CUTTING METHOD

Abstract

Cutting method for cutting a workpiece (1) in the form of a plate along an intended cutting line (5), wherein the cutting method comprises: Forming a reshaped area (7) in the workpiece (1) along the intended cutting line (5) by applying a laser beam (L) while positioning a condensation point (P) in the workpiece (1); and after forming the transformed area (7) in the workpiece (1), forming a groove (9) in the workpiece (1) along the intended cutting line (5), where in the formation of a groove (9), a first dry etching process is carried out from a front surface (3) to a back surface (4) of the workpiece (1), After the first dry etching process, a first pressure reduction process is carried out in which the workpiece (1) is placed under an atmosphere with reduced pressure compared to the pressure during the first dry etching process, and after the first pressure reduction process a second dry etching process is carried out from the front surface (3) to the back surface (4) of the workpiece (1), where the pressure is not less than 10 Pa during the first dry etching process and during the second dry etching process.

Description

Scope of the invention

[0001] The present invention relates to cutting methods, particularly to a cutting method for cutting a workpiece in the form of a plate along an intended cutting line. State of the art

[0002] There is a well-known machining method for applying a laser beam to position a condensation point in a plate-shaped workpiece to form a reformed region, and then performing an etching process on the reformed region. This machining method is described, for example, in Japanese Patent Application Publication No. JP 2004-359475 A (PTL 1). The machining method described in this publication uses a wet etching process as the etching process for the reformed region. Citation listPatent literature

[0003] PTL 1: Japanese Patent Application, Publication No.: JP 2004- 359 475 A

[0004] US 2013 / 0 059 428 A1 discloses a method for dicing a wafer by using a focused laser beam to create modified regions within the wafer along specific separation lines. An introduced etching gas erodes the modified regions, thereby dividing the wafer into individual pieces. DE 11 2013 002 348 T5 relates to a manufacturing method for a semiconductor substrate in which trenches are formed by etching. US 2005 / 0 287 846 A1 discloses a method for manufacturing a thin-film integrated circuit. WO 2011 / 112 823 A2 teaches manufacturing methods for semiconductor devices suitable for use in low-pitch applications. Summary of the inventionTechnical problem

[0005] A cutting method can be conceived in which a workpiece, such as a semiconductor substrate, is cut using the machining method described in the above publication. When chips to be formed from the semiconductor substrate as a workpiece are small, it is appropriate to employ a dry etching process, which can be manufactured by microfabrication, compared to the wet etching process. When a conventional dry etching process is used as the etching process for the reformed region, a groove formed along an intended cutting line has a narrow width, making it difficult for etching gas to penetrate into the groove. This disadvantageously leads to a low groove formation rate.

[0006] The present invention has been made in view of the above problem, and an object of the present invention is to provide a cutting method capable of increasing the formation rate of a groove along an intended cutting line. Solution to the problem

[0007] A cutting method according to claim 1 is for cutting a workpiece in the form of a plate along an intended cutting line. The cutting method includes: forming a reformed region in the workpiece along the intended cutting line by applying a laser beam while positioning a condensation point in the workpiece; and after forming the reformed region in the workpiece, forming a groove in the workpiece along the intended cutting line. In forming a groove, a first dry etching process is performed from a front surface to a back surface of the workpiece. After the first dry etching process, a first pressure reducing process is performed in which the workpiece is placed under an atmosphere of reduced pressure compared to the pressure during the first dry etching process. After the first pressure reducing process, a second dry etching process is performed from the front surface to the back surface of the workpiece.During the first dry etching process and during the second dry etching process, the pressure is not less than 10 Pa. Advantageous effects of the invention

