Mirror reflection stage

Abstract

A specular reflection stage includes a wafer stage bearing a wafer having a physical property of being penetrable in a range from ultraviolet light to near infrared light, and detecting crystal defects on the surface and inside of the wafer through second order and higher order (more than third order) nonlinear optics; the wafer stage is provided with a mirror reflection structure, and the mirror reflection structure faces the lower surface of the wafer; incident light of the second-order and high-order nonlinear optics acts on the wafer to generate signal light which is not equal to the wavelength of the incident light, the signal light is reflected on the specular reflection structure to become specular reflection light which is not equal to the wavelength of the incident light, and whether a crystal of the wafer has flaws or not can be judged by analyzing the specular reflection light. The detection sensitivity is improved through the mirror reflection structure.

Description

Technical Field

[0001] The present invention relates to a technology for detecting crystal defects of wafers using nonlinear optics. More specifically, the present invention provides a mirror reflection carrier, which is used to carry wafers and improve the sensitivity of nonlinear optical detection with its mirror reflection structure. Background Art

[0002] Silicon carbide (SiC) substrates are required for the manufacture of high-frequency and high-power chips. The internal structure of the SiC substrate must be flawless, high-quality crystal to guarantee the quality of the SiC wafer. Therefore, detecting crystal defects within the SiC substrate is crucial.

[0003] Currently, critical crystal defects can only be detected through destructive KOH etching for sampling. This destructive detection method wastes valuable silicon carbide (SiC) substrates, resulting in high costs. Sampling detection also fails to accurately reflect the complete crystal column defect status, making it difficult to serve as a basis for process improvement and an effective tool for advancing silicon carbide (SiC) crystal column manufacturing technology.

[0004] In view of the above problems, the industry has introduced non-destructive detection technology, which uses nonlinear optics (NLO) technology to detect crystal defects on the surface and inside of silicon carbide (SiC) substrates.

[0005] The following are technical documents related to nonlinear optical detection.

[0006] Patent application CN117929395A proposes a third-generation semiconductor 3D defect detection method that uses a near-infrared laser to scan a sample on a moving platform. After the infrared scan, the sample is judged to be defective based on the feedback signal. Using nonlinear optical technology, the interaction between the optical and substrate materials generates a doubled frequency signal. Based on this principle, the feedback signal is used to determine if the sample is defective.

[0007] CN114577727A discloses a second harmonic characterization optical system and a detection device based on second harmonic characterization. The incident optical path system transmits fundamental frequency light to the sample to be detected. After the fundamental frequency light is incident on the sample to be detected, a second harmonic generation (SHG) signal carrying information about the sample defects is generated, and the second harmonic signal is emitted along the direction of the light beam reflected from the surface of the sample to be detected. Utility Model Content

[0008] The purpose of the utility model is to provide a mirror reflection carrier, which is used for carrying wafers and improves the sensitivity of nonlinear optical detection by its mirror reflection structure.

[0009] Technical solution of this utility model:

[0010] A mirror reflection carrier includes a wafer carrier, which carries a wafer. The wafer has the physical property of being transparent in the range of ultraviolet light to near-infrared light. Crystal defects on the surface and inside of the wafer are detected through second-order and higher-order (third-order and above) nonlinear optics. The wafer carrier is provided with a mirror reflection structure, which faces the lower surface of the wafer. The mirror reflection structure is configured such that: an incident light of the second-order and higher-order nonlinear optics acts on the wafer to generate signal light with a wavelength not equal to that of the incident light. The signal light is reflected on the mirror reflection structure to become mirror reflection light with a wavelength not equal to that of the incident light. By analyzing the mirror reflection light, it can be determined whether the crystal of the wafer has defects.

[0011] Preferably, the mirror reflection structure contacts the lower surface of the wafer.

[0012] Preferably, there is a gap between the mirror reflection structure and the lower surface of the wafer.

[0013] Preferably, the area of ​​the mirror reflection structure is greater than or equal to the area of ​​the wafer.

