JP2007298506A - Sample cooling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sample cooling apparatus capable of cooling and holding samples or wafers at a cryogenic temperature with no vibration or drift with respect to a measurement reference surface. <P>SOLUTION: In the sample cooling apparatus, (a) a sample holder is arranged in a vacuum vessel mounted on a housing having a table for forming a measurement reference surface to be supported by a thermal insulator. (b) A frame is disposed within the housing, and the part between the housing and the frame is supported by a first buffer. (c) A refrigerating machine is disposed in the frame to be supported by a second buffer disposed between the frame and the refrigerating machine having a cooling head directed to the vacuum vessel. The cooling head of the refrigerating machine is connected to the sample holder by way of a flexible thermal conduction member disposed between the sample holder and cooling head. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sample cooling apparatus for cooling a sample or a wafer to an extremely low temperature and performing microscopic observation, microscopic differential light, near-field microscopic observation, near-field spectroscopy, photoconductive property evaluation, or conductive property evaluation.

  When a sample or wafer is cooled to a cryogenic temperature by a refrigerator, vibrations using the refrigerator as a vibration source are transmitted to the sample or wafer, and the sample or wafer vibrates or drifts with respect to the measurement reference plane. When performing microspectroscopy, near-field microscope observation, near-field spectroscopy, photoconductive property evaluation, or conductive property evaluation, there is a problem of reducing the accuracy.

  On the other hand, conventionally, a method (Patent Documents 1 to 5) in which a vacuum vessel and a refrigerator are connected via an anti-vibration adapter has been proposed. Certainly, the sample with less vibration adapter has less vibration and drift, but it is still not enough for high spatial resolution measurement.

  Accompanying this, a method of fixing the weight to the refrigerator and reducing the vibration (Patent Documents 6 and 7) and a method of fixing the refrigerator firmly on the floor and reducing the vibration (Patent Document 8) were devised. ing. Certainly, this further reduces sample vibration and drift, but is insufficient for measurements requiring high spatial resolution of 1 micron or less.

  In addition, a method (Patent Document 9) has also been proposed in which the relative motion between the sample and the measurement system is made zero by fixing the measurement system to the vibrating part of the refrigerator. However, since the vibration part vibrates at an acceleration, the measurement system and the member fixing the measurement system are deformed, so that the relative motion does not actually become zero.

  On the other hand, a method for cooling a sample via air, helium gas or liquid helium and not transmitting the vibration of the refrigerator directly to the sample has been proposed (Patent Documents 10 to 12). Since the vibration of the refrigerator is indirectly transmitted to the sample through, the substantial effect is low.

  In addition, a method of stopping the refrigerator once during the measurement (Patent Document 13) has also been proposed, but is not suitable for precise measurement because the temperature is not constant and the sample drift is large.

JP 05-243042 A Japanese Patent Application Laid-Open No. 07-84058 Japanese Patent Laid-Open No. 09-50910 Japanese Patent Laid-Open No. 11-87131 JP-A-11-512512 Japanese Patent Application Laid-Open No. 09-229997 JP 2006-41259 A JP 2005-24184 A JP 05-245395 A Japanese Patent Laid-Open No. 05-297092 Japanese Patent Laid-Open No. 06-74819 Japanese Patent Laid-Open No. 06-109821 JP 2002-277086 A

  The object of the present invention is to solve the problems of the prior art, and when the sample or wafer is cooled to an extremely low temperature, the sample or wafer vibrates or drifts with respect to the measurement reference plane. The purpose is to realize a device without any problem. In particular, it is preferable that the temperature of the sample or wafer is 20K or less and the vibration or drift of the sample or wafer is 0.2 μm or less, thereby enabling precise sample evaluation at a very low temperature and high spatial resolution.

In order to solve the above problems, the sample cooling device of the present invention includes: (a) a sample holder provided in a housing having a table that forms a measurement reference surface, supported via a heat insulating member, and disposed in a vacuum vessel; ,
(B) a frame disposed in the housing, the frame supported between the housing and the frame by a first shock absorber;
(C) A refrigerator disposed in the frame, wherein the refrigerator is provided by a second shock absorber disposed between the frame and a refrigerator having a refrigerator head directed toward the vacuum vessel. The refrigerator head supported and connected to the sample holder by a flexible heat conducting member disposed between the sample holder and the refrigerator head,
It is characterized by that.
In the present invention, in the table forming the measurement reference surface, the measurement reference surface can be the position of the upper surface of the table.

Hereinafter, preferred embodiments of the sample cooling device of the present invention will be described.
It is preferable to arrange a vacuum container on one side of the table forming the measurement reference surface and a frame on the other side.

  A through-hole is formed in the table forming the measurement reference surface in the housing, a U-shaped vacuum container having a lower opening above the through-hole, and a U-shaped frame having an upper opening below the through-hole. The refrigerator head is placed in the vacuum vessel so that the lower part of the refrigerator head is positioned in the frame, and the sides of the refrigerator are sealed in a sealed manner. The upper part of the member and the lower part of the vacuum vessel are preferably connected by a flexible vacuum bellows.

