Method for removing semiconductor chips, and plasma irradiation device.

Abstract

Semiconductor chips are removed from circuit boards using a simpler process that utilizes atmospheric pressure plasma. [Solution] A method for removing a semiconductor chip, comprising the steps of: placing a mask having an opening corresponding to one of the semiconductor chips on a circuit board on which a plurality of semiconductor chips are fixed with adhesive and arranged in a two-dimensional manner, at a position corresponding to a designated semiconductor chip; and irradiating the designated semiconductor chip with atmospheric pressure plasma through the opening to remove the adhesive fixing the designated semiconductor chip.

Description

Technical Field

[0001] The present invention relates to a method for removing a semiconductor chip and a plasma irradiation device.

Background Art

[0002] In recent years, attention has been paid to the atmospheric pressure plasma technology that can stably generate plasma, which was conventionally required in a vacuum process, under atmospheric pressure.

[0003] Since atmospheric pressure plasma does not require a large vacuum chamber and can continuously perform plasma processing, the productivity of plasma processing can be significantly improved. Such atmospheric pressure plasma is used for processes such as surface modification or cleaning of various products.

[0004] For example, Patent Document 1 below discloses a method for producing a surface-modified fluororesin film in which peroxide functional groups are introduced onto the surface of a fluororesin film by atmospheric pressure plasma treatment.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In addition to the introduction of functional groups onto the surface of the fluororesin film disclosed in Patent Document 1, various applications of atmospheric pressure plasma are being studied.

[0007] Therefore, the present invention proposes a novel and improved method for removing a semiconductor chip and a plasma irradiation device that can remove a semiconductor chip from a circuit board in a simpler process using atmospheric pressure plasma.

Means for Solving the Problems

[0008] To solve the above problems, according to one aspect of the present invention, a method for removing a semiconductor chip is provided, which includes the steps of: placing a mask having an opening corresponding to one of the semiconductor chips on a circuit board on which a plurality of semiconductor chips are fixed with adhesive and arranged in a two-dimensional manner, at a position corresponding to a designated semiconductor chip; and irradiating the designated semiconductor chip with atmospheric pressure plasma through the opening to remove the adhesive that fixes the designated semiconductor chip.

[0009] Furthermore, in order to solve the above problems, according to another aspect of the present invention, a plasma irradiation apparatus is provided, comprising: an alignment mechanism that moves relative to the position of a circuit board on which a plurality of semiconductor chips are fixed with adhesive and arranged in a two-dimensional manner, the position of a mask having an opening corresponding to one of the semiconductor chips, and the position of a plasma nozzle for irradiating atmospheric pressure plasma, on a plane parallel to the main surface of the circuit board on which the semiconductor chips are arranged; and a control unit that, after aligning the circuit board, the mask, and the plasma nozzle so that the position of a designated semiconductor chip corresponds to the position of the opening and the plasma nozzle, controls the plasma nozzle to irradiate the designated semiconductor chip with atmospheric pressure plasma through the opening in order to remove the adhesive fixing the designated semiconductor chip. [Effects of the Invention]

[0010] As described above, according to the present invention, it is possible to remove semiconductor chips from circuit boards using a simpler process with atmospheric pressure plasma. [Brief explanation of the drawing]

[0011] [Figure 1] This is a longitudinal cross-sectional view illustrating the object from which a semiconductor chip is removed in the present invention. [Figure 2] This is a longitudinal cross-sectional view illustrating atmospheric pressure plasma processing in one embodiment of the present invention. [Figure 3]This is a longitudinal cross-sectional view showing the state of the object after atmospheric pressure plasma treatment. [Modes for carrying out the invention]

[0012] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. In this specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0013] <1. Items to be processed> First, with reference to Figure 1, the configuration of the processing target 1 from which the semiconductor chip is removed in one embodiment of the present invention will be described. Figure 1 is a longitudinal cross-sectional view illustrating the processing target 1 from which the semiconductor chip 110 is removed in one embodiment of the present invention.

