vacancies. In the fluorescence reaction, electrons from higher energy states relax into the vacancies, releasing photons corresponding to the energy difference.

[0046] As indicated above, the energy required for K excitation of silver (Ag) is approximately 44 keV, and for K excitation of tin (Sn) it is approximately 50 keV. These energies are typically at the higher end of the spectrum of typical X-ray tubes used for detection. Alternatively, L excitation of tin (Sn) requires 6.888 keV, and L excitation of silver (Ag) requires 5.968 keV. These lower energies are easier to achieve, eliminating interference associated with Compton scattering. Furthermore, lower energy X-ray beams in the 5 to 7 keV range are characterized by lower transmittance, enabling the detection of Ag / Sn bumps while reducing background interference and the influence of the material matrix beneath the detection area.

[0047] Detection of Ag / Sn bumps using L-excitation enables detection with reduced X-ray energies and offers various advantages over K-excitation-based detection. However, fluorescence data can include emissions from additional elements within these energy ranges. More specifically, the Kα line for argon (Ar) at 2.957 keV. Since argon is naturally present in atmospheric air, sample detection under atmospheric conditions can affect the resulting spectra at these energies. Figure 3 (from Imashaku et al., Spectrochim Acta Part B At Spectrosc, pp. 73, 75–78 (2012)) illustrates the fluorescence spectra of various materials and shows the effect of atmospheric conditions on XRF measurements when the atmospheric environment is replaced by nitrogen (N2). As shown, the presence of argon (Ar) provides a relatively high fluorescence response, while in a nitrogen (N2) environment, the Ar peak is reduced.

[0048] Therefore, to eliminate or at least significantly reduce environmental interference in the collected fluorescence emission, system 100 may utilize an inert gas purging configuration 150 as described above. The inert gas purging configuration 150 (e.g., purging units 150a and 150b) may include a gas trough and a release valve or be connected to an external gas source and configured to allow a selected inert gas composition to flow through the detection space before and during sample detection. The selected inert gas composition is chosen to provide an inert gas mixture that exhibits X-ray fluorescence with an L-line fluorescence response away from the material to be detected (such as silver and tin), while being chemically inert to the sample interacting with the system elements. Generally, the selected inert gas composition may include one or more of nitrogen (N2) and / or helium (He).

[0049] To eliminate or at least significantly reduce interference from atmospheric gases in the detection data, an inert gas drive configuration 150 can be operated to provide overpressure conditions at a selected flow rate. The inert gas flow is used to remove the atmospheric air mixture to reduce or even eliminate fluorescence reactions associated with argon excitation.

[0050] In some embodiments, the inert gas driven configuration may be connected to an external gas source (e.g., via a wall mount). Such an inert gas driven configuration may include one or more of the following: a suitable connector, valve, flow meter, particle filter, gas purifier (e.g., for N2 and / or helium), and a release port.

[0051] To achieve the overpressure conditions of the selected inert gas composition, system 100 can be placed within a sealed housing 160. The sealed housing 160 does not need to be completely sealed; however, a typical gas flow through-hole in the housing can determine the flow rate required to provide the overpressure conditions within the housing 160 and the time required to adequately purge the atmospheric mixture from the housing.

[0052] Generally, some detection systems operate to scan samples and generate output data indicating fluorescence emission spectra for each scanned position on the sample. Therefore, in some embodiments disclosed herein, detection system 100 utilizes an inert gas driving configuration 150 to provide detection conditions for detecting and analyzing Ag / Sn solder regions using L-line fluorescence, while eliminating or at least significantly reducing interference from argon fluorescence peaks. The output detection data can then be examined and analyzed to determine the composition and structural parameters of a sample comprising one or more Ag / Sn solder regions.

