Substrate processing method

Abstract

To provide a substrate processing method which relaxes warpage generated in a substrate when the substrate is coated with a resin, thereby reduces the possibility that a problem occurs due to the warpage in a post process, and can easily peel the resin from the substrate.SOLUTION: A substrate processing method includes: a laminated material formation step 101 of applying external stimulus to a resin, in a state of a substrate and a film are integrated with each other through a resin cured by the external stimulus, thereby semi-curing the resin and obtaining a laminated material; a processing step 102 of processing the laminated material; a curing degree improving step 103 of applying the external stimulus to the resin, and thereby improving a curing degree of the resin, after the processing step 102; and a peeling step 104 of peeling the resin and the film from the substrate, after the curing degree improving step 103.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for processing a substrate. [Background technology]

[0002] In the semiconductor wafer manufacturing process, as-sliced ​​wafers are formed by slicing a cylindrical ingot with a wire saw.

[0003] These as-sliced ​​wafers (wafers) have swells and warps due to the slicing process using a wire saw, and these swells and warps are removed by grinding or the like.

[0004] In order to remove waviness and warpage by grinding, a method has been disclosed in which one side of the wafer is coated with resin to form a flat surface, and the other side is ground using the formed flat surface as a reference surface (see, for example, Patent Document 1).

[0005] In the method described in Patent Document 1, a liquid resin that hardens when exposed to ultraviolet light is supplied onto a film held on a holding table, one side of the wafer is brought closer to the holding table to spread the liquid resin, and while the liquid resin is spread on one side of the wafer, ultraviolet light is irradiated to harden the liquid resin, thereby coating one side of the wafer with resin.

[0006] Thereafter, the other surface of the wafer is ground to be flattened, and then the resin and film are peeled off from the wafer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-151099 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the method described in Patent Document 1, the liquid resin may shrink when it hardens, which may cause warping of the wafer.

[0009] If a wafer is warped, various problems may occur in the subsequent processes of transferring the wafer to a grinding device and in the grinding process.

[0010] Another possible method for mitigating warpage is to reduce the degree of hardening of the liquid resin. However, this reduces the fixing force between the resin and the film, which results in the problem that the resin remains on the wafer when peeling the resin and film from the wafer, making peeling difficult.

[0011] The present invention has been made in consideration of such problems, and aims to provide a substrate processing method that reduces the possibility of problems occurring in subsequent processes due to warping by mitigating the warping that occurs in the substrate when the substrate is coated with resin, and that makes it possible to easily peel the resin from the substrate. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems and achieve the object, the substrate processing method of the present invention is a substrate processing method characterized by comprising: a laminate formation step in which the substrate and a film are integrated together via a resin that hardens in response to an external stimulus, and the resin is semi-hardened by applying the external stimulus to the resin to obtain a laminate; a processing step in which the laminate is processed; a hardness improvement step in which, after the processing step, the resin is hardened by applying the external stimulus to the resin to improve its hardness; and a peeling step in which, after the hardness improvement step, the resin and the film are peeled off from the substrate.

[0013] In the substrate processing method, the substrate side of the laminate may be ground in the processing step.

[0014] In the substrate processing method, in the laminate formation step, the resin may be supplied to one side of the film, and one side of the substrate may be pressed against the film to which the resin has been supplied, so that the resin is semi-cured while being spread out on the one side of the substrate. [Effects of the Invention]

