Plasma processing method and bonding system

Abstract

To provide a method for processing plasma and a junction system which can accurately join a first junction member and a second junction member to each other while suppressing damages on the first junction member and the second junction member.SOLUTION: The present invention includes the steps of: preparing a first junction member and a second junction member on which first plasma processing has been done in a vacuum atmosphere and performing second plasma processing on one of the first joint member and the second joint member in an atmosphere which is less vacuum than the atmosphere of the first plasma processing; and joining the first junction member and the second junction member to each other.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a plasma processing method and a bonding system. [Background technology]

[0002] It has been widely known that plasma treatment is performed to give a target object a predetermined function. For example, in the method described in Patent Document 1, a laminate of a polymer film and an inorganic substrate is subjected to an inactivation treatment selected from a group including a vacuum plasma treatment and an atmospheric plasma treatment using a specific atmospheric pressure plasma, thereby realizing a laminate having a small transition region width between a good adhesion part having a high adhesive strength between the film and the substrate and an easy peeling part having a low adhesive strength. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-149040 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the steps of semiconductor manufacturing processing, when the object of plasma processing is something that is easily affected by plasma irradiation, such as a wafer, there is a risk that the wafer may be damaged depending on the mode of plasma processing.

[0005] Incidentally, these problems generally occur in common when the object of plasma processing is something other than a wafer.

[0006] Therefore, an object of the present disclosure is to provide a plasma processing method and a bonding system that can accurately achieve the purpose of the plasma processing while suppressing damage to a target of the plasma processing. [Means for solving the problem]

[0007] The plasma processing method of the present disclosure includes a step of preparing a first bonding member and a second bonding member that have been subjected to a first plasma treatment in a vacuum atmosphere, performing a second plasma treatment on the first bonding member or the second bonding member in an atmosphere with a lower degree of vacuum than the first plasma treatment, and a step of bonding the first bonding member and the second bonding member.

[0008] Even if the surface of the first or second joining member is once modified by the first plasma treatment, the degree of modification of the surface deteriorates over time. However, by performing the second plasma treatment on the first or second joining member in this way, the degree of modification of the surface can be restored. The second plasma treatment used here is a plasma treatment with a lower degree of vacuum than the first plasma treatment, so that the surface modification of the member, which is the purpose of the plasma treatment, can be achieved while suppressing damage to the first or second joining member.

[0009] In the plasma processing method of the present disclosure, the second plasma processing may be a plasma processing performed in an atmospheric pressure atmosphere.

[0010] In this way, by using the second plasma treatment performed in an atmospheric pressure atmosphere when restoring the degree of surface modification of the first bonding member or the second bonding member, damage to the first bonding member or the second bonding member due to the plasma treatment can be further prevented.

[0011] In the plasma processing method of the present disclosure, the second plasma treatment may be a treatment for reducing a contact angle of water at a joint between the first bonding member and the second bonding member.

[0012] In this way, the affinity of the first and second bonding members for water is improved by the plasma treatment, so that hydrophilic bonding, which is a type of direct bonding, can be performed appropriately.

[0013] In the plasma processing method of the present disclosure, the second plasma treatment may be a treatment for increasing the ratio of hydrophilic functional groups at the bonding portions of the first bonding member and the second bonding member.

[0014] In this way, the ratio of hydrophilic functional groups at the bonding portions of the first bonding member and the second bonding member is increased by plasma treatment, improving their affinity for water, and hydrophilic bonding, which is a type of direct bonding, can be performed accurately.

[0015] In the plasma processing method of the present disclosure, the bonding portions of the first bonding member and the second bonding member may be directly bonded to each other by hydrophilic bonding using a hydrophilic functional group.

[0016] In this manner, the first and second bonding members can perform hydrophilic bonding, which is a type of direct bonding, by using hydrophilic functional groups whose ratio is increased by the plasma treatment.

[0017] In the plasma processing method of the present disclosure, the hydrophilic bonding may be performed in a state in which water is held at the bonding portion between the first bonding member and the second bonding member.

[0018] In this manner, hydrophilic bonding, which is a type of direct bonding, can be performed more accurately while water is held at the bonding portions of the first bonding member and the second bonding member.

[0019] In the plasma processing method of the present disclosure, the first bonding member may be a wafer, the second bonding member may be a substrate, the first plasma processing may be performed in a pre-process of a semiconductor manufacturing process including a process of forming a predetermined pattern on the wafer, and the second plasma processing may be performed in a post-process of the semiconductor manufacturing process including a process of mounting a semiconductor chip cut from the wafer on the substrate.