[0053] Further, according to some embodiments, this disclosure provides a method for detecting a sample. Figure 4 illustrates a method for a detection system according to some embodiments of this disclosure. Specifically, the method includes providing a sample 4010 for detection, and typically placing the sample on a sample mount within the detection system. Typically, prior to the detection procedure, this disclosure may include allowing a selected inert gas mixture (e.g., nitrogen and / or helium) to flow into the detection system 4020 to expel 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 typically includes scanning and detecting the sample 4030 by XRF detection. Scanning and detecting the sample typically includes, for each scan point, irradiating the scan point 4032 (having a selected polychromatic or monochromatic energy range) with one or more X-ray beams, collecting fluorescence emission 4034 from the sample to generate output detection data for each scan location. Typically, the actions of irradiating the scan point 4032 with one or more X-ray beams and collecting the fluorescence emission data 4034 may occur simultaneously or nearly simultaneously. Furthermore, in some embodiments, the method can immediately provide output data for each scan point (action 4040). The detection procedure is executed until the sample scan is completed by scanning all selected areas of the sample 4038.

[0054] The detection output data typically includes data on the spectrum and intensity of fluorescence emission at each scan point. The method includes providing fluorescence data for analysis 4040, which can be performed manually or using computer software. In some embodiments, the method may utilize the output of fluorescence data for each scan point rather than generating output data after the scan is completed.

[0055] Furthermore, in some embodiments, the method includes analyzing output detection data 4050 and determining the Ag / Sn solder connector 4060 based on the fluorescence peak associated with the L-line excitation of the sample material.

[0056] As indicated above, silver's L-line excitation provides a peak at energy 2.984 keV, and tin's L-line excitation provides a peak at energy 3.444 keV. These energy peaks allow for lowering the energy of the interrogating X-ray beam, where energies of 6 to 10 keV are sufficient for L-line excitation. Furthermore, the lower energy of the X-ray beam is typically characterized by reduced penetration depth and decreased interference from the substrate layer and sample mount.

[0057] The inventors of this disclosure have conducted experiments to determine the effect of using an inert gas when detecting the L-lines of Ag and / or Sn in a sample. Experimental data were collected using an X-ray detection system with a W anode (e.g., manufactured by MXR). This system was operated at 50 kV and 950 mA using a multi-capillary configuration with a focal spot of approximately 15 µm (e.g., manufactured by XOS). The detection system further utilized a detector array manufactured by Amptek. The detection system was modified to support the flow of N2 gas into the detection area to clean the measurement area and remove Ar.

[0058] Two sets of measurements were performed on a 13 µm bump, each consisting of 10 measurements, each lasting 60 seconds. One set of measurements was performed without an N2 flow to obtain a reference point, and the second set was performed with...

[0059] The experiment was conducted at a flow rate of 2.5 L / min N2. Table 1 below summarizes ten results from different groups of measurements. Table 1 There is an N2 flow No N2 flow Ag (CPS) Ar (CPS) Sn (CPS) Ag (CPS) Ar (CPS) Sn (CPS) 1 202 128 20,916 212 276 20,305 2 204 124 20,861 220 271 20,315 3 216 118 20,884 215 279 20,316 4 208 129 20,879 216 278 20,339 5 212 123 20,882 225 272 20,324 6 211 129 20,913 220 271 20,310 7 219 122 20,908 221 276 20,306 8 210 122 20,919 212 279 20,311 9 208 122 20,900 208 284 20,317 10 211 118 20,916 205 280 20,325

[0060] The mean, standard deviation, and RSD were calculated from these results, as shown in Table 2.

[0061] As can be seen from the results, using N2 to remove unwanted gases from the detection area reduces the RSD by approximately 1.7%, in this example, from 8.85 to 7.18. When examining the Ar signal, a 55% reduction is observed. Table 2 There is an N2 flow No N2 flow Ag Ar Sn Ag Ar Sn Average (CPS) 210 124 20,898 215 277 20,317 Standard deviation (CPS) 5.03 3.98 19.97 6.35 4.11 10.24 RSD% under 3σ 7.18 N / A 0.29 8.85 N / A 0.15

[0062] Therefore, this disclosure provides a detection system and a detection method suitable for identifying one or more elements (typically Ag / Sn solder connectors) using L-line excitation of a sample element. The system and method can eliminate or at least significantly reduce contamination of the detection data by the fluorescence peaks of ambient materials (such as argon) having energy peaks close to the L-line excitation peaks of the sample material by removing gas from the detection area.

[0063] It should be noted that the various features described in the various embodiments can be combined according to all possible combinations of techniques.

