Manufacturing method of semiconductor device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-12-14
- Publication Date
- 2026-03-06
AI Technical Summary
The challenge in manufacturing semiconductor devices using wide bandgap materials is the high cost and waste associated with polishing semiconductor wafers, and the difficulty in bonding semiconductor substrates to supports during high-temperature processes without using costly CMP methods.
A method involving the formation of a dividing layer in a semiconductor wafer using hydrogen ions or laser irradiation, followed by forming an annular fixed part under reduced pressure to create a bonding force through pressure differences, allowing separation and handling of semiconductor substrates without full-surface bonding.
This method reduces waste and lowers manufacturing costs by enabling easy handling and bonding of semiconductor substrates, while minimizing stress and defects during high-temperature processes.
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Abstract
Description
[Technical field]
[0001] The present invention relates to semiconductor device manufacturing techniques. [Background technology]
[0002] 2. Description of the Related Art There exists a semiconductor device manufacturing technique that includes a process of forming a semiconductor substrate of a desired thickness (for example, a thickness of 150 μm or less) by polishing a semiconductor wafer (for example, a wafer having a thickness of about 300 μm).
[0003] In recent years, wide band gap (WBG) materials such as GaAs, SiC, GaN, AlN, BN, and diamond have been attracting attention as semiconductor materials that enable semiconductor devices to operate normally even at high temperatures of up to 300°C. WBG materials are also semiconductor materials that enable faster switching speeds, and in that respect, they are expected to be used as materials for semiconductor devices for high-speed communications. WBG materials are also semiconductor materials that are resistant to high electric fields, and in that respect, they are expected to be used as materials for high-voltage semiconductor devices. Thus, WBG materials have various advantages as materials for semiconductor devices.
[0004] On the other hand, WBG materials are expensive materials, and yet when semiconductor substrates are formed from WBG materials by polishing semiconductor wafers, the parts of the semiconductor wafers that are removed by polishing are wasted, resulting in a significant increase in manufacturing costs.
[0005] In order to prevent such waste, a technique has been proposed in which a dividing layer is formed in a semiconductor wafer by injecting hydrogen ions into the surface of the semiconductor wafer, and the semiconductor wafer is divided at the dividing layer to form a semiconductor substrate (see, for example, Patent Document 1). With this technique, it is possible to manufacture thin semiconductor substrates without wasting the semiconductor material that constitutes the semiconductor wafer. [Prior art documents] [Patent documents]
[0006] [Patent Document 1] JP 2007-250576 A Summary of the Invention [Problem to be solved by the invention]
[0007] In the above-mentioned technology for forming a semiconductor substrate by implanting hydrogen ions, when dividing the semiconductor wafer at the dividing layer, it is necessary to hold the portion that will become the semiconductor substrate by a support (such as a glass substrate). Meanwhile, the semiconductor substrate after separation from the semiconductor wafer is exposed to a high-temperature atmosphere while still being held by the support during a process of forming a circuit on the semiconductor substrate. For this reason, it is necessary to bond the semiconductor wafer and the support in order to hold the semiconductor substrate by the support, but it is difficult to select an adhesive as a bonding means.
[0008] In the past, a method for bonding a semiconductor wafer to a support was used in which both bonding surfaces were subjected to CMP (Chemical Mechanical Polishing) and then the bonding surfaces were directly bonded together, thereby bonding the entire bonding surfaces together by atomic or molecular forces (direct bonding method).
[0009] However, bonding using CMP has the following problems: (1) the cost of the CMP process is high; and (2) because the semiconductor wafer and the support are strongly bonded, if it is desired to remove the support from the semiconductor substrate after separation from the semiconductor wafer, a process of grinding or otherwise removing the support is required.
[0010] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to facilitate handling of a semiconductor substrate after its formation in a semiconductor device manufacturing technique that includes a process for forming the semiconductor substrate using a dividing layer. [Means for solving the problem]
[0011] The method for manufacturing a semiconductor device according to the present invention includes a dividing layer forming step, a fixing portion forming step, and a dividing step. In the dividing layer forming step, a dividing layer is formed at a position at a predetermined depth from the surface of a first substrate mainly composed of a semiconductor, for enabling a semiconductor substrate having a thickness of the predetermined depth to be separated from the first substrate. After the dividing layer forming step, in the fixing portion forming step, a fixing portion for fixing a portion of the first substrate that will become a semiconductor substrate to a second substrate is formed in an annular shape in an atmosphere at a lower pressure than a predetermined pressure, thereby sealing the inside of the annular shape. After the fixing portion forming step, in the dividing step, the first substrate is divided at the dividing layer in an atmosphere at the predetermined pressure.
