Method for manufacturing semiconductor device

Abstract

As an example, the present invention relates to a hybrid bonding method using an organic insulating film as an insulating film. In a hybrid bonding method using an organic insulating film, a thermal expansion difference is sometimes generated between a terminal electrode made of metal or the like and the organic insulating film by heating during bonding, so that a predetermined step (D) needs to be provided in advance between the front end surface of the terminal electrode and the surface of the organic insulating film. In the present invention, in order to set the step (D), the surface of the semiconductor substrate (100) is irradiated with plasma (as an example, argon plasma). In this plasma irradiation, the organic insulating film (102) is etched by plasma such that the surface (102a) of the organic insulating film (102) of the semiconductor substrate (100) is closer to the inner side than the tip surface (103a) of the electrode (103).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a semiconductor device. Background Art

[0002] Patent Documents 1 to 3 disclose an example of a hybrid bonding (HB) technology for a wafer-to-wafer (W2W) bonding process or a chip-on-wafer (CoW) bonding process in three-dimensional mounting of semiconductor devices.

[0003] Previous technical literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-197430

[0006] Patent Document 2: Japanese Patent Application Publication No. 2021-197431

[0007] Patent Document 3: Japanese Patent Application No. 2018-528622 Summary of the invention

[0008] Technical issues to be solved by the invention

[0009] In the hybrid bonding technology described in Patent Document 1, etc., an organic material (resin) is sometimes used in the insulating portion. In this case, the position of the surface may be offset due to the difference in thermal expansion coefficient (linear thermal expansion coefficient CTE) between the metal material constituting the terminal electrode and the organic material constituting the insulating portion, thereby causing poor bonding in the insulating portion or the terminal electrode. Therefore, a method for easily presetting a desired step difference between the surface of an organic insulating film of a semiconductor substrate used for hybrid bonding and the front end face of an electrode is desired.

[0010] An object of the present invention is to provide a method for manufacturing a semiconductor device that can easily provide a desired step between the surface of an organic insulating film of a semiconductor substrate and the front end face of an electrode in a hybrid bonding method using an organic insulating film.

[0011] Means for solving technical problems

[0012] [1] A method for manufacturing a semiconductor device according to one aspect of the present invention includes the steps of: preparing a first semiconductor substrate having a first substrate body, a first organic insulating film provided on one surface of the first substrate body, and a first electrode; and irradiating a surface of the first semiconductor substrate with plasma. In the step of irradiating with plasma, at least the first organic insulating film is etched by plasma in such a manner that a surface of the first organic insulating film is closer to the first substrate body than a front end surface of the first electrode.

[0013] In the manufacturing method of the semiconductor device, at least the first organic insulating film is etched by plasma in such a manner that the surface of the first organic insulating film is closer to the first substrate body than the front end face of the first electrode. In this case, although both the first organic insulating film and the first electrode are irradiated with plasma, the amount of etching by plasma is different due to the difference in elastic modulus between the two. Therefore, according to the manufacturing method, by changing the plasma conditions according to the materials of the organic insulating film and the electrode or the difference in elastic modulus between the two, it is possible to easily provide a desired step difference between the surface of the organic insulating film of the semiconductor substrate and the front end face of the electrode in the hybrid bonding method using the organic insulating film.

[0014] [2] In the method for manufacturing a semiconductor device of [1] above, in the plasma irradiation step, the first semiconductor substrate is preferably irradiated with argon plasma. In this case, it is easier to adjust the step between the surface of the organic insulating film of the semiconductor substrate and the front end surface of the electrode to a desired value.

[0015] [3] In the method for manufacturing a semiconductor device according to [1] or [2], in the step of irradiating plasma, the flow rate of the plasma gas is preferably 3.38×10 -2 Pa·m 3 / sec(20sccm)~1.69Pa·m 3 / sec(1000sccm). By setting the flow rate of plasma gas to 3.38×10 -2 Pa·m 3 / sec (20 sccm) or more can promote the etching by plasma so that the step difference between the surface of the organic insulating film of the semiconductor substrate and the front end face of the electrode becomes the desired value at an early stage. On the other hand, by making the flow rate of the plasma gas 1.69 Pa·m 3 / sec (1000 sccm) or less, it is possible to suppress the roughening of the surface of the organic insulating film and the electrode caused by plasma.

[0016] [4] In the method for manufacturing a semiconductor device according to any one of [1] to [3], in the step of irradiating plasma, the plasma output is preferably 10 W to 1000 W. By setting the plasma output to 10 W or more, etching by plasma can be promoted so that the step between the surface of the organic insulating film of the semiconductor substrate and the front end face of the electrode can be made to reach a desired value at an early stage. On the other hand, by setting the plasma output to 1000 W or less, roughening of the surface of the organic insulating film and the electrode caused by plasma can be suppressed.

[0017] [5] In the method for manufacturing a semiconductor device according to any one of [1] to [4], in the step of irradiating plasma, the plasma treatment time is preferably 30 seconds or longer. By setting the plasma treatment time to 30 seconds or longer, the etching by plasma can be promoted so that the step between the surface of the organic insulating film of the semiconductor substrate and the front end surface of the electrode can be made to reach a desired value at an early stage.

[0018] [6] In the method for manufacturing a semiconductor device according to any one of [1] to [5] above, the elastic modulus of the first organic insulating film is preferably not more than 7.5 GPa. In this case, a desired step can be easily provided between the surface of the organic insulating film of the semiconductor substrate and the front end surface of the electrode.

[0019] [7] In the method for manufacturing a semiconductor device according to any one of [1] to [6] above, in the plasma irradiation step, the surface of the first semiconductor substrate may be irradiated with plasma so that the step distance between the surface of the first organic insulating film and the front end face of the first electrode is 40 nm or more and 100 nm or less. In this case, when the first semiconductor substrate is bonded to another substrate by hybrid bonding, the offset between the surface of the first organic insulating film and the front end face of the first electrode is reduced due to thermal expansion, and the bonding of the first semiconductor substrate to the other substrate can be performed more reliably.

