DE102018212403A1 - Inspection system and inspection procedure for quality assessment of semiconductor structures - Google Patents

Abstract

An inspection system (1) is used to assess the quality of semiconductor structures. The inspection system has an ion beam source (2) for the spatially resolved exposure of the structures, which can be qualitatively assessed with an ion beam (3). A secondary ion detection device (12) including a mass spectrometer (13) is also provided. The mass spectrometer (13) is able to measure an ion mass to charge ratio in a given bandwidth.

Description

The invention relates to an inspection system for quality assessment of semiconductor structures. The invention further relates to an inspection method for quality assessment of semiconductor structures.

An inspection system and also an inspection procedure for quality assessment of 3D semiconductor structures is over US 2007/0221843 A1 is known and is also known from G. Hlawacek and A. Gölzhäuser (ed.), Helium Ion Microscopy, Nanoscience and Technology, Springer International Publishing, Switzerland, 2016.

It is an object of the present invention to improve such an inspection system for the quality assessment of semiconductor structures, in particular for the quality determination of 2D or 3D semiconductor structures.

This object is achieved by an inspection system which contains the features from claim 1.

It has been recognized that using a mass spectrometer to measure ion mass to charge ratios at a given bandwidth, along with using an ion beam source to produce secondary ions to be detected by the mass spectrometer, provides a powerful tool for quality assessment of semiconductor structures , The system can be used for quality assessment of 2D and / or 3D structures. The system is able to place a well-defined confined ion beam on an object or sample that is to be qualitatively assessed. Furthermore, the system can correlate high-resolution secondary ion imaging on the one hand with analytical information obtained by means of mass spectroscopy, on the other hand. To this end, the system can include secondary electron imaging optics. The secondary ion mass spectrometer involved here enables different ion mass-to-charge ratios to be tracked at the same time and therefore gives respective information with reference to different materials and / or elements and / or isotopes that are present in a sample area. It was also recognized that the results of such an inspection system are not impaired by the use of a low-current ion beam which can be provided with a high spatial resolution and also with a very small focal diameter. The spatial resolution can be better than 100 nm, better than 50 nm and can be better than 20 nm. A focal diameter of the ion beam can be less than 10 nm, less than 5 nm, less than 2 nm, less than 1 nm and can even be less than 0.5 nm. The inspection system can be used as part of a device for checking and / or removing defects in the qualitatively assessed semiconductor structures. The inspection system can be used to check special structures, for example to inspect and check HAR contact coils (HAR: High Aspect Ratio). Such inspection and verification steps can take place during a manufacturing process of the respective semiconductor structure.

• Eine Anwendung ist die Messung einer kritischen Dimension (CD: Critical Dimension) unter Verwendung von Sekundärionenmassenspektrometrie (SIMS), die die wachsende Komplexität und den Umfang an in Halbleitervorrichtungen verwendeten Materialien bewältigt. Aufgrund der Verwendung des Massenspektrometers ist das Inspektionssystem dazu in der Lage, zwischen Elementen basierend auf Masse zu unterscheiden. Dies kann genutzt werden, um klassische CD-Messungen von Halbleitervorrichtungen abzuschließen, die keinerlei elementare/chemische Informationen ergeben. Die Sekundärionenausbeute in herkömmlicher Ionenmikroskopie liefert lediglich Graustufen pro Element für eine qualitative Analyse.

The inspection system according to the invention has a wide variety of applications. Some of them are discussed below:

• One application is the measurement of a critical dimension (CD: Critical Dimension) using secondary ion mass spectrometry (SIMS), which copes with the increasing complexity and amount of materials used in semiconductor devices. Due to the use of the mass spectrometer, the inspection system is able to distinguish between elements based on mass. This can be used to complete classic semiconductor device CD measurements that do not provide any elemental / chemical information. The secondary ion yield in conventional ion microscopy provides only gray levels per element for a qualitative analysis.

