Joint strength measurement method, joint strength measurement system, and joint strength measurement program

Abstract

To provide a joint strength measurement method, a joint strength measurement system, and a joint strength measurement program that can accurately measure joint strength. [Solution] The bonding strength measurement method according to the present invention is a bonding strength measurement method for measuring the bonding strength of a bonded substrate in which a first substrate and a second substrate are bonded, and comprises: step S1 of measuring the thickness distribution of the first substrate and the second substrate; step S2 of inserting a blade between the first substrate and the second substrate to generate a crack; step S3 of extracting the area from the tip of the blade to the end of the crack as a delamination area; step S4 of determining the average thickness of the first substrate and the second substrate in the delamination area based on their respective thickness distributions; and step S5 of determining the bonding strength of the bonded substrate based on the Young's modulus of the first substrate and the second substrate, the average thickness of the first substrate and the second substrate, the distance of the delamination area, and the thickness of the blade.

Description

Technical Field

[0001] The present invention relates to a bonding strength measurement method, a bonding strength measurement system, and a bonding strength measurement program.

Background Art

[0002] As a method for measuring the bonding strength of a bonded substrate formed by bonding wafers, the "blade method" is known, in which a blade is inserted into the bonding interface, and calculation is performed from the distance of the generated crack, the thickness of the wafer, the thickness of the blade, and the Young's modulus of the wafer (Patent Document 1).

Prior Art Literature

Patent Document

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] Strictly speaking, the thickness of a wafer is not constant, and may vary slightly depending on the location. However, in the conventional blade method, deviations in wafer thickness are not taken into account, and the wafer thickness at the location where the crack actually occurs may not match the wafer thickness used for calculation. For this reason, there has been a problem that the bonding strength may not be obtained with high accuracy in some cases.

[0005] In view of the above problems, an object of the present disclosure is to provide a bonding strength measurement method, a bonding strength measurement system, and a bonding strength measurement program that can measure bonding strength with high accuracy.

Means for Solving the Problems

[0006] A bonding strength measurement method according to one aspect of the present disclosure is a bonding strength measurement method for measuring the bonding strength of a bonded substrate formed by bonding a first substrate and a second substrate, comprising the steps of: measuring the thickness distribution of the first substrate and the second substrate; inserting a blade between the first substrate and the second substrate to generate a crack; extracting the area from the tip of the blade to the end of the crack as a delamination area; determining the average thickness of the first substrate and the second substrate in the delamination area based on the respective thickness distributions; and determining the bonding strength of the bonded substrate based on the Young's modulus of the first substrate and the second substrate, the average thickness of the first substrate and the second substrate, the distance of the delamination area, and the thickness of the blade.

[0007] A bonding strength measurement system according to one aspect of the present disclosure is a bonding strength measurement system for measuring the bonding strength of a bonded substrate formed by bonding a first substrate and a second substrate, comprising: a thickness distribution measuring unit for measuring the thickness distribution of the first substrate and the second substrate; a crack generating unit for inserting a blade between the first substrate and the second substrate to generate a crack; a delamination unit for extracting the area from the tip of the blade to the end of the crack as a delamination unit; an average thickness calculation unit for determining the average thickness of the first substrate and the second substrate in the delamination unit based on the respective thickness distributions; and a bonding strength calculation unit for determining the bonding strength of the bonded substrate based on the Young's modulus of the first substrate and the second substrate, the average thickness of the first substrate and the second substrate, the distance of the delamination unit, and the thickness of the blade.

[0008] A bonding strength measurement program according to one aspect of the present disclosure is a bonding strength measurement program for measuring the bonding strength of a bonded substrate formed by bonding a first substrate and a second substrate, and causes a computer to perform the following steps: measuring the thickness distribution of the first substrate and the second substrate; inserting a blade between the first substrate and the second substrate to generate a crack; extracting the area from the tip of the blade to the end of the crack as a delamination area; determining the average thickness of the first substrate and the second substrate in the delamination area based on the respective thickness distributions; and determining the bonding strength of the bonded substrate based on the Young's modulus of the first substrate and the second substrate, the average thickness of the first substrate and the second substrate, the distance of the delamination area, and the thickness of the blade. [Effects of the Invention]

