KR100912220B1 - Apparatus Measuring Stress of Coating - Google Patents

Abstract

The present invention relates to an apparatus for measuring a coating stress, and more particularly, to an apparatus for obtaining a stress generated in the coating layer during drying of a coating layer coated on a substrate by measuring a positional movement of reflected light rays. The coating stress measuring apparatus of the present invention enables more precise coating stress measurement by controlling environmental variables such as temperature or humidity in a drying room that is blocked from the outside, and easily adjusts the light path by introducing a reflecting part or a distance adjusting part. Furthermore, there is an advantage that the asymmetrical bending displacement distribution can be grasped by simultaneously irradiating a plurality of light beams to all regions of the substrate through the light distribution unit and measuring the change in their respective positions. By controlling the drying process based on the information thus obtained, occurrence of cracks, peeling, wrinkles, and the like can be suppressed.

Coating, substrate, stress, warpage, drying

Description

Coating Stress Measuring Device {Apparatus Measuring Stress of Coating}

The present invention relates to an apparatus for measuring a coating stress, and more particularly, to an apparatus for obtaining a stress generated in the coating layer during drying of a coating layer coated on a substrate by measuring a positional movement of reflected light rays.

The process of coating on a substrate and drying it occupies an essential position in many industries. In particular, it is very important in the information and communication industry such as semiconductor or LCD.

However, in fact, research on liquid coatings themselves (rheology, surface chemistry, etc.) and coating processes have a long history and a considerable understanding of the phenomenon. The reality is that no research has been done.

However, as mentioned in the opening paragraph, drying of coatings coated on substrates in the telecommunications industry is regarded as an important step to influence the overall yield due to the characteristics of the industry requiring a high level of precision, and controlling them well Is emerging as a buzzword.

The reason why the drying of the coating liquid coated on the substrate is important is due to the warpage phenomenon as shown in FIG. That is, the state in which the coating liquid is first coated on the substrate 61 is a liquid state. As the solvent is evaporated from the coating layer 62 while the coating liquid is being dried, the volume of the coating layer 62 decreases, and at some point, the coating layer 62 reaches the instant of solidification. At this time, the solidification starts from the coating surface where drying occurs first and moves into the coating layer 62, and eventually reaches the interface between the coating layer 62 and the substrate 61. However, the coating layer 62 at this interface is fixed to the substrate 61 and is constrained by the reduction in volume. Thus, the coating at this point creates a tensile stress that is in fact pulled towards the edge. In this state, a situation in which the bottom portion of the coating layer 62 is pulled up arbitrarily occurs, a bending moment occurs, and as a result, a bending deflection D occurs due to bending up to the substrate 61.

If the warpage is excessively progressed beyond a certain degree, it may adversely affect the coating layer itself. For example, cracks may occur, the coating layer may be peeled off the substrate, or the coating layer may be wrinkled or distorted. Can be.

In order to prevent such a problem, it is necessary to suppress the stress occurring in the coating layer of the entire area as much as possible, and to maintain the distribution of the stress uniformly, but research on the coating stress measuring device for this is very poor.

The present invention has been made to solve the above problems, it is an object of the present invention to provide a coating stress measuring device that is easy to operate, high precision and reproducibility, and can be measured and analyzed for asymmetrical bending.

Coating stress measuring apparatus of the present invention in order to achieve the object as described above,

Light source;

A drying chamber for drying the coated substrate; And

A detector which detects light rays reflected by the coated substrate after being irradiated from the light source

It includes, the drying chamber

A window through which the light beam is transmitted;

A support for supporting the coated substrate; And

sensor

Characterized in having a.

In addition, the present invention may further include a light distribution unit for distributing 2 to 36 light rays emitted from the light source.

In addition, the present invention preferably further comprises a distance adjusting unit for adjusting the distance between the light source-substrate, the detection unit-substrate, or the light source-substrate and the detection unit-substrate.

In addition, the present invention may further include a reflector for reflecting light rays emitted from the light source.

In the present invention, at least a part of the drying chamber except for the window preferably includes a heat insulating material.

In the present invention, the sensor preferably measures temperature, humidity, or temperature and humidity.

In addition, in the present invention, the support portion may fix one end of the coated substrate.

In addition, the support may support at least a portion of the coated substrate edge.

In addition, the support portion preferably supports at least two points centered on the center of gravity of the coated substrate.

In addition, the support may be in the form of a flat plate having a through hole.

In addition, in the present invention, the detection unit may be a photodiode.

In addition, the detection unit may be a charge-coupled device camera (CCD camera).

In the present invention, the light beam is preferably a laser.

