Needle point support and scanning tunneling microscope

Abstract

The utility model provides a pinpoint holder and a scanning tunneling microscope, the pinpoint holder comprises a fixing frame, the fixing frame comprises an exposed surface and a first mounting surface which are opposite to each other, and a fixing piece and a bearing piece which sequentially extend between the exposed surface and the first mounting surface, the periphery of the bearing part extends to the outer side of the fixing part to form a mounting part, the side face, opposite to the first mounting face, of the mounting part is a second mounting face, and a needle hole extending towards the first mounting face is formed in the exposed face; the fastening piece is connected with the fixing frame, and the fastening piece is arranged to be suitable for moving in the needle hole in the radial direction of the needle hole; and a hard insulating member. According to the needle point support and the scanning tunneling microscope, the scanning probes of different specifications are inserted into the needle holes, and the fasteners are operated to move in the radial direction of the needle holes, so that the scanning probes in the needle holes are extruded and limited, and the scanning probes of different specifications are rapidly fixed.

Description

Technical Field

[0001] The utility model relates to the technical field of vacuum equipment, in particular to a needle tip holder and a scanning tunneling microscope. Background Art

[0002] Scanning tunneling microscope (STM) uses the tunneling principle of quantum mechanics to obtain atomic-scale sample surface morphology information and local electron state density by scanning the tunneling current between the probe and the sample being measured. It studies novel physical phenomena on the surface of materials and has shown important application value in fields such as quantum information, nanoelectronics, and biomedicine. The scanning head, as the core component of the STM, adjusts and fixes the position and angle of the probe through the needle tip holder to achieve accurate surface imaging and physical property measurement.

[0003] Currently, the tip holders used in STM scanners are primarily cylindrical, with an inner diameter larger than the probe diameter. This requires multiple manual bending of the probe tail to secure it to the inner wall of the cylindrical holder. The tip holder also has a fixed structure and cannot be adjusted to accommodate varying scanning probe specifications. The insufficient contact area between some scanning probes and the tip holder can lead to probes easily falling off when transferred between different chambers in the system, and can also introduce vibration noise during the scanner measurement process.

[0004] The existing needle tip holder requires additional conductive adhesive to connect the side end surface of the cylindrical needle tip holder to the scanning head base to transmit the tunneling current signal during the scanning process. The setting of the conductive adhesive increases the use cost of the needle tip holder and increases the installation time of the needle tip holder.

[0005] Therefore, in order to solve the above problems, the present invention proposes a tip holder and a scanning tunneling microscope that can be applied to the installation of scanning probes of different specifications, thereby reducing the use cost and installation time. Utility Model Content

[0006] In order to solve the problems that the existing needle tip holder is not suitable for installation of scanning probes of different specifications during use, has high use cost and takes a long time to install, the utility model provides a needle tip holder and a scanning tunneling microscope.

[0007] According to one purpose of the present invention, the present invention provides a needle tip holder, comprising:

[0008] a fixing frame, the fixing frame comprising an exposed surface and a first mounting surface facing each other, and a fixing member and a supporting member extending sequentially between the exposed surface and the first mounting surface, the peripheral edge of the supporting member extending outward from the fixing member to form a mounting portion, a side of the mounting portion opposite the mounting surface being a second mounting surface, and a pinhole extending toward the first mounting surface being formed on the exposed surface;

[0009] a fastener connected to the fixing frame, wherein the fastener is configured to move inside the needle hole along the radial direction of the needle hole;

[0010] A hard insulating member having a uniform thickness, and covering the second mounting surface.

[0011] Preferably, a fastening hole is opened on the outer side of the fixing piece, the fastening hole is connected to the pinhole, the axis of the fastening hole and the axis of the pinhole intersect, and the fastener is screwed into the fastening hole.

[0012] Preferably, the axis of the fastening hole is perpendicular to the axis of the pinhole, and the axis of the fastening hole intersects at the center position of the axis of the pinhole.