Another application of the inspection system according to the present invention is the characterization of organic films. This application can be used for directional self-assembly (DSA: Directed Self-Assembly) for wafer structuring. A DSA vapor that is used often uses block copolymers to form structures that have typical dimensions between 10 nm and 100 nm (nano range). A distinction between different types of organic polymers in the nanoscale is very important when developing processes using DSA. The inspection system according to the invention has the ability to directly distinguish between different types of polymers using a characteristic fingerprint that is measured with the mass spectrometer.

Another application of the inspection system is the detection of individual and buried defects. The detection and analysis of a chemical structure of individual defects on a wafer is important in order to determine the origin of such defects. In addition, chemical information about buried defects and a surrounding layer can be determined with the inspection system.

Another application of the inspection system is etch residue characterization. Such an analysis of etch residues on wafers provides valuable information. In particular, a stoichiometric variation of etch chemicals is of interest to determine a cause of an incomplete / faulty etch or incorrect subsequent process steps caused by etch residues within limited volumes, such as trenches, holes, corners, etc. The use of the inspection system according to the invention, which can have a high spatial resolution and / or a high surface sensitivity, makes it possible to query the stoichiometric variation across different device topologies.

Providing a mass spectrometer that is capable of continuously measuring ion mass to charge ratios according to claim 2 further improves the information output of the inspection system. With the selected mass-to-charge ratio bandwidth, all the ion mass-to-charge ratios present there can be detected simultaneously. The selected ion mass to charge ratio bandwidth can include a bandwidth that is capable of detecting the elements silicon, titanium, copper, selenium, tellurium and antimony at the same time. The resulting mass bandwidth can range from 1 u (unified atomic mass unit) to 500 u.

A secondary electron detection unit according to claim 3 enables secondary ion detection with high accuracy and high efficiency. A usable yield, ie the ratio between the number of secondary ions on the one hand that can be measured by the inspection system and the number of atomized particles that are produced by the ion beam on the other hand can be high. The usable yield can range from 10 ^-5 to 0.1.

Ion beams according to claims 4 or 5 have been found to be particularly useful for the inspection system.

A secondary ion transfer unit according to claim 6 enables switching between a semiconductor structure production mode of a device that can be used as a projection exposure device and an inspection mode with the secondary ion transfer unit in the transfer position. This enables an integrated inspection during a semiconductor production process.

A total ion counter according to claim 7 gives z. B. Ratio information about the occurrence distribution of different elements in a scanned area.

An extensive detector array according to claim 8 gives a high spatial resolution of the secondary ion detection device, which can lead to a high mass resolution. The detector array can be implemented as an array of channel electron multipliers (CEMs: Channel Electron Multipliers) or a microchannel plate (MCP: Micro-Channel Plate).

Another object of the invention is to improve an inspection method for the quality assessment of semiconductor structures, in particular for the quality assessment of 2D or 3D semiconductor structures.

This goal is achieved by an inspection process according to the steps from claim 9.

It was recognized that a combination of a rough review of the structure to be assessed qualitatively on the one hand and a more detailed review of quality assessment volume candidates identified in the rough review step using an ion beam and a secondary ion detection device, an inspection of scanning areas / volumes that are to be checked in detail, with high accuracy and high informative value. The volumes to be checked in detail can be selected using the rough inspection step, which can be carried out using a secondary electron microscope image. The detailed check based on the ion beam and the secondary ion detection device can then be performed based on the rough information derived from the rough check. Performing continuous mass spectrometry leads to the ability to collect detailed element distribution information of the volume to be checked in the detailed review step.

A lateral spatial resolution according to claim 10 gives a high informative value. Tiny structural details that can correspond to the resolution of a semiconductor structure process can be checked in detail.

A focus diameter according to claim 11 has the corresponding advantages.

The advantages of the inspection method are very effective if the inspection method is carried out integrated during a semiconductor production process according to claim 12. Additionally or alternatively, the inspection process can be used to perform a failure analysis perform an object or sample surface, and / or can be used to perform defect detection. Such a fault analysis / defect detection can take place in an offline mode, ie not during a semiconductor production process.

