JP2008241415A - Scanning probe microscope and local thin film adhesion evaluation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evaluate local adhesion of a thin film. <P>SOLUTION: In the method, a scanning microscope provided with both a stage 10 for fixing a sample 80 and a cantilever 30 having a probe 40 at its tip part is used to evaluate the local adhesion of the thin film 81 to a substrate 82 in the sample 80, in which the thin film 81 adheres onto the substrate 82. The method comprises a process for fixing the substrate 82 onto the stage 10; a process for fixing the probe 40 to a prescribed position of the thin film 81 with an adhesive 50; a process for separating the cantilever 30, of which the probe 40 is adhered to the prescribe position of the thin film 81 in a prescribed direction, with respect to the sample 80 and detecting a force acting on the cantilever 30; and a process for computing the adhering strength of the thin film 81 to the substrate 82 on the basis of results of the detection of the force acting on the cantilever 30, when the thin film 81 is peeled of from the substrate 82 by separating the cantilever 30 with respect to the sample 80. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a scanning probe microscope and a local thin film adhesion evaluation method.

  A scanning probe microscope is a microscope that can investigate the surface state and physical properties of a sample with atomic-scale spatial resolution, and is used in various applications such as examining the crystal structure of materials and inspecting semiconductor circuits. . Specific examples of such a scanning probe microscope include an atomic force microscope and a scanning tunneling microscope, and the configuration and operation thereof are disclosed in Patent Document 1.

  According to Patent Document 1, an atomic force microscope is an atom that acts according to the distance between a probe and a sample by bringing a probe provided at the tip of a cantilever (cantilever) close to the sample. Interatomic force can be detected by examining the deflection of the cantilever. In addition, as a method of examining the deflection of the cantilever, a method of detecting reflected light reflected by the back surface of the cantilever using a light lever principle or a cantilever made of a piezoelectric element is used. There are methods for measuring the voltage between the terminals attached to the cantilever, and the deflection can be detected with very high sensitivity by using these methods.

By the way, downsizing of electronic devices has been promoted, and the semiconductor circuits and the like have become more highly integrated. In order to improve the performance and reliability of such a semiconductor circuit, it is important to examine in detail physical properties such as the strength of a thin film which is an important component of the semiconductor circuit. In order to examine the strength of the thin film, it is essential to evaluate the adhesion of the thin film.
JP-A-8-86790

  However, according to conventional apparatuses and methods, there is a problem that local thin film adhesion cannot be evaluated. Since the conventional scanning probe microscope is not intended to evaluate the adhesion, it does not have a function or mechanism for that purpose. In addition, since a conventional thin film adhesion evaluation apparatus, for example, Sebastian (trade name, Quad Group) cannot measure a minute portion, it cannot evaluate a thin film adhesion of a thin film in an actual product, for example.

  The thin film adhesion evaluation method by Sebastian etc. is a method in which a stud pin is bonded to a thin film adhered on a substrate, the substrate and the thin film are peeled by pulling the substrate and the stud pin, and the tensile strength (adhesion strength) is measured It is. However, since the diameter of the stud pin is several millimeters, the stud pin cannot be attached to a minute part of the thin film (for example, the diameter is several tens of μm), and local thin film adhesion cannot be evaluated. . Therefore, according to Sebastian et al., Although the adhesion of a thin film as a material can be evaluated using a large sample, the thin film is affected by heat or the like in the process of manufacturing a product, Even if the adhesiveness changed due to the influence, this could not be evaluated.

  Moreover, it is difficult to solve the above-described problems simply by using a small-diameter stud pin. In other words, if it is intended to evaluate local thin film adhesion, stud pins need to be accurately bonded to the thin film evaluation position. However, conventional thin film adhesion evaluation devices such as Sebastian measure sample surface conditions. Since the function to perform is not provided, the evaluation position cannot be specified, and the stud pin cannot be attached at a desired position.

  In addition, using a conventional scanning probe microscope or the like, the surface state of the sample is examined in advance to identify the desired evaluation position, and the stud pin is attached to the thin film adhesion evaluation device. The coordinates at the time of attaching the stud cause a misalignment with the coordinates at the time of scanning the sample with the scanning probe microscope, and the stud pin cannot be attached at a desired position. Even if an alignment mark is provided on the sample, the thin film adhesion evaluation apparatus cannot detect a minute alignment mark, and therefore cannot accurately align the alignment. Thus, the subject that a stud pin cannot be correctly adhere | attached on the desired evaluation position of the thin film occurred.

  The present invention has been made in view of the above problems, and provides a scanning probe microscope capable of evaluating the thin film adhesion of a minute part (local) and a local thin film adhesion evaluation method using the same. With the goal.

