SILICON GRIPPER WITH LASER SEPARATION LAYERS AND METHOD FOR HANDLING A WAFER

Abstract

A method of handling a wafer (102), the method comprising: Positioning a gripper (106) attached to the wafer by a bonding layer (104) comprising a separation layer (204), an optical gain layer (206), an optical interface layer (202), and an anti-reflection layer (208); and Separating the gripper (106) from the wafer using a laser that emits laser energy at a wavelength that is absorbed by the separation layer (204), that is concentrated onto the separation layer (204) by the optical gain layer (206), and that is reflected back to the separation layer (204) by the optical interface layer (202) such that the material of the separation layer (204) is ablated when it is exposed to the laser energy to release the wafer (102).

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates generally to the manufacture of semiconductor devices and, more particularly, to wafer grippers with laser separation layers.

[0002] Three-dimensional chip integration allows for better utilization of chip space by stacking components on top of each other. Among other things, this stacking can reduce chip complexity and improve performance by shortening signal propagation times, for example.

[0003] Positioning the various layers of the three-dimensional chip relative to each other before bonding them together can be difficult. In some cases, where the chip to be moved is particularly thin, the wafer can be damaged if moved without support. Therefore, grippers can be used to provide structural support for the wafer. Such a gripper can be glued to one side of the wafer while the wafer is moved, and then detached and removed to provide a means for further processing.

[0004] For this separation process, a laser can be used to penetrate the gripper material and heat a separation layer. When the separation layer is sufficiently heated, it can sublimate and release the wafer. However, the absorption of the laser energy within the separation layer can be very weak (e.g., approximately 5%). High-power lasers must therefore be used, which increases the cost of the separation process. However, if only a small amount of laser energy is needed to heat the separation layer itself, the remaining laser energy will pass through and be absorbed by the surrounding materials and the environment. This can damage the wafer and other circuitry if the laser energy is inadvertently absorbed by a structure.

[0005] US 10 112 377 B2 describes a method for separating a carrier from a laminate consisting of a substrate, an adhesive layer, a light-absorbing release layer, and a carrier plate. The method comprises an irradiation step in which laser light with a pulse width of at least 20 ns impinges on the release layer. SUMMARY

[0006] The invention is described by the features of the independent claims. Embodiments are specified in the dependent claims.

[0007] A method for handling a wafer includes positioning a gripper attached to a wafer by a bonding layer comprising a separation layer, an optical gain layer, and an anti-reflective layer. The gripper is separated from the wafer using a laser that emits laser energy at a wavelength that is absorbed by the separation layer and focused by the optical gain layer onto the separation layer, thereby ablating the material of the separation layer exposed to the laser energy and releasing the wafer.

[0008] A method for transferring a wafer includes bonding a gripper to a wafer using a bonding layer comprising a release layer, an optical gain layer, and an anti-reflective layer. The gripper is positioned. The gripper is separated from the wafer using a laser that emits laser energy at a wavelength that is absorbed by the release layer and focused by the optical gain layer onto the release layer, thereby ablating the material of the release layer exposed to the laser energy and releasing the wafer.

[0009] A gripper wafer contains a gripper layer made of a material transparent to light of a particular wavelength. A bonding layer contains a separation layer and an optical gain layer. The separation layer absorbs the light of that wavelength because it is made of a material with a true refractive index greater than 3.0 and an extinction coefficient greater than 5.0 at that wavelength. The optical gain layer is made of a material transparent at that wavelength with a refractive index greater than 2.0 and concentrates the light energy at that wavelength onto the separation layer.

[0010] A gripper wafer contains a gripper layer formed from a material transparent to light of one wavelength. A link layer contains a separation layer that absorbs light of one wavelength and is formed from a material with a refractive index greater than 3.0 and an extinction coefficient greater than 5.0 at that wavelength. An optical gain layer of the link layer is formed from a material that is transparent at that wavelength, has a refractive index greater than 2.0, and concentrates light of that wavelength onto the separation layer.

