Source: https://patents.google.com/patent/JP4993371B2/en
Timestamp: 2020-01-24 15:43:21
Document Index: 97476006

Matched Legal Cases: ['art 17', 'art 18', 'art 23', 'art 22', 'art 15', 'art 20']

JP4993371B2 - Wafer surface roughening method for semiconductor light emitting device and semiconductor light emitting device - Google Patents
Wafer surface roughening method for semiconductor light emitting device and semiconductor light emitting device Download PDF
JP4993371B2
JP4993371B2 JP2007301569A JP2007301569A JP4993371B2 JP 4993371 B2 JP4993371 B2 JP 4993371B2 JP 2007301569 A JP2007301569 A JP 2007301569A JP 2007301569 A JP2007301569 A JP 2007301569A JP 4993371 B2 JP4993371 B2 JP 4993371B2
JP2007301569A
JP2009130027A (en
2007-11-21 Application filed by サンケン電気株式会社, パナソニック株式会社 filed Critical サンケン電気株式会社
2007-11-21 Priority to JP2007301569A priority Critical patent/JP4993371B2/en
2009-06-11 Publication of JP2009130027A publication Critical patent/JP2009130027A/en
2012-08-08 Publication of JP4993371B2 publication Critical patent/JP4993371B2/en
The present invention relates to a method for forming a rough surface for suppressing total reflection on a semiconductor light emitting device wafer, and a semiconductor light emitting device having a rough surface for suppressing total reflection.
The semiconductor light emitting diode is composed of a semiconductor chip that emits light and a light-transmitting protective resin that covers the semiconductor chip. A semiconductor layer (for example, a current dispersion layer or a contact layer) having a surface for taking out light of the semiconductor chip has a light refractive index of about 2.0 to 3.5, and a protective resin has a light refractive index of about 1.5. Therefore, the critical angle between the semiconductor chip and the protective resin is 25 to 48 degrees. For this reason, when the incident angle of light incident on the light extraction surface of the semiconductor chip is larger than the critical angle, total reflection occurs, making it impossible to extract light having a large incident angle to the outside, and the light extraction efficiency is improved. descend.
It is known in Japanese Patent Application Laid-Open No. 2003-209283 (Patent Document 1) and the like to roughen the surface of a semiconductor chip in order to suppress the decrease in light extraction efficiency due to the total reflection. In Patent Document 1, the light extraction surface of the light emitting semiconductor region is roughened by blade processing (processing by a blade) or etching processing using a resist mask (photolithography technology). However, in the case of blade processing, a special tool is required, and in the case of photolithography technology, not only a mask is required, but also unevenness of tens to hundreds of nm can be stably formed. difficult. For this reason, it has been difficult to easily and inexpensively form a rough surface on the surface of the light emitting semiconductor region by a conventional method. Further, it has been difficult to further improve the light extraction efficiency of the semiconductor light emitting device.
Japanese Patent Laid-Open No. 2003-209283
The problem to be solved by the present invention is that a semiconductor light emitting device having a rough surface capable of further improving the light extraction efficiency is required, and the object of the present invention is to provide a semiconductor light emitting device capable of meeting this requirement. It is an object to provide a method for roughening a device wafer and a semiconductor light emitting device.
Forming a resist film on the surface of the wafer having a light emitting semiconductor region;
A concave portion corresponding to the convex portion of the concave and convex surface of the molding die and the molding die by pressing a molding die having a concave and convex surface in which a large number of convex portions or concave portions are arranged at a first average pitch against the resist film. Forming a convex portion corresponding to the concave portion of the concave and convex surface of the mold on the resist film;
Performing a non-selective etching process on the resist film to remove all of the concave portions of the resist film and removing a portion of the convex portions of the resist film, thereby obtaining a mask comprising the remaining portion of the resist film; ,
Forming a first recess corresponding to the recess of the resist film in the portion which is not covered by the mask of the wafer by applying a continuous etching process or another etching process for etching the processing of the resist film on the wafer Process,
The remaining portion of the resist film is removed after or during the etching process of the wafer, and the first recess is formed on the surface of the wafer via the first recess and the inclined side surface of the first recess. A step of obtaining the first convex portion disposed adjacent to the first convex portion repeatedly with a first average pitch ; and
The step of forming the over the surface of the wafer, a metal film made of a metal material having a property of functioning as a mask when and etching the wafer has a property to aggregate with said first recess and said first protrusion When,
A plurality of heat treatments at a temperature capable of agglomeration are performed on the metal film simultaneously with or after the formation of the metal film, and the metal film is arranged at a second average pitch smaller than the first average pitch. And the step of not disposing the metal film and the granular body on the inclined side surface ,
In the plurality of the areas not covered by the granules by etching the first recess and the first pre-Symbol second average pitch protrusions of the wafer using said plurality of granules as a mask Obtaining a plurality of second concave portions and second convex portions arranged; and
After or during the step of forming a large number of the second concave portions and the second convex portions arranged at the second average pitch on the surface of the wafer, the large number of granules on the wafer And a step of removing the surface of the wafer for a semiconductor light emitting device.
In addition, the wafer in the invention of each claim is not only a semiconductor wafer having only a light emitting semiconductor region, but also a wafer having a light-transmitting conductive film such as ITO on the light extraction surface of the semiconductor wafer, and the light emitting semiconductor region is a semiconductor substrate. Or the wafer etc. of the structure supported by the insulated substrate are also meant.
Moreover, the resist film in the invention of each claim means not only a film having etching resistance but also a film in which etching proceeds in proportion to the time of dry etching or wet etching.
In addition, the aggregation in the invention of each claim means a phenomenon in which the metal film changes into a large number of granular bodies (aggregates) or lumps.
Moreover, the etching in the invention of each claim means well-known dry etching or well-known wet etching.
Further, the first average pitch of the plurality of recesses or projections in the inventions of each claim is the mutual relationship between the center of the first recess or projection and the center of another first recess or projection adjacent thereto. Means the average value of a number of intervals. Similarly, the second average pitch of the multiple recesses or projections is the multiple average of the mutual distance between the center of the second recess or projection and the center of another second recess or projection adjacent thereto. Means value.
According to a second aspect of the present invention, it is preferable that the etching process of the resist film is dry etching, and the etching using the granular material as a mask is also dry etching.
According to a third aspect of the present invention, the resist film is selectively removed instead of obtaining a large number of recesses or protrusions arranged at the first average pitch using a molding die for the resist film. As a result, a large number of openings or concave portions or convex portions arranged at the first average pitch can be formed in the resist film.
According to a fourth aspect of the present invention, before the step of forming a large number of openings or concave portions or convex portions arranged at the first average pitch in the resist film, the first step is performed based on the aggregation of the metal film on the surface of the wafer. A step of obtaining a large number of granules (aggregates) arranged at an average pitch of 2, and etching the areas of the wafer not covered with the multiple granules using the plurality of granules as a mask. A step of obtaining a large number of convex portions arranged at the second average pitch on the surface of the wafer can be provided.
In addition, as shown in claim 5, after the step of obtaining a large number of granules (aggregates) arranged at the second average pitch on the surface of the wafer based on the aggregation of the metal film, the granules (aggregates) Next, a resist film is provided on the surface of the wafer, and then a large number of openings, recesses, or protrusions arranged at the first average pitch are formed in the resist film, and then the resist having openings, recesses, or protrusions Etching is performed on the wafer using the film as a mask and the remaining resist film is removed, and then, using a large number of granular materials as a mask, etching is performed on regions not covered with the large number of granular materials on the wafer. A large number of second convex portions and concave portions arranged at the second average pitch on the surface of the wafer can be obtained.