The scanning probe microscope of the present invention is
A stage for fixing a sample in which a thin film adheres to a substrate, a cantilever having a probe at the tip,
Position control means for changing the relative position of the stage and the cantilever;
An adhesive for adhering the cantilever probe to a predetermined position of the thin film of the sample;
Force detecting means for detecting a force acting on the cantilever when the cantilever having the probe bonded to a predetermined position of the thin film of the sample with the adhesive is separated from the sample in a predetermined direction;
Based on the result of detecting the force acting on the cantilever when the thin film is peeled from the substrate by separating the cantilever in a predetermined direction with respect to the sample, the force detection unit detects the force on the substrate. An adhesion strength calculating means for calculating the adhesion strength of the thin film.

In this way, since the microprobe of the scanning probe microscope is provided, the surface state of the sample can be examined in detail, and the coordinates of the desired evaluation position can be specified. Further, the cantilever probe can be adhered to the predetermined position of the thin film using the adhesive by using the coordinates as they are. Therefore, a minute probe can be adhered to a desired evaluation position of the thin film.
Further, since the relative position between the stage and the cantilever can be changed by the moving means, the base of the sample fixed to the stage and the thin film adhered to the probe of the cantilever are separated in a predetermined direction, The substrate of the sample and the thin film can be peeled off. At this time, since the force detecting means is provided, the force acting on the cantilever, that is, the tensile force for peeling the substrate and the thin film can be detected, and the adhesion strength calculating means is provided. The adhesion of the thin film to the substrate can be evaluated. That is, it is possible to accurately measure and evaluate the local adhesion strength that becomes a minute portion of the thin film at a desired evaluation position.

Moreover, it is preferable to provide a curing means for curing the adhesive.
In this way, the predetermined position of the thin film and the probe of the cantilever can be bonded in a short time, and workability can be improved.

Further, the force detection means analyzes the light source that irradiates the cantilever with laser light, the optical sensor that detects the laser light irradiated from the light source and reflected from the surface of the cantilever, and the laser light detected by the optical sensor. And a calculation means for calculating the force acting on the cantilever.
In this way, a minute force can be detected using the principle of an optical lever, and the adhesion of the thin film can be accurately evaluated.

The method for evaluating local adhesion according to the present invention uses a scanning probe microscope equipped with a stage for fixing a sample and a cantilever having a tip at a tip, and a thin film is adhered on a substrate. A local adhesion evaluation method for evaluating the adhesion of a sample to the substrate of the thin film,
Fixing the sample substrate on a stage;
Fixing the cantilever probe to a predetermined position of the thin film of the sample using an adhesive;
A step of detecting the force acting on the cantilever by separating the cantilever in which the probe is bonded to a predetermined position of the thin film of the sample with the adhesive in a predetermined direction;
Based on the result of detecting the force acting on the cantilever when the thin film was peeled from the substrate by separating the cantilever in a predetermined direction, the adhesion strength of the thin film to the substrate was determined. And a calculating step.

  In this case, the cantilever probe is adhered to a predetermined position of the thin film of the sample, and the cantilever is spaced apart from the sample in a predetermined direction. Therefore, the thin film adhered to the cantilever probe The adhesion strength of the thin film is calculated by detecting the force acting on the cantilever at this time, that is, the tensile force for peeling the substrate and the thin film, and the adhesion of the thin film to the substrate. Sex can be evaluated. Here, since the probe of the scanning probe microscope has a very small diameter, a minute portion corresponding to this diameter can be evaluated, and local adhesion evaluation that cannot be performed by the conventional method can be performed. it can. Therefore, for example, the adhesion of a thin film in an actual product can be evaluated, and the strength and quality of a thin film in a product using a lot of thin films such as semiconductor circuits and MEMS can be evaluated. Therefore, it is possible to obtain important information for improving the life and performance of the product.

Further, the step of fixing the substrate of the sample on a stage and the step of fixing the cantilever probe to a predetermined position of the thin film of the sample using an adhesive, the probe using the probe. It is preferable to have a step of scanning the surface of the sample and examining the surface state of the sample.
In this way, the surface state of the sample can be obtained, and a desired evaluation position can be specified. Further, the probe can be adhered accurately to this position using the coordinates of the evaluation position obtained in the step of examining the surface state. Therefore, the adhesion of the thin film at a desired evaluation position can be evaluated.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the technical scope of the present invention is not limited to the following embodiment.