[0015] The present invention has the effect of reducing the possibility of problems occurring in later processes due to warping by mitigating the warping that occurs in the substrate when the substrate is coated with resin, and also making it possible to easily peel the resin from the substrate. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a substrate to be processed by the substrate processing method according to the first embodiment. [Figure 2] FIG. 2 is a flowchart showing the flow of the substrate processing method according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view that schematically shows a state in which a resin that hardens in response to an external stimulus is placed on a film on a holding table in the laminate formation step of the substrate processing method shown in FIG. [Figure 4] FIG. 4 is a diagram showing the relationship between the amount of ultraviolet light irradiated onto the semi-cured liquid resin and the adhesive strength in the laminate formation step of the substrate processing method shown in FIG. [Figure 5] Figure 5 is a cross-sectional view schematically showing a state in which one side of a substrate held on the underside of a holding unit is faced to a resin on a film on a holding table that hardens in response to an external stimulus in the laminate formation step of the substrate processing method shown in Figure 2. [Figure 6] Figure 6 is a cross-sectional view schematically showing a state in which one side of a substrate held on the underside of a holding unit is pressed against resin on a film on a holding table that hardens in response to an external stimulus in the laminate formation step of the substrate processing method shown in Figure 2. [Figure 7] 7A to 7C are side views schematically showing processing steps of the substrate processing method shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view schematically showing the hardness improving step of the substrate processing method shown in FIG. [Figure 9] FIG. 9 is a side view schematically showing a laminate before the peeling step of the substrate processing method shown in FIG. [Figure 10] FIG. 10 is a side view schematically showing the peeling step of the substrate processing method shown in FIG. [Figure 11] FIG. 11 is a side view schematically showing the other surface grinding step of the substrate processing method shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0018] [Embodiment 1] A substrate processing method according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view schematically showing a substrate to be processed by the substrate processing method according to the first embodiment. Fig. 2 is a flowchart showing the flow of the substrate processing method according to the first embodiment.

[0019] (substrate) The substrate processing method according to the first embodiment is a method for processing a substrate 1 shown in Fig. 1. The substrate 1 to be processed by the substrate processing method according to the first embodiment is a so-called as-sliced ​​wafer formed into a disk shape by cutting a cylindrical ingot made of silicon, sapphire, gallium, SiC, or the like into a predetermined thickness using a wire saw or the like.

[0020] As shown in Fig. 1, the substrate 1 according to the first embodiment has undulations formed on both a circular first surface 2 (corresponding to one surface) and a circular second surface 3 (corresponding to the other surface) behind the first surface 2. The undulations refer to the curvature of both the first surface 2 and the second surface 3 so that the thickness varies depending on the position on the substrate 1. In the first embodiment, the undulations are generated when the substrate 1 is cut out from an ingot using the wire saw described above. In Fig. 1, the undulations of the first surface 2 and the second surface 3 are shown exaggerated compared to their actual size.

[0021] The substrate processing method according to the first embodiment is a method for flattening both the first surface 2 and the second surface 3 of the substrate 1 and thinning the substrate 1 to a predetermined thickness. As shown in Fig. 2, the substrate processing method according to the first embodiment includes a laminate formation step 101, a processing step 102, a hardness improvement step 103, a peeling step 104, and an other surface grinding step 105.

[0022] (Laminate formation step) Fig. 3 is a cross-sectional view schematically showing a state in which a resin that is cured by an external stimulus is placed on a film on a holding table in the laminate formation step of the substrate processing method shown in Fig. 2. Fig. 4 is a diagram showing the relationship between the amount of ultraviolet light irradiation and adhesive strength of the liquid resin that is semi-cured in the laminate formation step of the substrate processing method shown in Fig. 2. Fig. 5 is a cross-sectional view schematically showing a state in which one side of a substrate held on the lower surface of a holding unit faces the resin that is cured by an external stimulus on a film on the holding table in the laminate formation step of the substrate processing method shown in Fig. 2. Fig. 6 is a cross-sectional view schematically showing a state in which one side of a substrate held on the lower surface of a holding unit is pressed against the resin that is cured by an external stimulus on a film on the holding table in the laminate formation step of the substrate processing method shown in Fig. 2.

[0023] In the laminate formation step 101, the substrate 1 and the film 5 (shown in FIGS. 3 and 5) are integrated together via the resin 4 (shown in FIGS. 3 and 5) that is cured by an external stimulus, and then an external stimulus is applied to the resin 4 to semi-cure the resin 4, thereby obtaining a laminate 10 (shown in FIG. 6). In the laminate formation step 101 in the first embodiment, as shown in FIG. 3, a transparent and flexible disk-shaped film 5 is placed on a flat holding surface 21 of a holding table 20 that is made of a translucent material such as glass and that has a built-in ultraviolet irradiation lamp 30 that irradiates ultraviolet rays 31 (shown in FIG. 6), which is the external stimulus. In the first embodiment, the film 5 is formed in a disk shape with a larger diameter than the substrate 1 and is made of PET (Polyethylene Terephthalate) resin.

