Temporary fixing substrate and method for manufacturing temporary fixing substrate

Abstract

A temporary fixing substrate is peeled off from a fixed object after a predetermined fixed object is fixed on one main surface, and the temporary fixing substrate is provided with a thin region which is an annular region having a predetermined width from a side end portion, and has a first thin portion recessed from the one main surface on the one main surface side of the thin region, and a second thin portion recessed from the one main surface on the other main surface side of the thin region. The thickness of the thin region is smaller than the thickness of the region other than the thin region, and the difference between the thickness of the side end portion and the thickness of the region other than the thin region is 1 [mu] m to 5 [mu] m.

Description

Technical Field

[0001] The present invention relates to a temporary fixing substrate used in a manufacturing process of a semiconductor package. Background Art

[0002] FOWLP (Fan-out Wafer Level Package) technology is a well-known semiconductor package manufacturing technology. FOWLP technology generally utilizes four steps to produce thinner semiconductor packages than conventional ones: resin molding onto a temporary mounting substrate to which a semiconductor chip is temporarily fixed using an adhesive; grinding the resin mold to expose the electrode terminals of the semiconductor chip; forming a thin-film redistribution layer (multilayer wiring) and solder balls on the exposed electrode terminals; and singulating the individual packages and separating them from the temporary mounting substrate.

[0003] As a temporary substrate for fixing chips in the FOWLP technology, a method using a light-transmitting ceramic substrate is already known (for example, see Patent Documents 1 and 2).

[0004] In addition, a method of obtaining a joint body by warping a supporting substrate composed of glass or ceramics in advance and then bonding it to a silicon substrate using a thermosetting resin, and a method of obtaining a glass substrate with a thin film with less warping and then bonding it to the surface of another component are also known (for example, see Patent Documents 3 and 4).

[0005] In FOWLP technology, the temporary mounting substrate is peeled off by irradiating it with light from a laser light source, a lamp, or other light source. This method of peeling off the temporary mounting substrate using light irradiation from a laser light source is known as laser lift-off. Specifically, laser light or other light is irradiated from the temporary mounting substrate side onto the interface (the adhesive surface) between the temporary mounting substrate, the semiconductor chip, and the resin being fixed (the adhesive bonded to the substrate). This light irradiation is required to prevent any residue from the semiconductor package's resin, adhesive, or other materials from remaining on the temporary mounting substrate.

[0006] Furthermore, there is a need to remove a supporting substrate after producing a bonded structure or laminating substrates as disclosed in Patent Documents 3 and 4. The supporting substrate can also be considered a temporary fixing substrate. When light irradiation is used to remove such a supporting substrate, it is undesirable that the adhesive resin or the like remains on the supporting substrate.

[0007] The inventors of the present invention have conducted intensive studies and have found that the better the transmittance of light such as laser light at the outer periphery, the higher the reliability of the peeling of the temporarily fixed substrate.

[0008] Prior art literature Patent Literature Patent Document 1: Japanese Patent No. 6430081 Patent Document 2: Japanese Patent No. 6420023 Patent Document 3: Japanese Patent Application Laid-Open No. 2011-23438 Patent Document 4: Japanese Patent Application Laid-Open No. 2010-58989 Summary of the Invention

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to realize a temporary fixing substrate in which resin or the like is unlikely to remain when being peeled off by light irradiation.

[0010] In order to solve the above-mentioned problems, the first method of the present invention is a temporarily fixed substrate, characterized in that the temporarily fixed substrate is peeled off from the fixed object after being temporarily fixed to a given fixed object on one main surface, and the temporarily fixed substrate has a thin area, which is an annular area of ​​a given width starting from the side end, and has a first thin portion that is recessed than the one main surface on the one main surface side of the thin area, the thickness at the thin area is less than the thickness of the area other than the thin area, and the difference between the thickness at the side end and the thickness of the area other than the thin area is 1μm to 5μm.

[0011] The second embodiment of the present invention is based on the temporary fixed substrate involved in the first embodiment, and is characterized in that it also has a second thin portion on the other main surface side of the thin area that is recessed than the other main surface, and the total amount of the recess of the first thin portion at least at the side end from the one main surface, that is, the front recess amount, and the total amount of the recess of the second thin portion at least at the side end from the other main surface, that is, the back recess amount, is 1μm to 5μm.

[0012] A third aspect of the present invention is the temporary fixing substrate according to the second aspect, wherein the first thin portion and the second thin portion are tapered.

[0013] A fourth aspect of the present invention is the temporary fixing substrate according to the second aspect, wherein the first thin portion and the second thin portion are stepped.

[0014] A fifth aspect of the present invention is the temporary fixing substrate according to any one of the first to fourth aspects, wherein the temporary fixing substrate is disk-shaped, and the given width of the thin region is greater than or equal to 0.5% and less than or equal to 3% of the radius of the temporary fixing substrate.

