JP6269913B2 - Surface emitting laser element manufacturing method, light source device manufacturing method, optical scanning device, and image forming apparatus - Google Patents

Description

  The present invention relates to a method for manufacturing a surface-emitting laser element, a method for manufacturing a light source device, an optical scanning device, and an image forming apparatus, and more specifically, a method for manufacturing a surface-emitting laser element having a light-emitting portion. The present invention relates to a method of manufacturing a light source device having a surface emitting laser element, an optical scanning device including the light source device manufactured by the manufacturing method, and an image forming apparatus including the optical scanning device.

  Conventionally, a lower reflector, a resonator structure including an active layer, an upper reflector including a selective oxidation layer, and a contact layer are sequentially stacked on a substrate to form a stacked body, and the stacked body is etched to form a mesa. A step of forming a structure, a step of forming a protective film on the mesa structure and a peripheral region of the mesa structure, a step of forming a resist pattern on the protective film, and wet etching the protective film. A method for manufacturing a surface emitting laser including the same is known (for example, see Patent Documents 1 to 3).

  However, in the surface emitting laser manufacturing methods disclosed in Patent Documents 1 to 3, a so-called “blackening defect” occurs in the contact layer by exposing the contact layer to an etchant for wet etching (for example, BHF). However, it is difficult to eliminate the surface emitting laser in which the blackening defect has occurred as a defective product.

The present invention relates to a method of manufacturing a surface-emitting laser device having at least one light-emitting portion, and includes a lower reflector on a substrate, a resonator structure including an active layer, an upper reflector including a selective oxidation layer, and a contact layer Forming the laminate by sequentially laminating the laminate, and forming the laminate so as to form at least one mesa structure that is the at least one light emitting portion and the selective oxidation layer is exposed on a side surface. Etching, forming a protective film on the at least one mesa structure and a peripheral region of the at least one mesa structure, forming a resist pattern on the protective film, and forming the protective film Wet etching, and in the wet etching step, the protective film formed on the at least one mesa structure is partially removed, and at least One of with the emission port is formed, said protective film formed on the peripheral region is partially removed, at least one opening is formed, opening area of the opening, an opening area of the light exit opening It is a manufacturing method of the surface emitting laser element characterized by being larger than this.

  According to this, the surface emitting laser element in which the blackening defect has occurred can be excluded as a defective product.

It is a figure for demonstrating schematic structure of the laser printer which concerns on 1st Embodiment of this invention. It is the schematic which shows the optical scanning device in FIG. It is a figure for demonstrating the structure of a surface emitting laser element. It is a figure for demonstrating arrangement | positioning of a surface emitting laser element. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is sectional drawing of a laminated body. It is a figure which shows the state which formed the resist pattern on the laminated body of FIG. It is sectional drawing which shows the state which formed the light emission mesa and the mesa for a test | inspection by dry-etching the laminated body of FIG. It is sectional drawing which shows the state which oxidized the to-be-selected oxidation layer of the light emission mesa of FIG. 8, and formed the electric current passage area | region. FIG. 10 is a cross-sectional view illustrating a state where an interlayer insulating film is formed on the structure of FIG. 9. It is sectional drawing which shows the state which formed the contact hole and the opening for a test | inspection in the structure of FIG. It is a top view of the surface emitting laser element of a comparative example. FIG. 13A is a graph showing variation in drive current between the light emitting portions of the surface emitting laser element of the first embodiment, and FIG. 13B is a graph between the light emitting portions of the surface emitting laser element of the comparative example. It is a graph which shows the dispersion | variation in a drive current. It is sectional drawing of the surface emitting laser element of 2nd Embodiment. It is sectional drawing of the laminated body of 2nd Embodiment. FIG. 16 is a view showing a state in which a resist pattern for forming a mesa for inspection is formed on the photodetector of the laminated body of FIG. 15. It is sectional drawing which shows the state which wet-etched (sulfuric acid type | system | group) the structure of FIG. It is sectional drawing which shows the state which wet-etched (hydrochloric acid type) the structure of FIG. It is sectional drawing which shows the state in which the resist pattern for light emission mesa formation was formed in the structure of FIG. FIG. 20 is a diagram showing a state in which a light emitting mesa and an inspection mesa are formed by dry etching the structure of FIG. 19. It is sectional drawing which shows the state which oxidized the to-be-selected oxidation layer of the light emission mesa of FIG. 20, and formed the electric current passage area | region. It is a figure which shows the state which formed the interlayer insulation film on the structure of FIG. It is a figure which shows the state which formed the contact hole and the test | inspection opening by carrying out the wet etching of the structure of FIG. It is a graph which shows the dispersion | variation in the drive current between the light emission parts of the surface emitting laser element of 2nd Embodiment. It is a figure for demonstrating schematic structure of a color printer. It is sectional drawing of the surface emitting laser element of 3rd Embodiment. It is sectional drawing of the laminated body of 3rd Embodiment. It is a figure which shows the state which formed the resist pattern A on the dielectric material layer of the laminated body of FIG. It is the figure which looked at the pattern a and the pattern b of the resist pattern A from the + Z side. It is a figure which shows the state which wet-etched the dielectric material layer of the laminated body of FIG. FIG. 31 is a diagram showing a state in which a resist pattern B is formed on the resist pattern A on the structure of FIG. 30. FIG. 32 is a diagram showing a state in which a light emitting mesa and an inspection mesa are formed by dry etching the structure of FIG. 31. It is sectional drawing which shows the state which oxidized the to-be-selected oxidation layer of the light emission mesa of FIG. 32, and formed the electric current passage area | region. It is a figure which shows the state which formed the interlayer insulation film on the structure of FIG. It is a figure which shows the state which removed the interlayer insulation film on the contact layer of a light emission mesa and a test | inspection mesa by wet etching.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a laser printer 1000 as an image forming apparatus according to the first embodiment.

  The laser printer 1000 includes an optical scanning device 1010, a photosensitive drum 1030, a charging device 1031, a developing roller 1032, a transfer charger 1033, a charge eliminating unit 1034, a cleaning unit 1035, a toner cartridge 1036, a paper feeding roller 1037, a paper feeding tray 1038, A registration roller pair 1039, a fixing roller 1041, a paper discharge roller 1042, a paper discharge tray 1043, a communication control device 1050, a printer control device 1060 that comprehensively controls the above-described units, and the like are provided. These are housed in predetermined positions in the printer housing 1044.

  The communication control device 1050 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The printer control device 1060 includes a CPU, a ROM described in a program written in code readable by the CPU, various data used when executing the program, a RAM as a working memory, an analog data An AD conversion circuit for converting the signal into digital data. The printer control device 1060 controls each unit in response to a request from the host device, and sends image information from the host device to the optical scanning device 1010.

  The photosensitive drum 1030 is a cylindrical member, and a photosensitive layer is formed on the surface thereof. That is, the surface of the photoconductor drum 1030 is a scanned surface. The photosensitive drum 1030 rotates in the direction of the arrow in FIG.

The charging device 1031, the developing roller 1032, the transfer charger 1033, the charge removal unit 1034, and the cleaning unit 1035 are each disposed in the vicinity of the surface of the photosensitive drum 1030. The charging device 1031 → the developing roller 1032 → the transfer charger 1033 → the discharging unit 1034 → the cleaning unit 1035 are arranged in the order of rotation of the photosensitive drum 1030.
The charging device 1031 uniformly charges the surface of the photosensitive drum 1030.

  The optical scanning device 1010 scans the surface of the photosensitive drum 1030 charged by the charging device 1031 with a light beam modulated based on image information from the host device, and corresponds to the image information on the surface of the photosensitive drum 1030. A latent image is formed. The latent image formed here moves in the direction of the developing roller 1032 as the photosensitive drum 1030 rotates. The configuration of the optical scanning device 1010 will be described later.

