Electrode preparation method of semiconductor device

Abstract

The invention provides an electrode preparation method of a semiconductor device. The electrode preparation method comprises the steps that a semiconductor base body and a donor substrate are provided, the semiconductor base body is provided with a first surface, a boss structure is arranged in the first surface, and the donor substrate is provided with a second surface; forming a transfer film on the second surface, wherein the material of the transfer film comprises a conductive material; the transfer printing film is attached to the top table top of the boss structure; the semiconductor base body is separated from the donor substrate through the transfer printing technology, so that the top table top picks up the conductive material attached to the top table top in the transfer printing film, and pickup is achieved through the transfer printing technology by controlling the stripping speed; and curing the conductive material of the top mesa to obtain an electrode of the semiconductor device. According to the invention, the problem of low patterning uniformity of the mesa electrode of the semiconductor device in the prior art is solved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor chip process preparation, and in particular, to a method for preparing an electrode of a semiconductor device. Background Art

[0002] High-power devices such as IGCT and IGBT are key modules in DC power transmission and transformation technology. The cathode of the device has a special table structure (or boss structure, the surface of which includes a top table and inclined side walls), which is responsible for the electrical isolation of the gate cathode during crimping. To ensure effective insulation isolation, the table height of the cathode table structure should reach 15µm, so the gate cathode structure needs to be designed as a so-called "table-like" groove structure.

[0003] In order to meet the high withstand voltage requirements of power devices, the thickness of the mesa electrode can reach more than 20µm and the consistency of the electrode morphology must be met. However, during the preparation of the mesa electrode, due to the height difference between the mesa structure and the trench structure, the glue thickness of the top mesa of the mesa structure and the bottom of the trench of the trench structure is uneven (the glue thickness of the top mesa is lower), and the top mesa will be overexposed under the same exposure dose and time, which reduces the exposure uniformity and affects the uniformity of the photoresist line width; in addition, due to the scattering of light caused by the inclined sidewalls of the mesa structure, the exposure pattern position at the mesa structure will be offset and cannot be aligned, reducing the uniformity of the metal electrode (including the mesa electrode) line width and patterning, and even causing the gate cathode short circuit phenomenon.

[0004] In summary, the current patterning preparation technology of mesa electrodes faces problems such as low lithography uniformity, difficult etching process and low efficiency, which seriously affect the reliability, processing efficiency and yield of power devices. Summary of the invention

[0005] The main purpose of the present application is to provide a method for preparing an electrode of a semiconductor device, so as to solve the problem of low uniformity of the patterning of mesa electrodes of semiconductor devices in the prior art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a method for preparing an electrode of a semiconductor device is provided, comprising: providing a semiconductor base and a donor substrate, the semiconductor base having a first surface, the first surface having a boss structure, and the donor substrate having a second surface; forming a transfer film on the second surface, the material of the transfer film comprising a conductive material; bonding the transfer film to the top table of the boss structure; separating the semiconductor base from the donor substrate by using a transfer technology so that the top table picks up the conductive material bonded to the top table in the transfer film, wherein the transfer technology achieves the picking up by controlling the peeling speed; and curing the conductive material on the top table to obtain the electrode of the semiconductor device.

[0007] Optionally, the conductive material is liquid metal, and a transfer film is formed on the second surface, including: dissolving the liquid metal and a polymer matrix material to prepare a composite conductive slurry, wherein the polymer matrix material includes nanoclay or hydrogel; and coating the composite conductive slurry on the second surface to form a transfer film.

[0008] Optionally, the electrode preparation method further comprises: before the step of laminating the transfer film to the top table of the boss structure, forming an interface modification layer on the first surface, wherein the material of the interface modification layer has hydrogen bonds.

[0009] Optionally, the conductive material is solid metal, and forming a transfer film on the second surface includes: using a thin film deposition technology to deposit the solid metal on the second surface to form the transfer film.

[0010] Optionally, the conductive material is solid metal, and the transfer film is bonded to the top surface of the boss structure to obtain a bonded structure. The electrode preparation method also includes: heat treating the bonded structure at a temperature higher than the melting point of the solid metal.

