Method for locating devices

Abstract

Method for locating devices after the transfer of a utility layer (80), the method comprising the following steps: a) Providing a support substrate (10), comprising: - a device layer (40) comprising a free area; and - Alignment markers (50); b) Providing a donor substrate (60); c) Forming a weakened zone (70) in the donor substrate (60), wherein the weakened zone (70) borders a working layer (80); d) Mounting the donor substrate (60) and the support substrate (10); and e) Breaking the donor substrate (60) in the weakened zone (70) to transfer the working layer (80) to the device layer (40); wherein the alignment markings (50) are arranged in cavities (90) formed in the device layer (40), wherein the cavities (90) have an opening that is flush with the free surface of the device layer (40), and wherein, in step e) of breaking the donor substrate (60), through holes are automatically formed in the working layer (80) which correspond in position to the cavities (90).

Description

Field of invention

[0001] The present invention relates to a method for locating devices after the transfer of a functional layer onto a carrier substrate. Background of the invention

[0002] US 2011 / 0298021 A1 discloses a semiconductor device and a method for manufacturing the semiconductor device, in which an insulating intermediate layer comprising silicon, oxygen, and carbon is formed on a wiring plane. WO 2012 / 042653 A1 discloses a manufacturing method for a semiconductor device in which the substrate and adhesive have such transparency that a front surface of the semiconductor wafer is visible. A prior art method for locating devices after the transfer of a utility layer 8 onto a substrate 1, as described in Fig. As shown in 1a, it includes the following steps: a0) Providing a carrier substrate 1, comprising: - a front side 2; - a reverse side 3, parallel to the front side 2; and - a device layer 4 arranged on the front side 2, wherein the device layer 4 comprises alignment markings 5; b0) Providing a donor substrate 6; c0) Forming a weakened zone 7 in the donor substrate 6, wherein the weakened zone 7 borders a working layer 8; d0) Mounting the donor substrate 6 and the support substrate 1; and e0) Breaking the donor substrate 6 in the weakened zone 7 to transfer the usable layer 8 to the device layer 4.

[0003] Device layer 4 includes devices such as transistors, (npn or pnp) junctions, interconnects and other structures.

[0004] The utility layer 8 generally comprises an opaque semiconductor layer. After the breaking step e0), the utility layer 8 masks the fixtures on the fixture layer 4 and the alignment markers 5.

[0005] The biggest disadvantage of this method is that the alignment markings 5 ​​are no longer accessible or visible.

[0006] Therefore, as in Fig. Figure 1b shows a common procedure in which openings 9 (or holes) are made in the wear layer 8 to expose the alignment marks 5.

[0007] The process for forming the openings 9 generally includes a photolithography step followed by an etching step.

[0008] The photolithography step serves to define the shape and position of the openings in the payload layer 9. However, this step is performed without any reference point other than the edge of the substrate 1 and has a precision of ±100 µm. The alignment marks 5 can therefore only be located within ±100 µm. The openings 9 must therefore have a side length of approximately 250 µm.

[0009] Such a side length consumes too much space and is unacceptable.

[0010] One objective of the invention is therefore to provide a simpler method for locating devices after the transfer of a utility layer 8, so that smaller openings can be formed than with the methods according to the prior art. Brief description of the invention

[0011] The present invention provides a solution to the aforementioned problems and relates to a method for locating devices after the application of a utility layer according to claim 1.

[0012] The alignment markings are arranged so that the devices can be located.

[0013] The wear layer can consist of a set of sublayers.

[0014] The functional layer is generally opaque and therefore masks the device layer according to step e).

[0015] The cavities have walls, and the volume of a cavity bounded by the walls and its opening constitute the volume of the cavity.

[0016] The expression "alignment markings are arranged in cavities" means that the alignment markings are arranged within the volume of the cavities.

[0017] The applicant observed the presence of through holes in the working layer after the breaking step (e), which correspond in position to the cavities. The holes thus extend the cavities into the working layer, so that the alignment marks are visible from the free surface of the working layer.

[0018] The devices of the device layer can thus be located from the free area of ​​the working layer.

[0019] Furthermore, it is not necessary to perform special steps to create holes in the wear layer. According to the invention, the holes are automatically formed at the positions of the cavities at the moment the wear layer is applied.

[0020] According to one implementation procedure, assembly step d) includes a direct bonding step, which is carried out in an environment at a pressure of less than 2000 Pa (20 mbar).

[0021] According to the applicant's observations, the through-holes in the surface layer have a shape that corresponds to the opening of the cavities.

[0022] The through-holes in the surface layer therefore do not extend further than the opening of the cavities.

[0023] According to one implementation procedure, the cavities extend into the substrate.

[0024] According to an implementation procedure, the alignment markings are arranged on the bottom of the cavities.