• 1 zeigt eine schematische Veranschaulichung der Strahl/Teilchen-Wechselwirkung in einem Inspektionssystem zur Qualitätsbeurteilung von 3D-Halbleiterstrukturen;
• 2 zeigt Hauptkomponenten des Inspektionssystems in einer weiteren schematischen Veranschaulichung;
• 3 zeigt einen Abschnitt eines Mikroskopbildes, das von dem Inspektionssystem von Sekundärelektronen erhalten wurde, die durch das Inspektionssystem produziert wurden;
• 4 zeigt ein Diagramm einer zeitaufgelösten Zählrate der drei verschiedenen Ionenenergien, die durch ein Massenspektrometer des Inspektionssystems bei drei unterschiedlichen Positionen innerhalb des in 3 gezeigten Objektabschnitts gemessen werden;
• 5 zeigt im Vergleich zu 3 einen anderen Abschnitt des Objekts, der durch Sekundärelektronen durch das Inspektionssystem vor einem Objektfrässchritt durch den Ionenstrahl abgebildet wird, in einem weiter vergrößerten Maßstab;
• 6 zeigt den Abschnitt gemäß 5 nach dem Frässchritt, der drei unterschiedliche gefräste rechteckige Abschnitte zeigt;
• 7 zeigt den Abschnitt aus 6, wobei die gefrästen Bereiche hervorgehoben sind;
• 8 zeigt die Zeitentwicklung von drei unterschiedlichen gemessenen Ionenenergien, die aus einem ersten in 7 hervorgehobenen Bereich abgeleitet werden, in einem zu 4 vergleichbaren zeitaufgelösten Diagramm;
• 9 zeigt die Zeitentwicklung von drei unterschiedlichen gemessenen Ionenenergien, die aus einem zweiten in 7 hervorgehobenen Bereich abgeleitet werden, in einem zu 4 vergleichbaren zeitaufgelösten Diagramm; und
• 10 zeigt die Zeitentwicklung von drei unterschiedlichen gemessenen Ionenenergien, die aus einem dritten in 7 hervorgehobenen Bereich abgeleitet werden, in einem zu 4 vergleichbaren zeitaufgelösten Diagramm.

Embodiments of the invention are explained below with reference to the drawings. In these drawings:

• 1 shows a schematic illustration of the beam / particle interaction in an inspection system for quality assessment of 3D semiconductor structures;
• 2 shows main components of the inspection system in a further schematic illustration;
• 3 shows a portion of a microscope image obtained from the inspection system of secondary electrons produced by the inspection system;
• 4 shows a diagram of a time-resolved count rate of the three different ion energies, which is determined by a mass spectrometer of the inspection system at three different positions within the 3 object section shown are measured;
• 5 shows compared to 3 another portion of the object, which is imaged by secondary electrons through the inspection system before an object milling step by the ion beam, on a further enlarged scale;
• 6 shows the section according to 5 after the milling step, which shows three different milled rectangular sections;
• 7 shows the section 6 , with the milled areas highlighted;
• 8th shows the time evolution of three different measured ion energies from a first one in 7 highlighted area are derived in a too 4 comparable time-resolved diagram;
• 9 shows the time evolution of three different measured ion energies from a second one in 7 highlighted area are derived in a too 4 comparable time-resolved diagram; and
• 10 shows the time evolution of three different measured ion energies, from a third in 7 highlighted area are derived in a too 4 comparable time-resolved diagram.

1 and 2 show the working principle and the main components of an inspection system 1 for the quality assessment of three-dimensional (3D) semiconductor structures, in particular for the quality assessment of lithography photo masks. Such photomasks can be particularly suitable for EUV projection lithography.

The inspection system 1 has an ion beam source 2 on that in 1 is shown schematically. Such an ion beam source 2 is a plasma source with a well-defined source volume. Examples of such an ion beam source are shown in US 2007/0221843 A1 disclosed. The ions produced by the ion beam source are noble gas ions, especially helium or neon ions. Other noble gases including argon, krypton or xenon can also be used by providing an appropriate ion beam source.

