JP3753965B2 - Method of manufacturing gallium nitride compound semiconductor light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
    The present inventionNitroThe present invention relates to a method for manufacturing a gallium phosphide-based compound semiconductor light emitting device.
[0002]
[Prior art]
In recent years, blue light emitting gallium nitride compound semiconductor lasers using gallium nitride compound semiconductors such as InGaAlN have been developed. This gallium nitride-based compound semiconductor semiconductor laser is expected to be used as a light source for high-density information processing such as an optical disk because it has a short wavelength and a small beam diameter. In application to an optical disk system or the like, it is necessary to focus the laser beam to a minimum spot, and fundamental transverse mode oscillation is indispensable. As such a gallium nitride based semiconductor laser, many ridge structure lasers have been reported and sold. In the ridge structure laser, element characteristics such as oscillation threshold and transverse mode control greatly depend on the depth of the ridge and the width of the ridge. In particular, the width of the ridge portion needs to be about 2 μm or less.
[0003]
A method of manufacturing this ridge structure laser will be briefly described with reference to FIG. FIG. 12 is a schematic diagram showing the magnification of each part changed. In the ridge structure laser manufacturing method, first, a laminate 602 is formed on a substrate 601, and reactive ion etching (RIE) or reactive ion beam etching is performed on each laser portion L (i) of the laminate 602. The ridge R (i) is formed by an etching method such as (RIBE). Next, SiO 2 is deposited on the stacked pair 602 by a film formation method such as CVD or sputtering.₂A film S is formed. Next, SiO 2 is obtained by a light exposure process using the window W (i) of the glass mask 603.₂Striped openings H (i) are opened in the film S. Here, the position of the ridge R (3) and the position of the opening H (3) are made to coincide. Next, an electrode metal is evaporated from the opening H (i) to the ridge R (i). Thereafter, each laser portion L (i) on the substrate 601 is element-isolated to obtain a laser element.
[0004]
[Problems to be solved by the invention]
A conventional ridge laser is generally formed on a substrate 601 made of sapphire or silicon carbide. However, as shown in FIG. 12, the substrate 601 is greatly warped due to the difference in thermal expansion coefficient between the substrate 601 and the stacked body 602. This warp is a large warp compared to the width of the ridge R (i) of about 2 μm. For example, when a substrate 601 having a diameter of about 5 cm is placed on a horizontal plane, the height of the center portion and the end portion of the substrate 601 is The difference is several tens of μm. For this reason, the position of the ridge R (i) and the opening H (i) is shifted at the end of the substrate 601. That is, the position of the ridge R (3) and the opening H (3) coincide with each other in the laser portion L (3) at the center of the substrate 601, whereas the ridge R (1) in the laser portion L (1) at the end of the substrate 601. ) And the opening H (1) are misaligned.
[0005]
As described above, in the conventional method of manufacturing a gallium nitride compound semiconductor laser, the positions of the ridge R (i) and the opening H (i) are shifted at the end portion of the substrate 601, so The position has shifted. As a result, in the laser portion L (i) at the end of the substrate 601, the resistance increases or a leak occurs, and laser oscillation cannot be obtained. For this reason, the yield of the laser element is reduced toward the end of the substrate 601. The laser element was obtained only in an area of about 20% or less near the center of the substrate 601.
[0006]
As described above, the conventional method for manufacturing a gallium nitride compound semiconductor laser has a problem that the yield of electrode formation on the ridge R (i) is extremely poor. In addition, the problem of yield reduction due to the warpage of the substrate is also present in gallium nitride compound semiconductor light emitting devices other than gallium nitride compound semiconductor lasers and gallium nitride compound semiconductor devices.
[0007]
  The present invention has been made on the basis of recognition of the above-described problems, and its purpose is as follows.WalkIt is to provide a method for manufacturing a gallium nitride compound semiconductor light emitting device having a high yield.
