JPS6151890A - Manufacture of buried type semiconductor laser - Google Patents

Abstract

PURPOSE:To shallow diffusion depth, and to improve reproducibility by introducing an impurity to a quantum well active layer in one-dimensional manner. CONSTITUTION:An N-Ga0.52Al0.48As clad layer 12, a quantum well active layer 15, a P-Ga0.52Al0.48As clad layer 14 and a P-GaAs ohmic contact layer 15 are grown on an N-GaAs substrate 11 in a crystalline shape, and a photo-resist 16 is formed onto the layer 15. In this case, the clad layer 12 is 2.5-3.0mum thick, the active layer 13 takes an N type or a P type and is formed by growing GaAlAs barrier layers in thickness such as 150Angstrom and well layers by GaAs layers in thickness such as 80Angstrom in five or ten layers, the clad layer 14 is 1.5- 2.0mum thick, and the ohmic contact layer 15 is 0.5-1.0mum thick. Mesa etching reaching the clad layer 12 is conducted while using the resist 16 as a mask. A P type impurity is introduced under the state to shape an impurity introducing layer 17. The impurity is diffused in a diffusion furnace and diffusion depth of approximately 1mum is obtained regarding impurity introduction at that time.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for manufacturing a semiconductor laser, and in particular to a method for manufacturing a semiconductor laser, particularly a buried semiconductor laser having a quantum well (1.1 dimple) active layer.
This article relates to an I-making method.

[Technical background of the invention and its problems] The semiconductor Rayleigh' using up to the Roti well 11'1 is known to have a short oscillation wavelength and high oscillation efficiency. ■ Up to the secondary well 114, the active layer of the so-called double hetero 1743 is formed thinly to less than 1 degree Hf' of the matter wave of carriers in the crystal, and the energy is 8.
It is a structure that causes a child to wake up.

Hereinafter, a description will be given using a GaApAS-based ω-kotsukido structure as an example. In general, it is known that a 1°11 structure becomes disordered due to high-temperature treatment or the introduction of impurities, and the isolateral refractive index becomes the average value of the surrounding burr layer.
61 is used to realize light to the embedding 11 as shown in FIG. Here, 81 is one more than p-GaAS, 8
2 ft l) -Gr'' 8ffi A Si, 83 is a filtration layer including a burr layer and a well layer, 84 is n-G a A I
Optical Rad ffl by AS, 85 is n-G
a1~S ohmic] one layer. The quantum well layer activity 83 is GJ]ΔflAs barrier layer (,',”+
a A S or Aff's small'! jigaaffi
As well 'Pb'! i, here h) 了Y[
It has a multiple minimum well structure where multiple door notifications can be made. The fact that 83 in the figure is displayed with multiple lines indicates this. In addition, the area 86 in the figure is the P Virgin 1 area where Zn is diffused, and the area 86 and 83 are located in the town 11 (Koj Hope 1.: Il! This area is the embedded area.As a result, optically
Confinement is achieved by a cladding layer of 83° and 86° and an amorphous region.

Next, we will explain that it is possible to confine current in this 1"4 structure. From the above, it can be concluded that the pn junction of this 1" structure is formed in the area where 84, 86, and 83 are in contact. However, p in contact with the ω well active layer 83
There is a relatively clear diffusion type difference between the n junction and the pn junction of the QaAffiAS cladding layer 84.
Although it varies depending on the content of i, it is about 0.2 to 0.3 [eV] in the commonly used Sfl composition.

Therefore, in the construction of this (layer resistance) and this diffusion type (
Considering the difference, the inflow current ratio of ε36 from 8 ll and embedded from 84 ζ83/\ can be determined. By setting this ratio to 18 degrees, it is possible to determine the current confinement factor at the current level used. ,,L! , :
, in this structure 85(,2aA S ohmic-
1 contact layer is 86 f electricity 1j m (, 21 non-conducting is Oa A 5 layer (this is formed) n l
This is because the diffusion potential of G;, 1 (than that of IANA 5 layers) may increase the reactive current. Note that this current is 81°82 compared to the n-type or By making 86 an n-type, it can be almost ignored, but if we make 131.82 an n-type or 86 an n-type, a restriction is imposed that 86 must not reach 81. ) come. The structure shown in FIG. 8 thus makes it possible to confine heat and current.

