CN207020390U - One kind scanning particle beam microscopy system - Google Patents
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- CN207020390U CN207020390U CN201720883782.7U CN201720883782U CN207020390U CN 207020390 U CN207020390 U CN 207020390U CN 201720883782 U CN201720883782 U CN 201720883782U CN 207020390 U CN207020390 U CN 207020390U
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Abstract
The utility model discloses one kind to scan particle beam microscopy system, including：Scan particle beam microscopy and focus control system；The focus control system includes：Two illumination imaging devices, for producing illuminating bundle and transmission from the light beam of the carrying focusedimage of sample surfaces reflection；Two reflection units, for illuminating bundle caused by corresponding illumination imaging device to be reflexed into the sample surfaces and the light beam for the carrying focusedimage that the sample surfaces reflect is reflexed into the detection device；Two detection devices, for receiving the light beam from the carrying focusedimage of sample surfaces reflection, and detect the focusedimage that the light beam carries.
Description
Technical Field
The present invention relates to scanning particle beam microscopy, and more particularly to a scanning particle beam microscope system.
Background
Scanning particle Beam microscopes (SEM) and Focused Ion Beam (FIB) devices are increasingly used in modern manufacturing and scientific research.
The depth of field of the scanning particle beam microscope is in the range of nm to um, and is small especially under the condition of high resolution; when a sample is observed by a scanning particle beam microscope, if the change in the height of the surface of the sample exceeds the depth of field of the scanning particle beam microscope, the image cannot be clearly formed. The working distance of a scanning particle beam microscope is generally kept constant by adjusting the focusing of the electromagnetic lens of the scanning particle beam microscope.
However, since there is a hysteresis effect when adjusting the electromagnetic lens, the charged particle beam cannot be changed at once when adjusting the focusing of the electromagnetic lens by changing the current value of the electromagnetic lens due to the influence of the hysteresis feedback time. In addition, the distance between the microscope and the surface of the sample is not determined due to the uncertain height variation of the sample; therefore, the current value of the electromagnetic lens needs to be adjusted repeatedly to find an appropriate current value near the focusing current to determine the focusing current, so that the charged particle beam is refocused on the surface of the sample. Not only the time consumed by the adjusting process is long, but also the charged particle beams irradiate the sample for a long time, so that the sample is easy to be damaged; especially for non-conductive samples, charge accumulation effects tend to occur, affecting image quality.
In addition, when a sample is observed using a scanning particle beam microscope, it is desirable that the brightness and contrast of all images obtained in the entire observation range are kept uniform; therefore, it is necessary to ensure that the operating conditions of the charged particle beam remain unchanged throughout the detection process, i.e., that the focusing conditions of the charged particle beam and the energy of the charged particle beam do not change. Adjusting the focusing of the electromagnetic lens generally changes the focusing condition of the charged particle beam, which affects the uniformity of the image quality. Moreover, when the electromagnetic lens is adjusted to different current values, the rotation of the initial electron beam and the return signal electrons excited on the sample can be influenced by the change of the magnetic field, so that the observed image is rotated, and the complexity of image analysis is increased.
In the process of detecting the sample, the image consistency can be kept by adjusting the sample stage to keep the same distance (namely the working distance of the charged particle beam microscope or the height of the sample) with the electromagnetic lens all the time; however, the conventional charged particle beam microscope can only determine whether the working distance changes according to the definition of the image focusing, which not only takes a long time, but also has the defects that the determination standards are not uniform and the complexity of the determination standards is high.
SUMMERY OF THE UTILITY MODEL
In view of this, embodiments of the present invention are directed to a scanning particle beam microscope system, and the technical solution of the embodiments of the present invention is implemented as follows:
an embodiment of the utility model provides a scanning particle beam microscope system, include: a scanning particle beam microscope and a focus control system; wherein,
the focus control system includes:
two illumination imaging devices symmetrically located above the vacuum chamber of the scanning particle beam microscope and on the side of the charged particle optical column of the scanning particle beam microscope for generating illumination beams and transmitting beams carrying focused images reflected from the sample surface; the sample is located within the vacuum chamber;
two reflecting devices symmetrically positioned in the vacuum chamber and used for reflecting the illumination light beams generated by the corresponding illumination imaging devices to the surface of the sample and reflecting the light beams carrying the focused images reflected by the surface of the sample to the detecting device;
and the two detection devices are symmetrically positioned above the two illumination imaging devices and are used for receiving the light beams carrying the focused images reflected from the surface of the sample and detecting the focused images carried by the light beams.
An embodiment of the present invention provides another scanning particle beam microscope system, including: a scanning particle beam microscope and a focus control system; wherein,
the focus control system includes:
two illumination imaging devices symmetrically located above the vacuum chamber of the scanning particle beam microscope and on the side of the charged particle optical column of the scanning particle beam microscope for generating illumination beams and transmitting beams carrying focused images reflected from the sample surface; the sample is located within the vacuum chamber;
two reflecting devices symmetrically positioned in the vacuum chamber and used for reflecting the illumination light beams generated by the corresponding illumination imaging devices to the surface of the sample and reflecting the light beams carrying the focused images reflected by the surface of the sample to the detecting device;
the two detection devices are symmetrically positioned above the two illumination imaging devices and are used for receiving the light beams carrying the focused images reflected from the surface of the sample and detecting the focused images carried by the light beams;
and the focusing control device is used for processing the focusing image to obtain the distance attribute of the sample, and adjusting the position parameter of the sample according to the distance attribute to control the working distance of the scanning particle beam microscope.