[0010]
[Means for Solving the Problems]
BookA method for manufacturing a gallium nitride-based compound semiconductor light-emitting device according to the present invention is a method for manufacturing a gallium nitride-based compound semiconductor light-emitting device having a gallium nitride-based compound semiconductor layer having an end face as a light emitting surface, and a resist pattern,The side surface of the element isolation groove as the end surfaceForming a portion of the surface of the gallium nitride-based compound semiconductor layer excluding the end surface; and immersing the gallium nitride-based compound semiconductor layer in an aqueous solution in which a first dielectric is dissolved in a supersaturated state. A step of selectively depositing the dielectric film, and immersing the gallium nitride compound semiconductor layer in an aqueous solution in which the second dielectric is dissolved in a supersaturated manner to form a second dielectric film on the first dielectric. And selectively depositing, and forming a multilayer reflective film of the first dielectric film and the second dielectric film on the end face.The first or second dielectric film is made of SiO. ₂ And the second or first dielectric film is TiO. ₂ Membrane and ZrO ₂ One of the membranesIt is characterized by that.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, a method for manufacturing a gallium nitride-based compound semiconductor device according to an embodiment of the present invention will be described with reference to the drawings. One of the features of the present embodiment is that, as can be seen from FIG. 1C, SiO 2 is formed on the gallium nitride compound semiconductor layer 102 on which the resist pattern M is formed.₂In the method of forming the film S (dielectric film), by using the liquid phase growth method (LPD) originally developed by the present inventor, SiO 2 is formed on the resist pattern M.₂A SiO film is selectively formed on the gallium nitride compound semiconductor layer 102 without forming the film S and without forming the resist pattern M.₂This is the point at which the film S is formed. First of all,thisWe ’ll talk about liquid deposition,referenceExample and number1A method of manufacturing a gallium nitride-based compound semiconductor laser using this liquid phase deposition method will be described in the embodiment.
[0012]
  Figure1 (a)-(d)NitridingIt is a figure which shows the manufacturing method of a gallium type compound semiconductor element.
[0013]
(1) First, as shown in FIG. 1A, a GaN layer (gallium nitride compound semiconductor layer) 102 is grown on a sapphire substrate 101 by metal organic chemical vapor deposition (MOCVD).
[0014]
(2) Next, a positive resist is applied on the GaN layer 102, and as shown in FIG. 1B, a desired resist pattern M is formed by an optical exposure process. Thereafter, baking is performed at 105 ° C. in a nitrogen atmosphere.
[0015]
(3) Next, as shown in FIG. 1C, SiO is selectively formed on the GaN layer 102 on which the resist pattern M is not formed by the liquid phase deposition method originally developed by the present inventor.₂A film S (dielectric film) is formed. Specifically, the liquid temperature is kept at 30 ° C. and SiO 2₂H dissolved in supersaturation₂SiF₆By immersing the wafer in an aqueous solution (0.35 mol / l) and adding a slight amount of Al foil into the solution, the following chemical reaction results in SiO 2₂Film S is deposited.
[0016]
H₂SiF₆+ 2H₂O = SiO₂+ 6HF (1)
6HF + Al = AlF₆+ 3H₂   (2)
At this time, SiO₂The film S does not deposit on the resist pattern M, but only on the GaN layer 102. Here, Al advances the reaction in the formula (1) to the right side, and SiO 2₂It serves to facilitate the deposition of the film S. SiO under these deposition conditions₂The deposition rate of the film S is 0.1 μm / hr.
[0017]
(4) Next, the resist pattern M is removed, and as shown in FIG.₂A predetermined pattern of openings H is obtained in the film S. This opening H can be used for electrode formation or the like.
[0018]
  As explained aboveNitridingThe manufacturing method of a gallium compound semiconductor device can be grasped as follows. That is, a step of forming a resist pattern M on the gallium nitride-based compound semiconductor layer 102 (FIG. 1B), SiO 2₂H in which (dielectric) is dissolved in supersaturation₂SiF₆The gallium nitride compound semiconductor layer 102 is immersed in an aqueous solution to remove SiO 2 on the gallium nitride compound semiconductor layer 102 except for a portion where the resist pattern M is formed.₂And a step of selectively depositing the film S (dielectric film) (FIG. 1C).