The coating stress measuring apparatus of the present invention enables more precise coating stress measurement by controlling environmental variables such as temperature or humidity in a drying room that is blocked from the outside, and easily adjusts the light path by introducing a reflecting part or a distance adjusting part. Furthermore, there is an advantage that the asymmetrical bending displacement distribution can be grasped by simultaneously irradiating a plurality of light beams to all regions of the substrate through the light distribution unit and measuring the change in their respective positions. By controlling the drying process based on the information thus obtained, occurrence of cracks, peeling, wrinkles, and the like can be suppressed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the elements of each drawing, it should be noted that the same elements are denoted by the same reference numerals as much as possible even if they are displayed on different drawings. In addition, in the following description there are shown a number of specific details such as specific components, which are provided only to help a more comprehensive understanding of the present invention, it is common in the art that the present invention may be practiced without these specific details. It is self-evident to those who have knowledge of the world. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Figure 2 is a schematic diagram showing an embodiment of the coating stress measuring apparatus of the present invention, when explaining the measuring principle of the present apparatus through the following.

First, the light beam irradiated from the light source 10 is reflected by the coated substrate 61 inside the drying chamber 20 and detected by the detector 30.

As the coated substrate 61 is dried as shown in FIG. 3, warpage occurs due to stress, and thus, the position of the light beam identified by the detector 30 changes.

When a photodiode is used as the detection unit 30, the position change is immediately expressed as a change in voltage, which is converted into a bending displacement value and a stress to be obtained in the present invention by a previously prepared correlation curve as shown in FIG. This is possible.

The above steps are explained in more detail.

Light rays detected by the detection unit 30 are reflected by the substrate 61 to be irradiated by the light source 10 to measure the bending displacement. In this case, as long as a light ray is a light ray which is excellent in linearity, there is no restriction | limiting in the kind, A laser is more preferable from a stability viewpoint.

In addition, it is preferable that the light beam passes through an appropriate reflector 17 before reaching the coated substrate 61. By introducing such a reflector 17, the path of the light beam can be changed more easily. The accuracy of the measurement can also be improved.

Meanwhile, the substrate 61 reflecting the light beam is fixed to the support part 21 inside the drying chamber 20.

The support 21 shown in FIG. 2 is an example, and shows a cantilever shape for fixing one end of the substrate 61. However, the type of the support 21 is not limited as long as the substrate 61 can be fixed.

The drying chamber 20 is preferably blocked from the outside in order to precisely observe the effect of environmental variables such as temperature or humidity on the drying, and further the bending displacement. In this case, it is preferable that the portion corresponding to the path forms the window 24 so that the light beam irradiated from the light source 10 can be reflected from the substrate 61.

In addition, it is preferable to include a sensor 27 to control the environment variable to be kept constant. In addition, it is preferable that at least a portion of the window 24 includes a heat insulating material for more precise temperature control.

Meanwhile, the light rays reflected from the coated substrate 61 are detected by the detector 30. As shown in FIG. 3, as the drying proceeds, the reflection position and the reflection angle change, so that the light rays are received by the detector 30. Position changes.

When the photodiode is used as the detection unit 30, the position change appears as a change in voltage in real time, and when this is substituted into a correlation curve prepared in advance as shown in FIG. 4, a bending displacement ('D' in FIG. 1) can be obtained. have. This bending displacement is obtained by the stress σ in the coating layer 62 by a relational formula, for example, Equation 1 below.

In the formula, E: elastic modulus

t: thickness

L: length

ν: Poisson's ratio

Subscript s: Substrate

Subscript c: coating layer

Figure 5 is a schematic diagram showing another embodiment of the coating stress measuring apparatus of the present invention.

The embodiment shown in Fig. 2 is basically a suitable case when one-dimensional analysis of such a degree of warping in the longitudinal direction is performed when the substrate 61 is generally rounded so that it is symmetrical at a certain point.

However, in this case, it is easy to generate a difference in bending displacement between one end fixed to the cantilever and the free end opposite, and there is a limit inherent in one-dimensional analysis or more.

However, this limitation can be easily overcome by the embodiment shown in FIG. 5, the light source 10 of FIG. 5 irradiates a plurality of light rays by the light distribution means therein, which is again outside the light source 10. Distributed by the light distribution unit 15, a plurality of light rays are irradiated onto the substrate 61 at the same time.

The number of the light beams to be distributed is preferably 2 to 36, and when the number of light beams exceeds 36, the spacing between the light beams is too narrow, which may cause interference with adjacent light beams.

FIG. 6 is a conceptual view showing A of FIG. 5 from another angle, in which case nine rays reach the substrate 61 at the same time as shown in FIG.

In addition, in this case, the support 21 needs to evenly support the entire area of the edge of the substrate 61, rather than the cantilever shape supporting only one side of the substrate as in the previous embodiment. As such a support form, as shown in FIG. 7, at least a part of an edge of the substrate 61, more preferably, two or more points centered on the center of gravity of the substrate 61 may be exemplified. .

Alternatively, as shown in FIG. 8, almost all regions of the substrate 61 are supported, and the region where the light rays from the light source 10 reach may be in the form of the through hole 22.

Meanwhile, in FIGS. 7 and 8, the space of the right core of the support part 21 provides an operating space of a transfer arm for lifting the substrate 61 when transferring the substrate 61.

