DE2425328A1 - OPTOELECTRONIC DIRECTIONAL GUIDANCE AND PROCEDURE FOR THEIR PRODUCTION - Google Patents

Description

Applicant in; Stuttgart, 21 May 1974 _o

Hughes Aircraft Company P2891 S / kg

Centinela Avenue and

Teale Street

Culver City, Calif., V. StoAo

Optoelectronic directional line and Process for their manufacture

The invention relates to an optoelectronic directional line with a semiconductor material that having a forbidden band of selected energy, existing substrate, one in a region of the substrate radiation source formed by a planar pn junction and one in another area of the substrate formed radiation-sensitive detector, the responds to the radiation emitted by the radiation source and lying in a certain wavelength range and generates a corresponding output voltage «

409883/0838 ./.

Optoelectronic directional lines, which are also referred to as insulators or isolators "and to Light sources and photodetectors combined in one unit are included in the optoelectronic Technique known and have been commercially available for several years. Typical building blocks of this type include a light emitting diode or light emitting diode, such as a discrete gallium arsenide, gallium phosphide or gallium arsenide phosphide diode that works along with a discrete detector such as a Silicon Photodetector Enclosed in a Small Package These optoelectronic directional leads have their utility in a variety of ways found optoelectronic applications, for example high quality voltage regulators, subgroup couplers, Operating switches and various types of logic circuits «Furthermore, these Building blocks of such venerable components as coupling transformers and relays as well as amplifier coupling and Feedback Networks Replaced Accordingly, there is no doubt that these building blocks are very interesting and useful are. Such an optoelectronic transfer line is known, for example, from US Pat. No. 3,727,064.

These known optoelectronic directional lines were made using discrete elements for the Light source, the light detector and the intermediate coupling medium for the light waves formed. The light emitting diode is a source of radiation that is widely available commercially today, and so is

409883/0838

the silicon photodetector, the one for the light emitting diodes Has required spectral sensitivity, for several years in optoelectronic Industry generally available «Suitable coupling media, such as a transparent silicone resin, have been used with success to place both the discrete components in a desired spatial relationship to be physically held in the structural unit that forms the directional line and also to provide adequate light coupling between the components and to dissipate heat from these components.

Although the prior art directional lines constructed from discrete components perform a variety of optical coupling functions in a variety of industrial and commercial applications, the nature of the construction of these components does not appear to result in very high volume mass production as is the case with the manufacture of monolithic methods of pail , in which a large number of individual components are produced in batches at the same time _e Therefore, the manufacturers of such optoelectronic directional lines have so far not been able to exploit the advantages of batch production of semiconductor wafers, in which a large number of components are produced simultaneously in a single wafer in a sequence of process steps getting produced. It is evident, therefore, that it would be very desirable to have an economical method of manufacturing such optoelectronic directional lines in batches

O/,

409883 / Q838

Accordingly, the invention is based on the object of a to create novel monolithic optoelectronic directional line that has the same advantages such as the well-known optoelectronic alignment cables made from discrete components their manufacture, however, can be made use of the advantages that result from the at a high level Yield leading process technology, as it is known from the semiconductor planar technology.

This task is achieved in an optoelectronic Eichtung line of the type described above solved that a lying between the radiation source and the detector region of the substrate has a refractive index which is different from the refractive index of the substrate and thereby forms a waveguide, the radiation emanating from the radiation source limited and fed to the detector

The invention also relates to a method for producing such a directional line A variant of this method is a certain area of the substrate with protons of such energy and irradiated in such an amount that they penetrate the surface of the substrate and become semi-insulating therein Form area whose refractive index differs significantly from that of the substrate.

In a preferred embodiment of the invention ion implantation is also used to create the radiation source of the monolithic optoelectronic directional line in the form of a planar pn junction

409883/0838

form. The radiation detector of this arrangement can advantageously also be carried out by ion implantation to form a detector with a pn junction or by a suitable metal vapor deposition technique so that the detector has a Schottky boundary layer has ©

Accordingly, the invention provides a new monolithic optoelectronic directional line and a new method for producing it. Such a directional line causes a high impedance transformation between the connected input and output circuits. The monolithic design enables automatic optical alignment and high optical transmission efficiency between the radiation source and the radiation detector "given the same time, this direction line can in large quantities produced in batches easily as it's been known to the art of planeren semiconductors · in particular, in the use of passivated gallium arsenide ale substrate can directional wires are manufactured according to the invention cause only low costs and at the same time are characterized by high reliability and durability «,

The invention is described in more detail below with reference to the exemplary embodiments shown in the drawing Explained o Those to be taken from the description and the drawing In other embodiments of the invention, features can be used individually or collectively in any desired manner Combination find application «,

409883/0338

- ο -

Pig. 1 illustrates in cross-sections the method steps in the manufacture of a three-pole optoelectronic directional line with a Schottky-C'yp photodetector.