The invention relating to the method of roughening a wafer for a semiconductor light emitting device according to claim 1 of the present application has the following effects.
(1) In the first aspect of the present invention, a concave or convex portion having the first pitch is formed on the resist film using a molding die, and then the resist film having the concave or convex portion is used as a mask on the wafer. By performing an etching process, a plurality of first concave portions and first convex portions having a first average pitch are formed on the wafer. Therefore, a plurality of first concave portions and first convex portions having the first average pitch can be easily formed on the wafer without using a photolithography technique.
(2) The second concave portions and convex portions arranged at the second average pitch smaller than the first average pitch form a metal film made of a metal material having an aggregating property on the surface of the wafer. It is formed by etching the wafer using the granular material (aggregate) formed by the above method as a mask. Therefore, the second concave portions and the convex portions arranged at the second average pitch can be easily formed without a photolithography process, and the processing cost can be reduced.
(3) when forming the semiconductor light-emitting element and the first concave and convex portions and the second concave and convex portions of the semiconductor wafer, it contributes to the reduction of the total reflection in the light extraction surface. The provision of the second concave and convex portions first recess and convex portions having different average pitches, the effective area of the light extraction surface is increased, the light extraction efficiency is improved.
(4) Even if the light exceeds the critical angle with respect to the first concave portion and the convex portion, the critical angle may not be exceeded with respect to the inclined side surface. Therefore, the light extraction improvement effect can be obtained by the inclined side surface.
According to the invention according to claim 2, the first concave portion or the convex portion and the second concave portion or the convex portion can be easily formed by dry etching.
In the invention according to claim 3, instead of forming irregularities in the resist film using the molding die according to claim 1, an opening, a concave portion or a convex portion is formed in the resist film by a well-known lithography technique, and then the wafer is formed. Etching. Therefore, according to the invention of claim 3, the effect (1) of the invention of claim 1 cannot be obtained. However, since the method of forming the second concave portion and the convex portion having the second average pitch is the same as that of the invention of claim 1, the same as (2), (3) and (4) of the invention of claim 1 The effect is obtained.
In the inventions of claims 4 and 5, the second concave portions and the convex portions arranged at the second average pitch are formed by etching using a granular material formed based on aggregation as a mask. Therefore, the inventions of claims 4 and 5 can obtain the same effects as the above-mentioned (2), (3) and (4) of the invention of claim 1.
The semiconductor light-emitting device according to the invention of claim 6, rough surface including a first recess and a convex portion disposed at a first average pitch, and a second recess and convex portions arranged at a second average pitch Therefore, the same effect as the above (3) (4) of the invention of claim 1 can be obtained.
A semiconductor wafer 1 for a double heterojunction semiconductor light emitting device in Example 1 shown in FIG. 1 includes a substrate 2, a buffer layer 3, and a light emitting semiconductor region 4. The light emitting semiconductor region 4 is a portion that generates light, and includes an n-type semiconductor layer 5, an active layer 6, a p-type semiconductor layer 7, and an auxiliary semiconductor layer 8. The substrate 2 is made of silicon to which an n-type or p-type impurity is added and has conductivity. The substrate 2 can be formed of a semiconductor other than silicon, or an insulator such as sapphire or ceramic. The buffer layer 3 is a multilayer structure buffer in which AlN and GaN are alternately epitaxially grown on the substrate 2 a plurality of times. Of course, the buffer layer 3 can be a single buffer layer or the buffer layer 3 can be omitted.
The n-type semiconductor layer 5 can also be called an n-type cladding layer, and is formed by epitaxially growing, for example, an n-type nitride semiconductor (for example, n-type GaN) on the buffer layer 3. The active layer 6 is formed, for example, by epitaxially growing a nitride semiconductor (for example, InGaN) to which no impurity is added on the n-type semiconductor layer 5. In FIG. 1, the active layer 6 is shown as a single layer for the sake of simplicity, but actually has a well-known multiple quantum well structure. Of course, the active layer 6 may be a single semiconductor layer. Alternatively, the active layer 6 may be omitted and the p-type semiconductor layer 7 may be in direct contact with the n-type semiconductor layer 5. The p-type semiconductor layer 7 can also be called a p-type cladding layer, and is formed by epitaxially growing, for example, a p-type nitride semiconductor (for example, p-type GaN) on the active layer 6. The auxiliary semiconductor layer 8 disposed on the p-type semiconductor layer 7 can also be called a current dispersion layer or an ohmic contact layer. For example, a p-type impurity is added at a higher concentration than the p-type semiconductor layer 7. For example, the p-type nitride semiconductor layer (for example, p-type GaN) is formed by epitaxial growth. Since this auxiliary semiconductor layer 8 is not directly involved in light emission, it can be omitted.
One main surface 9 of the semiconductor wafer 1 having a light emitting function functions as a light extraction surface. The anode electrode of the semiconductor light emitting element is formed on one main surface 9 of the semiconductor wafer 1, and the cathode electrode is formed on the other main surface 10 of the semiconductor wafer 1 having conductivity, that is, the lower surface of the substrate 2. A part of one main surface 9 of the semiconductor wafer 1 is covered with a light-transmitting protective resin when a semiconductor light emitting element is formed. As already described, the portion (auxiliary semiconductor layer 8) including the light extraction surface of the semiconductor wafer 1 and the light transmitting protective resin have different light refractive indexes. By the way, not all of the light directed to the light extraction surface is incident on the light extraction surface at an incident angle smaller than the critical angle. Light having an incident angle with respect to the light extraction surface larger than the critical angle is totally reflected by the light extraction surface and cannot be extracted outside. Accordingly, it is necessary to roughen one main surface 9 of the semiconductor wafer 1 in order to prevent a decrease in light extraction efficiency due to total reflection.
In the present embodiment, in order to roughen one main surface 9 used as the light extraction surface of the semiconductor wafer 1, the first average surface 9 of the semiconductor wafer 1 has a first average as shown in FIG. A large number of first concave portions 17 and convex portions 18 arranged at a pitch P1, and a large number of second concave portions 22 and convex portions 23 arranged at a second average pitch P2 smaller than the first average pitch P1; Is formed.
First, when forming the 1st recessed part 17 and the convex part 18, as shown in FIG. 2, the resist film (insulating film | membrane or the photosensitive resin film) 11 is applied on one main surface 9 of the semiconductor wafer 1, for example, the coating method To a predetermined thickness (for example, 1.5 to 2.0 μm). The resist film 11 of this embodiment is not used as a film for a typical lithography technique, but is used as a film for press working (plastic deformation processing). Therefore, the resist film 11 is formed of a material selected from various materials having a plastically deformable property, for example, SGO (Spin On Glass).
