WO2025026895A1 - Detachable semiconductor substrate made of polycrystalline silicon carbide - Google Patents

Abstract

The present disclosure relates to an intermediate substrate (10) for the manufacture of a semiconductor substrate, the intermediate substrate successively comprising: a a first semiconductor layer (2); b a first thermal barrier layer (5); c a support (13) comprising an absorption layer (3) configured to absorb laser radiation in a given wavelength range, the temperature of the absorption layer (3) increasing as it absorbs the laser radiation, and a separation zone (8) adjacent to the absorption layer (3) configured to thermally degrade due to the increase in temperature of the absorption layer, so as to separate at least part of the support (13) from the rest of the intermediate substrate (10).

Description

DESCRIPTION

Detachable polycrystalline silicon carbide semiconductor substrate

TECHNICAL AREA

The present application relates to the manufacture of semiconductor substrates, and more particularly to the manufacture of polycrystalline silicon carbide support layers for their use in high performance substrates.

STATE OF THE ART

In the field of power electronics, it is known to use wideband semiconductor materials. These materials have a wider band gap than semiconductor materials such as silicon, which gives them electrical insulation properties between those of semiconductors and insulating materials. In particular, wideband semiconductors have the advantage of tolerating temperatures higher than those that conventional semiconductors are capable of withstanding. In addition, these materials have an increased power density compared to conventional semiconductors, allowing volume and mass gains in the electronic systems comprising them.

A frequently used broadband semiconductor material is silicon carbide (SiC). For the production of power electronic components, and in particular metal-oxide-semiconductor field-effect transistors (or MOSFETs), it is necessary to have SiC substrates with a certain thickness, generally of the order of 300 micrometers, giving them a mechanical resistance that allows the performance of front-end processes, i.e. the formation of electronic functions on the semiconductor substrate. The semiconductor substrates thus obtained are then placed on a metal support, in particular made of copper, and which has a Young's modulus and a thermal expansion coefficient different from those of the semiconductor substrate. Mechanical stresses can therefore be generated in the semiconductor substrate during thermal cycles to which it is subjected on the metal support. One way to overcome this problem is to reduce the thickness of the SiC layer, which is possible only after the front-end processes have been performed.

For this purpose, a SiC substrate of a given thickness, close to 300 micrometers, can be formed before mechanically etching a part of it in order to reduce its thickness, and therefore to reduce the mechanical constraints imposed on the metal support or on any welds between it and the SiC substrate during use and cycling. thermal resistance of the electronic component. In addition, such a reduction in the thickness of the SiC substrate makes it possible to reduce the ON resistance and thermal resistance thereof, enabling better electrical performance, and makes it possible to bring the Young's modulus and the thermal expansion coefficient of the SiC substrate closer to those of the metal support.

However, mechanical etching is relatively expensive and difficult to implement due to the hardness of SiC, and the remaining part of the substrate may have imperfect flatness. It is therefore necessary to establish processes that allow obtaining a semiconductor substrate of low thickness and having regular flatness, while reducing the costs and time required to implement such processes.

EXPOSED

One aim sought is to remedy the aforementioned drawbacks.

For this purpose, according to a first aspect, an intermediate substrate is proposed for manufacturing a semiconductor substrate, successively comprising: a. a first semiconductor layer, b. a first layer forming a thermal barrier, c. a support comprising an absorption layer configured to absorb laser radiation in a determined wavelength range, the temperature of the absorption layer increasing during absorption, and a separation zone adjacent to the absorption layer and configured to thermally degrade under the effect of the increase in temperature of the absorption layer, so as to separate at least part of the support from the rest of the intermediate substrate.

Thus, the proposed substrate allows the separation, after completion of the front-end processes, of the semiconductor substrate into two distinct parts without mechanical etching, so as to retain only the desired thickness of the semiconductor layer before its integration into the metal support without compromising the flatness of the semiconductor layer. The use of a laser to divide the semiconductor substrate into two parts, and thus isolate the desired thickness of this substrate, allows it to be obtained more quickly and at a lower cost than by mechanical etching. The use of a thermal barrier layer makes it possible to limit the propagation of heat in the rest of the substrate and therefore promotes separation with reduced power and/or laser exposure time. According to one embodiment, the support comprises: a. a separation assembly comprising: i. the absorption layer, and ii. a separation layer adjacent to the absorption layer and comprising the separation zone, the degradation of the separation zone occurring when the absorption layer reaches a threshold temperature, b. a second thermal barrier layer c. a support layer, the second thermal barrier layer being located between the separation assembly and the support layer.

