JP2017168714A - Method of manufacturing light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for suppressing discoloration of an electrode of a semiconductor element.SOLUTION: The method of manufacturing semiconductor device includes steps of: preparing a semiconductor element having an electrode on its upper surface; covering the entire surface of the electrode with silicon oxide; performing plasma treatment of the silicon oxide with a mixed gas containing argon and fluorocarbon to remove the silicon oxide to expose the electrode; and bonding a metal member on the exposed electrode.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for manufacturing a light emitting device.

  2. Description of the Related Art LEDs (Light Emitting Diodes) using semiconductor light emitting elements (hereinafter referred to as light emitting elements) are known. The light emitting element includes a semiconductor layer and an electrode, and the electrode of the light emitting element and the wiring of the substrate are electrically connected via a conductive member such as a wire. It is known that the electrode of the light emitting element or the wiring of the substrate is subjected to plasma treatment on the surface thereof (for example, Patent Document 1).

JP 2014-17816 A

  Patent Document 1 discloses that contaminants are removed by plasma of a mixed gas containing a fluorocarbon. However, depending on the plasma conditions, the electrode may change color.

In order to solve the above-described problems, an embodiment of the present invention includes the following configuration.
A step of preparing a semiconductor element having an electrode on its upper surface, a step of covering the entire surface of the electrode with silicon oxide, a silicon oxide is plasma-treated using a mixed gas containing argon and fluorocarbon, A method of manufacturing a semiconductor device, comprising: removing the electrode by removing; and bonding a metal member on the exposed electrode.

  As described above, discoloration of the electrode can be suppressed.

FIG. 1 is a schematic view of a method for manufacturing a semiconductor device according to an embodiment. FIG. 2 is a schematic view of the method for manufacturing the semiconductor device according to the embodiment. FIG. 3 is a schematic view of the method for manufacturing the semiconductor device according to the embodiment. FIG. 4 is a schematic view of the method for manufacturing the semiconductor device according to the embodiment. FIG. 5 is a schematic view of the method for manufacturing the semiconductor device according to the embodiment.

  A mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below illustrates the manufacturing method of the light-emitting device for materializing the technical idea of this invention, and this invention does not limit the manufacturing method of a light-emitting device below.

  Further, the present specification by no means specifies the member shown in the claims as the member of the embodiment. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention only to that extent unless otherwise specified. It should be noted that the size and positional relationship of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate.

(Process for preparing semiconductor elements)
A semiconductor element having an electrode on its upper surface is prepared. Examples of semiconductor elements include semiconductor light emitting elements (LED elements, laser elements), light receiving elements, protective elements, transistors, and the like. The semiconductor element includes a semiconductor layer and a p-electrode and an n-electrode that form a pair of electrodes.

As a semiconductor layer of the semiconductor light emitting device, for example, as a light emitting device for ultraviolet light, blue light, and green light, ZnSe or nitride semiconductor (In _X Al _Y Ga _1- XYN, 0 ≦ X, 0 ≦ Those using Y, X + Y ≦ 1) can be used. As the red light emitting element, GaAs, InP, or the like can be used. Examples of the semiconductor layer of the light receiving element include GaAs and InGaAs. Examples of the protective element include a Zener diode, and examples of the semiconductor layer of the Zener diode include Si and Ge.

  A pair of electrodes of the semiconductor element are arranged on the same surface side of the semiconductor layer, or at least a pair of electrodes on opposite surfaces. The pair of electrodes may be any ohmic connection with the semiconductor layer in which the electrodes are provided so that the current-voltage characteristics are linear or substantially linear. Each electrode may have a single layer structure or a laminated structure. In addition, the electrodes are a whole surface electrode that is in ohmic contact with the semiconductor layer (an electrode that covers substantially the entire upper or lower surface of the semiconductor layer), and a pad electrode that is formed on the ohmic electrode (an electrode to which a wire is connected). For example, the electrode can be divided into a plurality of functions. In the case of such a structure, it is only necessary that contaminants on the electrode joined to the metal member can be removed.

  As the electrode of the semiconductor element, a material known in this field can be used. For example, Au, Ag, Cu, etc. are mentioned.

(Process for coating the entire surface of the electrode with silicon oxide)
The semiconductor element is placed on the substrate with the upper surface having the electrodes facing upward. A plurality of semiconductor elements can be mounted on one substrate.