  In the sample cooling apparatus of the present invention, it is preferable that a plurality of frames and a plurality of sets of shock absorbers are used to form a multistage or multiple structure.

  The sample holder, the flexible heat conducting member, and the refrigerator head of the refrigerator are preferably covered with a heat radiation shield connected to the intermediate cooling unit of the refrigerator.

  It is preferable that the vibration and drift values of the sample are 0.2 μm or less and the temperature of the sample is 20 K or less.

  The first and / or second buffer preferably has an active vibration isolation function. Even in a plurality of frames and a plurality of sets of shock absorbers, it is preferable that all or a part of the shock absorbers have an active vibration isolation function.

  It is preferable that the vacuum container has a detachable or openable optical window. Although it is possible to observe the sample and perform optical measurement through the optical window, it is also possible to exchange the sample when the optical window is opened.

  The thermal radiation shield preferably has an optical measurement hole.

  It is preferable that the heat radiation shield has a detachable or openable lid.

  It is preferred that the heat radiation shield has an optical window that is impermeable to heat.

  It is preferable to install a mechanism that can connect or approach an electric wire, a probe electrode, a cantilever, or an optical probe member to a sample or a wafer.

  It is preferable to fix the heat insulating member and the vacuum vessel with at least two beams.

  It is preferable that the beam has a structure that penetrates the heat radiation shield.

  The beam has a bolt shape inserted into the hole from the outside of the vacuum vessel and fixed to the heat insulating member, the head of the bolt beam is covered with the vacuum cover of the vacuum vessel, and the vacuum vessel and the vacuum cover It is preferable to adopt a configuration in which a vacuum leak between the two is prevented by an O-ring.

  The beam has a bolt-like shape that is inserted into the hole from the outside of the vacuum vessel and is fixed to the heat insulating member, and the cylindrical side surface of the bolt-like beam is in close contact with the vacuum vessel hole, and the columnar shape of the beam It is preferable that the O-ring prevents vacuum leakage between the side surface and the side surface of the hole.

  It is preferable to have a structure that can adjust the position or inclination of the sample holder with respect to the measurement reference plane by using six or eight beams.

  It is preferable that the heat insulating member has a cylindrical or rod-like structure.

  When fixing the sample or wafer to the sample holder, it is preferable that a ring or mesh plate is placed on the sample and the ring or mesh plate is fixed to the sample holder with a screw or clamp. .

  It is preferable that the sample holder has an electrostatic adsorption function.

  Flexible heat conducting member is copper wire, silver wire, silver plated copper wire, gold plated copper wire, gold plated silver wire, copper ribbon, silver ribbon, silver plated copper ribbon, gold plated copper ribbon or gold plated silver It is preferably made from a ribbon.

  It is preferable to install a gate valve and a load lock for exchanging the sample or wafer in the vacuum vessel.

  It is preferable to have a cassette for holding a single sample or a plurality of samples for exchanging samples or wafers inside or outside the load lock.

  It is preferable that a sample or a wafer is exchanged by a manual arm or an automatic arm.

  It is preferable that the table having the measurement reference surface or the member fixed to the table having the measurement reference surface is an optical surface plate. Here, the optical surface plate and the table are one of the members forming the housing.

  It is preferable to provide a mechanism for moving or finely moving the measurement reference plane relative to the second measurement reference plane.

  As the refrigerator, a GM refrigerator, a Solvay refrigerator, a Joule-Thomson refrigerator, a piston tube refrigerator, or a helium circulation refrigerator is preferably used.

  It is preferably used as a sample cooling device for microscopic observation of a sample, microscopic light, near-field microscopic observation, near-field spectroscopy, photoresponse characteristic evaluation, photoconductive characteristic evaluation, or conductive characteristic evaluation.

  It is preferable that the sample cooling device has a configuration in which the sample can be microscopically observed, microscopically differentiated, near-field microscopically observed, near-field spectroscopy, photoresponse characteristic evaluation, photoconductive characteristic evaluation, or conductive characteristic evaluation in a wafer state.

  Thus, in the present invention, even if the sample or wafer is cooled to a very low temperature, it is possible to make the sample or wafer almost free of vibration and drift with respect to the measurement reference plane. For example, the temperature of the sample or wafer can be 20 K or less, and the vibration or drift of the sample or wafer can be 0.2 μm or less.

Therefore, it is possible to perform more precise microscopic observation, microscopic differential light, near-field microscopic observation, near-field spectroscopy, photoresponse characteristic evaluation, photoconductive characteristic evaluation, or conductive characteristic evaluation of a sample or wafer at an extremely low temperature.
Precise microscopic observation or microscopic observation or microspectroscopy is performed by a scanning tunneling microscope (STM), an atomic force microscope (AFM), a near-field scanning optical microscope (NSOM), or various other scanning probe microscopes (SPM). It can also be done.