[0011] Optionally, laminating the transfer film with the top surface of the boss structure includes: transferring the semiconductor substrate to a surface of the transfer film facing away from the donor substrate; and applying pressure to the semiconductor substrate to laminarly fit the transfer film with the top surface of the boss structure.

[0012] Optionally, when the conductive material is liquid metal, a first pressure is applied to the semiconductor substrate, and the first pressure is 5-10N.

[0013] Optionally, when the conductive material is solid metal, a second pressure is applied to the semiconductor substrate, and the second pressure is 50-100N.

[0014] Optionally, the semiconductor substrate has a first end and a second end relative to each other, and the direction in which the first end points to the second end is parallel to the first surface. The semiconductor substrate is separated from the donor substrate by using a transfer technology, including: lifting the semiconductor substrate from the first end; peeling the semiconductor substrate and the conductive material in the transfer film that is in contact with the top table from the donor substrate until the second end is separated from the donor substrate.

[0015] Optionally, a first peeling speed is used to peel the semiconductor base and the conductive material in the transfer film that is in contact with the top table from the donor substrate, and the first peeling speed is 10-30 cm / s.

[0016] The technical solution of the present application is applied to a method for preparing an electrode of a semiconductor device, comprising: providing a semiconductor substrate and a donor substrate, wherein the semiconductor substrate has a first surface, a boss structure is provided in the first surface, and the donor substrate has a second surface; forming a transfer film on the second surface, wherein the material of the transfer film includes a conductive material; laminating the transfer film with the top table of the boss structure; separating the semiconductor substrate from the donor substrate by a transfer technique, so that the top table picks up the conductive material laminating with the top table in the transfer film, wherein the transfer technique realizes the picking up by controlling the peeling speed; and curing the conductive material on the top table to obtain an electrode of the semiconductor device. Through the present application, the boss structure is laminating and separating the transfer film formed on the second surface of the donor substrate by a transfer technique, so that the conductive material can automatically align with the boss structure, thereby achieving the purpose of picking up the conductive material by a stamp-type self-alignment technique, and avoiding the lithography and etching problems such as light scattering at the boss due to the structural particularity of the boss structure of the semiconductor substrate and low exposure uniformity and CD uniformity caused by uneven glue thickness, thereby obtaining an electrode (table electrode) with higher uniformity. In summary, the present application solves the problem of low uniformity of mesa electrode patterning of semiconductor devices in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0018] Figure 1 A schematic structural diagram of a semiconductor substrate provided in a method for preparing an electrode of a semiconductor device according to an embodiment of the present application is shown;

[0019] Figure 2 A schematic structural diagram of a donor substrate with a transfer film and an inverted semiconductor substrate is shown in a method for preparing an electrode of a semiconductor device according to an embodiment of the present application;

[0020] Figure 3 A schematic structural diagram of a donor substrate and a semiconductor base after a top table picks up a conductive material in a transfer film that is bonded to a top table in a method for preparing an electrode of a semiconductor device according to an embodiment of the present application is shown.

[0021] The above drawings include the following reference numerals:

[0022] 10. Semiconductor substrate; 101. Boss structure; 20. Donor substrate; 30. Transfer film; 40. Conductive material. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0026] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be intermediate elements. Moreover, in the specification and claims, when it is described that an element is "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element through a third element.

[0027] As introduced in the background technology, in the prior art, during the preparation process of the mesa electrode, due to the height difference between the mesa structure and the trench structure, the glue thickness of the top mesa of the mesa structure and the bottom of the trench of the trench structure is uneven (the glue thickness of the top mesa is lower), and the top mesa will be overexposed under the same exposure dose and time, which reduces the exposure uniformity and thus affects the uniformity of the photoresist line width; in addition, due to the scattering of light generated by the inclined sidewall of the mesa structure, the exposure pattern position at the mesa structure will be offset and cannot be aligned, reducing the uniformity of the line width and patterning of the metal electrode (including the mesa electrode), and even causing the gate cathode short circuit phenomenon. In order to solve the problem of low uniformity of the patterning of the mesa electrode of the semiconductor device in the prior art, the embodiment of the present application provides a method for preparing an electrode of a semiconductor device.