[0020] [8] In the method for manufacturing a semiconductor device according to any one of [1] to [6] above, in the plasma irradiation step, the surface of the first semiconductor substrate may be irradiated with plasma so that the step distance between the surface of the first organic insulating film and the front end face of the first electrode is 60 nm or more and 80 nm or less. In this case, when the first semiconductor substrate is bonded to another substrate by hybrid bonding, the offset between the surface of the first organic insulating film and the front end face of the first electrode is reduced due to thermal expansion, and the bonding of the first semiconductor substrate to the other substrate can be performed more reliably.

[0021] [9] The method for manufacturing a semiconductor device according to any one of [1] to [8] further includes a step of grinding a first organic insulating film and a first electrode disposed on one side of a first semiconductor substrate, and the step of grinding the first semiconductor substrate is preferably performed before the step of irradiating plasma. In the grinding step, the surface roughness of the surface of the first organic insulating film of the first semiconductor substrate and the front end surface of the first electrode can be reduced, and the step difference can be made to a desired value, but it is difficult to adjust a fine step difference. Therefore, in a case where the desired step difference amount cannot be obtained in the grinding step, the step difference amount can be further adjusted by performing the step of irradiating plasma after the grinding step. Thus, according to this manufacturing method, it is possible to reduce poor bonding in hybrid bonding.

[0022]

[10] In the method for manufacturing a semiconductor device of [9] above, in the step of polishing the first semiconductor substrate, the polishing is preferably performed in such a manner that the surface roughness Ra of each surface of the first organic insulating film and the first electrode becomes 5 nm or less, preferably 1 nm or less. In this case, bonding defects in hybrid bonding can be more reliably reduced.

[0023]

[11] The method for manufacturing a semiconductor device of any one of [1] to

[10] above may further include the following steps: preparing a second semiconductor substrate, the second semiconductor substrate having a second substrate body, a second organic insulating film and a second electrode provided on one side of the second substrate body; aligning the second electrode of the second semiconductor substrate relative to the first electrode of the first semiconductor substrate; and heating and pressurizing the first semiconductor substrate and the second semiconductor substrate so that the first organic insulating film and the second organic insulating film are bonded to each other, and the first electrode and the second electrode are bonded to each other. In this case, the first semiconductor substrate and the second semiconductor substrate can be bonded by hybrid bonding. In addition, the hybrid bonding described herein can be a hybrid bonding used in any of a wafer-to-wafer (W2W) bonding process and a chip-on-wafer (CoW) bonding process.

[0024]

[12] The method for manufacturing a semiconductor device of

[11] further includes a step of irradiating the surface of the second semiconductor substrate with plasma. In the step of irradiating the second semiconductor substrate with plasma, at least the second organic insulating film can be etched by plasma in such a manner that the surface of the second organic insulating film is closer to the second substrate body than the front end face of the second electrode. In this case, by changing the plasma conditions according to the materials of the organic insulating film and the electrode or the difference in elastic modulus between the two, it is possible to easily provide a desired step between the surface of the organic insulating film of the semiconductor substrate and the front end face of the electrode even in the second semiconductor substrate.

[0025]

[13] In the method for manufacturing a semiconductor device of any one of [1] to

[12] above, the resin material contained in the first organic insulating film may include bismaleimide, polyimide, a polyimide precursor, polyamide-imide, benzocyclobutene (BCB), polybenzoxazole (PBO) or a PBO precursor. Since these materials are liquid or soluble in a solvent, it is easy to make the first organic insulating film by, for example, a spin coating method, and it is easy to form a thin film. In addition, these materials have high heat resistance and can withstand the high temperature when the first semiconductor substrate is bonded to the second semiconductor substrate, and the substrates can be bonded to each other more reliably. In addition, the second organic insulating film of the second semiconductor substrate may be formed by including the above-mentioned organic material. Even in this case, the same effect can be exerted.

[0026] Effects of the Invention

[0027] According to the present invention, in the hybrid bonding method using an organic insulating film, a desired step can be easily provided between the surface of the organic insulating film of the semiconductor substrate and the front end surface of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a cross-sectional view schematically showing an example of a semiconductor device (CoW) manufactured by a method for manufacturing a semiconductor device according to an embodiment of the present invention.

[0029] Figure 2 It means manufacturing Figure 1 A method of manufacturing a semiconductor device is shown in FIG.

[0030] Figure 3 It is a schematic representation of the manufacturing Figure 2 A diagram of a plasma process in a method of manufacturing a semiconductor device is shown.

[0031] Figure 4 It means manufacturing Figure 2 A diagram showing a bonding method in a method of manufacturing a semiconductor device. DETAILED DESCRIPTION

[0032] Hereinafter, several embodiments of the present invention will be described in detail with reference to the accompanying drawings as needed. In the following description, the same figure marks are marked on the same or equivalent parts, and repeated descriptions are omitted. In addition, regarding the positional relationship such as up, down, left, and right, unless otherwise specified, the positional relationship shown in the accompanying drawings shall be used as a reference. In the description and claims of this specification, when terms such as "left", "right", "front", "back", "up", "down", "above", and "below" are used, these are intended to illustrate and do not necessarily mean that it will always be this relative position. In addition, the dimensional ratios of the accompanying drawings are not limited to the ratios shown in the drawings.

[0033] In this specification, the term "layer" includes not only a structure of a shape formed on the entire surface but also a structure of a shape formed on a part when viewed from above. Also, in this specification, the term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved. Also, a numerical range represented by "to" indicates a range that includes the numerical values ​​recorded before and after "to" as the minimum and maximum values, respectively.

[0034] (Structure of Semiconductor Device)

[0035] Figure 1 1 is a cross-sectional view schematically showing an example of a semiconductor device manufactured by the manufacturing method according to the present embodiment. Figure 1 As shown, the semiconductor device 1 is, for example, an example of a semiconductor package, which includes a plurality of semiconductor chips 10 and a semiconductor substrate 20, and has a chip-on-wafer (CoW) structure. The plurality of semiconductor chips 10 are produced by singulating a semiconductor substrate 100 described later by cutting. The plurality of semiconductor chips 10 are mounted on the semiconductor substrate 20 to form a three-dimensional mounting structure. The semiconductor substrate 20 may be, for example, a substrate in which a plurality of semiconductor chips such as an LSI (Large scale Integrated Circuit) chip or a CMOS (Complementary Metal Oxide Semiconductor) sensor are formed in a portion corresponding to each semiconductor chip 10. Each semiconductor chip 10 may be, for example, a semiconductor chip such as an LSI or a memory. The plurality of semiconductor chips 10 and the semiconductor substrate 20 are hybrid-bonded to each other as described later, and the respective terminal electrodes and the insulating film surrounding them are firmly and finely bonded to each other without shifting their positions. The semiconductor device 1 can be further singulated into a separate semiconductor device, which has Figure 1 The structure shown further includes one semiconductor chip 10 that is singulated and a substrate portion that is a portion of a semiconductor substrate 20 corresponding to the one semiconductor chip 10. The manufacturing method according to the present embodiment can be applied to a W2W bonding process, and in this case, semiconductor substrates are bonded to each other.