[0012] According to the above manufacturing method, in the fixing part forming step, a ring-shaped fixing part is formed under an atmosphere of lower pressure than a predetermined pressure (for example, atmospheric pressure), so that in an atmosphere of the predetermined pressure (the atmosphere used in the dividing step), a pressure difference can be generated between the pressure inside the ring of the fixing part (internal pressure) and the pressure outside the ring (external pressure), and as a result, an adhesion force due to the pressure difference can be generated between the first substrate and the second substrate. Therefore, in an atmosphere of the predetermined pressure, the first substrate and the second substrate can be firmly bonded by the bonding force of the fixing part and the adhesion force due to the pressure difference between the internal pressure and the external pressure. Therefore, even if the first substrate and the second substrate are not bonded over the entire bonding surface as in the conventional method (i.e., even if bonding using CMP is not performed), a bonding force sufficient to hold the semiconductor substrate separated from the first substrate in the dividing step to the second substrate can be obtained. Effect of the Invention
[0013] According to the present invention, in a semiconductor device manufacturing technique including a process of forming a semiconductor substrate using a dividing layer, the semiconductor substrate can be easily handled after it is formed. [Brief description of the drawings]
[0014] [Figure 1]1A to 1C are conceptual diagrams showing a manufacturing method according to an embodiment in the order of processing steps. [Diagram 2] FIG. 2 is a conceptual diagram showing the subsequent processing of FIG. 1 in processing order. [Diagram 3] FIG. 4 is a plan view showing the shape of a fixing portion formed in the embodiment. [Figure 4] 10A to 10C are conceptual diagrams showing a part of a manufacturing method according to a first modified example in a processing order. [Diagram 5] FIG. 13A is a conceptual diagram showing a division layer forming step performed in a manufacturing method according to a second modified example, and FIG. 13B is a conceptual diagram showing a comparative example. [Figure 6] FIG. 13 is a conceptual diagram showing a part of a manufacturing method according to a fourth modified example in the order of processing. [Figure 7] FIG. 13 is a plan view showing the shape of a fixing portion formed in a fourth modified example. [Figure 8] 8A is a conceptual diagram and FIG. 8B is a plan view showing a further modified example of the manufacturing method shown in FIGS. 6 and 7. [Figure 9] FIG. 13 is a plan view showing a first example of the shape of the fixing portion Q formed in the fifth modified example. [Figure 10] 13A and 13B are plan views showing a second example and a third example of the shape of the fixing portion Q formed in the fifth modified example, respectively. [Figure 11] 13A is a conceptual diagram showing a fastening portion forming step and a cutting step performed in a manufacturing method according to a sixth modified example, and FIG. 13B is a plan view showing the shape of the fastening portion formed in the sixth modified example. [Figure 12] FIG. 13 is a conceptual diagram showing a cutting step and a peeling step performed in a manufacturing method according to an eighth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Hereinafter, embodiments and modifications of the method for manufacturing a semiconductor device according to the present invention will be specifically described. Note that the manufacturing method described below can be realized by using various well-known apparatuses.
[0016] [1] Implementation Example 1 and 2 are conceptual diagrams showing the manufacturing method according to the embodiment in the order of processing. In this manufacturing method, a division layer forming step S1, a fixing part forming step S2, a division step S3, a device forming step S4, a cutting step S5, a peeling step S6, and a singulation step S7 are performed in this order. Each step will be specifically described below.
[0017] <Dividing layer forming step S1> In the division layer forming step S1 (see FIG. 1), a division layer 111 is formed at a position of a predetermined depth Dt from the surface 11a of the first substrate 11 mainly composed of a semiconductor. Here, the first substrate 11 is not particularly limited, but for example, a single crystal semiconductor wafer, and its main component (semiconductor) can be a wide band gap (WBG) material such as GaAs, SiC, GaN, AlN, BN, diamond, etc. Also, the division layer 111 is a layer that enables the semiconductor substrate K having a thickness Td of the predetermined depth Dt to be separated from the first substrate 11, and can be formed by implanting hydrogen ions from the surface 11a of the first substrate 11. According to the method of implanting hydrogen ions, the division layer 111 can be formed at a depth of about 10 μm or shallower from the surface 11a, and as a result, a semiconductor substrate K having a thin thickness Td can be obtained.
[0018] Here, instead of the method of implanting hydrogen ions, the division layer 111 can be formed by irradiating laser light with a focal point at a position at a predetermined depth Dt from the surface 11a. With this method, the focal point position can be changed in the depth direction, so that the division layer 111 can be formed at a desired depth. Therefore, with the method of irradiating laser light, the division layer 111 can be formed at a deeper position (for example, a position at a depth of about 50 to 150 μm from the surface 11a) than with the method of implanting hydrogen ions, and as a result, a semiconductor substrate K with a large thickness Td can be obtained.
[0019] The first substrate 11 is divided at the division layer 111 in a division step S3 described later, and as a result, a semiconductor substrate K having a thickness Td corresponding to a predetermined depth Dt is separated from the first substrate 11. Here, when dividing the first substrate 11, it is necessary to hold the portion that will become the semiconductor substrate K with a support. Therefore, in the next fixing portion forming step S2, a second substrate 12 that will become the support is bonded to the surface 11a of the first substrate 11.
[0020] <Fixed portion forming step S2> The second substrate 12 is not particularly limited, but may be, for example, a polycrystalline semiconductor wafer, and its main component (semiconductor) may be a wide band gap (WBG) material such as GaAs, SiC, GaN, AlN, BN, diamond, etc. Note that, instead of a semiconductor wafer, the second substrate 12 may be a substrate formed of another material (Si, sapphire, quartz, etc.) that is not limited to semiconductors.
[0021] In the fixing portion forming step S2, a fixing portion Q for fixing a portion of the first substrate 11 that will become the semiconductor substrate K to the second substrate 12 is formed in an annular shape in an atmosphere at a pressure lower than a predetermined pressure Pt, thereby sealing the inside of the annular portion. Here, the predetermined pressure Pt is the atmospheric pressure used in the division step S3 described later, and is not particularly limited, but is, for example, atmospheric pressure.
[0022] Specifically, in the fixing portion forming step S2 (see FIG. 1), a metal layer forming step S21 and a laser light irradiating step S22 are carried out in this order.
[0023] In the metal layer forming step S21, a metal layer 13 is formed on the entire surface 11a of the first substrate 11. Although not particularly limited, the metal layer 13 is formed to a thickness of 1 μm or less by a film forming method such as a vapor deposition method. The main component of the metal layer 13 may be a metal such as Cu, Al, Cr, Ti, Ta, or Au.
[0024] Thereafter, in a laser light irradiation step S22, the first substrate 11 and the second substrate 12 are opposed to each other with the metal layer 13 interposed therebetween. Then, in this state, a portion of the metal layer 13 where the fixing portion Q is to be formed (in this embodiment, a portion on the peripheral portion 112 of the first substrate 11; details will be described later (see FIG. 3)) is irradiated with laser light to heat the portion. At this time, the first substrate 11 and the second substrate 12 may be sandwiched between quartz plates or the like to increase the degree of adhesion with the portion of the metal layer 13 where the fixing portion Q is to be formed.