[0009] The present invention provides a joint strength measurement method, a joint strength measurement system, and a joint strength measurement program that can accurately measure joint strength. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram showing the configuration of the joint strength measurement program according to this embodiment. [Figure 2] This is a schematic diagram illustrating the operation of the crack generation section according to this embodiment. [Figure 3] This is a schematic diagram illustrating the operation of the peeling portion extraction unit according to this embodiment. [Figure 4] This is a schematic diagram showing an example of the thickness distribution of the first substrate. [Figure 5] This is a flowchart illustrating the joint strength measurement method according to this embodiment. [Figure 6] This graph shows an example of the relationship between the time from blade insertion to extraction of the peeled portion and the length of the extracted peeled portion. [Modes for carrying out the invention]

[0011] The following describes specific embodiments to which the present invention is applied, with reference to the drawings. However, the present invention is not limited to the following embodiments. In this specification, terms such as "parallel," "perpendicular," "orthogonal," and "identical," which specify shapes, geometric conditions, and their degrees, shall not be interpreted strictly, but shall be interpreted to include a range that can be expected to function similarly. For clarity, the following descriptions and drawings have been simplified as appropriate. In each drawing, the same or corresponding elements are denoted by the same reference numeral, and redundant explanations have been omitted where necessary for clarity.

[0012] (Joint strength measurement system) First, the bonding strength measurement system 100 according to this disclosure will be described. The bonding strength measurement system 100 measures the bonding strength of a bonded substrate formed by bonding a first substrate and a second substrate. In this embodiment, the first substrate and the second substrate are wafer-type substrates.

[0013] Figure 1 is a block diagram illustrating the schematic of the joint strength measurement system 100 according to this disclosure. As shown in Figure 1, the joint strength measurement system 100 comprises a thickness distribution measurement unit 110, a crack generation unit 120, a delamination unit extraction unit 130, an average thickness calculation unit 140, and a joint strength calculation unit 150. Each element of the joint strength measurement system 100 may be controlled by a user or by a CPU (Central Processing Unit) equipped with a memory in which a program is stored.

[0014] The thickness distribution measurement unit 110 measures the thickness distribution of the first substrate and the second substrate. In this embodiment, the thickness distribution measurement unit 110 is composed of a known device capable of measuring the thickness distribution of a wafer. For example, the thickness distribution measurement unit 110 irradiates the substrate to be measured with infrared light and measures the thickness of the substrate at each point from the result of the interference between the light reflected from the substrate surface and the light that passes through the inside of the substrate and is reflected from the back surface. The thickness distribution data obtained by the thickness distribution measurement unit 110 is output to the average thickness calculation unit 140.

[0015] The crack generating unit 120 generates cracks by inserting a blade between the first substrate and the second substrate. Figure 2 is a schematic diagram illustrating the operation of the crack generating unit 120 in this embodiment. As shown in Figure 2, the crack generating unit 120 consists of a blade 121 with thickness h, a motor 122 capable of driving the blade 121, and a computer 123 that controls the motor 122. The bonded substrate 10, to which the first substrate 11 and the second substrate 12 are joined, is fixed by a stage (not shown). In this state, the computer 123 controls the motor 122 to insert the blade 121 between the first substrate 11 and the second substrate 12, thereby generating cracks within the bonded substrate 10.

[0016] The delamination extraction unit 130 extracts the area from the tip of the blade to the end of the crack as the delamination area in a cracked bonded substrate. Figure 3 is a schematic diagram illustrating the operation of the delamination extraction unit 130 in this embodiment. As shown in Figure 3, the delamination extraction unit 130 consists of an imaging device 131 and a computer 132 capable of analyzing the imaging data. The imaging device 131 images the surface of the cracked bonded substrate 10 and outputs the imaging data to the computer 132. At this time, the area from the tip of the blade to the end of the crack is imaged with a different brightness than the area without a crack. Therefore, the computer 132 can extract the delamination area 13 by binarizing the obtained image of the bonded substrate 10 and identifying the area with different brightness. Information on where the delamination area 13 is located on the bonded substrate 10 is output to the average thickness calculation unit 140.

