Method of manufacturing an UV light emitting semiconductor device

Abstract

The present disclosure relates to a method for manufacturing an ultraviolet light-emitting semiconductor device comprising: a semiconductor light-emitting chip that emits ultraviolet light; an encapsulating material that protects the semiconductor light-emitting chip and has light transparency; and an external substrate having a base on which the semiconductor light-emitting chip and the encapsulating material are placed, the base having an upper surface and a lower surface facing the upper surface, wherein the method comprises the steps of: forming a first upper conductive layer and a second upper conductive layer electrically connected to the semiconductor light-emitting chip on the upper surface of the base, and a blocking layer having a concave portion on its side that functions as a stopper in the formation of the encapsulating material; coupling the semiconductor light-emitting chip to the external substrate, wherein the semiconductor light-emitting chip is electrically connected to the first upper conductive layer and the second upper conductive layer; and forming an encapsulating material to surround the semiconductor light-emitting chip, wherein the encapsulating material is formed in a lens shape over the first upper conductive layer, the second upper conductive layer, and the blocking layer, wherein the blocking layer functions as a stopper and is fixed by being embedded in the concave portion of the blocking layer.

Description

Technology Field

[0001] The present disclosure relates to a method for manufacturing an ultraviolet light-emitting semiconductor device in general, and in particular to a method for manufacturing an ultraviolet light-emitting semiconductor device in which the bonding strength of the encapsulation material to an external substrate is improved. Background Technology

[0002] This section provides background information related to the present disclosure, which is not necessarily prior art.

[0003] FIGS. 1 and 2 are drawings illustrating an example of an ultraviolet light-emitting semiconductor device as disclosed in US Patent Publication No. US11,824,148, wherein the ultraviolet light-emitting semiconductor device (1) comprises a semiconductor light-emitting chip (10), an encapsulating material (12), and an external substrate (14). The semiconductor light-emitting chip (10; e.g., flip chip, vertical chip, lateral chip) comprises a plurality of semiconductor layers including an active layer (101) that generates light by the recombination of electrons and holes, and electrodes (102) electrically connected to the plurality of semiconductor layers. The encapsulating material (12) is formed on the external substrate (14) to encapsulate the semiconductor light-emitting device chip (10), and may be made of a transparent resin (e.g., transparent thermoplastic resin) having a transmittance to light generated from the active layer (101) (e.g., ultraviolet light with a peak wavelength of 100 nm to 400 nm). The external substrate (14) may consist of a base (141), conductive layers (142, 145), a barrier layer (143), and a reflective layer (144). The base (141) may be made of a material that is electrically insulating and has excellent thermal conductivity (e.g., a high thermal conductivity polymer material, a ceramic material, an AlN ceramic). The conductive layers (142, 145) are electrically connected to the electrodes (102) of the semiconductor light-emitting chip (10) and may be formed by including at least one metal such as Ni, Pt, Pd, Rh, W, Ti, Al, Ag, Au, or Cu. The barrier layer (143) acts as a boundary edge, that is, a dam utilizing surface tension, to prevent the encapsulating material (12) from being formed beyond the barrier layer (143) when the encapsulating material (12) is formed. By providing a reflective layer (144) as needed, light emitted from a semiconductor light-emitting chip (10) directed toward an external substrate (14) can be reflected and directed toward the upper side of the external substrate (14), thereby improving light efficiency, and the upper surface can be made of a material with excellent reflectivity (e.g., a metal such as Al, Ag, Au, etc.). Of course, by composing the conductive layer (142), the blocking layer (143), and the reflective layer (144) of the same material, they can be formed in a single process.

[0004] The ultraviolet light-emitting semiconductor device (1) shown in FIGS. 1 and 2 is according to the inventors of the present invention and has the advantage of solving the problem of a conventional ultraviolet light-emitting semiconductor device as shown in FIG. 3 (where a window or lens (L) is formed at a distance from the semiconductor light-emitting chip (10), causing light loss of about 5% to 20% in an air-filled space (A)). However, even setting aside the difficulty of forming a sealing material (12) made of a resin that is transparent to ultraviolet light by directly attaching it to an external substrate (14), it has the problem that the sealing material (12) can be separated from the external substrate (14) after manufacturing. The problem to be solved

[0005] This is described at the end of 'Specific details for implementing the invention'. means of solving the problem