[0024] In embodiment 1, in laminate formation step 101, as shown in Fig. 3, liquid resin 4 that hardens in response to an external stimulus is placed on film 5 on holding surface 21 of holding table 20. In embodiment 1, liquid resin 4 is a resin that crosslinks and hardens when irradiated with ultraviolet light 31, which is an external stimulus, and does not soften after hardening even when an external stimulus is applied. Furthermore, the degree of hardening (also referred to as hardness) of liquid resin 4 improves as the amount of ultraviolet light 31 irradiated increases.

[0025] In addition, in embodiment 1, as shown in Fig. 4, the adhesive strength 41 (shown by a solid line in Fig. 4) of the liquid resin 4 to the film 5 improves as the amount of ultraviolet light 31 irradiated increases, and the adhesive strength 42 (shown by a dashed line in Fig. 4) of the liquid resin 4 to the substrate 1 improves as well. Note that the horizontal axis of Fig. 4 indicates the amount of ultraviolet light irradiated, and the vertical axis of Fig. 4 indicates the adhesive strengths 41 and 42. In embodiment 1, the adhesive strength 41 of the liquid resin 4 to the film 5 is higher than the adhesive strength 42 to the substrate 1, and the difference between the adhesive strength 41 to the film 5 and the adhesive strength 42 to the substrate 1 increases as the amount of ultraviolet light 31 irradiated increases.

[0026] In embodiment 1, in laminate formation step 101, the first surface 2 of substrate 1, whose second surface 3 is suction-held on the flat lower surface of holding unit 22, is made to face liquid resin 4 on film 5 on holding surface 21 of holding table 20, as shown in Fig. 5. In embodiment 1, in laminate formation step 101, the first surface 2 of substrate 1, whose second surface 3 is suction-held on the flat lower surface of holding unit 22, is pressed against liquid resin 4 on film 5 on holding surface 21 of holding table 20, as shown in Fig. 6, so that the liquid resin 4 is spread by the first surface 2 of substrate 1 and the liquid resin 4 is brought into close contact with both film 5 and first surface 2 of substrate 1.

[0027] In embodiment 1, in laminate formation step 101, as shown in Fig. 6, the liquid resin 4 that has been brought into close contact with both the film 5 on the holding surface 21 of the holding table 20 and the first surface 2 of the substrate 1 is irradiated with ultraviolet light 31 from an ultraviolet irradiation lamp 30 built into the holding table 20, through the holding table 20 and the film 5. In embodiment 1, in laminate formation step 101, the liquid resin 4 is irradiated with ultraviolet light 31 from the ultraviolet irradiation lamp 30 at a first irradiation amount 43 (shown in Fig. 4).

[0028] In the first embodiment, the first irradiation amount 43 is an irradiation amount at which, when ultraviolet light 31 equal to or greater than the first irradiation amount 43 is irradiated, the liquid resin 4 is semi-cured, the amount of change in thickness of the resin 4 in processing step 102 becomes a predetermined value or less, and the second surface 3 of the substrate 1 can be ground to flatten the second surface 3. In other words, the first irradiation amount 43 is an irradiation amount of ultraviolet light 31 at which the liquid resin 4 is semi-cured, and the second surface 3 of the substrate 1 can be ground to flatten the second surface 3. Semi-curing means that the liquid resin 4 is cured to an extent that the amount of change in thickness of the resin 4 in processing step 102 becomes a predetermined value or less, and the second surface 3 of the substrate 1 can be ground to flatten the second surface 3.

[0029] Thus, in embodiment 1, in laminate formation step 101, the liquid resin 4 that has adhered to both the film 5 and the first surface 2 of the substrate 1 is semi-cured to obtain a laminate 10 in which the film 5, the substrate 1, and the resin 4 are integrated together. Thus, in embodiment 1, in laminate formation step 101, the liquid resin 4 is supplied to one side of the film 5, the first surface 2 of the substrate 1 is pressed against the film 5 to which the resin 4 has been supplied, and the resin 4 is semi-cured in a state in which the resin 4 is spread on the first surface 2 of the substrate 1.

[0030] In the first embodiment, an ultraviolet-curable resin that cures when exposed to ultraviolet light 31, which is an external stimulus, is used as the liquid resin 4, but in the present invention, a thermosetting resin that cures when exposed to heat, which is an external stimulus, may also be used. Also, in the present invention, in the laminate formation step 101, the dose of ultraviolet light 31 irradiated onto the liquid resin 4 that has adhered to both the film 5 and the first surface 2 of the substrate 1 may be set to be equal to or greater than the first dose 43 and less than the second dose 44 described below.

[0031] (Processing Steps) Fig. 7 is a side view schematically showing the processing steps of the substrate processing method shown in Fig. 2. Processing step 102 is a step of processing the laminate 10. In the first embodiment, processing step 102 involves grinding the second surface 3 side of the substrate 1 of the laminate 10.

[0032] In the first embodiment, in processing step 102, a grinding device 50 shown in Fig. 7 suction-holds the first surface 2 of the substrate 1 on a holding surface 52 of a holding table 51 via the film 5 and the semi-cured resin 4. In the first embodiment, in processing step 102, as shown in Fig. 7, the grinding device 50 rotates a grinding wheel 53 about its axis using a spindle (not shown) and rotates the holding table 51 about its axis while supplying grinding water, and also brings a grinding stone 54 into contact with the second surface 3 of the substrate 1 and moves it toward the holding table 51 at a predetermined feed rate, thereby grinding the entire second surface 3 of the substrate 1 with the grinding stone 54 and flattening the second surface 3.

[0033] (Cure improvement step) Fig. 8 is a cross-sectional view schematically showing the hardness improving step of the substrate processing method shown in Fig. 2. The hardness improving step 103 is a step that follows the processing step 102, in which the hardness of the resin 4 is improved by applying ultraviolet light 31, which is an external stimulus, to the resin 4.

[0034] In the first embodiment, in the curing degree improving step 103, the first surface 2 of the substrate 1 is placed on the flat holding surface 21 of the holding table 20 with the film 5 and the resin 4 interposed therebetween, as shown in Fig. 8. In the first embodiment, in the curing degree improving step 103, the resin 4 is brought into close contact with both the film 5 on the holding surface 21 of the holding table 20 and the first surface 2 of the substrate 1, and ultraviolet light 31 is irradiated onto the resin 4 from an ultraviolet irradiation lamp 30 built into the holding table 20 through the holding table 20 and the film 5, as shown in Fig. 8.

[0035] In embodiment 1, in the curing degree improving step 103, the resin 4 is irradiated with ultraviolet light 31 such that the cumulative irradiation amount of ultraviolet light 31 irradiated from the ultraviolet irradiation lamp 30 to the resin 4 from the laminate forming step 101 becomes a second irradiation amount 44 (shown in FIG. 4). Note that in embodiment 1, the second irradiation amount 44 is greater than the first irradiation amount 43, and when ultraviolet light 31 equal to or greater than the second irradiation amount 44 is irradiated, when the film 5 is peeled from the first surface 2 of the substrate 1, the resin 4 can be peeled off from the first surface 2 of the substrate 1 together with the film 5 without remaining on the first surface 2 of the substrate 1.

[0036] That is, when ultraviolet light 31 is irradiated onto resin 4 at an irradiation amount equal to or greater than first irradiation amount 43 and less than second irradiation amount 44, when film 5 is peeled off from first surface 2 of substrate 1, a portion of resin 4 remains on first surface 2 of substrate 1, and the remainder of resin 4 peels off from first surface 2 of substrate 1 together with film 5. Thus, in embodiment 1, in curing degree improving step 103, the curing degree of resin 4 in close contact with both film 5 and first surface 2 of substrate 1 is improved. Also, in the present invention, in curing degree improving step 103, the cumulative irradiation amount of ultraviolet light 31 irradiated onto resin 4 in close contact with both film 5 and first surface 2 of substrate 1 from laminate formation step 101 may be an irradiation amount equal to or greater than second irradiation amount 44.

[0037] (peeling step) Fig. 9 is a side view schematically showing the laminate before the peeling step of the substrate processing method shown in Fig. 2. Fig. 10 is a side view schematically showing the peeling step of the substrate processing method shown in Fig. 2. Peeling step 104 is a step of peeling resin 4 and film 5 from substrate 1 after hardness increasing step 103.

[0038] In the first embodiment, in the peeling step 104, only the film 5 is peeled from the laminate 10 shown in Fig. 9 after the cure improving step 103. Then, in the cure improving step 103, the resin 4 is irradiated with the ultraviolet light 31 at the second irradiation dose 44, so in the peeling step 104, all of the resin 4 is peeled off from the first surface 2 of the substrate 1 together with the film 5, as shown in Fig. 10. Note that in the first embodiment, in the peeling step 104, the film 5 is peeled off from the first surface 2 of the substrate 1 so that one end of the film 5 is centered and the other end is moved away from the first surface 2 of the substrate 1.

[0039] (Other side grinding step) Fig. 11 is a side view schematically showing the other surface grinding step of the substrate processing method shown in Fig. 2. The other surface grinding step 105 is a step of grinding the first surface 2 side of the substrate 1.

[0040] In the first embodiment, in the other-side grinding step 105, a grinding device 50 shown in Fig. 11 suction-holds the flattened second surface 3 side of the substrate 1 on a holding surface 52 of a holding table 51. In the first embodiment, in the other-side grinding step 105, as shown in Fig. 11, the grinding device 50 rotates a grinding wheel 53 about its axis by a spindle (not shown) and rotates the holding table 51 about its axis while supplying grinding water, and brings a grinding stone 54 into contact with the first surface 2 of the substrate 1 and moves it toward the holding table 51 at a predetermined feed rate, thereby grinding the entire first surface 2 of the substrate 1 with the grinding stone 54, flattening the first surface 2 and thinning the substrate 1 to a predetermined thickness.

[0041] The substrate processing method according to the first embodiment described above includes a laminate formation step 101 in which the substrate 1 and the film 5 are integrated together via a liquid resin 4 that hardens in response to an external stimulus, and the resin 4 is semi-hardened to obtain a laminate 10; a processing step 102 in which the laminate 10 is ground as a processing step; a hardness improvement step 103 after the processing step 102 in which the hardness of the resin 4 is improved by applying an external stimulus to the resin 4; and a peeling step 104 after the hardness improvement step 103 in which the resin 4 and the film 5 are peeled off from the substrate 1.

[0042] Therefore, in the substrate processing method of embodiment 1, the liquid resin 4 is semi-cured in the laminate formation step 101, which can suppress the shrinkage of the resin 4 in the laminate formation step 101 and can mitigate the warping that occurs in the substrate 1 when the substrate 1 is covered with the resin 4.

[0043] As a result, the substrate processing method of embodiment 1 alleviates the warping that occurs in the substrate 1 when the substrate 1 is covered with the resin 4, thereby reducing the possibility of problems occurring due to the warping in subsequent processes and making it possible to easily peel the resin 4 from the substrate 1. [Explanation of symbols]

[0044] 1 board 2 1st page (front page) 3 2nd side (other side) 4. Resin 5 Film 10 laminate 101 Laminate formation step 102 Processing Steps 103 Hardening improvement step 104 Peeling Step

Claims

1. A method for processing a substrate, comprising: a laminate formation step of semi-curing the resin by applying an external stimulus to the resin in a state in which the substrate and the film are integrated via the resin that is cured by the external stimulus, thereby obtaining a laminate; a processing step of treating the laminate; a hardness increasing step of increasing the hardness of the resin by applying the external stimulus to the resin after the treatment step; a peeling step of peeling the resin and the film from the substrate after the hardness increasing step.

2. 2. The method for processing a substrate according to claim 1, wherein the processing step includes grinding the substrate side of the laminate.

3. 3. The method for processing a substrate according to claim 1, wherein in the laminate formation step, the resin is supplied to one side of the film, and one side of the substrate is pressed against the film to which the resin has been supplied, and the resin is semi-cured while being spread out on the one side of the substrate.

Images