TW202236407A - A method for back grinding a wafer and a method for manufacturing an electronic device - Google Patents

Abstract

An object of the present invention is to provide a method for back grinding a wafer capable of suppressing the influence of surface unevenness of the wafer on back grinding and improving operability of the wafer after thinning. A solution to such object is a method for back grinding a wafer having unevenness on a surface, which has the following steps prior to the back grinding of the wafer: step (1) of forming a protective layer on the surface of the wafer; step (2) of planarizing a surface of the protective layer not in contact with the wafer; and step (3) of adhering the surface of the protective layer not in contact with the wafer to a support body via an adhesive layer.

Description

Wafer back grinding method and electronic device manufacturing method

The present invention relates to a back grinding method of a wafer in a method of thinning a wafer having uneven surface, and more specifically, to a back grinding method of a wafer, which protects the wafer with a protective layer After the surface of the wafer is flattened by flattening the surface of the protective layer that is not in contact with the wafer, the influence of the unevenness of the wafer surface can be suppressed, and the operation can be improved in various processing processes after wafer thinning sex.

In order to highly integrate semiconductor devices or to manufacture high-performance semiconductor devices, back grinding is widely performed to grind wafers on which circuits are formed to have a uniform thickness and fine thickness. However, in the manufacturing steps of electronic devices such as semiconductor devices, circuits, etc. may be formed on the surface of semiconductor wafers such as silicon or gallium-arsenic in the so-called pre-step, or due to bump electrodes, etc., there may be The surface of the circle has unevenness. Among such electronic devices, in particular, power devices used in power converters such as inverters and converters have irregularities on the wafer surface due to their characteristics, structure, and manufacturing steps. In the so-called subsequent steps, if a protective layer such as a protective adhesive tape is made and the backside is ground directly, the unevenness on the wafer surface will be transferred to the backside of the wafer, and the unevenness will be reflected on the finished product of the wafer Thickness, especially in electrical devices, affects device characteristics.

As for the back grinding method of the wafer to suppress the influence of the unevenness of the wafer surface, after the wafer is supported by an adhesive tape, the base material of the tape is flattened by a planer, so that the back grinding of the wafer is known. A method for uniformizing the thickness of finished products (Patent Document 1). However, although this method can suppress the variation in the thickness of the finished wafer, it still has the problem of difficulty in handling such as transportability of the thinned wafer.

On the other hand, as a method of improving the handling properties of a thinned wafer, there is known a method of temporarily fixing the wafer and the support substrate with a protective layer to facilitate handling (Patent Document 2) . However, in this method, due to the unevenness of the surface of the wafer, etc., the unevenness in the finished thickness of the wafer may not be sufficiently suppressed due to uneven application of the protective layer.

[Prior Art Literature]

[Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2009-43931

[Patent Document 2] Japanese Unexamined Patent Publication No. 2004-64040

In view of the above technical background, the purpose of the present invention is to provide a wafer back grinding method, which can suppress the impact of the unevenness of the wafer surface and improve the operability of the wafer after thinning.

As a result of intensive research, the present inventors have found that after the surface of the wafer is protected with a protective layer before the back grinding of the wafer, the surface of the protective layer that is not in contact with the wafer is flattened and bonded The above problems can be solved by attaching the surface of the planarized protective layer that is not in contact with the wafer to the support, and finally completed the present invention.

That is, the present invention relates to the following:

[1] A wafer back grinding method is a method of back grinding a wafer having unevenness on the surface, and the back grinding method comprises the following steps before the back grinding of the wafer:

Step (1), forming a protective layer on the surface of the aforementioned wafer;

Step (2) is to planarize the surface of the aforementioned protective layer that is not in contact with the wafer; and,

In step (3), the surface of the protective layer that is not in contact with the wafer is bonded to the support through an adhesive layer.

Hereinafter, any one of [2] to [15] is a preferred aspect or an embodiment of the present invention.

[2] The wafer back grinding method according to [1], wherein the protective layer is a protective adhesive tape.

[3] The wafer back grinding method according to [2], wherein the base material layer of the protective adhesive tape contains a compound selected from the group consisting of PET, PEN, PBT, LCP, PI, PA, PEEK, and PPS. At least one resin from the group.