[0028] The present application provides a method for preparing an electrode of a semiconductor device, comprising:

[0029] A semiconductor base and a donor substrate are provided, wherein the semiconductor base has a first surface, wherein a boss structure is provided in the first surface, and the donor substrate has a second surface; a transfer film is formed on the second surface, wherein the material of the transfer film includes a conductive material; the transfer film is bonded to the top table of the boss structure; a transfer technique is used to separate the semiconductor base from the donor substrate, so that the top table picks up the conductive material bonded to the top table in the transfer film, wherein the transfer technique achieves the picking up by controlling the peeling speed; and the conductive material on the top table is solidified to obtain an electrode of the semiconductor device.

[0030] In the above implementation, the boss structure is attached to and separated from the transfer film formed on the second surface of the donor substrate by transfer technology, so that the conductive material can automatically align with the boss structure, achieving the purpose of picking up the conductive material by the stamp-type self-alignment technology, and avoiding the lithography and etching problems such as light scattering at the boss due to the structural particularity of the boss structure of the semiconductor substrate, low exposure uniformity and CD uniformity caused by uneven glue thickness, so that a more uniform electrode (table electrode) can be obtained. In summary, the present application solves the problem of low uniformity of the patterning of the table electrode of the semiconductor device in the prior art.

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0032] In some embodiments, Figure 1 As shown, a boss structure 101 can be prepared on one side surface of a semiconductor substrate to obtain a semiconductor substrate 10, so that the boss structure 101 protrudes in the first surface to generate a height difference, so as to serve as a recipient or a receiving object of a transfer film on a donor substrate. Among them, the first surface of the semiconductor substrate 10 can have a plurality of boss structures 101 arranged at intervals. Furthermore, the plurality of boss structures 101 can be presented as evenly distributed comb boss structures in the first surface.

[0033] Specifically, Figure 1 As shown, the boss structure 101 can be prepared by dry / wet etching method:

[0034] For wet etching processes, such as Figure 1As shown, after first preparing a patterned mask layer through a photolithography process, a specific proportion of silicon etching solution (a mixture of hydrofluoric acid, concentrated nitric acid and hydrogen peroxide) can be selected, based on a tooling clamping and rotating etching process, at a specific etching time (such as 1 to 3 minutes) and process temperature (such as 15 to 25°C), a wet trenching process of a semiconductor substrate can be completed, and the table height is 15 to 20µm, forming a uniformly distributed comb-shaped convex platform structure, and the etching uniformity is less than 3%. After the preparation of the table structure is completed, the surface mask is removed through a plasma dry stripping process or an inorganic wet stripping process to complete the preparation of the convex platform structure 101.

[0035] For the dry etching process, after first preparing a patterned mask layer through a photolithography process, by selecting etching gases (sulfur hexafluoride and oxygen) with a specific ratio and flow rate, based on the deep silicon etching process, at a specific etching time, upper electrode power, chamber pressure and process temperature, the dry etching process of the semiconductor substrate is completed, and the table height is 15~20µm, forming a uniformly distributed comb-shaped convex structure, and the etching uniformity is less than 3%. After the preparation of the table structure is completed, the surface mask is removed by a plasma dry stripping process or an inorganic wet stripping process to complete the preparation of the convex structure 101.

[0036] In some optional embodiments, the conductive material is liquid metal, and a transfer film 30 is formed on the second surface, including: dissolving the liquid metal and the polymer matrix material to prepare a composite conductive paste, wherein the polymer matrix material includes nanoclay or hydrogel; and coating the composite conductive paste on the second surface to form the transfer film 30.

