DE1439958A1 - Controlled semiconductor rectifiers and processes for their manufacture - Google Patents

Description

U39958

Munich 2, - SL JUNE 1S6 9

EleoteLe Corporation Witteisbacherplatz 2

Pittsburgh, P.A.

PA 63/8284

Controlled semiconductor rectifiers and methods for their

Manufacturing

I ^{1 For} this # registration the priority of the corresponding StaamaBBLtiäuzigexi in the USA, Serial No. 249 530 and 249 of 4 * 1.1963 claimed.

The training generally refers to controlled semiconductor glide resistance and process for their production and in the eiBa # lB®j3 on solo rectifier with a pn collector lbeargdng w'eloher a flat gradient of pollution has econation.

** There beeteht at verachied en en semiconductor devices the task (^ a pn junction with a gradient of flaohen Verunreini-ο get gungakonzentration This Gr ^ dieafc .Ur Varunreini- ° * gungakonzentration represents the change in the / _r; r. : ί t ^ in i ι, 'ιηα- ^ - o

concentration in ViiTeci »fcfcoU.neft4b« taftden from ·; ..,.; ι t :; > ■ -? $ ■ u; _f ; ei ■ · .-. ■ ·. ■ "'BAD

· ' . · · - ··.''U39958

PLa 63/8284 "" "

towards a flat gradient of the impurity concentration runs only with minor changes and shows no abrupt jumps. Controllable semiconductor rectifiers belong to those semiconductor arrangements in which a pn junction with a flat gradient of the impurity concentration is desired, as a result of which the rectifier exhibits a high breakover voltage. The present invention will be described in detail in relation to a controlled caliber rectifier. Δβ int it is clear that it can also be used in other semiconductor devices in which a flat gradient of the impurity concentration is desired.

A controlled semiconductor rectifier (semiconductor current gate) ■ is a semiconductor arrangement which usually has four successive zones of different conductivity types (pnpn). These zones are hereinafter referred to in their \ sequence as a cathode-emitter (or cathode), the first base, second base and the anode emitter (or anode). designated. Connections are provided for the cathode, anode and the first base. L'in load circuit, which is connected to the cathode and ■ ^; Anode is connected, can be controlled by a control signal which is given to the connection of the first base, which is also called ils control connection · *. ⁱ

Controlled rectifiers have a well-known characteristic, which, in a few quadrants, has an area with g ^ iii ^ er conductivity, -juer hoiv ^ i'i .Λ .-- 1 : -rat;: ti w.il \ <u \ it uu'.lt ^: a'ui area with ^ 'tvi

ORIGINAL

u ' w''-''''H39958

- '. "■,' PLA 6? / 8284

Conductivity and a transition range of negative <7ider- ■ - ■ <· «■■, I stood« between the two. A sufficiently high voltage which is applied between the anode and cathode may cause the butts, that is, switching from the area of high Widerstandet j in the region of the high conductivity without _'v that any control signal applied to the Lteueransehluß

“This voltage is drawn as the breakover voltage of the rectifier” . It is generally desirable that the breakover voltage be relatively high so that the rectifier does not

"; only on the basis of the voltage applied by the Laotstromkrei3 ; switches through, Ks is preferred on the contrary that the : Rectifier at most voltageseveauo just by doing this 4ei {it is possible that an osignal is given to the remote control connection will.

It has been shown that the breakover voltage is higher if the pn-junction, called the collector-pn junction, between the first base and the second base has a flat gradient of the impurity concentration, that is, if the impurity concentration in the first base " only gradually decreases as the pn junction is approached, it seems unnecessary to deal with the physical explanation for this relationship between the gradient of the pollutant concentration and the breakover voltage, since it has been discussed extensively in the literature, e.g. by Yeloric, etc. . in "Avalanche Breakdown Voltage in Silicon ^Λ Diffused PN Junctions as a Function of Impurity Gradient", Journal of Applied Physios, Volume 227, Applies 895 to 899,

909883/0466 BAOORtQiNAL.

PLA 63/8284 dated August 1956.

Controlled rectifiers of the pnpn type have hitherto been produced in such a way that a single impurity of the p-type was diffused into a semiconductor body of the n-type and that the redoped zone thus created was divided into two physically separate areas, whereby the first basic zone and the. .ncdenzone were formed, which rest on J opposite .ioites of the second base zone, | which is formed by the ..usgango material. Line η-leiten- I de zone (cathode) v / 5rd on the surface of the first base zone, preferably formed by alloy. But Cie can also ~. can be generated by diffusion of an impurity * ' ^: \ which generates η conduction. In the method just described is; the diffusion process by which the first base zone is formed is of primary interest for improving the breakover voltage of the device.

