JP2015014595A - Contact probe and manufacturing method therefor, nondestructive contact forming method, measurement method for multi-layer film during manufacturing process, and prober - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact probe for nondestructively making contact with a film of nm thickness to make measurement.SOLUTION: A contact probe comprising a contact unit, such as an Au ball having a smooth surface, provided at a tip of an elastic body, such as a W-wire, is used to make electrical contact with a film of nm thickness by putting the Au ball thereon. The Au ball is produced by fusing an AU wire while being entwined with the W-wire using Joule heat generated by flowing current through the W-wire and then solidifying the same, and has an extremely smooth spherical surface. This allows contact to be made with force dispersed over a large contact surface, enabling nondestructive contact to be made without requiring feedback of contact pressure or the like.

Description

  The present invention relates to a contact probe, and particularly a contact that can make non-destructive electrical contact with a very thin film or a fragile sample, which would destroy the sample when a conventional prober is used. The present invention relates to a probe and a manufacturing method thereof. Furthermore, the present invention relates to a non-destructive contact formation method using such a contact probe, a measurement method in a manufacturing process of a multilayer film, and a prober.

  In the development of materials used for capacitors, transistors, memory devices, and other devices, a laminated film in which an extremely thin film of about several atoms is laminated in multiple layers is often used. In addition, graphene is regarded as a promising electrode material, and layered materials such as molybdenum disulfide are expected to be used as ultra-thin channel materials utilizing its two-dimensionality. There is a growing need to evaluate various properties of samples by forming electrical contacts on thin materials.

  There are an enormous number of parameters to be checked in order to find the optimum material / process for the laminated film as described above. Among these parameters, material selection is important, and screening of materials by investigating the electrical characteristics at the time when the laminated structure is the same as that of a thin film-like device rather than a bulk is a variety of materials and film thicknesses. It becomes an effective means to narrow down. That is, a development process is performed in which material screening is first performed, a device structure is actually formed for the screened material, and electrical characteristics are measured with a conventional prober to perform fine tuning such as a process.

  However, in a method of pressing a tungsten probe used in a semiconductor prober that is a normal device electrical property measuring apparatus, an electrical contact is obtained by breaking an electrode pad over a depth of several nm or more. Referring to FIG. 1 for explaining this prior art, when contact is made with this type of probe (probe), the probe is positively pressed against an object to be contacted. In many probes, the probe is bent by such pressing, and the tip of the probe slides on the surface of the object. By such pressing (in some cases, sliding of the tip is also added), the surface of the contact target is deformed by approximately 20 nm or more. This degree of deformation results in irreversible deformation or destruction of the film, especially for nm-thick films present on the target surface. FIG. 2 shows an optical micrograph of a portion where a conventional probe is pressed. Attention should be paid to the part surrounded by the vertically long elliptical broken line on the right side of the figure. It can be seen that the upper part of the film where the probe is pressed is destroyed.

  Furthermore, damage such as peeling due to sliding occurs, or even if sliding does not occur, there is a possibility that an adverse effect on the film may occur due to the application of a parallel force to the very thin film surface. When making contact with an object where irreversible deformation or surface peeling does not become a problem, the destruction of a very thin film on the surface of the sample should be avoided by avoiding the effects of contamination existing on the surface of the object. In many cases, it is rather useful in terms of realizing a good contact. However, such a conventional technique is naturally not applicable when the film having a thickness of nm itself is a measurement object or a part of the structure of the measurement object. Therefore, when a thin and fragile device film is targeted, after fabrication, the surrounding wiring is also performed to produce an electrode pad with a thickness exceeding 100 nm, and a tungsten probe is pressed onto the electrode pad. To check the characteristics. Alternatively, as shown in FIG. 3, an electrode pattern is vapor-deposited on an insulating substrate, and a film of a material to be measured (a square region on the insulator substrate in the drawing) is vapor-deposited on the pattern. Check the characteristics without destroying the film itself by pressing the probe against the part of the electrode pattern (in the figure, the circular part located at the four corners of the square film) that is not covered by the film of the material to be measured. It is carried out. As another method, as shown in FIG. 4, a sample is formed in the shape of a device, and an electrode pad for contacting a probe may be provided in this measuring device.

  In addition, X-ray photoelectron spectroscopy (XPS) measurement is effective for evaluating band alignment that determines the electrical characteristics of the device. In the structure in which the semiconductor / insulator is in contact with the electrode, as shown in FIG. The measurement result may differ depending on whether or not is set to the ground potential. Further, in the structure in which the semiconductor / insulator is sandwiched between the electrodes, the flat band voltage can be evaluated from the XPS measurement by applying the electrical contact from both the upper and lower sides and applying the bias voltage. Patent Document 1 and Non-Patent Document 1 use this to freely switch electrical connection with a measurement sample having a non-ohmic contact interface, and acquire an electron spectrum in a state where various voltages are applied above and below it. Thus, identification of the interface where non-ohmic contact occurs, Schottky barrier height, flat band voltage, and the like are obtained by electron spectroscopy.

  An object of the present invention is to provide a contact probe capable of reversibly forming a non-destructive electrical contact with a film having a thickness of nm.

According to one aspect of the present invention, there is provided an elastic support body that extends in the longitudinal direction and has electrical conductivity, and a contact portion that is attached to the support body and has at least a part of a spherical surface having electrical conductivity. A contact probe is provided that obtains electrical contact with the film by bringing the spherical surface of the contact portion into non-destructive contact with a film having a thickness of nm.
Here, the contact portion may be provided at the tip of the support.
The contact portion may include at least a film made of a first material covering the surface and a member made of a second material covered with the first material.
Further, the spring constant k of the support may be in a range represented by the following formula.
π × 10 ⁻² [N / m ² ] ≦ k ≦ 5π × 10 ³ [N / m ² ]
The spherical surface of the contact portion may be a surface obtained by solidifying a dissolved substance.
The length of the support may be 2 mm or more.
Further, at least a part of the surface of the spherical surface may be an insulating region having an opening having a desired area.
The diameter of the opening may be 100 μm or less.
The insulating region may be a region covered with an insulating layer.
According to another aspect of the present invention, an elastic support having an electrical conductivity extending in the longitudinal direction is prepared, and a substance having a melting point lower than that of the elastic body and having an electrical conductivity is attached to the support. The contact probe manufacturing method according to any one of the above is provided, wherein the material is melted by energizing the support, and the melted material is solidified by stopping energization after the melting.
Here, after the material is solidified, the surface thereof may be coated with another conductive material.
Further, after the substance is solidified or coated with the other conductive substance, an insulating region having an opening may be formed on the surface thereof.
The insulating region may be formed by covering an insulating layer.
The insulating layer is coated on both the region where the insulating quantity group is to be formed and the region where the opening is to be formed, and the insulating of the region where the opening is to be formed after the insulating layer is coated. This may be done by removing the layer.
The insulating layer may be a photoresist layer, and the opening may be formed by exposing the photoresist with a laser and developing after the exposure.
The insulating layer may be formed with the opening.
The insulating layer may be coated by nano ink printing.
The insulating layer may be coated by reacting only a portion irradiated with the beam by vaporizing a substance that becomes an insulator when reacted.
According to still another aspect of the present invention, the contact pressure is maintained by feedback while the spherical surface of the contact portion of any one of the contact probes is in contact with the surface on which the thin film on the sample is provided. There is provided a non-destructive contact formation method between the thin film and the contact probe that does not perform any control.
According to still another aspect of the present invention, while the spherical surface of the contact portion of any of the contact probes is in contact with the surface on which a thin film is provided on the sample, the contact portion is placed on the sample. There is provided a non-destructive contact formation method between the thin film and the contact probe that does not move relatively along the surface of the contact probe.
According to still another aspect of the present invention, in the contact forming method in which the surface of the spherical surface of the contact portion of any one of the contact probes is brought into non-destructive contact with a surface on which a thin film is provided on a sample, A nondestructive contact formation method between the thin film and the contact probe is provided, wherein the contact surface to be contacted has a radius of 1 μm or more.
According to still another aspect of the present invention, at least a part of the spherical surface of the contact probe is an insulating region having an opening having a desired area, and the non-destructive contact is made through the opening. Any of the above contact formation methods is provided.
Here, the diameter of the opening may be 100 μm or less.
The insulating region may be a region covered with an insulating layer.
A plurality of the contact probes may be used to form non-destructive contacts between the thin film and the plurality of contact probes.
According to still another aspect of the present invention, after forming one or a plurality of films, the contact is formed by any one of the non-destructive contact forming methods, and a desired measurement is performed. A measurement method in the manufacturing process of the multilayer film forming the film is provided.
According to still another aspect of the present invention, a prober using one or a plurality of the contact probes is provided.