According to one embodiment, the support comprises: a. the absorption layer, and b. a support layer further forming a second thermal barrier, the separation zone being included in the support layer.

According to one embodiment, the substrate further comprises a seed layer suitable for growing the first semiconductor layer, the seed layer preferably comprising graphite, the first semiconductor layer being interposed between the seed layer and the first thermal barrier layer.

According to one embodiment, the separation layer is made of silicon nitride.

According to one embodiment, the absorption layer is made of a material chosen from polycrystalline silicon carbide of the p-SiC type, titanium nitride or zirconium.

According to one embodiment, the substrate further comprises a monocrystalline semiconductor layer, preferably comprising silicon carbide or gallium nitride, a first face of the monocrystalline semiconductor layer being adjacent to the first semiconductor layer.

According to one embodiment, the first semiconductor layer is made of a broadband semiconductor material, in particular a material chosen from silicon carbide, aluminum nitride and gallium nitride. According to one embodiment, the support layer is a second semiconductor layer of lower quality than the first semiconductor layer, preferably made of a material chosen from silicon carbide and silicon nitride.

According to one embodiment, the support layer has a thickness of between 100 and 200 nanometers.

According to one embodiment, the first and/or second thermal barrier layer has a thermal conductivity of less than 25 W/mK, the second thermal barrier layer preferably being made of titanium dioxide or silicon nitride.

According to one embodiment, the substrate further comprises a monocrystalline semiconductor layer disposed on a surface region of the first semiconductor layer, the first semiconductor layer being located between the first thermal barrier layer and the monocrystalline semiconductor layer.

Another aspect relates to a method for manufacturing a semiconductor intermediate substrate, successively comprising steps of: a. growing a first electrically semiconductor layer on a seed layer, b. growing, on the first semiconductor layer, a first thermal barrier layer, c. growing, on the first thermal barrier layer, a support comprising an absorption layer configured to absorb laser radiation in a determined wavelength range, the temperature of the absorption layer increasing during absorption, the support further comprising a separation zone adjacent to the absorption layer and configured to thermally degrade under the effect of the increase in temperature of the absorption layer, so as to separate at least part of the support from the rest of the intermediate substrate, d. removing the seed layer, the growth steps being obtained in particular by gas phase deposition on the previously formed layers. According to one implementation of the method, the growth of the support comprises successive steps of: a. growth of a separation assembly consisting of the absorption layer and a separation layer, the growth of the separation assembly comprising: the growth of the absorption layer the growth of the separation layer, the separation layer comprising the separation zone, the separation zone being adjacent to the absorption layer, b. growth, on the separation assembly, of a second layer forming a thermal barrier: c. growth, on the second layer forming a thermal barrier, of a support layer, the growth steps being obtained in particular by gas phase deposition on the previously formed layers.

According to one implementation of the method, the growth of the support comprising successive steps of: a. growth, on the first layer forming a thermal barrier, of the absorption layer b. growth, on the absorption layer, of a support layer also acting as a second thermal barrier, the separation zone being included in the support layer, the growth steps being obtained in particular by gas phase deposition on the previously formed layers.

Another aspect relates to a method of manufacturing a substrate comprising a monocrystalline semiconductor layer on a polycrystalline semiconductor substrate, comprising implementing the method of manufacturing an intermediate semiconductor substrate as defined above, the first semiconductor layer being polycrystalline, and further comprising successive steps of: a. forming a weakening zone in a semiconductor donor substrate by implantation of species, so as to delimit a monocrystalline semiconductor layer to be transferred, b. bonding the monocrystalline semiconductor layer to be transferred to a surface region of the first semiconductor layer, c. detaching the donor substrate along the weakening zone to transfer the monocrystalline semiconductor layer to the first semiconductor layer.

Another aspect relates to a method of manufacturing an electronic component, comprising successive steps of: a. Implementing the method of manufacturing a substrate as defined above, b. Carrying out front-end processes in the monocrystalline semiconductor layer to form said electronic component.