FIG. 1 is a perspective view schematically showing a configuration of an embodiment of a scanning probe microscope according to the present invention. As shown in FIG. 1, a scanning probe microscope 1 is provided on a stage 10 for fixing a sample 80, a scanner 20 for moving the stage 10, and a holding member (not shown). A cantilever 30 held in a shape, a probe 40 provided at the tip of the cantilever 30, an adhesive 50 disposed on the stage 10, and a computer 70.
The computer 70 incorporates a movement control program for sending a movement command signal to the scanner 20, and the scanning probe microscope 1 includes position control means having the movement control program and the scanner 20.
Above the cantilever 30, a light source 61 for irradiating the cantilever 30 with laser light and an optical sensor 62 for detecting reflected light 63 reflected by the surface of the cantilever 30 are provided and detected. An analysis program for analyzing the reflected light 63 is incorporated in the computer 70. As described above, the scanning probe microscope 1 includes a force detection unit having the light source 61, the optical sensor 62, and the analysis program. Although details will be described later, this force detection unit is used. Thus, the force acting on the cantilever 30 can be detected.

  In the present embodiment, the stage 10 is provided on the scanner 20 so that the upper surface thereof is horizontal. On the stage 10, an adhesive 50 in a heat insulating container (not shown) is placed at a predetermined position. The adhesive 50 needs to have a stronger adhesive strength than the adhesion between the thin film 81 and the base 82. For example, a thermosetting resin such as an epoxy resin or an ultraviolet curable resin can be selected and used. In this embodiment, an epoxy resin is used. The stage 10 is provided with a heating means such as a heater, for example. As will be described in detail later, the adhesive 50 disposed between the sample 80 and the probe 40 is heated by the heating means. It can be cured to shorten the bonding time. This heating means is connected to a temperature control program incorporated in the computer 70 so that the heating temperature and heating time can be controlled using the computer 70.

  The scanner 20 includes, for example, piezoelectric elements corresponding to the respective directions of the X axis, the Y axis, and the Z axis. Upon receiving a movement command from the movement control program of the computer 70, the scanner 20 converts the piezoelectric elements corresponding to the respective directions. A predetermined voltage can be applied and moved accurately. That is, a minute amount of movement can be controlled by applying a voltage to the piezoelectric element and expanding and contracting it. Further, the coordinates of the stage 10 at each time are sent from the movement control program of the computer 70 to the evaluation program, stored, and used for evaluation. Further, a heat insulating means 15 is provided between the stage 10 and the scanner 20 so that the scanner 20 is not heated by the heating means to cause a problem.

  FIG. 2 is an enlarged schematic view showing the stage 10 on which the sample 80 is fixed. As shown in FIG. 2, the sample 80 is composed of, for example, a base 82 and a thin film 81 in close contact with the base 82, and the base 82 and the stage 10 are detachable by a fixing means such as a magnet or a screw. It is fixed. In FIG. 2, the thickness of the thin film 81 is shown enlarged from the actual one for easy viewing. Specific examples of the sample include a thin film 81 made of a conductive, insulating, or semiconductive material, an optical material, or the like on a semiconductor substrate (base) 82 such as silicon or an insulating substrate 82 such as glass. A thin film 81 made of various functional materials is formed. A thin plate-shaped cantilever 30 is provided on the stage 10 so that the upper surface thereof is horizontal, for example. As described above, the cantilever 30 is a cantilever whose rear end is fixed independently from the stage 10. The cantilever 30 is made of, for example, silicon or silicon nitride, and has a length of, for example, about several hundred μm.

  Further, a probe 40 is provided at the bottom end of the cantilever 30, and the tip (lower end) of the probe 40 is moved to the stage by moving the stage 10 in the X and Y directions by the scanner 20. 10 can be made to correspond to a desired position. Accordingly, the probe 40 is made to correspond to a predetermined position (desired position) of the sample 80, or the tip position of the probe 40 is made to correspond to the placement position of the adhesive 50, and the adhesive 50 is attached to the tip of the probe 40. Can be attached. The probe 40 is formed integrally with the thin plate portion of the cantilever 30. The size of the probe 40 is, for example, about several μm to several tens of μm in height, and the local radius of the tip is several nm to It is about 10 and several nm. The cantilever 30 equipped with such a probe 40 can be manufactured using a known semiconductor manufacturing process, but is commercially available at a low price. It can also be used.

When a force acts on the probe 40 of the cantilever 30 as described above, the cantilever 30 is displaced (deflected) upward or downward. For example, when the stage 10 is moved upward by the scanner 20 to bring the sample 80 closer to the probe 40, the probe 40 and the sample 80 have an atomic force (repulsive force) F ₁ corresponding to the distance between them. Acting, the cantilever 30 receives a force upward in the vertical direction at its tip, and is bent upward. Further, for example, when the stage 10 is moved downward in a state where the probe 40 and the thin film 81 of the sample 80 are bonded with the adhesive 50, the cantilever 30 receives a downward force in the vertical direction at the tip thereof, A downward deflection is generated.