[0014] As shown in Figure 1, the object to be processed 1 includes, for example, a circuit board 100, a bump electrode 140, a semiconductor chip 110, a stopper 120, and an adhesive layer 130. The object to be processed 1 is a laminate in which the semiconductor chip 110 is bonded to the main surface of the circuit board 100. Although Figure 1 and other figures illustrate a structure in which only one semiconductor chip 110 is provided on the main surface of the circuit board 100, a large number of semiconductor chips 110 (not shown) are bonded in a two-dimensional arrangement on the main surface of the circuit board 100.

[0015] The circuit board 100 is a substrate on which circuit wiring 105, which is electrically connected to each of the semiconductor chips 110, is provided on its main surface. The circuit wiring 105 is made of a metal such as gold, silver, copper, or aluminum. The circuit wiring 105 can supply power to each of the semiconductor chips 110 bonded to the main surface of the circuit board 100 and input / output control signals via bump electrodes 140 and chip electrodes 111, which will be described later.

[0016] The circuit board 100 may be, for example, a glass substrate, a glass epoxy substrate, an epoxy substrate, a polyimide substrate, or a (meth)acrylic substrate, or it may be a flexible substrate made of polyester or polyethersulfone. The circuit board 100 is, for example, a pixel array substrate for a microLED display having a rectangular shape with sides of several tens of centimeters to 1 m.

[0017] The bump electrodes 140 are electrodes provided in multiple convex shapes on the main surface of the circuit board 100, electrically connected to the circuit wiring 105. The bump electrodes 140 electrically connect the circuit wiring 105 on the main surface of the circuit board 100 to the semiconductor chip 110. Specifically, the bump electrodes 140 are electrically connected to the chip electrodes 111 of the semiconductor chip 110 bonded to the circuit board 100. The shape of the bump electrodes 140 may be a convex shape such as a cylinder, a cylinder with a rounded tip, a cone, a cone shape, a hemispherical shape, or a flattened sphere.

[0018] More specifically, the bump electrode 140 may be configured as a resin core electrode including a resin core 141 made of organic resin and a metal coating 143 covering the surface of the resin core. With such a structure, the bump electrode 140 can more reliably connect to the chip electrode 111 of the semiconductor chip 110 by deforming the resin core 141 when compressed between the circuit board 100 and the semiconductor chip 110.

[0019] The resin core 141 may be composed of one or more organic resins such as polyolefin resin, acrylic resin, epoxy resin, silicone resin, polyimide resin, polyalkylene terephthalate resin, polysulfone resin, polycarbonate resin, polyamide resin, phenolic resin, melamine resin, urethane resin, and urea resin. The metal coating 143 may be composed of one or more metals such as gold, nickel, copper, silver, tin, and palladium.

[0020] However, the structure of the bump electrode 140 is not limited to the above. The bump electrode 140 may be composed of a single or multiple metals. For example, it may be a metal electrode formed by plating or vapor deposition, a solder paste, or a solder ball.

[0021] Two bump electrodes 140 may be provided corresponding to one semiconductor chip 110 (corresponding to the positive and negative electrodes of the semiconductor chip 110 respectively). For example, two bump electrodes 140 may be provided in a two-dimensional array on the main surface of the circuit board 100 corresponding to each of the semiconductor chips 110 two-dimensionally arranged on the main surface of the circuit board 100.

[0022] The semiconductor chip 110 is an electronic component formed of a semiconductor. The semiconductor chip 110 is joined to the main surface of the circuit board 100 via the bump electrode 140. For example, the semiconductor chip 110 may be an LED (Light-Emitting Diode) chip composed of a compound semiconductor such as gallium nitride, gallium arsenide, or silicon carbide. The semiconductor chip 110 that is an LED chip is provided in a two-dimensional array on the main surface of the circuit board 100 as a pixel of a micro LED display. Also, the semiconductor chip 110 may be an IC (Integrated Circuit) chip composed of silicon. The semiconductor chip 110 that is an IC chip is provided in a two-dimensional array on the main surface of the circuit board 100 for each group of a plurality of LED chips, for example, as a pixel control IC that controls the LED chips of a micro LED display.

[0023] On the surface of the semiconductor chip 110 facing the main surface of the circuit board 100, chip electrodes 111 for joining to the bump electrode 140 are provided. The chip electrodes 111 are electrically connected to the circuit wiring 105 provided on the circuit board 100 via the bump electrode 140. Two chip electrodes 111 (positive and negative electrodes) may be provided for one semiconductor chip 110. The chip electrodes 111 may be composed of a metal such as gold, nickel, copper, silver, or aluminum, for example.