In the above aspect, the scanning particle beam microscope includes: the device comprises a charged particle source for generating a charged particle beam, a charged particle optical column for focusing and deflecting the charged particle beam, and a vacuum chamber connected with the charged particle optical column.
In the above aspect, the illumination imaging apparatus includes:
a light source for generating an illumination beam;
a grating for forming a grating pattern of at least one shape;
a prism for directing the illumination beam to project the grating pattern to an imaging lens;
and the imaging lens is used for guiding the illumination light beam to be reflected by the reflecting device and then focusing the grating pattern on the surface of the sample.
In the above scheme, the imaging lens is further configured to guide the light beam carrying the focused image to project to the detection device.
In the above solution, two vacuum windows corresponding to the two illumination imaging devices are disposed at the top of the vacuum chamber, and the vacuum windows are used for allowing the illumination light beams to enter the vacuum chamber and allowing the light beams carrying the focused images to penetrate through the vacuum chamber.
In the above solution, the imaging lens at least includes a telecentric lens system for guiding the illumination beam to zoom and focus the grating pattern on the surface of the sample, and guiding the beam carrying the focused image to zoom and focus on the detecting device.
In the above aspect, the focus control device includes:
the processor is used for processing the sample focusing images at different distances to obtain the distance variation of the sample; the distance is the distance between the sample and the scanning particle beam microscope;
and the position adjusting component is used for adjusting the position parameters of the sample according to the distance variation.
Wherein the position adjustment assembly comprises at least 3 piezoceramic motors.
The embodiment of the present invention further provides a focusing control method, applied to a scanning particle beam microscope system, where the system generates two illumination beams having a symmetrical position relationship, including:
two beams of illuminating beams carrying the grating patterns are respectively contracted and focused to the surface of a sample, and are respectively amplified and focused for imaging after being reflected by the surface of the sample;
respectively detecting the focused grating images;
obtaining a distance attribute of the sample based on the focused image, and adjusting a position parameter of the sample according to the distance attribute.
In the above scheme, the illumination light beam is incident on the prism through the grating, and then the grating pattern is projected to the imaging lens;
after the illumination light beam passes through the imaging lens and the reflecting device, the grating pattern is subjected to zoom focusing to the surface of the sample;
and the focused image reflected from the surface of the sample is reflected by a reflecting device, passes through an imaging lens and is amplified and focused for imaging.
In the above scheme, the light beam carrying the focused image is emitted from the illumination imaging system and projected to the detection device, so that the detection device detects the focused image carried by the light beam.
In the foregoing solution, the obtaining a distance attribute of the sample based on the focused image and adjusting a position parameter of the sample according to the distance attribute includes:
processing the sample focusing images at different distances to obtain the distance variation of the sample; the distance is the distance between the sample and the scanning particle beam microscope;
and adjusting the position parameters of the sample according to the distance variation.
In the embodiment of the present invention, by adding an independent focusing control system outside the structure of the conventional scanning particle beam microscope, the focusing control system can acquire a focused image emitted from the surface of a sample, and based on the position of the focused image on the detection device of the focusing control system, it can be determined whether the horizontal position of the sample changes; the distance attribute of the sample is obtained by processing the focused image reflected by the surface of the sample, and the position parameter of the sample is adjusted according to the distance attribute so as to control the working distance of the scanning particle beam microscope, thereby realizing the consistency of the scanning image observed by the scanning charged particle beam microscope; the focusing control system adjusts the position parameters of the sample under the control of the computer, so that the adjustment precision is improved, and the observation time is shortened.
Drawings
FIG. 1 is a schematic diagram of a scanning particle beam microscope system according to an embodiment of the present invention;
fig. 2 is a schematic diagram of the working principle of the focus control system according to the embodiment of the present invention;
fig. 3 is a schematic diagram illustrating the detection of a sample by the focus control system when the sample is tilted according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a scanning particle beam microscope system according to another embodiment of the present invention;
fig. 5 is a schematic structural diagram of a scanning particle beam microscope system according to another embodiment of the present invention;
fig. 6 is a schematic structural diagram of a position adjustment assembly according to an embodiment of the present invention;
fig. 7 is a schematic processing flow diagram of a focus control method according to another embodiment of the present invention;
fig. 8 is a schematic flow chart of a scanning particle beam microscope for implementing focus control according to five embodiments of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example one
The embodiment of the present invention provides a scanning particle beam microscope system, the component structure of scanning particle beam microscope system, as shown in fig. 1, scanning particle beam microscope system includes: a scanning particle beam microscope and a focus control system for controlling the working distance of the scanning particle beam microscope.
In an embodiment of the present invention, the scanning particle beam microscope includes: a charged particle source 101, a charged particle optical column 103, and a vacuum chamber 140.
The charged particle beam generated by the charged particle source 101 is focused and deflected by the charged particle optical column 103, and then enters the vacuum chamber 140.
In an embodiment of the present invention, the focus control system includes: the first illumination imaging device 11, the second illumination imaging device 12, the first reflection device 115, the second reflection device 125, the second detection device 120 and the focus control device 130.
The first illumination imaging device 11 is located above the vacuum chamber of the scanning particle beam microscope and on the side of the charged particle optical column 103, and is used for generating an illumination beam.