[0011] A gripper wafer contains a gripper layer formed from silicon. A bonding layer includes a separation layer, an optical gain layer, an optical interface layer, and an anti-reflection layer. The separation layer absorbs light of a wavelength from a separation laser selected from a range between 1,200 nm and 2,500 nm and is formed from a material selected from the group consisting of magnesium, iron, nickel, rhodium, palladium, platinum, and lutetium. An optical gain layer is formed from a material selected from the group consisting of amorphous silicon, amorphous germanium, and polycrystalline silicon to concentrate laser energy at the light wavelength onto the separation layer. An optical interface layer is located on a side of the separation layer opposite the gripper layer to reflect the light of the wavelength into the separation layer.There is an anti-reflection layer between the optical gain layer and the gripper layer.

[0012] Some embodiments may include a release layer comprising a metallic material selected from the group consisting of magnesium, iron, nickel, rhodium, palladium, platinum, and lutetium.

[0013] Some embodiments may include a separation layer comprising a metal having an extinction coefficient of at least 5.0 at the laser wavelength.

[0014] Some embodiments may include an optical gain layer formed from a material selected from the group consisting of amorphous silicon, amorphous germanium, and polycrystalline germanium.

[0015] These and other features and advantages will become apparent from the following detailed description and its illustrative embodiments when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following description provides details of preferred embodiments with reference to the following figures, wherein: Fig. 1 is a cross-sectional view of an arrangement of layers for gripping a wafer according to an embodiment of the present invention, including a bonding / separating layer capable of releasing a wafer when a separating member is removed using laser energy; Fig.2 is a cross-sectional view of an assembly of layers for gripping a wafer according to an embodiment of the present invention, including a multi-layer bonding / separating layer capable of releasing a wafer when a separating member is removed using laser energy; Fig. 3 is a cross-sectional view of an arrangement of layers for gripping a wafer according to an embodiment of the present invention, including a multi-layer bonding / separating layer capable of releasing a wafer when a separating member is removed using laser energy; Fig. 4 is a block diagram / flowchart of a method for separating a gripper layer from a wafer by laser ablation of a separation layer according to an embodiment of the present invention; Fig.5 is a block diagram / flowchart of a method according to an embodiment of the present invention for manipulating a wafer using a gripper that can be selectively severed using laser energy; Fig. 6 is a block diagram / flowchart of a method according to an embodiment of the present invention for forming a gripper including a separation layer formed from a material selected to enhance the absorption of laser energy for the purpose of separating a wafer; and Fig. 7 is a diagram of a wafer gripping system according to an embodiment of the present invention having a handle attached to a gripper connected to the wafer and reciprocating and positioning the wafer for processing. DETAILED DESCRIPTION

[0017] When multiple chips are integrated into a three-dimensional array, the chips are carefully and neatly moved and positioned relative to each other for manufacturing processes and to create functional contacts between structures. Wafer handling can be accomplished using a variety of structures. For example, a gripper layer made of any suitable material, such as silicon, can be bonded to the wafer being moved. This can prevent damage to the wafer by providing structural support. This is especially important when the wafer substrate is very thin, which can weaken the wafer with respect to lateral forces.

[0018] The handling process includes not only the mechanism by which the gripper layer is bonded to the wafer, but also the manner in which the gripper is separated from the wafer. For example, a laser can be used to remove the separation layer. The material of the separation layer, as well as the wavelength and power of the laser, can be selected to selectively remove the separation layer without damaging the wafer, for example, by sublimating the separation layer material. A separation layer can be formed from a material with sufficient stability at operating temperatures, a suitable melting point, a matching refractive index, and sufficient absorption at the laser wavelength.By selecting the right material for the separation layer, low-power, low-cross-section lasers can be used, and high throughput can be achieved with low risk of damage to the wafer circuitry.

[0019] In particular, the bonding / separation layer may comprise multiple individual layers. One such individual layer may be a bonding layer that provides an adhesive bond between the gripper and the wafer. Another such individual layer may be a separation layer between the bonding layer and the gripper, formed from a metal or a foil. The separation layer may be designed to release the wafer when a suitable laser is applied, for example, by melting or sublimating the material of the separation layer. Once the separation layer is completely removed, the gripper can be lifted off the wafer without causing damage.

[0020] The separation layer can be formed from a metallic or foil material with a high refractive index (e.g., greater than about 3.0) and a suitable extinction coefficient (e.g., κ between about 5 and about 10) at the mid-infrared wavelength of the laser (e.g., between about 1,200 nm and about 6,000 nm). A laser wavelength is selected that is not absorbed by the gripper material, so that separation can occur by the action of the laser light through the gripper material. In addition, a layer can be used to enhance the separation effect, which has a high refractive index (e.g., greater than about 2.0) and high transmittance (e.g., κ close to zero) for the laser light at a mid-infrared wavelength.The complex refractive index of the separation layer and the surrounding material favors the concentration of laser energy within the separation layer, where a high percentage of the energy is absorbed and used to facilitate separation. Details of such materials are described in more detail below.

