Processing method, chip manufacturing method, and thinned wafer manufacturing method

Abstract

The present invention provides a processing method for forming a workpiece comprising a first member, a second member, and an adhesive portion, which can reduce the time required for workpiece formation while forming a workpiece of suitable quality for processing. [Solution] The present invention relates to a processing method for forming a workpiece in which a first member and a second member are laminated and an adhesive portion containing a photocurable substance is provided between the first member and the second member, comprising: a first curing light irradiation step of irradiating the material to be the adhesive portion with curing light so that the material has adhesive properties and fluidity after irradiation; a joining step of joining the first member and the second member with the material to be the adhesive portion, which has been irradiated with curing light in the first curing light irradiation step, in between; a second curing light irradiation step of irradiating the exposed portion of the adhesive portion with curing light after the joining step; and a processing step of processing the workpiece after the second curing light irradiation step.

Description

Technical Field

[0001] The present invention relates to a processing method used when forming a workpiece in which a first member and a second member are laminated and an adhesive portion containing a photocurable substance is provided between the first member and the second member, and a method for manufacturing a chip and a method for manufacturing a thinned wafer using the processing method.

Background Art

[0002] Device chips mounted on electronic devices such as mobile phones and personal computers are manufactured by processing semiconductor wafers.

[0003] On one surface of a disk-shaped semiconductor wafer, a plurality of dividing planned lines (streets) are set in a grid pattern, and devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed in each rectangular region partitioned by the dividing planned lines. By cutting the semiconductor wafer on which the devices are formed along each dividing planned line, the semiconductor wafer is divided into a plurality of device chips.

[0004] In recent years, in the manufacture of such device chips, the wafer is thinned in order to reduce the size and weight of the chip. For example, in the manufacturing process of the device chip as described above, the entire wafer is thinned by grinding the back surface of the wafer on which the device is formed on the surface.

[0005] In the manufacturing process of a wafer involving such thinning, in order to maintain the strength even after the wafer is thinned, a laminated wafer in which another wafer is joined to the wafer to be processed as a support substrate may be used. By subjecting the wafer to be processed (first member) joined to the support substrate (second member) to grinding, while the first member is thinned, a thickness sufficient to maintain the strength of the entire laminated wafer is maintained (see, for example, Patent Document 1).

[0006] In such laminated wafers, a photocurable material is sometimes used to bond the first and second components. A photocurable material is, for example, an ultraviolet-curing resin that begins to harden when irradiated with ultraviolet light of a specific wavelength. The photocurable material is sandwiched between the first and second components as an adhesive layer, forming a laminated wafer.

[0007] In this case, if the first and second members are made of materials with low transmittance to ultraviolet light, even if ultraviolet light is irradiated after the ultraviolet-curing resin has been sandwiched between the first and second members, the entire adhesive layer made of ultraviolet-curing resin cannot be properly cured. On the other hand, if ultraviolet light is irradiated onto the adhesive layer before joining, the hardening of the adhesive layer will begin before joining, so depending on the timing of the irradiation and the speed of hardening, problems may occur in joining the first and second members.

[0008] Therefore, a method has been adopted in which a delayed-curing UV-curing resin, which takes a certain amount of time to harden after irradiation with ultraviolet light, is used as the photocurable material that forms the adhesive layer, and after irradiating the adhesive layer with ultraviolet light, the first member and the second member are bonded together while the adhesive layer has sufficient fluidity for bonding before the adhesive layer has completely hardened.

[0009] However, even with such methods, it is not easy to set conditions that allow for favorable bonding. For example, with regard to ultraviolet irradiation, increasing the irradiation time shortens the time it takes for the adhesive layer to harden, thus reducing the time required for bonding and improving manufacturing efficiency. However, the longer the irradiation time, the greater the viscosity of the adhesive layer when bonding the first and second members.

[0010] If the viscosity of the adhesive layer is too high, when bonding the first and second components, the adhesive layer will not spread easily between the opposing first and second components, making it difficult to obtain a laminated wafer in which the adhesive layer has sufficiently spread to the outer edge.

[0011] On the other hand, if the UV irradiation time is shortened to prioritize the ease with which the adhesive layer spreads during bonding, the waiting time required for the adhesive layer to fully cure after bonding will increase, leading to a decrease in manufacturing efficiency.

[0012] Shortening the UV irradiation time and reducing the waiting time for the adhesive layer to harden means that grinding, polishing, cutting, and other processes will be performed on the laminated wafer before the adhesive layer has fully hardened. As a result, the possibility of problems such as delamination between components and contamination of the processing room and equipment increases. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Japanese Patent Publication No. 2024-34584 [Overview of the project] [Problems that the invention aims to solve]

[0014] The object of the present invention is to provide a processing method, a chip manufacturing method, and a wafer manufacturing method that can form a workpiece of suitable quality for processing while reducing the time required to form the workpiece, which comprises a first member, a second member, and an adhesive portion. [Means for solving the problem]

[0015] According to one aspect of the present invention, a processing method is provided for forming a workpiece in which a first member and a second member are laminated and an adhesive portion containing a photocurable substance is provided between the first member and the second member, the processing method comprising: a first curing light irradiation step of irradiating the material that will become the adhesive portion with curing light so that the material has adhesive properties and fluidity after irradiation; a joining step of joining the first member and the second member with the material that will become the adhesive portion, which has been irradiated with curing light in the first curing light irradiation step, in between; a second curing light irradiation step of irradiating the exposed portion of the adhesive portion with curing light after the joining step; and a processing step of processing the workpiece after the second curing light irradiation step.