[0017] The average thickness calculation unit 140 obtains the average thicknesses of the first substrate and the second substrate in the peeled portion based on the respective thickness distributions. In the present embodiment, the average thickness calculation unit 140 is configured by a CPU including a memory storing a program. Here, to describe the operation of the average thickness calculation unit 140, FIG. 4 shows an example of the thickness distribution of the first substrate 11 acquired by the thickness distribution measurement unit 110. In FIG. 4, the position corresponding to the peeled portion 13 extracted by the peeled portion extraction unit 130 is shown in an overlapping manner. The average thickness calculation unit 140 focuses only on each point included in the peeled portion 13 in the thickness distribution of the first substrate 11, and calculates the average value of the thicknesses in the relevant portion. Similarly for the second substrate, the average value of the thicknesses at each point included in the peeled portion 13 is calculated. In this way, the average thicknesses of the first substrate and the second substrate in the peeled portion are obtained. These values are output to the bonding strength calculation unit 150.

[0018] The bonding strength calculation unit 150 obtains the bonding strength of the bonded substrate based on the Young's moduli of the first substrate and the second substrate, the average thicknesses of the first substrate and the second substrate, the distance of the peeled portion, and the thickness of the blade. In the present embodiment, the bonding strength calculation unit 150 is configured by a CPU including a memory storing a program. Further, the bonding strength calculation unit 150 acquires the Young's modulus E1 of the first substrate, the Young's modulus E2 of the second substrate, the average thickness t1 of the first substrate in the peeled portion, the average thickness t2 of the second substrate in the peeled portion, the distance c of the peeled portion, and the thickness h of the blade, and calculates the bonding strength F based on the following formula (1). [Formula]

[0019] Here, formula (1) is a formula in which the thickness of each substrate is replaced with the average thickness of each substrate in the peeled portion in the calculation of bonding strength in the conventional blade method. Therefore, the bonding strength can be derived with higher accuracy than the conventional blade method that does not consider the thickness distribution. Note that the following documents can be cited as the basis for formula (1). D. Maugis. Contact, Adhesion and Rupture of Elastic Solids (Springer Series in Solid-State Sciences).

[0020] In this embodiment, if the first or second substrate can transmit visible light, it is preferable to use a device that uses visible light as a light source as the imaging device 131, for example, an optical microscope. When visible light is used as the light source of the imaging device 131, the contrast in brightness between the delaminated area and other areas becomes larger compared to, for example, when infrared light is used as the light source, and the delaminated area can be extracted with greater accuracy. In addition, since visible light has a shorter wavelength than infrared light, it is possible to perform measurements with higher resolution.

[0021] (Joining strength measurement method) Next, the joint strength measurement method according to this disclosure will be described. Figure 5 is a flowchart illustrating the joint strength measurement method according to this disclosure. As shown in Figure 5, the joint strength measurement method according to this disclosure comprises steps S1 to S5.

[0022] First, in step S1, the thickness distribution of the first substrate and the second substrate is measured. Step S1 can be performed, for example, by the thickness distribution measuring unit 110. From the viewpoint of simplifying the measurement, it is preferable that step S1 be performed before the first substrate and the second substrate are joined together.

[0023] Next, in step S2, a blade is inserted between the first substrate and the second substrate to generate a crack. Step S2 can be performed, for example, by the crack generation unit 120.

[0024] Next, in step S3, the section from the tip of the blade to the end of the crack is extracted as the delamination section. Step S3 can be performed, for example, by the delamination section extraction unit 130. It is preferable to perform step S3 after a predetermined time has elapsed since inserting the blade in step S2. This predetermined time is preferably 60 seconds or more, and more preferably 90 seconds or more. Figure 6 is a graph showing an example of the relationship between the time from blade insertion to delamination section extraction and the length of the extracted delamination section. As shown in Figure 6, after 60 seconds or more have elapsed since blade insertion, the crack growth rate of the bonded substrate decreases, and the delamination section becomes less likely to become long. Therefore, by performing step S3 after 60 seconds or more have elapsed since blade insertion, the delamination section can be extracted stably.