[0025] By irradiating the metal layer 13 with the laser light, the metal layer 13 can be melted together with the first substrate 11 and the second substrate 12 at the irradiated portion of the laser light (the portion where the fixing portion Q is to be formed), or the metal that is the main component of the metal layer 13 can be diffused into the first substrate 11 and the second substrate 12. As a result, a compound (metal silicide, etc.) or an alloy (metal-Si alloy, etc.) of the main component (semiconductor, etc.) of the first substrate 11 and the second substrate 12 and the metal is formed at the interface between the first substrate 11 and the second substrate 12 and the metal layer 13, respectively, and thus the fixing portion Q that firmly bonds the first substrate 11 (the portion that will become the semiconductor substrate K) and the second substrate 12 is formed.
[0026] Such a fixed portion Q is formed continuously and annularly in an atmosphere at a lower pressure than the predetermined pressure Pt, so that the inside of the annular portion is sealed while maintaining the pressure therein at a lower pressure than the predetermined pressure Pt.
[0027] Fig. 3 is a plan view showing the shape of the fixing portion Q formed in this embodiment. As shown in Fig. 3, in this embodiment, the fixing portion Q is formed around the entire periphery of the peripheral portion 112 of the first substrate 11 (specifically, the peripheral portion of the portion of the first substrate 11 that will become the semiconductor substrate K; see also Fig. 1). In the example of Fig. 3, the first substrate 11 is disk-shaped, and the fixing portion Q is formed in an annular shape along the peripheral portion 112.
[0028] The shape of the fixing portion Q is not limited to a circular ring shape, and can be appropriately changed to another ring shape (such as a polygonal shape) according to the peripheral shape of the first substrate 11. When the fixing portion Q is formed on the peripheral portion 112 of the first substrate 11 as in this embodiment, the metal layer forming step S21 is not limited to forming the metal layer 13 on the entire surface 11a of the first substrate 11, but may form the metal layer 13 only on the region on the peripheral portion 112 of the surface 11a, or may form the metal layer 13 only on the portion of the surface 11a where the fixing portion Q is to be formed. Furthermore, in the metal layer forming step S21, instead of forming the metal layer 13 on the surface 11a of the first substrate 11, the metal layer 13 may be formed on the surface 12a of the second substrate 12. In this case, in the metal layer formation step S21, the metal layer 13 is not limited to being formed over the entire surface 12a of the second substrate 12, but may be formed only in the area of the surface 12a that will face the peripheral portion 112, or may be formed only in the portion of the surface 12a where the fixing portion Q is intended to be formed.
[0029] According to such a fixing part forming step S2, by forming the annular fixing part Q under an atmosphere of a lower pressure than the predetermined pressure Pt (for example, atmospheric pressure), a pressure difference can be generated between the pressure inside the annular part of the fixing part Q (internal pressure) and the pressure outside the annular part (external pressure) under the atmosphere of the predetermined pressure Pt (the atmosphere used in the division step S3 described later), and as a result, an adhesion force due to the pressure difference can be generated between the first substrate 11 and the second substrate 12. Therefore, under the atmosphere of the predetermined pressure Pt, the first substrate 11 and the second substrate 12 can be firmly bonded by the bonding force of the fixing part Q and the adhesion force due to the pressure difference between the internal pressure and the external pressure. Therefore, even if the first substrate 11 and the second substrate 12 are not bonded over the entire bonding surface as in the conventional method (i.e., even if bonding using CMP is not performed), a bonding force sufficient to hold the semiconductor substrate K separated from the first substrate 11 in the division step S3 described later on the second substrate 12 can be obtained.
[0030] Therefore, when the fixing portion Q is formed in a ring shape along the peripheral portion 112 as in this embodiment, the peripheral portion 112 of the semiconductor substrate K can be held by the second substrate 12 by the bonding force of the fixing portion Q, while the portion of the semiconductor substrate K inside the fixing portion Q (the portion where the multiple device regions Rd are provided) can be held by the second substrate 12 by the adsorption force caused by the pressure difference, and as a result, the semiconductor substrate K can be held by the second substrate 12 with sufficient bonding force.
[0031] <Division step S3> In the dividing step S3 (see FIG. 1), the atmospheric pressure is adjusted to a predetermined pressure Pt (e.g., atmospheric pressure). This allows the portion of the first substrate 11 that will become the semiconductor substrate K to be held to the second substrate 12 with sufficient bonding strength (bonding strength by the fixing portion Q and an adhesion force resulting from the pressure difference between the internal and external air pressures). Then, in the dividing step S3, the first substrate 11 is divided at the dividing layer 111 in an atmosphere of the predetermined pressure Pt.
[0032] As a result, the semiconductor substrate K having a thickness Td corresponding to the depth (predetermined depth Dt) at which the division layer 111 was formed is separated from the first substrate 11 while still being held by the second substrate 12. Then, the device formation step S4 described below is performed on this semiconductor substrate K. Meanwhile, the remaining portion 11R of the first substrate 11 other than the semiconductor substrate K (the portion remaining after division) is reused for manufacturing a new semiconductor substrate K and a semiconductor device.
[0033] <Device formation step S4> In the device formation step S4 (see FIG. 2), at least some of the elements (hereinafter referred to as "elements Gd") that will be included in a semiconductor device are fabricated in each of a plurality of device regions Rd (see also FIG. 3) provided in the semiconductor substrate K. Although not particularly limited, in the device formation step S4, elements Gd such as MOSFETs and Schottky diodes can be formed in each device region Rd. Note that, before the elements Gd are formed in the semiconductor substrate K, the surface Ka of the semiconductor substrate K (the surface that appears after division at the division layer 111) may be polished to adjust the smoothness (surface roughness) of the surface Ka to the smoothness required for fabricating the elements Gd in the semiconductor substrate K.