[0014] Preferably, the mirror reflection structure includes a carrier, the carrier carrying an optical coating; the carrier is fixed on the wafer stage, and the optical coating faces the lower surface of the wafer.

[0015] Preferably, the mirror reflection structure is a high-precision polished surface formed by polishing the surface of the wafer stage.

[0016] Preferably, the mirror reflection structure is a mirror reflection film, and the mirror reflection film covers the surface of the wafer stage for supporting the wafer.

[0017] Preferably, the mirror reflection structure is a metal reflection plate having a high-precision polished surface; the metal reflection plate is fixed on the wafer stage, and the high-precision polished surface faces the lower surface of the wafer.

[0018] Preferably, the surface roughness of the high-precision polished surface reaches Ra 0.008μm to 0.1μm.

[0019] This system uses second-order and higher-order (third-order and above) nonlinear optical technology to detect crystal defects on and within wafers. An incident light path system projects incident light onto the wafer. This incident light, upon impacting the wafer, generates signal light of a wavelength different from the incident light. This signal light is reflected by the mirror reflection structure as mirror-reflected light of a wavelength different from the incident light. This light then exits the wafer surface and is received by a detector. An output light path system coupled to the detector analyzes the mirror-reflected light to determine whether the wafer contains crystal defects. This mirror reflection structure enhances detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is one of the side view schematic diagrams of the present utility model.

[0021] Figure 2 This is the second side view schematic diagram of the present utility model.

[0022] Figure 3 The first embodiment of the present invention is described with a side view schematic diagram.

[0023] Figure 4 The second embodiment of the present invention is described in a side view schematic diagram.

[0024] Figure 5 The third embodiment of the present invention is described in a side view schematic diagram.

[0025] Figure 6 The fourth embodiment of the present invention is described in a side view schematic diagram.

[0026] Figure 7 The side view schematic diagram is used to describe the implementation of nonlinear optical detection in the present invention. DETAILED DESCRIPTION

[0027] To facilitate the explanation of the central concept of the present invention as described above, specific embodiments are provided. The various objects in the embodiments are depicted in proportions, sizes, deformations, or displacements appropriate for the description, rather than in scale with the actual components. This is to be noted.

[0028] like Figure 1 The mirror reflective stage 10 of the present invention includes a wafer chuck 11 for carrying a wafer 12. The wafer chuck 11 is provided with a mirror reflective structure 20 facing the lower surface 121 of the wafer 12.

[0029] The wafer 12 has the physical property of being transparent to light in the ultraviolet to near-infrared range, and includes, but is not limited to, silicon carbide (SiC) wafers 12. In the present invention, second-order and higher-order (third-order or higher) nonlinear optical detection techniques are used to determine whether crystal defects exist on or within the wafer 12 having such physical properties.

[0030] exist Figure 1 In the embodiment, the mirror reflective structure 20 contacts the lower surface 121 of the wafer 12, but is not limited thereto. Figure 2 As shown, there is a gap D between the mirror reflection structure 20 and the lower surface 121 of the wafer 12 .

[0031] The area of ​​the mirror reflective structure 20 is consistent with the area of ​​the wafer 12 . Specifically, the area of ​​the mirror reflective structure 20 should be greater than or equal to the area of ​​the wafer 12 so that the lower surface 121 of the wafer 12 is fully covered by the mirror reflective structure 20 .

[0032] like Figure 3 The first embodiment of the mirror reflective structure 20 includes a carrier 21 that carries an optical coating 22. The optical coating 22 can achieve specular reflection. The carrier 21 is fixed to the wafer stage 11 using known techniques such as vacuum adsorption or fixture fixation, with the optical coating 22 facing the lower surface 121 of the wafer 12.