[0019]
In the manufacturing method of the gallium nitride compound semiconductor device of FIG. 1 described above, by using the liquid phase deposition method, SiO 2 is selectively formed on the GaN layer 102 as shown in FIG.₂A film S can be formed. As a result, the opening H can be formed at the designed location without displacement, and the electrodes and the like can be formed without displacement.
[0020]
However, in the conventional method of manufacturing a gallium nitride compound semiconductor device, SiO₂The selective deposition of film S has been considered extremely difficult. For this reason, a manufacturing process has been designed on the assumption that such selective deposition cannot be performed. Conventionally, selective deposition using the above-described liquid phase deposition method has received little attention. As one of the causes, the present inventor has made SiO 2 by a liquid deposition method.₂The selective deposition of the film S is sensitive to the deposition conditions and is believed to be difficult for a normal engineer to achieve. However, the present inventor has found that the above-described selective deposition can be performed under the following conditions by continuous research and development.
[0021]
First, SiO₂In order to selectively form the film S, it has been found that the baking temperature after the formation of the resist pattern M should be less than 150 ° C. In the manufacturing method of FIG. 1, the baking temperature after forming the resist pattern M is set to 105 ° C. However, according to the experiment of the present inventors, when the baking temperature is set to 150 ° C. or higher, the resist pattern M is altered and the resist SiO on the pattern M₂Film S was deposited. And this makes SiO₂The selectivity of the membrane S has been lost.
[0022]
Here, in the manufacturing method of FIG. 1, after the step of FIG. 1B, dry etching using a chlorine-based gas is performed using the resist pattern M as a mask, and the resist pattern M is used as it is as a mask for selective deposition. It can also be used. Also in this case, it was found that selectivity was not lost by suppressing the wafer temperature during etching to 150 ° C. or lower.
[0023]
Next, in the manufacturing method of FIG. 1, it was found that the deposition rate changes depending on the concentration of the solution and the temperature of the solution. When the deposition rate is 0.5 μm / h or more, SiO generated by uniform nucleation in the solution is obtained.₂Film S adheres on the wafer and SiO₂It has been found that the morphology of the membrane S is significantly degraded. In addition, SiO₂It has been found that the film S is deposited on the resist pattern and the selectivity is lost. As a result of further experiments, the present inventor has found that SiO₂To selectively form the film S, SiO₂It has been found that the deposition rate of the film S is desirably 0.2 μm / h or less.
[0024]
The inventor further conducted detailed studies to obtain such a deposition rate. As a result, H₂SiF₆It has been found that the concentration of the aqueous solution should be 0.3 mol / l or more and 0.7 mol / l or less, desirably 0.3 mol / l or more and 0.5 mol / l or less. Furthermore, it has been found that the deposition temperature is preferably 40 ° C. or lower.
[0025]
As described above, SiO on the gallium nitride based semiconductor 102 according to the present invention.₂The selective deposition of the film S is not easily achieved by being influenced by the deposition conditions, but has been found by continuous research and development.
[0026]
  In the method of manufacturing the nitride gallium compound semiconductor device of FIG. 1 described above, the dielectric film S is made of SiO.₂A film was used but TiO₂Membrane and ZrO₂A membrane can also be used. SiO₂When using a film, as an aqueous solution used in the liquid layer deposition method,KayHydrofluoric acid H₂SiF₆In addition to aqueous solution, ammonium silicofluoride (NH₄)₂SiF₆Aqueous solution, potassium silicofluoride K₂SiF₆Aqueous solution, sodium silicate Na₂SiO₃Aqueous solution, sodium silicofluoride Na₂SiF₆An aqueous solution or the like can be used. TiO₂When using a film, ammonium hexafluorotitanate (NH) is used as an aqueous solution used in the liquid layer deposition method.₄)₂TiF₆Aqueous solution, potassium titanium fluoride K₂TiF₆Aqueous solution, sodium hexafluorotitanate Na₂TiF₆An aqueous solution or the like can be used. ZrO₂When a film is used, potassium zirconium fluoride K is used as the aqueous solution used in the liquid layer deposition method.₂ZrF₆An aqueous solution can be used.