  FIGS. 3A and 3B are diagrams for explaining the force detection means. As described above, the force detection means analyzes the detected data and the force acting on the cantilever 30 by the light source 61 that irradiates the upper surface of the cantilever 30 with the laser light from the predetermined position, the optical sensor 62 that detects the laser light. And an analysis program for calculation. In this embodiment, the position of the light source 61 and the position of the optical sensor 62 can be adjusted, and these positions are reflected by the upper surface of the cantilever 30 where no deflection occurs, as shown in FIG. The positions of the light source 61 and the optical sensor 62 are adjusted so that the reflected light 63 incident on the light receiving surface of the optical sensor 62 is adjusted. After being adjusted in this way, the light source 61 and the optical sensor 62 are fixed so that the relative position with the rear end portion (fixed end) of the cantilever 30 does not change.

  The optical sensor 62 is connected to an analysis program of the computer 70 (see FIG. 1), and sends coordinate data on the light receiving surface of the detected reflected light 63 to the analysis program. The analysis program analyzes the coordinate data of the detected reflected light 63 to obtain the deflection amount of the cantilever 30, and works on the cantilever 30 using the relationship (spring constant) between the force acting on the cantilever 30 and the deflection amount. Force can be detected.

  For example, when a vertical downward force is applied to the tip of the cantilever 30 and deflected downward, the laser beam is incident on the curved surface of the cantilever 30a that is bent as shown in FIG. 3B. Is reflected in a direction corresponding to the tangential direction of the curved surface and the incident direction of the laser beam. Therefore, when the amount of vertical deflection of the cantilever 30a increases, the position where the reflected light 63a is detected by the optical sensor 62 moves downward. Further, when the amount of deflection of the cantilever 30a exceeds a certain value, the reflected light 63a does not enter the optical sensor 62, and therefore cannot be detected by the optical sensor 62. Thus, the traveling direction of the reflected light 63a changes in accordance with the amount of deflection of the cantilever 30a.

Here, the detection position of the reflected light 63 on the light receiving surface of the optical sensor 62 when the predetermined deflection amount is generated in the cantilever 30 is examined in advance, and the relationship between the detection position and the deflection amount is used. The analysis program can calculate the deflection amount of the cantilever 30 from the detection position of the reflected light 63.
The relationship between the amount of deflection of the cantilever 30 and the force F ₁ (spring constant) is obtained by examining the amount of deflection when a predetermined load is applied to the cantilever 30 in advance. The force acting on the cantilever 30 can be calculated from the amount of deflection.

  In the present embodiment, the computer 70 (see FIG. 1) receives a movement control program for controlling the scanner 20, an analysis program for receiving an incident signal of the reflected light 63 detected by the optical sensor 62, and analyzing it. A temperature management program for controlling the heating means of the stage 10 and an evaluation program (adhesion strength calculating means) for calculating the adhesion strength of the thin film 81 to the base 82 based on the analysis result of the analysis program are incorporated. . These programs can exchange data with each other, and can function together.

  The movement control program sends a movement command signal to the scanner 20 to drive the scanner 20 to move the stage 10 to a predetermined position, and the position (coordinates) of the stage 10 at this time is changed to the evaluation program every time. To send to. The analysis program analyzes the force acting on the cantilever 30 based on the detection position data of the reflected light 63 detected by the optical sensor 62 as described above, and also detects the detection position data of the reflected light 63 and the cantilever 30. The data such as the force acting on, the amount of deflection, and the information when the reflected light 63 is not detected are sent to the evaluation program every time.

  The evaluation program can evaluate the adhesion strength by obtaining the tensile force for separating the thin film 81 and the base 82, that is, the adhesion force of the thin film 81. Specifically, when the stage 10 is gradually moved downward in a state where the probe 40 and the thin film 81 at the tip of the cantilever 30 are bonded, the cantilever 30 is pulled downward to cause deflection, and this elastic restoring force Becomes a tensile force that pulls the thin film 81 adhered to the probe 40 upward. Further, the base 82 fixed to the stage 10 moves downward together with the stage 10, but since the base 82 and the thin film 81 are in close contact, the thin film 81 and the base 82 are pulled in the direction in which they are separated from each other. Force acts. This tensile force increases as the stage 10 moves downward, and when the adhesion force between the thin film 81 and the substrate 82 becomes larger, the thin film 81 and the substrate 82 are separated. And if the thin film 81 and the base | substrate 82 peel, the peeling part of the thin film 81 will move upward, and the bending of the cantilever 30 will reduce.