[0020] In this way, even if a predetermined time elapses between the pre-processing and the post-processing of the semiconductor manufacturing process after the first plasma treatment has been performed in the pre-processing and the post-processing of the semiconductor manufacturing process, causing a deterioration in the degree of modification of the surface of the joining portion of the first joining member or the second joining member, the second plasma treatment can be performed in the post-processing of the semiconductor manufacturing process to preferably restore the degree of modification of the surface of the first joining member or the second joining member.

[0021] The bonding system of the present disclosure is a bonding system for bonding a first bonding member and a second bonding member that have been subjected to a first plasma treatment in a vacuum atmosphere, and includes a plasma processing unit that performs a second plasma treatment on the first bonding member or the second bonding member in an atmosphere with a lower degree of vacuum than the first plasma treatment, and a bonding unit that bonds the first bonding member and the second bonding member.

[0022] Even if the surface of the first or second joining member is once modified by the first plasma treatment, the degree of modification of the surface deteriorates over time. However, by performing the second plasma treatment on the first or second joining member in this way, the degree of modification of the surface can be restored. The second plasma treatment used here is a plasma treatment with a lower degree of vacuum than the first plasma treatment, so that the surface modification of the member, which is the purpose of the plasma treatment, can be achieved while suppressing damage to the first or second joining member. Effect of the Invention

[0023] The present disclosure makes it possible to accurately join the first joining member and the second joining member while suppressing damage to the first joining member or the second joining member. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a diagram for explaining an example of an outline of a vacuum plasma process. [Diagram 2] FIG. 1 is a diagram for explaining an example of an outline of a vacuum plasma process. [Diagram 3] FIG. 1 is a diagram for explaining an example of an outline of atmospheric pressure plasma processing. [Figure 4] FIG. 1 is a diagram for explaining an example of an outline of a plasma processing method. [Diagram 5] 1 is a flowchart showing an example of the contents of a plasma processing method. [Figure 6] 10 is a flowchart showing an example of the contents of a joining process. [Figure 7] 1A to 1C are diagrams for explaining the operation of a plasma processing method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of a plasma processing method will be described with reference to the drawings.

[0026] In summary, the plasma processing method of the present invention is applied to semiconductor manufacturing processing, and includes performing a second plasma processing in a post-process with a lower vacuum than the first plasma processing on a first bonding member and a second bonding member that have been subjected to a first plasma processing in a vacuum atmosphere in a pre-process. Here, the pre-process and the post-process can be performed close to each other in time, for example, consecutively, but in this embodiment, it is assumed that the pre-process is performed in a different environment and the post-process is performed after a certain time. In this specification, the term "preparation" refers to applying the member processed in the pre-process so that the post-process can be performed, that is, carrying it in and performing the processing required before the second plasma processing. Therefore, this embodiment also covers an aspect in which the post-process is started by carrying in the member that is the result of carrying out the pre-process without carrying out the pre-process and performing the processing required before the second plasma processing.

[0027] Next, the plasma processing method of the present embodiment will be described with reference to the drawings. First, as a pre-process, a vacuum plasma processing is performed on a wafer. The wafer includes a first wafer to be diced and a second wafer on which semiconductor chips are mounted.

[0028] As shown in FIG. 1, the vacuum plasma processing is performed, for example, by placing a wafer 13 on counter electrodes 10, 11 provided in a chamber. An RF power source 12 is connected to the counter electrodes 10, 11 to generate plasma between the counter electrodes 10, 11. The wafers 13 may be plasma-processed one by one, or multiple wafers may be plasma-processed simultaneously. As shown in FIG. 2, the vacuum plasma processing may be performed by connecting RF power sources 12A, 12B to the counter electrodes 10, 11, respectively, and applying AC powers of different voltage values ​​and frequencies to the counter electrodes 10, 11, respectively, to irradiate plasma between the counter electrodes 10, 11. The plasma-processed wafer 13 is taken out of the chamber by a hand (not shown) and transported by a magazine or the like.

[0029] Here, the vacuum plasma treatment is an example of the first plasma treatment, which is a plasma treatment performed in a vacuum atmosphere. The vacuum plasma treatment is, for example, a direct plasma irradiation method in which a substrate is directly placed between electrodes (plasma space) and irradiated with plasma, for the purpose of high speed processing.

