WO2021172085A1

WO2021172085A1 - Substrate processing method and substrate processing apparatus

Info

Publication number: WO2021172085A1
Application number: PCT/JP2021/005609
Authority: WO
Inventors: 隼斗田之上; 陽平山下
Original assignee: 東京エレクトロン株式会社
Priority date: 2020-02-28
Filing date: 2021-02-16
Publication date: 2021-09-02
Also published as: TW202200299A

Abstract

Provided is a substrate processing method for processing a substrate, the method including irradiating a substrate from a back surface side of the substrate with laser light, and forming a plurality of first peripheral reforming layers along a boundary between a peripheral portion of the substrate to be removed and a center portion of the substrate. From a radially outer side to a radially inner side of the substrate, the plurality of first peripheral reforming layers are formed on positions at different heights so as to be directed toward the back surface side from a surface side in the inside of the substrate.

Description

Substrate processing method and substrate processing equipment

This disclosure relates to a substrate processing method and a substrate processing apparatus.

Patent Document 1 describes a processing apparatus for a polymerized substrate in which a first substrate and a second substrate are joined, and is inside the first substrate along a boundary between a peripheral portion and a central portion to be removed. It is disclosed that a peripheral surface modification layer extending in the thickness direction and an internal surface modification layer extending from the central portion to the peripheral edge portion along the surface direction of the first substrate are formed. According to the processing apparatus described in Patent Document 1, the peripheral edge portion of the first substrate is removed along the peripheral modified layer formed inside the first substrate and the internal surface modified layer, and the peripheral portion is removed. The back surface side of the first substrate is separated (thinning of the first substrate).

International Publication No. 2020/017599

The technique according to the present disclosure appropriately removes the peripheral edge of the substrate and thins the substrate along the modified layer formed inside the substrate.

One aspect of the present disclosure is a substrate processing method for processing a substrate, which irradiates a laser beam from the back surface side of the substrate along a boundary between a peripheral portion of the substrate to be removed and a central portion of the substrate. , A plurality of the first peripheral modification layers are formed, and the plurality of the first peripheral modification layers are formed from the front side to the back surface inside the substrate from the radial outer side to the inner side of the substrate. They are formed at different height positions so as to face the side.

According to the present disclosure, it is possible to appropriately remove the peripheral edge of the substrate and thin the substrate along the modified layer formed inside the substrate.

It is explanatory drawing of the problem in the separation of the 1st wafer. It is a side view which shows the structural example of a polymerization wafer. It is a top view which shows the outline of the structure of the wafer processing system which concerns on this embodiment. It is explanatory drawing which shows an example of the main process in the semiconductor wafer manufacturing process. It is a flow chart which shows an example of the main process in the semiconductor wafer manufacturing process. It is explanatory drawing which shows the formation example of the modified layer in the inside of the 1st wafer. It is a top view which shows the example of forming the modified layer on a 1st wafer. It is explanatory drawing which shows the other formation example of the modified layer in the inside of the 1st wafer. It is explanatory drawing which shows the other formation example of the modified layer in the inside of the 1st wafer. It is an enlarged view which shows the structural example of a polymerization wafer. It is explanatory drawing which shows the other separation example of the 1st wafer. It is a top view which shows the other formation example of the modified layer on a 1st wafer. It is explanatory drawing which shows the other formation example of the modified layer in the inside of the 1st wafer. It is explanatory drawing which shows the other formation example of the modified layer in the inside of the 1st wafer.

In recent years, in a semiconductor device manufacturing process, a peripheral portion of a wafer is removed (so-called edge trim) with respect to a semiconductor substrate (hereinafter, simply referred to as a "wafer") in which devices such as a plurality of electronic circuits are formed on the surface. At the same time, the wafer is separated into a device wafer on the front side and a separated wafer on the back side to be thinned.

Edge trimming and thinning of the wafer are performed using, for example, the substrate processing apparatus disclosed in Patent Document 1. That is, by irradiating the inside of the wafer with a laser beam, a peripheral modification layer serving as a base point for removing the peripheral edge portion and an internal surface modifying layer serving as a base point for separating the wafer are formed, and the peripheral surface modifying layer is formed. The peripheral portion is removed from the base point, and the wafer is separated (thinned) from the internal surface modification layer as the base point.

Further, Patent Document 1 discloses that by forming the peripheral modification layer and the internal surface modification layer at the same height inside the wafer, the peripheral edge portion of the wafer is removed and the back surface side is separated integrally. ing. According to the description of Patent Document 1, the removed separated wafer is recovered. Since the diameter of the separated wafer to be collected is the same as the diameter of the wafer before separation, the separated wafer can be reused as, for example, a support wafer.

However, when the peripheral edge portion of the wafer and the separated wafer are integrally removed in this way, as shown in FIG. 1, when the peripheral edge modification layer M'which is the base point for removing the peripheral edge portion W'e is formed, the peripheral edge is formed. The crack C'extending from the modified layer M'may extend to the back surface W'b of the wafer W'. When the crack C'reaches the back surface W'b in this way, the peripheral edge portion W'e is removed from the separation wafer with the crack C'as the base point, and the removed peripheral edge portion W'e cannot be properly recovered. In addition, the separated wafer may not be recovered in a desired shape and cannot be reused.

The technique according to the present disclosure has been made in view of the above circumstances, and appropriately removes the peripheral edge of the substrate and thins the substrate along the modified layer formed inside the substrate. Hereinafter, the substrate processing apparatus and the substrate processing method according to the present embodiment will be described with reference to the drawings. In the present specification and the drawings, elements having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

In the wafer processing system 1 as a substrate processing apparatus according to the present embodiment, as shown in FIG. 2, as a polymerization substrate in which a first wafer W as a substrate and a second wafer S as another substrate are bonded. Processing is performed on the polymerized wafer T of. Then, in the wafer processing system 1, the peripheral portion We of the first wafer W is removed, and the first wafer W is thinned. Hereinafter, in the first wafer W, the surface on the side to be joined to the second wafer S is referred to as a front surface Wa, and the surface opposite to the front surface Wa is referred to as a back surface Wb. Similarly, in the second wafer S, the surface on the side to be joined to the first wafer W is referred to as the front surface Sa, and the surface opposite to the front surface Sa is referred to as the back surface Sb. Further, in the first wafer W, the radial inner side of the peripheral edge portion We as the removal target is referred to as the central portion Wc.