According to one implementation, the method comprises, after carrying out said frontal processes, a step of applying laser radiation in the determined wavelength range to the intermediate substrate, so as to thermally degrade the separation zone and to separate at least part of the support from the rest of the intermediate substrate.

According to one implementation, the method comprises, after the application of the laser radiation, a step of removing residual layers located on a face of the first semiconductor layer opposite the monocrystalline semiconductor layer, the residual layers resulting from the step of applying the laser radiation.

Another aspect relates to an intermediate substrate for the manufacture of a semiconductor substrate, successively comprising:

A first semiconductor layer made of polycrystalline silicon carbide (pSiC),

A first layer forming a thermal barrier, made of titanium dioxide (TiO ₂ ),

An absorption layer, made of 3C-type polycrystalline silicon carbide (3C-pSiC),

A separation layer, made of silicon nitride (Sisl^ ),

A second layer forming a thermal barrier, made of titanium dioxide (TiO ₂ ), A support layer, consisting of polycrystalline silicon carbide type 4H (4H-pSiC)

Another aspect relates to an intermediate substrate for the manufacture of a semiconductor substrate, successively comprising:

A first semiconductor layer made of polycrystalline silicon carbide (pSiC),

A first layer forming a thermal barrier, made of titanium dioxide (TiO ₂ ),

An absorption layer, made of titanium nitride (TiN),

A separation layer, made of silicon nitride (Sisl^ ),

A second layer forming a thermal barrier, made of titanium dioxide (TiO ₂ ),

A support layer, made of polycrystalline silicon carbide type 4H (4H-pSiC).

DESCRIPTION OF FIGURES

Other features, purposes and advantages will emerge from the following description, which is purely illustrative and not limiting, and which must be read in conjunction with the drawings.

[Fig. 1], [Fig. 2], [Fig. 3] and [Fig. 4] schematically illustrate intermediate substrates for the manufacture of a semiconductor substrate, according to different embodiments of a first aspect;

[Fig. 5], [Fig. 6], [Fig. 7] illustrate methods of manufacturing an intermediate substrate for subsequent manufacturing of a semiconductor substrate, according to different embodiments of a second aspect,

Figure 8 illustrates a method of manufacturing a substrate comprising a monocrystalline semiconductor layer on a polycrystalline semiconductor substrate, according to a third aspect.

Figure 9 illustrates a method of manufacturing an electronic component, according to a fourth aspect. [Fig. 10], [Fig. 11], [Fig. 12] represent results of a simulation of the temperature evolution of an intermediate substrate during the application of laser radiation.

In all figures, similar elements bear identical references.

DETAILED DESCRIPTION OF EMBODIMENTS

According to a first aspect, an intermediate substrate 10 is shown in FIG. 1. It comprises an arrangement of layers, which can be formed successively from a seed layer 1 of graphite. The formation of the different layers of the intermediate substrate 10 can involve the successive injection of gases which make it possible to produce deposits by condensation.

The first layer formed is a first semiconductor layer 2 called “high quality”, which is configured to support a layer from which components will be formed, in particular with a view to manufacturing power electronic components. The first semiconductor layer 2 is intended to remain in the final electronic component. The first semiconductor layer 2 may be a layer of polycrystalline silicon carbide, in particular of type 4H or 3C (also called p-pSiC). Alternatively, and depending on the applications, it may be made of monocrystalline silicon carbide of type 4H. The first semiconductor layer 2 may also be made of another broadband semiconductor material, such as aluminum nitride (AIN) or gallium nitride (GaN).

In some embodiments, the first semiconductor layer 2 is further configured to conduct an electric current. In particular, the first semiconductor layer 2 is doped.

When the first semiconductor layer 2 is made of silicon carbide, it can be highly doped with nitrogen (N++ doping). It is also possible to envisage N-type doping with phosphorus or P-type doping with gallium or aluminium. This doping makes it possible to give the first semiconductor layer 2 a very low electrical resistivity, as well as a high thermal conductivity, close to that of bulk silicon carbide. When the first semiconductor layer 2 is, on the other hand, formed of other materials, other forms of doping are conceivable: for example, for a first semiconductor layer 2 made of gallium nitride (GaN), silicon or magnesium doping can be used. In order to minimise the electrical resistance of this first semiconductor layer 2, it is desirable for it to have a thickness of between 10 and 300 pm, preferably less than 100 pm. However, it is necessary for the intermediate semiconductor substrate to have sufficient mechanical strength to support the front-end processes that will be applied to it. For this purpose, the intermediate substrate 10 comprises a support 13 whose thickness is configured to give the substrate 10 a given mechanical strength, for example between approximately 100 and 400 pm.

