CN117558616A - Semiconductor monocrystalline material laser stripping method based on stress layer - Google Patents

Semiconductor monocrystalline material laser stripping method based on stress layer Download PDF

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Publication number
CN117558616A
CN117558616A CN202311457281.9A CN202311457281A CN117558616A CN 117558616 A CN117558616 A CN 117558616A CN 202311457281 A CN202311457281 A CN 202311457281A CN 117558616 A CN117558616 A CN 117558616A
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China
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single crystal
layer
semiconductor single
crystal material
semiconductor
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CN202311457281.9A
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Inventor
修向前
李彬
张�荣
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Nanjing University
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Nanjing University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02002—Preparing wafers
    • H01L21/02005—Preparing bulk and homogeneous wafers
    • H01L21/02008—Multistep processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/50—Working by transmitting the laser beam through or within the workpiece
    • B23K26/53—Working by transmitting the laser beam through or within the workpiece for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/6835—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L21/6836—Wafer tapes, e.g. grinding or dicing support tapes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
    • H01L2221/67—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere
    • H01L2221/683—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L2221/68304—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L2221/68381—Details of chemical or physical process used for separating the auxiliary support from a device or wafer
    • H01L2221/68386—Separation by peeling

Abstract

The invention discloses a semiconductor monocrystalline material laser stripping method based on a stress layer, which comprises the following steps: (1) Forming a patterned stress layer on the surface of the semiconductor monocrystalline material through a mask plate; (2) Focusing laser in the semiconductor monocrystal material to certain depth, decomposing the material with the heat effect in the focus to form modified layer and micro crack; (3) And coating a heat release adhesive or polyimide adhesive tape on the surface of the semiconductor single crystal material, and applying a mechanical external force to peel off to obtain the semiconductor single crystal film. The method has the advantages of simple process and working procedure, short time consumption, material loss reduction and time and cost saving compared with the traditional wire cutting or common stripping process.

Description

Semiconductor monocrystalline material laser stripping method based on stress layer
Technical Field
The invention relates to a semiconductor monocrystalline material laser stripping method based on a stress layer, and belongs to the technical field of semiconductor materials.
Background
The first generation of semiconductor materials represented by silicon (Si) and germanium (Ge) are the material bases in the fields of large-scale integrated circuits, sensors, photovoltaic devices, and the like, and have an indisputable position in the semiconductor industry. The second generation semiconductor materials such as III-V compound semiconductor materials including gallium arsenide (GaAs), indium phosphide (InP) and the like are widely applied in the fields of semiconductor lasers, satellite communication, GPS navigation and the like. In recent years, third generation semiconductor materials represented by wide band gap materials such as gallium nitride (GaN) and silicon carbide (SiC) and fourth generation semiconductor materials represented by ultra wide band gap materials such as gallium oxide (Ga 2O 3), diamond (C) and aluminum nitride (AlN) have been highlighted in recent years because of their characteristics of high breakdown electric field, high kagay value, good thermal stability, strong radiation resistance and the like, and have been in great importance in the field of manufacturing high performance semiconductor devices.
The semiconductor single crystal needs to be prepared into a wafer with a certain thickness to be put into practical application, and for materials such as silicon carbide, silicon, germanium, gallium arsenide, sapphire and the like, an ingot or a crystal rod is obtained through various growth methods, and then the ingot or the crystal rod is subjected to a series of processes such as orientation, rod drawing, barreling, slicing, grinding, chamfering, polishing, cleaning and the like to obtain the wafer which can be directly used. The slicing is to cut the crystal bar into thin wafers. The traditional process generally adopts a diamond sand line multi-wire cutting mode, and has the problems of large material loss, long processing time, high cost, serious environmental pollution and the like. Particularly, the method is more difficult and heavy for processing hard and brittle materials such as silicon carbide, gallium nitride and the like, the surface and subsurface of the materials cut by the silicon carbide wire are seriously damaged, the thickness of a damaged layer exceeds 100 mu m, the material loss can reach more than 40 percent, the time is as long as a plurality of days, the cost is greatly improved, and the productivity is limited.
In addition to the wire-cut method, there are chemical peeling, laser peeling, various mechanical peeling, mechanical peeling based on two-dimensional materials, and the like, but various technical difficulties exist, either the complicated process is costly or the peeling interface is difficult to realize or rough. Taking laser stripping as an example, the sample moves at a high speed during scanning, the laser scanning is not necessarily focused on the same scanning plane, and the pulse depth may have fluctuation, so that cracks appear at different depth positions and are not easy to connect, and stripping is not performed. Even if the cracks continue, the thickness of the cracks is relatively large, resulting in waste of material. In addition, the laser may generate a sweep of the sample moving at high speed, resulting in difficulty in complete peeling.
Disclosure of Invention
The invention aims to provide a semiconductor single crystal material laser stripping method based on a stress layer.
The technical scheme of the invention is as follows:
a semiconductor single crystal material laser stripping method based on a stress layer comprises the following steps:
(1) Forming a patterned stress layer on the surface of the semiconductor monocrystalline material through a mask plate;
(2) Focusing laser in the semiconductor monocrystal material to certain depth, decomposing the material with the heat effect in the focus to form modified layer and micro crack;
(3) And coating a heat release adhesive or polyimide adhesive tape on the surface of the semiconductor single crystal material, and applying a mechanical external force to peel off to obtain the semiconductor single crystal film.
The peeled semiconductor single crystal film can be subjected to a method such as acid cleaning to remove the stress layer.
The steps (1) - (3) may be repeated until the semiconductor single crystal film cannot be peeled off.
And (3) polishing and cleaning the surface of the semiconductor monocrystalline material between each patterned stress layer, wherein the cleaning is to ultrasonically clean the semiconductor monocrystalline material in acetone, alcohol and deionized water for 15 minutes respectively, remove oil stains and impurities on the surface, and blow-dry the semiconductor monocrystalline material by a nitrogen gun.
Preferably, the stress layer is a three-layer structure of a metal adhesion layer, a metal seed layer and an electroplated metal layer, wherein the metal adhesion layer is attached to the surface of the semiconductor single crystal material.
Preferably, the metal adhesion layer is a metal Ti layer which is evaporated or deposited on the surface of the semiconductor single crystal material, and the thickness is 50-100nm.
Preferably, the metal seed layer is a metal Ni layer which is evaporated or deposited on the surface of the metal adhesion layer, and the thickness is 50-1000nm.
Preferably, the electroplated metal layer is a metal Ni layer electroplated on the surface of the metal seed crystal layer, and the thickness is 1-200 mu m. The metallic Ti adhesive layer can enable metallic Ni to be better adhered to the surface of the semiconductor single crystal, so that stress is applied to the single crystal, and the Ni seed layer is used for electroplating Ni more easily, so that an electroplated metallic Ni layer with high stress is formed.
Preferably, the semiconductor single crystal material is GaN, siC, gaAs, ge or Si. Either as a wafer or ingot or as a monocrystalline film.
Preferably, the mask plate is in a plurality of parallel long strips, a long strip stress layer is formed, the width of the mask region (stress layer) is 10-1000 mu m, the width of the stress-free layer region is 10-100 mu m, and the length of the mask region is matched with the surface of the semiconductor monocrystalline material.
Preferably, the plating conditions are: niCl 2 Concentration c=100-500 g/L, H 3 BO 3 Concentration c=10-60 g/L, plating solution PH=1.0-4.0, current density J=10-60 mA/cm 2 Electroplating time t=1-100 min.
Preferably, the wavelength of the laser light source is 300-800nm, the pulse width is 100fs-100ns, the single pulse energy is 100-600 mu J, the repetition frequency is 0.1-10kHz, and the wavelength of the laser is larger than the wavelength corresponding to the forbidden bandwidth of the semiconductor single crystal material. The laser adopts pulse laser, the pulse time is enough for the energy to reach the threshold value for decomposing the semiconductor single crystal material, and 3-5 pulses are generally adopted for a single point. The depth of focus is related to the thickness requirements for the desired lift-off, such as 4 inch silicon carbide according to the national standard, which is 400 μm, and the laser depth of focus is about 450-500 μm, and the standard thickness for polishing after laser lift-off is 400 μm. The semiconductor single crystal material can be a single crystal ingot, the wafer with thinner thickness is obtained by directly stripping the semiconductor single crystal material by the method, and the stripped ingot can be repeatedly subjected to simple surface polishing treatment to realize the cutting of the ingot into a plurality of wafers; or a composite substrate, such as a gallium nitride film on sapphire, and separating the sapphire from the gallium nitride by the method to obtain a self-supporting gallium nitride wafer; and can also be used for thinning the wafer.
The beneficial effects of the invention are as follows:
the invention generates microcracks in the semiconductor monocrystalline material by means of laser focusing scanning, and the microcracks are mutually expanded and connected by means of the stress applied by the high-stress layer generated by electroplating, so that the separation of wafers with certain thickness is finally realized. Can be applied to stripping semiconductor wafers (such as SiC or GaN, etc.) with different thicknesses on thicker ingots or substrates. The existence of the large-area stress layer ensures that even if the laser pulse scanning plane has undulation, the stress can cause the microcracks to be mutually and transversely expanded and fused, so that the stripping is easier to realize, the separation of large-size wafers is realized, the thickness of the microcracks is only in the order of several micrometers, and compared with the thickness loss of hundreds of micrometers when the wire cutting is performed, the loss of materials is greatly reduced.
The method has the advantages of simple process and working procedure, short time consumption, material loss reduction and time and cost saving compared with the traditional wire cutting or common stripping process.
The process of the invention is easy to realize, the process repeatability is good, and the process can be repeated by simply polishing and cleaning the surface of the ingot or the substrate such as SiC, gaN and the like which are remained after the stripping.
Drawings
Fig. 1 is a process flow diagram of preparing a single crystal wafer by a stress layer-based semiconductor single crystal material laser lift-off method.
Fig. 2 is a schematic diagram of a preferred patterned stress layer of a stress layer-based semiconductor single crystal material laser lift-off method according to the present invention.
Fig. 3 is a view of a stress layer-based semiconductor single crystal material laser lift-off method for lift-off of a silicon carbide wafer, wherein a is an upper and lower portion of the wafer after separation, and B is an optical micrograph, and the laser scanning area (black) and the stress layer coverage area (light area, color due to microcracks) are clearly visible.
Detailed Description
The following is a clear and complete description of the technical solutions according to embodiments of the present invention, with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
As shown in fig. 1, a semiconductor single crystal material laser lift-off method based on a stress layer specifically includes the following steps:
1) Ultrasonically cleaning a gallium nitride (GaN) thick film template on a sapphire with the thickness of 20X20mm in acetone, alcohol and deionized water for 15 minutes respectively, removing oil stains and impurities on the surface, and blow-drying by a nitrogen gun;
2) Placing a mask plate on the surface of a sample, and evaporating Ti (75 nm)/Ni (200 nm) on the surface of GaN by using magnetron sputtering to serve as an adhesion layer and a seed crystal layer;
3) Electroplating a Ni stress layer on the GaN surface seed crystal layer in the step (2) by using a chlorine-based plating solution, wherein the electroplating conditions are as follows: niCl 2 Concentration c=300 g/L, H 3 BO 3 Concentration c=32.8 g/L, plating solution ph=2.0, current density j=25 mA/cm 2 Electroplating time t=20min, stress layer width about 50 μm, thickness about 20 μm;
4) Focusing laser at the position with the depth of about 100 mu m in GaN through an optical path and a focusing lens, decomposing the material into gallium metal, nitrogen and the like by utilizing the thermal effect at a focus, wherein the micro cracks are generated in the sample due to the difference of the thermal expansion coefficients of gallium metal and gallium nitride and the high pressure of the generated nitrogen in a small space;
5) The back of the sapphire is fixed on a table top by using glue, a polyimide tape with the thickness of 25 mu m is covered on the stress layer, then the polyimide tape is adhered on the surface by using a hard plate, and the GaN self-supporting film with the thickness of about 100 mu m can be obtained by pulling the hard plate perpendicular to the surface of a sample by adopting mechanical pulling force. And placing the film in an acid solution for soaking to remove the metal stress layer.
Example 2
A semiconductor single crystal material laser stripping method based on a stress layer and a process for preparing a wafer specifically comprise the following steps:
1) Ultrasonically cleaning a 20X20mm silicon carbide (SiC) ingot or wafer in acetone, alcohol and deionized water for 15 minutes respectively, removing oil stains and impurities on the surface, and blow-drying by a nitrogen gun;
2) Placing a mask plate on the surface of a sample, and evaporating Ti (75 nm)/Ni (200 nm) on the surface of silicon carbide by using electron beam evaporation to serve as an adhesion layer and a seed crystal layer;
3) Electroplating a Ni stress layer on the seed crystal layer on the surface of the silicon carbide (SiC) ingot or the wafer by using a chlorine-based plating solution, wherein the electroplating conditions are as follows: niCl 2 Concentration c=300 g/L, H 3 BO 3 Concentration c=32.8 g/L, plating solution ph=2.0, current density j=25 mA/cm 2 The electroplating time t=20min, the wafer structure plated with the stress layer is shown in fig. 2, the width of the stress layer strip is 60 μm, and the thickness is 100 μm;
4) Laser is focused at the position with the depth of about 450 mu m in SiC through an optical path and a focusing lens, a material is decomposed into gallium metal, nitrogen and the like by utilizing the thermal effect at a focus, micro cracks are generated in a sample due to the difference of the thermal expansion coefficients of gallium metal and gallium nitride and the high pressure of generated nitrogen in a small space, and a sample photo is shown in figure 3.
5) The back of the sample is fixed on the table surface by using glue, a polyimide tape with the thickness of 25 mu m is covered on the stress layer, a silicon carbide wafer with the thickness of about 450 mu m can be obtained by stripping through mechanical pulling force, the wafer is placed in an acid solution to soak and remove the metal stress layer, and the standard silicon carbide wafer with the thickness of 400 mu m can be obtained after the wafer is polished.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims (9)

1. A semiconductor single crystal material laser stripping method based on a stress layer is characterized by comprising the following steps:
(1) Forming a patterned stress layer on the surface of the semiconductor monocrystalline material through a mask plate;
(2) Focusing laser in the semiconductor monocrystal material to certain depth, decomposing the material with the heat effect in the focus to form modified layer and micro crack;
(3) And coating a heat release adhesive or polyimide adhesive tape on the surface of the semiconductor single crystal material, and applying a mechanical external force to peel off to obtain the semiconductor single crystal film.
2. The laser lift-off method of a semiconductor single crystal material according to claim 1, wherein the stress layer is a three-layer structure of a metal adhesion layer, a metal seed layer, and an electroplated metal layer, wherein the metal adhesion layer is attached to the surface of the semiconductor single crystal material.
3. The laser lift-off method of a semiconductor single crystal material according to claim 2, wherein the metal adhesion layer is a metal Ti layer evaporated or deposited on the surface of the semiconductor single crystal material, and the thickness is 50-100nm.
4. The laser lift-off method of a semiconductor single crystal material according to claim 2, wherein the metal seed layer is a metal Ni layer evaporated or deposited on the surface of the metal adhesion layer, and the thickness is 50-1000nm.
5. The laser lift-off method of a semiconductor single crystal material according to claim 2, wherein the electroplated metal layer is a metal Ni layer electroplated on the surface of the metal seed layer, and has a thickness of 1-200 μm.
6. The method for laser lift-off of a semiconductor single crystal material according to any one of claims 1 to 5, characterized in that the semiconductor single crystal material is GaN, siC, gaAs, ge or Si.
7. The method for laser lift-off of a semiconductor single crystal material according to claim 6, wherein the mask plate has a pattern of a plurality of parallel elongated shapes to form an elongated stress layer, the mask region has a pattern width of 10-1000 μm, the stress-free layer region has a pattern width of 10-100 μm, and the mask region has a pattern length matching the surface of the semiconductor single crystal material.
8. The method for laser lift-off of a semiconductor single crystal material according to claim 5, wherein the plating conditions are: niCl 2 Concentration c=100-500 g/L, H 3 BO 3 Concentration c=10-60 g/L, plating solution PH=1.0-4.0, current density J=10-60 mA/cm 2 Electroplating time t=1-100 min.
9. The method for laser lift-off of a semiconductor single crystal material according to claim 1, wherein the wavelength of the laser light source is 300-800nm, the pulse width is 100fs-100ns, the single pulse energy is 100-600 μj, the repetition frequency is 0.1-10kHz, and the wavelength of the laser is larger than the wavelength corresponding to the forbidden bandwidth of the semiconductor single crystal material.
CN202311457281.9A 2023-11-03 2023-11-03 Semiconductor monocrystalline material laser stripping method based on stress layer Pending CN117558616A (en)

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