Next, the metal mold | die 12 as a shaping | molding die shown in FIG.3 and FIG.4 is prepared. A plurality of quadrangular pyramid-shaped convex portions 13 are formed on the mold 12 with a first average pitch P1, that is, a center interval. In the mold 12 of FIG. 3, a plurality of convex portions 13 are arranged with regularity. However, the convex portions 13 can be arranged irregularly, that is, randomly. When the plurality of convex portions 13 are irregularly arranged, the center interval between two adjacent convex portions 13 does not become a constant value. Therefore, the average of the mutual intervals of the many convex portions 13 is referred to as a first average pitch P1. Note that even if the convex portions 13 are arranged with regularity, not all the mutual intervals are the same, so the average of all the mutual intervals will be referred to as the first average pitch P1. . The shape of the convex portion 13 of the mold 12 is determined so that a first concave portion 17 in the semiconductor wafer 1 to be described later is obtained.
3 and 4 can be changed to other shapes such as a prismatic shape, a truncated cone shape, a cylindrical shape, a triangular pyramid shape, a triangular frustum shape, and a triangular prism shape.
The number of the convex portions 13 and the first average pitch P1 are determined so that the plurality of convex portions 13 are included in an area corresponding to the light extraction surface of one completed semiconductor light emitting element. Further, the first average pitch P1 is determined to be larger than a second average pitch P2 described later, and preferably 1 to 20 μm. Further, the height of the convex portion 13 is preferably determined to be 0.5 to 5 μm.
Next, as shown in FIG. 4, the surface of the mold 12 having the convex portion 13 is opposed to the resist film 11, and the mold 12 is pressed against the resist film 11 with a predetermined pressure (for example, 50 MPa). A plurality of concave portions 14 corresponding to the plurality of convex portions 13 of the mold 13 are formed in the resist film 11 by plastic deformation. As a result, a plurality of concave portions 14 and convex portions 15 surrounding the concave portions 14 are formed in the resist film 11. The convex portion 15 of the resist film 11 has a lattice-like planar pattern and is thicker than the concave portion 14.
Next, the semiconductor wafer 1 with the resist film 11 having the recesses 14 shown in FIG. 4 is placed in chlorine tetrachloride (CCl 4 ) gas, and non-selectively dry-etched with respect to the resist film 11 only for a predetermined time ( Plasma etching) is performed. As a result, the thin concave portion 14 of the resist film 11 is completely removed, and a remaining portion 11 ′ consisting of a part of the thick convex portion 15 is generated as shown in FIG. This remaining portion 11 'functions as a mask for selective etching. Instead of carbon tetrachloride (CCl 4 ) gas, for example, chlorine (Cl 2 ), carbon difluoride dichloride (CCl 2 F 2 ), carbon tetrafluoride (CCl 2 ), or boron trichloride (BCl 3) ) Etc. can be used for dry etching. Further, instead of plasma etching, dry etching such as well-known vapor phase etching, reactive ion etching, sputter etching, ion beam etching, and photo etching can be performed.
Next, a dry etching (plasma etching) process is performed on the semiconductor wafer 1 by using the remaining portion 11 ′ of the resist film left by the same etching gas as that during dry etching of the resist film 11 as a mask, and one main surface of the semiconductor wafer 1. A plurality of first recesses 17 are formed in 9. Note that the dry etching process of the semiconductor wafer 1 can be performed by an etching gas different from the dry etching process of the resist film 11. When the semiconductor wafer 1 is dry-etched, the remaining portion 11 ′ is gradually thinned.
Next, the remaining portion 11 ′ of the resist film is removed by, for example, a solvent to obtain a semiconductor wafer 1 in which a plurality of first recesses 17 are arranged on one main surface 9 as shown in FIGS. 6 and 7. It is also possible to perform a dry etching process for forming the first recess 17 in the semiconductor wafer 1 until the remaining portion 11 ′ of the resist film disappears by the dry etching process. In this case, a special process for removing the remaining portion 11 ′ of the resist film shown in FIG. 5 is not necessary.
The first concave portions 17 shown in FIGS. 6 and 7 are regularly arranged corresponding to the convex portions 13 of the mold 12, and the distance between the centers of the two adjacent first concave portions 17 is as shown in FIG. This is the same as the first average pitch P1 of the convex portions 13 of the mold 12. As already described, the size and number of the first recesses 17 on the one main surface 9 of the semiconductor wafer 1 are such that when the semiconductor wafer 1 is divided into a plurality of semiconductor light emitting element chips, It is determined so that there are a plurality of first recesses 17 on the light extraction surface. For this reason, the first average pitch P1 between the first recesses 17 is preferably determined to be 1 to 20 μm, and the depth from one main surface 9 to the bottom surface of the first recess 17 is preferably 0. .1-5 μm is determined.
A portion between the first concave portions 17 on one main surface 9 of the semiconductor wafer 1 can also be referred to as a first convex portion 18. The first convex portion 18 is a flat surface that can also be referred to as an upper surface portion, and has a lattice-like planar pattern surrounding the first concave portion 17.
The first concave portion 17 will be described in more detail. The first concave portion 17 has a flat bottom surface 41 and an inclined side surface (wall surface) 42. The bottom surface 41 of the first recess 17 and the flat surface (upper surface) of the first protrusion 18 are parallel to the substrate 2 and the active layer 6. The area of the bottom surface 41 of the first recess 17 after the formation of the first recess 17 with respect to the area A of the one main surface 9 of the semiconductor wafer 1 before forming the first recess 17 and the first protrusion 18 A preferable value of the ratio (B / A) of the sum B with the area of the flat surface is 50% or more. That is, in order to obtain the light extraction improvement effect by the scattering effect based on the second convex part 23 and the second concave part 22 described later, the larger the value of B / A is, the better. However, when light exceeding a critical angle with respect to the flat surface of one main surface 9 of the semiconductor wafer 1 is incident, the light extraction improvement effect based on the second convex portion 23 and the second concave portion 22 cannot be expected so much. In order to solve this problem, the inclined side surface (wall surface) 42 of the first recess 17 contributes. The inclined side surface (wall surface) 42 of the first recess 17 has a critical angle with respect to the inclined side surface (wall surface) 42 even if the light greatly exceeds the critical angle with respect to the flat surface of the one main surface 9 of the semiconductor wafer 1. Otherwise it can be passed. If the value of B / A is 50% or more, the light extraction improvement effect is greater than when only the first recess 17 is provided and when only the second recess 22 is provided.
In the present embodiment, the second convex portion 23 and the second concave portion 22 are not provided on the inclined side surface (wall surface) 42. When the angle θ of the inclined side surface (wall surface) 42 is 35 degrees or more, the granular material (aggregate) 21 described later is hardly formed on the inclined side surface (wall surface) 42 or is not formed. A more preferable angle θ of the inclined side surface (wall surface) 42 is 60 to 80 degrees.
On one main surface 9 of the semiconductor wafer 1 having the first concave portion 17, a number of second convex portions 23 arranged at a second average pitch P2 smaller than the first average pitch P1 shown in FIG. In order to form the second recess 22, first, as shown in FIG. 8, the one main surface 9 of the semiconductor wafer 1 having the first recess 17 is made of a material different from that of the semiconductor wafer 1 and is granular by heat treatment. A metal material (for example, Ag) that easily forms or aggregates is deposited on one main surface 9 of the semiconductor wafer 1 to form a mask forming metal film 20. More specifically, for example, Ag (silver) is deposited on one main surface 9 of the semiconductor wafer 1 using a vacuum deposition apparatus which is one of film forming apparatuses generally used in the field of semiconductors. A mask forming metal film 20 shown in FIG. 8 is formed. The mask-forming metal film 20 preferably has a thickness of 2 to 100 nm (20 to 1000 mm), more preferably 10 to 30 nm, and the thickness in this example is 20 nm. The thickness of the mask-forming metal film 20 is adjusted according to the target particle size. However, when the thickness of the mask-forming metal film 20 is greater than 100 nm, there are many agglomeration defects in which the granular material (aggregate) and the granular material (aggregate) are connected, and when the thickness is less than 2 nm, the target It is difficult to obtain particles of a size that meets the requirements.
