Metallization of semiconductor wafer

Abstract

To provide a method for manufacturing a semiconductor wafer and a method for manufacturing a semiconductor wafer by metallizing the semiconductor wafer.SOLUTION: A method includes: i) a step of applying a metal-organic decomposition (MOD) ink composition to a semiconductor wafer to form a precursor layer; and ii) a step of curing the precursor layer. The application in the step i) is performed by inkjet printing. The method for inkjet-printing a MOD ink has low equipment cost, low power consumption, no material waste, and enables on-demand printing, thereby providing easy selective deposition and design flexibility (without requiring etching).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a semiconductor wafer, and more particularly to a method for manufacturing a semiconductor wafer by metallizing the semiconductor wafer.

[0002] During the manufacture of semiconductor devices, it is usually necessary to metallize semiconductor wafers. Metallization schemes typically must meet the following requirements: First, layers deposited directly on the wafer must be bonded to the wafer. Second, the outer surfaces of the metallization structure must be solderable so that the semiconductor device can be attached to a lead frame or the like. Third, the metallization structure itself must be crack-free. In addition, metallization requires effective stress control for the stack to reduce further wafer warpage, and low ohmic contact resistance and excellent adhesion are also important requirements for the metallization process.

[0003] The conventional method for wafer metallization is sputtering / evaporation, where multiple stacked layers such as Ti / Ni / Ag, Al / Ti / NiV / Ag, or Ti / Au are typically used.

[0004] For example, U.S. Pat. No. 4,946,376 discloses a metallization scheme for semiconductor devices comprising a vanadium layer having a thickness of 500 to 3000 Å disposed on the backside of the wafer and a silver layer having a thickness of 10,000 to 20,000 Å disposed on the vanadium layer, the vanadium layer and the silver layer being applied by evaporation or sputtering.

[0005] U.S. Patent No. 6,790,709 (B2) discloses a microelectronic device and a method for manufacturing the same. The microelectronic device comprises a microelectronic die having an active surface, a back surface, and at least one side surface, the microelectronic die having sloped sidewalls and channel sidewalls, and a metallization layer disposed on the back surface and sloped sidewalls of the microelectronic die. The metallization layer can be formed by any method known in the art, including, but not limited to, chemical vapor deposition, sputtering deposition (PVD), electroplating, etc., preferably sputtering deposition.

[0006] US Patent Application Publication No. 2008 / 0083611(A1) discloses a method for improving adhesion between a wafer and a deposited metal film, This method involves bombarding the deposited film with metal ions at temperatures below 200°C, with the energy of the metal ions being high enough to achieve interfacial mixing between the metal atoms and the wafer atoms, and low enough to prevent stress damage to the wafer. The deposited film in this document is produced by sputtering.

[0007] The main drawbacks of the above-mentioned prior art techniques are high equipment cost, low material utilization, and the need for additional hardware (shields / masks) to accommodate wafer size variations (e.g., 200 mm to 300 mm).

[0008] In addition, the prior art also discloses methods of metallization by using printing techniques.

[0009] For example, U.S. Pat. No. 10,763,230 (B2) discloses a method for backside metallization of integrated circuits, comprising forming a wetting layer by inkjet printing a pattern of nanosilver particle conductive ink on a first side of a silicon wafer, and then curing the wetting layer by heating the wafer in an oven to evaporate solvents and other materials in the ink.

[0010] WO 2020 / 094583(A1) discloses a method for producing a semiconductor package at least partially covered with an electromagnetic interference shielding layer, the method including at least the steps of: (i) providing a semiconductor package and an ink composition, the ink composition including at least the following components: a) a compound containing at least one metal precursor and b) at least one organic compound; (ii) applying at least a portion of the ink composition to the semiconductor package to form a precursor layer; and (iii) treating the precursor layer with electromagnetic radiation having a peak wavelength in the range of 100 nm to 1 mm. In this method, the ink composition is applied to the semiconductor package, i.e., epoxy, rather than to the silicon wafer itself, for the purpose of providing an electromagnetic interference shielding layer rather than metallizing the wafer.

[0011] Prior art methods of metallization by printing have several drawbacks, and the adhesion and conductivity of the metallization layer still need further improvement. Summary of the Invention

[0012] The object of the present invention is to overcome the drawbacks of the prior art and to provide a method for manufacturing a semiconductor wafer, in particular a method for manufacturing a semiconductor wafer by metallizing the semiconductor wafer, in which the resulting metallization layer has improved adhesion and conductivity.

[0013] Specifically, the object of the present invention is to provide a method for manufacturing a semiconductor wafer, comprising: i) applying a MOD ink (Metal-Organic Decomposition ink) composition to a semiconductor wafer, thereby forming a precursor layer; ii) curing the precursor layer.