The first wafer W is a semiconductor wafer such as a silicon substrate, and a device layer D including a plurality of devices is formed on the surface Wa. A surface film Fw is further formed on the device layer D, and is bonded to the surface film Fs of the second wafer S via the surface film Fw. Examples of the surface film Fw include an oxide film (SiO ₂ film, TEOS film), a SiC film, a SiCN film, and an adhesive. The peripheral edge portion We of the first wafer W is chamfered, and the cross section of the peripheral edge portion We becomes thinner toward the tip thereof. Further, the peripheral edge portion We is a portion that is removed when the first wafer W is separated, which will be described later, and is, for example, in the range of 0.5 mm to 3 mm in the radial direction from the outer end portion of the first wafer W.

The second wafer S is, for example, a wafer that supports the first wafer W. Surface films Fs are formed on the surface Sa of the second wafer S, and the peripheral edge is chamfered. Examples of the surface film Fs include an oxide film (SiO ₂ film, TEOS film), a SiC film, a SiCN film, and an adhesive. Further, the second wafer S functions as a protective material (support wafer) for protecting the device layer D of the first wafer W. The second wafer S does not have to be a support wafer, and may be a device wafer on which a device layer is formed as in the first wafer W. In such a case, the surface film Fs is formed on the surface Sa of the second wafer S via the device layer.

In the following description, the separated first wafer W on the front surface Wa side is referred to as a device wafer Wd1, and the separated first wafer W on the back surface Wb side is referred to as a separated wafer Wd2. The device wafer Wd1 refers to the first wafer W in a state of being joined to the second wafer S, and may be referred to as a device wafer Wd1 including the second wafer S. Further, the separated surfaces of the device wafer Wd1 and the separated wafer Wd2 may be referred to as separation surfaces.

As shown in FIG. 3, the wafer processing system 1 has a configuration in which the loading / unloading station 2 and the processing station 3 are integrally connected. At the loading / unloading station 2, for example, a cassette Ct capable of accommodating a plurality of polymerization wafers T, device wafers Wd1, and separation wafers Wd2 is loaded / unloaded from the outside. The processing station 3 is provided with various processing devices that perform desired processing on the polymerized wafer T.

The loading / unloading station 2 is provided with a cassette mounting stand 10. In the illustrated example, a plurality of, for example, three cassette Cts can be freely mounted in a row on the cassette mounting table 10 in the Y-axis direction. The number of cassettes Ct mounted on the cassette mounting table 10 is not limited to this embodiment and can be arbitrarily determined.

The loading / unloading station 2 is provided with a wafer transfer device 20 adjacent to the cassette mounting table 10 on the X-axis negative direction side of the cassette mounting table 10. The wafer transfer device 20 is configured to be movable on a transfer path 21 extending in the Y-axis direction. Further, the wafer transfer device 20 has, for example, two

transfer arms

22 and 22 that hold and transfer the polymerized wafer T. Each transport arm 22 is configured to be movable in the horizontal direction, the vertical direction, the horizontal axis, and the vertical axis. The configuration of the transport arm 22 is not limited to this embodiment, and any configuration can be adopted. The wafer transfer device 20 is configured to be able to transfer the polymerized wafer T to the cassette Ct of the cassette mounting table 10 and the transition device 30 described later.

The loading / unloading station 2 is provided with a transition device 30 for delivering the polymerized wafer T adjacent to the wafer transfer device 20 on the X-axis negative direction side of the wafer transfer device 20.

The processing station 3 is provided with, for example, three processing blocks B1 to B3. The first processing block B1, the second processing block B2, and the third processing block B3 are arranged side by side in this order from the positive direction side of the X axis (the loading / unloading station 2 side) to the negative direction side.

The first processing block B1 includes an etching device 40 that etches the ground surface of the first wafer W ground by the processing device 80 described later, a cleaning device 41 that cleans the ground surface of the first wafer W, and the like. A wafer transfer device 50 is provided. The etching apparatus 40 and the cleaning apparatus 41 are arranged in a laminated manner. The number and arrangement of the etching apparatus 40 and the cleaning apparatus 41 are not limited to this.

The wafer transfer device 50 is arranged, for example, on the Y-axis negative direction side of the etching device 40 and the cleaning device 41. The wafer transfer device 50 has, for example, two

transfer arms

51 and 51 that hold and transfer the polymerized wafer T. Each transport arm 51 is configured to be movable in the horizontal direction, the vertical direction, the horizontal axis, and the vertical axis. The configuration of the transport arm 51 is not limited to this embodiment, and any configuration can be adopted. The wafer transfer device 50 is configured to be able to transfer the polymerized wafer T to the transition device 30, the etching device 40, the cleaning device 41, the interface reformer 60 described later, and the internal reformer 61 described later. There is.

The second processing block B2 is provided with an interface reformer 60 as a second reformer, an internal reformer 61 as a reformer, and a wafer transfer device 70. The interface reformer 60 and the internal reformer 61 are arranged in a laminated manner. The number and arrangement of the interface reformer 60 and the internal reformer 61 are not limited to this.

The interface reformer 60 as the second reforming portion irradiates the outer peripheral portion of the device layer D of the first wafer W with a laser beam (interfacial laser beam, for example, a CO ₂ laser), and serves as a removal target. The interface between the first wafer W and the device layer D at the peripheral edge We of the first wafer W is modified. As a result, an unbonded region Ae in which the bonding strength between the first wafer W and the second wafer S is reduced is formed on the peripheral edge portion We of the first wafer W.

The internal reformer 61 as a reforming unit irradiates the inside of the first wafer W with a laser beam (internal laser beam, for example, a YAG laser) to irradiate the peripheral modifying layer M1 and the internal surface modifying layer M2. Form. The peripheral edge modification layer M1 serves as a base point when removing the peripheral edge portion We. The internal surface modification layer M2 serves as a base point when the first wafer W is separated into the device wafer Wd1 and the separation wafer Wd2.

The wafer transfer device 70 is arranged, for example, on the Y-axis positive direction side of the interface reformer 60 and the internal reformer 61. The wafer transfer device 70 has, for example, two

transfer arms

71 and 71 that attract and hold the polymerized wafer T by a suction holding surface (not shown) and convey it. Each transport arm 71 is supported by an articulated arm member 72, and is configured to be movable in the horizontal direction, the vertical direction, the horizontal axis, and the vertical axis. The configuration of the transport arm 71 is not limited to this embodiment, and any configuration can be adopted. The wafer transfer device 70 is configured to be able to transfer the polymerized wafer T to the etching device 40, the cleaning device 41, the interface reformer 60, the internal reformer 61, and the processing device 80 described later.

The processing device 80 is provided in the third processing block B3.

The processing device 80 has a rotary table 81. The rotary table 81 is rotatably configured around a vertical rotation center line 82 by a rotation mechanism (not shown). Two chucks 83 for sucking and holding the polymerized wafer T are provided on the rotary table 81. The chucks 83 are evenly arranged on the same circumference as the rotary table 81. The two chucks 83 can be moved to the delivery position A0 and the processing position A1 by rotating the rotary table 81. Further, each of the two chucks 83 is configured to be rotatable around a vertical axis by a rotation mechanism (not shown).

At the delivery position A0, the polymerization wafer T is delivered. A grinding unit 84 is arranged at the processing position A1 to grind the first wafer W. The grinding unit 84 has a grinding unit 85 having an annular shape and a rotatable grinding wheel (not shown). Further, the grinding portion 85 is configured to be movable in the vertical direction along the support column 86.

The above wafer processing system 1 is provided with a control device 90 as a control unit. The control device 90 is, for example, a computer equipped with a CPU, a memory, or the like, and has a program storage unit (not shown). The program storage unit stores a program that controls the processing of the polymerized wafer T in the wafer processing system 1. The program may be recorded on a computer-readable storage medium H and may be installed on the control device 90 from the storage medium H.

Next, wafer processing as a substrate processing method performed using the wafer processing system 1 will be described. In this embodiment, the polymerized wafer T is formed in advance in an external bonding device (not shown) of the wafer processing system 1. Further, in the following description, the thickness direction of the first wafer W may be referred to as "vertical direction", and the back surface Wb side of the first wafer W is referred to as "upper" and the front surface Wa side is referred to as "lower".

First, a cassette Ct containing a plurality of polymerized wafers T shown in FIG. 4A is placed on the cassette mounting table 10 of the loading / unloading station 2. Next, the polymerized wafer T in the cassette Ct is taken out by the wafer transfer device 20 and transferred to the transition device 30. The polymerized wafer T transferred to the transition device 30 is subsequently transferred to the interface reformer 60 by the wafer transfer device 50. In the interface reformer 60, as shown in FIG. 4B, the interface between the first wafer W and the device layer D is irradiated with a laser beam to reform the interface (step P1 in FIG. 5).

When the interface between the first wafer W and the device layer D is modified in step P1, the bonding strength between the first wafer W and the second wafer S decreases. As a result, at the interface between the first wafer W and the device layer D, the bonding strength is reduced at the bonding region Ac where the first wafer W and the second wafer S are bonded and the radial outside of the bonding region Ac. An unbonded region Ae, which is a region, is formed.

The "modification" of the interface in the formation of the unbonded region Ae refers to a process of reducing the bonding strength between the first wafer W and the second wafer S, or eliminating the bonding strength, for example, a laser. It shall include peeling, removal, amorphization, etc. of the interface by irradiation with light.

The polymerized wafer T on which the unbonded region Ae is formed is subsequently transferred to the internal reformer 61 by the wafer transfer device 50. In the internal reformer 61, as shown in FIGS. 4C and 4D, the peripheral reforming layer M1 and the internal surface reforming layer M2 are sequentially formed inside the first wafer W (FIG. 6). Step P2 and step P3) of step 5.

In forming the peripheral modification layer M1, the laser light is periodically irradiated from the laser head (not shown) while rotating the layered wafer T (first wafer W), and the irradiation position of the laser light is set to the first position. Wafer W is moved to the inside in the radial direction and to the back surface Wb side of the first wafer W. In other words, as shown in FIG. 6, the plurality of peripherally modified layers M1 formed inside the first wafer W have higher formation positions toward the inner side in the radial direction of the first wafer W in cross-sectional view. They are formed at different height positions so as to be. Further, as shown in FIG. 7, the peripheral modification layer M1 is formed in an annular shape concentric with the bonding region Ac (unbonded region Ae). The number of peripheral modification layers M1 formed on the first wafer W is not limited to the illustrated example, and can be arbitrarily determined.

Inside the first wafer W, along the forming direction of the peripheral modification layer M1, that is, from the outer side to the inner side in the radial direction of the first wafer W, from the front surface Wa side to the back surface of the first wafer W. The crack C1 (crack) extends toward the Wb side. As shown in FIG. 6, the crack C1 makes the lower end portion reach the front surface Wa of the first wafer W, and the upper end portion does not reach the back surface Wb. In other words, the extension length of the crack C1 is determined by the formation interval of the peripheral modification layer M1 and the output of the laser beam, so that the crack C1 does not reach the front surface Wa and the back surface Wb in this way. , The formation operation of the peripheral modification layer M1 is controlled.

Further, when the first wafer W is separated later, the peripheral edge portion We is removed from the device wafer Wd1 with the peripheral edge modifying layer M1 and the crack C1 as base points. In order to properly remove the peripheral edge portion We, it is desirable that the peripheral edge modifying layer M1 is formed, for example, at an interval at which the cracks C1 extending from the adjacent peripheral edge modifying layer M1 are connected to each other. Further, for example, the formation interval may be controlled so that a part of the adjacent peripheral modification layers M1 overlap each other.