[0016] Preferably, the first member is thinned in the processing step.

[0017] Preferably, the photocurable substance contained in the adhesive portion has properties that allow curing to be accelerated by heat, and the processing step includes a first processing step of processing the workpiece and a second processing step of processing the workpiece after the first processing step, wherein in the first processing step the workpiece is processed under conditions that cause the temperature of the adhesive portion to rise more easily than in the second processing step.

[0018] According to another aspect of the present invention, a method for manufacturing a chip is provided, wherein the workpiece is formed by the processing method described in claim 1, the first member is a plate-shaped article, and the chip is manufactured by dividing the first member in the processing step.

[0019] According to yet another aspect of the present invention, a method for manufacturing a thinned wafer is provided, wherein the workpiece is formed by the processing method described in claim 1, the first member is a plate-shaped article, and the processing step involves thinning the first member to produce a thinned wafer. [Effects of the Invention]

[0020] In the processing method according to one aspect of the present invention, and in the method for manufacturing a chip and the method for manufacturing a thinned wafer using the same, in forming a workpiece in which a first member and a second member are laminated, first, a curing light is irradiated onto a material that will be an adhesive part to such an extent that the photocurable substance is not completely cured. Subsequently, after the first member and the second member are joined, the curing light is irradiated onto a part (outer peripheral part) exposed between the first member and the second member in the adhesive part.

[0021] When the irradiation of the curing light and the joining of the first and second members are performed in such a procedure, at the time of joining, since the material that becomes the adhesive part has adhesiveness and fluidity, the material that becomes the adhesive part adheres to both wafers and spreads well between the first member and the second member, and the joining of the first and second members is suitably performed.

[0022] Subsequently, the curing light is irradiated onto the outer peripheral part of the adhesive part exposed between the first member and the second member, thereby promoting the curing of the outer peripheral part of the adhesive part. As a result, an adhesive strength that can withstand subsequent processing is obtained as a whole. Thereby, while reducing the time required for forming the workpiece, a workpiece of suitable quality for processing can be formed.

Brief Description of the Drawings

[0023] [Figure 1] FIG. 1 is a perspective view showing an example of the form of a workpiece formed by laminating a first member and a second member. [Figure 2] FIG. 2 is a flowchart for explaining an example of the procedure related to the processing method for forming a workpiece, and the method for manufacturing a chip and the method for manufacturing a thinned wafer using the same. [Figure 3] FIG. 3 is a flowchart for explaining an example of the content of the processing steps in the procedure of FIG. 2. [Figure 4] FIG. 4 is a side view schematically showing one step in the procedure of FIGS. 2 to 3, and shows a state in which the curing light is irradiated onto the material that becomes the adhesive part in the first curing light irradiation step. [Figure 5]Figure 5 is a schematic side view illustrating one step in the procedure shown in Figures 2 and 3, showing how the first member and the second member are joined together in the joining step. [Figure 6] Figure 6 is a schematic side view illustrating one step in the procedure shown in Figures 2 and 3, and shows how curing light is irradiated onto the adhesive area during the second curing light irradiation step. [Figure 7] Figure 7 is a schematic side view showing one step in the procedure in Figures 2 and 3, illustrating another example of the arrangement of each part in the second curing light irradiation step. [Figure 8] Figure 8 is a schematic side view showing one step in the procedure shown in Figures 2 and 3, illustrating how the first member is ground during the first and second processing steps of the processing procedure. [Figure 9] Figure 9 is a schematic side view showing one step in the procedure shown in Figures 2 and 3, illustrating how the first member is peeled away from the adhesive during the peeling step of the processing steps. [Figure 10] Figure 10 is a schematic side view showing one step in the procedure shown in Figures 2 and 3, illustrating how the first component is attached to the adhesive tape during the attachment step of the processing steps. [Figure 11] Figure 11 is a schematic side view showing one step in the procedure shown in Figures 2 and 3, illustrating how the first component is divided during the division step of the processing steps. [Modes for carrying out the invention]

[0024] Embodiments of the present invention will be described with reference to the attached drawings.

[0025] First, referring to Figure 1, we will explain the processing method for forming a workpiece, as well as the workpieces handled in the method for manufacturing chips and thinned wafers using this method. Figure 1 is a perspective view showing an example of the form of a workpiece formed by stacking a first member and a second member.

[0026] The workpiece 2, which is a stacked wafer, has a configuration in which a first member (wafer) 4 and a second member (wafer) 6, each in the shape of a plate, are stacked, and an adhesive portion 8 containing a photocurable material is sandwiched between the first wafer 4 and the second wafer 6.

[0027] The first wafer 4 and the second wafer 6 are disc-shaped wafers formed from silicon, and are joined to each other on one side by an adhesive portion 8.

[0028] On the side of the first wafer 4 that is joined to the second wafer 6 via the adhesive portion 8, a device such as an IC (Integrated Circuit) or LSI (Large Scale Integration) is formed. Note that the device may be formed in a later process.

[0029] The second wafer 6 is a so-called dummy wafer, also known as an NP (Non-Product) wafer or QC (Quality Control) wafer, and no device is formed on it.

[0030] There are no restrictions on the type, material, shape, structure, size, etc., of the first wafer 4 and the second wafer 6. For example, the first and second wafers 4 and 6 may be substrates (wafers) made of semiconductors other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, etc. There are also no restrictions on the type, number, shape, structure, size, arrangement, etc., of the devices formed on the first wafer 4. Devices may not even be formed on the first wafer 4.

