Substrate processing apparatus and substrate processing method

Abstract

A substrate processing apparatus processes an overlapping substrate formed by stacking a first substrate, an interface layer, and a second substrate, wherein the interface layer includes at least a laser absorption film and a release facilitating film. The substrate processing apparatus comprises: a substrate holding section for holding the overlapping substrate; an interface laser irradiation section for irradiating the laser absorption film with laser pulses; a moving mechanism for moving the substrate holding section and the interface laser irradiation section relative to each other; and a control section for controlling the interface laser irradiation section and the moving mechanism, wherein the control section performs the following control: selecting a position of the peel surface between the first substrate and the second substrate from one of the following: between the first substrate and the laser absorption film, and between the release facilitating film and the second substrate, based on the thickness of the laser absorption film.

Description

Technical Field

[0001] This disclosure relates to a substrate processing apparatus and a substrate processing method. Background Technology

[0002] Patent Document 1 discloses a substrate processing system comprising: a modification layer forming apparatus that forms a modification layer inside a first substrate in an overlapping substrate formed by bonding a first substrate and a second substrate, along the boundary between the peripheral and central portions of the first substrate to be removed; and a peripheral removal apparatus that removes the peripheral portion of the first substrate using the modification layer as a base point. Furthermore, Patent Document 1 describes forming a modification surface inside a device layer formed on a non-processed surface of the first substrate to reduce the bonding force between the first and second substrates at the peripheral portion of the first substrate.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2019 / 176589 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] The technology disclosed herein involves properly separating the first substrate from the second substrate in an overlapping substrate formed by bonding the first substrate and the second substrate.

[0008] Solution for solving the problem

[0009] One aspect of this disclosure is a substrate processing apparatus for processing an overlapping substrate formed by stacking a first substrate, an interface layer, and a second substrate, wherein the interface layer includes at least a laser absorption film and a release facilitating film. The substrate processing apparatus includes: a substrate holding section for holding the overlapping substrate; an interface laser irradiation section for irradiating the laser absorption film with laser pulses; a moving mechanism for moving the substrate holding section and the interface laser irradiation section relative to each other; and a control section for controlling the interface laser irradiation section and the moving mechanism, wherein the control section performs the following control: selecting a position of the peel surface between the first substrate and the second substrate from one of the areas between the first substrate and the laser absorption film, and between the release facilitating film and the second substrate, based on the thickness of the laser absorption film.

[0010] The effects of the invention

[0011] According to this disclosure, the first substrate can be properly peeled from the second substrate in an overlapping substrate formed by bonding the first substrate and the second substrate. Attached Figure Description

[0012] Figure 1A This is a side view showing an example of the structure of the superimposed wafer involved in the embodiment.

[0013] Figure 1B This is a side view illustrating other structural examples of the overlapping wafer involved in the embodiment.

[0014] Figure 2 This is a top view showing an outline of the structure of the wafer processing system according to this embodiment.

[0015] Figure 3 This is a side view showing an outline of the structure of the interface modification device.

[0016] Figure 4 This is an explanatory diagram showing the main wafer processing steps in a wafer processing system.

[0017] Figure 5 This is an explanatory diagram showing the situation of overlapping wafers that have been irradiated by a laser.

[0018] Figure 6 This is an explanatory diagram showing the location of the peeling surface of the first wafer.

[0019] Figure 7 This is a table showing the correlation between the thickness of the laser absorption film and the laser irradiation interval and the position of the peeling surface of the first wafer.

[0020] Figure 8 This is a flowchart illustrating the main wafer processing steps involved in the implementation method.

[0021] Figure 9 It is a graph showing the tendency of the relationship between the thickness of the laser absorption film and the pulse energy of the laser.

[0022] Figure 10 This is an explanatory diagram showing the main wafer processing steps in the wafer processing system.

[0023] Figure 11 This is an explanatory diagram showing the main wafer processing steps in the wafer processing system. Detailed Implementation

[0024] In the manufacturing process of semiconductor devices, sometimes the periphery of the first substrate is removed from an overlapping substrate formed by bonding a first substrate (a silicon substrate such as a semiconductor substrate) on which multiple electronic circuits and other devices are formed on its surface with a second substrate. This process is known as edge trimming.

[0025] Edge trimming of the first substrate is performed, for example, using the substrate processing system disclosed in Patent Document 1. Specifically, a modified layer is formed by irradiating the interior of the first substrate with a laser, and the peripheral portion is removed from the first substrate using this modified layer as a base point. Furthermore, according to the substrate processing system described in Patent Document 1, a modified surface is formed by irradiating the interface where the first and second substrates are joined with a laser, thereby reducing the bonding force between the first and second substrates in the peripheral portion.

[0026] Furthermore, in this edge trimming process, sometimes a laser is irradiated onto a laser-absorbing layer (e.g., an oxide film) formed between the first and second substrates to create a peel at the interface between the first and second substrates. However, when the laser is irradiated onto the laser-absorbing layer to trim the edge of the first substrate, if the thickness of the laser-absorbing layer is small, the energy absorbed and stored by the absorption layer through laser irradiation is small, and therefore the edge trimming of the first substrate may not be performed properly.

[0027] The technology disclosed herein was developed in view of the above circumstances, and in an overlapping substrate formed by bonding a first substrate and a second substrate, the first substrate is appropriately peeled from the second substrate. Hereinafter, a substrate processing system and substrate processing method, which are substrate processing apparatuses according to this embodiment, will be described with reference to the accompanying drawings. Furthermore, in this specification and the accompanying drawings, elements having substantially the same functional structure are labeled with the same reference numerals, thereby omitting repeated descriptions.