  Embodiments of a sample cooling apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a front view showing a part of the outline of the configuration of the sample cooling apparatus according to the present invention in a longitudinal sectional view and partly in a front view. As shown in FIG. 1, the sample cooling apparatus according to the present invention fixes a sample holder 5 through a heat insulating member 4 in a vacuum vessel 2 fixed to a table forming a measurement reference surface 1, and also measures a measurement reference. A frame 7 is installed on the table forming the surface 1 via the first buffer 6, and the refrigerator 11 is supported by the frame 7 via the second buffer 8 and the refrigerator head faces the vacuum vessel 2. And the refrigerator head 12 of the refrigerator 11 is connected to the sample holder 5 via the flexible heat conducting member 13.

The table forming the measurement reference plane 1 is made of a flat plate-like member installed horizontally, supported by a vertical wall 61 erected from the bottom plate 60, and a through hole 62 is formed at the center.
In the sample cooling apparatus shown in FIG. 1, a vacuum container 2 having a U-shaped cross-section with a lower opening opened above a table forming the measurement reference plane 1 is provided with a refrigerator 11 below the table forming the measurement reference plane 1. A frame 7 having a U-shaped cross-section with an opening above the support is disposed. In FIG. 1, the housing includes a table that forms the measurement reference plane 1, a vertical wall 61, and a bottom plate 60.

The refrigerator 11 is arranged such that the refrigerator head 12 is located in the vacuum vessel 2 and the lower part of the refrigerator head 12 is located in the space in the frame 7, and the side portion of the refrigerator 11 is sealed. The upper part of the sealing member 10 covered in a shape and the lower part of the vacuum vessel 2 are connected by a flexible vacuum bellows 9 to form a vacuum space continuous with the space in the vacuum vessel 2. In the case of FIG. 1, the intermediate cooling unit 14 of the refrigerator 11 is located in the flexible vacuum bellows 9.
The refrigerator 11 includes a second shock absorber 8 provided at several places between a sealing member 10 that covers the side portion in a sealing manner and an inner wall of the frame 7, and a second shock absorber provided at the bottom wall of the frame 7. It is supported by the frame 7 via 8.

  A cylindrical heat insulating member 4 is connected to the lower side of a flat sample holder 5 arranged horizontally, and the heat insulating member 4 is supported by a beam 3 extending from the vacuum vessel 2. The refrigerator head 12 of the refrigerator 11 is located in the U-shaped space of the lower opening formed by the flat sample holder 5 and the cylindrical heat insulating member 4, and the refrigerator head 12, flexible heat A cylindrical heat radiation shield 15 extending upward from the intermediate cooling unit 14 of the refrigerator 11 is provided so as to cover the conductive member 13 and the sample holder 5.

  Here, by disposing the refrigerator 11 inside the frame 7, the sample cooling device according to the present invention can be miniaturized.

  In addition, by disposing the vacuum vessel 2 on the measurement reference plane 1, assembly, maintenance, or sample replacement of the sample cooling device according to the present invention is facilitated.

  In addition, by disposing the vacuum vessel 2 below the measurement reference surface 1, it becomes easy to dispose another measuring device or the like in the space above it.

  The sealing member 10 that covers the refrigerator 11 and the sides of the refrigerator in a sealing manner generates vibration during operation of the refrigerator 11, and is provided between the refrigerator 11 and the sealing member 10 and the frame 7. The vibration is attenuated by the shock absorber 8 and transmitted to the frame 7 slightly.

  Here, the frame 7 is floated with respect to the reference plane 1 by the first shock absorber 6 and can be freely vibrated, and further connected to the refrigerator 11 and the sealing member 10 by the second shock absorber 8. Therefore, the frame 7 moves behind the movement of the refrigerator 11.

  Therefore, the vibration of the refrigerator 11 and the vibration of the frame 7 are out of phase, and the frame 7 acts to cancel the vibration of the refrigerator 11 and the sealing member 10.

  The slight vibration transmitted to the frame 7 is further attenuated by the first shock absorber 6, and as a result, the vibration of the refrigerator 11 and the sealing member 10 is fixed to the measurement reference plane 1 or the measurement reference plane 1. In addition to being hardly transmitted to the members, it is possible to suppress vibrations of the original refrigerator 11 and the sealing member 10.

  On the other hand, the reduced vibrations of the refrigerator 11 and the sealing member 10 described above are hardly transmitted to the measurement reference plane 1 due to the flexibility of the flexible vacuum bellows 9.

  In addition, the sample 17 or the sample holder 5 is cooled by the refrigerator head 12 through the flexible heat conducting member 13, but due to the flexibility of the flexible heat conducting member 13, the vibration of the refrigerator 11 causes the sample to vibrate. Little is transmitted to the holder 5 or the sample 17.