According to possible variants, the first semiconductor layer 2 is also likely to be undoped, or even to be electrically insulating (for example, in the case of a silicon carbide layer, by vanadium doping).

The support 13 comprises an absorption layer 3 and a separation zone 8 adjacent thereto. The absorption layer 3 is configured to absorb laser radiation in a determined wavelength range, so that its temperature increases.

The wavelength range for the laser radiation is chosen so that the seed layer 1 and the first thermal barrier layer 5 (described below) are substantially transparent to this radiation, in order to ensure that a sufficient portion of the radiation reaches the absorption layer 3, and in order to avoid damage to these layers by the radiation.

Under the effect of the temperature increase caused by the absorption of the laser radiation by the absorption layer 3, the separation zone 8 degrades, thus allowing the separation of the intermediate substrate 10 into two parts. It is thus possible to manufacture the intermediate substrate and then carry out the front processes from the semiconductor layer 2, the total thickness of the intermediate substrate 10 giving it sufficient mechanical strength to not be damaged by these processes, and finally apply a laser in the determined wavelength range so as to separate a thin part of the substrate which comprises the first semiconductor layer 2 from the rest of the substrate 10, without resorting to mechanical polishing or grinding which could damage the first semiconductor layer 2 and which would be longer and more expensive to implement.

The absorption layer 3 may be made of a material selected from polycrystalline silicon carbide of the p-SiC type, titanium nitride (TiN) or zirconium (Zr). When it is made of p-SiC, the absorption layer 3 may be configured to absorb laser radiation whose wavelength is between 380 and 410 nanometers. Titanium nitride has the advantage of being able to absorb a wider range of radiation wavelengths, such that when the absorption layer is made of this material, it can be configured to absorb laser radiation whose wavelength is between 380 nanometers and 1.7 micrometers. Silicon carbide has the advantage of being a material that can be used for the manufacture of the first semiconductor layer 2, and therefore not to introduce any new chemical element during the manufacture of the intermediate substrate 10.

The intermediate substrate further comprises, interposed between the first semiconductor layer 2 and the support 13, a first thermal barrier layer 5. This layer is configured to form a barrier to thermal conduction between the absorption layer 3 and the first semiconductor layer 2, so as to limit as much as possible an increase in temperature of the first semiconductor layer. Indeed, the first thermal barrier layer 5 is configured to have a lower thermal conductivity than that of the first semiconductor layer 2, and the first semiconductor layer 2 would therefore undergo an increase in its temperature in the absence of the first thermal barrier layer 5. Despite this, the first semiconductor layer 2 must have a low absorption coefficient over the wavelength range intended for the laser radiation, for example of a wavelength between 380 and 410 nanometers, so that it does not absorb the radiation intended to heat the absorption layer 3.

According to one embodiment, illustrated in FIG. 2, the support 13 comprises a separation assembly 12 comprising, on the one hand, the absorption layer 3, and on the other hand a so-called sacrificial separation layer 4 adjacent to the absorption layer and comprising the separation zone 8. The separation layer 4 is configured so that the degradation of the separation zone 8 takes place when the absorption layer 3 reaches a threshold temperature, so as to be able to precisely control the separation of the intermediate substrate 10. The separation assembly 12 is arranged between the first layer 5 forming a thermal barrier and a second layer 6 forming a thermal barrier. Finally, the second thermal barrier layer 6 is adjacent, on its side opposite the separation assembly, to a support layer 7. The two thermal barriers 5, 6 make it possible to confine the temperature rise to the separation assembly so that only the separation assembly undergoes a significant temperature increase, allowing the separation of the substrate into two parts along the separation zone 8 without degradation of the rest of the substrate 10.