[0024] The stopper 120 is provided projecting from the main surface of the circuit board 100 so as to surround the entire circumference of the area where the semiconductor chip 110 is bonded. In other words, the stopper 120 is provided projecting from the main surface of the circuit board 100 so as to separate the areas where the semiconductor chip 110 is bonded from each other. The stopper 120 may be made of a patterned organic resin. For example, the stopper 120 may be made of one or more of the organic resins listed as organic resins constituting the resin core 141.

[0025] The stopper 120 functions as a guide to hold the semiconductor chip 110 in place so that it does not shift laterally when the circuit board 100 and the semiconductor chip 110 are joined together. The stopper 120 also functions to hold the adhesive layer 130 that bonds the semiconductor chip 110 to the circuit board 100 around the semiconductor chip 110.

[0026] The adhesive layer 130 is provided in the area surrounded by the stopper 120 and adheres the semiconductor chip 110 and the circuit board 100. Specifically, the adhesive layer 130 is provided by filling the space surrounded by the semiconductor chip 110, the circuit board 100, and the stopper 120 with a thermosetting adhesive. For example, the adhesive layer 130 may be composed of a phenolic thermosetting adhesive, an epoxy thermosetting adhesive, or an acrylic thermosetting adhesive. The adhesive layer 130 is thermosetting when the semiconductor chip 110 and the circuit board 100 are joined, thereby adhering the semiconductor chip 110 and the circuit board 100.

[0027] In the processing target 1 having the above configuration, a large number of semiconductor chips 110 are arranged in a two-dimensional array on the circuit board 100, so mounting defects (such as poor adhesion or poor conductivity) may occur between some of the semiconductor chips 110 and the circuit board 100. Also, some of the semiconductor chips 110 among the large number of semiconductor chips 110 bonded to the circuit board 100 may be defective. In such cases, the defective semiconductor chips 110 are removed from the circuit board 100 and re-bonded to the circuit board 100. However, since each of the semiconductor chips 110 is bonded to the circuit board 100 by an adhesive layer 130, it is important to selectively remove the adhesive layer 130 that bonds the semiconductor chip 110 in order to remove the defective semiconductor chip 110 from the circuit board 100.

[0028] The semiconductor chip removal method according to this embodiment involves selectively removing the adhesive layer 130 that adheres a specified semiconductor chip 110 from among a plurality of semiconductor chips 110 bonded to the circuit board 100 using atmospheric pressure plasma. The semiconductor chip removal method according to this embodiment will be described in more detail below.

[0029] <2. Atmospheric pressure plasma treatment> Next, we will describe an atmospheric pressure plasma treatment that selectively removes the adhesive layer 130 that adheres to the semiconductor chip 110, as described in the method for removing the semiconductor chip 110 according to this embodiment. Figure 2 is a longitudinal cross-sectional view illustrating the atmospheric pressure plasma treatment of this embodiment. Figure 3 is a longitudinal cross-sectional view showing the state of the object to be treated 1 after atmospheric pressure plasma treatment.

[0030] As shown in Figure 2, in atmospheric pressure plasma processing, first, a mask 210 with an opening H corresponding to the shape and size of the semiconductor chip 110 is placed on the designated semiconductor chip 110 to be processed 1. A plasma nozzle 220 that generates atmospheric pressure plasma P is placed approximately above the center of the opening H of the mask 210.

[0031] Next, atmospheric pressure plasma P is irradiated onto the object to be processed 1 from the plasma nozzle 220 through the opening H of the mask 210, thereby selectively removing only the adhesive layer 130 that bonds the semiconductor chip 110 to the circuit board 100, as shown in Figure 3. The plasma nozzle 220, which irradiates the object to be processed 1 with atmospheric pressure plasma P through the opening H of the mask 210, may be positioned, for example, at a distance of 10 mm or less from the object to be processed 1.