[0027]
  NextNext, a method for manufacturing a gallium nitride-based compound semiconductor light-emitting device using the liquid phase deposition method will be described with reference to the drawings. First,referenceThe example describes a method for forming an electrode of a gallium nitride semiconductor laser electrode without misalignment.1In this embodiment, a method of selectively forming a highly reflective coating film on the end face of a gallium nitride based semiconductor laser will be described.
[0028]
  (referenceExample)
  FIG.referenceIt is a schematic sectional drawing of the gallium nitride type compound semiconductor laser concerning an example. Gallium nitride compound semiconductor layers 202 to 210 are formed on the sapphire substrate 201. That is, on the substrate 201, a GaN buffer layer 202, an n-GaN contact layer 203, an n-GaAlN cladding layer 204, an n-GaN waveguide layer 205, an InGaN multiple quantum well (MQW) active layer 206, an n-GaAlN overflow. The prevention layer 207, the p-GaN waveguide layer 208, the p-GaAlN cladding layer 209, and the p-GaN contact layer 210 are sequentially stacked. A part of the p-GaN contact layer 210 and the p-GaAlN clad layer 209 is removed by etching to the middle of the p-GaAlN clad layer 210 as shown in FIG. 2 to form a striped ridge R. On the upper surface of the laser shown in FIG.₂A film S is formed. And the SiO above the ridge R₂An opening is formed in the film S. As described below, the bookReference exampleThen this SiO₂The opening of the film S is formed by using liquid phase deposition (LPD). The p-side electrode 230 that is one side electrode is deposited so as to be in contact with the p-GaN contact layer 210 using this opening. Further, the n-side electrode 220 which is the other side electrode is deposited on the n-GaN contact layer 203 exposed by partially removing the p-GaN contact layer 210 to the n-GaAlN cladding layer 204.
[0029]
Next, a method for manufacturing the gallium nitride compound semiconductor laser shown in FIG. 2 will be described with reference to FIGS.
[0030]
FIG. 3 is a conceptual perspective view for explaining a manufacturing method of the gallium nitride compound semiconductor laser of FIG. As can be seen from FIG. 3, the laser of FIG. 2 is obtained by element isolation of a wafer on which a plurality of laser portions L (i) are formed on a substrate 201. Here, in FIG. 3, the 202-205 layer of FIG. 2 is shown as 200n, and the 207-210 layer of FIG. 2 is shown as 200p. FIG. 3 shows a diameter of about 5 × 10⁴FIG. 6 is a conceptual diagram showing a part of a μm circular substrate 201, and the width of each laser portion L (i) is about 5 × 10.²μm.
[0031]
  BookreferenceOne of the features of the example is the aforementioned SiO₂Using the selective growth method of the film,₂This is the point that the opening of the film S is formed without displacement. As a result, SiO₂Misalignment between the p-side electrode 230 formed in the opening of the film S and the ridge R is eliminated. Hereinafter, the manufacturing method of the laser portion L (i) of FIG. 3 will be described in detail with reference to the conceptual cross-sectional views of FIGS. 4 to 9 in which each laser portion L (i) is enlarged.
