DE1943029B2 - DEVICE FOR CONTINUOUS DEPOSITION OF A DOPING AGENT ON THE SURFACE OF SEMI-CONDUCTOR PLATES - Google Patents

Description

The ilrfindiing relates to an apparatus for continuous Depositing a dopant-containing material on the surface of semiconductor chips. with a tubular chamber, the at least one supply line and an outlet opening for Ciase which contain the dopant, and which at their ends have an inlet or outlet opening » for the semiconductor wafers.

Such a device is already known (French patent 1511289), in which the inlet and outlet lines for the cages are spaced from one another and run transversely to the chamber. Furthermore, the 1 semiconductor plates are sent through the chamber with the help of such carriers, which have the shape of a container and at one end have a window whose shape corresponds to the cross section of the chamber, so that the chamber is divided into sections by these disks. This known device enables / was a consistent working, but a uniform · -. The semiconductor single doping ^r pliittchen not assured, since svegen the transverse to Kammerlaiigsrichlung inlets and outlets for the (were reading and the non vorbeistreiehen lent older form of the semiconductor wafer, the dopant-containing gases in an even flow to the Halbleiterplätlrhen. Negative affects also from . that the chamber segments formed by the carriers for the semiconductor wafers are constantly improving compared to the inlet openings for the gases. Finally, it must be ascertained whether it is possible with the known device ^ cliiiitlen individual Kamnierab. son ⁽¹ PHfIi i.ini (ii> only cooling and Anssärmcn

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13 which are supposed to serve as a conduit, with regard to which it is relatively high; because the disks arranged on the supports for the semiconductor wafers and forming the camnier sections cannot be precisely matched to the cross-section of the chamber, otherwise they will wedge in the chamber in view of the temperature differences.

The invention was therefore based on the object of sounding a continuously operating device, which ensures uniform doping of semiconductor wafers and the same doping lines. Starting from a device of the type mentioned at the outset, this Auigabe is according to the invention c.tdureh solved that the supply lines for the gases are only provided at the chamber ends and that the inlet and outlet openings for the Semiconductor wafers are the outlet openings for the Ciase form. Characterized in that in the device according to the invention containing the dopant Gases have to flow all along the chamber, these gases sweep in a steady flow past the semiconductor wafers to be doped. Furthermore, the chamber is covered by the carriers for the EIaIbleiterpläitchen does not have to be subdivided, these can be passed through the chamber much more easily transport, as lower frictional resistances have to be overcome. Another difference compared to that the known device, namely that no special lines are provided for the outflowing gas are, but that the gas escapes through the inlet and outlet openings for the semiconductor wafers and is sucked off there, leads to the further advantage that in the reaction space of the chamber a certain overpressure prevails, which prevents the penetration of polluted atmospheric air through the Prevents entry and exit openings for the semiconductor wafers.

Experiments have shown that an optimal doping can be achieved that the openings in the form of gates extending outwardly from opposite ends of the chamber are trained; Particularly beneficial results are achieved with gates that are tlie etsva 10 cm long.

In order to maintain the opening of the overpressure inside the chamber, it is ultimately advantageous if the openings in the gates are as large as the carriers and the small lead plates. ie. when the openings are just big enough that the carriers equipped with semiconductor p'iüclien barely allow the chamber to enter the chamber. can be pushed into these envelopes.

On the basis of the drawing, there are particularly advantageous ones Α - ''. Fülmmgsformen the inventive Device explained: e- shows

Fin. 1 a first fill-in game. being to Verdeuilichuiii '. Tier Darstelluni ¹ , a part of a furnace that heats you chamber was relearned.

Fig. 2 shows a typical carrier for two semiconductors plate, as it is in connection with the one shown in Fig. device shown is used.

Fi g. 3 shows a milder embodiment of a Niederschlatisrohrs for the device according to the invention and

F i μ ,. 4 shows a third embodiment of such an electric strike tube.

The device according to the invention is provided with a low-temperature pipe, this a chamber aiii sseist, which is semicircular in cross-section

in and an ehi-ncn testicle shark. Opposite flatness is not particularly important. By clcn

the ends hesii / i the hcvoi / uutc Auslühi uimsliinu I lalbkrcisqucrscliniit be the G;: se da / u uchracht.

of the discharge pipe / ulciiunmn ITn gases and only flow over the surface of the planchen / u,

fine l'.iniriiis- and Ausiiiiisioie. whose Ollnungeii during liei use of a full circular cross

jjcrade are large enough to accommodate the mil I lalhleiierpläii- S schiiiils the iiase even under the planchen \ orbci-

small back carrier duich / ulasscii. while the can flow, making the Sirömuiigsverlaiil del

Vimi Niederschlagsriiiir formed Kammei in the rest of the hare in the chamber 13 is more difficult to regulate / ti.

closed is. The chamber is part of a. Although other materials for the tube I-

() l'en surrounded, whereby the temperature of the duich are usable, is Ouar /. since it is relatively inert.

The chamber led I sometimes preferred to the iu.

Desired deposit temperature can be increased in order to achieve an even flow

can. reach chamber 13 / u, extend double

In a preferred embodiment, gas inlets 14 are through inlet end 15 into the canisters.

zvwi CiaszuleiungLMi at the end of the chamber wirger 13, while further double gas inlets

see, at which the bullets are fed into the lower 15 16 through the projecting end 17 into the chamber 13

Enter the hammer tube and stretch through these connections. Tests have shown that with double

If a carrier gas such as nitrogen, furthermore oxygen is admitted a better uniformity can be achieved

and a gas containing a detergent, more urgent than with a single inlet on both pits, and

directs; there are also two at the other end of the chamber, and better results can be achieved with inlets

Gus feed lines provided, through which, however, expediently 20 at both ends of the chamber as m. ' an inlet

moderately only one carrier gas is introduced at one end only. Also, cIL have results

Carriers for the semiconductor wafers are shown in that the double gas inlets 14 and 16

linder at the entry end of the Nieuerschlagsrolir should reach about 4 cm into the chamber 13,

leads, each carrier preferably two horizontal so that the entering gases before they over the plate

! contains actually arranged semiconductor wafers, 25 surfaces flow, are suitably heated, whereby the

A uniform evenness is improved in the discharge pipe.

Layer of a compound containing the dopant. At the inlet end 15 of the chamber 13 is an egg 11-

cni, attached to the surface of each semiconductor entrance gate 18, while at the Arstrittsende 17

plate deposited, whereupon the carrier with the chamber 13 an exit gate 19 is attached.

ilalblei'.clättchen the precipitation! ·! Iir around 30 In order to achieve optimal doping, the

leave the entrance gate. A conveyor device brings the length of the gates about K) cm, whereby

Search results pushed out of the precipitation pipe have shown that shorter gates close

ger ztiir. Feed end of the precipitation pipe lead to a lower doping of the platelets,

back to where the die removed and both gates 18 and 19 are under the gas inlets 14

the empty carriers are loaded again. There are 35 and 16 arranged in such a way that the bottom of each

Devices with the help of which the semiconductor plate gate is flush with the bottom of the chamber 13. so

chen automatically placed on the Trägei and from that a smooth transition of the container zvvi-

These can be removed so that the gates 18 and 19 and the chamber 13 can be seen

proper device, can be seen from the inside achieved. The internal dimensions of the two gates are so

slide and remove the carrier einrpal, 40 selects that the container filled with the platelets

works automatically. The same system is used. 20 go straight through it, leaving enough room for

around the doping solids in the semiconductor platelets the passage of the gases through the gates remains,

to be allowed to infuse in, however, since here over the inlet and outlet ends of the raw material

iIlm 'flow course is not so critical. a wev.nl- res 12 vents 21 are arranged to pass through

borrowed a semicircular tube 45 of simpler design, the gates 18 and 19 emerging from the chamber 13

beniii / i can be used to collect and discharge the plant costs / ii gases / u. The tube 12 is

reduce. außei at the ends 15 and 17 of the chamber 13 through

Although nii'ii could get by with a gas supply at one of the insulation 4 and by heating windings 3 around the end of the low-height pipe. connected to a power source (not shown), as already mentioned. Gas / iik'iiimgcn 50 are closed. A conveyor belt 22 that is preferred no closer to both E.iden. Furthermore it is shown in detail. is used in order to return the loads exiting at least one of the gas lines to the exit gate 1 of the pipe 12, the double inlet with white containers to the entrance gate 18 after it has opened. It is advisable to use the white ^ iMi. which the platelets have been removed from them, / to preheat the filled gases, which is why: s / wake-up 55 whereupon the containers are used again,
is moderate. When at least one of the gas lines is in operation, the chamber 13 will extend approximately K) cm into the interior of the chamber through the . ! ei / vvicklimgen 3 extended to a desired one. In this case it is recommended, but it is heated at a given temperature, in order to heat the surface for the purpose of simplification both inlet openings and all plates 8 to a desired lowering of the double inlet temperature at a common feed temperature while they are connected through the line. Chamber are performed. To get a rainfall with

In Fig. I is a device according to the invention P-conductivity to obtain oxygen, a

10, a preferred embodiment is a carrier gas, such as nitrogen, and a doping gas, such as

a precipitation pipe 12 contains. The tube 12 boron tribromide (BBr.,), Which can be obtained from a liquid

has a lower hunting chamber 13, which is given the shape of a 65 reservoir, through the double inlets 14 cinge-

Has a cross-section and has an im, boron being the dopant. Even though

has essentially flat ground, in contrast. the same gas mixture also through the double

TO a complete pipe, although the degree lasse 16 can be inserted, this is not necessary.

derlich, which is why through the inlets 16 normally only the carrier gas is introduced, mainly to generate a uniform flow path the gases in chamber 13. The gases exit chamber 13 through gates 18 and 19 the end. The tube 12 may be provided with gas vents (not shown) which connect to the inlet and outlet ports Exhaust gates are connected to evacuate the gases. However, it was found that such vents did work are not necessary, as the gates 18 and J9 have enough space for the gases to escape Offer.

It was also found that when a deposit is made of the P conductivity on SiIiciumplättchcn with a group of gas streams uniform precipitation in a temperature range from about 800 to about 1200 C achievable are. A typical gas flow consists e.g. B. from 3.5 1 nitrogen / min, through the inlet 16. also 3.5 1 Nitrogen / min., 20 ecm oxygen / min. and 6 ecm Nitrogen min. through inlet 14, the latter StickstolT Amount by liquid boron tribiomide to be led.

For the production of a precipitate of the nitrogen capacity on silicon wafers the flow rate is not the same! for all low temperatures used. Flow rates in the range between approx. 775 and approx. 900 ° C are suitable !! from 2.75 l nitrogen / min, through inlet 16. further 2.75 l nitrogen. Min. 80 ecm oxygen T / min. and 120 ecm nitrogen min. Through inlet 14. where the latter nitrogen is passed through liquid phosphorus oxychloride (POCE.,). Between about W) O and about 1200 C are suitable flow men of 3.25 1 nitrogen min. through inlet 16, further 3.25 1 nitrogen min. 180 ecm oxygen / Min. Through inlet 14, the latter amount of nitrogen being replaced by liquid phosphorus oxychloride is passed through.

At the beginning of the deposition, an empty tray 20 is placed at the loading end of the device in front of the Entry gate 18 turned off. The container shown in FIG is shown. can be a flat trough with space for two tiles on its surface. the Be arranged side by side. Two plates 8 are placed horizontally on the carrier and through Pins 23 held, which protrude slightly above the surface of the Träaers. The carrier 20 can, for example au · - qua; / exist. However, E ^ is used as a carrier material Graphite proreezoeen. eggs coated with silicon carbide is; because between silicon carbide and quartz the The coefficient of friction is smaller than that between quartz and quartz. The choice of material for the wearer is significant in that. if the quartz tube is cefiillt with straps. as it did while driving ahead the case is. the frictional forces can become large. These frictional forces determine the operating speed until the pipe 12 needs to be cleaned. which is expensive and tedious and therefore as possible should be pressed down to a minimum !. For this reason, a material other than quartz is preferred for the carrier.

The temperature of the chamber 13 is chosen so that the center of the flat floor is slightly lowered. so that only the edges of the bottom of the carrier 20 rest and run on the bottom of the pipe, whereby the friction between the chamber 13 and the tracers 20 is reduced.

The loading and unloading of the '! "Rager takes place outside the pipe 12. This reduces contamination of the pipe, as no other Material than quartz of the chemically and thermally aggressive environment in the chamber 13 is longer Can withstand time and maintain a high level of purity. Instead of the carrier 20 through pushing the tube 12 through;. · in consideration be pulled, a kind of conveyor belt to ve γιο apply, however, it was found that no material in the long run the extreme environmental conditions in the pipe 12 can withstand. The empty carriers are at the loading end of the device load automatically. The drive of the tear!

takes place by a motor, not shown, which is connected to a drive mechanism, not shown is. which acts on the carrier, which is arranged in front of the emirite gate 18. Every trigger presses the previous one in front of you and through the tube 12, the driving force from the driving mechanism is exercised on the last Träjier in the container train.

While the platelets 8 are passed through the chamber 13, their surface temperature rises.

a5 temperature so far. that the dopant, e.g. B. Bor. At P-conductivity if boron trichloride as doping agent is used, or phosphorus in the case of N-egg capacity. when phosphorus oxychloride is used as a medication agent is used, with the oxygen and the silicon reacts and settles on the hot surface the platelets as vitreous boron-silicate-yerbinduiiL precipitates when boron is used and as glass like phosphorus silicate compound, if Phosphoi and when silicon wafers are used. Dk speed with which the platelets pass through da-pipe and the flow rate and the concentration of the gases determines the rate of deposition of the doping layer on the surface of the platelets. These pam meters are checked before the start of the Niederschiacszyklu * determined and changed depending on the desired surface resistance of the plate, and zwa after the subsequent diffusion-oxidation process step. The lazy ones covered with platelets

leaving the pipe 12 through the exit gate 19, 11 nc are transported by the conveyor belt 22 to the unloading end of the device 10, where the pieces are automatically taken out of the containers: i. The empty bins are then / \ v:

The end of the feed is transported back in front of the entrance gate 18 and loaded with new semiconductor wafers load, whereupon the cycle is repeated.

In Fig.! is a preferred embodiment of the pipe 12, through which a max:

male uniformity and flexibility achievable i- · However, a less precise implementation can also be achieved The tube 33 shown in Fig. 3 can also be used for the diffusion and oxyda tion can be used. has the same chamber 13 with a semicircular cross-section as the tube 12. On one: An entry gate 18 is at the end of the chamber 13 and an exit gate 19 is seen at the other end. Whom no need for a throttle down ii the chamber 13 consists such. B. when lioh If sheet resistances are desired, the gate 18 and 19 can be omitted or made shorter. Individual gas inlets 24 open on both Ends in the chamber 13 but extend!

not into this, so that the incoming gas is not heated before it enters the chamber itself. The individual gas inlets 24 do not result in such a uniform flow profile in the chamber 13 like the double inlets shown in FIG are, however, they can be used especially for diffusion and oxidation, if the flow course the gases in the chamber is not too critical.

In Fig. 4, a further Ausfülirungsform a precipitation pipe 25 is shown. The Chamber 13 has the same shape with a semicircular cross-section as in the tubes 12 and 33. The tube 25 has an inlet window Exit gates 26 which do not protrude from the chamber 13. Instead, those who have decided have

Ends of the chamber 13 ÖITniingen 26, which are sufficient. to insert the containers in the chamber 13 and remove them. At opposite ends of the Chamber 13, double gas inlets 14 and 16 are provided which extend into chamber 13 and are long enough to preheat the incoming gases. Because as a result of the lack of elongated There is no back pressure as with the above aluminum embodiments such high doping levels cannot be achieved with the tube 25, in particular at low temperatures. such as B. below 900 "C.

The deposition chamber can be any combination of Gascinlässen and gates used ^first

1 sheet of drawings 109 583

Claims (4)

l'alcniunsi -he: 1. \ <Ii ι i ι ii iiu for the koiuinuici borrowed deposition of a painting containing a doping agent aiii the surface son I semiconductors. with a tubular chamber, the at least one feed line and a Auslaßölfnuiig for gases containing the Diitierungsniillel and the .nden at their I ⁷ has a FJn- or an exit in cilTiniiig for Halbleiterplüuchen, characterized in that the supply lines in the gases (14, 16) are provided only at the chamber ends, and that the input and / or. Austriiisölfiumgen (18, l ^l >) for the semiconductor plan (8) form the outlet openings for the Ciase. 2. Apparatus according to claim 1, characterized in that ύ'.ζ openings (18,19) in the form of son the opposite ends of the chamber (13) from outwardly extending gates (Fig. 1 and 3) are formed. 3. Device according to claim 2, characterized in that that the gates are etsva 10 cm long. 4. Apparatus according to claim 2 or 3, with carriers for the semiconductor wafers, characterized in that that the openings of the gates are as large as the carriers (20) including the semiconductor devices are. 30th