[0031] The first wafer 4 and the second wafer 6 may be made of the same material or different materials. Furthermore, the first wafer 4 and the second wafer 6 may be formed in the same shape or different shapes. However, it is preferable that the second wafer 6 has a size and shape that can support the entirety of the first wafer 4.

[0032] The adhesive portion 8 is located between the first wafer 4 and the second wafer 6, and by adhering to the first wafer 4 and the second wafer 6 respectively, it forms an adhesive layer that joins the first wafer 4 and the second wafer 6 together.

[0033] The adhesive portion 8 contains a photocurable material. A photocurable material is a material that begins to harden when irradiated with light of a specific range of wavelengths, such as an ultraviolet-curable resin. In this specification, "the adhesive portion 8 contains a photocurable material" includes not only cases where a part of the material forming the adhesive portion 8 is a photocurable material, but also cases where the entire adhesive portion 8 is composed of a photocurable material. The photocurable material may consist of a single substance or a mixture of several types of substances.

[0034] The light used to cure the photocurable material contained in the adhesive portion 8 is referred to here as "curing light." For example, if the adhesive portion 8 contains an ultraviolet-curable resin as the photocurable material, the curing light is ultraviolet light.

[0035] The photocurable substance contained in the adhesive portion 8 is preferably a delayed-curing type substance that does not harden immediately upon irradiation with curing light, but gradually hardens over a certain period of time (several minutes to several tens of minutes) after irradiation with curing light. Examples of such delayed-curing photocurable substances include polyfunctional epoxy resins, monofunctional epoxy compounds, and polyfunctional oxetane resins.

[0036] Next, the processing methods used in relation to the formation of the workpiece (layered wafer) 2 described above will be explained with reference to Figures 2, 3, and 4 to 11. Figure 2 is a flowchart illustrating an example of the procedure for processing the workpiece, as well as a chip manufacturing method and a thinned wafer manufacturing method using the same. Figure 3 is a flowchart illustrating an example of the contents of the processing steps in the procedure of Figure 2. Figures 4 to 11 are schematic side views showing one step in the procedure of Figures 2 to 3, respectively.

[0037] First, curing light is irradiated onto the material that will become the adhesive portion 8 in the workpiece (laminated wafer) 2 (see Figure 1) that will be formed later (first curing light irradiation step S10). Figure 4 shows how curing light is irradiated onto the material that will become the adhesive portion in the first curing light irradiation step S10.

[0038] As shown in Figure 4, for example, a material that will become an adhesive portion 8 containing a photocurable substance is placed on one side of a plate-shaped second wafer 6, and curing light is irradiated onto the material that will become the adhesive portion 8 from a light source device 10 that emits curing light (in Figure 4, the material that will become the adhesive portion 8 is given the same designation "8" as the adhesive portion. The same applies in Figure 5). If the photocurable substance contained in the material that will become the adhesive portion 8 is an ultraviolet curing resin, the light source device 10 may be, for example, a high-pressure mercury lamp or metal halide lamp that emits ultraviolet light by performing an arc discharge on a metal vapor, or a UV-LED that generates ultraviolet light from an LED element.

[0039] Here, the material that will become the adhesive portion 8 is irradiated with curing light under conditions (intensity of curing light, wavelength, irradiation time, temperature, etc.) such that the material that will become the adhesive portion 8 does not completely harden, that is, the material that will become the adhesive portion 8 retains adhesiveness and fluidity after irradiation with curing light.

[0040] In addition, during the irradiation of curing light in the first curing light irradiation step S10, instead of placing the material that will become the adhesive portion 8 on the second wafer 6, the material that will become the adhesive portion 8 may be placed on the first wafer 4.

[0041] Next, as shown in Figure 5, the first wafer 4 and the second wafer 6 are joined to each other so as to sandwich the material that will become the adhesive portion 8, which has been irradiated with curing light (joining step S20). Figure 5 shows how the first member (wafer) 4 and the second member (wafer) 6 are joined in joining step S20.

[0042] Furthermore, when the material that will become the adhesive portion 8 is irradiated with curing light in the first curing light irradiation step S10, the photocurable substance contained in the material that will become the adhesive portion 8 begins to harden. Therefore, the bonding step S20 must be completed before the photocurable substance has completely finished hardening.

[0043] In the laminated wafer 2 thus formed, as shown in Figure 6, the first wafer 4 and the second wafer 6 are laminated with an adhesive portion 8 in between. Most of the adhesive portion 8 is sandwiched on both sides by the first wafer 4 and the second wafer 6 and is not exposed to the outside, but only the outer periphery of the adhesive portion 8 is slightly exposed between the first wafer 4 and the second wafer 6. The exposed portion of the adhesive portion 8 is further irradiated with curing light from the light source device (second curing light irradiation step S60).

[0044] Figure 6 shows how the adhesive portion 8 is irradiated with curing light in the second curing light irradiation step S30. Here, curing light is irradiated from a light source device 10 positioned laterally to the stacked wafer 2 (later to the virtual axis that penetrates the first wafer 4, the adhesive portion 8, and the second wafer 6). Since the adhesive portion 8 is exposed on the side surface of the stacked wafer 2, irradiating it with curing light from the side ensures that the exposed adhesive portion 8 is efficiently irradiated with curing light.

[0045] In this case, the stacked wafer 2 may rotate around the virtual axis relative to the light source device 10, or the light source device 10 positioned to the side of the stacked wafer 2 may move circumferentially relative to the stacked wafer 2 while irradiating the side surface of the stacked wafer 2 with curing light, or the stacked wafer 2 may be irradiated with curing light from a light source device 10 positioned to surround the side of the stacked wafer 2.