A relatively flat impurity concentration gradient usually results from a long one; deep diffusion. But long process times are highly undesirable, and moreover, the Cberflächenkonzentration the erzeugton by Diffusicn zone must also be controlled, if a satisfactory operation of the apparatus is to be achieved _t, kut'iert as also in the literature dis- ^ * was'. The well-known manufacturing process is one thing

'single contaminant, which p-type conduit ei * - 4 * produces, e.g. ' Gallium, for the division of the first base zone 1. '

909883/0466 j

BATH

¹ * - ■■ "'H38958

f · PLA 63 / 8.284

used is necessarily a. Compromise between this, different factors for the purpose of a satisfactory one Device at the lowest cost.,

At the moment the starting material shows a resistance in the order of magnitude of about 1 to 50 chin. If the specific resistance is increased, a flat gradient of the pollution concentration could be achieved more easily. The higher specific resistance of the starting material, however, increases the voltage drop of the controlled rectifier in the conductive state and is therefore undesirable. The surface concentration of the first base zone produced by diffusion must be sufficiently high so that the gain factor of the transistor equivalent of the first three zones is still small enough so that it does not cause the controlled rectifier to ignite at only slightly increased temperatures As a result, the rectifier should preferably not be temperature-dependent in its breeding characteristics at all. Ea ^ er-earseits difficult too high CberfläehenkoKze, nermost base zone xxnä the flashover under all loading dsie surface concentration should therefore

until 10

17 1 ft ^

im dter Si? ®lei3 ^ rdtHiiug from 10 to 10 atoms / cm and not w®3ea3. are slightly higher or lower.

It is therefore an object of the present invention to produce improved semi-parental devices which have a flat gradient of pure organic concentration.

-. 5 BATH

ί439958

ELa 63/8284

wetteren 2Le = Il it is _B vreorbess-erte; Controlled Semiconductors ™ ^: ■ "■ *

gle-icfixia-feter ':, = soft one, have a kippspianniiirg: without Wersafeieeliteriiag: the other ^ h & rakrte-ris-tilceB: - have. "

Lim weiteores. Target actual it ,, u first longitudinal process of Hälfe- leiterg ^ sräten _ZXI: create and insfeeacrrdejre: g-estexEearteil · IiaXfeleJlter-gieic.Br ^ ieia.terii. zix sG: B.affeH., _f w, elen.e a 2on: e with "a flaciien; 3, radd.en.teö der · Ve.rttnreliii
undi e-in: © g ^ rtau controlled ClaerflllciliejxkcnzentratiQii;

Bierülr, fin (fiingi tretri-fft Cesh.aJllr ein. ¥ er £ airren
one-s IEalb: lÄiteElatteIemsn; t3 ,, inu fee special of an Ealiile; it: e; ir stüoiatesrB! S · νσίη; ρηιρη ^ -Ιjp, where in a
Halläleit: eirlcQrper ' _r dear at least on a Flaeiisei "fce
"beatimmten LeitfäM-gikexttyp: -has -. ,, from this-.
he, v a ¹ äexi, entgiKg ^ g: esetz
the pollution is diffused., iLr-fi
at least ⁱ sten _; &: two, the opposite;
¥ pollution; s;

crdej-r in two g: © t2reirttteaa! "esrtga & arensgÄngem emn> -

Briefly, "thus concerns a method DIE Erfindung- Zunt producing a Halbleiteranordnung- with a pn junction with a shallow gradient of Yertmreinigungsfconzentratx.gn _r · * wherein at least two impurities of the same ·:
ability type to be diffused, van. those; the & £ n® "bis

BATH

H39958

PLA 63/8284

. Diffused into the desired pn junction depth and a causes flat gradients at the pn junction, and from which

_: the second penetrates to a shallower depth and causes a desired high surface concentration. The invention further relates to semiconductor arrangements, in particular to controlled rectifiers, which have a zone with two impurities which have penetrated to different depths and which are produced by the method described above. Furthermore, it is a feature of the present refinement that diffusion nuclei are provided with which the method described above can be carried out, and in which, for example, the impurities to be diffused are contained in the same source.

The features of the present _-figuring know together with the above-mentioned and other distributions best from the following description in connection with the enclosed the drawing can be understood. In the drawing they show

Pig. 1 to 4 cross-sections of a controlled semiconductor equal ^ Richter according to the present invention in various Creation phases,

Fig. 5 shows a graph of the impurity concentration ι applied over the .-, penetration depth e for a typical

Arrangement according to the present invention, Pig. 6 shows the. cross section of a diffusion source according to

of the present invention. The ■ 'Fig · 7 to 10 show cross sections of a controlled semiconductor

909883/0466 BATHROOM

PLA 63 / 8284-

rectifier, which according to another embodiment the present refinement is made in different ~ successive phases of its manufacturing process. ".

