Semiconductor and manufacturing method thereof

Abstract

The invention belongs to the technical field of semiconductor manufacturing, and discloses a semiconductor and a manufacturing method thereof, and the manufacturing method comprises the following steps: an ultrathin wafer A and a substrate wafer are prepared, and the ultrathin wafer A is provided with a front surface on which a chip is formed and a back surface corresponding to the front surface; the ultrathin wafer A and the substrate wafer are bonded through organic bonding glue to obtain a bonded wafer, then the bonded wafer is attached to a UV film, laser cutting, water washing, film expanding, chemical solvent cleaning and wafer picking are conducted in sequence, and a wafer is obtained; bonding the substrate with a solid crystal adhesive and curing the substrate at a specific temperature; and sequentially removing the substrate wafer and the organic bonding glue. The method effectively solves the problems that the film is difficult to adhere before the ultrathin wafer is cut, the UV film stains the back surface of the wafer, the wafer is easy to damage after being cut, the wafer is difficult to pick and the like, and the reliability and the stability of a semiconductor manufactured based on the ultrathin wafer are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a semiconductor and a manufacturing method thereof. Background Art

[0002] In semiconductor manufacturing, wafer dicing and packaging are key processes that determine chip performance and yield. Wafer picking is a crucial step between dicing and packaging, and currently faces technical challenges such as mechanical stress control and clean transfer. The wafer attachment and fixation methods used in the pre-dicing stage (such as UV film application) also have a significant impact on wafer picking, especially when handling ultra-thin wafers.

[0003] The existing pre-treatment process generally fixes the wafer by attaching UV film. This method has certain applicability for wafers of conventional thickness, but has significant defects when used for ultra-thin wafers (≤50μm). On the one hand, the high warpage of ultra-thin wafers makes it impossible to achieve flat fixation through conventional vacuum adsorption methods, and blindly increasing the adsorption force can easily cause wafer damage. On the other hand, the UV film directly contacts the back of the wafer, and there is an inherent contradiction in its viscosity control. The smaller the product chip size, the higher the viscosity requirement of the UV film. Excessive viscosity will affect the subsequent chip picking process. First, sticky substances are likely to remain on the back of the chip after picking; second, the ultra-thin chip needs to withstand greater picking force when it is separated from the UV film, which can easily cause chip damage.

[0004] The existing chip picking process applies a lifting force to the bottom of the chip, separating it from the UV film and increasing the distance between it and adjacent chips. A vacuum pad is then applied to the top of the chip to transfer the chip. However, the mechanical stress generated during chip lifting can easily cause the ultra-thin chip to break, and the transfer process can also easily contaminate and damage the front of the chip. Summary of the Invention

[0005] The present invention aims to improve at least one technical problem in the background technology.

[0006] The present invention provides a semiconductor manufacturing method, comprising the following steps: preparing a wafer A and a substrate wafer, wherein the thickness of the wafer A is 10 μm-50 μm, and the wafer A has a front surface on which a chip is formed and a back surface corresponding to the front surface;

[0007] The substrate wafer includes a first side and a second side;

[0008] The front side is connected to the first side by organic bonding adhesive, thereby bonding wafer A and the substrate wafer to obtain a bonded wafer. The second side is then attached to a UV film, and then laser cutting, the first water flow washing, film expansion, chemical solvent cleaning, and wafer picking are carried out in sequence to obtain a wafer.

[0009] The back surface is bonded to the substrate using a die-bonding adhesive and cured at a first temperature;

[0010] removing the substrate wafer and the organic bonding adhesive in sequence;

[0011] The first temperature is 100°C-400°C, and the curing time does not exceed 2 hours.

[0012] Furthermore, after coating the front surface with organic bonding adhesive, the front surface and the first surface are connected with the organic bonding adhesive, thereby bonding the wafer A and the substrate wafer. The coating thickness of the organic bonding adhesive is 15 μm-25 μm.

[0013] Furthermore, after the front surface and the first surface are bonded together by organic bonding adhesive, a first pressure is applied to bond the wafer A and the substrate wafer, and the first pressure is 0.02 MPa-0.04 MPa.

[0014] Furthermore, the substrate wafer includes one of Si and glass.

[0015] Furthermore, the thickness of the substrate wafer is 100 μm-200 μm.

[0016] Furthermore, the removal of the organic bonding adhesive includes soaking in an organic solvent, the soaking time of the organic solvent is 10 minutes to 30 minutes, and the soaking of the organic solvent is performed at 60° C. to 80° C.