Fig «2 again illustrates in cross sections the individual procedural step «! in the manufacture of a three-pole optoelectronic directional line with a radiation detector that has a pn junction generated by ion implantation having"

Figo 3 illustrates the multiple use of the Ion implantation into a semiconductor substrate to produce a high level of electrical Isolation in a new, four-pole optoelectronic directional line

Figure 4 illustrates a further sequence of method steps for generating an optoelectronic directional line with an epitaxial coupling waveguide between the radiation source and radiation detector

5 illustrates a sequence of method steps for producing an optoelectronic Directional line, through which in the monolithic epitaxial structure of an optoelectronic Directional conduction by ion implantation a radiation detector with a pn junction is formed «

409833/0838

Fig. 1a shows an n-type gallium arsenide substrate 10 with a thickness of the order of 250 to 400 µm, that has a typical specific resistance in the size

-17 / -5 order of 0.01 ohm »cm, which is about. 10 ' beams / cm ^ equals o Prior to lapping and polishing, the GaAs substrate 10 was approximately 500 µm in thickness. A typical process suitable for lapping and polishing the top surface of the substrate 10 involves using an initial wet grinding operation of aluminum oxide (AlpO ^) abrasive with a particle diameter of 0.5 tiBU. Thereafter, the upper surface of the GaAs substrate 10 is chemically etched using a commercially available solution of methyl alcohol and bromine while at the same time the substrate is rubbed with a suitable felt _e through this Surface treatment steps, the thickness of the substrate is usually reduced by 100 to 250 µm.

After the η-type substrate 10 has been chemically polished in the manner indicated, it is turned into a Brought oxidation furnace in which a layer 12 of silicon dioxide is applied, which has a thickness of about 0.15-0.20 µm. The method used to apply the SiOg layer is this sucked "Silox" low temperature glass deposition process, with the silane and oxygen in an oxidation furnace about 380 ° C to react to hydrogen and silicon dioxide according to the following reaction equation to create:

I ₂ .

409883/0838

- ο -

In some cases it can be useful to have an intermediate layer (not shown) made of sprayed-on oxide between det. xaAs substrate IO and the applied To use layer 12 to the surface protection achieved by the SiO ^ mask for the manufactured To improve components, for this purpose, for example the substrate 10 can be arranged in the vicinity of a quartz plate, which itself is rich in energy Ions or protons are bombarded to form SiOp molecules knock out of the platelet and spray onto the adjacent substrate 10 "

Thereafter, the SiO2 ~ layer 12 of the arrangement according to FIG. 1b is covered with a suitable thin layer of a photoresist, such as, for example, the Kodak metal etch resist (KMER) or the Kodak thin film resist (KTFR), and in accordance with known photolithographic ultraviolet exposure and etching process developed in order to form a photoresist mask, not shown in detail, on the SiOp layer 12 for example, hydrofluoric acid (HF) to the upper surface of the structure described wird.dann dab silica in the area of the opening 16 in Fig _o 1c removed to expose in this way a certain surface portion 21 of the GaAs substrate 10 _o Instead could also for removing micromachining with an ion beam can be applied to the exposed silicon oxide layer 12.

409883/0838

The structure provided with a SiOp mask according to FIG. 1c is then brought into an ion implantation chamber in which an ^{ion beam 18 consisting of zinc ions (Zn +} ) enters the exposed section of the surface of the gallium arsenide substrate 10 with a particle energy of approximately

16 2

30 keV and irradiated in an amount of about 10 atoms / cm to form _a p-type region 20. The silicon oxide mask 12 is then removed using hydrofluoric acid and the surface of the substrate is then provided with a new silicon oxide layer 22 as shown in Fig. 1d. For this purpose, again the above-mentioned method used Silox The newly formed silicon oxide film 22 has brought a thickness in the order of 0.15 to 0.2 micrometers ₀ The structure of FIG. Id is in an annealing oven, where it is about three hours at about 900 ° C is annealed to a pn junction at a depth of about 1.0 · in order to generate these ^R J? IEFE can be varied by means of the annealing time and annealing temperature <> with an annealing time of one hour at 900 ⁰ C was added a depth of the pn junction from 0.5 to achieved "by three-hour annealing at 900 ⁰ C was d: _ese depth to be doubled ,,

Thereafter, a thin gold layer is sprayed onto the upper surface of the SiO ₂ layer 22, as shown in FIG. 1e, in order to form a mask layer 24 which is impermeable to protons. This mask layer 24 has a typical thickness on the order of 1 to 1.5 . «* & And is provided with an opening 26 using the ion beam micromachining technique, so that the mask shown in FIG. 1f is produced. This technique requires first

409883/0838

the formation of a photoresist layer, not shown, on the surface of the gold layer 24- and the subsequent Developing the photoresist layer to form a hardened photoresist mask. This mask has a annular opening through which the ion beam used for processing reaches the gold layer in order to achieve the to remove exposed gold sections and the underlying oxide sections by sputtering.