Here, the crack C1 extending inside the first wafer W generally tends to easily extend along the crystal orientation of the first wafer W. Usually, the crystal orientation of the first wafer W is often spread in the plane direction and the thickness direction of the first wafer W from the viewpoint of molding and processing, so that the peripheral edge is modified as shown in FIG. When the quality layers M'are arranged side by side in the thickness direction, the crack C1 easily extends in the thickness direction, that is, easily reaches the back surface Wb.

In this respect, in the present embodiment, the adjacent peripheral modification layers M1 are formed by shifting them in the thickness direction and the radial direction, respectively, in other words, they are formed side by side in the diagonal direction. As a result, the extension of the crack C1 is suppressed and the arrival of the crack C1 on the back surface Wb is suppressed as compared with the case where the peripheral modification layers M'are arranged in the thickness direction as in the conventional case. At this time, in the present embodiment, the formation interval of the peripheral modification layer M1 is controlled to the formation interval in which the cracks C1 are connected to each other or the formation interval so that a part of the peripheral modification layer M1 overlaps with each other. Therefore, it is possible to more appropriately prevent the crack C1 from reaching the back surface Wb.

Further, as shown in FIG. 6, the formation position of the peripheral modification layer M1 (1) formed on the outermost radial direction inside the first wafer W was formed by the interface modifier 60. It is determined to be slightly inward in the radial direction from the inner peripheral side end of the unjoined region Ae, that is, the boundary Ad between the joined region Ac and the unjoined region Ae. The boundary Ad is detected, for example, by using an IR camera or the like in the formation result of the unbonded region Ae in the interface reformer 60 or in an alignment device (not shown) provided at an arbitrary position in the wafer processing system 1.

Ideally, the peripheral modification layer M1 is formed at a position overlapping the boundary Ad, but it may be formed so as to be displaced in the radial direction due to, for example, a processing error. As a result, when the peripheral modification layer M1 is formed radially outside the boundary Ad, that is, in the unbonded region Ae, the first wafer W with respect to the second wafer S after the peripheral edge We is removed. May become floating. In this respect, by controlling the peripheral modification layer M1 to be formed radially inside the boundary Ad, for example, even if the formation position shifts due to a processing error, the position overlaps with the boundary Ad or the diameter is larger than the boundary Ad. The peripheral modification layer M1 can be formed at a position close to the boundary Ad even on the outer side in the direction, and the floating state of the first wafer W is suppressed.

When the peripheral modification layer M1 is formed, the laser head (not shown) is moved to extend the inner surface modification layer in the radial direction of the peripheral modification layer M1 in the surface direction of the first wafer W. Form M2. In forming the internal surface modification layer M2, the laser beam is periodically irradiated from the laser head while rotating the layered wafer T (first wafer W), and the irradiation position of the laser beam is set on the first wafer W. Move inward in the radial direction. As a result, the internal surface modification layer M2 is formed on the entire surface of the first wafer W along the surface direction. The radial formation interval of the inner surface modified layer M2 can be arbitrarily determined.

Inside the first wafer W, cracks C2 extend along the formation direction of the internal surface modification layer M2, that is, along the surface direction of the first wafer W. When the first wafer W is separated later, the separated wafer Wd2 is separated from the device wafer Wd1 with the internal surface modification layer M2 and the crack C2 as base points. In order to properly perform such peeling, as shown in FIG. 6, the radial outer end of the crack C2 is connected to the upper end of the crack C1, and the cracks C2 extending from the adjacent internal surface modification layers M2 are mutually formed. It is desirable to connect to.

Here, in the present embodiment, the peripheral modification layer M1 is set to the radial inside of the first wafer W and the back surface Wb of the first wafer W while rotating the polymerized wafer T as described above. It is formed by moving it to the side. Further, the internal surface modification layer M2 is formed by moving the irradiation position of the laser beam in the radial direction of the first wafer W while rotating the polymerized wafer T as described above.

That is, in the present embodiment, the formation of the inner surface modified layer M2 is continued to the formation of the peripheral modified layer M1 by stopping the movement of the irradiation position of the laser beam in the thickness direction at the time of forming the peripheral modified layer M1. It is possible to do it continuously. In other words, it is not necessary to stop the irradiation of the laser beam in the transition from the formation of the peripheral modification layer M1 to the formation of the inner surface modification layer M2. Then, by continuously forming the peripheral modification layer M1 and the internal surface modification layer M2 from the outside in the radial direction without stopping the irradiation of the laser beam in this way, the modification layer in the internal modification device 61 is formed. The throughput related to the operation can be greatly improved.

The polymerized wafer T on which the internal surface modification layer M2 is formed is then transferred to the processing device 80 by the wafer transfer device 50. In the processing apparatus 80, first, when the polymerized wafer T is delivered from the transport arm 71 to the chuck 83, as shown in FIG. 4 (e), the peripheral modification layer M1, the crack C1, the inner surface modification layer M2 and the crack C2 The first wafer W is separated into the device wafer Wd1 and the separation wafer Wd2 (step P4 in FIG. 5). At this time, the peripheral portion We of the first wafer W is also removed from the first wafer W together with the separated wafer Wd2.

In the separation of the first wafer W in step P4, the first wafer W is sucked and held by the suction surface 71a provided on the transport arm 71, and the second wafer S is sucked and held by the chuck 83. After that, the transfer arm 71 is raised while the suction surface 71a sucks and holds the back surface Wb of the first wafer W to separate the first wafer W into the device wafer Wd1 and the separation wafer Wd2. Then, as described above, in step P4, the separation wafer Wd2 and the peripheral edge portion We are integrally separated. That is, the peripheral portion We is removed and the first wafer W is separated (thinned) at the same time.

Here, when the peripheral modification layers M1 are arranged side by side in the thickness direction of the first wafer W, when the separation wafer Wd2 is lifted upward by the transport arm 71, the separation wafer Wd2 is as shown in FIG. There is a risk of interfering with the corner K of the device wafer Wd1. Then, when the separated wafer Wd2 interferes with the device wafer Wd1 in this way, the corner portion K may be chipped. In this respect, in the present embodiment, the adjacent peripheral modification layers M1 are formed so as to be displaced in the thickness direction and the radial direction, respectively, in other words, they are formed side by side in the oblique direction. As a result, the corner portion K is not formed on the device wafer Wd1, and it is possible to prevent the device wafer Wd1 and the separated wafer Wd2 from interfering with each other when the separated wafer Wd2 is raised. Since the chipping of the corner portion K is suppressed in this way, the deterioration of the quality of the device wafer as a product is suppressed, and the internal contamination of the wafer processing system 1 by the particles generated by the chipping is suppressed.

The separated wafer Wd2 is collected outside the wafer processing system 1, for example. Further, for example, a recovery unit (not shown) may be provided within the movable range of the transport arm 71, and the separated wafer Wd2 may be collected by the recovery unit.

Further, in the present embodiment, the transfer arm 71 is used to separate the first wafer W in the processing apparatus 80, but the wafer processing system 1 is a separation apparatus for separating the first wafer W (FIG. (Not shown) may be provided. The separation device can be arranged so as to be laminated with, for example, the interface reformer 60 and the internal reformer 61. Further, the method for separating the first wafer W can also be arbitrarily determined.

When the first wafer W is separated, the chuck 83 is subsequently moved to the machining position A1 and the grinding unit 84 grinds the separated surface of the device wafer Wd1 as shown in FIG. 4 (f) (FIG. 5). Step P5). By such a grinding process, the peripheral modification layer M1 and the internal surface modification layer M2 remaining on the separation surface of the device wafer Wd1 are removed, and the device wafer Wd1 is reduced to a desired finish thickness.

The polymerized wafer T in which the first wafer W is thinned to a desired thickness in the processing apparatus 80 is conveyed to the cleaning apparatus 41 by the wafer transfer apparatus 70, and the ground surface of the device wafer Wd1 is cleaned in step P6 of FIG. ).

Subsequently, the polymerized wafer T is transferred to the etching device 40 by the wafer transfer device 50, and the ground surface of the device wafer Wd1 is wet-etched by the chemical solution (step P7 in FIG. 5).

After that, the polymerized wafer T that has been subjected to all the processing is transported to the transition device 30 by the wafer transfer device 50, and further transferred to the cassette Ct of the cassette mounting table 10 by the wafer transfer device 20. In this way, a series of wafer processing in the wafer processing system 1 is completed.

In the above embodiment, the unbonded region Ae is formed by the interface reformer 60 provided inside the wafer processing system 1, but in the unbonded region Ae, the polymerized wafer T is carried into the wafer processing system 1. It may be preformed before it is used. In such a case, the interface reformer 60 may be omitted in the configuration of the wafer processing system 1.

According to the above embodiment, the cracks C1 extending from the peripheral modification layer M1 are formed on the first wafer by forming the adjacent peripheral modification layers M1 so as to be arranged in the diagonal direction while shifting in the thickness direction and the radial direction, respectively. Reaching the back surface Wb of W is suppressed. As a result, it is possible to prevent the peripheral edge portion We from being unintentionally peeled from the separated wafer Wd2, and the separated wafer Wd2 can be appropriately reused.

Further, according to the above embodiment, the peripheral modification layer M1 and the inner surface modification layer M2 are continuously formed from the radial outside of the first wafer W without stopping the irradiation of the laser beam. Can be done. As a result, the throughput required for the reforming layer forming operation in the internal reformer 61 can be appropriately improved.

Further, according to the above embodiment, by forming the adjacent peripheral modification layers M1 in an oblique direction, the corner portion K is not formed at the end of the device wafer Wd1, and the first wafer W is separated. The concentration of stress on the end of the device wafer Wd1 is suppressed. As a result, it is suppressed that the end portion of the device wafer Wd1 is chipped when the first wafer W is separated, the generation of particles inside the wafer processing system 1 is suppressed, and the device wafer Wd1 as a product is defective. Is suppressed.

When the adjacent peripheral modification layers M1 are formed by arranging them in an oblique direction in this way, as shown in FIG. 4 (f), the end portion of the device wafer Wd1 reduced to the final finish thickness has an inclination. However, there is a risk that the device wafer Wd1 cannot be properly commercialized, especially at this end. Therefore, the peripheral modification layers formed in the wafer processing system 1 are formed so as to be arranged in a direction perpendicular to the surface direction of the first wafer W, at least on the surface Wa side of the final finish thickness of the device wafer Wd1. Is preferable.

Specifically, as shown in FIG. 8, the peripheral modification layers formed inside the first wafer W are formed by arranging the peripheral modification layers in an oblique direction as shown in the above embodiment. It is preferable to have the layer M1 and the second peripheral modification layer M3 formed side by side in the thickness direction of the first wafer W.

The first peripheral edge modification layer M1 is formed so as to be arranged diagonally inside the first wafer W as described above, and the upper end portion of the crack C1 extends from the inner surface modification layer M2 to the outer peripheral side end of the crack C2. Connect with the unit. Further, the lower end portion of the crack C1 does not reach the surface Wa of the first wafer W, and is positioned at least above the final finish thickness height G of the device wafer Wd1.

The second peripheral modification layer M3 is formed inside the first wafer W so as to be arranged in the thickness direction. Further, it is preferable that the second peripheral edge modification layer M3 is formed slightly inside the boundary Ad between the unbonded region Ae and the bonding region Ac in the radial direction and above the final finish thickness height G of the device wafer Wd1. Further, the crack C3 extending from the second peripheral edge modifying layer M3 in the thickness direction of the first wafer W has the lower end portion reaching the surface Wa of the first wafer W and the upper end portion with the lower end portion of the crack C1. Connecting.

In this way, the second peripheral modification layers M3 are formed side by side in the thickness direction of the first wafer W, and the second peripheral modification layers M3 are formed above the final finish thickness height G of the device wafer Wd1. By locating it, it is appropriate to appropriately suppress the formation of an inclination at the end of the device wafer Wd1 as a product, and it is appropriate that the peripheral modification layers M1 and M3 remain on the device wafer Wd1 after the finish grinding process. Is suppressed. Further, by forming the peripheral modification layers M1 diagonally above the final finish thickness height G, it is appropriate that the corner portions K are formed on the device wafer Wd1 when the first wafer W is separated. It is suppressed. Furthermore, by forming the second peripheral modification layer M3 side by side in the thickness direction of the first wafer W, the crack C3 can easily extend in the thickness direction of the first wafer W, that is, the first wafer can be appropriately extended. The crack C3 can be extended to the surface Wa of W.

In the above embodiment, for example, when forming the peripheral modification layer M1, the laser beam irradiation position is moved at a constant speed in the radial direction and the thickness direction of the first wafer W, as shown in FIG. In addition, the peripheral modification layer M1 is arranged in a substantially linear shape in a cross-sectional view, but the arrangement of the peripheral modification layer M1 is not limited to this. For example, by controlling the movement of the irradiation position of the laser beam in the formation of the peripheral modification layer M1, the peripheral modification layer M1 may be arranged in a substantially round shape in a cross-sectional view as shown in FIG. Even in such a case, since the corner portion K is not formed on the device wafer Wd1, it is appropriately suppressed that the device wafer Wd1 is chipped when the first wafer W is separated. Further, since the peripheral modification layers M1 are not formed side by side in the thickness direction, it is suppressed that the crack C1 extends in the thickness direction of the first wafer W and reaches the back surface Wb of the first wafer W.

In the above embodiment, the unbonded region Ae is formed at the interface between the first wafer W and the device layer D in the interface reformer 60 provided inside or outside the wafer processing system 1. The unbonded region Ae does not necessarily have to be formed. Specifically, as shown in FIG. 2, the peripheral edges of the first wafer W and the second wafer S are chamfered, whereby the chamfering is formed to have a smaller thickness toward the end. The part is formed. In other words, in the polymerized wafer T in which the first wafer W and the second wafer S on which the chamfered portion is formed are joined, the first wafer W and the second wafer S are formed in the chamfered portion. Can be regarded as unjoined.

Therefore, as shown in FIG. 10, in the polymerized wafer T, the formation range of the chamfered portion R of the first wafer W and the second wafer S is defined as the unbonded region Ae, in other words, the chamfered portion R is the removal target. It may be regarded as the peripheral edge We of the first wafer W. That is, the inner peripheral side end portion of the chamfered portion R can be regarded as the boundary Ad in the above embodiment, and the peripheral modification layer M1 can be formed slightly radially inside the boundary Ad. Then, in such a case, the lower end portion of the crack C1 extending from the peripheral modification layer M1 is brought to reach the radial inner end portion of the chamfered portion R on the surface Wa side of the first wafer W. As a result, it is not necessary to form an unbonded region Ae at the interface of the first wafer W by irradiating the laser beam, so that the time required for wafer processing can be shortened and it is not necessary to configure the interface modifier 60. Therefore, the system configuration can be simplified. Further, by making the lower end portion of the crack C1 reach the radial inner end portion of the chamfered portion R, the peripheral edge portion We can be removed more appropriately.

Further, even if the peripheral modification layer M1 is formed inside the first wafer W so that the crack C1 reaches the front surface Wa and the back surface Wb of the first wafer W, respectively, as shown in FIG. 11A. good. That is, as shown in FIG. 11B, only the peripheral edge portion We may be removed from the first wafer W with the peripheral edge modifying layer M1 and the crack C1 as base points. The removed peripheral edge We is collected, for example, in a collection unit (not shown). When the peripheral edge modification layers M1 are formed in an oblique direction in this way to remove the peripheral edge portion We, as shown in the above embodiment, the corner portion to the first wafer W after the peripheral edge portion We is removed. The formation of K is suppressed, that is, the occurrence of chipping at the corner K of the first wafer W is suppressed. As a result, the generation of particles inside the wafer processing system 1 is suppressed, and the quality deterioration of the first wafer W (device wafer Wd1) as a product is suppressed.

Further, when removing only the peripheral edge portion We from the first wafer W with the peripheral edge modifying layer M1 and the crack C1 as the base points, after that, for example, the processing apparatus 80 grinds the back surface Wb of the first wafer W to the first wafer W. The wafer W of 1 is thinned. In such a case, as shown in FIG. 11, the crack C1 is formed in an oblique direction with respect to the surface Wa of the first wafer W, so that the outer edge portion of the first wafer W after grinding may be chipped. It is suppressed. As a result, the generation of particles inside the wafer processing system 1 after grinding is suppressed, and the quality deterioration of the first wafer W (device wafer Wd1) as a product is suppressed.

When the technique of the present disclosure is used to prevent the outer edge of the first wafer W from being chipped after grinding, the crack C1 is formed in an oblique direction with respect to the surface Wa of the first wafer W. Then, while the crack C1 is being formed in the oblique direction, the direction of the crack C1 may be directed in the direction perpendicular to the surface Wa of the first wafer W. That is, the lower end portion of the crack C1 may be formed in an oblique direction with respect to the front surface Wa, and the upper end portion of the crack C1 may be formed in a direction perpendicular to the back surface Wb. However, the range formed in which the expansion direction of the crack C1 is directed in the direction perpendicular to the surface Wa of the first wafer W is formed so as to be removed by the subsequent grinding.

The positions where the crack C1 faces obliquely with respect to the surface Wa of the first wafer W (that is, the position where the extension direction of the crack C1 changes from the vertical direction to the diagonal direction) are the positions of the first wafer W and the second wafer S. It is determined at the inner peripheral side end of the unjoined region Ae. Alternatively, the position may be determined slightly inward in the radial direction with respect to the inner peripheral side end portion of the unjoined region Ae. The unjoined region Ae may be an unjoined region Ae that has been modified as shown in FIG. 6 to reduce the joining strength, or may be a chamfered portion R as shown in FIG. good.

Further, when removing only the peripheral edge portion We from the first wafer W with the peripheral edge modifying layer M1 and the crack C1 as the base points, it is preferable to fragment the peripheral edge portion We in the circumferential direction. As a method of fragmenting the peripheral edge portion We, for example, a plurality of divided and modified layers M4 are formed inside the peripheral edge portion We, and the peripheral edge portion We is fragmented using the plurality of divided and modified layers M4 as a base point.

Specifically, for example, in the internal reformer 61, the inside of the first wafer W (peripheral portion We) is irradiated with a laser beam, and as shown in FIGS. 12 and 13, the surface of the first wafer W is surfaced. A plurality of split reformed layers M4 are formed in the direction perpendicular to the direction and along the radial direction of the first wafer W. In the illustrated example, the split-modifying layer M4 of the line extending in the radial direction is formed at eight locations, but if at least the lines of the split-modifying layer M4 are formed at two locations, the peripheral edge. Part We can be fragmented and removed.

The plurality of split reforming layers M4 are formed radially outward from the upper end portion (the portion reaching the back surface Wb) of the crack C1. Further, in the plurality of divided modified layers M4, the lower end portion of the crack C4 extending from the divided modified layer M4, which will be described later, is peripherally modified above the peripheral modified layer M1 and the crack C1 in the thickness direction of the first wafer W. It is formed so as to reach the layer M1 or the crack C1. For example, by controlling the radial distance for irradiating the laser beam corresponding to the thickness position of the first wafer W, the plurality of divided modified layers M4 of the present embodiment are formed. In this case, it is preferable that the lower end portion of the crack C4 does not pass through the peripheral modification layer M1 or the crack C1.

Further, since the plurality of divided modified layers M4 are removed as the peripheral portion We, the position of the lowermost divided modified layer M4 is not particularly limited. In the present embodiment, the lowermost split reforming layer M4 is formed above the final finish thickness height G.

Further, the crack C4 extends from the split reforming layer M4. On the radial outer side of the boundary Ad between the unbonded region Ae and the bonded region Ac, the upper end portion of the crack C4 reaches the back surface Wb and the lower end portion reaches the front surface Wa. On the other hand, inside the boundary Ad in the radial direction, the upper end portion of the crack C4 reaches the back surface Wb, and the lower end portion reaches the peripheral edge modification layer M1 or the crack C1. The timing of forming the crack C4 is not limited to this embodiment. For example, the crack C4 may reach the back surface Wb not when the split reforming layer M4 is formed by irradiation with a laser beam but when the peripheral edge portion We is removed. The method for removing the peripheral portion We is not particularly limited. For example, the peripheral edge portion We may be adsorbed and held and removed, or the peripheral edge portion We may be impacted to remove the peripheral edge portion We. At this time, an insertion member (for example, a wedge roller, a blade, or the like) having a sharp tip may be inserted into the interface between the peripheral edge portion We and the device layer D from the side of the polymerization wafer T.

According to the present embodiment, when the peripheral edge portion We is removed, the peripheral edge portion We is divided into a plurality of parts by the divided modified layer M4 while being separated from the annular peripheral edge modified layer M1 as a base point. Then, the peripheral portion We to be removed is fragmented and can be removed more easily.

Moreover, in the present embodiment, the split modified layer M4 is formed so that the lower end portion of the crack C4 reaches the peripheral modified layer M1 or the crack C1 above the peripheral modified layer M1 and the crack C1. In other words, the split modified layer M4 is formed over a wide area on the radial outer side of the upper end portion of the crack C1. Therefore, the peripheral portion We can be surely fragmented by the split modification layer M4.

The position where the split modified layer M4 is formed on the radial side of the peripheral modified layer M1 and the crack C1 is not limited to the above embodiment.

For example, as shown in FIG. 14, the plurality of divided modified layers M4 may be formed further outside the outermost peripheral modified layer M1 in the radial direction of the first wafer W. That is, the plurality of divided modified layers M4 may be formed radially outside the boundary Ad between the unbonded region Ae and the bonded region Ac. The position of the lowermost split reforming layer M4 is not particularly limited, but in the present embodiment, it is above the final finish thickness height G. The crack C4 extending from the split modified layer M4 reaches the front surface Wa and the back surface Wb.

In such a case, as in the above embodiment, the peripheral portion We can be easily removed by fragmenting the peripheral portion We by the split reforming layer M4. Further, in the present embodiment, since the radial distance for irradiating the laser beam may be the same in the thickness direction of the first wafer W, laser processing can be easily performed. In particular, when the radial distance between the upper end of the crack C1 and the boundary Ad is sufficiently small, the peripheral edge We can be formed even if the modified layer does not exist between the peripheral modified layer M1 and the divided modified layer M4. It can be divided appropriately.

In the examples shown in FIGS. 13 and 14 above, the crack C1 was formed in an oblique direction with respect to the surface Wa of the first wafer W, but while the crack C1 was formed in the oblique direction, the crack C1 was formed in the oblique direction. The direction of the crack C1 may be oriented perpendicular to the surface Wa of the first wafer W.

In the above embodiment, the polymerization wafer T includes the device layer D, but may be a polymerization wafer that does not include the device layer D.

In the above embodiment, in the layered wafer T in which the first wafer W and the second wafer S are joined in the wafer processing system 1, the peripheral portion of the first wafer W is removed and thinned. However, the first wafer W may not be bonded to the second wafer S.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The above embodiments may be omitted, replaced or modified in various forms without departing from the scope of the appended claims and their gist.

1 Wafer processing system 61 Internal reformer 90 Control device W 1st wafer Wa Front surface Wb Back surface Wc Central part Wd Boundary We Peripheral part M1 (1st) Peripheral reforming layer M3 2nd peripheral reforming layer