[0021] Using these materials, the optical absorption strength of the laser light used for cutting is concentrated within the metallic or foil layer. This increases the efficiency of the cutting process, allowing the use of lower-power lasers. Furthermore, because the absorption of the laser light energy is concentrated within the cutting layer, less heat is generated in the gripper and the wafer.

[0022] Fig.1 shows a cross-sectional view of a gripper 106 connected to a wafer 102. While it is specifically conceivable that the wafer 102 is an integrated circuit formed on a semiconductor substrate such as silicon, it should be understood that the wafer may be formed from any suitable materials and may include any suitable devices. For example, the wafer 102 may include active circuit components such as transistors, as well as passive circuit components such as capacitors, inductors, and conductive interconnects.

[0023] The gripper 106 may also be formed from any suitable material, with particular consideration given to silicon. The gripper 106 may further include an anti-reflection layer 108, which may be formed from silicon nitride or another material with a suitable refractive index and transmittance. The gripper 106 is formed from a material that is transparent to light at a wavelength used for separation.

[0024] A multilayer bonding layer 104 is shown between the wafer 102 and the gripper 106. The bonding layer 104 is described in more detail below. The layers comprising the bonding layer 104 are selected to concentrate the absorption of the laser light within a separation layer. Thus, the bonding layer 104 performs a dual function by firstly providing an adhesive bond between the wafer 102 and the gripper 106 and secondly separating the two structures once the wafer 102 has been moved into a position where laser light is applied.

[0025] During semiconductor manufacturing processes, the use of a gripper 106 makes it possible to significantly improve the yield and speed of chip packaging. The systems can be configured to pick up the wafer 102 using the gripper 106, for example, by applying suction or by mechanical gripping, so that the wafer can be moved automatically and precisely during the manufacturing process. This is particularly advantageous when stacking one wafer on top of another, for example, when packaging three-dimensional integrated circuits. In particular, during a flip-chip process, integrated circuits can be manufactured on a wafer. The wafer can then be divided into chips, which are then flipped and connected to another chip. This process is described in more detail below.

[0026] Fig.2 shows a cross-sectional view of a gripper 106 connected to a wafer 102, additionally including a detailed view of the bonding layer 104. The bonding layer 104 may include a first optical interface layer 202, a separation layer 204, a second optical interface layer 206, and an anti-reflection coating 208. Each of these layers may have a thickness in the range between 20 nm and 50 µm.

[0027] The optical interface layers 202 and 206, as well as the anti-reflective coating 208, perform functions to control the reflection behavior between layers; these functional assignments should not be interpreted in a precise manner. In particular, depending on the differences in refractive index, a particular layer may provide an anti-reflective function for one layer and an optical interface function for another layer.

[0028] Although with reference to Fig.2 describes a specific arrangement of layers, however, it should be understood that other layers may be used in addition to or instead of the layers shown. For example, the interconnect layer 104 may include, in order from gripper to wafer, a first optional anti-reflective coating, an optional optical interface layer, a second optional anti-reflective coating, a release layer, and an optical interface layer.

[0029] The first optical interface layer 202 may provide an adhesive bond to the wafer 102 and may be made of a material having a refractive index of the real component n real < 2.0. The material of the first optical interface layer 202 may, for example, consist of a polyimide with a complex refractive index of approximately n = 1.6 + 0i, where the real part n realis the refractive index and the imaginary part is the extinction coefficient κ of the material at the wavelength in question. Alternatively, silicon dioxide with a complex refractive index of approximately n = 1.5 + 0i can be used as the material for the first optical interface layer 202. A low value for the refractive index is selected to enhance reflections at the interface between the separation layer 204 and the first optical interface layer 202. Thus, when laser light passes through the separation layer 204, some of the energy is absorbed and some is transmitted, which in turn is reflected back into the separation layer 204 at the first optical interface layer 202.