The ion beam source produces an ion beam 3 with well-defined directional properties. The spatial resolution caused by such an ion beam 3 is better than 20 nm. The ion beam 3 is on an object field 4 on one surface 5 of an object or a sample 6 with the 3D structures focused by the inspection system 1 are to be assessed qualitatively. A focal diameter of the ion beam 3 is less than 0.5 nm.

The ion beam can have an energy in the range of 2.5 keV to 30 keV, for example 25 keV. A beam current of the ion beam can be in the range from 1 to 100 pA, in particular in the range from 10 pA.

1 shows schematically the interaction of the focused ion beam 3 in the object field 4 with material of the object 6 , There are three types of atoms 7 . 8th . 9 shows that from the object field of the surface 5 through the ion beam 3 be atomized. The atom 7 is positively charged. The atom 8th is neutral. The atom 9 is negatively charged. Furthermore, a secondary electron (SE) is shown, which are produced during this atomization and which in 1 are designated with e-. Next is in 1 a beam interaction area 10 shown an interaction between the ion beam 3 and the matter of the object 6 takes place during the atomization process.

In 1 a Cartesian x / y / z coordinate system is also shown. The coordinates x and y span the surface 5 of the object 6 on. The coordinate z is perpendicular to such an x / y surface plane.

Such a beam interaction area 10 has a very well-defined volume with x / y dimensions in the range from 5 nm to 50 nm and with a z dimension in the range from 5 nm to 50 nm. The inspection system 1 includes secondary electron optics 11 which is capable of producing a secondary electron image of the object field 4 to produce. Such secondary electron optics is also in US 2007/0221843 A1 disclosed. The system 1 can also have projection optics of a projection exposure device for EUV lithography. During such a semiconductor manufacturing process, a three-dimensional structure can be produced by placing a reticle on the object field 4 is imaged with the projection exposure device using the projection optics.

The inspection system 1 further includes a secondary ion detection device 12 for the detection of secondary ions, especially the charged atoms 7 and 9 that result from ion beam sputtering. The secondary ion detection unit 12 includes a mass spectrometer 13 ,

The mass spectrometer 13 is capable of secondary ion mass spectrometry (SIMS). Such a mass spectrometer 13 is able to measure ion mass-to-charge ratios of the secondary ions in a given bandwidth and in particular to measure them continuously. This is shown schematically in 2 shown the secondary ion beam paths 14 . 15 . 16 . 17 represents that correspond to different ion mass-to-charge ratios. After the secondary ions have been collected by an extraction optics, they are evenly at z. B. 3 kV accelerated towards a magnetic sector.

The ray path 14 relates to the smallest detectable ion mass. The ray path 17 affects a largest detectable ion mass. There is a continuous ion mass bandwidth between this smallest and largest ion mass 18 by the mass spectrometer 13 is detectable.

In 2 a diagram is schematically shown which shows an accumulated count result in this ion mass-to-charge bandwidth 18 after a certain measuring period of the inspection system 1 shows. Accumulated count rates are shown for a large number of different ion mass-to-charge ratios, which correspond to different elements. The mass spectrometer contains to measure the ion energies 13 a secondary electron detection unit 19 including a total ion counter. The secondary ion detection unit 19 is implemented as an extended detector array. An example of such a detector array is an array of channel electron multipliers (CEM). The secondary ion detection unit may include 4 or more such channel electron multipliers, for example 4, 5, 6, 8, 10, 15, 20, 25, 30, 50, 75, 100 or even a larger number of channel electron multipliers.

The secondary ion detection unit 19 can be implemented as a microchannel plate (MCP) with more than 50, more than 100, more than 200, more than 500, more than 1000, more than 2000 or even more than 4000 channels.