[4] The wafer back grinding method according to any one of [1] to [3], wherein the wafer having irregularities on the surface is formed by electrodes formed on the surface, circuit patterns, polyimide A wafer having concavo-convex at least one of the defective marks or the bumps.

[5] The wafer back grinding method according to any one of [1] to [4], wherein the planarization step is a step of planarization by cutting, grinding, or polishing.

[6] The wafer back grinding method according to [5], wherein the cutting is performed by cutting with a bit.

[7] The wafer back grinding method according to any one of [1] to [6], wherein the adhesive layer is a liquid adhesive or an adhesive tape.

[8] The wafer back grinding method according to any one of [1] to [7], wherein the support body is made of glass, silicon, ceramics, metal, resin, or a composite material thereof.

[9] The wafer back grinding method according to any one of [1] to [8], wherein after the aforementioned step (2) and before the aforementioned step (3), the following steps are included: The surface of the aforementioned protective layer that is not in contact with the wafer, the surface of the aforementioned support body, or both thereof are used to form the aforementioned adhesive layer.

[10] The wafer backside grinding method according to any one of [1] to [9], further comprising a backside treatment step of the wafer after the backside grinding of the wafer.

[11] The wafer back grinding method according to [10], wherein the wafer back processing step includes at least one of etching, electrode formation, ion implantation, and annealing.

[12] The wafer back grinding method according to any one of [1] to [11], wherein the thickness of the wafer after back grinding is 200 μm or less.

[13] A method of manufacturing an electronic device, comprising, in the manufacturing step, the method of backgrinding the wafer according to any one of [1] to [12].

[14] The method of manufacturing an electronic device according to [13], wherein the electronic device is a device that also includes electrodes on the back side.

[15] The method of manufacturing an electronic device according to [14], wherein the electronic device is an electric device.

According to the wafer back grinding method of the present invention, when the wafer is ground back, the impact of the unevenness of the wafer surface can be suppressed, and the operability after wafer thinning can be improved. In this processing process, wafers can be stably processed, so it is possible to prevent damage to circuits formed on wafers, and to suppress The characteristics of electronic devices such as semiconductor devices are unexpectedly affected, and many and/or various steps are performed on wafers with high productivity and yield, which greatly contributes to electronic devices such as semiconductor devices productivity improvement.

1: Semiconductor wafer, wafer

3: Protective adhesive tape

4: Adhesive layer

5: Support body

11: Wafer surface, surface

12: The back side of the wafer, the back side

31: Protect the substrate layer and substrate layer of the adhesive tape

32: Adhesive layer of protective adhesive tape

33: Substrate layer and substrate layer of planarized protective adhesive tape

FIG. 1 is a schematic diagram illustrating the steps of an embodiment of the present invention. (a) represents the wafer 1 with the back surface 12 ground by the present invention. (b) represents the wafer 1 with the protective adhesive tape 3 attached to the surface 11 of the wafer 1 by using the protective adhesive tape 3 as a protective layer through step (1). (c) represents the wafer 1 in which the base material layer 31 of the protective adhesive tape 3 is planarized by the step (2). (d) represents the wafer 1 in which the adhesive layer 4 is formed from the planarized substrate layer 33 of the protective adhesive tape 3 obtained in step (2). (e) shows the wafer 1 to which the support body 5 and the protective adhesive tape 3 were planarized through the adhesive layer 4 in step (3) and the base material layer 33 was bonded.

The back grinding method of the wafer of the present invention is a back grinding method of a wafer with unevenness on the surface, and the back grinding method of the wafer has the following steps before the back grinding of the wafer:

Step (1), forming a protective layer on the surface of the aforementioned wafer;

Step (2) is to planarize the surface of the aforementioned protective layer that is not in contact with the wafer; and,

In step (3), the surface of the protective layer that is not in contact with the wafer is bonded to the support through an adhesive layer.

Wafer with uneven surface:

The wafer back ground by the method of the present invention has irregularities on the surface. surface of the wafer Concave-convex system can include, for example: electrodes, circuit patterns, thick polyimide (5 to 20 μm) belonging to the protective film, defective marks (5 to 100 μm) for identifying defective chips, and bump bonding derived from replacing wire bonding Gold bumps (10 to 100 μm) or solder bumps (50 to 300 μm) are used, and the height of the bumps can be 5 to 300 μm.