  With such a configuration, even when the sample 17 is cooled to a very low temperature, it is possible to make the sample 17 have almost no vibration or drift with respect to the measurement reference plane 1.

When the first shock absorber 6 and / or the second shock absorber 8 has an active vibration isolation function, the sample 17 can be brought closer to a vibration-free and drift-free state with respect to the measurement reference plane 1.
Here, the active vibration isolation function first detects the original vibration, and then generates a vibration having the same amplitude as that of the vibration, thereby canceling the original vibration in a feedback manner. It means the function to attenuate the vibration from the original vibration.

  In addition, observation of the sample 17 and optical measurement are possible by installing the optical window 16 in the vacuum vessel 2.

  By installing the optical window 18 that does not allow heat to pass through the heat radiation shield 15, it is possible to suppress the temperature rise of the sample 17 even when the sample 17 is observed from the outside. Further, a mechanism (not shown) that can connect or approach an electric wire, a probe electrode, a cantilever, or an optical probe member to the sample 17 may be installed.

  Here, as shown in FIG. 1, when the heat radiation shield 15 is branched so as to be installed inside and outside the heat insulating member 4, the heat radiation shield effect is enhanced.

  By fixing the heat insulating member 4 and the vacuum vessel 2 with at least two or more beams 3, the sample 17 can be firmly fixed to the measurement reference plane 1 and the relative motion can be reduced.

  In this case, the beam 3 has a structure that penetrates the heat radiation shield 15.

  Further, the beam 3 has a bolt-like shape that is inserted from the outside of the vacuum vessel 2 and fixed to the heat insulating member 4, and the head of the bolt-like beam 3 is brought into close contact with the vacuum vessel 2 through an O-ring 19. By covering with the vacuum cover 20, the sample 17 can be firmly fixed to the measurement reference plane 1 and the vacuum in the vacuum container 2 can be maintained.

  In this case, the position of the heat insulating member 4, the sample holder 5, and the sample 17 can be slightly moved by closing the bolt-shaped beam 3, but the beam 3 is separately moved or slightly moved with respect to the measurement reference plane 1. You may add the mechanism which is not illustrated.

  The O-ring may be installed on the cylindrical side surface of the bolt-shaped beam 3 below the head of the bolt-shaped beam 3.

  Furthermore, by using six or eight beams, the position or inclination of the heat insulating member 4, the sample holder 5, and the sample 17 can be adjusted with respect to the measurement reference plane 1 with higher accuracy.

  The heat insulating member 4 has a cylindrical or rod-shaped structure, so that the strength is increased and the sample holder 5 or the sample 17 can be firmly fixed to the measurement reference plane 1.

The sample 17 can be fixed to the sample holder 5 with an adhesive, but a ring or mesh plate (not shown) is placed on the sample 17 and the ring or mesh plate is screwed or removed. By fixing to the sample holder 5 with the clamp, it is easy to fix the sample and replace the sample.
At this time, the sample 17 may be separately fixed to a plate-like member (not shown), and the plate-like member may be attached to and detached from the sample holder 5.

  In addition, when the sample holder 5 has an electrostatic adsorption function, the sample 17 can be easily attached and detached.

  As the flexible heat conducting member 13, copper wire, silver wire, silver plated copper wire, gold plated copper wire, gold plated silver wire, copper ribbon, silver ribbon, silver plated copper ribbon, gold plated copper ribbon or gold plated A silver ribbon can be used.

  If a gate valve (not shown) and a load lock for exchanging the sample 17 are installed in the vacuum vessel 2, the sample 17 can be exchanged while maintaining the vacuum in the vacuum vessel 2.

  If a cassette for holding a single sample or a plurality of samples or wafers for exchanging samples or wafers is installed inside or outside the load lock, it is possible to measure a plurality of samples or wafers continuously.

At that time, if the sample 17 is replaced by a manual arm or an automatic arm, the sample can be quickly replaced.
At this time, the sample 17 may be separately fixed to a plate-like member and replaced with the plate-like member.

  When the table forming the measurement reference surface 1 is configured as an optical surface plate, the sample 17 can be measured using an optical system installed on the optical surface plate. The measurement reference plane 1 or the optical surface plate may be fixed by placing the refrigerator, the frame, the vacuum vessel, etc. on the side or by inverting the top and bottom.

  When a mechanism for moving or finely moving the measurement reference plane 1 with respect to a second measurement reference plane (not shown) is provided, the in-plane distribution of the sample 17 can be measured using a measurement system installed on the second measurement reference plane. .

  As the refrigerator 11, a GM type refrigerator, a Solvay type refrigerator, a Joule Thomson type refrigerator, a piston tube type refrigerator, or a helium circulation type refrigerator can be used.

  The sample 17 can be used as a sample cooling device for microscopic observation, microscopic light, near-field microscopic observation, near-field spectroscopy, photoresponse characteristic evaluation, photoconductive characteristic evaluation, or conductive characteristic evaluation.