The structure shown in FIG. 1f is then brought into a proton bombardment chamber, in which high-energy protons 28 are injected through the opening 26 of the mask into the gallium arsenide substrate 10 in order to form a hall-insulating ring-shaped area 30 an energy of about 300 1 eV and an amount of about 2 χ 10 ^ protons / cm implantieit to form an approximately 3 "m deep and 5 ois 10 m wide annular Kpnal 30 _o The exact width of the channel 30 is determined by the The desired operating voltage of the detector and the breakdown voltage in gallium arsenide are determined »The breakdown voltage is in the order of magnitude of 5 x 10 ■ V / cm at a channel width of 10 "m about 100 V, of 100 m is about 1000" is V _o, etc. in a linear manner. " It is obvious that the effectiveness of the optical coupling through the waveguide region is reduced when the width of the channel region 30 increases. Therefore, the channel region 30 extends about 2 "m below the approximately 1 m deep light-emitting pn junction 33ι which has been produced by ion implantation is as it shows J ¹ Ig ₀ if »

409883/0838

This pn junction "forms the radiation source of the described monolithic optoelectronic conduc- tors, while the semi-insulating ring-shaped waveguide region 30 forms the optical coupling between the radiation source and the radiation-sensitive detector, which is to be arranged on the outer hand of the semi-insulating ring-shaped channel 30. The above-mentioned proton bombardment destroys the internal crystal structure of the gallium arsenide substrate 10, so that the resistivity of the annular portion 30 to about 10 ohm "cm is increased. This gives the ring-shaped region 30 has a refractive index which is substantially greater than that of the located thereunder substrate 1O ₀ This significant difference in the refractive indices of these adjacent areas leads to good light reflection at the interface $ 1. In this way, the radiation emitted laterally by the pn junction is limited to the annular area 30.

After the proton implantation described above is completed, the structure according to Fig _o 1f is placed in an annealing furnace in which it is annealed one hour between 500 and 600 ⁰ C for about. This annealing step is not necessary, the effect of extending the semi-insulating region 30 to a greater depth than has been already achieved by the proton implantation iat _o In this way, however, a better control of resistivity in the channel reaches 30 and there may be excessive damage in gallium arsenide, caused by the proton bombardment by

4 0 S 8 8 3/0 8 3 8

eliminates the heat treatment in the crystal structure will. Such excessive damage would result in excessive radiation absorption in the waveguide coupling region cause »It can also be useful to re-coat the structure with a SiOp layer to be provided, as described below with reference to Figo 1g will be carried out before this step of the annealing treatment is carried out by such a previous one The surface of the substrate would be better protected during the annealing process if an oxidation such protection is necessary "

After the process steps of proton bombardment and annealing described with reference to Fig. 1f have been completed, the oxide mask 22 and the gold mask 24 _above it are removed by means of a hydrofluoric acid solution o It has been found that hydrofluoric acid etches away the SiOp layer 22 satisfactorily and at the same time the overlying Bold layer 24- removed without attacking the gallium arsenide substrate 10. It is even possible to immerse the structure in hydrofluoric acid so that the hydrofluoric acid etches away the SiOp layer laterally under the gold layer 24- and thereby removes the two surface masks 22 and 24- in less than an hour 24 · does not need to consist of gold, but can also consist of another metal.1 with a high atomic number, such as, for example, tungsten, which adheres well to the SiQp layer 22 _a

40988 3/0838

After the oxide and gold fairies 22 and 24 after Fig. 1f have been removed in the manner described, the implanted ions and protons having Gallium arsenide substrate 10 is again placed in the oxidation furnace and using the Silox process on its upper surface with a further silicon dioxide layer 32 provided, which is a Thickness of about 0.15 to 0.20 µm hato then be below Use of conventional photolithographic photoresist masking After that, openings 34 formed in this new mask layer 32 and etching process are formed opposing surfaces of the substrate 10 using conventional vapor deposition methods as ohmic Contacts serving metal surfaces 36 and 38 applied After the metal surfaces 36 and 38 at the desired Place have been vapor-deposited and on the opposite surfaces of the gallium arsenide substrate 10 adhere sufficiently firmly, the structure according to FIG. 1h is placed in an annealing furnace in which the temperature rises a V / ert is raised sufficient to alloy the metal surfaces 36 and 38 with the substrate 10 and thereby to form good ohmic contacts.

If a conventional gold-germanium alloy is used for the metal surfaces 36 and 38, heating the structure to an alloy temperature of about 450 ° C. for about two minutes leads to a very good ohmic contact at the metal-semiconductor interface of the FIG 1h shown structure ₀ However, low-melting metal alloys are now available for which it is not necessary to keep the temperature so high

409883/0838

as with a gold-germanium alloy. For example, an alloy of 96% indium and 4% silver can be used, in which case the metal surfaces 36 and 38 used to produce the ohmic contact only need to be heated to about 156 ° C In order to produce a good ohmic contact to the g-allium arsenide surface, an alloy of 75% lead and 25% indium could be used instead, in which case temperatures in the range of 275 C are sufficient for well-alloyed ohmic contacts to the metal surfaces 36 and 38 to manufacture. Another alternative is an alloy that consists of 98.88% lead, 0.9% indium and 0.22% gallium and which requires an alloy temperature of around 325 ° ^C. In some cases it may be desirable to use one of these alloys, which come with lower temperatures, if the use of a temperature of 4-50 ° C. for the gold-germanium alloy has the effect of reducing the disturbances caused by the proton bombardment in the waveguide region 30 It is possible that the annealing caused by the annealing lowers the refractive index of the waveguide area too much and thereby reduces the reflection at the interfaces of the waveguide area too much.

After the ohmic contacts 36 and 38 in the described V / eise have been produced, the structure according to Fig. 1h is brought into a conventional metal vapor deposition system, in one to form a Schottky transition suitable metal layer, for example made of aluminum, on the remaining annular opening 34-

409883/0838

is sprayed in the SiOp layer 32 sxi £ in order in this way to produce a contact with a Schottky zone under the metal layer 40 at the interface with the gallium arsenide. Instead of this, the metal layer 4-0 used to produce the Schottky junction can also consist of a multilayer metallization which comprises, for example, layers of titanium, tungsten and gold. Multi-layer metallization is often preferred to a single-layer aluminum layer, since titanium forms an optimal Schottky junction at the interface with the gallium arsenide, while gold has optimal properties for making contact with external electrodes. The intermediate layer of ■ tungsten forms an excellent physical connection and thermal adaptation between the outer titanium and gold layers. Accordingly, it goes without saying that the metal layer 4-0 shown in FIG. II is only a schematic representation and can illustrate a two-, three- or multi-layer metallization _{or the like}

If, during operation, a suitable voltage is applied to the input terminal 42 and the common terminal 44 of the ^? ig. 1i is applied, which acts on this arrangement in the forward direction, a direct current flows through the li ^ htemittenden pn-junction 33 generated by ion implantation , generates the radiation 48 which is directed radially via the V / ellenleiLer coupling region 30 onto the Schottky junction 49

4 0 9 8 8 3 / Cl 8 3 8

The effectiveness of the coupling region 30 naturally depends on several factors, a significant one of which is the difference between the refractive indices of the region 30 and the substrate 10 below it, as has already been mentioned _above Received photon radiation 48 serves to form hole-electron pairs at the biased Schottky junction 49, which in turn has the consequence that the Schottky diode current which flows through the output terminal 50 to an external load (not shown) is increased. This current can, for example, be provided by a suitable load resistor in order to generate an output voltage which is then amplified and processed further in the usual way _{or the like}

The light-emitting pn junction 33 in the gallium arsenide generates infrared radiation with a wavelength from about 0.900 - .. m if the diode is in the described Way is applied in the forward direction. This wavelength is the resulting r> hoton energy inversely proportional, which is greater than the forbidden band energy of the gallium arsenide so therefore the energy of the photons that are emitted from the pn junction 33 and via the waveguide coupling element are transmitted, sufficiently high to in the area of the Schottky junction 49 the above-mentioned hole-electron pairs to generate »This in turn generates the output detector current at the output terminal 50, as it does mentioned above. In arrangements for which

409883/0838

Substrate 10 of the η-type gallium phosphide or gallium arsenic Enide phosphide semiconductors are used, the wavelengths are those of the pn junctions of these others Substances also emitted radiation for a short enough time to absorb the energy of the forbidden band of these materials To overcome, gallium phosphide creates visible red Light of about 0.660; m wavelength, while Galliumars enide phosphide generates radiation with wavelengths in the range of about 0.700 m «

In the following description of the illustrated in FIGS _o 2 to 5 The method and structures according to the description is omitted such process steps and details that übereinstimnen those explained with reference to FIG. 1 process steps and details _o steps as oxide formation, etching, polishing, etc., the illustrated Methods common and well known in the art. However, if these known steps differ in details from those discussed above, such as, for example, the parameters in particle implantation, specific details such as energy and dosage are specifically given

For the production of the optoelectronic sealing line, which is shown in FIG. 2, a substrate 51 made of gallium arsenide with a thickness of 250 to 4-00 m, which has a specific resistance of about 0.01 ohm _o cm, is assumed. This substrate 51 is then placed in an oxidation furnace in which, using the Silox process described above, an SiO ^ layer 52 with a thickness of about 0.15 "to 0.20 .mu.m

o / c

409883/0838

. is formed _o Thereafter w:; shows .g _o 2c, the structure shown in Figure 2b by known photolithographic method, so treated namely, by applying a photoresist mask and etching, that a relatively large opening 56 is formed as F .rd. The structure shown in FIG. 2c is then irradiated with high-energy positive ions 58 in order to form the implantation region 60. Preferably we3. * Uses the positive zinc ions, which are accelerated in a conventional ion implantation chamber, so that it has, under the influence of an accelerating voltage of about 30 keV in the exposed upper surface of in FIG _o 2c illustrated structure "penetrate _o It ^ plantations dosage a typical value of

16 2
10 ions / cm, thereby forming a p-type region 60. After a subsequent annealing process, the pn junction e3 »is sufficient for a supply ^r on about 1.00 * m.

The last-mentioned annealing process is preferably carried out after removal of the oxide mask 52 by means of a hydrofluoric acid solution and the subsequent application of a further oxide layer 62, again using the above-described oil ox method. This further oxide layer 62 is shown in FIG in turn, has a typical thickness of about 0.15 to 0.20 in "in FIG. 2d structure shown is annealed at about 900 ⁰ C for about three hours, transition pn to the above-mentioned depth of the to the by implanting Zn -Ions generated range of about 1 µm to reach au

After the structure shown in FIG. 2d has been annealed it is placed in a gold vapor deposition chamber in which

409883/0838

2 ^ 25328

a thin gold layer 64 is applied with a thickness of about 1 to 1.5 ^m , as S ¹ Xg. 2e showed "This gold layer in turn has the purpose of forming a proton implantation mask that is able to withstand higher particle energies than the SiOp mask, which was used for the relatively low-energy zinc ions. The gold mask for proton implantation is produced In the same way as the above-described production of the mask according to FIG. 1f using the photoresist technique and micromachining; by means of an ion beam. After the mask with its opening 66 has been produced, protons 68 of high energy are radiated into the area of the structure 2f whose Jläche exposed in the region of the opening 66 to an α about 5 m deep, corrupted by proton and _o to provide characterized semi-insulating region 70 if it were transition pn to an annular area of the m by about 2 under the previously formed Typical values extended to 73 for this step are an acceleration voltage of 300 keV and a Dosage of 10 ^ protons / cm _o

The structure shown in Figo 2f is then with a Hydrofluoric acid Ätζlösung brought into contact, whereby the Silicon oxide layer 62 with the overlying gold layer 64 is removed as described above. The structure is then placed in an oxidation furnace, in which again the Silox process is used a new silicon oxide layer 76 is applied, as e3 Fig # 2g shows. After the oxide layer has a thickness has reached from about 0.15 to 0.20 m, the structure

409883/0838

placed in an annealing furnace and heated ^{to 500 to 600 0 G for about one hour.} The new oxide layer 76 not only protects the surface of the structure according to FIG. 2g during the annealing, but is also subsequently used as a permanent passivation oxide mask on the three-pole monolithic optoelectronic sealing line, which is shown in FIG. 2h

After the annealing, the oxide layer 76 according to FIG. 2g is treated using conventional photolithographic processes in such a way that the openings shown in FIG. 2h are formed. Since all of the metallic contacts shown in FIG are generated in a single pass 82 _o after application of the metal surfaces of the structure according to Fig _o 2h is placed in a furnace to the metal contacts 78, 80 and 82 to alloy with d> jm gallium arsenide substrate at a certain temperature, depending on the nature of the metallization depends »as stated above, the required temperature depends on the alloy metals used from _e in the present Auüführungsbeispiel according to Figo 2 h may be a gold-germanium alloy and applied for about two minutes warmed to ⁰ C 4-5O"

In operation, the optoelectronic Kichtungsleitung of Fig. 2h functionally identical with the reference to Fig. 1i optoelectronic direction wiring described serving as the detector pn junction 83 'formed by the zinc implantation of FIG _e 2c been

409883/0838

is applied in the reverse direction in operation, while the light-emitting pn junction 73 is operated with a bias voltage applied in the forward direction. The radiation emitted by the pn junction 73 runs radially through the waveguide coupling region 70, ei ar die Has properties of a semi-insulator with a specific resistance of about 10 ohm _o cm, and is received with a relatively high coupling efficiency in the region of the detector junction 83 biased in the reverse direction. The received radiation generates hole-electron pairs in the vicinity of the pn junction 83, as a result of which a detector output current is generated at the terminals 85 and 87 if these output terminals are connected to an external load (not shown ) The method described is in some respects the same as the method previously described with reference to FIG. 1 and differs from the latter essentially only in that a detector with a pn junction instead of a Schottky junction has been produced on the outer edge of the arrangement

It goes without saying that, if necessary, the mutual positions of the radiation sources described above and detectors with pn junction can be interchanged, so that the detector is the central section of the arrangement and the radiation source occupies the edge region of the arrangement. It is believed that the optical effectiveness this proposed alternative arrangement is not as great as the optjdehe effectiveness of the arrangements

4 09883/0838

according to FIGS. 1i and 2h _o The reason for this is that "in the case of a peripheral light-emitting pn junction, a substantial part of the radiation generated would be radiated outwards through the outer edge of the light source and thus be lost. that facilities, such as a suitable
Reflector near the pn junction of the radiation source,
could be provided in order to prevent such radiation losses with the alternative arrangement «,

Fig. 3a shows an n-type gallium arsenide substrate 90
as a starting material that is doped with chromium and has a very high specific resistance «, this
Material is specially used for the production of a four-pole optoelectronic cable,
is described below, "The specific resistance of 10 'to 10 Ohm.cm of the substrate 90 is significantly higher than the specific resistance of 0.01 0hm _o cm, as it substrates 10 described above
and 51 of FIG. 1 or 2 _{o o} had chromium doped substrates are available from a UE umber suppliers commercially and are usually prepared by the melt chromium is added, from which the GaAs single crystals
The chromium serves to form deep-lying traps in the forbidden band, which trap electrons and - due to the specific resistance of the

7 pulled ^ riütalles to the order of 10 'to 10

0hm _o cm, which corresponds to a concentration of about ^/ ] 0 ^y charge carriers / cm.

409883/0838

Using the same lapping and polishing methods as described above with reference to FIG. 1, the substrate is lapped and polished to a thickness of 250 to 400 '-im. Thereafter, a thin (0.15 to 0.2 <m) Silicon dioxide layer 92 is applied to the surface of the substrate 90 by the above-mentioned SiIox method, as shown in FIG. 3b. Then, the Siliziuindioxid layer 92 is masked with a suitable Photoresxstlack and then etched, as is conventional in photolithography to form a relatively large opening 96, as FIG _o 3c showed This first silicon dioxide layer must be sufficiently thick to to be impermeable to a first implantation of high-energy sulfur ions, which forms a deep implanted n-region 100, which is indicated in FIG an acceleration voltage of about 600 keV and an ion dosage of about 10 ions / cm. The depth of the containing sulfur ions implanted region 100 takes up about 3 / in to when the assembly was annealed after ion implantation at about 900 ⁰ C _o This annealing is not performed immediately, but rather after subsequent implantation of zinc ions.