The secondary ion detection unit further includes a secondary ion transfer unit 20 , Such a secondary ion transfer unit 20 is between one in 2 shown first position, in which the secondary ion transfer unit 20 Secondary ions (ie charged atoms 7 . 9 ) originating from the beam interaction area, ie originating from a target volume of a probe structure to be assessed qualitatively, to the mass spectrometer 13 and in particular to the secondary ion detection unit 19 transferred, and a second, neutral position movable, in which the secondary ion transfer unit 20 does not counteract secondary electrons and / or secondary ions produced in the beam interaction area. Such mobility of the secondary ion transfer unit 20 To reach between the first transfer position and the second neutral position, the secondary ion transfer unit interacts 20 with a drive 21 ,

The secondary ion transfer unit 20 includes a first distractor 22 which is in the transfer position of the secondary ion transfer unit 20 directly above the beam interaction area 10 located. The distractor 22 includes a pass-through channel for passing the ion beam through 3 in the beam paths between the ion beam source 2 and the beam interaction area 10 , Also includes the secondary ion transfer unit 20 a jet tube 23 for encapsulating the secondary ion beam path between the deflecting means 22 and the mass spectrometer 13 , The mass spectrometer 13 itself includes two other distractions 24 . 25 , the latter being the magnetic sector for widening the secondary ion beam paths 14 to 17 to the secondary ion detection unit 19 serves. The secondary ion detection unit 19 , ie the CEMs, is at a focal plane of the magnetic sector 25 arranged. The CEMs are used to directly measure the secondary ions, which have different trajectories, based on their mass-to-charge ratio (compare beam paths 14 to 17 in 2 ).

The distractor 22 is implemented as an electrostatic sector.

The distractor 24 is implemented as an electrostatic sector.

The secondary ions are from the sample 6 collected and electrostatically focused, accelerated and on a focal plane of the secondary ion detection unit 19 projected. The mass spectrometer 13 can have a Mattauch-Herzog design.

In a typical operating mode of the system 1 become the magnetic field of the magnetic sector 25 and the position of the secondary electron detection unit 19 is kept constant and a count rate on the respective channels of the secondary ion detection unit 19 while buffering the sample 6 measured to obtain volumetric information about this sample.

A mass resolution of the mass spectrometer 13 is sufficient to distinguish not only different elements, but also individual isotopes.

A measurement of an ion mass-to-charge ratio bandwidth can be carried out in an alternating operating mode by scanning the magnetic field of the magnetic sector 25 and / or by moving individual detectors or the entire secondary ion detection unit 19 to be produced.

An embodiment, in particular the distraction means 24 . 25 and the secondary ion transfer unit is in G. Hlawacek and A. Gölzhäuser (ed.), Helium Ion Microscopy, Nanoscience and Technology, Springer International Publishing, Switzerland, 2016, in particular in chapter 13 from Tom Wirtz et al., "SIMS on the helium ion microscope: The powerful tool for high-resolution high-sensitivity nano-analytics".

Using the inspection system 1 is an inspection method for quality assessment of 3D semiconductor structures in the following with reference to 3 to 10 described.

The inspection process includes a step of a rough review of the structure to be assessed qualitatively.

3 shows an example of such a rough inspection inspection step. A section of an object to be assessed qualitatively is shown 6 , Such a scanning area 26 of the object 6 is using a conventional secondary electron microscope technique using secondary electron optics 11 of the inspection system 1 produced. The object to be inspected 6 includes some structural areas. Sub-areas "1", "2" and "3" of these object structures to be inspected are shown in 3 highlighted.

Section "1" contains a ridge structure that shows some kind of stopper in electron microscope imaging without further definition. Section "2" shows a corresponding ridge without such a plug. Subarea "3" is an example of several "outgrowth" structures that are in some positions on the sample area of the object 6 are present during the rough check step.

Those highlighted subsections "1", "2" and "3" serve as quality assessment volume candidates that are identified in the rough review step. During the inspection process, these subareas "1", "2" and "3" are now subjected to a detailed review during the inspection process. During this detailed check, a spatially resolved ion beam atomization is carried out in the volume of the respective partial area “1”, “2” and “3” by the ion beam 3 “1”, “2” and “3” are aimed at these sub-areas. For each of these sub-areas "1", "2" and "3", the secondary ions (compare secondary ions 7 and 9 out 1 ) detected during the detailed check in a time-resolved measurement. These detected secondary ions are subjected to continuous mass spectrometry using the secondary ion transfer unit and the mass spectrometer 13 subjected, ie using the secondary ion detection device 12 of the inspection system 1 as above with reference to 2 is described.

