JP2803253B2 - Adhesion measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indentation type adhesive force measuring device for measuring the adhesive force between a thin film and a substrate.

[Related Art] In recent years, with the rapid progress of film forming technology, many thin films formed by sputtering, vapor deposition, and the like have been used in a wide range of industrial fields as magnetic materials, electronic materials, and corrosion-resistant materials.

In devices using these thin films, when the film thickness is relatively large, when a multilayer film in which thin films of different materials are stacked, or when a combination of materials with poor matching between the substrate and the thin film must be used For example, peeling between the thin film and the substrate or between the thin film has become a problem. This problem directly leads to a decrease in product yield and an increase in manufacturing cost.
Further, depending on the use environment of the device, thermal peeling or corrosion peeling becomes a problem, and peeling due to temperature change or corrosion often affects the environmental resistance and long-term reliability of a thin film device. Therefore, from the viewpoint of quality control and improvement of reliability, we have established a film deposition technology that suppresses peeling of thin films and developed a method to measure the adhesion between thin films with high accuracy to quantitatively grasp the tendency of peeling. It is urgent to do it.

FIG. 3 is a schematic diagram of an adhesive force measuring device showing an example of the related art. 2. Description of the Related Art Conventionally, as an example of this kind of adhesive force measuring device, it is disclosed in, for example, Japanese Patent Publication No. 62-188193. As shown in FIG. 3, this adhesive force measuring device mounts a test piece 1 having a thin film formed on a substrate and tilts the test piece 1, and mounts the tilted sample base 11 on the substrate. A sample dish 3 to be sampled, an electronic balance 2 serving as a load transducer for placing the sample dish 3, and a detector that applies indentation deformation to the test piece 1 and detects the propagation state of cracks generated inside the test piece 1. , A piezoelectric actuator 5 for driving the conical indenter 4 a, a mirror 6, an optical fiber 7, and a photonic sensor 9, which are interlocked with the piezoelectric actuator 5 and measure the pressing amount of the indenter 4 a. And the above-described crack propagation state, ie, AE (Acoustic Emissi-on), which is connected to the displacement meter and the terminal 12 of the indenter 4a.
And an AE analysis device 10 for analyzing the

The operation of this adhesive force measuring device is as follows. First, a conical indenter 4a is pressed against the test piece 1 on which the thin film is formed, thereby deforming the test piece 1, and the amount of deformation at this time is obtained by the photonic sensor 9. The indentation load is determined by the electronic balance 2, and further,
At this time, the AE characteristic of the test piece 1 is detected by the indenter 4a, the characteristic value of the AE is analyzed by an AE analyzer to analyze the waveform, and the adhesive force of the thin film of the test piece 1 is measured based on the obtained data. I was

[Problems to be solved by the invention]

However, in the above-mentioned conventional adhesive force measuring device,
Since the shape of the indenter is conical and the area to be pressed is a point, there is a problem that the tip is weak in strength and the tip is damaged.

Further, there is a disadvantage that the peel strength in any direction of the thin film around the indenter cannot be grasped quantitatively.

An object of the present invention is to solve the above problem and to provide an adhesion measuring device which can measure the directional adhesion of a thin film without damaging an indenter.

[Means for solving the problem]

An adhesive force measuring apparatus according to the present invention includes a load converter having a tilting mechanism for mounting a test piece having a thin film formed on a substrate and tilting the test piece, and applying indentation deformation to the test piece, and It has an indenter also serving as a detector for detecting the propagation state of cracks generated inside the indenter, a driver for driving the indenter, and a displacement meter that works with the driver and measures the amount of pushing of the indenter. In the adhesive force measuring device, the indenter has a wedge shape.

〔Example〕

The present invention relates to AE generated by destruction or delamination occurring inside a substrate, inside a thin film, or at an interface between a thin film and a substrate.
(Acoustic Emissi-on) This is based on the fact that the amplitude and frequency of the signal are different. That is, an indenter having a sharp wedge-shaped blade surface is provided as an AE converter, and by adopting this wedge shape, the strength of the indenter is improved and the measurement sensitivity is improved. Also, by controlling and measuring the load applied to the test piece via the indenter and the indentation depth of the indenter with high precision, the AE signal accompanying the separation between the ultra thin film and the substrate is detected. . The tilting mechanism for tilting the test piece is for applying a shear stress between the thin film and the substrate.

Here, the load applied when AE occurs due to the separation of the interface is W
When the indentation depth of the indenter at this time is δ, the inclination angle of the test piece forming the horizontal plane is α, and the width of the twill surface of the wedge-shaped indenter is L, the twill of the blade surface of the indenter is perpendicular to the thin film surface. The shearing stress τ acting on the interface when peeling occurs when applied is τ = (W / δ ² ) · cosα.

When the edge of the blade surface of the indenter is applied to the thin film surface, τ = (W / Lδ ² ) · cosα.

The value of τ defines the adhesive force measured by the adhesive force measuring device of the present invention.

