# Patent

## Title
Apparatus and method of separating wafer from carrier

## Abstract

A method of separating a wafer from a carrier includes placing a wafer assembly on a platform. The wafer assembly includes the wafer, the carrier, and a layer of wax between the wafer and the carrier. A wafer frame is mounted on the wafer of the wafer assembly. The layer of wax is softened. The wafer and the wafer frame mounted thereon are separated, by a first robot arm, from the carrier.

## Background
BACKGROUND
The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits formed on larger wafers than the previous generation. Technologies, such as three-dimensional integrated circuits (3D ICs) and through silicon vias (TSVs), are also used to further decrease the number and length of interconnections between electrical components formed on the ICs as the number of electrical components increases. In some applications, the 3D IC and TSV technologies include performing a backside thinning (or grinding) process to a wafer for obtaining thinner chips or dies. This is accomplished by mounting a front side of the wafer to a carrier and then removing a predetermined amount of material from the back side of the wafer after the electrical components for the circuit and/or TSVs have been fabricated on the front side of the wafer.



DESCRIPTION OF THE DRAWINGS
One or more embodiments are illustrated by way of examples, and not by limitation, in the figures of the accompanying drawings, wherein elements having the same reference numeral designations represent like elements throughout and wherein:
FIG. 1A is a perspective view of a wafer assembly in accordance with one or more embodiments;
FIG. 1B is a perspective view of a wafer assembly and a wafer frame mounted thereon, and an enlarged cross-sectional partial view of the wafer frame in accordance with one or more embodiments;
FIG. 1C is a perspective view of a wafer separated from a carrier in accordance with one or more embodiments;
FIG. 2 is a system block diagram of an apparatus usable for separating a wafer from a carrier in accordance with one or more embodiments;
FIG. 3 is a flow chart of a method of separating a wafer from a carrier in accordance with one or more embodiments; and
FIGS. 4A-4D are system block diagrams of an apparatus at various operating stages in accordance with one or more embodiments.