[0030] The wafer that has been through the pre-processing is then carried into a bonding system that is used in the post-processing. The bonding system performs a dicing process on the carried-in wafer (first wafer) to fabricate semiconductor chips, and performs a cleaning process on the bonded portions of the fabricated semiconductor chips and the wafer (second wafer). Next, atmospheric pressure plasma processing is performed on the bonded portions of the semiconductor chips and the wafer that have been subjected to the cleaning process.

[0031] 3, the atmospheric pressure plasma treatment is performed by a plasma irradiation unit 14 provided above the driving stage 20. The plasma irradiation unit 14 is composed of a pair of opposing electrodes 15, 16, and irradiates the wafer 13 placed on the driving stage 20 with plasma from below the opposing electrodes 15, 16. An RF power supply 17 is connected to the opposing electrode 15, and is configured to be able to perform plasma treatment continuously on the wafer 13 placed on the driving stage 20.

[0032] Here, the atmospheric pressure plasma treatment is an example of the second plasma treatment, and is a plasma treatment performed in an atmospheric pressure atmosphere with a lower degree of vacuum than the vacuum plasma treatment. For example, the atmospheric pressure plasma treatment is performed using a remote plasma irradiation method in which plasma is ejected from a slit for the purpose of suppressing damage to the wafer. Note that the second plasma treatment is not limited to an atmospheric pressure atmosphere, and may be performed in an atmosphere substituted with gas such as nitrogen, a pressurized atmosphere, or a low vacuum atmosphere with a lower degree of vacuum than the first plasma treatment.

[0033] Thereafter, the wafer that has been subjected to the atmospheric pressure plasma treatment is subjected to a surface hydrophilization treatment, etc., and a mounting substrate is fabricated by mounting a semiconductor chip on the wafer. The steps up to the atmospheric pressure plasma treatment corresponding to the second plasma treatment correspond to the "preparation" of the present invention. A specific example of a plasma treatment method in the bonding system will be described later with reference to Figs. 5 and 6. Note that in the following description, the second substrate is a wafer, but the second substrate is not limited to a wafer, and may be, for example, a substrate other than a wafer, such as a printed circuit board, or a substrate on which an individual semiconductor chip has already been mounted.

[0034] 4, the bonding system 100 includes, as components for carrying out the above-mentioned plasma processing, for example, a dicing device 110, a cleaning device 120, a plasma processing device 130, and a surface hydrophilization device 140. Each device may be arranged enclosed in the same housing, or may be arranged in a so-called line, and items processed in each device may be transferred to the next process by a conveying device or by hand. In addition, the bonding system may include devices for other processing steps, without being limited to these devices.

[0035] The dicing device 110 is a device that cuts a disk-shaped wafer into a lattice pattern and separates ICs (integrated circuits) formed on the wafer into individual semiconductor chips.

[0036] The cleaning apparatus 120 is a device that uses a sponge or the like to scrub and gently wash the surface of the semiconductor chips diced by the dicing apparatus 110, thereby cleaning the wafer cutting debris, adhesives, and other organic matter generated by the dicing apparatus 110.

[0037] The plasma processing apparatus 130 is an apparatus that performs the second plasma processing. Specifically, the plasma processing apparatus 130 performs atmospheric pressure plasma processing on the bonding portion between the semiconductor chip cleaned by the cleaning apparatus 120 and the wafer on which the semiconductor chip is mounted. For example, the plasma processing apparatus 130 removes a coating layer such as an oxide film formed on the surface layer over time at the bonding portion between the semiconductor chip and the wafer, the surface of which has been modified by vacuum plasma processing in the pre-process of the semiconductor manufacturing process, by atmospheric pressure plasma processing, thereby modifying the surface. At this time, the atmospheric pressure plasma processing causes less damage to the bonding portion of the wafer than the vacuum plasma processing, and therefore has the advantage of being able to modify the surface while suppressing damage to the target of the plasma processing.

[0038] The surface hydrophilization device 140 hydrophilizes the mutual junction of the semiconductor chip and the substrate that have been subjected to the atmospheric pressure plasma treatment by the plasma treatment device 130. The surface hydrophilization device 140, for example, supplies pure water to the semiconductor chip or the substrate while rotating the semiconductor chip or the substrate held by the spin chuck, and diffuses the pure water into the mutual junction of the semiconductor chip and the substrate to hydrophilize it. Here, "hydrophilization" refers to a process that increases the ratio of hydrophilic functional groups on the surfaces of the semiconductor chip and the substrate, thereby reducing the contact angle with water on the surfaces of the semiconductor chip and the substrate and increasing the affinity for water. In hydrophilization, the hydrophilization is performed smoothly by holding water in the hydrophilic functional groups formed on the mutual junction of the semiconductor chip and the substrate, thereby appropriately maintaining the distance between the hydrophilic functional groups.