The material of the wafer can be a material that is generally used in the manufacture of electronic devices and can form electronic circuits, etc., and is expected to be thinned as a polished base material. Examples include silicon wafers or compound semiconductor wafers such as SiC, AlSb, AlAs, AlN, AlP, BN, BP, BAs, GaSb, GaAs, GaN, GaP, InSb, InAs, InN, or InP, and crystal wafers. , sapphire or glass, etc., but not limited to these. Silicon wafers or compound semiconductor wafers can be doped.

In particular, wafers having irregularities on the surface include wafers used as electronic devices for power devices such as inverters and converters.

step 1):

Step (1) is a step of forming a protective layer on the surface of the wafer.

The protective layer:

The protective layer is used to prevent the electronic circuits on the surface of the wafer from being damaged or polluted by grinding debris or grinding water when the backside of the wafer is ground. In order to grind the back side of the wafer, infeed grinding is generally used, which is to make the wafer suck and hold it on a vacuum chuck type chuck table, and by rotating the chuck table, the wafer is rotated while grinding Grinding tools such as stones are pressed on the back of the wafer; when grinding the back of the wafer in this way, the surface of the wafer is covered with a protective layer, so that the surface of the wafer will not directly contact the holding surface of the chuck table and the wafer will not be damaged. Electronic circuits, etc. on the surface of the circle are damaged.

In one aspect, the protective layer can include, for example, a protective adhesive tape, a protective resin layer, etc., and the protective layer is preferably a protective adhesive tape.

The protective layer of the present invention has a thickness suitable for the protection of the wafer surface, and at the same time, In step (2) described later, planarization, that is, excess thickness for the necessary cutting thickness can be tolerated.

It is better to use protective adhesive tape for the protective layer. When the protective layer is a protective adhesive tape, the step (1) is a step of sticking the protective adhesive tape on the surface of the wafer. The sticking of the protective adhesive tape to the surface of the wafer can be carried out by conventionally known methods, but it is preferably carried out by using an automatic sticking device, and it is preferable to adjust the pressure and temperature appropriately according to the material or type of the wafer and the protective adhesive tape. , time, etc.

protective adhesive tape

The protective adhesive tape used as a preferred protective layer in the method of the present invention is as long as it can withstand the flattening in the step (2) described later, the machinability, and the adhesion that can withstand the back grinding described later, can withstand The chemical resistance and heat resistance of the backside treatment steps described later, and the state that can finally reduce the contamination of the wafer surface can be removed from the wafer, and there is no special limitation. Generally, for the backside grinding of semiconductor wafers, it is preferably selected from as Protects the user of the adhesive tape and can also be used.

Materials for protecting the substrate layer of the adhesive tape include, for example: high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), very low-density polyethylene (VLDPE), linear low Density polyethylene (L-LDPE), random copolymerized polypropylene (random PP), block copolymerized polypropylene (block PP), homogeneous polypropylene (homogeneous PP), polybutene (PB), polymethyl Polyolefins such as pentene (PMP), ethylene-/vinyl acetate copolymer (EVA), ethylene/acrylic acid copolymer or ethylene/methacrylic acid copolymer and their metal crosslinked products (ionomer: ionomer) , and polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), liquid crystal polymer (LCP), etc. For example, polyurethane (PU), polycarbonate (PC), polyimide (PI), polyetheretherketone (PEEK), polyetherimide (PEI), polyamide Amine (PA), wholly aromatic polyamide, polyphenyl sulfide (PPS), fluororesin, polyvinyl chloride, polyvinylidene chloride, cellulose-based resin, etc. Also, the aforementioned resins may be used alone as a single-layer substrate, or may be formed as a combination of the aforementioned plural resins and blended or different substrates. Resin multi-layer composition. From the viewpoint of heat resistance, a substrate having a melting point or a glass transition temperature of 100° C. or higher is preferred, and 150° C. or higher is particularly preferred.

In one embodiment, if the base material layer of the protective adhesive tape considers the following conditions, it is best to include PET, PEN, PBT, LCP, PI, PA, PEEK, and PPS.