However, such conventional lasers have the following drawbacks.

First, there is the control 1' of the embedding width.

In the conventional method (21j shown in FIG. 8), 111 layers of Zn are diffused by diffusion of about 2 [μm71] or more, which is a considerably deep diffusion (j) for impurity diffusion.

Usually, as the name suggests, impurity diffusion has spatial expansion not only in the vertical direction but also in the horizontal direction. Therefore, a l
Even if diffusion is performed from the upper surface of the semiconductor layer 11 using an impurity diffusion mask, the diffusion will not be performed in the same width as the mask width, and the embedding will be performed in a width narrower than the mask width. In addition, the diffusion profile is as shown in Figure 8 (diffusion source).
The embedding is narrow on the sides and wide on the bottom (diffusion direction) side. And the deeper the diffusion, the larger the child. For this reason,
There is a natural limit to the buried width by diffusion, and since the width on the upper side affects the ohmic contact resistance, a certain width is required, which further limits the buried width. This may sometimes result in unsatisfactory requirements for a single transverse mode waveguide as an embedded waveguide. , J:
In order to perform deep diffusion, the so-called abnormal diffusion11 (
(Proceed to expansion j1 under the mask.

Differences in diffusion rates often occur and reproducibility is poor.

As a method to improve this point, there is a method of introducing an ion immobilization method. The ion implantation method has the advantage that the embedding width is approximately close to the mask width and that the impurity implantation depth b can be all 011 with the accelerating voltage of the device. However, ion implantation requires a large accelerating voltage to deeply introduce impurities, and this has the drawback that the impurity collides with the crystal with high energy, often destroying the crystal. .

Second, there is the problem of current confinement. This is related to the control of the embedding width mentioned above. For example, in the structure shown in FIG. 8, the embedding width can be made sufficiently narrow.
If contact 1 touches 1, the reactive current increases, or the width of 85 becomes too narrow and the resistance of ohmic contact 1 increases. Also, 81.82 is n-type, 84. In Ij and J structures where f+5 is p-type, the diffusion depth should not reach 81 (P h is not <7, and due to the diffusion profile, the embedding width cannot be narrowed by 70%, and the diffusion depth is It is poor in controllability to 111ability.

In this way, ``L Song Kaijio-C had the disadvantage that problems were likely to occur in terms of IFj production technology and heavy industry characteristics due to the deep introduction of impurities. In order to make it shallower, one possibility is to make one layer of flannelette 1 of ε3/l thinner, but since this 1t has the possibility of deteriorating the prohibited 1q property, it is difficult to do so (unlikely).

[of the invention]

The purpose of the tree 51 light is to take advantage of the 111 song of the embedding by ordering, and to improve the reproduction of the 1111 song with a high embedding width.
An object of the present invention is to present a method for manufacturing a buried Y) type semiconductor laser.

[Summary of the Invention] The purpose of the needle of the present invention is to one-dimensionally carry out an inert material test for a quantum well active layer to reduce the diffusion depth and improve reproducibility.

That is, the present invention is based on the manufacturing method of "a buried semiconductor radar having a U-well active layer", in which an 18th conductor is applied to a semiconductor substrate of a first conductivity type through a crack opening, a first or second conductivity type or After at least three layers, the quantum well active layer including the p + Form a mesa deep enough to stop at the bottom of the mesa, and then at the bottom of the mesa, the half η (]J.

Here, 1:11n 'Ibt Hiroto as an egg1rl
i As shown in Figure 1 (C)! Do this in one state (J, i
Introducing a non-stretchable material into the first layer does not mean that the sheet is one-dimensional in the horizontal direction only, and its depth becomes disordered due to embedding. The thickness of the cladding region 11 is approximately 1 μm (1 μm), which is sufficient, and a relatively shallow layer of 29 is sufficient. Therefore, the controllability and reproducibility are higher than the conventional method of two-dimensionally performing deep diffusion of approximately 2 [μm] or more.