[0008] According to the cutting method of the present invention, the formation rate of a groove along an intended cutting line can be increased. Short description of the drawings Fig. 1 is a schematic plan view of a workpiece in a cutting method according to an embodiment of the present invention. Fig. 2 is a sectional view along the line II-II in Fig. 1. Fig. 3 is a schematic configuration diagram of a laser processing apparatus for use in forming reformed portions in the cutting process according to the embodiment of the present invention. Fig. 4 is a schematic plan view of the workpiece in which the reformed portions are to be formed in the cutting method according to the embodiment of the present invention. Fig. 5 is a sectional view along the line VV in Fig. 4. Fig. 6 is a schematic plan view of the workpiece after laser processing in the cutting method according to the embodiment of the present invention. Fig. 7 is a sectional view along the line VII-VII in Fig. 6. Fig. 8 is a sectional view along the line VIII-VIII in Fig. 6. Fig. 9 is a schematic plan view of the workpiece after the reformed portions are formed in the cutting method according to the embodiment of the present invention. Fig. 10 is a sectional view taken along the line XX in Fig. 9. Fig. 11 is a schematic configuration diagram of an etching apparatus for use in forming grooves in the cutting process according to the embodiment of the present invention. Fig. 12 is a schematic plan view of the workpiece after the grooves are formed in the cutting process according to the embodiment of the present invention. Fig. 13 is a sectional view along the line XIII-XIII in Fig. 12. Fig. 14 is an enlarged sectional view of an area A in Fig. 10. Fig. 15 is an enlarged sectional view illustrating a first dry etching process performed in Fig. 10 was carried out in area A. Fig. 16 is an enlarged sectional view illustrating a first pressure reducing process performed in Fig. 10 was carried out in area A. Fig. 17 is an enlarged sectional view illustrating a second dry etching process performed in Fig. 10 was carried out in area A. Fig. Figure 18 is an enlarged sectional view illustrating a second pressure reduction process performed in Fig. 10 was carried out in area A. Fig. 19 is an enlarged sectional view illustrating a third dry etching process used in Fig. 10 was carried out in area A. Fig. 20 is a schematic plan view of the workpiece after division. Fig. 21 is a sectional view along the line XXI-XXI in Fig. 20. Fig. 22 is a flowchart illustrating the cutting method according to the embodiment of the present invention. Fig. 23 is a schematic sectional view of a TEG formation region in the workpiece after laser processing in the cutting method according to the embodiment of the present invention. Fig. Fig. 24 is an enlarged sectional view showing a first dry etching process performed at the TEG formation area in Fig. 23 is carried out. Detailed description of embodiments of the invention

[0009] A cutting method according to an embodiment of the present invention will be described below with reference to the drawings. Unless otherwise stated, the same elements are denoted by the same symbols, and their descriptions will not be repeated.

[0010] With reference to the Fig. 1 and Fig. 2, a workpiece 1 is prepared for the cutting method according to the embodiment of the present invention. As shown in the Fig. 1 and Fig. As shown in Figure 2, the workpiece 1 is, for example, a semiconductor substrate. The following describes the case where the workpiece 1 is a semiconductor substrate.

[0011] The semiconductor substrate as workpiece 1 is configured to have a substantially disk shape. The workpiece (semiconductor substrate) 1 has an orientation surface 2 on its outer circumference. The workpiece (semiconductor substrate) 1 is, for example, a silicon (Si) wafer.

[0012] A plurality of functional devices (not shown) are provided on a front surface 3 of the workpiece (semiconductor substrate) 1. In other words, the workpiece (semiconductor substrate) 1 includes a substrate body and the plurality of functional devices arranged on a front surface of the substrate body. The functional devices are, for example, semiconductor operating layers formed by crystal growth, light-receiving devices such as photodiodes, light-emitting devices such as laser diodes, or circuit elements formed as a circuit. The plurality of functional devices are provided in a matrix in directions parallel and perpendicular to the orientation surface 2 of the semiconductor substrate.

[0013] With reference to the Fig. 3 to 10, the formation of a reformed region in the cutting method according to the embodiment of the present invention will be described. First, a laser processing apparatus 100 for use in forming the reformed region will be described.

[0014] As in Fig. 3, the laser processing apparatus 100 includes: a laser source 101 for causing pulse oscillation of a laser beam (processing laser beam) L; a dichroic mirror 103 configured to change the orientation of an optical axis of the laser beam L by 90°; and a condenser lens 105 for converging the laser beam L. The laser processing apparatus 100 also includes: a support table 107 for supporting the workpiece (semiconductor substrate) 1 irradiated with the laser beam L converged by the condenser lens 105; a stage 111 for moving the support table 107 in the X, Y, and Z directions; a laser source controller 102 for controlling the laser source 101 to adjust the output, pulse width, and the like of the laser beam L; and a stage controller 115 for controlling the movement of the stage 111.

[0015] In this laser processing apparatus 100, the laser beam L emitted from the laser source 101 is changed in its optical axis orientation by 90° by the dichroic mirror 103 and condensed by the condenser lens 105 onto the workpiece (semiconductor substrate) 1 placed on the support table 107. At the same time, the stage 111 is moved, causing the workpiece (semiconductor substrate) 1 to move relative to the laser beam L along an intended cutting line. As a result, a reformed region is formed in the workpiece (semiconductor substrate) 1 along an intended cutting line 5, which serves as a starting point for cutting. This reformed region will be described in detail below.

[0016] As in Fig. As shown in Figure 4, the workpiece (semiconductor substrate) 1 in the form of a plate is provided with an intended cutting line 5 along which the workpiece (semiconductor substrate) 1 is to be cut. The intended cutting line 5 is a linearly extending imaginary line. When forming the reformed area within the workpiece 1, the laser beam L is directed relatively along the intended cutting line 5 (namely, in the direction of an arrow A in Fig. 4) while a condensation point P is positioned within the workpiece (semiconductor substrate), as shown in Fig. 5. As a result, as shown in the Fig. 6 to 8, a reformed region 7 is formed within the workpiece (semiconductor substrate) 1 along the intended cutting line 5, and the reformed region 7 formed along the intended cutting line 5 serves as a cutting start point region 8.