[0028] In the wafer processing system 1 described later in this embodiment, as... Figure 1A As shown, a superimposed wafer T, which is formed by bonding a first wafer W (serving as a first substrate) and a second wafer S (serving as a second substrate), is processed. Hereinafter, in the first wafer W, the surface bonded to the second wafer S is referred to as surface Wa, and the surface opposite to surface Wa is referred to as back surface Wb. Similarly, in the second wafer S, the surface bonded to the first wafer W is referred to as surface Sa, and the surface opposite to surface Sa is referred to as back surface Sb.

[0029] The first wafer W is, for example, a semiconductor wafer such as a silicon substrate, and a device layer (not shown) including multiple devices is formed on the surface Wa side. A laser absorption film Fw as a laser absorption film, a metal film Fm as a lift-off promoting film, and a surface film Fe are also stacked on the surface Wa side of the first wafer W. This surface film Fe is bonded to the surface film Fs of the second wafer S. The laser absorption film Fw is, for example, an oxide film (SiO2 film, TEOS film) capable of absorbing laser light from the laser irradiation system 110 described later. The metal film Fm is, for example, a tungsten film, with a adhesion strength to the surface film Fe that is at least weaker than the adhesion strength between the first wafer W and the laser absorption film Fw. Furthermore, the peripheral portion We of the first wafer W is the portion to be removed during edge trimming described later, for example, a radial range of 0.5 mm to 3 mm from the outer end of the first wafer W. The surface film Fe is, for example, an oxide film (THOX film, SiO2 film, TEOS film), a SiC film, a SiCN film, or an adhesive.

[0030] The second wafer S is, for example, a wafer that supports the first wafer W. A surface film Fs is formed on the surface Sa of the second wafer S. Examples of surface films Fs include oxide films (THOX films, SiO2 films, TEOS films), SiC films, SiCN films, or adhesives. Furthermore, the second wafer S functions as a protective element (auxiliary wafer) that protects the device layer of the first wafer W. Alternatively, the second wafer S does not need to be an auxiliary wafer; it can also be a device wafer with a device layer (not shown) formed, similar to the first wafer W.

[0031] Furthermore, in the superimposed wafer T involved in this embodiment, the laser absorption film Fw, the metal film Fm, the surface film Fe, and the surface film Fs are equivalent to the "interface layer" involved in the technology disclosed herein.

[0032] Furthermore, the following describes the process in wafer processing system 1. Figure 1A The example shown is a case where a superimposed wafer T, on which a laser absorption film Fw, a metal film Fm, a surface film Fe, and a surface film Fs are stacked at the interface between the first wafer W and the second wafer S, is processed. However, the structure of the superimposed wafer T processed by the wafer processing system 1 is not limited to this.

[0033] For example, in wafer processing system 1, such as Figure 1BAs shown, a superimposed wafer T2, on which a surface film Fm2, serving as a second lift-off promoting film, is formed at the interface between the surface Wa of the first wafer W and the laser absorption film Fw, can be processed. As the surface film Fm2, a film (e.g., a SiN film) with an adhesion force to the surface Wa of the first wafer W that is at least smaller than that to the laser absorption film Fw, and which allows laser light from the laser irradiation system 110 described later to pass through, can be used. Furthermore, at this time, the adhesion force between the metal film Fm and the surface film Fe is smaller than the adhesion force between the surface Wa of the first wafer W and the surface film Fm2.

[0034] like Figure 2 As shown, the wafer processing system 1 has a structure that integrates the loading / unloading station 2 and the processing station 3. For example, a cassette C capable of accommodating multiple overlapping wafers T is used to load and unload between the loading / unloading station 2 and the outside. The processing station 3 is equipped with various processing devices for performing desired processing on the overlapping wafers T.

[0035] The loading / unloading station 2 is equipped with a cassette stage 10 for holding cassettes C capable of accommodating multiple overlapping wafers T. Furthermore, a wafer transport device 20 is disposed adjacent to the cassette stage 10 on the positive X-axis side. The wafer transport device 20 is configured to move along a transport path 21 extending in the Y-axis direction to transport overlapping wafers T between the cassettes C of the cassette stage 10 and the transport device 30 described later.

[0036] On the positive X-axis direction side of the wafer transfer device 20 at the transfer station 2, a transfer device 30 for transferring overlapping wafers T between the wafer transfer device 20 and the processing station 3 is provided adjacent to the wafer transfer device 20.

[0037] The processing station 3 is equipped with a wafer transport device 40, a peripheral removal device 50 as a peripheral removal section, a cleaning device 60, an interface modification device 70 as an interface laser irradiation section, and an internal modification device 80 as an internal laser irradiation section.

[0038] The wafer transport device 40 is disposed on the positive X-axis side of the transport device 30. The wafer transport device 40 is configured to move freely on the transport path 41 extending along the X-axis direction, and is configured to transport overlapping wafers T to the transport device 30, peripheral removal device 50, cleaning device 60, interface modification device 70 and internal modification device 80 of the transport station 2.

[0039] Peripheral removal device 50 removes the peripheral portion We of the first wafer W, i.e., edge trimming. Cleaning device 60 cleans the exposed surface of the edge-trimmed second wafer S to remove particles from the exposed surface. Interface modification device 70 irradiates the interface between the first wafer W and the second wafer S with a laser (interface laser, such as a CO2 laser) to form the unbonded region Ae, which will be described later. The detailed structure of interface modification device 70 will be described later. Internal modification device 80 irradiates the interior of the first wafer W with a laser (internal laser, such as a YAG laser) to form a peripheral modification layer M1, which serves as the basis for the peeling of the peripheral portion We, and a segmentation modification layer M2, which serves as the basis for the fragmentation of the peripheral portion We.

