Probe for detecting geometric parameters of inner wall of silicon through hole

Abstract

The invention belongs to the technical field of silicon through hole detection, and particularly relates to a probe for detecting geometric parameters of the inner wall of a silicon through hole. The probe comprises a probe rod and a probe head; the length-diameter ratio of the probe rod is (10-50): 1; the probe head comprises a semi-sphere part and a needle tip, the semi-sphere part and the needle tip are integrally connected, and the tip end of the needle tip is far away from the semi-sphere part; the semi-spherical part is integrally connected with the probe rod, and the included angle between the tip end of the needle tip and the axis of the probe rod is 70-110 degrees; the radius of curvature of the probe tip is 10 nm to 50 nm, and the probe rod and the probe head are both made of tungsten materials. The probe provided by the invention can meet the measurement requirements of the critical dimension and the side wall roughness of the silicon through hole with the depth-to-width ratio greater than 10: 1.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of through-silicon via detection, and particularly relates to a probe for detecting the geometric parameters of the inner wall of a through-silicon via. BACKGROUND

[0002] A through-silicon via is abbreviated as TSV, and the manufacture of the TSV is a core process of advanced packaging of a chip. The process is located in a back-end link of chip manufacturing, and defects of the process can cause a whole wafer to be defective, and determine the packaging quality and performance stability of a 3D chip. According to a research report of the International Semiconductor Industry Association, with an increase in the number of stacked layers of a wafer and a continuous increase in the aspect ratio of the TSV, a whole chip defective rate caused by a single defect of the TSV increases exponentially, and the process quality of the TSV becomes a yield bottleneck of subsequent packaging. Therefore, how to measure and detect the TSV and guarantee a high yield of the production link through quality control are problems to be solved by the advanced packaging industry of the chip.

[0003] A mainstream process of the TSV is a Bosch process, which belongs to a deep reactive ion etching technology. A first process of the process is to process a straight hole with a diameter of 10 to several tens of microns and a depth penetrating through a wafer on a silicon wafer substrate. The initial thickness of a 12-inch wafer is about 775 microns. SF6 fluorine-containing gas and C4F8 fluorocarbon are alternately circulated to vertically etch and protect the silicon substrate material, and the production of a high aspect ratio TSV is realized. Ideally, the inner wall of the TSV should be regular and smooth, but in the process of alternately removing and protecting the silicon material, the Bosch process forms a periodic sawtooth scallop morphology on the sidewall, so that the surface roughness is increased by about 100nm-200nm. If the sidewall roughness is too large, the adhesion of metal filling is reduced, which is not conducive to uniform deposition of the subsequent oxide layer and metal conductive material, and causes problems such as leakage of the dielectric layer and voids of the filling layer. In addition, fluctuations in the etching process parameters can also induce other typical defects of the TSV, such as foot gap, silicon grass, uneven hole depth / hole diameter, and sidewall taper angle. The above geometric size and shape defects can cause failure of the electrical characteristics of the TSV, damage to the structural stability, and out-of-control of the chip thermal management in the later stage. Therefore, after the TSV via is formed, sampling inspection must be performed, and the key size top end and bottom hole diameter, hole depth, sidewall angle and sidewall roughness are accurately measured to prevent defective products from entering the next production link.

[0004] Atomic force microscope, abbreviated as AFM, is a high-resolution technology commonly used for surface roughness measurement, but it can only measure the vertical surface of the sample, and it is difficult to detect the inside of the high aspect ratio hole, especially the imaging of the sidewall of the hole. Through real-time adjustment of the probe direction, the South Korea University of Sejong used high aspect ratio carbon nanotube AFM probe to detect the sidewall inside the high aspect ratio structure, realized 3D imaging of the through hole with an aspect ratio of 4.3, and the resolution reached 2nm; Su-Been et al. tilted the tip of the AFM, designed a scanner that can tilt left and right, improved into a 3D-AFM that can rotate a certain angle in the vertical plane, and realized the scanning of the sidewall, but the existing technology is limited to the imaging of the sidewall of the groove. The core component of AFM is the tip of its probe, and Xi'an Jiaotong University assembles carbon nanotubes CNT on the silicon probe of AFM, and the diameter of the nanometer probe tip prepared by CNT is as low as 10nm, which is a CNT tip in the shape of a “pyramid” grown on a silicon-based cantilever, which has been successfully used in many domestic measurement institutions. In addition, some scholars design and prepare special-shaped probes such as horn-shaped probes and three-pronged probes to realize 3D scanning of the sidewall. However, the longitudinal detection depth of the above-mentioned AFM probe size is not enough, the length of the AFM probe is 125μm~225μm, and the aspect ratio is 3~8. When measuring a deeper TSV hole, the existing AFM probe cannot balance high resolution and large aspect ratio, and even by tilting the probe, the whole picture inside the hole cannot be characterized. Therefore, the AFM probe is not suitable for TSV inner size measurement with an aspect ratio greater than 10. SUMMARY

[0005] In order to solve the above problems, the application provides a probe for detecting the geometric parameters of the inner wall of a through silicon via.

[0006] A probe for detecting the geometric parameters of the inner wall of a through silicon via, comprising a probe rod and a probe head; The aspect ratio of the probe rod is 10:1~50:1; The probe head comprises a semicircular ball part and a tip, the semicircular ball part and the tip are integrally connected, and the tip end of the tip is away from the semicircular ball part; The semicircular ball part is integrally connected with the probe rod, and the included angle between the tip end of the tip and the axis of the probe rod is 70°~110°; The radius of curvature of the tip is 10nm~50nm; The probe rod and the probe head are both made of tungsten.

[0007] The application adopts tungsten material as the probe rod and the probe head. The tungsten wire material has high rigidity and hardness. In addition, the long tungsten wire will cause insufficient rigidity of the probe rod, and bending will occur during contact measurement. The ratio of length to diameter of 10-30:1 can realize the measurement of the TSV inner size with the aspect ratio greater than 10, and the rigidity of the probe can be ensured. The semispherical part is integrally connected with the probe rod, so that the probe can be scanned in the hole or subjected to lateral force, the semispherical root can effectively share the bending moment, the stress concentration crack in the rod-needle transition zone is avoided, and the probe still has good rigidity and structural strength under the condition of the length to diameter ratio of 10-30:1. The structural design of the semispherical part and the needle tip integrally connected can further improve the overall structural strength and rigidity of the probe, so that deformation and wear do not occur during the measurement of the TSV inner size with the aspect ratio greater than 10. The angle between the tip of the needle tip and the axis of the probe rod is 70°-110°, which is used to realize accurate measurement of the side wall angle and the side wall roughness. During the detection process, the probe does not need to be inclined, and the overall appearance in the hole can also be represented. The curvature radius of the needle tip is 10nm-50nm, which can improve the sharpness of the needle tip and realize high-resolution measurement of the TSV side wall surface roughness.

[0008] In another preferred embodiment, the diameter of the probe rod is 60μm-100μm. The diameter can ensure that it is suitable for most silicon through hole detection. If the diameter of the tungsten wire is too small, the rigidity and structural strength of the probe rod will be insufficient under the length to diameter ratio of 10-30:1, which will affect the detection accuracy. Since the diameter of the silicon through hole is generally below 100μm, if the diameter of the tungsten wire is too large, the probe rod cannot enter the silicon through hole for detection.

[0009] In another preferred embodiment, one side of the probe rod is tangent to the arc part of the semispherical part. Through the tangent mode, the semispherical part will not produce multi-line contact or wedge phenomenon on the hole wall during the detection process, the cantilever deflection signal can be directly mapped to the real topography of the hole wall, and the artifacts are eliminated.

[0010] In another preferred embodiment, the ratio of the radius of the semispherical part to the diameter of the probe rod is 2-3:1.

[0011] In another preferred embodiment, the ratio of the length of the needle tip to the radius of the semispherical part is 2-3:1. Under this ratio, the rigidity of the needle tip during use can be ensured, so that the needle tip is more rigid and can withstand the friction of the TSV side wall and the scanning shear force without buckling or breaking.

[0012] In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013] In another preferred embodiment, when the probe rod is conical, the semispherical part is integrally connected with the smaller end of the probe rod. In another preferred embodiment, the probe rod is cylindrical or conical.

[0013]

[0014] In another preferred embodiment, the diameter of the cross section at the junction of the needle tip and the semi-spherical portion is the same as the diameter of the semi-spherical portion.

[0015] In another preferred embodiment, the probe shaft and the probe head are both made of tungsten.

[0016] Compared with the prior art, the present application has the following beneficial effects.

