JP2745648B2 - Adhesion measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for measuring the adhesion strength of a thin film formed on a substrate.

(Prior Art) Conventionally, methods for measuring the adhesive force of a thin film include a method for indirect measurement and a method for direct measurement.

As a typical method of the indirect measurement method, for example, a tape or a rod is adhered on a thin film, the thin film is separated by applying a force to the tape or the rod, and a force required for the separation is measured. There is a method of measuring the adhesive force.

Further, as a method of directly measuring, there is a method of directly applying a force to a thin film to cause peeling, and measuring an adhesive force at that time. This method is applied to relatively adhesive thin films.

For example, as a typical example of the latter method, a bending stress is applied to the interface between the substrate and the thin film by bending the formed substrate, thereby causing peeling of the thin film. There is a method of measuring the adhesive force of a thin film by measuring.

(Problems to be Solved by the Invention) However, in the conventional method of measuring the adhesive force of a thin film by bending a substrate of this type, there is no method for accurately detecting peeling.

(Means for Solving the Problems) An adhesive force measuring apparatus according to the present invention comprises an indenter for pressing and bending a film-formed substrate, a substrate load applying unit for applying pressure to the indenter, the substrate or the thin film, and an interface between both. Acoustic Emissio
means for detecting n), a substrate deflection detector for measuring the amount of deflection of the substrate, and a microscope for observing peeling,
A microscope control unit for automatically setting the field of view and the focal point of the microscope to a region where separation has occurred.

(Function) In the adhesive force measuring apparatus of the present invention, there are two kinds of means of detecting a peeling phenomenon of a thin film from an acoustic emission generated from a substance and observing a thin film surface with a microscope while performing a bending test. Detect using Detection of peeling by acoustic emission can be performed more accurately and quickly than by a visual method. However, when a bending test is performed on a sample, acoustic emission may occur due to factors different from the peeling of the thin film, such as substrate destruction and film cracking. It is necessary to conduct the test while always confirming that the emission is due to the peeling of the thin film. Since the adhesive force measuring apparatus of the present invention has a function of observing the surface of a sample under test with a microscope, it can detect only acoustic emission caused by peeling of a thin film and accurately detect peeling.

(Example) Next, the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of an adhesive force measuring device showing one embodiment of the present invention. The adhesive force measuring device includes a column 10 erected on a measuring table 11, a substrate bending mechanism 4 mounted on the measuring table 11, and a substrate load mounted on support plates 12 and 13 of the column 10, respectively. Addition unit 14 and board deflection amount detection unit
It consists of 15.

The substrate bending mechanism 4 includes an indenter 2 and a fulcrum member 3, and applies a bending stress to the substrate 1, which is a material to be tested, by these three points. The fulcrum member 3 is mounted on a table 16 which can be adjusted up and down by three screws 17. Under the table 16, a load cell 18 for detecting a load applied to the substrate 1 is mounted. Have been.

An example of the fulcrum member 3 is shown in FIG. FIG. 3A shows a configuration in which a knife edge 3a is fixed to a bracket 3b with a pin 3c.
FIG. 2B shows a configuration using a roller 21 instead of the knife edge.

The substrate load applying unit 14 includes a feed screw 5 attached to the other end of the indenter 2 and a motor 6 that rotates through a gear pair 7 attached to the feed screw 5.

The board deflection amount detection unit 15 includes a displacement detection unit 9 connected to the end face of the feed screw 5 and a displacement converter 8 directly connected to the displacement detection unit 9. The displacement converter 8 converts the amount of deflection of the substrate 1 into an electric signal.

Acoustic emission sensor for detecting acoustic emission emitted from a sample (first
The AE sensors 27 are attached to both ends of the sample 1 and position determination is performed on the peeled sample based on the difference in the time when the acoustic emission reaches both sensors.

The peel observation unit 29 includes a microscope 23 and a microscope position control unit 24.
, A television camera 25, a monitor 26, and a rail 28. The microscope 23 is mounted on a microscope position control unit 24, and both move along the rail 28 in conjunction with each other. The microscope 23 has a function of automatically focusing. Further, the microscope position controller 24 has a function of setting the field of view of the microscope 23 to an area where a thin film is generated.

The position control of the microscope will be described with reference to FIG.
When the bending test is performed, two AE sensors 27 are attached to both ends of the sample. The detected AE signal is sent to the signal processing unit 22. The signal processing unit 22 locates the position of the separation on the sample from the signal time difference input from the two AE sensors 27,
Information about the peeling position is transferred to the microscope position control unit 24. Peeling position control unit to which information about the peeling position is input
The slide 24 slides on the rail 28 so that the visual field of the microscope 24 is set at the peeling position.

Next, the operation of this device will be described. First, the substrate 1 on which the film is formed is placed on the two support members 3. Next, the motor 6 is rotated to rotate the spline shaft attached to one end of the feed screw 5 via the gear pair 7. By this rotation, the feed screw 5 is rotated, the feed screw 5 is lowered by the nut 19 fixed to the support 20 of the column 10, and the indenter 2 starts to push and bend the substrate 1.