[0037] Specifically, Figure 2 As shown, in the case where the conductive material is liquid metal, firstly, the semiconductor substrate 10, the donor substrate 20 and the composite conductive paste are provided, and then the composite conductive paste is coated on the second surface of the donor substrate 20 to form a transfer film 30. It is noted here that the order of the steps of preparing the composite conductive paste, providing the semiconductor base and providing the donor substrate 20 is not limited, and the step of coating the composite conductive paste on the second surface is after providing the donor substrate 20. Next, the transfer film 30 is bonded to the top table of the boss structure 101, and then the semiconductor substrate 10 is separated from the donor substrate 20 by using the transfer technology, so that the top table picks up the conductive material (composite conductive paste) bonded to the top table in the transfer film 30, and then the conductive material (composite conductive paste) on the top table is cured to obtain the electrode of the semiconductor device.

[0038] In the above embodiment, when the conductive material of the transfer film 30 is liquid metal, by dissolving the liquid metal and the polymer matrix material, a composite conductive paste having a smaller surface tension than that of the liquid metal and high viscosity can be formed. Therefore, when the composite conductive paste is coated on the second surface, the difficulty of spreading and extending the transfer film 30 is reduced, so that a transfer film 30 with better film quality can be obtained.

[0039] Specifically, Figure 2 As shown, the thickness of the transfer film 30 in this embodiment can be 20-40 μm.

[0040] Specifically, Figure 2 As shown, the transfer film 30 can be prepared from the composite conductive paste, that is, the material of the transfer film 30 includes the liquid metal and the polymer matrix material. It is explained here that since the composite conductive paste contains conductive liquid metal, the composite conductive paste is also a conductive material.

[0041] The liquid metal is a low melting point alloy and may include a gallium-based liquid metal or a mercury-based liquid metal.

[0042] In some examples, the liquid metal includes but is not limited to one or more of metal elements such as Ga, In, Sn, Bi, Mg, Zn, and Hg.

[0043] Specifically, when the conductive material is liquid metal and the polymer matrix material is nanoclay, the steps for preparing the composite conductive slurry may be: adding nanoclay powder to the liquid metal, and stirring at high speed to form a high-viscosity paste-like conductive nanoclay, i.e., the composite conductive slurry.

[0044] Specifically, when the conductive material is liquid metal and the polymer matrix material is hydrogel, the steps for preparing the composite conductive paste may be: firstly, ultrasonically treat the liquid metal, extract the liquid metal sediment after dispersion precipitation, and mix it into the hydrogel, and after stirring and curing, obtain the liquid metal hydrogel "ink", i.e., the composite conductive paste. The hydrogel may include but is not limited to polyvinyl alcohol (PVA), poly (acrylic acid) (PAA), (PAAm) and biopolymers.

[0045] It is explained here that the viscosity of the composite conductive paste can be controlled by adjusting the volume proportion of the polymer matrix material. Among them, the higher the proportion of the polymer matrix material, the greater the viscosity, the better the overall support and film-forming properties of the composite conductive paste, and the more conducive it is to be used as an "ink pad" material to be picked up by the top table of the boss structure of the semiconductor substrate; the higher the proportion of liquid metal, the better the conductivity of the composite conductive paste. Those skilled in the art can adjust the proportion of polymer matrix material and liquid metal in the composite conductive paste according to actual needs, without limitation here.

[0046] In addition, in order to coat the composite conductive slurry on the second surface to form a transfer film, the composite conductive slurry can be spread on the second surface by any one of spin coating, drip coating, spray coating, dip coating and brush coating. In this step, the thickness of the transfer film can be regulated by adjusting the process parameters such as spin coating, such as by adjusting the spin coating speed, increasing the speed can obtain a thinner transfer film; or, a certain amount of composite conductive slurry can be dipped by a customized polymer hard brush and evenly brushed on the second surface. To adjust the thickness of the transfer film, it can be thinned by multiple scrapings, and the thickness of the transfer film can be tested by a thickness measuring tool to ensure that the thickness of the transfer film is controlled within the optimal range.

[0047] In some optional embodiments, the method for preparing an electrode of the semiconductor device further comprises: before the step of laminating the transfer film to the top table of the boss structure, forming an interface modification layer on the first surface, wherein the material of the interface modification layer has hydrogen bonds.