[0032] Once the adhesive layer 130 is removed, the specified semiconductor chip 110 is no longer bonded to the circuit board 100, and can therefore be removed from the circuit board 100. If the removed semiconductor chip 110 has no functional problems, the adhesive layer 130 (before heat curing) is reapplied to the circuit board 100, and the chip is then re-bonded to the circuit board 100. This allows the processing target 1 to resolve the mounting error by removing and re-bonding the faulty semiconductor chip 110. On the other hand, if the removed semiconductor chip 110 is faulty, the adhesive layer 130 (before heat curing) is reapplied to the circuit board 100, and a new semiconductor chip 110 is bonded to the circuit board 100. This allows the processing target 1 to resolve the semiconductor chip error by removing the faulty semiconductor chip 110 and bonding a new semiconductor chip 110.

[0033] The plasma nozzle 220 is a plasma irradiation device capable of stably generating plasma under atmospheric pressure and irradiating a localized area with the generated atmospheric pressure plasma P. The plasma nozzle 220 may also be a gas irradiation type plasma irradiation device that radicalizes the process gas by passing it through a discharge space and irradiates the target object 1 with the radicalized process gas as atmospheric pressure plasma P. As another example, the plasma nozzle 220 may be a discharge treatment type plasma irradiation device in which the target object 1 is placed inside a discharge space, and a high voltage is applied inside the discharge space while supplying process gas, thereby causing the radicalized process gas to act on the target object 1 as atmospheric pressure plasma P. The discharge method of the plasma irradiation device is not particularly limited.

[0034] The process gas may be an easily available gas such as oxygen, hydrogen, nitrogen, air (dry air), or argon. The process gas, radicalized by the plasma nozzle 220, is irradiated onto the object to be processed 1 as atmospheric pressure plasma P, thereby ashing and removing the adhesive layer 130 that bonds the semiconductor chip 110 to the circuit board 100.

[0035] Unlike vacuum plasma, atmospheric pressure plasma P has relatively low power, making it possible to selectively remove only the adhesive layer 130 without damaging the semiconductor chip 110, chip electrode 111, bump electrode 140, and circuit wiring 105, which are made of materials other than organic resin. Furthermore, by making the stopper 120, which is made of organic resin, different in material or crosslinking structure from the adhesive layer 130, it is possible to ensure a selectivity ratio between the adhesive layer 130 and the atmospheric pressure plasma P. Therefore, atmospheric pressure plasma P can selectively remove only the adhesive layer 130 that adheres to the semiconductor chip 110 corresponding to the opening H of the mask 210.

[0036] Furthermore, the circuit board 100 of the object to be processed 1 is connected to ground so that it does not acquire an electrical potential due to irradiation with atmospheric pressure plasma P. This prevents the object to be processed 1 from acquiring an electrical potential, and the plasma nozzle 220 can appropriately irradiate the object to be processed 1 with atmospheric pressure plasma P even when the irradiation with atmospheric pressure plasma P is prolonged.

[0037] The mask 210 is a hard mask that covers the entire object to be processed 1 and has an opening H corresponding to the semiconductor chip 110. The mask 210 may be, for example, a glass plate or a metal plate with the opening H. If the mask 210 is a metal plate, it is desirable that the mask 210 be connected to earth so that it does not have any potential, similar to the circuit board 100.

[0038] The aperture H is provided in a shape and size corresponding to one semiconductor chip 110. For example, if one semiconductor chip 110 has a rectangular shape with sides of 20 μm to 30 μm, the shape of the aperture H may be a rectangular shape with sides of 50 μm to 100 μm. By ensuring that only one semiconductor chip 110 is contained within the region communicating with the plasma nozzle 220 through the aperture H, atmospheric pressure plasma P can be irradiated only onto the adhesive layer 130 that adheres the specified semiconductor chip 110.

[0039] The plasma nozzle 220 and mask 210 and the processing target 1 are provided so as to be able to move relative to each other in a plane parallel to the plane on which the semiconductor chips 110 are arranged in two dimensions. Specifically, if the plane on which the semiconductor chips 110 are arranged in two dimensions is the XY plane, the plasma nozzle 220 and mask 210 and the processing target 1 are provided so as to be able to move relative to each other in the mutually orthogonal X axis and Y axis. The plasma nozzle 220 and mask 210 and the processing target 1 may be able to move independently of each other, the plasma nozzle 220 and mask 210 may be fixed and only the processing target 1 may be able to move, or the processing target 1 may be fixed and only the plasma nozzle 220 and mask 210 may be able to move relative to each other. The plasma nozzle 220 and mask 210 and the processing target 1 may be provided so as to be able to move relative to each other by using an XY stage as an alignment mechanism.