[0039] (Specific example of plasma treatment method) Next, an example of the plasma processing method of this embodiment will be described with reference to the flow charts shown in FIGS.

[0040] 5, first, wafers that have been subjected to vacuum plasma processing in a pre-process of semiconductor manufacturing processing are carried in (step S100). The carried in wafers include a first wafer to be diced and a second wafer on which semiconductor chips fabricated by dicing the first wafer are mounted. This carrying in may include, for example, storing wafers that have been plasma-processed in another location or device, and transporting them to carry them into the bonding system 100.

[0041] Next, the wafer (first wafer) carried in the previous step S100 is diced to fabricate semiconductor chips (step S200). Specifically, the disk-shaped wafer (first wafer) prepared in the previous step S100 is cut into a lattice pattern, and ICs (integrated circuits) formed on the wafer are separated into individual semiconductor chips to fabricate the semiconductor chips.

[0042] Next, a bonding process is performed between the wafer (second wafer) carried in the previous step S100 and the semiconductor chip fabricated in the previous step S200 (step S300).

[0043] Detailed steps of the bonding process are shown in Fig. 6. As shown in Fig. 6, in the bonding process, first, the semiconductor chip produced in the previous step S300 is washed (step S310). Specifically, the bonding portion between the substrate and the semiconductor chip produced in the previous step S300 is scrubbed or gently washed using a sponge or the like to clean off the wafer cutting chips generated during dicing, organic matter such as adhesive, and the like.

[0044] Next, the semiconductor chip cleaned in the previous step S310 is subjected to atmospheric pressure plasma treatment to modify the surface of the semiconductor chip (step S320). Specifically, the surface of the semiconductor chip cleaned in the previous step S310 is modified by removing a coating layer such as an oxide film that has formed on the surface over time at the bonding portion between the semiconductor chip and the substrate by the atmospheric pressure plasma treatment.

[0045] Next, the surface of the semiconductor chip modified in the previous step S320 is made hydrophilic (step S330). Specifically, while rotating the semiconductor chip modified in the previous step S320 while being held by a spin chuck, pure water is supplied to the semiconductor chip, and the pure water is diffused in the bonding portion of the semiconductor chip with the substrate, thereby making the surface hydrophilic.

[0046] Next, the substrate (second wafer) carried in the previous step S100 is cleaned (step S340). Specifically, the bonding portion between the substrate and the semiconductor chip prepared in the previous step S100 is scrubbed and washed with a sponge or the like, for example, to clean the surface of the substrate.

[0047] Next, the substrate cleaned in the previous step S340 is subjected to atmospheric pressure plasma treatment to modify the surface of the substrate (step S350). Specifically, a coating layer such as an oxide film that has formed over time on the surface of the bonded portion of the substrate cleaned in the previous step S340 with the semiconductor chip is removed by atmospheric pressure plasma treatment to modify the surface.

[0048] Next, the surface of the substrate whose surface has been modified in the previous step S350 is made hydrophilic (step S360). Specifically, while rotating the substrate whose surface has been modified in the previous step S350 while being held by a spin chuck, pure water is supplied to the substrate, and the pure water is diffused into the bonded portion of the substrate with the semiconductor chip, thereby making the substrate hydrophilic.

[0049] Next, the surface of the semiconductor chip that has been hydrophilized in the previous step S330 and the surface of the substrate that has been hydrophilized in the previous step S360 are pressed against each other while overlapping each other to bond the semiconductor chip and the substrate (step S370), thereby completing the flow chart shown in Fig. 5. In the above plasma treatment, the atmospheric pressure plasma treatment is performed on both the semiconductor chip and the substrate, but the atmospheric pressure plasma treatment may be performed on only one of the semiconductor chip and the substrate.

[0050] Next, the operation of the plasma processing method of this embodiment will be described.

[0051] As shown in FIG. 7, in this embodiment, the initial contact angle of the wafer with respect to water is relatively high (corresponding to (1)). Then, when vacuum plasma processing is performed on the wafer in the front-end process of the semiconductor manufacturing process, the contact angle of the wafer with respect to water is significantly reduced (corresponding to (2)). After the vacuum plasma processing is performed, when a certain amount of time has passed, including the process of moving from the front-end process to the back-end process of the semiconductor manufacturing process, the contact angle of the wafer with respect to water, which had been reduced by the vacuum plasma processing, gradually increases (corresponding to (3)). In other words, the hydrophilicity of the wafer is gradually lost immediately after the vacuum plasma processing. Therefore, by performing atmospheric pressure plasma processing on such a wafer, the contact angle of the wafer with respect to water is reset (corresponding to (4)). By performing atmospheric pressure plasma processing, it is possible to restore the hydrophilicity of the wafer surface while suppressing damage to the wafer.

