Method for manufacturing bonded body

Abstract

A purpose of the present disclosure is to provide a method for manufacturing a bonded body, such as a substrate or chip, that can be easily obtained with high precision.　A method for manufacturing a bonded body according to one aspect of the present disclosure is a method for manufacturing a bonded body in which a first substrate or first chip having a first electrode portion and a first non-electrode portion is bonded to a second substrate or second chip having a second electrode portion and a second non-electrode portion. The method is provided with: a step for bonding the first non-electrode portion and the second non-electrode portion to obtain a temporary bonded body; and a step for bonding the first electrode portion and the second electrode portion in the temporary bonded body. In the bonding step, the temporary bonded body is pressurized by a hot isostatic pressing method.

Description

Method for producing bonded body

[0001] The present disclosure relates to a method for producing a bonded body obtained by bonding a substrate, a chip, and the like to each other.

[0002] In recent years, there has been a demand for semiconductor substrates that achieve high performance and size reduction by increasing the density of chips, wiring, and the like. To meet this demand, high-precision mounting technology is required. A method for bonding semiconductor chips that can improve mounting precision is known (Japanese Unexamined Patent Publication No. 2014-236021).

[0003] Japanese Unexamined Patent Publication No. 2014-236021

[0004] The bonding method described in the above publication is implemented in a bonding apparatus including a temporary bonding section that temporarily bonds a semiconductor chip to a predetermined region of a substrate, and a main pressure bonding section that performs main pressure bonding of the temporarily bonded semiconductor chip. By disposing the temporary bonding section apart from the main pressure bonding section, it is possible to suppress conduction of heat to the temporary bonding section when the semiconductor chip is subjected to main pressure bonding, and thus it is described that positional displacement of the semiconductor chip during temporary bonding can be suppressed. In the above bonding method, a plurality of the semiconductor chips are brought into pressure contact with the substrate and metal-bonded by moving a main pressure bonding head of the main pressure bonding section in a normal direction to a surface of the substrate. In pressure contact in one direction, slight positional displacement may occur in the bonded portion of the semiconductor chip within a plane perpendicular to the one direction. For high-density semiconductor substrates, alignment with precision on the order of micrometers or nanometers may be required. There is a demand for bonding substrates, chips, and the like with higher precision.

[0005] The present disclosure has been made in view of the circumstances described above, and an object of the present disclosure is to provide a method for producing a bonded body, which allows easily obtaining a bonded body of highly precisely bonded substrates, chips, and the like.

[0006] A method for manufacturing a bonded body, which is one aspect of the present disclosure made to solve the above problems, is a method for manufacturing a bonded body in which a first substrate or first chip having a first electrode portion and a first non-electrode portion is joined to a second substrate or second chip having a second electrode portion and a second non-electrode portion, comprising the steps of joining the first non-electrode portion and the second non-electrode portion to obtain a temporary bonded body, and joining the first electrode portion and the second electrode portion in the temporary bonded body, wherein in the joining step, the temporary bonded body is pressurized by a hot isostatic pressing method.

[0007] One embodiment of the present disclosure is a method for manufacturing a bonded body, which allows for easy production of bonded bodies such as substrates and chips with high precision.

[0008] Figure 1 is a schematic front view showing a hot isostatic pressurizing device, which is one embodiment of the present disclosure. Figure 2 is a graph showing the results of I-V measurements of temporary joints in Test Example 1 and Test Example 2. Figure 3 is a graph showing the results of I-V measurements of joints in Test Example 1 and Test Example 2. Figure 4 is a graph showing the relationship between the number of daisy chains and the resistance value in Test Example 6.

[0009] [Description of Embodiments of the Disclosure] First, embodiments of the Disclosure will be listed and described.

[0010] (1) A method for manufacturing a bonded body according to one aspect of the present disclosure is a method for manufacturing a bonded body in which a first substrate or first chip having a first electrode portion and a first non-electrode portion is joined to a second substrate or second chip having a second electrode portion and a second non-electrode portion, comprising the steps of: joining the first non-electrode portion and the second non-electrode portion to obtain a temporary bonded body; and joining the first electrode portion and the second electrode portion in the temporary bonded body, wherein in the joining step, the temporary bonded body is pressurized by a hot isostatic pressing method.

[0011] The method for manufacturing the joint (hereinafter also simply referred to as "the manufacturing method") involves applying pressure to the temporary joint with the non-electrode portion joined by a hot isostatic pressing method. This effectively suppresses misalignment of the electrode portion while ensuring reliable joining, making it possible to easily obtain a joint with the electrode portion joined with high precision.