[0046] Alternatively, if the curing light reaches the adhesive portion 8 exposed on the side surface of the stacked wafer 2 due to the direction of the curing light emitted from the light source device 10 or reflection of the curing light by surrounding objects, the light source device 10 may be arranged such that the curing light is emitted from above and below (from a direction along the virtual axis; from below in Figure 7), as shown in Figure 7. Figure 7 shows an example of the arrangement of each part in the second curing light irradiation step S30, different from that in Figure 6.

[0047] It should be noted that "the adhesive portion 8 is exposed" in this context means that it is optically exposed to the curing light being irradiated, and does not necessarily mean that the adhesive portion 8 is not covered by any material. For example, even if the adhesive portion 8 is separated from the external space or light source by a film or wall made of a material that transmits curing light, it is still described as "the adhesive portion 8 is exposed."

[0048] In this manner, the first wafer 4 and the second wafer 6 are joined together, and the laminated wafer 2, which has been irradiated with curing light at the bonding portion 8, is subjected to processing step S40. Processing step S40 includes, for example, a first processing step S41, a second processing step S42, a peeling step S43, a bonding step S44, and a splitting step S45, as shown in Figure 3.

[0049] Figure 8 shows the grinding of the first member (wafer) 4 in the first processing step S41 and the second processing step S42 of processing step S40. Figure 9 shows the peeling of the first member (wafer) 4 from the adhesive portion 8 in the peeling step S43 of processing step S40. Figure 10 shows the attachment of the first member (wafer) 4 to the protective member (adhesive tape) 32 in the attachment step S44 of processing step S40. Figure 11 shows the division of the first member (wafer) 4 in the division step S45 of processing step S40.

[0050] In the first processing step S41 and the second processing step S42, for example, a first component (wafer) 4 that forms part of the workpiece (stacked wafer) 2 is ground. The grinding apparatus 12 used for grinding, as shown in Figure 8, includes a holding mechanism 14 that holds the workpiece (stacked wafer) 2 and a grinding mechanism 20 that grinds the workpiece held by the holding mechanism 14.

[0051] The holding mechanism 14 is, for example, a chuck table, which is designed to hold the stacked wafer 2, which is the workpiece, by suction. The holding mechanism 14, which is a chuck table, has a disc-shaped table base 16 made of a material such as ceramics or metal, and a suction plate 18 attached to the table base 16.

[0052] The suction plate 18 is a disc-shaped member made of, for example, porous ceramics. A disc-shaped recess corresponding to the dimensions of the suction plate 18 is formed on the upper part of the table base 16, and the suction plate 18 is fixed by fitting into this recess. A flow channel (not shown) is formed inside the table base 16, and one end of the flow channel is connected to the lower surface of the suction plate 18.

[0053] The other end of the channel provided within the table base 16 is connected to a suction source (not shown), such as an ejector. When the suction source is activated, the negative pressure supplied to the channel acts on an object such as a stacked wafer 2 placed on the upper surface 18a of the suction plate 18. In this way, the upper surface 18a of the suction plate 18 functions as a holding surface for holding the stacked wafer 2. The suction plate 18 may be, for example, a plate-shaped member of metal or the like with multiple holes that penetrate vertically through it.

[0054] A rotation mechanism (not shown) is connected to the lower part of the holding mechanism 14, which rotates the holding mechanism 14 around a rotation axis aligned vertically (a rotation axis extending in a direction approximately perpendicular to the holding surface 18a).

[0055] The grinding mechanism 20 comprises a spindle housing 22 and a spindle 24, which is a rotating body housed in the spindle housing 22. The spindle 24, which is a cylindrical member, is rotatably supported relative to the spindle housing 22 with respect to an axis provided along the vertical direction.

[0056] The lower end of the spindle 24 is exposed to the outside of the spindle housing 22, and a disc-shaped wheel mount is fixed to the tip of the lower end of the spindle 24. A disc-shaped grinding wheel 26, which has approximately the same diameter as the wheel mount, is mounted on the lower surface of the wheel mount. Multiple grinding wheels 28 are fixed around the entire circumference of the lower surface of the grinding wheel 26.

[0057] A rotational drive source (not shown), such as a motor, is connected to the upper end of the spindle 24, causing the spindle 24 to rotate together with the grinding wheel 26.

[0058] The grinding apparatus 12 is further equipped with a processing liquid supply unit (not shown). The processing liquid supply unit is, for example, a nozzle that supplies water as the processing liquid. The discharge port of the processing liquid supply unit, which is a nozzle, is provided, for example, above the holding mechanism 14 to supply water to the workpiece held by the holding mechanism 14. The grinding apparatus 12 may also be equipped with a processing liquid supply unit that supplies the processing liquid through the grinding mechanism 20.

[0059] During grinding, the stacked wafer 2 is held on the holding surface 18a of the holding mechanism 14 with the first wafer 4 facing upwards and the second wafer 6 facing downwards. The grinding mechanism 20 is positioned above the stacked wafer 2 held by the holding mechanism 14 so that, in a plan view, the stacked wafer 2 and the grinding wheel 26 overlap.

[0060] Next, the holding mechanism 14 rotates about an axis aligned vertically, and the spindle 24 of the grinding mechanism 20, to which the grinding wheel 26 is attached, also rotates about an axis aligned vertically. As both the holding mechanism 14 and the spindle 24 rotate and move closer to each other in the vertical direction, the first wafer 4 of the stacked wafer 2 held by the holding mechanism 14 and the grinding wheel 28 of the grinding wheel 26 attached to the spindle 24 of the grinding mechanism 20 come into contact with each other while rotating.

