FR2537778A1 - METHOD FOR METALLIZING A SINGLE CRYSTALLINE SILICON PLATE - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS FOR MANUFACTURING SEMICONDUCTOR COMPONENTS, AND IN PARTICULAR FOR METALLIZING A SURFACE PART OF A MONOCRISTALLINE SILICON Wafer. A THICKNESS OF AT LEAST ONE MICRON IS REMOVED FROM A METALIZED SURFACE PART TO REMOVE ANY OXYGEN CONTAMINATION, THEN A THIN LAYER OF NICKEL 70 IS DEPOSITED ON THE SURFACE PART 60, 61 AND IT IS CONVERTED INTO A PART OF ITS THICKNESS IN NICKEL SILICIDE, THEN AT LEAST ONE LAYER 71, 72, 73 OF A CONTACT METAL, IS DEPOSITED ON THE NICKEL. THE INVENTION APPLIES IN PARTICULAR TO THE MANUFACTURE OF HIGH-POWER SEMICONDUCTOR COMPONENTS.

Description

The present invention relates to

  semiconductor components and more specifically

  Firstly, a novel method of manufacturing multiple semiconductor components from a common wafer. The initial phases of manufacturing

  semiconductor power components such as rectifiers

  ordered or similar devices, normally take place in a wafer manufacturing facility in which junctions are formed in a wafer

  very large diameter for several components

  After the formation of the junctions in the large wafer, the individual components are separated from the wafer and are then treated separately, usually in an assembly plant. In the subsequent treatment, a contact of expansion plates is first.

  allied beneath the individual elements of a wafer.

  Subsequently, contact metals are applied to the upper surface of the individual elements. This contact metallization process normally requires masking and etching-oxidation for each element.

individual of a wafer.

  This sequence of first combining the expansion contact and subsequently applying metal contacts was necessary because the metal contacts used in the power components are

  usually aluminum The contact metal daliuminium.

  may diffuse into the wafer surface at the alloy temperatures used to apply the expansion contact below the wafer, which could

  disrupt the configuration of the junctions; disseminated.

  After metallization, the outer surface of the individual elements is tapered to increase the initiator voltage of the component. This process involves etching or grinding followed by acid etching to eliminate grinding damage. the aluminum contact can be

  attacked by the acid used in the chamber operation.

  Moreover, it is necessary to protect the metallization by covering it, for example, with a gold plating or with wax before the acid attack operation. All these operations were executed in

  an assembly plant on individual elements

  wafer duals that had to be handled separately.

  Thus, the additional phases and the separate manipulations considerably increase the price of the components

  and reduces the manufacturing yield.

  According to the invention, a metallization is applied to the wafer in the wafer manufacturing plant before it is cut into these individual components. The metallization uses nickel and silver This metallization forms an ohmic contact on the surfaces underlying silicon and can survive after alloy temperatures, used for expansion contact on a

  individual element of a wafer After the metal-

  This element is cut into individual elements. These elements are then alloyed with the lower expansion contacts in a vacuum alloy operation using

  temperatures as high as 650 ° C for 30 minutes.

  Since the metallization has an outer layer of silver, a hot caustic may be applied to the outer surface

  elements of the wafer after the chamfering operation.

  without the need to protect the metal

  The caustic potash is preferably used for the etching operation and citric acid is used for the final rinse. Caustic soda can also be used as an etching product. given that no protection of the metallization is necessary during the attack of the outer surface of the component, several

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  operations are saved, compared to the previous operation of chamfering using an acid and a

  nickel-plated aluminum contact.

  The method makes it possible to manufacture high-power semiconductor components which may be, for example, silicon-controlled rectifiers having inverse voltages of up to 5000 volts and direct currents of greater than about 50 amps. However, the invention may also be used. apply to any high-power component including expansion plate contact and / or

conical outer surface.

  Also according to the invention, when polished silicon must receive a contact, the etching operation is used to remove from 1 to 3 gm of the silicon surface before the application of a first coating of nickel If the attack is less than 1 gm, a

  peeling-layers of silver nickel is observed.

  Above 3 Am, the voltage characteristics and

  gate current of a controlled rectifier are

  A method of treating the surface of silicon is to use an etching product comprising two parts of hydrofluoric acid, nine parts of nitric acid and four parts of acetic acid. The etching solution is applied to the silicon surface. for about 15 seconds that removes about 2 name from a

polished silicon surface.

  Immediately after the attack operation

  a layer of nickel is evaporated on the silicon surface

  treated to a thickness of 125 to 1000 Angstroms.

  The nickel layer forms a silicide in the vacuum chamber if the substrate is moderately heated (more than enough) and if there is a very clean silicon surface. During the evaporation of the nickel layer, the radiated heat from the surface of the boiling nickel delivers considerable energy to the wafer surfaces Similarly, the evaporation of the nickel atoms themselves produces impacts with considerable kinetic energy. Excellent results.

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  were obtained at an evaporation temperature as low as 60 c A 1200 C, the four-layer metallization strongly adhered to the underlying oxide and it began to become difficult to separate from the oxide The thickness of nickel is critical -If it is too big, above about 300 Angstroms, a detachment occurs If it is too weak, below about 100 Angstroms,

  the metallization does not come off the oxide.

  It turned out that if the layers of metal-

  they cover an oxide layer above the

  silicon surface, the metallization comes off easily-

  of the oxide layer but adheres very well to the

  silicon surface exposed and treated.

  In addition to strongly adhering to underlying silicon, but not to oxidized silicon, metallization

  above also has the following characteristics:

lowing

  (1) Metallization is temperature resistant

  alloys during the following operations of manufacturing a semiconductor component, such as temperatures of 6500 C which are encountered in one operation.

of vacuum alloy.

  <2) The metallization establishes a good ohmic contact with the silicon, of type P as well as of

  N type and various resistivities.

  (3) The new metallization has a weak

lateral impedance.

  (4) The metallization is covered by a layer of silver and is therefore resistant to the chemicals used in many of the following operations.

  manufacturing process of a semiconductor component.

  (5) Metallization withstands thermal fatigue that may occur during operation

  of the semiconductor component with which it is associated.

  (6) The metallization is weldable and does not require the use of any welding coating for

  connect wires to the metallization.

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  Other features and benefits of

  the invention will become apparent during the description which

go follow.

  In the accompanying drawings, given by way of non-limiting examples only: FIG. 1 is a plan view of a semiconductor wafer which contains a large number of individual components which are simultaneously processed in a wafer manufacturing facility, FIG. Fig. 3 shows one of the wafer elements of Figs. 1 and 2 after being laser separated from the wafer in a prior operation. Fig. 4 shows FIG. 5 shows the wafer of FIG. 4 after a masking and oxide etching operation, in preparation for the formation of a contact. of the prior type, Figure 6 shows the plate of the figure after the evaporation of an aluminum contact on the

  upper surface of the component, according to an earlier method

  Figure 7 shows the wafer of Figure 6 after the aluminum contact has been plated with gold plated nickel and peeled off oxide, with the edges of the ground device and the sprayed wax on the upper surface, FIG. 8 shows the device of FIG. 7 after previous operations of chamfering, etching, wax removal and application of a varnish on the outer surface. FIG. 9 shows the plate of FIG. photographic masking operation and oxidation etchings of the non-separated wafer, and after the new silicon etching operation to prepare the metallization surface, FIG. 10 is a large-scale figure of a portion of the wafer. FIG. 9 after metallization with four successive metal layers which strongly adhere to the treated silicon surface. FIG. 11 shows the structure of FIG. 10 after a sintering operation and delamination wherein the metallization is separated from the oxide coating on the silicon wafer, Figure 12 shows a separate element

  of the plate of Figure 2, 9, 10 and 11 by an ope-

  laser separation and shows a molybdenum contact which is then alloyed with the element and FIG. 13 shows the device of FIG. 12 after chamfering and treatment with a hot caustic product and the application of a coating passivation on the outer surface of the component. First, FIGS. 1 and 2 show a current-type silicon wafer 20 which may have any desired configuration and whose thickness is considerably exaggerated to clarify.

  plate 20 may have a diameter of 100 mm and a thickness of

  0.25 to 1 mm, typically 0.375 mm -The wafer is processed in a suitable wafer manufacturing facility that ensures extreme cleanliness

  for the treatment of a wafer in the desired manner.

  As an exeraple; the plate of figures 1 and 2 has been

  treated to form junctions for several

  Thus, the entire wafer 20 receives a layer 21 of type B followed by a layer 22 of type N, followed in turn by a layer 23 of type P Controlled rectifiers to be formed comprise a configuration central grid and all include an N-type annular cathode region 24 The underlying P-type layer 23, which is the gate region of each component is exposed in the center

of each annular region 24.

  The final phase of the manufacture of the wafer in the prior art for the wafer

  set 20 is the formation of the cathode regions 24.

  During this operation, which is generally a diffusion operation, an oxide layer 26 is produced by growth on the surface of the wafer 20. This oxide layer 26 may have, for example, a thickness of 1.25 gm and is used during the next processing of the component. It may be desirable to continue with the processing phases to complete the components

  formed in the plate of Figures 1 and 2 in the

  The platelet fabrication plant is better suited to perform operations such as masking, oxide etching and the like. In addition, it may be desirable to metallize the various P and NW regions of the wafer surface of FIG. receive contacts or electrodes while the wafer is in the wafer manufacturing facility But this can not be done with the existing contact systems, such as aluminum, risk-diffusing in the silicon during the phases of The following alloys are required for attaching expansion plate type contacts to the bottom surface of the wafer elements.

  manufacture of Figures 1 and 2 were taken out of

  manufacture of wafers.

  The wafer elements, like the elements 25 of FIG. 3, were then separated from the wafer, for example by laser. In the example of FIGS.

  2 and 3, seven elements of individual circular inserts

  25, each having a diameter, for example 18 mm, are separated from the wafer. When their treatment is completed, the elements 25 must be used in controlled rectifiers which may have nominal reverse voltages of up to 5000 volts and nominal direct currents greater than 50 Amperes Different numbers of elements may be cut out in the

  plate 20, in function of the nominal value of the com-

  It should also be noted that the descrip-

  The invention of the invention will be directed to the example of a controlled rectifier. However, the invention may apply to any component formed in a silicon wafer regardless of the number of junctions or their configuration, and could also apply to the manufacture of a single component in a single

wafer.

  All phases that follow the laser cutting operations of Figure 3 are generally performed in an assembly facility that is not as clean or as well controlled as the platelet manufacturing facility but the conditions in the assembly facility are of normally quality

  sufficient to allow the following operations to be carried out

  which are described with reference to Figures 4 to 8

  relating to the prior art.

  In the first operation performed, and as shown in FIG. 4 for the individual element 25, a plurality of individual elements 25 are allied with expansion plate contacts such as the contact 30,

  which may be molybdenum or tungsten or the like.

  In general, the contact 30 is a molybdenum contact with the same diameter as the wafer 25 and a thickness of 0.75 to 3 mm, generally 1.5 mm It should be noted that the relative dimensions of the wafer and contacts are

  in Figures 4 to 8 for clarity.

  binding of the contact 30 with the wafer 25 is at a

  relatively high temperature O Therefore, the operation

  prior alloy ration was performed prior to application

  cation of the aluminum contacts to the regions 23 and 24 of the wafer 25 because an aluminum contact can diffuse in these regions at the alloy temperatures and form

  a P-type region in the N-type region 24.

  Then, and as shown in FIG. 5, the upper surface of the individual elements 25 is

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  photographically masked and the oxide layer 26 is etched to cover an annular window 31 on the annular region 24 of type N and to open a window

  central 32 in the center of each pellet element 25.

  The window 31 can then receive a cathode contact for the controlled rectifier while the central window

  32 can receive a gate contact.

  As shown in FIG. 6, an aluminum contact layer 33 is then evaporated or applied

  by any other means on the upper surface of the

  The layer 33 penetrates into the windows 31 and 32 to make contact with the cathode and gate regions of the pellet elements 25.

  aluminum layer 33 may have a thickness of 0.125 nm.

  The wafer member 25 of Figure-6 is then placed in an oven and exposed to elevated temperature in a neutral or reducing atmosphere to sinter the aluminum layer in the silicon surface and decompose the photosensitive layer L '. aluminum does not adhere to the underlying oxide layer 33 but adheres to the decomposed photosensitive layer. Next, after the sintering operation, the aluminum which covers the oxide 33 is easily peeled off and the aluminum remains only in windows 31 and 32, adhering on the surface

  silicon of the wafer element 25.

  Then, and as shown in FIG. 7, the upper surface of the wafer is plated with nickel, the nickel plating adhering to the upper surface of the aluminum contact 33 The nickel plating has a thickness of about 0.75 μm and is weldable for conductors that are subsequently applied. After the nickel plating operation of FIG. 7, gold is plated on the nickel to a thickness of 3000 Angstroms. The nickel and gold layers are The gold plating is used to protect the underlying nickel and aluminum from the acid-etching attack which will follow. The upper surface of the wafer member 25 is then covered with a coating. of wax 36 which protects the coated surfaces

  against attack by an acid used next.

  Then, and as shown in FIG. 8, the outer surface of the plate 25 is chamfered, for example by grinding. The chamferin shown in FIG. 8 has a first conical surface 40 which makes a first angle of intercept of the the wafer of about 35 at the reverse junction between the regions 21 and 22 A second conical surface 41 is also ground, making a second intercept angle between the outer surface of the wafer element and the direct junction between the regions 22 and 23, from 20 to 100, for example 4 It should be noted that these angles are not shown in scale because the dimensions of the component have been greatly exaggerated for the sake of clarity. The component is then subjected to an acid attack on the outer surface. This acid attack can not attack what remains of the nickel-plated aluminum contact because it is protected by the gold layer and the layer of wax that covers it. FIG. 8, the wax layer 36 is then peeled off and

  the component is subjected to a slight polishing attack

  A varnish layer 50 is then applied to the outer surface of the member 25 to pass the edges of the etched junction. A suitable silica product may also be applied to the wafer member. The entire component of Figure 8 can

  then be mounted in a box Electrical contacts

  can be established with the cathode and grid contact layers that are exposed through the windows

31 and 32 -: -

  The novel process according to the invention, which replaces the process described with reference to FIGS.

  will now be described with reference to Figures 9 to 13.

  As shown in FIG. 9, it is on the same page as FIGS. 1 and 2, the plate of FIG. 2 is subjected before the laser cutting operation, to a simple photographic masking and to an attack which opens windows in the oxide layer 26 to expose the cathode and gate regions of each of the individual elements 5 before they are separated from the wafer 20 Thus, as shown in FIG. 9, windows 60 and 61 which are respectively an annular window and a central window are located on the respective regions of annular cathode 24 and gate

  of each of the elements 23 defined in the

  By way of example, the oxide etching process for opening the windows 60 and 61 can utilize a common buff oxide attack. These operations are performed in the platelet fabrication facility which is designed for this purpose. It should be noted that the equivalent masking and etching process has been performed in the prior art during the phase of FIG. 5 for each of the separate elements.

  in a platelet assembly plant -

  After opening the windows 60 and 61, the exposed surface of the silicon wafer 20 is treated in a new way that allows the desired contact metals to adhere strongly to the treated silicon but not to the surrounding oxide. desirable to use a contact metallization of

  nickel, chromium, nickel and silver for

  high power silicon (those having a nominal direct current greater than about 50 amperes) if the contact metals adhere securely to the underlying silicon surface after high temperature processing operations such as those used to combine Expansion plates with individual components But so far, the adhesion of metals in this arrangement was not safe because the silver layer

  superior was frequently detached from

  are non-controlled and apparently arbitrary.

  In addition, the lower nickel layer sometimes formed

  bubbles from the underlying silicon surface

  core. According to the invention, and to ensure that the

  metallization adheres securely to the sub-silicon

  the following prior treatment of the surface of

  silicon exposed by the windows 60 and 61 is used.

  After the windows 60 and 61 have been opened by the

  elimination of the oxide according to FIG. 9, it is assumed

  that the exposed surface of the silicon is oxide free.

  In fact, there is a saturated silicon layer of oxygen below the contact surface between the silicon and the silicon dioxide. Thus, a sufficient amount of oxygen is released by the upper surface layers of the silicon substrate. to cause a lack of adhesion and delamination of the layers

  metallized during a subsequent sintering operation.

  According to the invention, a new etching product is used to eliminate a sufficient thickness of the

  silicon surface exposed to ensure that the surface.

  exposed to be completely free of oxygen It has been found sufficient to remove about 1 to 3 gm of the polished surface exposed by the windows 60 and 61.

  Preferably, two microns should be removed.

  It turned out that the problems of taking off

  -25 ment are present if one micron or less is removed from

  If more than three microns are

  the voltage and current characteristics of

  grid are unacceptably modified.

  The etching of the silicon is preferably carried out using an etching solution consisting of 2 parts of hydrofluoric acid, 9 parts of nitric acid and 4 parts of acetic acid, this solution being applied by windows 60 and 61 on the silicon surface

  exposed wafer 20 for about 15 seconds.

  Then, the wafer 20 is placed in a rinsing bowl for about 5 minutes to remove the acid.

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  After rinsing, wafer 20 is

  exposed to a slight attack by 50 parts of

  This operation removes the chemical oxide that remains after the initial attack using nitric acid as a constituent. The wafer 20 is then rinsed in a bowl for about 5 minutes and is dried. spinning in the usual way. The metal layers 70 to 73 of Fig. 10 are then applied to the treated surface by vacuum evaporation techniques. For example, after pumping a vacuum for about 15 minutes, the substrate is heated to about 1250 ° C. the pressure has decreased to about 5 x 10 6 torr, a first layer of nickel 70 is evaporated on the surface to a thickness of 125 to 1000 Angstroms, preferably 200 Angstroms The nickel layer 70 must have a sufficient thickness to allow its conversion to nickel silicide during the deposition operation The substrate must be at a temperature of 100 ° C or higher, during the

  deposition of nickel to facilitate its conversion to silicide.

  The purpose of the silicon attack operation

  is to eliminate any source of oxygen from the treated surface.

  It appears that there is normally an oxygen-saturated silicon layer immediately below the surface Si O 2 / Si Si - this layer is left undisturbed during silicide formation, it appears that oxygen atoms of the region considered become extremely mobile and diffuse upward to be trapped on the contact surface between nickel and silver The end result is an oxidized film that destroys the contact surface between nickel and silver, which

it results from the detachments -

  In addition, the nickel layer 60 produces bubbles from the substrate if oxygen is present in the latter below the nickel after the end of the metallization. However, the etching of the silicon eliminates any trace of oxygen from the substrate. the exposed surface of the monocrystalline silicon wafer and solves the problem of delamination at the contact surface between nickel and silver as well as the problem of separation between the

nickel and silicon.

  The layers 71, 72 and 73 respectively of chromium, nickel and silver are then evaporated separately on the layer 70 as shown in the figure. The wafer is then allowed to cool to

Room temperature.

  The chromium layer 71 has a thickness sufficient to act as a diffusion barrier and may have, for example, a thickness of 500 to 3000 Angstroms, preferably 1500 Angstroms. The nickel layer 72 has a thickness sufficient to prevent the erlission of silver. from the layer 73 to the layer 71 and may have for example a thickness of 1000 to 6000 Angstroms, preferably 4000 Angstroms. The silver layer 73 is thick enough to receive welded connections and must be greater than about 1 Nom,

for example 6 gm.

  After the metal deposition operation, a peeling operation takes place in which the nickel layer and the metal layers 71, 72 and 73 lying above the underlying oxide layer 26 are

  peeled off the oxide as shown in Figure 11.

  To perform this decol-

  the wafer 20 is immersed in demineralized water

  The platelets are exposed to ultrasonic energy for about 15 minutes to release the metal from the insulating layer. The platelets are then exposed to a demineralized water jet which removes all the peeled metal on the layer. The wafer is then rinsed and spin-dried, and then inspected for residual metal. Residual metal must be blown off.

with a jet of nitrogen.

  The wafer 20 now has the general appearance of FIG. 11, wherein the layers 70, 71, 72 and 73 firmly adhere to the exposed regions in the windows 60 and 61. The metallization is resistant to temperatures which are then applied to the

  poses during alloying or other processing operations.

  In addition, the metallization resists certain etching products which are then applied to the wafer elements. Further, the metallization reduces the resistance of the P-type or N-type silicon connections and the contacts are weldable, having low lateral impedance and resistance to thermal fatigue. The metallization also makes it possible to apply a new method to complete the structure of the plate 25 as shown in FIGS. 12 and 13. More particularly, this new metallization allows a vacuum alloying of the individual elements of platelets on expansion plates after the metallization This is because there is no diffusion of contact metal or any damage during the alloy and thanks to the fact that the edge of the junction can be attacked by a caustic attack product which does not attack the metal. 'money

underlying metallization.

  Thus, during the next phase of the entire process, the individual metallized elements of FIG. 1 are cut for example by laser, from the plate 20 of FIGS. 9, 10 and 11.

  The individual is then bonded with a dilatation plate.

  Like the plate 80 shown in FIG. 12 The expansion plate -80 may be, for example, a molybdenum disk having a thickness of 1.5 mm. The vacuum alloying operation is carried out in nitrogen at a pressure of approximately 4 x 10 5 torr at a temperature of about 650 ° C, for about 30 minutes A large number of elements are processed simultaneously Since the vacuum alloying operation of Figure 12 is done after

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  the contact metals have been applied, the different phases of the prior process of FIGS. 5, 6 and 7 are eliminated. After the alloying operation, the outer surfaces of the individual members 25 are ground on a diamond wheel, for example, to form a first conical surface 90 shown in FIG. 13. The surface 90 may form an angle of about 35 with the junction between the regions 21 and 22 Then, a second conical surface 91 is ground, making an angle of approximately with the junction between the regions 22 and 23 These angles are not shown in scale in Figure 13 The elements of platelets 25 are then rinsed with demineralized EA and are cleaned in a bath

ultrasonic cleaning.

  Then, the ground outer surface of the wafer 25 is subjected to a new caustic attack which eliminates the damage to the outer surface caused by the grinding operation. This new caustic attack operation can be performed without the need for use a gold plating or a protective wax, or other, on the metallization layer because the silver layer 73 resists caustic attack The caustic attack fluid is preferably potash

caustic.

  More particularly, and according to the invention, a solution of about 80 g of caustic potash in about 1 liter of demineralized water is heated to about 95 to 1000 C A solution of 80 g of citric acid in about 1 liter Deionized water at room temperature is also prepared. The elements are first placed in deionized water running hot for about 1 minute. They are then placed in the caustic solution for about 3 minutes, the support containing the elements 25 being agitated

  The elements are then taken out of the

  caustic potash and placed in hot water

  demineralized in circulation for about 3 minutes.

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  Subsequently, the elements are placed in the citric acid solution in about 30 seconds while being constantly agitated. The elements are then lined in hot deionized water in circulation for about 2 minutes and then dried, for example

  by radiation under an infrared lamp.

  The wafer elements 25 are then loaded into a coating tray and their surfaces are coated with a passivation coating 100 as shown in FIG. 13. The 100 tru coating of any desired type. Preferably, it consists of a silicone such as Q 1-4935 manufactured by Dow Corning Company After coating with this product, the elements are placed in a vacuum chamber for about 10 minutes and then heated at about 325 ° C for about 20 minutes. The completed elements can then be mounted in a case or be treated

by any other means.

  Of course, various modifications may be made by those skilled in the art to the process described and illustrated by way of non-limiting example without

depart from the scope of the invention.

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Claims (10)

  Process for metallizing a surface portion of a wafer (20) of monocrystalline silicon, characterized in that it initially consists in eliminating a thickness of at least one micron of said surface portion to ensure the removing an inadvertent oxygen contamination in said surface portion, then depositing a thin layer of nickel (70) on said surface portion (60,61) and converting at least a portion of the thickness of said layer nickel nickel silicide, and then depositing at least one layer (71, 72, 73) of a contact metal on top of said nickel layer, said contact metal layer being fixed   tenaciously on said surface portion.   Method for metallizing a plurality of exposed surface portions of a silicon wafer (20), said surface portions being for identical wafer elements which must then be separated from one another, the metallization surface being able to withstand temperatures higher than about 650 ° C and making ohmic contact with N- or P-type silicon, and resistant to a variety of etching products, and readily weldable, by applying an insulating coating to a surface of said silicon wafer, to perform a photographic masking and etching through said mask to expose at least a predetermined surface portion of said surface through said insulating coating, characterized in that it then consists in eliminating a thickness at least one micron of said surface portion (60, 61) while leaving said coating An intact insulator for removing an inadvertent oxygen contamination in said surface portion, depositing a continuous thin layer (70) of a silicide-forming metal above said surface portion and above neighboring surfaces of the insulating coating and to convert at least a portion of 19 2537778 1   the thickness of said metal forms a silicide in a metal silicide, depositing at least one layer of a contacting metal (71, 72, 73) above said layer of a silicide-forming metal, to apply a stress detachment from said metal layers to remove said silicide-forming layer and said contact metal layer above said insulating coating, with the silicide-forming layer and said contact layer adhering strongly on said surface portion of said platelet silicon, to cut said silicon wafer into a plurality of elements (25) which all contain at least one of said exposed surface portions and thereafter to treat each of said plurality of elements to complete semiconductor components respectively.   Process according to claim 1 or 2, characterized in that said thickness of at least 1 gm is removed from said surface by an acid attack product. 4 Process according to claim 1 or 2, characterized in that the thickness of the material removed   of said surface portion is 1 to 3 Dam.   A process according to claim 3 or 4, characterized in that said acid etching product is a mixture of hydrofluoric acid, nitric acid, and acetic acid which is applied to said portion of   surface for about 15 seconds.   Process according to any one of   Claims 1 to 5, characterized in that said layer   nickel has a thickness in the range of 125 Angstroms to about 1000 Angstroms.   Process according to any one of   Claims 1 to 6, characterized in that said layer   of contact metal is made of a material that resists to a product of attack, caustic.   Process according to any one of   Claims 1 to 7, characterized in that said layer Contact metal is silver.   A process for producing a plurality of identical semiconductor components (25) which are simultaneously processed and metallized simultaneously with a plurality of metallization layers while forming part of a common thin flat silicon wafer (20) comprising a first and a second parallel surface, said metallization adhering intimately in ohmigue contact with several parts spaced from said first   surface and able to withstand temperatures that   during subsequent processing operations, said metallization comprising a non-junction metal (70) in contact with said first surface of said wafer and an outer layer of metal   solder that does not react with a caustic   a process characterized in that it consists essentially of   separating a plurality of wafer elements (25) from said wafer (20) with each of said wafer elements comprising at least one respective region of metallization on at least a portion of its first surface, to secure a respectf (30) plate contact dilating on the second surface of each of said wafer elements, and etching the outer surface of each of said wafer elements with a product of caustic attack.   The method of claim 9, wherein   characterized in that it further comprises washing said product   of caustic attack with weak acid.   The method of claim 9, wherein   characterized in that said caustic attack product consists of caustic potash, the process further comprising a washing operation with citric acid after said caustic potash has been contacted with said outer surface of each of said elements for a given time, 12 Process according to any one of the   claims 9, 10 and 11, characterized in that each   said expansion plates are attached to a respective one of the vacuum alloy wafer elements at temperatures of the order of 650 ° C.