[0032]
(1) First, as shown in FIG. 4, a gallium nitride compound semiconductor layer 200 (200n, 206, 200p) is formed on a sapphire substrate 201 by metal organic chemical vapor deposition (MOCVD). That is, on the substrate 201, a buffer layer 202 having a thickness of 10 to 200 nm, an n-GaN contact layer 203 having a thickness of 4 μm, an n-GaAlN cladding layer 204 having a thickness of 0.6 μm, and an n-GaN having a thickness of 0.1 μm. Light guide layer 205, In_{0 . 25}Ga_{0 . 75}N well layer / In_{0 . 05}Ga_{0 . 95}A multi-quantum well active layer 206 made of an N barrier layer, a carrier overflow prevention layer 207 made of p-GaAlN, a p-GaN light guide layer 208 having a thickness of 0.1 μm, and a p-GaAlN cladding layer 209 having a thickness of 0.6 μm. Then, a p-GaN contact layer 210 having a thickness of 0.1 μm is sequentially formed. Thereafter, the wafer is removed from the growth apparatus.
[0033]
(2) Next, a positive resist is applied on the p-GaN contact layer 210, and as shown in FIG. 5, a stripe-shaped resist pattern M having a width of 2 μm is formed by an optical exposure process. Then, baking is performed at 105 ° C. for 10 minutes in a nitrogen atmosphere.
[0034]
(3) Next, as shown in FIG. 6, using the resist pattern M as a mask, the p-GaN contact layer 210 and the p-GaAlN cladding layer 209 are dry-etched to a depth of 0.5 μm to form a ridge R. . Specifically, a wafer is set in an inductively coupled reactive ion etching (ICP-RIE) apparatus, chlorine gas is used as an etching gas, RF power for plasma generation is 500 W, and RF power for substrate bias is 200 W. Etching is performed. At this time, the substrate temperature is controlled to 25 ° C.
[0035]
(4) Next, as shown in FIG. 7, by using the resist pattern M used as a mask in the dry etching as it is, the above-described liquid phase deposition method is used to form SiO.₂A film S is selectively deposited. Specifically, SiO₂H saturated₂SiF₆The wafer is immersed in an aqueous solution (0.35 mol / l), and the Al foil is immersed in the solution. At this time, the temperature of the solution is kept at 30 ° C. and deposition is performed for 2 hours. In this process, SiO₂The film S is not deposited on the resist pattern M, but is deposited only on the side wall of the ridge R and the bottom of the ridge R that are not covered with the resist pattern M. SiO₂The thickness of the film S is 200 nm.
[0036]
  (5) Next, as shown in FIG. 8, the resist pattern M is removed and SiO 2 is removed.₂An opening H for electrode formation is formed in the film S. BookReference exampleIn this manufacturing method, the position of the opening H coincides with the position of the ridge R with extremely high accuracy.
[0037]
(6) Next, as shown in FIG. 9, etching for forming the n-side electrode 204 is performed. Specifically, first, a resist is applied on the laminate of FIG. 8, and as can be seen from FIG. 9, a resist pattern M ′ is formed by an optical exposure process. Then, baking is performed at 105 ° C. in a nitrogen atmosphere. Next, a portion of SiO not covered with the resist pattern M ′ is etched by wet etching using ammonium fluoride.₂After the film S is removed by etching, the wafer is set again in an inductively coupled reactive ion etching (ICP-RIE) apparatus. Next, using the resist pattern M ′ as a mask and chlorine gas as an etching gas, under the conditions of RF power for plasma generation of 500 W and RF power for substrate bias of 200 W, as shown in FIG. Etch away partially until exposed.
[0038]
(7) Next, the resist pattern M ′ is removed, and an n-side electrode 220 and a p-side electrode 230 are formed by a lift-off process. Thereby, the laser portion L (i) of FIG. 3 is formed. Then, the laser portion L (i) in FIG. 3 is element-isolated to obtain the laser in FIG.
[0039]
  The book explained abovereferenceThe manufacturing method of the example gallium nitride compound semiconductor laser can be grasped as follows. That is, a step of forming a striped resist pattern M on the gallium nitride-based compound semiconductor layer 200 (FIG. 5), a step of forming a ridge R by dry etching using the resist pattern M as a mask (FIG. 6), SiO 2₂H in which (dielectric) is dissolved in supersaturation₂SiF₆The gallium nitride-based compound semiconductor layer 200 is immersed in an aqueous solution, and a portion of the gallium nitride-based compound semiconductor layer 200 is formed on the gallium nitride-based compound semiconductor layer 200 except for a portion where the resist pattern M is formed.₂A step of selectively depositing a film S (dielectric film) (FIG. 7), and removing the resist pattern M to form the SiO₂It can be grasped as comprising the step of forming an opening H in the portion of the film S on the ridge R (FIG. 8) and the step of depositing the electrode 230 on the ridge R through the opening H.
[0040]
  Explained abovereferenceIn the manufacturing method of the example gallium nitride compound semiconductor laser, the liquid phase deposition method is used, and SiO₂A film S can be deposited (FIG. 7). As a result, the position of the resist pattern M used for forming the ridge R (FIG. 6) is directly changed to SiO 2.₂The position of the opening H (FIG. 8) of the film S can be set. The opening H can be used for forming the p-side electrode 230. That is, the formation of the ridge R and the formation of the opening H can be performed by self-alignment using the resist pattern M. As a result, SiO₂The position of the opening H of the film S coincides with the position of the ridge R with extremely high accuracy. As a result, the position of the ridge R and the position of the p-side electrode 230 coincide with each other with extremely high accuracy, and the p-side electrode 230 can be formed with an extremely high yield.
[0041]
  On the other hand, in the conventional manufacturing method, SiO₂It was thought that selective deposition of film S was not possible. For this reason, in the conventional manufacturing method, first, after forming the ridge R in the step of FIG. 6, the resist pattern M is removed, and then the entire surface of the stacked body is made of SiO.₂A film S is formed, and then this SiO₂An opening H was formed in the film S (FIG. 12). However, in this method, the yield is lowered because the position of the opening H and the position of the ridge R occur at the edge of the substrate. BookReference exampleEven in this manufacturing method, the substrate 201 is warped, but since there is no deviation between the position of the ridge R and the position of the opening H, the yield reduction due to the warp of the substrate 201 is very small.
[0042]
  As above, the bookReference exampleIn this gallium nitride compound semiconductor laser manufacturing method, SiO₂Since the selective deposition of the film S is possible, the position of the ridge R and the position of the opening H coincide with each other regardless of whether the substrate 201 is warped, and the p-side electrode 230 can be formed with a very high yield.
[0043]
  Explained abovereferenceIn the manufacturing method of the example nitride gallium compound semiconductor laser, the dielectric film S is made of SiO.₂A film was used but TiO₂Membrane and ZrO₂A membrane can also be used. In each of these cases,Manufacturing method of FIG.An appropriate aqueous solution described in the above can be used.
[0044]
  (First embodiment)
  First1In this embodiment, a method of forming a highly reflective coating film on the end face of a gallium nitride compound semiconductor laser by a liquid phase deposition method will be described with reference to FIGS. The process up to the formation of the highly reflective coating film (FIG. 3)referenceSimilar to the example.
[0045]
  FIG.1It is a conceptual perspective view which shows the manufacturing method of the gallium nitride type compound semiconductor laser of the Example of. FIG. 10 is a conceptual diagram showing a part of a circular substrate 201 having a diameter of about 5 × 104 μm, as in FIG. 3, and the width of each laser portion L (i) is about 5 × 102 μm. FIG. 11 is a cross-sectional view taken along a dotted line AA ′ in FIG.
[0046]
(1) First, a positive resist is applied on the wafer of FIG. 3, and a resist pattern M is formed by an optical exposure process as can be seen from FIG. As can be seen from FIG. 10, this resist pattern M has stripe-shaped grooves for forming element isolation grooves 402 in a direction perpendicular to the ridge stripe. Thereafter, baking is performed at 105 ° C. in a nitrogen atmosphere. Next, SiO exposed in the grooves of the resist pattern M₂The film S is removed by etching with an ammonium fluoride solution. Further, etching is performed to form an element isolation groove 402 as shown in FIG. Specifically, a wafer is set in an inductively coupled reactive ion etching (ICP-RIE) apparatus, chlorine gas is used as an etching gas, RF power for plasma generation is 500 W, and RF power for substrate bias is 200 W. Then, etching is performed until the sapphire substrate 201 is exposed, and the element isolation trench 402 is formed. The surface exposed to the element isolation groove 402 is a laser emission end surface 501 shown in FIG.
[0047]
(2) Next, the wafer of FIG.₂H saturated₂SiF₆Immerse in an aqueous solution (0.35 mol / l) and add Al foil into this solution. At this time, the temperature of the solution is maintained at 30 ° C. In this step, as can be seen from FIG.₂A film S ′ is deposited on the laser end surface 501 and the sapphire surface 201 not covered with the resist pattern M. SiO₂The deposited film thickness of the film S ′ is set so that the optical film thickness at the laser end surface 501 is ¼ wavelength. Next, the wafer was subjected to 0.5 mol / l ammonium hexafluorotitanate (NH₄)₂TiF₆Of 0.5 mol / l H at the same time₃BO₃And add pure water. As a result, SiO deposited on the laser end face 501 and sapphire 201.₂On the film S ', TiO₂A film T is deposited. By repeating this process, SiO₂Film S 'and TiO₂A highly reflective coating film 502 in which the films T are alternately laminated twice is deposited.
[0048]
(3) Next, the resist pattern M is removed as shown in FIG. Thereafter, the wafer is separated into chips to produce a semiconductor laser.
[0049]
  In addition, the first explained above1The manufacturing method of the gallium nitride-based compound semiconductor laser of the embodiment can be grasped as follows. That is, a method of manufacturing a gallium nitride compound semiconductor light emitting device having a gallium nitride compound semiconductor layer 200 having a light exit surface as an end face 501, wherein a resist pattern M is formed on the surface of the gallium nitride compound semiconductor layer 200. Forming the portion excluding the end face 501 and SiO.₂The gallium nitride compound semiconductor layer 200 is immersed in an aqueous solution in which the (first dielectric) is supersaturated to form SiO on the end face 501.₂Selectively depositing a film (first dielectric film) S ′;₂The gallium nitride compound semiconductor layer 200 is immersed in an aqueous solution in which the (second dielectric) is supersaturated and the SiO 2 is dissolved.₂TiO on the film S '₂The step of selectively depositing a film (second dielectric film) T is alternately performed, and SiO 2 is formed on the end surface 501 where the resist pattern M is not formed.₂Film S 'and TiO₂And a step of forming the multilayer reflective film 502 with the film T.
[0050]
  No. explained above1In the manufacturing method of the gallium nitride compound semiconductor laser of the embodiment, since the high reflection coating film 502 is formed by the liquid layer deposition method, the high reflection coating film 502 can be easily formed before the wafer is separated from the device. The device yield can be increased. That is, since the substrate 201 before element isolation has a diameter of about several centimeters, it is easy to handle, and when forming a highly reflective film, there is no decrease in yield due to difficulty in wafer handling. Further, although the high reflection film 502 is a dielectric, since it is selectively deposited, there is no wraparound to the electrode portion, and there is no reduction in yield due to poor conductivity.
[0051]
On the other hand, conventionally, a highly reflective coating film has been formed by a method such as sputtering or vacuum deposition. In this case, the wafer is first cleaved in the direction perpendicular to the stripe-shaped laser portion L (i) and separated into bars (see FIG. 3). Then, a highly reflective film was deposited on each side of the cleavage plane. However, in this method, since the wafer was separated before the highly reflective film was deposited, the wafer handling was difficult and the yield was poor. Further, in this method, even if the portion of the wafer other than the cleavage plane is covered, the deposition of the vapor deposition material causes the p-side electrode 230 or the n-side electrode 220 to be SiO.₂Film S 'or TiO₂Film T has been deposited. For this reason, poor conductivity occurred, and the yield further deteriorated. Moreover, it was necessary to set a thin bar-shaped sample on a jig, and the productivity was poor.
[0052]
  In the manufacturing method of FIGS. 10 and 11 described above, TiO is used as the highly reflective coating film 502.₂/ SiO₂I explained about the membrane,Manufacturing method of FIG.By using the appropriate aqueous solution described in 1.₂/ SiO₂Other highly reflective coating films such as films can also be formed. Further, not only the high reflection coating film but also the low reflection film used for the DFB laser can be formed by adjusting the combination of the deposited films and the film thickness.
[0054]
【The invention's effect】
According to the present invention, in the method for manufacturing a gallium nitride-based compound semiconductor, the dielectric film can be selectively formed on a portion where the resist pattern is not formed by the liquid phase deposition method.HighThe formation of the reflective coating film can be carried out at the designed location without misalignment, and the yield can be increased.
[Brief description of the drawings]
[Figure 1]NitridingSectional drawing which shows the manufacturing method of a gallium type compound semiconductor element.
FIG. 2 of the present inventionreference1 is a schematic cross-sectional view of a gallium nitride compound semiconductor laser according to an example.
FIG. 3 of the present inventionreferenceThe conceptual perspective view for demonstrating the manufacturing method of the gallium nitride type compound semiconductor laser of an example.
FIG. 4 of the present inventionreferenceThe conceptual sectional view showing the manufacturing method of the example gallium nitride compound semiconductor laser.
FIG. 5 shows the present invention.referenceFIG. 5 is a conceptual cross-sectional view showing a method for manufacturing the example gallium nitride compound semiconductor laser, following FIG. 4.
FIG. 6 of the present inventionreferenceFIG. 6 is a conceptual cross-sectional view illustrating a method for manufacturing the example gallium nitride compound semiconductor laser, following FIG. 5.
[Fig. 7] of the present invention.referenceFIG. 7 is a conceptual cross-sectional view showing a method for manufacturing the example gallium nitride compound semiconductor laser, following FIG. 6.
[Fig. 8] of the present inventionreferenceFIG. 8 is a conceptual cross-sectional view showing a method for manufacturing the example gallium nitride compound semiconductor laser, following FIG. 7.
FIG. 9 shows the present invention.referenceFIG. 9 is a conceptual cross-sectional view illustrating the method for manufacturing the example gallium nitride compound semiconductor laser, following FIG. 8.
FIG. 10 shows the first of the present invention.1The conceptual perspective view which shows the manufacturing method of the gallium nitride type compound semiconductor laser of the Example of.
FIG. 11 shows the first of the present invention.1FIG. 11 is a conceptual cross-sectional view showing a method of manufacturing the gallium nitride-based compound semiconductor laser of the example of FIG.
FIG. 12 is a conceptual cross-sectional view showing a conventional method of manufacturing a gallium nitride compound semiconductor laser.
[Explanation of symbols]
102 Gallium nitride compound semiconductor layer
200 Gallium nitride compound semiconductor layer
230 p-side electrode
502 High reflective coating film (Multilayer reflective film)
S SiO2 film
S 'SiO2 film
T TiO2 film
M resist pattern
H opening
R Ridge

Claims (1)

A method of manufacturing a gallium nitride compound semiconductor light emitting device having a gallium nitride compound semiconductor layer having an end face as a light emitting surface, wherein the gallium nitride compound semiconductor layer surface has a resist pattern as a side face of the element isolation groove. And forming the first dielectric film on the end face by immersing the gallium nitride compound semiconductor layer in an aqueous solution in which the first dielectric is dissolved in a supersaturated manner. A step of depositing, a step of selectively depositing a second dielectric film on the first dielectric by immersing the gallium nitride compound semiconductor layer in an aqueous solution in which a second dielectric is dissolved in a supersaturated state, And alternately forming a multilayer reflective film of the first dielectric film and the second dielectric film on the end face , wherein the first or second dielectric film is made of SiO. _Two membranes, The method of manufacturing a gallium nitride-based compound semiconductor light emitting device, wherein the second or first dielectric film is any one of a TiO ₂ film and a ZrO ₂ film .

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