[0013] Preferably, the sum of the length of the fastening hole and the diameter of the pinhole is not greater than the length of the fastener.

[0014] Preferably, one side of the needle hole in the radial direction is the operating side, the fastener is arranged on the operating side of the fixing member, and the fixing member is arranged close to the operating side of the supporting member.

[0015] Preferably, the fixing member and the supporting member are integrally cast, and the bottom surface of the pinhole is configured to be in contact with a probe.

[0016] Preferably, the supporting member and the fixing member are bonded by vacuum adhesive, the bottom surface of the pinhole and the probe are spaced apart, and the probe, the pinhole side wall and the fastener are sequentially connected to form a tunneling current path.

[0017] Preferably, the outer side surface of the fixing member in the radial direction of the needle hole is a prism surface, and there are multiple prism surfaces, and each prism surface is correspondingly provided with at least one fastening hole.

[0018] Preferably, the insulating part is an insulating ceramic insulating part, and the insulating part is bonded to the second mounting surface by vacuum glue. A mounting hole is provided on the insulating part, and the outer edge of the insulating part is flush with the outer edge of the second mounting surface. A gap is reserved between the inner wall of the mounting hole on the insulating part and the inner edge of the mounting portion on the horizontal plane.

[0019] The utility model also provides a scanning tunneling microscope, comprising the above-mentioned needle tip holder, and further comprising:

[0020] A scanning head base, wherein a connecting surface is provided on the scanning head base, and the connecting surface is in contact with the first mounting surface;

[0021] A clamping member is connected to the scanning head base, the clamping member matches the supporting member, and the clamping member abuts against the insulating member.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. The needle tip holder and scanning tunneling microscope can insert scanning probes of different specifications into the needle hole, and operate the fastener to move in the radial direction of the needle hole to achieve extrusion and limit the scanning probe in the needle hole, thereby achieving rapid fixation of scanning probes of different specifications;

[0024] 2. The tip holder and scanning tunneling microscope have a support component that is larger than the fixing component, which increases the contact area between the tip holder and the scanning head base. This allows tunneling current signal transmission without the need for a conductive adhesive. Furthermore, the stability of the scanning probe is increased, effectively suppressing noise interference caused by mechanical vibration and thermal drift, thereby improving the quality of the STM scanning image.

[0025] 3. The needle tip holder and scanning tunneling microscope are fixed in the scanning head by insulating parts to avoid short circuits and ensure that the tunneling current can only flow through the scanning probe in the pinhole. Among them, the hard and uniform thickness insulating parts replace the traditional insulating glue, avoiding the problem of uneven application of the insulating glue.

[0026] The present invention is further described below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic cross-sectional view of a needle tip holder according to the present invention from one viewing angle;

[0028] Figure 2 The vibration noise level spectrum of different measurement frequencies of the needle tip holder described in the utility model when applied to a scanning tunneling microscope;

[0029] Figure 3 The present invention discloses an electrical noise level spectrum at different measurement frequencies when a needle tip holder is applied to a scanning tunneling microscope.

[0030] In the figure: 100, fixing frame; 100a, exposed surface; 100b, first mounting surface; 101, fixing member; 1011, fastening hole; 102, supporting member; 1021, mounting portion; 1021a, second mounting surface; 103, pinhole; 200, fastener; 300, insulating member; 301, mounting hole. DETAILED DESCRIPTION

[0031] The following description is intended to fully illustrate the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are provided for illustrative purposes only, and those skilled in the art will readily appreciate other obvious variations. The basic principles of the present invention as defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0032] See also Figure 1 The utility model provides a technical solution: a needle tip support, comprising:

[0033] A fixing frame 100 includes an exposed surface 100a and a first mounting surface 100b facing each other, and a fixing member 101 and a supporting member 102 extending sequentially between the exposed surface 100a and the first mounting surface 100b. The peripheral edge of the supporting member 102 extends outward from the fixing member 101 to form a mounting portion 1021. A side of the mounting portion 1021 opposite the first mounting surface 100b is a second mounting surface 1021a. A pinhole 103 is defined in the exposed surface 100a and extends toward the first mounting surface 100b.

