Semiconductor tool

Abstract

A semiconductor tool includes a grinding wheel configured to rotate around a first axis, a chuck table configured to rotate around a second axis offset from the first axis, and a plurality of adjustment shafts disposed at a peripheral portion of the chuck table. The chuck table includes an edge contour where an edge of the grinding wheel is projected onto the chuck table, and a wheel center where a center of the grinding wheel is projected onto the chuck table. The plurality of adjustment shafts are configured to adjust an inclination of the chuck table, wherein each of the plurality of adjustment shafts are disposed on an extending line extending from the wheel center toward a point on the edge contour.

Description

BACKGROUND

[0001] Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductor layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon. Many integrated circuits are typically manufactured on a single semiconductor wafer. The dies of the wafer may be processed and packaged at the wafer level, and various technologies have been developed for wafer level packaging.BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

[0003] FIG. 1 illustrates a cross sectional view of a semiconductor tool according to some embodiments of the present disclosure.

[0004] FIG. 2 illustrates a bottom view of a grinding wheel of a semiconductor tool according to some embodiments of the present disclosure.

[0005] FIG. 3 illustrates a partial cross sectional view of the grinding wheel in FIG. 2.

[0006] FIG. 4A illustrates a top view of a grinding wheel and a chuck table of a semiconductor tool according to some embodiments of the present disclosure.

[0007] FIG. 4B illustrates a top view of a chuck table of a semiconductor tool according to some embodiments of the present disclosure.

[0008] FIG. 5 illustrates a side view of a semiconductor tool according to some embodiments of the present disclosure.

[0009] FIG. 6 illustrates cross sectional views of a semiconductor wafer before grinding process and after grinding process according to some embodiments of the present disclosure.

[0010] FIG. 7A illustrates a cross sectional view of a semiconductor tool according to some embodiments of the present disclosure.

[0011] FIG. 7B illustrates cross sectional views of a semiconductor wafer after grinding process according to some embodiments of the present disclosure.

[0012] FIG. 8A illustrates a cross sectional view of a semiconductor tool according to some embodiments of the present disclosure.

[0013] FIG. 8B illustrates cross sectional views of a semiconductor wafer after grinding process according to some embodiments of the present disclosure.

[0014] FIG. 9 illustrates an operation scenario of sensors detecting an inclination state of a semiconductor wafer according to some embodiments of the present disclosure.

[0015] FIG. 10 to FIG. 17 illustrate cross sectional views of intermediate stages in the manufacturing of a semiconductor package according to some embodiments of the present disclosure.

[0016] FIG. 18 illustrates a process flow of intermediate stages in a grinding process of a semiconductor wafer according to some embodiments of the present disclosure.

[0017] FIG. 19 illustrates a process flow of intermediate stages in a grinding process of a semiconductor wafer according to some embodiments of the present disclosure.DETAILED DESCRIPTION

[0018] The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and / or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and / or configurations discussed.

[0019] Further, spatially relative terms, such as “beneath,”“below,”“lower,”“above,”“upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0020] FIG. 1 illustrates a cross sectional view of a semiconductor tool according to some embodiments of the present disclosure. Referring to FIG. 1, in some embodiments, the semiconductor tool 10 shown in FIG. 1 may be a grinding apparatus 10, which is provided to perform a grinding process on one or more semiconductor wafer 300 and includes a grinding wheel 100, a chuck table 200, and a plurality of adjustment shafts 230. The method of grinding a semiconductor wafer 300 may using the grinding apparatus 10 shown in FIG. 1 may include the following steps. In some embodiments, the chuck table 200 is configured to receive one or more workpieces such as one or more semiconductor wafers (one semiconductor wafer 300 is illustrated herein) on a front surface of the chuck table 200. In some embodiments, the semiconductor wafer 300 may be placed by a robot or manually on the chuck table 200 with, for example, front-side of the semiconductor wafer 300 facing the chuck table 200 to hold the semiconductor wafer 300 on the chuck table 200. The chuck table 200 may hold the semiconductor wafer 300 down by vacuum, electrostatic charge (ESC) or the like. In an alternative embodiment, a double-sided tape, an edge clamp, or other suitable manner may also be used to secure the semiconductor wafer 300 to the chuck table 200.

[0021] As shown in FIG. 1, in some embodiments, a front surface of the chuck table 200, that is, a holding surface for holding the semiconductor wafer 300 and facing the grinding wheel 100 has a protruding shape. In other words, the front surface of the chuck table 200 has a central portion and an edge portion surrounding the central portion. In this embodiment, the central portion is higher than the edge portion when viewed from the side. In a grinding process (rough grinding and fine grinding), grinding wheel 100 to be described later comes into contact with the semiconductor wafer 300. The front surface of the chuck table 200 is formed to have the protruding shape and the semiconductor wafer 300 is attracted to conform to this front surface of the chuck table 200 so that the semiconductor wafer 300 is ground and polished into a uniform thickness.

[0022] In some embodiments, the chuck table 200 may include a base 220, and a chuck 210 disposed on the base 220. By way of example, a porous chuck may be used as the chuck 210. That is, a porous layer 212 as a porous body having a multiple number of holes therein is provided on the surface of the chuck 210. The porous layer 212 may be made of various kinds of materials as long as they are porous. By way of non-limiting example, the porous layer 212 may be made of carbon, alumina, silicon carbide, or the like. By suctioning the semiconductor wafer 300 via the porous layer 212 with a suction mechanism (not shown), the semiconductor wafer 300 is attracted to and held by the chuck 210.

[0023] A rotating shaft 240 and a plurality of adjustment shafts 230 may be coupled to the base 220 of the chuck table 200. The rotating shaft 240 is configured to drive the chuck table 200 to rotate around an axis A2. In some embodiments, the grinding wheel 100 is configured to rotate around a first axis A1, and the chuck table 200 is configured to rotate about a second axis A2 offset from the first axis A1. During the grinding process, the chuck table 200 and the grinding wheel 100 may be rotated in the same direction, or in different directions. In some embodiments, the chuck table 200 may be vertically movable with respect to the grinding wheel 100 by the using the adjustment shafts 230, such that the grinding wheel 100 can be in contact with the semiconductor wafer 300 for grinding.