DETAILED DESCRIPTION
It is understood that the following disclosure provides many different embodiments, or examples, for implementing different features of the disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, examples and are not intended to be limiting. In accordance with the standard practice in the industry, various features in the drawings are not drawn to scale and are used for illustration purposes only.
The formation of a feature on, connected to, and/or coupled to another feature in the present disclosure that follows may include embodiments in which the features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the features, such that the features may not be in direct contact. In addition, spatially relative terms, for example, “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top,” “bottom,” etc. as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) are used for ease of the present disclosure of one features relationship to another feature. The spatially relative terms are intended to cover different orientations of the device including the features.
FIG. 1A is a perspective view of a wafer assembly 100 in accordance with one or more embodiments. The wafer assembly 100 includes a wafer 110, a carrier 120, and a layer of wax 130 between the wafer 110 and the carrier 120. The wafer 110 has an upper surface 112, a lower surface 114, and a cut mark 116 (such as a V-shape notch) that is usable to identify an orientation of the wafer 110. In some embodiments, the cut mark 116 is also usable to identify a material used to form a substrate of the wafer 110. The carrier 120 has an upper surface 122 and a lower surface 124. The upper surface 122 of the carrier 120 and the lower surface 114 of the wafer 110 sandwich and are bonded together by the layer of wax 130. In at least one embodiment, the wafer assembly 100 is usable for performing a back side grinding process on the wafer 110.
In some embodiments, the wafer 110 is a semiconductor wafer having a semiconductor substrate and a plurality of electrical components formed on a front side of the substrate. In at least one embodiment for performing a back side grinding process on a back side of the substrate, the lower surface 114 of the wafer 110 corresponds to the front side of the substrate, and the upper surface 112 of the wafer 110 corresponds to the back side of the substrate. In some embodiments, the wafer 110 has a thickness ranging from 10 μm to 200 μm. In some embodiments, the wafer 110 has a diameter greater than 100 mm. In at least one embodiment, the wafer 110 has a diameter of 450 mm.
In some embodiments, the carrier 120 comprises a material including silicon, metal, or glass. In some embodiments, a thickness of the carrier 120 ranges from 700 μm to 1000 μm. In at least one embodiment, the carrier 120 maintains an overall rigidity and an overall thickness of the wafer assembly 100 when performing the back side grinding process on the wafer 110. By maintaining the rigidity and thickness of the wafer assembly 100, the risks of warpage and cracking of the wafer 110 caused during the back side grinding process and the transportation of the wafer 110 before, during, and after the back side grinding process decrease. In some embodiments, the carrier 120 has a size and shape substantially the same as the wafer 110.
In some embodiments, the layer of wax 130 is capable of retaining the wafer 110 to the carrier 120 during the back side grinding process. In some embodiments, the wax material of the layer of wax 130, at a temperature less than a threshold temperature, is in solid state or in liquid state having a viscosity coefficient greater than a predetermined value at least sufficient to withstand the torque caused during the back side grinding process. In some embodiments, the wax material of the layer of wax 130, at a temperature equal to or greater than the threshold temperature, is in liquid state having a viscosity coefficient equal to or less than the predetermined value. In some embodiments, the threshold temperature ranges from 100° C. to 120° C. In some embodiments, a thickness of the layer of wax 130 ranges from 3 μm to 5 μm.
FIG. 1B is a perspective view of the wafer assembly 100 and a wafer frame 140 mounted thereon and an enlarged cross-sectional partial view of the wafer frame 140 taken at plane A in accordance with one or more embodiments. The wafer assembly 100 having the wafer frame 140 mounted thereon is usable as an intermediate product before separating the wafer 110 from the carrier 120.
The wafer frame 140 is mounted on the upper surface 112 of the wafer 110. The wafer frame 140 includes a ring shape frame 142 and a tape 144. The ring shape frame 142 has an upper surface 143, and the tape 144 is attached to the upper surface 112 of the wafer 110 and the upper surface 143 of the ring shape frame 142. The ring shape frame 142 has a hollow region 145 defined therein. The tape 144 extends over the hollow region 145 and has an adhesive material that binds the wafer 110, the tape 144, and the ring shape frame 142 as one piece.
In some embodiments, the ring shape frame 142 has any size and shape. In at least one embodiment, the ring shape frame 142 defines a circular hollow region 145 having an area larger than an area of the wafer 110. In some embodiments, the ring shape frame 142 has a shape that fits a container used to transport the ring shape frame 142. In some embodiments, the ring shape frame 142 comprises a plastic material. In some embodiments, the ring shape frame 142 comprises a metallic material including stainless steel, which is more rigid and less vulnerable to corrosion than using a plastic material. In some embodiments, the ring shape frame 142 has a thickness ranging from 0.7 mm to 1.6 mm.