[0034] A fastener 200 connected to the fixing frame 100, wherein the fastener 200 is configured to move inside the needle hole 103 along the radial direction of the needle hole 103;

[0035] The hard insulating member 300 has a uniform thickness and covers the second mounting surface 1021 a .

[0036] By inserting scanning probes of different specifications into the pinhole 103, the operating fastener 200 moves in the radial direction of the pinhole 103, thereby achieving extrusion and positioning of the scanning probe in the pinhole 103, and realizing rapid fixation of scanning probes of different specifications;

[0037] The size of the supporting member 102 is larger than that of the fixing member 101, which increases the contact area between the needle tip support and the scanning head base, and can achieve tunneling current signal transmission without conductive adhesive. At the same time, the stability of the scanning probe is increased, effectively suppressing noise interference caused by mechanical vibration and thermal drift, and improving the quality of STM scanning images.

[0038] The needle tip holder is fixed in the scanning head by the insulating part 300 to avoid short circuit, ensuring that the tunneling current can only flow through the scanning probe in the pinhole 103. Among them, the hard and uniform thickness insulating part 300 replaces the traditional insulating glue, avoiding the problem of uneven application of the insulating glue.

[0039] Regarding the specific connection structure between the fastener 200 and the fixing frame 100, a fastening hole 1011 is formed on the outer side of the fixing member 101. The fastening hole 1011 is connected to the pinhole 103, and the axis of the fastening hole 1011 intersects with the axis of the pinhole 103. Preferably, the inner wall of the fastening hole 1011 is provided with an internal thread, and the fastener 200 is screwed into the fastening hole 1011. During use, the fastener 200 can be rotated to move within the fastening hole 1011 along the axis of the fastening hole 1011. When the end of the fastener 200 enters the interior of the pinhole 103, the scanning probe in the pinhole 103 can be squeezed and positioned.

[0040] The axis of the fastening hole 1011 is perpendicular to the axis of the pinhole 103, and the sum of the length of the fastening hole 1011 and the diameter of the pinhole 103 is no greater than the length of the fastener 200. This ensures that when the fastener 200 moves within the fastening hole 1011 and the pinhole 103, one end of the fastener 200 is always located outside the fixing member 101, facilitating operation. In one embodiment, the fastener 200 is a bolt, and the screw head of the fastener 200 is located on the side of the fastener 200 facing away from the pinhole 103.

[0041] To ensure that the end of the fastener 200 can effectively squeeze the scanning probe located in the pinhole 103, the axis of the fastening hole 1011 intersects at the center position of the axis of the pinhole 103;

[0042] The diameter of the fastener 200 is not less than the diameter of the pinhole 103 .

[0043] Furthermore, a spring-loaded shock-absorbing pad is provided on the side of the fastener 200 near the pinhole 103. The side of the pad facing away from the fastener 200 is provided with an extrusion groove, which is arranged around the axis of the fastener 200. During use, the shock-absorbing pad at the end of the fastener 200 contacts the scanning probe in the pinhole 103. The shock-absorbing pad can exert an opposing force on the fastener 200 to improve the installation stability of the fastener 200. The extrusion groove on the shock-absorbing pad ensures that the shock-absorbing pad can squeeze and limit the scanning probe to a greater extent during the rotation process.

[0044] The fixing frame 100 and the fastener 200 are made of stainless steel, beryllium copper, oxygen-free copper, molybdenum or titanium. The working environment temperature of the needle tip holder is room temperature, liquid nitrogen, liquid helium or lower temperature.

[0045] One radial side of the needle hole 103 is the operating side, and the fastener 200 is disposed on the operating side of the fixing member 101. The fixing member 101 is disposed on the operating side close to the supporting member 102. By disposing the fixing member 101 on the supporting member 102 with the side close to the fastener 200, uneven weight distribution of the entire needle tip holder, which could cause the needle tip holder to easily tip over in the cavity, is avoided under the influence of the fastener 200. The center of gravity of the needle tip holder is horizontally aligned with the geometric center of the base plate on which the needle tip holder is mounted.

[0046] The needle hole 103 is arranged close to the center of the supporting member 102 to ensure that after the probe is installed in the needle hole 103, the probe can be kept in the center position of the needle tip support, which is convenient for operation.

[0047] Regarding the connection method between the supporting member 102 and the fixing member 101, the supporting member 102 and the fixing member 101 may be connected by bolts; bonded by vacuum adhesive; or integrally cast. The vacuum adhesive may be at least one of conductive silver paste, glass cement, silicone rubber, acrylate polymer, polyimide, polyester, and epoxy resin.

[0048] In one embodiment of the present invention, the outer side surface of the fixing member 101 in the radial direction of the needle hole 103 is a circular surface, and the fixing member 101 is a cylindrical fixing member 101.

[0049] In another embodiment of the present invention, the outer side surface of the fixing member 101 in the radial direction of the pinhole 103 is a prism, and the number of prisms is multiple. Each prism has at least one fastening hole 1011, and the axis of each fastening hole 1011 is located in the same horizontal plane or in different horizontal planes. Depending on the number of prisms on the outer side surface of the fixing member 101, the fixing member 101 can be a triangular prism-shaped fixing member 101 or a quadrangular prism-shaped fixing member 101.

[0050] The insulating member 300 is made of insulating ceramic, which is smoother than insulating adhesive and thus presents less resistance when inserted into the scanning head, thereby improving the success rate of installation and preventing the needle tip holder from tipping over in the scanning head. The insulating member 300 is provided with a mounting hole 301, which is used to insert the fixing member 101 through the mounting hole 301 and adhere to the second mounting surface 1021a using vacuum adhesive. The outer edge of the insulating member 300 is flush with the outer edge of the second mounting surface 1021a, and a gap is reserved horizontally between the inner wall of the mounting hole 301 on the insulating member 300 and the inner edge of the mounting portion 1021 to facilitate the insertion of the insulating member 300 through the mounting hole 301 onto the outer side of the fixing member 101.

[0051] The utility model also provides a scanning tunneling microscope, not shown in the figure, which includes the above-mentioned needle tip holder and further includes:

[0052] A scanning head base, wherein a connecting surface is provided on the scanning head base, and the connecting surface is in contact with the first mounting surface 100b;

[0053] The clamping member is connected to the scanning head base, and the clamping member matches the supporting member 102, wherein the clamping member abuts against the insulating member 300.

[0054] The clamping member moves toward the center of the scanning head base. Specifically, a guide groove extending toward the center is formed on the scanning head base, and the clamping member is installed in the guide groove. An elastic member is provided between the clamping member and the scanning head base, and the elastic member is configured to drive the clamping member to move along the guide groove toward the center of the scanning head base. Preferably, the elastic member is a spring.

[0055] Optionally, the scanning tunneling microscope is a scanning tunneling microscope with a Pan-type scanning head or an Omicron scanning tunneling microscope. In addition, the tip holder can also be used for an ultra-high vacuum system combined with a pulsed light deposition device or a molecular beam epitaxy device and an angle-resolved photoelectron spectrometer device.

[0056] The size of the fastening hole 1011 is M1*10mm-M6*40mm, and the size of the fixing member 101 is 1*1*1cm-5*5*6cm. The above size limits ensure the operability and mechanical strength of the fixing frame 100 while reducing the overall weight of the needle tip holder and preventing the needle tip holder from falling off during transportation;

[0057] The dimensions of the support member 102 range from 5*5*0.1cm to 20*20*1cm. This dimension is limited to match the working distance of the fixed spring clip of the needle tip holder in the scanning head, thereby reducing mechanical vibration, mechanical coupling, and thermal drift caused by inertia of the needle tip holder during scanning. This improves the feedback control accuracy of the STM under high-speed scanning and facilitates improved image scanning stability.