  Inspection of the wafer can be performed by configuring the sample cooling apparatus that can perform microscopic observation, microscopic observation, near-field microscopic observation, near-field spectroscopy, photoresponse characteristic evaluation, photoconductive characteristic evaluation, or conductive characteristic evaluation of the sample 17 in a wafer state. It becomes possible.

  FIG. 2 is a front view showing an outline of the configuration of the sample cooling apparatus according to the present invention. This FIG. 2 is similar to FIG. 1, but in FIG. 2, two frames (7, 7-1) and a plurality of sets of shock absorbers are used to form a two-stage or double structure. By preventing the vibration from being transmitted in two stages, the vibration is more difficult to be transmitted. In addition, it is also possible to make it difficult to transmit vibration by using a plurality of frames and a plurality of sets of shock absorbers, and having a multi-stage structure of three or more stages or a triple structure of three or more layers. It is possible that all or part of the shock absorber has an active vibration isolation function. Further, as shown in FIG. 2, the vibration isolation effect can be further increased by supporting the flexible vacuum bellows 9 with a beam 105 installed on the frame 7. In FIG. 2, the same reference numerals as those in FIG. 1 denote the same elements as those in FIG.

  Hereinafter, the present invention will be described based on examples with reference to the drawings. However, the present invention is not limited to the following examples. In the following description, the same reference numerals in FIG. 1 and FIG.

Example 1 of the sample cooling device of the present invention is shown in FIG. The sample cooling apparatus according to the first embodiment includes a vacuum vessel 2, a beam 3, a heat insulating member 4, a sample holder 5-2, a first shock absorber 6, 6-2, a frame 7, and a second buffer, which are the features of the present invention. As shown in FIG. 1, the machine 8, the flexible vacuum bellows 9, the sealing member 10, the refrigerator 11, the flexible heat conducting member 13, and the heat radiation shield 15 are formed on the table forming the measurement reference plane 1. It is arranged on a fixed member 22.
In FIG. 3, the vacuum cover 20 covers the buffer member 51, the spring-loaded buffer member 52, the sealing means 26 including the support members 53, 54, 55 and 56, and the sealing member 10, and the head of the beam 3. The sealing means 27 and the sealing means 28 including the sample 17 and the optical window 16 are respectively enlarged and schematically shown in the drawing.

  In Example 1, the measurement reference surface 1 is set on the optical surface plate 21, and the vacuum container 2 is fixed to a member 22 fixed on the optical surface plate 21 that forms the measurement reference surface 1. .

  The optical surface plate 21 is fixed to the floor 24 by a pillar 23, and the frame 7 is installed via the first buffer 6 or the first buffer 6-2 connected to the member 22 and the floor 23. Has been.

Note that the optical surface plate 21 and the column 23 may be separately provided with a vibration isolation function.
In FIG. 3, the housing includes an optical surface plate 21, a member 22, a pillar 23, and a floor 24.

  The refrigerator 11 or the sealing member 10 is installed in the frame 7 via the second shock absorber 8 or the second shock absorber 8-2, and the sealing member 10 is connected to the vacuum container 2 via the flexible vacuum bellows 9. Has been.

  Here, the refrigerator 11 or the sealing member 10 is installed inside the frame 7 and is arranged so as to make the overall size compact.

  Further, the first shock absorber 6 uses a shock absorbing member such as rubber, resin, gel, or spring, and the second shock absorbers 8 and 8-2 are shock absorbing members in which main roles are divided in respective space directions. The second shock absorber 8 includes a shock absorber 51 for buffering vertical vibration and a shock absorber 52 with a spring for buffering horizontal vibration in support members 53 and 54. , 55 and 56.

  The second shock absorber 8-2 has a structure in which four functions of the second shock absorber 8 are combined into one.

  The combination of the buffer members is not necessarily limited to this example, and other combinations may be used.

  On the other hand, the sample holder 5-2 is fixed on the heat insulating member 4 fixed to the vacuum vessel 2 by the beam 3, and the lower part thereof is connected to the refrigerator head 12 via the flexible heat conducting member 13. Yes.

  The heat radiation shield 15 is connected to the intermediate cooling unit 14 of the refrigerator 11 and covers the cooling head 12, the flexible heat conducting member 13, and the sample holder 5-2 to prevent heat radiation from the outside. Yes.

  In Example 1, the sample 17 is arranged so as to be observable from the side surface, and is arranged through the thermal radiation shield 15 so as to be observed closer to the optical window 16 on the side surface. .

  In the first embodiment, the temperature of the sample 17 can be cooled to 10K or less, and the vibration and drift of the sample 17 can be suppressed to 0.1 μm or less with respect to the optical surface plate 21 or the member 22 forming the measurement reference surface. done.

  Further, if the caster 25 is attached to the frame 7, it is convenient for moving the apparatus.