[0064] It should be understood that the present invention is not limited to the application of the details set forth in the description contained herein or illustrated in the drawings. The invention can have other embodiments and can be practiced and implemented in various ways. Therefore, it should be understood that the words and terms used herein are for descriptive purposes and should not be considered limiting. Thus, those skilled in the art will understand that the concepts on which this disclosure is based can be readily utilized as a basis for designing other structures, methods, and systems to achieve several of the objectives of the subject matter currently disclosed.

[0065] Those skilled in the art will readily understand that various modifications and alterations can be applied to the embodiments of the invention as described above without departing from the scope of the appended patent applications and as defined by the appended patent applications.

[0066] 50: Sample 100: Detection System 110: X-ray source 120: Optical Configuration 130: Detector 130a: Detector 130b: Detector 140: Sample mounting base 150: Inert gas driven configuration 150a: Inert gas source 150b: Inert gas source 160: Sealed shell 4010: Steps 4020: Steps 4030: Steps 4032: Steps 4034: Steps 4038: Steps 4040: Steps 4050: Steps 4060: Steps FR: Fluorescence reaction IR: X-ray beam PG: Inert gas composition

Claims

1. An XRF detection system for detecting a sample, the system comprising: at least one X-ray radiation source providing X-ray radiation of a selected energy spectrum; an optical configuration for focusing the X-ray radiation onto a selected detection point 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; The XRF detection system further includes an inert gas source configured to provide a selected inert gas composition to a measurement region comprising a portion of a radiation path between at least one X-ray radiation source, the selected detection point, and the at least one detector, thereby purging atmospheric gases from the measurement region. The selected inert gas composition is chosen to avoid interaction with the material on the sample to be detected and the structural material of the XRF detection system. Furthermore, the selected inert gas composition is chosen such that detection of L-line excited fluorescence can be performed using a detector for detecting L-line excitation without the need for other detectors.

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

3. The XRF detection system of claim 1, further comprising a housing, wherein the inert gas source is configured to provide the selected inert gas composition under pressurized conditions within the housing, thereby eliminating atmospheric gas composition from within the housing.

4. The XRF detection system of claim 1, wherein the selected inert gas composition comprises one or more materials whose characteristic fluorescence energy levels are not aligned with the L-line peak of at least one material to be detected.

5. The XRF detection system of claim 1, wherein the selected inert gas composition is composed of nitrogen (N2) and / or helium (He).

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

7. An XRF detection system as claimed in any one of claims 1 to 5, wherein the optical configuration includes a multi-capillary configuration for focusing X-ray radiation from the at least one X-ray radiation source onto an illumination point having a diameter in the range of 1 micrometer to 100 micrometers.

8. An XRF detection system as claimed in any of claims 1 to 5, wherein the output data includes data indicating sample fluorescence emission with energies in the range of 0.054 keV to 8 keV.

9. A method for detecting solder bumps in a sample, the method comprising: directing at least one X-ray beam to at least one illumination point on the sample; collecting fluorescent X-ray emission from the sample and generating fluorescence emission data indicating the level and energy range of the fluorescence emission; processing the fluorescence emission data and determining data related to the material level within one or more solder bumps based on the emission peak of L-line excitation indicating the material in the sample; and providing a selected inert gas composition to a measurement area containing the sample before and during at least a portion of the directing and collection process, thereby purging atmospheric gases from the measurement area; wherein the selected inert gas composition is selected to avoid interaction with the material on the sample to be detected and the structural material of a detection system for performing the method; and wherein the collection is performed using a detector for detecting L-line excitation, without requiring any other special detectors besides the detector.

10. The method of claim 9, wherein providing the selected inert gas composition includes providing the 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 9, comprising detecting the sample within a housing and providing the selected inert gas composition within the housing under pressurized conditions, thereby eliminating atmospheric gas composition from the housing.

12. The method of claim 9, wherein the collection is performed by using one or more polysiloxane drift detectors.

13. The method of claim 9, wherein the selected inert gas composition is composed of nitrogen (N2) and / or helium (He).

14. The method of 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 of any one of claims 9 to 13, wherein the fluorescence emission data includes data indicating the fluorescence emission of a sample with an energy range between 0.5 keV and 8 keV.

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