Also, in this (I11 configuration, 11.12 is n type, 14°1
Since 5 is set to p IV, the pn lf1 coupling is at the junction between the 12 GaAflAS cladding layers and the impurity-introduced layer 17. For this reason, GaAS ohmic contact h
Even if 1&15 contacts the impurity-introduced layer 17, the reactive current does not increase. Furthermore, expansion ii' at the junction of 12 and 17
1. Den()′L is a quantum well i! i sex h'i 13 and 1
Since the expansion at the junction of It is possible to reproduce the results of Todoroki 1 formation with good reproducibility (9).

〔Effect of the invention〕

A (According to the invention, impurity diffusion into the active layer can be performed one-dimensionally, so the buried semiconductor layer has high controllability of the buried width and high reproducibility.)
4I can do it. In addition, since the ohmic contact layer may be in contact with the impurity-introduced layer, the ohmic contact layer shown in FIG.
This makes it easy to use the same structure, and is also effective in reducing ohmic contact resistance.

(Embodiments of the Invention) The details of the present invention will be explained below with reference to the illustrated embodiments.

1(a) to 1(C) are cross-sectional views, not showing the manufacturing process, of an entrainment type half 8 (4C laser) according to the method of the first embodiment of the present invention, and FIG. FIG. 11 is a cross-sectional view showing the structure of the semiconductor 1 Holley that was fabricated.
As shown in Fig. 1(a)
I]-('-r Ll n-,4△之., on the p plate 11.
4. lAS Ri・2t layer 12゜■ Koido active 1!1. I
J 13, l) -G a, ,,,, /\(2o
,,, AS clad l1J111 and l) -G a
Sixteen AS ohmink contact layers 15 were grown, and 74 resists 1-16 were formed thereon. Here, each 1
14j12, ~. The composition of 15 is Cla-L-Do-1 Hi-I12 has a thickness of 2.5 to 3.0 [11 m], speech 1+J
13 is n type or 1.11') type, for example 150 [people]
Ga Affi △ [5 barrier u and 80 [person 1's Gi\sI Shikaku's J, door 10 was grown in 5 to 10 layers, cladding layer 14 iJ: thickness 1.5 to 2
．． The thickness of the layer 15 was Q, 5-1, 0 [μm1].

Next, as shown in FIG. 1(b), mesa etching was performed to reach the cladding layer 12 using the resist 16 as a mask. In this state, as shown in FIG. 1(C),
(impurity introduction layer 17 was formed. Here, the impurity 11Il force was expanded by 645 ['C] 711 diffusion for about 30 minutes in a furnace, and about 1 [μIIL
The diffusion depth of the culm can be set to 111.

At this expanded depth, for the active layer 13 (Zn diffusion occurs only from the yellow direction, and there is almost no diffusion in the u direction, J1). 1st shift is calculated by subtracting 1st shift of 218 of 1 wide fi 22 squares from the width of <
Tru. 1. t is the embedding width (Zn ripple meter - 1.
．． 5-2, ○ [μIrL] The deviation is good. In other words,
From now on, 11 Akiko will be active lL・j13 as the width of the mesa
In the region of 3.5~ll, OCt1m etc. will be good.

Further, the depth of the n-type GaAj2AS cladding 12 should be 2 to 2.5 [μr/L] remaining +xt:it.

After this, a membrane 18 (for example, 5102.3000) is provided for performing one-selective current injection, and further n-side and n-side
J
:Thus, the embedded type underfill 11 and laser as shown in FIG. 2 are completed. Note that the mold surface metal is 1, for example, CrALl on the n side and UGe/! on the n side. You can use Z.

Thus, according to the Kinomi method, since impurity diffusion is performed with 11 meshes as shown in Figure 1(C), impurity diffusion occurs only in the lateral direction, in one dimension.
Ru. However, Fault 11! The depth of the material introduction (about the thickness of the embedded cranoid I'!rl region (about 1fl)
In)01 minutes. Therefore, H, ? of 2 [#', m] or more? Compared to the two-dimensional method, it is possible to avoid dizziness by controlling the branches and mountains and rivers in a two-dimensional manner.

No. 3121 - ('J 5'l Second implementation of light Ikll
Embedded type lower ij4 It related to the lj method, 11λ approximately l of the rake! ! There is a horizontal cross-sectional view of the structure, marked 11η'1
A 18-green film having the structure shown in Figure 2 was formed by spin coating.