When the absorption coefficient of the absorption layer 3 and the separation layer 4 at the wavelengths intended for the laser radiation permit it, the absorption layer 3 may be arranged, within the separation assembly 12, closer to the first thermal barrier layer 5 - as shown in FIG. 2 - or, alternatively, the separation layer 4 may be arranged closer to the first thermal barrier layer 5. In other words, the absorption coefficients of the absorption layer 3 and the separation layer 4 must allow heating of the absorption layer 3 and degradation of separation zone 8 of the separation layer

4 according to the arrangement chosen for these two layers 3, 4 in the separation assembly 12.

The wavelength range for the laser radiation is chosen so that the second thermal barrier layer 6 and the support layer 7 are substantially transparent to this radiation, in order to avoid damage to these layers by the radiation.

The separation layer 4 is advantageously very thin, for example less than 100 micrometers thick, so as not to weaken the intermediate substrate before separation. Providing a thin separation layer 4 also makes it possible to limit the manufacturing cost of this layer. It is not necessary to provide a thick separation layer 4 because the latter does not have the function of contributing to the mechanical strength of the substrate. It can be made of silicon nitride (of formula SisN^.

The thermal barrier layers 5, 6 may have a thermal conductivity of less than 25 W/mK, preferably less than 10 W/mK. They may in particular be made of titanium dioxide (TiCh), or silicon nitride (SisN^.

The main function of the support layer 7 is to increase the thickness of the intermediate substrate 10 so as to give it adequate mechanical strength for carrying out the front-end processes. In particular, the semiconductor properties of this layer are not important. It is therefore advantageous to minimize the cost of this layer as much as possible. The support layer 7 is therefore preferably of lower quality than that of the first semiconductor layer 2: the thermal resistivity and the electrical resistivity of the support layer 7 are, in particular, higher than those of the first semiconductor layer 2. For example, the first semiconductor layer 2 has an electrical resistivity of less than 5 mΩ/cm while the support layer 7 has an electrical resistivity of greater than 5 mΩ/cm.

The support layer 7 may be made of polycrystalline silicon carbide of the 4H-SiC type, or of silicon nitride (SisN^. It may have a thickness of between 100 and 200 nanometers. Furthermore, and like the first semiconductor layer 2, it is advantageous for the support layer 7 to have a low absorption coefficient over the wavelength range intended for the laser radiation, so that it does not absorb the radiation intended to heat the absorption layer 3.

Another embodiment is illustrated in Figure 3. The intermediate substrate 10 according to this embodiment does not comprise a second thermal barrier 6. In this case, the support layer 7 is made of a material having a low absorption coefficient. at the wavelengths intended for the laser radiation (i.e. transparent to the laser wavelength used), as well as low thermal conductivity. It may for example be silicon nitride (Sisl^ ). The presence of a second layer forming a thermal barrier 6 is then not necessary, since the support layer 7 is not at risk of being damaged by the radiation. In addition, silicon nitride has a coefficient of thermal expansion substantially close to that of polycrystalline silicon carbide, so that no additional mechanical stresses are introduced, compared with the embodiments previously described. This embodiment has the advantage of being compatible with the manufacturing process of layer 2 (silicon and nitrogen in the deposition reactor) and of simplifying the stacking of layers compared with the embodiments previously described.

According to one embodiment, illustrated in FIG. 4, the intermediate substrate 10 comprises a monocrystalline semiconductor layer 14, a first face of which is adjacent to the first semiconductor layer 2 on its side opposite the first thermal barrier layer 5. The monocrystalline semiconductor layer may comprise silicon carbide or gallium nitride (GaN).

A second aspect relates to a method for manufacturing a semiconductor intermediate substrate 10 as described above. The method comprises several layer growth phases, preferably implemented by successive gas depositions on the previously formed layers. Other deposition methods known to those skilled in the art, however, fall within the scope of the present disclosure: for example, liquid phase epitaxy, molecular beam epitaxy or cathode sputtering. Advantageously, all the successive layers can be deposited in the same enclosure and using the same deposition method.