[0040] The wafer processing system 1 described above is equipped with a control device 90, which serves as a control unit. The control device 90 is, for example, a computer, and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of the overlapping wafers T in the wafer processing system 1. Additionally, the program storage unit also stores a program for controlling the operation of the drive systems of the various processing devices, transport devices, etc., described above to implement the wafer processing described later in the wafer processing system 1. Furthermore, the above-mentioned program can be recorded in a computer-readable storage medium H and installed from the storage medium H onto the control device 90.

[0041] Next, the detailed structure of the interface modification device 70 described above will be explained.

[0042] like Figure 3 As shown, the interface modification apparatus 70 has a holding disk 100, which serves as a substrate holding portion, holding the overlapping wafer T via its upper surface. The holding disk 100 adsorbs and holds the back side Sb of the second wafer S.

[0043] The holding plate 100 is supported on the sliding table 102 via an air bearing 101. A rotating mechanism 103 is provided on the lower surface of the sliding table 102. The rotating mechanism 103 may have a built-in motor as a drive source. The holding plate 100 is configured to rotate freely about the θ axis (vertical axis) via the air bearing 101 through the rotating mechanism 103. The sliding table 102 is configured to move along a guide rail 105 extending in the Y-axis direction via a horizontal moving mechanism 104 provided on its lower surface. The guide rail 105 is provided on the base 106. Furthermore, there is no particular limitation on the drive source of the horizontal moving mechanism 104; for example, a linear motor can be used. In this embodiment, the rotating mechanism 103 and the horizontal moving mechanism 104 described above correspond to the "moving mechanism" involved in the present disclosure.

[0044] A laser irradiation system 110 is provided above the holding plate 100. The laser irradiation system 110 has a laser head 111 and a lens 112. The lens 112 can be configured to be raised and lowered freely by a lifting mechanism (not shown).

[0045] The laser head 111 has a laser oscillator (not shown) that oscillates to produce pulsed laser light. That is, the laser light irradiating the superimposed wafer T held on the holding disk 100 from the laser irradiation system 110 is a so-called pulsed laser, with power repetitions of 0 (zero) and a maximum value. Furthermore, in this embodiment, the laser is a CO2 laser, and the wavelength of the CO2 laser is, for example, 8.9 μm to 11 μm. In addition, the laser head 111 may include devices other than a laser oscillator, such as an amplifier.

[0046] Lens 112 is a cylindrical component that irradiates the superimposed wafer T held in the holding disk 100 with laser light. The laser light emitted from the laser irradiation system 110 passes through the first wafer W and is irradiated by the laser absorption film Fw and absorbed.

[0047] Next, the wafer processing performed using the wafer processing system 1 configured as described above will be explained. Furthermore, in this embodiment, as described above, the case of peeling the peripheral portion We of the first wafer W from the second wafer S in the wafer processing system 1 (so-called edge trimming) will be explained as an example. In addition, in this embodiment, the first wafer W and the second wafer S are bonded in a bonding device (not shown) outside the wafer processing system 1 to pre-form an overlapping wafer T.

[0048] First, the box C containing multiple overlapping wafers T is placed on the box placement stage 10 of the loading / unloading station 2.

[0049] Next, the overlapping wafer T in box C is removed by wafer transfer device 20 and transferred to internal modification device 80 via transfer device 30 through wafer transfer device 40. In internal modification device 80, as... Figure 4 As shown in (a), a laser is irradiated into the interior of the first wafer W to form a perimeter modification layer M1 and a segmentation modification layer M2. The perimeter modification layer M1 serves as the base point for removing the perimeter portion We during edge trimming, which will be described later. The segmentation modification layer M2 serves as the base point for fragmentation of the removed perimeter portion We. Furthermore, in the accompanying drawings used in the following description, illustrations of the segmentation modification layer M2 are sometimes omitted to avoid complicating the drawings.

[0050] Next, the overlapping wafer T, on which a peripheral modification layer M1 and a partition modification layer M2 are formed inside the first wafer W, is transported to the interface modification apparatus 70 using the wafer transport device 40. In the interface modification apparatus 70, while the overlapping wafer T (first wafer W) is rotated and moved along the Y-axis, laser pulses are applied to the interface between the first wafer W and the second wafer S at the peripheral portion We (more specifically, the aforementioned laser absorption film Fw formed at this interface). Thus, as... Figure 4As shown in (b), a stripping occurs at the interface between the first wafer W and the second wafer S.

[0051] In the interface modification apparatus 70, an unbonded region Ae with reduced bonding strength between the first wafer W and the second wafer S is formed by peeling at the interface between the first wafer W and the second wafer S, as shown in this manner. Thus, as... Figure 5 As shown, an annular unbonded region Ae is formed at the interface between the first wafer W and the second wafer S, and a bonding region Ac, formed after the first wafer W and the second wafer S are bonded, is formed radially inside the unbonded region Ae. In the edge trimming described later, the peripheral portion We of the first wafer W, which is the object of removal, needs to be removed. The presence of the unbonded region Ae in this way allows for the appropriate removal of the peripheral portion We.

[0052] Furthermore, the detailed method for forming the unbonded region Ae in the interface modification device 70 will be described later.

[0053] Next, the overlapping wafer T with the unbonded region Ae formed is transported to the peripheral removal device 50 using the wafer transport device 40. In the peripheral removal device 50, as... Figure 4 As shown in (c), the peripheral portion We of the first wafer W is removed, i.e., edge trimming. At this time, the peripheral portion We is peeled off from the center of the first wafer W with the peripheral modification layer M1 as the base point, and completely peeled off from the second wafer S with the unbonded region Ae as the base point. In addition, the peripheral portion We that has been removed at this time is fragmented with the dividing modification layer M2 as the base point.

[0054] When removing the peripheral portion We, a blade, for example, formed in a wedge shape, can be inserted at the interface between the first wafer W and the second wafer S forming the overlapping wafer T. Alternatively, the peripheral portion We can be removed by applying pressure, for example, by jetting air or a water jet. In this way, during edge trimming, the peripheral portion We is peeled off with the peripheral modification layer M1 as the base point by impacting the peripheral portion We of the first wafer W. Furthermore, as described above, the bonding strength between the first wafer W and the second wafer S is reduced by the unbonded region Ae, thus the peripheral portion We is properly removed from the second wafer S.

[0055] Next, the overlapping wafer T, with the peripheral portion We of the first wafer W removed, is transferred to the cleaning apparatus 60 using the wafer transfer device 40. In the cleaning apparatus 60, as... Figure 4 As shown in (d), the periphery (hereinafter, sometimes referred to as the "exposed surface" after edge trimming) of the second wafer S, to which the periphery We has been removed, is cleaned.

[0056] In the cleaning apparatus 60, for example, the exposed surface of the second wafer S is irradiated with a cleaning laser (e.g., a CO2 laser) to modify and remove the surface of the exposed surface, thereby removing (cleaning) particles and the like remaining on the exposed surface. For example, the exposed surface can be rotated and cleaned by supplying cleaning fluid to the exposed surface of the second wafer S while rotating the overlapping wafer T.

[0057] In addition, the cleaning apparatus 60 can clean the exposed surface of the second wafer S and the back surface Sb of the second wafer S.

[0058] Then, the fully processed overlapping wafer T is transferred from the wafer transfer device 20 to the cassette C of the cassette stage 10 via the transfer device 30. In this way, a series of wafer processing steps in the wafer processing system 1 are completed.

[0059] Furthermore, in the above explanation, in cases such as Figure 4 (a) and Figure 4 As shown in (b), after the peripheral modification layer M1 and the partition modification layer M2 are formed by the internal modification device 80, the unbonded region Ae is formed by the interface modification device 70. However, the order of wafer processing in the wafer processing system 1 is not limited to this. That is, it is also possible that after the unbonded region Ae is formed by the interface modification device 70, the peripheral modification layer M1 and the partition modification layer M2 are formed by the internal modification device 80.

[0060] Here, in the interface modification apparatus 70, a laser is irradiated from the laser irradiation system 110 onto the laser absorption film Fw formed at the interface between the first wafer W and the second wafer S. The irradiated laser is absorbed by the laser absorption film Fw. At this time, the laser absorption film Fw stores energy due to the absorption of the laser, and therefore its temperature rises and it expands. As a result, due to the expansion of the laser absorption film Fw, the interface between the first wafer W and the laser absorption film Fw (at... Figure 1B In the superimposed wafer T2 shown, shear force is generated at the interface between the first wafer W (where the adhesion force is weak) and the surface film Fm2, resulting in peeling at the interface between the first wafer W and the laser absorption film Fw (surface film Fm2). That is, at the laser irradiation position, an unbonded region Ae with reduced adhesion force between the first wafer W and the second wafer S is formed by peeling.

[0061] Typically, in the interface modification apparatus 70, an unbonded region Ae is formed at the interface between the laser absorption film Fw (surface film Fm2) and the first wafer W. As described above, when the thickness of the laser absorption film Fw is small, the energy absorbed and stored by the laser absorption film Fw is smaller. That is, the expansion of the laser absorption film Fw is reduced, and therefore the shear stress generated at the interface between the first wafer W and the laser absorption film Fw (surface film Fm2) is smaller. As a result, the interface between the first wafer W and the laser absorption film Fw (surface film Fm2) cannot be properly peeled off, and the unbonded region Ae may not be properly formed.

[0062] Regarding this point, in this embodiment, as shown in FIG1, a metal film Fm serving as a lift-off promoting film is formed at the interface between the first wafer W and the second wafer S. As this metal film Fm, a film with a adhesion strength between the metal film Fm and the surface film Fe is used that is at least weaker than the adhesion strength between the first wafer W and the laser absorption film Fw (surface film Fm2). Furthermore, in the following description, the interface between the first wafer W and the laser absorption film Fw (… Figure 1B The interface between the first wafer W and the surface film Fm2 in the superimposed wafer T2 is called "interface A", and the interface between the metal film Fm and the surface film Fe is called "interface B" (refer to...). Figure 6 ).

[0063] Therefore, in this embodiment, even when the thickness of the laser absorption film Fw is small, resulting in low shear stress at interface A due to laser irradiation, peeling can still occur at interface B, where the adhesion is weak, to form an unbonded region Ae. Specifically, even when the shear stress generated by the expansion of the laser absorption film Fw is insufficient for peeling at interface A, the stress required for peeling at interface B can be achieved. As a result, the unbonded region Ae can be formed at interface B instead of interface A.

[0064] In other words, in this embodiment, even when the thickness of the conventional laser absorption film Fw is small, making it difficult to properly peel the first wafer W from the second wafer S, the peeling (edge ​​trimming) of the first wafer W can still be performed appropriately.

[0065] However, on the other hand, even if a metal film Fm is formed at the interface between the first wafer W and the second wafer S as shown in Figure 1, if the thickness of the laser absorption film Fw is large, when laser irradiation is performed under the same conditions as when the thickness of the laser absorption film Fw is small, it may be impossible to properly form the unbonded region Ae at the B interface. Specifically, if the thickness of the laser absorption film Fw is large, the energy generated by irradiating the laser cannot reach the interface on the side opposite to the incident surface of the laser, i.e., the metal film Fm side. As a result, the shear stress required for peeling off the B interface may not be generated.

[0066] That is, for example, when multiple overlapping wafers T are irradiated with laser under the same processing conditions, if the thickness of the laser absorption film Fw of each overlapping wafer T is different, the edge trimming may not be properly performed in the overlapping wafer T with a larger laser absorption film Fw, resulting in a decrease in yield.

[0067] Therefore, after careful study, the inventors of this invention have learned that by controlling the irradiation interval (pulse spacing P) of the laser in the circumferential direction and the irradiation interval (index spacing Q) of the laser in the radial direction targeting the laser absorption film Fw (see reference) Figure 5 The pulse spacing P and index spacing Q are sometimes referred to together as the "irradiation interval". This selectively determines the location of the peeling surface (the formation location of the unbonded region Ae) between the first wafer W and the second wafer S.

[0068] Specifically, it is understood that: Figure 7 As shown, when the laser irradiation interval targeting the laser absorption film Fw is reduced, peeling occurs at the interface (interface A) between the first wafer W and the laser absorption film Fw (surface film Fm2). When the laser irradiation interval is increased, peeling occurs at the interface (interface B) between the metal film Fm and the surface film Fe. Furthermore, in the following description, as... Figure 7 As shown, the irradiation interval that produces peeling at interface A is sometimes called the "A interface peeling interval", and the irradiation interval that produces peeling at interface B is called the "B interface peeling interval".

[0069] Furthermore, the inventors of this invention have learned that the laser irradiation interval (hereinafter referred to as "switching gap Pq") that switches the position of the peeling surface between the first wafer W and the second wafer S between interface A and interface B varies according to the thickness of the laser absorption film Fw. Specifically, it has been learned that: Figure 7 As shown, the conversion gap Pq increases with the thickness of the laser absorption film Fw. Furthermore, the inventors of this invention have learned that as the thickness of the laser absorption film Fw increases (in... Figure 7In the example above 700nm, peeling does not occur at interface B, but only at interface A.

[0070] Therefore, the method for forming an unbonded region Ae at the interface between the first wafer W and the second wafer S by means of the interface modification apparatus 70 based on the above insights will be described next.

[0071] When forming the unbonded region Ae using the interface modification device 70, firstly, the thickness of the laser absorption film Fw is obtained from the layer information of the overlapping wafer T, which is the object to be formed of the unbonded region Ae. Figure 8 (Step E1). The obtained layer information of the overlapping wafer T is output to the control device 90.

[0072] The layer information of the overlapping wafer T can be obtained through the interface modification device 70, or it can be obtained in advance outside the interface modification device 70.

[0073] Furthermore, there are no particular limitations on the method for obtaining layer information of the superimposed wafer T. For example, it can be measured by sensors or obtained by photographing the superimposed wafer T using a camera.

[0074] Furthermore, the layer information obtained for the overlapping wafer T is not limited to the thickness information of the laser absorption film Fw. In addition, the thickness of the device layer (not shown), the surface shape tendency of the first wafer W and the second wafer S (e.g., whether it is convex or concave) can also be obtained.

[0075] Once the layer information (thickness information of the laser absorption film Fw) of the overlapping wafer T is obtained, then from... Figure 6 In the interfaces A and B shown, select the location of the peeling surface between the first wafer W and the second wafer S. Figure 8 (Step E2). Specifically, the decision can be made, for example, based on the layer information of the overlapping wafer T obtained in step E1, or it can be determined according to the purpose of wafer processing. In addition, when the peeling surface position is determined based on the layer information of the overlapping wafer T, it can be determined manually as appropriate based on the obtained layer information, or the desired thickness of the laser absorption film Fw can be automatically determined as a threshold.

[0076] After selecting the peeling surface position between the first wafer W and the second wafer S, the irradiation interval (pulse spacing P and index spacing Q) of the laser irradiation system 110 on the laser absorption film Fw is then determined. Figure 8 Step E3).

[0077] like Figure 7As shown, in the overlapping wafer T, when the laser irradiation interval is less than or equal to the transition pitch Pq (A interface peeling pitch), an unbonded region Ae is formed at the A interface; when the laser irradiation interval is greater than or equal to the transition pitch Pq (B interface peeling pitch), an unbonded region Ae is formed at the B interface. In other words, the position of the peeling surface from the second wafer S changes according to the laser irradiation interval. Furthermore, the transition pitch Pq that switches the position of the peeling surface increases as the thickness of the laser absorption film Fw formed on the surface Wa side of the first wafer W increases.

[0078] Therefore, in this embodiment, the irradiation interval of the laser irradiating the laser absorption film Fw is determined based on the layer information (thickness of the laser absorption film Fw) of the overlapping wafer T obtained in step E1 and the peeling surface position selected in step E2. Specifically, when the first wafer W is peeled off at interface A in step E2, the irradiation interval is determined to be within the A interface peeling interval that is less than or equal to the conversion pitch Pq. When the first wafer W is peeled off at interface B, the irradiation interval is determined to be within the B interface peeling interval that is greater than or equal to the conversion pitch Pq.

[0079] In addition, regarding Figure 7 The relationship between the thickness of the laser absorption film Fw and the laser irradiation interval and the position of the peeling surface of the first wafer W is expected to be obtained in advance before the wafer processing in the wafer processing system 1 begins and output to the control device 90.

[0080] Here, as mentioned above, the location of the peeling surface of the first wafer W is designated as interface A when it is below the transition pitch Pq, and as interface B when it is above the transition pitch Pq. In other words, the laser irradiation interval for peeling the first wafer W at interface A or interface B can be arbitrarily selected as long as it falls within the range of the peeling pitch at interface A and interface B.

[0081] Therefore, when determining the laser irradiation interval in step E3, the production capacity of the interface modification apparatus 70 can be improved by determining the laser irradiation interval by, for example, the larger of the A-interface peeling interval and the B-interface peeling interval. Furthermore, by appropriately selecting the laser irradiation interval between the A-interface peeling interval and the B-interface peeling interval, the production capacity of the interface modification apparatus 70 can be arbitrarily controlled, for example, making it easier to achieve compatibility between the interface modification apparatus 70 and other external processing devices.

[0082] Furthermore, as described above, when the laser irradiation interval is increased, the peeling surface of the first wafer W tends to become the interface (B interface) between the metal film Fm and the surface film Fe. From this point of view, if it is determined that the first wafer W can be peeled off at the B interface based on the thickness of the laser absorption film Fw obtained in step E1, the peeling surface of the first wafer W can be determined to be the B interface, thereby improving the production capacity of the interface modification apparatus 70.

[0083] Once the laser irradiation interval is determined, the laser is irradiated onto the laser absorption film Fw of the overlapping wafer T held on the holding disk 100 in a manner consistent with the determined irradiation interval. Figure 8 Step E4). Specifically, the frequency of the laser and the rotational speed of the holding disk 100 (overlapping wafer T) are controlled to irradiate the laser at a determined pulse interval P, and the moving speed of the holding disk 100 (overlapping wafer T) in the Y-axis direction is controlled to irradiate the laser at a determined index interval Q.

[0084] Subsequently, the laser irradiates the entire surface of the laser absorption film Fw on the peripheral portion We, which is the object to be removed, and when an unbonded region Ae is formed, the series of wafer processing in the interface modification apparatus 70 ends.

[0085] According to this embodiment, when removing the peripheral portion We of the first wafer W (edge ​​trimming), a laser is irradiated onto the laser absorption film Fw formed at the interface between the first wafer W and the second wafer S to form an unbonded region Ae, thereby reducing the bonding force at the interface between the first wafer W and the second wafer S. At this time, since a metal film Fm is formed at the interface between the first wafer W and the second wafer S with a weaker adhesion force to the surface film Fe than to the adhesion force between the first wafer W and the laser absorption film Fw, even if it is difficult to peel off the peripheral portion We at the interface (interface A) between the first wafer W and the laser absorption film Fw, the peripheral portion We can be appropriately peeled off at the interface (interface B) between the metal film Fm and the surface film Fe.

[0086] Furthermore, according to this embodiment, the irradiation interval (pulse spacing P and index spacing Q) of the laser irradiating the laser absorption film Fw is controlled according to the thickness of the laser absorption film Fw, thereby selectively determining whether the first wafer W is peeled off at the aforementioned A interface or B interface. Thus, even if a thickness deviation of the laser absorption film Fw occurs between multiple overlapping wafers T processed by the interface modification apparatus 70, the peripheral portion We of the first wafer W can be appropriately removed in each overlapping wafer T. In particular, according to this embodiment, even if the thickness of the laser absorption film Fw is small, making it difficult to peel off the peripheral portion We at the A interface as in the past, the peripheral portion We can be appropriately peeled off at the B interface.

[0087] Furthermore, according to this embodiment, edge trimming of the first wafer W can be performed with a substantially fixed pulse energy, regardless of the thickness of the laser absorption film Fw formed at the interface of the overlapping wafer T.

[0088] Specifically, such as Figure 9 As shown in the comparative example, in a conventional superimposed wafer T where no metal film Fm is formed at the interface, when the thickness of the laser absorption film Fw is small, the volume of absorbed pulse energy is small and the energy absorption efficiency is low, thus increasing the pulse energy required for peeling. In other words, the energy control involved in the peeling of the first wafer W (formation of the unbonded region Ae) becomes more complex and has room for improvement from the viewpoint of energy efficiency.

[0089] Regarding this point, based on the overlapping wafers T and T2 involved in this embodiment where a metal film Fm is formed at the interface, such as Figure 9 As shown, the first wafer W can be peeled off (forming the unbonded region Ae) with a substantially fixed pulse energy, regardless of the thickness of the laser absorption film Fw. In other words, according to this embodiment, the first wafer W can be peeled off (forming the unbonded region Ae) with highly energy-efficient and simple control.

[0090] Furthermore, according to this embodiment, as described above, the irradiation interval of the laser for the purpose of peeling off the first wafer W at interface A or interface B can be arbitrarily determined between the peeling interval at interface A and the peeling interval at interface B, thereby enabling appropriate control of the production capacity in the interface modification apparatus 70.

[0091] Specifically, for example, laser irradiation is performed with the widest irradiation interval between the A interface peeling spacing and the B interface peeling spacing, thereby maximizing the production capacity of the interface modification device 70.

[0092] Furthermore, for example, by irradiating the laser at any interval between the A-interface peeling spacing and the B-interface peeling spacing, the laser processing time in the interface modification apparatus 70 can be adjusted to the laser processing time required by the wafer processing system 1, thereby easily matching the production rhythm with other processing apparatuses. In other words, wafer processing in the entire wafer processing system 1 can be optimized, that is, the overall production capacity of the wafer processing system 1 can be improved.

[0093] Furthermore, in the above embodiment, the irradiation interval of the laser on the laser absorption film Fw is determined based on the thickness of the laser absorption film Fw formed at the interface of the overlapping wafer T. However, alternatively, if it is necessary to control the irradiation interval of the laser in the interface modification apparatus 70 with a desired laser irradiation interval, the thickness of the laser absorption film Fw can be determined based on the irradiation interval to form the overlapping wafer T.

[0094] Similarly, if there are requirements regarding the position of the separation surface between the first wafer W and the second wafer S, depending on the purpose of wafer processing, the thickness of the laser absorption film Fw can be determined based on the required separation surface position to form an overlapping wafer T.

[0095] Furthermore, in the above embodiments, the example described is that the laser absorption film Fw at the position corresponding to the peripheral portion We is irradiated with laser in order to remove the peripheral portion We of the first wafer W, i.e., edge trimming. However, the wafer processing performed in the wafer processing system 1 is not limited to edge trimming.

[0096] For example, such as Figure 10 As shown, an inner surface modification layer M3 is formed inside the first wafer W as a thinning base point of the first wafer W. When the peripheral portion We is integrally removed from the back side Wb side of the first wafer W, the technology involved in this disclosure can also be applied.

[0097] Specifically, such as Figure 10 As shown in (a), a peripheral modification layer M1 and an internal surface modification layer M3 are sequentially formed in the internal modification device 80. Then, an unbonded region Ae is further formed in the interface modification device 70 at a position corresponding to the peripheral portion We. Thus, as... Figure 10 As shown in (b), the first wafer W is thinned with the inner surface modification layer M3 as the base point, and the peripheral portion We is integrally peeled off and removed with the peripheral modification layer M1 and the unbonded region Ae as the base points.

[0098] In this case, by forming a metal film Fm at the interface between the first wafer W and the second wafer S as described above, and by controlling the irradiation interval of the laser targeting the laser absorption film Fw, the peeling surface position of the peripheral portion We can be appropriately selected from interfaces A and B. In other words, regardless of the thickness of the laser absorption film Fw, the first wafer W can be appropriately peeled from the second wafer S.

[0099] In addition, for example, Figure 11 As shown, the technology disclosed herein can also be applied when the entire surface of the first wafer W is peeled off from the second wafer S and a device layer (not shown) formed on the surface Wa side of the first wafer W is transferred to the second wafer S, i.e., when a so-called laser peeling is performed.

[0100] Specifically, such as Figure 11 As shown in (a), in the interface modification apparatus 70, a laser is irradiated onto the laser absorption film Fw on the entire surface of the overlapping wafer T to form an unbonded region Ae. Consequently, the bonding force between the first wafer W and the second wafer S decreases across the entire surface of the overlapping wafer T, as... Figure 11 As shown in (b), the first wafer W can be properly separated from the second wafer S.

[0101] Furthermore, even in this case, by forming a metal film Fm at the interface between the first wafer W and the second wafer S as described above, and by controlling the irradiation interval of the laser targeting the laser absorption film Fw, the peeling surface position of the first wafer W can be appropriately selected from interfaces A and B. In other words, regardless of the thickness of the laser absorption film Fw, the first wafer W can be appropriately peeled from the second wafer S.

[0102] Furthermore, in the above embodiments, the case where the peeling promoting film formed at the interface between the first wafer W and the second wafer S is a metal film Fm (e.g., a tungsten film) was described as an example, but the type of peeling promoting film is not limited to this.

[0103] Specifically, the adhesion force between the surface film Fe (or the laser absorption film Fw) and the laser absorption film Fw should be different from that between the first wafer W and the laser absorption film Fw, so that the position of the peeling surface can be selected when the laser absorption film Fw is irradiated with laser.

[0104] Furthermore, the location of the release-promoting film is not limited to the example shown in Figure 1, i.e., between the laser absorption film Fw and the surface film Fe. For example, it can be formed between the surface Wa of the first wafer W and the laser absorption film Fw. In this case, the release-promoting film needs to be permeable to the laser light from the laser irradiation system 110.

[0105] Furthermore, in the above embodiments, such as Figure 4As shown, after the periphery modification layer M1 and the partition modification layer M2 are formed inside the first wafer W, an unbonded region Ae is formed at the interface between the first wafer W and the second wafer S. However, the order of wafer processing in the wafer processing system 1 is not limited to this. That is, it is also possible that after the unbonded region Ae is formed at the interface between the first wafer W and the second wafer S as described above, the periphery modification layer M1 and the partition modification layer M2 are formed inside the first wafer W.

[0106] In addition, regarding Figure 10 The case shown where the peripheral portion We is integrally removed from the back surface Wb side of the first wafer W can also be similarly formed after an unbonded region Ae is formed at the interface between the first wafer W and the second wafer S, forming a peripheral modification layer M1 and an inner surface modification layer M3 inside the first wafer W.

[0107] It should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, or modified in various ways without departing from the appended claims and their spirit.