The substrate layer of the protective adhesive tape must be able to withstand planarization, so the thickness before planarization is preferably 10 to 1000 μm, particularly preferably 25 to 500 μm. If the thickness of the base material layer of the protective adhesive tape becomes thinner, the protective layer becomes thinner, and the amount that can be polished during planarization is limited, so the effect of flattening the protective layer tends to be reduced. Therefore, when the concavo-convex shape on the wafer surface is large, the thickness accuracy of the wafer after grinding may be lowered due to its influence. On the other hand, if the protective layer before planarization becomes thicker, the rigidity of the protective layer will be high, and the processability will decrease depending on the shape of the tape, and the cutting property will tend to decrease when the tape is cut into a wafer shape. Also, since the protective adhesive tape is not easily deformed due to its rigidity, the detachability of the protective layer removal step after wafer backside grinding tends to decrease.

In addition, the base material layer of the protective tape preferably has a tensile modulus of 1×10 ⁷ Pa or more at 23° C. according to JIS K7113, and more preferably a tensile modulus of 5×10 ⁷ Pa or more. When the tensile modulus becomes low, it tends to affect the flattening of the base material layer of the protective tape. Specifically, even after planarization, the thickness accuracy of the wafer after back grinding tends to decrease due to the influence of unevenness on the wafer surface. On the other hand, from the standpoint of processability, cuttability, bendability, etc. of the substrate layer, the tensile modulus of elasticity is preferably 1×10 ¹⁰ Pa or less, more preferably 6×10 ⁹ Pa or less.

Generally used pressure-sensitive adhesives or hardening adhesives can be used for the adhesive layer of the protective adhesive tape. In general, the adhesive layer may be a single layer or multiple layers. From the viewpoint of following the unevenness of the wafer surface, it may be a multi-layer structure in which a soft intermediate layer and a low-contamination adhesive layer are laminated.

Examples of the pressure-sensitive adhesive include adhesives such as acrylic adhesives, rubber adhesives, and silicone adhesives. In terms of the adhesiveness of the semiconductor wafer or substrate layer, and the cleaning properties of the wafer after peeling off the protective adhesive tape with ultrapure water or organic solvents such as alcohols, it is preferable to use acrylic polymers. as an acrylic adhesive for the base polymer.

Examples of the above-mentioned curable adhesives include photocurable adhesives that crosslink and cure by light irradiation, and thermosetting adhesives that crosslink and cure by heating. The said photocurable adhesive agent is mentioned, for example: The photocurable adhesive agent which has a polymerizable polymer as a main component and contains a photoinitiator. Examples of the thermosetting adhesive include, for example, a thermosetting adhesive containing a polymerizable polymer as a main component and containing a thermal polymerization initiator.

If the adhesive layer of the protective adhesive tape is peeled off and the adhesive force is small, the adhesion to the wafer will be insufficient compared to the shear force when the substrate layer of the protective adhesive tape is flattened, and there will be a problem that the protective adhesive tape will be completely peeled off from the wafer. . On the other hand, if the peeling adhesive force is high, it may be difficult to peel the protective adhesive tape from the wafer. Therefore, from the viewpoint of final wafer peeling, the thickness is preferably 5 to 500 μm, particularly preferably 10 to 100 μm. In addition to using the attached body as a silicon mirror wafer, the rest is based on JIS Z0237 (2009) 180° peel adhesion (peeling speed 300mm/min), preferably 0.3 to 10N/25mm, and 0.5 to 7N/25mm as the characteristic good. Within this range, appropriate adjustments are made according to the manufacturing process.

As the protective layer, a protective resin layer can also be used. When the protective layer is a protective resin layer, the protective resin layer is applied by a known method such as spin coating of raw resin dissolved in a solvent or liquid raw resin itself (hereinafter also referred to as a precursor resin solution), and It is hardened by light irradiation, heating, drying, etc., and functions as a solid protective layer. It may also be formed in plural layers.

Protective resin layer:

The protective resin layer that can be used as the protective layer is as long as it can withstand planarization in the step (2) described later Adhesiveness, machinability, and adhesiveness that can withstand the backside grinding described later, chemical resistance that can withstand the backside treatment steps described later, heat resistance, and finally the state of reducing the contamination of the wafer surface can be removed from the wafer, It is not particularly limited, and it is preferably selected from known materials for temporarily fixing a device wafer to a support, and may also be used. Precursor resin solutions include, for example, rubber-based resin solutions in which rubber, elastomer, etc. are dissolved in a solvent, single-component thermosetting resin solutions based on epoxy, urethane, etc., epoxy, amine Ethyl formate, acrylic acid, etc. as the base of the two-component mixed reaction type resin liquid, hot melt adhesive, acrylic, epoxy, etc. as the base ultraviolet (UV) or electron beam curing type resin liquid, water dispersion resin liquid. Polymerizable vinyl oligomers such as urethane acrylate, epoxy acrylate, or polyester acrylate, and/or acrylic or methacrylic monomers are suitable for adding photopolymerization initiators, and , UV curable resin liquid with additives depending on the situation. Examples of additives include thickeners, plasticizers, dispersants, fillers, flame retardants, and heat-resistant aging agents. The protective resin layer may also be formed in plural layers.