With reference to FIG. 5, the first step 101 consists in growing, on a seed support 1, a first high-quality semiconductor layer 2. The method then comprises the growth 102 on this first semiconductor layer 2 of a first thermal barrier layer 5, then the growth 103 of a support 13 on the first thermal barrier layer 5. Finally, once these three growth steps have been completed, the method comprises the removal 104 of the seed layer, in particular by mechanical grinding or polishing. The support 13 comprises an absorption layer 3 and a separation zone 8 adjacent thereto. As described for the intermediate substrate 10 according to the first aspect, the absorption layer 3 is configured to absorb light radiation over a given wavelength range, the temperature of the absorption layer 3 then increasing by radiation, and the separation zone 8 is configured to become fragile and dissociate. under the effect of heating, and thus allow the separation of at least part of the support

13 of the remainder of the intermediate substrate 10.

According to an implementation of the method, shown in FIG. 6, the growth 103 of the support 13 is divided into a plurality of successive sub-steps. A first sub-step consists in growing a separation assembly 12 comprising the absorption layer 3 as well as a separate adjacent separation layer 4, the separation layer 4 comprising the separation zone 8, the separation layer 4 being configured so that the separation zone 8 degrades when the absorption layer 3 reaches a threshold temperature. This first sub-step comprises the growth 1031 of the absorption layer 3, then the growth 1032 of the separation layer 4. A second sub-step 1033 comprises the growth 1033, on the separation assembly 12 thus formed, of a second thermal barrier layer 6, thus making it possible to contain the increase in temperature by irradiation between the two thermal barrier layers 5, 6, i.e. at the level of the separation assembly 12, and therefore without compromising the quality of the first semiconductor layer 2. Finally, the growth step 103 of the support 13 comprises a third sub-step 1034 of growing a support layer 7 configured to give the intermediate substrate 10 a thickness and mechanical strength suitable for carrying out front-end processes.

According to an alternative implementation to that described in the preceding paragraph, and illustrated by FIG. 7, the growth 103 of the support 13 comprises a first growth step 1031 of the absorption layer 3 on the first thermal barrier layer 5, then a second growth step 1035 of a support layer 7 which comprises the separation zone 8. In this case, the support layer 7 is made of a material having a low thermal conductivity, and which is transparent to the wavelengths intended for the light radiation applied to the intermediate substrate 10 in order to separate the substrate 10 along the separation zone 8. The support layer 7 is of lower quality than the first semiconductor layer 2. For example, the support layer 7 was deposited with a growth speed greater than that of the first semiconductor layer 2.

A third aspect relates to a method for manufacturing a high-performance substrate. This method, illustrated in FIG. 8 , comprises a first step of implementing the method for manufacturing an intermediate substrate 10 according to the second aspect. Then, the method comprises the formation 109 of a weakening zone in a semiconductor donor substrate 9 by implantation of species through a face of the donor substrate 9 so as to separate the donor substrate into two parts, one part defining a monocrystalline semiconductor layer 14. This is followed by a step 110 of bonding the donor substrate 9, at the level of the monocrystalline semiconductor layer 14, on a surface region of the first semiconductor layer 2 and a detachment step 111 of the donor substrate along the weakening zone. A semiconductor substrate is then obtained, comprising a monocrystalline semiconductor layer 14 arranged on a semiconductor layer 2, which can itself be monocrystalline or polycrystalline depending on the applications.

A fourth aspect relates to a method for manufacturing an electronic component, as shown in FIG. 9. This method comprises a first step of implementing the method for manufacturing a semiconductor substrate according to the third aspect, as described in the preceding paragraph. Then, the method comprises a step 112 of performing front-end processes in the first layer in order to form the electronic component. Front-end processes, also referred to by the English term “front-end” processes, mean the production of individual components - such as transistors, resistors, capacitors or others - integrated into the monocrystalline semiconductor layer 14 of the substrate.

According to one implementation, the method may further comprise, after the performance 112 of the front-end processes, the application 113 of laser radiation in a determined wavelength range to the intermediate substrate 10, thereby increasing the temperature of the absorption layer 4 and allowing the degradation of the separation zone 8 once the temperature of the absorption layer 4 reaches a threshold, and thus allowing the separation of at least part of the support 13 from the remainder of the intermediate substrate 10. The application 113 of laser radiation may in particular be done on the support layer 7.

According to one implementation, and after the application 113 of laser radiation, the method may further comprise a step 114 of removing residual layers 15 located on a face of the first semiconductor layer 2 opposite the monocrystalline semiconductor layer. The residual layers 15 come from the step 113 of applying the laser radiation, and comprise in particular the first thermal barrier layer 5, and possibly the absorption layer 3 as well as a portion of the separation layer 4.