FIG. 9 shows a case in which a total of 25 rays are irradiated onto the substrate 61, and each ray (indicated in red) irradiated at the position of the left figure showing before drying is shown as a blue dot in the right figure after drying. You can see that the position has changed.

This change in position is preferably detected by the detection unit 30 which is a charge-coupled device camera (CCD camera).

10 and 11 illustrate an example of obtaining stress based on '①' in the right drawing of FIG. 9.

In Fig. 10, after calculating δd1 (= d1 '-d1) and δd2 (= d2'-d2), the curvature κ is calculated by the following Equation 2, and substituted into the following Equation 3 to obtain the stress σ. .

In the formula, κ: curvature

R is the radius of curvature

Where M _{s is the} modulus of substrate

h _s : substrate thickness

h _f : film thickness

By arranging the curvature and stress obtained for each point, and comparing the values for the direction (①) (horizontal axis) and '②' (vertical axis) can be obtained information about the stress distribution throughout the coating layer.

Equations 2 and 3 exemplify one of methods for analyzing the warpage when the warpage does not occur evenly over the entire area of the substrate 61, and there may be many analysis methods in addition to these methods.

On the other hand, the coating stress measuring apparatus of the present invention is the light source 10-the substrate 61, the detection unit 30-the substrate 61, or the light source 10-the substrate 61 and the detection unit 30-substrate It is preferable to further include a distance adjusting unit (not shown) for adjusting the distance between the (61).

The method of detecting the position of the reflected light by irradiating the lower portion of the substrate 61 should be very sensitive to the extent of the substrate 61. Since the sensitivity is determined by the positions of the substrate 61, the light beam, and the detector 30, the devices for determining the sensitivity should be free to move the position according to the sample and the experimental conditions, so that an optimal experimental result may be obtained.

Similarly to the introduction of the reflector 15 for changing the path of the light beam, by introducing the distance adjuster, the light beam can be irradiated to the detector 30 so that a more accurate measurement is possible.

For example, the distance adjusting unit may adjust the height of the drying chamber 20.

Although the above has been illustrated and described with respect to the preferred embodiments of the present invention, the present invention is not limited to the specific embodiments described above, those skilled in the art without departing from the gist of the present invention various modifications Of course, implementation is possible. Therefore, the scope of the present invention should not be construed as being limited to the above embodiments, but should be defined by the claims below and equivalents thereof.

1 is a view illustrating a process in which bending displacement occurs in a coated substrate as drying proceeds.

Figure 2 is a conceptual diagram showing an embodiment of the coating stress measuring apparatus of the present invention.

3 is a diagram illustrating a phenomenon in which bending displacement occurs when the substrate and the coating layer are twisted.

4 is a graph showing the correlation between the bending deflection and the voltage when the photodiode is used as the detection unit.

Figure 5 is a conceptual diagram showing another embodiment of the coating stress measuring apparatus of the present invention.

FIG. 6 is a view illustrating portion A of FIG. 5 from another angle.

7 is a view showing an embodiment of the support of the present invention.

8 is a view showing another embodiment of the support of the present invention.

FIG. 9 is a view showing the positional change before and after drying when a plurality of light beams are irradiated to the substrate at the same time.

FIG. 10 is a view illustrating a process of measuring bending displacement in part ① of FIG. 9.

11 is a diagram illustrating variables for measuring curvature and stress.

** Description of the symbols for the main parts of the drawings **

10: light source 15: light distribution

17: reflection part 20: drying chamber

21: support portion 22: through hole

24: Window 27: Sensor

30: detector 61: substrate

62: coating layer

Claims (11)

Light source; A drying chamber for drying the coated substrate; A detector for detecting a light beam reflected by the coated substrate after being irradiated from the light source; A light distribution unit for distributing 3 to 36 light beams emitted from the light source; And The distance adjusting unit adjusts the distance between the light source-substrate, the detection unit-substrate, or the light source-substrate and the detection unit-substrate by adjusting the height of the drying chamber. It includes, the drying chamber A window through which the light beam is transmitted; A support for supporting the coated substrate; And sensor Coating stress measuring apparatus comprising a. delete delete The method according to claim 1 or 2, Coating stress measuring apparatus further comprises a reflector for reflecting the light emitted from the light source. The method according to claim 1 or 2, Coating stress measuring apparatus, characterized in that at least a part of the drying chamber except the window comprises a heat insulating material. The method according to claim 1 or 2, The sensor is a coating stress measuring apparatus, characterized in that for measuring the temperature, humidity or temperature and humidity. The method according to claim 1 or 2, The support portion coating stress measuring apparatus, characterized in that for fixing one end of the coated substrate. The method according to claim 1 or 2, And said support portion supports at least a portion of said coated substrate edges. The method according to claim 1 or 2, The support portion is a coating stress measuring device, characterized in that the flat plate having a through-hole. The method according to claim 1 or 2, The detector is a coating stress measuring apparatus, characterized in that the photodiode (photodiode). The method according to claim 1 or 2, The detection unit is a coating stress measuring device, characterized in that the charge-coupled device camera (CCD camera).

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