  According to the present invention, an electrical contact can be reversibly formed on a film having a thickness of nm without destroying the film. Therefore, electrical characteristics evaluation can be performed without producing wiring and electrode pads. In addition to being able to significantly reduce the time, various evaluations and measurements such as band alignment evaluation by XPS, internal photoelectric effect and electromotive force measurement can be performed in the same manner. Furthermore, since contact in the elastic deformation region is possible, measurement without leaving a trace on the sample to be contacted becomes possible. In other words, if the contact is completely non-destructive and reversible, it is possible to continue laminating the film after the characteristic evaluation, and in-situ feedback to optimize the film forming conditions and monitoring during the film forming are also possible. Thereby, it becomes possible to contribute to the improvement of the development cost and the manufacturing yield. Furthermore, when actually used as a component of a device, the film to be contacted in the present invention is most often used in combination with other materials such as an electrode instead of the film material alone. Therefore, selection of a combination of a film material and a material such as an electrode is also an important parameter in device design. According to the present invention, by considering the material of the contact probe as an electrode material, it is possible to find an appropriate electrode material by changing the probe material instead of actually manufacturing a device. In addition, since the contact area between the contact portion and the electrical contact object can be easily made constant, reproduction of measurement when the contact area, such as measurement of capacitance-voltage characteristics, affects the measured value. The characteristics can be improved, and comparison with other measurement results is facilitated. In addition, this makes it possible to know the contact area without measuring the actual contact area individually, so that the physical parameter value per unit area can be easily obtained from the measurement results that the contact area affects. Become.

The figure explaining the bad influence to the measurement object film | membrane of the contact probe by a prior art. The optical micrograph which shows destruction of the measuring object film | membrane after a measurement with the contact probe of a prior art. The figure explaining an example of the prior art for avoiding the bad influence to the measurement object film | membrane. The figure explaining the other example of the prior art for avoiding the bad influence to a measuring object film | membrane. The figure which shows how to take various electrical contacts which may make a difference in a measurement result. Here, M, M1, and M2 represent metals, I represents an insulator, and S represents a semiconductor. The figure which shows a force curve at the time of making a cantilever contact a sample. The figure which shows the model of a deformation | transformation when the spherical surface of a rigid body is made to contact a flat plate. The figure which shows the outline of the contact probe of one Example of this invention. An overall photograph of an example of a contact probe using gold as the contact material and tungsten as the support material. A photograph of the tip of an example of a contact probe when gold is used as a contact material and tungsten is used as a support material. The figure which shows the structure of the measurement object sample for the verification experiment of the operation | movement of the Example of this invention. The figure which shows the structure of the measurement system for the verification experiment of the operation | movement of the Example of this invention. The graph which shows Pt4f spectrum, Hf4f, and O1s spectrum obtained by the measurement using the contact probe of one Example of this invention. The graph which shows the spectrum corresponding to FIG. 13 obtained by the nonpatent literature 1. FIG. The graph which plotted the peak position of each spectrum shown in FIG. 13 as a function of an applied bias voltage. The graph which shows the peak position corresponding to FIG. 15 obtained by the nonpatent literature 1. FIG. The photograph of the contact part and the circumference | surroundings where Au sphere of the contact probe of one Example of this invention was contacting the sample surface. XPS measurement of this contact portion was performed. The contact micrograph of the contact probe of one Example of this invention and the micrograph of the periphery of the contact part which was contacting the sample surface which has a thin film on the surface. The graph which shows the XPS spectrum obtained from the contact part of FIG. The inset is an enlarged view around the Au 4f peak position, and shows that no peak associated with gold is seen in the XPS spectrum from the contact portion. The conceptual diagram explaining the aspect of the measurement of the internal photoelectric effect and electromotive force which can be performed using the contact probe of this invention. The photograph which shows the mode of operation | movement demonstration of the mechanism which implement | achieves an electrical contact using the contact probe of the Example of this invention in a high vacuum, and the said mechanism using the gold | metal thin film on mica. The conceptual diagram explaining the method of explaining the method of measuring and evaluating for every layer during film forming. The conceptual diagram of the mechanism which forms and cancels | releases the contact of the contact probe and measurement object of this invention by one operation | movement. The conceptual diagram of the multi-contact probe measurement using the contact probe of this invention. The conceptual diagram of the aspect which performs multi-contact probe measurement with respect to the patterned thin film. The conceptual diagram of the aspect which performs multi-contact probe measurement, taking back contact. The figure which shows notionally an example of the method of producing the contact probe with an opening which limited the contact area. The optical microscope photograph of the opening periphery of the contact probe with an opening of sample numbers # 1-1 to # 1-6 shown in Table 1. 5 is an optical micrograph of the periphery of the apertures of contact probes with apertures of sample numbers # 2-1, # 2-3, and # 2-5 shown in Table 1. Optical micrographs of the periphery of the opening before and after post-baking of the contact probes with openings of sample numbers # 2-2, # 2-4 and # 2-6 shown in Table 1.

[Principle for realizing non-destructive contact]
First, the principle of realizing electrical contact without destroying a film having a thickness of nm will be described. “Electric contact” means physically what it means. For simplicity, consider that there is “electrical contact” between two metals. In this case, the electron distribution of the two metal surfaces is sufficiently overlapped so that the electrons can freely move back and forth, and the Fermi level is aligned, which is an “electrical contact” situation. This situation can be realized with an atomic force microscope (AFM). Note that electrons travel through the tunnel under the measurement conditions of the scanning tunneling electron microscope, but the Fermi level does not spontaneously match (if the Fermi level spontaneously matches, a bias voltage cannot be applied between the tip and the sample. ). In an AFM using a cantilever whose tip is coated with metal, an ohmic behavior is observed when the current-voltage (IV) characteristics are measured while the tip is close enough to exert a repulsive force against the metal sample surface. It can be seen that “electrical contact is made” between the sample and the tip of the chip. Even in the repulsive force region, when the force curve returns to the original position (is elastically deformed), the contact AFM is regarded as a nondestructive measurement (see FIG. 6). That is, atoms are close to each other so that repulsive force acts between the two materials, but non-destructive electrical contact can be made by realizing a state in which they are elastically deformed and return to their original state when the force is removed.

  However, it is unrealistic to use AFM to measure the electrical characteristics of an ultrathin film that is uniform in the order of microns in the film surface direction. This is because in the AFM, the region to be electrically contacted is at the atomic level, and a precise force feedback mechanism and vibration isolation mechanism are required, and a problem of quantization conductance may occur (non- Patent Document 2). As a probe for measuring the electrical characteristics, a probe that contacts the sample in a relatively wide area and disperses the force (no need for precise force feedback) and that fits in the elastic deformation area in the depth direction is required.

Therefore, the repulsive pressure regarded as non-destructive measurement in AFM is calculated. When the sample surface is brought close to contact with the probe using a cantilever having a spring constant of -3 [N / m] with respect to Cu, and the sample is further pressed to the probe by about 5 nm as shown in FIG. The force curve overlapped between the approach and retract, and it was found that repulsive force was acting on the sample but it was elastically deformed. The radius of curvature of the contact portion at the tip of the cantilever is 25 nm or less, and the radius of the circle where the cantilever is in contact with the sample is estimated to be about 10 nm from the spatial resolution of the image due to the atomic force in the contact mode measured using the cantilever. The That is, a force of 3 [N / m] × 5 [nm] is applied to the contact area π × (10 nm) ² . Therefore, the repulsive pressure is {3 [N / m] × 5 [nm]} / {π × (10 nm) ² } to 5 × 10 ⁷ [Pa]. Since the yield strength of a general inorganic material is about 1 × 10 ⁸ [Pa], the result of a force curve that is elastically deformed in this repulsive force range is reasonable. In the above, “When the sample is pressed to about 5 nm on the probe” is written, but this “5 nm” corresponds to the deflection of the cantilever and depends on the elasticity of the sample. This is considered to be considerably less than 5 nm. Here, consider a model in which a rigid sphere having a radius r as shown in FIG. 7 is brought into contact with a flat plate that can be deformed by pressure. If the above conditions are put into the relational expression of the radius of curvature r of the contact portion at the tip of the cantilever, the radius y of the circle of the contact surface and the depth of penetration x, which is the equation shown in FIG. It will be slightly less than 2 nm. The actual depth of penetration depends on the elastic modulus, film thickness, and form of the sample, and varies greatly depending on the sample. Furthermore, when the cantilever contact portion on the spherical surface is pressed against a flat sample, the deformation of the spherical surface is considered to be greater if both have the same elastic modulus. It is thought that it is often a small value. Therefore, the depth of penetration is not a very essential parameter.

Next, it is examined based on the model shown in FIG. 7 whether or not the force in the pressure range obtained above can be realized without precise feedback with a contact probe whose contact surface radius is in the micron order. First, since the contact portion of the contact probe of the present invention has a substantially spherical shape, the spherical contact portion cannot be made extremely small in diameter even in consideration of its manufacture and handling. Further, even when considering the normal material of the spherical contact portion and the sample to be contacted, it is not usually necessary to consider that the material deforms greatly with a slight contact pressure. Therefore, it can be considered that the practical minimum circular radius of the contact surface is also in the micron order, that is, 1 μm. If the flat plate is deformed by this contact pressure and the sphere enters only x, and the sphere and the flat plate come into contact with a circle having a radius y, the relationship between r, x and y is r ² = (r− x) ² + y ²
It can be expressed as. For example, when the radius of the circle of the contact surface is 100 μm, the force for applying the pressure obtained above is 5 × 10 ⁷ [Pa] × {π × (100 μm) ² } to 1.5 [N]. The vertical deflection when a load of 50 [N] is applied to a thin plate spring with a thickness of 0.5 mm that is commercially available as a holding spring is about 30 mm (spring constant: 2 × 10 ³ [N / m]). When a force of .5 [N] is applied, the amount of deflection is about 1 mm, and the deflection can be sufficiently detected visually. That is, the pressure in the elastic deformation region can be applied to the sample by pressing the contact probe against the sample to the extent that it begins to bend visually. Actually, a spring having a smaller spring constant, such as a thinner plate spring or a wire-like spring instead of a plate shape, is used as the support for the contact probe, so that a larger deflection can be obtained with the same load. Therefore, it can be considered that electrical contact can be easily made by bringing the contact probe into contact with the sample within the range of repulsive force that elastically deforms without precise feedback.

Here, if the range of the required spring constant is obtained, the following relational expression π × 10 ¹⁰ [N / m ² ] is assumed, where the radius of the contact surface (circular) is y [m] and the spring constant is k [N / m]. ] ≦ k / y ² ≦ 5π × 10 ¹¹ [N / m ² ]
It is necessary to satisfy. On the other hand, when considering the radius y of the contact surface, the lower limit may be 1 μm as described above. As for the upper limit, if the radius y exceeds 100 μm, the contact surface tends to be non-uniform, and the curvature radius of the contact portion is considered because the deformation amount is not so large with the normal material of the contact portion and the sample. Is extremely impractical and may interfere with measurement, and further, device evaluation for measuring by passing a current may cause an excessive current value. Therefore, the range of realistic contact surface radius y is 1 μm ≦ y ≦ 100 μm.
It can be. Accordingly, the range of the spring constant k that satisfies the above relational expression and the range of the radius of the contact surface is as follows.
π × 10 ⁻² [N / m ² ] ≦ k ≦ 5π × 10 ³ [N / m ² ]
This spring constant range overlaps with the spring constant range of cantilevers used in atomic force microscopes, but has a slightly larger value, and the conventional cantilever-type electrical contact contacts used in electromagnetic relays. The value is two orders of magnitude or more smaller than the spring constant. Also, since the straight needle-like probe used in conventional probers is not considered as a spring, its spring constant is not usually published as a specification, but from the conventional cantilever-type electrical contact contacts Is considered to have a higher spring constant.

  Although the specific confirmation method by visual observation of the above-mentioned vertical deflection is not limited to this, for example, there is the following method. First, the position of the contact probe is fixed, and the sample is raised so that the upper surface of the sample to be contacted approaches the spherical contact at the tip of the contact probe. When the contactor or any member that is directly interlocked with the contactor is watched, the contactor position of the contact probe does not change because the contactor of the contact probe is not in contact with the sample at first. When the spherical surface portion of the contact is in contact with the sample and the sample position is still raised, a repulsive force due to deformation of the spring portion to which the contact is connected is applied between the upper surface of the sample via the spherical portion, The upper surface of the sample is elastically deformed. On the other hand, the rise of the sample position after the contact lifts the contactor upward, so by keeping the spring constant of the spring part sufficiently small, the deformation of the top surface of the sample is on the contactor while it is in the elastic deformation region. The amount of movement becomes a size that can be visually detected.

  The direction of relative motion between the contact and the sample upper surface is such that a force in a direction parallel to the sample upper surface is not substantially applied between the two due to this relative motion after the contact between the contact and the sample. The direction is preferred. Specifically, the movement direction of the contact is constrained by the spring portion, and it is preferable that the direction of the constrained movement is parallel to the relative movement direction of the contact and the sample. This is because if this parallel force is applied, the contact may slide on the upper surface of the sample and damage the membrane, and even if no sliding occurs, the force parallel to such a membrane surface This is because it is preferable to suppress this parallel force to such an extent that such an adverse effect can be almost ignored.

  Alternatively, various methods for detecting a small amount of deviation of a member using other means such as optical and electrical, and a specific apparatus configuration for realizing the same, without relying on visual observation, are well known. Therefore, it is naturally possible to adopt such existing technology.

  Regarding the sample on which an extremely thin film as a main object to be contacted by the contact probe of the present invention is formed, the elastic deformation region is considered to be approximately 5 nm or less, but the vertical direction described above using numerical examples From the calculation result of the deflection and the like, if the sphere enters the sample by about 5 nm, the above-described vertical deflection can be sufficiently detected visually without performing any control such as feedback. In practice, the degree of elastic deformation of the sample is often dependent on the elastic modulus and thickness of the sample, and there is little direct quantity relationship with the vertical deflection of the support. Therefore, it is not appropriate to take the amount of elastic deformation as a direct indicator of whether or not a contact is formed by the contact probe of the present invention and whether or not it can be detected. For example, in the case of the five-layer graphene described in the embodiment of the present invention described below, it is considered that the elastic deformation of graphene at the time of contact formation is considerably smaller than 1 nm, but still sufficient electrical contact is obtained. In addition, the vertical deflection of the support could be sufficiently detected visually.

  Such a contact member (contact probe) is different from a normal cantilever-like contact probe having a uniform structure as a whole, and the thickness of the layer to be measured on the sample to be measured ( Compared with the thickness (nm thickness), the contact between the spherical contact surface and the specimen with a sufficiently large radius of curvature and the spring member, such as a thin plate or thin wire, which is easy to bend, are distinctly different from each other, and each has a simple shape and requirements. It has two elements with the function to be performed. Therefore, optimization such as employing an optimal material and size for each element is facilitated.

  Here, the difference between the cantilever used in the AFM and the contact probe of the present invention will be further described. As described above, the AFM is not only a contact surface area much smaller than that of the contact probe of the present invention, but is also used with the contact probe of the present invention in that it is brought into contact with an appropriate contact pressure while applying feedback. Are essentially different, the required length of the support is quite different. Since the AFM cantilever controls the position and pressure by applying very fine feedback, it is necessary to reduce its mass as much as possible. In addition, if it is long, the cantilever is susceptible to various disturbances. Is used. Specifically, the AFM cantilever that is usually available has a length of about 500 μm at most.

  On the other hand, in the contact probe of the present invention, a short support length is disadvantageous in actual production, for example, if the length of the support is set to a value as short as AFM, it becomes very difficult to make. In addition, since the feedback for maintaining the contact pressure at an appropriate value is not performed for the contact, the support cannot be shortened so much because the deflection of the support needs to be increased to some extent as described above. . For example, if the support length is 500 μm, which is the upper limit of the normal AFM cantilever length, in order to bend the tip of the support by about 1 mm as described above, the change in angle between the support and the sample surface is considerably large. (The angle change is much closer to 90 degrees than 0 degrees). When such a deflection is applied to the support, the spring constant greatly changes between the initial deflection position and the final deflection position. Furthermore, even if only a vertical force is applied between the contact area and the top surface of the sample at the beginning of the deflection, the force component parallel to the top surface of the sample increases as the deflection increases. In addition, the contact portion slides on the upper surface of the sample unless the sample is translated in the direction of the upper surface in accordance with the amount of deflection. Therefore, a short support length is very disadvantageous in that it makes non-destructive contact with the upper surface of the sample. Therefore, in the contact probe of the present invention, it is desirable that the length of the support is sufficiently longer than the maximum deflection distance of the support tip. Specifically, it is usually desirably 10 mm or more, and the lower limit is 2 mm, preferably 3 mm, and more preferably 5 mm even considering special applications and usage conditions. The upper limit of the support length is theoretically not particularly limited, but from the actual use environment of the contact probe (for example, used in a narrow space in a vacuum chamber, used with other equipment, etc.) If it is longer than about 10 cm, it is considered that practicality is lost.

  Since the above-described analysis is based on the model shown in FIG. 7, inconvenience may occur in a situation greatly deviating from this model. Specifically, the sphere in contact with the flat plate needs to be a smooth spherical surface at least on the contact surface with the radius y. If this part is uneven, stress concentrates on it, causing irreversible deformation of the flat plate (specifically, a thin film with a thickness of nm), or the uneven part scrapes the sample surface, or conversely the spherical surface The material may peel off and adhere to the sample side, which may adversely affect the sample to be measured. That is, two are important: a smooth curved surface with no stress concentration and a certain contact area (a contact area that disperses pressure to such an extent that the deflection of the support can be visually observed without destroying the sample).

  Furthermore, there is also a demand that the area (contact area) in which electrical contact is actually made in the contact region should be constant or that the contact area should be known. For example, when measuring capacitance-voltage characteristics (capacitor characteristics, MOS characteristics), a measurement value proportional to the contact area is naturally obtained, but the value to be known is often the capacitance per unit area. However, it is often difficult to actually measure the contact area. Alternatively, even if a value per unit area is not necessarily required, the measurement may be affected by the contact area. For comparison between measurement results, the contact area must be measured each time (for the same contact probe). It is desirable that it is guaranteed to be constant (when used repeatedly or when the contact probe used is replaced). In particular, in the case of contact between a smooth curved surface having a relatively large radius of curvature and a surface having a certain degree of elasticity as in the present invention, it is necessary to consider that the contact area changes due to a slight difference in conditions. There is.

In order to ensure that the actual contact area in the contact region is constant or known, at least the region of the contact region that is scheduled to be contacted is made insulative (of course this way In this case, an opening may be provided in the insulating region and contacted with the object to be measured through the opening. Thereby, a contact area is controlled by the area of this opening part. Of course, the method for manufacturing the contact region having the opening is not limited to this. Although there is no intention to limit to this, if other methods are exemplified, the portion other than the opening is coated by printing with nano ink or the like, and the material that becomes an insulator when reacted reacts to irradiate the beam By reacting only a part, the opening can be formed by coating other than the opening. Specifically, for example, an oxygen beam is irradiated in a vacuum apparatus into which a gas containing a metal element such as titanium chloride (TiCl ₄ ) or trimethylgallium is introduced, and only a portion where the beam is irradiated is very thin amorphous. It can be realized by a method such as forming an insulating film. Alternatively, an organic insulating film with an opening can be formed by depositing organic molecules and irradiating an electron beam or light to cause a polymerization reaction only in the irradiated portion.

  The size of the opening is preferably smaller than a minute region where the contact region and the measurement object are predicted to actually come into contact when no insulating region is provided. A method for forming an insulating region having a desired size and shape on a conductive region is a technique established in the area of microfabrication technology, and a suitable method may be appropriately employed as necessary. Also, the size of the opening is usually much smaller than the radius of curvature of the spherical surface near the opening, so that the surface of the conductive contact exposed from the opening does not interfere with the surface to be measured. In addition, the thickness of the insulating region (insulating film or the like) is preferably sufficiently thin. In addition, it is preferable that the insulating region is sufficiently flexible for the purpose of preventing damage to the measurement object during contact. Specifically, it is desirable that the material is softer than the material (Au or the like) that is the base of the insulating region. Since the contact area is regulated by the opening, it is usually necessary to assume that the insulating region around the opening is in contact with the surface to be measured. For this reason, although depending on the usage, such as the object to be measured and the required number of repeated use, a certain degree of strength is often required for the insulating region. In the embodiment described below, a desired position on the resist film formed in the contact region is exposed with a desired shape and size using a laser, and then developed, so that the diameter is sufficiently controlled. A resist film provided with an opening was formed on the contact region. Of course, any other method may be adopted. The shape of the opening may be other than a circle.

  In the case of a contact between a metal and a semiconductor or an insulator, even if “electrical contact can be made”, it often does not become ohmic behavior, but if the Fermi level is aligned, “electrical contact can be obtained”. It can be said. Therefore, the “electrical contact” realized by the present invention means that the Fermi level is uniform.

  Further, in the above description of the principle of the present invention, not only does the destruction not occur, but the contact is made at most in the range of elastic deformation with respect to the sample to be measured, that is, the contact is not caused by plastic deformation. Once released, the sample was described as fully returning to the state prior to contact. However, a contact mode in which plastic deformation remains on the sample surface although no fracture has occurred is also sufficiently useful depending on the purpose and application field. Therefore, in the present application, the terms such as “non-destructive” and “without breaking” represent cases where plastic deformation remains unless otherwise specified.

  “The“ nm thickness ”in the present application refers to a thickness of less than 50 nm, for example, 20 nm or less, 10 nm or less, 5 nm or less. The lower limit of the film thickness is preferably 1 nm.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, it cannot be overemphasized that this invention is not what is limited to a following example.

[Production of contact probe]
A small amount of wire of contact material such as gold is entangled with the wire tip of a material that becomes a support such as tungsten in the form of a hairpin, and the two ends of the support wire are connected to current introduction terminals, respectively. This is connected to a vacuum vessel and evacuated to a high vacuum region (about 10 ⁻⁶ Torr). The current introduction terminal is connected to a constant current voltage source, and a current is passed through the wire (Joule) to heat it. The temperature of the wire tip is raised to the melting point of the contact material, and the contact material is melted. Because the molten contact material is not in contact with other parts, the surface tension makes the surface very smooth and spherical (of course, due to gravity, wettability between the molten contact material and the wire material and other effects, Although it does not become a spherical surface, in this application, even if there is such a case, it will be called a spherical surface even if there is a slight deviation from the true spherical surface as long as the purpose and effect of the present application are achieved. By stopping the current in this state, the molten contact material solidifies while maintaining a very smooth surface state. The wire in which the spherical contact material thus produced is fused is used as a contact probe, and is brought into contact with the laminated film to form an electrical contact. When the contact surface of the contact material is very smooth and does not damage the laminated film when it contacts the laminated film, the metal sphere is brought into contact with the support wire. Do not destroy.

  FIG. 8 shows a conceptual diagram of an example of a contact probe manufactured as described above. The contact shown here is obtained by welding a gold sphere (Au sphere) as a metal sphere to the tip (folded portion) of a hairpin-shaped tungsten wire (W wire). The reason why the wire is bent is that a cantilever structure is obtained in which an Au sphere is mounted on the tip and supported by two flexible and easily bent W wires. A contact probe having such a cantilever structure can easily replace a conventional probe in a prober or the like. It is also advantageous in that the position of the metal sphere can be easily controlled by tangling a wire such as Au to the bent portion of the hairpin structure for welding. Note that the contact probe has a pure cantilever configuration in which supports such as two W wires extend from the contact in the same direction as hairpins, and these supports can be regarded as a single beam. There is no necessity. For example, the hairpin can be in any shape according to the usage and production convenience, such as when the hairpin legs are open, that is, the two supports are not parallel but extend in different directions. Although there is no intention to limit to a specific shape, as an example other than the above shape, two wires are entangled into a single shape, which is in the middle of a wire that is almost straight. Examples include shapes with contacts. Further, after the contact is formed, one of the wires is cut, or the contact is actually cantilevered with only one wire by attaching the contact to the tip of one wire by a method other than the above. Other shapes are also possible.

  The specific shape of the contact probe produced in this way is the melting point and amount of the contact material, the diameter of the support, the surface tension of the molten contact material and the wettability to the support, the heating temperature and the heating time, etc. FIG. 9 and FIG. 10 show an overall photograph of an example of a contact probe and a photograph of its tip when gold is used as the contact material and tungsten is used as the support material, respectively. Note that tweezers are also shown in the overall photograph of FIG. 9 in order to make it easy to understand the size of an example of the contact probe. Further, it can be seen from FIG. 10 that the surface of the metal (gold) sphere is very smooth.

  As shown in the example above, the most common contact material is gold and the most common support material is tungsten. Actually, a contact probe was produced in the system shown in the table below.

  In the above method, the melting point of the contact material needs to be much lower than the melting point of the support material. However, platinum or the like is also conceivable as a contact material. If you want to use a material with a high melting point, such as platinum, as a contact material, form a sphere with a very smooth surface fused with a relatively low melting point gold, etc. By coating the material thinly by sputter deposition or the like, any material can be used as a contact material while maintaining a spherical shape with a smooth surface.

[Demonstration of electrical contact]
In order to demonstrate that the contact probe produced in this way can make an electrical contact equivalent to that of a semiconductor prober or tester used for a thick film, The experiment was conducted.

  The sample used for the experiment is a MOS sample having the structure shown in FIG. 11 which is prepared for the bias application XPS experiment shown in Non-Patent Document 1. In the sample of FIG. 11, a 4 nm Pt film was provided as the uppermost layer, but the left end portion was 60 nm thick. In the bias application XPS experiment conducted in Non-Patent Document 1, an electrical contact was obtained on the 60 nm thick Pt film through an Au-coated CuBe spring plate. In the experiment of Non-Patent Document 1, various bias voltages are applied between the Pt film and the Si substrate on the lower surface of the sample to acquire XPS spectra, and the bias dependence of the binding energy of each element of the MOS component is measured. Thus, it has been demonstrated that an electrical contact without contact resistance is obtained between the Au-coated CuBe spring plate and the 60 nm-thick Pt film. In the embodiment of the present application, not the portion of the Pt film having a thickness of 60 nm, but on the Pt film having a thickness of 4 nm for XPS measurement (shown as “contact point” in FIG. 11), as illustrated in FIG. An electrical contact was taken using a contact probe using Au sphere as a contact material and tungsten wire as a support, and placed in an XPS apparatus to measure bias application XPS. The measurement system configuration is shown in FIG. The measurement procedure, conditions, and the like are the same as in the experiment of Non-Patent Document 1 performed by making electrical contact through an Au-coated CuBe spring plate on a 60 nm thick Pt film. Since the present invention is not the XPS measurement method itself, details of the conditions of this experiment will not be described any more, but if necessary, refer to Non-Patent Document 1.

FIG. 13a) shows the Pt 4f spectrum, Hf 4f, and O 1s spectrum when a bias voltage is applied to the Si substrate side with the Pt film side as the ground. FIG. 13b) shows the Pt 4f spectrum, Hf 4f, and O 1s spectrum when a bias voltage is applied to the Pt film side with the Si substrate side as the ground. FIG. 14 shows the measurement results shown in Non-Patent Document 1, that is, the measurement results corresponding to those shown in FIG. 13 when electrical contact is made through the Au-coated CuBe spring plate on the 60 nm thick portion of the Pt thin film. Indicates. FIGS. 15a) and 15b) are graphs in which the peak positions of the respective spectra shown in FIG. 13 are plotted as a function of the applied bias voltage. FIG. 16 is a graph corresponding to FIG. 15 shown in the non-patent literature, as in FIG. Similar to the result on the Pt film having a thickness of 60 nm in Non-Patent Document 1, when the potential on the Pt side is always grounded, the peak position of Pt 4f does not depend on the bias voltage. This indicates that an electrical contact having no contact resistance is obtained between the contact probe fabricated this time and the 4 nm thick Pt film. Further, these results show that the XPS measurement position is away from the contact point, so that the continuity of the film is not impaired by the contact being cracked in the 4 nm thick Pt film. . Furthermore, the result that the deviation from the ideal band alignment obtained from the difference in bias voltage dependence of the peak positions of Pt 4f, Hf 4f and O 1s is about 30% of the applied voltage at the interface of the Pt film and the HfO ₂ film, The result was the same as that on the 60 nm thick Pt film. From these results, it was demonstrated that non-destructive and sufficient electrical contact was obtained by using a contact probe in which the Au sphere produced here and a tungsten support were combined.

[Confirmation of no contact contamination]
Contact with the contact probe was released from the MOS sample used in the above-described experiment, and the surface composition of the portion where contact occurred was examined by XPS. FIG. 17 shows a photograph of the contact portion where the Au sphere of the contact probe was in contact with the sample surface and its surroundings. As shown in the XPS spectrum in FIG. 19, no gold photoelectron peak of the contact probe was detected from the contact portion. This result shows that there is no contamination due to the substance at the tip of the contact probe adhering to the sample surface even when the contact probe of this example is brought into contact with the sample. As a result, even if the measurement is performed on the film formed at that stage during the device fabrication, and the device fabrication process is continued thereafter, the measurement during the device may adversely affect the operation of the final device. There is no.

[Confirm that contact does not destroy the film]
FIG. 2 shows a photograph of an example of film destruction on the sample surface according to the prior art. Here, a comparative experiment was conducted on the contact probe of the present invention. That is, in the above [Electrical contact verification], an electrical contact verification test is performed on the contact probe of the present invention. Next, in [Confirmation that there is no contamination due to contact], the contact of the contact probe is released and contamination occurs The sample after confirming the absence was photographed with an optical microscope. The result is shown in FIG. FIG. 18 was taken with the same optical microscope as in FIG. 2, but, as can be seen from the image of the contact point of the Au sphere (indicated by the dashed circle in the upper left of the figure), the trace of contact was not found at all. It wasn't.

[Application / Modification]
The novel contact probe of the present invention described above can be used for nondestructive measurement, for example, by mounting in place of a tungsten probe conventionally used in a semiconductor prober.

  In the above embodiment, Au is used as the material of the contact portion. However, as already described, various other materials such as Cu, Al, Pt, etc. can be used. After a smooth spherical surface used as a contact portion is formed, it can be used as a contact probe as it is, or coating can be performed on the spherical surface. By coating, almost all materials can be used as contact materials.

  Furthermore, even before the electrode is formed on the measurement target side, the contact material itself on the contact probe side is brought into contact with the sample as the same material as the element such as the electrode to be formed on the measurement target side sample, This contact material itself can be evaluated as a part of the device (that is, an electrode or the like that should originally be formed on the device side).

  For example, when the gate metal is used as the contact material, CV measurement can be performed even if the gate metal is not patterned or the gate insulating film has a hole. If the electrode metal is used as a contact material, the electrode metal dependency of the ReRAM operation can be easily measured.

  As another example of the measurement that can be performed using the contact probe of the present invention, for example, the internal photoelectric effect measurement whose conceptual diagram is shown in FIG. 20 (a) and the conceptual diagram thereof are shown in FIG. 20 (b). There is a measurement of electromotive force. In FIG. 20, the sample to be measured is metal 1, semiconductor 2, metal or semiconductor 3 (other combinations are also possible). Although not shown, the sample to be measured has more layers, so that there may be more metal / semiconductor interfaces and semiconductor / semiconductor interfaces than in the case shown in FIG. A contact (front contact) is taken from the upper surface of the sample having such a configuration with the contact probe of the present invention, and a contact (back contact) is taken on the lower surface of the sample by another means. In this state, while changing the energy of light applied to the sample, the amount of electrons excited by light is measured from the current, and the threshold energy at which the photocurrent flows is measured (FIG. 20A). Alternatively, while changing the energy of the irradiated light, a bias voltage is applied so that no current flows, and the photovoltaic force is measured from the voltage (FIG. 20B), and the measurement is performed. In addition, as a mechanism for generating voltage, various voltages are generated such as photoelectromotive force in the case of light irradiation, thermoelectromotive force in the case of heat (heating and cooling the sample), and electromotive force of the battery in the case of chemical reaction. There is a mechanism, and this method can be applied regardless of the voltage generation mechanism. Throughout this application, V represents a voltmeter or voltage source, and A represents an ammeter or current source. In FIG. 20 (a) and FIGS. 24 (a) and 24 (c) described later, the voltmeter / voltage source V and the ammeter / current source A are connected in series between the two terminals. Although this does not necessarily mean that they are physically connected in series, the voltmeter / voltage source V and the ammeter / current source A function together between the two terminals. Note that it means connected appropriately. For example, when V is a voltmeter and A is a current source, the voltmeter V and the current source A are physically physically parallel so that both function normally between two terminals. Connected to.

  In order to use the contact probe of the present invention to reversibly contact a measurement object while maintaining a vacuum state, for example, a mechanism shown in the photograph in FIG. FIG. 21 (a) The mechanism on the right side is attached to the vacuum chamber so that the bar-like portion visible at the center enters the vacuum chamber. The contact probe of the present invention is attached to the tip of the rod-like portion, and wiring for electrically connecting the tip of the contact probe to an external measurement system is provided. With this mechanism attached to the vacuum chamber, the rod-like part to which the contact probe is attached can be operated from the outside of the vacuum chamber, and by doing this, the rod-like part is put in and out, the tip part is swung, etc. Control the position of the contact probe. Thereby, it is possible to perform measurement using the contact probe while maintaining the vacuum state in the vacuum chamber.

  Once the vacuum is lost, it takes a long time to return to the original vacuum state. Therefore, using such a mechanism greatly improves the measurement efficiency. In addition, if this mechanism is incorporated in a film forming apparatus, the characteristics of each stack can be evaluated during film formation by utilizing the property that non-destructive measurement can be performed even on an extremely thin film by the probe contact of the present invention. Will be able to do. In FIG. 22 schematically showing such an evaluation, by forming contact with the surface of L3 with the contact probe of the present invention at the time when L1 to L3 are formed in the middle of the formation of the laminated film composed of L1 to L5, The layer structure created up to this point is being evaluated. Even if this evaluation is performed, the layers L1 to L3 to be evaluated have not been destroyed. Therefore, by continuing the stacking of the layers L4 and L5 after the evaluation is completed, the stacking of the L1 to L5 that is not affected by the evaluation A structure is obtained. In this way, when performing measurement / evaluation in the middle of the process of forming a multilayer structure, that is, when only a part of the film is formed, it is possible to perform measurement while maintaining the vacuum state. It is extremely important to prevent oxidation and contamination of the intermediate layer structure.

  In order to demonstrate that sufficient contact can be made between the contact probe of the present invention and the sample to be measured using the mechanism shown in FIG. 21 (a), a gold thin film is deposited on the mica surface, This mechanism was used to contact the gold thin film with the contact probe. As shown in FIG. 21 (b), the measurement result that the electrical resistance due to the contact between the gold thin film probe and the gold thin film was 0 was obtained by this operation.

  The mechanism shown in FIG. 21 can control the position of the contact probe with a very high degree of freedom. However, when the position of the sample to be contacted with the contact probe is fixed, the degree of freedom of position control may be small. A simplified mechanism can be used. A conceptual diagram of an example of such a simplified mechanism is shown in FIG. As shown in the figure, a structure is provided in which two members can pivot around one axis like a hinge. The contact probe of the present invention is attached to one of these members. By urging this member, the member is swung between a position in contact with the sample as shown in FIG. 23 (a) and a state not in contact with the sample as shown in FIG. 23 (b). be able to. In order to bias such a member, for example, various actuators may be appropriately installed.

  The contact probe described above uses a single contact probe from the upper surface of the substrate to be measured and the other electrode from the lower surface of the object to be measured without using the contact probe of the present invention. It was to make contact. However, instead of the contact from the lower surface, contact can be made by using the contact probe of the present invention at two places on the upper surface of the measurement object, as schematically shown in FIG. Alternatively, as shown in FIGS. 24B and 24C, four-terminal measurement can be realized by making contacts from four positions on the upper surface (in this way, measurement can be performed by taking a plurality of contacts). This is hereinafter referred to as multi-contact probe measurement). In this way, the electrical characteristics of a very thin metal, graphene, molybdenum disulfide, or other film on the insulator itself can be measured by multi-contact probe measurement in which multiple contacts are made from the upper surface of the measurement object. Note that V and A in FIG. 24 and their connections are as already described in detail in the description of FIG.

  Further, when a patterned thin film is a measurement target, as schematically shown in FIG. 25, electrical characteristics across the interface in the plane parallel direction can be realized by multi-contact probe measurement. In other words, these contact probes are arranged so that the required portions of the patterned thin film are in contact with the contact probes of the present invention, and a voltmeter, a voltage source, an ammeter, and a current source are arranged on these contact probes as necessary. Etc. can be connected to perform various measurements.

  Of course, in addition to such contact from the upper surface side of the measurement object, simultaneous contact can be made from the lower surface as necessary. That is, FIG. 26A schematically shows a case where one contact is made from the upper surface side and one contact from the lower surface side, as in the configuration shown in FIG. As shown, in addition to the contacts on the lower surface side, it is of course possible to take two or more contacts from the upper surface side.

  When the contact position to the measurement object is determined in advance when performing the multi-contact probe measurement as described above, each contact probe is positioned so that each contact probe contacts the contact position. A multi-contact probe assembly can be prepared. Of course, contacts may be made at necessary contact positions by individually setting the position of each contact probe.

The present invention can be widely applied not only to the kind of materials that have been widely used in semiconductor devices, but also to contact in general for thin films. For example, in the layout of FIG. 24A, the distance between the contact probes was about 1 mm, and the electrical resistance of the five-layer graphene transferred and formed on sapphire by a chemical method was measured. As a result, the electrical resistance was about 3 kΩ, and the calculated electrical resistivity was about 8 × 10 ⁻⁶ [Ωm]. According to Non-Patent Document 3, the electrical resistivity of graphite corresponding to an infinite layer of graphene is 4.0 × 10 ⁻⁷ [Ωm], and 10 layers are produced by reducing a graphene oxide dispersion solution formed on a substrate. The electrical resistivity of the following low-layer graphene is 8.8 × 10 ⁻⁵ [Ωm]. The electrical resistivity of low-layer (10 layers or less) graphene depends on the graphene production method and the number of layers, but the electrical resistivity obtained in this example is obtained by reducing graphite and graphene oxide. It is a value between the produced low-layer graphene, and is considered to be a reasonable value. Therefore, it has been confirmed that the present invention can be applied satisfactorily even when making contact with graphene.

[Contact probe with known contact area]
In order to realize a contact probe with a known contact area, the region where contact is supposed to be made is made insulative including its surroundings, and an opening of a desired area is provided in the inside thereof. Thus, the range in which an electrical contact is actually formed between the contact probe and the measurement object is regulated. In order to make the region insulative, for example, an insulating film can be formed on the region.

  This contact probe was manufactured according to the manufacturing method conceptually shown in FIG. First, a tungsten probe having a diameter of 0.1 mm and a length of about 70 mm was used as a support, and a contact probe having an Au sphere having a diameter of about 700 μm as a contact at the folded portion was produced. Since the method of manufacturing the contact probe itself has already been described, it will not be repeated here. Next, the Au sphere was dip coated with a photoresist solution to apply a thin film (1 μm thickness) of an insulating resist on the surface. Next, when using this contact probe, the contact probe is arranged so that the contact side of the Au sphere is in contact with the object to be measured (in FIG. 27, the tungsten wire support faces upward and the tungsten wire support is substantially horizontal. In this case, a range corresponding to an opening having a desired shape and area (in a specific example, a disk-shaped range having a diameter of 70 μm, 50 μm, and 30 μm) was exposed to the top of the Au sphere). After the exposure, the reaction part of the resist was dissolved with a developer, rinsed with deionized water, and blown with nitrogen to perform post-processing. As a result, the laser-exposed region of the insulating resist thin film was removed, and an opening was formed therein as shown in the lower side of FIG. In order to clearly show that the insulating resist film covers the Au sphere, this film thickness is shown to be considerably thicker than the actual thickness. Therefore, in FIG. 27, the opening is positioned below the edge of the insulating resist film. Looks like. However, in actuality, the thickness of the insulating resist film is as very thin as 1 μm, and the insulating resist film is sufficiently flexible. Therefore, the contact probe manufactured in this way is measured in the manner already described. , Almost all of the Au sphere surface in the opening is in electrical contact with the object to be measured. Therefore, as long as this opening is smaller than the area where the contact probe that does not have an insulating region such as an insulating resist film is actually in contact with the object to be measured, the contact area is constant and reproduced during measurement. The property becomes very good. Further, the edge of the opening contacts the object to be measured, but this edge is made of a resist and is relatively flexible, so that this edge does not cause damage or plastic deformation to the object to be measured.

  In the following, a specific example of the contact probe with an opening produced as described above will be shown. The photolithography process is as follows.

Laser exposure uses a DL-1000 (manufactured by Nanosystem Solutions) as a laser exposure apparatus, a 405 nm semiconductor laser (h-ray) as a light source, and irradiation with 140 mJ / cm ² of laser light at an illuminance of 300 mW / cm ^2. went.

  As the photoresist, ZA5214E (trade name of positive resist) was used. There are two types of resist solutions which are solutions of this photoresist (ZA5114E and ethyl lactate or PGMEA (propylene glycol monomethyl ether, also known as 1-Methoxy-2-propanol acetate)) In a 1: 1 ratio). As the developer, TMAH 238% (an aqueous solution containing 2.38 wt% of tetramethyl ammonium hydroxide (TMAH) sold under the trade name AZ 300 MIF) was used.

  In addition, after applying the photoresist, as a post-treatment after applying the resist, vacuum drying (40 minutes or 3 hours) or heat treatment (110 ° C., 10 minutes, hereinafter referred to as pre-baking) is performed, followed by laser exposure. Went. Furthermore, some samples were subjected to heat treatment (110 ° C., 10 minutes, hereinafter referred to as post-bake) after laser exposure and development.

  In addition, the diameter of the exposure region (hereinafter referred to as the aperture diameter) at the time of laser exposure of the circular region was set to three types of 70 μm, 50 μm, and 30 μm.

  In this way, twelve types of contact probes with openings were manufactured under different conditions. The processing conditions are summarized in Table 2 below.

  Optical microscope photographs around the opening of the contact probe with the opening thus prepared are shown in FIGS. In order to show the correspondence between the photographs in these figures and the samples whose preparation conditions are shown in Table 2, the sample numbers in the leftmost column of Table 2 are shown in the upper right part of each photograph.

  FIG. 28 is an optical micrograph of contact probes produced under the conditions of sample numbers # 1-1 to 1-6. As can be seen from Table 2, these contact probes are not pre-baked but post-baked as post-processing immediately after resist processing, and post-baking or other processing is not particularly performed in post-processing immediately after development. . On the other hand, the contact probes of sample numbers # 2-1, # 2-3, and # 2-5, whose optical micrographs are shown in FIG. 29, were pre-baked, but were subjected to processing such as post-baking immediately after development. Not. Sample numbers # 2-2, # 2-4, and # 2-6 whose optical micrographs are shown in FIG. 30 are both pre-baked and post-baked. In FIG. 30, the left and right columns show photographs before and after post-baking at the same position of each sample, respectively. As can be seen from these optical micrographs, the aperture diameter and the actual aperture size differed slightly due to the difference in post-processing, but almost the same aperture size was obtained under the same processing conditions in any case.

  The contact is made by contacting the metal while holding the contact probe with the opening produced in this way by hand, and the resistance between the metal at that time and the support portion of the contact probe (here, the tungsten wire), It measured using the ohmmeter which can measure to a 0.1-ohm digit. Contact probes that were not pre-baked or post-baked (sample numbers # 1-1 to # 1-6), contact probes that were pre-baked only (sample numbers # 2-1, # 2-3, and # 2-5) ) And the contact probe (sample numbers # 2-2, # 2-4, and # 2-6) subjected to both pre-baking and post-baking, the measurement of the resistance value was specifically repeated, and the durability was examined. As a result, although the resistance value of zero Ω was obtained in any contact probe, the following differences were observed in durability. Due to the difference in processing for the same opening diameter, the durability improved in the order of contact probe in which neither pre-baking nor post-baking was performed → contact probe in which only pre-baking was performed → contact probe in which both pre-baking and post-baking were performed. This is because the resist film becomes stronger as the baking is performed more strongly. Specifically, for example, the pre-baking is performed only before the pre-baking and post-baking are performed, and both pre-baking and post-baking are performed. In addition, even when both pre-baking and post-baking are performed, the strength is higher when the post-baking temperature is higher, and the optimal contact position and angle are manually trial-and-errored for resist films with lower strength. It is considered that the resist film is easily peeled off. Actually, it has been found that, in a contact probe having an opening diameter of 30 μm in which neither pre-baking nor post-baking is performed, a part of the resist film may be peeled off after the durability test. However, the contact probe contact test was performed manually as described above, so the measurement was performed while changing the contact position and angle of the two so that a good contact could be obtained while observing the measured resistance value. For this reason, it was a test under severe conditions for the resist film, such that a lateral force tends to be applied between the contact probe in contact with metal. Therefore, it is considered that the resist film used above is sufficiently practical. Moreover, you may implement | achieve the contact probe with an opening part using another material and another method.

  As described above, according to the present invention, since it is possible to directly contact non-destructively even for a very thin film that can only be contacted there by pulling out a pad in the prior art, The present invention is expected to greatly contribute to the semiconductor field and the like. Of course, there is no intention to limit the present invention to a particularly effective field using the present invention. For example, when searching for a material for an electronic device to be used at a thickness of nm, a stage before detailed analysis of the measurement result is provided. And efficient screening of material candidates. By using the contact probe of the present invention, a very thin film with a thickness of nm can be directly measured non-destructively with a simple procedure. By applying the present invention that enables immediate evaluation when a target film is formed, screening labor, time, and cost are greatly reduced. Furthermore, the present invention is not only for evaluating electrical characteristics as measured by a conventional prober, but also for evaluation applications that do not require quantitative measurement of current values such as checking for disconnection of ultra-thin film wiring and measurement of electromotive force, internal photoelectric effect It can be widely applied to electrical contact applications for evaluation not intended by conventional probers, such as the measurement of Schottky barrier heights by means of the above.

JP 2008-111800 A

M. Yoshitake, K. Ohmori, T. Chikyow, Surf. Interface Anal. 2010, 42, 70-76. Yugo Kawabata, Journal of the Physical Society of Japan Vol.55, No.4, 2000, p.256 Chihiro Shigemoto, Master Thesis (Nihon University College of Science and Engineering, Yamamoto Laboratory, 2011)

Claims (27)

An elastic support that extends in the longitudinal direction and has electrical conductivity;
A contact portion attached to the support, at least a part of the surface having a spherical electrical conductivity;
A contact probe for obtaining electrical contact with the film by nondestructively contacting the surface of the spherical surface of the contact portion with a film having a thickness of nm.   The contact probe according to claim 1, wherein the contact portion is provided at a distal end portion of the support body.   The contact probe according to claim 1, wherein the contact portion includes a coating made of a first material covering at least a surface and a member made of a second material covered with the first material. The contact probe according to claim 1, wherein the spring constant k of the support is in a range represented by the following formula.
π × 10 ⁻² [N / m ² ] ≦ k ≦ 5π × 10 ³ [N / m ² ]   The contact probe according to claim 1, wherein the surface of the spherical surface of the contact portion is a surface obtained by solidifying a dissolved substance.   The contact probe according to claim 1, wherein the support has a length of 2 mm or more.   The contact probe according to claim 1, wherein at least a part of the spherical surface is an insulating region having an opening having a desired area.   The contact probe according to claim 7, wherein the opening has a diameter of 100 μm or less.   The contact probe according to claim 7, wherein the insulating region is a region covered with an insulating layer. Prepare an elastic support that extends in the longitudinal direction and has electrical conductivity,
A substance having a melting point lower than that of the elastic body and electrical conductivity is attached to the support,
Melting the substance by energizing the support,
Solidifying the molten material by stopping energization after the melting;
A method for manufacturing a contact probe according to claim 1.   The manufacturing method according to claim 10, wherein the surface of the substance is coated with another conductive substance after the substance is solidified.   The method for manufacturing a contact probe according to claim 10 or 11, wherein an insulating region having an opening is formed on a surface of the material after the material is solidified or coated with the other conductive material.   The method of manufacturing a contact probe according to claim 12, wherein the insulating region is formed by covering an insulating layer. Covering the insulating layer is performed on both the region where the insulating quantity group is to be formed and the region where the opening is to be formed,
By removing the insulating layer in the region where the opening is to be formed after coating the insulating layer,
A method for manufacturing the contact probe according to claim 13.   The method for manufacturing a contact probe according to claim 14, wherein the insulating layer is a photoresist layer, and the opening is formed by exposure of the photoresist with a laser and development after exposure.   The method of manufacturing a contact probe according to claim 13, wherein the insulating layer is formed so as to have the opening.   The method of manufacturing a contact probe according to claim 16, wherein the insulating layer is coated by nano ink printing.   The method for manufacturing a contact probe according to claim 16, wherein the insulating layer is coated by reacting only a portion irradiated with a beam by vaporizing a substance that becomes an insulator when reacted.   The contact pressure is continuously controlled by feedback while the spherical surface of the contact portion of the contact probe according to any one of claims 1 to 9 is in contact with the surface on which the thin film is provided on the sample. A non-destructive contact formation method between the thin film and the contact probe, which is not performed.   The contact portion is brought into contact with the surface of the sample while the spherical surface of the contact portion of the contact probe according to claim 1 is in contact with the surface on which the thin film is provided on the sample. A non-destructive contact formation method between the thin film and the contact probe, which is not relatively moved along the contact.   The contact is performed in a contact forming method in which the spherical surface of the contact portion of the contact probe according to claim 1 is brought into nondestructive contact with a surface on which a thin film is provided on a sample. A nondestructive contact forming method between the thin film and the contact probe, wherein the contact surface has a radius of 1 μm or more.   The at least part of the surface of the spherical surface of the contact probe is an insulating region having an opening with a desired area, and makes the non-destructive contact through the opening. The contact formation method as described.   The contact forming method according to claim 22, wherein a diameter of the opening is 100 μm or less.   The contact formation method according to claim 22 or 23, wherein the insulating region is a region covered with an insulating layer.   The nondestructive contact formation method according to any one of claims 19 to 24, wherein a plurality of the contact probes are used to form nondestructive contacts between the thin film and the plurality of contact probes. After forming one or more films, the contact is formed by the nondestructive contact formation method according to any one of claims 19 to 25, and a desired measurement is performed.
A measurement method in a manufacturing process of a multilayer film in which another film is formed after the measurement.   A prober using one or a plurality of the contact probes according to claim 1.