Note that Ag is suitable as a material for the mask-forming metal film 20 because it is easily granulated (aggregated) and exhibits etching resistance in a later etching step. However, instead of Ag, an Ag alloy or Al (aluminum) is suitable. Alternatively, the mask forming metal film 20 may be formed using Cu (copper), Au (gold), or an alloy thereof. In addition, a substance that promotes aggregation can be added to the mask material. The mask forming metal film 20 can also be formed by another method such as a well-known sputtering method, electron beam evaporation method, or coating.
In this embodiment, the temperature of the semiconductor wafer 1 when the mask forming metal film 20 is formed by the vacuum deposition method is set to room temperature, but it may be set to room temperature to about 150 ° C. Further, the temperature of the semiconductor wafer 1 when forming the mask forming metal film 20 is set to a temperature at which the mask forming film 20 aggregates (for example, 150 to 500 ° C.), and the mask material is simultaneously formed with the mask forming metal film 20. Can be agglomerated. That is, when the heat treatment temperature of the semiconductor wafer 1 is set to a temperature at which the mask material can be agglomerated, Ag agglomeration occurs simultaneously with the deposition of Ag on the semiconductor wafer 1, and a large number of particles (aggregates) are obtained. .
Next, the semiconductor wafer 1 with the mask forming metal film 20 is put in a heat treatment furnace generally used in the field of semiconductors, and the semiconductor wafer 1 with the mask forming metal film 20 is compared with the semiconductor wafer 1 in the atmosphere. A heat treatment at 300 ° C. is performed to change the mask-forming metal film 20 into a large number of granular bodies (aggregates) 21 schematically shown in FIG. A preferable temperature for aggregating Ag by the heat treatment is 250 to 350 ° C. The heat treatment temperature for agglomeration varies depending on the change of the mask material, and is preferably selected from the range of 150 to 500 ° C. The preferred heat treatment time for this agglomeration step is in the range of 5-30 min. Ag aggregation hardly progresses even if the heat treatment time is extended to 15 minutes or more.
A large number of granular materials 21 are irregularly distributed on one main surface 9 of the semiconductor wafer 1. In FIG. 9, for the sake of easy illustration, a large number of granular materials 21 are shown in a hemispherical shape, but actually change indefinitely. In FIG. 9, the granular material 21 is disposed on both the bottom surface of the first concave portion 17 and the top surface of the first convex portion 18 on one main surface 9 of the semiconductor wafer 1, and the inclined side surface of the first concave portion 17. Is not arranged. However, the granular material 21 can be disposed on the inclined side surface of the first recess 17 as necessary.
The particle size of the granular material 21 changes in proportion to the thickness of the mask forming coating 20. When the thickness of the mask forming film 20 made of Ag is 20 nm, the particle size is in the range of 50 to 200 nm, and the average particle size is about 130 nm. If the thickness of the mask-forming metal film 20 made of Ag is greater than 50 nm, it becomes difficult to form a large number of independent granules 21 even when heat treatment for aggregation is performed. The connection between each other occurs, and a state where Ag is distributed in a mesh shape is generated. Further, when the thickness of the mask forming metal film 20 made of Ag is thicker than 100 nm, a thick portion of Ag is formed in a mesh shape on one main surface 9 of the semiconductor wafer 1 when heat treatment is performed. However, it is covered with thin Ag, and a granular material (aggregate) that can be used as a mask cannot be obtained, and the light extraction improvement effect can hardly be expected. Therefore, the preferable thickness range of the mask forming metal film 20 made of Ag is 2 to 100 nm as described above.
The number of granular materials 21 per 1 μm 2 based on aggregation of the mask-forming metal film 20 made of Ag having a thickness of 20 nm is 4 to 15. The number of the granular materials 21 per unit area changes in inverse proportion to the thickness of the mask forming metal film 20. The granular materials 21 are irregularly distributed on one main surface 9 of the semiconductor wafer 1, but are distributed in a relatively uniform state when viewed on the entire one main surface 9 of the semiconductor wafer 1.
As shown in FIG. 9, a large number of granules (Ag grains) 21 dispersed on one main surface 9 of the semiconductor wafer 1 function as a mask for selective etching of the semiconductor wafer 1. That is, one main surface 9 of the semiconductor wafer 1 can be etched using the granular material 21 as a mask. Therefore, in this embodiment, the granular material 21 of the semiconductor wafer 1 is formed by a well-known dry etching (plasma etching) method in which a Cl 2 gas (chlorine gas) is flowed on one main surface 9 of the semiconductor wafer 1 made of a nitride semiconductor. The uncovered portion is etched for about 10 to 30 minutes to form the second recess 22 shown in FIG. The second recess 22 has a lattice-like planar pattern corresponding to a portion of the one main surface 9 of the semiconductor wafer 1 that is not covered with the granular material 21. On one main surface 9 of the semiconductor wafer 1, a large number of second convex portions 23 each surrounded by a second concave portion 22 having a lattice-like plane pattern are generated. The second convex portion 23 is generated in a portion corresponding to the lower part of the granular material 21.
The granular material 21 after dry etching in FIG. 10 is shown in substantially the same shape as the granular material 21 before dry etching in FIG. However, Ag forming the granular material 21 does not react with chlorine (Cl 2 ) gas in dry etching and reacts at a level lower than that of the semiconductor wafer 1, and therefore actually differs from before and after dry etching. The slight deformation of the granular material 21 does not cause any problem with respect to the roughening of one main surface 9 of the semiconductor wafer 1. Rather, the deformation of the granular material 21 may be convenient for roughening the semiconductor wafer 1.
Next, the granular material 21 made of Ag after dry etching shown in FIG. 10 is used as an etching solution for Ag, for example, an etching solution made of hydrogen chloride (HCI) and water, or ammonium hydroxide (NH 4 OH). The second recess 22 and the projection 23 shown in FIG. 11 are removed by etching for 2 minutes at room temperature with an etchant comprising hydrogen, hydrogen peroxide (H 2 O 2 ), and water (H 2 O). A semiconductor wafer 1 having a main surface 9, that is, a rough surface for preventing total reflection, is obtained. FIG. 12 schematically shows an enlarged part of one main surface 9 of the semiconductor wafer 1 of FIG. As is clear from this, the second convex portion 23 schematically shown in a circle is surrounded by the second concave portion 22.
Since the multiple second convex portions 23 on the one main surface 9 of the semiconductor wafer 1 are irregularly arranged, the multiple average values of the center-to-center distances between the two adjacent second convex portions 23 are calculated as the second value. Is defined as an average pitch P2. Many average values of the distances between the centers of the second concave portions 22 arranged between the second convex portions 23 are the same as the second average pitch P <b> 2 of the second convex portions 23.