[0030] The separation layer 204 is formed on the first optical interface layer 202. The separation layer 204 may be formed from a material having a complex refractive index, preferably having a real component of n real> 3.0 and an imaginary component of κ > 5.0 at at least one suitable laser wavelength, for example in the range between 1,200 nm and 6,000 nm. Exemplary materials for the separation layer can be selected from those shown in Table 1. These materials have useful values of the complex refractive index for at least one wavelength range, both for the real part and for the absorption part. Table 1 material Refractive index at 1,200 nm Refractive index at 1,500 nm Refractive index at 2,000 nm n K n K n K magnesium 2,7836 12,332 7,2536 15,209 7,1988 9,1847 iron 3,1822 5,4909 3,0702 6,6994 3,0056 9,0376 nickel 3,0763 6,7413 3,1239 7,866 3,0976 10,326 Rhodium 3,7168 8,5141 3,6355 10,031 3,8285 13.126 palladium 3,4558 7,3899 3,8154 8,5835 4,128 10,662 platinum 4,7446 8,1653 5,6406 8,3367 4,8397 9,691 lutetium 3,1044 4,5883 3,1694 5,4249 3,4391 7,3115

[0031] Table 2 shows other materials that can be used. These materials have high absorption values but relatively small real parts of their refractive indices, or a large real part and low absorption values. Table 2 material Refractive index at 1,200 nm Refractive index at 1,500 nm Refractive index at 2,000 nm n k n k n k beryllium 3,1021 4,346 2,7983 5,3941 2,457 7,439 Aluminum m 1.3014 11,503 1,4639 14,711 2,1427 19,819 titanium 4,9660 3,9405 5,2052 4,4024 5,3495 4,7147 chrome 4.2709 4,1511 4,0328 4,5835 3,5854 5,8711 manganese 4,098 4,751 4,78 5,08 5,769 5,61 Cobalt 5.178 4,5708 3,8277 5,1263 2,7638 7,6934

[0032] In addition to those shown in Table 3, other materials may be used. These materials are similar to those in Table 2, but have a high boiling point. Table 3 material Refractive index at 1,200 nm Refractive index at 1,500 nm Refractive index at 2,000 nm n k n k n k tungsten 2,7899 5,1496 2,34 6,6453 2,1162 9,6315 zirconium 4.51 3,936 4,819 4,182 5,183 4.5860

[0033] Some materials, such as tungsten and zirconium, have relatively high boiling points (e.g., above 4,000 °C), which can make their use unsuitable, as the temperature required to separate the wafer can damage neighboring components. Aluminum, in turn, has a relatively high solubility in silicon, which affects the optical properties of such a layer and reduces the absorption of laser light energy. Materials such as nickel and platinum, on the other hand, absorb laser light very strongly, even at relatively thin layer thicknesses (e.g., approximately 500 Å).

[0034] To achieve a desired complex refractive index, alloys of the materials described herein can also be used. Likewise, alloys of the metals described herein with other metals can also be used, provided they are suitable. Furthermore, the separation layer 204 can be composed of several layers of different suitable materials. When selecting the separation layer 204, two different material properties are used to improve the absorption of the laser light. Further selection criteria can include compatibility with the semiconductor production line to avoid contamination of the wafer materials. The selection can also be based on storage properties to prevent corrosion or oxidation of the separation layer 204.

[0035] In some cases, the separation layer 204 may include a polymer film with a filler selected from one or more of the materials described herein. The filler may include, for example, metal particles, metal alloy particles, carbon particles with metal coatings, and non-metallic particles. The filler material is selected so that, together with the polymer material of the film, it absorbs the laser energy to be removed during the separation process.

[0036] The second optical gain layer 206 can be formed on the separation layer 204 to reduce the reflection of light from the interface of the separation layer 204. Since reflections occur at interfaces between materials, which increase as the difference between the refractive indices of the interface layers increases, a layer with an intermediate refractive index can reduce the amount of laser light energy reflected by the separation layer 204.

[0037] An anti-reflection coating 208 may provide an additional material with an intermediate refractive index. For example, the anti-reflection coating 208 may be formed from silicon dioxide with a complex refractive index of 1.5 + 0i at the wavelengths in question.