[0024] After the semiconductor wafer 300 is placed on the chuck table 200, an inclination state of the semiconductor wafer 300 and / or the front surface of the chuck table 200 can be obtained by at least one sensor (e.g., the sensor 60 illustrated in FIG. 9). Then, an inclination of the front surface of the chuck table 200 (and / or an inclination of the semiconductor wafer 300) is adjusted by at least three adjustment shafts 230 according to the inclination state sensed by the sensor. As shown in FIG. 1, the adjustment shafts 230 are disposed at a peripheral portion of the chuck table 200 and functioned as a height adjuster to adjust an inclination of the chuck table 200 and the semiconductor wafer 300 disposed thereon. In detail, the chuck table 200 is supported by the rotating shaft 240 at the center and at least three adjustment shafts 232, 234, 236 disposed around the edge of the chuck table 200 that can extend and contract in the vertical direction (Z direction), and by independently adjusting the extension and contraction of the at least three adjustment shafts 232, 234, 236 in the Z direction, the altitude and inclination of the chuck table 200 with respect to the grinding wheel 100 can be controlled. In the present embodiment, each of the adjustment shafts 232, 234, 236 may include a cylinder operated independently for raising or lowering the corresponding portion of the chuck table 200. The adjustment shafts 232, 234, 236 may also be any mechanism capable of controlling the length in the Z direction. For example, a piezoelectric element may be used, or a ball screw is rotated by an electric motor to advance and retract a movable pin supporting the chuck table 200. In some embodiments, more than one of the adjustment shafts (e.g., the adjustment shafts 232, 236, but not limited thereto) raise or lower respective portions of the chuck table during adjusting the inclination of the chuck table.

[0025] In some embodiments, the semiconductor wafer 300 includes a semiconductor substrate, such as a bulk semiconductor substrate. The bulk semiconductor substrate may include an elementary semiconductor, such as silicon; a compound semiconductor, such as silicon germanium, silicon carbide; or combinations thereof. In some embodiments, the semiconductor wafer 300 includes a plurality of devices such as circuitries, transistors, etc. disposed over or in the semiconductor wafer 300. In some embodiments, the circuitries formed over or in the semiconductor wafer 300 may be any type of circuitries suitable for a particular application. In some embodiments, the semiconductor wafer 300 may include a CMOS substrate, or the like. In some embodiments, the semiconductor wafer 300 may include a stacked wafer. According to the present exemplary embodiment, the semiconductor wafer 300 is a substrate to be thinned. The semiconductor wafer 300 is a semiconductor wafer such as, but not limited to, a silicon wafer or a composite wafer. A device (not shown) is formed on a front surface FS of the semiconductor wafer 300, and a protective tape 301 for protecting the device is attached on the front surface FS of the semiconductor wafer 300. The semiconductor wafer 300 is thinned as preset processing such as grinding and polishing are performed on a back surface BS of the semiconductor wafer 300. However, the disclosure is not limited thereto. In other embodiments, the grinding and polishing process may also be performed on a front surface of the semiconductor wafer to remove the excess material (e.g., encapsulating material) that covers the front surface of the semiconductor wafer.

[0026] FIG. 2 illustrates a bottom view of a grinding wheel of a grinding apparatus according to some embodiments of the present disclosure. FIG. 3 illustrates a partial cross sectional view of the grinding wheel in FIG. 2. Referring to FIG. 1 to FIG. 3, in some embodiments, the semiconductor wafer 300 may be grinded by the grinding wheel 100 from, for example, the back surface BS to reduce the thickness and to thin and planarize the back surface BS of the semiconductor wafer 300. In some embodiments, the grinding wheel 100 may be driven to rotate by a motor (not shown). In some embodiments, the grinding wheel 100 includes a base disk 112 and a plurality of grinding teeth 114 protruding from a surface of the base disk 112. In some embodiments, the grinding wheel 100 may further includes a structural reinforcing element, a stress or impact absorbing layer, or the like. The base disk 112 may include a metal-based ring-shaped structure with a hollow region for heat dissipation and for removal of debris. In some embodiments, the material of the metal base 102 includes aluminum, steel, molybdenum, molybdenum alloys, titanium or titanium alloys.

[0027] In some embodiments, the grinding teeth 114 are mounted on the base disk 112 and facing the semiconductor wafer 300, so that the grinding teeth 114 functions as a grinding element mounted on the base disk 112 (main body) of the grinding wheel to exert grinding ability toward the structure / layer to be ground. In accordance with the embodiments, pitches between the grinding teeth 114 can be modified based on product design or the requirements of grinding capability. Various types of the grinding teeth 114 may be arranged with a uniform pitch or different pitches. In certain embodiments, a lower surface of the grinding teeth 114 is the contact surface during the grinding process and the lower surface will be in direct contact with a wafer surface of the semiconductor wafer 300. It is appreciated that the contact area or grinding area of the grinding wheel 100 varies along different moving trajectories of the grinding wheel, but the semiconductor wafer 300 such as a silicon wafer or the intermediate package structure should be ground as a whole, globally reducing the height (or thickness) with uniformity or ground to a specific profile.

[0028] In some embodiments, the grinding teeth 114 may include a base material 1141 and a plurality of grinding abrasives 1142 dispensed in the base material 1141. In some embodiments, the base material 1141 may include polymeric material, composite material or the like. The base material 1141 may be configured as a molding layer to fix the grinding abrasives 1142. By way of example, the grinding abrasives 1142 may be mixed in the base material 1141 in the form of fluid. After solidification, the plurality of grinding abrasives 1142 can be mounted within the base material 1141. The grinding abrasives 1142 may be randomly or uniformly distributed in the base material 1141.