[0014] Another object of the present invention is to provide a semiconductor wafer obtained by the method of the present invention.

[0015] A further object of the present invention is to provide a semiconductor device comprising the semiconductor wafer of the present invention.

[0016] It is yet another object of the present invention to provide a semiconductor wafer precursor comprising: a) a semiconductor wafer; and b) an uncured MOD ink layer. DETAILED DESCRIPTION OF THE INVENTION

[0017] In one aspect, the present invention provides a method for manufacturing a semiconductor wafer, comprising: i) applying a MOD ink composition to a semiconductor wafer, thereby forming a precursor layer; ii) curing the precursor layer.

[0018] The method of the present invention allows for metallization of the back and / or front surfaces of a semiconductor wafer, preferably the back surface. The metal used can be Ag, Ag / Sn, or Au. The thickness of the resulting metallization layer can be determined as desired, for example, from about 100 nm to about 3000 nm, preferably from about 300 nm to about 2000 nm, and particularly preferably from about 300 nm to about 1000 nm. The resulting metallization layer has good electrical and thermal conductivity, and also has good solderability to externally attached materials.

[0019] The semiconductor wafer may be a Si wafer, a SiC wafer, a GaN wafer, a GaAs wafer, or a Ga2O3 wafer, preferably a Si wafer. The semiconductor wafer may be a power electronics wafer or a logic IC wafer.

[0020] Step i) In one embodiment of the present invention, the application in step i) is performed by spraying, spin coating, dip coating or inkjet printing, preferably by inkjet printing.

[0021] Inkjet printing is an additive manufacturing process that reduces material waste and does not require masks or etching steps. Furthermore, inkjet printing can handle large wafers (e.g., 300 mm wafers), thereby reducing the need for expensive metal deposition equipment for such wafers and thus reducing manufacturing costs.

[0022] Inkjet printing can be performed in a patterned manner. Inkjet printing can be performed by any type of inkjet printer, such as a piezoelectric inkjet printer. The number of layers applied by inkjet printing can be one or more layers, preferably 1 to 10 layers, to achieve the desired layer thickness. The layer thickness of inkjet printing can be adjusted by adjusting the printing resolution and the number of layers. The DPI range X / Y of inkjet printing can be 300 to 3000.

[0023] The MOD ink composition used in the present invention comprises a precursor compound of the applied metal and a solvent. To form a film of the applied metal (particularly silver), the organic solvent must be removed so that the metal precursor compound can be converted into a solid structure by a decomposition reaction.

[0024] However, during solvent removal, bubbles can form internally or on the surface, especially if the film is thick, ultimately resulting in a film with high porosity. Therefore, MOD inks have traditionally been considered suitable only for preparing thin films; otherwise, quality issues may arise. Furthermore, metal films prepared with MOD inks are thought to have poorer adhesion to substrates than those prepared by other methods, such as CVD or PVD. The only way to reduce bubble density is to slowly remove the solvent by simply changing the heating rate. Therefore, this method is too slow to be applied in the modern semiconductor industry.

[0025] As a result, MOD inks are currently only used in the semiconductor industry to fabricate circuits (i.e., create conductive paths) on polyimide (PI) or polyethylene terephthalate (PET), for example, in flexible printed circuit (FPC) applications. In these applications, the metal layer should be thin and uniform and should be used in a relatively benign environment. MOD inks are considered unsuitable for other applications, such as backside metallization, where the backside metallization layer should be relatively thick and strong to ensure good bonding to the wafer so that the metallization layer does not peel off when temperatures change significantly or when high current densities are frequently encountered.

[0026] However, it has been surprisingly discovered that when MOD inks are used in the method of the present invention, thick, dense layers with low porosity can be rapidly obtained in a single application and curing cycle by fully curing them in a post-application curing step (called the application and curing cycle). Alternatively, multiple application and curing cycles can be performed, each resulting in a layer thickness of 100 nm to 800 nm, preferably 150 nm to 500 nm, and more preferably 200 nm to 300 nm. Thus, thick, dense layers with low porosity and large grains (up to 1000 nm) can be rapidly obtained. The resulting layers have good adhesion and conductivity, thus enabling the use of MOD inks for backside metallization of wafers, thus overcoming the biases of the prior art. Layers obtained by the method of the present invention using MOD inks have porosities comparable to or less than those of PVD processes.

