Detailed Description
Specific embodiments of a bonding wafer, a bonding structure, and a bonding method according to the present invention will be described in detail below with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of the steps of a method according to an embodiment of the present invention, including: step S10, providing a first wafer and a second wafer for bonding; step S11, forming alignment marks on the first wafer and the second wafer, wherein the alignment marks are through holes; step S12, bonding the first wafer and the second wafer with the alignment marks on the first wafer and the second wafer as the reference.
Referring to step S10, as shown in fig. 2A, a first wafer 21 and a second wafer 22 for bonding are provided. The materials of the first wafer 21 and the second wafer 22 are respectively and independently selected from any one common wafer material such as silicon, silicon carbide, sapphire, glass, GaAs, GaN, and metal.
Referring to step S11, as shown in fig. 2B, alignment marks 211 and 221, which are both through holes, are formed on the first wafer 21 and the second wafer 22. In this step, at least one alignment mark on the wafer should include a via. The technical solution adopted in the present embodiment is to set the alignment marks 211 and 221 on both wafers as through holes. The method for forming the through hole can adopt dry etching or wet etching processes including DRIE, ICP, KOH etching and the like, and different etching or etching process parameters are selected according to different wafer materials, so that the consistency of the patterns on the two wafers is ensured. The number of the alignment marks 211 and 221 may be one or more, and the shape thereof may be any shape such as a circle, a square, a cross, and the like, to improve the accuracy of alignment.
Referring to step S12, as shown in fig. 2C, the first wafer 21 and the second wafer 22 are bonded with the alignment marks 211 and 221 on the first wafer 21 and the second wafer 22 as the reference. Because the alignment mark is a through hole, the alignment can be realized without an additional infrared auxiliary device or respectively positioning two wafers in advance, and no special requirement is imposed on the light transmittance of the wafers.
Bonding after wafer alignment is typically achieved by applying pressure and heat. After the preliminary bonding, processes such as annealing, strengthening and the like can be carried out according to needs to complete the bonding so as to improve the firmness of the bonding interface.
The bonding structure obtained after the above steps are performed includes the first wafer 21 and the second wafer 22 bonded to each other, and the first wafer 21 and the second wafer 22 include the alignment marks 211 and 221. At least one of the alignment marks on the wafer in the structure should include a via. In the present embodiment, the alignment marks 211 and 221 are provided as through holes.
FIG. 3 is a schematic diagram illustrating the steps of the method of this embodiment, including: step S30, providing a first wafer and a second wafer for bonding; step S31, forming alignment marks on a first wafer and a second wafer, wherein the alignment mark of the first wafer is a wafer surface pattern, and the alignment mark of the second wafer is a wafer surface pattern; step S32, bonding the first wafer and the second wafer in a back-to-back direction with the alignment marks on the first wafer and the second wafer as a reference.
Referring to step S30, as shown in fig. 4A, a first wafer 41 and a second wafer 42 for bonding are provided. The material of the first wafer 41 and the second wafer 42 is independently selected from any one common wafer material such as silicon, silicon carbide, sapphire, glass, GaAs, GaN, and metal.
Referring to step S31, as shown in fig. 4B, alignment marks 411 and 421 are formed on the first wafer 41 and the second wafer 42, where the alignment mark of the first wafer 41 is a wafer surface pattern 413, and the alignment mark of the second wafer 42 is a wafer surface pattern 421. The method for forming the through hole can adopt dry etching or wet etching processes including DRIE, ICP, KOH etching and the like, and different etching or etching process parameters are selected according to different wafer materials, so that the consistency of the patterns on the two wafers is ensured. The number of the alignment marks may be one or more, and the shape thereof may be any shape such as a circle, a square, a cross, and the like, so as to improve the accuracy of alignment.
Referring to step S32, as shown in fig. 4C, the first wafer 41 and the second wafer 42 are bonded with the alignment marks on the first wafer 41 and the second wafer 42 as the reference marks. Since the alignment mark of the first wafer 41 is the circular surface pattern 413 and the alignment mark of the second wafer 42 is the wafer surface pattern 421, no additional infrared auxiliary device is required, and no special requirement is imposed on the light transmittance of the wafers, so that the alignment can be realized without respectively positioning the two wafers in advance.
Bonding after wafer alignment is typically achieved by applying pressure and heat. After the preliminary bonding, processes such as annealing, strengthening and the like can be carried out according to needs to complete the bonding so as to improve the firmness of the bonding interface.
The bonding structure obtained after the above steps are completed includes a first wafer 41 and a second wafer 42 bonded to each other, the alignment mark of the first wafer 41 is a pattern 413 on the wafer surface, and the alignment mark of the second wafer 42 is a pattern 421 on the wafer surface.
FIG. 5 is a schematic diagram of the steps of a method according to an embodiment of the present invention, including: step S50, providing a first wafer and a second wafer for bonding; step S51, forming alignment marks on a first wafer and a second wafer, wherein the alignment marks on the first wafer are through holes, and the alignment marks on the second wafer are second wafer surface patterns; step S52, bonding the first wafer and the second wafer with the alignment marks on the first wafer and the second wafer as the reference.
Referring to step S50, as shown in fig. 6A, a first wafer 61 and a second wafer 62 for bonding are provided. The materials of the first wafer 61 and the second wafer 62 are respectively and independently selected from any one common wafer material such as silicon, silicon carbide, sapphire, glass, GaAs, GaN, and metal.
Referring to step S51, as shown in fig. 6B, alignment marks 611 and 621 are formed on the first wafer 61 and the second wafer 62, where the alignment mark 611 on the first wafer 61 is a through hole, and the alignment mark 621 on the second wafer 62 is a pattern on the surface of the second wafer 62. In this step, at least one alignment mark on the wafer should include a via. The technical solution adopted in the present embodiment is that the alignment mark 611 on the first wafer 61 is a through hole, and the alignment mark 621 on the second wafer 62 is a pattern on the surface of the second wafer 62. The method for forming the through hole can adopt dry etching or wet etching processes including DRIE, ICP, KOH etching and the like, and different etching or etching process parameters are selected according to different wafer materials, so that the consistency of the patterns on the two wafers is ensured. The number of the alignment marks 611 may be one or more, and the shape thereof may be any shape such as a circle, a square, a cross, and the like, so as to improve the accuracy of alignment. Preferably, the intrinsic pattern on the surface of the second wafer 62 is used as an alignment basis, and a through hole corresponding to the intrinsic pattern is formed on the first wafer 61 as an alignment mark, so as to complete the alignment. The above is particularly suitable for the case where the first wafer 61 has no pattern or a simple pattern, and there is enough space for forming the through holes. The second wafer 62 does not need to make additional bonding alignment marks, so that the wafer area is saved, and the integration level of a single chip on the wafer can be further improved.
Referring to step S52, as shown in fig. 6C, the first wafer 61 and the second wafer 62 are bonded with reference to the alignment marks 611 and 621 on the first wafer 61 and the second wafer 62. Because the alignment mark is a through hole, the alignment can be realized without an additional infrared auxiliary device or respectively positioning two wafers in advance, and no special requirement is imposed on the light transmittance of the wafers.
Bonding after wafer alignment is typically achieved by applying pressure and heat. After the preliminary bonding, processes such as annealing, strengthening and the like can be carried out according to needs to complete the bonding so as to improve the firmness of the bonding interface.
The bonding structure obtained after the above steps are performed includes the first wafer 61 and the second wafer 62 bonded to each other, and the first wafer 61 and the second wafer 62 include the alignment marks 611 and 621. At least one alignment mark on the wafer in the structure comprises a through hole. In this embodiment, the alignment mark 611 on the first wafer 61 is a through hole, and the alignment mark 621 on the second wafer 62 is a pattern on the surface of the second wafer 62.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.