[0015] A sixth aspect of the present invention is a method for manufacturing a temporary fixing substrate, characterized in that the temporary fixing substrate is peeled off from the fixing object after a given fixing object is temporarily fixed to one main surface of the temporary fixing substrate, and the method for manufacturing a temporary fixing substrate obtains the temporary fixing substrate by performing the following steps: a forming step of casting a raw material slurry containing powder of translucent ceramic using a mold and solidifying it to produce a formed body mainly composed of the translucent ceramic and having a shape corresponding to the temporary fixing substrate; a firing step of firing the formed body to obtain a sintered body; a chamfering step of chamfering the corners of the sintered body; and a grinding step of grinding the chamfered sintered body, wherein the temporary fixing substrate has a thin region, the thin region being an annular region of a given width starting from a side end portion, and having a first thin portion that is recessed relative to the one main surface on the side of the one main surface of the thin region, the thickness of the thin region being smaller than the thickness of the region other than the thin region, and the difference between the thickness of the side end portion and the thickness of the region other than the thin region is 1 μm to 5 μm.

[0016] The seventh embodiment of the present invention is a method for manufacturing a temporary fixed substrate, characterized in that the temporary fixed substrate is peeled off from the fixed object after being fixed to a given fixed object on one main surface. The method for manufacturing a temporary fixed substrate obtains the temporary fixed substrate by performing the following steps: a forming step, after producing a formed body mainly composed of translucent ceramics, deforming the formed body into a shape corresponding to the temporary fixed substrate; a firing step, firing the formed body to obtain a sintered body; a chamfering step, chamfering the corners of the sintered body; and a grinding step, grinding the chamfered sintered body, the temporary fixed substrate has a thin area, the thin area is an annular area of ​​a given width starting from the side end, and has a first thin portion that is recessed than the one main surface on the side of the one main surface of the thin area, the thickness at the thin area is less than the thickness of the area other than the thin area, and the difference between the thickness at the side end and the thickness of the area other than the thin area is 1μm to 5μm.

[0017] The eighth embodiment of the present invention is based on the manufacturing method of the temporary fixed substrate involved in the seventh embodiment, and is characterized in that the forming process includes: a casting process, using a mold to cast a raw material slurry containing the powder of the translucent ceramic and solidifying it to obtain the formed body; and a deformation process, by pressing the formed body obtained by the casting process to deform it.

[0018] The ninth aspect of the present invention is based on the manufacturing method of the temporary fixed substrate involved in the seventh aspect, and is characterized in that the forming process includes: a tape casting forming process, forming the raw material slurry containing the powder of the translucent ceramic into a plurality of tapes; a stacking process, obtaining a stacked body by stacking and integrating the plurality of tapes; a punching process, punching the stacked body to obtain the formed body; and a deformation process, deforming the formed body obtained by the punching process by pressing it.

[0019] According to the first to ninth embodiments of the present invention, in a temporary fixing substrate for temporarily fixing a fixed object such as a semiconductor chip, by providing a thin area at least on the entire periphery of the mounting surface of the fixed object, the temporary fixing substrate can be properly peeled off from the semiconductor chip using a light source and the resin molded part. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a plan view of one main surface (front surface) 1 a of the temporary fixing substrate 1 .

[0021] Figure 2 It is a partial cross-sectional view of the vicinity of the side end portion 1 e of various temporary fixing substrates 1 .

[0022] Figure 3 These are schematic cross-sectional views showing in stages the state of a semiconductor package manufacturing process using the temporary fixing substrate 1 based on the FOWLP technique.

[0023] Figure 4 These are schematic cross-sectional views showing in stages the state of a semiconductor package manufacturing process using the temporary fixing substrate 1 based on the FOWLP technique.

[0024] Figure 5 1 is a flowchart schematically showing a manufacturing process of the temporary fixed substrate 1 .

[0025] Figure 6 This is a diagram schematically showing how a molded body 1α is produced by a die casting method.

[0026] Figure 7 This figure shows a case where a molded body 1β produced by tape casting is used to produce a temporary fixing substrate 1 having a stepped front-side thin portion 2a.

[0027] Figure 8 It is a diagram illustrating an example of a measurement location of the front surface depression amount Δta. DETAILED DESCRIPTION

[0028] Temporarily fixing the base plate Figure 1This figure shows a top view of one principal surface (front surface) 1a of a temporary mounting substrate 1, one embodiment of a support substrate according to the present invention. Temporary mounting substrate 1 is used, for example, to temporarily mount semiconductor chips when manufacturing a semiconductor package using FOWLP (Fan-out Wafer Level Package) technology.

[0029] The temporary fixing substrate 1 is a disc-shaped, translucent ceramic substrate with a diameter of several hundred millimeters (e.g., 300 mm), a thickness of several hundred μm to several millimeters (e.g., 1 mm), an in-plane thickness difference of within a few μm (e.g., within 3 μm), and a warpage of several hundred μm or less (e.g., 200 μm). It should be noted that in this embodiment, the translucent ceramic refers to a ceramic having a total front light transmittance of 20% or greater across the entire wavelength range of 200 nm to 1500 nm. Examples of such translucent ceramics include aluminum oxide, silicon nitride, aluminum nitride, and silicon oxide. For example, a substrate primarily composed of aluminum oxide and having a total front light transmittance of 70% or greater at a wavelength of 1500 nm is a preferred example of the temporary fixing substrate 1. When alumina is the main component, it is preferred to use high-purity alumina powder of 99.9% or more (more preferably 99.95% or more) as the raw material, and it is preferred to add magnesium oxide, zirconium oxide (ZrO2) as a sintering aid, and yttrium oxide (Y2O3) to the alumina powder.

