CN101425659A - Semiconductor laser and manufacturing method thereof - Google Patents

Semiconductor laser and manufacturing method thereof Download PDF

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CN101425659A
CN101425659A CNA2008101351847A CN200810135184A CN101425659A CN 101425659 A CN101425659 A CN 101425659A CN A2008101351847 A CNA2008101351847 A CN A2008101351847A CN 200810135184 A CN200810135184 A CN 200810135184A CN 101425659 A CN101425659 A CN 101425659A
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mask
substrate
semiconductor layer
type iii
compound semiconductor
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CN101425659B (en
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仓本大
仲山英次
大泉善嗣
藤本强
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Sony Corp
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Sony Corp
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Abstract

The invention discloses a semiconductor laser, method for manufacturing the same, optical head, optical disk device, semiconductor device and method for manufacturing the same and method for growing nitride type Group III-V compound semiconductor layer, wherein a semiconductor laser having an end face window structure is manufactured by growing a nitride type Group III-V compound semiconductor layer including an active layer including a nitride type Group III-V compound semiconductor containing at least In and Ga over a substrate. The method for manufacturing the semiconductor laser includes the steps of: forming a mask including an insulating film over the substrate, at least in the vicinity of the position of forming the end face window structure; and growing the nitride type Group III-V compound semiconductor layer including the active layer over a part, not covered with the mask, of the substrate. According to the invention, the nitride type Group III-V compound semiconductor layer can be very easily grown, which at least contains In and Ga and has a part with band-gap energy changed in at least one direction.

Description

Semiconductor laser and manufacture method thereof
The cross reference of related application
The present invention is contained in the theme of on October 31st, 2007 to the Japanese patent application JP 2007-282714 of Japan Patent office submission, and its full content is hereby expressly incorporated by reference.
Technical field
The present invention relates to manufacture method, semiconductor laser, shaven head, optical disc apparatus, the manufacture method of semiconductor device and the growing method of nitride type III-V compound semiconductor layer of semiconductor laser, relate in particular to ridged stripe semiconductor laser that for example has the end face window structure of using nitride type III-V compound semiconductor and shaven head and the optical disc apparatus that semiconductor laser is used as or is used for light source.
Background technology
In order to increase the maximum light output of semiconductor laser, need to introduce end face window structure inevitably, wherein, for the end face setting of resonator is transparent window with respect to the light from active layer.
In GaInP emitting red light semiconductor laser according to correlation technique, following method is effective: after the growth of the semiconductor layer that forms laser structure, with the Zn atom diffusion enter with the semiconductor layer that closes on as the resonator end face part in, increase band-gap energy with the part, thereby form end face window structure (for example, disclosing 2005-45009 number) with reference to Japan Patent.
On the other hand, in recent years, be used as light source in high-density optical disk apparatus etc. based on the semiconductor laser of nitride type III-V compound semiconductor.Most of nitride type III-V compound semiconductors are at heat and the mechanical properties material more stable than GaInP semiconductor.Therefore, in semiconductor laser, be difficult to form end face window structure by effectively not homoatomic diffusion and wet etching under the situation of GaInP emitting red light semiconductor laser based on nitride type III-V compound semiconductor.
Given this, for semiconductor laser, proposed to be used to form the whole bag of tricks of end face window structure and to test based on nitride type III-V compound semiconductor.Now, will the formation method of the end face window structure that has proposed be described.
Proposed following method: after forming laser bar by splitting (cleavage), utilization is by laser emission or be exposed to H 2The caused In of plasma eliminates and handles, and forms end face window structure (for example, disclose 2006-147814 number with reference to Japan Patent discloses 2006-147815 number with Japan Patent) by increasing near the resonator end face band-gap energy.Yet, in order to carry out these methods, need the high vacuum chamber facility, thereby cause large-scale device and facility investment.In addition, handle the resonator end face after the splitting and left over problem usually about productivity ratio.
Had many motions for following method: epitaxial growth is used to form after the semiconductor layer of laser structure on substrate, by the semiconductor layer part of reactive ion etching (RIE) excavation as the resonator end face, and in excavation regions once more epitaxial growth have the high band gap energy nitride type III-V compound semiconductor layer (for example, with reference to Japan Patent disclose 2004-134555 number, Japan Patent disclose 2003-60298 number, the world discloses the 03/036771st trumpeter's volume and Japan Patent discloses 2002-204036 number).Yet, according to this method, on by the surface that RIE excavated, can form surface level (level), thereby worry that meeting when laser operation light absorption takes place and amount of localized heat generates.
As another example, following method has been proposed: be provided with the semiconductor layer that epitaxial growth on the substrate that utilizes formed how much steps of RIE or insulator film deposition (step) is used to form laser structure, thereby form end face window structure (for example, with reference to Japan Patent disclose 2005-191588 number, Japan Patent disclose 2005-294394 number, Japan Patent discloses 2003-198057 number and Japan Patent discloses 2000-196188 number).This method is at a kind of phenomenon: on the laser direct of travel, the coating that band-gap energy is higher than active layer plays the effect of end face window structure.Figure 49 illustrates its representative instance.As shown in figure 49, in this semiconductor laser, an interarea by RIE one patterned substrate 101 is provided with recess 101a, growing n-type semiconductor layer 102, active layer 103 and p type semiconductor layer 104 in turn on recess 101a subsequently, after this, on p type semiconductor layer 104, form p lateral electrode 105, insulating electrode 106 and liner (pad) electrode 107.In other words, the existence owing to substrate 101 center dant 101a causes how much precipitous steps of generation in n type semiconductor layer 102, active layer 103 and p type semiconductor layer 104, feasible can the generation fiber waveguide loss near step.In addition, can't realize that therefore, this semiconductor structure can not play the function of effective end face structure by adding the transparence that broad-band gap obtains near the active layer the resonator end face 103.
Summary of the invention
As mentioned above, be used in the past having a lot of problems in the method that forms end face window structure based on the semiconductor laser of nitride type III-V compound semiconductor.
Therefore, need a kind of semiconductor laser of nitride type III-V compound semiconductor and manufacture method of semiconductor laser used, make and to form end face window structure easily, can suppress fiber waveguide loss, and can the operation of limit laser device the time because light absorption that the existence of surface level causes and amount of localized heat generation.
Also need above-mentioned good semiconductor laser is used as or is used for the shaven head and the optical disc apparatus of light source.
In addition, the growing method that needs nitride type III-V compound semiconductor layer, by this method, the nitride type III-V compound semiconductor that can easily grow and comprise In and Ga at least and have the part that band-gap energy changes at least in one direction, and need semiconductor device and manufacture method (wherein utilizing this growing method) thereof.
In order to address the above problem, the present inventor has carried out big quantity research.As result of study, the I nitride type III-V compound semiconductor layer that the present inventor has found to comprise In and Ga at least in growth (for example, the InGaN layer) under the situation, width that can be by selecting dielectric film mask part, at interval, shape, position wait the band-gap energy of controlling nitride type III-V compound semiconductor layer expectation part, and they have reached the present invention.Below, will the present inventor's discovery be described.
Basic research test below having carried out.
Shown in Figure 1A and Figure 1B, on n type GaN substrate 1, form two SiO of stripe-shaped with width w 2Film mask 2, their parallel to each other and spacing distances are d.Here, Figure 1A is a plane graph, and Figure 1B is the sectional view that the line B-B along Figure 1A is obtained.Subsequently, shown in Fig. 2 A and Fig. 2 B, be provided with SiO 2Epitaxial growth forms the GaN semiconductor layer 3 of the laser structure layer of GaN semiconductor laser on the n type GaN substrate 1 of film mask 2, and it comprises n type AlGaN coating (clad layer) 3a, n type GaN light waveguide-layer 3b, has unadulterated Ga 1-xIn xN (quantum well layer)/Ga 1-yIn yThe active layer 3c and the unadulterated InGaN light waveguide-layer 3d of N (barrier layer, x〉y) multi-quantum pit structure.Here, the n type AlGaN coating 3a of the layer that does not contain In and the growth temperature of n type GaN light waveguide-layer 3b for example are set in 900 ℃～1100 ℃ scopes; On the other hand, for example in 700 ℃～800 ℃ scopes, be provided with and have Ga 1-xIn xN/Ga 1-yIn yThe growth temperature of the active layer 3c of N multi-quantum pit structure and the InGaN light waveguide-layer 3d that do not mix of the layer that contains In.In this case, GaN semiconductor layer 3 is not in fact at SiO 2On the film mask 2 growth, but only on n type GaN substrate 1 not by SiO 2Grow on the part that film mask 2 covers.
The sample that utilizes exciting light (hv) irradiation to generate thus, and by the peak energy (referring to Fig. 2 B) of micro-luminescence generated by light estimation from the light of active layer 3c emission.As a result, can obtain about from the peak energy of active layer 3c emission to SiO 2The dependent basic data of the width w of film mask 2 and interval d.Fig. 3 and Fig. 4 show measurement result.
In figure shown in Figure 3, the following Δ λ that obtains on the reference axis that is defined in bBy λ 1Be illustrated in and SiO 2The office, par of the formed GaN semiconductor layer 3 in position that film mask 2 is enough far away is corresponding to the wavelength of the peak energy of launching from active layer 3c.In this case, along with away from SiO 2In a single day film mask 2 is moved into short wavelength side corresponding to the wavelength of emission peak energy, then is moved into long wavelength side once more.By λ MinExpression is corresponding to the peaked minimal wave length of emission peak energy.In this case, adopt Δ λ b=λ Min-λ 1Definition.
Fig. 3 shows at SiO 2The width w of film mask 2 keeps Δ λ b under the constant situation to change with the change of interval d.Width w is set to 5 μ m, 30 μ m and 50 μ m Three Estates.As shown in Figure 3, usually, along with interval d becomes big and along with width w becomes big, Δ λ bTend on negative direction, increase.For example, be that 5 μ m and interval d are under the situation of 10 μ m at width w, obtain the Δ λ of pact-9nm bValue.The Δ λ of pact-9nm bValue increases about 80meV corresponding to band-gap energy.This variation of band-gap energy is enough as the value of end face window structure.
In figure shown in Figure 4, the following Δ λ that obtains on the reference axis that is defined in cBy λ 2Expression with from SiO 2The corresponding wavelength of peak energy of the mid portion of the active layer 3c of Grown GaN semiconductor layer 3 emission in the zone between the film mask 2.In this case, adopt Δ λ c=λ 2-λ 1Definition.
Fig. 4 shows at SiO 2The width w of film mask 2 keeps Δ λ under the constant situation cChange with interval d changes.Width w is set to 5 μ m, 30 μ m and 50 μ m Three Estates.As shown in Figure 4, be not less than under the situation of 30 μ m Δ λ at width w cMove up at losing side; At width w is under the situation of 5 μ m, and when interval d was not more than 5 μ m, Δ λ c trended towards moving up in pros, and when d at interval is 10 μ m～50 μ m, trends towards moving up at losing side.For example, be that 5 μ m and interval d are under the situation of 3 μ m at width w, obtain the Δ λ of pact+5nm cValue, and w be 5 μ m and at interval d be under the situation of 20 μ m, obtain the Δ λ of pact-5nm cValue.