[0027] One advantage of MOD inks over other inks, such as nanoparticle inks, is their ability to form more uniform, flatter, and denser films. Layers obtained with inks containing metal nanoparticles are typically very sparse, i.e., have high porosity. In contrast, layers obtained by the methods of the present invention using MOD inks have much lower porosity. Unlike nanoparticle inks, MOD inks are solutions rather than mixtures (suspensions), do not settle over time, and present fewer problems during application (e.g., less likelihood of clogging nozzles). The viscosity of MOD inks can be easily adjusted to control sprayability and annealing temperature. Additionally, MOD inks are environmentally friendly, do not contain nanoparticles, are more readily available, and ultimately may be less expensive than nanoparticle inks.

[0028] The MOD ink composition used in the present invention comprises the following components: a) at least one metal precursor; and b) a solvent.

[0029] The metal in the MOD ink composition is Ag, Ag / Sn, or Au.

[0030] The metal precursor has a decomposition temperature of 80°C to 500°C, for example, 80°C to 500°C, or 150°C to 500°C, or 180°C to 350°C, or 150°C to 300°C, or 180°C to 270°C.

[0031] The metal precursor is a) at least one metal cation; b) at least one anion selected from the group consisting of carboxylate, carbamate, nitrate, and halide ions, and an oxime.

[0032] Combinations of two or more metal precursors may be used, with the same metal cation but the same or different anions, or different metal cations but the same anions, such as a silver carboxylate and a tin carboxylate, two different silver carboxylates, and a silver carboxylate and a silver carbamate.

[0033] Carboxylate salts are salts of one or more metal cations and one or more carboxylate anions. The carboxylic acid portion of the carboxylate anion may be linear, branched, or have a cyclic structural unit, and may be saturated or unsaturated. More preferred types of carboxylates are monocarboxylates and dicarboxylates, or cyclic carboxylates. In one embodiment, linear saturated carboxylates, such as carboxylates having 1 to 20 carbon atoms, are preferred. The linear carboxylates may be selected from the group consisting of acetate, propionate, butyrate, valerate, hexanoate, heptanoate, octanoate, nonanoate, decanoate, undecanoate, dodecanoate, tetradecanoate, hexadecanoate, or octadecanoate. In another embodiment, saturated isocarboxylates and saturated neocarboxylates having 1 to 20 carbon atoms may be used. In one embodiment, saturated neocarboxylates having 5 or more carbon atoms are preferred, such as neopentanoate, neohexanoate, neoheptanoate, neooctanoate, neononanoate, neodecanoate, and neododecanoate.

[0034] The halide ions are selected from the group consisting of fluoride ions, chloride ions, bromide ions, and iodide ions.

[0035] The metal content of the MOD ink composition is from about 1% to about 60% by weight, e.g., from about 1% to about 50% by weight, or from about 10% to about 40% by weight, calculated as metal, based on the total weight of the ink composition, as typically determined by thermogravimetric analysis (TGA).

[0036] The MOD ink composition further comprises a solvent, which in each case comprises from about 0.1% to about 90% by weight, and preferably from about 20% to about 90% by weight, based on the total weight of the MOD ink composition.

[0037] The solvent may be selected from the group consisting of glycol ethers, terpenes, aliphatic hydrocarbons, aromatic hydrocarbons, ketones, aldehydes, or combinations thereof.

[0038] Glycol ethers are organic substances containing at least one diol unit. Examples of glycol ethers include ethylene glycol ether, diethylene glycol ether, triethylene glycol ether, tetraethylene glycol ether, propylene glycol ether, and dipropylene glycol ether. Commercially available examples include DOWANOL PNP (propylene glycol n-propyl ether), DOWANOL PNB (propylene glycol n-butyl ether), DOWANOL DPNB (dipropylene glycol n-butyl ether), and DOWANOL DPNP (dipropylene glycol n-propyl ether).

[0039] Terpenes are naturally occurring unsaturated hydrocarbons, which can be isolated from natural materials, and their structures can be traced to one or more isoprene units.Some terpenes are also available industrially and artificially.Terpenes are preferably acyclic or cyclic terpenes.Among cyclic terpenes, monocyclic terpenes are preferred.Preferably, terpenes are selected from orange terpenes, limonene, and pinene, or combinations thereof.

[0040] Other suitable solvents, such as aliphatic hydrocarbons, aromatic hydrocarbons, ketones, and aldehydes, are well known in the art.

[0041] The MOD ink composition may optionally include one or more other ingredients, such as adhesion promoters, viscosity aids, and other additives.

[0042] In one embodiment, the MOD ink composition may include an adhesion promoter, and preferably the adhesion promoter may be present in an amount of from about 0.1% to about 5% by weight, based on the total weight of the MOD ink composition.

[0043] In one embodiment, the MOD ink composition may include one or more viscosity aids in a weight ratio of from about 5% to about 30% by weight, more preferably from about 10% to about 20% by weight, based on the total weight of the ink composition.