Figure 10 illustrates the temperature evolution in the intermediate substrate 10 during simulations of irradiation of the substrate by a laser radiation of 50 Watts and 125 micrometers in diameter, having a wavelength of 404 nanometers. Three curves I, II and III are shown, corresponding respectively to an irradiation duration of 47.2 milliseconds, 47.9 milliseconds and 50 milliseconds. The intermediate substrate 10 used for the simulation comprises two separate thermal barrier layers 5, 6 as well as a separation layer 4, and the laser radiation is applied to a free face of the support layer 7 opposite the other layers of the intermediate substrate 10. It can be seen that the temperature of the absorption layer exceeds 2000 °C while the temperatures of the first semiconductor layer 2 and the support layer 7 rise to a maximum of approximately 800 °C.

Figure 11 shows a change in the maximum temperature in the separation layer 4 as a function of the diameter of the laser used, under the same simulation conditions as for Figure 10. The three curves I, II and III correspond respectively to exposure times of the intermediate substrate 10 of 50, 100 and 200 microseconds. It can be seen that it is necessary to provide a small laser radiation diameter in order to obtain a sufficiently high temperature rise in the separation layer 4. For an increase in the temperature in the separation layer 4 beyond 2000 °C, laser radiation of less than 150 micrometers in diameter is necessary under these simulation conditions.

Figure 12 shows, for the same simulation conditions: the evolution of the maximum temperature in the separation layer 4, the latter being represented by the curves marked I to VI, the evolution of the surface temperature of the substrate, represented by the curve marked VII for laser radiation of 125 micrometers in diameter and for an exposure time of 200 microseconds.

The diameter of the laser beam can vary depending on several factors, for example the laser power or the materials present in the substrate. For the maximum temperature values in the separation layer 4, the parameters of the laser used are listed, for each curve, in Table 1 below.

As for the surface temperature of the substrate, it is seen that it reaches a maximum of about 200 °C, much lower than the temperatures obtained in the separation layer, which demonstrates the effectiveness of the thermal barrier layers 5, 6.

The evolutions of the substrate surface temperature observed during these simulations for the other parameters (i.e. the simulation parameters corresponding to curves I to V), which are not shown in Figure 12, are similar.

[Table 1]