■ ι

FIGS. 11 and 12 show diagrams of the diffusion profile for two examples of this embodiment of the invention. ; '

Fig. 13 shows the cross section of a device for. Performing _- \ diffusion according to one embodiment of the invention. ^!

Fig. 1 shows in cross section a semiconductor wafer TO, which ■; . for example of the n-conductivity type. _; . "." .: ■! '

In Fig. 2, the output disk 10 is shown after Ver- f

impurities according to the present invention were diffused -f. The diffused layer 12 consists of an ^inner:; I.

Part 13, which has a pn junction 14 with the starting material J

forms, and an outer part. 15 of the same conductivity ^ I

tvps like the inner part 13, but which has a higher impurity concentration and is therefore referred to as ρ + ·

while the inner part 13 is denoted as ρ. "·

In Figures 3 and 4 are further stages of the manufacturing process which complete the present example. In Fig. 3 "'the diffused pane 10 is according to Fig. 2 with an ohmic contact 16 on the lower Flat side of the disk shown, * as well as an annular zone 18 of the n-conductivity type on the upper flat side of the disk, which can be produced, for example, by alloying, so that at the same time an ohmic contact is made on this η-conductive zone

909883/0466

Τ 43 9-9 5 $

PiA 63/8284

• is appropriate, and; also a second ohmic contact on the diffused zone.

4 shows the arrangement according to FIG. 3, which is now provided with a "trench 22 which divides the diffused zones T3 and 15 into two physically separate parts. The trench can be ring-shaped and the ring plates - Shaped n-conductive zone 18. On the other hand, material can also be removed from the hand of the disk ¹ according to an equivalent method, so that the pn junctions are separated.

It turns out that the arrangement which is shown in FIG. 4 is used as a controlled rectifier . The arrangement consists essentially of m.erhalteleitendeja 2-onen of alternating conductivity type - imLt dasxsGhen lxÄg-ejidBn: pn- ^ transitions. The e-rate. BV-iBitJ ^ Rüer. Zxm & TB on the upper flat side dxent: als Kathadeümxtirer '. ? pear Tm ± H DCEA · dif fundierteiji ächiohit which s0.w, ahi p> - umtf E * ^ eiäjei · T3 ^"1 u®J; 15 entiiält: and: which to the cathode: t: ,,, diieaifti: as; first base zone 23, and the contact 20; ,,

n: aaigeabraEcikt is, serves as a control connection .. That ^ p AiöBgarrg? SBia.terial 10 serves as the second base zone.

Bear! Beau & sv da- £ ßun41e- rten Zaxm 13 and 15, which one to the?. KL'ÄrÄS! Öi ^: te of the device adjoins, serves as an anode

- ο

ii, 6% / B284

The · arrangement straäfl; Fig · ... Φ karm for: all: feekana ten an ^ falxe. from the ge: s: expensive: rten Glexeirricirterrr an ^ ewaird: t be: and is especially: advantageous to apply in _{the 'cases;} where one; High breakover voltage * and one - high: ArbeitsiieTnii.eiE - i.fcur desirable.

lie high: Klppspanming; is thereby, tea-effect,. because the earste, base "zon: e: 2'3 has a faiaehr acbf allend: e: V ^ rurareirKisurigBkDnzreiitratio;. In this ·. way it is possible, - the: ^ ixror-ingtiefe: des pn:

Ubier ganges- 1 Φ sa. ahead-2: _utrjeibeK: άΆ & a: flat ex gradient, dear YerunreinigungsJcOiizüentration on:] pi> - 'over-gang "exists :, xxnü that; at the same dia gewünsciiter OTäie ^ flKcheja ^ oirzecntratiai v / oak ^ veariiältnisraäßig · high; be · And timzz & em: a ».

Weirfe: aainehnren ⁷ nnifl *. It; is: this is effected by diffusion: voir awei Terunireijnigun'gSH des gleioheaii ΐ-ypjsr, «in the vo: rli.egien: a: eii play of Akz: © pt: oren _r of which the one impurity; in:

the: starting material. penetrates and geawxnscirte-n: Ϊ1 the: pnr-ilbergang "forms, and; vonr d-eneir the second?

gung, IUs: - to: anear gmz ^ g & azerr Lower a ^ Lsr-diiei firstgun ^ einglcingif and * di: e; geminsichtei 01xe2Ef ^ ä; GÄeMfe <mzren * a! atä ^^

wirfctw - ■ "■■" - ■ "" "" - ■■■ ". ■" ■ .-. ■ .:

Btec? aiti ^ ffSitaiftossr ifearLauf diesr

ice; Bäsis ^ ianB: karrm "iieBacear ve-Es ^ änTdieM- wmtä & JK _i9 wieüm wem Fig., 5- BfesEiig:» imircte ,,: weiEcife daie; Ver ^^ r ^ eäinsogpn ^ HfeQiiaiis ^ of the first base zone 23- shows., Selbatrstän sirell-t this ~ only a celebration of the varl living invention 'represents ^1. The "Diffusian ^' -

profile of the first 'pollution ",, in this case; from AXu, -.;

minium, is represented by the erat.e Kurrva 30 '., Die- Älusiirj. ± iim> concentration is about "10. 'A-tome / cm ^ at your ·