[0044] Rosin resins or derivatives thereof are suitable viscosity aids for ink compositions. A particularly preferred commercial product is balsam resin available from H. Reynaud & Fils GmbH, Hamburg.

[0045] In one embodiment, the MOD ink composition may contain other additives in an amount of from about 0.05% to about 3% by weight, more preferably from about 0.05% to about 1% by weight, based on the total weight of the ink composition. All chemicals known to those skilled in the art to be suitable as ink additives can be used as other additives. Particularly preferred are siloxane-containing additives, such as polyether-modified polydimethylsiloxanes.

[0046] In one embodiment, the MOD ink composition comprises less than 1 wt. %, or less than 0.5 wt. %, or less than 0.2 wt. % metal particles, based on the total weight of the MOD ink composition. Most preferably, the compositions of the present invention are substantially free of metal particles.

[0047] The MOD ink composition may have a viscosity suitable for application, such as an ink composition having a viscosity of about 0.1 to about 100 mPa·s, for example, about 5 to about 30 mPa·s, measured at a temperature of 20° C. and an ambient pressure of 1013 hPa.

[0048] The components in the MOD ink composition can be mixed by any method known to those skilled in the art and deemed suitable. Mixing can be performed at a slightly elevated temperature to facilitate the mixing process. Typically, the temperature during mixing does not exceed 40°C. The ink composition can be stored at room temperature or in a refrigerator.

[0049] Step ii) In step ii) the precursor layer obtained in step i) is cured, during which the solvent in the wet layer evaporates, inducing nucleation within the layer.

[0050] Since metallic Ag, Ag / Sn, or Au in the MOD ink used in step i) is not easily oxidized, curing can be carried out in air. Of course, curing can also be carried out under an inert atmosphere. Examples of inert atmospheres include, but are not limited to, nitrogen, helium, argon, and neon.

[0051] The curing in step ii) may be carried out by heating and / or electromagnetic radiation. In one embodiment of the present invention, the heating and electromagnetic radiation may be carried out simultaneously, or heating may be followed by electromagnetic radiation, or electromagnetic radiation may be followed by heating.

[0052] When curing is carried out by heating, this may be carried out in an oven. The heating temperature may be about 50°C to about 250°C, preferably about 80°C to about 200°C, and more preferably about 150°C to about 200°C, and the heating time may be about 1 to about 60 minutes, preferably about 5 to about 40 minutes.

[0053] When curing is carried out by electromagnetic radiation, electromagnetic radiation having a wavelength of about 100 nm to about 1 mm, preferably about 100 nm to about 2000 nm, more preferably about 100 nm to about 800 nm may be used. The radiation intensity is about 100 W / cm. 2 ~Approx. 1000W / cm 2 , preferably about 100 W / cm 2 ~about 500W / cm 2 , more preferably about 100 W / cm 2 ~about 400W / cm 2 The radiation speed may be about 0.01 mm / sec to about 1000 mm / sec, preferably about 0.1 mm / sec to about 500 mm / sec, and more preferably about 0.1 mm / sec to about 50 mm / sec. Radiation may be carried out 1 to 100 times, preferably 1 to 50 times.

[0054] In one embodiment of the present invention, a cycle including steps i) and ii) is performed one or more times, and in each cycle, step i) is performed one or more times and step ii) is performed one or more times. For example, the cycle may be performed 1 to 10 times, preferably 1 to 5 times, and more preferably 1 to 3 times, and in each cycle, step i) is performed 1 to 10 times, preferably 1 to 5 times, and more preferably 1 to 3 times, and step ii) is performed 1 to 10 times, preferably 1 to 5 times, and more preferably 1 to 3 times.

[0055] If multiple cycles are performed, a layer having a thickness of 100 nm to 800 nm, preferably 150 nm to 500 nm, more preferably 200 nm to 300 nm is formed in each cycle.

[0056] Other steps The method of the present invention may further comprise step iii), ie annealing the layer obtained in step ii).

[0057] The annealing temperature is related to the melting point of the metal, with higher annealing temperatures being used for metals with higher melting points. The annealing temperature may be from about 120°C to about 500°C, preferably from about 150°C to about 460°C. The annealing time is also related to the melting point of the metal, with longer annealing times being used for metals with higher melting points. The annealing time may be from about 1 to about 60 minutes, preferably from about 5 to about 40 minutes, and more preferably from about 5 to about 30 minutes.

[0058] Since the metallic Ag, Ag / Sn, or Au in the MOD ink used in step i) is not easily oxidized, annealing can be performed in air. Of course, annealing can also be performed under an inert atmosphere. Examples of inert atmospheres include, but are not limited to, nitrogen, helium, argon, and neon.

