JP2014070210A - Temporarily fixing sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temporarily fixing sheet of being fixed to a carrier in temporarily fixing without generating warpage in a wafer or the like when a wafer or the like are subjected to grinding or polishing.SOLUTION: Provided is a temporarily fixing sheet 2 with a thickness of 10 μm to 1 mm obtained by infiltrating a nonwoven fabric or a porous sheet with a non-reaction type composition having a melting point of 40 to 90°C. The temporarily fixing sheet is impregnated with a non-reaction type composition including at least one kind selected from a thermoplastic resin and an elastomer made of hydrocarbon being a sold at 25°C.

Description

In the process of smoothly polishing or grinding the adherend, the present invention temporarily fixes a silicon wafer, sapphire glass, ceramic material, optical glass, crystal, magnetic material, metal, etc. as the adherend, The present invention relates to a sheet impregnated with a non-reactive composition suitable for polishing and grinding.

Conventionally, the side-chain crystalline polymer found in Patent Document 1 is known as a heat-sensitive raw material. These raw materials are used as thermal transfer recording media. In particular, high-speed printing is enabled by causing a solid-liquid-solid phase change in a short time. In order to make the composition into a liquid paint at 25 ° C., a low-viscosity solvent or paraffin is added in an amount of about 90% by weight. Moreover, it heat-drys and uses it.

Temporary fixing agents are known that are used when a surface of an adherend of a silicon wafer, sapphire glass, ceramic material, optical glass, crystal, magnetic material, or the like (hereinafter referred to as a wafer) is subjected to surface polishing. As the temporary fixing agent, a hot melt temporary fixing agent using a hot melt composition that is solid at room temperature is used. When applying a hot-melt type resin, the resin is applied to the adherend while being heated and melted. However, when the area of a wafer or the like is large, even if the melted temporary fixing agent is applied as a uniform coating, it is not possible to form a partially uniform coating due to surface tension.

In order to improve the workability of the conventional temporary fixing agent, Patent Document 3 is a reactive temporary fixing agent made of a resin composition that is cured by active energy rays, which can be dissolved in warm water at 90 ° C. to peel off a wafer or the like. it can. However, since the reactive temporary fixing agent undergoes curing shrinkage at the time of curing, when the thickness of the wafer or the like is thin, the wafer or the like is partially distorted. In particular, when the wafer or the like is a thin film, the distortion occurs remarkably.

JP 2007-119634 A JP 2006-290957 A

With conventional hot-melt type temporary fixing agents and reactive temporary fixing agents, it is difficult to fix the wafer or the like to the carrier without distortion when grinding or polishing the wafer or the like.

As a result of intensive studies to achieve the above object, the present inventors have completed the present invention relating to a temporary fixing sheet obtained by impregnating a non-reactive composition into a nonwoven fabric or a porous sheet.

The gist of the present invention will be described next. The first embodiment of the present invention is a temporary fixing sheet having a thickness of 10 μm to 1 mm, in which a non-reactive composition having a melting point of 40 to 90 ° C. is impregnated into a nonwoven fabric or a porous sheet.

According to a second embodiment of the present invention, there is provided the non-reactive composition according to the first embodiment including at least one selected from a thermoplastic resin or an elastomer composed of a hydrocarbon that is solid at 25 ° C. It is the temporarily fixed sheet impregnated.

A third embodiment of the present invention is a non-conducting material according to any of the first or second embodiments, comprising a thermoplastic resin that is solid at 25 ° C. and polymerized only from α-olefins having 16 to 35 carbon atoms. It is a temporary fixing sheet impregnated with a reactive type composition.

A fourth embodiment of the present invention is a manufacturing method in which an adherend is fixed by the temporary fixing sheet according to any one of the first to third embodiments, and the adherend is polished or ground.

The present invention can fix a wafer or the like to a carrier without distorting the wafer or the like when grinding or polishing the wafer or the like. Further, when the adherend such as a wafer is peeled off in the peeling direction by the temporarily fixing sheet of the present invention, it satisfies simultaneously that the adherend is peeled cleanly without being broken or deformed.

FIG. 1 is a side view of a specific example of chemical mechanical polishing, and the polishing method is not limited to this. FIG. 2 is a top view of FIG. FIG. 3 is an explanatory diagram for explaining a measuring method of shear strength measurement. FIG. 4 shows test pieces and measurement points in tolerance measurement.

The polishing process of the present invention mainly indicates chemical mechanical polishing, and is based on the relative movement of the polishing agent and the object to be polished by the surface chemical action of the polishing agent (abrasive grain) itself or the action of chemical components contained in the polishing liquid. This technique increases the mechanical polishing (surface removal) effect and obtains a high-speed and smooth polished surface. Also expressed as chemical mechanical polishing, chemical mechanical polishing, chemical mechanical polishing.

The present invention can be used for precision metal grinding in addition to polishing. In particular, the present invention is suitable for machining that requires accuracy. The specific processing of grinding is mainly abrasive processing, and typical processing is processing using loose abrasives using slurry and fixed abrasives in which abrasives are fixed with a binder. The processing using them includes processing such as belt grinding and horn finishing, but is not limited thereto.

Specific examples of adherends to be polished include optical glass (lens, prism, PBS, optical filter), electronic component glass, quartz glass (synthetic quartz, fused silica), and quartz (quartz heat sink, SAW, optical low-pass filter). lithium niobate LiNbO _3, lithium tantalate LiTaO _3-magnesium oxide MgO, samarium cobalt SmCo-neodymium-iron-boron NbFeB-ferrite (hard ferrite, soft ferrite) barium titanate BaTiO _3, potassium zirconia ZrO2-silicon nitride titanate Examples thereof include, but are not limited to, Si ₃ N ₄ , aluminum nitride AlN, alumina Al ₂ O ₃ , sapphire, piezoelectric ceramics PZT, and machinable ceramics.

The present invention is used for polishing on the back side of the epitaxially grown surface of a wafer or the like that has been subjected to epitaxy (epitaxial growth) for growing a crystal phase with a certain crystal orientation relationship with the substrate crystal on the base substrate crystal. . In this process, if the wafer or the like is warped, the thickness of the substrate after polishing varies, and the polishing accuracy of the substrate decreases.

The temporary fixing sheet in the present invention means that the adherend is fixed against a force in the shearing direction to such an extent that the adherend such as a wafer does not come off in the polishing process. Moreover, the thickness after polishing of a wafer or the like can correspond to polishing of less than 100 μm. The present invention is suitable for temporarily fixing a wafer having a large diameter having a diameter of 6 inches or more. In a wafer having a diameter of 150 mm or more, the wafer itself has a warp. Since a uniform coating film cannot be formed with a liquid temporary fixing agent, it is difficult to fix a wafer or the like having warpage due to sparse peel strength with a uniform force.

Details of the temporary fixing sheet of the present invention will be described below. The temporary fixing sheet is produced by impregnating a non-reactive composition having no reactive functional group into a sheet-like substrate having voids inside. (Hereinafter, in the present application, a sheet-like substrate having voids is simply referred to as “substrate”.) The substrate may be any sheet-like one having voids, specifically, a porous sheet, Examples thereof include paper-like or cloth-like nonwoven fabric, woven fabric, knitted fabric, and mesh. Examples of the porous sheet include those produced by JP-A-11-199345, JP-A-2004-51772, JP-A-2005-15580, and the like. In the present invention, a paper-like or cloth-like non-woven fabric, a porous sheet, and a mesh, which are inexpensive and inexpensive, are most preferable. The base material that can be used in the present invention is preferably a plastic or polymer material, and specific materials include, but are not limited to, nylon, polyester, polypropylene, polyethylene, and fluorocarbon resin. It is not a thing. In nonwoven indicates the density of the fibers by basis weight (g / m ^2), is preferably one having a basis weight of 1 to 50 g / m ² in order to have many voids better basis weight is small. In the porous sheet which has a space | gap inside a base material, the ratio for which a space | gap occupies is shown by porosity (%) among the whole volume, and what has a porosity of 50-95% about a porous sheet is preferable. In addition, a base material such as a mesh represents a void in an open area (%). The base material preferably has an open area of 20 to 80%.

The temporary fixing sheet of the present invention is produced by a method of impregnating a non-reactive composition in the voids of a substrate with an impregnation apparatus or forcibly impregnating with a thermocompression bonding apparatus. When the non-reactive composition does not contain a non-volatile component, it can be solidified by impregnating the base material with a composition melted by heating and scraping off the excess resin component. On the other hand, there is also a production method in which a volatile component is added to a composition in advance and impregnated into a substrate, and then heated at a temperature not higher than the melting point of the non-reactive composition to volatilize the volatile component. The thickness of the manufactured temporary fixing sheet is preferably 10 μm to 1 mm. In the temporary fixing sheet thinner than 10 μm, the force for fixing the wafer or the like is weakened, which causes peeling. In addition, a temporarily fixed sheet thicker than 1 mm is not suitable because a gradient occurs in the thickness of the temporarily fixed sheet at the time of fixing.

The non-reactive composition that can be used in the present invention is composed of at least one material selected from thermoplastic resins and elastomers that are solid at 25 ° C. as the component (A). Not only a saturated bond but an unsaturated bond may be included. Most preferably, the component (A) is composed of carbon and hydrogen and / or is composed of carbon, hydrogen and oxygen. In addition, the component (A) may include a material having a melting point (softening point) of 40 to 110 ° C. as an essential component, and two or more types of components (A) may be mixed. The melting point of the non-reactive composition is more preferably 40 to 90 ° C.

As the component (A) that can be used in the present invention, a thermoplastic resin obtained by copolymerizing an α-olefin such as ethylene, propylene, 1-butene, 1-pentene, and 1-octene, or these α-olefins, Examples include elastomers formed by copolymerization of cyclic olefins, styrene monomers, and non-conjugated dienes. Non-conjugated dienes include dicyclopentadiene, 1,4-hexadiene, dicyclooctadiene, methylene norbornene, 5-ethylidene-2-norbornene and the like. Specific examples of the component (A) include ethylene / propylene copolymer elastomer, ethylene / 1-butene copolymer elastomer, ethylene / propylene / 1-butene copolymer elastomer, ethylene / 1-hexene copolymer elastomer. , Ethylene / 1-octene copolymer elastomer, ethylene / styrene copolymer elastomer, ethylene / norbornene copolymer elastomer, propylene / 1-butene copolymer elastomer, ethylene / propylene / nonconjugated diene copolymer elastomer, ethylene Examples thereof include amorphous elastic copolymers mainly composed of olefins such as 1-butene-nonconjugated diene copolymer elastomer and ethylene / propylene / 1-butene-nonconjugated diene copolymer elastomer. Specific examples of the component (A) include, but are not limited to, PARAFINWAX series manufactured by Nippon Seiwa Co., Ltd., and Imabe series manufactured by Idemitsu Kosan Co., Ltd.

The component (A) of the present invention is most preferably a polymer obtained by polymerizing an α-olefin having 16 to 35 carbon atoms as an essential component. (Hereinafter, the α-olefin having 16 to 35 carbon atoms is referred to as a higher olefin.) Examples of the higher olefin include 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene and the like. Among these, 1 type (s) or 2 or more types can be used. When the α-olefin has 16 or more carbon atoms, the polymer has high crystallinity and tends to improve hardness. When the α-olefin has 35 or less carbon atoms, the polymer tends to be narrow and uniform in the melting and crystallization temperature range. Specific examples of the component (A) include Elkrista series manufactured by Idemitsu Kosan Co., Ltd., but are not limited thereto. Although there is no limitation in particular as a manufacturing method of (A) component, For example, it can manufacture using a metallocene catalyst by the method described in Unexamined-Japanese-Patent No. 2005-75908 or WO2003 / 070790.

The component (A) is a polymer having an olefin having 2 to 8 carbon atoms as a main constituent unit, and a copolymer having an ethylene unit as a main constituent unit and a wax solid at 25 ° C. is also applicable. . In particular, the component (A) having a softening point of 60 to 100 ° C. and / or a melting point of 40 to 80 ° C. is suitable. A wax having compatibility with the other component (A) is preferred, and a particularly preferred wax is a hydrocarbon wax and / or EVA wax. Two or more types can be mixed. Specific examples include, but are not limited to, the Licocene series manufactured by Clariant.

In the present invention, in addition to the component (A), a compound that is liquid at 25 ° C. can be appropriately added in the range of 0 to 30% by mass of the whole non-reactive composition. Specifically, it can be used as a solvent, a plasticizer, a lubricating oil, or a cleaning agent. However, from the viewpoint of the properties relating to the shear strength of the non-reactive composition, it is particularly preferred that the compound that is liquid at 25 ° C. is not substantially contained. The compound needs to be compatible with other components, and a hydrocarbon compound having no polar group such as a hydroxyl group, a carboxyl group, or an ester group is suitable. Specific examples include isoparaffinic hydrocarbons, paraffinic oils, and paraffinic hydrocarbons. When the compound is added, the non-reactive composition does not exhibit toughness, and there is a tendency that characteristics necessary for temporary fixing such as removal of a wafer during grinding and polishing work tend to decrease. Moreover, when these are added more than 30 mass parts with respect to 100 mass parts of (A) component, it will not become solid at 25 degreeC. The term “substantially free” means that a liquid component is intentionally mixed as an impurity in the raw material when it is not intentionally added, or when a minute amount of liquid is intentionally added to such an extent that the viscosity is hardly affected. The case where the compound is volatilized by drying after the addition. Specific examples of the hydrocarbon compound include IP Solvent Series, PS-32 manufactured by Idemitsu Kosan Co., Ltd., and Aqua Solvent Z Series manufactured by Aqua Chemical Co., Ltd., but are not limited thereto.

In the non-reactive composition used in the present invention, inorganic materials such as pigments, dyes and other colorants, metal powder, calcium carbonate, talc, silica, alumina, aluminum hydroxide and the like are used, as long as the effects of the present invention are not impaired. An appropriate amount of additives such as a filler, a flame retardant, an organic filler, a plasticizer, an antioxidant, an antifoaming agent, a silane coupling agent, a leveling agent, and a rheology control agent may be blended. By adding these, a temporary fixing sheet excellent in flexibility, adhesive strength and workability can be obtained.

Examples of the method of bonding the temporarily fixing sheet to a wafer or the like include a thermocompression bonding in which heat and pressure are applied and a method using a vacuum laminator that fixes the adherend by heating in a vacuum state, but is not limited thereto. As a method for peeling the temporarily fixed sheet from the adherend, there is a method by heating or dissolution. When the composition is insoluble in water, there is a method of heating, and when it is water-soluble, there is a method of heating or dissolving in water or hot water, but it is not limited thereto. On the other hand, when the temporary fixing sheet is peeled from the adherend, it is physically peeled off when the shear strength of the non-reactive composition is relatively low, and when it is firmly fixed temporarily, the non-reactive type is heated. The composition can be dissolved and removed, but is not limited thereto.

EXAMPLES Next, although an Example is given and this invention is demonstrated further in detail, this invention is not limited only to these Examples.

[Examples 1 to 5, Comparative Example 1]
In order to prepare a temporary fixing sheet, first, the following components were prepared in order to prepare a non-reactive composition. Thereafter, the prepared base material is impregnated with the non-reactive composition. Details are summarized in Table 1.

[Preparation of non-reactive composition]
Component (A): Thermoplastic resin or elastomer composed of hydrocarbons that are solid at 25 ° C. Thermoplastic resin polymerized only from α-olefins that are solid at 25 ° C. and have 16 to 35 carbon atoms (melting point: 70 ° C) (ELCRYSTA 7100 Idemitsu Kosan Co., Ltd.)
Aromatic thermoplastic resin (melting point: 100 ° C.) (Imabe P-100, manufactured by Idemitsu Kosan Co., Ltd.)
Polyolefin wax (softening point: 85-91 ° C.) (manufactured by licocene PP1602 Clariant)
・ Polyolefin-based thermoplastic resin (melting point: 69 ° C.) (PARAFINWAX 155 manufactured by Nippon Seiwa Co., Ltd.)
・ Polyolefin-based thermoplastic resin (melting point: 55 ° C.) (PARAFINWAX 130 manufactured by Nippon Seiwa Co., Ltd.)