The first illumination imaging device 11 includes: the optical system includes a first light source 110, a first grating 112, a first prism 111, and a first imaging lens 113.
The illumination light beam generated by the first light source 110 is projected to the first grating 112 to form a grating pattern, and then the transmission direction of the illumination light beam is changed by the first prism 111; the first prism 111 is used for guiding the illumination light beam to project the first grating 112 image to the first imaging lens 113; the first imaging lens 113 directs the illumination beam to be reflected by the first reflecting device 115, and then focuses the grating pattern onto the surface of the sample 141; the sample 141 is placed on a sample stage 142 within the vacuum chamber 140.
In a preferred embodiment, the first reflecting means 115 is equipped with an adjustable angle system, by means of which the first reflecting means 115 is adjusted to an angle between the illumination beam reflected onto the sample 141 and the sample 141 of less than 15 ° in order to ensure a high degree of measurement sensitivity; the function performed by the first reflecting means 115 may be performed by a mirror.
Here, a first vacuum window 114 and a second vacuum window 124 are provided on the top of the vacuum chamber 140, and the illumination beam enters the vacuum chamber 140 through the first vacuum window 114 and then is irradiated to the first reflecting device 115; the light beam carrying the focused image is irradiated to the second illumination imaging device 12 after passing through the second vacuum window 124; the first reflecting device 115 reflects the illuminating light beam generated by the first illumination imaging device 11 to the surface of the sample 141, and the illuminating light beam is reflected on the surface of the sample 141 to form a light beam carrying a focused image; the light beam carrying the focused image enters the second illumination imaging device 12 after being reflected by the second reflection device 125.
The second illumination imaging apparatus 12 includes: a second imaging lens 123; therefore, the light beam carrying the focused image is irradiated to the second imaging lens 123 after passing through the second vacuum window 124; the second imaging lens 123 directs the light beam carrying the focused image to be focused on the second detecting device 120.
The second detecting device 120 is located above the second illumination imaging device 12, and is used for detecting the focused image carried by the light beam. The focus control device 130 processes the focused image to obtain a distance attribute of the sample, and adjusts a position parameter of the sample according to the distance attribute to control a working distance of the scanning particle beam microscope. Specifically, the position parameter of the sample 141 can be adjusted by adjusting the movement of the sample stage 142 carrying the sample 141.
In a specific embodiment, the focus control device 130 is configured to process focused images of samples at different distances to obtain a distance variation of the sample 141; the distance is the distance between the sample 141 and the scanning particle beam microscope, and the position parameter of the sample 141 is adjusted according to the distance variation.
In one embodiment, each optical element in the first illumination and imaging device 11 can be cured into a module with an adjusting device, which can facilitate adjustment of optical parameters outside the vacuum chamber 140 and adapt to different working distances of the scanning particle beam microscope by adjusting the Z-direction height of the module.
In a preferred embodiment, the function of the first Light source 110 can be implemented by a Light Emitting Diode (LED). The first grating 112 may be a grating structure comprising a variety of shapes. The first imaging lens 113 is a telecentric lens system and can adapt to different module Z-direction heights, so as to improve the tolerance of the first illumination imaging device 11.
In a preferred embodiment, the second reflecting device 125 is provided with an adjustable angle system, and in order to ensure high measurement sensitivity, the inclination angle of the second reflecting device 125 is adjusted by the adjustable angle system, so that the angles between the first reflecting device 115 and the second reflecting device 125 and the surface of the sample 141 are consistent. The function performed by the second reflecting means 125 may be performed by a mirror.
In the embodiment of the present invention, the focused image reflected from the surface of the sample 141 is focused by the second imaging lens to the imaging position on the second detecting device 120 is related to the surface height of the sample 141. Specifically, the working principle of the focusing control system is schematically illustrated, as shown in fig. 2, if there is a protrusion on the surface of the sample 141, the height of the sample 141 changes in the direction of the vector 200; according to the optical imaging principle, the position of the focus pattern forming the image on the second detection device 120 is moved in the direction of the vector 210.
Meanwhile, the imaging position of the focused image reflected from the surface of the sample 141 focused on the second detecting device 120 is related to the inclination of the surface of the sample 141, as shown in fig. 3, when the inclination angle between the sample table 142 or the surface of the sample 141 and the horizontal plane is α, the angle between the illumination beam reflected from the surface of the sample 141 detected by the second detecting device 120 and the reflected beam 126 detected when the sample 141 is horizontally placed is 2 α according to the optical imaging principle, and therefore, the position of the focused image on the second detecting device 120 is also shifted.
It should be noted that, in the embodiment of the present invention, the first illumination imaging device 11 is located on the left side of the optical lens barrel 103, and the second illumination imaging device 12 and the second detection device 120 are located on the right side of the optical lens barrel 103. In another embodiment, the first illumination imaging device 11 may be located at the right side of the optical lens barrel 103, and the second illumination imaging device 12 and the second detection device 120 may be located at the left side of the optical lens barrel 103.
Example two
Because the inclination of the sample or the sample stage in the first embodiment of the present invention also causes the position of the focused image on the detector to shift, the second embodiment of the present invention provides another scanning particle beam microscope system, which can avoid the problem of inaccurate detection result caused by the inclination of the sample or the sample stage in the first embodiment; the composition structure of the scanning particle beam microscope system, as shown in fig. 4, includes: a scanning particle beam microscope and a focus control system for controlling the working distance of the scanning particle beam microscope.