[0059] Annealing can be carried out in any suitable apparatus, for example, a tube furnace.

[0060] The method of the present invention may also include other steps, such as cleaning the semiconductor wafer.

[0061] In one embodiment of the present invention, a semiconductor wafer may be cleaned to remove any possible oxides on the surface before each layer (e.g., a MOD ink composition layer) is applied to the semiconductor wafer, or before each layer (e.g., a MOD ink composition layer) is applied to another layer already present on the semiconductor wafer. The presence of oxides can increase contact resistance and affect adhesion, which can in turn affect product performance. Additionally, cleaning can remove residual contaminants from the surface, as well as strengthening film adhesion by activating chemical bonds on the surface. Alternatively, the oxide layer on the surface can be retained during the cleaning process.

[0062] Cleaning methods may include plasma cleaning and chemical cleaning. Preferably, cleaning is performed using plasma. Examples of plasma cleaning may include Ar plasma cleaning, air plasma cleaning, or vacuum plasma cleaning. The time for plasma cleaning may be about 1 to about 60 minutes, preferably about 1 to about 10 minutes. Suitable chemical cleaning methods are well known in the art.

[0063] After cleaning the semiconductor wafer, a base layer can be applied to the semiconductor wafer. A suitable base layer can be an adhesion layer and a barrier layer, with the adhesion layer in direct contact with the silicon wafer surface and the barrier layer disposed on top of the adhesion layer to prevent oxidation of the adhesion layer and to prevent interdiffusion between the adhesion layer and the subsequent Ag, Ag / Sn, or Au layer (as described above). Of course, a layer having both adhesion and barrier functions can also be applied.

[0064] Specifically, the method of the present invention comprises the following steps, which are carried out before step i): 1) forming an adhesion layer and a barrier layer on a semiconductor wafer; or 2) forming a layer having both adhesive and barrier functions on the semiconductor wafer.

[0065] Surprisingly, it has been found that wafers provided with a layer having both adhesive and barrier functions and an Ag, Ag / Sn, or Au layer have excellent thermal and electrical conductivity.

[0066] The application of the base layer may be carried out by chemical vapor deposition, sputter deposition, electroplating, spraying, spin coating, dip coating, or inkjet printing, preferably by inkjet printing. When spraying, spin coating, dip coating, or inkjet printing is used, preferably a MOD ink composition containing a precursor of the metal to be applied is also used. The MOD ink composition used is such as that described above for the Ag, Ag / Sn, or Au layer, the difference being that the metal used is that used for the base layer.

[0067] The inkjet printing of the base layer can also be performed in a patterned manner. The inkjet printing is performed by an inkjet printer, preferably a piezoelectric inkjet printer. The number of layers applied by inkjet printing can be one or more layers, preferably 1 to 10 layers. The layer thickness of the inkjet printing can be adjusted by adjusting the printing resolution and the number of layers. The DPI range X / Y of the inkjet printing can be 300 to 3000.

[0068] After application of the base layer, the resulting base layer may be cured and annealed as described above. In the present invention, the curing and annealing processes are sometimes collectively referred to as "post-treatments."

[0069] When applying adhesive and barrier layers to a semiconductor wafer, this can be done by (i) applying one or more adhesive layers, curing and / or annealing the adhesive layers, then applying one or more barrier layers, and curing and / or annealing the barrier layers, or (ii) applying one or more adhesive layers, then applying one or more barrier layers, and then curing and / or annealing the resulting composite layers together. In case (i), when multiple adhesive layers are applied, it is possible to apply each adhesive layer, then cure and / or anneal that layer, then apply the next adhesive layer, then cure and / or anneal the next adhesive layer, and so on, until the desired thickness is achieved. After multiple adhesive layers are applied, it is also possible to cure and / or anneal all of the applied adhesive layers together. Similarly, in case (i), when multiple barrier layers are applied, each barrier layer can be applied, then cured and / or annealed, then the next barrier layer, then the next barrier layer, etc., until the desired thickness is achieved. After multiple barrier layers have been applied, all of the applied barrier layers can be cured and / or annealed together.