[0048] Specifically, the transfer film can be prepared from the composite conductive paste, that is, the material of the transfer film includes the liquid metal and the polymer matrix material.

[0049] It can be understood that the interface modification layer is formed on the first surface, and the first surface has a platform structure, so that the material of the interface modification layer covers the top platform of the platform structure.

[0050] In the above embodiment, the semiconductor substrate and the donor substrate are first provided, and then a transfer film is formed on the second surface of the donor substrate, and an interface modification layer is formed on the first surface of the semiconductor substrate, and then the transfer film is bonded to the top table of the boss structure. It should be emphasized here that since the interface modification layer is formed on the first surface, the bonding of the transfer film to the top table of the boss structure can be regarded as bonding the transfer film to the top table of the boss structure through the interface modification layer. Furthermore, since the material of the interface modification layer has hydrogen bonds, the material of the transfer film includes a polymer matrix material, so the material of the interface modification layer and the polymer matrix material will form a hydrogen bond between the boss structure and the transfer film, thereby strengthening the adhesion of the conductive material in the transfer film that is bonded to the top table of the boss structure to the top table. Next, the semiconductor base is separated from the donor substrate by using transfer technology so that the top table can pick up the conductive material in the transfer film that is bonded to the top table. It is mentioned here that since the interface modification layer strengthens the adhesion of the conductive material in the transfer film that is bonded to the top table, it can also improve the success rate and adhesion of the top table picking up the conductive material in the transfer film that is bonded to the top table.

[0051] In some optional embodiments, such as Figure 2 As shown, the conductive material in the transfer film is solid metal, and a transfer film 30 is formed on the second surface, including: using a thin film deposition technology to deposit the solid metal on the second surface to form the transfer film 30, and the thin film deposition technology includes electron beam evaporation, thermal evaporation, magnetron sputtering, pulsed laser deposition and electroplating.

[0052] Specifically, Figure 2 As shown, when the conductive material is solid metal, the transfer film 30 can be directly deposited and formed.

[0053] In some examples, the solid metal may include, but is not limited to, one or more of aluminum, copper, silver, platinum, gold, palladium, and iridium.

[0054] It is explained here that if Figure 2 As shown, in this embodiment, the thickness of the transfer film 30 can be adjusted by adjusting the deposition time in the thin film deposition technology. Those skilled in the art can make reasonable choices according to actual needs, and the embodiments of this application are not specifically limited.

[0055] Likewise, if Figure 2 As shown, the thickness of the transfer film 30 in this embodiment can be 20-40 μm.

[0056] In the above embodiment, the semiconductor substrate 10 and the donor substrate 20 are first provided, and then the solid metal is deposited on the second surface by thin film deposition technology to form a transfer film 30. Next, the transfer film 30 is bonded to the top table of the boss structure 101, and then the semiconductor substrate 10 is separated from the donor substrate 20 by transfer technology, so that the top table picks up the conductive material (solid metal) bonded to the top table in the transfer film 30, and then the electrode of the semiconductor device can be obtained by curing the conductive material (solid metal) on the top table.

[0057] In some embodiments, before the step of forming the transfer film on the second surface, a plurality of bonding portions spaced apart may be formed on the second surface by a dispensing process. The electrode preparation method of the semiconductor device in this embodiment may also include: measuring the spacing between two adjacent boss structures of the semiconductor substrate. Thus, the spacing between two adjacent bonding portions may be less than or equal to the length of the boss structure (the length direction of the boss is the direction of the connection between the two adjacent bonding portions, and is also the direction of the connection between the two adjacent boss structures). It is understandable that after the transfer film is formed on the second surface, the plurality of bonding portions may strengthen the bonding strength between the transfer film and the donor substrate. Later, in the process of laminating the transfer film to the top table of the boss structure, each bonding portion corresponds to the groove between the two adjacent boss structures. Since the plurality of bonding portions strengthen the bonding strength between the transfer film and the donor substrate, the process of separating the semiconductor substrate from the donor substrate may make the transfer film easier to be torn at the boundary where it is bonded to the bonding portion, thereby facilitating the picking up of the top table of the boss structure.