[0012] (2) In the above (1), it is preferable that the first electrode portion and the second electrode portion are electrically connected during the joining process. That is, this manufacturing method can produce a bonded body in which the substrate, chip, etc. are reliably electrically connected.

[0013] (3) In the above (1) or (2), multiple temporary joints may be joined simultaneously in the joining process. By joining multiple temporary joints simultaneously, multiple joints can be obtained efficiently.

[0014] (4) In any of (1) to (3) above, the joining process may be carried out in a nitrogen atmosphere, a hydrogen atmosphere, an argon atmosphere, or a mixture thereof. The joining strength of the electrode portion can be improved by joining the temporary joint in the above atmosphere.

[0015] The above-mentioned substrate refers to individually manufactured substrates (printed circuit boards), wafers cut from ingots, dies formed from individual wafers, etc. The above-mentioned chip refers to elements, devices, etc., placed on the above-mentioned substrate. The above-mentioned electrode portion refers to a conductive portion exposed on the surface of the above-mentioned substrate or chip, and means wiring (conductive patterns), contact points with electrode portions of other chips or other substrates (lands, etc.). The above-mentioned non-electrode portion refers to a non-conductive portion of the above-mentioned substrate or chip other than the above-mentioned electrode portion, and a conductive portion not exposed on the surface of the above-mentioned substrate (for example, a portion covered with a non-conductive material such as a coverlay on wiring).

[0016] [Details of the Implementation of This Disclosure] Next, one implementation of this disclosure will be described in detail with reference to the drawings.

[0017] <Method for Manufacturing a Bonded Body> The manufacturing method is a method for manufacturing a bonded body in which a first substrate or first chip having a first electrode portion and a first non-electrode portion is bonded to a second substrate or second chip having a second electrode portion and a second non-electrode portion. That is, the manufacturing method is what is called hybrid bonding, and can produce a bonded body in which substrates are bonded to each other, a bonded body in which a chip is bonded to a substrate, or a bonded body in which chips are bonded to each other. The manufacturing method comprises the steps of: obtaining a temporary bonded body by bonding the first non-electrode portion and the second non-electrode portion; and bonding the first electrode portion and the second electrode portion in the temporary bonded body. In the bonding step, the temporary bonded body is pressurized by a hot isostatic pressing method.

[0018] [Step to obtain a temporary bond] The step to obtain the temporary bond is, in other words, a step to perform temporary bonding, in which the non-electrode portions (first non-electrode portion and second non-electrode portion) of the first substrate or the first chip and the second substrate or the second chip are joined together. The method of temporary bonding is not particularly limited, and known methods such as adhesive bonding may be used. In the case of bonding substrates, if these substrates are silicon wafers or silicon dies, the surfaces to be bonded are washed with water to make them hydrophilic, and then they are bonded together, so that siloxane bonds are partially formed on each surface and the non-electrode portions (silicon surfaces) are joined together. After partial siloxane bonding, further heat treatment at 300°C to 400°C allows moisture near the interface of the partially bonded portion to diffuse, improving the bonding strength between the non-electrode portions.

[0019] [Joining Process] In the joining process described above, the temporary joint S, in which the non-electrode parts are joined together, is pressurized using the hot isostatic pressing method with a hot isostatic pressing device 1, for example, as shown in Figure 1. In the temporary joint S, the electrode parts (the first electrode part and the second electrode part) are in close proximity or in contact with each other due to the joining of the non-electrode parts. By pressurizing the temporary joint S, the surfaces of the electrode parts are joined together by metallic bonding.

[0020] The apparatus 1 comprises a housing 10 having a gas supply port 121 and a gas discharge port 131, a shelf 20 disposed inside the housing 10 on which temporary joints S formed by joining the non-electrode portions of a pair of substrates, temporary joints formed by joining the non-electrode portions of a substrate and the non-electrode portions of a chip, or temporary joints formed by joining the non-electrode portions of a pair of chips, and a heating unit (not shown) for heating the inside of the housing 10.

[0021] The temporary assembly S formed by joining (temporarily joining) the above pair of substrates may include at least one pair of substrates, and may also include multiple substrates that have been temporarily joined. The temporary assembly formed by joining chips to substrates may include multiple chips that have been temporarily joined to substrates. The temporary assembly formed by joining the above pair of chips may include at least one pair of chips, and may also include multiple chips that have been temporarily joined.

