TW202400364A - Grinding wheel for wafer thinning - Google Patents

Abstract

The present invention relates to a grinding wheel for wafer thinning, comprising: a substrate; a cushion layer disposed on the substrate, which has a thickness of 20 to 50 μm; and a grinding layer disposed on the cushion layer, which has a plurality of abrasive particles dispersed therein, and the average particle size of the abrasive particles is within the range of 0.05 to 5 μm. The grinding wheel for wafer thinning of the present invention can not only exhibit the effect of the cushion layer to alleviate the external force and reduce the damage of the components, but also maintain its good precision.

Description

Grinding wheel for wafer thinning

The present invention relates to a grinding wheel, particularly a grinding wheel for wafer thinning.

At this stage, grinding-related technologies have affected the semiconductor industry in various aspects, such as wafer thinning (or wafer thinning) or wafer planarization, which also involves mechanical wheel grinding (Grinding). and various technologies such as chemical mechanical polishing (CMP).

Chemical mechanical polishing can flatten the wafer surface for subsequent production of integrated circuits. The process includes the use of abrasive slurries and polishing pads. The liquid in the abrasive slurries is corrosive, and the particles in it can fill the fine grooves of the polishing pads. After being fixed, mechanical friction is provided to grind the wafer when the polishing pad rotates, reducing the roughness of the wafer surface and achieving a polishing effect.

Mechanical wheel grinding is currently the most commonly used technology for wafer thinning, mainly due to its fast thinning speed, relatively low equipment cost and stable thinning quality. Specifically, mechanical wheel grinding uses a high-speed rotating spindle to drive a grinding wheel, and uses the abrasive particles on its surface to contact and interact with the working surface to achieve the purpose of grinding.

Since the above-mentioned technologies usually involve rapid and repetitive grinding processes, long-term use of grinding equipment may cause damage to its components due to collision, thus affecting the accuracy of subsequent finished products. In view of this, the technical features of adding a polymer buffer layer to the polishing pad used for CMP have been proposed in the prior art (such as the case of the Republic of China Invention Patent Announcement No. TW I410299B); also see the related issue of setting up a spring structure inside the polishing layer. Content (such as the case of the People's Republic of China Invention Patent Publication No. CN 105397650A).

After observation, the inventor found that the provision of the buffer layer may lead to a decrease in the accuracy of the grinding wheel used for wafer thinning. Therefore, a review of the prior art shows that it is usually only used in polishing and grinding equipment; however, the processing of the polishing process Efficiency, processing costs and environmental sustainability costs are all relatively high. In view of this, the inventor found after further testing that when the particle size of the abrasive particles in the structure and the thickness of the buffer layer are within a certain numerical range, not only the buffer layer can exert its ability to slow down external forces and reduce the risk of component damage. It is more effective and can maintain the good precision of its grinding wheel. In other words, in practice, wafer thinning can be used to maximize processing procedures, thereby reducing the overall process cost and improving efficiency.

In view of this, on the one hand, the present invention provides a grinding wheel for wafer thinning, which includes: A substrate; a buffer layer located on the substrate, the buffer layer having a thickness of 20 to 50 μm; and a polishing layer located on the buffer layer, and the polishing layer has a plurality of abrasives dispersed therein particles, and the average particle size of the abrasive particles ranges from 0.05 to 5 μm.

Another aspect of the present invention provides a grinding wheel for wafer thinning, which includes: a substrate; a first adhesive layer provided on the substrate; a buffer layer provided on the first adhesive layer, the buffer layer The thickness is 20 to 50 μm; a second adhesive layer is provided on the buffer layer; and a polishing layer is provided on the second adhesive layer, and the polishing layer has a plurality of abrasive particles dispersed therein , and the particle size of the abrasive particles ranges from 0.05 to 5 μm.

According to an embodiment of the present invention, the buffer layer includes a metal material. Preferably, the structural metal material is a metal sheet with a periodic structure. More preferably, the thickness of the metal material is 1 to 50 μm.

According to an embodiment of the present invention, the buffer layer includes a polymer elastomer. Preferably, the polymer elastomer is siloxane resin.

According to an embodiment of the present invention, the first adhesive layer and/or the second adhesive layer is epoxy resin.

According to an embodiment of the present invention, the grinding layer has a grinding tip, and the grinding tip is blade-shaped, conical, arc-shaped, cylindrical, pyramid-shaped or prism-shaped. Preferably, the abrasive particles are selected from the group consisting of diamond, cubic boron nitride, aluminum oxide, cerium oxide and silicon carbide.

According to an embodiment of the present invention, the substrate is selected from the group consisting of stainless steel, mold steel, metal alloys, ceramics and plastics.

Compared with the prior art, the grinding wheel for wafer thinning of the present invention is provided with a buffer layer, and its thickness and the particle size of the abrasive particles are defined to be within a certain numerical range; thereby, the grinding wheel for wafer thinning not only It can have the effect of slowing down external forces and reducing damage to components played by the buffer layer, and can also maintain its good accuracy. In other words, in practice, wafer thinning can be used to maximize processing procedures, thereby reducing the overall process cost and improving efficiency.

The following embodiments should not be considered as unduly limiting the present invention. Those skilled in the art may make modifications and changes to the embodiments discussed herein without departing from the spirit or scope of the invention, while still falling within the scope of the invention.

The terms "a" and "an" in this article represent one or more than one (ie at least one) grammatical object in this article.

First, the present invention provides a grinding wheel for wafer thinning, which includes: a substrate; a buffer layer provided on the substrate; and a polishing layer provided on the buffer layer, and the polishing layer has a plurality of Abrasive particles dispersed in it. On the other hand, the present invention provides a grinding wheel for wafer thinning, which includes: a substrate; a first adhesive layer provided on the substrate; a buffer layer provided on the first adhesive layer; Two adhesive layers are provided on the buffer layer; and a polishing layer is provided on the second adhesive layer, and the polishing layer has a plurality of abrasive particles dispersed therein.

The "substrate" referred to in this article is composed of one or more of stainless steel, metal materials, plastic materials, and ceramic materials; in practice, it only needs to be able to bear the grinding layer. Preferred materials may be metal substrates, metal alloy substrates, stainless steel substrates or mold steel substrates. More specifically, the metal substrate includes but is not limited to copper, iron, aluminum, titanium or tin; the metal alloy substrate includes but is not limited to iron alloy, copper alloy, aluminum alloy, titanium alloy or magnesium alloy.

The "adhesive layer" referred to herein refers to a structure used to bond adjacent layers. Specifically, the materials of the first/second adhesive layer are selected from the group consisting of pressure-sensitive adhesive, one-liquid paste, two-liquid paste, acrylic resin and epoxy resin; preferably Ground, the materials of the first adhesive layer and the second adhesive layer are both epoxy resin. Pressure-sensitive adhesive usually includes a carrier film, which includes polyester and has a fluid adhesive layer on the upper and lower sides of the carrier film. One-component paste refers to a paste containing a high molecular weight elastomer as an adhesive, preferably polyurethane, and one-component paste includes oil-modified paint and moisture-hardening paint. Acrylic resin includes room temperature hardening type and heat hardening dry type; the room temperature hardening type is mainly acrylic resin monomer, and the heat hardening dry type is based on acrylic resin polymer as the basic structure, with active reactive groups introduced into it. , when heated, the resin reacts alone or with a resin containing reactive groups and a cross-linking agent to form a three-dimensional network structure. Epoxy resin can further form a three-dimensional structure by adding cross-linking agents.

The "buffer layer" referred to in this article refers to a layer that provides the effect of mitigating external forces on the device; in some cases, the material of the buffer layer may have a higher compressibility than other parts. The thickness of the buffer layer is 20 to 50 μm, for example: 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 , 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or 50μm.

According to some embodiments of the present invention, the buffer layer includes a metal material; specifically, the metal material is selected from the group consisting of iron, cobalt, nickel, chromium, manganese, silicon, and aluminum. Furthermore, the metal material is a metal sheet with a periodic structure. The term "metal sheet with periodic structure" referred to herein refers to a metal sheet provided with repetitive and regularly arranged microstructures; preferably, the microstructure can be an elastic structure. According to some specific embodiments of the present invention, the thickness of the metal material is 1 to 50 μm, such as: 1, 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50 μm.

According to some embodiments of the present invention, the buffer layer includes a polymer elastomer. As used herein, "polymer elastomer" is a class of polymers that exhibit rubber-like qualities. According to some embodiments of the present invention, the material of the polymer elastomer is selected from the group consisting of resin, polymer, polymer composite material, epoxy resin and siloxane resin; preferably, the buffer layer includes Siloxane resin.

The "abrasive layer" referred to herein is a layer used to carry the plurality of abrasive particles and is attached to the substrate. The abrasive particles are mainly embedded and fixed in the abrasive layer. Specifically, the selection of materials for the grinding layer includes brazing materials, electroplating materials, ceramic materials, metal materials or polymer materials, and the present invention is not limited thereto. Furthermore, the brazing material, the electroplating material or the metal material is selected from the group consisting of iron, cobalt, nickel, chromium, manganese, silicon, and aluminum; and the polymer material includes epoxy resin, polyester Resin, polyacrylic resin or phenolic resin; in addition, the ceramic material includes various metal oxides, nitrides, carbides, borides, silicides or combinations thereof, such as silicon carbide, silicon nitride, aluminum nitride, oxide Aluminum, titanium carbide, titanium boride or boron carbide, etc.

"Abrasive particles" as referred to herein are selected from the group consisting of natural diamonds, man-made diamonds, polycrystalline diamonds, cubic boron nitride, aluminum oxide, cerium oxide and silicon carbide. The outer shape of the abrasive particles may be, but is not limited to, pyramidal, conical, arc-shaped, cylindrical, blade-shaped or prism-shaped. The average particle size of the abrasive particles ranges from 0.05 to 5 μm; for example: 0.05, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 μm.

Example 1

Example 1 of this case is used to specifically demonstrate the grinding wheel for wafer thinning provided by the present invention. FIG. 1 illustrates the stacked structure of a grinding wheel 100A for wafer thinning according to Embodiment 1 of the present invention. The wafer thinning grinding wheel 100A includes a substrate 110, and a buffer layer 130 and a grinding layer 150 are sequentially provided above the substrate 110. The buffer layer 130 has a thickness D. The grinding layer 150 includes a plurality of abrasive particles 152, and the plurality of abrasive particles have a particle diameter d. Specifically, the buffer layer 130 is directly disposed on the substrate 110 , and the polishing layer 150 is directly disposed on the buffer layer 130 .

On the other hand, the thickness D is 20 to 50 μm, for example: 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37 , 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or 50μm. The particle size d is 0.05 to 5 μm; for example: 0.05, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 μm.

Example 2

Example 2 of this case is used to specifically demonstrate the grinding wheel for wafer thinning provided by the present invention. FIG. 2 shows the stacked structure of a grinding wheel 100B for wafer thinning according to Embodiment 2 of the present invention. The structure of the wafer thinning grinding wheel 100B is substantially similar to the structure of the wafer thinning grinding wheel 100A in Embodiment 1. The difference between the two is that in the wafer thinning grinding wheel 100B, the buffer layer 130 and the substrate 110 and between the polishing layer 150 and the buffer layer 130 are further provided with an adhesive layer 120 (the first adhesive layer and the second adhesive layer respectively).

Example 3

Example 3 of this case is used to specifically demonstrate the grinding wheel for wafer thinning provided by the present invention. FIG. 3 shows the stacked structure of a grinding wheel 100C for wafer thinning according to Embodiment 3 of the present invention. The structure of the wafer thinning grinding wheel 100C is substantially similar to the structure of the wafer thinning grinding wheel 100B in Embodiment 2. The difference between the two is that the buffer layer 130 is provided with a plurality of periodic structures 130S. Specifically, the complex periodic structures 130S are hollow structures with a fixed spacing therebetween. According to a preferred embodiment of the present invention, the plurality of periodic structures 130S can be respectively an elastic structure or a support structure; for example, a spring.

Analysis of force changes over time

Here, the inventor of the present case tested the changes in the external force experienced by the grinding wheel for wafer thinning according to the embodiment of the present case and the conventional grinding wheel when grinding the workpiece over time. Figure 4 shows the force changes of grinding wheel A over time during the process of grinding workpiece B. As shown in Figure 4, the horizontal axis presents time (unit is ms), while the vertical axis presents the external force on the grinding wheel (unit is N). The embodiments are represented by solid lines in the figure, while conventional grinding wheels are represented by dotted lines. Specifically, in this test, the grinding system of the grinding wheel adopts a fixed-speed feed mode.