[0070] Curing is carried out by electromagnetic radiation and / or heating. When curing is carried out by heating, the heating temperature is about 50°C to about 250°C, preferably about 80°C to about 200°C, more preferably about 150°C to about 200°C, and the heating time is about 1 to about 60 minutes, preferably about 5 to about 40 minutes. When curing is carried out by electromagnetic radiation, electromagnetic radiation having a wavelength of about 100 nm to about 1 mm, preferably about 1000 nm to about 2000 nm, more preferably about 100 nm to about 800 nm may be used. For curing of the adhesive layer and the barrier layer, the radiation intensity is about 1 W / cm. 2 ~about 100W / cm 2 , preferably about 10 W / cm 2 ~about 50W / cm 2 The radiation speed may be about 0.01 mm / sec to about 1000 mm / sec, preferably about 0.1 mm / sec to about 500 mm / sec, and more preferably about 0.1 mm / sec to about 50 mm / sec. Radiation may be carried out 1 to about 100 times, preferably 1 to about 50 times.

[0071] If the metal in the MOD ink used for the base layer is easily oxidized, such as Ti and Ni, it tends to convert to its oxide during curing, so annealing in an inert atmosphere is necessary to prevent oxidation of the metal. If the metal in the MOD ink used for the base layer is not easily oxidized, such as Pt, Ag, and Au, curing can be carried out in air. Of course, curing in an inert atmosphere is also possible. Examples of inert atmospheres include, but are not limited to, nitrogen, helium, argon, and neon.

[0072] The annealing temperature may be about 120°C to about 500°C, preferably about 150°C to about 460°C. The annealing time is also related to the melting point of the metal, with longer annealing times being used for metals with higher melting points. The annealing time may be about 1 to about 60 minutes, preferably about 5 to about 40 minutes, and more preferably about 5 to about 30 minutes. As mentioned above, depending on the metal used, annealing of the base layer may be carried out in a reducing or inert atmosphere.

[0073] The base layer can also be applied by PVD techniques, with specific PVD process conditions being well known in the art.

[0074] The metal used for the adhesion layer may be titanium (Ti), bismuth (Bi), tin (Sn), aluminum (Al), chromium (Cr), vanadium (V), yttrium (Y), cerium (Ce), silicon (Si), tin (Sn), zinc (Zn), or a mixture thereof. The metal used for the barrier layer may be nickel (Ni), vanadium (Vi), chromium (Cr), or a mixture thereof, such as nickel-vanadium (NiV). For layers having both adhesion and barrier functions, preferred metals are bismuth (Bi), nickel-vanadium (NiV), or tungsten (W), more preferably Bi.

[0075] The thickness of the adhesive layer may be 50 nm to 500 nm, preferably 50 nm to 100 nm. The thickness of the barrier layer may be 100 nm to 500 nm, preferably 100 nm to 200 nm. The thickness of the layer having both adhesive and barrier functions may be 30 nm to 500 nm, preferably 50 nm to 100 nm.

[0076] It should be noted that although in the context of the present invention, the adhesive layer and the barrier layer are clearly defined, in an actual manufacturing process, the adhesive layer and the barrier layer may fuse at the interface to form an interfacial layer.

[0077] Method embodiments of the present invention Figure 1 shows (i) combining MOD (metal precursor + solvent); (ii) inkjet printing a wetting layer on the backside of the wafer using MOD ink loaded in a piezoelectric press, where the layer thickness can be adjusted by adjusting the printing resolution and the number of layers; (iii) curing the wet printed layer by electromagnetic radiation to evaporate the solvent and cause nucleation; (iv) annealing the cured layer in a tubular oven; Steps (ii) and (iii) together represent one embodiment of the method of the present invention, which can be performed one or more times to obtain the desired layer thickness.

[0078] In a preferred embodiment, the present invention is a method for manufacturing a semiconductor wafer, comprising the steps of: 1) plasma cleaning the wafer; 2) inkjet printing an adhesive layer; 3) post-treating the adhesive layer; 4) inkjet printing a barrier layer; 5) post-treating the barrier layer; 6) inkjet printing a layer of Ag, Ag / Sn, or Au; 7) post-treating the silver layer.

[0079] The post-treatment conditions for the adhesive layer / barrier layer are as follows: Curing: Radiation intensity 1W / cm 2 ~100W / cm 2 , wavelength 100nm~1mm, speed 0.1mm / sec~1000mm / sec, 1~100 times, Annealing: 120℃~500℃ for 1~30 minutes.

[0080] The post-treatment conditions for the Ag, Ag / Sn, or Au layer are as follows: Curing: radiation intensity 100W / cm 2 ~1000W / cm 2 , wavelength 100nm~1mm, speed 0.1mm / sec~100mm / sec, 1~100 times, Annealing: 120℃~500℃ for 1~30 minutes.

[0081] Advantages of the method of the present invention The present invention utilizes MOD inks to deposit different thin film layers onto the backside of silicon wafers for wafer metallization applications in semiconductor devices, thereby saving on equipment costs and reducing material waste. In particular, preferred embodiments of the present invention use inkjet printing to apply the MOD inks, which allows for the production of films using industrial-scale piezoelectric inkjet presses, an additive manufacturing process with the following key advantages: 1. Low equipment cost and low power consumption (no vacuum required). 2. No waste of materials. 3. On-demand printing facilitates selective deposition / design flexibility (no etching required).