[0022] The housing 10 has a substantially cylindrical wall portion 11 and a top portion 12 and a bottom portion 13 that seal one opening of the wall portion 11. The wall portion 11 has an openable and closable door (not shown) for an operator to insert and remove the temporary joint S. A supply port 121 is formed in the top portion 12, and an outlet port 131 is formed in the bottom portion 13. The supply port and the outlet port may also be formed in the wall portion. A gas supply pipe P1 is connected to the supply port 121, and a gas discharge pipe P2 is connected to the outlet port 131. The gas supply pipe P1 includes a first valve (not shown), and the gas discharge pipe P2 includes a second valve (not shown). The supply and discharge of gas can be controlled by opening and closing these valves. By closing the second valve to block the gas discharge pipe P2 and opening the first valve to release the gas supply pipe P1, gas is supplied into the housing 10, the internal pressure increases, and the temporary joint S is pressurized.

[0023] The device 1 may be provided with multiple shelves 20 inside the housing 10. That is, the device 1 may be configured to accommodate multiple temporary joints S. By accommodating multiple temporary joints S in the device 1, they can be pressurized simultaneously, and multiple joints can be efficiently obtained.

[0024] The shelf section 20 may have through holes in the thickness direction, or be formed in a grid or mesh shape. By configuring the shelf section 20 as described above, the reliability of isotropically pressurizing the temporary joint S can be improved, and even when multiple shelf sections 20 are arranged inside the housing 10, the internal pressure can be made uniform, allowing the multiple temporary joints S to be pressurized evenly.

[0025] The material of the electrode portion is not particularly limited and may be copper, for example. When the electrode portions formed of copper are brought into close proximity or contact by the temporary joining, and pressure is applied to these electrode portions, copper atoms diffuse between their surfaces and metallic bonding occurs. A bonded body is formed when the non-electrode portions and the electrode portions are joined together.

[0026] The pressure applied to the temporary joint S in the joining process described above is not particularly limited and may be arbitrarily selected depending on the physical properties of the electrode part, the temperature inside the housing 10, the time for which pressure is applied to the temporary joint S, etc. The lower limit of the pressure may be, for example, 10 MPa or 15 MPa. The upper limit of the pressure is not particularly limited and may be, for example, 100 MPa or 50 MPa. Note that "the pressure applied to the temporary joint in the joining process described above" is the average value of the pressure maintained at a predetermined value in order to join the electrode parts together, and does not include the pressure values ​​when the inside of the housing 10 is increased or decreased in pressure.

[0027] The heating element is not particularly limited and may be, for example, a known heater. The heating element may be located inside the housing 10, on the outer surface of the housing 10, or embedded in the wall portion 11, top portion 12, or bottom portion 13 of the housing 10.

[0028] The temperature inside the housing 10 due to the heating unit in the joining process described above is not particularly limited and may be arbitrarily selected depending on the physical properties of the electrode parts, the pressure inside the housing 10, the time for which pressure is applied to the temporary joint S, etc. The lower limit of the temperature may be, for example, 150°C, 180°C, or 200°C. The upper limit of the temperature may be, for example, 500°C or 450°C. Note that "the temperature inside the housing due to the heating unit in the joining process described above" refers to the temperature when a predetermined pressure is applied to the temporary joint S in order to join the electrode parts together, and does not include the temperature when the inside of the housing 10 is pressurized or depressurized.

[0029] When heated, the electrode portion, which is made of copper, may expand. Pressurization from one direction can suppress expansion in that direction, but it may not be able to suppress expansion in other directions (for example, in a direction perpendicular to the aforementioned direction). In the joining process in this manufacturing method, the temporary joint S is uniformly pressed from all directions by the hot isostatic pressing method, so that displacement of the electrode portion due to the expansion of the copper can be suppressed in all directions, and the electrode portions can be joined to each other at a predetermined position with high precision. In addition, in the case of a water-washed temporary joint, heating causes the moisture between the surfaces of the electrode portions that are close together or in contact to diffuse, so the surface area for metallic bonding can be increased and the bonding strength can be improved.

[0030] The bonding process described above is preferably carried out in a nitrogen atmosphere, a hydrogen atmosphere, an argon atmosphere, or a mixture thereof. In other words, the bonding process is preferably carried out in a reducing atmosphere. For example, if the electrode portion is formed of copper, since copper is a noble metal, the surface exposed to air is prone to oxidation, which may reduce the bonding force between the surfaces under pressure. By applying pressure under a reducing atmosphere, oxidation of the surfaces can be suppressed, and the strength of the bond between the surfaces can be improved.

[0031] The time required to perform the above joining process is not particularly limited and may be arbitrarily selected depending on the physical properties of the electrode portion, the pressure inside the housing 10, the temperature inside the housing 10, etc. The lower limit of the above time may be, for example, 1.0 hour or 1.5 hours. The upper limit of the above time may be, for example, 3.0 hours or 2.5 hours. Note that "the time required to perform the above joining process" refers to the time during which a predetermined pressure is applied to the temporary joint S in order to join the electrode portions together, and does not include the time during which the inside of the housing 10 is pressurized or depressurized.