It can be seen from Figure 4 that within a certain period of time, the change in external force experienced by the wafer thinning grinding wheel in the process of grinding the workpiece according to the embodiment of the present invention is substantially smoother and more stable than that of conventional grinding wheels, and is not It is like a conventional grinding wheel with a sudden increase in stress during the test.

Without being limited by a specific theory, the thickness of the polishing layer is about 5 to 500 times the thickness of the buffer layer, preferably 100 to 350 times, and more preferably 120 to 200 times.

In summary, based on the definition of the grinding wheel for wafer thinning of the embodiment, the external force experienced during the grinding process can be substantially reduced compared with conventional grinding wheels. It can be understood from this that the grinding wheel for wafer thinning of the present invention not only has the effect of buffering the external force and reducing component damage, but also maintains its good accuracy, which can further improve the processing efficiency of the process in practice. Processing costs and environmental sustainability costs.

The present invention has been described in detail above. However, what is described above is only one of the preferred embodiments of the present invention. It should not be used to limit the scope of the present invention. That is, all claims based on the patent scope of the present invention are equal. Changes and modifications should still fall within the scope of the patent of the present invention.

100A, 100B, 100C: Grinding wheels for wafer thinning 110:Substrate 120: Adhesive layer 130:Buffer layer 130S: Periodic structure 150: grinding layer 152:Abrasive particles A:Grinding wheel B: workpiece D:Thickness d: particle size

In order to make the above and other objects, features, advantages and embodiments of the present invention easier to understand, the accompanying drawings are described as follows: 1 to 3 are schematic cross-sectional views of grinding wheels for wafer thinning according to different embodiments of the present invention. Figure 4 is a schematic diagram comparing the force changes of the grinding wheel over time.

In accordance with common practice, the various features and components in the figures are not drawn to actual scale, but are drawn in a manner intended to best present the specific features and components relevant to the present invention. In addition, the same or similar element symbols are used to refer to similar elements and components between different drawings.

A:Grinding wheel

B: workpiece

Claims (11)

A grinding wheel for wafer thinning, which includes: a substrate; A buffer layer is provided on the substrate, the thickness of the buffer layer is 20 to 50 μm; and A polishing layer is provided on the buffer layer, and the polishing layer has a plurality of abrasive particles dispersed therein, and the average particle size of the abrasive particles ranges from 0.05 to 5 μm. A grinding wheel for wafer thinning, which includes: a substrate; a first adhesive layer located on the substrate; A buffer layer is provided on the first adhesive layer, the thickness of the buffer layer is 20 to 50 μm; a second adhesive layer located on the buffer layer; and A polishing layer is provided on the second adhesive layer, and the polishing layer has a plurality of abrasive particles dispersed therein, and the particle size of the abrasive particles ranges from 0.05 to 5 μm. For example, the grinding wheel for wafer thinning of claim 1 or 2, wherein the buffer layer includes a metal material. For example, the grinding wheel for wafer thinning of claim 3, wherein the metal material is a metal sheet with a periodic structure. For example, the grinding wheel for wafer thinning of claim 4, wherein the thickness of the metal material is 1 to 50 μm. For example, the grinding wheel for wafer thinning according to claim 1 or 2, wherein the buffer layer includes a polymer elastomer. A grinding wheel for wafer thinning according to claim 6, wherein the polymer elastomer is siloxane resin. For example, the grinding wheel for wafer thinning of claim 2, wherein the first adhesive layer and/or the second adhesive layer is epoxy resin. Such as the grinding wheel for wafer thinning according to claim 1 or 2, wherein the grinding layer has a grinding tip, and the grinding tip is blade-shaped, conical, arc-shaped, cylindrical, pyramid-shaped or prism-shaped. For example, the grinding wheel for wafer thinning of claim 9, wherein the abrasive particles are selected from the group consisting of diamond, cubic boron nitride, aluminum oxide, cerium oxide and silicon carbide. For example, the grinding wheel for wafer thinning of claim 1 or 2, wherein the substrate is selected from the group consisting of stainless steel, mold steel, metal alloys, ceramics and plastics.

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