DE2351139C3 - Process for the production of doped zones in a semiconductor body - Google Patents

Description

Zones is improved.

In a method of the type mentioned at the outset

The invention relates to a method for producing this object, according to the invention of doped zones in a semiconductor solves that - ■ to prevent undesired Dif body from a II1-V-connection by 1) Aufbrin- fusion of one component of the semiconductor body! generation of a first oxide layer, which is one of the group III metals from the semiconductor selected areas of the surface of the semiconductor body in the second oxide layer during the Er Contains dopant to be diffused into the body, heat 60 - this differs from the dopant on a surface of the semiconductor body, 2) forming metal of group III of the second oxide dung of selected areas of the first oxide layer is added.

I do not lie on the surface of the semiconductor body, in a particular embodiment

the oxide layer is removed in other areas of the surface of the half-atom concentration of the second oxide layer conductor body, 3) added group III metal in the case of a second oxide layer on the do-gallium in the range of 10 ¹⁹ up to 10 ²¹ cm " ^3. The first oxide layer containing the beetentant and the special advantage is worked in such a way that a third oxide layer is formed in front of the exposed areas of the surface of the semiconductor

Oxide layer, which is a component of the semiconductor body Forming metal of group III contains, applies to the surface of the semiconductor body.

According to a further particular embodiment, the first Oxydschichi with an additional Content of the Group III metal which is a constituent part of the semiconductor body

_{Al 1} O ₃ is preferably used as the oxide of the second oxide layer.

The invention is explained in more detail below with reference to the drawings and the exemplary embodiments:

F i g. 1 shows the structure schematically in cross section a semiconductor element manufactured by a conventional method;

Fig. 2 is a graph of the measurement data the leakage current versus the applied voltage in the element according to FIG. 1;

F i g. 3 shows, in cross section, a semiconductor element produced by the method according to the invention is;

F i g. Figure 4 shows one made according to another embodiment of the method according to the invention Semiconductor element;

F i g. Figure 5 shows a manufactured according to a further embodiment of the method according to the invention Semiconductor element;

F i g. 6 is a graph of the measurement data of leakage current versus applied voltage for the Semiconductor elements according to FIG. 1 and 3.

One works in the usual production so that first a solution is prepared in that silicon acetate and a doping element to be diffused z. B. Zn in the form of a Zn compound, can be dissolved in an inert solvent such as ethanol. The solution is prepared by a conventional method, e.g. B. "Spinner" method, applied to a surface of a GaAs body 10 (η type). The coated body 10 is heated in air at 250 ° C. for 15 minutes or more so that the silicon acetate is decomposed _{into SiO 2.} Certain areas of the Zn-containing first oxide layer 11 formed in this way are selectively removed by conventional etching using a mask, so that areas 11 A remain for Zn to diffuse in. The exposed surfaces of the body 10 and the areas WA of the first oxide layer 11 are again covered with a solution of silicon acetate in an inert solvent. No doping element was added to this solution. When the coated body 10 was heated under the same conditions under which the first heating took place, the silicon acetate decomposed to form a second oxide layer 12 made of pure SiO ₂ . Thereafter, the body 10 with the areas 11 A and the second oxide layer 12 in an open quartz tube in a nitrogen stream or a stream of a mixture of about 93 percent by volume of N ₂ and about 7 percent by volume of H ₂ at a temperature of about 850 ° C for a sufficiently long time heated in order to diffuse Zn from the areas HA into the body 10 to the desired depth. Regions 13 with diffused-in dopings (Zn-doped p-regions in the η body (GaAs) 10 are thus formed.