Find out from data shown in Figure 3, when only using single SiO 2During film mask 2, can expect that emission wavelength moves (increase of active layer 3c band-gap energy) to short wavelength side more.In addition, as shown in Figure 4, Δ λ can be realized in pleasantly surprised ground c0, that is, emission wavelength is shifted to longer wavelength side (reducing of active layer 3c band-gap energy).Can understand, can be by designing SiO arbitrarily 2The pattern of film mask 2 freely changes the band-gap energy of active layer 3c.
The present inventor draws and is passing through to use SiO as mentioned above 2Under the situation of film mask 2 epitaxial growth GaN semiconductor layers 3, the reason that can change the band-gap energy of active layer 3c why according to the part of GaN semiconductor layer 3 is that the In diffusion length compares very little conclusion with the Ga diffusion length.Now, this reason will be described.
Shown in Fig. 2 A and Fig. 2 B, on n type GaN substrate 1 not by SiO 2Under the situation of the active layer 3c of growing GaN semiconductor layer 3, not only In and Ga are directly provided to this part from the growth material source on the part that film mask 2 covers, and In and Ga also are provided to this part (at SiO by DIFFUSION TREATMENT 2In that is provided on the film mask 2 and Ga are at SiO 2Diffusion on the film mask 2).
Fig. 5 A, Fig. 5 B and Fig. 5 C show with respect to along with SiO 2The direction of film mask 2 quadratures from the distance of edge metering draw from being formed on the SiO on the n type GaN substrate 1 2The edge of mask 2 is to the variation of the In component of the change in concentration of the Ga of outside diffusion and In and active layer 3c.Shown in Fig. 5 A and Fig. 5 B, to compare under the very little situation with the Ga diffusion length in the In diffusion length, In concentration begins to become constant from short distance, delta X1, and Ga concentration begins to become constant from long distance, delta X2.This is reflected shown in Fig. 5 C, the In component of active layer 3c reduces until Δ X1,, just raise once more subsequently, begin to become constant from distance, delta X2 in case reach minimum value.Along with the Ga of diffusion and the increase of In concentration, distance, delta X1 and Δ X2 increase respectively.
Fig. 6 shows at SiO 2Interval d between the film mask 2 is fixed as the measurement result that Δ X1 and Δ X2 under the situation of 5 μ m change with the change of width w.In addition, Fig. 7 shows at SiO 2Width w between the film mask 2 is fixed as the measurement result that Δ X1 and Δ X2 under the situation of 5 μ m change with the change of interval d.As can be seen, be under the situation of 3 μ m～5 μ m at width w from Fig. 6 and Fig. 7, under the growth temperature of active layer 3c, maximum Ga diffusion length is about 20 μ m, and maximum In diffusion length is not more than 3 μ m, and it is than the little about magnitude of maximum Ga diffusion length.For this reason, think that at width w be under the situation of 3 μ m～5 μ m, d increases to about 40 μ m even work as at interval, also can reduce SiO 2The In component of active layer 3c in the central area between the film mask 2, and increase its band-gap energy.
Though described use SiO above 2Even the situation of film mask 2 is but by using by such as SiN film and Al 2O 3The formed mask of other dielectric film of film also can be realized top to the In component of active layer 3c and the identical control of band-gap energy.In addition, not only, can control In component and band-gap energy similarly for active layer but also for any nitride type III-V compound semiconductor layer that comprises In and Ga.
Result as the further research of being carried out based on above-mentioned research institute by the present inventor has finished the present invention.
According to the first embodiment of the present invention, provide a kind of manufacture method of semiconductor laser.Comprise the nitride type III-V compound semiconductor layer of the active layer that contains the nitride type III-V compound semiconductor that comprises In and Ga at least by growing on substrate, this method has end face window structure.This method may further comprise the steps: form mask and growing nitride type III-V compound semiconductor layer.Forming masks comprises at least form dielectric film near the substrate the position that forms end face window structure.The step of growing nitride type III-V compound semiconductor layer is included on the part that does not have masked covering on the substrate and forms active layer.
According to a second embodiment of the present invention, a kind of semiconductor laser with end face window structure is provided, and it has the nitride type III-V compound semiconductor layer that comprises the active layer that contains the nitride type III-V compound semiconductor that comprises In and Ga at least on substrate.At least near part, on substrate, form the mask that comprises dielectric film corresponding to end face window structure.On the part that does not have masked covering on the substrate, form the nitride type III-V compound semiconductor layer that comprises active layer.
A third embodiment in accordance with the invention provides a kind of shaven head that semiconductor laser is used as or is used for light source.Semiconductor laser has end face window structure, and this structure has the nitride type III-V compound semiconductor layer that comprises the active layer that contains the nitride type III-V compound semiconductor that comprises In or Ga at least on substrate.At least near part, on substrate, form the mask that comprises dielectric film corresponding to end face window structure.On the part that does not have masked covering on the substrate, form the nitride type III-V compound semiconductor layer that comprises active layer.
A fourth embodiment in accordance with the invention provides a kind of optical disc apparatus that semiconductor laser is used as or is used for light source.Semiconductor laser has end face window structure, and this structure has the nitride type III-V compound semiconductor layer that comprises the active layer that contains the nitride type III-V compound semiconductor that comprises In or Ga at least on substrate.At least near part, on substrate, form the mask that comprises dielectric film corresponding to end face window structure.On the part that does not have masked covering on the substrate, form the nitride type III-V compound semiconductor layer that comprises active layer.
In first to fourth embodiment of the present invention, at least based on the resulting above-mentioned discovery of the present inventor, according to the factors such as characteristic needs of semiconductor laser come suitably to determine the width of mask, at interval, shape, position etc.Can be by such as SiO 2Film, SiN film and Al 2O 3The various dielectric films of film form mask.In the formation example of mask, near the position that forms end face window structure and in the one or both sides that form the laser stripe position, on substrate, form mask.The flat shape of mask can be trapezoidal, rectangle etc., but is not restricted to this.Alternatively, can adopt following structure: in a side of the position that forms laser stripe along the position that forms laser stripe, on substrate, form mask, by this way, form near the position of the formation laser stripe the position of end face window structure and the interval between the mask will less than or greater than other zone.Perhaps, can adopt following structure: in the both sides of the position that forms laser stripe along the position that forms laser stripe, on substrate, form mask, by this way, the interval between near the mask of the both sides of the position of the formation laser stripe the position of formation end face window structure will be greater than other zone.Usually, select the width W of mask 1Less than the interval W between the mask 2, but this structure is not limited thereto.Form in the both sides that form the laser stripe position under the situation of mask, usually, with near the mask width W the resonator center 3With mask space W 4Between relation and form near the end face window structure position mask width W 5With mask space W 6Between relation be set to satisfy W 3＜W 4And W 5＜W 6, but this design is not limited thereto.When using the growth of these masks to comprise the nitride type III-V compound semiconductor layer of active layer, can mask between or the relation between the In component y of the active layer of the In component x (or emission wavelength lambda) of the active layer of the laser stripe near the zone the mask and the laser stripe in the maskless district (emission wavelength lambda ') be set to satisfy x＜y (λ＜λ ').In addition, can be with the thickness t of the laser stripe in the zone between the mask 1Thickness t with laser stripe in the maskless district 2Between relation be set to satisfy t 2＜t 1
Nitride type III-V compound semiconductor generally includes Al xB yGa 1-x-y-zIn zAs uN 1-u-vP v(wherein, 0≤x≤1,0≤y≤1,0≤z≤1,0≤u≤1,0≤v≤1,0≤x+y+z＜1,0≤u+v＜1), particularly Al xB yGa 1-x-y-zIn zN (wherein, 0≤x≤1,0≤y≤1,0≤z≤1,0≤x+y+z＜1) is typically Al xGa 1-x-zIn zN (wherein 0≤x≤1,0≤z≤1), and its specific limiting examples comprises GaN, InN, AlN, AlGaN, InGaN and AlGaInN.At least the nitride type III-V compound semiconductor that comprises In and Ga generally includes Al xB yGa 1-x-y-zIn zAsuN 1-u-vP v(wherein, 0≤x≤1,0≤y≤1,0＜z≤1,0≤u≤1,0≤v≤1,0≤x+y+z＜1,0≤u+v＜1) is typically Al xGa 1-x-zIn zN (wherein, 0≤x≤1,0＜z≤1), and its specific limiting examples comprises InGaN and AlGaInN.Can be typically by various epitaxial growth method growing nitride type III-V compound semiconductor layers such as metal organic chemical vapor deposition (MOCVD), the growth of hydrogen phase epitaxy or halogen vapor phase epitaxial growth (HVPE) and molecular ray epitaxial growth (MBE), growing method is not limited thereto.As substrate, preferably use conductive semiconductor substrate, particularly nitride type III-V compound semiconductor substrate (most typical is the GaN substrate).Yet, can also use insulated substrate such as sapphire substrate; In addition, can also use in these substrates of one deck nitride type III-V compound semiconductor layer at least of having grown one thereon.
Preferably, on substrate, do not have to grow on the part of masked covering and comprise after the nitride type III-V compound semiconductor layer of active layer, be provided with a step, wherein, the at least a portion (being preferably the major part of recess (groove)) that is formed on the recess (groove) on the mask upside by growing nitride type III-V compound semiconductor layer is filled with insulating material, thus relaxed since recess have a caused step (level error).More preferably, the whole insulating material that is filled with of recess is to have eliminated owing to the caused step of recess and to have obtained smooth surface.Because the mitigation or the elimination of the caused step of recess have been guaranteed (for example to form dielectric film in the step of back, be used to form in the zone of the ridged both sides on the top that comprises nitride type III-V compound semiconductor layer dielectric film with the current narrowing that is laser stripe) or the situation of electrode under, can form thus the parts that form well, and can not generate interruption that step brings out etc.Insulating material is gone up substantially and can be any insulating material, and not restriction especially.The example of insulating material comprises such as the application type insulating material of spin-coating glass (SOG) etc., such as the organic material of polyimides etc., such as SiO 2, Al 2O 3Deng oxide and such as the nitride of SiN.Insulating material is preferably the material that does not comprise siloxanes.The silicate inorganic SOG that comprises Doping Phosphorus as the example of this application type insulating material.
Optical disc apparatus comprises the device that only is used for regeneration (reading), only is used for the device of record (writing) and can be used for the device of regenerating and writing down.In addition, do not limit regeneration and/or recording mode especially.Shaven head is the device that is applicable to this optical disc apparatus.
According to a fifth embodiment of the invention, provide a kind of on substrate growth comprise the manufacture method of semiconductor device of the nitride type III-V compound semiconductor layer of In and Ga at least, this semiconductor layer has band-gap energy at least along the part that changes on the direction of substrate surface, this method may further comprise the steps: near the part that band-gap energy changes, form the mask that comprises dielectric film on substrate; And on the part that does not have masked covering on the substrate growing nitride type III-V compound semiconductor layer.
According to a sixth embodiment of the invention, provide a kind of semiconductor device with the nitride type III-V compound semiconductor layer that comprises In and Ga at least, this semiconductor layer has band-gap energy at least along the part that changes on the direction of substrate surface.Near the part that band-gap energy changes, on substrate, form the mask that comprises dielectric film.On the part that does not have masked covering on the substrate, form nitride type III-V compound semiconductor layer.
In the of the present invention the 5th and the 6th embodiment, semiconductor device not only comprises the semiconductor light-emitting apparatus such as semiconductor laser and light-emitting diode, but also comprise various semiconductor devices, and suitably design the structure of nitride type III-V compound semiconductor layer according to one of the correspondence of these devices such as FET and electron transition device.
Semiconductor laser can be vertical cavity surface emitting laser (VCSEL).For example, under the situation of the face emitting semiconductor laser that the structure that comprises the active layer that contains the nitride type III-V compound semiconductor that comprises In and Ga at least is set between first reflector and second reflector, for example, can be pre-formed the mask that comprises dielectric film on the surface by the layer under active layer with circular open, the method of growth activity layer is come the growth activity layer thereon subsequently, thereby can obtain following structure: along with away from the edge, In component and refractive index near the circular open edge the part reduce gradually, along with near core, In component and refractive index raise gradually then.Therefore, in this face emitting semiconductor laser, because light is easy to converge in the zone line of the circular open in the mask that comprises dielectric film when operation, so allow to reduce operating current.As first reflector and second reflector each, use distribution Bragg reflector (DBR) usually.
Alternatively, for example, in above-mentioned face emitting semiconductor laser, pick up under the situation of output light by second reflector, at least the nitride type III-V compound semiconductor layer that comprises In and Ga can be used to the light output part in second reflector, thereby can form the lens section with expectation refraction index profile in nitride type III-V compound semiconductor layer.Especially, identical with above-mentioned situation, for example, can be by on the laminar surface under the nitride type III-V compound semiconductor layer, being pre-formed the mask that comprises dielectric film and the method for the growing nitride type III-V compound semiconductor layer nitride type III-V compound semiconductor layer of growing thereon with circular open, thereby can obtain following structure: along with away from the edge, In component and refractive index near the circular open edge the part reduce gradually, along with near core, In component and refractive index raise gradually then.As a result, can form bull's-eye in the inside of mask split shed.When the In component of the nitride type III-V compound semiconductor layer that constitutes convex lens is set to the In component that is lower than active layer, can prevent to be absorbed by convex lens from the light of active layer emission.
In the of the present invention the 5th and the 6th embodiment,, set up the above-mentioned condition relevant, unless they do not satisfy expected performance with the present invention first to fourth embodiment about outside just described other.
According to a seventh embodiment of the invention, provide a kind of on substrate growth comprise the method for nitride type III-V compound semiconductor laser of In and Ga at least, this semiconductor layer has band-gap energy at least along the part that changes on the direction of substrate surface, this method may further comprise the steps: near the part that band-gap energy changes, form the mask that comprises dielectric film on substrate; And on the part that does not have masked covering on the substrate growing nitride type III-V compound semiconductor layer.
This growing method of nitride type III-V compound semiconductor layer can be applicable to the situation of the part that the formation band-gap energy changes in comprising the nitride type III-V compound semiconductor layer of In and Ga at least usually.For example, this method not only can be applicable to the production such as the semiconductor device of semiconductor laser and light-emitting diode, but also can be applied to the production such as the optics of above-mentioned convex lens, in addition, also can be applicable to the production of photonic crystal etc.
In the seventh embodiment of the present invention,, set up and the relevant above-mentioned condition of the present invention first to the 6th embodiment, unless they do not satisfy desired performance about outside just described other.
In first to fourth embodiment of the present invention that constitutes as mentioned above, when forming near the substrate that forms the position of end face window structure at least when comprising the mask of dielectric film and on substrate, not having on the part of masked covering the growth activity layer, because it is very little that the In diffusion length is compared with the Ga diffusion length, be lower than the In component in the other parts so guaranteed the In component of the active layer in the part that forms end face window structure.In this case, in substrate, form recess and do not need to form end face window structure, and can eliminate the precipitous step of generation in comprising the nitride type III-V compound semiconductor layer of active layer by the shape of suitably selecting mask, make and to suppress the fiber waveguide loss.In addition, owing to need not excavate semiconductor layer in the part that is used for by RIE formation end face window structure, thus do not form surface level, and can prevent from when laser operation, to take place light absorption or amount of localized heat generation.In addition, when at least a portion that is formed on the recess of mask upside when the growth by nitride type III-V compound semiconductor layer has been filled insulating material, can relax because the caused step of recess (level error), make and in step subsequently, form under the situation of dielectric film or electrode etc., can form the parts that to be formed well, can not produce step and bring out interruption etc.
In the 5th to the 7th embodiment of the present invention that constitutes as mentioned above, near the part that band-gap energy changes, on substrate, form the mask that comprises dielectric film, and growing nitride type III-V compound semiconductor layer on the part that does not have masked covering on the substrate, wherein, because it is very little that the In diffusion length is compared with the Ga diffusion length,, thereby changed band-gap energy so the In component in the nitride type III-V compound semiconductor layer in the part is changed near mask.In addition, when at least a portion that is formed on the recess of mask upside when the growth by nitride type III-V compound semiconductor layer has been filled insulating material, can relax because the caused step of recess (level error), make and in step subsequently, form under the situation of dielectric film or electrode etc., can form the parts that to be formed well, not bring out interruption etc. and can not produce into step.
According to embodiments of the invention, the semiconductor laser of nitride type III-V compound semiconductor can be realized using, wherein, end face window structure can be easily formed, the fiber waveguide loss can be suppressed, and light absorption or localized heat generation can be prevented from when laser operation, to take place.By being used as or being used for the defect semiconductor laser of the light source of shaven head, can realize the high-performance compact disk device.
In addition, according to embodiments of the invention, the nitride type III-V compound semiconductor layer that can grow easily and comprise In and Ga at least and have the part that band-gap energy changes at least one direction.
Description of drawings
Figure 1A and Figure 1B illustrate plane graph and the sectional view that is used in the sample in the basic research of being undertaken by the present inventor respectively;
Fig. 2 A and Fig. 2 B illustrate the sectional view that is used in the sample in the basic research of being undertaken by the present inventor;
Fig. 3 illustrates in the sample that is used in the basic research of being undertaken by the present inventor emission wavelength along with SiO 2The schematic diagram that the width of film mask changes with change at interval;
Fig. 4 illustrates in the sample that is used in the basic research of being undertaken by the present inventor emission wavelength along with SiO 2Another schematic diagram that the width of film mask changes with change at interval;
Fig. 5 A, Fig. 5 B and Fig. 5 C are the schematic diagrames of the distribution of Ga concentration, In concentration and In component when on being used in by the sample in the basic research that the present inventor carried out growing InGaN layer is shown;
Fig. 6 is illustrated in the sample that is used in the basic research of being undertaken by the present inventor, at SiO 2Interval between the film mask keeps under the constant situation Δ X1 and Δ X2 along with SiO 2The change of film mask width and the schematic diagram that changes;
Fig. 7 is illustrated in the sample that is used in the basic research of being undertaken by the present inventor, at SiO 2The width of film mask keeps under the constant situation Δ X1 and Δ X2 along with SiO 2The change at the interval between the film mask and the schematic diagram that changes;
Fig. 8 is the plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Fig. 9 A and Fig. 9 B are the sectional views that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 10 A and Figure 10 B are another sectional views that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 11 A, Figure 11 B and Figure 11 C are sectional views again that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 12 A, Figure 12 B and Figure 12 C are the another sectional views that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 13 is the perspective view that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 14 is another plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 15 is a sectional view again that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 16 is another perspective view that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 17 A, Figure 17 B and Figure 17 C are sectional views again that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 18 is the another plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 19 A and Figure 19 B are sectional views again that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 20 is a perspective view again that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 21 is the another plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 22 A, Figure 22 B and Figure 22 C are the another sectional views that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 23 A, Figure 23 B and Figure 23 C are sectional views again that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 24 A, Figure 24 B and Figure 24 C are sectional views again that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 25 A, Figure 25 B and Figure 25 C are sectional views again that is used to illustrate according to the manufacture method of the GaN semiconductor laser of first embodiment of the invention;
Figure 26 is the another sectional view that illustrates according to the GaN semiconductor laser of first embodiment of the invention manufacturing;
Figure 27 is the another perspective view that illustrates according to the GaN semiconductor laser of first embodiment of the invention manufacturing;
Figure 28 A, Figure 28 B and Figure 28 C are sectional views again that illustrates according to the GaN semiconductor laser of first embodiment of the invention manufacturing;
Figure 29 A and Figure 29 B are perspective view and the sectional views that illustrates respectively according to the detailed structure of the GaN semiconductor laser of first embodiment of the invention manufacturing;
Figure 30 is the plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of second embodiment of the invention;
Figure 31 is the plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of third embodiment of the invention;
Figure 32 is the plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of fourth embodiment of the invention;
Figure 33 is the plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of fifth embodiment of the invention;
Figure 34 is the plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of sixth embodiment of the invention;
Figure 35 is the plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of seventh embodiment of the invention;
Figure 36 is the plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of eighth embodiment of the invention;
Figure 37 is the plane graph that is used to illustrate according to the manufacture method of the GaN semiconductor laser of ninth embodiment of the invention;
Figure 38 is the perspective view that is used to illustrate according to the manufacture method of the surface launching GaN semiconductor laser of eleventh embodiment of the invention;
Figure 39 A and Figure 39 B are respectively the sectional views and the schematic diagram that the distribution of In component and grown layer gross thickness is shown according to the surface launching GaN semiconductor laser of eleventh embodiment of the invention manufacturing;
Figure 40 is the perspective view that is used to illustrate according to the manufacture method of the photonic crystal of twelveth embodiment of the invention;
Figure 41 is another perspective view that is used to illustrate according to the manufacture method of the photonic crystal of twelveth embodiment of the invention;
Figure 42 is the sectional view that is used to illustrate according to the manufacture method of the GaN semiconductor laser of thriteenth embodiment of the invention;
Figure 43 is the sectional view that is used to illustrate according to the manufacture method of the GaN semiconductor laser of thriteenth embodiment of the invention;
Figure 44 is the sectional view that is used to illustrate according to the manufacture method of the GaN semiconductor laser of thriteenth embodiment of the invention;
Figure 45 is the sectional view that is used to illustrate according to the manufacture method of the GaN semiconductor laser of fourteenth embodiment of the invention;
Figure 46 is the sectional view that is used to illustrate according to the manufacture method of the GaN semiconductor laser of fourteenth embodiment of the invention;
Figure 47 is the sectional view that is used to illustrate according to the manufacture method of the GaN semiconductor laser of fourteenth embodiment of the invention;
Figure 48 is the perspective view that is used to illustrate according to the manufacture method of the GaN semiconductor laser of fourteenth embodiment of the invention; And
Figure 49 is the sectional view by the GaN semiconductor laser of the method manufacturing that forms end face window structure according to correlation technique.
Embodiment
Now, embodiments of the invention are described with reference to the accompanying drawings.In addition, in all accompanying drawings relevant with embodiment, identical or corresponding part is by identical symbolic representation.
Fig. 8～Figure 29 shows the manufacture method according to the GaN semiconductor laser of first embodiment of the invention.The GaN semiconductor laser has end face window structure and ridged striped (ridge stripe) structure, wherein, has removed near the part p lateral electrode, the resonator end face, makes the two end portions of resonator all be set to the non-injection region of electric current.
In first embodiment, at first, shown in Fig. 8 and Fig. 9 A and Fig. 9 B, having defined conduct on n type GaN substrate 11 is the chip region 12 of a laser chip finally.Then, in chip region 12, near the resonator end face that finally forms front side and rear side resonator end face by splitting forms position 13,14 and in the both sides that form the ridged fringe position 15 of ridged striped with respect to ridged striped formation position 15 lines symmetrically after a while, form dielectric film mask 16 with ladder plane shape.Here, Fig. 8 is a plane graph, and Fig. 9 A is the sectional view along the line A-A intercepting of Fig. 8, and Fig. 9 B is the sectional view along the line B-B intercepting of Fig. 8.For every pair of parallel edges of each dielectric film mask 16, long limit is positioned at the edge that the ridged striped forms position 15.Dielectric film mask 16 is d in the distance with resonator end face formation position 13,14 1Part have width w 1, and the distance at d 1～d 2Have in the part in the scope width along resonator length direction from w 1The conical in shape that～0 linearity reduces.A limiting examples of size is d 1=20 μ m, d 2=50 μ m and w 1=5 μ m.Can be by such as SiO 2Film, SiN film and Al 2O 3The dielectric film of film constitutes each dielectric film mask 16.For example, on n type GaN substrate 1, form dielectric film, by etching dielectric film is carried out one patterned then, can easily form dielectric film mask 16 by vacuum evaporation, CVD etc.For example, the thickness of dielectric film mask 16 is about 300nm, but is not restrictive.Determine that according to the factors such as characteristic needs of GaN semiconductor laser the ridged striped forms the width of position 15, and usually but the width examples that does not limit is about 1 μ m～20 μ m (or being about 1 μ m～12 μ m).Though in fact chip region 12 repeats with the rectangle pattern on n type GaN substrate 11, only figure 8 illustrates a chip region 12.In addition, though in fact dielectric film mask 16 is being formed on the resonator length direction in two or more adjacent chips district 12, only figure 8 illustrates the dielectric film mask 16 that in a chip region 12, occurs.The shape and size of chip region 12 shown in Figure 8 only are nonrestrictive examples.
Next, shown in Figure 10 A and Figure 10 B, for example, go up the GaN semiconductor layer that epitaxial growth is used to form laser structure by metal organic chemical vapor deposition (MOCVD) technology n type GaN substrate 11 (they are provided with dielectric film mask 16).Here, Figure 10 A is the sectional view along the line A-A intercepting of Fig. 8, and Figure 10 B is the sectional view along the line B-B intercepting of Fig. 8.As the GaN semiconductor layer that is used to form laser structure, particularly, order epitaxial growth n type AlGaN coating 17, n type GaN light waveguide-layer 18, unadulterated Ga 1-xIn xN (quantum well layer)/Ga 1-yIn yN (barrier layer, x〉y) active layer 19 of multi-quantum pit structure, unadulterated InGaN light waveguide-layer 20, unadulterated AlGaN light waveguide-layer 21, p type AlGaN electronic barrier layer 22, the unadulterated AlGaN superstructure of p type GaN/ coating 23 and p type GaN contact layer 24.Here, for example, in 900 ℃～1100 ℃ scope, be provided as the growth temperature of n type AlGaN coating 17, n type GaN light waveguide-layer 18, unadulterated AlGaN light waveguide-layer 21, p type AlGaN electronic barrier layer 22, the unadulterated AlGaN superstructure of p type GaN/ coating 23 and the p type GaN contact layer 24 of no In layer.On the other hand, for example, in 700 ℃～800 ℃ scope, be provided as the Ga that contains the In layer 1-xIn xNGa 1-yIn yThe active layer 19 of N multi-quantum pit structure and the growth temperature of unadulterated InGaN light waveguide-layer 20.In addition, in the following description, as required, these layers that form laser structure will be collectively referred to as GaN semiconductor layer 25.
The growth raw material that are used for the GaN semiconductor layer are as follows.The raw-material limiting examples that is used for Ga comprises triethyl-gallium ((C 2H 5) 3Ga, TEG) and trimethyl gallium ((CH 3) 3Ga, TMG); The raw-material limiting examples that is used for Al comprises trimethyl aluminium ((CH 3) 3Al, TMA); The raw-material limiting examples that is used for In comprises triethylindium ((C 2H 5) 3In, TEI) and trimethyl indium ((CH 3) 3In, TMI); And the raw-material limiting examples that is used for N comprises ammonia (NH 3).As dopant, the limiting examples of n type dopant comprises silane (SiH 4), and the limiting examples of p type dopant comprises two (methyl cyclopentadiene) magnesium ((CH 3C 5H 4) 2Mg), two (ethyl cyclopentadiene) magnesium ((C 2H 5C 5H 4) 2Mg) and two (cyclopentadiene) magnesium ((C 2H 5) 2Mg).In addition, the limiting examples of employed carrier gases comprises H during the growing GaN semiconductor layer 2Gas.The flow-rate ratio of the material of the material of V group element and III family element (V/III than) general but non-limiting value are 10 3～10 6Scope interior (for example, about 10 5).In addition, the limiting examples of the pressure during growth is 760 holders (normal pressure).
In this case, n type AlGaN coating 17, n type GaN light waveguide-layer 18, active layer 19, unadulterated InGaN light waveguide-layer 20, unadulterated AlGaN light waveguide-layer 21, p type AlGaN electronic barrier layer 22, the unadulterated AlGaN superstructure of p type GaN/ coating 23 and p type GaN contact layer 24 be not growth on isolation masks 16 basically, but only grows on the part that is not insulated film mask 16 coverings on the n type GaN substrate 11.Can utilize well-known method, easily realize this growth by selecting growth conditions.In this case, growing period at n type AlGaN coating 17, for ridged stripe-shaped in the zone between a pair of dielectric film mask 16 becomes the growth at 15 places, position, not only Al atom and Ga atom directly are provided to this zone from the growth raw material, and provide Al atom and Ga atom to the dielectric film mask 16 also to be provided to this zone (growth is had contribution) from the growth raw material by the diffusion on the dielectric film mask 16 in these regional both sides.Therefore, the thickness of the n type AlGaN coating 17 in the zone between a pair of dielectric film mask 16 is greater than the thickness in other zone.Here, for each dielectric film mask 16, the distance that forms position 13,14 with the resonator end face is d 1～d 2The part at place has from w 1The width that～0 linearity reduces, making provides ridged striped to this zone to form the Al atom of position 15 and the amount of Ga atom reduces gradually along resonator length direction from dielectric film mask 16.As a result, the thickness of n type AlGaN coating 17 increases towards resonator end face formation position 13,14 gradually along resonator length direction in this zone.On the other hand, for each dielectric film mask 16, the distance that forms position 13,14 with the resonator end face is d 1Part have constant width w 1, make that the Al atom and the Ga atomic weight that provide ridged striped to this zone to form the position from isolation masks 16 are constant along resonator length direction.As a result, the constant thickness of the n type AlGaN coating 17 in this zone.This is equally applicable to n type GaN light waveguide-layer 18.
On the other hand, growing period at the active layer 19 that comprises In and Ga, in order to form the growth at 15 places, position in the zone between a pair of dielectric film mask 16 at the ridged striped, not only In atom and Ga atom directly are provided to this zone from the growth raw material, and provide In atom and Ga atom to the dielectric film mask 16 also to be provided to this zone (growth is had contribution) from the growth raw material by the diffusion on the dielectric film mask 16 in these regional both sides.In this case, because (for example in the growth temperature of active layer 19,700 ℃～800 ℃) down the diffusion length of In atom is than the little about magnitude of diffusion length of Ga atom, so provide the ridged striped to this zone to form the In atomic weight of position 15 less than the Ga atomic weight from dielectric film mask 16.As a result, the In component of active layer 19 becomes inhomogeneous along resonator length direction; Particularly, the In component that becomes and be lower than other parts corresponding to the In component of part in zone between a pair of dielectric film mask 16.Therefore, the band-gap energy in this part is higher than the band-gap energy in the other parts, and therefore, this part will finally become the end face window structure district.This is equally applicable to the growth of unadulterated InGaN light waveguide-layer 20.
The growth of each of unadulterated AlGaN light waveguide-layer 21, p type AlGaN electronic barrier layer 22, the unadulterated AlGaN superstructure of p type GaN/ coating 23 and p type GaN contact layer 24 all is similar to the growth of n type AlGaN coating 17 and n type GaN light waveguide-layer 18.
Next, shown in Figure 11 A, go up formation dielectric film 26 at the GaN semiconductor layer 25 (the superiors of P type GaN contact layer 24) that forms laser structure, dielectric film 26 is scribbled resist (resist) 27 then.The limiting examples of dielectric film 26 is SiO 2Film.Subsequently, the photomask 28 that provides the mask pattern of reservation shape by use exposes resist 27.
Next, shown in Figure 11 B, so the resist 27 of selectivity exposure stands to develop, thereby forms opening 27a.The flat shape of opening 27a is the shape of stripes corresponding to the ridged shape of stripes that forms after a while (with the identical shape of shape of ridged striped formation position 15).In fact, form a plurality of such opening 27a abreast, but only show an opening 27a here with preset space length.
Subsequently, shown in Figure 11 C, come etching dielectric film 26 by using resist 27 as etching mask, to form opening 26a.For example, using SiO 2Under the situation of film as dielectric film 26, can carry out wet etching by using the hydrofluoric acid etch agent, but be not limited to this.
Next, shown in Figure 12 A, resist 27 is kept intact, form Pd film 29 and Pt film 30 in proper order by for example vacuum evaporation from direction with the surperficial quadrature of n type GaN substrate 11.Here, the thickness of Pt film 30 is set, makes that in case finish and be used to form the dry ecthing that RIE that the ridged striped carried out handles subsequently, Pt film 30 will etched substantially, stay very little thickness, for example, thickness that 5nm is following or the thickness below the 3nm.Especially, for example, the thickness of Pd film 29 is 150nm, and the thickness of Pt film is 30nm, and these values are not limited thereto.
Subsequently, resist 27 is removed (peeling off) with the Pd film 29 and the Pt film 30 that form on it.Therefore, shown in Figure 12 B, form Pd film 29 and Pt film 30 with the shape of stripes of extending in one direction.The Pd film 29 of shape of stripes is identical with the width that the ridged striped forms position 15 with the width of Pt film 30, for example is 1 μ m～20 μ m, but is not limited thereto.
Next, shown in Figure 12 C, dielectric film 26 is etched.Using SiO 2Under the situation as dielectric film 26, for example, carry out wet etching by using the hydrofluoric acid etch agent, but be not limited thereto.Figure 13 is the perspective view that this state is shown, and Figure 14 is the plane graph that this state is shown.
Subsequently, as shown in figure 15,, for example, be that the RIE of etching gas handles 25 dry ecthings of GaN semiconductor layer to desired depth, to form ridged striped 31 by using chlorine when the Pd film 29 that uses shape of stripes and Pt film 30 during as etching mask.In a single day in this case, as mentioned above, the thickness of Pt film 30 is set, makes and finish dry ecthing, Pt film 30 is just etched substantially, stays very little thickness, for example, and the thickness that thickness that 5nm is following or 3nm are following; Therefore, in the whole process of dry ecthing, Pd film 29 is always covered by Pt film 30.Therefore, needn't worry that the Pd deposition of being undertaken by the sputter on Pd film 29 surfaces can cause the roughening of etched surfaces during dry ecthing, and needn't worry that this roughening can give rise to trouble maybe can produce bad influence in the processing of carrying out subsequently the reliability of laser.For example, the rate of etch that RIE handles can be 0.01 μ m/min to Pt film 30, can be 0.13 μ m/min to GaN semiconductor layer 25.For example, the height of ridged striped 31 is 0.4 μ m～0.65 μ m, but is not limited thereto.Figure 16 is the perspective view that this state is shown.For example, the ridged striped 31 p type GaN/ intermediate depth of doped with Al Ga superstructure coating 23 not that can be formed into GaN semiconductor layer 25.So the Pd film 29 of the shape of stripes that finally stays and Pt film 30 constitute p lateral electrode 32.
Next, shown in Figure 17 A, order forms such as SiO on whole surface 2The dielectric film 33 of film and such as the dielectric film 34 of unadulterated Si film, be formed on the resist pattern (not shown) that has opening in the zone corresponding to ridged striped 31 thereon by photoetching process subsequently, and by using the resist pattern optionally to etch away the part of on ridged striped 31 film 33 and 34 as mask.After this, remove the resist pattern.Then, comprise that the whole surface in the zone of Pd film 29 and Pt film 30 is scribbled resist 35, and expose resist 35 by the photomask 36 that use is provided with the mask pattern of reservation shape.
Next, shown in Figure 17 B, the resist 35 that selectivity like this is exposed stands to develop, to form opening 35a.Figure 18 is the plane graph that this state is shown.The sectional view that Figure 17 B intercepts corresponding to the line B-B along Figure 18.The flat shape of opening 35a is that beam overall is that 2a (forms width on the resonator length direction of position 13,14 every sides and is a) and length overall is the rectangle of 2b (length of the every side of ridged striped 31 center lines is b) at the resonator end face.
Subsequently, shown in Figure 17 C,, use chloroazotic acid to carry out wet etching, to etch away extremely thin Pt film 30 and the Pd film 29 that stays by resist 35 as etching mask.Here, chloroazotic acid to the rate of etch of Pt film 30 with the rate of etch of Pd film 29 is compared very low.But,,, after this, can etch away Pd film 29 with enough rate of etch so can etch away Pt film 30 at short notice because Pt film 30 is extremely thin.For example, chloroazotic acid is about 50nm/min to the rate of etch of Pd film 29.By this way, can etch away Pd film 29 and Pt film 30 among the opening 35a of resist 35 fully.
Next, shown in Figure 19 A and Figure 19 B, remove resist 35.Figure 20 is the perspective view that the state of such acquisition is shown, and Figure 21 is the plane graph of this state.Here, Figure 19 A is the sectional view along the line A-A intercepting of Figure 21, and Figure 19 B is the sectional view along the line B-B intercepting of Figure 21.
Subsequently, shown in Figure 22 A, on the whole surface in the zone that comprises Pd film 29 and Pt film 30, form dielectric film 37 by vacuum evaporation etc.The limiting examples of dielectric film 37 is SiO 2Film.For example, the thickness of dielectric film 37 can be 200 μ m, but is not limited thereto.
Next, shown in Figure 22 B, dielectric film 37 is coated with resist 38, and exposes resist 38 by the photomask 39 that use is provided with the mask pattern of reservation shape.For example, the thickness of resist 38 can be 0.8 μ m, but is not limited thereto.
Subsequently, shown in Figure 22 C, so the resist 38 of selectivity exposure stands to develop, and forms opening 38a with the upside at ridged striped 31.
Next, shown in Figure 23 A, for example, handle dark etching resist 38 and dielectric film 37, to etch away the dielectric film 38 of ridged striped 31 upsides, to expose Pt film 30 by RIE.
Subsequently, shown in Figure 23 B, remove resist 38.
Next, shown in Figure 23 C, apply resists 39 to dielectric film 37 and Pt film 30, and by utilizing chlorobenzene to handle to harden the surface of resist 39, to form hardened layer 40.For example, the gross thickness of resist 39 and hardened layer 40 can be 3.0 μ m, but is not limited thereto.Subsequently, the photomask 41 that is provided with corresponding to the mask pattern of the shape of isolated electrode by use exposes hardened layer 40.
Next, shown in Figure 24 A, resist 39 that so exposes and hardened layer 40 stand to develop, to form the opening 42 of reservation shape.In this case, hardened layer 40 has towards the outstanding eaves shape in the inside of opening 42.
Subsequently, shown in Figure 24 B, resist 39 and hardened layer 40 are kept intact, for example, by forming Ti film, Pt film and Ni film in proper order, to form Ti/Pt/Ni film 43 from vacuum evaporation with the direction of the surperficial quadrature of n type GaN substrate 11.The limiting examples of the structure of Ti/Pt/Ni film 43 is that undermost Ti film has 10nm thickness, and the Pt film has 100nm thickness, and the Ni film of the superiors has 100nm thickness.
Next, resist 39 and hardened layer 40 are removed (peeling off) with the Ti/Pt/Ni film 43 that forms on it.In this case, because hardened layer 40 has towards opening 42 inner outstanding eaves shapes, so can easily carry out strip operation.By this way, shown in Figure 24 C, formed the isolated electrode 44 that comprises Ti/Pt/Ni film 43.
Subsequently, shown in Figure 25 A, to whole surface-coated resist 45, to cover isolated electrode 44, then by utilizing chlorobenzene to handle to harden the surface of resist 45, to form hardened layer 46.For example, the gross thickness of resist 45 and hardened layer 46 can be 3.0 μ m, but is not limited thereto.Next, use the photomask 47 be provided with corresponding to the mask pattern of pad electrode shape to expose resist 45 and hardened layer 46.
Subsequently, shown in Figure 25 B, resist 45 that so exposes and hardened layer 46 stand to develop, to form the opening 48 of reservation shape.In this case, hardened layer 46 has towards opening 48 inner outstanding eaves shapes.
Next, shown in Figure 25 C, resist 45 and hardened layer 46 are kept intact, for example, by coming order to form Ti film, Pt film and Au film, thereby form Ti/Pt/Au film 49 from vacuum evaporation with the direction of the surperficial quadrature of n type GaN substrate 11.The limiting examples of the structure of Ti/Pt/Au film 49 is the thickness that orlop Ti film has 10nm, and the Pt film has the thickness of 100nm, and the superiors' Au film has the thickness of 300nm.
Subsequently, resist 45 and hardened layer 46 are removed (peeling off) with the Ti/Pt/Au film 49 that forms on it.In this case, because hardened layer 46 has towards opening 48 inner outstanding eaves shapes, so can easily carry out strip operation.By this way, as shown in figure 26, form the pad electrode 50 that comprises Ti/Pt/Au film 49.
Next, for example, form n lateral electrode 51 by the dorsal part of peeling off the n type GaN substrate 11 of method in each chip region 12.
Subsequently, the n type GaN substrate 11 that is provided with laser structure in the above described manner stands to form along the resonator end face operations such as splitting of position 13,14, with the formation laser bar, thereby forms two resonator end faces.Next, the resonator end face stands end face and applies, and laser bar stands operations such as splitting then, thereby they are divided into chip.
By this way, made target GaN semiconductor laser.
Figure 27 and Figure 28 A, Figure 28 B and Figure 28 C show the GaN semiconductor laser of the chip form of acquisition like this.Here, Figure 27 is a perspective view, and Figure 28 A is the sectional view along the line A-A intercepting of Figure 27, and Figure 28 B is the sectional view along the line B-B intercepting of Figure 27, and Figure 28 C is the sectional view along the line C-C intercepting of Figure 27.In this GaN semiconductor laser, the width from each resonator end face along resonator length direction is the zone of a, do not have to form the p lateral electrode 32 that comprises Pd film 29 and Pt film 30, and these zones are as the non-injection regions of electric current.
Figure 29 A and Figure 29 B show the detailed structure of GaN semiconductor laser.Here, Figure 29 A is a perspective view, and Figure 29 B is the sectional view along the line B-B intercepting of Figure 29 A.
According to the first embodiment of the present invention, can obtain following advantage.Only by on n type GaN substrate 11, forming the GaN semiconductor layer 25 that dielectric film mask 16 and growth thereon are used to form laser structure in advance, the band-gap energy that just the resonator end face can be formed the active layer 19 in 13,14 near zones of position is provided with greater than other regional band-gap energy, makes to form end face window structure easily.In addition, the thickness of the GaN semiconductor layer 25 between a pair of dielectric film mask 16 in the zone forms position 13,14 along resonator length direction towards the resonator end face and increases gradually, makes not generate precipitous step.Therefore, as in according to the semiconductor laser of correlation technique shown in Figure 49, opposite with the semiconductor layer that is used to form laser structure in the situation that from each zone of the depression 101a scope outside, has how much precipitous steps to it, can suppress the fiber waveguide loss significantly.In addition, do not need to excavate the semiconductor layer that forms laser structure and form end face window structure by RIE, make and to have avoided when forming end face window structure, forming surface level, and can avoid because caused light absorption or the problem that generates of amount of localized heat when laser operation of this surface level.
In addition, according to first embodiment, can easily make and have ridged striped 31 with respect to comprising the Pd film 29 that forms with shape of stripes and the GaN semiconductor layer of the structure that the p lateral electrode 32 of Pt film 30 forms with self-aligned manner, wherein, near the part of the p lateral electrode 32 two resonator end faces is removed, and makes two end faces of resonator be used as the non-injection region of electric current.By two end faces as the resonator of the non-injection region of electric current, the GaN semiconductor laser can prevent the calamitous optical damage (COD) to the resonator end face effectively, thereby has prolonged the life-span and improved reliability.
Now, with the manufacture method of describing according to the GaN semiconductor laser of second embodiment of the invention.
In a second embodiment, at first, as shown in figure 30, the ridged striped form a side of position 15 and on resonator length direction along the whole length of resonator, on n type GaN substrate 11, form long dielectric film mask 16 with fixed width.Core on resonator length direction, ridged striped form a coincident of edge with the ridged striped formation position 15 of dielectric film mask 16 on 15 sides of position.Yet, be d forming position 13,14 distances with each resonator end face 1Part in, edge of dielectric film mask 16 and ridged striped form position 15 and are spaced apart w at interval 1, and be d forming position 13,14 distances with each resonator end face 1～d 2Part in, at interval from w 1Be decreased to 0 gradually.A limiting examples of size is d 1Be 20 μ m, d 2Be 50 μ m, the width of dielectric film mask 16 is 5 μ m, and w 1Be 5 μ m～10 μ m.
Next, in the same manner as in the first embodiment, for example, go up the GaN semiconductor layer 25 that growth is used to form laser structure at n type GaN substrate 11 (being provided with dielectric film mask 16) by mocvd method.In this case, for the active layer 19 that comprises In and Ga, be d in each distance with resonator end face formation position 13,14 2Part in, compare with the middle body on the resonator length direction, it is bigger to form the distance of position 15 from the edge of dielectric film mask 16 to the ridged striped.Therefore, for In atom that provides on dielectric film mask 16 and Ga atom, In atom (its diffusion length is than the little about magnitude of Ga atom) provides at distance d in the mode than Ga atom less amount 2Ridged striped in the interior part forms position 15.As a result, the In component of active layer 19 becomes inhomogeneous along resonator length direction.Especially, ratio is lower in other parts near the part of the In component resonator end face forms position 13,14, and the band-gap energy near 13,14 parts of end face formation position is greater than the band-gap energy in the other parts.Therefore, the part that band-gap energy is bigger in the active layer 19 is as end face window structure.
After this, carry out step subsequently in the same manner as in the first embodiment, thus manufacturing objective GaN semiconductor laser.
According to second embodiment, can obtain the advantage identical with first embodiment.
Now, with the manufacture method of describing according to the GaN semiconductor laser of third embodiment of the invention.
In the 3rd embodiment, at first, as shown in figure 31,, form at the ridged striped on each side of 15 both sides, position with the line symmetrical manner, on n type GaN substrate 11, form the dielectric film mask 16 that uses in a second embodiment.A limiting examples of size is d 1Be 20 μ m, d 2Be 50 μ m, the width of dielectric film mask 16 is 5 μ m, and the interval w between dielectric film mask 16 and the ridged striped formation position 15 1 Be 3 μ m～20 μ m.
Next, in the same manner as in the first embodiment, for example, go up growing GaN semiconductor layer 25 at n type GaN substrate 11 (being provided with dielectric film mask 16) by mocvd method.In this case, for the active layer 19 that comprises In and Ga, be d forming position 13,14 distances with the resonator end face 2Part in a pair of dielectric film mask 16 between the zone in, compare with the zone line on the resonator length direction, the interval between the dielectric film mask 16 is bigger, and it is bigger to form the distance of position 15 from the edge of dielectric film mask 16 to the ridged striped.Therefore, for In atom on the dielectric film mask 16 on these regional both sides that are provided between a pair of dielectric film mask 16 and Ga atom, In atom (its diffusion length is than the little about magnitude of Ga atom) provides to distance d in the mode than Ga atom less amount 2Ridged striped in the interior part forms position 15.As a result, the In component of active layer 19 becomes inhomogeneous along resonator length direction.Especially, ratio is lower in other parts near the resonator end face formation position 13,14 of In component between a pair of dielectric film mask 16 the part, and the band-gap energy near 13,14 parts of end face formation position is greater than the band-gap energy in the other parts.Therefore, the part that band-gap energy is bigger in the active layer 19 is as end face window structure.
After this, with first embodiment in identical mode carry out subsequently step, with manufacturing objective GaN semiconductor laser.
According to the 3rd embodiment, can obtain the advantage identical with first embodiment.
Now, with the manufacture method of describing according to the GaN semiconductor laser of fourth embodiment of the invention.
In the 4th embodiment, at first, shown in figure 32, the ridged striped form a side of position 15 and on resonator length direction along the whole length of resonator, on n type GaN substrate 11, form long dielectric film mask 16 with fixed width.Forming position 13,14 distances with each resonator end face is d 1Part in, the ridged striped forms the w that is spaced apart between the edge of edge and ridged striped formation position 15 of dielectric film mask 16 of position 15 2, and the distance be d 1～d 2Part in, at interval increase to w from the w2 linearity 3, the mid portion on resonator length direction reaches w 3Here, for example, select w with degree ground with Δ X1 among Fig. 5 C 2, and with Fig. 5 C in Δ X2 with degree or bigger the w that selects 3A limiting examples of size is d 1Be 20 μ m, d 2Be 50 μ m, the width of dielectric film mask 16 is 5 μ m, w 2Be 3 μ m～5 μ m, and w 3Be 10 μ m.
Next, in the same manner as in the first embodiment, for example, go up the GaN semiconductor layer 25 that growth is used to form laser structure at n type GaN substrate 11 (being provided with dielectric film mask 16) by the MOCVD method.In this case, for the active layer 19 that comprises In and Ga, with Δ X1 among Fig. 5 C with degree be chosen in each distance that forms position 13,14 with the resonator end face and be d 2Part in the edge of dielectric film mask 16 and ridged striped form the distance of position 15, and in the mid portion on resonator length direction, with Δ X2 among Fig. 5 C with degree or bigger the edge of dielectric film mask 16 and the distance that the ridged striped forms position 15 selected; Therefore,, be lower than in the other parts near the part of the In component resonator end face forms position 13,14, and the band-gap energy near the part the end face formation position 13,14 is greater than the band-gap energy in the other parts as Fig. 5 C finding.Therefore, the part that band-gap energy is bigger in the active layer 19 is as end face window structure.
After this, carry out step subsequently in the same manner as in the first embodiment, with manufacturing objective GaN semiconductor laser.
According to the 4th embodiment, can obtain the advantage identical with first embodiment.
Now, with the manufacture method of describing according to the GaN semiconductor laser of fifth embodiment of the invention.
In the 5th embodiment, at first, as shown in figure 33, to form position 15 line symmetrical manner with respect to the ridged striped, near the resonator end face forms position 13,14 and the ridged striped form the both sides of position 15, the formation flat shape is the dielectric film mask 16 of rectangle on n type GaN substrate 11.The edge of each dielectric film mask 16 of ridged striped formation position 15 sides and the coincident that the ridged striped forms position 15.Each dielectric film mask 16 all has fixing width w on resonator length direction 4A limiting examples of size is d 2Be 20 μ m～50 μ m, and the width of dielectric film mask 16 is 5 μ m～10 μ m.
Next, in the same manner as in the first embodiment, for example, go up the GaN semiconductor layer 25 that growth is used to form laser structure at n type GaN substrate 11 (being provided with dielectric film mask 16) by the MOCVD method.In this case, for the active layer 19 that comprises In and Ga, be d in each distance with resonator end face formation position 13,14 2Part in, for In atom on the dielectric film mask 16 that offers these part both sides and Ga atom, In atom (its diffusion length is than the little about magnitude of Ga atom) offers the ridged striped in the mode less than the amount of Ga atom and forms position 15, and the situation in the mid portion on this situation and the resonator length direction is different.As a result, the In component of active layer 19 becomes inhomogeneous along resonator length direction.Especially, be lower than in other parts near the part of the In component resonator end face of part between a pair of dielectric film mask 16 forms position 13,14, and the band-gap energy near 13,14 positions, end face formation position is greater than the band-gap energy in the other parts.Therefore, the part that band-gap energy is bigger in the active layer 19 is as end face window structure.
After this, carry out step subsequently in the same manner as in the first embodiment, with manufacturing objective GaN semiconductor laser.
According to the 5th embodiment, can obtain the advantage identical with first embodiment.
Now, with the manufacture method of describing according to the GaN semiconductor laser of sixth embodiment of the invention.
In the 6th embodiment, at first, as shown in figure 34, to form position 15 line symmetrical manner with respect to the ridged striped, near the resonator end face forms position 13,14 and on the both sides of ridged striped formation position 15, forming flat shape on n type GaN substrate 11 is trapezoidal dielectric film mask 16.The ridged striped forms the edge of each the dielectric film mask 16 on 15 sides of position and the coincident that the ridged striped forms position 15.The width of each dielectric film mask 16 is d forming position 13,14 distances with each resonator end face 2In part in from w 5Linearity is decreased to w 6A limiting examples of size is d 2Be 20 μ m～50 μ m, w 5Be 10 μ m～20 μ m, and w 6Be 5 μ m.
Next, in the same manner as in the first embodiment, for example, go up the GaN semiconductor layer 25 that growth is used to form laser structure at n type GaN substrate 11 (being provided with dielectric film mask 16) by the MOCVD method.In this case, for the active layer 19 that comprises In and Ga, be d in each distance with resonator end face formation position 13,14 2Part in, In atom and Ga atom for the dielectric film mask 16 that offers these part both sides, In atom (its diffusion length is than the little about magnitude of Ga atom) offers the ridged striped in the mode less than the amount of Ga atom and forms position 15, and the situation in the mid portion on this situation and the resonator length direction is different.As a result, the In component of active layer 19 becomes inhomogeneous along resonator length direction.Especially, be lower than in other parts near the part of the In component resonator end face of part between a pair of dielectric film mask 16 forms position 13,14, and the band-gap energy near 13,14 positions, end face formation position is greater than the band-gap energy in the other parts.Therefore, the part that band-gap energy is bigger in the active layer 19 is as end face window structure.
After this, carry out step subsequently in the same manner as in the first embodiment, with manufacturing objective GaN semiconductor laser.
According to the 6th embodiment, can obtain the advantage identical with first embodiment.
Now, with the manufacture method of describing according to the GaN semiconductor laser of seventh embodiment of the invention.
In the 7th embodiment, directly on n type GaN substrate 11, do not form dielectric film mask 16, but instead, for example, in any one of first to the 6th embodiment, on the whole surface of n type GaN substrate 11, after the epitaxial growth n type AlGaN coating 17, on n type AlGaN coating 17, form dielectric film mask 16.After this, in the same manner as in the first embodiment, order epitaxial growth n type GaN light waveguide-layer 18, active layer 19, unadulterated InGaN light waveguide-layer 20, unadulterated AlGaN light waveguide-layer 21, p type AlGaN electronic barrier layer 22, the unadulterated AlGaN superstructure of p type GaN/ coating 23 and p type GaN contact layer 24.An example of growth back state has been shown among Figure 35.For example, Figure 35 is corresponding to the sectional view along the line A-A of Fig. 8 intercepting.
After this, carry out step subsequently in the same manner as in the first embodiment, with manufacturing objective GaN semiconductor laser.
According to the 7th embodiment, can obtain the advantage identical with first embodiment.
Now, with the manufacture method of describing according to the GaN semiconductor laser of eighth embodiment of the invention.
In the 8th embodiment, as shown in figure 36, on n type GaN substrate 11, in the process of definition chip region 12, on resonator length direction, the abandoned stope 52 that goes out of use the most at last is set between located adjacent one another each is to contiguous chip region 12.Each edge of abandoned stope 52 all forms position 13,14 with the resonator end face and overlaps.Form position 13,14 with the resonator end face elongation dielectric film mask 16 of width less than abandoned stope 52 is set in each abandoned stope 52 abreast.The width of dielectric film mask 16 is not less than 5 μ m usually, for example, is not less than 10 μ m, but is not limited to this value.
Next, in the same manner as in the first embodiment, for example, go up the GaN semiconductor layer 25 that growth is used to form laser structure at n type GaN substrate 11 (being provided with dielectric film mask 16) by the MOCVD method.In this case, for the active layer 19 that comprises In and Ga, for In atom that offers dielectric film mask 16 and Ga atom, In atom (its diffusion length is than the little about magnitude of Ga atom) is provided for the ridged striped that forms in the part that position 13,14 has preset distance with each resonator end face in the mode less than the amount of Ga atom and forms position 15.As a result, the In component of active layer 19 becomes inhomogeneous along resonator length direction.Especially, be lower than in other parts near the part of the In component resonator end face forms position 13,14, and the band-gap energy near 13,14 positions, end face formation position is greater than the band-gap energy in the other parts.Therefore, the part that band-gap energy is bigger in the active layer 19 is as end face window structure.
After this, carry out step subsequently in the same manner as in the first embodiment, with manufacturing objective GaN semiconductor laser.In case form the resonator end face, just that abandoned stope 52 is discarded.
According to the 8th embodiment, can obtain the advantage identical with first embodiment.
Now, with the manufacture method of describing according to the GaN semiconductor laser of ninth embodiment of the invention.
In the 9th embodiment, as shown in figure 37,, on resonator length direction, between each chip region 12 located adjacent one another, abandoned stope 52 is set, and in each abandoned stope 52, dielectric film mask 16 is set vicinity in the mode identical with the 8th embodiment.In addition, on the resonator end face formation position 13,14 and the having a rest property ground, central area (dashed line form) between the ridged striped formation district 15 every pair of vicinity little width ridged stripe-shaped dielectric film mask 16 is set.
Next, in the mode identical, for example, go up the GaN semiconductor layer 25 that growth is used to form laser structure at n type GaN substrate 11 (being provided with dielectric film mask 16) by mocvd method with the 8th embodiment.In this case, the In component that the resonator end face forms near position 13,14 parts is lower than other parts, and the band-gap energy near 13,14 parts of resonator end face formation position is greater than other parts.In the mode identical with the 8th embodiment, the part that band-gap energy is bigger in the active layer 19 constitutes end face window structure; Yet it is noted that on the dielectric film mask 16 that is arranged on intermittent structure on the resonator end face formation position 13,14 does not have growth to be used to form the GaN semiconductor layer 25 of laser structure.
After this, carry out step subsequently in the same manner as in the first embodiment, with manufacturing objective GaN semiconductor laser.In this case, when forming the resonator end face, since the GaN semiconductor layer 25 that is used to form laser structure do not appear at intermittently be arranged on the resonator end face form on the dielectric film mask 16 on the position 13,14 and the resonator end face to form the mechanical strength at 13,14 places, position lower, so can be easily and carry out forming the splitting of position 13,14 definitely along the resonator end face.
According to the 9th embodiment, can obtain the advantage identical with first embodiment.
Now, with the manufacture method of describing according to the GaN semiconductor laser of tenth embodiment of the invention.
GaN semiconductor laser among this embodiment has window construction and ridged striated structure, and is that with the difference of first embodiment two end portions of resonator is not made into the non-injection region of electric current.
According to the tenth embodiment, except the advantage that in first embodiment, obtains because the two end portions of resonator is made into the structure of the non-injection region of electric current, can obtain the advantage identical with first embodiment.
Now, with the vertical resonator surface launching GaN semiconductor laser of describing according to eleventh embodiment of the invention.Figure 38 and Figure 39 A show surface launching GaN semiconductor laser.Here, Figure 38 is a perspective view, and Figure 39 A is the sectional view along the line A-A intercepting of Figure 38.
Shown in Figure 38 and Figure 39 A, on n type GaN substrate 11, form dielectric film mask 16 with circular open 16a.For example, the diameter of opening 16 can be about 20 μ m～30 μ m, but is not limited thereto.Next, order epitaxial growth bottom AlGaN coating 53, active layer 19, top AlGaN coating 54, p type DBR layer 55 and p type GaN contact layer 56.At the dorsal part epitaxial growth n of n type GaN substrate 11 type DBR layer 57.Active layer 19 has unadulterated Ga 1-xIn xN (quantum well layer)/Ga 1-yIn yN (barrier layer, x〉y) multi-quantum pit structure.P type DBR layer 55 comprises semiconductor multi layer film, wherein, alternately piles up p type Al zGa 1-zN layer and p type Al wGa 1-wThe N layer (wherein, z〉w, 0＜z, and w＜1); For example, these layers are stacked 25 circulations, to obtain the gross thickness of about 3 μ m.N type DBR layer 57 comprises semiconductor multi layer film, wherein, alternately piles up n type AlN layer and n type GaN layer; For example, these layers are stacked 35 circulations, to obtain the gross thickness of about 4 μ m.
In this case, because dielectric film mask 16 has opening 16a, so provide diametric(al) to increase gradually to the amount of the Al atom of opening 16a inside and Ga atom along opening 16a from dielectric film mask 16.As a result, the thickness of the bottom AlGaN coating 53 in this zone along with along the diametric(al) of the opening 16a of dielectric film mask 16 before the center of opening 16a and then reduce gradually.In the central area of opening 16a, the Al atom that is provided from the dielectric film mask 16 and the amount of Ga atom are constant on the diametric(al) of opening 16a.As a result, the thickness of bottom AlGaN coating 53 is constant in this zone.When growth activity layer 19, except directly In atom and Ga atom being offered the inside of opening 16a of dielectric film mask 16, from the growth raw material, provide to the In atom and the Ga atom of dielectric film mask 16 and also be provided to this zone (growth is had contribution) by diffusion from the growth raw material.In this case, because the diffusion length of the following In atom of the growth temperature (for example, 700 ℃～800 ℃) of active layer 19 is than the little about magnitude of Ga atom, so near the part opening 16a edge, the In component of active layer 19 reduces.Therefore, the In component of active layer 19 is once more along with increasing towards core.As a result, the In component of active layer 19 becomes inhomogeneous along the diametric(al) of opening 16a.Especially, near the In component the opening 16a in the part is lower than other parts, make band-gap energy in this zone be higher than the band-gap energy in the other parts, and this part forms low-index regions.On the other hand, because the In component in the central area of opening 16a is higher,, and should form high-index regions in the zone so the band-gap energy in should the zone diminishes.
Next, for example, in the central area of the opening 16a of dielectric film mask 16, circular p lateral electrode 32 is set on p type GaN contact layer 56.Subsequently, at the dorsal part of n type GaN substrate 11, on n type DBR layer 57, annular n lateral electrode 51 is set.
Figure 39 B shows the distribution of the gross thickness of In component (refractive index) in the cross section shown in Figure 39 A and grown layer.
According to the 11 embodiment, between the mid portion of the GaN semiconductor layer that is used to form laser structure and its outside, can produce the difference of refractive index by an epitaxial growth, thereby can in the middle body of resonator, limit light.Therefore, the surface launching GaN semiconductor laser that can easily realize having the low-threshold power current density and need very little operating current.
Now, with the manufacture method of describing according to the photonic crystal of twelveth embodiment of the invention.
In the 12 embodiment, as shown in figure 40, on n type GaN substrate 11, form the dielectric film mask 16 of a plurality of circular open 16a with two-dimensional array.In this case, have identical diameter, and progressively increase (for example, in 5 μ m～100 mu m ranges, progressively increasing) at the diameter of the opening 16a of each y direction array at the opening 16a of each x direction array.As shown in figure 41, be provided with growing InGaN layer 58 on the n type GaN substrate 11 of dielectric film mask 16 thereon.As a result, in each opening 16a inside, on n type GaN substrate 11 with cylindrical growing InGaN layer 58.In this case, along with the increase of the diameter of InGaN layer 58, the In component of InGaN layer 58 is higher.Therefore, refractive index progressively changes along the y direction.
According to the 12 embodiment, can comprise the photonic crystal of the two-dimensional array of the InGaN layer 58 that refractive index progressively changes along a direction by an epitaxial growth manufacturing.
Incidentally, the shape of dielectric film mask 16 split shed 16a is not limited to circle, but for example can be ellipse.In addition, for example, InGaN layer 58 can grow into taper shape.
Now, with the manufacture method of describing according to the GaN semiconductor laser of thriteenth embodiment of the invention.
In the 13 embodiment, as shown in figure 42, execution in step in the same manner as in the first embodiment, thereby growth is used to form the GaN semiconductor layer 25 such as the laser structure of active layer 19 on the part that is not insulated film mask 16 coverings on the n type GaN substrate 11, the recess 59 that will be formed on dielectric film mask 16 upsides then by the growth of GaN semiconductor layer 25 is filled with insulating material 60, the surface of smooth to obtain (complanation).Especially, for example,, thereby recess 59 is filled with insulating material 60, removes solvent by heat treatment subsequently by the phosphorus doping inorganic silicate SOG of spin-coating method coating as insulating material 60, thus curable dielectric material 60.Alternatively, by methods such as sputter or vacuum evaporations, will as insulating material 60 such as polyimides or SiO 2Deng organic material be coated on whole surface region, recess 59 is filled with insulating material 60, after this, etching insulating material 60 is until exposing GaN semiconductor layer 25.
Next, for example, on the surface of planarization in the above described manner (complanation), form such as SiO 2The dielectric film (not shown) of film turns to predetermined shape by etching with the dielectric film pattern then.Subsequently, as shown in figure 43, by dielectric film as etching mask, for example, by use chlorine be the RIE method of etching gas with 25 dry ecthings of GaN semiconductor layer to desired depth, to form groove 61,62, between groove 61,61, form ridged striped 31.Next, though stay as the dielectric film former state of etching mask, order forms such as SiO on whole surf zone 2The dielectric film 33 of film and such as the dielectric film 34 of unadulterated Si film, be formed on the resist pattern (not shown) that has opening in the zone corresponding to ridged striped 31 by photoetching then, and pass through the resist pattern as mask, remove the dielectric film 33,34 that ridged striped 31 upsides exist by etching selectivity ground.After this, remove the resist pattern.By these steps, in the zone of groove 61,62 outsides, form very thick on the whole dielectric film 33,34.Here, the dielectric film 33 in groove 61,62 perimeters comprises the dielectric film as etching mask.