The structure shown in Figure 3c _o is then etched in 3 lußsäure? To the mask 92 to remove, after which the Silox method is applied again to bring about a further ßiliziumdioxid layer 102 on the surface of once implanted arrangement ,, then is in the

409883/0838

Silicon dioxide layer 102 attached an annular opening, in the usual process steps of photoresist masking and etching can be used. The structure obtained on this yfeise is shown in Fig. 3d The opening 105 determines the width of the area in which an implantation of zinc ions 108 takes place, which accelerates at about 30 keV and in a dose of

/ ic O

about 10 ions / cm applied wei'di ..- ι. This zinc implantation step is identical to the zinc implantation steps described above. ,, The annealing for the sulfur and zinc implantation takes place after the zinc implantation has been completed and after the arrangement shown in Fig. 3d has been cleaned with hydrofluoric acid and a new oxide layer has been applied, as shown in FIG _o 3e "the structure shown in Figure"J> e with the new oxide layer 112 is then placed in an annealing furnace in which it is calcined for about three hours at about 900 G before the application of a gold layer as shown in FIG _o 3f is prepared.

The structure according to Fig _o 3f is prepared by applying a layer of gold generating a mask of photoresist and ion beam micromachining, as has been described above for the structure according to Fig .. 1f and 2f _o The mask is used to the width of the annular To determine opening 116, which is shown in FIG. 3f. Through this opening 116, high-energy protons 118 are penetrated, which also penetrate the previously formed pn junctions 101 and 107 in order to form a waveguide coupling region 122 with a high specific resistance, the one shown in Fig _o 3g

409883/0838

istο The structure according to Pig. 3g has a semi-insulating Area 122 which is annealed after the surface of the gallium arsenide substrate is re-coated with an oxide layer 124 has been provided o Here, too, the Silox-Vt c is used, ixm the oxide layer 124 on the surface of the gallium arsenide substrate before the areas of the proton implantation are heated to about 500 to 600 ° C for about an hour «.

Thereafter, the G _e b: \ _ ILcL _e according to FIG. 3g is masked using conventional photolithographic processes in order to form the illustrated openings in the silicon dioxide layer 124. A number of ohmic contacts 126, 128, 130 and 132 are then formed, all of which are located on the upper surface of the "structure shown in FIG. 3h. Advantageously, the contacts 128, 130 and 132 have an annular shape is required on the back of the substrate no electrode. the forward voltage across the light-emitting pn junctions 125 and 127 is between the center contact 126 and the inner ring contact _o applied 128 which serve as detector transitions 129 and 131 are reverse biased by applying a DC voltage between the middle ring contact 130 and the outer ring contact biased o

The deep, sulfur-implanted area 100 provides for the necessary isolation of the four-pole arrangement according to FIG. 3ho the emitted by the pn junctions 125 and 127

409883 / 0.8 38

Radiation is conducted radially through the semi-insulating annular waveguide coupling region 122 and in the pn detector transitions 129 and 131 collected _a It is noted that the deep implanted with sulfur area 100 both in surface contact with the center electrode 126 and the outer ring electrode 132 is such that all Betriebaspannungen can be supplied to the upper surface of the opto-electric line direction _o This property allows the assembly of the device of Fig. 3h on many types of sockets in which rear Contact Power can not be used.

4 illustrates a sequence of process steps which serve to produce an optoelectronic directional line with epitaxial Schottky junctions. As is understood from a substrate 140, η-type gallium arsenide, whose specific V / esistance is about 0.01 OhiUocm in Auaführungsformen FIGS _o 1 and 2. FIG. On the substrate '.40, an epitaxial layer 142 is applied by one of the many useful Aufdampftechhiken for depositing gallium arsenide is used on gallium arsenide substrates, "One of these techniques is the so-called _o arsenic trichloride method is conducted in which hydrogen by Araentrichlorid to to release elemental arsenic, which in turn is reacted with elemental gallium to form vaporous gallium arsenide, which is then deposited on the gallium arsenide substrate 140. Instead, gallium arsenide epitaxial wafers of the type shown in Figure 4a can be drawn from electronic material manufacturers.

409883/0838

After the formation of the epitaxial gallium arsenide layer 142, a thin silicon dioxide layer 144 is applied to the outer surface of the epitaxial layer 142. For this purpose, the Silox process discussed above can be used again. The silicon dioxide layer; 144 has a typical thickness in the range from 0.15 to 0.2 .mu.m. A photoresist layer (not shown) is then applied to the silicon dioxide layer 144 and treated by conventional photolithographic processes in order to produce a Zinc ions 150 are then radiated through this opening in order to create a p-type region by implantation of the zinc ions Procedures were used. The silicon dioxide hash 144 is then removed from the structure according to FIG. 4c using hydrofluoric acid. A further oxide layer 156 is then applied to the epitaxial gallium arsenide layer implanted with zinc ions, as shown in FIG. 4d. Then, the arrangement according to Fig. 4d annealed for three hours at about 900 ⁰ G

Thereafter, the oxide layer 156 is coated with a not shown Photoresist masked according to the usual Developed photolithographic process and for the production of the openings 158, 160 in the new oxide layer 156 is used, as shown in Fig. 4e. After that, the metallic contacts 162 and 164 vapor-deposited on the surface of the structure, as Figo 1f shows. The structure