[0006] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

[0007] According to one aspect of the present disclosure, a method for manufacturing an ultraviolet-emitting semiconductor device comprising: a semiconductor light-emitting chip that emits ultraviolet light; a sealing material that protects the semiconductor light-emitting chip and has light transparency; and an external substrate having a base on which the semiconductor light-emitting chip and the sealing material are placed, the base having an upper surface and a lower surface facing the upper surface, the method comprising: forming on the upper surface of the base a first upper conductive layer and a second upper conductive layer electrically connected to the semiconductor light-emitting chip, and a blocking layer having a concave portion on its side that functions as a stopper in the formation of the sealing material; and coupling the semiconductor light-emitting chip to the external substrate, wherein the semiconductor light-emitting chip is electrically connected to the first upper conductive layer and the second upper conductive layer. A method for manufacturing an ultraviolet light-emitting semiconductor device is provided, comprising the step of forming an encapsulation material to surround a semiconductor light-emitting chip; wherein the encapsulation material is formed in a lens shape over a first upper conductive layer, a second upper conductive layer, and a blocking layer, wherein the blocking layer functions as a stopper and is fixed by being embedded in a concave portion of the blocking layer. Effects of the invention

[0008] This is described at the end of 'Specific details for implementing the invention'. Brief explanation of the drawing

[0009] FIGS. 1 and 2 are drawings showing an example of an ultraviolet light-emitting semiconductor device as disclosed in U.S. Patent Publication No. US11,824,148. FIG. 3 is a drawing showing another example of a conventional ultraviolet light-emitting semiconductor device. FIG. 4 is a drawing showing an example of an ultraviolet light-emitting semiconductor device according to the present disclosure. FIGS. 5 to 9 are drawings illustrating an example of a method for manufacturing an ultraviolet light-emitting semiconductor device according to the present disclosure. Specific details for implementing the invention

[0010] The present disclosure will now be described in detail with reference to the accompanying drawings.

[0011] FIG. 4 is a drawing showing an example of an ultraviolet light-emitting semiconductor device according to the present disclosure, wherein the ultraviolet light-emitting semiconductor device comprises a semiconductor light-emitting chip (10), an encapsulating material (12), and an external substrate (14), similar to the device shown in FIG. 1 and FIG. 2.

[0012] A semiconductor light-emitting chip (10) emits ultraviolet light, and ultraviolet light refers to light having an emission peak wavelength of 400 nm or less, and is divided into UV-A, UV-B, and UV-C (300 nm or less, particularly 200 nm to 280 nm) depending on the wavelength, and the ultraviolet light-emitting semiconductor device according to the present disclosure is particularly suitable for UV-B and UV-C. The semiconductor light-emitting chip (10) may be a lateral chip, a vertical chip, or a flip chip, but in the case of a lateral chip and a vertical chip, one or two wire bondings are required, and in the presented example, a flip chip that does not use wire bonding is exemplified, and the semiconductor light-emitting chip (10) has two electrodes (10a, 10b) facing an external substrate (14). Examples of semiconductor light-emitting chips (10) are disclosed in U.S. Patent Publication No. US11,600,755, etc.

[0013] The encapsulating material (12) is formed on an external substrate (14) to surround and come into contact with the semiconductor light-emitting chip (10), and protects the semiconductor light-emitting chip (10) from physical impact, gas and moisture ingress, while also functioning as a lens. The encapsulation material (12), that is, the encapsulation material (12) used in the semiconductor light-emitting chip (10) that emits ultraviolet light, is distinguished from the encapsulation material used in the semiconductor light-emitting chip that emits visible light (e.g., blue, green) (the encapsulation material for visible light becomes discolored when continuously exposed to ultraviolet light, and thus its transmittance to ultraviolet light is significantly reduced and cannot be used). Therefore, in the case of a general ultraviolet light-emitting device, it takes the form shown in FIG. 3 (using glass or quartz as a window or lens (L) at a distance from the semiconductor light-emitting chip (10)), but in the case of the ultraviolet light-emitting device shown in FIG. 1 and FIG. 2, a method is presented to manufacture an ultraviolet light-emitting device by using a transparent resin (e.g., Cytop series, perfluorinated polymer, Cytop-S) with a transmittance to ultraviolet light of 80% or more as the encapsulation material (12).