The second concave portion 22 and the second convex portion 23 formed on one main surface 9 of the semiconductor wafer 1 have a function of suppressing total reflection on the light extraction surface of the semiconductor light emitting element. In order to satisfactorily achieve total reflection suppression, the second average pitch P2 of the second protrusions 23 is the same as the wavelength of light generated from the active layer 5 of the semiconductor wafer 1 or an order of a fraction thereof. For example, it is set to 50 to 800 nm, preferably 100 to 300 nm. The second average pitch P2 of the second convex portions 23 is significantly smaller than the first average pitch P1 of the first concave portions 17 formed on the one main surface 9 of the semiconductor wafer 1 described above.
As shown in FIGS. 11 and 12, a plurality of first concave portions 17 disposed on one main surface 9 of the semiconductor wafer 1 with a relatively large first average pitch P1 and a relatively small second average pitch P2 are used. The arranged second concave portion 22 and second convex portion 23 are mixed. The effect of this combination will be described later.
Next, an anode electrode and a cathode electrode are formed on the semiconductor wafer 1 and then divided into a plurality of light emitting element chips. After that, as shown in FIG. 13, the light emitting element chip is electrically connected to the first and second terminal members 24 and 25, and an enclosure 26 made of a light-transmitting protective resin is further provided. The semiconductor light emitting device (light emitting diode) in FIG. 13 will be described in more detail. A semiconductor chip 1 ′ corresponding to a semiconductor wafer 1 shown in FIG. 11 is divided into a substrate 2, a buffer layer 3, and a semiconductor wafer 1 in FIG. A substrate 2 ′, a buffer layer 3 ′, and a light emitting semiconductor region 4 ′ respectively corresponding to the light emitting semiconductor region 4 are provided. The light emitting semiconductor region 4 ′ in FIG. 13 includes an n-type semiconductor layer 5 ′ and an active layer 6 ′ corresponding to the n-type semiconductor layer 5, the active layer 6, the p-type semiconductor layer 7, and the auxiliary semiconductor layer 8, respectively. , P-type semiconductor layer 7 ′, and auxiliary semiconductor layer 8 ′. One main surface 9 ′ of the semiconductor chip 1 ′ schematically shown in FIG. 13 has a plurality of first recesses 17 and a number of second recesses 22 and protrusions 23 that are the same as those shown in FIG. 11. . An anode electrode 27 is formed at the center of the one main surface 9 ′, and the anode electrode 27 is connected to the second terminal member 25 by a metal wire 28. A cathode electrode 29 is formed on the other main surface 9 ′ of the semiconductor chip 1 ′, and the cathode 29 is connected to the first terminal member 24 by a bonding material (not shown). One roughened main surface 9 ′ functioning as a surface for extracting light from the semiconductor chip 1 ′ to the outside is covered with a light transmissive protective resin enclosure 26 indicated by a chain line. The optical refractive index of the protective resin enclosure 26 is about 1.5, which is smaller than the optical refractive index (for example, 2.5 to 3.5) of the semiconductor chip 1 ′.
(1) Using the mold 12 for the resist film 11 to form the recesses 14 with the first average pitch P1, and then etching the resist film 11 non-selectively, the thin first portion 15 of the resist film 11 is formed. Is removed before the thick second portion 16. As a result, the semiconductor wafer 1 can be selectively etched using the remaining portion 11 ′ of the second portion 16 as a mask, and the plurality of first recesses 17 having the first average pitch P 1 can be easily formed in the semiconductor wafer 1. Can be formed.
(2) The second concave portion 22 and the convex portion 23 arranged at the second average pitch P2 smaller than the first average pitch P1, the mask forming metal film made of silver which is a metal material having an aggregating property. The granular material 21 based on the aggregation of 20 is used as a mask. Since it is not necessary to regularly form the granular material 21 as a mask, the second concave portion 22 and the convex portion 23 can be easily formed without a photolithography process, and the processing cost is reduced. Can be achieved.
(3) The plurality of first concave portions 17 arranged at the first average pitch P1 and the plurality of second convex portions 23 arranged at the second average pitch P2 of the semiconductor wafer 1 are the light of the semiconductor light emitting device. This contributes to reduction of total reflection on the extraction surface. When not only the plurality of second convex portions 23 arranged at the second average pitch P2, but also the plurality of first concave portions 17 arranged at the first average pitch P1, a plurality of second convex portions are provided. The effective area of the light extraction surface is increased as compared with the case of only 23, and the light of the first concave portion 17 is also large even if the light greatly exceeds the critical angle with respect to the flat surface of one main surface 9 of the semiconductor wafer 1. Since the light can pass through the inclined side surface (wall surface) 42 if it does not exceed the critical angle, the light extraction efficiency is improved. That is, without forming the first concave portion 17 according to the present invention on one main surface 9 ′ of the semiconductor chip 1 ′, only the second concave portion 22 and the convex portion 23 according to the present invention are arranged at a pitch of several tens to several hundreds nm. The brightness of the formed semiconductor light emitting device is about 3.6 times that of a conventional semiconductor light emitting device in which one main surface (light extraction surface) of the semiconductor chip is not rough. In addition, the brightness of the semiconductor light emitting device when both the first concave portion 17 and the convex portion 18 and the second concave portion 22 and the convex portion 23 according to the present invention are formed is only the second concave portion 22 and the convex portion 23. The brightness was about 16% higher than the brightness when forming the film.
(4) A mask having a special pattern is used for one main surface 9 of the semiconductor wafer 1 and the second convex portion 23 of the one main surface 9 'of the semiconductor chip 1' required to suppress total reflection. It can be easily formed without. That is, a mask forming metal film 20 made of Ag is provided on the entire main surface 9 of the semiconductor wafer 1 using a film forming apparatus generally used in the field of semiconductors, and this is generally used for heat treatment. A large number of granular materials 21 functioning as a mask can be obtained by a simple method of heat treatment so that agglomeration occurs using a furnace. Therefore, it is possible to reduce the manufacturing cost for the roughening of one main surface 9 of the semiconductor wafer 1.
(5) Since the size of the granular material 21 changes when the thickness of the mask-forming metal film 20 is changed, the granular material 21 having an arbitrary size can be easily obtained.
(6) The shape and size of the second concave portion 22 and the convex portion 23 change depending on the dry etching conditions. Therefore, it becomes easy to adjust the shape and size of the second concave portion 22 and the convex portion 23.
(7) When the first concave portion 17 has a periodic structure with an appropriate pitch, an effect of improving the light extraction efficiency due to the light diffraction effect can be expected. Furthermore, since the light extraction efficiency improvement effect by the light scattering effect is obtained by the second concave portion 22 and the convex portion 23, the light extraction efficiency can be made larger than the light extraction efficiency improvement effect by itself due to the synergistic effect of both. .
(8) By forming the first concave portion 17, the second concave portion 22, and the convex portion 23 on one main surface 9 ′ of the semiconductor chip 1 ′, the directivity of light emission to the outside becomes wide, and the directivity A wide variety of semiconductor elements can be provided. Further, when the directivity is widened, the light intensity in the vicinity of the semiconductor chip 1 ′, that is, the light flux density is reduced. Therefore, when a wavelength conversion material such as a phosphor is disposed in the vicinity of one main surface 9 ′ of the semiconductor chip 1 ′. Therefore, it is possible to prevent the wavelength conversion material from being deteriorated.
