TW202408710A - Wafer processing methods - Google Patents

Abstract

[Topic] To provide a wafer processing method that can process a wafer having a passivation film deposited on a pattern layer with good quality. [Solution] A wafer processing method is to process a wafer 100 having a pattern layer 120 and a passivation film 130 covering the pattern layer 120 formed on a front surface 111 of a substrate 110 along a predetermined dividing line 112. The wafer processing method comprises the following steps: a passivation film processing step, irradiating a laser beam with a first output along the predetermined dividing line 112 to form a first processing groove 151 in the passivation film 130; a pattern layer processing step, irradiating a laser beam 21 with a second output greater than the first output along the first processing groove 151 to form a second processing groove 152 in the pattern layer 120; and a substrate processing step, processing the substrate 110 along the second processing groove 152.

Description

Wafer processing method

The present invention relates to a method for processing a wafer having a pattern layer covered with a passivation film.

It is known that there is a method for processing a passivation film and a pattern layer with a single laser (see, for example, Patent Document 1). Prior Art Document Patent Document

Patent document 1: Japanese Patent Application Publication No. 2018-026397

Invention Problems to be Solved

However, if the pattern layer becomes thicker, a larger output of laser light will be required to form the processing groove. If the processing is performed with the same output, problems such as the passivation film peeling off and becoming fragile will occur.

The present invention was made in view of the above-mentioned problems, and an object thereof is to provide a wafer processing method that can process a wafer with a passivation film laminated on a pattern layer with good quality. means to solve problems

In order to solve the above-mentioned problems and achieve the purpose, the wafer processing method of the present invention is to process a wafer having a pattern layer and a passivation film covering the pattern layer on the front side of the substrate along a predetermined dividing line. The above-mentioned wafer processing method is characterized by having the following steps: Passivation film processing step, irradiating laser light with a first output along the predetermined dividing line to form a first processing groove in the passivation film; Pattern layer processing step, irradiating laser light with a second output larger than the first output along the first processing groove to form a second processing groove in the pattern layer; and Substrate processing step, processing the substrate along the second processing groove.

Alternatively, the substrate processing step is to manufacture a plurality of chips by dividing the substrate.

Alternatively: the passivation film is polyimide.

Alternatively: the passivation film processing step uses laser light with a pulse width in the range of picoseconds or femtoseconds.

Alternatively, the first processing groove may be wider than the second processing groove. Effect of the invention

The present invention processes the pattern layer with a second laser light having a larger output than the first laser light after processing the passivation film with a first laser light output. This can suppress heat damage to the passivation film 130 and prevent peeling, deterioration, or damage. It can also achieve good quality processing of the pattern layer, and can process a wafer with a passivation film deposited on the pattern layer with good quality.

The form used to implement the invention

The form for implementing the present invention (implementation form) is described in detail with reference to the drawings. The present invention is not limited by the contents described in the following implementation form. Furthermore, the constituent elements described below include constituent elements that can be easily conceived by a person with ordinary knowledge in the relevant technical field and substantially the same constituent elements. In addition, the structures described below can be appropriately combined. Furthermore, various omissions, substitutions or changes in the structure can be made without departing from the gist of the present invention.

[Implementation Form 1] The wafer processing method of implementation form 1 of the present invention is described according to the drawings. FIG. 1 is a flow chart showing the processing procedure of the wafer processing method of implementation form 1. The wafer processing method of implementation form 1 is a method for processing a wafer 100 as described later, and as shown in FIG. 1 , it has a passivation film processing step 1001, a pattern layer processing step 1002, and a substrate processing step 1003.