[0017] Furthermore, after soaking in the organic solvent, isopropyl alcohol and water are used for soaking in sequence; the soaking time in isopropyl alcohol is 3 minutes to 10 minutes, and the soaking time in water is 2 minutes to 10 minutes.

[0018] Furthermore, after removing the organic bonding adhesive, plasma treatment is performed.

[0019] Furthermore, the plasma includes oxygen plasma, and the plasma treatment time is 30s-100s.

[0020] The present invention also provides a semiconductor manufactured according to the above manufacturing method.

[0021] The beneficial effects of the present invention: The present invention effectively solves the problems of difficulty in laminating ultra-thin wafers before cutting, UV film contaminating the back of the wafer, easy damage after cleaning after cutting, and difficulty in picking wafers, and significantly improves the reliability and stability of semiconductor manufacturing based on ultra-thin wafers. It is of great significance in improving the yield of semiconductor production, reducing production costs, and ensuring product quality, and has a strong impact on promoting the development of semiconductor manufacturing technology towards higher precision and higher performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a schematic structural diagram of a bonded wafer attached to a UV film in an embodiment of the present invention.

[0024] In the accompanying drawings: 100 - bonding wafer; 110 - wafer A; 111 - front side; 112 - back side; 120 - organic bonding adhesive; 130 - substrate wafer; 131 - first side; 132 - second side; 200 - UV film. DETAILED DESCRIPTION

[0025] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content of the present invention record, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the application's appended claims.

[0026] This embodiment provides a semiconductor manufacturing method, comprising the following steps: preparing a wafer A (in this embodiment, wafer A is GaAs; in some other embodiments, wafer A may be one of Si, GaAsAl, InP, and InGaAs; in this embodiment, wafer A is an ultra-thin wafer with a thickness of 10 μm; in some other embodiments, wafer A is also an ultra-thin wafer with a thickness of 10 μm-50 μm, for example, 15 μm, 20 μm, 30 μm, or 50 μm) and a substrate wafer (in this embodiment, substrate wafer is Si; in some other embodiments, substrate wafer may be glass; in this embodiment, substrate wafer has a thickness of 100 μm; in some other embodiments, substrate wafer may have a thickness of 100 μm-200 μm, for example, 120 μm, 150 μm, or 200 μm; if the substrate wafer is too thin, the protection effect is poor; if the substrate wafer is too thick, the laser cutting effect is affected, and subsequent uniform film expansion may not be achieved). Wafer A has a front side with a chip formed thereon and a back side corresponding to the front side.

[0027] The substrate wafer includes a first side and a second side;

[0028] The front side of wafer A is bonded to the first side of substrate wafer by organic bonding adhesive to obtain a bonded wafer. Subsequently, the second side of substrate wafer is attached to UV film (the schematic diagram of the structure of the bonded wafer attached to UV film in this embodiment is shown in FIG. Figure 1 As shown), laser cutting, first water washing, film expansion, chemical solvent cleaning, and wafer picking are then performed in sequence to obtain wafers;

[0029] The back side of the wafer (the back side of wafer A, which corresponds to the back side of the wafer after laser cutting) is bonded to the substrate using a bonding adhesive (silver paste in this embodiment) and cured at a first temperature.

[0030] removing the substrate wafer and the organic bonding adhesive in sequence;

[0031] The first temperature is 250°C (in some other embodiments, if the solid crystal glue also uses silver paste, the first temperature can be 100°C-250°C, for example, 100°C, 150°C, 200°C; if other solid crystal glue is used, the first temperature can be 100°C-400°C), and the curing time is 1 hour (in some other embodiments, the curing time can be no more than 2 hours, for example, 30 minutes, 90 minutes, 2 hours).

[0032] In traditional semiconductor manufacturing, the back of the wafer is attached to a UV film by vacuum adsorption before laser cutting to facilitate subsequent cutting. This method is suitable for wafers of conventional thickness (≥100μm), but when used for ultra-thin wafers (thickness ≤50μm), the ultra-thin wafer itself has a high degree of warpage. In order to make it adsorb flat, the vacuum adsorption force needs to be increased. However, excessive vacuum adsorption force will directly cause problems such as wafer damage. In addition, the smaller the preset wafer cutting size, the higher the viscosity requirement for the UV film, and the high viscosity of the UV film affects the subsequent chip picking. First, after picking, sticky substances are likely to remain on the back of the chip (the chip is obtained by wafer cutting); second, the ultra-thin chip (obtained by ultra-thin wafer cutting) needs to withstand greater picking force when it is separated from the UV film, which can easily cause chip damage.