(9) Increasing the effective surface area of the semiconductor chip 1 ′ by forming the first concave portion 17, the second concave portion 22, and the convex portion 23 on one main surface 9 ′ of the semiconductor chip 1 ′. Can do. Thereby, the contact area of the electrode 27 with respect to the semiconductor chip 1 ′ is increased, and the adhesion and bonding properties of the electrode 27 with respect to the semiconductor chip 1 ′ are improved. At the same time, the adhesion and bonding of the electrode 27 to the semiconductor chip 1 ′ based on the anchor effect by the first recess 17 and the second recess 22 are also improved. The effect of improving the adhesion and bondability is also effective when a light-transmitting conductive film such as ITO is provided on the main surface of the semiconductor wafer 1 or the semiconductor chip 1 ′ having the first recess 17 and the second recess 22. Can be obtained. Further, the effect of improving the adhesion and bonding can be obtained even when a passivation film is provided on the main surface of the semiconductor wafer 1 or the semiconductor chip 1 ′ having the first recess 17 and the second recess 22. It is done.
(10) In this embodiment, the second recess 22 is not formed on the inclined side surface 42 of the first recess 17. If comprised in this way, the ratio which the light radiate | emitted from the inclined side surface 42 returns in semiconductor chip 1 'can be reduced, and the light extraction efficiency improvement effect becomes large.
Next, a method for manufacturing the semiconductor light emitting device of Example 2 shown in FIG. 14 will be described. However, in FIG. 14 and FIGS. 15 to 18 described later, substantially the same parts as in FIGS. 1 to 13 are denoted by the same reference numerals, and the description thereof is omitted.
The method for roughening the semiconductor light emitting device wafer of Example 2 shown in FIG. 14 differs from the method of manufacturing the semiconductor light emitting device of Example 1 only in the method of forming the first recesses 17. In the method for manufacturing the semiconductor light emitting device of Example 2 shown in FIG. 14, after forming a resist film 11 on one main surface 9 of the semiconductor wafer 1 as shown in FIG. 14A, a known photolithography process is performed. An opening 14 ′ shown in FIG. 14B is formed. Instead of forming the opening 14 ', the resist film 11 can be left at the bottom of the opening 14' as shown by a chain line 15a in FIG. 14B, and a recess can be formed instead of the opening 14 '. The remaining portion indicated by the chain line 15a is removed in the next dry etching step.
Next, the semiconductor wafer 1 is selectively dry-etched using the resist film 11 ′ having the openings 14 ′ as a mask to form the first recesses 17 arranged at the first average pitch P 1. Next, the resist film 11 ′ shown in FIG. 14B is removed. Note that when the semiconductor wafer 1 is dry-etched, the resist film 11 ′ is also dry-etched. If the resist film 11 ′ disappears during dry etching of the semiconductor wafer 1, a special process for removing the resist film 11 ′ becomes unnecessary.
Next, on the one main surface 9 of the semiconductor wafer 1, the same method as the method for forming the second concave portion 22 and the convex portion 23 in the first embodiment, that is, a mask made of silver which is a metal material having an aggregating property. The second concave portions 22 and the convex portions 23 arranged at the second average pitch P2 are formed by a method using the granular material 21 based on the aggregation of the forming metal film 20 as a mask.
The method of Example 2 shown in FIG. 14 is the same as the method of manufacturing the semiconductor light emitting element of Example 1 except for the method of forming the first recess 17, and therefore the effects (2) to (6) of Example 1 The same effect can be obtained.
In the method of manufacturing the semiconductor light emitting device of Example 3 shown in FIG. 15, the order of the formation process of the first recess 17 and the formation process of the second recess 22 and the protrusion 23 is reversed from that of Example 1. Except for the point, it is substantially the same as Example 1. That is, in the third embodiment, first, the same material as the mask forming metal film 20 of FIG. 8 is formed on one main surface 9 of the semiconductor wafer 1, and heat treatment is performed in the same manner as in the first embodiment, and FIG. ), A granular material (aggregate) 21 made of Ag is formed. Next, the semiconductor wafer 1 is selectively etched using the granular material (aggregate) 21 as a mask, so that a fine pitch, that is, a first pitch is formed on one main surface 9 of the semiconductor wafer 1 as shown in FIG. The formation of the second concave portion 22 and the convex portion 23 arranged at an average pitch P2 of 2 is formed. Next, the granular material (aggregate) 21 is removed to obtain what is shown in FIG. Next, as shown in FIG. 15D, a resist film 11 is formed on one main surface 9 of the semiconductor wafer 1 having the second concave portions 22 and the convex portions 23 arranged at a minute pitch, that is, the second average pitch P2. Is formed non-selectively. Next, using the same mold 12 as that of the first embodiment, the resist film 11 is formed with a concave pitch 14 and convex portions arranged at a fine pitch, that is, a pitch larger than the second average pitch P2, that is, the first average pitch P1. The part 15 is formed as shown in FIG. Next, the semiconductor wafer 1 with the resist film 11 shown in FIG. 15 (E) is subjected to the same dry etching process as in FIG. 5 of Example 1 to remove the recesses 14 of the resist film 11, and The semiconductor wafer 1 is etched using the remaining portion 11 'of the thick convex portion 15 as a mask to form the first concave portion 17 and the convex portion 18 arranged at a large pitch, that is, the first average pitch P1. Thereafter, the remaining portion 11 ′ of the resist film 11 is removed to obtain substantially the same as that shown in FIG.
If the remaining portion 11 ′ of the resist film 11 disappears during the dry etching process of the semiconductor wafer 1, a special removal process for the remaining portion 11 ′ of the resist film 11 is not necessary. Further, instead of the method of forming the recess 14 of the resist film 11 using the mold 12, a method of forming the opening 14 'by the photolithography process shown in FIG. 14 can be employed. That is, an opening can be formed by a photolithography process as indicated by a broken line 14 'in FIG. Moreover, a recessed part can be formed instead of the opening shown with the broken line 14 '.
In FIG. 15F, the first convex portion 18 on one main surface 9 of the semiconductor wafer 1 has the second concave portion 22 and the convex portion 23 arranged at a minute pitch, that is, the second average pitch P2. 1 is obtained, but the first concave portion 17 is not the same as the second concave portion 22 and the convex portion 23 arranged at the second average pitch P2 of the first embodiment. However, the second concave portions 22 and the convex portions 23 arranged at the minute pitch, that is, the second average pitch P2 in the first convex portion 18 of the one main surface 9 of the semiconductor wafer 1 are totally reflected as in the first embodiment. It functions as a rough surface for prevention, and unevenness having a depth and height smaller than that corresponding to the second concave portion 22 and the convex portion 23 in FIG. Therefore, this also functions as a rough surface for preventing total reflection.
The manufacturing method of the semiconductor light emitting device of Example 3 shown in FIG. 15 is the same as that of Example 1 except that the first concave portion 17 is formed after the second concave portion 22 and the convex portion 23 are formed. Since the manufacturing method is the same, the same effect as in the first embodiment can be obtained.