Step (2):

Step (2) is a step of planarizing the surface of the protective layer not in contact with the wafer.

For example, when the protective layer is a protective adhesive tape, it is a step of flattening the base material layer of the protective adhesive tape. If a protective adhesive tape is pasted on the surface of the wafer in step (1), the unevenness on the surface of the wafer will be transferred to the substrate layer of the protective adhesive tape. Furthermore, if the backside is ground directly, the power of the backside grinder It is not applied uniformly, but reflects the unevenness of the substrate layer of the protective adhesive tape, and the unevenness is also transferred to the backside of the wafer. When the protective layer is formed from the protective resin layer, it may not be sufficiently planarized only by spin coating, and unevenness may still occur on the surface of the protective layer and be transferred to the back surface of the wafer.

In this way, the substrate layer of the protective adhesive tape with the unevenness transferred is flattened before the back grinding, so that the force of the back grinder can be applied evenly, and the unevenness can be prevented from being transferred to the backside of the wafer.

There is no special planarization system as long as it can prevent unevenness from being transferred to the back of the above-mentioned wafer. Restrictions are preferably those that satisfy the following conditions, for example.

Covering the entire surface to be cut, the difference between the concave portion and the convex portion of the surface of the protective layer not in contact with the wafer is preferably 5 μm or less, more preferably 3 μm or less, and most preferably 1 μm or less.

In one embodiment, the aforementioned planarization is performed by cutting, grinding or polishing.

In one embodiment, the aforementioned cutting is performed by cutting with a tool. Compared with the case of planarization by polishing with a grinder, cutting with a tool can solve problems such as grinding stone clogging during polishing, and planarization can be easily performed. Tool cutting can be implemented by a surface planar.

Step (3):

Step (3) is a step of adhering the surface of the protective layer not in contact with the wafer to the support through an adhesive layer to form a laminate.

adhesive layer

The adhesive layer is used to bond the surface of the protective layer not in contact with the wafer to the support. The adhesive layer temporarily fixes the wafer on the support. After processing, for example, it can be applied by IR laser method, UV irradiation method, laser removal method, solvent stripping method, thermal/UV foaming method, mechanical A well-known temporary fixing material that can easily separate the support body by a peeling method or the like may be an adhesive tape formed by applying a liquid adhesive (adhesive dissolved in a solvent, etc.) by spin coating or the like. The adhesive layer can be formed on the support, on the protective layer, or both. The uneven thickness of the adhesive layer is preferably not more than 5 μm, more preferably not more than 3 μm, and most preferably not more than 1 μm.

The adhesive layer is at least one selected from the group consisting of acrylic, polysiloxane, polyimide, and rubber. When the adhesive layer is an adhesive tape, the adhesive tape may be a single layer, a laminate of plural layers, or a double-sided tape including a base film in a layer.

Support body

The support body preferably has sufficient strength and rigidity, and is excellent in heat resistance, chemical resistance, and thickness accuracy. Using such a support, even if the wafer is thinned after grinding, the wafer can be handled stably without warping, etc., and the wafer can be supplied to many and/or various processes.

Known supports can be used in the support system, preferably used materials can be listed as: silicon, sapphire, crystal, metal (such as aluminum, copper, steel, stainless steel), various glasses and ceramics, resin (such as polyimide , polyamide, epoxy, phenol, polyphenylene ether, polyetheretherketone, polyetherimide, fully aromatic polyamide, polyphenylene sulfide resin). The support system can be composed of a single material, or multiple materials, and can include other materials deposited on the base material. For example, a vapor-deposited layer of silicon nitride or the like may be provided on a silicon wafer. Particularly preferred supports are made of glass, silicon, ceramics, metal, resin, or composite materials of these.