[0038] The individual layers of the multilayer interconnect layer can be formed through sequential deposition processes. Starting from the gripper 106, the first optical interface layer, the anti-reflection coating 208, and the second optical interface layer 206 can be formed by corresponding depositions using one or more of any suitable processes, such as physical vapor deposition (PVD) or chemical vapor deposition (CVD) 208 on the gripper surface. Likewise, the separation layer 204 can be formed using PVD or CVD. The first optical interface layer 202, which can be formed from polyimide, can be deposited using a spin-coating process. If the wafer 102 is an active silicon wafer, the polyimide can act as an adhesive.If the wafer 102 is a passive redistribution layer, the wafer 102 can be formed directly on the polyimide of the first optical interface layer 202, so no separate step for bonding to the wafer 102 is required.

[0039] Fig. 3 shows a cross-sectional view of a gripper 106 bonded to a wafer 102 with additional detail on the bonding layer 104. Some embodiments may use a second optical interface layer 302 that also has a high refractive index in addition to using a separation layer 204 with a high refractive index.

[0040] Exemplary materials for this layer include amorphous silicon with a complex refractive index of 3.5 + 0i at the wavelength in question and amorphous or polycrystalline germanium with a complex refractive index of 4.0 + 0i at the wavelength in question. Compared to the use of silicon nitride for this layer, the use of amorphous silicon can increase the absorption of laser light in the separation layer 204 from 60% to 80% to 90% to 100%.

[0041] Fig.4 shows a method for separating a gripper 106 from a wafer 102. This step occurs after the wafer 102 has been positioned and bonded to another chip, or may be performed to prepare for an intermediate process in which the underside of the wafer 102 is to be processed. This positioning may include alignment with another chip, for example, a carrier chip, and further a bonding process to attach the wafer 102 to the other chip. Such a bonding process may include, for example, reflowing solder balls and underfilling with an adhesive to structurally support the electrical connections.

[0042] In block 404, a portion of the separation layer 204 is ablated using a laser of a suitable wavelength. This ablation can be performed using a short-duration laser pulse in a focused region. If a wavelength is used at which the light is absorbed by the separation layer 204, the energy of the laser light is transferred to the material of the separation layer 204 in the focused region, causing a local change in the material. This change can be viewed as sublimation of the material, which converts the material directly into the gaseous or plasma state without first melting. The penetration of thermal energy can thus be concentrated on the separation layer 204, with the resulting temperature increase being quickly absorbed by the neighboring layers.

[0043] In this way, the separation layer 204 can be selectively removed from the space between the wafer 102 and the gripper 106 without causing thermal damage to the wafer 102. With each laser shot, material is removed from the laser's focal spot. The ablation can then be repeated by scanning in a pattern to completely remove the separation layer 204. A determination is then made in block 406 as to whether the separation process has been completed, for example, by determining that the entire separation layer 204 has been hit by a laser pulse. If this is not the case, the laser is re-aligned with the separation layer 204 in block 408 so that the laser's focal spot hits a new area, and the ablation of the new area is repeated in block 404 by irradiating it with another laser pulse. After the separation is complete in block 406, the gripper 106 is removed from the wafer 102 in block 410.Any remaining material of the adhesive layer 202 can be dissolved using a solvent.

[0044] Fig. 5 shows a method for manufacturing integrated circuits using a gripper. In block 502, one or more manufacturing processes are applied to create a wafer 102 with an integrated circuit. For example, in block 502, a sequence of deposition and etching steps may be performed to create circuit components, including active components such as transistors and passive components such as interconnect lines, capacitors, and inductors. The wafer 102 may include multiple layers, including active circuit layers and interconnect layers.

[0045] In block 504, a gripper 106 is bonded to the wafer 102 using a bonding layer 104. As mentioned above, the bonding layer 104 may include multiple individual layers with advantageous functional and optical properties that may be formed on the gripper 106. Bonding may occur by adhering the bonding layer 104 to the wafer 102.

[0046] In block 505, the wafer 102 is positioned. During this positioning, the wafer 102 may be transferred relative to another structure, for example, a chip or a second wafer. Positioning may also include transferring the wafer 102 from one processing location to another, for example, by transferring the wafer 102 to another machine for further processing. Positioning may also include turning the wafer to expose an underside of the wafer 102. Positioning may be performed, for example, by lifting the gripper 106 or the wafer 102 using negative pressure.

[0047] After the wafer 102 has been positioned as described above in block 505, the wafer 102 may be separated from the gripper 106 using block 400. The gripper 106 is removed in block 506 to then perform any additional processing required in block 508. The wafer 102 may be further processed, for example, to form additional structures, to process the substrate of the wafer 102, or to bond another structure to the wafer 102.

[0048] Fig.6 shows a method for forming a gripper. In block 602, an anti-reflective layer 208 is formed on a gripper layer 106, for example, using a CVD or PVD process. In block 604, an optical gain layer 206 is formed on the anti-reflective layer 208, and in block 606, the isolation layer 204 is formed on the optical gain layer 206, again using a CVD or PVD process. In block 608, the optical barrier layer 202 is then formed on the isolation layer 204, for example, using a spin-coating process. At this point, in block 610, the gripper 106 can be bonded to the wafer 102, for example, by turning the gripper 106 over and pressing it onto the wafer 102 until the material of the optical barrier layer 202 is cured.

[0049] CVD is a deposition process in which a deposited substance is formed by a chemical reaction between reactants at a temperature above room temperature (e.g., from about 25°C to about 900°C). The solid reaction product is deposited on the surface, on which a film, coating, or layer of the solid reaction product is formed. Variants of CVD processes, including, but not limited to, atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), plasma-enhanced CVD (PECVD), and metal-organic CVD (MOCVD), as well as combinations thereof, may also be employed. In alternative embodiments using PVD, a sputtering apparatus may utilize DC diode systems, radio frequency sputtering, magnetron sputtering, or ionized metal plasma sputtering.

[0050] Fig.Figure 7 shows an apparatus for gripping a wafer. A wafer 702, which may include a gripper layer as described above, is moved using a vacuum manipulator 704. The gripper layer stiffens the wafer 702, which could otherwise bend, crack, or break due to the pressure of the vacuum manipulator 704 or the forces encountered when transferring the wafer 702 from one location to another.

[0051] While the use of a vacuum manipulator 704 is specifically contemplated, it should be understood that the wafer handling system described herein may be used to position a wafer using any type of manipulator, including any type of manual or automated gripping device. The manipulator 704 may engage a gripping side of the wafer 702 to protect potentially sensitive surface components of the wafer 702 from damage.

[0052] It should also be clear that when an element, such as a layer, region, or substrate, is described as being "on" or "above" another element, it may be directly on top of that other element, or it may have other elements in between. Conversely, when an element is described as being "directly on" or "directly above" another element, there are no intervening elements. It should also be clear that when an element is described as being "connected" or "coupled" to another element, it may be directly connected or coupled to that other element, or it may have other elements in between. Conversely, when an element is described as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0053] The present embodiments may include a design for an integrated circuit chip that can be created in a graphics computer programming language and stored in a computer storage medium (e.g., a magnetic tape storage disk, a physical hard disk drive, or a virtual drive such as in a memory access network). If the chip designer does not manufacture chips or photolithographic masks used to manufacture chips themselves, they may transfer the developed design directly or indirectly to such facilities by physical means (e.g., by providing a copy of the storage medium with the design stored therein) or electronically (e.g., via the Internet). The stored design is then converted into the appropriate format (e.g.,GDSII) to produce photolithographic masks, which typically comprise multiple copies of the chip design to be formed on a wafer. The photolithographic masks are used to define areas on the wafer (and / or in the layers thereon) that are to be etched or otherwise processed.

[0054] Methods described herein can be used in the manufacture of integrated circuit chips. The finished integrated circuit chips can be distributed by the manufacturer in raw wafer form (that is, as a single wafer with multiple bare chips), as a bare circuit chip, or in an encapsulated form. In the latter case, the chip is embedded in a single-chip package (e.g., on a plastic carrier from which conductors lead to a motherboard or higher-level carrier) or in a multi-chip package (e.g., on a ceramic carrier that has surface and / or buried interconnections). In each case, the chip is then combined with other chips, discrete circuit elements, and / or other signal processing units as part of either (a) an intermediate product such as a motherboard or (b) a final product.The final product can be any article containing integrated circuit chips, from toys or other simple applications to high-end computer products with a display, keyboard or other input device, and a central processor.

[0055] It should also be clear that material compounds such as SiGe are also described as listed elements. These compounds contain different proportions of the elements within the compound, e.g. SiGe contains Si x Ge 1-x , where x is less than or equal to one, etc. Furthermore, other elements may be present in the compound and still function according to the present principles. These compounds with additional elements are referred to herein as alloys.

[0056] Reference in the specification to "a particular embodiment" or "any embodiment" means that a particular feature, structure, characteristic, etc., described in connection with the embodiment, is included in at least one embodiment. Thus, phrases such as "in a particular embodiment" or "in any embodiment" appearing throughout the specification, as well as any other variations that appear in various places in the specification, are not necessarily all referring to the same embodiment.

[0057] It should be understood that when using any of the following expressions such as " / ", "and / or" and "at least one of", in the cases "A / B", "A and / or B" and "at least one of A and B", this is intended to cover the selection of only the first listed option (A), or the selection of only the second listed option (B), or the selection of both options (A and B). Furthermore, in the cases "A, B and / or C" and "at least one of A, B and C", such expression is intended to cover the selection of only the first listed option (A), or the selection of only the second listed option (B), or the selection of only the third listed option (C), or the selection of only the first and second listed options (A and B), or the selection of only the first and third listed options (A and C), or the selection of only the second and third listed options (B and C), or the selection of all three options (A, B, and C).This may include either the two options (B and C) or the selection of all three options (A, B, and C). It will be apparent to those skilled in this and other fields that this may be extended to as many positions as listed.

[0058] The terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting of the exemplary embodiments. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, unless the context otherwise indicates. Further, it is to be understood that the terms "comprises," "having," "includes," and / or "containing," when used in this specification, indicate the presence of specified features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0059] Spatial terms of reference such as "beneath," "underneath," "lower," "above," "upper," and the like may be used herein for convenience of description to describe the relationship of an element or feature to one or more elements or features illustrated in the FIGURES. It should be understood that the spatial terms of reference are intended to encompass various orientations of the unit employed or operation in addition to the orientation shown in the FIGURES. For example, if the unit in the FIGURES is turned over, then the elements described as being "below" other elements or features, or "below" are located "above" the other elements or features. Thus, the term "below" can encompass an orientation of both above and below.The unit may be oriented differently (rotated 90 degrees or in other orientations), and the spatial reference descriptions used herein may be interpreted accordingly. Furthermore, it should be understood that a layer described as "between" two layers may be the only layer between the two layers, or there may be one or two intermediate layers.

[0060] It should be clear that while the terms "first," "second," etc., may be used to describe various elements, these elements are not intended to be limited by them. These terms are intended to emphasize one element over another. Thus, a first element discussed may be referred to as a second element without departing from the scope of the present concept.

[0061] The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions comprising one or more executable instructions for implementing the one or more specified logical functions. According to some alternative implementations, the functions specified in the blocks may not appear in the order illustrated in the figures.For example, two blocks shown in sequence may actually execute concurrently, substantially concurrently, in a partially or completely overlapping manner, or the blocks may sometimes execute in the reverse order, depending on the intended functionality. It is also to be understood that each block of the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by specialized hardware systems that perform the specified functions or acts, or by combinations of specialized hardware and computer instructions.

Claims

[1] A method of handling a wafer (102), the method comprising: Positioning a gripper (106) attached to the wafer by a bonding layer (104) comprising a separation layer (204), an optical gain layer (206), an optical interface layer (202), and an anti-reflection layer (208); and Separating the gripper (106) from the wafer using a laser that emits laser energy at a wavelength that is absorbed by the separation layer (204), that is concentrated onto the separation layer (204) by the optical gain layer (206), and that is reflected back to the separation layer (204) by the optical interface layer (202) such that the material of the separation layer (204) is ablated when it is exposed to the laser energy to release the wafer (102). [2] The method of claim 1, wherein the release layer (204) contains a metallic material selected from the group consisting of magnesium, iron, nickel, rhodium, palladium, platinum, and lutetium. [3] The method of claim 1, wherein the release layer (204) includes a metallic material selected from the group consisting of beryllium, titanium, chromium, manganese, and cobalt. [4] The method of claim 1, wherein the release layer (204) includes a metallic material selected from the group consisting of zirconium, niobium, tungsten, and rhenium. [5] The method of claim 1, wherein the separation layer (204) contains a metal having an extinction coefficient of at least 5 at the wavelength. [6] The method of claim 1, wherein the metal of the separation layer (204) has an extinction coefficient of at least 10 at the wavelength. [7] The method of claim 1, wherein the wavelength is selected from a range between 1,200 nm and 6,000 nm. [8] The method of claim 1, wherein the wavelength is selected from a range between 1,200 nm and 2,500 nm. [9] The method of claim 1, wherein the optical gain layer (206) is formed of a material selected from the group consisting of amorphous silicon, amorphous germanium, and polycrystalline germanium. [10] A method of handling a wafer (102), the method comprising: Connecting a gripper (106) to the wafer using a bonding layer (104) comprising a separation layer (204), an optical gain layer (206), an optical interface layer (202), and an anti-reflection layer (208); Positioning the gripper (106) and Separating the gripper (106) from the wafer using a laser that emits laser energy at a wavelength that is absorbed by the separation layer (204) and concentrated by the optical gain layer (206) onto the separation layer (204), and that is reflected back to the separation layer (204) by the optical interface layer (202) such that the material of the separation layer (204) is ablated when it is exposed to the laser energy to release the wafer (102). [11] The method of claim 10, wherein connecting the gripper (106) to the wafer comprises applying an adhesive layer to the connecting layer (104). [12] The method of claim 11, wherein the adhesive layer is a polyimide layer. [13] Gripper wafer comprising: a gripper layer (106) formed of a material that is transparent at a wavelength of light; a connecting layer (104) containing: a separation layer (204) that absorbs the light at the wavelength of light and is formed of a material that has a real refractive index greater than 3.0 and an extinction coefficient greater than 5.0 at the wavelength of light; an optical gain layer (206) formed of a material, which is transparent at the wavelength of light and has a refractive index greater than 2.0 to concentrate energy at the wavelength of light onto the separation layer (204); and an optical interface layer (202) disposed on a side of the separation layer (204) opposite the gripper layer (106) and reflecting laser energy of the light wavelength into the separation layer (204). [14] The gripper wafer of claim 13, wherein the separation layer (204) contains a metallic material selected from the group consisting of magnesium, iron, nickel, rhodium, palladium, platinum, and lutetium. [15] The gripper wafer of claim 14, wherein the metal of the separation layer (204) has an extinction coefficient of at least 10 at the wavelength of light. [16] The gripper wafer of claim 13, wherein the light wavelength is selected from a range between 1,200 nm and 6,000 nm. [17] The gripper wafer of claim 16, wherein the light wavelength is selected from a range between 1,200 nm and 2,500 nm. [18] The gripper wafer of claim 13, wherein the optical gain layer (206) is formed from a material selected from the group consisting of amorphous silicon, amorphous germanium, and polycrystalline germanium. [19] The gripper wafer of claim 13, further comprising an anti-reflection layer (208) between the optical gain layer and the gripper layer (106). [20] The gripper wafer of claim 13, wherein the gripper layer (106) is formed of a semiconductor material containing silicon. [21] Gripper wafer comprising: a gripper layer (106) formed of a material that is transparent at a wavelength of light; a connecting layer (104) containing: a separation layer (204) which absorbs the light of the light wavelength and is formed from a material which has a real refractive index greater than 3.0 and an extinction coefficient greater than 5.0 at the light wavelength; an optical gain layer (206) formed of a material that is transparent at the wavelength of light and has a refractive index greater than 2.0 for concentrating energy at the wavelength of light onto the separation layer (204); and an optical interface layer (202) formed from a material having a real refractive index of less than 2.0, disposed on a side of the separation layer (204) opposite the gripper layer (106) and reflecting laser energy of the light wavelength into the separation layer (204). [22] The gripper wafer of claim 21, wherein the bonding layer (104) further comprises an adhesive layer. [23] The gripper wafer of claim 22, wherein the adhesive layer is formed of polyimide. [24] Gripper wafer comprising: a gripper layer (106) formed of silicon; a connecting layer (104) containing: a separation layer (204) that absorbs light of a wavelength from a separation laser selected from a range between 1,200 nm and 2,500 nm and formed from a metallic material selected from the group consisting of magnesium, iron, nickel, rhodium, palladium, platinum and lutetium; an optical gain layer (206) formed of a material selected from the group consisting of amorphous silicon, amorphous germanium, and polycrystalline silicon for concentrating laser energy at the wavelength of light onto the separation layer (204); an optical interface layer (202) on a side of the separation layer (204) opposite the gripper layer (106) for reflecting the light at the wavelength into the separation layer (204) and providing an adhesive bond to a wafer; and an anti-reflection layer (208) between the optical gain layer (206) and the gripper layer (106).

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