[0029] In some embodiments, the plurality of grinding abrasives 1142 is ball type. The grinding abrasive 1142 may have a substantially rounding perimeter. By way of examples, the plurality of grinding abrasives 1142 may substantially have a spheroid shape, an oblate spheroid shape, a prolate spheroid shape, an ellipsoid shape, an oblate ellipsoid shape, a prolate ellipsoid shape or the like. In some embodiments, the plurality of grinding abrasives 1142 has a smooth surface such that damage to the semiconductor wafer 300 during grinding operation can be alleviated. In some embodiments, the plurality of grinding abrasives 1142 has, for example, a Mohs hardness substantially equal to or greater than 9 to enhance grinding effect. The Mohs hardness of the ball type grinding abrasives 1142 can be modified based on the material of the semiconductor wafer 300 to be grinded. In some embodiments, the plurality of grinding abrasives 1142 is made of metal ceramic composites. In some embodiments, the plurality of grinding abrasives 1142 is made of corundum, tungsten carbide, silicon carbide (carborundum), titanium carbide, boron, boron nitride, rhenium diboride, stishovite, titanium diboride, diamond, carbonado or the like.

[0030] FIG. 4A illustrates a top view of a grinding wheel and a chuck table of a semiconductor tool according to some embodiments of the present disclosure. FIG. 4B illustrates a top view of a chuck table of a semiconductor tool according to some embodiments of the present disclosure. FIG. 5 illustrates a side view of a semiconductor tool according to some embodiments of the present disclosure. Referring to FIG. 4A to FIG. 5, in some embodiments, the grinding wheel 100 is disposed over the chuck table 200 and configured to partially overlap with the chuck table 200 from a top view. Accordingly, when viewing from the top view shown in FIG. 4A, an edge (contour) of the grinding wheel 100 is projected onto the chuck table 200. In the embodiment, the edge contour EC of the grinding wheel 100 projected on the chuck table 200 passes a center O2 of the chuck table 200, and a wheel center O1 of the grinding wheel 100 projected onto the chuck table 200 falls on an edge of the chuck table 200. In other words, when viewing from the top view, the chuck table 100 includes an edge contour EC (encircled by a dotted frame), where an edge of the grinding wheel 100 is projected onto the chuck table 100, and the wheel center O1 where a center of the grinding wheel 100 is projected onto the chuck table 200. Referring to FIG. 4A and FIG. 4B, with such arrangement, each of the adjustment shafts 232, 234, 236 are disposed on an extending line extending from the wheel center O1 toward a point on the edge contour EC. In some embodiments, the chuck table includes an overlap portion that is overlapped with the grinding wheel 100 from the top view, and a supporting portion that is not overlapped with grinding wheel 100 from the top view. The adjustment shafts 232, 234, 236 are disposed at the supporting portion of the chuck table 200 to raise or lower the chuck table independently.

[0031] In accordance with some embodiments of the disclosure, the grinding apparatus 10 includes at least three adjustment shafts 232, 234, 236, which are disposed on the peripheral portion of the chuck table 200 and located on the extending lines extending from the wheel center O1 toward the corresponding point on the edge contour EC, and extended toward the edge of the chuck table 200. As shown in FIG. 4A, when viewing from the top view, the edge of the chuck table 200 and the edge of the grinding wheel 100 are intersected at an edge point P1 on the chuck table 200. The edge contour EC includes a first segment S1 (illustrated as a bold line), which is from the center O2 of the chuck table 200 to the edge point P1. The edge contour EC further includes a second segment, which is from the center O2 of the chuck table 200 to the middle point C1 of the first segment S1.

[0032] Referring to FIG. 4A and FIG. 4B, with such definition, in the embodiments, the (first) adjustment shaft 232 is disposed on an extending line extending from the wheel center O1 toward a middle point C1 of the first segment S1. In the present embodiment, the first adjustment shaft 232 is disposed around an intersection of such extending line and the edge of the chuck table 200. The (second) adjustment shaft 234 is disposed at a position where the wheel center, the first adjustment shaft 232, and the second adjustment shaft 234 form an equilateral triangle from a top view. The (third) adjustment shaft 236 is disposed on an extending line extending from the wheel center O2 toward a quarter point Q1, which is a midpoint of the second segment (e.g., the segment from the center O2 of the chuck table 200 to the middle point C1 of the first segment S1). In the present embodiment, the third adjustment shaft 236 is disposed around an intersection of such extending line and the edge of the chuck table 200.

[0033] Referring to FIG. 4B, with such configuration, when the first adjustment shaft 232 is controlled (by the controller 140 shown in FIG. 1) to vertically move 1 unit distance (i.e., displacement d1=1), the displacement d1 of the first adjustment shaft 232 would cause the edge point P1 to vertically move 0.7 unit distance (i.e., displacement d3=0.7), cause a middle point C1 of the edge segment S1 to vertically move 0.6 unit distance (i.e., displacement d4=0.6), and cause the center O2 of the chuck table 200 to vertically move 0.35 unit distance (i.e., displacement d5=0.35). That is, the ratio of the displacements d1: d3:d4:d5=1:0.7:0.6:0.35.

[0034] In addition, when the third adjustment shaft 236 is controlled to vertically move 1 unit distance (i.e., displacement d2=1), the displacement d2 of the third adjustment shaft 236 would cause the edge point P1 to vertically move 0.75 unit distance (i.e., displacement d3=0.75), cause a middle point C1 of the edge segment S1 to vertically move 0.65 unit distance (i.e., displacement d4=0.65), and cause the center O2 of the chuck table 200 to vertically move 0.4 unit distance (i.e., displacement d5=0.4). That is, the ratio of the displacements d2:d3:d4:d5=1:0.75:0.65:0.4. It is noted that the second adjustment shaft 234 herein can be seen as a reference point without moving, but the disclosure is not limited thereto.