  The toner cartridge 1036 stores toner, and the toner is supplied to the developing roller 1032.

  The developing roller 1032 causes the toner supplied from the toner cartridge 1036 to adhere to the latent image formed on the surface of the photosensitive drum 1030 to visualize the image information. Here, the toner-attached image (hereinafter also referred to as “toner image” for the sake of convenience) moves in the direction of the transfer charger 1033 as the photosensitive drum 1030 rotates.

  Recording paper 1040 is stored in the paper feed tray 1038. A paper feed roller 1037 is disposed in the vicinity of the paper feed tray 1038, and the paper feed roller 1037 takes out the recording paper 1040 one by one from the paper feed tray 1038 and conveys it to the registration roller pair 1039. The registration roller pair 1039 temporarily holds the recording paper 1040 taken out by the paper supply roller 1037, and in the gap between the photosensitive drum 1030 and the transfer charger 1033 according to the rotation of the photosensitive drum 1030. Send it out.

  A voltage having a polarity opposite to that of the toner is applied to the transfer charger 1033 in order to electrically attract the toner on the surface of the photosensitive drum 1030 to the recording paper 1040. With this voltage, the toner image on the surface of the photosensitive drum 1030 is transferred to the recording paper 1040. The recording sheet 1040 transferred here is sent to the fixing roller 1041.

In the fixing roller 1041, heat and pressure are applied to the recording paper 1040, whereby the toner is fixed on the recording paper 1040. The recording paper 1040 fixed here is sent to the paper discharge tray 1043 via the paper discharge roller 1042 and is sequentially stacked on the paper discharge tray 1043.
The neutralization unit 1034 neutralizes the surface of the photosensitive drum 1030.

  The cleaning unit 1035 removes the toner remaining on the surface of the photosensitive drum 1030 (residual toner). The surface of the photosensitive drum 1030 from which the residual toner is removed returns to the position facing the charging device 1031 again.

Next, the configuration of the optical scanning device 1010 will be described.
As shown in FIG. 2 as an example, the optical scanning device 1010 includes a light source device 14, a coupling lens 15, an aperture plate 16, a cylindrical lens 17, a reflection mirror 18, a polygon mirror 13, a first scanning lens 11a, and a second scanning lens 11a. A scanning lens 11b, a scanning control device (not shown), and the like are provided. These are assembled at predetermined positions of the optical housing 30.

  In the following, for convenience, the direction corresponding to the main scanning direction is abbreviated as “main scanning corresponding direction”, and the direction corresponding to the sub scanning direction is abbreviated as “sub scanning corresponding direction”.

The coupling lens 15 converts the light beam emitted from the light source device 14 into substantially parallel light.
The aperture plate 16 has an aperture and defines the beam diameter of the light beam through the coupling lens 15.

  The cylindrical lens 17 forms an image of the light flux that has passed through the opening of the aperture plate 16 in the vicinity of the deflection reflection surface of the polygon mirror 13 via the reflection mirror 18 in the sub-scanning corresponding direction.

  The optical system disposed on the optical path between the light source device 14 and the polygon mirror 13 is also called a pre-deflector optical system. In the present embodiment, the pre-deflector optical system includes a coupling lens 15, an aperture plate 16, a cylindrical lens 17, and a reflection mirror 18.

  The polygon mirror 13 is made of a regular hexagonal columnar member having a low height, and six deflecting reflection surfaces are formed on the side surface. The polygon mirror 13 deflects the light flux from the reflection mirror 18 while rotating at a constant speed around an axis parallel to the sub-scanning corresponding direction.

  The first scanning lens 11 a is disposed on the optical path of the light beam deflected by the polygon mirror 13.

  The second scanning lens 11b is disposed on the optical path of the light beam that passes through the first scanning lens 11a. Then, the light beam that has passed through the second scanning lens 11b is irradiated onto the surface of the photosensitive drum 1030 to form a light spot. This light spot moves in the longitudinal direction of the photosensitive drum 1030 as the polygon mirror 13 rotates. That is, the photoconductor drum 1030 is scanned. The moving direction of the light spot at this time is the “main scanning direction”. The rotation direction of the photosensitive drum 1030 is the “sub-scanning direction”.

  The optical system arranged on the optical path between the polygon mirror 13 and the photosensitive drum 1030 is also called a scanning optical system. In this embodiment, the scanning optical system includes a first scanning lens 11a and a second scanning lens 11b. Even if at least one folding mirror is disposed on at least one of the optical path between the first scanning lens 11 a and the second scanning lens 11 b and the optical path between the second scanning lens 11 b and the photosensitive drum 1030. good.

  As an example, the light source device 14 includes a surface emitting laser element 100 and a package (not shown) on which the surface emitting laser element 100 is mounted, as shown in FIG.

  As an example, the surface emitting laser element 100 includes 35 (7 × 5) light emitting units 140 arranged in a matrix and four inspection openings arranged so as to surround the 35 light emitting units 140. 150.

  Here, each light emitting unit is a vertical cavity surface emitting laser (VCSEL) having an oscillation wavelength of 850 nm. Therefore, hereinafter, the plurality of light emitting units 140 are also collectively referred to as a surface emitting laser array.

  In this specification, the light emission direction from each light emitting unit is described as a Z-axis direction, and two directions orthogonal to each other in a plane orthogonal to the Z-axis direction are described as an X-axis direction and a Y-axis direction.

  The surface emitting laser element 100 is mounted on a package (not shown) in a state where the rotational position around the Z axis is adjusted, for example, as shown in FIG. In this case, since the perpendiculars dropped from the center of the 35 light emitting units onto the virtual line extending in the sub-scanning corresponding direction are equally spaced (interval d2), the photosensitive member is adjusted by adjusting the lighting timing of each light emitting unit. 35 light spots can be formed on the drum 1030 at equal intervals in the sub-scanning direction. Hereinafter, in the surface emitting laser element 100, the direction in which the seven light emitting units 140 are arranged is referred to as a row direction, and the direction in which the five light emitting units 140 are arranged is referred to as a column direction.

  As an example, if the pitch d1 in the sub-scanning corresponding direction between two light emitting units adjacent in the column direction is, for example, 18.55 μm, the interval d2 is 2.65 μm. If the magnification of the entire optical system of the optical scanning device 1010 is, for example, 2 times, writing dots can be formed on the photosensitive drum 1030 at intervals of 5.3 μm in the sub-scanning direction. That is, high-density writing of 4800 dpi (dot / inch) can be performed.

Of course, if the number of light emitting units arranged in the row direction is increased, the light emitting units are arranged so that the pitch d1 is narrowed and the interval d2 is further reduced, or the magnification of the entire optical system of the optical scanning device 1010 is decreased. The writing density can be further increased, and higher quality printing is possible. Note that the writing interval in the main scanning direction can be easily controlled by adjusting the lighting timing of each light emitting unit.
The four inspection openings 150 will be described in detail later.

  As an example, the surface emitting laser element 100 includes a substrate 101, a lower semiconductor DBR 103, a lower spacer layer 104, an active layer 105, an upper spacer layer 106, as shown in FIG. The upper semiconductor DBR 107, the contact layer 109, the interlayer insulating film 111, the p-side electrode 113, the n-side electrode 114, and the like are included.

The substrate 101 is an n-GaAs single crystal substrate.
The lower semiconductor DBR 103 is stacked on the + Z side of the substrate 101 and has 40.5 pairs of a low refractive index layer made of n-AlAs and a high refractive index layer made of n-Al _0.3 Ga _0.7 As. doing. Between each refractive index layer, in order to reduce an electrical resistance, a composition gradient layer having a thickness of 20 nm in which the composition is gradually changed from one composition to the other composition is provided. Each refractive index layer includes 1/2 of the adjacent composition gradient layer, and is set to have an optical thickness of λ / 4 when the oscillation wavelength is λ. When the optical thickness is λ / 4, the actual thickness D of the layer is D = λ / 4n (where n is the refractive index of the medium of the layer).