[0036] (Method for manufacturing semiconductor device)

[0037] Next, refer to Figure 2 and Figure 4 , a method for manufacturing the semiconductor device 1 is described. Figure 2 It is used to manufacture Figure 1 A method of manufacturing a semiconductor device is shown in FIG. Figure 3 It is schematically indicated Figure 2 A diagram of a plasma process in a method of manufacturing a semiconductor device is shown. Figure 4 Yes means Figure 2 A diagram showing a bonding method in a method of manufacturing a semiconductor device.

[0038] The semiconductor device 1 can be manufactured through, for example, the following steps (a) to (j).

[0039] (a) A step of preparing a semiconductor substrate 100 corresponding to the plurality of semiconductor chips 10 and including a substrate body 101 , an insulating film 102 , and a plurality of electrodes 103 .

[0040] (b) A step of preparing a semiconductor substrate 200 including a substrate body 201 , an insulating film 202 , and a plurality of electrodes 203 .

[0041] (c) A step of polishing the insulating film 102 of the semiconductor substrate 100 together with the electrode 103 .

[0042] (d) A step of polishing the insulating film 202 of the semiconductor substrate 200 together with the electrode 203 .

[0043] (e) A step of irradiating the insulating film 102 and the electrode 103 of the semiconductor substrate 100 with plasma.

[0044] (f) A step of irradiating the insulating film 202 and the electrode 203 of the semiconductor substrate 200 with plasma.

[0045] (g) A step of singulating the semiconductor substrate 100 to obtain a plurality of semiconductor chips 10 , each of which includes an insulating film portion 102 b corresponding to the insulating film 102 and an electrode 103 .

[0046] (h) A step of aligning the positions of the electrodes 103 of the plurality of semiconductor chips 10 with respect to the electrodes 203 of the semiconductor substrate 200 is performed.

[0047] (i) A step of bonding the insulating film portions 102 b of the plurality of semiconductor chips 10 and the insulating film 202 of the semiconductor substrate 200 to each other.

[0048] (j) A step of bonding the electrodes 103 of each of the plurality of semiconductor chips 10 to the electrodes 203 of the semiconductor substrate 200 .

[0049] [Step (a) and Step (b)]

[0050] Step (a) is a step of preparing a semiconductor substrate 100 (second semiconductor substrate), which is a silicon substrate corresponding to a plurality of semiconductor chips 10 and on which an integrated circuit composed of semiconductor elements and wirings connecting these elements is formed. Figure 2 As shown in (a), on one side 101a of a substrate body 101 (second substrate body) composed of silicon or the like, a plurality of electrodes 103 (second electrodes) composed of copper or aluminum or the like are provided at predetermined intervals, and an insulating film 102 (second organic insulating film) formed of an inorganic material or an organic material is provided. The electrode 103 is a terminal electrode for allowing an integrated circuit or the like formed on the semiconductor substrate 100 to penetrate the insulating film 102 and be exposed to the outside. The insulating film 102 may be provided on one side 101a of the substrate body 101 and then the plurality of electrodes 103 may be provided, or the plurality of electrodes 103 may be provided on one side 101a of the substrate body 101 and then the insulating film 102 may be provided.

[0051] Step (b) is a step of preparing a semiconductor substrate 200 (first semiconductor substrate), which is a silicon substrate on which an integrated circuit composed of semiconductor elements and wirings connecting these elements is formed. Figure 2 As shown in (a), on one side 201a of a substrate body 201 (first substrate body) composed of silicon or the like, a plurality of electrodes 203 (first electrodes) composed of copper or aluminum or the like are provided at predetermined intervals, and an insulating film 202 (first organic insulating film) formed of an inorganic material or an organic material is provided. The electrode 203 is a terminal electrode for allowing an integrated circuit or the like formed on the semiconductor substrate 200 to penetrate the insulating film 202 and be exposed to the outside. The insulating film 202 may be provided on one side 201a of the substrate body 201 and then the plurality of electrodes 203 may be provided, or the plurality of electrodes 203 may be provided on one side 201a of the substrate body 201 and then the insulating film 202 may be provided.

[0052] The insulating film 102 and the insulating film 202 used in the steps (a) and (b) are composed of organic materials. The organic materials used for the insulating film are, for example, polyimide, a polyimide precursor (for example, polyimide amide ester or polyamic acid), polyamide-imide, benzocyclobutene, i.e., BCB, polybenzoxazole, i.e., PBO or a PBO precursor. These organic materials have a lower elastic modulus than inorganic materials such as silicon oxide (SiO2) and are soft materials. By using such an organic material, when the insulating films are bonded to each other in the step (i) described later, even if there are fine foreign matter (debris) on the insulating film, it will be absorbed into the insulating film to prevent poor bonding caused by foreign matter, so that the insulating films can be bonded to each other reliably. The elastic modulus of the organic material constituting the insulating film 102 and the insulating film 202 can be, for example, less than 7.0 GPa, less than 5.0 GPa, less than 3.5 GPa, less than 3.0 GPa, or less than 2.5 GPa. The elastic modulus described herein refers to Young's modulus. Since the insulating film is composed of an organic material having such an elastic modulus, the thickness of the insulating film can be easily thinned by plasma irradiation in the steps (e) and (f) described later. In addition, the organic material constituting the insulating film 102 and the insulating film 202 preferably has a thermal expansion coefficient of less than 70 ppm / K, and more preferably less than 50 ppm / K.