[0014] The external substrate includes a base (141) having an upper surface (141a) and a lower surface (141b), conductive portions (142a, 142b, 145a, 145b, 146a, 146b), a protective layer (143), and a reflective layer (144). Compared to the element shown in FIGS. 1 and 2, it differs in that the protective layer (143) further includes a concave portion (143a) for secure fixation of the encapsulating material (12) and for preventing the ingress of gas and moisture. Preferably, the conductive portions (142a, 142b, 145a, 145b, 146a, 146b) are formed on the upper surface (141a) of the base (141) and include a first upper conductive layer (142a) and a second upper conductive layer (142b) that are electrically and physically coupled to the first electrode (10a) and the second electrode (10b), respectively; a first lower conductive layer (145a) and a second lower conductive layer (145b) that are electrically connected to the first upper conductive layer (142a) and the second upper conductive layer (142b), respectively, formed on the lower surface (141b) of the base (141); and a first connecting portion (146a) that is formed penetrating the base (141) and connects the first upper conductive layer (142a) and the first lower conductive layer (145a), and the second upper conductive layer (142b) and the second lower It includes a second connecting portion (146b) that connects the conductive layer (145b). The protective layer (143) prevents the sealing material (12) from moving beyond the protective layer (143) toward the reflective layer (144) by utilizing surface tension during the formation process of the sealing material (12), thereby allowing the sealing material (12) to have a designed lens shape. The concave portion (143a) formed in the protective layer (143) and functioning as an anchor securely fixes the sealing material (143) to the external substrate (14) to prevent separation and further prevents moisture, etc. from penetrating into the device. For example, as shown in FIG. 2, the protective layer (143) can be formed in a ring shape outside of the conductive layers (142a, 142b) at a distance.It is preferable that a reflective layer (144) be provided to prevent light from being absorbed by the upper surface (141a) of the base (144) where the encapsulating material (12) is not formed. The base (141) may be made of, for example, a ceramic substrate (Al2O3, AlN, glass ceramic, etc.), a glass substrate (soda lime glass, quartz glass, etc.), or a semiconductor substrate (silicon substrate, sapphire substrate).

[0015] FIGS. 5 to 9 are drawings illustrating an example of a method for manufacturing an ultraviolet light-emitting semiconductor device according to the present disclosure. First, as shown in FIG. 5, a base (141) is prepared having a first connecting portion (1461), a second connecting portion (146b), a first lower conductive layer (145a), and a second lower conductive layer (145b) formed thereon. The first connecting portion (1461), the second connecting portion (146b), the first lower conductive layer (145a), and the second lower conductive layer (145b) do not necessarily have to be formed first. A method for manufacturing such an external substrate (14) is disclosed in U.S. Patent Publication No. US11,552,213, etc.

[0016] Next, as shown in FIG. 6, a seed metal layer (150) is formed on the upper surface (141a) of the base (141). For example, Cu is deposited on the front surface through plating.

[0017] Next, as illustrated in FIG. 7, a mask (M) is formed on a seed metal layer (150), and after opening the areas corresponding to the conductive portions (142a, 142b; first and second upper conductive layers), the anti-corrosion layer (143), and the reflective layer (144) through a photolithography process, the conductive portions (142a, 142b), the anti-corrosion layer (143), and the reflective layer (144) are formed. It is also possible to deposit a material to constitute the conductive portions (142a, 142b), the anti-corrosion layer (143), and the reflective layer (144) over the entire upper surface (141a), and to form the conductive portions (142a, 142b), the anti-corrosion layer (143), and the reflective layer (144) through a photolithography process. Of course, each of these can be formed sequentially through individual processes and with a material optimized for each function. In the example presented, selective etching is used as one method to form a recess (143a) in at least the protection layer (143), and for this purpose, the protection layer (143) is formed in multiple layers. For example, the protection layer (143) can be composed of a first layer (151) where etching mainly takes place and a second layer (153) that acts as a stopper or dam for the encapsulating material (12). Specifically, a first layer (151) made of Cu can be formed through plating, and a second layer (153) made of Au can be formed thereon to prevent oxidation, while having high reflectivity and providing surface tension for the encapsulating material (12). Preferably, a third layer (152) made of a barrier metal such as Ni or Ti can be provided to prevent diffusion between the first layer (151) and the second layer (153). In the example presented, by configuring the first layer (151) with the same material (e.g., Cu) as the seed metal layer (150), the seed metal layer (150) is removed together during the process of forming the concave portion (143a) through selective etching, thereby providing the advantage of electrical separation between the conductive portion (142a, 142b), the blocking layer (143), and the reflective layer (144).Of course, if the conductive portion (142a, 142b), the protective layer (143), and the reflective layer (144) can be formed on the base (141) without the help of the seed metal layer (150), the seed metal layer (150) may be omitted.