[0025] Next, in step S4, the average thickness of the first and second substrates in the peeled area is determined based on their respective thickness distributions. Step S4 can be performed, for example, by the average thickness calculation unit 140.

[0026] Finally, in step S5, the bonding strength of the bonded substrates is determined based on the Young's moduli of the first and second substrates, the average thickness of the first and second substrates, the distance of the delamination area, and the thickness of the blade. Step S5 can be performed, for example, by the bonding strength calculation unit 150.

[0027] In the bonding strength measurement method according to this embodiment, the bonding strength of a bonded substrate formed by joining a first substrate and a second substrate can be measured as described above. According to the bonding strength measurement method of this embodiment, the bonding strength can be derived with higher accuracy than the conventional blade method, which does not take thickness distribution into consideration.

[0028] The bonding strength measurement method according to this disclosure may be performed by a program that causes a computer to execute steps S1 to S5. In this case, the program includes a set of instructions (or software code) that, when loaded into a computer, causes the computer to perform one or more of the functions described in the embodiments. The program may be stored in a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disk (DVD), Blu-ray® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrically, optically, acoustically, or otherwise propagating signals.

[0029] Although the present invention has been specifically described above based on embodiments, it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from its essence. [Explanation of symbols]

[0030] 10 Bonded substrate 11. First circuit board 12 Second board 13. Peeled section 100 Joint Strength Measurement System 110 Thickness distribution measurement section 120 Crack formation area 121 Blades 122 Motor 123 Computer 130 Peeling section extraction section 131 Imaging device 132 Computers 140 Average Thickness Calculation Unit 150 Joint strength calculation section

Claims

1. A method for measuring the bonding strength of a bonded substrate formed by joining a first substrate and a second substrate, A step of measuring the thickness distribution of the first substrate and the second substrate, The steps include inserting a blade between the first substrate and the second substrate to generate a crack, The steps include extracting the section from the tip of the blade to the end of the crack as the peeled portion, The steps include determining the average thickness of the first and second substrates in the peeled portion based on their respective thickness distributions, The method comprises the step of determining the bonding strength of the bonded substrates based on the Young's modulus of the first substrate and the second substrate, the average thickness of the first substrate and the second substrate, the distance of the delamination portion, and the thickness of the blade. Bond strength measurement method.

2. The step of extracting the peeled portion is performed after a predetermined time has elapsed since inserting the blade. The method for measuring joint strength according to claim 1.

3. The predetermined time is 60 seconds or more. The method for measuring joint strength according to claim 2.

4. In the step of extracting the delamination portion, the image of the bonded substrate captured in visible light is binarized, and regions with different brightness levels are extracted as the delamination portion. The method for measuring joint strength according to claim 1.

5. A bonding strength measuring system for measuring the bonding strength of a bonded substrate formed by joining a first substrate and a second substrate, A thickness distribution measuring unit for measuring the thickness distribution of the first substrate and the second substrate, A crack generating unit that inserts a blade between the first substrate and the second substrate to generate a crack, A peeling section extraction unit that extracts the section from the tip of the blade to the end of the crack as the peeling section, An average thickness calculation unit that determines the average thickness of the first substrate and the second substrate in the peeled portion based on the respective thickness distributions, The system includes a bonding strength calculation unit that determines the bonding strength of the bonded substrates based on the Young's modulus of the first and second substrates, the average thickness of the first and second substrates, the distance of the delamination portion, and the thickness of the blade. Joint strength measurement system.

6. A bonding strength measurement program for measuring the bonding strength of a bonded substrate formed by joining a first substrate and a second substrate, A step of measuring the thickness distribution of the first substrate and the second substrate, The steps include inserting a blade between the first substrate and the second substrate to generate a crack, The steps include extracting the section from the tip of the blade to the end of the crack as the peeled portion, The steps include determining the average thickness of the first and second substrates in the peeled portion based on their respective thickness distributions, The computer is instructed to perform the following steps: determine the bonding strength of the bonded substrates based on the Young's moduli of the first and second substrates, the average thickness of the first and second substrates, the distance of the delamination portion, and the thickness of the blade. Joint strength measurement program.

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