[0025] According to one implementation method, the device layer comprises devices that are regularly distributed across the entire area of ​​the device layer.

[0026] According to one implementation procedure, an opaque layer is present on the wear layer before assembly step d).

[0027] According to an implementation procedure, the opaque layer comprises at least one material selected from the following group: tungsten, titanium, tungsten silicide, titanium silicide, nickel silicide, nickel silicide and platinum.

[0028] According to an implementation procedure, step c) is carried out to form the weakened zone by implanting at least one species chosen from the following group: hydrogen and helium.

[0029] According to an implementation procedure, the step to break e) includes a heat treatment carried out at a temperature between 200 and 500 °C.

[0030] According to one implementation method, the thickness of the functional layer is less than 800 nm (8000 Å) and preferably less than 500 nm (5000 Å).

[0031] According to one implementation method, the user layer comprises sublayers with different doping levels. Brief description of the drawings

[0032] Further features and advantages will become apparent from the following description of implementation methods of a method for locating devices according to the invention, the description serving only as a non-limiting example and referring to the attached drawings, in which: Fig. 1a and Fig. 1b schematic representations of a structure obtained using a prior art device locating method; Fig. 2 a schematic representation of a method for locating devices according to an embodiment of the invention; Fig. 3 is a schematic representation of the structure obtained using the device locating method according to a second embodiment of the invention; and Fig. Figure 4 is a schematic representation of the method for locating devices according to an embodiment of the invention. Detailed description of exemplary embodiments of the invention

[0033] In the various implementation methods, the same reference symbols are used for identical elements or elements that offer the same function, for better understanding of the description.

[0034] Fig. 2 and Fig. Figure 3 thematically demonstrates a method for locating devices.

[0035] To simplify the presentation, the respective thicknesses of the different layers have not been shown to scale.

[0036] Step a) of the procedure for locating devices includes providing a support substrate 10.

[0037] The carrier substrate 10 can comprise a bulk substrate on which a device layer 40 is formed.

[0038] The bulk substrate can consist of any material that is conventionally used in the fields of microelectronics, optics, optoelectronics and photovoltaics.

[0039] In particular, the bulk substrate comprises at least one material selected from the following group: silicon, silicon carbide, silicon germanium, glass, ceramics and a metal alloy.

[0040] The device layer 40 includes devices such as electronic devices (for example, transistors, junctions, etc.), connections and / or metallized zones.

[0041] The devices are formed using techniques known to experts.

[0042] The devices are distributed in a particularly advantageous manner over the entire area of ​​the device layer 40.

[0043] Cavities 90 are formed in the device layer 40. The cavities 90 are open and comprise an opening that is flush with the free surface of the device layer 40.

[0044] The cavities 90 contain walls. The walls of cavity 90 and the opening of cavity 90 define the volume of cavity 90.

[0045] Advantageously, the cavities 90 extend into the support substrate 10.

[0046] Alignment markings 50 are arranged in the volume of the cavities 90, the alignment markings 50 spacing the opening of these cavities 90.

[0047] The alignment markings 50 are arranged so that the devices of the device layer 40 can be precisely located.

[0048] Alignment marks 50 are conventionally used to align photolithographic masks.

[0049] The alignment markings 50 can be in the form of crosses, zigzag lines or interference patterns, or any other form which allows the precise localization of the devices to be determined.

[0050] In this context, experts can find a technical description of the alignment or photolithographic masks in "Fundamentals of Microfabrication: The Science of Miniaturization, 2nd Edition, Marc J. Madou, Nanogen, Inc., San Diego, CA".

[0051] Advantageously, the alignment markings 50 are arranged on the bottom of the cavities 90.

[0052] Step b) of the device localization procedure includes providing a donor substrate 60.

[0053] The donor substrate 60 can consist of any material that is conventionally used in the fields of microelectronics, optics, optoelectronics and photovoltaics.

[0054] In particular, the donor substrate 60 comprises at least one material selected from the following group: silicon, silicon carbide and silicon germanium.

[0055] The donor substrate 60 can advantageously comprise a semiconductor.

[0056] Step c) of the device localization procedure comprises forming a weakened zone 70 in the donor substrate 60.

[0057] The donor substrate 60 comprises a first surface. The weakened zone 70 and the first surface of the donor substrate 60 define a working layer 80, which is intended to be transferred to the device layer 40.

[0058] The weakened zone 70 can be maintained by implanting atomic species. This weakening implantation can be performed with a single species (for example, hydrogen or helium), but also with a multitude of species implanted sequentially (for example, hydrogen and helium).

[0059] The hydrogen is preferably introduced with an energy between 20 keV (3.204353268 fJ) and 70 keV (11.215236438 fJ) and a dose between 4×10 16 and 6×10 16 atoms / cm² 2 implanted.