409883/0838

is then placed in an annealing furnace in which contacts 162 and 164 are matched with the corresponding, upper and lower Planar sections of the gallium arsenide body are alloyed to provide good ohmic contacts for applying the required To form voltage at the light-emitting pn junction 1? 1 o

A gold-germanium alloy can be used for the contacts 162 and 164 and the steps discussed above for treating the alloy can also be used in this embodiment Schottky junction to the surface of the epitaxial gallium arsenide layer in the annular U ^ fnung 158 applied, which has previously been produced in the silicon dioxide üchicht ,, Accordingly serves in the monolithic optoelectronic direction line ^p ig in Fig.3. 4g is shown, the interface 169 between the epitaxial layer and the substrate for limiting the radiation 170, which emanates from the license-emitting pn junction 1'-1, to a more or less radial Yfeg when the radiation is in the direction of the reverse direction biased Schottky junction spreads out at the gallium arsenide-metal interface immediately below the annular contact Ring electrode 168 is applied. Otherwise, the mode of operation of the optoelectronic directional line is the same as that previously described for the other embodiments with a Schottky junction _{or the like}

409883/0838

The sequence of method steps shown in FIG. 5 differs from the sequence of method steps shown in FIG. 4 only in that pn junctions produced by ion implantation are used for the detector part of the monolithic optoelectronic directional line instead of Schottky junctions. Accordingly, after the epitaxial gallium arsenide layer 182 has been applied to the gallium arsenide substrate 180, the structure according to FIG. 5 is placed in an oxidation furnace in which a silicon dioxide mask 186 is produced according to the above-described Silox process. Thereafter the apparent from F.ig _o 5 ° silica mask is generated, the openings 188 and 190 'has through these apertures are then zinc ions 192 at an acceleration voltage of about 30 keV and with a

16 2 dosage of about 10 ions / cm implanted.

After the zinc ions have been implanted, the arrangement shown in FIG. 5c is etched with hydrofluoric acid in order to remove the oxide mask. The etched structure is then placed in an oxidation furnace in order to apply a new silicon dioxide layer 197, which is shown in FIG. 5d oxidation is carried out to prepare a subsequent annealing step, during which the structure according to Fig. annealed 5 during about three hours at about 900 ⁰ G, the pn junctions 198 and 200 to a depth of about 1 ft_m below the surface of the epitaxial layer 182 to to drive"

The structure according to Fig. 5d is then from the annealing furnace, taken out and photolithographically applied

4 09883/0838

"Known photoresist masking and etching techniques" to form the central opening 202 and an annular outer opening 204- in the oxide layer 197 ". Thereafter, DIE metal contacts 206, 208 and 210 are deposited, so that the DUX jjestellte arrangement in Fig. 5f is created by known metal vapor deposition method used werdeno Thereafter, the fabric according to S ¹ is Xg. 5f alloyed for a predetermined time and temperature in order to produce good ohmic contacts under these metallic contact surfaces. The above-mentioned metal alloys and the alloy temperatures required for them can be used for this last process step.

It is evident from the illustrated Embodiments of the method described can be modified in many ways. For example it is necessary with the reference to FIG. 5 procedures discussed not a combination of a ^ hospital axial procedure to act with a method of ion implantLon, instead it can be an epitacial process and a diffusion process can be combined in which both the light-emitting as well as the pn-junction serving as a detector due to the diffusion of impurities formed by the oxide mask in the epitaxial layer 182 will. Another alternative would be to to mask the epitaxial layer with a silicon dioxide layer, the openings of which have the desired geometry corresponding to the transitions used for radiation emission and detection, and then to di-3 in these openings exposed portions of the Ga Llium arsenide epitaxial layer epitaxially suitably doped gallium arsenide layer of opposite conductivity grow to

409883/0838

let to be used as a radiation source or detector to form serving pn junctions. Then the oxide layer between the junctions can be made using Plus acid removed to make a mesa-type structure to create in which the pn junctions serving as radiation source and detector are each below an epitaxial mesa «. The freely etched areas between the mesas can then be treated with a material suitable for the formation of waveguide coupling regions can be filled to the planar geometry to restore the structure formed by the radiation source, waveguide and detector. Finally, suitable and known processes for the production of oxide masks, for etching, for metal coating Steaming and alloying can be used to finish the arrangement in the manner described above

The method described above with reference to FIG. 3 is also used does not refer to the use of zinc and sulfur as p- and η-type impurities for ion implantation but many other doping ions can be used. For example, can other p-type ions are used for p-implantation such as cadmium, beryllium and magnesium, while for n-implantation such ions η-type can be used such as selenium, tellurium, silicon, sulfur and tin if the correct one Procedural conditions are respected, all of these Dopants are suitable for creating radiation-emitting pn junctions, the radiation of which in the wavelength range

o / c

409883/0838

"range from 0.900" to 1.000 '-im _o Furthermore, the processes described in the introduction are not limited to the use of the Silox low-temperature glass deposition process, but instead other low-temperature glass deposition processes can be used, such as the pyrolytic decomposition of tetraethyl orthosilicate,

For certain combinations of metals and dopants, which can be used for the novel Kicntungsleitungen, it may happen that the appropriate annealing and alloying steps require such temperatures that they interfere with each _o Therefore, it may be necessary in some cases, some or all to combine or isolate the annealing and alloying steps required again. In the latter case, changes to the described sequence of procedural steps are inevitable.