[0053] Furthermore, since the organic material used for the insulating film is in liquid form or soluble in a solvent, each insulating film can be easily formed into a thin film by a spin coating method or the like. In addition, since these organic materials are heat-resistant, they can withstand the temperature (e.g., a high temperature of 300° C. or higher) when the electrode 103 and the electrode 203 are joined in the later-described step (j), so that the joining of the insulating films to each other will not be degraded by the high temperature. In addition, as an organic material constituting the insulating film 102 and the insulating film 202, a photosensitive resin, a thermosetting non-conductive film (NCF: Non Conductive Film) or a thermosetting resin can be used. The organic material can be a bottom filling material. In addition, the insulating film 102 and the insulating film 202 can be an insulating film containing both an inorganic material and an organic material, or one insulating film can be formed of an inorganic material and the other insulating film can be formed of an organic material. The inorganic material used for the insulating film is, for example, silicon oxide (SiO2).

[0054] The thickness of the insulating film 102 can be 20 μm or less. By making the thickness of the insulating film 102 thin enough, the wiring formed by the electrode 103 can be made into a finer structure. For example, the minimum size (electrode width) of the electrode 103 formed in the insulating film 102 is determined by the thickness of the insulating film 102 and the aspect ratio of the photosensitive material used. When the aspect ratio of the photosensitive material is, for example, 1:1 (opening width: depth), the electrode width of the electrode 103 can be set to 20 μm or less by making the thickness of the insulating film 102 less than 20 μm. In addition, the thickness of the insulating film 102 can be thicker than 20 μm. In this case, in the step (i) described later, when the insulating films are bonded to each other, more foreign matter can be buried in the resin insulating film 102, so that the insulating films can be bonded to each other more reliably. In addition, the adhesion between the insulating films can also be improved by using any resin insulating film to relieve the stress when bonding the insulating films to each other.

[0055] In addition, the thickness of the insulating film 102 can be 4 μm or more. In this case, by burying tiny foreign matter in the resin insulating film, even if it is assumed that tiny foreign matter remains, the connection between the insulating film 102 and the insulating film 202 can be made good. For example, the size of the foreign matter that can be buried in the insulating film 102 is determined by the thickness of the resin insulating film 102. When the thickness of the insulating film 102 is, for example, 4 μm, a foreign matter with a diameter or width of 4 μm can be buried in the insulating film 102. That is, according to this manufacturing method, even if there are debris with a thickness less than that of the insulating film 102, by burying the debris in the resin insulating film, the connection between the insulating film 102 and the insulating film 202 can be made good. In addition, the thickness of the insulating film 202 can be less than 20 μm, thicker than 20 μm, or more than 4 μm, similar to the insulating film 102. As described above, the insulating film 202 can bury debris.

[0056] [Step (c) and Step (d)]

[0057] Step (c) is a step of grinding the semiconductor substrate 100. In step (c), the surface of the insulating film 102 provided with the electrode 103 is ground using a CMP (Chemical Mechanical Polishing) method. This grinding is preferably performed before step (e) of irradiating plasma. This is because the surface of the insulating film 102 is sometimes roughened due to the plasma irradiation in step (e), so the average roughness of the surface of the insulating film 102 is reduced in advance before hybrid bonding. By this grinding, the average roughness of the surface of the insulating film 102 is made less than 5 nm, preferably less than 1 nm, so that hybrid bonding described later can be performed. By this grinding, debris on the surface of the semiconductor substrate 100 can be removed. In addition, in this grinding step, a part of the step difference between the surface 102a of the insulating film 102 and the front end face 103a of the electrode 103 can be formed.

[0058] Step (d) is a step of grinding the semiconductor substrate 200. In step (d), the surface of the insulating film 202 provided with the electrode 203 is ground using the CMP method. This grinding is preferably performed before step (f). This is because, similar to step (c), the surface of the insulating film 202 is sometimes roughened due to the plasma irradiation in step (f), so the average roughness of the surface of the insulating film 202 is reduced before hybrid bonding. By this grinding, the average roughness of the surface of the insulating film 202 is made less than 5nm, preferably less than 1nm, so that hybrid bonding described later can be performed. By this grinding, debris on the surface of the semiconductor substrate 200 can be removed. In addition, in this grinding process, a part of the step difference between the surface 202a of the insulating film 202 and the front end face 203a of the electrode 203 can be formed.

[0059] In step (c) and step (d), the insulating film 102 may be ground to have the same thickness as the insulating film 202, but, for example, the insulating film 102 may be ground to have a thickness thicker than the insulating film 202. On the other hand, the insulating film 102 may be ground to have a thickness thinner than the insulating film 202. In the case where the insulating film 102 is thicker than the insulating film 202 and is formed of an organic material, the insulating film 102 can contain most of the debris that adheres to the bonding interface when the semiconductor chip 10 is singulated or when the chip is mounted, thereby reducing poor bonding. On the other hand, in the case where the insulating film 102 is thinner than the insulating film 202, the height of the mounted semiconductor chip 10, that is, the semiconductor device 1, can be reduced.

[0060] [Step (e) and Step (f)]

[0061] Step (e) is a step of irradiating the insulating film 102 and the electrode 103 of the semiconductor substrate 100 with plasma. In step (e), Figure 3 (a) and Figure 3 As shown in (b), the insulating film 102 is etched by plasma in such a manner that the surface 102a of the insulating film 102 is closer to the substrate body 101 (the back side) than the front end surface 103a of the electrode 103. The plasma used in step (e) is, for example, argon (Ar) plasma. The semiconductor substrate 100 is placed in a reduced pressure chamber, and the surface of the semiconductor substrate 100 is irradiated with argon plasma for etching. As a condition for argon plasma, the flow rate of the plasma gas (argon gas) can be 3.38×10 -2 Pa·m 3 / sec(20sccm)~1.69Pa·m 3 / sec(1000sccm) (all represent flow rate at 1 atmosphere and 0°C), the plasma output can be 10W to 1000W, and the plasma treatment time can be more than 30 seconds. In addition, the plasma treatment time can be less than 500 seconds. By irradiating with such plasma, Figure 3 As shown in (b), the step difference D between the surface 102a of the insulating film 102 and the front end face 103a of the electrode 103 is made to be greater than 40nm and less than 100nm. Such a step difference D is formed due to the difference in elastic modulus between the insulating film 102 and the electrode 103. Plasma can be irradiated in such a manner that the step difference D between the surface 102a of the insulating film 102 and the front end face 103a of the electrode 103 is greater than 60nm and less than 80nm. From the viewpoint of the oxide film, the plasma used is preferably argon plasma, but it is not limited thereto, and oxygen plasma or the like may also be used.

[0062] Step (f) is a step of irradiating the insulating film 202 and the electrode 203 of the semiconductor substrate 200 with plasma. In step (f), similarly to step (e), the insulating film 202 is etched by plasma in such a manner that the surface 202a of the insulating film 202 is closer to the substrate body 201 (the back side) than the front end surface 203a of the electrode 203. The plasma used in step (f) is, for example, argon (Ar) plasma. The semiconductor substrate 200 is placed in a reduced pressure chamber, and the surface of the semiconductor substrate 200 is irradiated with argon plasma for etching. As a condition for argon plasma, the flow rate of the plasma gas (argon gas) can be 3.38×10 - 2 Pa·m 3 / sec(20sccm)~1.69Pa·m 3 / sec(1000sccm) (all represent flow rate at 1 atmosphere and 0°C), the plasma output can be 10W to 1000W, and the plasma treatment time can be more than 30 seconds. In addition, the plasma treatment time can be less than 500 seconds. By irradiating with such plasma, Figure 3 As shown in step (b), the step difference D between the surface 202b of the insulating film 202 and the front end face 203a of the electrode 203 is made to be greater than 40nm and less than 100nm. Such a step difference D is formed due to the difference in elastic modulus between the insulating film 202 and the electrode 203. Plasma irradiation may be performed in such a manner that the step difference D between the surface 202b of the insulating film 202 and the front end face 203a of the electrode 203 is greater than 60nm and less than 80nm. Plasma other than argon may be used, which is the same as step (e).

[0063] [Step (g)]

[0064] Step (g) is a step of singulating the semiconductor substrate 100 to obtain a plurality of semiconductor chips 10. If the grinding of the semiconductor substrate 200 is completed, in step (g), the ground semiconductor substrate 100 is singulated to obtain a plurality of semiconductor chips 10 (semiconductor substrates) each having an insulating film portion 102b corresponding to the insulating film 102 and at least one electrode 103. In step (g), the semiconductor substrate 100 is arranged on a dicing tape and singulated into a plurality of semiconductor chips 10 from the insulating film 102 toward the substrate body 101 by cutting means such as dicing. When cutting the semiconductor substrate 100, a protective material or the like may be coated on the insulating film 102 and then singulated. Through step (g), as Figure 2 As shown in (b), the insulating film 102 of the semiconductor substrate 100 is divided into insulating film portions 102b corresponding to each semiconductor chip 10. In addition, the substrate body 101 is similarly divided into corresponding substrate portions 101b. As a cutting method for singulating the semiconductor substrate 100, for example, plasma cutting, stealth cutting or laser cutting can be used. In step (g), the singulated semiconductor chips 10 can be cleaned after the singulation by cutting is completed.

[0065] [Process (h)]

[0066] like Figure 2 (c) (left part) and Figure 4 As shown in (a), step (h) is a step of aligning the positions of the electrodes 103 of the plurality of semiconductor chips 10 relative to the electrodes 203 of the semiconductor substrate 200. In step (h), the positions of the semiconductor chips 10 are aligned in such a way that the electrodes 103 of the semiconductor chips 10 are opposed to the corresponding electrodes 203 of the semiconductor substrate 200. Figure 4(a) is magnification Figure 2 (c) is a schematic diagram of a portion of the Figure 4 As shown in (a), before heating for bonding, there are steps between the insulating film portion 102b and the electrode 103 and between the insulating film 202 and the electrode 203. That is, the electrodes 103 and 203 protrude from the surfaces of the insulating film portion 102b and the insulating film 202.

[0067] [Step (i)]

[0068] Step (i) is a step of bonding the insulating film portions 102b of the plurality of semiconductor chips 10 to the insulating film 202 of the semiconductor substrate 200. In step (i), after removing organic matter or metal oxides attached to the surfaces of the semiconductor chips 10 and the semiconductor substrate 200, the semiconductor chips 10 are aligned with respect to the semiconductor substrate 200. When the alignment is completed, Figure 2 (c) (right part) and Figure 4 As shown in (b), the insulating film portions 102b of the plurality of semiconductor chips 10 are bonded to the insulating film 202 of the semiconductor substrate 200 as a hybrid bond. At this time, the insulating film portions 102b of the plurality of semiconductor chips 10 and the insulating film 202 of the semiconductor substrate 200 can be uniformly heated before bonding. By heating for bonding, the insulating film composed of an organic material expands more than the electrode, thereby eliminating the step difference between the insulating film portion 102b and the electrode 103 and the step difference between the insulating film 202 and the electrode 203. In addition, the step difference can be completely eliminated so that the surfaces of the insulating film portion 102b and the electrode 103 become the same surface, and the surfaces of the insulating film 202 and the electrode 203 become the same surface, or a state in which some step differences remain. The temperature difference between the semiconductor chip 10 and the semiconductor substrate 200 during bonding is preferably, for example, less than 10°C. By such heating bonding at a uniform temperature, the insulating bonding portion formed by bonding the insulating film portion 102b and the insulating film 202 is formed, and the plurality of semiconductor chips 10 are mechanically firmly mounted on the semiconductor substrate 200. Furthermore, since the heat bonding is performed at a uniform temperature, it is not easy to cause positional deviation of the bonding portion, and high-precision bonding can be performed. In this mounting stage, the electrodes 103 of the semiconductor chip 10 and the electrodes 203 of the semiconductor substrate 200 are separated from each other and are not connected (but are aligned). In addition, the bonding of the semiconductor chip 10 and the semiconductor substrate 200 can be performed by other bonding methods, such as bonding by room temperature bonding.