[0017] In the present application, the probe head is composed of a semi-spherical portion and a needle tip portion. By controlling the included angle between the needle tip and the probe shaft axis to be 70°-110°, the probe can be vertically inserted into the TSV hole when measuring a relatively deep TSV hole, thereby realizing characterization of the 3D size and morphology inside the TSV hole, and significantly improving the detectability of the physical probe for the size of a micro-hole with a high aspect ratio. The radius of curvature of the needle tip is 10-50 nm, which can improve the sharpness of the needle tip and realize high-resolution measurement of the surface roughness of the TSV sidewall. The length-diameter ratio of the probe shaft is 10-50:1, which can realize in-depth detection of the inside of a TSV hole with a large aspect ratio, and realize the measurement requirements of typical TSV key sizes and sidewall roughness with a lateral size of 50-100 μm and an aspect ratio greater than 10:1. The integral connection of the probe shaft and the semi-spherical portion, and the integral connection of the semi-spherical portion and the needle tip make the obtained probe have good structural strength and rigidity, and are not prone to deformation and wear during the measurement process, have a long service life, and can ensure the reliability of the measurement results of the probe during service. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Fig. 1 is a structural schematic diagram of the probe of the present application.

[0019] Figure 2 Fig. 2 is a structural schematic diagram of the probe head of the present application.

[0020] BRIEF DESCRIPTION OF DRAWINGS: 1-probe shaft, 2-probe head, 21-semi-spherical portion, 22-needle tip. DETAILED DESCRIPTION

[0021] The specific embodiments of the present application are described in detail below, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments. Based on the examples in the present application, all other examples obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application. The experimental methods described in the embodiments of the present application are conventional methods unless otherwise specified.

[0022] At present, AFM is limited by the probe size, and the longitudinal detection depth is insufficient. The length of the existing AFM probe is 125-225 mu m, and the aspect ratio is 3-8:1. The specific parameters are shown in Table 1. When measuring a deep TSV hole, the existing AFM probe cannot accurately detect the geometric parameters of the inner wall of the silicon through hole due to the insufficient sharpness of the needle tip, i.e. the large radius of curvature, thereby reducing the detection accuracy. Although the carbon nanotube tip in the form of a pyramid is assembled on the AFM silicon probe to reduce the needle diameter and improve the sharpness of the needle tip to achieve high resolution of the silicon through hole, it cannot achieve an aspect ratio greater than 10. It can be seen that the existing AFM probe cannot simultaneously consider high resolution and large aspect ratio. Even by tilting the probe, it can only touch the shallow layer of the deep hole and cannot represent the overall appearance of the hole. Therefore, the existing AFM probe is not suitable for TSV inner size measurement with a depth-width ratio greater than 10.

[0023] Table 1: Parameters of existing AFM probe

[0024] Therefore, the present application provides a probe for detecting the geometric parameters of the inner wall of the silicon through hole, which improves the longitudinal detection depth by an aspect ratio of 10-50:1. The probe head is composed of a semicircular spherical part and a needle tip part. By controlling the radius of curvature of the needle tip, the sharpness of the needle tip is improved, so that the detection of the silicon through hole can be more accurately realized, and the included angle between the tip of the needle tip and the axis of the probe rod is 70-110°. In the detection process, the probe does not need to be tilted, thereby improving the depth that the probe can touch and the detection accuracy.

[0025] The following describes a probe for detecting a silicon through hole.

[0026] The present application provides a probe for detecting a silicon through hole, as shown in Figure 1 The probe includes a probe rod 1 and a probe head 2.

[0027] The aspect ratio of the probe rod 1 is 10-50:1. In this embodiment, the aspect ratio of the probe rod 1 is 10:1. The probe rod 1 is cylindrical or conical. In this embodiment, the probe rod 1 is conical, and the taper is 85-89°, and the diameter is 60 mu m, so as to extend into the narrow space of the TSV inner hole to measure the side wall.