The lower spacer layer 104 is stacked on the + Z side of the lower semiconductor DBR 103 and is a layer made of non-doped (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P.

  The active layer 105 is stacked on the + Z side of the lower spacer layer 104 and is an active layer having a triple quantum well structure having three quantum well layers and four barrier layers. Each quantum well layer is made of GaInAsP, which has a composition that induces 0.7% compressive strain, and has a band gap wavelength of about 780 nm. Each barrier layer is made of GaInP, which is a composition that induces a tensile strain of 0.6%.

The upper spacer layer 106 is laminated on the active layer 105 on the + Z side, and is a layer made of non-doped (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P.

  A portion composed of the lower spacer layer 104, the active layer 105, and the upper spacer layer 106 is also called a resonator structure, and the thickness thereof is set to be an optical thickness of one wavelength. The active layer 105 is provided at the center of the resonator structure at a position corresponding to the antinode in the standing wave distribution of the electric field so that a high stimulated emission probability can be obtained. The resonator reflectivity is designed to be 99% or more.

The upper semiconductor DBR 107 is laminated on the + Z side of the upper spacer layer 106, and has a low refractive index layer made of p-Al _0.9 Ga _0.1 As and a high refractive index made of p-Al _0.3 Ga _0.7 As. It has 25 pairs of layers. Between each refractive index layer, in order to reduce electrical resistance, a composition gradient layer is provided in which the composition is gradually changed from one composition to the other composition. Each refractive index layer is set to have an optical thickness of λ / 4 including 1/2 of the adjacent composition gradient layer.

  In one of the low refractive index layers in the upper semiconductor DBR 107, a selectively oxidized layer 108 made of p-AlAs is inserted with a thickness of 33 nm.

  The insertion position of the selectively oxidized layer 108 is a position corresponding to the third node from the active layer 105 in the standing wave distribution of the electric field.

  The contact layer 109 is stacked on the + Z side of the upper semiconductor DBR 107 and is a layer made of p-GaAs.

  The interlayer insulating film 111 is stacked on the + Z side of the contact layer 109 and is a layer made of a SiN film.

  A metal wiring insulated from the interlayer insulating film 111 extending from the contact layer 109 to an electrode pad (not shown) is formed. The metal wiring and the electrode pad are made of ohmic material AuZn and wiring material Au by a lift-off method.

  Next, a method for manufacturing the surface emitting laser element 100 will be described. A plurality of surface emitting laser elements 100 are simultaneously formed on the substrate 101 by a semiconductor manufacturing process, and then divided into a plurality of chip-shaped surface emitting laser elements 100. Note that a structure in which a plurality of semiconductor layers are stacked over the substrate 101 as described above is also referred to as a “stacked body” for convenience in the following.

(1) A laminate is formed by crystal growth by metal organic vapor phase epitaxy (MOCVD) or molecular beam epitaxy (MBE) (see FIG. 6).

Here, in the case of the MOCVD method, trimethylaluminum (TMA), trimethylgallium (TMG), and trimethylindium (TMI) are used as the group III material, and phosphine (PH ₃ ) is used as the group V material. Arsine (AsH ₃ ) is used. Further, carbon tetrabromide (CBr ₄ ) is used as a p-type dopant material, and hydrogen selenide (H ₂ Se) is used as an n-type dopant material.

(2) The 35 locations that will be the 35 light emitting portions 140 on the surface of the laminate are each masked with, for example, a square resist pattern with a side of 25 μm. In addition, a region surrounding the 35 locations on the surface of the laminated body is a substantially square frame resist in which 4 locations (for example, square portions each having a side of 25 μm) project inward are formed. Mask with a pattern (see FIGS. 3 and 7).

(3) A mesa structure (hereinafter abbreviated as “mesa” for the sake of convenience) is formed by ECR etching using Cl ₂ gas using each resist pattern as a photomask. Here, the etching is performed until the lower semiconductor DBR 103 is reached. In this case, a light emitting mesa serving as each light emitting portion and an inspection mesa in which each inspection opening is formed are formed. Note that although the location where the inspection opening is formed is not strictly a mesa structure, it will be referred to as an inspection mesa for convenience.

(4) The photomask is removed (see FIG. 8).

(5) The laminated body is heat-treated in water vapor. As a result, Al (aluminum) in the selectively oxidized layer 108 of the light emitting mesa is selectively oxidized from the outer peripheral portion of the light emitting mesa and is not oxidized surrounded by the Al oxide 108a at the center of the light emitting mesa. Region 108b remains (see FIG. 9). That is, a so-called oxidized constriction structure is formed that restricts the drive current path of the light emitting part only to the central part of the light emitting mesa. The non-oxidized region 108b is a current passage region (current injection region). In this way, for example, a substantially square current passing region having a width of about 4 μm is formed. The inspection mesa is also selectively oxidized inward from the three side surfaces.

(6) An interlayer insulating film 111 made of SiN is formed by vapor phase chemical deposition (CVD) (see FIG. 10).

(7) A photomask for forming a square contact hole 230 as a p-side electrode outlet is formed above each light emitting mesa. Further, a photomask for forming a square inspection opening 150 having the same opening area as that of the contact hole 230 is formed above each inspection mesa.

(8) A resist is applied on the interlayer insulating film 111, irradiated with light (for example, ultraviolet light) through the photomask, and developed to form a resist pattern.

(9) The interlayer insulating film 111 on which the resist pattern is formed is wet-etched to form the contact hole 230 and the inspection opening 150. Here, for example, BHF (buffered hydrofluoric acid) is used as the etchant.

(10) The photomask is removed.

  As a result, a square contact hole 230 is formed on the + Z side of each light emitting mesa in the interlayer insulating film 111, and a square having the same opening area as that of the contact hole 230 on the + Z side of each inspection mesa in the interlayer insulating film 111. A test opening 150 is formed (see FIG. 11).

(11) A square-shaped resist pattern having a side of 10 μm is formed in a region (emission region) serving as a light emitting part on the light emitting mesa, and a p-side electrode material is deposited. As the electrode material on the p side, a multilayer film made of Cr / AuZn / Au or a multilayer film made of Ti / Pt / Au is used. At this time, the p-side electrode material is also deposited on the electrode pad and the metal wiring.

(12) The electrode material deposited in the region to be the light emitting portion is lifted off, and the p-side electrode 113 is formed. A region surrounded by the p-side electrode is an emission region (light emission port) (see FIG. 5). At this time, an electrode pad and a metal wiring are also formed at the same time. As can be seen from FIG. 5, the opening area of the light exit opening is smaller than the opening area of the inspection opening 150.

(13) After polishing the back side of the substrate 101 to a predetermined thickness (for example, about 250 μm), the n-side electrode 114 is formed on the back surface (the −Z side surface) of the substrate 101. Here, the n-side electrode is a multilayer film made of AuGe / Ni / Au.

(14) Ohmic conduction is established between the p-side electrode and the n-side electrode by annealing. Thus, the light emitting mesa becomes a light emitting portion, and a plurality of surface emitting laser elements 100 are formed on the substrate 101.

  Thereafter, a plurality of chip-shaped surface emitting laser elements 100 are formed through several steps such as a cleaving step.

  By the way, when a contact hole is formed by wet etching by exposure, the contact layer made of p-GaAs as a mesa is exposed to an etchant (for example, BHF) for etching and removing the interlayer insulating film.

  In general, a contact layer made of p-GaAs does not dissolve in hydrofluoric acid, and acts as an etching stop layer during wet etching.

