TWI835575B - Manufacturing method of semiconductor wafer - Google Patents

Abstract

The present application provides a manufacturing method of a semiconductor wafer, including: providing a wafer and a supporting substrate, where the wafer includes a first portion and a second portion; forming a separation layer on a surface of the supporting substrate; bonding the supporting substrate and the wafer, where the separation layer is formed between the supporting substrate and the wafer; performing a smart-cut process on the bonded supporting substrate and the wafer to remove the first portion of the wafer; and separating the supporting substrate from the second portion of the wafer by the separation layer.

Description

Semiconductor wafer manufacturing method

The present application relates to the field of semiconductors, and in particular to a manufacturing method of semiconductor wafers.

Smart-cut® technology is a gas ion implantation and then peeling technology that can be used to transplant ultra-thin single crystal layers generated by wafer materials (such as silicon) to the surface of another substrate. Specifically, gas ions are implanted in a wafer, and then the wafer is bonded to another substrate. Then, the bonded wafer and substrate are heat treated at about 500°C. At this time, continuous cavities are formed at the gas ion implantation site, causing part of the wafer to automatically peel off, thereby forming a silicon on insulator (SOI) structure.

However, in the conventional smart cutting technology, permanent wafer bonding is used between the wafer and the substrate, resulting in a certain thickness of the SOI structure after smart cutting, making it difficult to further reduce the thickness. In addition, since the thickness of the wafer retained after smart cutting is in the micron range and its size is at least 6 inches, even if the SOI structure is mechanically processed to remove the substrate through grinding and other techniques, it is difficult to achieve the target with current processing technology. Accuracy, which in turn derives various process risks. Furthermore, the substrate cannot be reused regardless of mechanical processing, resulting in high production costs.

In view of this, it is necessary to provide a manufacturing method for semiconductor wafers to solve the above technical problems.

In order to solve the above-mentioned problems of the conventional technology, the purpose of this application is to provide a manufacturing method of a semiconductor wafer, which can separate the wafer from the substrate after smart cutting.

In one aspect, the present application provides a method for manufacturing a semiconductor wafer, including: providing a wafer and a support substrate, wherein the wafer includes a first part and a second part; forming a separation layer on the surface of the support substrate ; Bonding the support substrate and the wafer, wherein the separation layer is formed between the support substrate and the wafer; performing an intelligent cutting process on the bonded support substrate and the wafer to remove the wafer a first part; and separating the support substrate from the second part of the wafer by the separation layer.

In some embodiments, in the step of forming the separation layer, the manufacturing method further includes: depositing a material layer on the surface of the support substrate, wherein the material layer is different from the material of the support substrate, and the material layer serves as The separation layer.

In some embodiments, in the step of forming the separation layer, the manufacturing method further includes: performing surface treatment on the surface of the support substrate to form a lattice defect layer, wherein the lattice defect layer serves as the separation layer.

In some embodiments, the energy band of the separation layer is smaller than the energy band of the support substrate.

In some embodiments, in the step of separating the support substrate from the second part of the wafer through the separation layer, the manufacturing method includes: irradiating the separation layer with a laser to separate the support substrate from the second part of the wafer. The wafer is separated.

In some embodiments, the energy band of the separation layer corresponds to a first wavelength, the energy band of the support substrate corresponds to a second wavelength, and the wavelength emitted by the laser is between the first wavelength and the second wavelength. .

In some embodiments, in the step of separating the support substrate from the second part of the wafer through the separation layer, the manufacturing method further includes: removing the separation layer through an etching process to separate the support substrate. separated from the wafer.

In some embodiments, after performing the smart cutting process to remove the first portion of the wafer, the manufacturing method further includes: exposing a first surface of the second portion of the wafer; form a source. After the support substrate is separated from the second part of the wafer by the separation layer, the manufacturing method further includes: exposing a second surface of the second part of the wafer, wherein the second surface is opposite on the first surface; forming a drain on the second surface.

In some embodiments, in the step of providing the wafer, the manufacturing method further includes: performing gas ion implantation on the wafer to form a gas ion layer inside the wafer, wherein the gas ion layer is formed on the wafer. between the first part and the second part. When performing the smart cutting process, the manufacturing method further includes: performing heat treatment on the bonded support substrate and the wafer to cause the gas ion layer to form bubbles, thereby making the first part and the second part of the wafer separation.

Compared with the prior art, this application provides a method for manufacturing a semiconductor wafer, which separates the support substrate after smart cutting from the wafer through a preset separation layer, so that corresponding processing can be performed on the two opposite surfaces of the wafer. The manufacturing process makes the application fields of semiconductor wafers wider. Secondly, the thickness of the final semiconductor wafer is thinner, which is conducive to the manufacture of thinner electronic devices. Furthermore, the separated support substrate can be recycled and reused, thereby effectively reducing production costs.

In order to make the above and other objects, features, and advantages of the present application more obvious and understandable, preferred embodiments of the present application will be cited in the following and described in detail with reference to the attached drawings.

Please refer to FIG. 1 , which shows a series of schematic diagrams for illustrating a semiconductor wafer manufacturing method according to an embodiment of the present application. First, the wafer 10 to be processed and the supporting substrate 20 are provided. Optionally, the material of the wafer 10 includes, but is not limited to, silicon, sapphire, gallium nitride (GaN), silicon carbide (SiC), etc. The material of the support substrate 20 includes, but is not limited to, silicon carbide (SiC), gallium nitride, aluminum nitride (AlN), etc.

As shown in FIG. 1 , in step S111 , a wafer 10 to be processed is provided, and the wafer 10 is first pre-processed. The pretreatment specifically involves ion implantation of the wafer 10 with gas ions (such as hydrogen, inert gas, etc.) to form a gas ion layer 13 inside the wafer 10 . That is, the wafer 10 provided includes the stacked first part 11 , the second part 12 and the gas ion layer 13 , wherein the gas ion layer 13 is located between the first part 11 and the second part 12 . It should be understood that the above steps of preprocessing the wafer 10 can be implemented by a device such as an ion implanter.

As shown in FIG. 1 , in step S112 , a support substrate 20 to be processed is provided, and the support substrate 20 is preprocessed first. The pretreatment is specifically to form a separation layer 21 on the surface of the supporting substrate 20 . In some embodiments, the separation layer 21 is formed by depositing a material layer on the surface of the support substrate 20 . The material layer is different from the material of the supporting substrate 20. For example, the material layer is a silicon layer, and the supporting substrate 20 contains materials other than silicon, such as silicon carbide, gallium nitride, aluminum nitride, etc., but is not limited thereto. That is, the material layer (eg silicon layer) is used as the separation layer 21 . It should be understood that the above separation layer 21 can be formed by, for example, chemical vapor deposition and related devices.

Optionally, in some embodiments, the separation layer 21 is formed by surface treatment of the surface of the support substrate 20 . For example, surface treatment can be performed by ion implantation, ion bombardment, chemical treatment, etc. A layer of lattice defect layer will be formed on the surface of the support substrate 20 after surface treatment, and the lattice defect layer serves as the separation layer 21 . It should be noted that the separation layer 21 formed by surface treatment is made of the same material as the supporting substrate 20 , so the material properties (such as melting point, etc.) of the separation layer 21 and the supporting substrate 20 are substantially the same. In addition, the main difference between the two is that since the crystal lattice of the separation layer 21 has many defects, the energy bandgap of the separation layer 21 is smaller than the energy band of the support substrate 20 . It should be understood that the formation of the separation layer 21 can be achieved by, for example, an ion implanter, an ion bombardment device, a wet etching or dry etching method, and related devices.

It should be noted that in this application, the formation method of the separation layer 21 is related to the conditions (such as temperature) of subsequent processes, and the specific formation method will be described in detail later. In addition, the selection of materials for the wafer 10 , the support substrate 20 and the separation layer 21 is also related to the conditions of subsequent processes, and the specific content will be described in detail later.

As shown in FIG. 1 , after the wafer 10 and the support substrate 20 are pre-processed, step S120 is performed to bond the support substrate 20 to the wafer 10 using wafer bonding technology. At this time, the separation layer 21 is provided between the support substrate 20 and the wafer 10 . Wafer bonding technology aims to bond two substrates to each other without the use of any adhesive, keeping the bonding interface clean and thus meeting the stringent requirements for interface properties of microelectronics and optoelectronic materials. Wafer bonding technology can be performed using a variety of methods, such as room-temperature bonding, anodic bonding, direct bonding, vacuum bonding, bonding Adhesive Bonding, Ion Enhanced Bonding, Plasma Activation Bonding, Eutectic Low Temperature Bonding, etc.

As shown in FIG. 1 , after the support substrate 20 and the wafer 10 are bonded, step S130 is performed to perform an intelligent cutting process on the bonded support substrate 20 and the wafer 10 to remove the first part 11 of the wafer 10 . Specifically, the bonded support substrate 20 and the wafer 10 are heat-treated at approximately 500° C., and bubbles will be formed in the gas ion layer 13 at this time. These bubbles will form continuous cavities, thereby separating the first part 11 and the second part 12 of the wafer 10 . The second portion 12 of the wafer 10 remains bonded to the support substrate 20 . On the other hand, the first part 11 of the separated wafer 10 can be recycled and used as a wafer to be processed in another semiconductor process (such as the wafer 10 provided in step S111 ).

As shown in FIG. 1 , after the first portion 11 of the wafer 10 is removed, the first surface 121 of the second portion 12 of the wafer 10 is exposed. Next, step S140 is performed to form various functional element layers on the first surface 121, such as the source electrode 31 and so on. The formation of the functional element layer can be achieved through processes such as doping.

As shown in FIG. 1 , after completing the arrangement of the functional element layer on the first surface 121 , step S150 is performed, using, for example, laser lift-off technology (Laser Lift-Off) to separate the support substrate 20 and the wafer 10 through the separation layer 21 separation. Specifically, when the laser stripping technology is used, the laser 40 emits laser light 41 and irradiates the separation layer 21 with the laser light 41 .

Optionally, in some embodiments, in step S150, etching technology may also be used to remove the separation layer 21. When etching technology is used, a suitable etching liquid and its etching liquid ratio are selected according to the material or lattice structure of the separation layer 21 , and then the support substrate 20 and the wafer 10 are immersed in the selected etching liquid. The separation layer 21 between the support substrate 20 and the wafer 10 can be removed through the above etching process.

As shown in FIG. 1 , after the separation layer 21 is weakened or removed using laser or etching technology, step S160 is performed to separate the support substrate 20 from the second part 12 of the wafer 10 . Specifically, after the laser light 41 is irradiated, the separation layer 21 absorbs the laser light 41 and converts it into thermal energy, thereby causing thermal decomposition. It should be understood that the wavelength of the laser light 41 is related to the energy bands of the separation layer 21 and the supporting substrate 20 . Furthermore, in order for the separation layer 21 to effectively absorb the energy emitted by the laser 40, the energy band of the separation layer 21 can be smaller than the energy band of the supporting substrate 20, and the wavelength of the laser light 41 is between the energy bands of the two. between wavelengths. That is to say, the energy band of the separation layer 21 corresponds to the first wavelength, the energy band of the supporting substrate 20 corresponds to the second wavelength, and the wavelength of the laser light 41 is between the first wavelength and the second wavelength.

On the other hand, as shown in FIG. 1 , in this application, the separated support substrate 20 can be recovered and reused. That is to say, the supporting substrate 20 can be used as the supporting substrate 20 to be processed in another semiconductor process (such as the supporting substrate 20 provided in step S112 ). The production cost can be effectively reduced by recycling the support substrate 20 .

As shown in FIG. 1 , after the supporting substrate 20 is separated from the second part 12 of the wafer 10 , step S170 is performed to expose the second surface 122 of the second part 12 of the wafer 10 . The second surface 122 is opposite to the first surface 121 . Then, various functional element layers can be formed on the second surface 122, such as the drain electrode 32 and so on. The formation of the functional element layer can be achieved through processes such as doping.

It should be understood that in this application, since the support substrate 20 is separated from the wafer 10 through the separation layer 21 , both opposite surfaces of the second part 12 of the wafer 10 are exposed, and thus the surface of the wafer 10 can be The two opposite surfaces of the second part 12 undergo corresponding processes (such as forming functional component layers). That is, the thickness of the final formed semiconductor wafer 10 (second portion 12 ) is thinner and may be suitable for fabrication in which electric current is transferred vertically (for example, electric current is transferred from the drain 32 of the second surface 122 of the wafer to the first surface). The source 31 of 121 delivers) electronic components, such as power devices. On the other hand, in the conventional technology, the SOI structure formed after smart cutting has one surface of the wafer bonded to the substrate, so that the SOI structure can only be used to manufacture the current for horizontal transfer (current along parallel surfaces). direction of transmission) electronic components. In comparison, the semiconductor wafer manufactured by this application has a wider application field.

Please refer to Table 1, which shows a comparison of the properties of various materials.

Table I: characteristic Si 3C-SiC 4H-SiC GaAs GaN diamond Energy band(eV) 1.1 2.2 3.26 1.43 3.45 5.45 Melting point(°C) 1420 2830 2830 1240 2500 4000

First embodiment:

In the first embodiment of the present application, the material of the support substrate 20 may include, but is not limited to, high-energy band materials, such as silicon carbide, gallium nitride, and aluminum nitride (energy band is about 6.2 eV). In addition, the material of the separation layer 21 may include, but is not limited to, low energy band materials, such as silicon. For example, the separation layer 21 is formed by forming a silicon layer on the surface of the support substrate 20 through a deposition process, and the formed silicon layer serves as the separation layer 21 . As shown in Table 1, taking the material of the support substrate 20 as 4H-SiC as an example, the energy band of the support substrate 20 is 3.26 eV, and the energy band of the separation layer 21 is 1.1 eV. The wavelength emitted by the laser should be between the wavelengths corresponding to the energy bands of the support substrate 20 and the separation layer 21 , that is, the wavelength emitted by the laser should be greater than 380 nm and less than 1100 nm. In this embodiment, the material of the wafer 10 includes silicon, sapphire, gallium nitride, etc., but is not limited thereto.

Second embodiment:

In the second embodiment of the present application, the material of the wafer 10 is a high melting point material, such as gallium nitride or silicon carbide. In addition, the material of the support substrate 20 is also a high melting point material such as silicon carbide, and the material of the separation layer 21 is the same as the material of the support substrate 20 , such as silicon carbide. For example, the separation layer 21 is formed by subjecting the support substrate 20 to surface treatment to form a lattice defect layer on its surface, and the lattice defect layer serves as the separation layer 21 . It should be noted that the material of the separation layer 21 formed by surface treatment is the same as that of the support substrate 20, so the melting points of the separation layer 21 and the support substrate 20 are the same. In addition, since the crystal lattice of the separation layer 21 has many defects, the energy band of the separation layer 21 is smaller than the energy band of the support substrate 20 . It should be understood that the wavelength selection of the laser is related to the energy band of the separation layer 21 and the support substrate 20, and will not be described in detail here.

Furthermore, in the second embodiment of the present application, since the wafer 10 , the supporting substrate 20 and the separation layer 21 are all made of high-melting-point materials, they are suitable for high-temperature processes. For example, in step S140, the required functional element layer can be formed through a high-temperature (eg, 1700°C) doping process. At this time, since the melting point of the separation layer 21 is as high as, for example, 2830° C., premature decomposition of the separation layer 21 can be avoided.

It should be understood that in this application, the material of the separation layer 21 is preferably inorganic, and the use of organic compounds (such as adhesives) is avoided. Using organic compounds as the separation layer can easily lead to premature decomposition of the separation layer (such as decomposition in a high-temperature environment), thereby affecting subsequent processes. Secondly, organic compounds can easily release or remain unintended substances, causing wafer contamination.

Compared with the existing technology, this application provides a method for manufacturing a semiconductor wafer, which separates the support substrate after smart cutting from the wafer through a preset separation layer, so that corresponding processing can be performed on the two opposite surfaces of the wafer. The manufacturing process makes the application fields of semiconductor wafers wider. Secondly, the thickness of the final semiconductor wafer is thinner, which is conducive to the manufacture of thinner electronic devices. Furthermore, the separated support substrate can be recycled and reused, thereby effectively reducing production costs.

The above are only preferred embodiments of the present disclosure. It should be noted that those with ordinary knowledge in the art can make several improvements and modifications without departing from the principles of the present disclosure. These improvements and modifications should also be regarded as the present disclosure. Revealed scope of protection.

10:wafer

11:Part One

12:Part 2

121: First surface

122: Second surface

13: Gas ion layer

20: Support base plate

21:Separation layer

31:Source

32:Jiji

40:Laser

41:Laser light

S111, S112, S120~S170: steps

FIG. 1 shows a series of schematic diagrams for illustrating a semiconductor wafer manufacturing method according to an embodiment of the present application.

10:wafer

11:Part One

12:Part 2

121: First surface

122: Second surface

13: Gas ion layer

20:Support base plate

21:Separation layer

31:Source

32:Jiji

40:Laser

41:Laser light

S111, S112, S120~S170: steps

Claims (9)

A method for manufacturing a semiconductor wafer, including: providing a wafer and a support substrate, wherein the wafer includes a first part and a second part; forming a separation layer on the surface of the support substrate; bonding the support substrate and the wafer, wherein the separation layer is formed between the support substrate and the wafer; performing an intelligent cutting process on the bonded support substrate and the wafer to remove the first portion of the wafer; and by the A separation layer separates the support substrate from the second part of the wafer to expose two opposite surfaces of the second part. The manufacturing method of a semiconductor wafer as claimed in claim 1, wherein in the step of forming the separation layer, the manufacturing method further includes: depositing a material layer on the surface of the supporting substrate, wherein the material layer is different from the material of the supporting substrate. Different, and this layer of material acts as this separation layer. The manufacturing method of a semiconductor wafer as claimed in claim 1, wherein in the step of forming the separation layer, the manufacturing method further includes: performing surface treatment on the surface of the supporting substrate to form a lattice defect layer, wherein the lattice The defective layer serves as this separation layer. The manufacturing method of a semiconductor wafer as claimed in claim 1, wherein the energy band of the separation layer is smaller than the energy band of the support substrate. The manufacturing method of a semiconductor wafer as claimed in claim 4, wherein in the step of separating the supporting substrate from the second part of the wafer through the separation layer, the manufacturing method further includes: irradiating the supporting substrate with a laser A separation layer separates the support substrate from the wafer. The method of manufacturing a semiconductor wafer according to claim 5, wherein the energy band of the separation layer corresponds to a first wavelength, the energy band of the support substrate corresponds to a second wavelength, and the wavelength emitted by the laser is between the first wavelength and the second wavelength. The manufacturing method of a semiconductor wafer as claimed in claim 4, wherein in the step of separating the supporting substrate from the second part of the wafer through the separation layer, the manufacturing method further includes: removing the supporting substrate through an etching process. A separation layer separates the support substrate from the wafer. The manufacturing method of a semiconductor wafer as in claim 1, wherein after performing the smart cutting process to remove the first part of the wafer, the manufacturing method further includes: exposing a first part of the second part of the wafer. surface; forming a source electrode on the first surface; and after separating the support substrate from the second part of the wafer through the separation layer, the manufacturing method further includes: exposing the second part of the wafer A second surface of a portion, wherein the second surface is opposite to the first surface; a drain is formed on the second surface. The manufacturing method of a semiconductor wafer as claimed in claim 1, wherein in the step of providing the wafer, the manufacturing method further includes: subjecting the wafer to gas ion implantation to form a gas ion layer inside the wafer, wherein The gas ion layer is formed between the first part and the second part; and when performing the smart cutting process, the manufacturing method further includes: performing heat treatment on the bonded support substrate and the wafer to make the The gas ion layer forms bubbles, thereby separating the first part and the second part of the wafer.

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