[0058] The size of the pinhole 103 is Φ0.1*10mm-Φ1*20mm, and the size of the fastening hole 1011 is M1*10mm-M6*40mm. The size of the pinhole 103 is limited to match the common specifications of the scanning probe, so as to achieve repeatable fixation of the probe angle and position, and ensure the fastening and stable tunneling of the probe when the needle tip vibrates mechanically during the scanning process;

[0059] The thickness of the insulating member 300 is 0.1-2 mm;

[0060] The fixing frame 100 is made of beryllium copper, and the fastener 200 is made of pure molybdenum. The beryllium copper fixing frame 100 has the advantages of good machinability and low cost, and can realize one-piece casting of the structure. Its good electrical conductivity, mechanical strength, and wear resistance are conducive to achieving a stable scanning signal. The pure molybdenum fastener 200 has high mechanical strength, which is conducive to maintaining its state of multiple fixing of the scanning probe and not easy to deform. In addition, pure molybdenum also has good electrical conductivity and chemical stability, which is conducive to measuring STM tunneling current signals and maintaining ultra-high vacuum conditions. The use of pure molybdenum fastener 200 for threaded connection with the stainless steel fixing frame 100 is conducive to achieving high mechanical strength, wear resistance, high temperature resistance, and stable electrical conductivity in an ultra-high vacuum environment.

[0061] In one embodiment of the present invention, the fixing member 101 and the supporting member 102 are integrally cast, the insulating member 300 is 0.5 mm thick, and a 3*3 cm mounting hole 301 is opened on the surface of the insulating member 300; the fixing member 101 has a size of 2.5*2.5*3 cm; the supporting member 102 has a size of 11*8*0.5 cm; the needle hole 103 has a size of Φ0.5*3 mm; the fastening hole 1011 has a size of M1.6*1.8 mm. In this embodiment, the needle tip holder is used as follows:

[0062] First, insert the probe into the pinhole 103 of the fixing member 101 at a suitable depth and angle until it contacts the bottom of the pinhole 103. Then, screw the fastener 200 into the fastening hole 1011 until it is tightened, so that the fastener 200 squeezes and positions the probe in the pinhole 103.

[0063] The needle tip holder is mounted on the needle tip transfer holder and transferred into the vacuum chamber, and the needle tip holder is placed on the scanning head base in the vacuum chamber, wherein the supporting member 102 is in contact with the scanning head base, and the installation of the scanning probe is completed by clamping the insulating member 300 of the needle tip holder with the clamping member on the scanning head base.

[0064] In another embodiment of the present invention, the support member 102 and the fixing member 101 are bonded together using vacuum adhesive. The probe end face and the bottom surface of the pinhole 103 are spaced apart. The probe, the sidewall of the pinhole 103, and the fastener 200 are sequentially connected to form a tunneling current path. During use, the tunneling current sequentially passes through the contact surface of the probe, the sidewall of the pinhole 103, and the fastener 200. This tip support is used in a combined system of an ultra-high vacuum scanning tunneling microscope and a molecular beam epitaxy device.

[0065] In summary, the needle tip holder uses the fastener 200 and the fixing member 101 to fix the scanning probe. Its operation is convenient and simple, and the degree of fastening is controllable. It is suitable for scanning probes of different specifications and can accurately and quickly adjust and fix the angle and position of the probe. According to the practice of many operators in related fields, the average operation time of needle tip installation has been shortened from the traditional approximately 1 hour to approximately 10 minutes.