[0033] In this embodiment, the front side of wafer A is first connected to the first side of the substrate wafer through an organic bonding adhesive, thereby bonding wafer A and the substrate wafer to obtain a bonded wafer. Figure 1 As shown in the figure, the front of the bonded wafer is the back of wafer A, and the back of the bonded wafer is the second side of the substrate wafer. The second side is then attached to the UV film, eliminating the need for the wafer to directly contact the UV film, completely avoiding potential contamination of the wafer backside by the UV film.

[0034] In this embodiment, during laser cutting, the front side of wafer A is no longer used as a cutting surface due to bonding with the substrate wafer. Instead, the back side of wafer A is used as the cutting surface, thereby avoiding contamination and burning of the front side of the wafer by laser cutting, which may affect the yield of the chip.

[0035] In this embodiment, silver paste is used to bond the back side of the chip to the substrate at the first temperature. At the same time, the organic bonding adhesive will soften at this temperature (in some other embodiments, when the first temperature is 100°C-250°C, the organic bonding adhesive will also soften). Therefore, in the subsequent removal of the substrate wafer, it can be removed by gently pushing it with tweezers or a bonding robot arm. The operation is simple and convenient.

[0036] In this embodiment, after the organic bonding adhesive is coated on the front side, the front side (of wafer A) is connected to the first side (of the substrate wafer) through the organic bonding adhesive, thereby bonding wafer A and the substrate wafer. The coating thickness of the organic bonding adhesive is 20 μm (in some other embodiments, the coating thickness of the organic bonding adhesive can be 15 μm-25 μm, for example, 15 μm, 18 μm, 25 μm; if the coating thickness of the organic bonding adhesive is too small, the buffer layer is too thin, the risk of bonding between the thin sheet and the substrate sheet is high, and the subsequent removal of the substrate sheet is difficult; if the coating thickness of the organic bonding adhesive is too large, the heat generated by laser cutting will partially melt the organic bonding adhesive, which may cause the chip to slip during cutting). The coating of the organic bonding adhesive can be done by spin coating or spraying. In this embodiment, the organic bonding adhesive has a certain coating thickness, which can protect the front side of the chip from damage when the substrate wafer is gently pushed to be removed.

[0037] In this embodiment, after the front side (of wafer A) and the first side (of the substrate wafer) are connected by organic bonding glue, a first pressure is applied to bond wafer A and the substrate wafer. In this embodiment, applying the first pressure can make the bonding between wafer A and the substrate wafer more flat. The first pressure is 0.02MPa (in some other embodiments, the first pressure can be 0.02MPa-0.04MPa, such as 0.025MPa, 0.03MPa, 0.04MPa; if the first pressure is too large, the thin wafer cannot withstand it and cracks will occur; if the first pressure is too small, the flatness of the bonding will be affected, which will directly affect the subsequent cutting quality and lead to problems such as crooked cutting or abnormal image recognition).

[0038] In this embodiment, the organic bonding adhesive is KS1000-2 (supplier: Shanghai Feikai Materials Technology Co., Ltd.).

[0039] In this embodiment, before laser cutting, laser cutting protection liquid is spin-coated on the back side of wafer A, which serves as the cutting surface, to further prevent high temperature and hot melt generated by laser cutting from causing damage and contamination to the wafer.

[0040] In this embodiment, after laser cutting, the first water flow flushing is first performed to remove the laser cutting protective liquid and part of the hot melt. In this embodiment, the water pressure of the first water flow flushing is 0.5MPa (in some other embodiments, the first water pressure of the first water flow flushing can be 0.3-0.9MPa, such as 0.3MPa, 0.6MPa, 0.9MPa), and the time of the first water flow flushing is 10min (in some other embodiments, the time of the first water flow flushing can be 10min-20min, such as 12min, 15min, 18min, 20min). In traditional semiconductor manufacturing, excessive water pressure during water flow flushing is not suitable for ultra-thin chips because it can easily damage the chip, and too low water pressure makes it difficult to remove laser cutting residues. In this embodiment, the back of wafer A is used as the cutting surface, and the water flow flushing after laser cutting also acts on the back of wafer A, and the front of wafer A is also protected by the substrate wafer, so the chip and ultra-thin wafer of this embodiment will not be damaged during water flow flushing.