In one embodiment, the aforementioned adhesive layer can be made from the substrate layer of the aforementioned protective adhesive tape flattened in step (2), and can also be made on the surface of the aforementioned support, or can be formed on both sides. Examples of the method of making the adhesive layer include spin coating when the adhesive layer is a liquid adhesive (adhesive dissolved in a solvent, etc.), and adhesive tape when the adhesive layer is adhesive tape. The method of carrying out, but not limited to these.

Back grinding steps:

The back grinding step is typically wafer grinding and polishing, but is not limited thereto, and may include singulation and the like.

When the wafer on which the electrodes are formed is ground or polished, the surface on which the electrodes are not formed (back side) is ground or polished. The thickness of the wafer after such backside grinding or polishing is different depending on the semiconductor device used, but it is preferably set at 200 μm or less, more preferably at 50 μm or less Down. This enables thinning of the obtained semiconductor device and miniaturization of electronic equipment using such a semiconductor device.

When the wafer is ground or polished, in step (3), a laminate is formed with a rigid support volume layer and a rigid support volume layer with good thickness accuracy through the adhesive layer, and the wafer can be ground with more excellent processing accuracy, and, in After the grinding and the like, the wafer can be supplied to the backside processing step described later without damaging the wafer, or can be easily separated from the support body and the adhesive layer.

In one embodiment, the wafer back grinding method of the present invention may further include a wafer back processing step, a support removal step, an adhesive layer removal step, or a protective adhesive tape after the wafer back grinding. At least 1 of the steps is removed.

Backside processing steps:

The wafer back grinding method of the present invention further includes a step of processing and/or chemically treating the wafer as a back treatment step after the back grinding of the wafer.

The above-mentioned processing includes, for example, annealing treatment, rear electrode formation (sputtering: Sputtering), vapor deposition, etching, chemical vapor deposition (CVD), physical vapor deposition (PVD), resist coating/patterning ion implantation, reflow soldering, doping, etc., but not limited to these.

The above-mentioned chemical treatment is typically a treatment using an acid, alkali or organic solvent, for example: electrolytic plating, electroless plating and other plating treatments, or hydrofluoric acid, tetramethylammonium hydroxide aqueous solution (TMAH) and other wet Formula etching treatment, or resist stripping process with N-methyl-2-pyrrolidone, monoethanolamine, DMSO, etc., or cleaning process with concentrated sulfuric acid, ammonia water, hydrogen peroxide solution, etc., but not limited to etc.

In one embodiment, the backside treatment includes at least one of etching, electrode formation, ion implantation, and annealing.

Support removal steps:

The support removal step is a step of removing the support from the laminate. The removal method of the support includes, for example, IR laser method, UV irradiation method, laser removal method, solvent stripping method, thermal/UV foaming method, mechanical stripping method, etc., but is not limited thereto.

Protective layer and adhesive layer removal steps

The step of removing the protective layer and the adhesive layer is a step of removing the protective layer from the thinned wafer, and the protective layer and the adhesive layer can be removed simultaneously or successively. As a removal method, peeling, washing|cleaning, etc. are mentioned, for example.

In one aspect, a method of manufacturing an electronic device is provided, which includes the wafer back grinding method of the present invention in the manufacturing steps. That is, the wafer ground by the wafer back grinding method of the present invention can be further supplied to a subsequent step to manufacture a final product. In the case of forming circuits, etc. on a wafer, the steps commonly used in the manufacture of semiconductor devices or electronic devices such as crystal dicing, bonding, packaging, and sealing are performed, and semiconductor devices and electronic devices can be manufactured as finished products.

In an implementation form, the aforementioned electronic device is an electric device. As mentioned above, the power device is used in a power converter such as an inverter or a converter, and has unevenness on the surface of the wafer due to its characteristics, structure, and manufacturing steps. According to the present invention, the influence of the device characteristics due to the influence of its unevenness can be suppressed.

In addition, not only in the back grinding of wafers, but also in various processing processes, it can suppress the influence of unevenness and improve operability, so for example, it can also be applied to electrodes vertically penetrating silicon substrates (TSV) or large unevenness In the grinding application of the bump wafer.

Hereinafter, the wafer back grinding method of an embodiment of the present invention will be further described with reference to the drawings, but the present invention is not limited to these embodiments.