H Γ λ Γ

PLA 6Τ / 8284

and takes on less than 10 atoms / cnr at a depth of . about 50 to 62 / rev in the material. The horizontal interrupted one Line 31 shows the level of the contamination concentration. tration, which the starting material has, and which approx 10 atoms / cm. Therefore the aluminum diffusion causes that at a depth of a little more than 50 / rev. a pn junction is formed »Since aluminum is a relatively fast diffusing substance, it penetrates deeply and forms one flat gradient of the impurity consentra'tion am pn junction. That is, the decline in the principle of aluminum diffusion at the pn junction is relatively flat, which is desirable for a high breakover voltage. Unfortunately ; are a flat gradient of the impurity concentration

at the pn junction and the desired surface concentration cannot generally be achieved simultaneously with a single doping material, as was explained in the introduction. It was found that the surface ion center of aluminum is limited to about 10 atoms / cm ', which is for the%. desired properties of the controllable rectifier is too 'low. The reason for this limitation of the surface; concentration of aluminum is not quite clear, but ^one J, it seems that a surface layer of the half-

ladder is due to »soft the diffusion of further . , Prevents aluminum from getting into the interior of the material.

second curve 32 shows the diffusion profile of a second impurity, in this case gallium. The gallium

lyl ^ iffusicnsprofil shows a surface concentration of "vV" 909883/0466

- 11 - 3i / wing

BATH

- '- H39958

PM 63/8284

10 "atoms / cm _r which drops off quite sharply and not '

the depth of the pn- --- \ " J junction formed by the" aluminum diffusion "is reached. On the other hand - aluminum - can help with it

of gallium the desired surface concentration in ^comparable; - '

".- ■" ■ '■ - ■ - ■ ■> .

can be achieved in a relatively short time. But if gallium> · |

alone would be used to connect the pn junction with the ge ι

to produce the desired surface concentration, would have to;

different Kachteile are accepted. So that a ver "j

relatively flat gradient of the impurity concentration *

could be achieved at the pn junction with the aid of gallium, J.

a very long and slow diffusion would be necessary, which j.

would be economically unsustainable. In addition, with gallium]

the leakage current across the pn junction is not as desired · ·. · ■ |

keep it small * It is also very difficult to keep the surface, \

Keep concentration under control so that they don't. - ■

18 the desired value, which is in the order of magnitude of 10 atoms / cm, overshoots if the necessary penetration depth, which is necessary for a shallow gradient of the ver. ■ The impurity concentration at the pn junction is necessary, with - ■ Gallium wants to achieve. Thus one by Galliumdiffusion the 'could-achieving time desired pn Gharakteristik and Cberflächenkonzentration within a hrauchbaren, it would be necessary to use very high temperatures, which likely _Λ borrowed the semiconductor material interfere would and what' it for practically impossible * diffusion to be carried out within a commonly used evacuated oar tube. Μ ''"ί

The vertical dashed line 33 indicates the depth "In

909883/0466

" ¹² ~ - .; 3i / Bf?

'> H39958

PLA 63/8284

Welefaer ier emltter-pn-junction is formed by alloy. This depth can be easily determined by the thickness of the alloy foil can be determined and is chosen so that the doping level is at the pn junction. Range of about 6. 10 atoms / cm to about 3 »to atoms / cm ''.

Jäs thus shows that the present invention offers a solution to the problems associated with the fusion of two impurities of the same ijp into a crystal. This improvement Ιεεββ can easily be carried out since one is not radically deviating from the usual methods of making controlled rectifiers !! departing needs, but only a Abwaailidig of diffusion processes, which are carried out with the Ausgangsisateriäl necessary is "2s showed au & er iesif that in addition to improving Kippspännung, welerh © ¹ due äes shallow gradient of VerunreinigungskonUefitir ^ tion in the first base region 23 occurs , additionally the Speri'Bpaicau & g, which the arrangement can withstand »increased

The graduated conductivity of the diffused zone in de ©

26, which is a highly doped p4--3ehich.t 15 * It also has the advantage that the effect of the

is enlarged when the arrangement is in the state »

It "divides" out that a source for the diffusion of the iswel? trttöi * © iltigujagen of the same type are created