Claims

1. Intermediate substrate (10) for manufacturing a semiconductor substrate, successively comprising: a. a first semiconductor layer (2), b. a first thermal barrier layer (5), c. a support (13) comprising: i. an absorption layer (3) configured to absorb laser radiation in a determined wavelength range, the temperature of the absorption layer (3) increasing during absorption, and ii. a separation layer (4) comprising a separation zone (8) adjacent to the absorption layer (3) and configured to thermally degrade under the effect of the increase in temperature of the absorption layer, so as to separate at least part of the support (13) from the rest of the intermediate substrate (10), the degradation of the separation zone (8) taking place when the absorption layer (3) reaches a threshold temperature, iii. a second thermal barrier layer (6), and iv. a support layer (7), the support layer (7) being a second semiconductor layer of lower quality than the first semiconductor layer (2). 2. Intermediate substrate (10) according to claim 1, further comprising a seed layer (1) suitable for the growth of the first semiconductor layer (2), the seed layer (1) preferably comprising graphite, the first semiconductor layer (2) being interposed between the seed layer (1) and the first thermal barrier layer (5). 3. Intermediate substrate according to any one of claims 1 and 2, the separation layer (4) being made of silicon nitride. 4. Intermediate substrate according to any one of claims 1 to 3, the absorption layer (3) being made of a material chosen from polycrystalline silicon carbide of p-SiC type, titanium nitride or zirconium. 5. Intermediate substrate according to any one of claims 1 to 4, further comprising a monocrystalline semiconductor layer (14), preferably comprising silicon carbide (SiC) or gallium nitride (GaN), a first face of the monocrystalline semiconductor layer (14) being adjacent to the first semiconductor layer (2). 6. Intermediate substrate according to any one of claims 1 to 5, the first semiconductor layer (2) being made of a broadband semiconductor material, in particular a material chosen from silicon carbide, aluminum nitride and gallium nitride. 7. Intermediate substrate according to any one of claims 1 to 6, in which the support layer (7) is made of a material chosen from silicon carbide and silicon nitride. 8. Intermediate substrate according to any one of claims 1 to 7, the support layer (7) having a thickness of between 100 and 200 nanometers. 9. Intermediate substrate according to any one of claims 1 to 8, the first (5) and/or the second layer (6) forming a thermal barrier having a thermal conductivity of less than 25 W/mK, the second layer (6) forming a thermal barrier preferably being made of titanium dioxide or silicon nitride. 10. An intermediate substrate according to any one of claims 1 or 3 to 9, further comprising a monocrystalline semiconductor layer (14) disposed on a surface region of the first semiconductor layer, the first semiconductor layer (2) being located between the first thermal barrier layer (5) and the monocrystalline semiconductor layer (14). 11. A method of manufacturing an intermediate semiconductor substrate (10), successively comprising the steps of: a. growing (101) a first electrically semiconductor layer (2) on a seed layer (1), b. growing (102), on the first semiconductor layer (2), a first thermal barrier layer (5), c. growing (103), on the first thermal barrier layer (5), a support (13) comprising an absorption layer (3) configured to absorb laser radiation in a determined wavelength range, the temperature of the absorption layer (3) increasing upon absorption, the support (13) further comprising a separation zone (8) adjacent to the absorption layer (3) and configured to thermally degrade under the effect of the increase in temperature of the absorption layer, so as to separate at least part of the support (13) from the remainder of the intermediate substrate (10), d. removal (104) of the seed layer (1), the growth steps being obtained by gas phase deposition on the previously formed layers. 12. A method of manufacturing an intermediate semiconductor substrate (10) according to claim 11, the growth (103) of the support (13) comprising successive steps of: a. growing a separation assembly (12) consisting of the absorption layer (3) and a separation layer (4), the growth of the separation assembly (12) comprising: the growth (1031) of the absorption layer (3); the growth (1032) of the separation layer (4), the separation layer (4) comprising the separation zone (8), the separation zone (8) being adjacent to the absorption layer (3); b. growing (1033), on the separation assembly (12), a second thermal barrier layer (6); c. growing (1034), on the second thermal barrier layer (6), a support layer (7), the growth steps being obtained in particular by gas phase deposition on the previously formed layers. 13. A method of manufacturing an intermediate semiconductor substrate (10) according to claim 11, the growth (103) of the support (13) comprising successive steps of: a. growth (1031), on the first thermal barrier layer (5), of the absorption layer (3) b. growth (1035), on the absorption layer (3), of a support layer (7) also acting as a second thermal barrier, the separation zone (8) being included in the support layer (7), the growth steps being obtained in particular by gas phase deposition on the previously formed layers. 14. A method of manufacturing a substrate comprising a monocrystalline semiconductor layer on a polycrystalline semiconductor substrate, comprising implementing the method of manufacturing an intermediate semiconductor substrate (10) according to any one of claims 11 to 13, the first semiconductor layer (2) being polycrystalline, and further comprising successive steps of: a. forming (109) a weakening zone in a semiconductor donor substrate (9) by implantation of species, so as to delimit a monocrystalline semiconductor layer (14) to be transferred, b. bonding (110) the monocrystalline semiconductor layer (14) to be transferred to a surface region of the first semiconductor layer (2), c. detaching (111) the donor substrate (9) along the weakening zone to transfer the monocrystalline semiconductor layer (14) to the first semiconductor layer (2). 15. A method of manufacturing an electronic component, comprising successive steps of: a. Implementing the method of manufacturing a substrate according to claim 14, b. Carrying out (112) front-end processes in the monocrystalline semiconductor layer (14) to form said electronic component. 16. A method of manufacturing an electronic component according to claim 15, comprising, after carrying out said front-end processes, a step of applying (113) laser radiation in the determined wavelength range to the intermediate substrate (10), so as to thermally degrade the separation zone (8) and to separate at least part of the support (13) from the rest of the intermediate substrate (10). 17. Method of manufacturing an electronic component according to claim 16, comprising, after the application of the laser radiation, a step of removing (114) residual layers (15) located on one face of the first layer. semiconductor (2) opposite the monocrystalline semiconductor layer (14), the residual layers (15) coming from the step of application (113) of the laser radiation.