FR2508706A1 - SEMICONDUCTOR DEVICES FOR HIGH POWER, PASSIVE WITH GLASS - Google Patents

Abstract

A process for producing a semiconductor device comprises making incisions in a relatively large-area semiconductor body, making regions of opposite conductivity inside the region encompassed by the incision and making a second incision inside the first incision. Said second incision is coated with a glass layer in order to passivate the boundary layers which end in the second incision. The process can be used to produce any desired type of semiconductor, for example thyristors, transistors and diodes or the like.

Description

Semiconductor device for high powers
passive with glass
The present invention relates to semiconductor devices in general, and more particularly to semiconductor devices, as well as to the process for the preparation thereof, which use molten glass for the passivation of pn junctions; and a method for preparing a series of devices from a single large body of semiconductor material.

 Until now, the thyristors, transistors and diodes sealed under glass used a wall of molten glass on an edge of the body of semiconductor material to ensure the seal protecting the pn junctions formed at the interface of the zones of opposite conductivity type. . A typical example of a conventional glass seal is described in U.S. patent application 897,323, Belgian Patent No. 875,606, in U.S. patent application

891,090, and Belgian Patent No. 875,082.

 These conventional devices use a body of semiconductor material whose edges are thinned. The result is a non-symmetrical device. This non-symmetry can increase the stresses caused by temperature variations during power-up cycles.

 Another example of a conventional device encapsulated under glass is presented in the U.S. patent application.

970,045, and EPA patent application 79302905.9. This classic device uses preformed glass rings for its preparation. The use of such glass preforms requires the extensive use of mounting devices to ensure correct initial positioning of the glass pre-formation and the maintenance of this position during the melting and return to solid state of the glass. .

 Another example of a device encapsulated under glass is presented in U.S. patent application -168,818, and EPA patent application 81105364.4.

 The present application describes a method for forming a series of devices from a large body of semiconductor material as well as a device formed by this method.

 In the context of the present application, circular grooves, vertically aligned, are formed in the body of semiconductor material from the faces of the top and of the base. The grooves are separated by a part of the body. Glass paste is placed in these grooves so that it solidifies on the spot. We cut in the body the isolated area inside the circular grooves by cutting right through the body outside the circular grooves.

 Referring to Figure 1, there is shown a thyristor 10 of high power and large area manufactured according to the method of patent application EPA 81105364.4.

 This thyristor 10 is composed of a cathode emitter zone 12, a cathode base zone 14, an anode base zone 16 and an anode emitter zone 18.

 There is a p-n 20 junction between zones 12 and 14, a p-n 22 junction between zones 14 and 16 and a p-n 24 junction between zones 16 and 18.

 The grooves 26 extend in the thyristor from the upper surface 28 to a depth greater than the depth of the p-n junction 22 and the grooves 30 extend in the thyristor beyond the p-n junction 24.

 The grooves 26 and 30 respectively contain a mass of hardened glass 32 and 34 which performs the passivation of the p-n junctions 22 and 24 at the point where the junctions open into the grooves.

 The glass in the grooves has a thickness of about 13 ssm if using aluminum lead borosilicate glass, and a thickness of about 50 ssm if using zinc borosilicate glass. The difference in thickness is due to the fact that zinc borosilicate glass has a coefficient of expansion closer to that of silicon. Obviously, if we modify the coefficient of expansion of a glass of leadaluminium borosilicate or of any suitable glass so that it approaches the coefficient of expansion of silicon, by adding silica flakes for example, the wall of glass may be thicker, that is to say approach or be equal to 50 Am.

 The cathode emitter electrode 36 establishes ohmic electrical contact with the cathode emitter zone 12 and the cathode base zone 14. The floating trigger electrode 38 is in electrical contact with the cathode emitter zone 12, and the cathode base zone 14, the trigger electrode 40 being in ohmic electrical contact with the cathode base zone 14. The cathode emitter electrode 36, the floating trigger electrode 38 and the trigger electrode 40 are arranged on the upper surface 28.

 An anode emitter electrode 42 is in ohmic electrical contact with the anode emitter zone 18, on the lower surface 44.