Further, the present invention, by providing the wedge-shaped indenter described above, a test piece that is a substrate on which a thin film is formed,
The purpose is to measure the peel strength of the thin film in all directions by changing the direction of the blade surface of the indenter.

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

FIG. 1 is a schematic view of an adhesive force measuring device showing one embodiment of the present invention, and FIG. 2 is a side view of the indenter of FIG. In this adhesive force measuring device, the indenter 4 shown in FIG. 1 has a wedge shape as shown in FIG. That is, as shown in FIG. 2, a round bar or a material having a square cross section is provided with a twill surface 14 so as to form a knife edge on both sides. The side surface 13 of the indenter 4 is determined by the width of the twill surface according to the test piece. Further, the material of the indenter 4 is, for example, PZT (piezoelectric element made of lead zirconate titanate), and a wedge-shaped cutting edge is formed by ion milling to have a radius of 10 μm and a width of 100 μm by ion milling.
The wedge-shaped cutting edge finished to about μm is a transducer.

On the other hand, a test piece 1 having a thin film formed on a substrate is placed on a sample dish 3 of an electronic balance 2 used as a load transducer. The wedge-shaped indenter 4 is attached to the tip of a piezoelectric actuator 5 which is a driving device. The wedge-shaped indenter 4 pushes the blade into the test piece and deforms the same at the same time as the inside of the substrate or the thin film or at the interface between the substrate and the thin film. Detects the AE signal accompanying destruction.

Here, the method of pushing the indenter 4 includes the case where the side surface of the indenter shown in FIG. 1 is pushed into the test piece 1 and the direction rotated by 90 degrees with respect to FIG. And push it in. The amount of indentation of the indenter 4 is determined by reflecting light 8 from a photonic sensor 9 (trade name, manufactured by Photonics, USA) through an optical fiber 7 that moves simultaneously with the indenter to a mirror 6 placed on the sample dish 3. The change in the intensity of the reflected light returned to the optical fiber is converted into a voltage change by the photonic sensor 9 again, and the change in the distance between the optical fiber 7 and the mirror 6, that is, the amount of the indenter 4 pressed into the test piece 1 is measured.

The AE signal from the wedge-shaped indenter 4, which is the AE converter, is
The data is processed by the analyzer 10. This data processing analyzes the frequency distribution, the amplitude distribution, and the count (the number of AEs generated), and detects the AE signal caused by the separation between the thin film and the substrate.

On the other hand, the resolution of the electronic balance 2 as a load transducer is 0.1
It is about μg. As this load converter, for example, there is a differential transformer type, but the electronic balance is more advantageous in that it is hardly affected by mechanical vibration and does not affect displacement measurement. In addition, the optical fiber 7 and the photonic sensor 9 used as the displacement type have a high sensitivity and a displacement amount with high sensitivity by using a glass plate coated with gold, platinum, and palladium, which has a high reflectance and a small change over time. Can be measured. In addition, a non-contact displacement meter of the dielectric type can also be used.

As described above, according to the present invention, by using the AE transducer having wedge-like piezoelectricity for the indenter 45, it was possible to reduce the breakage at the time of pushing and to measure the peel strength of the thin film in various directions. For example, an experiment was conducted in which a diamond-like carbon thin film formed on a nickel-phosphorus electroless plated thin film substrate by plasma enhanced chemical vapor deposition (CVD) was used to attach another conical AE transducer to an indenter holder. In comparison with
While the conical indenter failed after several measurements, the wedge-shaped indenter showed no failure after more than 50 measurements. Also, by measuring the peel strength in two directions,
The problems of the thin film forming method were also analyzed.

As the AE converter, other piezoelectric materials such as quartz can be used in addition to the PZT shown in the embodiment, but PZT is used in view of workability and stability of AE characteristics.

〔The invention's effect〕

As described above, the present invention is capable of measuring the thin film strength in various directions without indenter breakage by indenting the test piece, deforming the test piece, and forming the shape of the indenter for detecting the AE characteristics into a wedge shape. There is an effect that an adhesive force measuring device can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an adhesive force measuring device showing one embodiment of the present invention, FIG. 2 is a side view of the indenter of FIG. 1, and FIG. 3 is a schematic diagram of an adhesive force measuring device showing an example of the prior art. is there. 1 ... test piece, 2 ... electronic balance, 3 ... sample dish, 4 and 4a
... indenter, 5 ... piezoelectric actuator, 6 ... mirror, 7 ...
... Photonic probe, 8 ... Light, 9 ... Photonic sensor, 10 ... AE analyzer, 11 ... Tilt sample table, 12 ...
... terminals, 13 ... sides, 14 ... twill.

Claims (1)

(57) [Claims] 1. A load converter having a tilting mechanism for mounting a test piece having a thin film formed on a substrate and tilting the test piece, applying a pressing deformation to the test piece and generating the test piece inside the test piece. An indenter also serving as a detector for detecting the propagation state of a crack, a driver for rotating the indenter in the vertical direction and the axis in the vertical direction, and a displacement for interlocking the driver and measuring the pushing amount of the indenter An adhesion measuring device having a gauge, wherein the indenter has a wedge shape.