[0035] FIG. 6 illustrates cross sectional views of a semiconductor wafer before grinding process and after grinding process according to some embodiments of the present disclosure. Referring to FIG. 4B to FIG. 6, when the third adjustment shaft 236 is vertically moved upward about 1 unit distance (i.e., displacement d2=1), the ratio of the displacements d3, d4, d5 of the edge point P1, the middle point C1, and the center O2 of the chuck table 200 is d3:d4:d5=0.75:0.65:0.4. Generally, the higher a point on the chuck table 200 is, the more grinding such point would endure. Accordingly, the edge point P1 would endure more grinding than the middle point C1, and the middle point C1 would endure more grinding than the center O2 of the chuck table 200. As such, after the grinding process with the third adjustment shaft 236 vertically moved upward about 1 unit distance, the thickness Te of the edge point P1 is thinner than the thickness Tm of the middle point C1, and the thickness Tm of the middle point C1 is thinner than the thickness Tc of the center O2 of the chuck table 200, so as to arrive at the profile of the ground semiconductor wafer 300a shown in FIG. 6.

[0036] In some exemplary embodiments, if the first adjustment shaft 232 and the third adjustment shaft 236 move for the same unit distance but in opposite direction, to be more specific, if the third adjustment shaft 236 is controlled to vertically move upward for about 1 unit distance (i.e., displacement d2=1), while the first adjustment shaft 232 is controlled to vertically move downward for about 1 unit distance (i.e., displacement d1=−1), the edge point P1 would be vertically moved about 0.05 unit distance (i.e., displacement d3=0.75−0.7=0.05), the middle point C1 of the edge segment S1 would be vertically moved about 0.05 unit distance (i.e., displacement d4=0.65−0.6=0.05), and the center O2 of the chuck table 200 would be vertically moved about 0.05 unit distance (i.e., displacement d5=0.4−0.35=0.05). That is, the ratio of the displacements d3:d4:d5=0.05:0.05:0.05. As such, the edge point P1, the middle point C1, and the center O2 of the chuck table 200 can be adjusted to be about the same level and the resolution of inclination tuning can be increased up to 7 times compared to the resolution of inclination tuning merely using one or two adjustment shafts. Therefore, by adjusting the lengths of the first adjustment shaft 232, the second adjustment shaft 234, and the third adjustment shaft 236, the inclination of the chuck table 200 can be tuned more precisely.

[0037] FIG. 7A illustrates a cross sectional view of a grinding apparatus according to some embodiments of the present disclosure. FIG. 7B illustrates cross sectional views of a semiconductor wafer after grinding process according to some embodiments of the present disclosure. After the inclination state of the chuck table 200 is adjusted by the adjustment shafts 232, 234, 236, a grinding process can be performed on at least a portion of the semiconductor wafer 300 by the grinding wheel 100. Referring to FIG. 7A and FIG. 7B, the chuck table 200 is adjusted by the adjustment shafts 232, 234, 236 to be tilted as the center portion of the chuck table 200 is higher than a peripheral portion of the chuck table 200. Accordingly, during the grinding process as illustrated in FIG. 7A, the central portion of the semiconductor wafer 300 comes into contact with the grinding wheel 100 before the peripheral portion of the semiconductor wafer 300. Therefore, the grinding is started with the central portion of the semiconductor wafer 300, and the back surface BS of the semiconductor wafer 300 is ground such that a ground region gradually expands to the peripheral portion. As a result, as illustrated in FIG. 7B, the semiconductor wafer 300b is ground such that a central portion of the back surface BS as a ground surface is recessed and the section along the diameter of the semiconductor wafer 300b becomes a centrally recessed shape. The semiconductor wafer 300b thus becomes a centrally recessed shape, e.g., a V-shaped wafer.

[0038] FIG. 8A illustrates a cross sectional view of a grinding apparatus according to some embodiments of the present disclosure. FIG. 8B illustrates cross sectional views of a semiconductor wafer after grinding process according to some embodiments of the present disclosure. Referring to FIG. 8A and FIG. 8B, the chuck table 200 is adjusted by the adjustment shafts 232, 234, 236 to be tilted as the central portion of the radius of the chuck table 200 is higher than a peripheral portion of the chuck table 200. Accordingly, during the grinding process as illustrated in FIG. 8A, the central portion of the radius in the semiconductor wafer 300 comes into contact with the grinding wheel 100 first, that is, before the central portion and the peripheral portion of the semiconductor wafer 300. Therefore, the grinding is started with the central portion of the radius, and the back surface BS of the semiconductor wafer 300 is ground such that the ground region gradually expands to the central portion and the peripheral portion of the semiconductor wafer 300. As a result, as illustrated in FIG. 8B, the semiconductor wafer 300c is ground such that the central part of the radius in the back surface BS as a ground surface is thinner than the central portion and the peripheral portion of the semiconductor wafer 300b and the section along the diameter of the semiconductor wafer 300c becomes a W-shape. The semiconductor wafer 300c thus becomes a W-shaped wafer.

[0039] FIG. 9 illustrates an operation scenario of sensors detecting an inclination state of a semiconductor wafer according to some embodiments of the present disclosure. Referring to FIG. 9, the grinding apparatus may further includes at least one sensor 60 for detecting and monitoring an inclination state of the semiconductor wafer 300 or an inclination state of the front surface 201 of the chuck table 200. In some embodiments, the sensor 60 may include a signal emitter (e.g., light emitter) 61 for emitting a signal 62 and a signal receiver (e.g., light receiver) 63 for receiving the reflected signal 64. The signal emitter is positioned at a first position above the chuck table 200 to transmit a signal at a predetermined transmission angle relative to a vertical axis of the chuck table 200 (or the axis A3 normal to the chuck table 200) at the intended reflectance point 68 to obtain an inclination of the semiconductor wafer 300 and / or the inclination of the chuck table 200, such that the signal 62 emitted by the signal emitter 61 is reflected from the semiconductor wafer 300. In the present embodiment, the sensor 60 is a non-contact sensor that do not contact the semiconductor wafer 300 during the grinding process. The sensor 60 may be parts of a reflectivity measurement tool, which is configured to measure the reflectivity by emitting signal (e.g., light) 62, measure the intensity of the reflected signal (e.g., light) 64, and calculating the reflectivity. Since the reflected signal 64 may be reflected from the surface and also from the internal features of the semiconductor wafer 300, the reflectivity may be a function of the surface materials and the materials buried under the surface of the semiconductor wafer 300. The reflectivity may also be a function of the topology of the features in the semiconductor wafer 300.