[0061] The first wafer 4 is ground by the sliding motion between the grinding wheel 28 and the first wafer 4. As the first wafer 4 is ground and the grinding wheel 28 wears down, the holding mechanism 14 and the grinding mechanism 20 are moved relative to each other in the vertical direction by a moving mechanism (not shown) so that the grinding wheel 28 and the first wafer 4 move slightly closer to each other. During grinding, water is supplied as a processing liquid from a processing liquid supply unit (not shown) to the area of ​​the stacked wafer 2 that is being ground. In this way, the first wafer 4 is thinned.

[0062] Next, the second processing step S42 is performed. In the second processing step S42, the first wafer 4 is ground in the same way as in the first processing step S41, and the first wafer 4 is thinned.

[0063] The grinding in the first processing step S41 and the grinding in the second processing step S42 are performed, for example, as rough grinding and finish grinding, respectively, by changing conditions such as the rotational speed of the grinding wheel 26 and the feed rate (the speed at which the stacked wafer 2 and the grinding wheel 28 approach each other in the vertical direction during grinding). Different grinding devices may be used for the grinding in the first processing step S41 and the grinding in the second processing step S42, or the grinding wheel 26 and grinding wheel 28 may be replaced when moving from the first processing step S41 to the second processing step S42. Alternatively, the same grinding device 12 may be used for both the first processing step S41 and the second processing step S42.

[0064] Thus, in the first processing step S41 and the second processing step S42 of the processing step S40, the first component (wafer) 4 that forms the workpiece (laminated wafer) 2 is thinned, and a thinned wafer is manufactured.

[0065] In the procedure described here, in forming the stacked wafer 2, first, the material that will become the adhesive portion 8 is irradiated with curing light to the extent that the photocurable substance does not completely harden (first curing light irradiation step S10), and then, after the first wafer 4 and the second wafer 6 are joined (joining step S20), a portion of the adhesive portion 8 exposed between the first wafer 4 and the second wafer 6 (outer periphery) is irradiated with curing light (second curing light irradiation step S30).

[0066] When curing light irradiation and bonding of the first and second wafers 4 and 6 are performed in this procedure, the material forming the bonding portion 8 has adhesive and fluid properties during bonding. As a result, the material forming the bonding portion 8 adheres well to both wafers and spreads well between the first wafer 4 and the second wafer 6, allowing for favorable bonding of the first wafer 4 and the second wafer 6.

[0067] Furthermore, the conditions related to the irradiation of curing light in the first curing light irradiation step S10 and the bonding in the bonding step S20 (such as the intensity of the curing light, the placement of the light source device 10 relative to the material that will become the bonding portion 8, temperature, irradiation time, the time from irradiation of curing light until bonding of the first wafer 4 and the second wafer 6, and the force applied to the first and second wafers 4 and 6 during bonding) should be adjusted as appropriate so that the curing light is reliably irradiated onto the material that will become the bonding portion 8 and that bonding of the first and second wafers 4 and 6 can be performed without any problems.

[0068] Since the bonding step S20 is performed while the material forming the adhesive portion 8 is tacky and fluid, the adhesive portion 8 is not yet fully cured when the bonding step S20 is completed. Therefore, in the subsequent second curing light irradiation step S30, curing light is irradiated onto the outer periphery of the adhesive portion 8 exposed between the first wafer 4 and the second wafer 6, thereby accelerating the curing of the outer periphery of the adhesive portion 8.

[0069] If, after the bonding step S20 is completed, the processing step S40 is immediately performed on the stacked wafer 2 without going through the second curing light irradiation step S30, the curing of the adhesive portion 8 will be incomplete at the start of the processing step S40. As a result, there is a risk that misalignment may occur between the first wafer 4 and the second wafer 6, or that defects such as cracks or chips may occur in the first wafer 4.

[0070] Photocurable materials such as UV-curing resins begin to harden once exposed to curing light, even with a short exposure time, and continue to harden over time. The rate of hardening is positively correlated with the exposure time of the curing light; if the exposure time is short, hardening will occur, but the rate will be slower, and the time it takes for the photocurable material to harden completely will be longer.

[0071] Therefore, after the bonding step S20, if a certain amount of time is allowed, a laminated wafer 2 can be obtained in a state where the bonded portion 8 is sufficiently hardened. However, if the waiting time required for the bonded portion 8 to harden is prolonged, it will directly lead to a decrease in manufacturing efficiency.

[0072] Therefore, in this procedure, after the bonding step S20, a second curing light irradiation step S30 is performed so that the exposed outer periphery of the bonded portion 8 is cured. In this second curing light irradiation step S30, it is assumed that the curing light does not sufficiently reach the central region of the bonded portion 8 that is not exposed, and therefore, it is possible that the bonded portion 8 in the central region is not completely cured and still retains fluidity. However, if even a part of the bonded portion 8 (the outer periphery) is irradiated with curing light, the cumulative irradiation time of the curing light in that part becomes longer, promoting curing and obtaining an adhesive strength that can withstand subsequent processing.

[0073] Furthermore, if the photocurable substance contained in the adhesive portion 8 has properties that accelerate curing with heat, it can be expected that the curing of the adhesive portion 8 will be accelerated as the temperature of the adhesive portion 8 rises during processing step S40.