(A) A component is heated and melted. The melting temperature is appropriately adjusted for each material. Stir for 15 minutes until the molten component (A) is uniform. Since it becomes solid when the temperature falls to room temperature, it is ground in a mortar and made into powder. Detailed preparation amounts follow Table 1, and all numerical values are expressed in parts by mass.

In order to prepare the temporarily fixing sheets of Examples 1 to 5, the following base materials were prepared. Details of the non-reactive composition and the temporary fixing sheet are summarized in Table 1.

[Preparation of substrate]
Porous sheet substrate A: polyethylene microporous membrane (thickness 20 μm, porosity 88%)
Substrate B: polyethylene microporous membrane (thickness 35 μm, porosity 88%)
Nonwoven fabric substrate C: Nonwoven fabric made of polyester (thickness 38 μm, basis weight 15 g / m ² ) (manufactured by JH-30015 Japan Vilene Co., Ltd.)

The method for impregnating the substrate with the non-reactive composition is as follows. A necessary amount of the powdery non-reactive composition calculated from the porosity is heated at 90 ° C. to melt. After pouring the non-reactive composition onto the release paper, two sheets of the same non-reactive composition are produced by extending the non-reactive composition into a sheet so that the film thickness is approximately constant. After the sheet-like non-reactive composition returns to room temperature, the substrate is sandwiched between two sheet-like non-reactive compositions formed on the release paper, and the composition is heated with a hot roll laminator at 90 ° C. While melting, the substrate is impregnated with the non-reactive composition and left to room temperature. What peeled off the release paper is equivalent to a temporary fixing sheet.

For Comparative Examples 1 and 2, melt viscosity measurement and shear strength measurement were performed by the following methods. Moreover, tolerance measurement was performed for Examples 1 to 5 and Comparative Example 1, and the measurement results are summarized in Table 2.

[Measurement of melt viscosity]
Measurement is performed under the following conditions, and the viscosity in an atmosphere of 100 ° C. is defined as “melt viscosity (mPa · s)”. When handling the composition, the melt viscosity is preferably 1 to 5000 mPa · s. In the case of 1 mPa · s or less, the composition approaches due to surface tension. On the other hand, when the viscosity is 5000 mPa · s or more, the viscosity is too high and the stringing is accompanied, which is difficult to handle. Comparative Example 1 was 960 mPa · s, and Comparative Example 2 was 2500 mPa · s.
Brookfield RVT (Brookfield Thermocell System)
Spindle: SC4-21
Rotational speed: appropriately changed to 5, 10, 20, 50, 100 rpm depending on the viscosity of the composition Measuring temperature: 100 ° C.

[Shear strength measurement]
The composition is applied to the following glass plate while heating, and the glass plate is aligned and bonded. After that, the glass plate is fixed as shown in FIG. 3, the digital force gauge is moved at a predetermined moving speed, and the strength when the digital force gauge head is brought into contact with the glass plate in the shearing direction with respect to the bonding surface ( N) is measured. The strength per bonding area (m2) is defined as “shear strength (MPa)”. If the shear strength is less than 0.05 MPa, it is not suitable for temporarily fixing a wafer or the like. Comparative Example 1 was 0.19 MPa, and Comparative Example 2 was 0.12 MPa.
Glass plate: 5.0 x 25 x 100 mm
Bonding area: 25 × 10mm
Strength measuring instrument: Digital force gauge FGC-10 Nidec Sympo Co., Ltd. Strength measuring instrument moving speed: 10 mm / min

[Tolerance measurement]
A glass plate having a length of 150 mm, a width of 150 mm, and a thickness of 3 mm (the difference between the maximum value and the minimum value of the glass plate thickness is 1 to 2 μm) is used. The thickness of the glass plate at the first to fifth measurement points in FIG. 4 is measured in advance with a film thickness meter to obtain the “thickness of the glass plate (μm)”. Similarly, a sapphire plate having a diameter of 100 mm and a thickness of 900 μm (the difference between the maximum value and the minimum value of the sapphire plate thickness is 1 to 2 μm) is measured as “sapphire thickness (mm)”. Then, sapphire is bonded together using Examples 1-5 and Comparative Example 1 on a glass plate using a bonding apparatus. Make 5 pieces of pasted together. Each example and comparative example were made in 5 sheets. The bonding was performed by the following bonding apparatus, the bonding temperature was set to 90 ° C. for the upper and lower heaters, and the pressure was set so that 110 kg was applied per sheet. After the temperature reaches room temperature, all the thicknesses at the first to fifth measurement points as shown in FIG. 4 are measured by a film thickness measuring instrument to be “all thicknesses (mm)”. The thickness obtained by subtracting “glass plate thickness” and “wafer thickness” from “all thicknesses” is referred to as “thickness of temporarily fixed portion (μm)”. The average value, maximum value, and minimum value of the thickness of the temporarily fixed portion are obtained, and the difference between the maximum value and the minimum value of the “temporarily fixed portion thickness” is defined as “tolerance (μm)”. The closer the “tolerance” is to 0 μm, the better the bonding accuracy, and the range of 0 to 10 μm is preferable. If the tolerance is larger than 10 μm, the sapphire plate is excessively distorted, so that the sapphire plate is polished obliquely during polishing.
Equipment used Thickness measuring instrument: Micro gauge PMU150-25DM manufactured by Mitutoyo Corporation
Bonding device: Vacuum press heater manufactured by Mikado Equipment Sales Co., Ltd.
MKP-500V-WH-ST

In Examples 1 to 5, verification is performed using two types of non-reactive compositions and three types of base materials, and Comparative Example 1 is a state of only non-reactive compositions not using a base material. From the result of tolerance measurement, in the case of a temporarily fixed sheet, since it has the thickness of the base material even if it is the thinnest, the average value of the “thickness of the temporarily fixed portion” is thicker than the thickness of the base material. In the case of Comparative Example 1 that does not have, the “thickness of the temporarily fixed portion” is close to zero. However, looking at the tolerance that is the difference between the maximum value and the minimum value, the tolerance of 14 μm is generated in Comparative Example 1, but in all of Examples 1 to 5, the tolerance is smaller than 6 μm. Therefore, in the embodiment, the adherend can be stably polished and ground by keeping the tolerance low.

Along with miniaturization and high performance of electronic components, high precision is required in polishing grinding of wafers and the like, and it is also required to improve production efficiency. The present invention is a non-reactive composition that satisfies these requirements, and can be used for polishing grinding of metals such as various wafers.

The symbols in FIGS.
1: Carrier 2: Temporary fixing sheet 3: Wafer (Substrate)
4: Nozzle 5: Slurry 6: Pad conditioner 7: Platen 8: Pad 9: Digital force gauge head moving at a constant speed (main unit omitted)
10: Temporarily fixed glass plate 11: Fixing jig 12: Sapphire substrate 13: Glass plate 14: First measurement point 15: Second measurement point 16: Third measurement point 17: Fourth measurement point 18: Fifth measurement point

Claims (4)

A temporary fixing sheet having a thickness of 10 μm to 1 mm, in which a non-reactive composition having a melting point of 40 to 90 ° C. is impregnated into a nonwoven fabric or a porous sheet. The temporary fixing sheet impregnated with the non-reactive composition according to claim 1, comprising at least one selected from thermoplastic resins or elastomers composed of hydrocarbons that are solid at 25 ° C. The temporary fixing sheet impregnated with the non-reactive type composition according to any one of claims 1 and 2, comprising a thermoplastic resin that is solid at 25 ° C and is polymerized only from an α-olefin having 16 to 35 carbon atoms. A manufacturing method in which an adherend is fixed by the temporarily fixing sheet according to claim 1, and the adherend is polished or ground.