In some embodiments, the adhesive material of the tape 144 is releasable under electromagnetic radiation of a predetermined wavelength. In at least one embodiment, the predetermined wavelength is within an ultraviolet spectrum. In some embodiments, “ultraviolet spectrum” refers to electromagnetic radiation having a wavelength ranging from 10 nm to 400 nm.
FIG. 1C is a perspective view of the wafer 110 already separated from the carrier 120 (FIG. 1A and FIG. 1B) in accordance with one or more embodiments. After the separation of the wafer 110 and the carrier 120, the wafer frame 140 is usable for supporting and transporting the wafer 110. By mounting the wafer frame 140 to the wafer 110, the risks of warpage and cracking of the wafer 110 caused during transport of the wafer 110 decrease.
FIG. 2 is a system block diagram of an apparatus 200 usable for separating a wafer (such as wafer 110 in FIGS. 1A-1C) from a carrier (such as carrier 120 in FIGS. 1A-1B) in accordance with one or more embodiments.
The apparatus 200 includes a platform 210 having an upper surface 212, a tape feeding unit 220, robot arms 230 and 240, an alignment sensor 250, and a controller 260 electrically coupled to the platform 210, the tape feeding unit 220, the robot arms 230 and 240, and the alignment sensor 250. The apparatus 200 also includes a container 270 for storing ring shape frames (such as ring shape frame 142 in FIGS. 1B-1C). In some embodiments, the container 270 is placed outside the apparatus 200. In some embodiments, the container is a front opening universal pod (FOUP) that is suitable for being transported by a FOUP transportation system.
During operation of the apparatus 200, two other containers 282 and 284 are positioned within reach of either one or both of the robot arms 230 and 240. In some embodiments, the container 282 is usable to store wafer assemblies (such as wafer assembly 100 in FIG. 1A) to be processed for separating the wafer 110 from the carrier 120 of the wafer assembly 110 by the apparatus 200. In some embodiments, the container 284 is usable to store the wafer 110 after the wafer 110 is separated from the corresponding carrier 120. In some embodiments, the containers 282 and 284 are FOUPs.
In some embodiments, the robot arm 230 is configured to obtain the wafer assembly 100 from the container 282 outside the apparatus 200 and to place the wafer assembly 100 on the upper surface 212 of the platform 210. In some embodiments, the robot arm 230 is also configured to move the wafer assembly 100 to the alignment sensor 250. In some embodiments, the robot arm 240 is configured to move the ring shape frame 142 to the upper surface 212 of the platform 210. In some embodiments, the robot arm 240 is configured to move the wafer 110 to the container 284 after the wafer 110 is separated from the carrier 120. In some embodiments, one of the robot arms 230 and 240 is capable of moving various components among various units of the apparatus 200, and thus the other one of the robot arms 230 and 240 is omitted.
In some embodiments, the platform 210 is a chuck table capable of securing the carrier 120 on the upper surface 212 of the platform 210. In some embodiments, the chuck table secures the carrier 120 by a vacuum device or by an electrostatic device. In some embodiments, the platform 210 is rotatable about a rotational axis 214 of the platform 210. In at least one embodiment, the platform includes a heater that is usable to adjust a temperature at the upper surface 212 of the platform 210.
In some embodiments, the controller 260 controls the movement of the robot arms 230 and 240. In some embodiments, the controller 260, by using the alignment sensor 250, detects a wafer orientation of the wafer assembly 100 and positions, by controlling the robot arm 230 or 240, the wafer assembly 100 on the upper surface 212 of the platform 210 according to the detected wafer orientation. In some embodiments, the controller 260 controls the tape feeding unit 220 to mount a wafer frame 140 on the wafer 110. In some embodiments, the controller 260 controls the rotation of the platform 210. In some embodiments, the controller 260 controls the heater of the platform 210.
FIG. 3 is a flow chart of a method 300 of separating a wafer 110 (FIG. 1A) from a carrier 120 (FIG. 1A) in accordance with one or more embodiments. FIGS. 4A-4D are system block diagrams of the apparatus 200 at various operating stages in accordance with one or more embodiments. It is understood that additional processes may be performed before, during, and/or after the method 300 depicted in FIG. 3, and that some other processes may only be briefly described herein.
As depicted in FIG. 3, in operation 310, a wafer assembly 100 is placed on the upper surface 212 of the platform 210. In at least one embodiment, operation 310 includes operation 312, operation 314, and operation 316. As depicted in FIG. 3 and FIG. 4A, in operation 312, the wafer assembly 100 is removed from the container 282 by the robot arm 230. In operation 314, the robot arm 230 then transports the wafer assembly 100 to the alignment sensor 250. In at least one embodiment, the movement of the robot arm 120 is controlled by the controller 260.
In some embodiments, the detection of the wafer orientation of the wafer assembly 100 is performed by detecting a position of the cut mark 116 of the wafer 110 with regard to the position of the robot arm 230. In at least one embodiment, the detection of the movement of the wafer orientation is performed by the controller 260 in conjunction with the alignment sensor 250.
As depicted in FIG. 3 and FIG. 4B, in operation 316, the wafer assembly 100 is positioned onto the upper surface 212 of the platform 210 according to the detected wafer orientation. In at least one embodiment, the platform 210 is a chuck table having a vacuum device generating a suction force that pulls the wafer assembly 100 toward the upper surface 212 of the platform 210. In at least one embodiment, the platform is a chuck table having a electrostatic device generating a electrostatic force that pulls the wafer assembly 100 toward the upper surface 212 of the platform 210. In some embodiments, the wafer assembly 100 is secured on the platform 210 by the vacuum device or the electrostatic device. In some embodiments, the vacuum device or the electrostatic device is controlled by the controller 260.