However, the body 10 with the p-regions 13 formed in this way does not have sufficiently high dielectric strength values between the p-regions 13. According to FIG. 2, a considerable leakage current is detected even at a voltage well below the breakdown voltage which is to be expected due to the electron density in the n-body 10. The poor dielectric properties are probably due to the fact that during the diffusion of the doping at the high temperature of 850 ° C, some of the Ga atoms in the surface area of the GaAs body 10 _{diffuse into the SiO 2} layer 12 above it, ίο which in the surface area of the GaAs body 10 defects arise which result in an unstable surface condition and a reduced dielectric strength. However, the defects not only lead to poor insulation between the p-regions 13, but also to a reduced breakdown voltage at each reverse-biased pn junction.

In some cases, improvements are achieved by a method in which a protective layer of Si ₃ N ₄ ao is formed. Instead of the second oxide layer, a layer of silicon nitride or an oxysilicon nitride is formed on the surface of the semiconductor body after the first oxide layer containing the doping element is formed on selective parts of the body. The diffusion is then carried out by conventional heating. Since the Si ₃ N ₄ layer prevents any diffusion of any kind of diffusion much better than the SiO ₂ layer, both the diffusion of Ga or As from the body and the diffusion of foreign ions from the surrounding atmosphere are under conditions that are usual for solids / Solids diffusion are almost completely avoided. The surface area is free of the defects described above and maintains its normal or stable state. However, manufacturing difficulties and disadvantageous properties in the layers occur with this method of operation. When a layer of silicon nitride or a corresponding derivative is formed, the body is held at 500 ^° C. in a reaction tube; a gas mixture of SiH ₄ , NH ₃ and Ar is passed through the pipe. SiH ₄ and NH ₃ decompose in the tube to form Si ₃ N ₄ , which is deposited on the surface of the body and the oxide layer until a layer about 250 Å thick is formed. The conversion conditions must be precisely controlled, since the properties of the Si ₂ N ₄ layer change with varying conditions. The slow growth rate of the layer requires a long manufacturing time. The Si ₃ N ₄ layer exerts a strong pressure effect on the body, so that there is sometimes excessive diffusion into the body; cracks easily form in the Si ₃ N ₄ layer if it is deposited in a relatively large thickness.

According to the invention, the second oxide layer is al; a a metal that is part of the semiconductor body compound is formed containing layer on the body egg. As a result of the presence of this metal: In the second oxide layer, the diffusion of substances from the body takes place during or after the heater effectively prevents the doping from diffusing in.

In the embodiment according to the invention, FIG. 3 is a semiconductor body 10 from a III-V connection, namely GaAs, GaAsP, GaP or InP, used. A surface of the body 10 win initially covered with the first oxide layer 11

The layer 11 contains a Do which is to be diffused. Layer 15 contains the same metal nator or acceptor doping element, e.g. B. Zn or like the second oxide layer 14; it is also in the-Te, and can be formed in the usual way, preferably in the same way as the second oxide layer 14. Application of a suitable solution and then the first doping-containing oxide layer 11, by heating, is formed. Parts of the layer 11 5 are formed on the layer 15. This is followed by selective etching are then passed through a conventional encryption removal of portions of oxide layers 11 and application of a mask selectively removed, so that 15, forming the second, the metal containing the desired portions 11 A are formed. Then there is oxide layer 14 and subsequent heating to diffuse in the doping on the exposed surface areas of the body. In the resulting pers 10 and the surfaces of the areas 11Λ of the io semiconductor element, the outer surfaces of the doped oxide layer 11 are the second oxide layer 14, ent-diffused areas 13 directly with the non-holding a metal of group III, which is a component of remote areas ISA of the third Oxide layer 15 of body 10 is e.g. B. Ga for a GaAs body, while the remaining areas of the surface are formed. The layer 14 is preferably formed by the second oxide layer 14 of the body 10 in that a solution which is covered from a 15 is first produced. The non-removed areas 15 Λ of the inert organic solvent, silicon acetate and third oxide layer 15 prevent metal diffusion consists of a compound of the selected metal from the body 10 in the dopant-containing Beauf applies said surfaces; subsequently rich IiA due to the metal contained therein; is heated in air, whereby the silicon acetate is converted to SiO, at the same time the undesirable phenomena are decomposed. Thereafter, the doped regions 13 ao are avoided as a result of the separation of the dopant-containing regions in the body 10 by conventional heating of the 11 A from the body 10. The thickness of the layer coated body 10 is formed. 15 must be large enough to allow diffusion from the body