[0033] like Figure 4 The second embodiment of the mirror reflection structure 20 is shown. The mirror reflection structure 20 includes a high-precision polished surface 23 formed on the surface of the wafer carrier 11 through mirror processing technology. The material of the wafer carrier 11 is a material with light reflective properties (including but not limited to stainless steel). Mirror processing technology is applied to the surface of the wafer carrier 11 used to support the wafer 12, thereby forming the high-precision polished surface 23 with a surface roughness of Ra 0.008μm to 0.1μm, thereby achieving mirror reflection. Mirror processing technology includes but is not limited to mechanical polishing.

[0034] like Figure 5 The mirror reflection structure 20 is a third embodiment. The mirror reflection structure 20 includes a mirror reflection film 24 covering the surface of the wafer stage 11 for supporting the wafer 12 .

[0035] like Figure 6The fourth embodiment of the mirror reflective structure 20 includes a metal reflective plate 25 having a high-precision polished surface 26 formed by mirror processing technology. The surface roughness of the high-precision polished surface 26 reaches Ra 0.008μm to 0.1μm, thereby achieving mirror reflection. The metal reflective plate 25 is fixed to the wafer carrier 11 by known technical means such as vacuum adsorption or fixture fixation, with the high-precision polished surface 26 facing the lower surface 121 of the wafer 12.

[0036] like Figure 7 , using second-order and higher-order (third-order or higher) nonlinear optics to detect crystal defects on and within the wafer 12. An incident light path system 31 projects an incident light 32 onto the wafer 12. The incident light 32 acts on the wafer 12 to generate signal light having a wavelength different from the incident light. The signal light is reflected by the mirror reflection structure 20 to form mirror-reflected light 33 having a wavelength different from the incident light. The mirror-reflected light 33 is emitted from the surface of the wafer 12 and received by a detector 34. The output light path system coupled to the detector 34 analyzes the mirror-reflected light 33 to determine whether the wafer 12 has crystal defects.

[0037] The above is a preferred embodiment of the present invention and the technical principles used therein. For those skilled in the art, any obvious changes such as equivalent transformations, simple replacements, etc. based on the technical solution of the present invention, without departing from the spirit and scope of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A mirror reflection stage, comprising a wafer stage, the wafer stage carrying a wafer having the physical property of being transparent to light ranging from ultraviolet to near-infrared, and detecting crystal defects on and within the wafer using second-order and higher-order nonlinear optics; Its characteristics are: The wafer stage is provided with a mirror reflection structure, and the mirror reflection structure faces the lower surface of the wafer; The mirror reflection structure is configured such that an incident light of the second-order and higher-order nonlinear optics acts on the wafer, generating a signal light having a wavelength that is not equal to the incident light. The signal light is reflected on the mirror reflection structure and becomes a mirror reflection light having a wavelength that is not equal to the incident light. By analyzing the mirror reflection light, it is determined whether the crystal of the wafer has defects.

2. The mirror reflection stage according to claim 1, wherein: The mirror reflection structure contacts the lower surface of the wafer.

3. The mirror reflection stage according to claim 1, wherein: There is a gap between the mirror reflection structure and the lower surface of the wafer.

4. The mirror reflection stage according to claim 1, wherein: The area of ​​the mirror reflection structure is greater than or equal to the area of ​​the wafer.

5. The mirror reflection stage according to claim 1, wherein: The mirror reflection structure includes a carrier, and the carrier carries an optical coating; the carrier is fixed on the wafer stage, and the optical coating faces the lower surface of the wafer.

6. The mirror reflection stage according to claim 1, wherein: The mirror reflection structure is a high-precision polishing surface formed by polishing the surface of the wafer carrier.

7. The mirror reflection stage according to claim 1, wherein: The mirror reflection structure is a mirror reflection film, and the mirror reflection film covers the surface of the wafer carrier for carrying the wafer.

8. The mirror reflection stage according to claim 1, wherein: The mirror reflection structure is a metal reflection plate having a high-precision polishing surface. The metal reflection plate is fixed on the wafer carrier, and the high-precision polishing surface faces the lower surface of the wafer.

9. The mirror reflection stage according to claim 6 or 8, wherein: The surface roughness of the high-precision polished surface reaches Ra 0.008μm to 0.1μm.

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