[0041] In this embodiment, film expansion is performed after water rinsing to separate the chips, thereby increasing the contact area between the hot melt and the chemical solvent, facilitating subsequent processing. In this embodiment, film expansion is performed to achieve a distance of 10 μm between adjacent chips on the bonded wafer (in other embodiments, the distance between adjacent chips on the bonded wafer can be 10 μm-20 μm, such as 12 μm, 15 μm, or 20 μm).

[0042] In this embodiment, chemical solvent cleaning is performed after film expansion, and the chemical solvent cleaning includes a first chemical solvent immersion and a second chemical solvent immersion. In which, the first chemical solvent includes phosphoric acid and hydrogen peroxide, the volume concentration of phosphoric acid is 10% (in some other embodiments, the volume concentration of phosphoric acid can be ≥10%, for example, 15%, 20%, or 30%), the volume concentration of hydrogen peroxide is 10% (in some other embodiments, the volume concentration of hydrogen peroxide can be ≥10%, for example, 15%, 20%, or 30%), and the soaking time of the first chemical solvent is 20 minutes (in some other embodiments, the soaking time of the first chemical solvent can be 10 minutes to 30 minutes, for example, 10 minutes, 15 minutes, 25 minutes, or 30 minutes); the second chemical solvent includes ammonia water, the volume concentration of ammonia water is 2% (in some other embodiments, the volume concentration of ammonia water can be 1% to 10%, for example, 1%, 3%, 5%, or 10%), and the soaking time of the second chemical solvent is 2 minutes (in some other embodiments, the soaking time of the second chemical solvent can be 1 minute to 2 minutes, for example, 1 minute, 1.5 minutes, or 1.8 minutes); the soaking temperature of the first chemical solvent and the second chemical solvent is room temperature. In this embodiment, a mixed solution of phosphoric acid and hydrogen peroxide with a specific volume concentration can be used to chemically etch away the remaining hot melt; the second chemical solvent immersion uses an ammonia solution with a specific volume concentration to remove the phosphoric acid and hydrogen peroxide remaining after the first chemical solvent immersion.

[0043] Furthermore, in this embodiment, a second water flush is performed after the first chemical solvent soaking, and a third water flush is performed after the second chemical solvent soaking. In this embodiment, the time for the second water flushing is 15 minutes (in some other embodiments, the time for the second water flushing can be 10 minutes to 20 minutes, such as 10 minutes, 12 minutes, 17 minutes, or 20 minutes), and the time for the third water flushing is 5 minutes (in some other embodiments, the time for the third water flushing can be 5 minutes to 10 minutes, such as 6 minutes, 8 minutes, or 10 minutes). In this embodiment, further water flushing is performed after the first chemical solvent soaking and the second chemical solvent soaking to further remove chemical solvent residues.

[0044] In this embodiment, wafer picking is performed after chemical solvent cleaning. This step distinguishes and picks chips of different performance levels. Traditional wafer picking corresponds to the position of the chip. There will be a lifting force at the bottom of the wafer to separate the edge of the chip from the flexible UV film. At the same time, a vacuum adsorption adhesive disc is used to adsorb the front of the chip above the chip and transfer it to a chip storage box for distinguishing and temporarily storing chips of different grades. In traditional wafer picking, the lifting force at the bottom of the wafer needs to lift the chip by about 1-5mm. This method will cause ultra-thin chips to break, so it is not suitable for ultra-thin chips. In addition, when the vacuum adsorption adhesive disc is used to pick up the chip, it is easy to cause contamination and damage to the front of the chip. The wafer picking in this embodiment is to separate the bonded wafer from the UV film, so there is no problem of the lifting force causing the chip and ultra-thin wafer to break. In addition, when the vacuum adsorption adhesive disc is used to pick up the chip in this embodiment, the adhesive disc adsorbs the back of wafer A, so it will not cause contamination and damage to the front of the wafer.

[0045] In this embodiment, after picking the chip, the back side of the chip is first bonded to the substrate, and then the substrate wafer and the organic bonding adhesive are removed. On the one hand, the first temperature when the chip and the substrate are bonded is used to soften the organic bonding adhesive, which is more conducive to removing the substrate wafer; on the other hand, a rigid support surface is provided for the chip when the substrate wafer and the organic bonding adhesive are removed to prevent the chip from being deformed during subsequent processing and causing damage to the chip.

