US-20260130176-A1 - LAMINATED SHEET, METHOD FOR MANUFACTURING LAMINATED SHEET, METHOD FOR PROCESSING WORKPIECE, AND METHOD FOR MANUFACTURING DEVICE CHIP

US20260130176A1US 20260130176 A1US20260130176 A1US 20260130176A1US-20260130176-A1

Abstract

A laminated sheet includes: a first layer having a storage modulus of 1.0E+9 Pa or more and 1.0E+10 Pa or less in a tensile direction under a condition where a frequency of 1 Hz is applied in an environment of 50° C.; and a second layer laminated on the first layer and having a storage modulus of 1.0E+6 Pa or more and 1.0E+8 Pa or less in the tensile direction under the condition where the frequency of 1 Hz is applied in the environment of 50° C. A difference in a solubility parameter between the first layer and the second layer is 3.0 or less. The first layer and the second layer are laminated without an adhesive layer interposed therebetween.

Inventors

Norihisa Arifuku
Masamitsu Kimura
Shingo MOTOIKE

Assignees

DISCO CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251021
Priority Date: 20241106

Claims (13)

1 . A laminated sheet comprising: a first layer having a storage modulus of 1.0E+9 Pa or more and 1.0E+10 Pa or less in a tensile direction under a condition where a frequency of 1 Hz is applied in an environment of 50°C.; and a second layer laminated on the first layer and having a storage modulus of 1.0E+6 Pa or more and 1.0E+8 Pa or less in the tensile direction under the condition where the frequency of 1 Hz is applied in the environment of 50°C., wherein a difference in a solubility parameter between the first layer and the second layer is 3.0 or less, and the first layer and the second layer are laminated without an adhesive layer interposed therebetween.
2 . The laminated sheet according to claim 1 , wherein a thickness of the first layer is smaller than a thickness of the second layer.
3 . A method for processing a workpiece having irregularities on a front surface, the method comprising: fixing the second layer side of the laminated sheet according to claim 1 to the front surface side of the workpiece; and grinding a back surface side of the workpiece after the fixing.
4 . A method for manufacturing a device chip by dividing a workpiece along planned division lines set on a front surface of the workpiece, the method comprising: fixing the second layer side of the laminated sheet according to claim 1 to the front surface or a back surface of the workpiece; and after the fixing, dividing the workpiece along the planned division lines by processing the workpiece from the first surface or the back surface opposite to the surface to which the laminated sheet is fixed.
5 . The method for manufacturing a device chip according to claim 4 , wherein the fixing includes fixing the second layer side of the laminated sheet to the front surface of the workpiece.
6 . The method for manufacturing a device chip according to claim 5 , wherein a film is formed on the back surface of the workpiece.
7 . The method for manufacturing a device chip according to claim 5 , further comprising imaging, via the laminated sheet fixed to the front surface side of the workpiece, the planned division lines set on the front surface of the workpiece, wherein the dividing includes processing the workpiece from the back surface side along the planned division lines based on positions of the planned division lines imaged in the imaging.
8 . A method for manufacturing a laminated sheet, the method comprising: preparing a first sheet and a second sheet, the first sheet having a storage modulus of 1.0E+9 Pa or more and 1.0E+10 Pa or less in a tensile direction under a condition where a frequency of 1 Hz is applied in an environment of 50°C., and the second sheet having a storage modulus of 1.0E+6 Pa or more and 1.0E+8 Pa or less in the tensile direction under the condition where the frequency of 1 Hz is applied in the environment of 50°C. and having a difference in a solubility parameter from the first sheet of 3.0 or less; and laminating the first sheet and the second sheet without an adhesive interposed therebetween, and compressing and bonding the first sheet and the second sheet while melting an interface therebetween by heating.
9 . A method for processing a workpiece having irregularities on a front surface, the method comprising: fixing the second layer side of the laminated sheet according to claim 8 to the front surface side of the workpiece; and grinding a back surface side of the workpiece after the fixing.
10 . A method for manufacturing a device chip by dividing a workpiece along planned division lines set on a front surface of the workpiece, the method comprising: fixing the second layer side of the laminated sheet according to claim 8 to the front surface or a back surface of the workpiece; and after the fixing, dividing the workpiece along the planned division lines by processing the workpiece from the first surface or the back surface opposite to the surface to which the laminated sheet is fixed.
11 . The method for manufacturing a device chip according to claim 10 , wherein the fixing includes fixing the second layer side of the laminated sheet to the front surface of the workpiece.
12 . The method for manufacturing a device chip according to claim 11 , wherein a film is formed on the back surface of the workpiece.
13 . The method for manufacturing a device chip according to claim 11 , further comprising imaging, via the laminated sheet fixed to the front surface side of the workpiece, the planned division lines set on the front surface of the workpiece, wherein the dividing includes processing the workpiece from the back surface side along the planned division lines based on positions of the planned division lines imaged in the imaging.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2024-194456 filed in Japan on Nov. 6, 2024 and Japanese Patent Application No. 2025-108342 filed in Japan on Jun. 26, 2025. TECHNICAL FIELD The present disclosure relates to a laminated sheet, a method for manufacturing the laminated sheet, a method for processing a workpiece, and a method for manufacturing a device chip. BACKGROUND In the manufacturing process of the device chip, the back surface of a wafer, which has a front surface on which a device is formed, is ground to thin the wafer, and dicing is performed along streets to divide the wafer into individual device chips. In grinding the back surface of the wafer, the front surface of the wafer is protected with a sheet for surface protection, and then the back side is ground while the sheet is held on the holding surface of a holding table (see JP 2019 029543 A). When the wafer surface has irregularities such as bumps, if the surface protection sheet is a single layer, the surface protection sheet has irregularities that follows the irregularities such as bumps, resulting in insufficient protection of the wafer surface and causing thickness variation during grinding. Even when the surface protection sheet is a laminated sheet in which two or more layers of sheet are laminated, if the sheets are bonded to each other with an adhesive, the thickness variation of an adhesive layer directly leads to thickness variation during grinding. SUMMARY According to an aspect of the present disclosure, a laminated sheet includes: a first layer having a storage modulus of 1.0E+9 Pa or more and 1.0E+10 Pa or less in a tensile direction under a condition where a frequency of 1 Hz is applied in an environment of 50° C.; and a second layer laminated on the first layer and having a storage modulus of 1.0E+6 Pa or more and 1.0E+8 Pa or less in the tensile direction under the condition where the frequency of 1 Hz is applied in the environment of 50° C. A difference in a solubility parameter between the first layer and the second layer is 3.0 or less. The first layer and the second layer are laminated without an adhesive layer interposed therebetween. According to another aspect of the present disclosure, a method is for manufacturing a laminated sheet. The method includes: preparing a first sheet and a second sheet, the first sheet having a storage modulus of 1.0E+9 Pa or more and 1.0E+10 Pa or less in a tensile direction under a condition where a frequency of 1 Hz is applied in an environment of 50° C., and the second sheet having a storage modulus of 1.0E+6 Pa or more and 1.0E+8 Pa or less in the tensile direction under the condition where the frequency of 1 Hz is applied in the environment of 50° C. and having a difference in a solubility parameter from the first sheet of 3.0 or less; and laminating the first sheet and the second sheet without an adhesive interposed therebetween, and compressing and bonding the first sheet and the second sheet while melting an interface therebetween by heating. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view illustrating a schematic configuration of a laminated sheet according to an embodiment; FIG. 2 is a flowchart illustrating a flow of a method for manufacturing the laminated sheet according to the embodiment; FIG. 3 is a schematic view for explaining an example of the method for manufacturing the laminated sheet; FIG. 4 is a schematic view for explaining an example of the method for manufacturing the laminated sheet; FIG. 5 is a perspective view illustrating a schematic configuration of a workpiece to be processed by the method for processing the workpiece according to the embodiment; FIG. 6 is a flowchart illustrating a flow of the method for processing the workpiece according to the embodiment; FIG. 7 is a side view illustrating a state in a sheet fixing step illustrated in FIG. 6 in a partial cross section; FIG. 8 is a side view illustrating a state after FIG. 7 in a partial cross section; FIG. 9 is a side view illustrating a state in a grinding step illustrated in FIG. 6 in a partial cross section; FIG. 10 is a side view illustrating a state in the grinding step illustrated in FIG. 6 in a partial cross section; FIG. 11 is a flowchart illustrating a flow of a method for manufacturing a device chip according to the embodiment; FIG. 12 is a side view illustrating a state in a sheet fixing step illustrated in FIG. 11 in a partial cross section; FIG. 13 is a side view illustrating a state in an imaging step illustrated in FIG. 11 in a partial cross section; FIG. 14 is a side view illustrating an example of a dividing step illustrated in FIG. 11 in a partial cross section; and FIG. 15 is a side view illustrating another example of the dividing step illustrated in FIG. 11 in a partial cross section. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A