 The part 46 of silicon placed along the outer periphery of the grooves 26 and 30 and the glass 32 and 34 passivate the thyristor.

 The EPA patent application just described has certain weak points. Firstly, creating grooves by chemical attack both from the upper and lower surface, then applying and solidifying glass in the grooves increases the number of manufacturing operations. Increasing the number of steps in any manufacturing always results in lower profitability. Then, the groove passivated by the glass on the lower surface or back of the body of semiconductor material reduces the contact surface with an electrode and increases the thermal impedance of the device.

 An object of the invention is to obtain a process comprising less manufacturing phase.

 An additional object of the invention is to provide a semiconductor device having a lower thermal impedance.

 One aspect of the invention relates to a semiconductor device comprising: a body having opposite lower and upper surfaces and a central part isolated from the peripheral part by a first circular groove extending from the upper surface in said body over a first depth less than the thickness of the body, at least part of said body comprising at least two zones of opposite conductivity type with at least one pn junction, a second circular groove extending from said upper surface of the body in said body to a second depth less than said first depth, and being disposed inside said first groove; solidified glass disposed inside said second groove sealing with the walls thereof, said part at least surrounded by said second groove and said second depth being greater than the distance between the upper surface and the pn junction .

 Another aspect of the invention relates to a process for preparing a series of passivated semiconductor devices with glass from a large body of semiconductor material having opposite upper and lower surfaces, this process consisting in forming a first groove having a first depth in a circular configuration through said upper surface of said body; forming a second groove in a circular configuration through said upper surface inside the internal diameter of said first groove and extending in said body to a second depth less than the first depth; depositing glass paste, composed of glass powder and a binder, in said second groove; removing the binder and solidifying said glass in said second groove; and cutting entirely right through said body around the outer periphery of the first groove.

For a better understanding of the present invention, we will describe it with reference to the accompanying drawings, among which
- Figure 1 is a section of a conventional thyristor passivated with glass
- - Figure 2 is a section of a silicon body during manufacture according to the method of the present invention
- Figure 3 is a plan view of a # silicon body of large dimensions during manufacture according to the method of the present invention;
- Figures 4, 5 and 6 are sections of the body of Figure 2 during manufacture according to the method of the present invention
- Figure 7 is a section of a thyristor manufactured according to the method of the present invention
- Figure 8 is a section of a silicon body during manufacture according to the method of the present invention;
- Figure 9 is a section of a thyristor manufactured according to the method of the present invention
- Figure 10 is a section of a silicon body during manufacture according to a modified process of the present invention.

 Referring to Figure 2, there is shown a body 50 of large area of semiconductor material, preferably silicon suitable for use in the manufacture according to the method of the present invention, of a semiconductor device for high powers, large area, passivated with glass, and in particular a thyristor for high powers, large area, passivated with glass.

 "Large area" here means a thyristor whose body of semiconductor material has a diameter of at least 13 mm. Devices have been fabricated on silicon wafers having diameters of at least 16 mm to at least 23 mm. Devices are provided with a diameter of 33 mm.

 "High powers" here means a thyristor capable of handling nominal voltages from at least 1000 V up to 1200 V or more.

 The large area body 50, composed of a suitable initial material, has a typical diameter of 76 mm or more, a thickness of about 300 ssm, an n-type conductivity and a resistivity of 4000 ohm / m.

 The body 50 has an upper face 52 and a lower face 54. The lower and upper faces 52 and 54, respectively, are substantially planar and parallel. A portion 56 extends at the edge between the faces 52 and 54.

 Referring to FIG. 3 in addition to FIG. 2, the upper face 52 of the body 50 is covered with a product resistant to chemical attack, such as that sold commercially under the registered name of Waycoat SC, and a series of grooves 56 is formed by etching in the upper face 52, in a circular configuration in the body 50 over a predetermined depth.

This predetermined depth is normally, for devices of this type, at least 75 ssm and usually more. In all cases, the distance "x" between the internal face 58 of the groove 56 and the lower surface 54 of the body 50 must be such that x / 2 is less than or equal to the depth of the subsequent p-type diffusion.