BATH

'"14399511

PLA 65/8234

It is possible that the two impurities are intimately mixed or alloyed together on a suitable base, with the proportions of your two impurities; can be determined in accordance with the desired degree of conductivity "which is to be generated". For example, compounds of gallium and aluminum alloyed together with a gallium content of 0.5 to 50 percent grain cause the desired areas of surface concentration and penetration depth in silicon. "The gallium-aluminum alloy can be produced by placing weighed quantities of the substances on a body made of p-conductive silicon and melting them in a vacuum for the purpose of producing the alloy. The diffuse can be used in. known ίίί ei se be used ^ for example by being in an evacuated ^ uarzröhre eingeleg "fc in which the ^ to be diffused Öiliziumscliei Jen contain" * siijd * FIG * Θ is such ^ uejlXe dai> set "consisting of a doped semiconductor Läge Bestefet ^ whichever ΐϊϊ this all atts p-conductive iiilizvium beeteh% and ms £ which the intermingled Veruiireinlgert 42, such as Sallium and Alumiiiium, are / are. ν

In a typical example of the method of the present invention, various silicon wafers were used. / used as a starting material. The SI- / silicon wafers were degreased in trichlorethylene and in. Methanol washed in an ultrasonic washer. The specific see Conductivity and thickness of the panes were tested externally *

- H - 909883/0468

PLA 63/8284

JÖer specific Y / esistance was between 10 to about 50 ohm cm (about 10 * igrößenordnungsmäßig atoms / cm * Verunreinigungskon- ■ '.' ■ "." Entrktion) and the thickness was about 300 / u. After Keini- were supply the Silicon wafers are etched in an etching bath, which consists of two parts by volume of nitric acid LNO, one part hydrofluoric acid HP and one part glacial acetic acid CK, COOh, and then dried and placed in a cleaned oil tube.

A diffusion source was then made from an alloy with 7 percent by weight gallium (most aluminum), and Ewar on a p-conductive silicon wafer with a thickness of about 1.5 πιπί. The alloy was alloyed in a QuecMeilber vacuum. The diffusion source was

also in the ^ uarzröhre with the öiliziumscheiben inserted * liziumscheiben The quartz tube with the diffusion source and the Si was then sealed by evaluation at about 10 "mm mercury and pushed in an adjustable oven, and then at a temperature of about 1230 ⁰ G about 20 Hours laag heated.

As a result of this, Diffusionsbehandiung a diffusion profile which substantially corresponds to the 5 shows. "i) The test of the assemblies produced showed that the ί I flip-over voltage at 10 milliamps leakage current and 150 ° C temperature

was about 780 V. This is an unusually high | [lpp voltage * compared to conventional arrangements.

t ;; y

"f ■

the embodiment just described are the two

909883/0466

BATH ORIGINAL.

PLA 63/8284

Simultaneously diffused impurities from the same impurity source. Although this procedure in general is satisfactory, it is sometimes desirable other methods of manufacturing controlled rectifiers possessing these properties. Hereinafter is with the pn junction referred to, the collector pn junction of the controlled rectifier meant unless expressly stated otherwise.

The aim of the embodiment of the invention described below is to provide improved methods of manufacturing controlled rectifiers which utilize readily available individual impurity diffusion sources . '- - ■■ "'. ■■: ■ - '.. /' ■ '- ■ -. ■ -; ' -: - ■

■■ ■■ A feature of this embodiment is short in the fact that in a method for producing controlled semiconductor rectifiers, a first contaminant is diffused into the starting material, penetrates this to the desired pn'Jbergangstiefe and a flat gradient of the impurity concentration at the pn transition causes. In a special diffusion process, a second impurity of the same conductivity type is diffused in, which causes a relatively high surface concentration. In general, the diffusion of the impurity material which determines the pn junction is carried out first, but the sequence of the diffusion processes can also be reversed. According to another feature of the

16 - 909 & 83/0466

BADORJQiNAt

Si / Bg

PLA 63/8284

4 *

lying force ground the two diffusion processes done simultaneously from two separate sources.

This embodiment, too, which is shown in FIGS. 7 to 13 is shown, can be used in particular in the manufacture of controlled rectifiers from η-conductive silicon. the impurity, which is the flat gradient of the impurity concentration at the pn transition boundary causes, aluminum, and the impurity, which causes the desired high surface concentration, Can be gallium. However, as will be shown, other selected contaminants may be with other semiconductor materials can be used similarly. >

Fig. 7 shows in cross section a calf wafer Ito, "which consists iD-elspielsweise conductive n-semiconductor material \.

In Fig. 8, the disc 110 is shown after having a first impurity has been diffused according to the present invention, whereby a diffused p-type Zone 112 was created. The first pollution invades the disc and creates a flat gradient of the Contamination concentration at pn junction 111. The area Gradient results from the fact that during diffusion there is a low surface concentration (of the order of magnitude 10 atoms / cm) is observed.