[0040] According to this, the plasma nozzle 220 and mask 210 can irradiate a semiconductor chip 110 bonded at any position with atmospheric pressure plasma P by aligning the opening H at any position on the main surface of the circuit board 100. Therefore, the plasma nozzle 220 can pinpoint and remove the adhesive layer 130 that bonds the defective semiconductor chip 110, making the defective semiconductor chip 110 removable.

[0041] The semiconductor chip removal method according to this embodiment, as described above, simplifies the process of removing the defective semiconductor chip 110 from the circuit board 100, thereby shortening the repair time for the defective semiconductor chip 110. Therefore, the semiconductor chip removal method according to this embodiment can further reduce the manufacturing cost of the microLED display.

[0042] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention.

[0043] Furthermore, a plasma irradiation apparatus capable of performing the semiconductor chip 110 removal method according to this embodiment may also be provided. Specifically, the plasma irradiation apparatus includes an alignment mechanism that moves the relative positions of the circuit board 100 and the mask 210 and plasma nozzle 220, and a control unit that aligns the plasma nozzle 220 so that atmospheric pressure plasma P is irradiated onto the designated semiconductor chip 110 through the aperture H, after aligning the positions of the designated semiconductor chip 110 with the aperture H of the mask 210 and the plasma nozzle 220. The alignment mechanism may be, for example, various stage mechanisms such as an XY stage, and the control unit may be a processing unit such as a CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit). [Explanation of Symbols]

[0044] 1...Item to be processed, 100...Circuit board, 105...Circuit wiring, 110...Semiconductor chip, 111...Chip electrode, 120...Stopper, 130...Adhesive layer, 140...Bump electrode, 141...Resin core, 143...Metal coating, 210...Mask, 220...Plasma nozzle, H...Aperture, P...Atmospheric pressure plasma

Claims

1. The steps include: placing a mask, which has an opening corresponding to one of the semiconductor chips, on a circuit board on which multiple semiconductor chips are fixed with adhesive and arranged in a two-dimensional manner, at a position corresponding to a specified semiconductor chip; The steps include: irradiating the designated semiconductor chip with atmospheric pressure plasma through the opening to remove the adhesive that fixes the designated semiconductor chip; A method for removing semiconductor chips, including [specific details omitted].

2. The method for removing a semiconductor chip according to claim 1, wherein the semiconductor chip is an LED chip or an IC chip that controls the light emission of the LED chip.

3. The method for removing a semiconductor chip according to claim 2, wherein the semiconductor chip is electrically connected to wiring on the circuit board via bump electrodes.

4. The method for removing a semiconductor chip according to any one of claims 1 to 3, wherein the atmospheric pressure plasma is generated using oxygen, argon, air, or nitrogen.

5. The method for removing a semiconductor chip according to any one of claims 1 to 3, wherein the atmospheric pressure plasma is emitted from a plasma nozzle.

6. The method for removing a semiconductor chip according to claim 5, wherein the plasma nozzle, the mask, and the circuit board are provided so as to be able to move relative to each other in a plane parallel to the main surface of the circuit board on which the semiconductor chips are arranged.

7. The method for removing a semiconductor chip according to any one of claims 1 to 3, wherein the circuit board is connected to earth.

8. A positioning mechanism that moves relative to the position of a circuit board on which multiple semiconductor chips are fixed with adhesive and arranged in a two-dimensional manner, the position of a mask having an opening corresponding to one of the semiconductor chips, and the position of a plasma nozzle that irradiates atmospheric pressure plasma, on a plane parallel to the main surface of the circuit board on which the semiconductor chips are arranged, A control unit aligns the circuit board, the mask, and the plasma nozzle so that the positions of the aperture and the plasma nozzle correspond to the position of the specified semiconductor chip, and controls the plasma nozzle to irradiate the specified semiconductor chip with atmospheric pressure plasma through the aperture in order to remove the adhesive that fixes the specified semiconductor chip. A plasma irradiation device equipped with the following features.

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