4 shows the time-resolved results of the detailed review of sub-areas "1", "2" and "3". The ordinate in the diagram 4 is the measured count rate, given in counts per second (CPS: Counts Per Second).

During the measurement, the ion beam 3 in a first time period T _{1 is directed} to sub-area "1", in a subsequent time period T _{2 is directed} to sub-area "2" and in a last time period T _{3 is directed} to sub-area "3".

The count rate, shown as a solid line, is as a first ion energy level of the mass spectrometer 13 given that corresponds to silicon (Si). The count rate, shown as a dashed line, is given for an ion energy corresponding to titanium (Ti). The count rate, shown as a dashed line, is given for an ion energy corresponding to copper (Cu).

The time-resolved count according to 4 also gives information about a depth distribution of the occurrence of the respective elements Si, Ti, Cu. In the area "1" there is titanium and copper on the surface. If the ion beam 3 milling under the surface of sub-area "1", the occurrence of titanium and copper drops and the occurrence decreases of the base material silicon, so that it dominates after a short sampling time.

There is no titanium in section "2" and the time-resolved behavior of the counting rates with regard to silicon and copper is similar to that of the measurement in section "1". From a comparison of the measurements of the partial areas "1" and "2" it can be deduced that in the secondary electron microscopy image 3 plug shown is a titanium plug.

The measurement at the “outgrowth” position of sub-area “3” shows that there seem to be traces of titanium that are just above the resolution limit of the mass spectrometer 13 are. The time-resolved behavior with regard to the presence of silicon and copper is similar to that in sub-areas "1" and "2". From a comparison of the count rate measurement of sub-area “3” with those of sub-areas “1” and “2”, it can be concluded that this is shown in the secondary electron microscopy image 3 shown "outgrowth" consists of titanium.

A lateral spatial resolution with regard to the detailed checking step described above is better than 100 nm and in particular better than 75 nm, better than 50 nm and better than 30 nm. The lateral spatial resolution, ie the resolution in x and y, can be 20 nm or even better , The depth resolution (z direction) depends on the milling rate of the ion beam 3 in the material of the object 6 from. Such a depth resolution can also be in the range of 100 nm or even better.

Accuracy in terms of ion beam 3 surface area to be scanned in the object field 4 can be better than 5 nm, can be better than 3 nm and can even be better than 1 nm. Such accuracy is particularly important when trying to detect probe structures, such as the "outgrowth" in sub-area "3". Such a more or less point-like partial area is detected by means of a rough check and its coordinates are then used for a relative positioning control of the inspection system 1 fed to ensure that the beam interaction area 10 correct for the sub-area in question, e.g. B. the section "3" is positioned. For this purpose the object 6 positioned at a high position xyz coordinate table that has a respective drive to the object 6 to move in a well-defined way with respect to the Cartesian coordinates x, y, z.

Such a relative movement between the ion beam 3 on the one hand and the object 6 on the other hand, additionally or alternatively, by a scanning scheme for scanning the ion beam 3 , e.g. B. can be realized by means of at least one and in particular two scanning coils.

An xy extension of the beam interaction area 10 , ie the diameter of the focus of the ion in the object field 4 , can be less than 1 nm and in particular less than 0.5 nm.

The beam current can be less than 20 pA and can be less than 9 pA. Such a small beam current gives the possibility of a very high spatial resolution of the detailed check.

5 and 6 show an anvil-like structure of the object 6 before a milling step ( 5 ), ie before an interaction of the ion beam 3 with the object 6 , and after such milling steps ( 6 ) with an increased spatial resolution.

In 6 Milling is shown in three linear sections “1”, “2” and “3” with a longitudinal extent of approximately 3 µm and a lateral extent of approximately 200 nm.