[0017] It should be noted that the condensation point P is a point where the laser beam L is converged. The intended cutting line 5 may be curved rather than linear, or a line actually drawn on the front surface 3 of the workpiece 1 rather than the imaginary line. The reformed region 7 may be formed continuously or intermittently. The reformed region 7 should only be formed at least within the workpiece 1. Cracks may originate from the reformed region 7, and the cracks and the reformed region 7 may be exposed on an outer surface (front surface, back surface, or outer peripheral surface) of the workpiece 1.

[0018] The remodeled region 7 refers to a region whose density, refractive index, mechanical strength, or other physical properties have been altered compared to those of a surrounding region. Examples include a melt-processing region, a crack region, a dielectric breakdown region, a region with a changed refractive index, and also a region containing a mixture of these regions.

[0019] With further reference to Fig. 3, the workpiece (semiconductor substrate) 1 is mounted on the support table 107 of the laser processing apparatus 100. Then, with the front surface 3 of the workpiece (semiconductor substrate) 1 as the laser beam entrance surface, the laser beam L is applied while the condensation point P is positioned within the workpiece (semiconductor substrate) 1, and the condensation point P is scanned by moving the support table 107 along the intended cutting lines 5 arranged in a grid pattern to extend through adjacent functional devices. In addition, the condensation point P on the intended cutting line 5 is scanned along a thickness direction of the workpiece (semiconductor substrate) 1.

[0020] As a result, as in Fig. 9, reformed regions 7 are formed in a grid pattern in the workpiece (semiconductor substrate) 1. Each reformed region 7 is formed within the workpiece (semiconductor substrate) 1 from the front surface side 3 to a rear surface side 4 of the workpiece (semiconductor substrate) 1, as shown in Fig. 10. In other words, the reformed region 7 is formed in the thickness direction of the workpiece (semiconductor substrate) 1.

[0021] The reformed region 7 may be formed such that a formation state of the reformed region 7 on the front surface side and a formation state of the reformed region 7 on the back surface side of the workpiece (semiconductor substrate) 1 are substantially identical. In this case, in the thickness direction of the workpiece (semiconductor substrate) 1, a formation state of the reformed region 7 from the center of the workpiece (semiconductor substrate) 1 to the front surface 3 and a formation state of the reformed region 7 from the center to the back surface 4 are substantially identical. In other words, the reformed region 7 is formed symmetrically to the center in the thickness direction of the workpiece (semiconductor substrate) 1.

[0022] With reference to the Fig. 11 to 19, the formation of a groove 9 in the cutting method according to the embodiment of the present invention will be described. First, an etching apparatus 200 for use in forming the groove 9 will be described.

[0023] As in Fig. 11, the etching apparatus 200 includes a chamber 201, a stage 202, a pressure gauge 203, a thermometer 204, a valve 205, a vacuum pump 206, a valve 207, a valve 208, a flow regulator 209, a first gas supply device 210, a valve 211, a flow regulator 212, and a second gas supply device 213.

[0024] In the etching apparatus 200, the chamber 201 is configured to accommodate the workpiece (semiconductor substrate) 1 in which the reformed regions 7 have been formed. The workpiece (semiconductor substrate) 1 is placed on the stage 202 in the chamber 201. Stage 202 is configured to have an adjustable temperature. Stage 202 is heated with the workpiece (semiconductor substrate) 1 placed thereon, thereby heating the workpiece (semiconductor substrate) 1 to a temperature equal to that of stage 202.

[0025] Chamber 201 is connected to pressure gauge 203 for measuring the pressure in chamber 201. Stage 202 is connected to thermometer 204 for measuring the temperature of workpiece 1 based on the temperature of stage 202. Thermometer 204 is connected to stage 202 and measures the temperature of stage 202, thereby measuring the temperature of workpiece (semiconductor substrate) 1, which has been heated to the same temperature as stage 202. Chamber 201 is connected to vacuum pump 206 by a pipe via valve 205. Vacuum pump 206 is a turbomolecular pump or a mechanical booster pump.

[0026] The chamber 201 is connected to the first gas supply device 210 by a pipeline via valve 207, valve 208, and flow regulator 209. The first gas supply device 210 is configured to supply a first etching gas. The chamber 201 is also connected to the second gas supply device 213 by a pipeline via valve 207, valve 211, and flow regulator 212. The second gas supply device 213 is configured to supply a second etching gas. The second etching gas can be identical to or different from the first etching gas. Valve 205, valve 207, valve 208, and valve 211 are each, for example, electronic control valves. Flow regulators 209, 212 are each, for example, mass flow meters.

[0027] While in the Fig. 11, the etching device 200 includes the second gas supply device 213 in addition to the first gas supply device 210, the etching device 200 may include only the first gas supply device 210. In other words, the etching device 200 may include only one gas supply device. Alternatively, the etching device 200 may include three or more gas supply devices.

[0028] As in the Fig. 12 and Fig. As shown in Figure 13, a dry etching process is performed in the etching apparatus 200 from the front surface 3 to the back surface 4 of the workpiece (semiconductor substrate) 1. The dry etching process is an anisotropic dry etching process using a mixed gas of sulfur hexafluoride (SF6), octafluorocyclobutane (C4F8), and oxygen (O2). The front surface 3 of the workpiece (semiconductor substrate) 1 is etched. Here, in the workpiece (semiconductor substrate) 1, the reformed region 7, which is made of, for example, polycrystalline silicon, has a higher etching rate than an unreformed region, which is made of, for example, monocrystalline silicon, and therefore the groove 9 is formed in the front surface 3 of the workpiece (semiconductor substrate) 1 along the intended cutting line 5. The dry etching process can be performed, for example, using a photoresist formed on the functional devices. This photoresist is removed after the dry etching process is completed.

[0029] A pressure reduction process is also performed, in which the workpiece (semiconductor substrate) 1 is placed under an atmosphere with a reduced pressure compared to the pressure during the dry etching process. During the pressure reduction process, the vacuum pump 206 operates to vacuum the chamber 201. In other words, a vacuum is created in the chamber 201 during the pressure reduction process. Any reaction byproduct resulting from the dry etching process is discharged via a pipe by means of the vacuum pump 206.

[0030] In the following, with reference to the Fig. 14 to 19 the formation of the groove 9 is described in detail. Fig. 14 to 19 correspond to an area A, which is in the Fig. 10 and Fig. 13 is enclosed by a dash-dot-dash line.

[0031] As in Fig. 14, after the formation of the transformed region 7 in the workpiece (semiconductor substrate) 1, the groove 9 in the workpiece (semiconductor substrate) 1 is formed along the Fig. 4 shown intended cutting line 5. As shown in Fig. As shown in Figure 15, a first dry etching process is performed on the workpiece (semiconductor substrate) 1 from the front surface 3 to the back surface 4 of the workpiece (semiconductor substrate) 1. The front surface 3 of the workpiece (semiconductor substrate) 1 is etched by the first dry etching process. Furthermore, the groove 9 is partially formed into the reformed area 7 from the front surface 3 to the back surface 4 of the workpiece (semiconductor substrate) 1.

[0032] As in Fig. As shown in Figure 16, a first pressure reduction process is performed after the first dry etching process. In the first pressure reduction process, the workpiece (semiconductor substrate) 1 is placed under an atmosphere with reduced pressure compared to the pressure during the first dry etching process. This removes any reaction byproduct from the interior of the chamber 201 during the first dry etching process, as shown in Figure 16. Fig. 11. Accordingly, the possible reaction by-product remaining in the groove 9 formed by the first dry etching process is removed from the inside of the groove 9.

[0033] As in Fig. As shown in Fig. 17, after the first pressure reduction process, a second dry etching process is performed from the front surface 3 to the back surface 4 of the workpiece (semiconductor substrate) 1. The front surface 3 of the workpiece (semiconductor substrate) 1 is etched by the second dry etching process. Furthermore, the groove 9 is formed at the end of the reformed region 7 from the front surface 3 to the back surface 4 of the workpiece (semiconductor substrate) 1. The second dry etching process can be performed for a longer time than the first dry etching process. The second dry etching process can be performed under a higher pressure than the first dry etching process. This allows a sufficient amount of etching gas to penetrate into the groove formed by the first dry etching process.

[0034] As in Fig. As shown in Figure 18, a second pressure reduction process is performed after the second dry etching process. During the second pressure reduction process, the workpiece 1 is placed in an atmosphere with reduced pressure compared to the pressure during the second dry etching process. Any reaction byproduct that may be present during the second dry etching process is thereby removed.

[0035] As in Fig. As shown in Figure 19, after the second pressure reduction process, a third dry etching process is performed from the front surface 3 to the back surface 4 of the workpiece (semiconductor substrate) 1. The front surface 3 of the workpiece (semiconductor substrate) 1 is etched by the third dry etching process. Furthermore, the groove 9 is formed from the front surface 3 so that it reaches the back surface 4 of the workpiece 1. In this way, the workpiece (semiconductor substrate) 1 is cut along the reformed region 7. The groove 9 can be formed from the front surface 3 so that it reaches the back surface 4 of the workpiece (semiconductor substrate) 1 in the second dry etching process. In the Fig. 12 and Fig. 13, the distance between the chips formed from the cut workpiece (semiconductor substrate) 1 is substantially zero.

[0036] Next, with reference to the Fig. 21 and Fig. 22, the cut workpiece (semiconductor substrate) 1 is divided into chips. In other words, the distance between the chips is increased. In the Fig. 20 and Fig. In the state shown in Figure 21, the distance between the chips is maintained at least at a prescribed distance. The distance between the chips should only be a distance suitable for the next step.

[0037] While the above description described that the dry etching process is performed three times in the first to third dry etching processes and the pressure relief process is performed twice in the first to second pressure relief processes, the cutting method according to the embodiment of the present invention is not limited to these numbers. The dry etching process should be performed only several times (twice or more), and the pressure relief process should be performed only once (once) or several times (twice or more).

[0038] With reference to Fig. 22 As the case where the dry etching process is performed four or more times and the pressure reduction process is performed three or more times, the case where the dry etching process is performed n times and the pressure reduction process is performed n-1 times is described. N, as used herein, means an integer of 4 or more.

[0039] First, a reformed region forming step is performed (step S1). After the reformed region is formed, a groove forming step is performed (step S2). In the groove forming step, a first dry etching process (step S21), a first pressure reducing process (step S22), a second dry etching process (step S23), a second pressure reducing process (S24), and a third dry etching process (step S25) are performed sequentially. Subsequently, the n-2nd pressure reducing process (step S26), the n-1st dry etching process (step S27), the n-1st pressure reducing process (step S28), and the nth dry etching process (step S29) are performed sequentially. In each pressure reducing process, the workpiece is placed under an atmosphere with reduced pressure compared to the pressure during the dry etching process immediately before the pressure reducing process.Once the groove is formed from the front surface so that it reaches the back surface of the workpiece, the workpiece is cut (step S30).

[0040] Next, etching gases for use in the dry etching processes in the cutting method according to the embodiment of the present invention will be described in detail.

[0041] A halogen-based etching gas may be used for each of the first dry etching process and the second dry etching process. A halogen-based etching gas may be used for each of the first to nth dry etching processes. The halogen-based etching gas may include at least one of chlorine trifluoride (ClF3), nitrogen trifluoride (NF3), sulfur hexafluoride (SF6), fluorine (F2), chlorine (Cl2), hydrogen bromide (HBr), carbon tetrafluoride (CF4), octafluorocyclobutane (C4F8), methane trifluoride (CHF3), and boron trichloride (BCl3). In other words, the halogen-based etching gas may be either a single gas or a mixed gas including these materials. For example, the halogen-based etching gas may be a mixed gas of octafluorocyclobutane (C4F8) and oxygen (O2).

[0042] Next, the function and effect of the cutting method according to the embodiment of the present invention will be described. According to the cutting method in the embodiment of the present invention, after the reformed region 7 is formed in the workpiece (semiconductor substrate) 1, the groove 9 is formed in the workpiece (semiconductor substrate) 1 along the intended cutting line 5. In the step of forming the groove 9, utilizing the fact that the reformed region 7 has a higher etching rate than a non-reformed region, the first dry etching process is performed to form the groove 9 in the workpiece (semiconductor substrate) 1 along the intended cutting line 5. After the first dry etching process, the first pressure reducing process is performed to discharge the remaining reaction by-product.After the first pressure reduction process, the second dry etching process is performed to allow the etching gas to quickly penetrate the groove 9 formed in the first dry etching process. This can improve the etching rate in the second dry etching process.

[0043] Namely, when a conventional dry etching process is performed after the formation of the reformed region 7, the pressure in the chamber is kept constant, resulting in a decrease in the etching rate due to the remaining reaction by-product. In contrast, in the cutting method according to the embodiment of the present invention, the second dry etching process is performed after the remaining reaction by-product generated when performing the first dry etching process is discharged from the groove 9 and the interior of the chamber 201 by performing the first pressure reducing process, thereby allowing the etching gas to quickly penetrate into the groove 9 formed in the first dry etching process. This can improve the etching rate compared to a conventional dry etching process.

[0044] According to the cutting method in the embodiment of the present invention, in the step of forming the groove 9, the groove 9 can be formed from the front surface to the back surface of the workpiece 1 to effect cutting of the workpiece 1 along the intended cutting line 5. The etching rate can be improved to enable rapid cutting of the workpiece 1.

[0045] According to the cutting method in the embodiment of the present invention, in the step of forming the groove 9, the second depressurization process is performed after the second dry etching process to thereby discharge the remaining reaction by-product. The third dry etching process is performed after the second depressurization process so that the etching gas can quickly penetrate into the groove 9 formed by the second dry etching process. Furthermore, the groove 9 can be formed by performing a cycle of dry etching, depressurization, and dry etching multiple times. This can further improve the etching rate.

[0046] According to the cutting method in the embodiment of the present invention, a halogen-based etching gas may be used for each of the first dry etching process and the second dry etching process.

[0047] According to the cutting method in the embodiment of the present invention, as the halogen-based etching gas, at least one of chlorine trifluoride (ClF3), nitrogen trifluoride (NF3), sulfur hexafluoride (SF6), fluorine (F2), chlorine (Cl2), hydrogen bromide (HBr), carbon tetrafluoride (CF4), octafluorocyclobutane (C4F8), methane trifluoride (CHF3) and boron trichloride (BCl3) can be used.

[0048] According to the cutting method in the embodiment of the present invention, in the step of forming the reformed region 7 in the workpiece 1, the reformed region 7 can be formed so that a state of formation of the reformed region 7 on the front surface side and a state of formation of the reformed region 7 on the back surface side are substantially identical. This allows the reformed region 7 to be etched evenly from the front surface side and the back surface side of the workpiece 1.

[0049] Next, various variants of the cutting method according to the embodiment of the present invention will be described. A first variant of the cutting method according to the embodiment of the present invention will be described first. As the first variant, which relates to the Fig. 23 and Fig. 24, a TEG (Test Element Group) 10 may be formed on the intended cutting line of the workpiece (semiconductor substrate) 1. In this case, at least one of tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo) may be used as the material for the TEG 10. In other words, in this case, the workpiece (semiconductor substrate) 1 includes the substrate body, the functional devices (not shown), and the TEG 10.

[0050] Therefore, the material for workpiece 1 may include at least one of silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo). In this case, in the step of forming the groove 9, the first dry etching process and the second dry etching process may be performed using a plasmaless chlorine trifluoride (ClF3) gas as the halogen-based etching gas at a pressure of not less than 10 Pa and not more than 90 kPa (abs) and at a temperature of not less than the boiling point of each fluoride in the material and less than 200°C. Referring again to Fig. 11, this pressure is the pressure in chamber 201. This temperature is the temperature of workpiece 1.

[0051] The pressure is set to not less than 10 Pa because the etching rate decreases due to a decrease in the etching reaction rate when the pressure is below 10 Pa. The pressure is set to not less than 10 Pa also because it takes time to adjust the pressure to less than 10 Pa with the vacuum pump 206. The pressure is set to not less than 10 Pa also because the amount of the possible reaction by-product discharged from the groove 9 when the pressure is set to less than 10 Pa remains substantially unchanged from the amount when the pressure is set to 10 Pa. The pressure is set to not less than 10 Pa also because a mechanical booster pump, not a turbomolecular pump, can be used to adjust the pressure to 10 Pa. The pressure is set to not more than 90 kPa because it is difficult to adjust the pressure to more than 90 kPa in a vacuum device.With the plasma-free chlorine trifluoride (ClF3) gas, etching can be performed over a pressure range of not less than 10 Pa and not more than 90 kPa (abs). For this reason, the pressure range is set to not less than 10 Pa and not more than 90 kPa (abs). The chlorine trifluoride (ClF3) gas can etch silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo). For this reason, silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo) are used as the material for workpiece 1. The temperature is set to not less than the boiling point of each fluoride in the material for workpiece 1, because the etching rate in each material can be guaranteed by this setting. The temperature is set to less than 200°C, since a maximum temperature during dicing of the devices formed on workpiece 1 is 200°C.

[0052] In the first variant of the cutting method according to the embodiment of the present invention, the material for the workpiece 1 may include at least one of silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo). In this case, in the step of forming the groove 9, the first dry etching process and the second dry etching process may be performed using a plasmaless chlorine trifluoride (ClF3) gas as the halogen-based etching gas at a pressure of not less than 10 Pa and not more than 90 kPa (abs), and at a temperature of not less than the boiling point of each fluoride in the material and less than 200°C. As a result, the workpiece 1 comprising at least one of silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo) can be etched.

[0053] Next, a second variant of the cutting method according to the embodiment of the present invention will be described. As the second variant, an insulating film may be formed on the intended cutting line of the workpiece. In this case, at least one of silicon dioxide (SiO2), silicon oxynitride (SiON), and silicon nitride (SiNx) may be used as the material for the insulating film. Note that SiNx may vary in composition ratio (x) around Si3N4, which is a ratio of the number of atoms (composition) constituting a SiN compound according to the chemical formula. The value of x must be, for example, not less than 1.0 and not greater than 1.5. In this case, the workpiece (semiconductor substrate) includes the substrate body, the functional devices, and the insulating film.

[0054] Therefore, the material for the workpiece may include at least one of silicon dioxide (SiO2), silicon oxynitride (SiON), and silicon nitride (SiNx). In this case, in the groove-forming step, the first dry etching process and the second dry etching process may be performed with anhydrous hydrogen fluoride (HF) added to the halogen-based etching gas. The etching gas comprising anhydrous hydrogen fluoride (HF) added to the halogen-based etching gas can etch silicon dioxide (SiO2), silicon oxynitride (SiON), and silicon nitride (SiNx). For this reason, the etching gas comprises anhydrous hydrogen fluoride (HF) added to the halogen-based etching gas.

[0055] In the second variant of the cutting method according to the embodiment of the present invention, the material for the workpiece may include at least one of silicon dioxide (SiO2), silicon oxynitride (SiON), and silicon nitride (SiNx). In this case, in the groove forming step, the first dry etching process and the second dry etching process may be performed with anhydrous hydrogen fluoride (HF) added to the halogen-based etching gas. As a result, the workpiece 1 including at least one of silicon dioxide (SiO2), silicon oxynitride (SiON), and silicon nitride (SiNx) can be etched.

[0056] In the plurality of plasmaless dry etching processes in the first variant and the second variant of the cutting method according to the above-described embodiment of the present invention, the volume density of gas molecules can be varied within a range of not less than 10 times and not more than 10,000 times compared to the volume density during the pressure reduction process immediately preceding each dry etching process.

[0057] Next, a third variant of the cutting method according to the embodiment of the present invention will be described. As a third variant, a TEG and an insulating film can be formed on the intended cutting line of the workpiece. In this case, at least one of tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo) can be used as the material for the TEG, and at least one of silicon dioxide (SiO2), silicon oxynitride (SiON), and silicon nitride (SiNx) can be used as the material for the insulating film.

[0058] Therefore, the material for the workpiece may include at least one of silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), molybdenum (Mo), silicon dioxide (SiO2), silicon oxynitride (SiON), and silicon nitride (SiNx). In this case, in the groove forming step, the first dry etching process and the second dry etching process may be performed using at least one of carbon tetrafluoride (CF4), sulfur hexafluoride (SF6), methane trifluoride (CHF3), hydrogen fluoride (HF), and oxygen (O2) in a plasma state as the etching gas at a pressure of not less than 10 Pa and not more than 0.8 kPa (abs) and at a temperature of less than 200°C. This pressure is the pressure in the chamber. This temperature is the temperature of the workpiece.

[0059] Carbon tetrafluoride (CF4), sulfur hexafluoride (SF6), methane trifluoride (CHF3), hydrogen fluoride (HF), and oxygen (O2) in the plasma state can etch silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), molybdenum (Mo), silicon dioxide (SiO2), silicon oxynitride (SiON), and silicon nitride (SiNx). Therefore, silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), molybdenum (Mo), silicon dioxide (SiO2), silicon oxynitride (SiON), and silicon nitride (SiNx) are used as workpiece materials. The pressure is set to no more than 0.8 kPa (abs), since the maximum power in the remote plasma has a pressure of 0.8 kPa.

[0060] In the third variant of the cutting method according to the embodiment of the present invention, the material for the workpiece may include at least one of silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), molybdenum (Mo), silicon dioxide (SiO2), silicon oxynitride (SiON), and silicon nitride (SiNx). In this case, in the groove forming step, the first dry etching process and the second dry etching process may be performed using at least one of carbon tetrafluoride (CF4), sulfur hexafluoride (SF6), methane trifluoride (CHF3), hydrogen fluoride (HF), and oxygen (O2) in a plasma state as the etching gas at a pressure of not less than 10 Pa and not more than 0.8 kPa (abs) and at a temperature of less than 200°C. This allows the workpiece, which comprises at least one of silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), molybdenum (Mo), silicon dioxide (SiO2), silicon oxynitride (SiON) and silicon nitride (SiNx), to be etched.

[0061] Next, a fourth variant of the cutting method according to the embodiment of the present invention will be described. As the fourth variant, an aluminum foil and a TEG can be formed on the intended cutting line of the workpiece. In this case, aluminum (Al) can be used as the material for the aluminum layer, and at least one of tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo) can be used as the material for the TEG.

[0062] Therefore, the material for the workpiece may include at least one of aluminum (Al), silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo). In this case, in the groove forming step, the first dry etching process and the second dry etching process may be performed using at least one of chlorine (Cl2), hydrogen bromide (HBr), hydrogen chloride (HCl), and boron trichloride (BCl3) in a plasma state as the etching gas at a pressure of not less than 10 Pa and not more than 0.8 kPa (abs) and a temperature of less than 200°C. This pressure is the pressure in the chamber. This temperature is the temperature of the workpiece.

[0063] Chlorine (Cl2), hydrogen bromide (HBr), hydrogen chloride (HCl), and boron trichloride (BCl3) in the plasma state can etch aluminum (Al), silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo). For this reason, aluminum (Al), silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo) are used as workpiece materials.

[0064] In the fourth variant of the cutting method according to the embodiment of the present invention, the material for the workpiece includes at least one of aluminum (Al), silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo). In the groove forming step, the first dry etching process and the second dry etching process may be performed using at least one of chlorine (Cl2), hydrogen bromide (HBr), hydrogen chloride (HCl), and boron trichloride (BCl3) in a plasma state as the etching gas at a pressure of not less than 10 Pa and not more than 0.8 kPa (abs) and at a temperature of less than 200°C. Thereby, the workpiece including at least one of aluminum (Al), silicon (Si), tungsten (W), titanium (Ti), titanium nitride (TiN), and molybdenum (Mo) can be etched.

[0065] In the plurality of dry etching processes in the plasma discharge in the third variation and the fourth variation of the cutting method according to the embodiment of the present invention described above, the pressure can be varied in a range of not less than 10% and not more than 100% of the pressure reducing process immediately preceding each dry etching process.

[0066] In the case of a downstream plasma treatment in which a gas exhaust chamber and a substrate-installed chamber are separated by an exhaust pressure control valve, the pressure in the substrate-installed chamber can be varied within a range of at least 1 / 10 and at most 1 / 10000 of the pressure in the gas exhaust chamber, while the exhaust pressure is kept constant.

[0067] It should be understood that the embodiments disclosed herein are in all respects illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, not by the foregoing description, and is intended to include all changes in spirit and scope equivalent to the terms of the claims. Explanation of the reference symbols

[0068] 1 workpiece; 3 front surface; 4 back surface; 5 intended cutting line; 7 reshaped area; 9 groove; 100 laser processing device; 200 etching device; 201 chamber; 202 stage; 203 pressure gauge; 204 thermometer; 205, 207, 208, 211 valve; 206 vacuum pump; 209, 212 flow regulator; 210 first gas supply device; 213 second gas supply device.

Claims

[1] Cutting method for cutting a workpiece (1) in the form of a plate along an intended cutting line (5), the cutting method comprising: Forming a reformed region (7) in the workpiece (1) along the intended cutting line (5) by applying a laser beam (L) while positioning a condensation point (P) in the workpiece (1); and after forming the transformed area (7) in the workpiece (1), forming a groove (9) in the workpiece (1) along the intended cutting line (5), wherein in the formation of a groove (9), a first dry etching process is carried out from a front surface (3) to a back surface (4) of the workpiece (1), after the first dry etching process, a first pressure reduction process is carried out in which the workpiece (1) is placed under an atmosphere with reduced pressure compared to the pressure during the first dry etching process, and after the first pressure reduction process, a second dry etching process is carried out from the front surface (3) to the back surface (4) of the workpiece (1), wherein during the first dry etching process and during the second dry etching process the pressure is not less than 10 Pa. [2] A cutting method according to claim 1, wherein, in forming a groove (9), the groove (9) is formed from the front surface (3) so as to reach the back surface (4) of the workpiece (1) to effect cutting of the workpiece (1) along the intended cutting line (5). [3] Cutting method according to claim 1 or 2, wherein in the formation of a groove (9), after the second dry etching process, a second pressure reduction process is carried out in which the workpiece (1) is placed under an atmosphere with reduced pressure compared to the pressure during the second dry etching process, and after the second pressure reduction process, a third dry etching process is carried out from the front surface (3) to the back surface (4) of the workpiece (1). [4] A cutting method according to any one of claims 1 to 3, wherein in the formation of a groove (9), a halogen-based etching gas is used for each of the first dry etching process and the second dry etching process. [5] The cutting method according to claim 4, wherein the halogen-based etching gas comprises at least one of chlorine trifluoride, nitrogen trifluoride, sulfur hexafluoride, fluorine, chlorine, hydrogen bromide, carbon tetrafluoride, octafluorocyclobutane, methane trifluoride and boron trichloride. [6] Cutting method according to claim 5, wherein a material for the workpiece (1) comprises at least one of silicon, tungsten, titanium, titanium nitride and molybdenum and when forming a groove (9), the first dry etching process and the second dry etching process are carried out using a plasma-free chlorine trifluoride gas as a halogen-based etching gas, at a pressure of not more than 90 kPa (abs) and at a temperature of not less than a boiling point of each fluoride in the material and less than 200°C. [7] Cutting method according to claim 6, wherein the material for the workpiece (1) comprises at least one of silicon dioxide, silicon oxynitride and silicon nitride and when forming a groove (9), the first dry etching process and the second dry etching process are carried out with anhydrous hydrogen fluoride added to the halogen-based etching gas. [8] Cutting method according to claim 1, wherein a material for the workpiece (1) comprises at least one of silicon, tungsten, titanium, titanium nitride, molybdenum, silicon dioxide, silicon oxynitride and silicon nitride, and when forming a groove (9), the first dry etching process and the second dry etching process are carried out using carbon tetrafluoride, sulfur hexafluoride, methane trifluoride, hydrogen fluoride and oxygen in the plasma state as etching gas, at a pressure of not more than 0.8 kPa (abs) and at a temperature of less than 200°C. [9] Cutting method according to claim 1, wherein a material for the workpiece (1) comprises at least one of aluminum, silicon, tungsten, titanium, titanium nitride and molybdenum and when forming a groove (9), the first dry etching process and the second dry etching process are carried out using at least one of chlorine, hydrogen bromide, hydrogen chloride and boron trichloride in a plasma state as an etching gas, at a pressure of not more than 0.8 kPa (abs) and at a temperature of less than 200°C. [10] The cutting method according to any one of claims 1 to 9, wherein, in forming a reformed portion (7) in the workpiece (1), the reformed portion (7) is formed such that a formation state of the reformed portion (7) on the front surface side (3) and a formation state of the reformed portion (7) on the back surface side (4) are substantially identical.

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