[0018] Next, the mask (M) is removed as shown in Fig. 8.

[0019] Next, as illustrated in FIG. 9, a recess (143a) is formed. In the presented example, a recess (143a) is formed on the side or lower side of the protection layer (143) through selective etching of the first layer (151). Since the conductive portion (142a, 142b), the protection layer (143), and the reflective layer (144) are formed in a single process, a recess (143a) is formed in the conductive portion (142a, 142b) and the reflective layer (144) as well, and as described above, the seed metal layer (150) is removed together during the etching process to expose the upper surface (141a), and an electrical short circuit is formed between the conductive portion (142a, 142b), the protection layer (143), and the reflective layer (144). Depending on the conditions of selective etching and the materials forming the first layer (151), second layer (153), and third layer (152), the concave portion (143a) may have a shape in which etching occurs only on the first layer (151) as shown in the illustration (the first layer (151) is a narrow rectangle with a width based on the cross-section, and the second layer (153) and third layer (152) are wide rectangles; the difference in width is about 10 to 40 μm), or the first layer (151), second layer (153), and third layer (152) may have an overall inverted trapezoidal shape, or the etching may proceed further from the inverted trapezoidal shape so that the side surface is concave inward, and there are no special restrictions on the shape as long as the encapsulating material (12) can be fixed. After forming the first layer (151), a second layer (152) and a third layer (153) of greater width can be deposited to form a concave portion (143a) in the conductive layer (143). For example, when the first layer (151; e.g., thickness of 5 to 50 μm) is Cu, the second layer (153; thickness of 10 μm or less) is Au, and the third layer (152; thickness of 5 μm or less) is Ni, the concave portion (143a) can be formed by etching within 5 minutes at a temperature of 70°C or less using a dilute sulfuric acid solution. The thickness of the seed metal layer (150) can be 1 μm or less, and the blocking layer (143) can have a total thickness of 5 to 70 μm.For example, when the conductive portion (142a, 142b) is entirely circular, the outer diameter may be 1 to 3 mm, and when the protective layer (143) is annular, the inner diameter may be 1.4 mm to 4 mm, and when the reflective layer (144) is square with a circular opening, the diameter of the opening may be 1.6 to 5 mm. Each of the conductive portion (142a, 142b), the protective layer (143), and the reflective layer (144) may be formed with a spacing of 100 μm or more, and the protective layer (143) may have a width of 50 to 300 μm.

[0020] Finally, as illustrated in FIG. 4, the first electrode (10a) and the second electrode (10b) of the semiconductor light-emitting chip (10) are bonded to the first upper conductive layer (142a) and the second upper conductive layer (142a), respectively, so that the semiconductor light-emitting chip (10) is attached to an external substrate (14), and then the encapsulating material (12) is formed so that it is recessed into the concave portion (143a) and securely fixed to the prevention layer (143). In the case of a lateral chip and a vertical chip, wire bonding is additionally required. Various methods disclosed in U.S. Patent Publication No. US11,824,148 may be used for the method of forming the encapsulating material (12).

[0021] Various embodiments of the present disclosure will be described below.

[0022] (1) A method for manufacturing an ultraviolet light-emitting semiconductor device comprising: a semiconductor light-emitting chip that emits ultraviolet light; a sealing material that protects the semiconductor light-emitting chip and has light transparency; and an external substrate having a base on which the semiconductor light-emitting chip and the sealing material are placed, the base having an upper surface and a lower surface facing the upper surface, wherein the method comprises the steps of: forming a first upper conductive layer and a second upper conductive layer electrically connected to the semiconductor light-emitting chip on the upper surface of the base, and a blocking layer that functions as a stopper in the formation of the sealing material and has a concave portion on its side; joining the semiconductor light-emitting chip to the external substrate; joining such that the semiconductor light-emitting chip is electrically connected to the first upper conductive layer and the second upper conductive layer; and forming a sealing material to surround the semiconductor light-emitting chip, wherein the sealing material is formed in a lens shape over the first upper conductive layer, the second upper conductive layer and the blocking layer, and the blocking layer functions as a stopper and is fixed by being embedded in the concave portion of the blocking layer.