[0030] The front surface 1a, which serves as the placement surface for the semiconductor chip, and the other main surface (back surface) 1b are pre-polished together to form flat, low-roughness polished surfaces. More specifically, the front surface 1a and back surface 1b achieve an in-plane thickness difference of less than a few μm and an arithmetic average roughness Ra of 100 nm or less (preferably 20 nm or less). More specifically, both the front surface 1a and back surface 1b are polished surfaces. It should be noted that there is no particular lower limit for the arithmetic average roughness Ra of the front surface 1a and back surface 1b; a value of 1 nm is sufficient for practical purposes.

[0031] However, in the temporary fixing substrate 1 according to this embodiment, a thin portion 2 (2a) is formed over the entire periphery of the front surface 1a, in an annular region having a given width a from the side end 1e, and is recessed relative to the rest of the region (in other words, having a lower height in the substrate thickness direction). Furthermore, although not shown in the figure, a thin portion 2 (2b) may also be provided over the entire periphery of the back surface 1b.

[0032] Hereinafter, the annular region with a width a extending from the side end 1e, formed by the thin portion 2, is referred to as the thin region RE. Specifically, the aforementioned thickness of the temporary fixing substrate 1, which ranges from several hundred μm to several millimeters, refers to the distance between the front surface 1a and the back surface 1b of the area excluding the thin region RE. However, as will be described later, the difference in thickness between the thin region RE and other portions is minimal. Therefore, in reality, it can be said that the temporary fixing substrate 1, including the thin region RE, has a thickness ranging from several hundred μm to several millimeters. Furthermore, the aforementioned arithmetic mean roughness Ra of 100 nm or less for the front surface 1a and back surface 1b is achieved at least for the front surface 1a and back surface 1b excluding the thin region RE.

[0033] The thin portion 2 is provided to appropriately perform peeling by irradiation with light from a light source as one of the steps in the process of manufacturing a semiconductor package when the temporary fixing substrate 1 is used, which will be described in detail later.

[0034] Figure 2 The diagram is a partial cross-sectional view of the vicinity of the side end portion 1e of various temporary fixing substrates 1 for illustrating a specific formation method of the thin portion 2. In each temporary fixing substrate 1, the thin portion 2 is formed in a thin region RE having a predetermined width a.

[0035] Figure 2 (a) is a diagram illustrating a temporary fixing substrate 1 including a tapered front-side thin portion 2a on the outer periphery of a front surface 1a.

[0036] Figure 2 (b) is a diagram illustrating a temporary fixing substrate 1 including a tapered front-side thin portion 2a and a tapered back-side thin portion 2b on the outer periphery of each of the front surface 1a and the back surface 1b.

[0037] Figure 2 (c) is a diagram illustrating a temporary fixing substrate 1 having a stepped front-side thin portion 2a on the outer periphery of the front surface 1a.

[0038] Figure 2 (d) is a diagram illustrating a temporary fixing substrate 1 including a front-side thin portion 2a and a back-side thin portion 2b having stepped shapes on the outer peripheries of the front surface 1a and the back surface 1b.

[0039] If the difference between the thickness of the temporary fixing substrate 1 excluding the thin region RE and the thickness of the temporary fixing substrate 1 at the side end 1e is defined as the total concavity Δt, the thickness direction distance between the front surface 1a and the side end 1e at the front thin portion 2a is defined as the front concavity Δta, and the thickness direction distance between the back surface 1b and the side end 1e at the back thin portion 2b is defined as the back concavity Δtb, then in the case Figure 2 (a) and Figure 2When only the front thin portion 2a is provided as shown in (c), Δt=Δta. Figure 2 (b) and Figure 2 When only the front-side thin portion 2 a is provided as shown in (d), Δt=Δta+Δtb.

[0040] The total concavity Δt corresponds to the maximum value of the thickness difference between the thin region RE and the rest of the region. If the front thin portion 2a and the back thin portion 2b are stepped, the front concavity Δta and the back concavity Δtb correspond to the step distances.

[0041] Should be noted that the formation mode of thin portion 2 is not limited to taper or step-like, and also can be formed into upward convex or downward convex curved surface shape when sectioning.In addition, the shape of front side thin portion 2a and back side thin portion 2b also can be different.

[0042] Semiconductor Package Manufacturing Process and the Effects of Thin-Part Formation In the above-described embodiment, the thin portion 2 of the temporary fixing substrate 1 is intended to ensure the manufacturing yield of the semiconductor package by appropriately performing the peeling of the temporary fixing substrate 1 by light irradiation as a step in the semiconductor package manufacturing process. This point will be explained below.

[0043] Figure 3 and Figure 4 This is a schematic cross-sectional view showing the state of the manufacturing process of a semiconductor package using the temporary fixing substrate 1 in stages based on the FOWLP technology. Figure 3 and Figure 4 In the figure, for simplicity of illustration and description, only the thin portion 2 on the front surface 1a side is shown with oblique lines.