FIG. 2 is a perspective view of the wafer 100 that is the object to be processed in the wafer processing method according to the first embodiment. FIG. 3 is a cross-sectional view of the wafer 100 of FIG. 2 . As shown in FIGS. 2 and 3 , a pattern layer 120 and a passivation film 130 covering the pattern layer 120 are formed on the front surface 111 of the substrate 110 on the wafer 100 , which is the object of the wafer processing method in Embodiment 1. The substrate 110 is, for example, a disc-shaped semiconductor wafer or an optical device wafer made of silicon as a base material. The base material of the substrate 110 is not limited to this in the present invention, and may also be sapphire, silicon carbide (SiC), gallium arsenide, etc. As shown in FIG. 2 , the substrate 110 has a wafer-sized device region 113 formed in a region defined by a plurality of planned division lines 112 formed in a grid shape on the flat front surface 111 .

The wafer 100 is formed with a plurality of device wafers (see FIG. 2 ). The plurality of device wafers include portions of each device region 113 of the substrate 110 and various pattern layers 120 formed on each device region 113 . and the parts of each passivation film 130 .

In the first embodiment, the pattern layer 120 is a metal pattern layer of an electronic circuit, an electrode, an inspection or evaluation element (test element group, TEG), an integrated circuit (IC), etc. The thickness of the pattern layer 120 is greater than 10 μm and less than 100 μm, and as shown in FIG. 3 , it is substantially thicker than the passivation film 130. When the wafer 100 is divided into a plurality of device chips, the pattern layer 120 may have a thickness equal to or greater than that of the substrate 110.

Although the passivation film 130 is a polyimide film in the first embodiment, the present invention is not limited thereto and may be an oxide film or a nitride film. The thickness of the passivation film 130 is greater than 2 μm and less than 10 μm, and is substantially thinner than the pattern layer 120. The passivation film 130 is not a temporary protective film to be removed after the substrate processing step 1003, but is retained on the upper surface of a plurality of device chips manufactured by dividing the wafer 100 in order to protect the pattern layer 120 constituting the device chip or the device region 113 of the substrate 110. That is, it is preferable that the passivation film 130 does not peel off even when the wafer 100 is divided into a plurality of device chips.

In the first embodiment, as shown in FIG. 2 , the wafer 100 has a supporting member 141 attached to the back surface 114 of the back side of the front surface 111 of the substrate 110, and a ring-shaped frame 142 is installed on the outer edge of the supporting member 141, but the present invention is not limited thereto. The supporting member 141 may be made of an adhesive tape or a sheet, wherein the adhesive tape has a base layer and an adhesive layer laminated on the base layer, wherein the base layer has flexibility and non-adhesion, the adhesive layer has flexibility and adhesion, and the sheet is made of a thermoplastic resin without an adhesive layer. When the supporting member 141 is a non-adhesive thermoplastic resin sheet, it is preferably a polyolefin sheet, a polyethylene sheet, a polypropylene sheet, or a polystyrene sheet, and is attached to the frame 142 or the wafer 100 by heat pressing. The supporting member 141 does not need to be in the form of a sheet from the beginning, and a powder or liquid may be supplied to the back side 104 of the wafer 100 (the back side 114 of the substrate 110), and formed into a sheet covering the back side 104 of the wafer 100 by heat pressing or by pushing or rotary coating.

FIG. 4 is a cross-sectional view illustrating the passivation film processing step 1001 of FIG. 1 . As shown in FIG. 4 , the passivation film processing step 1001 is a step of irradiating the laser beam 11 with the first output along the planned division line 112 to form the first processing groove 151 in the passivation film 130 .

In the passivation film processing step 1001, as shown in FIG. 4, a laser beam 11 having a wavelength that is absorbent to the passivation film 130 is irradiated with a first output toward the side of the wafer 100 on which the passivation film 130 is formed (the front side 101 of the wafer 100, the exposed side 131 of the passivation film 130), while a driving source (not shown) is used to drive the wafer 100 to passivate the film 130. The circle 100 is fed and moved relative to the laser irradiator 10 along the predetermined dividing line 112, whereby the laser beam 11 performs laser processing (so-called ablation processing) on the passivation film 130 along the predetermined dividing line 112, thereby removing the passivation film 130 along the predetermined dividing line 112, and forming a first processing groove 151 that penetrates the passivation film 130 and reaches the depth of the pattern layer 120.

Since the wafer processing method of Embodiment 1 processes the passivation film 130 by irradiating the laser light 11, it is no longer necessary to process the passivation film 130 by a lithography process, so the passivation and passivation costs can be reduced. There are costs associated with the processing of membrane 130.

Fig. 5 is a cross-sectional view illustrating the pattern layer processing step 1002 of Fig. 1. As shown in Fig. 5, the pattern layer processing step 1002 is a step of irradiating the laser beam 21 having a second output greater than the first output along the first processing groove 151 formed in the passivation film processing step 1001 to form a second processing groove 152 in the pattern layer 120.

In the pattern layer processing step 1002, as shown in FIG. 5, the laser irradiator 20 uses a second output larger than the first output to emit wavelengths that are absorptive to the pattern layer 120. The laser beam 21 is irradiated toward the pattern layer 120 exposed on the bottom surface of the first processing trench 151 formed in the wafer 100, while the wafer 100 is moved along the laser irradiator 20 by a driving source not shown in the figure. The pattern layer 120 is relatively fed and moved along the extending direction of the first processing groove 151, thereby performing laser processing (so-called ablation processing) on the pattern layer 120 along the extending direction of the first processing groove 151 with the laser beam 21. The pattern layer 120 is removed along the extending direction of the first processing trench 151 to form a second processing trench 152 with a depth that extends from the bottom surface of the first processing trench 151 and further penetrates the pattern layer 120 to the front surface 111 of the substrate 110 . Furthermore, the extending direction of the first processing groove 151 is along the direction along the planned division line 112 .

Here, since the passivation film 130 processed in the passivation film processing step 1001 is a polyimide film, an oxide film or a nitride film, and is thinner than the pattern layer 120, if the irradiation average output is a laser light that can form the second processing groove 152 in the pattern layer 120, it will be thermally damaged and easily cause peeling or deterioration or damage. Therefore, it is necessary to perform processing by irradiating with a laser light with an average output smaller than the average output suitable for forming the second processing groove 152 (division of the pattern layer 120) in the pattern layer 120. On the other hand, because the pattern layer 120 processed in the pattern layer processing step 1002 includes a wiring structure including a metal pattern layer such as an electronic circuit, an electrode, an inspection or evaluation element, and an integrated circuit, if it is irradiated with a laser beam with an average output smaller than the average output suitable for forming the first processing groove 151 (division of the passivation film 130) on the passivation film 130, the second processing groove 152 cannot be formed. Therefore, it is necessary to process it by irradiating with a laser beam with an average output larger than the average output suitable for dividing the passivation film 130. Therefore, the wafer processing method of implementing form 1 includes two steps, namely, a passivation film processing step 1001 for processing the passivation film 130 and a pattern layer processing step 1002 for processing the pattern layer 120, and by changing the laser light irradiated in the two steps, it is possible to suppress thermal damage to the passivation film 130 and inhibit peeling, deterioration, or damage, and achieve good quality processing of the pattern layer 120.

Therefore, in the wafer processing method of Embodiment 1, the average output of the laser light 11 irradiated in the passivation film processing step 1001, that is, the first output, is higher than that of the laser irradiated in the pattern layer processing step 1002. The average output of the light ray 21, that is, the second output is smaller. Alternatively, the energy density per spot of the laser light 11 irradiated in the passivation film processing step 1001 is smaller than the energy density per spot of the laser light 21 irradiated in the pattern layer processing step 1002 . In Embodiment 1, since the passivation film 130 is a polyimide film that is relatively heat-resistant and may melt due to heat, the use of the laser beam 11 with a small average output not only suppresses polyimide Melting can also be suppressed even if the imide film is peeled off, deteriorated, or damaged, so this embodiment has a more significant effect of suppressing thermal damage to the passivation film 130 . Furthermore, even when the passivation film 130 is an oxide film or a nitride film, peeling, deterioration, and damage of the oxide film or the nitride film can be suppressed. In Embodiment 1, since the thickness of the pattern layer 120 is 10 μm or more and 100 μm or less, by using the laser beam 21 with such a large average output, it is possible to achieve good alignment of the pattern layer 120 . A form of implementation in which the effect of quality processing is more significant. Furthermore, in Embodiment 1, the average output (first output) of the laser beam 11 is, for example, 1.1W, and the average output (second output) of the laser beam 21 is, for example, 6.4W.

Preferably, the laser light 11 is pulse-shaped and has a pulse width in the range of picoseconds or femtoseconds. Here, the pulse width in the range of picoseconds or femtoseconds means a pulse width of ^10-15 seconds or more and ^10-12 seconds or less in Embodiment 1. The wafer processing method of Embodiment 1 sets the pulse width of the laser light 11 to a range of picoseconds or femtoseconds, thereby further suppressing damage to the passivation film 130 in the passivation film processing step 1001. Thermal damage. Furthermore, when the pulse width of the laser light 11 is less than 10 ^-15 seconds, it is difficult with the existing technology. On the other hand, when the pulse width of the laser light 11 is greater than 10 ^-12 seconds, it may cause There is a concern that thermal damage to the passivation film 130 will become greater.

Furthermore, it is preferable that the repetition frequency of the laser light 11 is greater than that of the laser light 21 . Furthermore, it is preferable that the feeding speed of the wafer 100 through the focusing point of the laser light 11 is faster than that of the laser light 21 . The wafer processing method of Embodiment 1 is to set the repetition frequency of the laser light 11 to be greater than that of the laser light 21, and to set the feed speed of the focusing point of the laser light 11 to be greater than The laser light 21 is faster, thereby further suppressing thermal damage to the passivation film 130 in the passivation film processing step 1001, and achieving good quality processing of the pattern layer 120. Furthermore, in Embodiment 1, the repetition frequency of the laser light 11 is, for example, 3000 kHz, and the repetition frequency of the laser light 21 is, for example, 800 kHz. Furthermore, in Embodiment 1, the feeding speed of the focusing point of the laser beam 11 is, for example, 1000 mm/s, and the feeding speed of the focusing point of the laser beam 21 is, for example, 850 mm/s.

In addition, the width 161 of the first processing groove 151 formed in the passivation film processing step 1001 is wider than the width 162 of the second processing groove 152 formed in the pattern layer processing step 1002. Therefore, the wafer processing method of Embodiment 1 can prevent the laser beam 21 irradiated to form the second processing groove 152 in the pattern layer processing step 1002 from accidentally irradiating the edge of the first processing groove 151 or from the first processing groove 152 . The processing groove 151 exceeds and irradiates the passivation film 130, causing the passivation film 130 to peel off, deteriorate or be damaged.

Fig. 6 is a cross-sectional view illustrating the substrate processing step 1003 of Fig. 1. As shown in Fig. 6, the substrate processing step 1003 is a step of processing the substrate 110 along the second processing groove 152. Furthermore, the extending direction of the second processing groove 152 is along the direction of the predetermined dividing line 112.

In the substrate processing step 1003, the substrate 110 is processed along the extension direction of the second processing groove 152, that is, along the predetermined dividing line 112, by various methods, and the substrate 110 is further excavated downward in the thickness direction from the bottom surface of the second processing groove 152 to form a third processing groove 153 (refer to FIG. 6). In the first embodiment, in the substrate processing step 1003, the bottom surface of the third processing groove 153 is further made to reach the back surface 114 of the substrate 110 (the back surface 104 of the wafer 100) and penetrate the substrate 110, thereby dividing the substrate 110 along the predetermined dividing line 112, dividing the wafer 100, and manufacturing a plurality of device chips.

In the first embodiment, the third processing groove 153 having a width 163 narrower than the width 162 of the second processing groove 152 is formed in the substrate processing step 1003. Therefore, the wafer processing method of the first embodiment can prevent the passivation film 130 from being peeled off, deteriorated or damaged by accidentally processing the edge of the first processing groove 151 or processing beyond the first processing groove 151 when the third processing groove 153 is formed in the substrate processing step 1003, and can also prevent the pattern layer 120 from being peeled off, deteriorated or damaged by accidentally processing the edge of the second processing groove 152 or processing beyond the second processing groove 152.

In the first embodiment, the substrate processing step 1003 is implemented by the methods of the first, second, third, fourth and fifth examples described below. The present invention is not limited thereto, and the substrate processing step 1003 may be implemented by combining a part of the methods of the first to fifth examples.

In the method of the first example, the substrate processing step 1003 is performed by plasma etching. Specifically, the first example of the substrate processing step 1003 includes a side protection film deposition step of covering the first processing trench 151 and the second processing trench 152 with the side protection film and a deep digging processing step. As well as the side of the third processing trench 153, the aforementioned deep-drilling processing step is to further dig downward in the thickness direction of the wafer 100 through plasma etching to continue to dig the bottom surface of the second processing trench 152 or the bottom surface of the third processing trench 153. .

The side protection film deposition step is a step of supplying a predetermined plasma gas from the front surface 101 side of the wafer 100 and depositing a side protection film using the supplied plasma gas. In the deep digging processing step, after the side protection film is deposited in the side protection film deposition step, a predetermined plasma gas different from that in the side protection film deposition step is supplied from the front 101 side of the wafer 100, and the supplied plasma gas is used The step of removing the side protective film accumulated on the bottom surface of the third processing trench 153 and performing plasma etching on the substrate 110 on the bottom surface of the third processing trench 153 to deeply dig the third processing trench 153.

In Embodiment 1, in the first example of the substrate processing step 1003, the so-called Bosch Process is performed by alternately repeating the side protection film deposition step and the deep digging processing step in other steps. , so that the etching amount on the side surfaces of the first processing groove 151, the second processing groove 152, and the third processing groove 153 becomes sufficiently smaller than the etching amount on the bottom surface of the third processing groove 153 to form a higher aspect ratio. The third processing ditch 153. Furthermore, the present invention is not limited to this. In the first example of the substrate processing step 1003, the side protection film deposition step and the plasma etching step can also be performed simultaneously and in parallel to form a higher aspect ratio. The third processing ditch 153.

In the method of the second example, the substrate processing step 1003 is performed by cutting using a cutting blade. Specifically, in the second example of the substrate processing step 1003, a cutting blade thinner than the width 162, which is mounted on the front end of a predetermined spindle and is applied by the spindle to a rotational motion about the axis in the Y-axis direction, is moved in the Z-axis direction by a predetermined lifting unit to cut into the substrate 110 from the bottom surface of the second processing groove 152 to a predetermined depth, and then the spindle (cutting blade) is moved by a predetermined driving source. The cutting blade 152 is fed and moved relative to the wafer 100 along the extension direction of the second processing groove 152, so that the cutting blade cuts the substrate 110 along the predetermined splitting line 112, and forms a third processing groove 153 along the predetermined splitting line 112 that penetrates the substrate 110 and reaches the back side 114 of the substrate 110, thereby splitting the substrate 110 along the predetermined splitting line 112.

In the method of the third example, the substrate processing step 1003 is performed by irradiating the substrate 110 of the wafer 100 with laser light having a wavelength that is penetrating. Specifically, in the third example of the substrate processing step 1003, a predetermined laser irradiator is used to irradiate the laser light with a wavelength that is penetrating to the substrate 110 of the wafer 100 toward the substrate 110 formed on the wafer 100. The bottom surface of the second processing trench 152 of the wafer 100 is exposed to the substrate 110 for irradiation, while the wafer 100 is relatively advanced and moved along the planned division line 112 with respect to the laser irradiator by a driving source (not shown). , whereby the laser light forms a modified layer inside the substrate 110 along the planned dividing line 112, and cracks starting from the modified layer and extending toward the front 111 and the back 114, and the modified layer or The crack serves as the third processing groove 153 and divides the substrate 110 along the planned dividing line 112 . Here, the modified layer refers to a region in which density, refractive index, mechanical strength, or other physical properties are different from those of the surroundings, and examples thereof include a melt-processed region, a crack region, and an insulating layer. Damaged areas, refractive index change areas, and areas where these areas are mixed, etc.

In the method of the fourth example, the substrate processing step 1003 is performed by grinding the back surface 114 of the substrate 110 in addition to the same irradiation of laser light as in the third example. Specifically, in the fourth example of the substrate processing step 1003, like the third example, after the modified layer and cracks are formed by irradiating laser light, they are mounted on the front end of a predetermined spindle and are applied by the spindle. The grinding wheel with the grinding stone arranged in an annular shape around the axis along the Z-axis direction moves along the Z-axis direction by a predetermined lifting unit and comes into contact with the grinding wheel positioned below. The back surface 114 side of the substrate 110 of the wafer 100 is pressed, whereby the substrate 110 is ground to a predetermined thickness with a grinding stone and the third processing groove 153 (crack) reaches the back surface 114 side, and the substrate 110 is moved along the back surface 114 of the wafer 100 . It is divided along the planned dividing line 112.

In the method of the fifth example, the substrate processing step 1003 is performed by irradiating the substrate 110 of the wafer 100 with laser light having an absorptive wavelength. Specifically, in the fifth example of the substrate processing step 1003, a predetermined laser irradiator is used to direct laser light of a wavelength that has an absorptive wavelength toward the substrate 110 of the wafer 100 that has been formed on the wafer. The substrate 110 with the bottom surface of the second processing groove 152 of the circle 100 exposed is irradiated, while the wafer 100 is relatively advanced and moved along the planned dividing line 112 with respect to the laser irradiator by a driving source not shown in the figure. In this way, the substrate 110 is subjected to laser processing (so-called ablation processing) with the laser light along the planned division line 112 to form a third layer that penetrates the substrate 110 along the planned division line 112 and reaches the depth of the back surface 114 of the substrate 110 . The groove 153 is processed to divide the substrate 110 along the planned dividing line 112 .

The wafer processing method of Embodiment 1 having the above configuration is to process the passivation film 130 with the laser beam 11 of the first output, and then use the laser beam of the second output which is larger than the first output. 21 to process the pattern layer 120, so the following effects will be exerted: not only suppressing thermal damage to the passivation film 130 to suppress peeling, deterioration, and damage, but also achieving good quality processing of the pattern layer 120, and The wafer 100 in which the passivation film 130 is laminated on the pattern layer 120 can be processed with high quality.

In addition, in the wafer processing method of embodiment 1, since the substrate processing step 1003 forms a plurality of device chips by dividing the substrate 110, even when the wafer 100 has been divided into a plurality of device chips, the passivation film 130 can still be appropriately retained to protect the pattern layer 120 constituting the device chip or part of the device area 113 of the substrate 110.

In addition, in the wafer processing method of Embodiment 1, since the passivation film 130 is made of polyimide, the use of the laser beam 11 with a smaller average output not only suppresses the risk of being less heat-resistant but also melting due to heat. It can also suppress melting of the polyimide film that is suspected of peeling off, deteriorating, or being damaged, so this embodiment has a more significant effect of suppressing thermal damage to the passivation film 130 .

In addition, in the wafer processing method of embodiment 1, since the passivation film processing step 1001 uses the laser beam 11 having a pulse width in the picosecond or femtosecond range, the thermal damage to the passivation film 130 in the passivation film processing step 1001 can be further suppressed.

In addition, in the wafer processing method of embodiment 1, since the width 161 of the first processing groove 151 is wider than the width 162 of the second processing groove 152, it is possible to prevent the laser light 21 irradiated in the pattern layer processing step 1002 from accidentally irradiating the edge of the first processing groove 151 or extending beyond the first processing groove 151 to irradiate the passivation film 130, thereby preventing the passivation film 130 from being peeled off, deteriorated, or damaged.

[Embodiment 2] The wafer processing method according to Embodiment 2 of the present invention will be described based on the drawings. Each of FIGS. 7, 8 and 9 is a cross-sectional view illustrating the passivation film processing step 1001 of the wafer processing method according to Embodiment 2. Each of FIGS. 10, 11, and 12 is a cross-sectional view illustrating the pattern layer processing step 1002 of the wafer processing method according to Embodiment 2. In FIGS. 7 to 12 , the same parts as those in Embodiment 1 are denoted by the same reference numerals, and descriptions thereof are omitted.

The wafer processing method of the implementation form 2 is obtained by changing the structures of the passivation film processing step 1001 and the pattern layer processing step 1002 in the implementation form 1.

The passivation film processing step 1001 in the implementation form 2 is changed into the following structure in the passivation film processing step 1001 in the implementation form 1: before the irradiation of the laser light 11, as shown in FIG. 7, the upper surface protective film 170 is formed on the front surface 101 of the wafer 100 (the exposed surface 131 of the passivation film 130), and as shown in FIG. 8, the laser light 11 is irradiated, and the upper surface protective film 170 and the passivation film 130 are laser-processed along the predetermined dividing line 112 by the laser light 11 to form the first processing groove 151, and after the formation of the first processing groove 151, the upper surface protective film 170 is removed as shown in FIG. 9.

In the passivation film processing step 1001 in the implementation form 2, for example, before the irradiation of the laser beam 11, the wafer 100 is held with the front side 101 facing upward by a holding workbench not shown, and the holding workbench is rotated around an axis parallel to the lead vertical direction, thereby rotating the wafer 100 on the holding workbench while ejecting liquid resin toward the front side 101 of the wafer 100 on the holding workbench by a resin supply nozzle not shown, thereby applying liquid resin on the passivation film 130 of the wafer 100, and the applied liquid resin is dried to form a surface protection film 170 on the surface above the passivation film 130 of the protective wafer 100.

The liquid resin applied in the passivation film processing step 1001 in Embodiment 2 is a water-soluble resin, which can be, for example, polyvinyl alcohol (PVA) or polyvinyl pyrrolidone (PVP). wait. The upper surface protective film 170 formed in the passivation film processing step 1001 in Embodiment 2 prevents damage to the passivation film 130 by chips (processing chips) generated by the laser processing performed by the irradiation of the laser light 11. The attachment of the passivation film 130 to the upper surface. In the passivation film processing step 1001 in Embodiment 2, a water-soluble resin film is formed as the upper surface protective film 170 .

In the passivation film processing step 1001 in implementation form 2, for example, after the formation of the first processing groove 151, the wafer 100 is held with the front side 101 (the side on which the upper surface protective film 170 is formed) facing upward by a holding workbench not shown, and the holding workbench is rotated around an axis parallel to the lead vertical direction, thereby rotating the wafer 100 on the holding workbench while discharging the cleaning liquid toward the upper surface protective film 170 on the front side 101 of the wafer 100 on the holding workbench through a cleaning liquid supply nozzle not shown, thereby removing the upper surface protective film 170. The cleaning liquid may be, for example, pure water or a double fluid mixture of pure water and compressed air, and dissolves the water-soluble resin film, i.e., the upper surface protective film 170.

The pattern layer processing step 1002 in the implementation form 2 is changed into the following structure in the pattern layer processing step 1002 in the implementation form 1: before the irradiation of the laser light 21, as shown in FIG. 10, the upper surface protective film 170 which is the same as the passivation film processing step 1001 in the implementation form 2 is formed on the front surface 101 of the wafer 100 (the exposed surface 131 of the passivation film 130), and as shown in FIG. 11, the laser light 21 is irradiated, and the upper surface protective film 170 and the pattern layer 120 are laser processed along the predetermined dividing line 112 by the laser light 21 to form the second processing groove 152, and after the formation of the second processing groove 152, the upper surface protective film 170 is removed as shown in FIG. 12.

The wafer processing method of implementation form 2 is changed into the following structure in implementation form 1: in the passivation film processing step 1001 and the pattern layer processing step 1002, an upper surface protective film 170 is formed before the irradiation of the laser beams 11 and 21, respectively, and the upper surface protective film 170 is removed after the irradiation of the laser beams 11 and 21 (after the formation of the first processing groove 151 and the second processing groove 152). Therefore, it becomes an implementation form that exerts the same effect as implementation form 1.