[0069] [Step (j)]

[0070] Step (j) is a step of bonding the electrodes 103 of each of the plurality of semiconductor chips 10 to the electrodes 203 of the semiconductor substrate 200. In step (j), Figure 2 As shown in (d), when the bonding of step (i) is completed, a predetermined heat H or pressure or both are applied to bond the electrodes 103 of the plurality of semiconductor chips 10 to the electrodes 203 of the semiconductor substrate 200 as a mixed bond. When the electrodes 103 and 203 are made of copper, the annealing temperature in step (j) is preferably above 150°C and below 400°C, and more preferably above 200°C and below 300°C. By this bonding treatment, the electrode bonding portion where the electrode 103 is bonded to the corresponding electrode 203 is formed, and the electrodes 103 and 203 are mechanically and electrically firmly bonded. In addition, the electrode bonding of step (j) is performed after the bonding of step (i), but it can also be performed simultaneously with the bonding of step (i). Then, all the semiconductor chips 10 are bonded to the semiconductor substrate 200, thereby obtaining Figure 1 The semiconductor device 1 is shown.

[0071] Thus, it is possible to obtain a semiconductor device 1 in which a plurality of semiconductor chips 10 are electrically and mechanically arranged at predetermined positions on a semiconductor substrate 200 with high precision. Figure 1 The semiconductor device (CoW) having the structure shown is singulated, and each semiconductor device including one semiconductor chip 10 and a portion of the semiconductor substrate 200 corresponding to the one semiconductor chip 10 is formed separately.

[0072] As described above, according to the method for manufacturing a semiconductor device according to the present embodiment, in steps (e) and (f), the insulating films 102 and 202 are etched by plasma in such a manner that the surface of the insulating films 102 and 202 is closer to the substrate body 101 and 201 than the front end faces of the electrodes 103 and 203. In this case, although the insulating films 102 and 202 and the electrodes 103 and 203 are irradiated with plasma, the amount of etching by plasma is different due to the difference in elastic modulus between the two. Therefore, according to this manufacturing method, by changing the plasma conditions according to the materials of the organic insulating film and the electrode or the difference in elastic modulus between the two, in the hybrid bonding method using the insulating films 102 and 202, it is possible to easily provide a desired step D between the surface of the insulating film 202 of the semiconductor substrate 100 and 200 and the front end faces of the electrodes 103 and 203.

[0073] In the method for manufacturing a semiconductor device according to the present embodiment, in steps (e) and (f), argon plasma is preferably irradiated on the semiconductor substrate 100, 200. In this case, it is easier to adjust the step between the surface of the insulating film 102, 202 of the semiconductor substrate 100, 200 and the front end surface of the electrode 103, 203 to a desired value.

[0074] In the method for manufacturing a semiconductor device according to the present embodiment, in steps (e) and (f), the flow rate of the plasma gas is preferably 3.38×10 -2 Pa·m 3 / sec(20sccm)~1.69Pa·m 3 / sec(1000sccm). By setting the flow rate of plasma gas to 3.38×10 -2 Pa·m 3 / sec (20 sccm) or more can promote the etching by plasma so that the step difference between the surface of the insulating film 102, 202 of the semiconductor substrate 100, 200 and the front end surface of the electrode 103, 203 becomes the desired value at an early stage. On the other hand, by setting the flow rate of the plasma gas to 1.69 Pa·m 3 / sec (1000 sccm) or less, the roughening of the surfaces of the insulating films 102 and 202 and the electrodes 103 and 203 due to plasma can be suppressed.

[0075] In the method for manufacturing a semiconductor device according to the present embodiment, in steps (e) and (f), the plasma output is preferably 10 W to 1000 W. By setting the plasma output to 10 W or more, etching by plasma can be promoted so that the step between the surface of the insulating film 102, 202 of the semiconductor substrate 100, 200 and the front end surface of the electrode 103, 203 becomes a desired value at an early stage. On the other hand, by setting the plasma output to 1000 W or less, roughening of the surface of the insulating film 102, 202 and the electrode 103, 203 by plasma can be suppressed.

[0076] In the method for manufacturing a semiconductor device according to the present embodiment, in steps (e) and (f), the plasma treatment time is preferably 30 seconds or longer. By setting the plasma treatment time to 30 seconds or longer, the etching by plasma can be promoted so that the step difference between the surface of the insulating film 102, 202 of the semiconductor substrate 100, 200 and the front end surface of the electrode 103, 203 becomes a desired value at an early stage.

[0077] In the method for manufacturing a semiconductor device according to this embodiment, the elastic modulus of the insulating film 102 , 202 is preferably 7.5 GPa or less. In this case, a desired step can be easily provided between the surface of the insulating film 102 , 202 of the semiconductor substrate 100 , 200 and the front end surface of the electrode 103 , 203 .

[0078] In the method for manufacturing a semiconductor device according to the present embodiment, in steps (e) and (f), the surface of the semiconductor substrates 100 and 200 may be irradiated with plasma so that the step distance between the surface of the insulating film 102 and 202 and the front end surface of the electrode 103 and 203 is 40 nm or more and 100 nm or less. In this case, when the semiconductor substrates 100 and 200 are bonded to each other, the amount of displacement between the surface of the insulating film 102 and 202 and the front end surface of the electrode 103 and 203 is reduced due to thermal expansion, and the semiconductor substrates 100 and 200 can be bonded to each other more reliably.

[0079] In the method for manufacturing a semiconductor device according to the present embodiment, in steps (e) and (f), plasma may be irradiated onto the surface of the semiconductor substrates 100 and 200 so that the step distance between the surface of the insulating film 102 and 202 and the front end surface of the electrode 103 and 203 is 60 nm or more and 80 nm or less. In this case, when the semiconductor substrates 100 and 200 are bonded to each other by hybrid bonding, the offset amount between the surface of the insulating film 102 and 202 and the front end surface of the electrode 103 and 203 is reduced due to thermal expansion, and the semiconductor substrates 100 and 200 can be bonded to each other more reliably.