  FIG. 4 shows Example 2 of the sample cooling device of the present invention. The second embodiment is configured so that the sample can be observed from the upper surface.

  The sample 17 can be exchanged by opening the cover 34 of the heat radiation shield and the vacuum container cover 33 with the optical window 18 that does not allow heat to pass through and removing the fixing ring 35.

  The beam 3 is inserted from the outside of the vacuum vessel 2 and screwed to a stopper 31 inside the heat insulating member 4. At this time, the beam 3 passes through a hole opened in the heat radiation shield 15.

  Further, the flexible heat conducting member 13 is connected to the refrigerator head 12 through the heat conducting member 32, and the flexible heat conducting member 13 is connected to the sample holder 5 and the heat conducting member 32 at both ends. The member for is connected.

The sample 17 can be fixed to the sample holder 5 in the wafer state by using the fixing ring 35. However, if the sample holder 5 is provided with an electrostatic adsorption function, the sample replacement is easier.
Alternatively, the sample 17 may be separately fixed to a plate-like member (not shown) and replaced with the plate-like member.

  FIG. 5 shows Example 3 of the sample cooling apparatus of the present invention. In the third embodiment, the objective lens 42 installed in the microspectroscopic device 41 can be used to observe a sample from the side surface or to perform microspectroscopic light or microscopic light response measurement.

  Since the measurement reference plane is set on the optical surface plate 21 and the sample cooling device and the microspectroscopic device of the present invention are fixed to the optical surface plate 21, the sample temperature is set to 10K or less. High-precision microscopic observation, microscopic differential light or microscopic light response measurement with vibration and drift suppressed to 0.1 μm or less were possible.

  6 (A) and 6 (B) show Example 4 of the sample cooling device of the present invention. In Example 4, the photoconductivity or conductivity of the sample can be measured. FIG. 6A is an explanatory diagram of the usage state of the sample cooling device, and FIG. 6B is a schematic diagram showing an enlarged sample fixing member 78 inserted into the IC socket 75. FIG.

  Here, in the sample fixing member 78, the sample 17 is bonded to the IC package 71 and is electrically connected to the electrode pad 72 of the IC package 71 by the electric wire 73.

  Further, the IC package 71 inserts and fixes the electrode terminal 74 into the IC socket 75 installed in the sample holder 5-2.

  Here, when the electric wire 73-2 is connected to each electrode terminal of the IC socket 75, the sample 17 on the sample fixing member 78 and the electrical measuring device 76 can be electrically connected. It becomes possible to measure the characteristics.

  Note that the temperature of the sample 17 can be stabilized by placing the sample cover 77 on the IC package 71.

  Of course, although it is somewhat inconvenient, it is possible to connect an electric wire to the sample without using an IC package or an IC socket.

  FIG. 7 shows Embodiment 5 of the sample cooling device of the present invention. Example 5 is another example in which the photoconductivity and conductivity of a sample can be measured.

Here, the sample 17 installed in the sample holder 5 is electrically connected to the electrical measuring device by the probe electrode 81, but if the probe electrode 81 is moved by the moving stage 82, the sample 17 is connected to a plurality of electrical paths of the sample 17. Electrical measurement is possible.
The probe electrode 81 or the probe electrode 81 is replaced with a cantilever or an optical probe member, and near-field microscope observation or near-field spectroscopy can be performed.

  FIG. 8 shows a sixth embodiment of the sample cooling device of the present invention. Example 6 is an example in which sample exchange is facilitated.

  In the sixth embodiment, the gate valve 91 and the load lock 92 are installed in the vacuum vessel 2, and the gate valve 91 is connected to the gate valve opening / closing mechanism 91-2 while maintaining the vacuum in the vacuum vessel 2 and the load lock 92. The sample 17 is moved from the vacuum vessel 2 to the load lock 92 or from the load lock 92 to the sample holder 5 in the vacuum vessel 2 by opening and closing the arm 93 in and out of the vacuum vessel 2. be able to.

  At this time, the sample can be exchanged while maintaining the sample holder 5 at a low temperature, which leads to further shortening of the measurement time.

  The arm 93 may be manually operated, but when it is automatically operated, the sample can be exchanged accurately and quickly.

  On the other hand, when a cassette 94 for holding a single sample or a plurality of samples for exchanging samples is installed in the load lock 92, it is possible to continuously measure a plurality of samples while maintaining a vacuum.

  The cassette 94 can be moved by the cassette moving mechanism 94-2. However, the sample or the cassette 94 can be taken out of the load lock 92 by opening the load lock door 92-2.

  Further, the cassette 94 may be installed in the vacuum container 2. At that time, the cassette moving mechanism 94-2 is installed in the vacuum vessel 2.

When the sample holder 5 has a sample pressing mechanism or an electrostatic adsorption function, the sample 17 can be attached and detached reliably, and the cooling efficiency is improved.
Note that a mechanism may be employed in which the sample is separately fixed to a plate-like member and the plate-like member is attached to and detached from the sample holder 5.

  FIG. 9 shows Example 7 of the sample cooling apparatus of the present invention. The seventh embodiment is an example in which a mechanism for moving or finely moving the measurement reference plane 1 or the sample 17 with respect to the second measurement reference plane 101 is installed.

  Here, the sample cooling device 103 is installed on the moving stage 102, and the relative position of the sample cooling device 103 or the sample 17 can be changed with respect to the second measurement reference plane 101.

  According to this embodiment, an in-plane distribution of the sample 17 from the through hole 104 is achieved by moving the sample cooling device 103 by the moving stage 102 using an optical measurement system or the like fixed to the second measurement reference surface 101. Measurement of characteristics, etc. becomes possible.

  The best mode of the sample cooling apparatus of the present invention has been described based on the embodiments. However, the present invention is not limited to such embodiments, and is within the scope of the technical matters described in the claims. Needless to say, there are various embodiments.

  According to the present invention having the above-described configuration, when the sample or wafer is cooled to a cryogenic temperature by a refrigerator, vibration using the refrigerator as a vibration source is transmitted to the sample or wafer, which has been a conventional problem. However, because it vibrates or drifts with respect to the measurement reference plane, when performing microscopic observation, microscopic differential light, near-field microscopic observation, near-field spectroscopy, photoconductive property evaluation, or conductive property evaluation, the accuracy is reduced. Therefore, the present invention can be applied to an application that requires high-precision measurement of a sample or a wafer at an extremely low temperature.

  For example, it is extremely useful for microscopic observation of a sample or wafer at a very low temperature, measurement of microscopic differential light or microscopic photoconductive characteristics, near-field microscopic observation, or near-field spectroscopy.

  In particular, when the sample cooling apparatus of the present invention is used in a wafer inspection apparatus, high-resolution measurement at an extremely low temperature can be easily performed, so that more reliable wafer quality control can be performed.

It is a front view which shows the outline | summary of a structure of the sample cooling device which concerns on this invention. It is a front view which shows the outline | summary of the change aspect of the structure of the sample cooling device which concerns on this invention. It is a front view which shows Example 1 of the sample cooling device of this invention. It is a front view which shows Example 2 of the sample cooling device of this invention. It is a top view which shows Example 3 of the sample cooling device of this invention. It is a front view which shows the principal part of Example 4 of the sample cooling device of this invention, and is explanatory drawing of the use condition of a sample cooling device. FIG. 7 is an enlarged schematic view showing a sample fixing member 78 to be inserted into the IC socket 75 in FIG. It is a front view which shows the principal part of Example 5 of the sample cooling device of this invention. It is a front view which shows the principal part of Example 6 of the sample cooling device of this invention. It is a front view which shows Example 7 of the sample cooling device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Measurement reference plane 2 Vacuum container 3 Beam 4 Thermal insulation member 5, 5-2 Sample holder 6, 6-2 First buffer 7, 7-1 Frame 8 Second buffer 9 Flexible vacuum bellows 10 Sealing member 11 Freezing Machine 12 Refrigerator head 13 Flexible heat conduction member 14 Intermediate cooling part 15 Heat radiation shield 16 Optical window 17 Sample 18 Optical window not passing heat 19 O-ring 20 Vacuum cover 21 Optical platen 22 Member 23 Pillar 24 Floor 25 Caster DESCRIPTION OF SYMBOLS 31 Stopper 32 Thermal conduction member 33 Vacuum container lid 34 Thermal radiation shield lid 35 Fixing ring 41 Microspectroscope 42 Objective lens 51 Buffer member 52 Spring-cushion member 53, 54, 55, 56 Stopper 60 Bottom plate 61 Vertical wall 62 Through-hole 71 IC package 72 Electrode pad 73, 73-2 Electric wire 74 Electrode terminal 75 IC socket 76 Electrical measurement Device 77 Sample cover 78 Sample fixing member 81 Probe electrode 82 Moving stage 91 Gate valve 91-2 Gate valve opening / closing mechanism 92 Load lock 92-2 Load lock door 93 Arm 94 Cassette 94-2 Cassette moving mechanism 101 Second measurement standard Surface 102 Moving stage 103 Sample cooling device 104 Through hole 105 Beam

Claims (27)