[0040] The signal receiver 63 is positioned at a second position above the chuck table 200 to receive the reflected signal 64 at a predetermined reflectance angle relative to the vertical axis of the chuck table 200 (or the axis normal to the chuck table 200) at the intended reflectance point 68. The predetermined positioning of the signal emitter 61 and the signal receiver 63 are based on a signal reflectance algorithm. During the grinding process, the signal 62 that is emitted by the signal emitter 61 is projected onto a point 68 (which actually forms a circle with the rotation of semiconductor wafer 300) of the semiconductor wafer 300. It is realized that even if the signal 62 may be projected to a fixed direction, with the spinning of the semiconductor wafer 300, at different time points, the signal 62 may be projected onto other features along a circle path 68 on the semiconductor wafer 300 such as dies 22, encapsulating material 30 between dies 22. The measured reflectivity is thus the averaged result obtained from circle path 68. Accordingly, the intended reflectance point 68 along a surface of the semiconductor wafer 300 is selected such that leveling at various points along the semiconductor wafer 300 may be determined, so as to obtain a plurality of displacements at the various points of the chuck table 200, or a relative angle between the grinding wheel 200 and the semiconductor wafer 300.

[0041] FIG. 10 to FIG. 17 illustrate cross sectional views of intermediate stages in the manufacturing of a semiconductor package, in which a grinding process is performed. FIG. 18 illustrates a process flow of intermediate stages in a grinding process of a semiconductor wafer according to some embodiments of the present disclosure. It is noted that FIG. 10 and FIG. 11 illustrates one of the possible processes of forming the semiconductor wafer 300 to be provided on the chuck table 200 shown in FIG. 12. However, the disclosure is not limited thereto, and other suitable form of wafer such as a bulk silicon wafer, any wafer-level package may also be applied herein. Accordingly, the semiconductor wafer 300 in FIG. 12 is illustrated in an abstract manner as a blank block for simplicity purposes.

[0042] Referring to FIG. 10, a carrier 40 is provided, and a release layer 41 is disposed over the carrier 40, and an adhesive layer 42 such as a die attach film (DAF) is disposed over the release layer 41. The carrier 40 may be a glass carrier, a ceramic carrier, or the like. The carrier 40 may have a round top-view shape and may have a size of a silicon wafer. The release layer 41 may be formed of a polymer-based material (such as a light to heat conversion (LTHC) material), which may be removed along with the carrier 40 from the overlying structures that will be formed in subsequent steps. In accordance with some embodiments of the present disclosure, the release layer 41 is formed of an epoxy-based thermal-release material, which will decompose under the heat of light. In accordance with other embodiments of the present disclosure, the release layer 41 is formed of a ultra-violet (UV) glue. The release layer 41 may also be a laminate film laminated onto the carrier 40. The top surface of the release layer 41 is leveled and has a high degree of co-planarity. The adhesive layer 42 is laminated over the release layer 41, and is used for allowing the subsequently placed a plurality of device dies 22 (shown in FIG. 11) to attach to the carrier 40.

[0043] Referring to FIG. 11, a plurality of device dies 22 are placed over the carrier 40 and attached to the carrier 40 through the adhesive layer 42. The device dies 22 may be logic device dies including logic transistors therein. In accordance with some exemplary embodiments of the present disclosure, the device dies 22 are designed for mobile applications. For example, the device dies 22 may be Power Management Integrated Circuit (PMIC) dies, Transceiver (TRX) dies, or the like. In accordance with some exemplary embodiments of the present disclosure, a plurality of metal contacts 26 (such as a copper post) are pre-formed at the top surfaces of the device dies 22, wherein the metal contacts 26 are electrically coupled to the integrated circuit devices such as transistors in the device dies 22. In accordance with some embodiments of the present disclosure, the top dielectric layer 28 (which may be a polymer layer) fills the gaps between the neighboring metal contacts 26. Top dielectric layer 28 may be formed of polybenzoxazole (PBO), polyimide, or another polymer in accordance with some embodiments.

[0044] Next, an encapsulating material 30 is provided over the carrier 40 to encapsulate the device dies 22 through a molding process. The resulting structure is shown in FIG. 11. The encapsulating material 30 fills the gaps between the device dies 22. The encapsulating material 30 may include a molding compound, a molding underfill, an epoxy, or a resin. The top surface of the encapsulating material 30 is higher than the top ends of metal contacts 26. Throughout the description, the carrier 40 and the overlying structures including the device dies 22 and the encapsulating material 30 are in combination referred to as the semiconductor wafer 300 (composite wafer). It is noted that, in the present embodiment, the device dies 22 are placed on the carrier 40 in a manner of its front surface facing upward (e.g., toward the grinding wheel 100 shown in FIG. 12), however, in other embodiments, the device dies 22 may also be placed on the carrier 40 in a manner of its back surface (e.g., semiconductor substrate) facing upward (e.g., toward the grinding wheel 100 shown in FIG. 12). The disclosure is not limited to which surface of the semiconductor wafer 300 to be ground by the grinding apparatus.