[0023] (2) A method for manufacturing an ultraviolet light-emitting semiconductor device, wherein, in the step of forming a first upper conductive layer, a second upper conductive layer, and a barrier layer, a concave portion is formed on each side of the first upper conductive layer and the second upper conductive layer.

[0024] (3) A method for manufacturing an ultraviolet light-emitting semiconductor device, wherein the conductive layer comprises a first layer and a second layer formed on the first layer, and a concave portion is formed through selective etching of the first layer.

[0025] (4) A method for manufacturing an ultraviolet light-emitting semiconductor device, wherein a third layer made of a barrier metal that prevents diffusion between the first layer and the second layer is provided between the first layer and the second layer.

[0026] (5) A step of forming a seed metal layer on the upper surface of the base prior to forming the first upper conductive layer, the second upper conductive layer, and the blocking layer; further comprising a method for manufacturing an ultraviolet light-emitting semiconductor device.

[0027] (6) A method for manufacturing an ultraviolet light-emitting semiconductor device in which, during the process of forming a concave portion, a seed metal layer is removed so that the first upper conductive layer, the second upper conductive layer, and the prevention layer are electrically short-circuited to each other.

[0028] (7) A method for manufacturing an ultraviolet light-emitting semiconductor device in which a reflective layer is formed on the upper surface of a base that is not covered by a sealing material and is electrically short-circuited with a protective layer, and a concave portion is formed on the side of the reflective layer.

[0029] According to the ultraviolet light-emitting semiconductor device of the present disclosure, the bonding strength of the encapsulation material to the external substrate can be improved. Explanation of the symbols

[0030] Semiconductor light-emitting chip (10), encapsulating material (12), external substrate (14), base (141), conductive portion (142a, 142b, 145a, 145b, 146a, 146b), anti-corrosion layer (143), reflective layer (144)

Claims

Claim 1 A method for manufacturing an ultraviolet light-emitting semiconductor device comprising: a semiconductor light-emitting chip that emits ultraviolet light; an encapsulating material that protects the semiconductor light-emitting chip and has light transparency; and an external substrate having a base on which the semiconductor light-emitting chip and the encapsulating material are placed, the base having an upper surface and a lower surface facing the upper surface, the method comprising the steps of: forming on the upper surface of the base a first upper conductive layer and a second upper conductive layer electrically connected to the semiconductor light-emitting chip, and a blocking layer having a concave portion on its side that functions as a stopper in the formation of the encapsulating material; and coupling the semiconductor light-emitting chip to the external substrate, wherein the semiconductor light-emitting chip is electrically connected to the first upper conductive layer and the second upper conductive layer. A method for manufacturing an ultraviolet light-emitting semiconductor device, comprising: a step of forming an encapsulation material to surround a semiconductor light-emitting chip, wherein the encapsulation material is formed in a lens shape over a first upper conductive layer, a second upper conductive layer, and a blocking layer, wherein the blocking layer functions as a stopper and is fixed by being embedded in a concave portion of the blocking layer; wherein the blocking layer comprises a first layer and a second layer formed on the first layer, and a concave portion is formed through selective etching of the first layer. Claim 2 A method for manufacturing an ultraviolet light-emitting semiconductor device according to claim 1, wherein the first upper conductive layer and the second upper conductive layer each comprise a first layer and a second layer, and a concave portion is formed on each side of the first upper conductive layer and the second upper conductive layer through selective etching of the first layer. Claim 3 delete Claim 4 A method for manufacturing an ultraviolet light-emitting semiconductor device according to claim 1 or claim 2, wherein a third layer made of a barrier metal that prevents diffusion between the first layer and the second layer is provided between the first layer and the second layer. Claim 5 A method for manufacturing an ultraviolet light-emitting semiconductor device, further comprising the step of forming a seed metal layer on the upper surface of a base prior to forming a first upper conductive layer, a second upper conductive layer, and a blocking layer, in accordance with claim 1 or claim 2. Claim 6 A method for manufacturing an ultraviolet light-emitting semiconductor device according to claim 5, wherein, in the process of forming a concave portion, a seed metal layer is removed such that the first upper conductive layer, the second upper conductive layer, and the prevention layer are electrically short-circuited to each other. Claim 7 A method for manufacturing an ultraviolet light-emitting semiconductor device according to claim 1 or claim 2, wherein a reflective layer is formed on the upper surface of a base not covered by a sealing material by electrically short-circuiting with a protection layer, and a concave portion is formed on the side of the reflective layer.

Images