(A) a sample holder provided in a housing having a table forming a measurement reference surface, supported through a heat insulating member and disposed in a vacuum vessel;
(B) a frame disposed in the housing, the frame supported between the housing and the frame by a first shock absorber;
(C) A refrigerator disposed in the frame, wherein the refrigerator is disposed between the frame and the refrigerator with the refrigerator head facing the vacuum vessel. And the refrigerator head of the refrigerator is connected to the sample holder by a flexible heat conducting member disposed between the sample holder and the refrigerator head.
A sample cooling apparatus.   2. The sample cooling apparatus according to claim 1, wherein a vacuum container is disposed on one side of the measurement reference surface and a frame is disposed on the other side.   A through-hole is formed in the table forming the measurement reference surface in the housing, a U-shaped vacuum container having a lower opening above the through-hole, and a U-shaped frame having an upper opening below the through-hole. Then, the refrigerator head of the refrigerator is disposed in the vacuum vessel so that the lower portion of the refrigerator head is positioned in the frame, and the side portion of the refrigerator is covered in a sealed manner. The sample cooling apparatus according to claim 1 or 2, wherein an upper part of the sealing member and a lower part of the vacuum container are connected by a flexible vacuum bellows.   4. The sample holder, the flexible heat conducting member, and the refrigerator head of the refrigerator are covered with a heat radiation shield connected to the intermediate cooling section of the refrigerator. The sample cooling device according to 1.   5. The vibration value and drift value of the sample or wafer are each 0.2 μm or less, and the temperature of the sample or wafer is 20 K or less. 6. Sample cooling device.   The sample cooling device according to any one of claims 1 to 5, wherein the first shock absorber and / or the second shock absorber has an active vibration isolation function.   The sample cooling apparatus according to any one of claims 1 to 6, wherein the vacuum container has a detachable or openable optical window.   The sample cooling apparatus according to claim 4, wherein the heat radiation shield has a hole for optical measurement.   The sample cooling apparatus according to any one of claims 4 to 8, wherein the heat radiation shield has a detachable or openable lid.   The sample cooling device according to any one of claims 1 to 9, wherein an optical window that does not allow heat to pass through the heat radiation shield is installed.   The sample cooling device according to any one of claims 1 to 10, wherein a mechanism capable of connecting or approaching an electric wire, a probe electrode, a cantilever, or an optical probe member to a sample or a wafer is installed.   The sample cooling device according to any one of claims 1 to 11, wherein the heat insulating member is fixed to the vacuum vessel with at least two beams.   The sample cooling apparatus according to claim 12, wherein the beam has a structure that penetrates the heat radiation shield.   The beam has a bolt shape that is inserted into the hole from the outside of the vacuum vessel and is fixed to the heat insulating member, the head of the bolt beam is covered with the vacuum cover of the vacuum vessel, and the vacuum vessel and the vacuum cover The sample cooling device according to claim 12 or 13, wherein a vacuum leak between the two is prevented by an O-ring.   The beam has a bolt-like shape that is inserted into the hole from the outside of the vacuum vessel and is fixed to the heat insulating member, and the cylindrical side surface of the bolt-like beam is in close contact with the vacuum vessel hole, and the columnar shape of the beam The sample cooling device according to any one of claims 12 to 14, wherein a vacuum leak between the side surface and the side surface of the hole is prevented by an O-ring.   The sample cooling device according to any one of claims 1 to 15, further comprising a mechanism capable of adjusting the position or inclination of the sample holder with respect to the measurement reference plane by using six to eight beams.   The sample cooling device according to any one of claims 1 to 16, wherein the heat insulating member has a cylindrical shape or a rod shape.   When the sample or wafer is fixed to the sample holder, a ring or mesh plate is placed on the sample, and the ring or mesh plate is fixed to the sample holder with a screw or a clamp. The sample cooling device according to any one of claims 1 to 17.   The sample cooling device according to any one of claims 1 to 18, wherein the sample holder has an electrostatic adsorption function.   Flexible heat conducting member is copper wire, silver wire, silver plated copper wire, gold plated copper wire, gold plated silver wire, copper ribbon, silver ribbon, silver plated copper ribbon, gold plated copper ribbon or gold plated silver The sample cooling device according to any one of claims 1 to 19, wherein the sample cooling device is manufactured from a ribbon.   21. The sample cooling apparatus according to claim 1, wherein a gate valve and a load lock for exchanging a sample or a wafer are installed in the vacuum container.   The cassette according to any one of claims 1 to 21, further comprising a cassette for holding a single sample or a plurality of samples or wafers for exchanging a sample or a wafer in or outside the load lock. Sample cooling device.   The sample cooling device according to any one of claims 1 to 22, wherein the sample or the wafer is exchanged by a manual arm or an automatic arm.   The sample cooling device according to any one of claims 1 to 23, wherein the table forming the measurement reference surface is an optical table.   The sample cooling device according to any one of claims 1 to 24, further comprising a mechanism for moving the measurement reference plane with respect to the second measurement reference plane.   The GM type refrigerator, the Solvay type refrigerator, the Joule-Thompson type refrigerator, the piston tube type refrigerator, or the helium circulation type refrigerator is used as the refrigerator. The sample cooling device according to 1.   2. The sample or wafer is used as a sample cooling device for microscopic observation, microscopic observation, near-field microscopic observation, near-field spectroscopy, photoresponse characteristic evaluation, photoconductive characteristic evaluation, or conductive characteristic evaluation. Item 26. The sample cooling apparatus according to any one of Items 26.

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