[0108] Explanation of reference numerals in the attached figures

[0109] 1: Wafer processing system; 70: Interface modification device; 90: Control device; 100: Holding disk; 103: Rotation mechanism; 104: Horizontal movement mechanism; Fm: Metal film; Fw: Laser absorption film; P: Pulse pitch; Q: Index pitch; S: Second wafer; T: Overlapping wafer; W: First wafer.

Claims

1. A substrate processing apparatus for processing an overlapping substrate formed by stacking a first substrate, an interface layer, and a second substrate, wherein the interface layer comprises at least a laser absorption film and a lift-off promoting film, the substrate processing apparatus comprising: A substrate holding portion that holds the overlapping substrate; The interface laser irradiation unit irradiates the laser absorption film with laser pulses; A moving mechanism that moves the substrate holding portion and the interface laser irradiation portion relative to each other; and The control unit controls the laser irradiation unit of the interface and the moving mechanism. in, The control unit performs the following control: based on the thickness of the laser absorption film, it selects the position of the peeling surface between the first substrate and the second substrate from one of the two options: between the first substrate and the laser absorption film, and between the peeling promotion film and the second substrate.

2. The substrate processing apparatus according to claim 1, characterized in that, The control unit performs the following control: setting the interval of the laser irradiating the laser absorption film according to the selected position of the peeling surface.

3. The substrate processing apparatus according to claim 2, characterized in that, The mobile mechanism has: A rotating mechanism that rotates the substrate holding portion and the interface laser irradiation portion relative to each other; and A horizontal moving mechanism that moves the substrate holding part and the interface laser irradiation part relative to each other in a horizontal direction. The control unit performs the following control: setting a circumferential interval and a radial interval as the interval of the laser.

4. The substrate processing apparatus according to claim 2 or 3, characterized in that, The control unit performs the following control: setting the laser interval based on the thickness of the laser absorption film so as to minimize the laser processing time for the overlapping substrate.

5. The substrate processing apparatus according to claim 2 or 3, characterized in that, The control unit performs the following control: setting the laser interval based on the thickness of the laser absorption film, so that the laser processing time for the overlapping substrate becomes the laser processing time required by the substrate processing apparatus.

6. The substrate processing apparatus according to any one of claims 1 to 3, characterized in that, It also includes an internal laser irradiation unit, which irradiates a laser into the interior of the first substrate to form a modified layer that becomes the peeling start point of the first substrate.

7. The substrate processing apparatus according to claim 6, characterized in that, It also includes a peripheral removal section, which removes the peripheral portion of the first substrate that is the object of removal. The internal laser irradiation section forms a peripheral modification layer, which becomes the peeling starting point for the peripheral portion of the first substrate, which is the target of removal.

8. The substrate processing apparatus according to any one of claims 1 to 3, characterized in that, A second peeling facilitator film is formed between the first substrate and the laser absorption film. The control unit selects the position of the peeling surface of the first substrate and the second substrate from one of the two options: between the first substrate and the second peeling promoting film, which replaces the space between the first substrate and the laser absorption film, and between the peeling promoting film and the second substrate.

9. The substrate processing apparatus according to any one of claims 1 to 3, characterized in that, The peeling-promoting membrane is a tungsten membrane.

10. A substrate processing method for processing an overlapping substrate formed by stacking a first substrate, an interface layer, and a second substrate, wherein the interface layer comprises at least a laser absorption film and a lift-off promoting film, the substrate processing method comprising: Obtain the thickness information of the laser absorption film; as well as Based on the thickness information, the position of the peeling surface between the first substrate and the second substrate is selected from either the space between the first substrate and the laser absorption film, or the space between the peeling promotion film and the second substrate.

11. The substrate processing method according to claim 10, characterized in that, include: The interval of the laser irradiation onto the laser absorption film is set according to the selected location of the peeling surface; as well as The laser is pulsed onto the laser absorption film at intervals that are defined by the laser beam.

12. The substrate processing method according to claim 11, characterized in that, The laser spacing includes circumferential spacing and radial spacing. While irradiating the laser from the irradiation portion of the laser onto the laser absorption film, the overlapping substrate and the irradiation portion are rotated relative to each other to form the circumferential spacing, and the overlapping substrate and the irradiation portion of the laser are moved relative to each other in the horizontal direction to form the radial spacing.

13. The substrate processing method according to claim 11 or 12, characterized in that, The laser interval is set based on the thickness of the laser absorption film to minimize the laser processing time for the overlapping substrate.

14. The substrate processing method according to claim 11 or 12, characterized in that, The laser interval is set based on the thickness of the laser absorption film so that the laser processing time for the overlapping substrate becomes the required laser processing time.

15. The substrate processing method according to any one of claims 10 to 12, characterized in that, Also includes: A modified layer is formed by irradiating the interior of the first substrate with a laser to form a peeling start point for the first substrate.

16. The substrate processing method according to claim 15, characterized in that, It also includes: removing the peripheral portion of the first substrate, which is the target of removal. The modified layer formed inside the first substrate includes a peripheral modified layer, which serves as the peeling start point for the peripheral portion of the first substrate that is to be removed.

17. The substrate processing method according to any one of claims 10 to 12, characterized in that, A second peeling facilitator film is formed between the first substrate and the laser absorption film. The position of the peeling surface of the first substrate and the second substrate is selected from one of the two: between the first substrate and the second peeling promoting film, which replaces the space between the first substrate and the laser absorption film, and between the peeling promoting film and the second substrate.

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