  However, it is necessary to make the contact layer relatively thin (about 20 nm). For example, when manufacturing a surface emitting laser element in the visible band to 850 nm band, a hole on the order of submicron to several μm is opened in the contact layer. "Bad" occurs. The hole due to the “blackening failure” does not stay in the contact layer but also reaches the upper semiconductor DBR.

  That is, the contact layer is damaged and partially disappears, and the upper semiconductor DBR made of p-AlGaAs under the contact layer is partially exposed. For convenience, the materials of the low refractive index layer and the high refractive index layer constituting the upper semiconductor DBR are collectively referred to as p-AlGaAs.

  In this case, when the p-side electrode is formed on the upper semiconductor DBR exposed by the disappearance of the contact layer, the contact resistance increases and the drive voltage of the device increases.

  The opening of the p-side electrode functions as a light exit, but p-AlGaAs is exposed near the light exit, so that the p-AlGaAs is oxidized and becomes black. As a result, the laser light emitted from the light exit is scattered and absorbed by the blackened p-AlGaAs oxide layer, and the light output is reduced.

  Further, when the contact layer becomes thin in the manufacturing process of the surface emitting laser element, the reflectance of the upper semiconductor DBR changes, and characteristics such as the oscillation threshold value change.

As described above, in the manufacturing process of the surface-emitting laser element in the visible band to the 850 nm band, the contact layer is damaged during wet etching for forming the contact hole, so that the blackening defect occurs, and the reliability of the element is increased. This led to a decrease in yield and yield.
This is a problem even in the case of an infrared surface emitting laser element capable of thickening the contact layer.

  Usually, by increasing the thickness of the p-GaAs layer (contact layer), it is possible to prevent the p-AlGaAs layer (upper semiconductor DBR) from being exposed, but on the other hand, light absorption increases. Further, when the p-GaAs layer becomes thin in the manufacturing process of the surface emitting laser element, the reflectance of the p-AlGaAs layer changes, and the characteristics such as the oscillation threshold value fluctuate.

  Therefore, the inventors have elucidated the cause and the mechanism of “blackening failure” when the p-GaAs layer is exposed to an etchant (for example, BHF) when forming a contact hole, through trial and error. It came to do.

  That is, it has been found that the occurrence of the “blackening failure” involves electrons and holes generated in the semiconductor when irradiated with light, as will be described below.

  For example, the surface of the surface emitting laser element in which the substrate side is made of an n-type semiconductor material and the exit side is made of a p-type semiconductor material is irradiated with light having energy greater than the energy gap, so that holes and electrons are generated. Generated.

  The electrons and holes drift to the substrate side and the holes drift to the exit side by an electric field formed by the energy band of the PN junction. When holes accumulated by drifting exceed a certain threshold, discharge occurs.

  This discharge triggers the p-GaAs layer in that portion to be oxidized. Due to this oxidation, etching of the contact layer proceeds, and in some cases, a hole is opened. Al in the underlying p-AlGaAs layer is oxidized by BHF, so that the hole progresses in the depth direction.

  The contact layer above the mesa is electrically independent inside the mesa, and the accumulated holes cannot escape to the outside of the mesa. For this reason, when the area of the mesa is large, or when the area where the interlayer insulating film (dielectric layer) is removed at the time of forming the contact hole is small, “blackening failure” occurs in large quantities.

  In the case of a large mesa which is about 1000 times compared to a normal mesa formed experimentally, the occurrence rate of “blackening failure” is remarkably high even with the same contact hole area, rather than opening a hole. The p-GaAs layer surface is roughened by oxidation.

  The factors causing the “blackening failure” and the mechanism thereof described above are new findings that the inventors have demonstrated for the first time after repeating various experiments.

  For this blackening defect, in this embodiment, as described above, four inspection openings 150 are formed in the surface emitting laser element 100, and the contact layer 109 is attached to each of the inspection openings 150 using, for example, a microscope. The appearance is inspected to determine whether or not “blackening failure” has occurred, and the elements are selected.

  That is, a surface emitting laser element that is determined to have a “blackening defect” by appearance inspection of the contact layer 109 through each inspection opening 150 is determined to be a defective product and is rejected. A surface emitting laser element determined not to be generated is mounted in a package as a non-defective product, or is sent to another inspection process and determined to be a non-defective product, and then mounted in the package.

  Since the “blackening failure” gradually proceeds as described above, the contact layer 109 may be monitored through each inspection opening 150 for a predetermined time, and the elements may be selected based on the monitoring result.

  FIG. 11 shows a plan view of a surface emitting laser element of a comparative example. In this surface emitting laser element, since an inspection opening is not formed when the element is manufactured, it is difficult to determine whether or not “blackening failure” has occurred by appearance inspection. In this case, when the hole due to “blackening failure” reaches the p-AlGaAs layer, the oxidation of the p-AlGaAs layer proceeds thereafter. For example, after the surface emitting laser element is mounted on the package, the emission characteristics are deteriorated. It is possible to find out. As a result, the package on which the element is mounted must be excluded as a defective product, resulting in deterioration in manufacturing efficiency such as a waste of the mounting process and a decrease in yield after mounting.

  FIG. 13A is a graph showing variations in drive current between the light emitting portions of the surface emitting laser element 100 manufactured by the manufacturing method of the first embodiment and judged to have no blackening defect. ing. FIG. 13B is a graph showing variations in driving current of the surface emitting laser element of the comparative example shown in FIG. In FIG. 13A and FIG. 13B, the horizontal axis indicates the difference from the average value of the drive current in percentage, and the vertical axis indicates the number of light emitting units (number of channels) with respect to the drive current.

  As can be seen from FIG. 13A and FIG. 13B, the drive current between the light emitting portions of the surface emitting laser element manufactured by the manufacturing method of the first embodiment and determined to have no blackening defect. The variation is smaller than the variation in the drive current between the light emitting portions of the surface emitting laser element of the comparative example.

  In the method of manufacturing the surface-emitting laser device 100 according to the first embodiment described above, the lower semiconductor DBR 103, the active layer 105, the upper semiconductor DBR 107 including the selective oxidation layer 108, and the contact layer 109 are sequentially stacked on the substrate 101. Forming the body, and forming the stacked body so as to form a plurality of (for example, 35) light-emitting mesas that form a plurality of (for example, 35) light-emitting portions, with the selectively oxidized layer 108 exposed on the side surfaces. An etching step, a step of forming an interlayer insulating film 111 on the plurality of light emitting mesas and a peripheral region of the plurality of light emitting mesas, a resist pattern is formed on the interlayer insulating film 111, and the interlayer insulating film 111 is wet etched. And a process of performing. In the wet etching step, the interlayer insulating film 111 formed on the plurality of light emitting mesas is partially removed to form a plurality of light emission ports, and the interlayer insulating film formed on the peripheral region. 111 is partially removed, and a plurality of (for example, four) inspection openings 150 for visual inspection of the contact layer 109 are formed.

  In this case, compared with, for example, TEG (test element group), PCM (process control module), etc., “blackening failure” by element unit can be detected with high accuracy, so that an element with blackening failure can be excluded as a defective product. As a result, it is possible to provide a highly reliable surface emitting laser element with little variation in light emission characteristics.

  As a result, according to the first embodiment, it is possible to manufacture the light source device 14 by mounting a highly reliable surface emitting laser element free from blackening defects in a package, and to improve the yield after mounting. . That is, it is possible to suppress the mounting process from being wasted and to improve the manufacturing yield of the light source device 14.

  In addition, since the plurality of inspection openings 150 are formed in parallel with the light emission port in the wet etching step, an increase in manufacturing steps can be suppressed.

  Further, in the etching step, a plurality of inspection mesas (projections) protruding to the plurality of light emitting mesas, in which the plurality of inspection openings 150 are formed, are formed in a peripheral region of the plurality of light emitting mesas. The laminate is etched.

  In this case, since the position of the inspection opening 150 formed in each inspection mesa can be grasped at a glance, the appearance inspection of the contact layer 109 can be performed smoothly.

  Further, since one inspection opening 150 is formed on each of the plurality of light emitting portions 140 on the + X side, the −X side, the + Y side, and the −Y side, it is possible to inspect the entire contact layer 109 evenly. it can.

  The opening area of each inspection opening 150 is set larger than the opening area of the light exit.

  In this case, as compared with the case where the contact layer 109 is visually inspected through the light emission port, the contact layer 109 can be extensively and easily inspected through each inspection opening 150.

  In the light source device 14, the surface emitting laser element 100 including a plurality of (for example, 35) light emitting units 140 (which is not determined as a defective product due to blackening failure) is mounted on the package. It is possible to provide a light source device having a highly reliable multi-channel surface emitting laser element free from “blackening failure”.

  Further, since the optical scanning device 1010 includes the light source device 14, it is possible to stably and accurately scan the photosensitive drum simultaneously with a large number of light spots.

  Further, since the laser printer 1000 includes the optical scanning device 1010, an image can be formed at high speed and with high definition. That is, it is possible to improve throughput and image quality.

  On the other hand, even the techniques disclosed in Patent Documents 1 to 3 cannot completely suppress “blackening failure”, and if the hole opened in the contact layer reaches the AlGaAs layer, the AlGaAs layer is oxidized. Even if the device progressed and was determined to be a non-defective product in the initial characteristic inspection, the light emission characteristics deteriorated over time, and it was determined that the device was determined to be defective after being mounted on the package.

  In this case, the cost required for mounting is wasted, and the manufacturing cost of the element is increased. Further, if an inspection process is added so that this defective product does not flow out to the market, the cost increases due to an increase in inspection man-hours, which also increases the manufacturing cost. Also, even if an appearance inspection is performed through the light emission port before the mounting process to detect “blackening failure”, the light emission port has a very small opening area and a defect size of about submicron to several microns. Due to its size, it was difficult to detect. As a result, with the techniques disclosed in Patent Documents 1 to 3, it is difficult to eliminate the surface emitting laser element in which the blackening defect has occurred as a defective product.

  Below, 2nd Embodiment of this invention is described with reference to FIGS. In the second embodiment, differences from the first embodiment will be mainly described, and members having the same configurations as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

  In the second embodiment, each light emitting unit is a vertical cavity surface emitting laser (VCSEL) having an oscillation wavelength band of 780 nm.

  As an example, a surface emitting laser element 200 according to the second embodiment includes an n-type semiconductor layer 115 and a light detection unit between a contact layer 109 and an interlayer insulating film 111 of each inspection mesa as shown in FIG. The point 121 is different from the surface emitting laser element 100 of the first embodiment.

  In the method for manufacturing the surface emitting laser element 200 of the second embodiment, first, as shown in FIG. 15, the contact layer 109 which is the uppermost layer of the laminate produced in the manufacturing process (1) of the first embodiment. An n-type semiconductor layer 115 made of, for example, n-GaInP having a thickness of 30 nm, which functions as an etching stop layer and a diffusion prevention layer, is formed thereon.

  Then, an n-type semiconductor layer 117 made of n-GaAs having a thickness of 3 μm, for example, and a p-type semiconductor layer 119 made of p-GaAs having a thickness of 3 μm, for example, are sequentially stacked on the n-type semiconductor layer 115. A photodetector having a PN structure including the layer 117 and the p-type semiconductor layer 119 is formed.

  Thus, the photodetector is made of GaAs, which is the same material as the substrate 101, and it is generally difficult to provide a material having a smaller band gap energy on the substrate 101.

  That is, the photodetector is made of a material that can absorb even the light having the longest wavelength. Note that the photodetector may have a PIN structure including a p-GaAs layer, an i-GaAs layer, and an n-GaAs layer.

  The n-type semiconductor layer 115 has a composition that is lattice-matched to the substrate 101, has a sufficiently large band gap energy with respect to GaAs, and can effectively suppress carrier diffusion.

  In addition, since the n-type semiconductor layer 115 doped in the n-type has a potential barrier in the valence band, a contact layer of holes which are minority carriers generated in the n-type semiconductor layer 117 of the photodetector. Diffusion to the 109 side can be more effectively suppressed.

  Next, a resist pattern for forming an inspection mesa is formed on a predetermined portion of the light detector (see FIG. 16), and a portion of the light detector on which the resist pattern is not formed is removed using a sulfuric acid-based etching solution. As a result, the light detection unit 121 is formed (see FIG. 17). In this case, since n-GaInP is not eroded by the sulfuric acid-based etching solution, the etching can be stopped on the surface of the n-type semiconductor layer 115.

  Next, the n-type semiconductor layer 115 is removed using a hydrochloric acid-based etching solution. In this case, since p-GaAs is not eroded by the hydrochloric acid-based etching solution, the etching can be stopped at the surface of the contact layer 109 (see FIG. 18).

  Next, a light emitting mesa and an inspection mesa are formed in the same manner as in the manufacturing steps (2) to (4) of the first embodiment (see FIGS. 19 and 20), and in the same manner as in the manufacturing step (5). An oxide confinement structure is formed (see FIG. 21), and an interlayer insulating film 111 is formed in the same manner as in the manufacturing process (6) (see FIG. 22). In the same manner as in the manufacturing processes (7) to (10), Contact holes and inspection openings are formed (see FIG. 23), and a plurality of surface-emitting laser elements 200 are formed on the substrate 101 in the same manner as in the manufacturing steps (11) to (14). Then, it is divided into a plurality of chip-shaped surface emitting laser elements 200.

  FIG. 24 is a graph showing variations in driving current between the light emitting portions of the surface emitting laser element 200 manufactured by the manufacturing method of the second embodiment and determined to have no blackening defect. In FIG. 24, the horizontal axis indicates the difference from the average value of the drive current in percentage, and the vertical axis indicates the number of light emitting units (number of channels) with respect to the drive current.

  As can be seen from FIGS. 24 and 13A, the variation in the drive current between the light emitting portions of the surface emitting laser element 200 manufactured by the manufacturing method of the second embodiment and determined to be free from blackening defects is shown. The variation in the drive current between the light emitting portions of the surface emitting laser element 100 manufactured by the manufacturing method of the first embodiment is small.

  In the second embodiment, most of the incident light incident on the light detection unit 121 through the inspection opening is absorbed by the light detection unit 121, and the n-type semiconductor layer 117 and the p-type semiconductor layer 119 of the light detection unit 121 are absorbed. On the other hand, the generated minority carriers can easily reach the other. Further, the n-type semiconductor layer 115 suppresses the diffusion of minority carriers from the light detection unit 121 to the contact layer 109. Hereinafter, a portion other than the light detection portion of the surface emitting laser element is referred to as an element portion.

  As a result, the amount of charge accumulated in the photodetection unit 121 can be greatly increased, and as described below, the detection sensitivity of the damage to the surface of the element unit in the photodetection unit 121 is greatly increased and extremely fine. It is possible to accurately detect a defect.

  Generally, in a surface emitting laser element, a multilayer film reflecting mirror is used as an upper reflecting mirror. The multilayer mirror achieves extremely high reflectivity by alternately laminating a plurality of semiconductor layers having different refractive indexes. At this time, since the two adjacent semiconductor layers have different band gap energies in addition to the refractive index, a hetero barrier due to band discontinuity occurs at the interface between the two adjacent semiconductor layers, preventing carrier diffusion and drift. It is done.

  In the p-type multilayer mirror, the Fermi level is changed by doping, so that the valence band energies of the respective semiconductor layers are equal. In this case, a potential barrier corresponding to the band discontinuity exists on the conduction band side of the heterointerface of each semiconductor layer. As a result, drift and diffusion of electrons, which are minority carriers, are hindered by this potential barrier.