(implementation type 1)

Symbol 1 in FIG. 1( a ) represents a semiconductor wafer (hereinafter referred to as a wafer) thinned by back grinding. Should Wafer 1 is a silicon wafer or the like, and has a thickness of, for example, 700 μm to 800 μm before processing and is uniformized. On the surface 11 of the wafer 1, a plurality of squares are divided by grid-like dividing lines. Electrodes and the like are formed on the device, and unevenness is generated on the surface 11 of the wafer 1 .

The back grinding method of the wafer in this embodiment is as shown in Figure 1 (a) to (e), sticking the protective adhesive tape 3 on the surface 11 of the wafer 1, and then making it protect the base material layer of the adhesive tape 3 31 is planarized by tool grinding, and then the substrate layer 33 of the flattened protective adhesive tape 3 is bonded to the support body 5 through the adhesive layer 4, and then the back surface 12 of the wafer 1 is ground to be thinned to The intended thickness (for example, 200 μm or less). Hereinafter, the procedure will be described in detail.

As mentioned above, in this embodiment, the protective adhesive tape 3 is first pasted on the surface 11 of the wafer 1 . Pasting is carried out by using an automatic pasting device to reduce pressure to below 100Pa and heat below 100°C. As shown in FIG. 1( b ), the unevenness on the surface 11 of the wafer 1 is transferred to the base material layer 31 of the protective adhesive tape 3 to which it is pasted.

The wafer 1 with the protective adhesive tape 3 stuck on the surface 11 is then planarly cut the base material layer 31 of the protective adhesive tape 3 . The cutting system uses a planer. According to the surface planer, the back surface 12 of the wafer 1 is adsorbed and held on the suction surface of a vacuum chuck-type chuck table, and the base material layer 31 of the protective adhesive tape 3 is flattened by the engagement of the rotating cutting tool of the cutting unit. cutting.

Then, an adhesive layer 4 is formed on the planarized base material layer 33 of the protective adhesive tape. In order to form the adhesive layer 4, a so-called spin-coating method is suitably used, in which the substrate layer 33 of the flattened protective adhesive tape is exposed on a table driven by rotation, and the surface of the wafer 1 is exposed. The wafer 1 is placed and held in such a way that the center is aligned with the rotation axis of the table, the table is rotated, and the liquid adhesive is dripped into the center of the rotating wafer 1, so that the adhesive is fully coated on the planarized surface by centrifugal force. The substrate layer 33 of the protective adhesive tape. In this way, as shown in FIG. 1( d), an adhesive bond is formed on the substrate layer 33 of the flattened protective adhesive tape. Layer 4.

Then, by joining the support body 5 to the adhesive layer 4, the laminated body shown in FIG.1(e) can be obtained. The laminated system obtained in this way has no unevenness on the substrate layer 33 of the protective adhesive tape 3, so there is no unevenness transferred to the surface 11 of the wafer 1 by grinding the back surface 12 of the wafer 1, even if the wafer is ground by backside grinding. 1 is thinned, and also has a support body 5, so the operability such as transportability will not be lost in the subsequent processing process.

Then, the back surface 12 of the wafer 1 is ground to thin the wafer 1 to a desired thickness. For the back grinding of the wafer 1, it is suitable to use a grinding device for feed grinding. According to this polishing device, the support body 5 is adsorbed on the suction surface of a vacuum chuck type chuck table to hold the laminate, and the back surface 12 of the wafer 1 is polished by two polishing units (for rough grinding and finishing grinding). Rough grinding and finishing grinding are carried out in sequence.

At this time, in order to remove the thinned wafer 1 , after removing the support body 5 , the protective adhesive tape 3 is removed. The removal of the support body 5 is carried out by inserting a remover into the interface between the support body 5 and the adhesive layer 4 and pulling up the support body 5 by mechanical peeling. The removal of the protective adhesive tape 3 is performed by peeling the protective adhesive tape 3 from the wafer 1 . By using the protective adhesive tape 3, the cleaning step of the wafer after peeling can be unnecessary or minimized, so the workability is excellent, and the manufacturing cost of semiconductor devices and electronic devices can be controlled to be lower.