As depicted in FIG. 3 and FIG. 4C, in operation 320, a wafer frame 140 is mounted on the wafer 110 (FIG. 1B) of the wafer assembly 100. In at least one embodiment, operation 320 includes operation 322 and operation 324. In operation 322, a ring shape frame 142 is removed from the container 270 and placed on the platform 210. As depicted in FIG. 1B, the ring shape frame 142 having a hollow region 145 defined therein. Returning to FIG. 4C, the ring shape frame 142 is positioned such that the wafer assembly 100 is in the hollow region 145. As depicted in FIG. 3, in operation 324, a tape 144 is applied on an upper surface 112 (FIG. 1B) of the wafer 110 and on an upper surface 143 (FIG. 1B) of the ring shape frame 142. In some embodiments, the controller 260 drives the platform 210 to a position under the tape feeding unit 220 and controls the tape feeding unit 220 to apply the tape 144 on the ring shape frame 142 and the wafer assembly 100. In some embodiments, the controller 260 drives the tape feeding unit 220 to a position above the platform 210 and controls the tape feeding unit 220 to apply the tape 144 on the ring shape frame 142 and the wafer assembly 100.
As depicted in FIG. 3 and FIG. 4C, in operation 330, the layer of wax 130 (FIG. 1B) is softened. In some embodiments, the softening of the layer of wax 130 includes heating the upper surface 212 of the platform 210 to a temperature that is equal to or greater than a predetermined temperature. In some embodiments, the predetermined temperature is set to be sufficient to allow a wax material of the layer of wax 130 to transit into a liquid state having a viscosity coefficient equal to or less than a predetermined value. In some embodiments, the predetermined temperature ranges from 100° C. to 120° C.
As depicted in FIG. 3 and FIG. 4D, in operation 340, the wafer 100 and the wafer frame 140 mounted thereon is separated from the carrier 120 by the robot arm 240. Operation 340 includes rotating the platform 210 (operation 342) and lifting the wafer frame 140 and the wafer 100 (operation 344). In at least one embodiment, the temperature at the upper surface 212 of the platform 210 is maintained equal to or greater than the predetermined temperature.
In operation 342, the platform 210 is controlled by the controller 260 to rotate at a predetermined rotational speed in order to facilitate the detachment of the wafer 110 from the carrier 120 by a torque generated by the rotation of the platform 210. In operation 344, the robot arm 240 is driven to lift the wafer frame 140. In some embodiments, the robot arm 240 is driven to cause a predetermined pressure at an interface between the wafer 110 and the layer of wax 130. In at least one embodiment, the robot arm 240 is driven to lift the wafer frame 140 at a predetermined speed.
In at least one embodiment, operation 342 and operation 344 are performed simultaneously. In some embodiment, operation 342 is omitted. In some embodiments, after the separation of the wafer 110 and the carrier 120, the wafer 100 and the wafer frame 140 mounted thereon are moved to the container 284. Also, after the separation of the wafer 110 and the carrier 120, a layer of wax residue 132 remains on the upper surface 122 (FIG. 1A) of the carrier 120. In some embodiments, a layer of wax residue (not shown) remains on the lower surface 114 of the wafer 110.
Returning to FIG. 3, in operation 350, the wafer 100 having the wafer frame 140 mounted thereon is rinsed to remove wax residue on the lower surface 114 of the wafer 110. In some embodiments, the wafer 110 and the wafer frame 140 mounted thereon are dipped in a wax-cleaning solution for a predetermined period of time. In some embodiments, the wax-cleaning solution comprises saponifier. In some embodiments, water or hot water is used to remove the wax residue instead of the wax-cleaning solution.
In accordance with some embodiments, a method of separating a wafer from a carrier includes placing a wafer assembly on a platform. The wafer assembly includes the wafer, the carrier, and a layer of wax between the wafer and the carrier. A wafer frame is mounted on the wafer of the wafer assembly. The layer of wax is softened. The wafer and the wafer frame mounted thereon are separated, by a first robot arm, from the carrier.
In accordance with some embodiments, an apparatus includes a platform having an upper surface, a tape feeding unit, a first robot arm, and a controller coupled to the platform, the tape feeding unit, and the first robot arm. The controller is configured to mount a wafer frame, by using the tape feeding unit, on a wafer of a wafer assembly on the upper surface of the platform. The wafer assembly includes the wafer, a carrier, and a layer of wax between the wafer and the carrier. The controller is also configured to heat the upper surface of the platform to a predetermined temperature and to separate, by the first robot arm, the wafer and the wafer frame mounted thereon from the carrier.
In accordance with some embodiments, a manufacture includes a wafer, a carrier, a layer of wax between the wafer and the carrier, a ring shape frame, and a tape. The layer of wax includes a wax material that is in solid state or in liquid state having a viscosity coefficient greater than a predetermined value. The ring shape frame has a hollow region defined therein. The tape is attached to an upper surface of the wafer and an upper surface of the ring shape frame.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.