Claims

It is a substrate processing method that processes a substrate.
It includes irradiating a laser beam from the back surface side of the substrate to form a plurality of first peripheral modification layers along the boundary between the peripheral portion of the substrate to be removed and the central portion of the substrate.
The plurality of first peripheral modification layers are formed at different height positions from the radial outer side to the inner side of the substrate and from the front surface side to the back surface side inside the substrate. Substrate processing method.
The substrate processing method according to claim 1, wherein when the first peripheral modification layer is formed, the first crack extending from the adjacent first peripheral modification layer is connected.
Including irradiating the inside of the substrate with a laser beam to form a plurality of second peripheral modification layers along the boundary between the peripheral portion of the substrate to be removed and the central portion of the substrate.
The plurality of the second peripheral modification layers are formed so as to be arranged in a direction perpendicular to the surface direction of the substrate.
The second aspect of claim 2, wherein the lower end of the second crack extending from the second peripheral modification layer reaches the surface of the substrate and the upper end is connected to the lower end of the first crack. Substrate processing method.
The substrate processing method according to claim 3, wherein the upper end portion of the second crack is located on the back surface side of the final finishing thickness height of the substrate.
Including irradiating the inside of the substrate with a laser beam to form a plurality of internal surface modification layers along the surface direction of the substrate.
The third crack extending in the plane direction from the inner surface modification layer is according to any one of claims 2 to 4, wherein the radial outer end portion is connected to the upper end portion of the first crack. Substrate processing method.
The substrate processing method according to claim 5, wherein the first peripheral modification layer and the internal surface modification layer are continuously formed from the radial outer side to the inner side of the substrate.
The surface side of the substrate is bonded to another substrate to form a polymerized substrate.
The substrate processing method according to any one of claims 1 to 6, further comprising forming an unbonded region in the peripheral portion that weakens the bonding strength between the substrate and the other substrate.
A chamfered portion having a small end thickness formed in the cross-sectional view is formed on the substrate.
The surface side of the substrate is bonded to another substrate to form a polymerized substrate.
At the time of forming the first peripheral modification layer, the lower end portion of the first crack extending from the first peripheral modification layer is made to reach the radial inner end portion of the chamfered portion on the surface of the substrate. , The substrate processing method according to any one of claims 1 to 6.
Including irradiating the inside of the substrate with a laser beam to form a plurality of divided reforming layers in a direction perpendicular to the surface direction of the substrate and along the radial direction of the substrate.
The plurality of the divided and modified layers are formed radially outward from the upper end of the first crack extending from the first peripherally modified layer, and the first peripherally modified layer is formed in the thickness direction of the substrate. A claim that the lower end of the fourth crack extending from the split modified layer is formed above the layer and the first crack so as to reach the first peripheral modified layer or the first crack. Item 8. The substrate processing method according to any one of Items 1 to 8.
Including irradiating the inside of the substrate with a laser beam to form a plurality of divided reforming layers in a direction perpendicular to the surface direction of the substrate and along the radial direction of the substrate.
The invention according to any one of claims 1 to 8, wherein the plurality of the divided modified layers are formed on the outermost side of the plurality of the first peripheral modified layers in the radial direction of the substrate. Substrate processing method.
It is a substrate processing device that processes substrates.
A modified portion that irradiates a laser beam from the back surface side of the substrate to form a plurality of first peripheral modified layers along the boundary between the peripheral portion of the substrate to be removed and the central portion of the substrate.
A control unit for controlling the formation operation of the modified layer on the substrate is provided.
The control unit
The plurality of first peripheral modification layers are formed at different height positions so as to be directed from the radial outer side to the inner side of the substrate and from the front surface side to the back surface side inside the substrate. , A substrate processing device that controls the operation of the reforming unit.
The control unit
When the first peripheral modification layer is formed, the formation interval of the first peripheral modification layer is controlled so that the first cracks extending from the adjacent first peripheral modification layer are connected. The substrate processing apparatus according to claim 11.
The control unit
A plurality of second peripheral edges are arranged in a direction perpendicular to the surface direction of the substrate along the boundary between the peripheral edge portion to be removed from the substrate and the central portion of the substrate by irradiating the inside of the substrate with a laser beam. Form a modified layer,
The modified portion of the modified portion so that the lower end portion of the second crack extending from the second peripheral modification layer reaches the surface of the substrate and the upper end portion is connected to the lower end portion of the first crack. The substrate processing apparatus according to claim 12, which controls the operation.
The control unit
The substrate treatment according to claim 13, wherein the formation operation of the second peripheral modification layer is controlled so that the upper end portion of the second crack is located on the back surface side with respect to the final finish thickness height of the substrate. Device.
The control unit
A laser beam is irradiated to the inside of the substrate to form a plurality of internal surface modification layers along the surface direction of the substrate.
A claim that controls the operation of the modified portion so that the radial outer end portion of the third crack extending in the plane direction from the inner surface modified layer is connected to the upper end portion of the first crack. Item 2. The substrate processing apparatus according to any one of Items 12 to 14.
The control unit
15. The operation of the modified portion is controlled so that the first peripheral modification layer and the internal surface modification layer are continuously formed from the radial outer side to the inner side of the substrate. The substrate processing apparatus according to.
The surface side of the substrate is bonded to another substrate to form a polymerized substrate.
The substrate processing apparatus according to any one of claims 11 to 16, further comprising a second modified portion that forms an unbonded region that weakens the bonding strength between the substrate and the other substrate at the peripheral edge portion.
A chamfered portion having a small end thickness formed in the cross-sectional view is formed on the substrate.
The surface side of the substrate is bonded to another substrate to form a polymerized substrate.
The control unit
At the time of forming the first peripheral modification layer, the lower end portion of the first crack extending from the first peripheral modification layer is made to reach the radial inner end portion of the chamfered portion on the surface of the substrate. The substrate processing apparatus according to any one of claims 11 to 16, wherein the operation of forming the first peripheral modification layer is controlled as described above.
The control unit
By irradiating the inside of the substrate with a laser beam, a plurality of divided and modified layers are formed in a direction perpendicular to the surface direction of the substrate and along the radial direction of the substrate.
A plurality of the divided modified layers are formed radially outward from the upper end of the first crack extending from the first peripheral modified layer, and the first peripheral modified layer is formed in the thickness direction of the substrate. Above the layer and the first crack, the lower end of the fourth crack extending from the split modified layer is formed to reach the first peripheral modified layer or the first crack. The substrate processing apparatus according to any one of claims 11 to 18, which controls the operation of the reforming unit.
The control unit
By irradiating the inside of the substrate with a laser beam, a plurality of divided and modified layers are formed in a direction perpendicular to the surface direction of the substrate and along the radial direction of the substrate.
11. The operation of the reforming portion, wherein the plurality of divided reforming layers are formed on the outermost side of the plurality of first peripheral modification layers in the radial direction of the substrate, and the operation of the reforming portion is controlled. The substrate processing apparatus according to any one of 18 to 18.