[0082] Wafers obtained by inkjet printing of MOD inks and post-processing according to the present invention have a different layer microstructure compared to layers produced by PVD or nanoparticle inks. Prior art PVD produces very dense layers, while the use of prior art inks containing nanometal particles typically produces layers with small agglomerates and high porosity. In contrast, the MOD layers of the present invention have a dense structure containing large crystal grains after annealing, and the shape of each layer can be easily controlled by adjusting the post-processing conditions. This results in excellent conductivity of the Ag, Ag / Sn, or Au layers of the present invention. In particular, the conductivity of the Ag, Ag / Sn, or Au layers obtained by the present method is higher than that of layers obtained using prior art nanometal inks and comparable to that of layers obtained using prior art PVD methods.

[0083] Other aspects of the invention In another aspect of the present invention, there is provided a semiconductor wafer obtainable by the method of the present invention.

[0084] In yet another aspect of the present invention, a semiconductor device is provided comprising the semiconductor wafer of the present invention.

[0085] In a further aspect of the present invention, there is provided a semiconductor wafer precursor comprising: a) a semiconductor wafer; and b) an uncured MOD ink layer. [Brief explanation of the drawings]

[0086] [Figure 1] 1 shows a schematic diagram of the method of the present invention. [Figure 2] 1 shows an electron microscope image of a cross section of the bismuth oxide / silver stack of Example 2. [Example]

[0087] The purpose of the following examples is to further illustrate the present invention, but not to limit the scope of the invention.

[0088] Test Method Square Resistivity A four-point probe obtained from Ossila (Sheffield, UK) was used to measure the square resistivity of the layers obtained by the method of the present invention.

[0089] Peel test The adhesion of the metallization layer to the wafer was characterized by a peel test, the peel test standard being ASTM D3359-09.

[0090] Example 1 In this example, the Ti / Ni layer as the adhesion layer and barrier layer was performed using PVD (obtained from Shanghai Yuquan Trading Co., Ltd.), and the silver layer was formed by inkjet printing using MOD ink, with the following parameters for each layer: Adhesive layer: Ti, 50nm Barrier layer: Ni, 100nm Silver layer: Ag, 300nm

[0091] The process flow was as follows: Clean with Ar plasma for 1.5 minutes. 2. PVD Ti to a thickness of 50 nm. 3. PVD Ni to a thickness of 100 nm. 4. Using a Heraeus inkjet printer, printhead model: RICOH MH5421F, inkjet printing was performed in one layer at 1200 x 1600 DPI using MOD silver ink. The MOD silver ink consisted of 15 wt% silver neodecanoate and 85 wt% limonene (DL-limonene, CAS number 138-86-3, available from Merck KGaA, catalog number 814546), each based on the total weight of the ink. 5. Cure the silver ink layer using a Heraeus UV curing device Heraeus Semray 4103 (wavelength: 395 nm, speed: 1 mm / sec, 1 pass, radiation intensity: 250 W / cm 2 ). 6. Anneal by using SG-XL1200 annealing machine under different conditions shown in the table below.

[0092] The resulting metallization layer was tested and the results are shown in the table below. [Table 1]

[0093] The adhesion performance of the entire metallization layer (Ti+Ni+Ag layer) on the wafer was tested and good results were obtained, passing 4B / 5B, with a square resistance of the Ag layer of about 64 mΩ / sq. There was essentially no difference in peel test and square resistance under different annealing conditions.

[0094] Example 2 In this example, MOD ink was used and all layers were applied by inkjet printing. The parameters for each layer were as follows: Printed layer with both adhesive and barrier functions: bismuth oxide, 60 nm, and Printed silver layer: Ag, 590nm.

[0095] The process flow was as follows: 1. Inkjet printing of adhesive and barrier layers: Using a Heraeus inkjet printer, printhead model: RICOH MH5421F, MOD bismuth ink, DPI: 564 x 564, 1 layer. The MOD bismuth ink was composed of 15 wt% bismuth neodecanoate and 85 wt% Dowanol PNP (propylene glycol n-propyl ether, CAS number 1569-01-3, obtained from The Dow Chemical Company, Inc., Maryland, USA), based on the total weight of the ink. 2. Using SG-XL1200 annealing machine, dry at 100°C for 10 minutes and anneal at 450°C for 10 minutes. 3. Using a Heraeus inkjet printer equipped with a RICOH MH5421F inkjet printhead model, MOD silver ink was printed in three layers at 1270 x 1270 DPI. The MOD silver ink consisted of 15 wt% silver neodecanoate and 85 wt% limonene (DL-limonene, CAS number 138-86-3, available from Merck KGaA, catalog number 814546), each based on the total weight of the ink. 4. Dry at 100°C for 10 minutes and anneal at 450°C for 10 minutes using SG-XL1200 annealing machine.