 The width of the groove is normally about 635 ssm at the surface 56 of the body 50. The distance Y between the grooves is about 13 mm.

 A suitable etching solution to form the throat 56 is composed, by volume, of 2 parts of nitric acid, of 1 part of hydrofluoric acid and of 1 part of acetic acid.

 After etching the grooves 56, the body 50 is cleaned by alternately using solutions of hydrogen peroxide (H202), an aqueous solution of hydrochloric acid (HCl-H20), and an aqueous solution of hydrogen peroxide and ammonia (H202-NH40H-H20>, with rinsing of the water between each successive cleaning operation.

 The aqueous hydrochloric acid solution is composed, by volume, of 2 parts of hydrochloric acid, 5 parts of water and 1 part of hydrogen peroxide.

 The aqueous solution of hydrogen peroxide and ammonia is composed, by volume, of 1 part of hydrogen peroxide, 1 part of ammonia and 5 parts of water.

 The water used for rinsing is 18 megohm water.

Referring to FIG. 4, after the chemical etching of the grooves 56 and the cleaning after the etching, conventional diffusion or epitaxial diffusion and photographic masking techniques are used to produce the structure shown in FIG. 4 in the body 6 #
Here again, only a part # of the body 60 located inside or in the immediate vicinity of the groove 56 is represented in FIG. 4.

 The part shown in Figure 4 is a thyristor 6 for high powers, ready for further processing according to the method of the invention.

 It should be understood that in practice the diffusion profile, which includes the depth of the junction and the doping concentration, is adjusted "to measure" according to the characteristics desired for the device. This diffusion profile which will be described with reference to FIG. 4 is such that the thyristor produced is capable of treating voltages from 1000 to 1200 V.

 The thyristor 60 comprises the cathode emitter area 62, the cathode base area 64, the anode base area 66 and the anode emitter area 68.

 There are p-n junctions between adjacent zones. A p-n 70 junction between zones 62 and 64, a p-n 72 junction between zones 64 and 66 and a p-n 74 junction between zones 66 and 68.

 The cathode emitter zone 62 has a thickness of 15 to 20 ssm, is of the n type of conductivity and is doped with a concentration of approximately 1020 atoms per cm.

The cathode base area 64 has a thickness of 65 to 75 ssm, is of the p type of conductivity and is doped 17 with a surface concentration of 5 × 10 atoms per cm 3
The anode base zone 66 has a thickness of 165 to 190 Am, is of the n type of conductivity and has a resistivity of 4000 to 5000 ohm / m. Zone 66 is the part not covered with the initial silicon body 50.

The anode emitter zone 68 has a thickness of 65 to 75 ssm, is of the p type of conductivity and is doped with a surface concentration of at least 5 × 10 9 atom per cm 3
If the anode emitter zone 68 is doped at a surface concentration of less than 5 × 1019 atoms per cm 3, the thyristor presents an unacceptable direct voltage drop because it is too high.

 Referring to FIG. 5, it can be seen that the surface delimited by the groove 56 can also be used to form a thyristor 80 with dynamic trigger. Components similar or identical to those in FIG. 4 have the same reference number in FIG. 5.

 The differences between the two structures of FIGS. 4 and 5 lie in that (1) the thyristor 80 with dynamic gate comprises a main zone 162 of cathode emitter and an auxiliary zone 262 of cathode emitter, these two zones having a circular configuration; (2) there is a p-n 170 junction between zone 162 and zone 64 and a p-n 270 junction between zone 262 and zone 64, and; (3) the parts 82 of the cathode base area 64 extend under the upper surface 52 of the thyristor 80.

 The anode base area 66 and the anode emitter area 68 are identical in the two devices.

 According to the preferred method for preparing thyristors for high powers and of large surface area in FIGS. 4 or 5, the zones 64 and 68 are formed by diffusion in the body 50 of FIG. 2. The zone 66 comprises the part of type n not diffused in the body 50.

 Masking of the face 52 is then carried out by conventional techniques and, in the case of the thyristor 60 of FIG. 4, the area 62 is formed by diffusion in the desired part of the face 52.