[0034] Such a device formation step S4 is often performed at a high temperature exceeding 1000°C. Here, consider a case where the expansion coefficient of the semiconductor substrate K is different from that of the second substrate 12. In this case, if the semiconductor substrate K and the second substrate 12 are bonded over the entire bonding surface as in the conventional method (i.e., bonding is performed using CMP), due to the bonding over the entire bonding surface, when the device formation step S4 is performed at a high temperature, one of the semiconductor substrate K and the second substrate 12, which has a larger expansion coefficient, will pull the other substrate and expand it to a value greater than its expansion coefficient, and conversely, the other substrate will try to hinder the expansion of the one substrate. For this reason, stress is generated in the semiconductor substrate K and the second substrate 12, and the stress may appear in the semiconductor substrate K and the second substrate 12 as defects such as distortion. In addition, the stress generated in the semiconductor substrate K may cause defects in elements Gd such as MOSFETs and Schottky diodes formed on the semiconductor substrate K.
[0035] On the other hand, in this embodiment, the semiconductor substrate K and the second substrate 12 are not bonded to each other inside the fixing portion Q. Therefore, when the device formation step S4 is performed at high temperature, one of the semiconductor substrate K and the second substrate 12, which has a larger expansion coefficient, can bend independently of the other substrate inside the fixing portion Q, and as a result, each of the two substrates can expand by an amount corresponding to its own expansion coefficient. Therefore, stress is unlikely to occur in either the semiconductor substrate K or the second substrate 12, and therefore defects are unlikely to occur in elements Gd such as MOSFETs and Schottky diodes formed on the semiconductor substrate K.
[0036] <Cutting step S5> In the cutting step S5 (see FIG. 2), the semiconductor substrate K and the second substrate 12 are held on the holding sheet 14 in a position in which the semiconductor substrate K faces the holding sheet 14. In this state, the second substrate 12 and the semiconductor substrate K are cut into annular shapes along the annular fixing portion Q at a position inside the fixing portion Q. Specifically, the second substrate 12 and the semiconductor substrate K are cut so that the cutting line surrounds all the device regions Rd provided on the semiconductor substrate K. The cutting method used at this time may be a blade dicing method, a plasma etching method, a laser ablation method, or the like.
[0037] In this embodiment, the semiconductor substrate K and the second substrate 12 are not bonded to each other inside the fixing portion Q. Therefore, by cutting inside the annular fixing portion Q, the semiconductor substrate K and the second substrate 12 inward from the cut portion are separated from the fixing portion Q. That is, the inner portions are released from the bond by the fixing portion Q. In addition, by the cutting, the sealing inside the annular portion by the fixing portion Q is released, and as a result, the suction force generated by the pressure difference between the internal air pressure and the external air pressure disappears. Therefore, the portion of the second substrate 12 inward from the cut portion (hereinafter referred to as the "inner portion 121") is separated from both the fixing portion Q and the semiconductor substrate K. In other words, the inner portion 121 of the second substrate 12 is in a state where it can be easily peeled off from the semiconductor substrate K.
[0038] <Peeling step S6> In a peeling step S6 (see FIG. 2), the inner portion 121 of the second substrate 12 is peeled off from the semiconductor substrate K at the interface between the second substrate 12 and the metal layer 13. This makes it possible to expose the metal layer 13 inside the annular portion 122 remaining after the peeling of the second substrate 12 (after the peeling of the inner portion 121). Thereafter, the exposed metal layer 13 is removed by a method such as polishing or etching, thereby making it possible to expose the semiconductor substrate K inside the annular portion 122.
[0039] In the above-mentioned fixing portion forming step S2, instead of forming the metal layer 13 on the surface 11a of the first substrate 11, if the metal layer 13 is formed on the surface 12a of the second substrate 12, the inner portion 121 of the second substrate 12 can be peeled off from the semiconductor substrate K at the interface between the metal layer 13 and the semiconductor substrate K in the peeling step S6. In this case, the semiconductor substrate K can be exposed by peeling off the inner portion 121 of the second substrate 12. In addition, in the metal layer forming step S21, if the metal layer 13 is formed only on the region on the peripheral portion 112 of the surface 11a of the first substrate 11 or the region facing the peripheral portion 112 of the surface 12a of the second substrate 12, the metal layer 13 is not interposed between the semiconductor substrate K and the second substrate 12 inside the peripheral portion 112, so in this case too, the semiconductor substrate K can be exposed by peeling off the inner portion 121 of the second substrate 12.
[0040] <Singulation step S7> In the singulation step S7 (see FIG. 2), while the semiconductor substrate K is held on the holding sheet 14, the semiconductor substrate K is cut to separate the multiple device regions Rd provided on the semiconductor substrate K. Specifically, the semiconductor substrate K is cut along boundary lines Lb (see FIG. 3) that separate the multiple device regions Rd to separate the multiple device regions Rd. The cutting method used in this process may be a blade dicing method, a plasma etching method, a laser ablation method, or the like. In this way, multiple semiconductor devices each having an element Gd such as a MOSFET or a Schottky diode are manufactured.
[0041] According to the manufacturing method of this embodiment, as described above, the first substrate 11 and the second substrate 12 can be firmly bonded to each other by the bonding force of the annular fixing portion Q and the suction force caused by the pressure difference between the air pressure inside the annular region (internal air pressure) and the air pressure outside the annular region (external air pressure). Therefore, even if the first substrate 11 and the second substrate 12 are not bonded to each other over the entire bonding surface as in the conventional method (i.e., even if bonding using CMP is not performed), a bonding force sufficient to hold the semiconductor substrate K separated from the first substrate 11 in the division step S3 on the second substrate 12 can be obtained. In addition, since the semiconductor substrate K and the second substrate 12 are not bonded to each other inside the fixing portion Q, the inner portion 121 of the second substrate 12 can be easily peeled off from the semiconductor substrate K by cutting inside the annular fixing portion Q in the cutting step S5, and the peeling of the inner portion 121 can expose the semiconductor substrate K.
[0042] Thus, according to the manufacturing method of this embodiment, in a semiconductor device manufacturing technology that includes a process of forming a semiconductor substrate K using the division layer 111, the semiconductor substrate K can be easily handled after it is formed (after the division step S3 is performed in this embodiment).
[0043] [2] Variations [2-1] First modified example FIG. 4 is a conceptual diagram showing a part of the manufacturing method according to the first modified example in the order of processing. In the above-mentioned manufacturing method, a reinforcing layer forming step S8 may be performed after the peeling step S6 and before the singulation step S7. Specifically, in the reinforcing layer forming step S8, inside the annular portion 122 remaining after peeling (after peeling of the inner portion 121) of the second substrate 12, a reinforcing layer 21 having a predetermined thickness Te is formed on the back surface Kb (the surface that was the front surface 11a of the first substrate 11) of the semiconductor substrate K located on the opposite side to the front surface Ka of the semiconductor substrate K facing the holding sheet 14. More specifically, the reinforcing layer 21 having the predetermined thickness Te can be formed by applying a reinforcing material (for example, a thermoplastic material, etc.) on the back surface Kb of the semiconductor substrate K inside the annular portion 122 of the second substrate 12 using an application method such as a spin coat method or a spray coat method. The reinforcing material may be an electrically insulating material or a conductive material.
[0044] In the singulation step S7, when the semiconductor substrate K is cut, the reinforcing layer 21 is also cut at the same positions as the cutting positions of the semiconductor substrate K when viewed in plan, thereby singulating each of the multiple device regions Rd provided on the semiconductor substrate K. This makes it possible to manufacture semiconductor devices supported by the reinforcing substrate 21S.
[0045] [2-2] Second variant FIG. 5(A) is a conceptual diagram showing the division layer forming step S1 executed in the manufacturing method according to the second modification. In the above-mentioned manufacturing method, a substrate having a rounded outer peripheral surface 11d (in other words, a convex outer peripheral surface 11d) as shown in FIG. 5(A) may be used as the first substrate 11. On the other hand, when the first substrate 11 having such a shape is used, if the division step S3 is executed as it is after the division layer 111 is formed, a sharp edge 11e is formed on the outer peripheral edge of the semiconductor substrate K formed in the division step S3 as shown in FIG. 5(B). Then, such a sharp edge 11e may damage other members or chip and cause defects in the semiconductor substrate K during the manufacturing process of the semiconductor device.
[0046] 5(A), after forming the division layer 111, the peripheral portion 112 (the portion with the rounded outer circumferential surface 11d) of the first substrate 11 may be cut off. Then, the first substrate 11 from which the peripheral portion 112 has been cut off may be used as a new first substrate 11, and the process from the fixing portion forming step S2 described above may be carried out. By cutting off the peripheral portion 112 (the portion with the rounded outer circumferential surface 11d) of the first substrate 11 in this manner, it is possible to prevent the above-mentioned sharp edge 11e from being formed on the outer periphery of the semiconductor substrate K.
[0047] In order to prevent the formation of the above-mentioned sharp edge 11e, instead of the method of cutting off the peripheral portion 112 (the portion having the rounded outer surface 11d) of the first substrate 11 after forming the dividing layer 111, the dividing layer 111 may be formed after cutting off the peripheral portion 112 (the portion having the rounded outer surface 11d) of the first substrate 11.
[0048] [2-3] Third variant In the above-described manufacturing method, even if the device formation step S4 is performed at high temperature, if there is no risk of problems caused by the expansion of the substrate as described above (problems in which the stress caused by the expansion of the substrate cannot be relieved and manifests itself as defects in the substrate or element Gd) occurring (for example, when the expansion coefficient of the semiconductor substrate K is the same as the expansion coefficient of the second substrate 12), the following process may be performed after the division step S3.
[0049] Here, according to the annular fixing part Q formed in the fixing part forming step S2, the inside of the annular part is sealed while the pressure inside the annular part is lower than the predetermined pressure Pt, so that in an atmosphere of the predetermined pressure Pt or an atmosphere of a higher pressure than the predetermined pressure Pt, a pressure difference can be generated between the pressure inside the annular part of the fixing part Q (internal pressure) and the pressure outside the annular part (external pressure), and as a result, an adhesive force due to the pressure difference can be generated between the first substrate 11 and the second substrate 12. Therefore, this adhesive force can adhere the first substrate 11 and the second substrate 12 to each other, or, if a metal layer 13 is interposed between the substrates, the substrate can be adhered to the metal layer 13.
[0050] Therefore, after the division step S3, the semiconductor substrate K and the second substrate 12 may be subjected to a heat treatment while maintaining the above-mentioned state of adhesion (i.e., under an atmosphere of a predetermined pressure Pt or under an atmosphere of a higher pressure than the predetermined pressure Pt), thereby producing a compound (such as a metal silicide) or an alloy (such as a metal-Si alloy) between the main component (such as a semiconductor) of the first substrate 11 and the second substrate 12 and the metal that is the main component of the metal layer 13 at their interface, and as a result, the semiconductor substrate K and the second substrate 12 may be bonded even in the region inside the bonding portion Q.