  As the substrate on which the semiconductor element is mounted, a substrate that forms part of the semiconductor device can be used. For example, a substrate constituting an electrode and a base of a semiconductor device can be used. Examples of such a substrate include a resin package having leads, a ceramic substrate having wiring, a glass epoxy substrate having wiring, a flexible substrate having wiring, and the like.

  Further, the substrate on which the semiconductor element is mounted can be a substrate that is not included in the structure of the semiconductor device by being removed in a later process. For example, a substrate used only in a work process, such as a wafer sheet and a transfer substrate, can be used.

  One or a plurality of semiconductor elements can be mounted on one substrate, and the number and arrangement of the semiconductor elements, and the composition can be selected as appropriate.

  Examples of the step of covering the entire surface of the electrode of the semiconductor element placed on the substrate with silicon oxide as described above include a) plasma irradiation, b) sputtering, and c) vapor deposition.

a) Formation of silicon oxide by plasma irradiation A process of forming silicon oxide will be described with reference to FIGS. 1 (a) to 2 (b). Here, a process of forming silicon oxide on the electrode 24 of the semiconductor element 20 that is finally placed on the substrate 10 constituting a part of the semiconductor device will be described.

  As shown in FIG. 1A, a substrate 10 on which a bonding member 30 is disposed and a semiconductor element 20 are prepared. The bonding member 30 is preferably provided with an area larger than the bottom area of the semiconductor element 20. For example, the bottom area of the semiconductor element 20 is preferably about 0.5 to 2 times. As a method for forming the bonding member 30, a molten bonding member is formed at a target position by dropping, potting, transfer, printing, spraying, or the like. A plurality of semiconductor elements 20 can be mounted on one substrate 10, and two semiconductor elements 20 will be described as an example here. The joining members 30 formed at a plurality of locations are provided so as to be separated from each other.

  A silicone resin member is used as the bonding member 30. In detail, a dimethyl silicone resin, a silicone modified epoxy resin, etc. are mentioned.

  Next, as shown in FIG. 1B, the semiconductor element 20 is placed on the bonding member 30. The semiconductor element includes an electrode 24 on the upper surface of the semiconductor layer 22 and is placed on the substrate 10 so that the upper surface is on the upper side. When the semiconductor element 20 is placed, a part of the bonding member 30 is deformed by pressing from above. Accordingly, the bonding member 30 is provided so as to be in contact with the lower surface of the semiconductor element 20 and a part of the side surface of the semiconductor element 20.

  Next, as shown in FIG. 2A, the substrate 10 is housed and stored in a sealable storage container 40. As storage conditions, for example, the temperature in the storage container is about 23 ° C. to 80 ° C., the pressure in the storage container is 10 Pa to atmospheric pressure, the humidity in the storage container is 10% to 85%, and the storage time in the storage container For 0.5 hour or longer. Further, the inside of the storage container is filled with a general inert gas or the like in addition to air.

  The silicone-based resin (joining member 30) has a silicone resin as a main component and has a property of being cured by heating at a temperature of about 90 ° C. to 180 ° C. Under the storage conditions as described above, in particular, the storage conditions at a temperature lower than the curing temperature of the silicone resin member, such as a temperature of about 23 ° C. to 80 ° C., the silicone resin member will not be completely cured. However, even under such low-temperature storage conditions, a component containing siloxane volatilizes from a silicone resin member containing a volatile component in addition to the main component silicone resin. That is, as shown in FIG. 2A, the silicon-containing volatiles 30 a are generated in the storage container 40 and scattered away from the joining member 30 into the space of the storage container 40.

  The scattered silicon-containing volatile material 30a adheres to another member in the periphery, that is, the surface of the substrate and the semiconductor element. After adhering, it may volatilize again, but it remains adhering and forms a thin film. In this way, as shown in FIG. 2B, the silicon-containing volatile material 30a can be provided so as to cover substantially the entire surface of the electrode 24 of the semiconductor element 20.

  In addition, the storage conditions mentioned above are an example of the storage conditions which can volatilize the component containing silicon from the silicone type resin member used as a joining member. Depending on the size of the storage container, the composition and shape of the electrode of the semiconductor element placed inside, and the amount and arrangement of the silicone resin (distance from the electrode of the semiconductor element), not limited to the above range, It can be stored under suitable conditions.