7 shows the milled sections "1", "2" and "3" again 6 , now highlighted.

8th to 10 show in a diagram similar to that 4 the count rates for ion energies corresponding to the elements selenium (Se), tellurium (Te) and antimony (Sb) measured by the secondary electron detection unit 12 of the inspection system 1 during the detailed review of the quality assessment volume candidates, ie the subareas "1", "2" and "3", in the rough review step, ie during the electron microscopy imaging 5 , be identified.

8th shows the time-resolved count rate for sub-area "1". Such a CPS result shows a relatively high proportion of selenium, together with small proportions close to the resolution limit of tellurium and antimony.

9 shows the results of subarea “2” with small proportions of all three elements, selenium, tellurium and antimony. Selenium levels in the CPS measurement according to 9 start with the ion beam for longer milling times 3 to occur, which indicates that in the subarea “2” selenium is not present directly on the surface but below the surface.

10 shows the time-resolved count rate measured in sub-area "3". Selenium and tellurium are present near the resolution limit. No trace of antimony can be found in section "3".

The same as above with particular reference to 3 to 10 The inspection method described can be integrated during production of the semiconductor structure of the object 6 be performed. Examples of a projection lithography exposure method for producing semiconductor structures in the micrometer or nanometer range are shown in DE 10 2016 201 317 A1 and DE 10 2017 210 162 A1 and given the references cited there. After an editing step, the respective three-dimensional structure is created, that in the object field 4 the projection exposure device is produced and then integrated (in situ) by means of the inspection system described above 1 can be checked. Production errors, in particular systematic production errors, can then be detected during the manufacturing process. Countermeasures are therefore possible to reduce such manufacturing defects during the production process itself, thereby reducing a loss.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 2007/0221843 A1 [0002, 0024, 0029]
• DE 102016201317 A1 [0067]
• DE 102017210162 A1 [0067]

Claims (12)

Inspection system (1) for quality assessment of semiconductor structures - with an ion beam source (2) for spatially resolved exposure of the structures, which can be qualitatively assessed with an ion beam (3), - With a secondary ion detection device (12), - The secondary ion detection device (12) includes a mass spectrometer (13), - The mass spectrometer (13) is designed to measure an ion mass-to-charge ratio in a given bandwidth. Inspection system according to Claim 1 , The mass spectrometer (13) being designed for the continuous measurement of the ion mass to charge ratio in the given bandwidth. Inspection system according to Claim 1 or 2 wherein the secondary ion detection device (12) includes a secondary electron detection unit (19). Inspection system according to one of the Claims 1 to 3 , wherein the ion beam source (2) generates a noble gas ion beam (3). Inspection system according to Claim 4 , wherein the ion beam source (2) generates a neon ion beam. Inspection system according to one of the Claims 1 to 5 , wherein the secondary ion detection device (12) includes a secondary ion transfer unit (20) which can be shifted between - a first transfer position in which the transfer unit (20) secondary ions (7, 9) originating from a target volume of a probe structure to be assessed qualitatively to the Secondary ion detection unit (19 transferred, - a second, neutral position. Inspection system according to one of the Claims 3 to 6 , wherein the secondary ion detection unit (19) contains a total ion counter. Inspection system according to one of the Claims 3 to 7 , wherein the secondary ion detection unit (19) includes an extensive detector array for mass filtered signals. Inspection procedure for quality assessment of semiconductor structures, which includes the following steps: - rough check of the structure to be assessed qualitatively, - in-depth review of quality assessment volume candidates identified in the rough review step - spatially resolved ion beam sputtering in the volume to be checked in detail, - Detection of secondary ions (7, 9) from the volume to be checked in detail, - Carrying out a continuous mass spectrometry of the detected secondary ions. Inspection procedure after Claim 9 , where a lateral spatial resolution is better than 100 nm. Inspection procedure after Claim 9 or 10 , the ion beam being focused in the volume to be checked in detail with a focal diameter which is smaller than 5 nm. Inspection procedure according to one of the Claims 9 to 11 , the inspection being carried out integrated during a semiconductor production.

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