[0058] In other optional embodiments, when the conductive material is solid metal, the transfer film is bonded to the top surface of the boss structure to obtain a bonded structure, and the electrode preparation method of the semiconductor device also includes: heat treating the bonded structure, and the heat treatment temperature is higher than the melting point of the solid metal.

[0059] Specifically, the semiconductor substrate and the donor substrate are first provided, and then the solid metal is deposited on the second surface by thin film deposition technology to form a transfer film. Next, the transfer film is bonded to the top table of the boss structure to obtain a bonded structure. The bonded structure is then subjected to the above-mentioned heat treatment so that the solid metal of the transfer film is transformed into a molten ink-like material, and then the semiconductor substrate is separated from the donor substrate by transfer technology so that the top table picks up the conductive material (molten solid metal) bonded to the top table in the transfer film, and then the electrode of the semiconductor device can be obtained by solidifying the conductive material (molten solid metal) on the top table.

[0060] Exemplarily, the thermal treatment of the bonded structure is achieved by placing the bonded structure on a hot plate and heating the hot plate.

[0061] Specifically, if the solid metal is aluminum, and the transfer film is an aluminum film, after the aluminum film is bonded to the top surface of the boss structure to obtain a bonded structure and placed on the hot plate, the heating temperature of the hot plate may be 600-800° C. The heating time may be 1-2 minutes.

[0062] In this embodiment, since the temperature of the heat treatment is higher than the melting point of the solid metal, the transfer film is in a flowing metastable state at the interface with the donor substrate, so that the overall stiffness and internal stress of the transfer film are reduced, and the conductive material of the transfer film is more likely to become unstable and rupture under the action of external force, making it more similar to the material of the composite conductive slurry or "ink pad" material mentioned above, which is more conducive to the top table picking up the conductive material in the transfer film that is in contact with the top table.

[0063] In some optional embodiments, combined with Figure 2 and Figure 3 As shown, the step of bonding the transfer film 30 to the top table of the boss structure 101 includes: transferring the semiconductor substrate 10 to the side surface of the transfer film 30 facing away from the donor substrate 20; applying pressure to the semiconductor substrate 10 to bond the transfer film 30 to the top table of the boss structure 101.

[0064] It is understandable that if Figure 2 As shown, before the semiconductor substrate 10 is transferred to the surface of the transfer film 30 facing away from the donor substrate 20, the semiconductor substrate 10 can be turned over so that the side of the semiconductor substrate 10 having the boss structure 101 faces the transfer film 30. Then, the semiconductor substrate 10 is transferred to the surface of the transfer film 30 facing away from the donor substrate 20, so that the top table of the boss structure 101 can be attached to the transfer film 30.

[0065] After the top table of the boss structure 101 contacts the transfer film 30, pressure may be applied to the semiconductor substrate 10 to make the top table of the boss structure 101 contact and fit with the transfer film 30. It should be noted that the transfer film 30 only fits with the top table of the boss structure 101 without a gap, and does not contact with any part of the first surface of the semiconductor substrate 10 other than the top table, so that after the semiconductor substrate 10 is separated from the donor substrate 20 by the transfer technology, the top table can pick up the conductive material 40 in the transfer film 30 that fits with the top table, such as Figure 3 shown.

[0066] In some optional embodiments, when the conductive material is liquid metal, in order to ensure that the top table surface of the boss structure is in seamless contact and fit with the transfer film without contacting the first surface of the semiconductor substrate other than the top table surface, a first pressure is applied to the semiconductor substrate, and the first pressure is 5~10N.

[0067] In some optional embodiments, when the conductive material is solid metal, in order to ensure that the top table surface of the boss structure is in seamless contact and fit with the transfer film without contacting the first surface of the semiconductor substrate other than the top table surface, a second pressure is applied to the semiconductor substrate, and the second pressure is 50~100N.