  After storing under the above-mentioned storage conditions and substantially covering the entire surface of the electrode of the semiconductor element with the silicon-containing volatile material, plasma treatment is performed.

  FIG. 3 shows a schematic diagram of the plasma processing apparatus. The plasma processing apparatus 50 includes a chamber 51 having an upper electrode 52 and a lower electrode 53, an open / close valve 54 for supplying a carrier gas and a plasma gas, a decompression pump 55 for controlling the pressure in the chamber 51, and a high-frequency power source 56. .

  The semiconductor element 20 and the substrate 10 including the electrode 24 to which the silicon-containing volatile material 30a is attached are placed in the chamber 51 together with the substrate 10. Thereafter, a gas containing argon (Ar) is injected into the chamber 51 through the opening / closing valve 54. The pressure in the chamber 51 is set to 8 Pa to 25 Pa, and then a high frequency electric field is generated to generate argon plasma. By irradiating the generated argon plasma onto the surfaces of the semiconductor element 20 and the substrate 10 provided with the electrodes 24, the silicon-containing volatiles 30a are changed into silicon oxides 30b. Thereby, substantially the entire surface of the electrode 24 formed on the upper surface of the semiconductor element 20 can be covered with the silicon oxide 30b as shown in FIG. The obtained silicon oxide 30b has a film thickness of 25 mm or less, for example. By setting it as such a film thickness, it can remove easily with the plasma of the mixed gas containing argon and fluorocarbon of a post process. Depending on the plasma conditions, even a silicon oxide having a film thickness larger than this can be removed.

  As described above, by using a silicone-based resin member, which is a raw material of silicon oxide that covers the electrodes of the semiconductor element, as a bonding member between the semiconductor element and the substrate, storage conditions can be managed without adding new processes. By doing so, a silicon oxide can be formed.

  When using a silicone-based resin member as a bonding member, the silicon oxide is heated in a state in which silicon oxide is adhered to cure the bonding member, and then a silicon oxide removal step described later is performed.

  In addition, as the silicon-based resin member used as a raw material for silicon oxide, a material other than that used as a bonding member may be used. For example, the semiconductor element can be disposed on a substrate which is a part of the semiconductor device and where no semiconductor element is placed. Alternatively, the silicone resin member may be disposed not in the substrate but in a storage container that accommodates the substrate. That is, you may use the silicone type resin member used only as a raw material of the silicon oxide which coat | covers an electrode. In such a case, it is not necessary to consider the bondability between the semiconductor element and the substrate as a characteristic of the silicone-based resin member. Furthermore, since it does not finally remain in the semiconductor device, it is not necessary to consider characteristics required for the semiconductor device such as light resistance and moisture resistance. Therefore, the choice of materials can be increased.

The silicone resin member used as a member other than the bonding member does not require a curing step and may be removed after forming the silicon oxide, or when the bonding member other than the silicone resin member is heated and cured. In addition, there is no particular problem even if heated together.

  When a silicone resin member is not used as a bonding member between a substrate and a semiconductor element, an insulating bonding member such as an epoxy resin member or an acrylic resin member, an Ag paste, a bump, or a eutectic crystal is used as the bonding member. A conductive bonding member can be used. And the process of preparing the semiconductor element joined on the board | substrate using such a joining member can be changed into the process of preparing the above-mentioned semiconductor element.

b) Formation of silicon oxide by sputtering The silicon-containing oxide may be formed by sputtering. In the above-described a), silicon oxide is formed by sputtering instead of the step of storing the substrate and the semiconductor element under specific storage conditions and the subsequent step of irradiating with argon plasma. Sputtering is performed using, for example, a target containing silicon oxide in a vacuum sealable apparatus.

First, the intermediate body is attached to a transfer jig, and the transfer jig is placed together with the transfer jig in a sealed chamber of the sputtering apparatus to obtain a high vacuum state. A SiO ₂ target material is disposed in the sealed chamber. Subsequently, argon gas is introduced into the sealed chamber and plasma discharge is performed, whereby argon ions collide with the target material, and SiO _{2 that} has jumped out of the target material adheres to the light-transmitting member as an intermediate. Thereby, a silicon-containing compound is formed on the surface of the translucent member.

c) Formation of silicon oxide by vapor deposition The silicon-containing oxide may be formed by vapor deposition. In the above a), silicon oxide is formed by vapor deposition instead of the step of storing the substrate and the semiconductor element under specific storage conditions and the subsequent step of irradiating with argon plasma.