 In the case of the thyristor 80 in FIG. 5, the face 52 is masked by conventional techniques and the emitter segments 162 and 262 are formed in the desired parts of the face 52.

 In a variant and in the case of the thyristor 80 of FIG. 5, diffusion is carried out on the entire face 52 to form a continuous n-type zone of cathode emitter extending over the surface of the body 80, and we then use photo-masking techniques; the parts 82 of the area 64 are formed by diffusion through the cathode emitter area at predetermined locations.

 Referring to FIG. 6, after the thyristor 60 of FIG. 4 has been diffused, a second groove 82 is # formed by chemical attack in the thyristor 60.

 This second groove 82 is formed inside the internal diameter of the first groove 56, that is to say that the first groove 56 surrounds the second groove 82. The groove 82 is formed according to the same chemical etching process and cleaning material presented about throat 56.

 This second groove 82 extends in the silicon body to a depth such that it crosses the pn junction 72 and opens onto the zone 66, thus isolating both the directly polarized pn junction 70 and the pn junction 72 reverse polarized.

 The groove 82 has a width at the surface 52 approximately equal to the width of the groove 56, that is to say approximately 630 ssm and a width of approximately 380 ssm at the bottom 83.

 The spacing between grooves 56 and 82 is not critical. But, so that undoubtedly, no scour likely to occur during the chemical etching of the groove 82 penetrates into the groove 56 and so that the groove 82 effectively crosses the horizontal part 85 of the pn junction 72 rather than the vertical part 87, a spacing "Z" in Figure 6 of about 760 am has been found to be satisfactory.

 A suitable glass powder, the particles of which have a nominal size of approximately 250 μm, is then mixed with a suitable vehicle to form a paste which is printed in the groove 82 by means of a screen printing press.

 The glass to be used according to the process of the invention must first of all have a coefficient of expansion close to that of silicon, for example in the range of 4.0 to 6.0 10 -6 cm per cm per degree C , and be essentially free of alkaline ions.

Furthermore :
1) this glass must have a stable structure, that is to say that it must not devitrify or separate in phases during the melting operation.

 2) this glass must have good chemical resistance to the environment and humidity.

 3) this glass must wet the semiconductor material, normally silicon in this case, and adhere to it.

 4) this glass must not chemically attack the surfaces of the semiconductor material, normally silicon, in a harmful way.

 5) the thermal characteristics of this glass must be such that the voltages can disappear at temperatures lying within the limits of the device or of the semiconductor material, once again normally of silicon.

 6) this glass must have a melting temperature below the degradation temperature of the device.

 7) the finished device must have resilience to thermal shock and thermal cycles and must have good mechanical strength.

In general, glasses of lead borosilicate and aluminum have been found to be satisfactory. In particular glasses having a general chemical composition, by weight of,
Constituents Percentages (%)
Si02 30-40
B203 12-23
PbO 40-48
At 203 2-6 proved to be adequate.

A particularly suitable glass is the glass sold commercially by Innotech under the reference IP745, which has a specific composition, by weight, of
Constituents Percentages (%)
SiO2 36% + 4%
B203 15% + 3%
PbO 45% + 3%
Au 203 3% + 1%
Another particularly satisfactory glass is sold by Innotech under the reference IP740, and has a nominal composition, by weight, of
Constituents Percentages (%)
Si02 40%
B203 8.2%
Pb02 49.3%
Al2O3 2.5%
The lead borosilicate glasses are also satisfactory, these glasses have a nominal composition, by weight, of
Constituents Percentages (%)
If 2 30-40
13203 12-23
PbO 40-48
The zinc and aluminum silicate glasses are also satisfactory, these glasses have a nominal composition, by weight, of
Constituents Percentages (%)
ZnO 40-50
Al2O3 2-6
Si02 50-60
Another particularly satisfactory glass is a zinc borosilicate glass, in particular that sold by JENAER GLASWERK SCHOTT & GEN., Under the reference G027 002, which has a nominal composition, by weight, of
Constituents Percentages (%)
ZnO 40-50
13203 1-5
SiO2 50-60 and which can contain, by weight, about 15% of SiO2 in the form of silica particles.