[0028] As shown in Figure 2As shown, the probe head includes a semicircular ball portion 21 and a needle tip 22, by setting the semicircular ball portion 21, the root thereof, i.e. the circular arc portion, can effectively share the bending moment, avoiding stress concentration cracks in the rod-needle transition zone; specifically, the semicircular ball portion 21 and the needle tip 22 are integrally connected; and the tip of the needle tip 22 is away from the semicircular ball portion 21; the semicircular ball portion 21 is integrally connected with the probe rod 1, and the structure design that the semicircular ball portion 21 is integrally connected with the needle tip 22 can further improve the overall structural strength and rigidity of the probe. The included angle between the tip of the needle tip 22 and the axis of the probe rod 1 is 70°-110°, and this angle can facilitate accurate measurement of the side wall angle and the side wall roughness of the probe, and in the embodiment, the included angle is 90°; the radius of curvature of the needle tip 22 is 10 nm-50 nm, which can improve the sharpness of the needle tip, and in the embodiment, the radius of curvature is 30 nm. The semicircular ball portion 21 is integrally connected with the smaller end of the probe rod 1, and one side of the probe rod 1 is tangent to the circular arc of the semicircular ball portion 21, and through the tangential mode, when the probe scans in the hole or encounters lateral force, the root of the semicircular ball portion 21 can effectively share the bending moment, avoiding stress concentration cracks in the rod-needle transition zone, in addition, the semicircular ball portion 21 will not produce multi-line contact or wedge phenomenon on the hole wall during the detection process, and the cantilever deflection signal can be directly mapped to the real topography of the hole wall, eliminating artifacts. The ratio of the radius of the semicircular ball portion 21 to the diameter of the probe rod 1 is 2-3:1, and in the embodiment, the ratio of the radius of the semicircular ball portion 21 to the diameter of the probe rod 1 is 2:1, and the diameter of the cross section at the connection between the needle tip 22 and the semicircular ball portion 21 is the same as the diameter of the semicircular ball portion 21. By controlling the taper of the probe rod 1, the included angle between the tip of the needle tip 22 and the axis of the probe rod 1, and the radius of curvature, the probe can be ensured to be both slender enough and have high rigidity, and can maintain negligible deformation in nanoscale contact measurement, thereby ensuring measurement accuracy.

[0029] The probe rod 1 and the probe head 2 are both tungsten material, and the surface of the probe head 2 is coated with a nanoscale wear-resistant coating, specifically, the nanoscale coating is an Al2O3 coating obtained by atomic layer deposition or chemical vapor deposition, and the thickness of the Al2O3 coating is 0.05 μm.

[0030] The above embodiment is a preferred embodiment of the present application, but the embodiments of the present application are not limited to the above embodiment, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement modes, and all shall be included in the protection scope of the present application.

Claims

1. A probe for detecting the geometric parameters of the inner wall of a through-silicon via (TSV), characterized in that, Includes probe rod (1) and probe head (2); The length-to-diameter ratio of the probe rod (1) is 10~50:1; The probe head (2) includes a hemispherical part (21) and a needle tip (22), the hemispherical part (21) and the needle tip (22) are integrally connected, and the tip of the needle tip (22) is far away from the hemispherical part (21). The hemispherical part (21) is integrally connected to the probe rod (1), and the angle between the tip of the needle (22) and the axis of the probe rod (1) is 70°~110°. The radius of curvature of the needle tip (22) is 10nm~50nm; Both the probe rod (1) and the probe head (2) are made of tungsten.

2. The probe for detecting the geometric parameters of the inner wall of a through-silicon via according to claim 1, characterized in that, The diameter of the probe rod (1) is 60μm~100μm.

3. The probe for detecting the geometric parameters of the inner wall of a through-silicon via according to claim 1, characterized in that, One side of the probe rod (1) is tangent to the arc portion of the hemispherical part (21).

4. The probe for detecting the geometric parameters of the inner wall of a through-silicon via according to claim 1, characterized in that, The ratio of the radius of the hemispherical portion (21) to the diameter of the probe rod (1) is 2~3:

1.

5. The probe for detecting the geometric parameters of the inner wall of a through-silicon via according to claim 1, characterized in that, The ratio of the length of the needle tip (22) to the radius of the hemispherical portion (21) is 2~3:

1.

6. The probe for detecting the geometric parameters of the inner wall of a through-silicon via according to claim 1, characterized in that, The probe rod (1) is cylindrical or conical.

7. The probe for detecting the geometric parameters of the inner wall of a through-silicon via according to claim 6, characterized in that, When the probe rod (1) is conical, the hemispherical part (21) is integrally connected to the smaller end of the probe rod (1).

8. The probe for detecting the geometric parameters of the inner wall of a through-silicon via according to claim 1, characterized in that, The diameter of the cross section at the junction of the needle tip (22) and the hemispherical portion (21) is the same as the diameter of the hemispherical portion (21).

9. The probe for detecting the geometric parameters of the inner wall of a through-silicon via according to claim 1, characterized in that, The probe head (2) is coated with a nano-scale wear-resistant coating.

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