[0044] In the manufacturing process of semiconductor package, first, Figure 3 As shown in (a), a layer (adhesive layer) 3α containing an adhesive is formed on the temporary fixing substrate 1. Examples of the adhesive include double-sided tape and hot melt adhesives, and various known methods such as roller coating, spray coating, screen printing, and spin coating can be applied to form the adhesive. In detail, the temporary fixing substrate 1 has a slightly convex warped shape toward the front surface 1a, but Figure 3 In the figure, the warping is ignored for the sake of illustration.

[0045] Then, if Figure 3 As shown in (b), a plurality (a large number) of semiconductor chips 4 are arranged on the adhesive layer 3α. Figure 3Although not shown in (b), semiconductor chip 4 is also positioned on thin region RE. Next, adhesive layer 3α is cured to form adhesive layer 3. This curing method can be selected from heating, ultraviolet irradiation, and other methods depending on the material of the adhesive used in adhesive layer 3α. This allows semiconductor chip 4 to be bonded and fixed to temporary mounting substrate 1.

[0046] When the semiconductor chip 4 is fixed to the temporary fixing substrate 1 in this manner, the mold resin flows over the entire upper surface of the temporary fixing substrate 1, that is, the gaps 5 between the semiconductor chips 4 and the entire upper surface of the semiconductor chips 4. By curing the mold resin, Figure 3 As shown in (c), a resin mold 6 is formed. Examples of the mold resin include epoxy resins, polyimide resins, polyurethane resins, and urethane resins.

[0047] Next, the resin mold 6 is ground until the electrode terminals of the semiconductor chip 4 are exposed. The resin mold 6 can be ground using a grinder, for example. Figure 4 (a) shows the situation after grinding. Figure 4 Although not shown in the figure, device components such as a redistribution layer and solder balls are formed on each semiconductor chip 4 exposed by grinding.

[0048] Next, dicing lines CL are formed on the resin mold 6 for singulating the resin mold 6 into a plurality of semiconductor packages 7 each including a semiconductor chip 4. The dicing lines CL are formed by, for example, dicing or the like.

[0049] Finally, the temporary fixed substrate 1 is peeled off (separated) by light irradiation. Figure 4 As shown in (b), light LB is irradiated onto the adhesive layer 3 from the temporary fixing substrate 1 side, for example, using a laser light source or lamp. Examples of light LB include UV light in the wavelength range of 200 nm to 400 nm and IR light in the wavelength range of 900 nm to 1200 nm. Examples of light sources for irradiating these lights include UV lamps, UV lasers, and IR lasers.

[0050] The light LB passes through the temporary fixing substrate 1 which is a light-transmitting ceramic substrate and is absorbed by the adhesive layer 3. As a result, the adhesive layer 3 is ablated (melted, evaporated), and the Figure 4 As shown in (c), the temporary fixing substrate 1 is peeled off from the semiconductor chip 4 and the resin mold 6. Furthermore, the individual semiconductor packages 7 are separated at the dicing lines CL.

[0051] In the present embodiment, by using the temporary fixing substrate 1 having the thin portion 2 provided on the outer periphery, the temporary fixing substrate 1 can be peeled off more satisfactorily and reliably by the light irradiation.

[0052] When irradiating a translucent object with light LB, the thinner the area, the greater the light LB's transparency. Therefore, in the temporary fixing substrate 1 according to this embodiment, the thinner regions RE provided at the periphery transmit light LB more effectively than other areas (e.g., the central portion). Consequently, in the temporary fixing substrate 1 irradiated with light LB, peeling occurs preferentially in the peripheral portion, with peeling proceeding from this peripheral portion. Ultimately, this achieves excellent and reliable peeling without any resin adhesion (residue). This can be achieved regardless of the light source type, whether a lamp or a laser, by irradiating light LB within the aforementioned wavelength range.

[0053] It should be noted that a larger total recess Δt increases the transmittance of light LB. However, if a semiconductor chip 4 is placed in a thin region RE with excessive front recess Δta, the surface of the semiconductor chip 4 placed in the thin region RE may not be exposed during grinding of the resin mold 6 before light exposure. If the surface of the semiconductor chip 4 is not exposed, it may cause a disconnection between the semiconductor chip 4 and the redistribution layer during formation, which is undesirable. On the other hand, if the front recess Δta is less than 1 μm, the effect of providing the front-side thin portion 2a is not achieved. Considering these considerations, the front recess Δta is set to 1 μm to 5 μm.

[0054] It should be noted that when setting the back side thin portion 2b, there is no need to consider the interference mentioned above, but in practice, it is sufficient to determine the front side depression Δta to be greater than 1μm and the total depression Δt to be approximately 1μm to 5μm.

[0055] In other words, in the temporary fixing substrate 1 according to the present embodiment, the thickness at the side end portion 1 e is 1 μm to 5 μm smaller than the thickness of the region excluding the thin region RE.

[0056] On the other hand, the larger the width a of the thin region RE, the wider the range of excellent transmittance of light LB. However, from the perspective of ensuring peelability, a maximum width a of 3% of the radius r of the temporary fixing substrate 1 is sufficient. In addition, when the width a exceeds 3% of the radius r, the number of semiconductor chips 4 arranged in the thin region RE increases, and the possibility of grinding defects also increases. On the other hand, when the width a is less than 0.5% of the radius r, the effect of suppressing peeling defects brought about by providing the thin region RE including the front-side thin portion 2a cannot be achieved. Taking the above into consideration, the width a of the thin region RE is 0.5% to 3% of the radius r of the temporary fixing substrate 1.