Another possible modification of the method and the device according to the invention makes implantation of η-type ions in p-type substrates.

It is also within the scope of the invention to change the annular structure of the optoelectronic direction wirings shown, special _o example, it may be desirable for certain applications such Kichtungsleitungen to deviate from the above-described ring structure and, instead, arranged with rectilinear distances,

409883/0838

Radiation source, detector and waveguide forming
■ Areas to be used «Although the illustrated ring shape maximizes the effectiveness of the coupling between radiation source and detector, which is desirable for most applications of such directional lines,
however, it may very well be desirable to have a
monolithic disc after manufacture into the
to divide individual components without ring-shaped
Having to drive around areas, for example
be desired, a special disk between the area of the radiation source and the waveguide coupling area ode :? between the area of the detector and the waveguide coupling area to separate two thirds of the construction of the optoelectronic directional line from the other third »This technique can be very useful when an existing discrete radiation source or a discrete detector with a partial combination of waveguides must be and detector or _o a sub-combination of waveguide and radiation source combined _o

There is another possible geometric design
in the application of a single radiation source
a pn junction that is in the center of an arrangement
with a large number of isolated detectors,
which are arranged surrounding the radiation source at a distance from one another. For example, detectors, and
both with Schottky and with pn junction
90 ° apart in the four quadrants of one
Be arranged area that the radiation source with

409883/0838

_ 34 -

Each detector could be connected to the central radiation source by an optical channel generated by proton bombardment and isolated from the other. Instead of this, isolated epitaxial channels between the radiation source and the detectors could be provided by suitable masks are applied _o In such .Arrangement the individual detectors could each other are applied to voltage-separated so that the light emitted by the radiation source only signal from each Detector can be processed separately according to the specific detector voltages applied.

The invention accordingly provides a new type of semiconductor component that is capable of causing significant changes in the optoelectronic industry. In addition, a number of new combinations of process steps have been detailed in the manufacture The New Devices Disclosed In particular, it is to be expected that the disclosed devices will experience proton implantation offer the possibility of such components in batches in large numbers with low Producing costs that were previously impossible in the production of optoelectronic light lines.

409883/0838

Claims (1)

Claims Λ ο) Optoelectronic directional line with a substrate made of semiconductor material, which has a forbidden band with selected energy, a radiation source formed in one area of the substrate by a planar pn junction and a radiation-sensitive detector formed in another area of the substrate, which on the radiation emitted by the radiation source and lying in a certain wavelength range responds and generates a corresponding output voltage, characterized in that a region (30) of the substrate (10) lying between the radiation source (33) and the detector (4-9) has a refractive index which differs from the refractive index of the substrate ^ 10) and thereby forms a waveguide which limits the radiation emanating from the radiation source (33) and guides it to the detector (4-9). Directional line according to claim 1, characterized in that that .the waveguide by a semi-insulating one produced by proton irradiation Area (30) of the substrate (10) is formed, 'whose specific resistance is significantly higher is than that of the substrate ο Directional line according to Claim 1, characterized in that the waveguide is formed by a section one formed in or on the substrate (140) O/. 409883/0838 Epitaxial layer (142) is formed, the The interface to the substrate (14-0) forms a reflective boundary which the radiation (170) at least limited to a considerable extent to the epitaxial layer (14-2). Ho directional line according to one of the preceding claims, characterized in that the detector (49) is formed by a metal layer (4-0) which is applied to a surface of the substrate (10) adjacent to the waveguide (30). 5o. Directional line according to one of claims 1 to 3 » characterized in that the detector (83) is separated from a planar one adjacent to the waveguide (70) pn junction is formed. Method of making a directional line according to claim 2, characterized in that a certain area of the substrate (1O) with protons, such energy and amount is irradiated that they penetrate into the surface of the substrate and forming therein a semi-insulating region (30) whose refractive index is different from that of the substrate differs significantly. 7. A method for producing a directional line according to claim 1 or 2, characterized in that that to form the radiation source a certain area (20) of the substrate (1O) with the conductivity type determining ions (18) of such energy and is irradiated in such an amount that eim radiation-emitting pn junction (33) arises, and 409883/0838 then the substrate (1O) is annealed at a sufficient temperature for so long that the implanted impurities are activated and in de. Neighborhood of the pn junction one radiant recombination take place kaniio 8. The method according to claim 7 »characterized in that that the substrate (1O) is irradiated with zinc ions (iö) will. 9 * Method according to one of the preceding claims, characterized in that in the substrate (90) Sulfur ions (98) are implanted to a selected depth before one of the radiation source, Diode or waveguide areas is formed to create an electrically insulating barrier layer (1O1) between to form the areas of the components and the remaining sections of the substrate. 10. The method according to any one of claims 6 to 9 »thereby characterized in that the radiation source as an annular pn junction (125, 127) within a outer pn junction (129, 1pi) forming the detector "and the area (122) between the both pn junctions is irradiated with protons to ensure effective radiation coupling between the radiation source and manufacture detector. 409883/0838 3 * Blank page