- 17 - Si / ßg

909883/0460 BA0 OFMQINAt

PLA 63/8284

In FIG. 9, the disk 110 is shown after it has been diffused with a second p-conduction pollutant which has an external effect. well-founded p-type zone 114 .generates. which has a better surface concentration. "and is therefore referred to as p + type to distinguish it from the first diffused p-type region 112. The second impurity is diffused in at a surface concentration of about 10 or 10 atoms / am ^.

The further production of the arrangement can be carried out according to known methods, in which case, for example, alloy foils can be applied which create an n-conductive zone 116 on the upper surface, which serves as a cathode center, and an ohmic -heai contact TTS on the base zone {by a first part of the diffused 2 '; ne 112 and 1T4 shown), which serves as the control end of the device, and a © mm is contact T2Ö on the lower: flat end as Anode connection, which is represented by a second part of the diffused zones Π 2 and 114. (3-The same way according to the known method dxe by. Diffusion zones are separated by a ditch, wödu3? Eii separate cables on the ¹ upper and lower Flaeliselte the · disc be created ,. ^v - '"..

For example, according to the present invention, the first mffusion step with a silicon wafer from type, which has a thickness of ßv / a

909883/0466

-'18-. ■. öi / Bg

BAD UBfG ^ ^Mf '^ ^A

_ \ _ά

909883/0466

U39958

PLk 6Ϊ / 8284

265 / U and a specific resistance of about 25 ohm cm. The first diffusion step is carried out with aluminum as the doping material, which penetrates to a depth of about 30 / U with a surface concentration of about 3. 10 atoms / cm ". The second diffusion step is carried out with gallium, which is diffused at a surface concentration of about 5 x 10 atoms / cm, during this diffusion diffundiert'das first [diffused aluminum mono- further into the semiconductor wafer, so j that The depth of the pn junction is about 43 / u. The alloyed η-conductive zone, which represents the cathode emitter of the arrangement, forms a pn junction at about 16.5 / U depth of the sheath »-

Fig. 11 shows a diffusion profile, which in the flat Diffusion processes described arises.

If the gallium is diffused in during the second diffusion for a longer period, so that the previously introduced Aluminum diffuses further to an even greater depth, an even higher breakdown voltage can be achieved.

In practicing the invention, silicon crystals are used e aechanii? ch prepared and chemically cleaned according to known methods. The crystals are in a Cuar2rohre introduced with the diffusion source. the Tube will «it. filled with an inert gas and sealed.

■■ - ■ • ■ ^>: > * ν · - ^V H39958

PLA 63/8284

If aluminum is used as one of the impurities, the source may consist of metallic aluminum or silicon which has diffused with aluminum and which is kept at substantially the same temperature as the disks which are to be diffused (between about 1100 u 1300 ° G). The time provided for the aluminum diffusion is preferably chosen to be long in order to achieve a flat gradient at the pn junction * This can usually be between 10 to 50 hours. When gallium is used as the other impurity can uelle _c consist of gallium in the metallic or alloyed form, which, at a different, generally lower _temperature; than the disks which are diffused

".." - "■■■". f should, whereby the steam pressure is controlled and an upper-

■ 17

Area concentration in the order of 10 or 10 ■ atoms / cnr is achieved. Specific parameters in diffusion Most of the two substances are known or 3 can easily be determined by experiment. . "" ■ ... ;;

According to the invention, it is also possible to reverse the order in which the two impurities are diffused in. For example, can be performed with the first diffusion gallium Λ which, although partially evaporates again during the second diffusion with aluminum, but I provides the desired high Gberflächenkonzenträtiön. "Pi ^ ;. 12 shows a typical Diffu§ionspro-fil which of. sucheii

Diffusion processes originates. ; ?

909883/0466 ,

Ln 63/8284

Jis was found to be in accordance with this embodiment of the invention Breakdown voltages higher than air 1000 V can easily be achieved »

When carrying out the invention, the surface concentration, after both diffusion processes have been completed

As noted above, 17 are relatively high - about 10 to 10 atoms / cm ' ⁵ ). This vert can, however, be varied within relatively wide limits, since the alloying of the cathode-imitter alloy has the consequence that the emitter-pn-junction which is then formed lies at a certain depth in the semiconductor material; and it is the impurity concentration at this depth which must be controlled in order to achieve good properties. In general, it has been found that good cathode emitter properties are achieved when the impurity concentration of the diffused base region at the pn junction is between 6. 10 Atoinen / cm to about '3' 10 atoms / cm lies. Therefore, when the surface concentration is relatively high, for example at 10, the emitter must be alloyed deeper than when the surface concentration is relatively low, for example at 10 ¹⁷ atoms / cm ⁵ . -

In Pig. \ 5 is. a diffusion device for carrying out another method according to the present invention \ illustrated. In a closed tube 150, η-conductive silicon disks 1 * 52, which are to be diffused, are provided. In the length of these Ucheiben and