It is essential that, according to the invention, the second 10 to prevent in the areas 11Λ; however, oxide layer 14 may contain the metal in question. The metal which is not so large that diffusion from the areas of the layer 14 prevents the 25 11/4 in the body 10 is prevented. _{If SiO 2 is} used as the diffusion of metal atoms from the surface of the oxide, the preferred thickness of the body 10 is in the layer 14. The atomic concentration of the layer 15 in the range from 500 to 1500 Å of the metal atoms in the layer 14 is in the case of Ga According to a further embodiment according to the invention, preferably in the range from 10 ¹ · to 10 "cm ^-3 . The shape of the metal diffusion from the areas of the second oxide layer 14 also effectively prevents the diffusion of the doping of the first oxide layer 11 into the first oxide layer 11 even without the formation of a third oxide layer 15 The surrounding atmosphere and the diffusion of modified first oxide layer 16 (Fig. 5) contains foreign ions from the atmosphere into the body 10 as well as a certain Group III metal, which during heating is also obtained as a component of the body 10, as well as an improved semiconductor element with a better upper 35 diffuse the dopant. The layer 16 surface stability, dielectric strength between the two is produced in the same way as the above diffusion junctions, breakdown voltage in the barrier-mentioned first oxide layer 11, with alignment at each junction and uniformity, however, with regard to the addition of a connecting element. This method is suitable for producing the selected metal for solution. The provision of better light-emitting diodes and 40 other process steps, ie the removal of better field-effect transistors. Advantageously, the layer 16 is sufficient, leaving only the simplicity of the formation of the oxide layers, required areas 16 A, formation of the second namely also the second oxide layer 14. Each oxide layer 14 and subsequent heating to form the BiI layer can easily be Method formation of the doped regions 13, take place as described above and do not require any special or standing in the method of operation according to FIG. 3 explained. The complex device. The heat treatment for the presence of a group III metal in which the doping does not diffuse can take place in a removed area 16 of the modified first open tube. In addition, the oxide layer 16 prevents the concentration of the doping element or the inhi metal atoms from diffusing in from the areas 13 of the body. Any metal in an oxide layer according to the diffusion from or into the remaining part of the requirements can easily be varied by varying the concentration of the solution in each subject according to the invention. Embodiment by the applied thereon

If a doping diffusion up to the second oxide layer 14 is to prevent a moderately shallow depth, the possibility exists that metal atoms will diffuse on the body 10 in 55, for example, the areas 11 A of the first oxide layer 11, even if a diffusion into the second oxide An n-type semiconductor body layer 14 doped with Te was prevented, and so surfaces made of GaAs were used to achieve an electron density of defects in the diffusion regions 13 and impairments Deep doping diffusion 60 namely the area (100), was produced up to a high gloss and if it continues, for example, the doping in the lapped and further only one of H, SO ₄ , H ₄ O ₁ and first oxide layer 11 in a relatively high concentration Water existing etching solution polished The polished is present so that the doping with the body 10 was reacted by means of a spinner device and the surface Adhesion between the first with a Zinzüicatfümlösung (solution of silicon oxide layer 11 and the body 10 is reduced, 65 acetate and a zinc compound in an inert »one works according to another organic solvent according to the invention) provided. The dea with embodiment (F i g. 4), so that on the surface plated provided Minutei body 15 of the body 10 was first heated a third oxide layer 15 to 200 ^e C in air, the SiGcnnnacetat to Si

silicon dioxide was decomposed. The SiO ₂ layer was about 2300 Å thick and contained zinc in an atomic ^{concentration of 10 21} cnrl Unnecessary areas of the SiO ₂ layer were removed by etching with a 10% aqueous solution of hydrofluoric acid using a mask made of acid-proof resin.

A gallium silicate film solution (solution of silicon acetate and a gallium compound in an inert organic solvent) was then applied with the aid of the spinner device to the exposed surface of the body and the unremoved areas of the SiO _{2 layer.} By heating the body coated in this way for 15 minutes in air at 200 ° C., the second SiO ₂ layer of about 2000 μm thickness, which contained Ga-A to mc in a concentration of 10 ²⁰ cm " ³ , was formed.

The body was then placed in an open tube and heated in a stream of a mixed gas of about 93 parts of N ₂ and about 7 parts of H ₂ at 800 ° C. for about 15 minutes until Zn-diffused p-regions of about 5.5 μm Depth in the body had formed by diffusion of Zn from the unremoved areas of the first SiO ₂ layer. The atomic concentration of Zn in the surface of the diffusion areas was of the order of 10 ²⁰ cm * ³ .

The voltage-current relationships between the p-regions thus formed in the body were then measured; the result is shown as curve / 1 in FIG. 6 reproduced. No leakage current was detected until the applied voltage was increased to the breakdown voltage of the body. The improvement achieved according to the invention can be seen from a comparison of curve A with curve B , which represents the result for diffusion regions in known bodies.

Example 2

In the case of an n-type semiconductor body made of Te-doped GaAs as in Example 1, the surface (100) was lapped and cleaned in the same way. Then, a gallium silicate film solution was applied to the polished surface of the body by means of a spinner. After heating in air for 15 minutes at 250 ^° C. there was an SiO ₂ layer about 1000 Å thick. containing Ga in an atomic concentration of 3 × 10 ²⁰ cm ^{3 was} formed. Then there was an SiO ₂ layer. containing Zn atoms in a concentration of 10 ²¹ cm " ^{3 was formed} with a thickness of about 2300 Å on the previously obtained SiO ₂ layer, using the same procedure as for the Zn-containing SiO ₂ layer according to Example 1 If the Zn concentration in the SiO ₂ layer ^{is required to be 10 22} cm- ', a body coated with the above-mentioned Ga-containing SiOj layer must again be heated to 450' for 30 minutes in a nitrogen atmosphere. C. before the Zn-containing solution is applied. Areas of the two SiO ₂ layers were selectively removed simultaneously using the same etching process as in Example I. On the exposed surface of the body and the areas of the SiO ₂ layers that were not removed a Ga-containing SiO ₂ layer about 2000 Å thick was formed in the same manner as the second SiO ₂ layer of Example 1. Then, the body was heat-treated in an open pipe under the same conditions as in Example 1 ndelt, wherein on the surface with Zn in an atomic concentration of 10 ²⁰ cm " ³ doped p-regions with a depth of about 3 μm were formed in the body.

Example 3

On the polished surface (100) of a Te-doped GaAs body as in the previous examples, a mixture of a zinc silicate film solution and a gallium silicate film solution was applied. The coated body was then ^{heated to 200 °} C. in air for 15 minutes, a 2300 Å _{thick SiO 2} layer containing Zn and Ga in atomic ^{concentrations of 10 21 cm 3} and 10 ²⁰ CiTi ³ , respectively, being formed. Then, as in Example 1, the SiOj layer was selectively removed, the second Ga-containing SiO ₂ layer was formed and the body was heated in an open tube. The generated p-regions were about 3 μm deep; the Zn concentration on the surface was 10 ²⁰ cm ^-3 .

The diffusion transitions produced according to Examples 2 and 3 have because of the stable surface area excellent and uniform properties.

In the same way as Zn, Cd can also be diffused into an n-GaAs body with good results by the method according to the invention. The diffusion of Se or Sn into a p-body made of GaAs can also take place in the same way. In addition to GaAs semiconductors, the method can also be used for other semiconductors made from compounds of III-V elements, such as GaAsP, GaP, InP. The Group III metal contained in the oxide layers is chosen taking into account the composition of the body. In is to be used for an inP body.

With regard to the formation of the oxide layers which contain a doping and / or the selected Group III metal, in addition to the spinner method or the application of a solution, conventional procedures can also be used, e.g. B. Spraying, steam growing, or thermal decomposition. _{Al 2} O ₃ can also be used as the oxide for the oxide layer containing the metal.

For this purpose 3 sheets of drawings

609647/31.

Claims (5)

25 51 139 1 2 body and 4) heating of the coated semiconductor patent claims: body for diffusing the dopant into the semiconductor body. 1. Process for the production of doped In the production of semiconductor elements with * Zones in a semiconductor body made of a III-V- 5 a body made of a semiconductor compound, such as Connection by 1) application of a first GaAs, GaAsP, GaP or InP, the required Oxide layer that lent a transitions into selected areas, such as pn. pp ⁺ , np or nn ⁺ , through the surface of the semiconductor body to diffuse in a donor or an acceptor containing dopant, produced on a top doping element in the body. Under surface of the semiconductor body, 2) formation of the various diffusion methods is the so- selected areas of the first oxide layer called solids / solids diffusion preferred. at on the surface of the semiconductor body by the method according to US-PS 36 15 943, with in other areas of the surface of the half of a silicon containing a dopant the oxide layer is removed from the conductor body, 3) the anti-oxide protective layer is application of a second oxide layer on which the 15 works and, when heated, the dopant First Oxydschichi containing metering substance diffused into the semiconductor body, result and the exposed areas of the surface of the good quality transitions; the procedure works Semiconductor body and 4) heating the coating- also economical; with him, however, there is only one Teten semiconductor body to diffuse in the relatively low dielectric strength between Doiierungsstoffes in the semiconductor body, which reaches the diffusion transitions, namely probably on characterized in that - for the reason of the unstable surface condition as a result of the preventing the undesired diffusion of metal atoms from diffusing out of the body. Component of the semiconductor body forming Me- From the "Journal for Applied Physics", Vol. 18 tails of group III from the semiconductor body (10) (1964), pp. 129 to 132, is in connection with in the second oxide layer (14) during the Er 25 gallium arsenide planar transistor a method of heat - this known from the dopant type mentioned at the beginning, with certain distinguishing group III metal of the second regions of the surface of the semiconductor body with Oxide layer is added. one z. B. containing tin as a dopant 2. The method according to claim 1, characterized thereby, silicon dioxide layer are provided, while indicating that the atomic concentration of the 30 more areas of the silicon dioxide layer uncovered second oxide layer of the added metal remain, whereupon a pure silicon dioxide group III in the case of gallium in the area of layer as a cover on which the dopant 10 ¹⁹ to 10 ²¹ cm " ³ is located. Oxide layer containing the dopant and the exposed layers 3. The method according to one of the preceding claims for the surface of the semiconductor body, characterized in that one is brought before 35 and then the dopant the formation of the first oxide layer (11) diffused into the semiconductor body by heating a third oxide layer (15), which becomes one component. Using a dopant part of the semiconductor body (10) forming metal (tin or zinc) with sufficient diffusion within Group III contains, on the surface of the half-the applied layer are indeed semi-conductor bodies (10) applies. 40 components made from semiconductor bodies with sensitive 4. Method produced according to one of the preceding surfaces; nevertheless, un-claims can be characterized in that the desired diffusion phenomena during the first Oxide layer (16) with additional heating cannot be avoided, and it will not be satisfied achieved dielectric strength on one component of the semiconductor. Group III metal 45 representing the body (10) The object of the invention is therefore in the is trained. Creating an improved and easily executable 5. The method according to any one of the preceding method for producing doped zones in claims, characterized in that as a semiconductor body made of an II IV compound, oxide of the second oxide layer Al ₂ O _{3 is} used, with undesired diffusion of the metal of the group. 50 III from the semiconductor body during the introduction of the doping element effectively prevented and so the surface stability of the resulting doped