[0060] The helium is preferably used with an energy between 20 and 70 keV and a dose between 0.5×10 16 and 3×10 16 atoms / cm² 2 implanted.

[0061] In a particularly advantageous manner, the functional layer 80 has a thickness of less than 800 nm (8000 Å) and preferably less than 500 nm (5000 Å).

[0062] Step d) of the device localization procedure includes mounting the donor substrate 60 and the support substrate 10.

[0063] Advantageously, step d) for assembly is carried out by direct bonding.

[0064] The assembly is advantageously carried out by bringing the wear layer 80 into direct contact with the fixture layer. During assembly, the volume of the cavities 90 is at least partially retained. Therefore, the presence of the cavities 90 creates zones without bonding.

[0065] Particularly advantageously, assembly step d) includes a direct bonding step which is carried out in an environment at a pressure of less than 2000 Pa (20 mbar).

[0066] As in Fig. As shown in 4, an intermediate layer 100 can be placed on the wear layer 80 before assembly step d).

[0067] The intermediate layer 100 can be an opaque layer arranged on the functional layer 80.

[0068] The opaque layer may comprise at least one material selected from the following group: tungsten, titanium, tungsten silicide, titanium silicide, nickel silicide, nickel silicide and platinum.

[0069] Step e) of the device localization method comprises breaking the donor substrate 60 in the weakened zone 70 to transfer the utility layer 80 to the device layer 40.

[0070] Therefore, after step e), the wear layer 80 masks the devices.

[0071] If an opaque layer was formed on the working layer 80 before assembly step b), the opaque layer is located between the working layer 80 and the fixture layer 40 after the breaking step.

[0072] Advantageously, the breaking step e) includes a heat treatment carried out at a temperature between 200 and 500 °C.

[0073] The applicant observed that the presence of through holes in the working layer 80 and the opaque layer, provided the latter is present, is particularly advantageous after step b) for breaking.

[0074] Furthermore, the through holes in the working layer 80 correspond in position to the cavities 90, so that the holes extend the cavities 90 into the working layer 80.

[0075] Furthermore, the opening of each cavity 90 is inscribed into the opening of a hole in the working layer 80.

[0076] In particular, in step d), comprising direct bonding in an environment with a pressure of less than 2000 Pa (20 mbar), each hole in the utility layer 80 has an opening that corresponds to the opening in the cavity 90 which it enlarges, as shown in Fig. 3 shown.

[0077] The presence of these holes in the wear layer 80 is particularly advantageous when exposing the alignment markings 50 arranged in the cavities 90. This makes it possible to locate the devices masked by the wear layer 80.

Claims

[1] Method for locating devices after the transfer of a utility layer (80), the method comprising the following steps: a) Providing a support substrate (10), comprising: - a device layer (40) comprising a free area; and - Alignment markers (50); b) Providing a donor substrate (60); c) Forming a weakened zone (70) in the donor substrate (60), wherein the weakened zone (70) borders a working layer (80); d) Mounting the donor substrate (60) and the support substrate (10); and e) Breaking the donor substrate (60) in the weakened zone (70) to transfer the working layer (80) to the device layer (40); wherein the alignment markings (50) are arranged in cavities (90) formed in the device layer (40), wherein the cavities (90) have an opening that is flush with the free surface of the device layer (40), and wherein, in step e) of breaking the donor substrate (60), through holes are automatically formed in the working layer (80) which correspond in position to the cavities (90). [2] Method according to claim 1, wherein assembly step d) comprises a direct bonding step which is carried out in an environment at a pressure of less than 20 mbar. [3] Method according to claim 1 or 2, wherein the cavities (90) extend into the support substrate (10). [4] Method according to any one of claims 1 to 3, wherein the alignment markings (50) are arranged on the bottom of the cavities (90). [5] Method according to any one of claims 1 to 4, wherein the device layer (40) comprises devices which are regularly distributed over the entire area of ​​the device layer (40). [6] Method according to any one of claims 1 to 5, wherein an opaque layer is present on the wear layer (80) before assembly step d). [7] Method according to claim 6, wherein the opaque layer comprises at least one material selected from the following group: tungsten, titanium, tungsten silicide, titanium silicide, nickel silicide, nickel silicide and platinum. [8] Method according to any one of claims 1 to 7, wherein step c) to form the weakened zone (70) is carried out by implanting at least one species selected from the following group: hydrogen and helium. [9] Method according to any one of claims 1 to 8, wherein the breaking step e) comprises a heat treatment carried out at a temperature between 200 and 500 °C. [10] Method according to any one of claims 1 to 9, wherein the thickness of the functional layer (80) is less than 800 nm and preferably less than 500 nm. [11] Method according to any one of claims 1 to 10, wherein the functional layer (80) comprises sublayers with different doping.

Images