Here, as the IIU 38, a polyimide polymer was used in the first case. 1!1 features of this example are:
The mesa portion can be buried by spin coating and the element surface can be flattened. Flattening allows for easier handling and backing of the device.

Figures 4(a) to (d) are cross-sectional views showing the process of manufacturing a buried semiconductor rake according to the method of the third embodiment of the present invention; This is a TlUi plane view showing the !lλ (14 structure) of the semiconductor laser. This embodiment differs from the previous first embodiment in that the l'8 HV film for embedding the mesa portion is replaced with The purpose is to use n-type or semi-insulating GaAffAs.

That is, in the step not shown in FIG. 1(a), a mask material film (for example, S t 3 N 411
A 2000 people) 41 t'AQ+-Jri. 4(b), the resist 16 and mask material film 41 are etched, and the crystal growth layer is roughly etched. As shown in FIG. 4(d), the resist 1G was removed, and the mask material 4' film 41 was left in place.Next, as shown in FIG. Reasoning layer 42
was formed. The buried crystal growth in the mesa part is n or half sheet i.
, sex, ~1O-CVD method or: I&'! I
Using methods such as F growth method? 1 is fine.

After this, remove the mask (the film 4゛1) and apply the electricity (the 19゜2).
If we take 0 (...), the semiconductor rake shown in FIG. 5 will be completed.

In this structure, the area outside the side of the mesa is n-p-n!
I! E confinement (1°1'1 structure allows for effective E confinement even with large currents.

This makes it possible to use a high-output half-j, ll-k laser.

Note that the present invention is limited to the above-mentioned real/l1li law method, and I:L/,=. For example, as a modification of the '1st embodiment, mesas are roughly provided on both sides of the mesa to provide element supports (1'-1
Alternatively, as a modification of the third example, the mesa may be shaped like an inverted mesa as shown in FIG. In addition, in the first embodiment of the present invention, GaAffiAS system, 14
Although I am talking about materials, it goes without saying that C can also be applied to the materials used in this first turn. Furthermore, as an example of materials and methods for impurity introduction, Zn
However, the object of the present invention can also be achieved by diffusion of S or ion implantation of Si or b. In short, the present invention is its gist)≦
It would be possible to implement it in various ways within the scope of '211R.

[Brief explanation of the drawing]

Figure 1 (E+)-(C) is a cross-sectional view showing the manufacturing process of the theoretical mold lower iM (a, Rayleigh) related to the method of the first embodiment of the present invention. , shows the bλ path 1.1.i structure of the semiconductor Rayleigh fabricated!J
FIG. 3 is a cross-sectional view showing the structure of the semiconductor 1-hole laser according to the method of the second embodiment, and FIG. 4(a)
-(d) is a cross-sectional view showing the process of fabricating the wire (thread warping semiconductor (7)) in the method of the third embodiment;
- indicates the approximate collapse of B of the semiconductor laser manufactured by U'
FIG. 6 is a cross-sectional view for explaining a modified example, and FIG. 8 is a cross-sectional view showing a schematic structure of a conventional embedded semiconductor relay. Provisional, 12...n-GaAQΔ
S ground layer, 13...11j-well active layer, 14.
...ρ-GaAβAS Krat j1"su, 15...p
-GaASJ-Mitsukuconctom°9,16...Photoresist,]7...Impurity-introduced layer, 18.38.
... 5i02 film (, 11 t8 edges), 19.20... Electric (Φ, 41...5i3N411 (J (mask material moon film)
, 42... Embedded layer. 1st opening 2nd figure 30 4th figure 5th figure 6 plate q 7th opening 8th figure

Claims (1)

[Claims] a first conductivity type cladding layer on the first conductivity type semiconductor substrate;
Alternatively, a step of sequentially growing crystals of at least three layers of a quantum well active layer including a second conductivity type or a pn junction and a second conductivity type cladding layer;
A buried semiconductor laser comprising the steps of: forming a mesa with a depth that stops in a conductive cladding layer; and diffusing impurities at the bottom of the mesa to a depth that does not reach the semiconductor substrate. Production method.