As described above, since the data such as the deflection amount of the cantilever 30 is sequentially sent from the analysis program to the evaluation program and stored, the evaluation program calculates the time (the peeling time) when the deflection amount starts to increase and decreases. You can ask for it.
Further, when the adhesion of the thin film 81 is strong and the deflection amount of the cantilever 30a is large, the reflected light 63a does not enter the optical sensor 62 and the deflection amount cannot be detected by the optical sensor 62, but the base 82 and the thin film are not detected. When peeling from 81, the deflection of the cantilever 30 decreases within a very short time, and the reflected light 63 is detected again by the optical sensor 62. Since this information is also sequentially sent from the analysis program to the evaluation program and stored, the evaluation program can obtain the time when the reflected light 63 is detected again as the peeling time.

  When the peeling time is obtained, the evaluation program can obtain the vertical position of the stage 10 at the peeling time by referring to the vertical position data of the stage 10 received from the movement control program. . Then, the maximum deflection amount of the cantilever 30 can be obtained by obtaining the difference between the vertical position of the stage 10 when the peeling occurs and the vertical position before the stage 10 is moved. The maximum tensile force can be obtained by causing the analysis program to analyze the amount of deflection. Further, the tensile strength is obtained using the maximum tensile force, the area where this force is applied, and the like, and the local adhesion strength can be evaluated based on the tensile strength.

  Further, as described above, the program incorporated in the computer 70 can be made to function in cooperation, whereby the scanning probe microscope 1 of the present embodiment is different from a general scanning probe microscope. Similarly, the surface state of the sample 80 can be examined. Specifically, the movement control program refers to the force acting on the cantilever 30 and moves the stage 10 by sending a movement command signal to the scanner 20 in accordance with this force, so that the probe 40 and the sample are moved. The position of the stage 10 can be controlled by adjusting the distance between them so that the force acting on the cantilever 30 has a predetermined magnitude. Here, if the sample 80 is scanned with the probe 40 while the force (interatomic force) acting on the cantilever 30 is kept constant, the atomic force is set at a distance between the sample 80 and the probe 40. Therefore, the vertical distance between the sample 80 and the probe 40 is constant. Since the tip (lower end) position of the probe 40 is fixed, the height for each position of the sample 80 can be obtained, and the surface state of the sample 80, that is, the surface unevenness can be examined. Yes.

  As described above, since the scanning probe microscope 1 according to the present embodiment can check the surface state of the sample 80, a desired evaluation position can be specified. Further, since the minute probe 40 can be adhered to a predetermined position of the thin film 81 using the coordinate data of the evaluation position, the probe 40 can be adhered accurately to a desired position of the thin film. Further, the stage 10 is moved by the scanner 20 so that the thin film 81 adhered to the probe 40 and the base 82 can be peeled off, and at this time, a tensile force (adhesion force) for peeling both can be obtained. It has become. Therefore, the local thin film adhesion evaluation with respect to the base | substrate 82 of the thin film 81 can be performed in the desired micro part (local) of the thin film 81. FIG.

  Next, one embodiment of the local adhesion evaluation method of the present invention is used in the case where the above-described scanning probe microscope 1 is used to evaluate the adhesion of the thin film 81 adhered on the substrate 82. explain. For example, the substrate 82 is like a semiconductor circuit substrate, and the thin film 81 is formed on the upper surface of the substrate 82.

4 (a) to 4 (c) and FIGS. 5 (a) to 5 (d) are diagrams illustrating an embodiment of the local adhesion evaluation method.
First, a sample 80 having a thin film 81 in close contact with a base 82 is prepared, and the base 82 is fixed to the stage 10 so as to be detachable and horizontal by a fixing means such as a magnet or a screw. The computer 70 receives the movement control program for controlling the scanner 20, the incident position data of the reflected light 63 detected by the optical sensor 62, the analysis program for analyzing the data, and the temperature management for controlling the heating means of the stage 10. A program and an evaluation program (adhesion strength calculating means) for calculating the adhesion strength of the thin film 81 to the base 82 based on the analysis result of the analysis program are incorporated in advance.