Subsequently, as shown in figure 44, on ridged striped 31, form p lateral electrode 32, in addition, form pad electrode 50, to cover p lateral electrode 32.
After this, carry out required step, with manufacturing objective GaN semiconductor laser.
According to the 13 embodiment, except the advantage identical, can also obtain following advantage with first embodiment.Because the recess 59 that is formed on dielectric film mask 16 upsides by the growth that is not insulated GaN semiconductor layer 25 on the part that film mask 16 covers on the n type GaN substrate 11 is filled with insulating material 60 and obtains flat surfaces and eliminate by recess 59 caused surface steps, so can carry out the dielectric film 33,34 in the later step and the formation of pad electrode 50 well, not bring out interruption etc. and can not generate step.
Now, with the manufacture method of describing according to the GaN semiconductor laser of fourteenth embodiment of the invention.
In the 14 embodiment, as shown in figure 45, with the mode execution in step identical with the 4th embodiment, thereby growth is used to form the GaN semiconductor layer 25 such as the laser structure of active layer 18 on the part that is not insulated film mask 16 coverings on the n type GaN substrate 11, after this, the recess 59 that growth by GaN semiconductor layer 25 is formed on dielectric film mask 16 upsides is filled with insulating material 60, thereby obtains smooth surface.Especially, for example,, thereby be recess 59 fill insulants 60, remove solvent and curable dielectric material 60 by heat treatment then by the phosphorus doping inorganic silicate SOG of spin-coating method coating as insulating material 60.Alternatively, by methods such as sputter, deposition to whole surface region apply as insulating material 60 such as polyimides or SiO 2Deng inorganic material, thereby be recess 59 fill insulants 60, dark then etching insulating material 60 is until exposing GaN semiconductor layer 25.
Next, for example, on the surface of planarization (leveling), form in the above described manner such as SiO 2The dielectric film (not shown) of film turns to reservation shape by etching with the dielectric film pattern then.Subsequently, as shown in figure 46, by dielectric film as etching mask, for example, by use chlorine be the RIE method of etching gas with 25 dry ecthings of GaN semiconductor layer to desired depth, to form groove 61,62, between groove 61,61, form ridged striped 31.Next, though stay as the dielectric film former state of etching mask, order forms such as SiO on whole surf zone 2The dielectric film 33 of film and such as the dielectric film 34 of unadulterated Si film, be formed on the resist pattern (not shown) that has opening in the zone corresponding to ridged striped 31 by photoetching then, and pass through the resist pattern as mask, remove the dielectric film 33,34 that ridged striped 31 upsides exist by etching selectivity ground.After this, remove the resist pattern.By these steps, in the zone of groove 61,62 outsides, form very thick on the whole dielectric film 33,34.Here, the dielectric film 33 in groove 61,62 perimeters comprises the dielectric film that is used as etching mask.
Subsequently, as shown in figure 47, on ridged striped 31, form p lateral electrode 32, in addition, form pad electrode 50 to cover p lateral electrode 32.In Figure 48, schematically shown the perspective view of representing this state.
After this, carry out required step, with manufacturing objective GaN semiconductor laser.
According to the 14 embodiment, except the advantage identical, can also obtain following advantage with first embodiment.Because being filled with insulating material 60 by the recess 59 that is formed on dielectric film mask 16 upsides in the growth that is not insulated GaN semiconductor layer 25 on the part that film mask 16 covers on the n type GaN substrate 11 obtains flat surfaces and eliminates by recess 59 caused surface steps, so can carry out the dielectric film 33,34 in the later step and the formation of pad electrode 50 well, not bring out interruption etc. and can not produce step.
Though when having specifically described embodiments of the invention above, the invention is not restricted to the foregoing description, but can carry out various modifications based on technology of the present invention.
For example, above numerical value, structure, substrate, processing of being mentioned among the embodiment etc. only be example, if desired, also can use and top mentioned different numerical value, structure, substrate, processing etc.
Especially, for example, though in the first, second, third, the 5th and the 6th embodiment, the edge of dielectric film mask 16 is positioned at the edge that the ridged striped forms position 15, but the edge that dielectric film mask 16 can be formed dielectric film mask 16 is positioned at the edge position spaced that forms position 15 with the ridged striped.
In addition, as required, can make up two or more among above-mentioned first to the tenth embodiment.
It should be appreciated by those skilled in the art, multiple modification, combination, recombinant and improvement to be arranged, all should be included within the scope of claim of the present invention or equivalent according to designing requirement and other factors.

Claims (17)

1. the manufacture method of a semiconductor laser, comprise that by growth on substrate the nitride type III-V compound semiconductor layer of the active layer that contains the nitride type III-V compound semiconductor that comprises indium and gallium at least makes, described semiconductor laser has end face window structure, said method comprising the steps of:
At least near the described substrate the position that forms described end face window structure, form the mask that comprises dielectric film; And
Growth comprises the described nitride type III-V compound semiconductor layer of described active layer on the part that is not covered by described mask on the described substrate.
2. the manufacture method of semiconductor laser according to claim 1 wherein, near the described position that forms described end face window structure and in the one or both sides of the position that forms laser stripe, forms described mask on described substrate.
3. the manufacture method of semiconductor laser according to claim 1, wherein, so that form the described position of described laser stripe and the interval between the described mask near the described position that forms described end face window structure less than in other regional mode, along the described position that forms described laser stripe, on the described substrate of a side of the described position that forms described laser stripe, form described mask.
4. the manufacture method of semiconductor laser according to claim 1, wherein, so that in the described mask near the interval between those parts of the both sides, described position that form described laser stripe is forming the described position of described end face window structure greater than in other regional mode, along the described position that forms described laser stripe, on the described substrate of the both sides of the described position that forms described laser stripe, form described mask.
5. the manufacture method of semiconductor laser according to claim 1, further comprising the steps of:
Growth comprises after the described nitride type III-V compound semiconductor layer of described active layer on the described part that is not covered by described mask on described substrate, with at least a portion of filling insulating material formed recess on the upside of described mask.
6. the manufacture method of semiconductor laser according to claim 5, wherein, with the described recess of described filling insulating material, to form smooth surface.
7. the manufacture method of semiconductor laser according to claim 5, wherein, described insulating material comprises application type insulating material, organic material, oxide or nitride.
8. a semiconductor laser has end face window structure, and described semiconductor laser has the nitride type III-V compound semiconductor layer that comprises the active layer that contains the nitride type III-V compound semiconductor that comprises indium and gallium at least on substrate,
Wherein, the mask that comprises dielectric film is formed at least on corresponding near the described substrate the part of described end face window structure, and
The described nitride type III-V compound semiconductor layer that comprises described active layer is formed on the described substrate not on the part that is covered by described mask.
9. semiconductor laser according to claim 8, wherein, at least a portion of recess that is formed on the upside of described mask is filled with insulating material.
10. semiconductor laser according to claim 9, wherein, described recess is filled out with described insulating material, to form smooth surface.
11. a shaven head, with semiconductor laser as or be used for light source,
Wherein, described semiconductor laser has the end face window structure that has the nitride type III-V compound semiconductor layer that comprises the active layer that contains the nitride type III-V compound semiconductor that comprises indium and gallium at least on substrate,
The mask that comprises dielectric film is formed at least on corresponding near the described substrate the part of described end face window structure, and
The described nitride type III-V compound semiconductor layer that comprises described active layer is formed on the described substrate not on the part that is covered by described mask.
12. an optical disc apparatus, with semiconductor laser as or be used for light source,
Wherein, described semiconductor laser has the end face window structure that has the nitride type III-V compound semiconductor layer that comprises the active layer that contains the nitride type III-V compound semiconductor that comprises indium and gallium at least on substrate,
The mask that comprises dielectric film is formed at least on corresponding near the described substrate the part of described end face window structure, and
The described nitride type III-V compound semiconductor layer that comprises described active layer is formed on the described substrate not on the part that is covered by described mask.
13. the manufacture method of a semiconductor device, at least the nitride type III-V compound semiconductor layer that comprises indium and gallium by growth on substrate is made, described semiconductor layer has band-gap energy in the part that changes at least one direction on the surface of described substrate, said method comprising the steps of:
On near the described substrate the described part that band-gap energy changes, form the mask that comprises dielectric film, and
The described nitride type III-V compound semiconductor layer of growth on the part that is not covered on the described substrate by described mask.
14. the manufacture method of semiconductor device according to claim 13 is further comprising the steps of:
On the described part that on described substrate, is not covered by described mask after the described nitride type III-V compound semiconductor layer of growth, with at least a portion of filling insulating material formed recess on the upside of described mask.
15. a semiconductor device has the nitride type III-V compound semiconductor layer that comprises indium and gallium at least, described semiconductor layer has the part that band-gap energy changes at least one direction along the surface of described substrate,
Wherein, the mask that comprises dielectric film is formed near the described part that band-gap energy changes the described substrate, and
Described nitride type III-V compound semiconductor layer is formed on the described substrate not on the part that is covered by described mask.
16. semiconductor device according to claim 15, wherein, at least a portion of formed recess is filled insulating material on the upside of described mask.
17. the growing method of nitride type III-V compound semiconductor layer on substrate that comprises indium and gallium at least, described semiconductor layer has band-gap energy in the part that changes at least one direction on the surface of described substrate, said method comprising the steps of:
On near the described substrate the described part that band-gap energy changes, form the mask that comprises dielectric film; And
The described nitride type III-V compound semiconductor layer of growth on the part that is not covered on the described substrate by described mask.
CN2008101351847A 2007-10-31 2008-08-13 Semiconductor laser and manufacturing method thereof Expired - Fee Related CN101425659B (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116299856A (en) * 2023-05-19 2023-06-23 中国科学院半导体研究所 Silicon optical coupling structure
CN117096236A (en) * 2023-10-18 2023-11-21 南昌凯捷半导体科技有限公司 Red light LED chip with resonant cavity structure and manufacturing method thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116299856A (en) * 2023-05-19 2023-06-23 中国科学院半导体研究所 Silicon optical coupling structure
CN116299856B (en) * 2023-05-19 2023-07-28 中国科学院半导体研究所 Silicon optical coupling structure
CN117096236A (en) * 2023-10-18 2023-11-21 南昌凯捷半导体科技有限公司 Red light LED chip with resonant cavity structure and manufacturing method thereof
CN117096236B (en) * 2023-10-18 2024-01-26 南昌凯捷半导体科技有限公司 Red light LED chip with resonant cavity structure and manufacturing method thereof

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