[0068] In some optional embodiments, such as Figure 2 and Figure 3 As shown, the semiconductor substrate 10 has a first end (not marked in the figure) and a second end (not marked in the figure) opposite to each other, and the direction pointing from the first end to the second end is parallel to the first surface. The semiconductor substrate 10 is separated from the donor substrate 20 by using a transfer technology, including: lifting the semiconductor substrate 10 from the first end; peeling off the semiconductor substrate 10 and the conductive material 40 in the transfer film 30 that is in contact with the top table from the donor substrate 20 (or in other words, peeling off the conductive material 40 in the transfer film 30 that is in contact with the top table of the boss structure 101 and the semiconductor substrate 10 from the donor substrate 20), until the second end is separated from the donor substrate 20.

[0069] Specifically, Figures 1 to 3 As shown, the semiconductor substrate 10 may be a hard structure.

[0070] In the above embodiment, by following the process of lifting from the first end of the semiconductor substrate and starting to peel off until the second end of the semiconductor substrate is separated from the donor substrate, the success rate of the top table picking up the conductive material in the transfer film that is attached to the top table can be improved.

[0071] In addition, in some examples, in order to ensure that there are sufficient force points when lifting the semiconductor substrate, a gripper can be adsorbed on the surface of the semiconductor substrate on the side away from the donor substrate. The gripper can include but is not limited to a movable suction pen, a vacuum suction pen, a clamping tool, and an adhesive tool.

[0072] According to the kinetic trade-off relationship between the energy release rate and the tearing rate at the interface, the peeling speed between the top table of the boss structure and the donor substrate directly affects the adhesion between the top table and the transfer film. If the top table of the boss structure is lifted from the donor substrate at a higher peeling speed, the adhesion of the top table of the boss structure to the transfer film is strong enough to transfer the conductive material of the transfer film (it can be understood that the conductive material here can be the above-mentioned composite conductive slurry including liquid metal or the above-mentioned solid metal) from the donor substrate to the top table of the boss structure. Thus, in some optional embodiments, in order to improve the success rate of the top table picking up the conductive material in the transfer film that is bonded to the top table, a first peeling speed is used to peel the semiconductor substrate and the conductive material in the transfer film that is bonded to the top table from the donor substrate, and the first peeling speed is 10~30cm / s.

[0073] In some embodiments, if the conductive material is liquid metal, the step of curing the conductive material on the top table to obtain the electrode of the semiconductor device may include: curing the conductive material on the top table by photocuring or thermal curing. For photocuring: the free radicals, monomers, oligomers, etc. in the composite conductive paste may be cross-linked and cured by irradiation with ultraviolet light, so that the composite conductive paste hardens and conforms to obtain an electrode. For thermal curing: the bonds between polymer molecules in the composite conductive paste may be formed by heating, and a three-dimensional network structure may be formed, so that the polymer is cured, and the hardened composite conductive paste conforms to obtain an electrode.

[0074] In some embodiments, if the conductive material is a solid metal, the step of solidifying the conductive material on the top table to obtain an electrode of the semiconductor device may include: after picking up the molten conductive material (solid metal) on the top table of the boss structure, cooling it, the molten conductive material (solid metal) may be hardened and conformed by standing it at room temperature, or by accelerated cooling and hardening at low temperature to obtain an electrode.

[0075] Specifically, in order to achieve electrical isolation of the boss structure during the crimping packaging process, there is a thickness difference between the top table of the boss structure and a portion of the first surface of the semiconductor substrate excluding the boss structure, and the thickness difference may be greater than 25 µm.

[0076] In some optional implementations, the semiconductor device is an IGCT device, and the top mesa of the boss structure is a cathode mesa of the IGCT device.