[0045] Then, at step S120, an inclination state of the semiconductor wafer 300 and / or the front surface of the chuck table 200 can be obtained by at least one sensor 60. Then, at step S130, an inclination of the front surface of the chuck table 200 and / or an inclination of the semiconductor wafer 300 is adjusted by the adjustment shafts 232, 234, 236 according to the inclination state sensed by the sensor 60. The adjustment shafts 232, 234, 236 are disposed at a peripheral portion of the chuck table 200 and functioned as a height adjuster to adjust an inclination of the chuck table 200 and the semiconductor wafer 300 disposed thereon. The adjustment shafts 232, 234, 236 are disposed around the edge of the chuck table 200 and configured to extend and contract in the vertical direction (Z direction), and by independently adjusting the extension and contraction of the adjustment shafts 232, 234, 236 in the Z direction, the altitude and inclination of the chuck table 200 with respect to the grinding wheel 100 can be controlled by the controller 140, which is coupled to the sensor 60, the chuck table 200, and the grinding wheel 100.

[0046] Referring to FIG. 12 and FIG. 18, then, at step S140, a grinding process is performed on at least a portion of the semiconductor wafer 300 by a grinding wheel 100, so as to thin the semiconductor wafer 300, for example, to thin the encapsulating material 30 until metal contacts 26 are exposed. The respective grinding process flow is also shown in FIG. 18. Due to the grinding, the top ends of metal contacts 26 are substantially coplanar with the top surface of encapsulating material 30 as shown in FIG. 13. For purpose of clarity and simplicity, detail description of same or similar features may be omitted, and the same or similar reference numbers denote the same or like components. Referring to FIG. 12 and FIG. 18, at step S110, the chuck table 200 is configured to receive the semiconductor wafer 300 on the front surface of the chuck table 200. In accordance with some exemplary embodiments of the present disclosure, the chuck table 200 secures the semiconductor wafer 300 thereon through vacuum. The chuck table 200 is configured to rotate around the axis A2. As a result, the semiconductor wafer 300 is also rotated around the axis A2.

[0047] The grinding apparatus 10 may further include the mechanism (such as the guide, motor, etc., not shown) configured to lift the grinding wheel 100 up when no grinding is performed, and lower down the grinding wheel 100 for the grinding. The grinding apparatus 10 also includes the mechanism (such as motor, controller, etc., not shown) to rotate the grinding wheel 100 around the axis A1, which is offset from the axis A2. In accordance with some embodiments of the present disclosure, the locations of the axis A1 and the axis A2 are fixed, and both the chuck table 200, and the grinding wheel 100 rotate simultaneously, so that the grinding teeth 114 of the grinding wheel 100 abrade the semiconductor wafer 300 on the chuck table 200. In accordance with some embodiments of the present disclosure, the grinding teeth 114 are formed of diamond, silicon carbide, carbon nitride, or other types of abrasive materials. The grinding teeth 114 have appropriate roughness and hardness for grinding the semiconductor wafer 300.

[0048] In some embodiments, the semiconductor wafer 300 and the grinding wheel 100 may counter-rotate (or rotate in a same direction) during the grinding process. For example, the semiconductor wafer 300 may be rotated in a clockwise direction around the axis A2, and the grinding wheel 100 may be rotated in a counter-clockwise direction around the axis A1. Through the rotation of both the semiconductor wafer 300 and the grinding wheel 100, the entire tops surface of the semiconductor wafer 300 is ground by the grinding wheel 100. It is appreciated that although the semiconductor wafer 300 is used as an example to describe the grinding process and the respective grinding apparatus 10, other integrated circuit components such as silicon wafers, package substrates, interposers, or the like may also be ground using the grinding apparatus 10.

[0049] FIG. 19 illustrates a process flow of intermediate stages in a grinding process of a semiconductor wafer according to some embodiments of the present disclosure. Referring to FIG. 12 and FIG. 19, in the grinding process, step S142 may be performed, that is, the inclination state is sensed and monitored, continuously or periodically, during the grinding process. Accordingly, at step S144, the controller 140 controls the respective adjustment shafts 232, 234, 236 to raise or lower the chuck table 200 independently according to the inclination state during the grinding process. In detail, the controller 140 controls the sensor 60 to detect, for example, the profile (including shapes, thickness, inclination, etc.) of semiconductor wafer 300 during the grinding process, so as to adjust the inclination of the chuck table 200 by raising or lowering the adjustment shafts 232, 234, 236 independently to achieve the desired thickness of the semiconductor wafer 300 with the desired profile after the grinding process. For example, during the grinding process, if the sensor 60 detects that the semiconductor wafer 300 is centrally recessed, which does not match the final profile of the semiconductor wafer 300, the controller 140 controls the adjustment shafts 232, 234, 236 to raise or lower the respective portions of the chuck table 200 so that the grinding wheel 100 can come into contact with a peripheral portion of the semiconductor wafer 300 and grind the peripheral portion of the semiconductor wafer 300. Accordingly, the ground area of the semiconductor wafer 300 expands from the annular peripheral portion to the central portion. The grinding wheel 100 performs the grinding process until the thickness of the semiconductor wafer 300 becomes the predetermined finished profile (thickness).

[0050] The, referring to FIG. 13, after the grinding process, the device dies 22 and the respective metal contacts 26 are revealed. Next, as shown in FIG. 14, a redistribution structure including at least one redistribution lines (RDLs) 136 and at least one dielectric layer 138 are formed. For example, as shown in FIG. 14, the redistribution lines 136 are formed on the top surfaces of the encapsulating material 30 and the metal contacts 26. In accordance with some embodiments of the present disclosure, the formation of the redistribution lines 136 includes depositing a metal layer (such as aluminum, aluminum copper, nickel, tungsten, or alloys thereof), and patterning the metal layer through an etching process. In accordance with alternative embodiments of the present disclosure, the redistribution lines 136 are formed in a plating process, wherein each of the redistribution lines 136 includes a seed layer (not shown) and a plated metallic material over the seed layer.

[0051] FIG. 14 also illustrates the dielectric layer 138, which covers some portions of the redistribution lines 136, while leaving some other portions not covered. In accordance with some embodiments of the present disclosure, the dielectric layer 138 is formed of a polymer such as PBO, polyimide, or the like. In accordance with alternative embodiments of the present disclosure, the dielectric layer 138 is formed of silicon nitride, silicon oxide, or multi-layers thereof. A plurality of openings 120 are formed in the dielectric layer 138 to expose the pads of the dielectric layer 138. The formation of the openings 120 may be performed through a photo lithography process. It is noted that one redistribution line and one dielectric layer 138 are illustrated herein, but more redistribution lines 136 and dielectric layers 138 can be formed.

[0052] FIG. 15 illustrates the formation of electrical connectors 122 in accordance with some exemplary embodiments. The formation of electrical connectors 122 may include placing solder balls on the exposed portions of the redistribution lines 136, and then reflowing the solder balls. In accordance with alternative embodiments of the present disclosure, the formation of electrical connectors 122 includes performing a plating step to form solder regions over the redistribution lines 136 and then reflowing the solder regions. The electrical connectors 122 may also include metal pillars and optionally solder caps, which may also be formed through plating. Under-Bump Metallurgies (UBMs, not shown) may or may not be formed before the formation of electric connectors 122. The formation of the UBMs may include deposition and patterning.

[0053] Next, referring to FIG. 15 and FIG. 16, the portions of the semiconductor wafer 300 over the release layer 41 are de-bonded from the carrier 40. The remaining portions of the semiconductor wafer (excluding the carrier 40 and the release layer 41) are referred to as a package 124, which is shown in FIG. 16. The de-bonding may be performed by projecting a light such as UV light or laser on the release layer 41 to decompose the release layer 41.

[0054] In subsequent steps, as shown in FIG. 16, the package 124 is placed on a dicing tape 126, which is fixed on a frame 128. Then, referring to FIG. 16 and FIG. 17, a die saw process is performed to saw the package 124 into a plurality of packages 320 shown in FIG. 17, each including a device die 22.

[0055] Based on the above discussions, it can be seen that the present disclosure offers various advantages. It is understood, however, that not all advantages are necessarily discussed herein, and other embodiments may offer different advantages, and that no particular advantage is required for all embodiments.

[0056] In accordance with some embodiments of the disclosure, a grinding apparatus includes a grinding wheel configured to rotate around a first axis, a chuck table configured to rotate around a second axis offset from the first axis, and a plurality of adjustment shafts disposed at a peripheral portion of the chuck table and configured to adjust an inclination of the chuck table. The chuck table includes an edge contour where an edge of the grinding wheel is projected onto the chuck table, and a wheel center where a center of the grinding wheel is projected onto the chuck table. Each of the plurality of adjustment shafts are disposed on an extending line extending from the wheel center toward a point on the edge contour. In one embodiment, the grinding apparatus further includes a rotating shaft coupled to the chuck table and configured to drive the chuck table to rotate around the second axis. In one embodiment, the edge contour passes a center of the chuck table from a top view. In one embodiment, each of the plurality of adjustment shafts includes a cylinder operated independently for raising or lowering a portion of the chuck table. In one embodiment, the chuck table further includes an edge point where an edge of the chuck table and the edge of the grinding wheel are intersected from a top view, and a first segment of the edge contour from the center of the chuck table to the edge point. In one embodiment, the plurality of adjustment shafts includes a first adjustment shaft disposed on an extending line extending from the wheel center toward a middle point of the first segment. In one embodiment, the plurality of adjustment shafts includes a second adjustment shaft, and the wheel center, first adjustment shaft, and the second adjustment shaft form an equilateral triangle from a top view. In one embodiment, the plurality of adjustment shafts includes a third adjustment shaft disposed on an extending line extending from the wheel center toward a quarter point, which is a midpoint of a second segment of the edge contour from the center of the chuck table to the middle point of the first segment. In one embodiment, the grinding wheel includes a base disk, and a plurality of grinding teeth protruding from a surface of the base disk. In one embodiment, a front surface of the chuck table facing the grinding wheel has a central portion higher than an edge portion surrounding the central portion.

[0057] In accordance with some embodiments of the disclosure, a grinding apparatus includes a grinding wheel configured to rotate around an axis, a chuck table configured to receive a workpiece thereon and including a supporting portion that is not overlapped with grinding wheel from a top view, and at least three adjustment shafts disposed at the supporting portion of the chuck table and configured to raise or lower the chuck table independently. In one embodiment, the chuck table includes an edge contour where an edge of the grinding wheel is projected onto the chuck table, an edge point where an edge of the chuck table and the edge of the grinding wheel are intersected from a top view, and an edge segment of the edge contour from the center of the chuck table to the edge point. In one embodiment, the at least three adjustment shafts includes a first adjustment shaft configured to vertically move 1 unit distance resulting in the edge point vertically moving 0.7 unit distance, a middle point of the edge segment vertically moving 0.6 unit distance, and the center of the chuck table vertically moving 0.35 unit distance. In one embodiment, the plurality of adjustment shafts includes a second adjustment shaft, the chuck table further includes a wheel center where a center of the grinding wheel is projected onto the chuck table, wherein the wheel center and the first adjustment shaft, and the second adjustment shaft form an equilateral triangle from a top view. In one embodiment, the at least three adjustment shafts includes a third adjustment shaft configured to vertically move 1 unit distance resulting in the edge point vertically moving 0.75 unit distance, a middle point of the edge segment vertically moving 0.65 unit distance, and a center of the chuck table vertically moving 0.4 unit distance. In one embodiment, an edge of the grinding wheel projected onto the chuck table passes a center of the chuck table from a top view.

[0058] In accordance with some embodiments of the disclosure, a method of grinding a semiconductor wafer includes receiving a semiconductor wafer on a front surface of a chuck table; adjusting an inclination of the front surface of the chuck table by at least three adjustment shafts disposed at a peripheral portion of the chuck table, wherein the at least three adjustment shafts is controlled to raise or lower the chuck table independently; and performing grinding process on at least a portion of the semiconductor wafer by a grinding wheel. In one embodiment, the method further includes: obtaining an inclination state of the semiconductor wafer or the front surface of the chuck table by a sensor, wherein the at least three adjustment shafts is controlled to raise or lower the chuck table independently according to the inclination state. In one embodiment, the inclination state is obtained by a plurality of sensors configured to measure a plurality of displacements of the chuck table, or measure a relative angle between the grinding wheel and the semiconductor wafer. In one embodiment, the method further includes: sensing and monitoring the inclination state during the grinding process; and controlling the at least three adjustment shafts to raise or lower the chuck table independently according to the inclination state during the grinding process.

[0059] 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 semiconductor tool, comprising:a grinding wheel configured to rotate around a first axis;a chuck table configured to rotate around a second axis offset from the first axis, wherein the chuck table comprises an edge contour where an edge of the grinding wheel is projected onto the chuck table, and a wheel center where a center of the grinding wheel is projected onto the chuck table; anda plurality of adjustment shafts disposed at a peripheral portion of the chuck table and configured to adjust an inclination of the chuck table, wherein each of the plurality of adjustment shafts are disposed on an extending line extending from the wheel center toward a point on the edge contour, more than one of the plurality of adjustment shafts raise or lower respective portions of the chuck table during adjusting the inclination of the chuck table.

2. The semiconductor tool as claimed in claim 1, further comprising a rotating shaft coupled to the chuck table and configured to drive the chuck table to rotate around the second axis.

3. The semiconductor tool as claimed in claim 1, wherein the edge contour passes a center of the chuck table from a top view.

4. The semiconductor tool as claimed in claim 1, wherein each of the plurality of adjustment shafts comprises a cylinder operated independently for raising or lowering a portion of the chuck table.

5. The semiconductor tool as claimed in claim 1, wherein the chuck table further comprises an edge point where an edge of the chuck table and the edge of the grinding wheel are intersected from a top view, and a first segment of the edge contour from the center of the chuck table to the edge point.

6. The semiconductor tool as claimed in claim 5, wherein the plurality of adjustment shafts comprises a first adjustment shaft disposed on an extending line extending from the wheel center toward a middle point of the first segment.

7. The semiconductor tool as claimed in claim 6, wherein the plurality of adjustment shafts comprises a second adjustment shaft, and the wheel center, first adjustment shaft, and the second adjustment shaft form an equilateral triangle from a top view.

8. The semiconductor tool as claimed in claim 6, wherein the plurality of adjustment shafts comprises a third adjustment shaft disposed on an extending line extending from the wheel center toward a quarter point, which is a midpoint of a second segment of the edge contour from the center of the chuck table to the middle point of the first segment.

9. The semiconductor tool as claimed in claim 1, wherein the grinding wheel comprises a base disk, and a plurality of grinding teeth protruding from a surface of the base disk.

10. The semiconductor tool as claimed in claim 1, wherein a front surface of the chuck table facing the grinding wheel has a central portion higher than an edge portion surrounding the central portion.

11. A semiconductor tool, comprising:a grinding wheel configured to rotate around an axis;a chuck table configured to receive a workpiece thereon and comprising a supporting portion that is not overlapped with grinding wheel from a top view; andat least three adjustment shafts disposed at the supporting portion of the chuck table and configured to raise or lower the chuck table independently.

12. The semiconductor tool as claimed in claim 11, wherein the chuck table comprises an edge contour where an edge of the grinding wheel is projected onto the chuck table, an edge point where an edge of the chuck table and the edge of the grinding wheel are intersected from a top view, and an edge segment of the edge contour from the center of the chuck table to the edge point.

13. The semiconductor tool as claimed in claim 12, wherein the at least three adjustment shafts comprises a first adjustment shaft configured to vertically move 1 unit distance resulting in the edge point vertically moving 0.7 unit distance, a middle point of the edge segment vertically moving 0.6 unit distance, and the center of the chuck table vertically moving 0.35 unit distance.

14. The semiconductor tool as claimed in claim 13, wherein the plurality of adjustment shafts comprises a second adjustment shaft, the chuck table further comprises a wheel center where a center of the grinding wheel is projected onto the chuck table, wherein the wheel center and the first adjustment shaft, and the second adjustment shaft form an equilateral triangle from a top view.

15. The semiconductor tool as claimed in claim 12, wherein the at least three adjustment shafts comprises a third adjustment shaft configured to vertically move 1 unit distance resulting in the edge point vertically moving 0.75 unit distance, a middle point of the edge segment vertically moving 0.65 unit distance, and a center of the chuck table vertically moving 0.4 unit distance.

16. The semiconductor tool as claimed in claim 12, wherein an edge of the grinding wheel projected onto the chuck table passes a center of the chuck table from a top view.

17. A method of grinding a semiconductor wafer, comprising:receiving a semiconductor wafer on a front surface of a chuck table;adjusting an inclination of the front surface of the chuck table by at least three adjustment shafts disposed at a peripheral portion of the chuck table, wherein the at least three adjustment shafts is controlled to raise or lower the chuck table independently; andperforming grinding process on at least a portion of the semiconductor wafer by a grinding wheel.

18. The method as claimed in claim 17, further comprising:obtaining an inclination state of the semiconductor wafer or the front surface of the chuck table by a sensor, wherein the at least three adjustment shafts is controlled to raise or lower the chuck table independently according to the inclination state.

19. The method as claimed in claim 18, wherein the inclination state is obtained by a plurality of sensors configured to measure a plurality of displacements of the chuck table, or measure a relative angle between the grinding wheel and the semiconductor wafer.

20. The method as claimed in claim 18, further comprising:sensing and monitoring the inclination state during the grinding process; andcontrolling the at least three adjustment shafts to raise or lower the chuck table independently according to the inclination state during the grinding process.

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