 The vehicle in which the glass is mixed to form a paste can be a liquid or a combination of liquids capable of supporting the particles of glass powder in suspension to form a paste, without having an adverse effect on these glass particles. In addition, this vehicle must be easily removed from the pulp by heating.

An example of a suitable vehicle is a mixture of ethylcellulose and butylcarbitol. Another satisfactory vehicle is sold commercially by Electro-Science
Laboratory under vehicle designation No. 400.

 The preferred vehicle for use with the zinc borosilicate glass is composed of 5 grams of ethylcellulose and 150 cm3 of butylcarbitol.

 The preferred paste to be used according to the method of the invention is composed of 40 grams of glass powder G027-002 whose particles have a nominal size of 10 ssm and 35 cm3 of vehicle formed from ethylcellulose and butylcarbitol.

 The dough is printed in the groove 82 by means of a press provided with a 0.092 mm mesh screen. Printing continues until the dough fills the throat 82.

 The dough is left to stand for about five to fifteen minutes, preferably about ten minutes, to allow it to flow and settle in all parts of the throat.

 This structure is then heated for about eight to twelve minutes at a temperature in the range of 100 to 1500C to remove excess vehicle paste.

This operation is normally carried out by heating with a heating lamp.

 The structure is then placed in a quartz support and then heated in an oven at a temperature in the range of 450 to 5500C for a period of 20 to 45 minutes; preferably 5000C for 30 minutes. The purpose of this operation is to burn or remove from the glass in the throat the entire excess vehicle. So you can change the temperature and time to complete this task depending on the vehicle used.

 After the removal operation and without cooling, the structure is heated to a temperature in the range of 650 to 7500C, preferably 7200C, for 5 to 45 minutes, preferably about 10 minutes, to fully solidify and set the glass. on silicon.

 If preferred, the removal, solidification and setting operation can be carried out in the same batch, the temperature being increased from the preferred value of 5000C to the preferred value of 7200C over a period of time. about 10 to 20 minutes.

 After heating, preferably at 7200C, for 10 minutes preferably, the oven is cooled from the preferred value of 7200C to a temperature in the range of 525 to 5000C in about 15 minutes. The oven temperature is maintained in this range for about 10 minutes, then the temperature is reduced to 4800C in about 15 minutes. The temperature of approximately 4800C is maintained for approximately 20 minutes and then the temperature is reduced to approximately 4100C in approximately 15 minutes. This temperature is maintained for approximately 30 minutes and then the oven temperature is reduced to room temperature at a speed of approximately 100C per minute.

 This cooling or annealing cycle releases harmful tensions in the glass.

 The hardened and treated glass is shown in Figure 6 and is referenced 84.

 Glass 84 is then covered with a layer 86 of a suitable photoresist using conventional photolithography techniques.

 Either a negative type photoresist or a positive type photoresist can be used. A negative photoresist is preferable.

 Examples of suitable negative photoresists are those sold commercially such as Hunts waycoat SC and the photoresists from Eastman Kodak designated by KTFR and KMER.

 Examples of suitable positive photoresists are commercially available from SHIPLEY under the designation 1350 and 1350H.

 After the application of the photoresist layer 86 on the glass 84, the series of thyristors, represented by the thyristor 60, is cut from the body 50 of silicon with a laser tip.

 The role of the photoresist is to protect the glass against the particles of molten silicon generated by laser cutting.

The laser point uses an Nd: Yag laser, these points are commercially available. A satisfactory laser tip is sold commercially by Quantronix
Corp. under model designation 604.

 The thyristors 60 are cut from the body 50 along a line 88 located about 0.5 to 1 mm from the external periphery 90 of the first circular groove 56. In practice, cutting is normally carried out at a distance of about 1.59 mm from the inner periphery 92 of the groove 56.

This distance between the. internal 92 or external 90 periphery of the groove 56 and the cutting line 88 is not critical.

 Referring to FIG. 7, the electrical contacts or the electrodes 90, 94 and 96 comprising the anode, trigger and cathode electrodes are fixed, as will be described below, to complete the thyristor.

 Referring to FIG. 8, there is seen the thyristor 80 with dynamic trigger of FIG. 5, in which, according to the method of the invention, the second groove 82 has been formed, filled with the hardened and treated glass 84 and this glass 84 was covered with a layer 86 of photoresist.

 All the operations mentioned above, that is to say the formation of the groove 82, the filling of this groove with the glass 84, the hardening and the treatment of the glass and the covering of this glass with a layer 86 of photoresist are carried out according to the methods described above.

 The thyristor is then cut from the large silicon body along the line 88 using a laser as already mentioned above.

 After laser cutting, cathode, anode and trigger electrodes are attached to the different areas.

 These electrodes are preferably bimetallic, and are composed of a first layer of titanium (Ti) about 1500 A thick, and a second layer of silver (Ag) about 20D00 A thick.

 The metal electrodes can be deposited by spraying or spraying.

 The metallization or fixing of the electrodes is carried out using, preferably, a shadow mask to delimit the cathode emitter, the trigger and the amplification trigger on one face and the anode emitter on the opposite face.

 After fixing the electrodes, the photoresist 52 is burned to remove it from the glass in an air medium at 400 C.

 Referring to Figure 9, we see that there is shown a thyristor 80 finished for high powers and large area with dynamic trigger produced according to the method of the invention.

 This dynamic trigger thyristor 80 has a cathode emitter area 162, an auxiliary emitter area 262, a cathode base area 64, an anode base area 66 and an anode emitter area 68 .

 There is a junction p-n 170 between zones 162 and 64; a p-n 270 junction between zones 262 and 64 a p-n 72 junction between zones 64 and 66 and a p-n 74 junction between zones 66 and 68.

 The first groove 56 extends under the upper surface 52 in the thyristor at a first predetermined depth "x" and the second groove 82, surrounded by the first groove 56, extends under the upper surface in the thyristor at a second depth predetermined. The second predetermined distance is greater than the distance between the upper face 52 and the p-n junction 72.

 The second groove 82 contains a mass of hardened glass 84.

 This solidified and treated glass in the grooves may have a thickness of about 13 ssm if using borosilicate glass of lead and aluminum and a thickness of about 50 ssm if using zinc borosilicate glass. The difference in thickness is due to the fact that the zinc borosilicate glass has a coefficient of expansion closer to that of silicon. Obviously, if we modify the coefficient of expansion of lead and aluminum borosilicate glass or any other suitable glass so that it approximates the coefficient of expansion of silicon, for example by adding silica flakes, the glass wall may be thicker, that is to say approach or be equal to 50 ssm.

 There is a cathode emitter electrode 90, an auxiliary emitter electrode 92, a trigger contact 94 and an anode emitter contact 96 established as described above.

 The cathode emitter electrode 90 establishes ohmic electrical contact with zones 162 and 64. The auxiliary transmitter electrode 92 establishes ohmic electrical contact with zones 262 and 64. Trigger electrode 94 establishes ohmic electrical contact with the zone 64 and the electrode 96 of anode emitter establishes the ohmic electrical contact with the zone 68.

 The thyristors produced according to the process of the invention can be encapsulated in resin or placed in shells according to any conventional technique.

Thyristors produced according to the process of the invention and encapsulated in silicone resins, such as that sold commercially under the designation GE SR112
Silicone Resin, have been shown to be stable over S00 hours.

 For some tension designs, it may be impossible to engrave a deep groove only from the top side, as described above.

 In this case, the first groove is etched in the silicon body starting from both the upper and lower faces.

 Referring to FIG. 10, starting again from a body 50 of large area made of semiconductor material, such as for example a body 76 mm in diameter of n-type silicon, the groove 56 is etched by chemical attack in the upper surface 52 of the body 50 and the groove 156 in the lower surface 54 of the body 50.

 The grooves 56 and 156 are engraved as described above.

 The distance "x" between the grooves 56 and 156 is such that x / 2 is less than or equal to the following p-type scattering.

