JPS6018977A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To prevent the short-circuit generating between an active layer and a current construction layer as well as to contrive improvement in the yield and reliability of a light-emitting element by a method wherein a back diffusion is prevented by reducing the difference in density of impurities. CONSTITUTION:A GaAlAs 2 containing no impurities is superposed on a GaAs substrate 12, Te and Zn are added, and a P type active layer 4, an N-layer 5, an N<+> layer 6 of GaAlAs are successively formed by performing a liquid-phase epitaxial method. At this time, the difference of impurity density between the active layer 4 and the N- layer 5 is reduced. Then, annular P<+> layer 7 reaching the P-layer 3 is formed by diffusing Zn, and subsequently, an annular P type current squeezing layer 10 exactly reaching the intermediate depth of the N-layer 5 is formed on the inner circumference of a P<+> layer 7 by diffusing Zn at the temperature a little lower than the diffusion temperature for a short period of time when the layer 7 is formed. When the above diffusion is performed, the Zn back diffusion layer located in the active layer 4 passes through the N-layer 5 but it does not reach the current squeezing layer 10 and no short-circuit is generated because its density difference is small. Then, a mesa groove reaching the surface of the P-layer 3 is formed along the interface of the layers 7 and 10, electrodes 8 and 9 are attached, they are formed into chips, the layers 2 and 3 are processed into dome-like form, and the semiconductor element is completed.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a method for manufacturing a semiconductor device, particularly a light emitting diode (
The present invention relates to a method of manufacturing a light emitting device.

[Background technology]

The applicant has developed the first near-infrared light emitting diode device for communications.
Develop a light emitting device with the structure shown in the figure. This light emitting element 1 consists of 15~
It has 23 layers 3 with a thickness of 20 μm. This P1 layer 3
has a 0.5 μm thick p-G a Affl in its center.
27 layers (active layer) consisting of As 4+ 8 layers consisting of n-GaA, eAs with a thickness of 1.5 μm, 5.0.7 μm
It has a structure in which N+ layers 6 made of n"-GaAs with a thickness of P
+ layer 7 is formed. A seven-node electrode 8 is provided on the P+ layer 7, and a cathode electrode 9 is provided on the N+ layer 6. Further, for the purpose of current confinement, KZn is diffused halfway into the N+ layers 6 and 8 layers 5 to provide a P+ current confinement layer 1o. When a predetermined voltage is applied between the anode electrode 8 and the cathode electrode 9, such a light emitting element 1 emits near-infrared light 11 at the PN junction at the approximate center of the dome.

However, in such a light-emitting element 1, the Zn diffused into the active layer 4 is absorbed by the heat during the 5Zn diffusion treatment (treatment at 700° C. for 100 minutes) performed to form the P+ layer 7. 5
The inventor of the present invention has found that Ab diffuses into the P+ current confinement layer 10 that is subsequently formed, causing a short-circuit failure.

Therefore, the present inventor studied this pack diffusion and found that the concentration of Te, which is an n conductivity type determining impurity, in the N layer 5 is lXl0 a! I, the concentration of Zn, which is an impurity determining the p conductivity type of the active layer 4, is 5X: 10171
m-3, and Kaoru learned that back diffusion is likely to occur due to the density difference being too large. Then, they realized that back diffusion could be prevented by reducing the density difference by 1, and developed the present invention.

[Object of the Invention] An object of the present invention is to prevent the occurrence of short-circuit defects by preventing back diffusion during heat treatment in the production of conductor elements.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, in the present invention, 27 layers made of p-GaA-#As, p-Q
22 layers (active layer) consisting of a A-# A S, n
N layer made of GaA-#As, N layer made of n-GaAs
After forming the layers by liquid phase epitaxial method, KZn is diffused from the N layer to the 21st layer to form the 21st layer of P+ conductivity type in a donut shape. Then, Zn is diffused so as to reach the middle of the N layer [to form a donut-shaped current confinement layer, and mesa etching is performed to reach 20 layers at the interface between the current confinement layer and the P+ layer. , Furthermore, a cathode electrode is formed on the N+ layer, an anode electrode is formed on the P+ layer, and it is made into a chip.

In the method of manufacturing a light emitting element with a dome structure, the diffusion rate of Zn from the active layer to the N layer due to heat during formation of the P+ layer and the current confinement layer is reduced, thereby preventing short circuits between the active layer and the current confinement layer. In order to prevent this, conduction (short circuit) between the active layer and the current confinement layer can be prevented by making the impurity concentration of the N layer similar to the impurity concentration of the active layer in advance, thereby improving the manufacturing yield of light emitting devices. This improves the reliability of the device.

〔Example〕

FIGS. 2(a) to 2(b) are cross-sectional views showing a method of manufacturing a dome-shaped light emitting element (light emitting diode) that emits near-infrared light according to an embodiment of the present invention.

In this embodiment, as shown in FIG. 2(a), a 300 μm thick
A wafer 13 having an undoped GaA-gAs body 2 having a certain thickness is prepared.

Next, by liquid phase epitaxial method, 15 to 20 pm
P8 layer made of p-GaAJIAs with a thickness of 3°; Pt layer (active layer) made of p-GaA-13As with a thickness of 0.5 μm; 4. 1.5μm thick n-Ga
A, 8 layers of eAs 5, 0.7 μm thick n
An N+ layer 6 made of "-GaA swamp As is sequentially formed. At this time, f'e is used as the n-conductivity WLm determining impurity, and Zn is used as the p-conductivity type determining impurity. In order to reduce the pack diffusion rate of Zn, the Zn concentration of the active layer 4 is increased from 5 to 101, for example.
7m-3, the Te concentration of the 8th layer 5 is, for example, 3 to 5.
The density difference is made small by approximating it to X10 011 .

Next, Zn'L is diffused from the main surface of the wafer 13, and
A doughnut-shaped P+ layer 7 extending up to layer 3 is formed by conventional photoetching and diffusion techniques. In addition,
This Zn diffusion is performed by processing at 700° C. for 100 minutes.

Next, a donut-shaped p-type current confinement layer 10 is formed on the inner periphery of the P+ layer 7 to a depth halfway through the eight layers 5 using conventional photoetching and diffusion techniques. In this diffusion process, in order to accurately diffuse Zn into the middle depth of the 1.5μ thin 8-layer 5, the temperature was lowered to 675°C compared to the diffusion temperature of 700°C when forming the P+ layer 7. , and the processing time is 20 minutes since the diffusion depth is shallow.
Make it as short as minutes.

In this diffusion process, Zn in the active layer 4 undergoes pack diffusion into the N layer 5, but the respective impurity concentrations in the active layer 4 and 8 layer 5 are 5 to 1017an-3 and 3 to 5X1017□□□-3. Approximately, the concentration difference is compared with that of the structure shown in Figure 1.

As a result, the pack diffusion layer (not shown) is 8
The current does not pass through the layer 5 and reach the current confinement layer 10, and no short-circuit failure occurs.

Next, donut-shaped mesa etching is performed along the interface between the P+ layer 7 and the current confinement layer 10. Mesa etching is performed so as to extend beyond the active layer 4 and reach the surface layer 21 of the layer 30. Further, an anode electrode 8 is formed on the surface of the P+ layer 7, and a cathode electrode 9 is formed on the surface of the N+ layer 6.

Furthermore, the Ueno 13 is divided into lattice shapes and made into chips, and the GaAgAs body portion is processed into a dome shape to produce a light emitting element 1 with a dome structure as shown in the same figure (d). do.

By applying a predetermined voltage between the anode electrode 8 and the cathode electrode 9, such a light-emitting element 1 emits near-infrared light 11 from the PN junction located approximately at the center of the dome.

〔effect〕

(1) Since the light emitting device of the present invention has a small impurity concentration difference between the active layer and the thin N layer adjacent thereto, the amount of bank diffusion of impurities in the active layer to the N layer ( rate) is small. Therefore, it is possible to prevent the pack diffusion layer from passing through the N layer and reaching the current confinement layer, which has the same conductivity type as the active layer, making it possible to prevent the occurrence of short circuit defects, and providing a highly reliable light emitting device. I can do it.

(2) From (1) above, it is possible to prevent the occurrence of short circuit defects in light emitting device manufacturing, thereby improving yield.
This has the effect that a highly reliable light emitting element can be manufactured at low cost.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. That is, the concentration values of Zn and Te may also be other than those in the examples. However, T
If the e concentration is increased to, for example, lXl018m, -3, the crystallinity will deteriorate, so care must be taken.

Furthermore, the present invention is similarly applicable to cases where there is a risk of short-circuiting occurring in the pack diffusion in an element structure in which a region of the same conductivity type as the pack diffusion layer is formed in the direction in which the pack diffusion advances after heat treatment.

[Application field]

In the above explanation, the invention made by the present inventor was mainly applied to the light emitting diode manufacturing technology, which is the background field of application, but the invention is not limited thereto. It can also be applied to manufacturing. At least, manufacturing of a semiconductor device having a structure in which a region of another conductivity type exists between regions of the same conductivity type, and there is a risk that a pair of regions of the same conductivity type may become electrically connected due to pack diffusion during heat treatment during manufacturing. It can be applied to certain semiconductor device manufacturing methods.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a light emitting device developed by the present applicant, and FIGS. 2(a) to 2(d) are sectional views showing a method for manufacturing a light emitting device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Light emitting element, 2... G a A-g As body, 3... 23 layers, 4... 23 layers (active layer), 5...
・N layer, 6... N layer, 7... P' layer, 8... anode electrode, 9... cathode electrode, 10... current confinement layer, 11 ・Near infrared light, 12 ...G a As plate, 13... Wafer.

Claims (1)

[Claims] 1. A method for manufacturing a semiconductor device, comprising the steps of simultaneously or separately forming a second conductivity type region sandwiching a first conductivity type region, and a heat treatment step, the method comprising the steps of: The impurity concentration in one or both of the second conductivity type regions is set so that the type determining impurity is diffused into the first conductivity type region or the first conductivity type formation region and the two cylinder conductivity type regions are not electrically conductive. A method for manufacturing a semiconductor device, characterized in that the impurity concentration is approximated to that of a first conductivity type region.