[0046] In this embodiment, the removal of the organic bonding glue includes immersion in an organic solvent, the organic solvent includes KS7203 (supplier: Shanghai Feikai Materials Technology Co., Ltd.), the immersion time of the organic solvent is 10 minutes (in some other embodiments, the immersion time of the organic solvent can be 10 minutes-30 minutes, for example, 15 minutes, 20 minutes, 30 minutes), and the organic solvent immersion is carried out at 80°C (in some other embodiments, the organic solvent immersion can be carried out at 60°C-80°C, for example, 60°C, 65°C, 70°C).

[0047] Furthermore, in this embodiment, after soaking in the organic solvent, isopropyl alcohol and water are used for soaking in sequence; the isopropyl alcohol soaking time is 5 min (in some other embodiments, the isopropyl alcohol soaking time can be 3 min-10 min, for example, 3 min, 8 min, 10 min), and the water soaking time is 5 min (in some other embodiments, the water soaking time can be 2 min-10 min, for example, 2 min, 4 min, 8 min, 10 min). In this embodiment, the organic solvent residue is removed by soaking in isopropyl alcohol, and the isopropyl alcohol residue is removed by soaking in water.

[0048] In this embodiment, after removing the organic bonding glue, plasma treatment is performed. The plasma package is oxygen plasma, and the plasma treatment time is 30s (in some other embodiments, the plasma treatment time can be 30s-100s, such as 40s, 50s, 70s, 100s). In this embodiment, plasma treatment is used to further remove the residues of the organic bonding glue and organic cleaning solution.

[0049] In this embodiment, after plasma treatment, packaging is performed, wiring is performed on the front side of the chip, and each metal electrode is connected to the corresponding position of the substrate with a metal wire; then, according to product requirements, a protective layer is added to the front side of the wired product, such as a transparent PI layer, an opaque cover plate, etc.

[0050] In this specification, the terms "first," "second," etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Therefore, a feature designated "first," "second," etc. may explicitly or implicitly include at least one of such features.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A semiconductor manufacturing method, characterized in that: The method comprises the following steps: preparing a wafer A and a substrate wafer, wherein the thickness of the wafer A is 10 μm-50 μm, and the wafer A has a front surface on which a chip is formed and a back surface corresponding to the front surface; The substrate wafer includes a first surface and a second surface; The front surface and the first surface are bonded together by organic bonding adhesive, thereby bonding the wafer A and the substrate wafer to obtain a bonded wafer. Subsequently, the second surface is attached to a UV film, and then laser cutting, first water washing, film expansion, chemical solvent cleaning, and wafer picking are sequentially performed to obtain a wafer. Adhere the back surface to the substrate using a die-bonding adhesive and cure at a first temperature; removing the substrate wafer and the organic bonding adhesive in sequence; The first temperature is 100° C.-400° C., and the curing time is no more than 2 hours.

2. The semiconductor manufacturing method according to claim 1, wherein After coating the organic bonding adhesive on the front surface, the front surface and the first surface are connected via the organic bonding adhesive, thereby bonding the wafer A and the substrate wafer. The coating thickness of the organic bonding adhesive is 15 μm-25 μm.

3. The semiconductor manufacturing method according to claim 2, wherein: After the front surface and the first surface are bonded together by organic bonding adhesive, a first pressure is applied to bond the wafer A and the substrate wafer, wherein the first pressure is 0.02 MPa-0.04 MPa.

4. The semiconductor manufacturing method according to claim 1, wherein: The substrate wafer includes one of Si and glass.

5. The semiconductor manufacturing method according to claim 4, wherein: The thickness of the substrate wafer is 100 μm-200 μm.

6. The semiconductor manufacturing method according to claim 5, wherein: The removal of the organic bonding adhesive includes soaking in an organic solvent. The soaking time of the organic solvent is 10 minutes to 30 minutes, and the soaking in the organic solvent is performed at 60° C. to 80° C.

7. The semiconductor manufacturing method according to claim 6, wherein: After the organic solvent soaking, isopropyl alcohol and water are sequentially used for soaking; the isopropyl alcohol soaking time is 3 minutes to 10 minutes; and / or the water soaking time is 2 minutes to 10 minutes.

8. The semiconductor manufacturing method according to claim 1, wherein: After removing the organic bonding adhesive, plasma treatment is performed.

9. The semiconductor manufacturing method according to claim 8, wherein: The plasma includes oxygen plasma, and the plasma treatment time is 30s-100s.

10. A semiconductor, characterized in that The semiconductor is manufactured according to the manufacturing method according to any one of claims 1 to 9.

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