(implementation type 2)

The surface 11 of the wafer 1 can be protected by using a protective resin layer instead of the protective adhesive tape 3 of Embodiment 1. At this time, the so-called spin coating method is suitably used, which is mounted on a rotary drive table with the surface 11 of the wafer 1 exposed, and the center of the wafer 1 is aligned with the rotation axis of the table. Place and hold the wafer 1, rotate the stage, and drop the precursor resin solution into the center of the rotating wafer 1, so that the precursor resin solution is fully coated on the surface 11 of the wafer 1 by centrifugal force. The coating film after spin coating is placed on a hot plate to dry, and the solvent in the film is completely removed to form a protective layer. The other steps are the same as those of Embodiment 1.

At this time, the protective layer is removed by the cleaning step to replace the protective adhesive of the above-mentioned embodiment 1. Peel off the adhesive tape 3. In the cleaning step, make the protective layer face up, fix the wafer 1 on the table driven by the rotation, spray the cleaning solvent, and place the cleaning solvent, after standing still, discard the cleaning solvent, and repeat the same process again. After placing the cleaning solvent in the same manner and leaving it still, the same operation was repeated twice, and cleaning was performed by spraying isopropyl alcohol (IPA) while rotating the wafer 1 .

[Industrial availability]

The back grinding method of the wafer of the present invention can suppress the influence of the unevenness of the wafer surface, and can improve the operability in various processing processes after the wafer is thinned, so it greatly contributes to semiconductor devices, electronics Improve the productivity of devices, etc., and have high applicability in various fields including the electronic parts industry of the semiconductor process industry, the electrical electronics industry using electronic parts, the transportation machinery industry, the information communication industry, and the precision machinery industry. .

1: Semiconductor wafer

3: Protective adhesive tape

4: Adhesive layer

5: Support body

11: The surface of the wafer

12: The back side of the wafer

31: Protect the substrate layer of the adhesive tape

32: Adhesive layer of protective adhesive tape

33: Substrate layer of planarized protective adhesive tape

Claims (15)

A method for grinding the back of a wafer is a method for grinding the back of a wafer with concavo-convex surfaces. The method for grinding the back of the wafer has the following steps before grinding the back of the wafer: Step (1), which is to form a protective layer on the surface of the aforementioned wafer; Step (2) is to planarize the surface of the aforementioned protective layer that is not in contact with the wafer; and In step (3), the surface of the protective layer that is not in contact with the wafer is bonded to the support through an adhesive layer. The wafer back grinding method according to claim 1, wherein the protective layer is a protective adhesive tape. The wafer back grinding method as described in Claim 2, wherein the substrate layer of the aforementioned protective adhesive tape is selected from the group consisting of PET, PEN, PBT, LCP, PI, PA, PEEK and PPS. At least 1 resin. The wafer back grinding method according to any one of Claims 1 to 3, wherein the wafer having unevenness on the surface is formed by electrodes, circuit patterns, polyimide, defective marks, or A wafer having concavo-convex for at least one of the bumps. The wafer back grinding method according to any one of claims 1 to 4, wherein the step of planarizing is a step of planarizing by cutting, grinding, or polishing. The wafer back grinding method according to claim 5, wherein the cutting is performed by cutting with a tool. The wafer back grinding method according to any one of claims 1 to 6, wherein the adhesive layer is a liquid adhesive or an adhesive tape. The back grinding method of a wafer as described in any one of Claims 1 to 7, wherein the preceding The above-mentioned support body is made of glass, silicon, ceramics, metal, resin or these composite materials. The back grinding method of a wafer as described in any one of claims 1 to 8, wherein, after the aforementioned step (2), before the aforementioned step (3), the following steps are included: on the planarized aforementioned protective layer The surface not in contact with the wafer, the surface of the aforementioned support or both, form the aforementioned adhesive layer. The wafer back grinding method according to any one of claims 1 to 9, further comprising a wafer back treatment step after the wafer back grinding. The wafer back grinding method according to claim 10, wherein the wafer back processing step includes at least one of etching, electrode formation, ion implantation, and annealing. The wafer back grinding method according to any one of claims 1 to 11, wherein the thickness of the wafer after back grinding is 200 μm or less. A method of manufacturing an electronic device, comprising the method of backgrinding a wafer according to any one of Claims 1 to 12 in the manufacturing steps. The method of manufacturing an electronic device according to claim 13, wherein the electronic device is a device that also has electrodes on the back side. The method of manufacturing an electronic device according to claim 14, wherein the electronic device is an electric device.

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