' ΤΑ39958

PLA 6'5 / β2ΒΑ

for gcy / öhnlijh in the same holder 133 there is a plurality of p-conducting ../iliziuniG disks 134 which have been diffused with aluminum up to a surface concentration of etv / 1110 Atarnen / 'Jm *. In addition, a metallic jellium source 136 is attached to one end of the tube and the tube is refilled with argon to a pressure of about 0.2 atmospheres at 25 ° 3. The closed stirrer is placed in a diffusion furnace in such a way that the end on which the gallium source 1;> 6 is located is kept at a temperature of about GOO ⁰ -conductive silicon disks and the p-conductive silicon disks, which contain the aluminum, are at a temperature of about 1215 °. Herr the diffusion is carried out for about 46 hours, it shows _#; that the .-. luniinium penetrates to a depth of about 60 ax and causes a shallow gradient in the impurity concentration. The gallium diffuses to a depth of about 41 / U and

17 causes a surface concentration of about 8.10 ⁼ atoms / cm »-Ea is necessary to keep the gallium at a significantly lower temperature than the silicon, because sicn. otherwise too high a gallium surface concentration results in »"'"■-." / -

In the procedure with simultaneous diffusion, which Just described was a successful diffusion of the first impurity, namely aluminum, achieved when the number of panes diffused with aluminum, which

¹ - y * w, ^.

BADORIQ (NAL "'"'

i 63/8284

serve as a diffusion source, about half the size of that of the to be diffused iSiliconseiben 'is. The usage such diffused aluminum disks is preferred, since the use of metallic aluminum with metallic gallium in the same tube turns out to be difficult to control has shown when the desired diffusion profile is to be achieved.

In the process of simultaneous diffusion of two impurities from different sources, it is important that impurities are used which have clearly different diffusion capacities, at least one difference "by a factor of about 2. As is known, the diffusion constant of aluminum about 5 times larger than that of gallium. When carrying out a refinement with two different steps, the difference in the diffusion constants is less critical, since the control of the time and temperature of the diffusion gives the process greater flexibility. It is even possible to use the same impurity, e.g. 3rd gallium, in both diffusion steps rapid diffusion with a relatively high gallium vapor pressure. The use of the same impurity However, adjustment in the two diffusion steps creates additional adjustment problems which it is desirable to avoid. . appears, and therefore it is also useful here to have two

9Ö9883 / 0A66

^BATH

3 β *

- 'U 3 99 58

■ PLA 65/8284

.: ■ ·. ■ .. · vt \ i ■ - .: . ; ■

Use impurities eu which have different diffusion constants to have.

It goes without saying that the present invention can be used with semiconductor materials and impurities other than those expressed. borrowed are carried out, jvs is within the teachings of the present invention to use two impurities in each semiconductor material, one of which has a diffusion constant of at least twice the size of the other in the particular material used, so that the impurity penetrates deeply with the higher Diffusiönskonstante and 'a shallow gradient of yerunreinigungekonzentration on creating pn junction and the other Verun * - ^":. cleaning the relatively high Cterfiächenkonzentration causes. . · - '-. : _ ■

'■ The following table gives useful examples of basic dimensions * material and contamination. The faster diffusing one

Impurity is stated firstί

Base material impurities

n-type silicon aluminum and either allium

or boron

n-type silicon boron and either indiura or

'''.. ■ ■ ...-....-., ■: thallium *

p-1 sided silicon phosphorus and either aismuth,

Arsenic or antimony

. η-conductive germanium indium and thallium p-type germanium. Arsenic and either "bismuth, anti-

mon or phosphorus

_ _{? 4} _ '90988370466

; - ;; ■ ν- BATH.

M439958

PLa 63/8284

Base material

Impurities

p-type a germanium p-type germanium η-conductive indium arsenide η-conductive tndium arsenide

Bismuth and phosphorus antimony and phosphorus zinc and magnesium cadmium and Z ink

The diffusion parameters that match in each case can be determined by the Semiconductors skilled in the art can be selected in accordance with known methods.

Although the present invention with reference to certain Examples have been described and illustrated, it is clear that it is not limited thereto, but that various Modifications without deviating from "the general thought possible are.