In an embodiment of the present invention, the scanning particle beam microscope includes: a charged particle source 101, a charged particle optical column 103, and a vacuum chamber 140.
The charged particle beam generated by the charged particle source 101 is focused and deflected by the charged particle optical column 103, and then enters the vacuum chamber 140.
In an embodiment of the present invention, the focus control system includes: the first illumination imaging device 11, the third illumination imaging device 13, the first reflection device 115, the second reflection device 125, the first detection device 121, and the second detection device 120.
Wherein the first illumination imaging device 11 and the third illumination imaging device 13 are symmetrically positioned above the vacuum chamber 140 of the scanning particle beam microscope and on two sides of the optical column 103; the first illumination imaging device 11 and the third illumination imaging device 13 are used for generating illumination light beams and transmitting light beams carrying focused images reflected from the surface of the sample 141; the sample 141 is located inside the vacuum chamber 140.
The first illumination imaging device 11 includes: the optical system includes a first light source 110, a first grating 112, a first prism 111, and a first imaging lens 113.
The illumination light beam generated by the first light source 110 is projected to the first grating 112 to form a grating pattern, and then the transmission direction of the illumination light beam is changed by the first prism 111; the first prism 111 is used for guiding the illumination light beam to project the grating 112 pattern to the first imaging lens 113; the first imaging lens 113 directs the illumination beam to be reflected by the first reflecting device 115, and then focuses the grating pattern onto the surface of the sample 141; specifically, the raster pattern is focused on the surface of the sample 141 in a position of the optical axis 102 of the scanning particle beam microscope; the sample 141 is placed on a sample stage 142 within the vacuum chamber 140.
In a preferred embodiment, the first reflecting means 115 is equipped with an adjustable angle system, by means of which the first reflecting means 115 is adjusted to an angle between the illumination beam reflected onto the sample 141 and the sample 141 of less than 15 ° in order to ensure a high degree of measurement sensitivity; the function performed by the first reflecting means 115 may be performed by a mirror.
Here, a first vacuum window 114 is provided on the top of the vacuum chamber 140, and the illumination beam enters the vacuum chamber 140 through the first vacuum window 114 and then is irradiated to the first reflecting device 115; the light beam carrying the focused image is irradiated to the third illumination imaging device 13 after passing through the second vacuum window 124.
The first reflecting device 115 reflects the illuminating light beam generated by the first illumination imaging device 11 to the surface of the sample 141, and the illuminating light beam is reflected on the surface of the sample 141 to form a light beam carrying a focused image; the light beam carrying the focused image enters the third illumination imaging device 13 after being reflected by the second reflection device 125.
The third illumination imaging device 13 includes: a second imaging lens 123, a second prism 127, a second grating 122, and a second light source 126; therefore, the light beam carrying the focused image is irradiated to the second imaging lens 123 after passing through the second vacuum window 124; the second imaging lens 123 guides the light beam carrying the focused image to pass through the second prism 127 and then project the light beam to the second detection device 120.
The second detecting device 120 is located above the second illumination imaging device 12, and is used for detecting the focused image carried by the light beam.
Based on the above description of the scanning particle beam microscope system, it can be seen that, after the illumination beam generated by the first light source 110 in the first illumination imaging device 11 passes through the first imaging lens 113 and the first reflection device 115, the illumination beam is reduced and focused on the surface of the sample by the grating pattern generated by the first grating 112, so as to generate a focused image; that is, the illumination beam is reflected on the surface of the sample 141 to form a beam carrying a focused image; the light beam carrying the focused image enters the third illumination imaging device 13 after being reflected by the second reflection device 125. The light beam carrying the focused image is irradiated to the second imaging lens 123 after passing through the second vacuum window 124; the second imaging lens 123 guides the light beam carrying the focused image to pass through the second prism 127 to be magnified and focused on the second detection device 120.
Based on the scanning particle beam microscope system of the embodiment of the utility model, another light beam transmission line is also simultaneously arranged; specifically, the illumination beam generated by the second light source 126 in the third illumination imaging device 13 is projected to the second grating 122 to form a grating pattern, the transmission direction of the illumination beam is changed by the second prism 127, and the illumination beam is guided by the second imaging lens 123 and the second reflecting device 125 to zoom and focus the grating pattern on the surface of the sample 141 to generate a focused image; the light beam carrying the focused image is reflected by the first reflecting device 115 and enters the first illumination imaging device 11. The light beam carrying the focused image passes through the first vacuum window 114 and then irradiates the first imaging lens 113; the first imaging lens 113 guides the light beam carrying the focused image to pass through the first prism 111 and then to be magnified and focused on the first detection device 121.
In one embodiment, each optical element in the first illumination and imaging device 11 can be cured into a module with an adjusting device, which can facilitate adjustment of optical parameters outside the vacuum chamber 140 and adapt to different working distances of the scanning particle beam microscope by adjusting the Z-direction height of the module.
In a preferred embodiment, the Light source 110 may be implemented by a Light Emitting Diode (LED). The grating 112 may be a grating structure comprising a variety of shapes. The first imaging lens 113 is a telecentric lens system and can adapt to different module Z-direction heights, so as to improve the tolerance of the first illumination imaging device 11.