  In addition, in the n-type multilayer mirror, the energy of the conduction band is aligned by doping, so that a potential barrier exists on the valence electron side, and movement of holes that are minority carriers is inhibited.

  As described above, when light absorption occurs in the p-type semiconductor layer and an electron-hole pair is formed, electrons that are minority carriers move to the pn junction surface (interface) by diffusion, and are generated by the electric field at the junction. It is accelerated and accumulated in the n-type semiconductor. In the n-type semiconductor, holes diffuse and accumulate in the p-type semiconductor across the pn junction.

  At this time, the minority carriers in the p-type semiconductor layer and the n-type semiconductor layer are affected by the potential barrier, and the diffusion to the pn junction surface is inhibited. In this case, in a structure including a large number of heterointerfaces, the amount of accumulated charge tends to decrease. This means that the occurrence of “blackening failure” is suppressed, which is preferable in this respect.

  However, in order to detect the degree of damage of the surface of the element portion with high sensitivity, it is desirable that the generated carriers are sufficiently accumulated on the surface of the inspection mesa (near the inspection opening).

  In the second embodiment, a configuration is realized in which damage to the surface of the element portion can be reduced as much as possible, and the damage state of the contact layer surface can be monitored with high sensitivity.

  Therefore, it is desirable that the light detection unit is formed of a semiconductor material that is homojunction and has as little band gap energy as possible. Further, a semiconductor material having a band gap energy as large as possible (for example, a band gap energy larger than that of a semiconductor material constituting the light detection unit) for preventing carrier diffusion between the light detection unit and the contact layer. It is desirable that a configured diffusion preventing layer is disposed.

  In this case, the light incident on the light detection unit through the inspection opening is efficiently absorbed by the light detection unit, and the light reaching the element unit is greatly reduced. In this case, since the generation of carriers in the multilayer reflector is reduced, it is possible to reduce the generation of ineffective carriers that are blocked by the potential barrier at the heterointerface and remain in the element portion. In addition, light that has been detected by the conventional element unit is absorbed by the photodetection unit, and since there is no barrier that inhibits carrier diffusion in the photodetection unit, minority carriers can easily be a partner region of a pn junction. The carriers are accumulated very efficiently with respect to the incident light.

  The above is a description of an element on an n-type substrate, but it is not limited to an element on an n-type substrate, and the same can be said for an element on a p-type substrate. In the case of using a p-type substrate, the same effect can be obtained by replacing the conductivity type of each semiconductor layer and the polarity of carriers with respect to the above description.

  By the way, on the GaAs substrate, an AlGaAs multilayer mirror having excellent reflection characteristics and heat dissipation characteristics can be used as compared with the case of using another substrate. For this reason, a surface emitting laser element having excellent characteristics for practical use using a GaAs substrate has been realized.

  In addition, an oscillation wavelength of 650 to 850 nm can be obtained by a plurality of semiconductor materials grown on a GaAs substrate.

  Of the semiconductor materials that can be grown on a GaAs substrate, GaAs has the smallest band gap energy, and if this is used as a material for the PN junction or PIN junction of the photodetection section, a wide range of light from the 870 nm band to a short wave can be obtained. Can be detected.

  In addition, GaInP has a larger band gap energy than GaAs, and the effect of preventing the carriers generated in the photodetection part from diffusing into the element part is obtained. Furthermore, selective etching can be performed on GaAs. It is possible to selectively remove the photodetector by PN junction or PIN junction made of GaAs grown on the region to be the light emitting portion in the portion, leaving only the normal element portion.

  As a result, according to the second embodiment, when a surface-emitting laser element in the 650 to 850 nm band is manufactured, a structure in which a light detection part by a PN junction or a PIN junction is provided on the element part can be easily manufactured. Can do. In addition, the sensitivity of light detection can be further increased.

  The above is a description of an element on an n-type substrate, but it is not limited to an element on an n-type substrate, and the same can be said for an element on a p-type substrate. When a p-type substrate is used, the same effect can be obtained by replacing the conductivity type of each layer and the polarity of carriers in the above description. Further, the wavelength is not limited to the 780 nm band, and may be another wavelength band using different active layer materials such as a 650 nm band, an 850 nm band, a 980 nm band, a 1.3 μm band, and a 1.5 μm band. The substrate may be a substrate other than GaAs.

  In the second embodiment, the n-type semiconductor layer 115 is formed between the photodetector and the contact layer. However, the photodetector is directly attached to the contact layer without providing the n-type semiconductor layer 115. It may be formed.

  Below, 3rd Embodiment of this invention is described with reference to FIGS. In the third embodiment, differences from the first and second embodiments will be mainly described, and members having the same configurations as those of the first and second embodiments are denoted by the same reference numerals, Description is omitted.

  FIG. 26 shows a cross-sectional view of the surface emitting laser element 300 of the third embodiment. The third embodiment is different from the first and second embodiments in that a dielectric layer 112 is disposed between the contact layer 109 and the interlayer insulating film 111.

  In the method for manufacturing the surface-emitting laser device 300 according to the third embodiment, first, the P-CVD method (on the contact layer 109 which is the uppermost layer of the laminate produced in the manufacturing step (1) of the first embodiment) An optically transparent dielectric layer 112 made of P-SiN (SiNx) is formed using a plasma CVD method (see FIG. 27).

  Here, the optical length of the dielectric layer 112 is λ / 4. Specifically, since the refractive index n of SiN is 1.89 and the oscillation wavelength λ is 780 nm, the actual film thickness (= λ / 4n) is set to 103 nm.

  Next, a resist pattern A is formed on the dielectric layer 112 (see FIG. 28). As an example, the resist pattern A includes a pattern a for defining the outer shape of each light emitting mesa, a pattern b for masking a part of a region where a light emission port of the light emitting mesa is formed, and each inspection mesa A pattern c for defining the outer shape and for masking the region where the electrode pad is formed is included.

  Here, as shown in FIG. 29, the pattern a is made of a square frame resist. The pattern b is formed of two rectangular resists having a longitudinal direction in the Y-axis direction formed so as to sandwich the central portion of the pattern a in the X-axis direction inside the pattern a. In the pattern c, an opening is formed at a location corresponding to the location where the inspection opening is formed. As an example, the opening areas of the pattern a and the pattern c are set to the same size.

  Then, for example, the dielectric layer 112 is selectively etched by wet etching using BHF as an etchant. As a result, the region where the resist pattern A is not formed in the dielectric layer 112 is removed, and the region where the resist pattern A is formed in the dielectric layer 112 remains (see FIG. 30).

  As a result, in the region where the light exit is formed, the reflectance of the peripheral portion is relatively lower than the reflectance of the central portion, and without lowering the light output of the fundamental transverse mode, Oscillation can be suppressed.

  Here, when the dielectric layer 112 is removed, the contact layer 109 is exposed and exposed to an etchant. Therefore, by performing an appearance inspection on the exposed portion of the contact layer 109, “blackening failure” in the contact layer 109 can be detected. When “blackening failure” is detected, the structure to be processed can be excluded from the manufacturing process.

  Next, a resist pattern B is formed on the resist pattern A. The resist pattern B includes a pattern d for masking a region surrounded by the pattern a and a pattern e for masking a region to be an inspection opening (see FIG. 31).

Then, for example, a light emitting mesa and an inspection mesa are formed by dry etching using Cl ₂ gas (see FIG. 32). Here, the bottom surface of the etching by dry etching is located in the + Z side surface of the lower semiconductor DBR 103. After the dry etching, the resist pattern A and the resist pattern B are removed.

  Next, the selectively oxidized layer 108 whose side surface is exposed by dry etching is heat-treated in water vapor to cause oxidation to proceed from the side surface of the mesa to generate an oxide 108a (see FIG. 33). That is, an oxidation confinement structure is formed that restricts the drive current path of the element to only the unoxidized region 108b in the center.

  Next, an interlayer insulating film 111 made of SiN is formed on the entire region of the structure shown in FIG. 33 by plasma CVD (see FIG. 34).

  Similar to the manufacturing steps (7) to (9) of the first embodiment, the interlayer insulating film 111 formed on the contact layer 109 of the light emitting mesa and the inspection mesa is wet using, for example, BHF as an etchant. Etching is performed to form contact holes and inspection openings.

  Here, when the interlayer insulating film 111 is removed, portions of the contact layer 109 corresponding to the contact holes and the inspection openings are exposed and exposed to the etchant. Therefore, by visually inspecting the contact layer 109 through the inspection opening, “blackening failure” in the contact layer 109 can be accurately detected. When “blackening failure” is detected, the structure to be processed can be excluded from the manufacturing process.

  Next, in the same manner as in the manufacturing steps (11) to (14) of the first embodiment, the p-side electrode 113 is formed, the n-side electrode 114 is formed, and ohmic conduction is established between the p-side electrode and the n-side electrode. . For example, a plurality of chip-shaped surface-emitting laser elements 300 are formed through several steps including a cleaving step.

  In the third embodiment described above, the contact layer 109 is exposed to the etchant when the dielectric layer 112 is removed by wet etching and when the interlayer insulating film 111 is removed by wet etching. In this case, from the time the dielectric layer 112 is removed until the interlayer insulating film 111 is removed, “exposed blackening” can be detected by appropriately inspecting the exposed portion of the contact layer 109. Then, after the interlayer insulating film 111 is removed, the appearance of the contact layer 109 is appropriately inspected through the inspection opening, thereby detecting “blackening failure”.

  On the other hand, since the opening area of the light exit opening is smaller than the opening area of the inspection opening and there is a part of the dielectric layer 112 in the light exit opening (see FIG. 26), the appearance inspection through the light exit opening is performed. Therefore, it is very difficult to detect “blackening failure”.

  Note that the resist pattern A in the third embodiment can be changed as appropriate. For example, the pattern b is different from the third embodiment as long as the reflectance at the peripheral portion inside the dielectric layer corresponding to the pattern a is lower than the reflectance at the central portion. It may be.

In the first to third embodiments, SiN is used as the material of the interlayer insulating film 111, but it may be, for example, SiO ₂ or SiON.

In the first to third embodiments, SiN is used as the material of the dielectric layer 112. However, for example, SiO ₂ , SiON, or the like may be used.

  In the first to third embodiments, when wet etching is performed, light having energy higher than the band gap energy of AlGaAs constituting the upper semiconductor DBR 107 may be irradiated when forming a resist pattern. .

  In this case, when the “blackening failure” occurs in the contact layer 109, the progress can be accelerated. Therefore, by monitoring the contact layer 109, “blackening failure” due to a subtle change in the wet etching environment. "Can be reliably detected at an early stage, and the element can be quickly selected. As a result, the manufacturing process after wet etching is not wasted. In addition, by feeding back the monitoring results to the wet etching process environment, it is possible to suppress the occurrence of “blackening failure” and to manufacture a highly reliable surface emitting laser element with less variation in light emission characteristics between light emitting portions. it can.

  By the way, wet etching is usually performed in an environment without illumination (dark environment) or an environment in which illuminance is controlled. However, wet etching in an environment without illumination is difficult and unintentional illuminance in terms of work and safety. Since a change is also assumed, “blackening failure” can be accurately detected by forming the inspection opening.

  Moreover, in the said 1st-3rd embodiment, although the opening area of each test opening is made the same as the opening area of a contact hole, it is not restricted to this, Essentially, it is more than the opening area of a light emission opening. Larger is preferred.

  In the first to third embodiments, the opening areas of the four inspection openings may be different from each other, and the protruding areas (areas viewed from the + Z side) of the four inspection mesas are different from each other. Alternatively, the four inspection mesas may have different planar shapes (the shapes viewed from the + Z side), and the four inspection openings may have different opening shapes (the shapes viewed from the + Z side). May be.

  In this case, since the four inspection openings can be easily identified, it is possible to grasp the defect caused by the “blackening failure” in the contact layer corresponding to which inspection opening, and this is fed back to the wet etching process environment, for example. By doing so, it is possible to construct a stable wet etching process, and it is possible to manufacture a highly reliable surface emitting laser element with less variation in light emission characteristics between light emitting portions.

  In the first to third embodiments, the number of inspection openings is four. However, the number is not limited to this. For example, the number may be one or more and three or less, or may be five or more. good.

  In the first to third embodiments, the four inspection openings are respectively formed on the + X side, the −X side, the + Y side, and the −Y side of the surface emitting laser array. For example, it may be formed at four corners of a rectangle surrounding the surface emitting laser array.

  In the first to third embodiments, the inspection opening is formed in the inspection mesa that is a protruding portion of a region (peripheral region) surrounding the surface emitting laser array, but is not limited thereto. For example, at least one inspection opening may be formed in the surrounding region without forming the inspection mesa in the region surrounding the surface emitting laser array. Further, for example, a mesa structure similar to the light emitting mesa may be formed in the peripheral region of the surface emitting laser array, and an inspection opening may be formed in the mesa structure.

  In the surface emitting laser arrays of the first to third embodiments, the light emitting units are arranged in a matrix along the XY plane. However, the present invention is not limited to this, and the two-dimensional arrangement is essential along the XY plane. It only has to be done.

  Moreover, in the surface emitting laser arrays of the first to third embodiments, the shape of the emission port and the inspection opening is a square shape, but is not limited thereto, for example, a polygonal shape other than a square, a circular shape, Other shapes such as an elliptical shape may be used.

  Moreover, although the said 1st-3rd embodiment demonstrated the case where the surface emitting laser element 100 had 35 light emission parts, it is not limited to this. For example, the surface emitting laser element may have only one light emitting portion, may have 2 to 34 pieces, or may have 36 pieces or more.

  Moreover, although the said 1st-3rd embodiment demonstrated the case where the oscillation wavelength of a light emission part was an 850 nm band or a 780 nm band, it is not limited to this. The oscillation wavelength of the light emitting unit may be changed according to the characteristics of the photoreceptor.

  The surface-emitting laser element 100, the surface-emitting laser element 200, and the surface-emitting laser element 300 can be used for applications other than the image forming apparatus. In that case, the oscillation wavelength may be a wavelength band such as a 650 nm band, an 850 nm band, a 980 nm band, a 1.3 μm band, and a 1.5 μm band depending on the application. In this case, a mixed crystal semiconductor material corresponding to the oscillation wavelength can be used as the semiconductor material constituting the active layer. For example, an AlGaInP mixed crystal semiconductor material can be used in the 650 nm band, an InGaAs mixed crystal semiconductor material can be used in the 980 nm band, and a GaInNAs (Sb) mixed crystal semiconductor material can be used in the 1.3 μm band and the 1.5 μm band.

  In the first to third embodiments, the case of the laser printer 1000 as the image forming apparatus has been described. However, the present invention is not limited to this.

  For example, an image forming apparatus that directly irradiates laser light onto a medium (for example, paper) that develops color with laser light may be used.

  For example, the medium may be a printing plate known as CTP (Computer to Plate). That is, the optical scanning device 1010 is also suitable for an image forming apparatus that forms a printing plate by directly forming an image on a printing plate material by laser ablation.

  For example, the medium may be so-called rewritable paper. For example, a material described below is applied as a recording layer on a support such as paper or a resin film. Then, reversibility is imparted to color development by thermal energy control by laser light, and display / erasure is performed reversibly.