The manufacturing method of the semiconductor light emitting device of Example 4 shown in FIG. 16 is different from Example 1 in that the granular material (aggregate) 21 is formed prior to the resist film 11, but the first concave portion 17 and the convex portion. 18 and the second concave portion 22 and the convex portion 23 are formed in substantially the same manner as in the first embodiment. That is, in Example 4, first, the same metal film 20 for mask formation as shown in FIG. 8 is formed on one main surface 9 of the semiconductor wafer 1, and heat treatment is performed in the same manner as in Example 1 to perform FIG. ) To form Ag granules (aggregates) 21. Next, as shown in FIG. 16B, a resist film 11 is formed on one main surface 9 of the semiconductor wafer 1 having a granular material (aggregate) 21. Next, by using the same mold 12 as that of the first embodiment, the concave portions 14 arranged in the resist film 11 with a fine pitch, that is, a pitch larger than the second average pitch P2, that is, the first average pitch P1, are illustrated. It is formed as shown in FIG. Instead of the method for forming the recess 14 of the resist film 11 using the mold 12, a method for forming the opening 14 'by the photolithography process shown in FIG. 14 can be adopted. That is, an opening can be formed by a photolithography process as indicated by a broken line 14 'in FIG. In addition, a recess can be formed in the resist film 11 instead of the opening indicated by the broken line 14 '.
Next, an etching process is performed on the one shown in FIG. 16C to remove the granular material (aggregate) 21 below the recess 14 of the resist film 11 as shown in FIG. Further, as shown in FIG. 16D, the first concave portion 17 and the convex portion arranged at a large pitch, that is, the first average pitch P1 by etching the semiconductor wafer 1 using the remaining portion 11 ′ of the resist film 11 as a mask. 18 is formed. Next, the remaining portion 11 ′ of the resist film 11 is removed, and a granular material (aggregate) 21 is formed on the surface of the first convex portion 18 of one main surface 9 of the semiconductor wafer 1 as shown in FIG. Get what is arranged. If the remaining portion 11 ′ of the resist film 11 disappears during the dry etching process of the semiconductor wafer 1, a special removal process for the remaining portion 11 ′ of the resist film 11 is not necessary.
Next, the semiconductor wafer 1 is dry-etched using the granular material (aggregate) 21 as a mask, and a fine pitch, that is, a second pitch is formed on one main surface 9 of the semiconductor wafer 1 as shown in FIG. The second concave portion 22 and the convex portion 23 arranged at the average pitch P2 are formed. Thereafter, the granular material (aggregate) 21 is removed. However, when the granular material (aggregate) 21 disappears during dry etching of the semiconductor wafer 1, a special removal step of the granular material (aggregate) 21 is not necessary.
The second concave portion 22 and the convex portion 23 are the same as those of the first embodiment on the first convex portion 18 of one main surface 9 of the semiconductor wafer 1 from which the granular material (aggregate) 21 shown in FIG. The first concave portion 17 is the same as the second concave portion 22 and the convex portion 23 arranged at the second average pitch P2 in the first embodiment. Things are not arranged. However, the second concave portions 22 and the convex portions 23 arranged at the minute pitch, that is, the second average pitch P2 in the first convex portion 18 of the one main surface 9 of the semiconductor wafer 1 are totally reflected as in the first embodiment. It functions as a rough surface for prevention, and a slight unevenness is generated on the bottom surface of the first concave portion 17 due to the granular material (aggregate) 21 shown in FIG. It functions as a rough surface.
The manufacturing method of the semiconductor light emitting device of Example 4 shown in FIG. 16 is the same as the manufacturing method of the semiconductor light emitting device of Example 1 except that the first concave portion 17 is formed after the granular material (aggregate) 21 is formed. Since they are the same, the same effect as in the first embodiment can be obtained.
A large number of first protrusions 18a are formed in an island shape on one main surface 9 of the semiconductor wafer 1 of Example 5 shown in FIG. 17, and have a lattice pattern surrounding each first protrusion 18a. A first recess 17a is provided. That is, the unevenness of one main surface 9 of the semiconductor wafer 1 of Example 5 shown in FIG. 17 is the first average pitch P1 on one main surface 9 of the semiconductor wafer 1 of Examples 1 to 4 shown in FIG. It corresponds to a structure in which a large number of first convex portions 18a are provided instead of the large number of first concave portions 17 arranged at the first average pitch P1. As shown in FIG. 17, even if the first concave portion 17a has a lattice pattern, a part of the first concave portion 17a is disposed between the first convex portions 18a. A sectional view passing through the first convex portion 18a is substantially the same as FIG. 6 in the first embodiment. Accordingly, the portion of the first concave portion 17a between the first convex portions 18a is arranged at the first average pitch P1, and the first convex portions 18a are also arranged at the first average pitch P1.
The deformed first concave portion 17a and the first convex portion 18a shown in FIG. 17 are the first concave portion 17 and the first convex portion in the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment. 18 can be formed instead. Even with the deformed first concave portion 17a and first convex portion 18a shown in FIG. 17, the same effects as those of the respective embodiments can be obtained.
A large number of first concave portions 17b and first convex portions 18b are formed in stripes on one main surface 9 of the semiconductor wafer 1 of Example 6 shown in FIG. That is, the first concave portion 17b and the first convex portion 18b on one main surface 9 of the semiconductor wafer 1 of the sixth embodiment shown in FIG. 18 are one of the semiconductor wafers 1 of the first to fourth embodiments shown in FIG. This corresponds to a large number of first concave portions 17 and first convex portions 18 in the main surface 9. As shown in FIG. 18, even when the first recess 17b has a stripe pattern, the cross-sectional view of FIG. 18 is substantially the same as FIG.
The deformed first concave portion 17b and the first convex portion 18b shown in FIG. 18 are the first concave portion 17 and the first convex portion in the first embodiment, the second embodiment, the third embodiment, or the fourth embodiment. 18 can be formed instead. Even with the deformed first concave portion 17b and first convex portion 18b shown in FIG. 18, the same effects as those of the respective embodiments can be obtained.
(1) The light emitting semiconductor region 4 of the semiconductor wafer 1 can be made of another material such as AlGaInP, AlGaAS, and GaP.
(2) A light-transmitting conductive film 30 made of, for example, ITO indicated by a chain line in FIG. 1 is provided on the light-emitting semiconductor region 4, and the first recesses 17, 17 a, 17 b and the first recesses are formed on the surface of the light-transmitting conductive film 30. The present invention can also be applied to the formation of rough surfaces such as the convex portions 18, 18a, 18b, the second concave portion 22 and the first convex portion 23.
(3) The first recesses 17, 17a, 17b and the second recess 22 can be formed by well-known wet etching.
(4) A plurality of first concave portions or convex portions arranged at a first average pitch on a light extraction surface of the light emitting semiconductor region, and a second smaller than the first average pitch. In order to obtain a semiconductor light emitting device in which a plurality of second recesses or projections arranged at an average pitch of 1 is obtained, the main surface having a plurality of projections 13 of the mold (molding die) 12 of FIG. A plurality of second concave portions or convex portions arranged at the second average pitch are provided in advance, and the first concave portion or convex portions are formed on the resist film 11 using the deformed mold (molding die). Then, the semiconductor wafer 1 can be etched through the resist film having the irregularities to form the irregularities corresponding to the irregularities shown in FIG. According to this method, a 1st recessed part or convex part and a 2nd recessed part or convex part can be formed in the same process, and a manufacturing process is simplified. In addition, in order to form unevenness corresponding to the second concave portion or convex portion on the mold (molding die), the same metal film 20 for mask formation of Example 1 was formed on the mold, and this A plurality of granular bodies (aggregates) are formed by heat-treating, and by using this as a mask, irregularities corresponding to the second concave portions or convex portions can be formed in the mold (molding die). it can.
It is sectional drawing which shows a part of semiconductor wafer for manufacturing the semiconductor light-emitting device according to Example 1 of this invention. FIG. 2 is a cross-sectional view of a semiconductor wafer having a resist film formed on the main surface of the semiconductor wafer of FIG. 1. FIG. 3 is a plan view showing a mold according to the first embodiment. It is sectional drawing which shows what formed the recessed part with the metal mold | die in the resist film of FIG. It is sectional drawing which shows the state which etched the resist film and semiconductor wafer which have a recessed part of FIG. FIG. 6 is a cross-sectional view showing a part of the semiconductor wafer after the remaining resist film in FIG. 5 is removed. FIG. 7 is a plan view of the semiconductor wafer of FIG. 6. It is sectional drawing which shows what formed the metal film for mask formation in the main surface of the semiconductor wafer of FIG. It is sectional drawing which shows what formed the granule by heat-processing the metal film for mask formation of FIG. It is sectional drawing which shows the state which etched the semiconductor wafer using the granular material of FIG. 9 as a mask. It is sectional drawing which shows the semiconductor wafer after removing the granular material of FIG. FIG. 12 is a plan view schematically showing a partial surface of FIG. 11 in an enlarged manner. It is sectional drawing of the semiconductor light-emitting device made based on the semiconductor wafer of FIG. It is sectional drawing which shows a semiconductor wafer for manufacturing a semiconductor light-emitting device according to Example 2 of this invention, and a part of resist film in order of a process. It is sectional drawing which shows the change of the semiconductor wafer for manufacturing a semiconductor light-emitting device according to Example 3 of this invention, a granular material, and a resist film in order of a process. It is sectional drawing which shows the change of the semiconductor wafer for manufacturing a semiconductor light-emitting device according to Example 4 of this invention, a granular material, and a resist film in order of a process. It is a top view which shows the semiconductor wafer for manufacturing a semiconductor light-emitting device according to Example 5 of this invention in the state which formed the 1st recessed part and the convex part. It is a top view which shows the semiconductor wafer for manufacturing a semiconductor light-emitting device according to Example 6 of this invention in the state which formed the 1st recessed part and the convex part.
DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 9 One main surface 17 1st recessed part 20 Metal film 21 for mask formation Granule 22 2nd recessed part
After or during the step of forming a large number of the second concave portions and the second convex portions arranged at the second average pitch on the surface of the wafer, the large number of granules on the wafer The method for roughening a wafer for a semiconductor light emitting device, comprising the step of removing.
2. The method of roughening a wafer for a semiconductor light emitting device according to claim 1, wherein the etching treatment of the resist film is dry etching, and the etching using the granular material as a mask is also dry etching.
A step wherein the resist film by selectively removing a to obtain a large number of apertures or concave portion on the resist film disposed at a first average pitch,
Etching the wafer using the resist film having the opening or recess as a mask, a step of obtaining a plurality of first recesses arranged in a first average pitch on the surface of the wafer,
Removing the resist film after or during the step of forming a large number of the first recesses arranged at a first average pitch on the surface of the wafer;
A property of aggregating the first concave portion and the first convex portion adjacent to the first concave portion via an inclined side surface on the surface of the wafer repeatedly arranged at a first average pitch. And forming a metal film made of a metal material having a property of functioning as a mask when the wafer is etched, and
A plurality of heat treatments at a temperature capable of agglomeration are performed on the metal film simultaneously with or after the formation of the metal film, and the metal film is arranged at a second average pitch smaller than the first average pitch. A step of changing the granular material to the first concave portion and the first convex portion, but not arranging the granular material on the inclined side surface ;
A plurality of second recesses arranged on the surface of the wafer at the second average pitch by etching a region of the wafer not covered with the plurality of granules using the plurality of granules as a mask. And obtaining a rough surface having a second protrusion ,
After or during the step of forming a large number of second concave portions and the second convex portions arranged at the second average pitch on the surface of the wafer, the large number of granules on the wafer are removed. And a step of roughening the wafer for a semiconductor light emitting device.
A plurality of first recesses arranged at a first average pitch on the surface of a wafer having a light emitting semiconductor region and the first recesses adjacent to the first recesses through inclined side surfaces of the first recesses . have a convex portion, and said first recess and said first plurality of second recesses arranged in a small second average pitch than the first average pitch protrusions and second protrusions And a method for obtaining a surface in which the second concave portion and the second convex portion are not formed on the inclined side surface ,
Forming on the surface of the wafer a metal film made of a metal material having a property of aggregating and functioning as a mask when etching the wafer;
Applying a heat treatment at a temperature capable of agglomeration to the metal film simultaneously with or after the formation of the metal film to change the metal film into a plurality of granular materials arranged at the second average pitch; ,
A plurality of the second particles arranged at the second average pitch on the surface of the wafer by etching a region of the wafer not covered with the plurality of particles using the plurality of particles as a mask . Obtaining a concave portion and the second convex portion ;
The plurality of granules on the wafer after or during the step of forming a number of the second concave portions and the second convex portions arranged at the second average pitch on the surface of the wafer. And a step of forming a resist film on the surface of the wafer having a large number of the second concave portions and the second convex portions arranged at the second average pitch,
Forming a plurality of recesses or protrusions or openings arranged at the first average pitch in the resist film;
The wafer is etched using the resist film having the recesses, projections, or openings as a mask to obtain a large number of the first recesses and the first projections arranged at the first average pitch on the surface of the wafer. Process,
Removing the resist film after or during the step of forming a number of the first concave portions and the first convex portions arranged at the first average pitch on the surface of the wafer. A method for roughening a wafer for a semiconductor light emitting device, comprising:
Forming a metal film made of a metal material having a property of aggregating on the surface of the wafer and functioning as a mask when the wafer is etched;
Performing a heat treatment at a temperature capable of agglomerating at the same time as or after the formation of the metal film to change the metal film into a large number of granules having the second average pitch;
Forming a resist film on the surface of the wafer having the multiple granular materials;
Removing the resist film after or during the step of forming a plurality of the first concave portions and the first convex portions arranged at the first average pitch on the surface of the wafer; and remaining on the wafer Etching the wafer using the granular material as a mask to form a plurality of the second concave portions and the second convex portions having the second average pitch;
A step of removing the granular material after or during the step of forming a plurality of the second concave portions and the second convex portions having the second average pitch. A method for roughening a wafer for a semiconductor light emitting device.
On the light extraction surface of the light emitting semiconductor region, the first concave portion and the first convex portion adjacent to the first concave portion via the inclined side surface of the first concave portion are repeated at the first average pitch. A plurality of second concave portions and second convex portions provided at a second average pitch smaller than the first average pitch on the first concave portion and the first convex portion, and the inclined side surface Are not provided with the second concave portion and the second convex portion , the first average pitch is set to 1 to 20 μm, and the second average pitch is set to 50 to 800 nm. A semiconductor light emitting device characterized by the above.
JP2007301569A 2007-11-21 2007-11-21 Wafer surface roughening method for semiconductor light emitting device and semiconductor light emitting device Active JP4993371B2 (en)
JP2007301569A JP4993371B2 (en) 2007-11-21 2007-11-21 Wafer surface roughening method for semiconductor light emitting device and semiconductor light emitting device
JP2009130027A JP2009130027A (en) 2009-06-11
JP4993371B2 true JP4993371B2 (en) 2012-08-08
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JP2007301569A Active JP4993371B2 (en) 2007-11-21 2007-11-21 Wafer surface roughening method for semiconductor light emitting device and semiconductor light emitting device
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