In a preferred embodiment, the second reflecting device 125 is provided with an adjustable angle system, and the function performed by the second reflecting device 125 can be performed by a mirror. Meanwhile, the first reflecting device 115 and the second reflecting device 125 are symmetrically arranged about the optical axis 102 of the scanning particle beam microscope, and the angles of the first reflecting device 115 and the second reflecting device 125 with the surface of the sample 141 are consistent.
In the embodiment of the present invention, two bundles of illumination imaging light beams are transmitted along the symmetrical path, and therefore, taking one of the light beam transmission paths as an example, the focused image reflected from the surface of the sample 141 is focused by the second imaging lens to the imaging position on the second detecting device 120 is related to the surface height of the sample 141. Specifically, the schematic diagram of the focus control system, as shown in fig. 2, if there is a protrusion on the surface of the sample 141, the height of the sample 141 changes in the direction of the vector 200; according to the optical imaging principle, the position of the focus pattern forming the image on the second detection device 120 is moved in the direction of the vector 210.
Meanwhile, the imaging position of the focused image reflected from the surface of the sample 141 focused on the second detecting device 120 is related to the inclination of the surface of the sample 141, as shown in fig. 3, when the inclination angle between the sample table 142 or the surface of the sample 141 and the horizontal plane is α, the angle between the illumination beam reflected from the surface of the sample 141 detected by the second detecting device 120 and the reflected beam 126 detected when the sample 141 is horizontally placed is 2 α according to the optical imaging principle, and therefore, the position of the focused image on the second detecting device 120 is also shifted.
In the embodiment of the present invention, the first illumination imaging device 11 and the third illumination imaging device 13 are symmetrically located on both sides of the optical barrel 103 and the top of the vacuum chamber 140 with the optical axis of the scanning particle beam microscope as the center, the first detection device 121 is located above the first illumination imaging device 11, and the second detection device 120 is located above the third illumination imaging device 13, since the position relationship between the first illumination imaging device 11 and the third illumination imaging device 13 has symmetry, the position relationship between the first detection device 121 and the second detection device 120 also has symmetry.
Meanwhile, because the illumination imaging device in the embodiment of the present invention is located outside the vacuum chamber, the focus control system can be independently adjusted to adapt to different working distances of the scanning particle beam microscope.
EXAMPLE III
Because the inclination of the sample or the sample stage in the first embodiment of the present invention also causes the position of the focused image on the detector to shift, the third embodiment of the present invention provides another scanning particle beam microscope system, which can avoid the problem of inaccurate detection result caused by the inclination of the sample or the sample stage in the first embodiment; the composition structure of the scanning particle beam microscope system, as shown in fig. 5, includes: a scanning particle beam microscope and a focus control system for controlling the working distance of the scanning particle beam microscope.
In an embodiment of the present invention, the scanning particle beam microscope includes: a charged particle source 101, a charged particle optical column 103, and a vacuum chamber 140.
The charged particle beam generated by the charged particle source 101 is focused and deflected by the charged particle optical column 103, and then enters the vacuum chamber 140.
In an embodiment of the present invention, the focus control system includes: the first illumination imaging device 11, the third illumination imaging device 13, the first reflection device 115, the second reflection device 125, the first detection device 121, the second detection device 120 and the focus control device 130.
Wherein the first illumination imaging device 11 and the third illumination imaging device 13 are symmetrically positioned above the vacuum chamber 140 of the scanning particle beam microscope and on two sides of the optical column 103; the first illumination imaging device 11 and the third illumination imaging device 13 are used for generating illumination light beams and transmitting light beams carrying focused images reflected from the surface of the sample 141; the sample 141 is located inside the vacuum chamber 140.
The first illumination imaging device 11 includes: the optical system includes a first light source 110, a first grating 112, a first prism 111, and a first imaging lens 113.
The illumination light beam generated by the first light source 110 is projected to the first grating 112 to form a grating pattern, and then the transmission direction of the illumination light beam is changed by the first prism 111; the first prism 111 is used for guiding the illumination light beam to project the grating 112 pattern to the first imaging lens 113; the first imaging lens 113 directs the illumination beam to be reflected by the first reflecting device 115, and then focuses the grating pattern onto the surface of the sample 141; specifically, the raster pattern is focused on the surface of the sample 141 in a position of the optical axis 102 of the scanning particle beam microscope; the sample 141 is placed on a sample stage 142 within the vacuum chamber 140.
In a preferred embodiment, the first reflecting means 115 is equipped with an adjustable angle system, by means of which the first reflecting means 115 is adjusted to an angle between the illumination beam reflected onto the sample 141 and the sample 141 of less than 15 ° in order to ensure a high degree of measurement sensitivity; the function performed by the first reflecting means 115 may be performed by a mirror.
Here, a first vacuum window 114 is provided on the top of the vacuum chamber 140, and the illumination beam enters the vacuum chamber 140 through the first vacuum window 114 and then is irradiated to the first reflecting device 115; the light beam carrying the focused image is irradiated to the third illumination imaging device 13 after passing through the second vacuum window 124.
The first reflecting device 115 reflects the illuminating light beam generated by the first illumination imaging device 11 to the surface of the sample 141, and the illuminating light beam is reflected on the surface of the sample 141 to form a light beam carrying a focused image; the light beam carrying the focused image enters the third illumination imaging device 13 after being reflected by the second reflection device 125.
The third illumination imaging device 13 includes: a second imaging lens 123, a second prism 127, a second grating 122, and a second light source 126; therefore, the light beam carrying the focused image is irradiated to the second imaging lens 123 after passing through the second vacuum window 124; the second imaging lens 123 guides the light beam carrying the focused image to pass through the second prism 127 and then project the light beam to the second detection device 120.
The second detecting device 120 is located above the second illumination imaging device 12, and is used for detecting the focused image carried by the light beam. The focus control device 130 processes the focused image to obtain a distance attribute of the sample, and adjusts a position parameter of the sample according to the distance attribute to control a working distance of the scanning particle beam microscope.
Specifically, the focus control device 130 includes a processor 131 and a position adjusting component 132, the processor 131 can process the focused images of the samples with different working distances to obtain the distance variation of the samples, and the position adjusting component 132 adjusts the position of the samples according to the distance variation. When the position of the sample is adjusted, the position parameter of the sample 141 can be adjusted by adjusting the movement of the sample stage 142 carrying the sample 141; for example, the position of the sample is adjusted by adjusting the horizontal X or Y movement of the sample stage 142 carrying the sample 141, or adjusting a Z-direction adjusting device such as a piezoelectric ceramic motor.
In a preferred embodiment, the structure of the position adjustment assembly 132, as shown in fig. 6, includes an XY plane adjustment device 401 and at least one Z-direction adjustment device 402; when the position adjusting assembly 132 comprises a point Z-direction adjusting device, only the height of the sample stage 142 can be adjusted; when the position adjusting assembly 132 comprises a Z-direction adjusting device with more than three points, not only the height of the sample stage 142 can be adjusted, but also the inclination angle of the sample stage 142 can be adjusted; wherein, the function of the Z-direction adjusting device can be realized by a piezoelectric ceramic motor.
Based on the above description of the scanning particle beam microscope system, it can be seen that, after the illumination beam generated by the first light source 110 in the first illumination imaging device 11 passes through the first imaging lens 113 and the first reflection device 115, the illumination beam is reduced and focused on the surface of the sample by the grating pattern generated by the first grating 112, so as to generate a focused image; that is, the illumination beam is reflected on the surface of the sample 141 to form a beam carrying a focused image; the light beam carrying the focused image enters the third illumination imaging device 13 after being reflected by the second reflection device 125. The light beam carrying the focused image is irradiated to the second imaging lens 123 after passing through the second vacuum window 124; the second imaging lens 123 guides the light beam carrying the focused image to pass through the second prism 127 to be magnified and focused on the second detection device 120.
Based on the scanning particle beam microscope system of the embodiment of the utility model, another light beam transmission line is also simultaneously arranged; specifically, the illumination beam generated by the second light source 126 in the third illumination imaging device 13 is projected to the second grating 122 to form a grating pattern, the transmission direction of the illumination beam is changed by the second prism 127, and the illumination beam is guided by the second imaging lens 123 and the second reflecting device 125 to zoom and focus the grating pattern on the surface of the sample 141 to generate a focused image; the light beam carrying the focused image is reflected by the first reflecting device 115 and enters the first illumination imaging device 11. The light beam carrying the focused image passes through the first vacuum window 114 and then irradiates the first imaging lens 113; the first imaging lens 113 guides the light beam carrying the focused image to pass through the first prism 111 and then to be magnified and focused on the first detection device 121.
In a specific embodiment, the focus control device 130 is configured to process focused images of samples at different distances to obtain a distance variation of the sample 141; the distance is the distance between the sample 141 and the scanning particle beam microscope, and the position parameter of the sample 141 is adjusted according to the distance variation.
In one embodiment, each optical element in the first illumination and imaging device 11 can be cured into a module with an adjusting device, which can facilitate adjustment of optical parameters outside the vacuum chamber 140 and adapt to different working distances of the scanning particle beam microscope by adjusting the Z-direction height of the module.
In a preferred embodiment, the Light source 110 may be implemented by a Light Emitting Diode (LED). The grating 112 may be a grating structure comprising a variety of shapes. The first imaging lens 113 is a telecentric lens system and can adapt to different module Z-direction heights, so as to improve the tolerance of the first illumination imaging device 11.
In a preferred embodiment, the second reflecting device 125 is provided with an adjustable angle system, and the function performed by the second reflecting device 125 can be performed by a mirror. Meanwhile, the first reflecting device 115 and the second reflecting device 125 are symmetrically arranged about the optical axis 102 of the scanning particle beam microscope, and the angles of the first reflecting device 115 and the second reflecting device 125 with the surface of the sample 141 are consistent.
In the embodiment of the present invention, two bundles of illumination imaging light beams are transmitted along the symmetrical path, and therefore, taking one of the light beam transmission paths as an example, the focused image reflected from the surface of the sample 141 is focused by the second imaging lens to the imaging position on the second detecting device 120 is related to the surface height of the sample 141. Specifically, the schematic diagram of the focus control system, as shown in fig. 2, if there is a protrusion on the surface of the sample 141, the height of the sample 141 changes in the direction of the vector 200; according to the optical imaging principle, the position of the focus pattern forming the image on the second detection device 120 is moved in the direction of the vector 210.
Meanwhile, the imaging position of the focused image reflected from the surface of the sample 141 focused on the second detecting device 120 is related to the inclination of the surface of the sample 141, as shown in fig. 3, when the inclination angle between the sample table 142 or the surface of the sample 141 and the horizontal plane is α, the angle between the illumination beam reflected from the surface of the sample 141 detected by the second detecting device 120 and the reflected beam 126 detected when the sample 141 is horizontally placed is 2 α according to the optical imaging principle, and therefore, the position of the focused image on the second detecting device 120 is also shifted.
In the embodiment of the present invention, the first illumination imaging device 11 and the third illumination imaging device 13 are symmetrically located on both sides of the optical lens barrel 103 and the top of the vacuum chamber 140 with the optical axis of the scanning particle beam microscope as the center, the first detection device 121 is located above the first illumination imaging device 11, and the second detection device 120 is located above the third illumination imaging device 13, since the positional relationship between the first illumination imaging device 11 and the third illumination imaging device 13 has symmetry, the positional relationship between the first detection device 121 and the second detection device 120 also has symmetry, in summary, it can be seen that the third embodiment of the present invention is a symmetrical structure, and the transmission process of the two illumination light beams generated by the first illumination imaging device 11 and the third illumination imaging device 13 also has symmetry, therefore, when the inclination angle between the sample surface or the sample stage and the horizontal plane is α, the deviation directions of the images detected by the first detection device 121 and the second detection device 120 are opposite and the deviation amounts are the same, and when the height of the sample 141 changes, the deviation directions of the images of the first detection device 121 and the second detection device 120 are the sample stage 121 and the deviation amounts of the sample stage are the symmetrical scanning particle beam microscope, so that the scanning particle beam vector distribution can be calculated by the method.
Meanwhile, because the illumination imaging device in the embodiment of the present invention is located outside the vacuum chamber, the focus control system can be independently adjusted to adapt to different working distances of the scanning particle beam microscope.
Example four
Based on the scanning particle beam microscope system, a processing flow diagram of the method is shown in fig. 7, and the method is applied to the scanning particle beam microscope system of the second embodiment, which generates two illumination beams having a symmetrical position relationship, and includes the following steps:
s101, two beams of illumination light beams carrying grating images are respectively reduced in times and focused on the surface of a sample, and are respectively amplified, focused and imaged after being reflected by the sample;
specifically, after an illumination light beam generated by a light source such as an LED enters a prism through a grating, the grating image is projected to an imaging lens; and after passing through the imaging lens and the reflecting device, the illumination light beam zooms and focuses the grating pattern on the surface of the sample to form a focused image.
Step S102, respectively detecting the focused grating images;
specifically, the light beam carrying the focused image is reflected by the reflection device and is magnified and focused by the imaging lens, and then is detected by the detection device.
Here, the detecting means may be a CCD camera or the like.
Step S103, obtaining a distance attribute of the sample based on the focused image, and adjusting a position parameter of the sample according to the distance attribute;
specifically, sample focusing images at different distances are processed to obtain distance variation of the sample; the distance is the distance between the sample and the scanning particle beam microscope; and adjusting the position parameters of the sample according to the distance variation.
When the position parameter of the sample is adjusted, the position parameter of the sample can be adjusted by adjusting the movement of a sample stage bearing the sample; for example, the position of the sample is adjusted by adjusting the horizontal X or Y movement of a sample stage for carrying the sample, or adjusting a Z-direction adjusting device such as a piezoelectric ceramic motor.
EXAMPLE five
Based on the scanning particle beam microscope system, the fifth embodiment of the present invention provides a method for implementing focus control of a scanning particle beam microscope, the processing flow diagram of the method is shown in fig. 8, the method is applied to the scanning particle beam microscope system of the second embodiment, the system generates two illumination beams with symmetrical position relationship, and the method includes the following steps:
step S201, initializing setting;
specifically, the working distance of the illumination imaging device is set according to the working distance of the known scanning particle beam microscope, and the angle of the reflecting device is adjusted, so that a focused image formed on the surface of a sample is at the position of the optical axis 102 of the scanning particle beam microscope.
Step S202, judging whether the focused image is clear, and if so, executing step S203; when the determination result is no, step S204 is executed.
In step S203, the sample is observed by a scanning particle beam microscope.
Step S204, adjusting the working distance of the illumination imaging device and the working distance of the detection device;
here, by adjusting the working distance of the illumination imaging device and the working distance of the detection device, a clear focused image can be observed.
Step S205, judging whether the detected image is clear or not or whether no displacement exists; if yes, executing step S203; when the determination result is no, step S206 is executed.
Step S206, calculating the position variation of the sample to obtain a calculation result;
here, specifically, in the process of observing the sample, when the surface height of the sample changes and even exceeds the depth of field of the scanning particle beam microscope, the position of the obtained grating image detected by the detection device shifts or the imaging is not clear; at this time, the amount of change in the sample position is calculated by the computer from the amount of change in the grating image position.
Step S207, adjusting the position of the sample based on the calculation result;
specifically, according to the calculated position change value of the sample, the position parameter of the sample can be adjusted by controlling and adjusting the movement of a sample stage bearing the sample through a computer; adjusting the sample height and inclination by adjusting a Z-direction adjusting device such as a piezoelectric ceramic motor, and resuming the operation of the scanning particle beam microscope until the image is clear, thereby continuing to execute step S203 for observing the sample by using the scanning particle beam microscope.
The whole automatic focusing process of the scanning particle beam microscope is a process of adjustment, observation, feedback and adjustment, the image quality is ensured to be consistent, the adjustment precision of the sample is improved, and the observation time of the sample is shortened.
The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (14)
1. A scanning particle beam microscope system, comprising: a scanning particle beam microscope and a focus control system; wherein,
the focus control system includes:
two illumination imaging devices symmetrically located above the vacuum chamber of the scanning particle beam microscope and on the side of the charged particle optical column of the scanning particle beam microscope for generating illumination beams and transmitting beams carrying focused images reflected from the sample surface; the sample is located within the vacuum chamber;
two reflecting devices symmetrically positioned in the vacuum chamber and used for reflecting the illumination light beams generated by the corresponding illumination imaging devices to the surface of the sample and reflecting the light beams carrying the focused images reflected by the surface of the sample to the corresponding detection devices;
and the two detection devices are symmetrically positioned above the two illumination imaging devices and are used for receiving the light beams carrying the focused images reflected from the surface of the sample and detecting the focused images carried by the light beams.
2. The system of claim 1, wherein the scanning particle beam microscope comprises: the device comprises a charged particle source for generating a charged particle beam, a charged particle optical column for focusing and deflecting the charged particle beam, and a vacuum chamber connected with the charged particle optical column.
3. The system of claim 1, wherein the illumination imaging device comprises:
a light source for generating an illumination beam;
a grating for forming a grating pattern of at least one shape;
a prism for directing the illumination beam to project the grating pattern to an imaging lens;
and the imaging lens is used for guiding the illumination light beam to be reflected by the reflecting device and then focusing the grating pattern on the surface of the sample.
4. The system of claim 3, wherein the imaging lens is further configured to direct the beam of light carrying the focused image to project to the detection device.
5. The system of claim 1, wherein the vacuum chamber is provided at the top with two vacuum windows corresponding to the two illumination imaging devices, respectively, for allowing the illumination beam to enter the vacuum chamber and the focused image carrying beam to pass through the vacuum chamber.
6. The system of claim 4, wherein the imaging lens comprises at least one telecentric lens system for directing the illumination beam to demagnify focus the grating pattern onto the sample surface and for directing the focused image-carrying beam to magnify focus onto the detection device.
7. A scanning particle beam microscope system, comprising: a scanning particle beam microscope and a focus control system; wherein,
the focus control system includes:
two illumination imaging devices symmetrically located above the vacuum chamber of the scanning particle beam microscope and on the side of the charged particle optical column of the scanning particle beam microscope for generating illumination beams and transmitting beams carrying focused images reflected from the sample surface; the sample is located within the vacuum chamber;
two reflecting devices symmetrically positioned in the vacuum chamber and used for reflecting the illumination light beams generated by the corresponding illumination imaging devices to the surface of the sample and reflecting the light beams carrying the focused images reflected by the surface of the sample to the corresponding detection devices;
the two detection devices are symmetrically positioned above the two illumination imaging devices and are used for receiving the light beams carrying the focused images reflected from the surface of the sample and detecting the focused images carried by the light beams;
and the focusing control device is used for processing the focusing image to obtain the distance attribute of the sample, and adjusting the position parameter of the sample according to the distance attribute to control the working distance of the scanning particle beam microscope.
8. The system of claim 7, wherein the scanning particle beam microscope comprises: the device comprises a charged particle source for generating a charged particle beam, a charged particle optical column for focusing and deflecting the charged particle beam, and a vacuum chamber connected with the charged particle optical column.
9. The system of claim 7, wherein the illumination imaging device comprises:
a light source for generating an illumination beam;
a grating for forming a grating pattern of at least one shape;
a prism for directing the illumination beam to project the grating pattern to an imaging lens;
and the imaging lens is used for guiding the illumination light beam to be reflected by the reflecting device and then focusing the grating pattern on the surface of the sample.
10. The system of claim 9, wherein the imaging lens is further configured to direct the focused image carrying beam to project to the detection device.
11. The system of claim 7, wherein the vacuum chamber is provided at the top with two vacuum windows corresponding to the two illumination imaging devices, respectively, for allowing the illumination beam to enter the vacuum chamber and the focused image carrying beam to pass through the vacuum chamber.
12. The system of claim 10, wherein the imaging lens comprises at least one telecentric lens system for directing the illumination beam to demagnify focus the grating pattern onto the sample surface and for directing the focused image-carrying beam to magnify focus onto the detection device.
13. The system of claim 7, wherein the focus control device comprises:
the processor is used for processing the sample focusing images at different distances to obtain the distance variation of the sample; the distance is the distance between the sample and the scanning particle beam microscope;
and the position adjusting component is used for adjusting the position parameters of the sample according to the distance variation.
14. The system of claim 13, wherein the position adjustment assembly comprises at least three piezo ceramic motors.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107329246A (en) * | 2017-07-20 | 2017-11-07 | 聚束科技（北京）有限公司 | One kind scanning particle beam microscopy system and focusing controlling method |
| CN110223901A (en) * | 2018-03-01 | 2019-09-10 | Fei 公司 | Difference imaging technique in scanning transmission charged particle microscope |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107329246A (en) * | 2017-07-20 | 2017-11-07 | 聚束科技（北京）有限公司 | One kind scanning particle beam microscopy system and focusing controlling method |
| CN110223901A (en) * | 2018-03-01 | 2019-09-10 | Fei 公司 | Difference imaging technique in scanning transmission charged particle microscope |
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