On the other hand, the load cell 18 detects a load applied to the substrate, detects the load, converts the magnitude of the load into a digital signal, and transmits the digital signal to the microcomputer. Further, the deflection amount of the substrate 1 is detected by the substrate deflection amount detection unit 15, and the detection signal is similarly transmitted to the microcomputer.

Here, as described above, when the indenter 2 starts to press and bend the substrate 1, for example, when the film forming side of the substrate 1 is pressed,
A compressive stress is generated on the surface of the substrate 1 on the side of the indenter 2 and a tensile stress is generated on the back surface, and a stress is generated at an interface between the substrate and the thin film. The thin film peels off due to this stress. The acoustic emission sensor 27 detects a sound wave emitted along with the peeling phenomenon at this time, so-called acoustic emission.

The acoustic emission is converted into an electric signal, and the electric signal is transmitted to the microcomputer. Further, the position of the peeled area on the sample is determined from the time difference at which the acoustic emission reaches the two sensors.

When peeling occurs in the bending test, the peeling position is determined as described above, and the microscope position control unit sets the visual field of the microscope in the peeling area, so that the state of the peeling that has occurred can be observed and detected. It is possible to analyze the correspondence between the acoustic emission and the peeling.

Next, an example in which the adhesion of a nitride thin film formed on a plastic substrate is measured using the adhesion measuring device of the present invention will be described.

When the surface of the thin film at the moment when acoustic emission occurs when a bending test is performed using the adhesion measuring device of the present invention is observed with a microscope, the thin film has a width (μ).
m), it can be seen that it has peeled off in a linear shape and floated.
It was confirmed that the acoustic emission detected at this time was caused by such peeling of the thin film. As described above, since the surface of the thin film is observed with a microscope when the substrate is bent, the origin of the detected acoustic emission can be confirmed.

FIG. 3 is an example showing an acoustic emission signal detected at the same time that the above-mentioned linear peeling is observed, and the vertical axis of the graph represents the occurrence of acoustic emission (expressed as the number of AEs generated in the figure); The horizontal axis is the deflection amount of the substrate. As can be seen from this figure, when the deflection amount is 0.1 (cm) and 1.6 (cm), acoustic emission is discretely generated, and the deflection amount is 2.0 (cm).
In the above, acoustic emission occurs intensively. From the results of the above microscopic observation, it can be concluded that these acoustic emission signals correspond to the peeling phenomenon of the thin film.

During the bending test, the stress applied to the interface between the thin film and the substrate is proportional to the amount of deflection of the substrate. Therefore, the amount at which an acoustic emission signal corresponding to the peeling phenomenon starts to be generated is δc is the thickness of the thin film. It is proportional to the applied strength. Therefore, the adhesive force can be measured by using δc as an index indicating the adhesive strength.

(Effect of the Invention) By using the adhesion measuring device of the present invention, it is possible to accurately detect peeling of a thin film by detecting acoustic emission released from a sample when a bending test is performed on a substrate. Was. Furthermore, since the bending test is performed while observing the surface of the sample with a microscope, the test can be performed while confirming that the detected acoustic emission is caused by the peeling of the thin film. The accuracy and accuracy of the thin film adhesion measurement have been improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of an adhesion measuring device showing one embodiment of the present invention, FIG. 2 is a diagram showing one embodiment of visual field control of a microscope, and FIG. FIGS. 4A and 4B are perspective views showing examples of the structure of a support member of the adhesive force measuring device, in which the amount of flexure for describing an example of measuring the adhesive force is shown as the number of acoustic emissions. DESCRIPTION OF SYMBOLS 1 ... Board, 2 ... Indenter, 3 ... Support member, 3a ... Knife edge, 3b ... Bracket, 3c ... Pin, 4 ... Board bending mechanism part, 5 ... Feed screw, 6 ... Motor , 7 ... gear pair, 8 ... displacement converter, 9 ... displacement detector, 10 ... column, 11 ... measuring table, 12, 13 ... support plate, 14 ... board load applying part, 15 ... … Substrate deflection detector, 16… Table, 17… Screw, 18… Load cell, 19… Nut, 20
... Support, 21 ... Roller, 22 ... Signal processing unit, 23 ...
Microscope, 24: Microscope position control unit, 25: TV camera, 26: Monitor, 27: AE sensor, 28: Rail, 29: Peeling observation unit.

Claims (1)

(57) [Claims] An indenter for pressing and bending a film-formed substrate, a substrate load applying portion for applying a pressing force to the indenter, and means for detecting acoustic emission generated from the substrate or the thin film and an interface between the two. And, a substrate deflection detection unit that measures the amount of deflection of the substrate, a microscope for observing peeling, and a microscope control unit that automatically sets the field of view and focus of this microscope to the area where peeling has occurred. An adhesive force measuring device comprising: