JP2007318168A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device, which of uniformly forms a parting plane with a flat surface and produces fewer poor conduction electrodes and resin liftings when dividing a substrate of the semiconductor device including gallium. <P>SOLUTION: A method of manufacturing a semiconductor device comprises processes of: forming a groove by radiating a laser beam 6 to make a boundary of each substrate on a substrate 1, on which an n-type semiconductor layer 2 and p-type semiconductor layer 3 are formed using gallium; immersing the substrate 1 into an acid liquid (hydrochloric acid) 7; and taking the substrate 1 out of the hydrochloric acid 7 to divide into each substrate from the boundary where the groove is formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device in which a substrate having a semiconductor layer containing gallium formed on at least one of a semiconductor layer and a substrate is cut with a laser beam.

  In the case of manufacturing a light-emitting element which is an example of a semiconductor device using gallium, it is necessary to form a circuit on a wafer to be a substrate and divide the substrate into columns and rows to form the light-emitting elements.

  FIG. 5 illustrates a method for manufacturing a light-emitting element, which is an example of a semiconductor device using a substrate on which a conventional semiconductor layer containing gallium is formed.

  A substrate 1 is formed of sapphire, and an n-type semiconductor layer 2 and a p-type semiconductor layer 3 made of gallium nitride are formed on the substrate 1 by MOCVD epitaxial growth. A p-type semiconductor layer is formed by RIE (reactive ion etching). 3 is removed to expose the n-type semiconductor layer 2, and an n-type electrode 4 and a p-type electrode 5 are formed on the exposed n-type semiconductor layer 2 and p-type semiconductor layer 3 (FIG. )).

  Grooves 10 are formed on the substrate 1 with a dicing saw (not shown) (FIG. 2B), and the substrate 10 is divided into individual substrates 1 (FIG. 1C).

  Semiconductor devices that use gallium arsenide, gallium phosphide, etc. for the substrate are not hard when the substrate is divided, so the substrate is cut by a dicing saw or the like, but for substrates using sapphire or gallium nitride, Because of its high hardness, it is difficult to cut with only a dicing saw. Therefore, a method has been used in which a groove is formed at a divided portion with a dicing saw and the substrate is divided at the groove as a boundary.

  In such a manufacturing method, since the hardness of sapphire and gallium nitride forming the substrate is high, it takes time to form the groove, the blade of the dicing saw to be used becomes hot, and the blade is heavily worn. The cost was high. Further, since the substrate has a high hardness, a deep groove cannot be formed, and if the substrate is divided so as to be divided from the shallow groove, the cut surface does not become a flat surface and is easily cracked due to an uneven fracture surface. FIG. 6 shows an example of a semiconductor device having a non-uniform fracture surface. FIG. 6A is an overall view, and FIG. As described above, when the cut surface has a non-uniform fracture surface, there is a problem that even a substrate that becomes an adjacent semiconductor device is broken.

  In order to solve this problem, in recent years, it has been proposed to form a groove by using a laser beam such as YAG (Yttrium Aluminum Garnet). Since the laser beam can be locally heated, a deep groove can be formed quickly, and the substrate of the semiconductor device can be cut into individual members in a short processing time.

  In Patent Document 1, laser beams are irradiated in columns and rows from one surface of a substrate of a nitride semiconductor device to form a scribe line, and then a scribe line formed on the opposite surface is formed from the other surface by a dicer. A technique is also disclosed in which a groove is formed and the substrate of the nitride semiconductor device is divided.

  Further, in Patent Document 2, after forming a groove with a dicer from one surface of the substrate of the nitride semiconductor device, a groove for further cutting is formed by irradiating the groove with a laser beam, A technique for dividing a substrate of a nitride semiconductor device from the cutting groove is disclosed.

Further, in Patent Document 3, after forming a dividing groove by irradiating the surface of the semiconductor wafer on the semiconductor formation side with liquid nitrogen, the semiconductor wafer is brought into contact with liquid nitrogen to give a thermal shock, and thermal stress is applied from the dividing groove. Discloses a method in which a crack is generated and divided.
Japanese Patent Laid-Open No. 11-163403 (paragraph numbers 0038-0043, FIG. 1) Japanese Patent Laid-Open No. 11-177137 (paragraph number 0042-0045, FIG. 1) JP 2001-284292 A (paragraph number 0027-0034, FIG. 1)

  The problem to be solved is to irradiate a portion of the substrate to be divided with a laser beam and locally raise the temperature to 1000 ° C. or higher to sublimate the substrate and the compound containing gallium used in the semiconductor layer laminated on the substrate. However, a part of the compound containing sublimated gallium becomes a gallium compound such as gallium oxide (hereinafter referred to as a gallium compound) and adheres to a substrate or an electrode.

  Thus, when the deposit that is a gallium compound adheres to the electrode formed on the substrate, when connected to another electrode using the electrode of this semiconductor device, or when connected to another electrode by wire bonding, There arises a problem that the conduction state is lowered and the wire connection strength is lowered.

  In addition, when this deposit adheres to the substrate and resin sealing is performed as it is, a gap is formed between the substrate and the resin, moisture enters from there, and if the deposit is heated, There is a problem that peeling occurs.

  Accordingly, the present invention provides a semiconductor in which when a substrate on which a semiconductor layer containing gallium is formed is divided into at least one of the semiconductor layer and the substrate, the dividing surface can be uniformly formed in a plane, and the occurrence of poor electrode conduction and resin peeling is small. An object is to provide a method for manufacturing a device.

  The semiconductor device of the present invention is a semiconductor device in which an n-type semiconductor layer and a p-type semiconductor layer are stacked on a substrate formed of gallium nitride, and the side surface of the semiconductor device is the n-type semiconductor layer of the substrate. And a p-type semiconductor layer formed by dividing a groove formed by laser irradiation from the side where the p-type semiconductor layer is laminated.

  As described above, in the method for manufacturing a semiconductor device of the present invention, a substrate on which a semiconductor layer containing gallium is formed on at least one of a semiconductor layer and a substrate is irradiated with a laser to divide the substrate into individual substrates. Then, by immersing the substrate in which the grooves are formed in an acid solution, the deposits of the gallium compound adhering to the laser irradiation can be removed.

  Therefore, since an adherent does not adhere to the electrode formed on the substrate when individual substrates are formed, it is possible to prevent a decrease in connection strength of the electrode formed on the substrate. In addition, when the substrate is sealed with a resin, it is possible to remove the contaminants from the interface by removing the adhering matter, so that the resin can be prevented from being peeled off.

  In addition, when the semiconductor device is a light emitting element, the gallium compound attached to the light emitting surface can be removed with an acid solution, so that a decrease in luminance of light emitted from the light emitting surface can be prevented.

  According to the present invention, when a substrate on which a semiconductor layer containing gallium is formed on at least one of the semiconductor layer and the substrate is divided, the cut surface is uniform in a plane, and deposits attached when dividing by laser irradiation can be removed. In order to obtain a semiconductor device, it was possible to remove deposits by immersing a substrate on which grooves, which are boundaries to be divided by laser irradiation, were formed in an acid solution.

  According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device in which a substrate having a semiconductor layer containing gallium formed on at least one of a semiconductor layer and a substrate is divided by laser irradiation. Forming a boundary between individual substrates, immersing the substrate in an acid solution, and dividing the substrate into individual substrates from the boundary where the grooves are formed. This is a method for manufacturing a semiconductor device. By dipping in an acid solution, a gallium compound, which is a deposit generated by laser irradiation, can be removed.

  According to a second aspect of the present invention, there is provided a method for manufacturing a semiconductor device, wherein the substrate is taken out from the acid solution and then divided into individual substrates from the boundary where the grooves are formed, and the substrate is immersed in the acid solution. Thereby, the gallium compound which is the deposit generated by the laser irradiation can be removed.

  According to a third aspect of the present invention, there is provided a method for manufacturing a semiconductor device, wherein the substrate is divided into individual substrates from the boundary where the grooves are formed, and then immersed in the acid solution. Since a gap is formed between them, the gallium compound that is a deposit can be efficiently removed.

  According to a fourth aspect of the present invention, there is provided a method for manufacturing a semiconductor device, wherein a groove is formed by irradiating a laser-irradiated portion from an opposite surface on which a semiconductor layer is formed. By performing laser irradiation from the opposite surface, the influence of heat on the semiconductor layer can be suppressed.

  According to a fifth aspect of the present invention, there is provided a method for manufacturing a semiconductor device, wherein the groove is irradiated with laser irradiation from an oblique direction so that the cross section is formed in a V shape. By doing so, the light emitted inside the semiconductor layer can be easily extracted to the outside, so that the luminance is improved.

  According to a sixth aspect of the present invention, there is provided a method for manufacturing a semiconductor device, wherein the laser irradiation is performed from the surface side on which the semiconductor layer is formed to form the groove, and the semiconductor layer is formed. The laser irradiation can be performed while visually confirming the surface side, so that the divided part of the substrate can be easily confirmed.

  A seventh invention is a method for manufacturing a semiconductor device, wherein the acid solution is hydrochloric acid or nitric acid. When immersed in hydrochloric acid, the gallium compound generated by laser irradiation is salified with hydrochloric acid. It can be removed as gallium.

  An eighth invention is a method for manufacturing a semiconductor device characterized in that the semiconductor device is a light emitting element. By removing the adhering material adhering to the light emitting surface of the light emitting element, a decrease in luminance can be prevented. .

  According to a ninth aspect of the present invention, there is provided a method for manufacturing a semiconductor device, wherein the groove is 30% or more of the thickness of the substrate, and the substrate is formed by setting the groove to be 30% or more of the thickness of the substrate. The dividing surface when cut can be made uniform.

(Embodiment 1)
A light-emitting element which is an example of a semiconductor device obtained by the method for manufacturing a semiconductor device according to the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a diagram illustrating a configuration of a semiconductor device obtained by a method for manufacturing a semiconductor device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention.

  First, a configuration of a light-emitting element that is an example of a semiconductor device obtained by a method for manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, each of the light-emitting elements cut individually includes a substrate 1 made of sapphire or gallium nitride, an n-type semiconductor layer 2 made of gallium nitride, and a nitrided n-type semiconductor layer 2. A p-type semiconductor layer 3 made of gallium is stacked. An n-type electrode 4 is formed in the region of the n-type semiconductor layer 2, and a p-type electrode 5 is formed in the region of the p-type semiconductor layer 3.

  By connecting a positive electrode to the p-type electrode 5 and a negative electrode to the n-type electrode 4 and supplying a current to this light-emitting element, light is emitted using the surface opposite to the formation surface of the p-type electrode 5 and the n-type electrode 4 as a light-emitting surface. .

  Next, a method for manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIG.

  In FIG. 2, each of the n-type semiconductor layer 2 and the p-type semiconductor layer 3 is formed on a substrate 1 made of sapphire or gallium nitride by MOCVD or the like (FIG. 2A).

  Next, the substrate 1 on which the n-type semiconductor layer 2 and the p-type semiconductor layer 3 are formed is removed by RIE, a part of the p-type semiconductor layer 3 is exposed to expose the n-type semiconductor layer 2, and each region is formed. The p-type electrode 5 is provided in the p-type semiconductor layer 3 region and the n-type electrode 4 is provided in the n-type semiconductor layer 2 region so that ohmic contacts can be obtained in the p-type semiconductor layer 3 region and the n-type semiconductor layer 2 region, respectively. Is formed ((b) in the figure).

  Then, the substrate 1 on which the n-type electrode 4 and the p-type electrode 5 are formed is polished to a predetermined thickness from the side opposite to the electrode forming surface ((c) in the figure).

  In order to use the substrate 1 having a predetermined thickness as individual light emitting elements, the YAG laser 6 irradiates the substrate 1 from the surface side in which the p-type electrode 5 and the n-type electrode 4 are formed in columns and rows, The groove is formed so as to have a depth of about 30% to 60% of the thickness of the substrate 1 ((d) in the figure).

  When the depth of the groove is too shallow than 30% of the thickness of the substrate 1, when the substrate is divided into individual substrates, the dividing surface at the boundary is not uniform and a fracture surface is formed. In the case of forming a groove that is deeper than 60%, the substrate may be cracked when immersed in an acid solution, or the groove formation time may be increased by laser irradiation. On the other hand, it is desirable to form a groove having a depth of about 30% to 60%.

  By irradiating the YAG laser 6 from the surface side of the substrate 1 on which the p-type electrode 5 and the n-type electrode 4 are formed, laser irradiation can be performed while visually confirming, and the divided portion of the substrate can be easily confirmed.

  At this time, when gallium is melted, evaporated or oxidized by irradiation with the YAG laser 6, it becomes a compound such as gallium or gallium oxide, and the side surface of the groove forming the boundary, the p-type electrode 5 or n It adheres to the mold electrode 4 and the like (not shown).

  The substrate 1 in which the groove is formed is immersed in a solution tank 8 in which hydrochloric acid 7, which is an acid solution containing hydrochloric acid as a main component, is stored for 5 minutes. This hydrochloric acid 7 is diluted with a solution having a concentration of about 30% and is 80 ° C. or lower (FIG. (E)).

Thus, as an example of the case where the gallium compound is gallium oxide, gallium oxide, which is a deposit attached to the side surface of the groove forming the boundary, is peeled off by a reaction represented by Ga ₂ O ₃ + 6HCl → 2GaCl ₃ + 3H ₂ O. Removed.

  Finally, the substrate 1 in which the groove is formed is taken out from the hydrochloric acid 7 in the solution tank 8, washed with pure water and dried, and pressed by the roller 9 from the surface opposite to the electrode forming surface (FIG. 5 (f)). ). By the pressing of the roller 9, it is divided so as to break from the groove that is the boundary, and becomes individual light emitting elements.

  In the embodiment of the present invention, each light emitting element is divided using the roller 9, but it may be divided into individual light emitting elements by pressing a blade into a groove as a boundary.

The acid solution can remove gallium oxide, which is an adhering substance, even as a solution mainly composed of nitric acid or the like. In this case, gallium oxide is peeled off and removed by a reaction represented by Ga ₂ O ₃ + 6HNO ₃ → 2Ga (NO ₃ ) ₃ + 3H ₂ O.

  In the method for manufacturing a semiconductor device according to the embodiment of the present invention, as shown in FIG. 2D, an n-type semiconductor layer 2 and a p-type semiconductor layer 3 are formed on a substrate 1, and an n-type electrode 4 and Although the groove was formed by irradiating the YAG laser 6 from the surface side where the p-type electrode 5 was formed, even if the YAG laser 6 was irradiated from the opposite surface where the n-type semiconductor layer 2 and the p-type semiconductor layer 3 were formed, Good.

  As shown in FIG. 3A, the YAG laser 6 is irradiated from the opposite surface side where the n-type electrode 4 and the p-type electrode 5 are formed to form the groove 10. In this way, by forming the groove 10 from the side opposite to the electrode forming surface of the substrate 1, the influence of heat is applied to the n-type electrode 4 and the p-type electrode 5, the n-type semiconductor layer 2 and the p-type semiconductor layer. Therefore, the groove 10 can be formed without giving to the bonding surface 3, and a light-emitting element with high luminance can be obtained.

  Further, as shown in FIG. 3B, the YAG laser 11 is obliquely irradiated from the opposite surface side where the n-type electrode 4 and the p-type electrode 5 are formed to form the grooves 12. In this way, by irradiating the YAG laser 11 obliquely from the surface opposite to the electrode forming surface of the substrate 1 and forming the groove 12 having a substantially V-shaped cross section, the light emitted inside the semiconductor layer is externally transmitted. Therefore, the luminance is improved.

  The groove 12 may be a groove formed by an inclined surface and a vertical surface, in addition to having a substantially V-shaped cross section.

  When the grooves 10 and 12 shown in FIG. 3 are formed, the grooves having a depth of about 30% to 60% with respect to the thickness of the substrate 1, as in the case of laser irradiation from the electrode forming surface side of the substrate 1. It is desirable to form.

(Embodiment 2)
Next, a method for manufacturing a semiconductor device according to the second embodiment of the present invention will be described with reference to FIG.

  Since (a), (b), and (c) of FIG. 4 are the same steps as (a), (b), and (c) of FIG. 2, description thereof is omitted.

  In order to form a semiconductor layer and an electrode on a sapphire or gallium nitride substrate in the steps (a), (b), and (c) of FIG. A surface opposite to the formation surface of the p-type electrode 5 and the n-type electrode 4 is attached to the dicing tape 13 made of polyethylene or the like. ((D) in the figure).

  The YAG laser 6 irradiates the substrate 1 from the surface side where the p-type electrode 5 and the n-type electrode 4 are formed in columns and rows, and the groove serving as the boundary has a depth of 30% or more of the thickness of the substrate 1. (FIG. (E)).

  After the groove is formed, the roller 9 presses the surface opposite to the surface of the dicing tape 13 on which the substrate 1 is attached ((f) in the figure). By the pressing of the roller 9, it is divided so as to break from the groove that is the boundary, and becomes individual light emitting elements.

  Thereafter, the dicing tape 13 is heated, and the dicing tape 13 is stretched and fixed in a state where a gap is formed so that a gap is formed between each of the divided light emitting elements ((g) in the figure).

  Next, with the individual light emitting elements attached to the dicing tape 13, the substrate is immersed for 5 minutes in a solution tank 8 storing hydrochloric acid 7, which is an acid solution mainly composed of hydrochloric acid. This hydrochloric acid 7 is diluted with a solution having a concentration of about 30% and is 80 ° C. or lower ((h) in the figure).

  By providing a gap between the individual light emitting elements, the gallium compound formed in the cross section of the light emitting element is efficiently removed. The gap may be a gap that allows the solution to enter, and preferably 10 μm or more. In particular, when gallium nitride is used for the substrate 1, the gallium compound formed in the cross section adheres in a larger amount than when sapphire is used for the substrate, so that the removal effect is increased.

  Thus, according to the method of manufacturing a semiconductor device according to the embodiment of the present invention, in order to form individual substrates, the gallium compound that adheres when forming a groove that is a boundary formed by laser irradiation is oxidized. It can be removed by dipping in a solution. Therefore, when a light-emitting element is manufactured as a semiconductor element, the attached matter attached to the light-emitting surface can be removed, so that a reduction in luminance can be prevented.

  In the above embodiment, description is made mainly using sapphire or gallium nitride as a substrate, but the substrate can also be applied to compounds containing gallium such as other gallium nitride compounds, gallium arsenide compounds, gallium phosphorus compounds, and the like. Can do.

  Although the light emitting element is used as the semiconductor device, an electronic element such as a light receiving element or a transistor may be used.

  It is effective as a method for manufacturing a semiconductor device that cuts a substrate in which a semiconductor layer containing gallium is formed on at least one of the semiconductor layer and the substrate with a laser beam, and in particular, manufacturing a light-emitting element using sapphire and a gallium compound semiconductor as the substrate Suitable for the method.

The figure explaining the structure of the semiconductor device obtained by the manufacturing method of the semiconductor device which concerns on embodiment of this invention The figure explaining the manufacturing method of the semiconductor device which concerns on embodiment of this invention The figure explaining the manufacturing method of the semiconductor device which is other embodiment The figure explaining the manufacturing method of the semiconductor device which is other embodiment The figure explaining the manufacturing method of the conventional semiconductor device The figure which shows the state of the semiconductor device obtained by the manufacturing method of the conventional semiconductor device

Explanation of symbols

1 substrate 2 n-type semiconductor layer 3 p-type semiconductor layer 4 n-type electrode 5 p-type electrode 6, 11 YAG laser 7 hydrochloric acid 8 solution tank 9 roller 10, 12 groove 13 dicing tape

Claims (3)

In a semiconductor device in which an n-type semiconductor layer and a p-type semiconductor layer are stacked on a substrate formed of gallium nitride, the side surface of the semiconductor device is stacked with the n-type semiconductor layer and the p-type semiconductor layer of the substrate. A semiconductor device formed by dividing a groove formed by laser irradiation from the formed surface side. An n-type electrode is formed on the n-type semiconductor layer exposed by removing a part of the p-type semiconductor layer, a p-type electrode is formed on the p-type semiconductor layer, and the n-type electrode and the p-type electrode are The semiconductor device according to claim 1, wherein the semiconductor device is formed on a surface side of the substrate on which the n-type semiconductor layer and the p-type semiconductor layer are laminated. 3. The semiconductor device according to claim 1, wherein a depth of the groove formed by laser irradiation on the side surface is in a range of 30 to 60% of a thickness of the substrate.

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