[0052] That is, even if a coating layer such as an oxide film is formed on the wafer surface over time after the wafer surface is modified by the vacuum plasma treatment, causing the modification of the wafer surface to deteriorate, the coating layer formed on the wafer surface is removed by performing atmospheric plasma treatment on the wafer, and the contact angle of the wafer with respect to water is reset. In this case, atmospheric plasma treatment causes less damage to the wafer than vacuum plasma treatment, so that the wafer bonding process can be performed smoothly while minimizing damage to the wafer.

[0053] The above embodiment can also be implemented in the following forms.

[0054] In the above embodiment, the case where a semiconductor chip and a substrate are bonded is described as an example. However, the combination of objects to be bonded is not limited to a semiconductor chip and a substrate, and may be any combination that allows bonding. In addition, the manner of bonding between the semiconductor chip and the substrate is not limited to direct bonding in which the two are directly bonded, but may be indirect bonding in which the semiconductor chip and the substrate are indirectly bonded by interposing an adhesive such as a resin between them.

[0055] The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The elements of the embodiments, as well as their arrangements, materials, conditions, shapes, sizes, etc., are not limited to those shown as examples and can be changed as appropriate. In addition, configurations shown in different embodiments can be replaced or combined in terms of regions. [Explanation of symbols]

[0056] 10, 11...counter electrode, 12, 12A, 12B...RF power supply, 13...wafer, 14...plasma irradiation unit, 15, 16...counter electrode, 17...RF power supply, 20...driving stage, 100...bonding system, 110...dicing device, 120...cleaning device, 130...plasma processing device, 140...surface hydrophilization device.

Claims

1. A first plasma treatment process is performed on bonding surfaces of a first wafer which is singulated to become a first bonding member, and a second wafer to which the first bonding member singulated from the first wafer is bonded, the first plasma treatment process being performed in a vacuum atmosphere and reducing the contact angles of the first and second wafers with water; a dicing step of cutting the first wafer processed by the first plasma processing step into individual pieces to form the first bonding members; a second plasma treatment process performed on the first wafer cut by the dicing process and subjected to a cleaning process and the second wafer subjected to the first plasma treatment process, the second plasma treatment process being performed in an atmosphere with a lower degree of vacuum than the first plasma treatment process and reducing the contact angles of the first and second wafers with respect to water; a step of bonding the first bonding member obtained from the first wafer that has been subjected to the second plasma processing step with a second bonding member obtained from the second wafer that has been subjected to the second plasma processing step; Including, Plasma treatment method.

2. The second plasma treatment step is a plasma treatment performed in an atmospheric pressure atmosphere. The plasma processing method according to claim 1 .

3. the first bonding member is a semiconductor chip cut from a wafer and separated into individual pieces, the second bonding member is a substrate, the first plasma processing step is performed in a pre-process of a semiconductor manufacturing process including a step of forming a predetermined pattern on the wafer, The second plasma treatment step is performed in a later step of a semiconductor manufacturing process including a step of mounting the semiconductor chip on a substrate. The plasma processing method according to claim 1 .

4. A joining system for joining a first joining member and a second joining member, a first plasma processing unit that performs a first plasma treatment on bonding surfaces of a first wafer that is cut into pieces to become the first bonding members and a second wafer to which the first bonding members cut from the first wafer are bonded, the first plasma treatment being performed in a vacuum atmosphere and reducing contact angles of the first and second wafers with water; a dicing processing section for cutting the first wafer that has been plasma-processed by the first plasma processing section into individual pieces to form the first bonding members; a second plasma processing unit that performs a second plasma processing on the first wafer cut by the dicing processing unit and cleaned, and the second wafer that has been subjected to the first plasma processing, the second plasma processing being performed in an atmosphere with a lower degree of vacuum than the first plasma processing, and reducing the contact angles of the first and second wafers with respect to water; a bonding section that bonds the first bonding member obtained from the first wafer that has been subjected to the second plasma treatment by the second plasma processing section and the second bonding member obtained from the second wafer that has been subjected to the second plasma treatment, Joining system.

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