## Claims

1. A method of separating a wafer from a carrier, the method comprising:
placing a wafer assembly on a platform, the wafer assembly including the wafer, the carrier, and a layer of wax between the wafer and the carrier;
mounting a wafer frame on the wafer of the wafer assembly;
softening the layer of wax;
separating, by a first robot arm, the wafer and the wafer frame mounted thereon from the carrier,
wherein the mounting the wafer frame, the softening the layer of wax, and the separating the wafer and the wafer frame are conducted with the carrier secured on an upper surface of the platform.

2. The method of claim 1, wherein the separation of the wafer and the carrier comprises rotating the platform at a predetermined rotational speed.

3. The method of claim 2, wherein the separation of the wafer and the carrier comprises driving the first robot arm to lift the wafer to cause a predetermined pressure at an interface between the wafer and the layer of wax.

4. The method of claim 1, wherein the separation of the wafer and the carrier comprises driving the first robot arm to lift the wafer at a predetermined speed.

5. The method of claim 1, wherein the wafer frame includes a ring shape frame having a hollow region defined therein and a tape extending over the hollow region, and the mounting of the wafer frame comprises:
placing the ring shape frame on the platform, the wafer assembly being in the hollow region; and
applying the tape on an upper surface of the wafer and on an upper surface of the ring shape frame.

6. The method of claim 1, wherein the softening the layer of wax includes heating the upper surface of the platform to a predetermined temperature.

7. The method of claim 6, wherein the predetermined temperature ranges from 100° C. to 120° C.

8. The method of claim 1, further comprising rinsing the wafer having the wafer frame mounted thereon to remove wax residue from a lower surface of the wafer.

9. The method of claim 8, wherein the rinse of the wafer comprises dipping the wafer and the wafer frame mounted thereon in a wax-cleaning solution or water.

10. The method of claim 9, wherein the wax-cleaning solution comprises saponifier.

11. The method of claim 1, wherein the mounting of the wafer frame is performed prior to the softening of the layer of wax.

12. The method of claim 1, wherein the placing the wafer assembly on the platform comprises:
obtaining the wafer assembly by a second robot arm;
detecting a wafer orientation by an alignment sensor; and
positioning the wafer assembly on the platform by the second robot arm according to the detected wafer orientation.

13. A method comprising:
mounting a wafer frame on a first surface of a wafer;
heating a layer of wax on a second surface of the wafer, the layer of wax being between the second surface of the wafer and a carrier and configured to bond the second surface of the wafer and the carrier prior to the heating operation; and
removing, by a robot arm, the wafer frame and the wafer from the carrier,
wherein the mounting the wafer frame, the heating the layer of wax, and the removing the wafer frame are conducted with the carrier secured on an upper surface of a platform.

14. The method of claim 13, further comprising causing the carrier to rotate during the removing operation.

15. The method of claim 13, wherein the wafer frame includes a ring shape frame having a hollow region defined therein and a tape extending over the hollow region, and the mounting the wafer frame comprises:
placing the wafer in the hollow region; and
applying the tape on the first surface of the wafer and on an upper surface of the ring shape frame.

16. The method of claim 13, wherein the heating the layer of wax comprises heating the layer of wax at a predetermined temperature ranging from 100° C. to 120° C.

17. The method of claim 13, further comprising removing wax residue from the second surface of the wafer after the mounting the wafer frame.

18. The method of claim 17, wherein the removing the wax residue comprises dipping the wafer and the wafer frame mounted thereon in a wax-cleaning solution or water.

19. The method of claim 18, wherein the wax-cleaning solution comprises saponifier.

20. A method comprising:
applying a tape on a first surface of a wafer and on an upper surface of a ring shape frame surrounding the wafer;
heating a layer of wax on a second surface of the wafer, the layer of wax being between the second surface of the wafer and a carrier and configured to bond the second surface of the wafer and the carrier prior to the heating operation;
removing, by a robot arm, the ring shape frame and the wafer from the carrier; and
removing wax residue from the second surface of the wafer,
wherein the applying the tape, the heating the layer of wax, and the removing the ring shape are conducted with the carrier secured on an upper surface of a platform.