[0096] The adhesion performance of the entire metallization layer (bismuth oxide + silver layer) on the wafer was tested and showed good results, passing 5B, with a square resistance of the Ag layer of about 42 mΩ / sq.

[0097] Figure 2 shows an electron microscope image of the cross section of the bismuth oxide / silver stack layer of this example, which shows that the bismuth oxide layer had good contact with the substrate, just as the silver layer had good contact with the bismuth oxide layer, and the film structure was very dense with low porosity.

Claims

1. A method for manufacturing a semiconductor wafer, comprising: i) applying a MOD ink composition to a semiconductor wafer, thereby forming a precursor layer; ii) curing the precursor layer.

2. 2. The method according to claim 1, wherein said applying in step i) is carried out by spraying, spin coating, dip coating or inkjet printing, preferably by inkjet printing.

3. 3. The method of claim 1, wherein the cycle comprising steps i) and ii) is carried out one or more times, and in each cycle, step i) is carried out one or more times and step ii) is carried out one or more times.

4. The method according to claim 3, wherein when multiple cycles are performed, a layer having a thickness of 100 nm to 800 nm, preferably 150 nm to 500 nm, more preferably 200 nm to 300 nm is formed in each cycle.

5. The method according to any one of claims 1 to 4, wherein the curing in step ii) is carried out by means of electromagnetic radiation and / or heat.

6. Radiation intensity is 100 W / cm ２ ~1000 W / cm ２ , preferably 100 W / cm ２ ~500 W / cm ２ , more preferably 100 W / cm ２ ~400 W / cm ２ and the radiation wavelength is from 100 nm to 1 mm, preferably from 100 nm to 2000 nm, more preferably from 100 nm to 800 nm.

7. The method according to claim 5, wherein the heating temperature is from 50°C to 500°C, preferably from 80°C to 400°C, more preferably from about 150°C to 300°C.

8. The method according to any one of claims 1 to 7, further comprising the step of iii) annealing the layer obtained after curing.

9. 9. The method of claim 8, wherein the annealing in step iii) is carried out at a temperature between 120°C and 500°C.

10. The method according to any one of claims 1 to 9, wherein the method metallizes the backside and / or the front side of the semiconductor wafer, preferably the backside.

11. The semiconductor wafer is a Si wafer, a SiC wafer, a GaN wafer, a GaAs wafer, or a Ga ２ O ３ The method according to any one of claims 1 to 10, wherein the wafer is preferably a Si wafer.

12. The method according to any one of claims 1 to 10, wherein the semiconductor wafer is a power electronics wafer or a logic IC wafer.

13. The method of any one of claims 1 to 12, wherein the MOD ink composition comprises: a) at least one metal precursor; and b) a solvent.

14. The method of claim 13, wherein the metal precursor has a decomposition temperature of 80°C to 500°C.

15. The method of claim 13 or 14, wherein the metal in the MOD ink composition is Ag, Ag / Sn, or Au.

16. The metal precursor a) at least one metal cation; b) at least one anion selected from the group consisting of carboxylate, carbamate, nitrate, and halide ions, and an oxime.

17. The method further comprises the steps, which are carried out before step i): 1) forming an adhesion layer and a barrier layer on the semiconductor wafer; or 2) The method according to any one of claims 1 to 16, further comprising the step of forming a layer having both adhesive and barrier functions on the semiconductor wafer.

18. 18. The method according to claim 17, wherein said forming of said layer in steps 1) and 2) is carried out by chemical vapor deposition, sputter deposition, electroplating, spraying, spin coating, dip coating or inkjet printing, preferably by inkjet printing.

19. 20. The method of claim 18, wherein when the forming of the layer is carried out by spraying, spin coating, dip coating, or inkjet printing, the ink used is a MOD ink composition.

20. 2), the method of claim 19, wherein the MOD ink composition is a bismuth-containing MOD ink composition.

21. 21. The method of claim 19 or 20, wherein after forming each layer of step 1) or 2), the resulting wafer is cured and / or annealed.

22. A semiconductor wafer obtainable by the method according to any one of claims 1 to 21.

23. A semiconductor device comprising the semiconductor wafer of claim 22.

24. a) a semiconductor wafer; b) an uncured layer of a MOD ink composition.

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