[0032] <Other Embodiments> The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is not limited to the configurations of the embodiments described herein, but is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0033] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0034] [Example 1] Copper electrodes were formed on dies formed from individual silicon wafers. The surface size of the electrode portion was 10 μm × 10 μm, the pitch between the electrode portions was 10 μm, and the thickness (depth) was 1 μm. The electrode portions were arranged in a daisy chain of 4160 units. The size of one die to be joined (first die) was 12 mm × 12 mm, and the size of the other die (second die) was 10 mm × 10 mm, with a thickness of 2.5 μm for each. Fiducial marks were formed on both dies.

[0035] A 500 mL autoclave (manufactured by Nitto High Pressure Co., Ltd.) was used as the hot isostatic pressurizing device. The surfaces of the first die and the second die, on which the electrode portion was formed, were washed with water, aligned based on the fiducial marks, and bonded together to obtain the temporary joints of Test Examples 1 to 5. The temporary joints were placed in the autoclave, which was kept in a reducing atmosphere, and the bonding process was carried out. The conditions for each bonding process are shown in Table 1.

[0036]

[0037] The fiducial marks on the pre-joining (temporary joint) and post-joining (joined body) of both Test Example 1 and Test Example 2 were observed using an infrared microscope. In both Test Example 1 and Test Example 2, there was no misalignment of the fiducial marks on the joined bodies, confirming that the joint was formed with high alignment accuracy.

[0038] For Test Examples 1 through 5, the I-V measurement was performed on the temporary joint and the final joint. In Test Examples 3, 4, and 5, the I-V of the joint could not be measured stably, indicating that the electrode portions were not sufficiently bonded to each other. This is thought to be due to insufficient heating temperature in Test Example 3 and insufficient pressure in Test Examples 4 and 5. Figure 2 shows the I-V measurement results of the temporary joint in Test Example 1 and Test Example 2, and Figure 3 shows the I-V measurement results of the final joint in Test Example 1 and Test Example 2. In Figures 2 and 3, the solid line represents the I-V measurement result (straight line) for Test Example 1, and the dashed line represents the I-V measurement result (straight line) for Test Example 2.

[0039] Figure 2 shows that the electrodes are not joined together in the temporary joint described above. Figure 3 shows that the I-V characteristics exhibit linear behavior, indicating that the electrodes are joined together with high precision and reliability by the hot isostatic pressing method. Furthermore, since the resistance value of Test Example 2 is more than 10% lower than that of Test Example 1, it can be seen that the reducing atmosphere provided by hydrogen promoted the bonding of the low-resistance copper.

[0040] [Example 2] Next, another pair of the dies was joined by hot isostatic pressing to obtain a joint with 33,280 daisy chains (Test Example 6). In Test Example 6, the number of daisy chains between the electrodes of the measuring instrument was varied and the resistance value was measured. The results are shown in Figure 4. As can be seen in Figure 4, the number of daisy chains and the resistance value show linear behavior, indicating an excellent correlation. From this, it can be seen that the electrode parts of the pair of dies are joined to each other with high precision and reliability by hot isostatic pressing.

[0041] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to these examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0042] This application is based on Japanese Patent Application No. 2025-056155 filed on March 28, 2025, and its contents are incorporated herein by reference.

[0043] The method for manufacturing a bonded body according to this disclosure can bond electrode parts such as substrates and chips with high precision, and is therefore suitable for use in semiconductor manufacturing and other applications.

[0044] 1 Hot isostatic pressurizing device 10 Housing 11 Wall section 12 Top section 121 Supply port 13 Bottom section 131 Discharge port 20 Shelf section P1 Gas supply pipe P2 Gas discharge pipe S Temporary joint

Claims

1. A method for manufacturing a bonded body in which a first substrate or first chip having a first electrode portion and a first non-electrode portion is joined to a second substrate or second chip having a second electrode portion and a second non-electrode portion, comprising the steps of: joining the first non-electrode portion and the second non-electrode portion to obtain a temporary bonded body; and joining the first electrode portion and the second electrode portion in the temporary bonded body, wherein in the joining step, the temporary bonded body is pressurized by a hot isostatic pressurizing method.

2. The method for manufacturing a bonded body according to claim 1, wherein the first electrode portion and the second electrode portion are electrically connected in the above bonding step.

3. The method for manufacturing a joined body according to claim 1, wherein a plurality of the above-mentioned temporary joined bodies are joined simultaneously in the above-mentioned joining step.

4. A method for manufacturing a joined body according to any one of claims 1 to 3, wherein the joining step is performed in a nitrogen atmosphere, a hydrogen atmosphere, an argon atmosphere, or a mixed atmosphere thereof.

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