[0080] The method for manufacturing a semiconductor device according to the present embodiment further includes a step of grinding the insulating film 102, 202 and the electrodes 103, 203 provided on one side of the semiconductor substrate 100, 200. The step of grinding the semiconductor substrate 100, 200 is preferably performed before the steps (e) and (f) of irradiating plasma. By irradiating plasma, the step difference between the surface of the insulating film 102, 202 of the semiconductor substrate 100, 200 and the front end face of the electrode 103, 203 can be made to a desired value, but depending on the output condition of the plasma, the surface roughness of the surface of the insulating film 102, 202 or the front end face of the electrode 103, 203 may sometimes be deteriorated. In hybrid bonding, if the surface roughness of the bonding surface is deteriorated, the bonding in hybrid bonding may be deteriorated. Therefore, in this manufacturing method, the surface roughness of the surface and the front end face that are roughened by plasma irradiation are reduced by pre-grinding. Thus, according to this manufacturing method, bonding defects in hybrid bonding can be reduced. Furthermore, in the grinding steps (c) and (d), the surface roughness of the surface of the organic insulating film of the semiconductor substrate 100, 200 and the front end face of the electrode can be reduced, and the step difference between the surface of the organic insulating film and the front end face of the electrode can be made to be a desired value. However, it is difficult to adjust a fine step difference during grinding. Therefore, in the case where the desired step difference amount is not obtained in the grinding steps (c) and (d), the step difference amount can be further adjusted by performing the plasma irradiation steps (e) and (f) after the grinding steps (c) and (d).

[0081] In the method for manufacturing a semiconductor device according to the present embodiment, in the polishing steps (c) and (d), polishing is preferably performed so that the surface roughness Ra of each surface of the insulating film 102, 202 and the electrode 103, 203 becomes 5 nm or less, preferably 1 nm or less. In this case, bonding defects in hybrid bonding can be more reliably reduced.

[0082] In the method for manufacturing a semiconductor device according to the present embodiment, the resin material contained in the insulating film 102, 202 may include bismaleimide, polyimide, a polyimide precursor, polyamide-imide, benzocyclobutene (BCB), polybenzoxazole (PBO) or a PBO precursor. Since these materials are liquid or soluble in a solvent, it is easy to make the insulating film 102, 202 by, for example, a spin coating method, and it is easy to form a thin film. In addition, since these materials have high heat resistance, they can withstand the high temperature when the semiconductor chip 10 (semiconductor substrate 100) is bonded to the semiconductor substrate 200, so that the substrates can be bonded to each other more reliably.

[0083] The embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments and can be applied to various embodiments. For example, in the above, as a hybrid bonding, the manufacturing method of the semiconductor device is described by taking the CoW bonding process as an example, but the manufacturing method of the semiconductor device involved in this embodiment can also be applied to a wafer-to-wafer (Wafer-to-Wafer, W2W) bonding process. In this case, the semiconductor substrate 100 and the semiconductor substrate 200 that have not been subjected to the step (g) of singulating the first semiconductor substrate by cutting are bonded by hybrid bonding.

[0084] Example

[0085] The present invention is described in more detail below by way of examples, but the present invention is not limited to the examples. The following examples (experimental examples) are examples in which a semiconductor substrate having an organic insulating film and an electrode disposed on one side of a substrate body is prepared, and the semiconductor substrate is irradiated with plasma to test whether the step difference between the surface of the organic insulating film and the front end face of the electrode can be adjusted.

[0086] First, a test wafer corresponding to the semiconductor substrate 100 was prepared. In this preparation, a first polyimide material and a second polyimide material were prepared as materials for the organic insulating film of the test wafer. The first polyimide material had a glass transition temperature of 290°C after curing and a linear expansion coefficient (CTE) of 100 ppm / °C (10 -6 / ℃), and the elastic modulus is 2.5GPa. Regarding the second polyimide material, the glass transition temperature after curing is 267℃, the linear expansion coefficient (CTE) is 75ppm / ℃, and the elastic modulus is 3.1GPa. In addition, the linear expansion coefficient of copper used for the electrode is 16.8ppm / ℃ (10 -6 / ℃), and the elastic modulus is 120GPa.

[0087] Next, as Experimental Example 1, Figure 3 As shown in FIG. 1 , a plurality of electrodes 103, i.e., copper pillars (Cu) of 10 μm square and 6 μm high, are fabricated on a substrate body 101 as a silicon substrate by a semi-additive method. Then, the first polyimide material is spin-coated on the substrate body 101 to cover the electrodes 103, and is cured by baking at 375° C. for 2 hours in a nitrogen atmosphere (refer to FIG. 1 ). Figure 3 Then, the solidified semiconductor substrate 100 is placed in a reduced pressure chamber, and argon plasma is irradiated on the semiconductor substrate 100 under the following plasma conditions (refer to Figure 3 (b)).

[0088] RF output (plasma output): 500W (watt)

[0089] Treatment time (plasma treatment time): 120 seconds

[0090] Ar flow rate (flow rate of plasma gas): 8.45×10 -2 Pa·m 3 / sec(50sccm)

[0091] After plasma irradiation was completed, the step D between the surface of the organic insulating film and the front end face of the electrode, the surface roughness Ra of the surface of the organic insulating film, and the surface roughness Ra of the front end face of the electrode were measured to obtain the following results.

[0092] The step D between the surface of the organic insulating film and the front end of the electrode: 72.4 nm

[0093] Surface roughness Ra of the organic insulating film: 1.5 nm

[0094] Surface roughness of the front end of the electrode Ra: 2.6 mm

[0095] According to the test under the plasma condition of Experimental Example 1, it was confirmed that the step D was within the range of 40 nm to 80 nm (when the elastic modulus was 2.5 GPa) in which the pressure bonding property of the hybrid bonding was good.

[0096] Furthermore, it can be confirmed that the surface roughness Ra of the organic insulating film and the electrode is also suppressed to a low value.

[0097] Next, as Experimental Examples 2 to 6, the first polyimide material having an elastic modulus of 2.5 GPa was used as it is, and the plasma conditions were changed to irradiate the semiconductor substrate 100 with plasma. The conditions other than the plasma irradiation conditions were the same as those of Experimental Example 1. The plasma conditions and test results in Experimental Examples 2 to 6 are shown in Table 1 below. In addition, the evaluation A of the pressure-bonding property in Table 1 indicates that the step difference D is within the range where the pressure-bonding property of the hybrid joint becomes good, as described above.