 By again following the process presented above, p and n type zones are formed in the body by diffusion or epitaxial diffusion techniques.

 After the diffusion or epitaxial diffusion operations, the groove 82 is formed as seen above and the operations of passivation by the glass, establishment of contacts and laser cutting of the body of large dimensions are carried out as described above to obtain a thyristor.

 Although the present invention has been described with reference to the thyristors in particular, it is clear that the invention is also applicable to diodes and transistors.

Claims (17)

 1.- semiconductor device characterized in that it comprises: a body (50) having opposite upper (52) and lower (54) surfaces and a central part isolated from the peripheral part by a first groove (56 ) circular extending from the upper surface in said body to a first depth less than the thickness of the body, at least part of said body comprising at least two zones of opposite conductivity type with at least one pn junction, a second circular groove (82) extending from said upper surface (52) of the body in said body (50) to a second depth less than said first depth, and being disposed inside said first groove (56 ) solidified glass (84) disposed inside said second groove (82) sealing with the walls thereof; said at least part being surrounded by said second groove; and said second depth being greater than the distance between the upper face (52) and the p-n junction.  2.- Device according to claim 1, characterized in that the glass (84) in the grooves is a borosilicate glass of lead and aluminum.  3.- Device according to claim 1, characterized in that the glass (84) in the grooves is a glass of zinc borosilicate.  4. Device according to any one of claims 1, 2 or 3, characterized in that the central part of the body (50) has four zones, adjacent zones being of opposite conductivity type with p-n junctions between them.  5.- Process for preparing a series of semiconductor devices passivated with glass from a body (50) of large surface area of semiconductor material having opposite upper (52) and lower (54) faces, characterized by the fact that it consists  - To form a first groove (56) having a first depth in a circular configuration through said upper face (52) of said body (50), to form a second groove (&) in a circular configuration through said upper face (52 ) inside the internal diameter of said first groove (56) and in said body (50) over a second depth less than said depth  - depositing glass paste (84), composed of glass powder and a vehicle, in said second groove (82);  - eliminating said vehicle and solidifying said glass (84) in said second groove (82); and  - To cut entirely right through said body (50) around the outer periphery of the first circular groove (56).  6.- method according to claim 5, characterized in that it consists: in forming by diffusion, following the forming of said first groove, at least a second zone inside said body, this second zone being of a conductivity type opposite to the conductivity type of said body.  7.- Method according to claims 5 or 6, characterized in that said glass paste is composed in part of a glass selected from the group of borosilicate glasses of lead and aluminum and zinc borosilicate glasses.  8.- Method according to claims 5 or 6, characterized in that said glass paste is composed in part of a glass of zinc borosilicate.  9.- Method according to any one of claims 5 to 8, characterized in that the glass paste is composed in part of a vehicle consisting of ethylcellulose and butylcarbitol.  10.- Method according to any one of claims 5 to 9, characterized in that the glass paste is composed of 40 g of a glass of zinc borosilicate and 35 cm3 of a vehicle composed of ethylcellulose and butylcarbitol.  11.- Method according to any one of claims 5 to 10, characterized in that the glass (84) is deposited in the grooves by printing on the screen.  12.- Method according to any one of claims 5 to 11, characterized in that the glass is left to settle in the grooves for about 5 to 15 minutes before eliminating the vehicle.  13.- Method according to claim 11, characterized in that the glass is left to settle in the grooves for 10 minutes before eliminating the vehicle.  14.- Method according to any one of claims 9, 10, 11, 12 and 13, characterized in that the vehicle is eliminated by heating for a period of 8 to 12 minutes at a temperature of 100 to 1500C.  15.- Method according to claim 14, characterized in that the glass (84) is hardened by heating it for a period of 20 to 45 minutes at a temperature of 4500 to 5500C, then it is heated for a period of 5 45 minutes at a temperature of 6500 to 7500C.  16.- Method according to claim 14, characterized in that the glass is hardened by heating it for 30 minutes at 5000C and then for 10 minutes at 7200C.  17.- Method according to any one of claims 5 to 16, characterized in that a laser tip is used to cut right through said body (50) of semiconductor material.