First, the intermediate body is attached to a transfer jig, and the transfer jig is placed together with the transfer jig in a hermetic chamber of the vapor deposition apparatus to obtain a high vacuum state. The enclosed chamber is arranged SiO ₂ deposition material, SiO ₂ is deposited on the transparent member evaporates intermediate be a high vacuum state. Thereby, a silicon-containing compound is formed on the surface of the translucent member.

  The step of forming silicon oxide is a step of removing silicon oxide, which will be described later, when a silicon oxide is formed using a wafer sheet or the like as a substrate when a substrate that is a part of a semiconductor device is not used. Before this, it is necessary to place the substrate on a substrate that becomes a part of the semiconductor device. That is, the substrate on which the semiconductor element is placed when forming the silicon oxide and the substrate on which the semiconductor element is placed when removing the silicon oxide are different substrates. Thereby, depending on the conditions for forming the silicon oxide, the silicon oxide can be formed without using a substrate that may be affected in some way in a later step.

  Further, as described above, the siloxane compound that covers the electrode of the semiconductor element may cover the surface of a metal member (for example, a wire or a bump) connected to the electrode of the semiconductor element.

(Process to remove silicon oxide by plasma irradiation)
The semiconductor element 20 including the electrode 24 whose surface is covered with the silicon oxide 30b obtained as described above is disposed in the plasma apparatus together with the substrate 10. A plasma apparatus similar to the plasma apparatus used in the above-described installation can be used. Here, a mixed gas containing argon (Ar) and fluorocarbon (CF ₄ ) is used as the type of plasma gas.

  The mixing ratio of argon and fluorocarbon can be in the range of 10:90 to 90: 100. By irradiating plasma of a mixed gas of argon and fluorocarbon, silicon oxide on the surface of the electrode of the semiconductor element is removed, and the surface of the electrode is exposed. The exposed electrode is a surface that is not discolored and free of contaminants.

  Even when silicon oxide is formed on the surface of the metal member, a metal member having a surface to which contaminants are not attached can be obtained by irradiating the same mixed gas plasma as described above.

The mechanism by which the siloxane compound is removed by irradiating plasma of a mixed gas of argon (Ar) and fluorocarbon (CF ₄ ) is that electrons, Ar ions, and CF radicals are generated by the plasma irradiation, and these are generated in silicon oxide It is disclosed in Patent Document 1 that it is considered that the bond between Si—O is broken and decomposed. In the present embodiment, such a decomposable silicon oxide is intentionally formed for use as a protective film, not a contaminant formed unintentionally in the process.

(Step of joining a metal member on the electrode)
The silicon oxide is removed, and a metal member is bonded onto the electrode whose surface is exposed. FIG. 5 shows an example in which a wire is used as the metal member 60. As the metal member, a bump may be used in addition to the wire.

  After the above-described steps, the semiconductor element is covered with a resin or the like, and the substrate is cut into pieces to obtain a semiconductor device.

  The method for manufacturing a semiconductor device according to an embodiment of the present disclosure can be used for a semiconductor device used for a wide range of applications.

DESCRIPTION OF SYMBOLS 10 ... Board | substrate 20 ... Semiconductor element 22 ... Semiconductor layer 24 ... Electrode 30 ... Joining member (silicone resin member)
30a ... Silicon-containing volatiles 30b ... Silicon oxide 40 ... Storage container 50 ... Plasma processing apparatus 51 ... Chamber 52 ... Upper electrode 53 ... Lower electrode 54 ... Opening / closing valve 55 ... Pressure reducing pump 56 ... High frequency power supply 60 ... Metal member

Claims (3)

Preparing a semiconductor element having an electrode on the upper surface;
Coating the entire surface of the electrode with silicon oxide;
Plasma-treating the silicon oxide using a mixed gas containing argon and fluorocarbon, and removing the silicon oxide to expose the electrode;
Bonding a metal member onto the exposed electrode;
A method for manufacturing a semiconductor device comprising:   The method of manufacturing a semiconductor device according to claim 1, wherein the silicon oxide is formed by irradiating a silicon-containing volatile material obtained by volatilizing a silicone resin member with plasma.   The method of manufacturing a semiconductor device according to claim 2, wherein the semiconductor device includes a substrate on which the semiconductor element is placed, and the silicone resin member is a bonding member that bonds the substrate and the semiconductor element.

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