[0057] Temporary fixed substrate manufacturing process Next, a process for manufacturing the temporary fixed substrate 1 including the thin portion 2 will be described. Figure 5 This is a flow chart schematically showing the manufacturing process of the temporary fixing substrate 1. The temporary fixing substrate 1 is manufactured generally through a compact manufacturing step (step S1), a firing step (step S2), a chamfering step (step S3), and a polishing step (step S4).

[0058] When manufacturing the temporary fixing substrate 1 , first, a compact mainly composed of translucent ceramic powder is produced (step S1 ). Examples of methods for producing the compact include die casting and tape casting.

[0059] Figure 6 1α is a diagram schematically showing a molded body 1α produced by die casting. Figure 6 In the embodiment, the steps for producing the molded body 1α are illustrated. The molded body 1α is used to obtain Figure 2 A temporary fixing substrate 1 including a tapered front-side thin portion 2 a as shown in FIG. 1 ( a ).

[0060] First, prepare Figure 6 The mold 50 shown in (a) is composed of an upper mold 50a and a lower mold 50b. In the mold 50, the upper mold 50a and the lower mold 50b are integrated to form a disk-shaped internal space 50s corresponding to the molded body 1α to be produced. However, a tapered portion 50t is provided on the upper outer peripheral portion of the inner surface of the upper mold 50a, which forms the internal space 50s, corresponding to the front thin portion 2a.

[0061] Then, the slurry S, which is a raw material for temporarily fixing the substrate 1 , is injected into the internal space 50 s from the injection port 50 c provided in the upper mold 50 a , thereby performing pouring of the slurry S.

[0062] The slurry S is prepared by kneading the above-mentioned alumina and other translucent ceramic raw material powders, magnesium oxide, ceramic powders such as sintering aids, dispersion media, gelling agents, dispersants, and organic materials such as catalysts using a ball mill or the like.

[0063] like Figure 6 As shown in (b), the slurry S injected into the internal space for 50s is solidified by being placed for a given time according to a given temperature curve. Figure 6 As shown in (c), the mold is released from the upper mold 50a and the lower mold 50b. Finally, a molded body 1α having a tapered thin portion 2α on the outer peripheral portion of the upper surface is obtained.

[0064] In addition, when providing the front-side thin portion 2a with a step shape, or when providing the back-side thin portion 2b in addition to the front-side thin portion 2a, a mold 50 corresponding thereto is used.

[0065] on the other hand, Figure 7 It means in Figure 2 (c) shows a case where a molded body 1β produced by tape casting is used to produce a temporary fixing substrate 1 having a stepped front-side thin portion 2a, such as the temporary fixing substrate 1 shown in FIG.

[0066] When forming the molded article 1β by tape casting, the slurry prepared as described above is first formed into a tape. Multiple rectangular sheets of a predetermined size are sheared (cut) from the resulting tape and stacked and pressed. The pressed stack is then demolded into a circular shape. This produces a disk-shaped molded article 1β.

[0067] Then, if Figure 7 As shown in (a), the outer peripheral portion of the disk-shaped molded body 1β is pressed (deformed) by a pressing die 60 having a pressing portion 60a corresponding to the outer peripheral portion, thereby Figure 7 As shown in (b), a stepped thin portion 2β is formed in the molded body 1β.

[0068] In addition, when the tapered front-side thin portion 2a is provided, or when the back-side thin portion 2b is provided in addition to the front-side thin portion 2a, a corresponding pressing die 60 is used.

[0069] In either case, during the compact production process, the dimensions and shape of the compact, including the shapes of the thin portions 2α and 2β, are determined in consideration of the firing shrinkage during the firing process. In other words, the dimensions and shape of the compact are determined to ultimately achieve the desired shape of the temporary fixed substrate 1.

[0070] Alternatively, the front thin portion 2a and the back thin portion 2b may be provided by pressing (deforming) the molded body 1α produced by die casting without the front thin portion 2a and the back thin portion 2b using the pressing die 60 .

[0071] Alternatively, a method of obtaining a molded body by a doctor blade method, an extrusion method, or the like is also possible.

[0072] Next, the produced compact is fired (step S2). During the firing process, organic components are removed, resulting in a ceramic sintered body (the temporary fixed substrate 1 before chamfering and polishing). It should be noted that the firing is preferably performed by pre-firing in an atmospheric furnace followed by main firing in a hydrogen furnace. From the perspective of achieving densification of the sintered body, the sintering temperature during the main firing is preferably 1700°C to 1900°C, and more preferably 1750°C to 1850°C.

[0073] After the main firing, the resulting sintered body can be further annealed in a hydrogen furnace to adjust (correct) warpage. To prevent deformation and abnormal grain growth and promote the release of sintering aids, annealing is preferably performed within ±100°C of the maximum main firing temperature, more preferably below 1900°C. The annealing time is preferably 1 to 6 hours.

[0074] Once the sintered body (temporary fixing substrate 1 before chamfering and polishing) is obtained, the edges (corners) of the sintered body are then chamfered (step S3). Chamfering is performed to prevent chipping at the corners of the temporary fixing substrate 1.

[0075] Finally, the front and back surfaces (both main surfaces) of the chamfered temporary fixed substrate 1 are polished (step S4). As a polishing method, buffing using diamond slurry can be exemplified.

[0076] Through the above steps, the temporary fixing substrate 1 including the front-side thin portion 2 a and further including the back-side thin portion 2 b in the thin region RE is obtained.

[0077] As described above, according to this embodiment, by providing a thin area with a given width at least from the side end portion of the semiconductor chip in a temporary fixing substrate used for temporarily fixing a semiconductor chip in a manufacturing process of a semiconductor package based on FOWLP technology, the temporary fixing substrate can be properly peeled off from the semiconductor chip and the resin molded part by irradiation with light from a light source.

[0078] Modifications While the aforementioned embodiment focuses on a temporary mounting substrate having a thin portion used as a substrate for temporarily mounting multiple semiconductor chips during the fabrication of a semiconductor package using FOWLP technology, the temporary mounting substrate is not limited to this application and may also be used to temporarily mount electronic components other than semiconductor chips. Specifically, the temporary mounting substrate described in the aforementioned embodiment may be used to remove the temporary mounting substrate by laser lift-off, as appropriate, when multiple electronic components are bonded to the temporary mounting substrate with an adhesive to form a resin mold.

[0079] Alternatively, when laser stripping is used to remove a support substrate from a bonded structure formed by bonding various substrates to a given support substrate using an adhesive, a thin region may be provided in advance on the outer periphery of the support substrate. Examples of substrates bonded to the support substrate include silicon substrates, compound semiconductor substrates, epitaxial substrates and other composite substrates, multilayer substrates, and multi-layer substrates. In this case, the same effects as those of the above-described embodiment can be achieved.

[0080] Example Six types of temporary mounting substrates 1 (Examples 1 to 6) with varying shapes in the thin region RE and total recess amounts Δt ranging from 1 μm to 5 μm were produced, 200 each. Using each of the resulting temporary mounting substrates 1, the steps up to light irradiation were sequentially performed according to the aforementioned semiconductor package fabrication process. Laser lift-off using UV laser (wavelength: 200 nm to 400 nm) was employed as the light irradiation method. The results were used to evaluate the grindability of the resin mold 6 and the removability of the temporary mounting substrates 1 by laser lift-off.

[0081] In addition, as Comparative Example 1, a temporary fixed substrate 1 was prepared in which the total depression amount Δt exceeded 5 μm. As Comparative Example 2, a temporary fixed substrate 1 was prepared in which the front side thin portion 2a and the back side thin portion 2b were not provided and which did not have a thin area RE (i.e., the total depression amount Δt was 0). The grindability of the resin mold 6 and the peelability of the temporary fixed substrate 1 by laser peeling were evaluated in the same manner as in Examples 1 to 6.

[0082] Specifically, 200 test samples were prepared for each of Examples 1 to 6 and Comparative Examples 1 and 2, and the grindability of the resin mold 6 and the peelability of the temporary fixed substrate 1 by laser lift-off were evaluated based on these test samples.

[0083] As a material for the temporary fixing substrate 1, a material having a specific surface area of ​​3.5 to 4.5 m 2 / g and an average primary particle size of 0.35 to 0.45 μm as the translucent ceramic raw material powder, and magnesium oxide powder and zirconium oxide powder and yttrium oxide powder as sintering aids as other ceramic powders.

[0084] In addition, dimethyl glutarate and ethylene glycol were used as dispersion media, MDI resin was used as a gelling agent, a high molecular weight surfactant was used as a dispersant, and N,N-dimethylaminohexanol was used as a catalyst.

[0085] These raw materials were mixed at the following weight ratio to obtain a slurry for forming a molding machine.

[0086] α-alumina powder: 100 parts by weight; Magnesium oxide: 0.025 parts by weight; Zirconium oxide: 0.040 parts by weight; Yttrium oxide: 0.0015 parts by weight; Dimethyl glutarate: 27 parts by weight; Ethylene glycol: 0.3 parts by weight; MDI resin: 4 parts by weight; Polymer surfactant: 3 parts by weight; N,N-dimethylaminohexanol: 0.1 parts by weight.

[0087] The prepared slurry was used to produce molded bodies for obtaining temporary fixing substrates 1 in Examples 1 to 6 and Comparative Examples 1 and 2 by die casting. An aluminum alloy mold was used as the mold 50. The resulting temporary fixing substrates 1 all had a diameter of 300 mm and a thickness of 1.00 mm. Except for Comparative Example 2, the width a of the thin region was set to 4.5 mm, and the shapes of the thin regions RE were varied.

[0088] In Example 1, Example 2, Example 5 and Comparative Example 1, in order to obtain Figure 2 A molded article was produced by temporarily fixing the substrate 1 having only the tapered front thin portion 2a shown in (a). In Examples 1, 2, and 5, the front concavity Δta, also referred to as the total concavity Δt, was set to 5 μm or less. In Comparative Example 1, this front concavity Δta was set to exceed 10 μm.

[0089] In Example 3, in order to obtain Figure 2 A compact was produced by temporarily fixing the substrate 1 having only the stepped front thin portion 2a shown in (c). At this time, the front concavity Δta, also referred to as the total concavity Δt, was set to 5 μm or less.

[0090] In Example 4, in order to obtain Figure 2 A molded body was produced by temporarily fixing the substrate 1 having the stepped front thin portion 2a and the back thin portion 2b shown in (d). At this time, the total recess amount Δt was set to 5 μm or less.

[0091] In Example 6, in order to obtain Figure 2 A molded body was produced by temporarily fixing the substrate 1 having the tapered front thin portion 2a and the back thin portion 2b shown in (b). At this time, the total recess amount Δt was set to 5 μm or less.

[0092] In Comparative Example 2, a molded body was produced without forming the front-side thin portion 2 a and the back-side thin portion 2 b.

[0093] In either case, when producing a molded body, the slurry is poured into the interior space of mold 50 at room temperature for 50 seconds, then left at room temperature for 1 hour, and then at 40°C for 30 minutes. The slurry, which has solidified to a certain degree, is then removed from mold 50 and then left at room temperature and 90°C for 2 hours each. Through the above treatment, a molded body is obtained.

[0094] Each of the obtained compacts was pre-fired (pre-calcined) at 1100° C. in air and then fired at 1750° C. in an atmosphere of 3:1 hydrogen:nitrogen. Subsequently, annealing was performed under the same atmosphere and temperature conditions to obtain a fired body.

[0095] The sintered body was polished using a diamond slurry having a diamond particle size of 6 μm, and then cleaned, thereby obtaining temporary fixed substrates 1 of Examples 1 to 6 and Comparative Examples 1 and 2.

[0096] For Examples 1 to 6 and Comparative Examples 1 and 2, a single temporary mounting substrate 1 was used as the test subject. A laser displacement meter using a spectroscopic interferometry method using an infrared SLD light source with a central wavelength of 820 nm was used to measure the front surface concavity Δta and the back surface concavity Δtb. The total concavity Δt was then calculated. Specifically, the front and back surfaces of the temporary mounting substrate 1 were illuminated with laser light to measure their shape. The results were then compared with a reference gauge block to determine the front surface concavity Δta and back surface concavity Δtb.

[0097] Figure 8 This is a diagram illustrating the measurement location of the front side depression amount Δta. When measuring the front side depression amount Δta, first, the temporary fixed substrate 1 is placed horizontally in such a manner that the front side 1a becomes the upper surface. In this state, the laser displacement meter is used to measure the difference in the height position of each of the four measurement points A, B, C, and D separated at equal angular intervals in the circumferential direction of the annular outer peripheral end of the temporary fixed substrate 1, i.e., the front side thin portion 2a included in the thin region RE, relative to the height position outside the thin region RE. Then, the average value of the difference about the four measurement points A, B, C, and D is set as the front side depression amount Δta. It should be noted that when the front side thin portion 2a is conical, the four measurement points A, B, C, and D are set as the radial end positions of the front side thin portion 2a.

[0098] When only the front-side thin portion 2 a is provided in the thin region RE, the front-side recess amount Δta is directly used as the total recess amount Δt.

[0099] On the other hand, when forming the back side thin portion 2b in addition to the front side thin portion 2a, the back side thin portion 2b is also formed. Figure 8 In the embodiment shown, the back surface recess amount Δtb is calculated based on the measurement by the laser displacement meter, and the sum of the front surface recess amount Δta and the back surface recess amount Δtb is taken as the total recess amount Δt.

[0100] Then, follow Figure 3 as well as Figure 4In the illustrated process, each of the obtained temporarily fixed substrates 1 undergoes temporary fixing of the semiconductor chips 4 by the resin mold 6, grinding of the resin mold 6, formation of dicing lines CL, and laser lift-off.

[0101] The grindability of the resin mold 6 was evaluated based on the defect rate (defective rate) during grinding of the resin mold 6 in all 200 test samples for Examples 1 to 6 and Comparative Examples 1 and 2. In this evaluation, if the semiconductor chips 4 arranged in the thin region RE were not exposed despite grinding to a predetermined amount that should expose all the semiconductor chips 4, a defect was determined to have occurred.

[0102] The releasability of the temporary fixing substrate 1 was also evaluated based on the defect rate (defective rate) when the temporary fixing substrate was peeled off by laser lift-off. In this evaluation, if resin components from the resin mold 6 or the adhesive layer 3 adhered to the temporary fixing substrate 1 after peeling, it was determined to be a defect.

[0103] Table 1 summarizes the total amount of depression Δt (“total depression amount” in Table 1), the evaluation results of the releasability of the temporary fixing substrate, and the evaluation results of the grindability of the resin mold for Examples 1 to 6 and Comparative Examples 1 and 2.

[0104] [Table 1]

[0105] In the evaluation of the grindability of the resin mold 6 and the releasability of the temporary fixing substrate 1, a defect rate of less than 3% indicates that the occurrence of defects has been appropriately suppressed, indicating that the grindability or releasability is good. In Table 1, results meeting this evaluation are marked with "O" (circled).

[0106] If the defect rate is 3% or more and less than 5%, it is evaluated that the occurrence of defects is suppressed to some extent, but not sufficiently. In Table 1, the results that meet this evaluation are marked with "△" (triangle mark).

[0107] On the other hand, when the defect rate was 5% or more, it was evaluated that the occurrence of defects was not suppressed. In Table 1, the results that met this evaluation are marked with "×" (cross mark).

[0108] As apparent from Table 1, in Examples 1 to 6 in which the total dishing amount Δt was 1 μm or more and 5 μm or less, both the releasability and the grindability were evaluated as good.

[0109] In contrast, in Comparative Example 1 in which the total recess amount Δt was as large as 10.4 μm, although the releasability was good, a large number of defects occurred during the grinding of the resin mold 6 .

[0110] In Comparative Example 2 having no thin region RE (total recess amount Δt is 0), although the grindability was good, more peeling failures occurred than in Examples 1 to 6, indicating insufficient peeling properties.

[0111] The above results show that, in order to ensure the grindability of the resin mold and suppress peeling failure during laser lift-off, it is preferable to provide the thin region RE on the outer periphery of the temporary fixed substrate 1 so that the total recess amount Δt is 1 μm or more and 5 μm or less.

Claims

1. A temporary fixed substrate, characterized in that: After the temporary fixing substrate temporarily fixes a predetermined fixing object on one main surface, it is peeled off from the fixing object. The temporary fixing substrate includes a thin region, which is an annular region with a predetermined width extending from a side end. The thin region has a first thin portion on the one main surface side thereof that is recessed relative to the one main surface. The thickness at the thin region is smaller than the thickness of the region other than the thin region, A difference between the thickness at the side end portion and the thickness of a region other than the thin region is 1 μm to 5 μm.

2. The temporary fixing substrate according to claim 1, characterized in that The thin region further has a second thin portion on the other main surface side thereof, which is recessed relative to the other main surface. The depression amount of the first thin portion at least at the side end from the one main surface is the front depression amount, and the depression amount of the second thin portion at least at the side end from the other main surface is the back depression amount, and the total of the front depression amount and the back depression amount is 1μm to 5μm.

3. The temporary fixing substrate according to claim 2, characterized in that: The first thin portion and the second thin portion are tapered.

4. The temporary fixing substrate according to claim 2, wherein: The first thin portion and the second thin portion are in a step shape.

5. The temporary fixing substrate according to any one of claims 1 to 4, characterized in that: The temporary fixing substrate is in the shape of a circular plate. The given width of the thin region is not less than 0.5% and not more than 3% of a radius of the temporary fixing substrate.

6. A method for manufacturing a temporary fixed substrate, characterized in that: The manufacturing method of the temporary fixing substrate is used to manufacture a temporary fixing substrate. After temporarily fixing a given fixing object on one main surface, the temporary fixing substrate is peeled off from the fixing object. The manufacturing method of the temporary fixing substrate obtains the temporary fixing substrate by performing the following steps: a molding step of producing a molded body having a shape corresponding to the temporary fixing substrate and mainly comprising the translucent ceramic and having a shape corresponding to the temporary fixing substrate by casting a raw material slurry containing translucent ceramic powder using a mold and solidifying the slurry; a firing step of firing the formed body to obtain a sintered body; a chamfering step of chamfering the corners of the sintered body; as well as a grinding step of grinding the sintered body having the chamfered edges, The temporary fixing substrate includes a thin region, which is an annular region with a predetermined width extending from a side end. The thin region has a first thin portion on the one main surface side thereof that is recessed relative to the one main surface. The thickness at the thin region is smaller than the thickness of the region other than the thin region, A difference between the thickness at the side end portion and the thickness of a region other than the thin region is 1 μm to 5 μm.

7. A method for manufacturing a temporary fixed substrate, characterized in that: The manufacturing method of the temporary fixing substrate is used to manufacture a temporary fixing substrate. After temporarily fixing a given fixing object on one main surface, the temporary fixing substrate is peeled off from the fixing object. The manufacturing method of the temporary fixing substrate obtains the temporary fixing substrate by performing the following steps: a forming step of forming a formed body mainly composed of translucent ceramic and deforming the formed body into a shape corresponding to the temporary fixing substrate; a firing step of firing the formed body to obtain a sintered body; a chamfering step of chamfering the corners of the sintered body; as well as a grinding step of grinding the sintered body having the chamfered edges, The temporary fixing substrate includes a thin region, which is an annular region with a predetermined width extending from a side end. The thin region has a first thin portion on the one main surface side thereof that is recessed relative to the one main surface. The thickness at the thin region is smaller than the thickness of the region other than the thin region, A difference between the thickness at the side end portion and the thickness of a region other than the thin region is 1 μm to 5 μm.

8. The method for manufacturing a temporary fixed substrate according to claim 7, wherein: The forming process comprises: a molding step of pouring a raw material slurry containing the translucent ceramic powder into a mold and solidifying the slurry to obtain the molded body; and The deformation step is to deform the molded body obtained in the die casting step by pressing the molded body.

9. The method for manufacturing a temporary fixed substrate according to claim 7, wherein: The forming process comprises: a tape casting step of forming a raw material slurry containing the translucent ceramic powder into a plurality of tapes; a lamination step of laminating and integrating the plurality of tapes to obtain a laminate; a punching step of punching the laminate to obtain the formed body; as well as The deformation step is to deform the formed body obtained in the punching step by pressing it.

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