[0077] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0078] The technical solution of the present application is applied to a method for preparing an electrode of a semiconductor device, including: providing a semiconductor substrate and a donor substrate, wherein the semiconductor substrate has a first surface, a boss structure is provided in the first surface, and the donor substrate has a second surface; forming a transfer film on the second surface, wherein the material of the transfer film includes a conductive material; laminating the transfer film with the top table of the boss structure; separating the semiconductor substrate from the donor substrate by a transfer technique, so that the top table picks up the conductive material laminating with the top table in the transfer film, wherein the transfer technique realizes the picking up by controlling the peeling speed; and curing the conductive material on the top table to obtain an electrode of the semiconductor device. Through the present application, the boss structure is laminating and separating the transfer film formed on the second surface of the donor substrate by a transfer technique, so that the conductive material can automatically align with the boss structure, thereby achieving the purpose of picking up the conductive material by a stamp-type self-alignment technique, and avoiding the lithography and etching problems such as light scattering at the boss due to the structural particularity of the boss structure of the semiconductor substrate and low exposure uniformity and CD uniformity caused by uneven glue thickness, thereby obtaining an electrode (table electrode) with higher uniformity. In summary, the present application solves the problem of low uniformity of mesa electrode patterning of semiconductor devices in the prior art.

[0079] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an electrode of a semiconductor device, characterized in that: include: Providing a semiconductor base and a donor substrate, wherein the semiconductor base has a first surface having a boss structure, and the donor substrate has a second surface; forming a transfer film on the second surface, wherein the material of the transfer film includes a conductive material; Laminating the transfer film to the top surface of the boss structure; Separating the semiconductor base from the donor substrate by using a transfer technique, so that the top table picks up the conductive material in the transfer film that is in contact with the top table, wherein the transfer technique achieves the picking up by controlling the peeling speed; The conductive material on the top terrace is cured to obtain an electrode of the semiconductor device.

2. The electrode preparation method according to claim 1, characterized in that: The conductive material is liquid metal, and a transfer film is formed on the second surface, including: Dissolving liquid metal and polymer matrix material to prepare a composite conductive slurry, wherein the polymer matrix material includes nanoclay or hydrogel; The composite conductive paste is coated on the second surface to form the transfer film.

3. The electrode preparation method according to claim 2, characterized in that: The electrode preparation method further comprises: Before the step of laminating the transfer film to the top mesa of the boss structure, an interface modification layer is formed on the first surface, and the material of the interface modification layer has hydrogen bonds.

4. The electrode preparation method according to claim 1, characterized in that: The conductive material is solid metal, and a transfer film is formed on the second surface, including: The solid metal is deposited on the second surface by using a thin film deposition technique to form the transfer film.

5. The electrode preparation method according to claim 1, characterized in that: The conductive material is solid metal, the transfer film is laminated to the top table of the boss structure to obtain a laminated structure, and the electrode preparation method further includes: The bonded structure is subjected to heat treatment, wherein the temperature of the heat treatment is higher than the melting point of the solid metal.

6. The electrode preparation method according to claim 1, characterized in that: Laminating the transfer film to the top surface of the boss structure, comprising: Transferring the semiconductor substrate to a surface of the transfer film facing away from the donor substrate; Pressure is applied to the semiconductor substrate to make the transfer film fit with the top surface of the boss structure.

7. The electrode preparation method according to claim 6, characterized in that: In the case where the conductive material is liquid metal, a first pressure is applied to the semiconductor substrate, and the first pressure is 5-10N.

8. The electrode preparation method according to claim 6, characterized in that: When the conductive material is solid metal, a second pressure is applied to the semiconductor substrate, and the second pressure is 50-100N.

9. The electrode preparation method according to claim 1, characterized in that: The semiconductor substrate has a first end and a second end opposite to each other, the direction in which the first end points to the second end is parallel to the first surface, and the semiconductor substrate is separated from the donor substrate by using a transfer technology, comprising: lifting the semiconductor substrate from the first end; The semiconductor substrate and the conductive material in the transfer film that is in contact with the top mesa are peeled off from the donor substrate until the second end is separated from the donor substrate.

10. The electrode preparation method according to claim 9, characterized in that: The semiconductor substrate and the conductive material in the transfer film that is in contact with the top table are peeled off from the donor substrate at a first peeling speed of 10-30 cm / s.

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