[0066] In addition, the tip holder can achieve tunneling current signal transmission without conductive adhesives. The greatly increased contact area between the tip holder and the scanning head base improves the stability of the scanning probe, effectively suppresses noise interference caused by mechanical vibration and thermal drift, and improves the quality of STM scanning images.

[0067] The embodiments described above are only used to illustrate the technical ideas and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The scope of patent application of the present invention cannot be limited by these embodiments alone. That is, any equivalent changes or modifications made according to the spirit disclosed by the present invention still fall within the patent scope of the present invention.

Claims

1. A needle tip holder, characterized in that: include: A fixing frame (100), the fixing frame (100) comprising an exposed surface (100a) and a first mounting surface (100b) opposite to each other, and a fixing member (101) and a supporting member (102) extending sequentially between the exposed surface (100a) and the first mounting surface (100b), the peripheral edge of the supporting member (102) extending to the outside of the fixing member (101) to form a mounting portion (1021), a side surface of the mounting portion (1021) opposite to the first mounting surface (100b) being a second mounting surface (1021a), and a pinhole (103) extending toward the first mounting surface (100b) being provided on the exposed surface (100a); a fastener (200), the fastener (200) being connected to the fixing frame (100), the fastener (200) being configured to move inside the needle hole (103) along the radial direction of the needle hole (103); A hard insulating member (300), wherein the insulating member (300) is an insulating member (300) with uniform thickness, and the insulating member (300) covers the second mounting surface (1021a).

2. A needle tip holder according to claim 1, characterized in that: A fastening hole (1011) is provided on the outer side of the fixing member (101), the fastening hole (1011) and the pinhole (103) are connected, the axis of the fastening hole (1011) and the axis of the pinhole (103) intersect, and the fastener (200) is screwed into the fastening hole (1011).

3. A needle tip holder according to claim 2, characterized in that: The axis of the fastening hole (1011) is perpendicular to the axis of the needle hole (103), and the axis of the fastening hole (1011) intersects at the center position of the axis of the needle hole (103).

4. A needle tip holder according to claim 2, characterized in that: The sum of the length of the fastening hole (1011) and the diameter of the pinhole (103) is no greater than the length of the fastener (200).

5. A needle tip holder according to claim 2, characterized in that: One radial side of the needle hole (103) is the operating side, the fastener (200) is arranged on the operating side of the fixing member (101), and the fixing member (101) is arranged close to the operating side of the supporting member (102).

6. A needle tip holder according to claim 1, characterized in that: The fixing member (101) and the supporting member (102) are integrally cast, and the bottom surface of the needle hole (103) is configured to be in contact with a probe.

7. A needle tip holder according to claim 1, characterized in that: The supporting member (102) and the fixing member (101) are bonded by vacuum adhesive, the bottom surface of the pinhole (103) and the probe are spaced apart, and the probe, the side wall of the pinhole (103) and the fastener (200) are sequentially connected to form a tunneling current path.

8. A needle tip holder according to claim 2, characterized in that: The outer side surface of the fixing member (101) in the radial direction of the needle hole (103) is a prism, and there are multiple prisms, and each prism is provided with at least one fastening hole (1011).

9. A needle tip holder according to claim 1, characterized in that: The insulating member (300) is an insulating ceramic insulating member (300), and the insulating member (300) is bonded to the second mounting surface (1021a) by vacuum adhesive. A mounting hole (301) is provided on the insulating member (300), and the outer edge of the insulating member (300) is flush with the outer edge of the second mounting surface (1021a). A gap is reserved on a horizontal plane between the inner wall of the mounting hole (301) on the insulating member (300) and the inner edge of the mounting portion (1021).

10. A scanning tunneling microscope, comprising the tip holder according to any one of claims 1 to 9, characterized in that: Also includes: A scanning head base, wherein a connecting surface is provided on the scanning head base, and the connecting surface is in contact with the first mounting surface (100b); A clamping member is connected to the scanning head base, the clamping member matches the supporting member (102), and the clamping member abuts against the insulating member (300).

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