[0074] Some photocurable materials, such as UV-curing resins, require irradiation with curing light, such as ultraviolet light, to initiate curing, and the subsequent curing process is affected by temperature. If the adhesive portion 8 contains such a material as a photocurable material, and a process that generates heat is performed in processing step S40, the curing of the photocurable material contained in the adhesive portion 8 may be accelerated by that heat.

[0075] For example, in the processing step S40 described here, the first processing step S41 and the second processing step S42 each involve grinding the first wafer. During this process, frictional heat is generated between the grinding wheel 28 and the first wafer 4. Depending on the conditions, this frictional heat may be transmitted to the adhesive portion 8, causing the temperature of the adhesive portion 8 to rise and accelerating its hardening.

[0076] Here, in the processing step S40, if the processing of the workpiece (laminated wafer) 2 is performed under conditions that cause the temperature of the bonded portion 8 to rise more easily in the first processing step S41 compared to the second processing step S42 that follows, it is preferable for ensuring the adhesive strength of the bonded portion 8 when the second processing step S42 is performed. First, in the first processing step S41, the bonded portion 8 hardens rapidly due to the rise in temperature of the bonded portion 8, so it can be expected that the bonded portion 8 is well hardened by the start of the subsequent second processing step S42, and that sufficient adhesive strength to withstand the processing in the second processing step S42 is obtained.

[0077] In particular, when a workpiece is thinned by processes such as grinding and polishing, the strength of the thinned portion of the workpiece decreases as the process progresses. To compensate for the strength reduction caused by thinning, it is desirable that the entire adhesive portion 8 be sufficiently hardened in the later stages of the thinning process.

[0078] If the temperature of the adhesive portion 8 rises significantly in the first processing step S41, the hardening of the adhesive portion 8 will be accelerated, and it is expected that a laminated wafer 2 with the entire adhesive portion 8 fully hardened will be obtained at the start of the second processing step S42.

[0079] For example, if the first wafer 4 is ground in the first and second processing steps S41 and S42, respectively, in the first processing step S41, the processing conditions can be set to conditions that make it easier for the temperature of the stacked wafer 2 to rise, compared to the second processing step S42. Specifically, for example, this can be done as follows.

[0080] (Condition setting 1) Regarding the flow rate of the processing liquid supplied from the processing liquid supply unit to the area of ​​the laminated wafer 2 where processing is performed, the flow rate of the processing liquid supplied in the first processing step S41 is less than the flow rate of the processing liquid supplied in the second processing step S42. Alternatively, no processing liquid is supplied in the first processing step S41, and processing liquid is supplied in the second processing step S42. When the frictional heat generated by grinding is transferred to the processing liquid, the laminated wafer 2 is cooled and its temperature drops. If the flow rate of the processing liquid is low or zero, the temperature drop due to cooling is suppressed.

[0081] (Condition setting 2) With respect to the temperature of the processing liquid supplied from the processing liquid supply unit to the region where the laminated wafer 2 is processed, the temperature of the processing liquid supplied in the first processing step S41 is higher than the temperature of the processing liquid supplied in the second processing step S42.

[0082] (Condition setting 3) With respect to the relative feed rate in the vertical direction between the grinding wheel 28 and the stacked wafer 2 (the vertical movement speed of the holding mechanism 14 or grinding mechanism 20 during grinding), the feed rate in the first processing step S41 is faster than the feed rate in the second processing step S42. A faster feed rate means that the amount of wear per unit time of the stacked wafer 2 and the grinding wheel 28 is large. In other words, the frictional force during grinding is large, and the amount of frictional heat generated is large.

[0083] (Condition setting 4) Regarding the rotational speed of the grinding wheel 26, the rotational speed of the grinding wheel 26 in the first processing step S41 is faster than the rotational speed of the grinding wheel 26 in the second processing step S42. If the rotational speed of the grinding wheel 28 relative to the stacked wafer 2 is faster, the amount of frictional heat generated will increase.

[0084] (Condition setting 5) Regarding the rotational speed of the holding mechanism 14, the rotational speed of the holding mechanism 14 in the first processing step S41 is faster than the rotational speed of the holding mechanism 14 in the second processing step S42. If the rotational speed of the stacked wafer 2 relative to the grinding wheel 28 is faster, the amount of frictional heat generated will increase.

[0085] (Condition setting 6) With respect to the grinding wheel 28, the density of pores in the grinding wheel 28 used in the first processing step S41 is smaller than the density of pores in the grinding wheel 28 used in the second processing step S42. If the density of pores in the grinding wheel 28 is small, the material of the grinding wheel 28 will be in close contact with the first wafer 4 during grinding, and as a result, more frictional heat will be generated. In addition, during grinding, frictional heat is transferred to the processing liquid as the processing liquid enters the pores of the grinding wheel 28, cooling the grinding wheel 28 and the first wafer 4. However, if the density of pores is small, the cooling effect by this mechanism is reduced, and the temperature is more likely to rise.

[0086] It should be noted that not all of the above conditions 1 to 6 need to be set as described above. It is sufficient if some of the above conditions 1 to 6 are set as described above, so that the temperature of the stacked wafer 2 rises more easily in the first processing step S41 than in the second processing step S42.

[0087] For example, under condition setting 1, the flow rate of the processing liquid in the first processing step S41 is greater than the flow rate of the processing liquid in the second processing step S42. However, under condition setting 2, the temperature of the processing liquid in the first processing step S41 is higher than the temperature of the processing liquid in the second processing step S42. Therefore, the temperature of the stacked wafer 2 is more likely to rise in the first processing step S41 than in the second processing step S42.