[0098] [Table 1]

[0099]

[0100] Next, as Experimental Examples 7 to 10, a second polyimide material having an elastic modulus of 3.1 GPa was used, and the plasma conditions were changed to irradiate the semiconductor substrate with plasma. The conditions other than the elastic modulus of the material of the organic insulating film and the plasma irradiation conditions were the same as those in Experimental Example 1. The plasma conditions and test results in Experimental Examples 7 to 10 are shown in Table 2 below. In addition, when the elastic modulus was 3.1 GPa, if the step difference D was in the range of 15 nm to 50 nm, the pressure-bonding property of the hybrid joint became good, which was evaluated as A. In addition, in Experimental Examples 7 to 10, it was confirmed that the surface roughness Ra of the organic insulating film and the electrode could also be suppressed to a lower value.

[0101] [Table 2]

[0102]

[0103] Next, as further experimental examples, Experiments 11 to 17 were conducted. In Experiments 11 to 17, the first polyimide material having an elastic modulus of 2.5 GPa was used as in Experiment 1, and the plasma conditions were changed to irradiate the semiconductor substrate 100 with plasma. The conditions other than the plasma irradiation conditions were the same as in Experiment 1. The plasma conditions and test results in Experiments 11 to 17 are shown in Table 3 below. In Experiments 11 to 17, the plasma conditions were greatly changed compared to Experiment 1 and the tests were conducted.

[0104] [Table 3]

[0105]

[0106]

[0107] As shown in Experimental Examples 11 to 17, it can be confirmed that the step difference D and the surface roughness Ra can be changed (i.e., various adjustments) by changing the plasma conditions. In addition, for semiconductor substrates with insufficient step difference D (e.g., Experimental Example 15) and semiconductor substrates with excessive step difference D (e.g., Experimental Example 17), it is believed that the step difference D and surface roughness Ra can be obtained by CMP or other treatments before plasma treatment, thereby enabling hybrid bonding.

[0108] As described above, according to the above experimental examples, it can be confirmed that when both the organic insulating film and the electrode are irradiated with plasma, the amount of etching by plasma can be made different due to the difference in elastic modulus of the two. In addition, it is confirmed that when such an organic insulating film or the like is subjected to plasma treatment, by changing the plasma conditions according to the materials of the organic insulating film and the electrode or the difference in elastic modulus of the two, a desired step can be easily provided between the surface of the organic insulating film of the semiconductor substrate and the front end face of the electrode in a hybrid bonding method using an organic insulating film.

[0109] Description of Reference Numerals

[0110] 1-semiconductor device, 10-semiconductor chip, 20-semiconductor substrate, 100, 200-semiconductor substrate, 101, 201-substrate body, 101a, 201a-one side, 102, 202-insulating film, 102a, 202a-surface, 102b-insulating film part, 103, 203-electrode, 103a, 203a-front end surface, D-step difference.

Claims

1. A method for manufacturing a semiconductor device, comprising the following steps: preparing a first semiconductor substrate including a first substrate body, a first organic insulating film provided on one surface of the first substrate body, and a first electrode; and irradiating the surface of the first semiconductor substrate with plasma, In the plasma irradiation step, at least the first organic insulating film is etched by the plasma so that the surface of the first organic insulating film is closer to the first substrate body than the front end surface of the first electrode.

2. The method for manufacturing a semiconductor device according to claim 1, wherein: In the plasma irradiation step, argon plasma is irradiated onto the first semiconductor substrate.

3. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein: In the plasma irradiation step, the flow rate of the plasma gas is 3.38×10 -2 Pa·m 3 / sec(20sccm)~1.69Pa·m 3 / sec(1000sccm).

4. The method for manufacturing a semiconductor device according to any one of claims 1 to 3, wherein: In the plasma irradiation step, the plasma output is 10W to 1000W.

5. The method for manufacturing a semiconductor device according to any one of claims 1 to 4, wherein: In the plasma irradiation step, the plasma treatment time is 30 seconds or longer.

6. The method for manufacturing a semiconductor device according to any one of claims 1 to 5, wherein: The elastic modulus of the first organic insulating film is 7.5 GPa or less.

7. The method for manufacturing a semiconductor device according to any one of claims 1 to 6, wherein: In the plasma irradiation step, the surface of the first semiconductor substrate is irradiated with plasma so that a step distance between the surface of the first organic insulating film and the front end surface of the first electrode is not less than 40 nm and not more than 100 nm.

8. The method for manufacturing a semiconductor device according to any one of claims 1 to 6, wherein: In the plasma irradiation step, the surface of the first semiconductor substrate is irradiated with plasma so that a step distance between the surface of the first organic insulating film and the front end surface of the first electrode is 60 nm to 80 nm.

9. The method for manufacturing a semiconductor device according to any one of claims 1 to 8, further comprising a step of polishing the first organic insulating film and the first electrode provided on the one surface of the first semiconductor substrate, The step of polishing the first semiconductor substrate is performed before the step of irradiating the plasma.

10. The method for manufacturing a semiconductor device according to claim 9, wherein: In the step of polishing the first semiconductor substrate, polishing is performed so that the surface roughness Ra of each surface of the first organic insulating film and the first electrode becomes 5 nm or less.

11. The method for manufacturing a semiconductor device according to any one of claims 1 to 10, further comprising the following step: preparing a second semiconductor substrate, the second semiconductor substrate having a second substrate body, a second organic insulating film provided on one surface of the second substrate body, and a second electrode; performing position alignment of the second electrode of the second semiconductor substrate with respect to the first electrode of the first semiconductor substrate; and The first semiconductor substrate and the second semiconductor substrate are heated and pressurized so that the first organic insulating film and the second organic insulating film are bonded to each other and the first electrode and the second electrode are bonded to each other.

12. The method for manufacturing a semiconductor device according to claim 11, further comprising the step of irradiating a surface of the second semiconductor substrate with plasma, In the step of irradiating the second semiconductor substrate with plasma, at least the second organic insulating film is etched by plasma so that the surface of the second organic insulating film is closer to the second substrate body than the front end surface of the second electrode.

13. The method for manufacturing a semiconductor device according to any one of claims 1 to 12, wherein: The resin material included in the first organic insulating film includes bismaleimide, polyimide, a polyimide precursor, polyamideimide, benzocyclobutene (BCB), polybenzoxazole (PBO), or a PBO precursor.

Images