  Next, in this embodiment, as shown in FIG. 4A, the surface state of the sample 80 is measured. In this embodiment, the cantilever 30 is attached so that the upper surface thereof is horizontal. As described above, the reflected light 63 irradiated from the light source 61 to the cantilever 30 and reflected by the surface of the cantilever 30 is detected by the optical sensor 62 and analyzed by an analysis program, whereby the deflection amount of the cantilever 30 is determined. Can be sought. Further, the distance between the probe 40 and the sample 80 is kept constant by moving the stage 10 in the horizontal direction while adjusting the vertical position of the stage 10 with the movement control program so as to keep this deflection amount constant. The surface of the sample 80 can be scanned with the probe 40 while maintaining the above. At this time, the position data of the stage 10 is stored by the movement control program, and the surface state of the sample 80 can be obtained on the atomic scale from the position data. In this way, for example, even if the thin film 81 to be evaluated has a size (diameter) of about several tens of μm, the position (coordinates) on which the thin film 81 is formed on the substrate 82 can be accurately known. A desired evaluation position (coordinates) on the thin film 81 can be set strictly.

  Next, as shown in FIG. 4B, the stage 10 is moved so that the tip position of the probe 40 of the cantilever 30 and the epoxy resin (adhesive) 50 placed on the stage 10 correspond to each other. A predetermined amount of epoxy resin 50 is attached to the tip of the probe 40. Here, in the present embodiment, the horizontal position of the probe 40 and the epoxy resin 50 is matched, and then the stage 10 is moved vertically upward while detecting the force acting on the cantilever 30 by the force detection means. Then, the epoxy resin 50 is moved closer to the probe 40. In this way, it is possible to detect the position of the surface of the epoxy resin 50 in the vertical direction by detecting a change in the force acting on the cantilever 30, and by sinking the probe 40 from this position to a desired depth, A predetermined amount of epoxy resin 50 can be adhered to the probe 40.

Next, as shown in FIG. 4C, the stage 10 is moved so that the horizontal position between the probe 40 to which the epoxy resin 50 is attached and the evaluation position of the thin film 81 is made to correspond. At this time, since the sample 80 remains fixed on the stage 10 from the time when the surface state of the sample 80 is examined, the coordinate data when the surface state of the sample 80 is obtained can be used as it is. Therefore, the probe 40 can be made to correspond to the desired evaluation position of the thin film 81 very accurately. Then, as shown in FIG. 5A, the stage 10 is moved in the vertical direction to bring the thin film 81 closer to the probe 40 so that the thin film 81 and the tip of the probe 40 are at a predetermined distance. The initial position Z ₀ in the vertical direction (Z direction) of the stage 10 is stored in the computer 70. By doing in this way, the contact area of the epoxy resin 50 adhering to the tip of the probe 40 and the thin film 81 can be controlled. Note that the initial position Z ₀ stored in the computer 70 is used for analysis for evaluating the adhesion force described later.

  Next, as shown in FIG. 5B, the epoxy resin 50 is heated and cured by the heating means of the stage 10, and the probe 40 and the thin film 81 are bonded. Between the stage 10 and the scanner 20 (see FIG. 1), for example, a heat insulating means 15 (see FIG. 1) such as a vacuum heat insulating means is provided. It is prevented. Thus, by using the heating means, the epoxy resin 50 can be sufficiently cured, and the probe 40 and the thin film 81 can be bonded with sufficient strength. Moreover, since it can adhere | attach in a short time, workability | operativity can be improved.

Next, as shown in FIG. 5C, the stage 10 is gradually moved downward, for example, and a tensile test of the sample 80 is performed. There is no deflection in the cantilever 30 before the stage 10 is moved downward. However, as the stage 10 is moved downward, the tip portion provided with the short needle 40 is pulled downward, causing deflection downward. At this time, on the thin film 81 and the substrate 82, in the direction of separating them, are working tensile force F ₂ of the same size as the elastic restoring force of the cantilever 30a resulting deflection moves the stage 10 downward as the tensile force _{F 2} becomes larger.

Further, a tensile force F ₂ is applied to the thin film 81 and the base 82 and the tensile force F ₂ is measured as follows. First, the cantilever 30 a is irradiated with laser light from the light source 61 at a predetermined position, and the reflected light 63 a is detected by the optical sensor 62. The position data is analyzed by the analysis program of the computer 70 on the light-receiving surface of the detected reflected light 63a, and this data is sent to the evaluation program of the computer 70 and stored every time and used for the adhesion evaluation later. This embodiment is an example in which the adhesion between the thin film 81 and the base 82 is strong, and it is necessary to apply a large tensile force F ₂ to separate the thin film 81 and the base 82. For this reason, the amount of deflection of the cantilever 30 a increases, and the reflected light 63 a reflected by this curved surface does not enter the optical sensor 62. In such a case, information that the reflected light 63a is not detected by the optical sensor 62 is sent to the evaluation program and recorded.

As the stage 10 is gradually moved downward, the tensile force F ₂ increases, and when the tensile force F ₂ reaches the tensile strength between the thin film 81 and the base 82, the thin film 81 and the base 82 are separated. The peeling between the thin film 81 and the substrate 82 occurs at a position corresponding to the evaluation position where the probe 40 and the thin film 81 are bonded to each other. For example, as shown in FIG. In addition, depending on the material of the thin film 81, the thin film 81 may be locally broken and peeled off from the base 82, or depending on the size of the thin film 81, the entire thin film 81 may be peeled off from the base 82. is there.

Here, in any of the above-described peeling states, the peeling portion of the thin film 81 is moved upward by the tensile force F ₂ (elastic restoring force), and the probe 40 adhered thereto is also moved upward. In this way, the cantilever 30a has a reduced amount of deflection, for example, a state in which no deflection is generated (cantilever 30). Further, since the amount of deflection is reduced, the reflected light 63a changes its traveling direction and is again detected by the optical sensor 62 (reflected light 63).

Using the data obtained as described above, local thin film adhesion is evaluated as follows. First, the evaluation program of the computer 70 checks the time history of the detection position of the reflected light 63a, and the time when the reflected light 63a is re-detected by the optical sensor 62, or the amount of deflection of the cantilever 30a changes from increasing to decreasing. The time, that is, the time when the thin film 81 and the base 82 are peeled off (peeling time) is obtained. Next, the evaluation program obtains the position Z _{1 in} the vertical direction of the stage 10 at the peeling time (see FIG. 5D) by referring to the position data of the stage 10 for each time. Also, determine the initial position Z ₀ of the vertical direction of the stage 10, by obtaining the difference between the initial position Z ₀ and the position Z _1, obtaining the maximum deflection amount is the deflection amount of the cantilever 30a in the release time. The analysis program calculates the maximum tensile force corresponding to the maximum deflection amount by using the spring constant of the cantilever 30, and sends this to the evaluation program. The evaluation program obtains the maximum tensile force (adhesion force), for example, the adhesion force per unit area, that is, the adhesion strength, using the area where the tensile force is applied to the thin film 81 and the base 82, for example. As the area where the tensile force is applied, for example, the area of the portion where the thin film 81 is peeled off from the base 82 or the contact area of the epoxy resin (adhesive) 50 on the upper surface of the thin film 81 is used. Can do. In this way, the local adhesion of the thin film can be evaluated.

  According to the local adhesion evaluation method of the present embodiment as described above, since the surface state of the sample 80 is examined on an atomic scale, the position for evaluating the adhesion of the thin film can be accurately specified. Further, the surface state of the sample 80 is examined while the sample 80 is fixed on the stage 10, and the probe 40 to which the epoxy resin (adhesive) 50 is attached is adhered to a predetermined position of the thin film 81. Therefore, the probe 40 can be adhered to a desired evaluation position. Further, since the minute probe 40 of the scanning probe microscope 1 is used, the probe 40 can be adhered to a minute part (evaluation position) of the thin film 81. As described above, the probe 40 is adhered accurately to a desired minute portion of the thin film 81, and the cantilever 30 and the stage 10 are separated from each other, whereby a tensile test is performed by applying a tensile force to the minute portion. Since the adhesion force (maximum tensile force) of the substrate 82 is obtained, the adhesion force of the minute portion (local) of the thin film 81 can be obtained accurately. In addition, since the local adhesion strength is analyzed by the adhesion strength calculating means to obtain the local adhesion strength and the adhesion evaluation is performed, an accurate adhesion evaluation can be performed.

Therefore, the local adhesiveness of the thin film which could not be evaluated conventionally can be accurately evaluated. Therefore, for example, the adhesion of a minute thin film formed on a semiconductor circuit or the like can be evaluated in the state of an actual product, heat treatment in the process of manufacturing the product, chemical reaction with other materials, or substrate restraint. The adhesion of the thin film can be evaluated including the influence of force and the like. In addition, for example, in actual products, a thin film may be formed on the uneven surface, and in such a case, it is difficult to spread the thin film material to the stepped corners of the uneven surface, so that the adhesion generally decreases. However, according to the local adhesion evaluation method of the present invention, it is possible to evaluate the adhesion of a very small portion, it is possible to evaluate the adhesion in a minute flat portion of the uneven surface, the uneven surface It is also possible to evaluate a decrease in adhesion due to the formation of a thin film thereon. In addition, by evaluating local adhesion in a thin film with a certain large diameter, for example, it is possible to evaluate differences in adhesion at the periphery and center of the thin film, and local adhesion due to contamination of impurities such as air. Variations can be evaluated.
In this way, since adhesion can be evaluated in an actual product or the like, extremely important information can be obtained in improving the manufacturing process of the product or improving the life or performance of the product.

In this embodiment, the force detection means of the cantilever 30 using the principle of the optical lever is used. However, for example, a voltage between terminals attached to the cantilever is measured using a cantilever made of a piezoelectric element. It may be a force detection means. In the present embodiment, the laser light source 61 and the optical sensor 62 are installed so that the relative position with respect to the fixed end of the cantilever 30 does not change, and the timing at which the reflected light 63 is detected by the optical sensor is used. However, for example, the optical sensor 62 may be moved in the vertical direction so that the reflected laser beam 63 is always detected. In this case, the cantilever can be determined by examining the time change of the position where the reflected beam 63 is detected. It is possible to examine the time change of the deflection amount of 30. Further, the cantilever 30 does not have to be installed so that the upper surface is horizontal, and maytilever may be installed so as to easily detect the reflected light 63 when the deflection occurs.
In addition to the epoxy resin, the adhesive 50 may be appropriately selected and used as long as it has an adhesive strength stronger than the adhesion of the thin film. For example, an ultraviolet curable resin is used, and an ultraviolet ray is used. You may make it harden | cure and adhere | attach by irradiating.
In addition, the size (diameter) of the portion for evaluating the adhesion can be several tens of μm or less, and the local radius of the tip of the probe 40 is several nm, which corresponds to this size. The adhesion can be evaluated even at a minute portion. In this embodiment, the thin film 81 is locally removed from the base 82. However, when the diameter of the thin film 81 is extremely small, the adhesive 50 is in contact with the entire surface of the thin film 81 so that the entire surface of the thin film 81 is covered. May be peeled off

It is a perspective view which shows typically the structure of the scanning probe microscope of this invention. It is a schematic diagram which expands and shows on the stage in which the sample is arrange | positioned. (A), (b) is a figure explaining a force detection means. (A)-(c) is a figure explaining the local adhesiveness evaluation method of this invention. (A)-(d) is a figure explaining the local adhesiveness evaluation method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Scanning probe microscope, 10 ... Stage, 20 ... Scanner, 30, 30a ... Cantilever, 40 ... Probe, 50 ... Epoxy resin (adhesive), 61 ... · Light source, 62 ... optical sensor, 63, 63a ... reflected light, 70 ... computer

Claims (5)

A stage for fixing a sample in which a thin film adheres to a substrate, a cantilever having a probe at the tip,
Position control means for changing the relative position of the stage and the cantilever;
An adhesive for adhering the cantilever probe to a predetermined position of the thin film of the sample;
Force detecting means for detecting a force acting on the cantilever when the cantilever having the probe bonded to a predetermined position of the thin film of the sample with the adhesive is separated from the sample in a predetermined direction;
Based on the result of detecting the force acting on the cantilever when the thin film is peeled from the substrate by separating the cantilever in a predetermined direction with respect to the sample, the force detection unit detects the force on the substrate. A scanning probe microscope comprising: an adhesion strength calculating means for calculating an adhesion strength of the thin film.   The scanning probe microscope according to claim 1, further comprising a curing unit that cures the adhesive.   The force detection means analyzes a light source that irradiates the cantilever with laser light, an optical sensor that detects laser light that is irradiated from the light source and reflected from the surface of the cantilever, and laser light detected by the optical sensor. The scanning probe microscope according to claim 1, further comprising a calculation unit that calculates a force acting on the cantilever. Using a scanning probe microscope equipped with a stage for fixing a sample and a cantilever having a probe at the tip, a sample in which a thin film is in close contact with the substrate is adhered to the substrate. A local adhesion evaluation method for evaluating the properties,
Fixing the sample substrate on a stage;
Fixing the cantilever probe to a predetermined position of the thin film of the sample using an adhesive;
A step of detecting the force acting on the cantilever by separating the cantilever in which the probe is bonded to a predetermined position of the thin film of the sample with the adhesive in a predetermined direction;
Based on the result of detecting the force acting on the cantilever when the thin film was peeled from the substrate by separating the cantilever in a predetermined direction, the adhesion strength of the thin film to the substrate was determined. A local adhesion evaluation method comprising: a step of calculating.   Between the step of fixing the substrate of the sample on the stage and the step of fixing the probe of the cantilever to a predetermined position of the thin film of the sample using an adhesive, The local adhesion evaluation method according to claim 4, further comprising a step of scanning a surface and examining a surface shape of the sample.

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