[0088] In addition to the above-mentioned conditions, other conditions can be considered to adjust how easily the temperature of the stacked wafer 2 rises in the first processing step S41 and the second processing step S42. For example, a mechanism for heating or cooling the holding mechanism 14, grinding wheel 28, etc., may be provided, or the temperature of the stacked wafer 2 may be adjusted by manipulating the temperature of the air in the space where the processing is performed.

[0089] Furthermore, various processes other than grinding, as described above, can be envisioned for the processing performed in the first and second processing steps. For example, polishing, in addition to grinding, can be used as a process to thin the workpiece. For polishing, a polishing device equipped with a polishing mechanism having a polishing pad instead of the grinding wheel 26 in the grinding device 12 described above is used. For example, polishing may be performed in both the first and second processing steps, or grinding may be performed in the first processing step and polishing in the second processing step.

[0090] Furthermore, in the processing step S40 shown in Figure 3, the peeling step S43, the adhesive step S44, and the dividing step S45 are performed.

[0091] In the delamination step S43, as shown in Figure 9, the first wafer 4 and the second wafer 6, which each form part of the stacked wafer 2, are separated from each other. In the example shown in Figure 9, the first wafer 4 is separated from the adhesive portion 8, but the first wafer 4 may be separated from the second wafer 6 together with the adhesive portion 8. Delamination may be performed, for example, by irradiating the stacked wafer 2 with an infrared laser to weaken the adhesive force of the adhesive portion 8, or by impregnating the adhesive portion 8 with a liquid such as water or an organic solvent to weaken the adhesive force. Alternatively, delamination may be performed by inserting a claw-shaped or plate-shaped delamination body between the first wafer 4 and the second wafer 6 from the outer edge, or by injecting a fluid between the first wafer 4 and the second wafer 6 and performing delamination by the pressure of the fluid.

[0092] The peeled first wafer is, if necessary, attached to an adhesive tape 32 as a protective member, as shown in Figure 10, for the convenience of handling such as transport and holding (attachment step S44). The adhesive tape 32 is then attached to an annular frame 34.

[0093] The frame 34 is a plate-shaped component made of a metal such as SUS (stainless steel). An opening is provided in the center of the frame 34, penetrating it in the thickness direction. The diameter of this opening is set to be larger than the diameter of the first wafer 4.

[0094] The adhesive tape 32 is composed of, for example, a circular film-shaped base material with a diameter larger than the central opening of the frame 34, and an adhesive layer provided on the base material. The base material is formed from an elastic resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer is made from an epoxy, acrylic, or rubber-based adhesive, and this material is applied to at least one side of the base material to form the adhesive layer.

[0095] The first wafer 4 is placed inside the opening of the frame 34, and with the first wafer 4 surrounded by the frame 34, the central part of the adhesive tape 32 is attached to the first wafer 4, and the outer periphery of the adhesive tape 32 is attached to the frame 34, thereby supporting the first wafer 4 in the frame 34.

[0096] Thus, the first wafer 4 is handled in a frame unit state in which the first wafer 4 is supported on the frame 34 via adhesive tape 32.

[0097] A splitting step S45 is performed on the first wafer 4, which forms part of the frame unit. The splitting step S45 is performed, for example, using a cutting device 36 as shown in Figure 11.

[0098] The cutting apparatus 36 in Figure 11 includes a holding mechanism 38 for holding the workpiece and a cutting mechanism 44 for cutting the workpiece (workpiece (layered wafer) 2) held by the holding mechanism 38.

[0099] The holding mechanism 38 is a chuck table similar to the holding mechanism 14 provided in the grinding mechanism 20 shown in Figure 8, and has a disc-shaped table base 40 made of metal or the like, and a suction plate 42 attached to the table base 40, and is designed to hold the stacked wafer 2, which is the workpiece to be processed, by suction to the holding surface 42a.

[0100] A rotation mechanism (not shown) is connected to the lower part of the holding mechanism 38, which rotates the holding mechanism 38 around a rotation axis aligned vertically (a rotation axis extending perpendicular to the holding surface 42a).

[0101] The cutting mechanism 44 comprises a spindle housing 46 and a spindle 48, which is a rotating body housed in the spindle housing 46. The cylindrical spindle 24 is rotatably supported relative to the spindle housing 46 about an axis provided along the horizontal direction.

[0102] One end of the spindle 48 is exposed to the outside of the spindle housing 46, and a cutting blade 50 is mounted there via a blade mount. The cutting blade 50 is a disc-shaped member formed by embedding abrasive grains, such as diamond, in a binder such as resin.

[0103] A rotational drive source (not shown), such as a motor, is connected to the other end of the spindle 48, causing the spindle 48 to rotate together with the cutting blade 50.

[0104] The cutting device 36 is further equipped with a processing fluid supply unit (not shown). The processing fluid supply unit is, for example, a nozzle that supplies water as the processing fluid.

[0105] The discharge port of the processing liquid supply unit is provided, for example, near the cutting blade 50 and above the holding surface 42a of the holding mechanism 38, and is configured to supply water to the cutting blade 50 or the first wafer 4, respectively.

[0106] During cutting of the first wafer 4, for example, the cutting mechanism 44 moves so that the lower end of the cutting blade 50 is lower than the upper surface of the first wafer 4 relative to the frame unit including the first wafer 4 held by the holding mechanism 38. While the cutting blade 50 is rotating with the spindle 48, the holding mechanism 38 moves along the horizontal direction, bringing the cutting blade 50 and the first wafer 4 closer together.

[0107] When the cutting blade 50 contacts the first wafer 4, the cutting blade 50 cuts into the first wafer 4, thereby cutting the first wafer 4. Cutting marks are formed on the upper surface of the first wafer 4 along the direction of movement of the holding mechanism 38. As the above process is repeated, multiple cutting marks are formed on the first wafer 4.

[0108] During cutting, a processing liquid (cooling water) for cooling the cutting blade 50 is supplied to the cutting blade 50 from a processing liquid supply unit (not shown). For the first wafer 4 held in the holding mechanism 38, a processing liquid (cutting water) for cutting the first wafer 4 and removing cutting debris is supplied from a processing liquid supply unit (not shown).

[0109] Through the above process, grooves are formed on the first wafer 4 as cutting marks along the planned division lines (streets). By dividing the first wafer 4 along these grooves, individual chips are obtained, each containing a separate device.

[0110] In this way, the first wafer 4, which has been thinned and has a device formed on its surface, is divided and a chip is manufactured.

[0111] Furthermore, the methods that can be used to divide the first wafer 4 are not limited to the cutting blade method described above. For example, the first wafer 4 can be divided using various methods such as division by laser beam irradiation, division by dry etching, division by wet etching, division by plasma etching, division by water jet, division by performing thinning processes such as grinding or polishing on a wafer in which a division starting point or processing groove has been formed so as not to divide the wafer completely, and similarly, division along the division starting point by expanding a tape attached to a wafer in which a division starting point has been formed.

[0112] Furthermore, the content of processing step S40 described above is merely an example, and various other processes can be envisioned for the workpiece (layered wafer 2), in addition to grinding, polishing, and cutting, such as cleaning, imaging, inspection, peeling off protective material (adhesive tape), transport, and film formation.

[0113] However, at the start of processing step S40, there is a high possibility that the adhesive portion 8, which forms part of the laminated wafer 2, may not have completely hardened in the central region. Among the processing steps in S40, it is preferable to perform a process that has little impact even if the hardening of the central region of the adhesive portion 8 is incomplete.

[0114] Such processing methods include, in addition to the wafer thinning (grinding, polishing) described above, laser ablation, internal processing, annealing (which melts and flattens the irradiated surface of the wafer), plasma processing, and cutting with a cutting blade. In such processing, the entire surface of the adhesive portion that contacts the first wafer is covered by the first wafer and not exposed before and after processing.

[0115] For example, when ablation processing is performed, the first wafer may not be processed over its entire thickness, but only partially in the thickness direction (for example, a groove may be formed on the surface side of the wafer, but this groove may not penetrate to the back side of the wafer). In such cases, since the parts constituting the first wafer remain connected even after processing, it can be expected that problems such as misalignment, delamination, cracking, and chipping are less likely to occur in the processed first wafer, even if the adhesive strength of the bonded parts is not very high.

[0116] The structures, methods, etc., according to the embodiments described above are not limited to those embodiments. For example, with respect to the chip manufacturing method, in addition to the first curing light irradiation step, the bonding step, and the second curing light irradiation step, it is sufficient to include at least a step of dividing the chip, and any other steps may be included. Similarly, with respect to the thinned wafer manufacturing method, in addition to the first curing light irradiation step, the bonding step, and the second curing light irradiation step, it is sufficient to include at least a step of thinning the workpiece, and any other steps may be included. Furthermore, the contents of the above embodiments may be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of Symbols]

[0117] 2: Workpiece (Laminated wafer) 4: First component (first wafer), 6: Second component (first wafer), 8: Adhesive part 10:Light source device 12: Grinding equipment 14: Holding mechanism, 16: Table base, 18: Suction plate, 18a: Holding surface 20: Grinding mechanism, 22: Spindle housing, 24: Spindle 26: Grinding wheel, 28: Grinding wheel, 30: Processing fluid supply unit 32: Protective material (adhesive tape), 34: Frame 36: Cutting equipment 38: Holding mechanism, 40: Table base, 42: Suction plate, 42a: Holding surface 44: Cutting mechanism, 46: Spindle housing, 48: Spindle, 50: Cutting blade 52: Processing liquid supply unit, 54: Processing liquid supply unit

Claims

1. A processing method for forming a workpiece in which a first member and a second member are laminated and an adhesive portion containing a photocurable substance is provided between the first member and the second member, A first curing light irradiation step involves irradiating the material that will become the adhesive portion with curing light so that the material that will become the adhesive portion has adhesiveness and fluidity after irradiation, A bonding step in which the first member and the second member are joined together with the material that will become the adhesive portion, which has been irradiated with curing light in the first curing light irradiation step, sandwiched between them, Following the bonding step, a second curing light irradiation step is performed, in which curing light is irradiated onto the exposed portion of the bonded area. After the second curing light irradiation step, a processing step for processing the workpiece and A processing method comprising the following:

2. The processing method according to claim 1, wherein the first member is thinned in the processing step.

3. The photocurable substance contained in the adhesive portion has the property of being accelerated by heat, The processing step includes a first processing step for processing the workpiece and a second processing step for processing the workpiece after the first processing step. In the first processing step, the workpiece is processed under conditions that make it easier for the temperature of the bonded portion to rise compared to the second processing step. The processing method according to claim 1 or 2.

4. The workpiece is formed by the processing method described in claim 1, The first member is a plate-shaped article, In this processing step, the first member is divided to produce a chip. A method for manufacturing chips.

5. The workpiece is formed by the processing method described in claim 1, The first member is a plate-shaped article, In this processing step, the first member is thinned to produce a thinned wafer. A method for manufacturing thinned wafers.

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