[0051] The method of bonding the inner region of the bonding portion Q by utilizing the suction force caused by the pressure difference can be realized even when performing heat treatment at a low temperature of 1000° C. or less (for example, 400° C.) (such as eutectic bonding). In this case, even if the expansion coefficient of the semiconductor substrate K is different from that of the second substrate 12, the inner region of the bonding portion Q can be bonded without causing a large difference in the amount of expansion. In other words, the inner region of the bonding portion Q can be bonded without causing a large stress caused by the difference in the expansion coefficient. Therefore, when it is desired to bond the semiconductor substrate K and the second substrate 12 over the entire bonding surface and the bonding over the entire bonding surface does not cause a problem in the subsequent process (for example, when the device formation step S4 is not performed at a high temperature), the method of bonding the inner region of the bonding portion Q by heat treatment at such a low temperature can be used.
[0052] [2-4] Fourth variant FIG. 6 is a conceptual diagram showing a part of the manufacturing method according to the fourth modification in the order of processing. FIG. 7 is a plan view showing the shape of the fixing part Q formed in this modification. In the above-mentioned manufacturing method, in the fixing part forming step S2, for each of the device regions Rd provided in the portion of the first substrate 11 that will become the semiconductor substrate K, the fixing part Q may be formed in an annular shape around the entire periphery of the peripheral part of the device region Rd. At this time, the fixing part Q is formed continuously and annularly in an atmosphere lower than the predetermined pressure Pt, so that the inside of the annular part is sealed while being in a state of lower pressure than the predetermined pressure Pt. In the example of FIG. 7, the shape of each device region Rd is quadrangular, and the fixing part Q is formed in a quadrangular annular shape along the peripheral part. Note that the shape of the fixing part Q is not limited to a quadrangular annular shape, but can be appropriately changed to another annular shape (such as a circular or polygonal shape) according to the peripheral shape of each device region Rd.
[0053] According to the formation of the fixing portion Q, in an atmosphere of a predetermined atmospheric pressure Pt, a pressure difference can be generated between the atmospheric pressure inside the annular region of the fixing portion Q (internal atmospheric pressure) and the atmospheric pressure outside the annular region (external atmospheric pressure) for each device region Rd, and as a result, an adhesion force due to the pressure difference can be generated at a plurality of locations between the first substrate 11 and the second substrate 12. Therefore, in an atmosphere of a predetermined atmospheric pressure Pt, the first substrate 11 and the second substrate 12 can be firmly bonded by the bonding force of the fixing portion Q and the adhesion force due to the pressure difference between the internal atmospheric pressure and the external atmospheric pressure. Therefore, even if the first substrate 11 and the second substrate 12 are not bonded over the entire bonding surface as in the conventional method (i.e., even if bonding using CMP is not performed), a bonding force sufficient to hold the semiconductor substrate K separated from the first substrate 11 in the division step S3 on the second substrate 12 can be obtained.
[0054] Then, after the dividing step S3 and the device forming step S4, in the cutting step S5, the semiconductor substrate K and the second substrate 12 are cut at positions between the fixing parts Q formed in each of the two adjacent device regions Rd while being held by the holding sheet 14, so that the multiple device regions Rd provided on the semiconductor substrate K can be individually separated. As a result, it is possible to manufacture semiconductor devices supported by the support substrate 12S (the substrate formed by cutting the second substrate 12). At this time, each semiconductor device is supported in a state of being firmly bonded to the support substrate 12S by the bonding force of the annular fixing parts Q and the suction force caused by the pressure difference between the air pressure inside the annular region (internal air pressure) and the air pressure outside the annular region (external air pressure).
[0055] Figures 8(A) and 8(B) are a conceptual diagram and a plan view showing a further modified example of the manufacturing method shown in Figures 6 and 7. As shown in Figures 8(A) and 8(B), in addition to forming an annular fixing portion Q on the periphery of each device region Rd, an annular fixing portion Q may also be formed along the periphery 112 of the first substrate 11 (specifically, the periphery of the portion of the first substrate 11 that will become the semiconductor substrate K).
[0056] According to this configuration, the annular fixing portion Q formed along the peripheral portion 112 can suppress peeling or flapping of the substrate edge portion when cutting is performed in the cutting step S5.
[0057] [2-5] Fifth variant In the above-described manufacturing method, in the fixing portion forming step S2, the annular fixing portion Q is not limited to the shape shown in FIG. 3 (embodiment) or FIG. 7 (fourth modified example), but may have the following shape.
[0058] 9, 10(A), and 10(B) are plan views showing three examples of the shape of the fixing portion Q formed in the fifth modified example. As shown in these figures, the device regions Rd may be divided into several groups, and the fixing portion Q may be formed in a ring shape for each group so as to surround all the device regions Rd in that group.
[0059] Here, in the example of FIG. 9, the fixing portion Q is formed to have an independent ring shape for each group. On the other hand, in FIG. 10(A) and FIG. 10(B), the fixing portion Q is formed by combining a circular portion and a straight portion so that a part of the fixing portion Q can be shared between groups. Specifically, FIG. 10(A) shows a case where the fixing portion Q is formed by a circular portion formed in a ring shape along the peripheral portion 112 and one straight portion crossing the inside of the circular portion. In this case, the straight portion of the fixing portion Q is shared between groups, and as a result, two ring-shaped portions capable of surrounding all the device regions Rd in each group are formed in the fixing portion Q. Also, FIG. 10(B) shows a case where the fixing portion Q is formed by a circular portion formed in a ring shape along the peripheral portion 112 and two straight portions crossing the inside of the circular portion and intersecting each other (orthogonal in the example of FIG. 10(B)). In this case as well, the straight line portions of the fixing portion Q are shared between the groups, and as a result, the fixing portion Q has four annular portions for each group that can surround all of the device regions Rd in that group.
[0060] [2-6] 6th variant Fig. 11(A) is a conceptual diagram showing the fixing portion forming step S2 and the cutting step S5 performed in the manufacturing method according to the sixth modified example, and Fig. 11(B) is a plan view showing the shape of the fixing portion Q formed in the sixth modified example.