13 figures

15 sponsors fcano claims

809885/0468

BATH

Claims (1)

"i ** vJ <J '<* " JU 6i / ö284 Claims 1. Method to manufacture a; iial stay edify learn to, insj a special calibrated reactor of the pnpn type. the in : a monocrystalline semiconductor body containing at least I has a certain conductivity type on one flat side, from this side of the flee a leading ί Ability type causing impurity * diffused in JL. ■. - "■ .- ■ - - ■■■" ■. I _f is characterized in that the two mindectena the ent-1-type of conductivity inducing impurities ■ - are diffused -. '. ί 2. Procedure nacii ^ hcpruüh T, dadurcL characterized that in : ■ - a physique n-lead.ep.dem silicon aluminum and allium are diffused. '..-...-. . ·. "5 * method according to claim 2, characterized in that in - a body made of η-conductive silicon with a specific one * Resistance of about 1 to 50 ohm cm aluminum with a - I surface concentration from about 10 atoms / cm '' up to a depth of 25 to 125 / U is diffused and gallium with a surface concentration of around 10 to 10 .... Atoms / cm to a depth of about 5 to 50 ./U. ^ 4, method _{according to claim I 1} in that both impurities are combined by alloying in a diffusion style, from which the impurities are uncer - ■ V ■■■■■; -26- SOS883 / O466: _t ^; i, ι 3ate-3 das An4 & nj, n (sssm. v.4 'i * Ä * - U39958 PLA 63/8284 Application of heat diffused into the semiconductor body will. . 5 «The method according to claim 4, characterized in that the Diffusion source is made from a body made of p-type silicon on which an alloy of 0.5 to 50 ßeMohteprojsent gallium and 50 to «99» 5 percent by weight aluminum is melted * 6. The method according to claim i, characterized in that for Manufacture of a semiconductor chromtoree in a disc shape Semiconductor body of a first conductivity type , on all sides aiwei the opposite conductivity values type-causing impurities are diffused in, . that the resulting zone of the second conductivity type is divided into two electrically separated zones, that on one of these zones another zone of the first conductivity type is produced, and that ohmic centacts ; attached to the two zones created by diffusion ' "will. 7. The method according to claim 6, characterized in that in a disk made of η-conductive silicon with a special - ι fishing resistance of about 10 to about 50 ^ hm cm aluminum! iitomen having a surface concentration of about 10 / cm "zn to a depth of about 75 / u and gallium with a \ surface concentration of about 10 atoms / cm ⁵ to a depth of about 25 / U is diffused, - 2 "- 90 98 8 3 / (H 6 6.: I / 3-BAD CmiGli4At ^ 'v ^ FLA 63/8284; 8. The method according to claim 1, characterized in that the " both impurities in two temporally separated contaminations * Fahrensufen be diffused into the semiconductor body. 9. The method according to claim 1, characterized in that the both impurities - in a common heating process are diffused into the semiconductor body from two separate diffusion sources. 10. The method according to claim 9 »- characterized in that the both diffusion sources at different temperatures being held. 11. The method according to claim 8, characterized in that in a body made of conductive silicon with a specific ■■■■■■ ■ -. · -. "■ - ^: '-' ■ ■■ - '^ e>. Resistance-from about 20 ohms to about JO ohm cm aluminum with a surface concentration of about 10 / itomen / cm ⁵ to a rate of about 25 bis ^ O / U diffuses in v / ira and gallium with a surface concentration of about 10 to TO atoms / cm to a shallow depth. 12. The method according to claim 8 _9, characterized in that for the production of a semiconductor leakage circuit in a body made of "n-conductive silicon with / a specific resistance of; about 20 ohm cm to about 30 ohm cm aluminum with a top «. j surface concentration of about 10 atoms / cm ^ up to a "C * ■ -. ■■■■■■■■■ = ..; -. ■■ ■■: - ■ - -, r : ■ ■ '■■■■■■■ = ^' ■ "" ■ ψ Depth of about 25 to 50 yu is diffused in that gallium " ρ « BATH PLA 6V8284 bx3 su a shallower depth is diffused, that the resulting p-conductive zone is divided into two electrically separated zones, and that in one of the resulting p-conductive zones by alloying a metal foil which contains a contaminant causing η-conduction, an η-conductive zone is generated, which is embedded in the p-conductive zone up to a depth _r in which the impurity con Atoms / cm. Impurity concentration around 6. 10 ° to 3. 10 tjJ. Semiconductor component manufactured according to the method according to ^? .nspruch 1, characterized in that both contamination of are ^l lialbleiterkörpers incorporated in the semiconductor material up to _t different depths from the surface, and that to a greater depth built-contamination, the depth determines a pn Jbergangs and the other I the Oberflächenkonsentration . ^: 14. Semiconductor component according to claim 1j _f , characterized in that it has a pnpn-xUifbau, and that the pn-junction produced by J diffusion represents the middle pn-junction between the two base zones of a semiconductor fcromtores. ' 15. Semiconductor component according to claim 14, characterized in that that the one base zone made of n-conducting silicon . with a doping concentration of about 10 atoms / cm - ²⁹ ■ «09883/0466 BADOFHQlNAf Ρω 65/8284 . exists, and that the other base zone consists of aluminum and gallium p-doped silicon with a surface concentration of about 10 ¹⁷ to ¹⁰ atoms / μm ^J , and is about 50 to 63 vU thick. - 30 - BADOR101NAL Read 1 1 e