  There are a transparent cloudy type rewritable marking method and a color developing / erasing type rewritable marking method using a leuco dye, both of which can be applied.

  The transparent cloudy type is a polymer thin film in which fine particles of fatty acid are dispersed. When heated to 110 ° C. or higher, the resin expands due to melting of the fatty acid. Thereafter, when cooled, the fatty acid becomes supercooled and remains in a liquid state, and the expanded resin solidifies. Thereafter, the fatty acid solidifies and shrinks to become polycrystalline fine particles, and voids are formed between the resin and the fine particles. Light is scattered by this gap and appears white. Next, when heated to an erasing temperature range of 80 ° C. to 110 ° C., the fatty acid partially melts, and the resin thermally expands to fill the voids. If it cools in this state, it will be in a transparent state and an image will be erased.

  The rewritable marking method using a leuco dye utilizes a reversible color development and decoloration reaction between a colorless leuco dye and a developer / decolorant having a long-chain alkyl group. When heated by laser light, the leuco dye and the developer / decolorant react to develop color, and when rapidly cooled, the colored state is maintained. Then, when it is slowly cooled after heating, phase separation occurs due to the self-aggregating action of the long-chain alkyl group of the developer / decolorant, and the leuco dye and developer / decolorizer are physically separated and decolored.

  In addition, when the medium is exposed to ultraviolet light, it develops in C (cyan) and is decolored by visible R (red) light, and when exposed to ultraviolet light, it develops in M (magenta). A photochromic compound that is decolored by G (green) light, a photochromic compound that develops color when exposed to ultraviolet light (Y) and is decolored by visible B (blue) light. So-called color rewritable paper provided on the body may be used.

  This is a method of expressing full color by controlling the color density of the three types of materials that develop color in Y, M, and C by the time and intensity of applying R, G, and B light once it is made black by applying ultraviolet light. However, if the strong light of R, G, and B is continuously applied, all three types can be decolored to become pure white.

  A device that imparts reversibility to color development by such light energy control can also be realized as an image forming apparatus including an optical scanning device similar to the above-described embodiment.

  Further, an image forming apparatus using a silver salt film as the image carrier may be used. In this case, a latent image is formed on the silver salt film by optical scanning, and this latent image can be visualized by a process equivalent to a developing process in a normal silver salt photographic process. Then, it can be transferred to photographic paper by a process equivalent to a printing process in a normal silver salt photographic process. Such an image forming apparatus can be implemented as an optical plate making apparatus or an optical drawing apparatus that draws a CT scan image or the like.

  As an example, as shown in FIG. 25, a color printer 2000 including a plurality of photosensitive drums may be used.

  The color printer 2000 is a tandem multicolor printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow), and is a black station (photosensitive drum K1, charging device K2). , Developing device K4, cleaning unit K5, and transfer device K6), cyan station (photosensitive drum C1, charging device C2, developing device C4, cleaning unit C5, and transfer device C6), and magenta station ( The photosensitive drum M1, the charging device M2, the developing device M4, the cleaning unit M5, and the transfer device M6), and the yellow station (the photosensitive drum Y1, the charging device Y2, the developing device Y4, the cleaning unit Y5, and the transfer device Y6). ), Optical scanning device 2010, and transfer belt 2 80, and a fixing unit 2030.

  Each photoconductor drum rotates in the direction of the arrow in FIG. 25, and a charging device, a developing device, a transfer device, and a cleaning unit are arranged around each photoconductor drum along the rotation direction. Each charging device uniformly charges the surface of the corresponding photosensitive drum. The surface of each photoconductive drum charged by the charging device is irradiated with light by the optical scanning device 2010, and a latent image is formed on each photoconductive drum. Then, a toner image is formed on the surface of each photosensitive drum by a corresponding developing device. Further, the toner image of each color is transferred onto the recording paper on the transfer belt 2080 by the corresponding transfer device, and finally the image is fixed on the recording paper by the fixing unit 2030.

  The optical scanning device 2010 has a light source device including a surface emitting laser element manufactured in the same manner as the surface emitting laser element 100 for each color. Therefore, the same effect as that of the optical scanning device 1010 can be obtained. In addition, since the color printer 2000 includes the optical scanning device 2010, the same effect as the laser printer 1000 can be obtained.

  By the way, in the color printer 2000, color misregistration may occur due to manufacturing error or position error of each component. Even in such a case, color misregistration can be reduced by selecting a light emitting unit to be lit.

  DESCRIPTION OF SYMBOLS 11a ... 1st scanning lens (a part of scanning optical system), 11b ... 2nd scanning lens (a part of scanning optical system), 13 ... Polygon mirror (light deflector), 14 ... Light source device, 100 ... Surface emitting laser Element 101 ... Substrate 103 ... Lower semiconductor DBR (lower reflector) 104 ... Lower spacer layer 105 ... Active layer 106 ... Upper spacer layer 107 107 Upper semiconductor DBR (upper reflector) 108 ... Selective oxidation Layer 109, contact layer 111, interlayer insulating film (protective film), 112 dielectric layer (protective film), 140, light emitting section, 150, inspection opening, 1000, laser printer, 1010, optical scanning device, 1030 ... photosensitive drum (image carrier), 2000 ... color printer (image forming apparatus), 2010 ... optical scanning device, K1, C1, M1, Y1 ... photosensitive drum (image carrier).

JP 2002-009393 A JP 2010-212515 A JP 2011-009368 A

Claims (7)

A method of manufacturing a surface-emitting laser element having at least one light-emitting portion,
A step of sequentially laminating a lower reflecting mirror, a resonator structure including an active layer, an upper reflecting mirror including a selective oxidation layer, and a contact layer on a substrate to form a stacked body;
Etching the stacked body so as to form at least one mesa structure in which the selective oxidation layer is exposed on a side surface, which serves as the at least one light emitting portion;
Forming a protective film on the at least one mesa structure and on a peripheral region of the at least one mesa structure;
Forming a resist pattern on the protective film, and wet etching the protective film,
In the wet etching step, the protective film formed on the at least one mesa structure is partially removed to form at least one light emission port, and the formed on the peripheral region. The protective film is partially removed to form at least one opening;
The method of manufacturing a surface-emitting laser element, wherein an opening area of the opening is larger than an opening area of the light emission port. The upper reflector includes AlGaAs,
2. The method of manufacturing a surface emitting laser element according to claim 1, wherein in the wet etching step, light having an energy higher than a band gap energy of the AlGaAs is irradiated when forming the resist pattern. . The at least one opening is a plurality of openings;
The method of manufacturing a surface emitting laser element according to claim 1, wherein opening areas of the plurality of openings are different from each other.   Prior to the etching step, a step of directly or indirectly forming a PN junction or a PIN junction sequentially laminated from a semiconductor layer of a conductivity type opposite to the contact layer on the contact layer of the laminate. The method of manufacturing a surface emitting laser element according to claim 1, further comprising:   In the step of forming the PN junction or the PIN junction, the band gap energy between the PN junction or the PIN junction and the contact layer is higher than that of the semiconductor layer constituting the PN junction or the PIN junction. The method of manufacturing a surface emitting laser element according to claim 4, wherein a semiconductor layer having a large thickness is formed.   6. The semiconductor layer according to claim 5, wherein the PN junction or the PIN junction includes GaAs, and the semiconductor layer having a larger band gap energy than the semiconductor layer constituting the PN junction or the PIN junction includes GaInP. The manufacturing method of the surface emitting laser element of description. A method of manufacturing a light source device having a surface emitting laser element manufactured by the method of manufacturing a surface emitting laser element according to any one of claims 1 to 6 and a package on which the surface emitting laser element is mounted,
Inspecting the contact layer through the opening to determine whether the surface emitting laser element is defective or not,
Mounting the surface-emitting laser element, which is determined not to be defective in the determining step, on the package.

Images