In addition, the wafer processing method of Embodiment 2 is preferably as follows: the upper surface protective film 170 further suppresses the peeling, deterioration or damage of the passivation film 130, and can reduce the attachment of the passivation film 130 or mold on the exposed surface 131. Concern about debris in sample layer 120. Furthermore, the present invention is not limited to this. In the case where the passivation film 130 and the pattern layer 120 respectively generated in the passivation film processing step 1001 and the pattern layer processing step 1002 have less debris, or the debris is In cases where the adhesion of the exposed surface 131 of the passivation film 130 will not affect the quality of the device wafer, the formation of the upper surface protective film 170 may be omitted and the wafer processing method of Embodiment 1 may be implemented. That is, the formation of the upper surface protective film 170 is not necessary for the present invention.

In addition, this invention is not limited to the invention of the said embodiment. That is, various modifications can be made without departing from the gist of the present invention.

10,20: Laser irradiator 11,21: Laser beam 100: Wafer 101,111: Front side 104,114: Back side 110: Substrate 112: Predetermined dividing line 113: Device area 120: Pattern layer 130: Passivation film 131: Exposed surface 141: Support member 142: Frame 151: First processing groove 152: Second processing groove 153: Third processing groove 161,162,163: Width 170: Upper surface protective film 1001: Passivation film processing step 1002: Pattern layer processing step 1003: Substrate processing step

FIG. 1 is a flow chart showing a processing procedure of a wafer processing method according to embodiment 1. FIG. 2 is a three-dimensional view showing a wafer that is a processing object of the wafer processing method according to embodiment 1. FIG. 3 is a cross-sectional view of the wafer according to FIG. 2. FIG. 4 is a cross-sectional view illustrating a passivation film processing step of FIG. 1. FIG. 5 is a cross-sectional view illustrating a pattern layer processing step of FIG. 1. FIG. 6 is a cross-sectional view illustrating a substrate processing step of FIG. 1. FIG. 7 is a cross-sectional view illustrating a passivation film processing step of a wafer processing method according to embodiment 2. FIG. 8 is a cross-sectional view illustrating a passivation film processing step of a wafer processing method according to embodiment 2. FIG. 9 is a cross-sectional view illustrating a passivation film processing step of a wafer processing method according to embodiment 2. FIG. 10 is a cross-sectional view illustrating a pattern layer processing step of a wafer processing method according to Embodiment 2. FIG. 11 is a cross-sectional view illustrating a pattern layer processing step of a wafer processing method according to Embodiment 2. FIG. 12 is a cross-sectional view illustrating a pattern layer processing step of a wafer processing method according to Embodiment 2.

20: Laser irradiator

21: Laser beam

100: Wafer

101,111:front

104,114:Back

110: Substrate

120: Pattern layer

130: Passivation film

131: Reveal your face

151: 1st processing ditch

152: Second processing groove

161,162:width

Claims (5)

A wafer processing method is to process a wafer having a pattern layer and a passivation film covering the pattern layer on the front side of a substrate, along a predetermined dividing line. The wafer processing method is characterized by comprising the following steps: a passivation film processing step, irradiating a laser beam with a first output along the predetermined dividing line to form a first processing groove in the passivation film; a pattern layer processing step, irradiating a laser beam with a second output greater than the first output along the first processing groove to form a second processing groove in the pattern layer; and a substrate processing step, processing the substrate along the second processing groove. A wafer processing method as claimed in claim 1, wherein the substrate processing step is to produce a plurality of chips by dividing the substrate. A wafer processing method as claimed in claim 1, wherein the passivation film is polyimide. A wafer processing method as claimed in claim 1, wherein the passivation film processing step uses laser light with a pulse width in the picosecond or femtosecond range. The wafer processing method of claim 1, wherein the first processing groove is wider than the second processing groove.