[0061] In the above-described manufacturing method, in the fixing portion forming step S2, the fixing portion Q may be formed on the boundary line Lb that divides the multiple device regions Rd provided on the first substrate 11. The example in Fig. 10(B) shows a case where the fixing portion Q is formed by a circular portion formed in an annular shape along the peripheral portion 112 and a plurality of straight line portions that cross the inside of the circular portion through the boundary line Lb to form a lattice. By forming a lattice with a plurality of straight line portions in this manner, a plurality of annular portions that surround each device region Rd are formed in the fixing portion Q.
[0062] When the adhesion portion Q is formed on the boundary line Lb of the device region Rd in this manner, in the cutting step S5 (see FIG. 11(A)), the second substrate 12 and the semiconductor substrate K are cut along the boundary line Lb, so that the adhesion portion Q can be removed together with the portions of the second substrate 12 and the semiconductor substrate K that are removed during cutting.
[0063] [2-7] 7th variant In the above-described manufacturing method, the method of forming the adhesion portion Q in the adhesion portion formation step S2 is not limited to the method of forming the adhesion portion Q by irradiating the metal layer 13 with laser light, but may be appropriately changed to a method of forming the adhesion portion Q by irradiating the interface between the first substrate 11 and the second substrate 12 while they are in direct contact with each other.
[0064] [2-8] 8th variant 12 is a conceptual diagram showing a cutting step S5 and a peeling step S6 executed in a manufacturing method according to an eighth modified example. In the manufacturing method according to the above-described embodiment, in the cutting step S5, only the second substrate 12 out of the second substrate 12 and the semiconductor substrate K may be cut annularly along the annular fixing portion Q at a position inside the fixing portion Q. Specifically, only the cutting of the second substrate 12 is executed so that the cutting line surrounds all the device regions Rd provided in the semiconductor substrate K.
[0065] According to this cutting method, the inner portion 121 of the second substrate 12 is cut off from the fixing portion Q, while the semiconductor substrate K is maintained in a state where the entirety of the semiconductor substrate K is connected to the fixing portion Q. In other words, the entirety of the semiconductor substrate K is joined by the fixing portion Q to the annular portion 122 remaining after the peeling of the second substrate 12 (after the peeling of the inner portion 121).
[0066] Therefore, by peeling the inner portion 121 of the second substrate 12 from the semiconductor substrate K in the peeling step S6, the semiconductor substrate K supported by the support can be obtained using the annular portion 122 of the second substrate 12 as a ring-shaped support.
[0067] [2-9] Other variations In the above-mentioned manufacturing method, when an adhesive force caused by a pressure difference between the air pressure inside the annular shape of the fixing part Q (internal air pressure) and the air pressure outside the annular shape (external air pressure) is not required, the shape of the fixing part Q may be appropriately changed to various shapes other than the annular shape. For example, the fixing part Q may be formed in the form of a dot or an open line (a line with an end).
[0068] The above-mentioned embodiments and the description of the modifications should be considered as illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims, not by the above-mentioned embodiments and modifications. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope of the claims.
[0069] Furthermore, from the above-described embodiments and modifications, some steps constituting the method for manufacturing a semiconductor device may be partially extracted as the subject of the invention, or each step may be extracted individually. [Explanation of symbols]
[0070] K Semiconductor substrate Q Attachment 11 First board 11a surface 11d Outer surface 11e Edge 11R remainder 12 Second board 12a surface 12S support board 13 Metal layer 14 Retaining Sheet 21 Reinforcement layer 21S Reinforcement board Dt Predetermined depth Gd element Ka surface Kb back Lb border Pt Prescribed pressure Rd Device Region Td Thickness Te specified thickness 111 Split layer 112 Periphery 121 Inner part 122 Circular Part S1 Dividing layer formation step S2 Adhesive formation step S3 Split Step S4 Device formation step S5 Cutting step S6 Peeling step S7 Singulation step S8 Reinforcement layer formation step S21 Metal layer formation step S22 Laser light irradiation step
Claims
1. a dividing layer forming step of forming a dividing layer at a position at a predetermined depth from a surface of a first substrate mainly made of a semiconductor, the dividing layer having a thickness corresponding to the predetermined depth, which enables separation of the semiconductor substrate from the first substrate; a fixing portion forming step of forming, after the dividing layer forming step, a fixing portion for fixing the portion of the first substrate that will become the semiconductor substrate to the second substrate in an annular shape under an atmosphere at a pressure lower than a predetermined pressure, thereby sealing the inside of the annular portion; a dividing step of dividing the first substrate at the dividing layer under the atmosphere of the predetermined pressure after the fixing portion forming step; Equipped with In the fixing portion forming step, the fixing portion is formed around the entire periphery of a peripheral portion of a portion of the first substrate that will become the semiconductor substrate, The fixing portion forming step includes: a metal layer forming step of forming a metal layer on at least a region on the peripheral edge portion of the surface of the first substrate or on at least a region facing the peripheral edge portion of the surface of the second substrate; a laser light irradiation step of interposing the metal layer between the first substrate and the second substrate, and irradiating a portion of the metal layer on the peripheral edge portion with laser light in this state to heat the portion and form the fixed portion; A method for manufacturing a semiconductor device, comprising:
2. a device forming step of fabricating at least some of the elements to be included in a semiconductor device in each of a plurality of device regions provided in the semiconductor substrate after the dividing step; a cutting step of holding the semiconductor substrate and the second substrate on a holding sheet in a position where the semiconductor substrate faces the holding sheet after the device forming step, and cutting at least the second substrate at a position inside the annular fixing portion in that state; The method of claim 1 further comprising:
3. A dividing layer forming step of forming a dividing layer at a position at a predetermined depth from the surface of a first substrate whose main component is a semiconductor, the dividing layer enabling a semiconductor substrate having a thickness corresponding to the predetermined depth to be separated from the first substrate; a fixing portion forming step of forming, after the dividing layer forming step, a fixing portion for fixing the portion of the first substrate that will become the semiconductor substrate to the second substrate in an annular shape under an atmosphere at a pressure lower than a predetermined pressure, thereby sealing the inside of the annular portion; a dividing step of dividing the first substrate at the dividing layer under the atmosphere of the predetermined pressure after the fixing portion forming step; A method for manufacturing a semiconductor device, comprising: In the fixing portion forming step, the fixing portion is formed around the entire periphery of a peripheral portion of a portion of the first substrate that will become the semiconductor substrate, a device forming step of fabricating at least some of the elements to be included in a semiconductor device in each of a plurality of device regions provided in the semiconductor substrate after the dividing step; a cutting step of holding the semiconductor substrate and the second substrate on a holding sheet in a position where the semiconductor substrate faces the holding sheet after the device forming step, and cutting at least the second substrate at a position inside the annular fixing portion in that state; The method for manufacturing a semiconductor device further comprises:
4. a peeling step of peeling off a portion of the second substrate inside the annular fixing portion from the semiconductor substrate after the cutting step; The method for manufacturing a semiconductor device according to claim 2 or 3, further comprising:
5. a reinforcing layer forming step of forming a reinforcing layer of a predetermined thickness as a reinforcing substrate for the semiconductor substrate on a back surface of the semiconductor substrate located inside the annular portion of the second substrate remaining after the peeling step, the back surface being opposite to the front surface of the semiconductor substrate facing the holding sheet; The method for manufacturing a semiconductor device according to claim 4 , further comprising:
6. In the dividing layer forming step, after forming the dividing layer, a peripheral portion of the first substrate is cut off; 2. The method for manufacturing a semiconductor device according to claim 1, wherein in the fixing portion forming step, the first substrate from which the peripheral portion has been cut off in the dividing layer forming step is used as a new first substrate, and the fixing portion is formed around the entire peripheral portion of the portion of the new first substrate that will become the semiconductor substrate.
7. A dividing layer forming step of forming a dividing layer at a position at a predetermined depth from the surface of a first substrate mainly composed of a semiconductor, the dividing layer enabling a semiconductor substrate having a thickness corresponding to the predetermined depth to be separated from the first substrate; a fixing portion forming step of forming, after the dividing layer forming step, a fixing portion for fixing the portion of the first substrate that will become the semiconductor substrate to the second substrate in an annular shape under an atmosphere at a pressure lower than a predetermined pressure, thereby sealing the inside of the annular portion; a dividing step of dividing the first substrate at the dividing layer under the atmosphere of the predetermined pressure after the fixing portion forming step; Equipped with In the dividing layer forming step, after forming the dividing layer, a peripheral portion of the first substrate is cut off; A method for manufacturing a semiconductor device, in which the fixing portion forming step uses the first substrate, whose peripheral portion has been cut off in the dividing layer forming step, as a new first substrate, and forms the fixing portion around the entire peripheral portion of the part of the new first substrate that will become the semiconductor substrate.
8. A dividing layer forming step of forming a dividing layer at a position at a predetermined depth from the surface of a first substrate mainly composed of a semiconductor, the dividing layer enabling a semiconductor substrate having a thickness corresponding to the predetermined depth to be separated from the first substrate; a fixing portion forming step of forming, after the dividing layer forming step, a fixing portion for fixing the portion of the first substrate that will become the semiconductor substrate to the second substrate in an annular shape under an atmosphere at a pressure lower than a predetermined pressure, thereby sealing the inside of the annular portion; a dividing step of dividing the first substrate at the dividing layer under the atmosphere of the predetermined pressure after the fixing portion forming step; Equipped with a semiconductor device manufacturing method, wherein after the dividing step, the semiconductor substrate and the second substrate are heat-treated in an atmosphere at the predetermined pressure or an atmosphere at a pressure higher than the predetermined pressure, thereby bonding the semiconductor substrate and the second substrate together in an area inside the bonding portion.
9. A dividing layer forming step of forming a dividing layer at a position at a predetermined depth from the surface of a first substrate whose main component is a semiconductor, the dividing layer enabling a semiconductor substrate having a thickness corresponding to the predetermined depth to be separated from the first substrate; a fixing portion forming step of forming, after the dividing layer forming step, a fixing portion for fixing the portion of the first substrate that will become the semiconductor substrate to the second substrate in an annular shape under an atmosphere at a pressure lower than a predetermined pressure, thereby sealing the inside of the annular portion; a dividing step of dividing the first substrate at the dividing layer under the atmosphere of the predetermined pressure after the fixing portion forming step; Equipped with A method for manufacturing a semiconductor device, in which the fixing portion forming step forms the fixing portion around the entire periphery of each device region provided in a portion of the first substrate that will become the semiconductor substrate.
10. The fixing portion forming step includes: a metal layer forming step of forming a metal layer on a surface of the first substrate or a surface of the second substrate; a laser light irradiation step of interposing the metal layer between the first substrate and the second substrate, and irradiating portions of the metal layer on the periphery of each of the device regions with laser light in that state to heat the portions and form the fixed portions; The method for manufacturing a semiconductor device according to claim 9, comprising:
11. a device formation step of fabricating at least some of the elements to be included in a semiconductor device in each of the device regions provided in the semiconductor substrate after the dividing step; a cutting step of holding the semiconductor substrate and the second substrate on a holding sheet in a position where the semiconductor substrate faces the holding sheet after the device forming step, and cutting the semiconductor substrate and the second substrate in this state at a position between the fixing portions formed in two adjacent device regions, respectively; The method for manufacturing a semiconductor device according to claim 9 or 10, further comprising: