CN115424953A - Method and device for detecting thickness of wide bandgap semiconductor subsurface damage layer - Google Patents

Method and device for detecting thickness of wide bandgap semiconductor subsurface damage layer Download PDF

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Publication number
CN115424953A
CN115424953A CN202211150534.3A CN202211150534A CN115424953A CN 115424953 A CN115424953 A CN 115424953A CN 202211150534 A CN202211150534 A CN 202211150534A CN 115424953 A CN115424953 A CN 115424953A
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wide bandgap
bandgap semiconductor
semiconductor wafer
layer
thickness
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耿文浩
王蓉
邵秦秦
皮孝东
杨德仁
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Zhejiang University ZJU
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Zhejiang University ZJU
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/10—Measuring as part of the manufacturing process
    • H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
    • G01B21/08—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness for measuring thickness
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
    • H01L22/24—Optical enhancement of defects or not directly visible states, e.g. selective electrolytic deposition, bubbles in liquids, light emission, colour change

Abstract

The invention relates to the technical field of semiconductors, and discloses a method and a device for detecting the thickness of a subsurface damage layer of a wide bandgap semiconductor.A wide bandgap semiconductor wafer structure detection sheet containing a cross section is used as a working electrode to be connected with a metal catalyst used as a counter electrode and is soaked in etching liquid, and then incident light with a specific wavelength is adopted to irradiate the cross section to generate a photoproduction hole-electron pair on the cross section; etching the side area of the non-damaged layer by using corrosive liquid, wherein the side area of the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the shape of the section after etching is finished; according to the invention, the thickness of the damaged layer of the wide bandgap semiconductor wafer generated in different processing processes can be accurately measured by directly observing the shape of the cross section of the wafer after reaction, so that the processing loss and the processing cost of the wide bandgap semiconductor material are reduced.

Description

Method and device for detecting thickness of wide bandgap semiconductor subsurface damage layer
Technical Field
The invention relates to the technical field of semiconductors, in particular to a method and a device for detecting the thickness of a damaged layer on a sub-surface of a wide bandgap semiconductor.
Background
At present, the processing procedures of wide bandgap semiconductor wafers such as SiC and GaN wafers mainly comprise wire cutting, thinning, grinding and chemical mechanical polishing. Due to the characteristic of high hardness of the wide bandgap semiconductor, cutting and grinding materials adopted in the processes of online cutting, thinning and grinding of the wide bandgap semiconductor wafer are all diamond materials. In the processes of cutting, thinning and grinding the diamond cutting and grinding material with high hardness on line, a stress damage layer appears on the sub-surface of the wafer. The thickness of the stress damage layer caused by different processes is different, wherein the sub-surface damage layer caused by wire cutting is thickest, thinned for the second time and ground for the minimum time. The thickness of the subsurface damage layer generated in each process directly affects the amount of surface material removed from the wafer in the next process. Therefore, how to accurately measure the thickness of the subsurface damaged layer generated by the wide bandgap semiconductor wafer in each process is very important to reduce the processing loss and the processing cost of the wide bandgap semiconductor material.
In the prior art, the measurement of the thickness of a damaged layer on the sub-surface of a wide bandgap semiconductor wafer mainly comprises two detection methods, namely a non-destructive detection method and a destructive detection method; the nondestructive detection method comprises an X-ray diffraction method, a laser scattering method, a sound wave detection method and the like, and the destructive detection method comprises a conical surface polishing method, a cross-section electron microscopy method, a chemical corrosion method and the like; non-destructive detection methods, while capable of rapidly analyzing the distribution of subsurface damage over the two-dimensional surface of a wafer, do not allow for accurate quantification of the thickness of the damaged layer. Destructive detection methods can accurately quantify the thickness of the damaged layer, but this is only a local damaged layer thickness, and the test is costly and complex to operate.
Disclosure of Invention
The invention aims to overcome the problem that the thickness of a damaged layer cannot be accurately detected in the prior art, and provides a method and a device for detecting the thickness of a damaged layer on a sub-surface of a wide bandgap semiconductor.
In order to achieve the above object, the present invention provides a method for detecting a thickness of a subsurface damaged layer of a wide bandgap semiconductor, comprising the following steps:
providing a wide bandgap semiconductor wafer, forming conductive layers on the surfaces of two sides of the wide bandgap semiconductor wafer to obtain a wide bandgap semiconductor wafer structure comprising the conductive layers and the wide bandgap semiconductor wafer;
disconnecting the wide bandgap semiconductor wafer structure to obtain a wide bandgap semiconductor wafer structure detection sheet comprising a cross section, wherein the cross section is a cleavage plane and comprises a damaged layer side area and a non-damaged layer side area;
connecting a conductive layer serving as a working electrode in the wide bandgap semiconductor wafer structure detection sheet with a metal catalyst serving as a counter electrode, and soaking the wide bandgap semiconductor wafer structure detection sheet and the metal catalyst into etching liquid, wherein the etching liquid contains an oxidant and a corrosion liquid;
irradiating the section of the wide bandgap semiconductor wafer structure detection sheet with incident light with the wavelength less than the critical value of the wavelength of the absorbed light corresponding to the wide bandgap semiconductor wafer to generate a photo-generated hole-electron pair on the section;
in the irradiation process, photo-generated electrons in the side area of the non-damaged layer are enriched on the metal catalyst along a circuit and react with the oxidant, the etching liquid etches the side area of the non-damaged layer with photo-generated holes, and the side area of the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the shape of the cross section after etching is completed.
As one possible embodiment, the wide bandgap semiconductor wafer is a silicon carbide wafer or a gallium nitride wafer, the silicon carbide wafer is a 4H type silicon carbide wafer or a 6H type silicon carbide wafer: when the wide bandgap semiconductor wafer is a gallium nitride wafer, the corresponding critical value of the wavelength of the absorbed light is 365nm, and when the wide bandgap semiconductor wafer is a 4H type silicon carbide wafer, the corresponding critical value of the wavelength of the absorbed light is 380nm; when the wide bandgap semiconductor wafer is a 6H-type silicon carbide wafer, the threshold value of the wavelength of the corresponding absorbed light is 410nm.
As one possible embodiment, when the wide bandgap semiconductor wafer is a silicon carbide wafer, the doping concentration of nitrogen in the silicon carbide wafer is in a range of 5 × 10 14 ～3×10 19 /cm 3 When the wide bandgap semiconductor wafer is a gallium nitride wafer, the doping concentration range of silicon in the gallium nitride wafer is 5 × 10 14 ～3×10 19 /cm 3 。
As an implementation manner, the conductive layer is a metal layer, the metal layer is one of a nickel layer, a titanium layer and an aluminum layer, and the thickness of the metal layer is 100-300 nm.
As an implementation manner, the step of disconnecting the wide bandgap semiconductor wafer structure specifically includes: and breaking the wide bandgap semiconductor wafer structure along the [11-20] direction to obtain the wide bandgap semiconductor wafer structure detection sheet with the cross section.
As one possible embodiment, the metal catalyst is a platinum mesh.
As an implementation manner, the etching solution is an alkali solution, the alkali solution is a potassium hydroxide solution or a sodium hydroxide solution, and the oxidant is oxygen contained in the etching solution, wherein the concentration of the alkali solution is in a range of 0.01 to 0.5mol/L.
Correspondingly, the invention also provides a device for detecting the thickness of the wide bandgap semiconductor subsurface damage layer, which comprises an electrolytic bath and a light source;
the electrolytic tank is used for containing etching liquid, a wide bandgap semiconductor wafer structure detection piece and a metal catalyst are arranged in the etching liquid, the wide bandgap semiconductor wafer structure detection piece comprises a wide bandgap semiconductor wafer and conductive layers positioned on the surfaces of two sides of the wide bandgap semiconductor wafer, the conductive layers serving as working electrodes in the wide bandgap semiconductor wafer structure detection piece are connected with the metal catalyst serving as counter electrodes, the section is a cleavage surface, and the section comprises a damaged layer side surface area and a non-damaged layer side surface area;
the light source is arranged at a preset position above the surface of the etching liquid, and incident light with the wavelength smaller than the critical value of the wavelength of the absorbed light corresponding to the wide bandgap semiconductor wafer, which is emitted by the light source, irradiates the section of the wide bandgap semiconductor wafer structure detection sheet, so that a photoproduction hole-electron pair is generated on the section; in the irradiation process, photo-generated electrons in the side area of the non-damaged layer are enriched on the metal catalyst along a circuit and react with the oxidant, the etching liquid etches the side area of the non-damaged layer with photo-generated holes, and the side area of the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the shape of the cross section after etching is completed.
As an embodiment, the light source is one of a xenon lamp, a mercury lamp, and an LED lamp.
As an implementation mode, the etching solution is also provided with a stirrer, and the rotating speed range of the stirrer is 300-500 r/min.
The invention has the beneficial effects that: the invention discloses a method and a device for detecting the thickness of a subsurface damage layer of a wide bandgap semiconductor.A wide bandgap semiconductor wafer structure detection sheet containing a cross section is used as a working electrode to be connected with a metal catalyst used as a counter electrode and is soaked in etching liquid, and then incident light with a specific wavelength is adopted to irradiate the cross section to generate a photoproduction hole-electron pair on the cross section; etching the side area of the non-damaged layer by using corrosive liquid, wherein the side area of the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the shape of the section after etching is finished; according to the invention, the thickness of the damaged layer of the wide bandgap semiconductor wafer generated in different processing processes can be accurately measured by directly observing the shape of the cross section of the wafer after reaction, so that the processing loss and the processing cost of the wide bandgap semiconductor material are reduced.
Drawings
FIG. 1 is a schematic diagram illustrating steps of a method for detecting a thickness of a sub-surface damage layer of a wide bandgap semiconductor according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a wide bandgap semiconductor wafer structure detection sheet in the method for detecting the thickness of the wide bandgap semiconductor subsurface damage layer according to the embodiment of the invention;
FIG. 3 is a schematic diagram of a device for detecting a thickness of a sub-surface damage layer of a wide bandgap semiconductor according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a chemical reaction occurring after a metal catalyst and a wide bandgap semiconductor wafer structure detection sheet form a circuit short circuit in the method for detecting the thickness of the wide bandgap semiconductor subsurface damage layer according to the embodiment of the present invention;
FIG. 5 is a differential interference microscope image of a cross section after a photochemical reaction in the method for detecting the thickness of the sub-surface damage layer of the wide bandgap semiconductor according to the embodiment of the present invention;
fig. 6 is a scanning electron microscope image of a cross section after a photochemical reaction in the method for detecting the thickness of the wide bandgap semiconductor subsurface damage layer according to the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, the present embodiment provides a technical solution: a method for detecting the thickness of a sub-surface damage layer of a wide bandgap semiconductor comprises the following steps:
step S100, providing a wide bandgap semiconductor wafer, forming conductive layers on the surfaces of two sides of the wide bandgap semiconductor wafer to obtain a wide bandgap semiconductor wafer structure comprising the conductive layers and the wide bandgap semiconductor wafer;
step S200, disconnecting the wide bandgap semiconductor wafer structure to obtain a wide bandgap semiconductor wafer structure detection sheet comprising a cross section, wherein the cross section is a cleavage plane and comprises a damaged layer side surface area and a non-damaged layer side surface area;
step S300, connecting a conductive layer serving as a working electrode in the wide bandgap semiconductor wafer structure detection sheet with a metal catalyst serving as a counter electrode, and soaking the wide bandgap semiconductor wafer structure detection sheet and the metal catalyst into etching liquid, wherein the etching liquid contains an oxidant and a corrosion liquid;
step S400, irradiating the section of the wide bandgap semiconductor wafer structure detection sheet with incident light with the wavelength less than the critical value of the wavelength of the absorbed light corresponding to the wide bandgap semiconductor wafer, and generating photo-generated hole-electron pairs on the section;
step S500, in the irradiation process, photo-generated electrons in the non-damage layer side surface area are enriched on the metal catalyst along a circuit and react with the oxidant, the corrosive liquid etches the non-damage layer side surface area with photo-generated holes, the damage layer side surface area is not etched, and therefore the thickness of the damage layer is obtained according to the shape of the cross section after etching is completed.
Step S100 is executed, and the wide bandgap semiconductor wafer is specifically a silicon carbide wafer or a gallium nitride wafer, where it should be noted that, in order to solve the technical problem, the wide bandgap semiconductor wafer provided in this embodiment is a wide bandgap semiconductor wafer after one of the processing processes of wire cutting, thinning, grinding, and the like.
In this embodiment, the wide bandgap semiconductor wafer is specifically a silicon carbide wafer or a gallium nitride wafer, and the silicon carbide wafer is specifically a 4H-type silicon carbide wafer or a 6H-type silicon carbide wafer.
In addition, since the semiconductor cross section does not undergo photochemical corrosion when the wide bandgap semiconductor wafer is not doped or the doping concentration is too low, in this embodiment, it is set that when the wide bandgap semiconductor wafer is specifically a silicon carbide wafer, the doping concentration range of nitrogen in the silicon carbide wafer is 5 × 10 14 ～3×10 19 /cm 3 When the wide bandgap semiconductor wafer is a gallium nitride wafer, the doping concentration range of silicon in the gallium nitride wafer is 5 × 10 14 ～3×10 19 /cm 3 。
The conductive layer is a metal layer, the metal layer is one of a nickel layer, a titanium layer and an aluminum layer, and the thickness of the metal layer is 100-300 nm.
Executing the step S200, wherein the step of disconnecting the wide bandgap semiconductor wafer structure specifically includes: and breaking the wide bandgap semiconductor wafer structure along the [11-20] direction to obtain the wide bandgap semiconductor wafer structure detection sheet with the cross section.
As shown in fig. 2, the wide bandgap semiconductor wafer structure test piece 1 is a wide bandgap semiconductor wafer structure test piece 1, the wide bandgap semiconductor wafer structure test piece 1 includes a wide bandgap semiconductor wafer 200 and conductive layers 100 plated on two side surfaces of the wide bandgap semiconductor wafer, wherein the wide bandgap semiconductor wafer 200 includes a non-damaged layer 220 and damaged layers 210 located on two sides of the non-damaged layer 220, and the damaged layers in the wide bandgap semiconductor wafer 200 are stress damaged layers generated on a sub-surface region of the wafer because the wide bandgap semiconductor wafer uses cutting abrasive particles as diamond abrasive particles in the processes of on-line cutting, thinning and grinding.
Specifically, in this embodiment, the wide bandgap semiconductor wafer structure is broken along the [11-20] direction to obtain a detection sheet of the wide bandgap semiconductor wafer structure including a cross section, and the obtained cross section is a cleavage plane more easily, where a newly obtained cleavage plane is flat and smooth, and a damage caused by wafer processing is retained without introducing an additional damage, and then, by photochemical selective etching, a thickness of a damage layer caused in a processing process of a silicon carbide wafer can be more accurately quantified, so that detection is more accurate.
Step S300 is executed, in this embodiment, the metal catalyst may specifically be a platinum mesh or the like, the etching solution may specifically be an alkali solution, the alkali solution may specifically be a potassium hydroxide solution, a sodium hydroxide solution, or the like, and an oxidant in the etching solution may specifically be oxygen or the like contained in the etching solution; wherein the concentration range of the alkali solution is 0.01-0.5 mol/L.
In this embodiment, a two-electrode system is adopted, the metal catalyst is used as a counter electrode, the wide bandgap semiconductor wafer structure detection sheet is used as a working electrode, and the two electrodes are directly connected by using a wire to form a circuit short circuit.
As shown in fig. 3, an electrolytic cell 10 is provided, an etching solution 20 is provided in the electrolytic cell 10, a metal catalyst 2 and a wide bandgap semiconductor wafer structure detection sheet 1 having a cross section are provided in the etching solution 20, and the metal catalyst 2 and the wide bandgap semiconductor wafer structure detection sheet 1 form a circuit short circuit through a wire 4.
Step S400 is performed, and in the present embodiment, the light source emitting incident light is specifically one of a xenon lamp, a mercury lamp, an LED lamp, and the like.
When the wide bandgap semiconductor wafer is a gallium nitride wafer, the corresponding critical value of the wavelength of the absorbed light is 365nm, and when the wide bandgap semiconductor wafer is a 4H-type silicon carbide wafer, the corresponding critical value of the wavelength of the absorbed light is 380nm; when the wide bandgap semiconductor wafer is a 6H-type silicon carbide wafer, the threshold value of the wavelength of the corresponding absorbed light is 410nm.
Step S500 is executed, as shown in FIG. 3 and FIG. 4, the irradiation direction of the incident light is shown, during the irradiation process, the photo-generated electrons e in the non-damaged layer side area are enriched on the metal catalyst 2 along the conducting wire 4, and are mixed with O contained in the etching solution 2 React to form OH - 。
And when the wide bandgap semiconductor wafer is specifically a silicon carbide wafer, the photo-generated electrons in the side surface region of the non-damaged layer are enriched on the metal catalyst along a circuit and react with the oxidant, and the step of etching the side surface region of the non-damaged layer with the photo-generated holes by the etching solution specifically comprises the following steps:
and photo-generated electrons in the side area of the non-damage layer are enriched on the metal catalyst along a circuit and are subjected to reduction reaction with the etching solution, the residual photo-generated holes in the side area of the non-damage layer are reacted with Si-C and Si-Si on the surface of the side area of the non-damage layer to generate silicon oxide, and the etching solution is reacted with the silicon oxide to etch the surface of the side area of the non-damage layer.
Specifically, when the wide bandgap semiconductor wafer is a silicon carbide wafer, the photo-generated holes h remaining in the side region of the non-damage layer react with Si-C and Si-Si on the surface of the non-damage layer to generate silicon oxide, and OH in the etching solution reacts with Si-C and Si-Si to generate silicon oxide - Reacts with the silicon oxide of the side area of the non-damaged layer to form
Figure BDA0003856931190000071
When the wide bandgap semiconductor wafer is a gallium nitride wafer, the residual photo-generated holes h in the side region of the non-damage layer react with Ga-N and Ga-Ga on the surface of the non-damage layer to generate gallium oxide, and OH in the etching solution - React with gallium oxide in the side region of the undamaged layer to form
Figure BDA0003856931190000081
Thereby etching the non-damaged layer lateral region.
However, in the side area of the damaged layer, because the stress damaged layer contains a large number of defects such as microcracks, phase change, amorphization and the like, the defects can play a role similar to quantum wells in wide-bandgap semiconductors, so that photo-generated hole-electron pairs can be quickly recombined on the surface of the defects without time for separation, and energy is released in a radiation or non-radiation mode; therefore, in the photochemical corrosion process of the wide-bandgap semiconductor, the phenomenon can occur, namely, the side area of the non-damaged layer is corroded in the participation of the photo-generated holes and the corrosive liquid, and the defects in the side area of the damaged layer have no holes on the surface or have low hole concentration due to the characteristic of quantum wells, so that the defects are not enough to be corroded and are reserved; therefore, the side area of the damaged layer is not etched, and the thickness of the damaged layer can be obtained by observing the shape of the etched section.
In the embodiment, a photochemical corrosion method is adopted to carry out photochemical corrosion on the section of the wide bandgap semiconductor wafer, and the shape of the section of the wafer after reaction can be directly observed through a differential interference microscope and a scanning electron microscope, so that the thickness of a damaged layer of the wide bandgap semiconductor wafer generated in different processing processes can be accurately measured, and the processing loss and the processing cost of the wide bandgap semiconductor material are reduced; fig. 5 and 6 show effect graphs, wherein fig. 5 shows a differential interference microscope picture of a cross section after the photochemical reaction, and fig. 6 shows a scanning electron microscope picture of a cross section after the photochemical reaction, it can be seen that the wide bandgap semiconductor wafer 200 clearly distinguishes the non-damaged layer 220 and the damaged layer 210 after the photochemical reaction is performed on the cross section.
Based on the same inventive concept, the embodiment of the invention also provides a device for detecting the thickness of the wide bandgap semiconductor subsurface damage layer, which comprises an electrolytic bath and a light source;
the electrolytic tank is used for containing etching liquid, a wide bandgap semiconductor wafer structure detection piece and a metal catalyst are arranged in the etching liquid, the wide bandgap semiconductor wafer structure detection piece comprises a wide bandgap semiconductor wafer and conductive layers positioned on the surfaces of two sides of the wide bandgap semiconductor wafer, the conductive layers serving as working electrodes in the wide bandgap semiconductor wafer structure detection piece are connected with the metal catalyst serving as counter electrodes, the section is a cleavage surface, and the section comprises a damaged layer side surface area and a non-damaged layer side surface area;
the light source is arranged at a preset position above the surface of the etching liquid, and incident light with the wavelength smaller than the critical value of the wavelength of the absorbed light corresponding to the wide bandgap semiconductor wafer, which is emitted by the light source, irradiates the section of the wide bandgap semiconductor wafer structure detection sheet, so that a photoproduction hole-electron pair is generated on the section; in the irradiation process, photo-generated electrons in the side area of the non-damaged layer are enriched on the metal catalyst along a circuit and react with the oxidant, the etching liquid etches the side area of the non-damaged layer with photo-generated holes, and the side area of the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the shape of the cross section after etching is completed.
The light source is one of a xenon lamp, a mercury lamp and an LED lamp.
As shown in FIG. 3, a stirrer 3 is further arranged in the etching solution, and the rotating speed range of the stirrer is 300-500 r/min.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.

Claims (10)

1. A method for detecting the thickness of a sub-surface damage layer of a wide bandgap semiconductor is characterized by comprising the following steps:
providing a wide bandgap semiconductor wafer, forming conducting layers on the surfaces of two sides of the wide bandgap semiconductor wafer to obtain a wide bandgap semiconductor wafer structure comprising the conducting layers and the wide bandgap semiconductor wafer;
disconnecting the wide bandgap semiconductor wafer structure to obtain a wide bandgap semiconductor wafer structure detection sheet comprising a cross section, wherein the cross section is a cleavage plane and comprises a damaged layer side area and a non-damaged layer side area;
connecting a conductive layer serving as a working electrode in the wide bandgap semiconductor wafer structure detection sheet with a metal catalyst serving as a counter electrode, and soaking the wide bandgap semiconductor wafer structure detection sheet and the metal catalyst into etching liquid, wherein the etching liquid contains an oxidant and corrosion liquid;
irradiating the section of the wide bandgap semiconductor wafer structure detection sheet with incident light with the wavelength less than the critical value of the wavelength of the absorbed light corresponding to the wide bandgap semiconductor wafer to generate a photo-generated hole-electron pair on the section;
in the irradiation process, photo-generated electrons in the side area of the non-damaged layer are enriched on the metal catalyst along a circuit and react with the oxidant, the etching liquid etches the side area of the non-damaged layer with photo-generated holes, and the side area of the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the shape of the cross section after etching is completed.
2. The method for detecting the thickness of the wide bandgap semiconductor subsurface damage layer according to claim 1, wherein the wide bandgap semiconductor wafer is a silicon carbide wafer or a gallium nitride wafer, and the silicon carbide wafer is a 4H-type silicon carbide wafer or a 6H-type silicon carbide wafer: when the wide bandgap semiconductor wafer is a gallium nitride wafer, the corresponding critical value of the wavelength of the absorbed light is 365nm, and when the wide bandgap semiconductor wafer is a 4H type silicon carbide wafer, the corresponding critical value of the wavelength of the absorbed light is 380nm; when the wide bandgap semiconductor wafer is a 6H-type silicon carbide wafer, the threshold value of the wavelength of the corresponding absorbed light is 410nm.
3. The method for detecting the thickness of the wide bandgap semiconductor sub-surface damage layer as claimed in claim 1, wherein when the wide bandgap semiconductor wafer is a silicon carbide wafer, the doping concentration range of nitrogen in the silicon carbide wafer is 5 x 10 14 ～3×10 19 /cm 3 When the wide bandgap semiconductor wafer is a gallium nitride wafer, the doping concentration range of silicon in the gallium nitride wafer is 5 × 10 14 ～3×10 19 /cm 3 。
4. The method for detecting the thickness of the sub-surface damage layer of the wide bandgap semiconductor of claim 1, wherein the conductive layer is a metal layer, the metal layer is one of a nickel layer, a titanium layer and an aluminum layer, and the thickness of the metal layer is 100-300 nm.
5. The method for detecting the thickness of the sub-surface damage layer of the wide bandgap semiconductor according to claim 1, wherein the step of breaking the wide bandgap semiconductor wafer structure specifically comprises: and breaking the wide bandgap semiconductor wafer structure along the [11-20] direction to obtain the wide bandgap semiconductor wafer structure detection sheet with the cross section.
6. The method for detecting the thickness of the sub-surface damage layer of the wide bandgap semiconductor, according to claim 1, wherein the metal catalyst is a platinum mesh.
7. The method for detecting the thickness of the sub-surface damage layer of the wide bandgap semiconductor according to claim 1, wherein the etching solution is an alkali solution, the alkali solution is a potassium hydroxide solution or a sodium hydroxide solution, and the oxidant is oxygen contained in the etching solution, wherein the concentration of the alkali solution is in a range of 0.01 to 0.5mol/L.
8. The detection device for the thickness of the subsurface damage layer of the wide bandgap semiconductor is characterized by comprising an electrolytic bath and a light source;
the electrolytic tank is used for containing etching liquid, a wide bandgap semiconductor wafer structure detection piece and a metal catalyst are arranged in the etching liquid, the wide bandgap semiconductor wafer structure detection piece comprises a wide bandgap semiconductor wafer and conductive layers positioned on the surfaces of two sides of the wide bandgap semiconductor wafer, the conductive layers serving as working electrodes in the wide bandgap semiconductor wafer structure detection piece are connected with the metal catalyst serving as counter electrodes, the section is a cleavage surface, and the section comprises a damaged layer side surface area and a non-damaged layer side surface area;
the light source is arranged at a preset position above the surface of the etching liquid, and incident light with the wavelength smaller than the critical value of the wavelength of the absorbed light corresponding to the wide bandgap semiconductor wafer, which is emitted by the light source, irradiates the section of the wide bandgap semiconductor wafer structure detection sheet, so that a photoproduction hole-electron pair is generated on the section; in the irradiation process, photo-generated electrons in the side area of the non-damaged layer are enriched on the metal catalyst along a circuit and react with the oxidant, the etching liquid etches the side area of the non-damaged layer with photo-generated holes, and the side area of the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the shape of the cross section after etching is completed.
9. The apparatus for detecting the thickness of the sub-surface damage layer of the wide bandgap semiconductor according to claim 8, wherein the light source is one of a xenon lamp, a mercury lamp and an LED lamp.
10. The device for detecting the thickness of the sub-surface damage layer of the wide bandgap semiconductor of claim 8, wherein a stirrer is further disposed in the etching solution, and the rotation speed of the stirrer ranges from 300 r/min to 500r/min.
CN202211150534.3A 2022-09-21 2022-09-21 Method and device for detecting thickness of wide bandgap semiconductor subsurface damage layer Pending CN115424953A (en)

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