Probe card and method of manufacturing the same

Abstract

Provided is a probe card capable of simultaneous measurement of both the optical and electrical characteristics of an opto-electronic device. The present invention is provided with probe pins for measuring the electrical characteristics, inserted into via holes formed in a substrate, and optical fibers for measuring the optical characteristics, inserted into via holes formed in the substrate.

Description

[Technical Field]

[0001] The present invention relates to a probe card, and more particularly to a probe card capable of simultaneously measuring both the optical and electrical characteristics of an optoelectronic device in which optical elements and optical circuits are integrated, and a method for manufacturing the same. [Background technology]

[0002] Semiconductor devices are manufactured by performing various processes on a semiconductor wafer to form multiple chips (or dies) with electronic circuits formed on them, and then cutting the wafer into multiple chips using a dicing saw, thereby manufacturing multiple semiconductor devices at once. During the semiconductor manufacturing process, the electrical characteristics of each chip are measured using an inspection system consisting of a prober and a tester. The prober contacts the probe pins of a probe card with the electrodes formed on each chip on the wafer fixed to the wafer chuck. The tester is electrically connected to the probe pins and applies a voltage or current to the electronic circuit of each chip, measuring various electrical characteristics via the probe pins.

[0003] Meanwhile, advances in silicon photonics technology have led to the mass production of optoelectronic devices that integrate electronic circuits with optical elements and optical circuits (see, for example, Non-Patent Document 1). Optoelectronic devices fabricated on silicon wafers require measurements of the electrical characteristics of the electronic circuits and the optical characteristics of the optical elements and optical circuits. Optical characteristics are measured by optically coupling optical elements attached to a probe card with grating couplers, elephant couplers, and the like in optical circuits pre-formed on each chip (see, for example, Non-Patent Document 2). Therefore, electrical and optical characteristics have been measured separately using different probe cards. In addition, when measuring optical characteristics, alignment between the optical elements on the probe card and the optical circuits must be performed for each chip, which requires a lot of time for testing during the manufacturing process. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] AE Lim et al., "Review of Silicon Photonics Foundry Efforts," in IEEE Journal of Selected Topics in Quantum Electronics, vol. 20, no. 4, pp. 405-416, July-Aug. 2014, Art no. 8300112, doi: 10.1109 / JSTQE.2013.2293274. [Non-patent document 2] J. De Coster et al., "Test-station for flexible semi-automatic wafer-level silicon photonics testing," 2016 21th IEEE European Test Symposium (ETS), Amsterdam, 2016, pp. 1-6, doi: 10.1109 / ETS.2016.7519306. Summary of the Invention

[0005] An object of the present invention is to provide a probe card capable of simultaneously measuring both the optical and electrical characteristics of an optoelectronic device, and a method for manufacturing the same.

[0006] In order to achieve the above object, one embodiment of the present invention is a probe card for measuring electrical and optical characteristics of an optoelectronic device, the probe card being inserted into a first via hole formed in a substrate and used to measure the electrical characteristics. attached vertically from the substrate The device is characterized by comprising a probe pin and an optical fiber that is inserted into a second via hole formed in the substrate and is used to measure the optical characteristics, the optical fiber having an attachment angle different from that of the probe pin.

[0007] Another embodiment is a method for manufacturing a probe card for measuring the electrical and optical characteristics of an optoelectronic device formed on a wafer, comprising the steps of: forming a via hole in a substrate; depositing a metal plating on the substrate for fixing a probe pin for measuring the electrical characteristics; inserting an optical fiber for measuring the optical characteristics into the via hole and fixing it so that it protrudes slightly from the surface facing the wafer; polishing the surface of the substrate facing the wafer; and inserting the probe pin into the via hole and fixing it in the area where the metal plating is formed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an inspection device according to one embodiment of the present invention; [Figure 2] FIG. 2 is a diagram showing a schematic configuration of a probe card for the inspection device of this embodiment; [Figure 3] FIG. 3 is a diagram showing another example of a probe card for the inspection apparatus of this embodiment; [Figure 4] FIG. 4 is a diagram showing a manufacturing process of a probe card according to Example 1 of the present invention; [Figure 5] FIG. 5 is a diagram showing a manufacturing process of a probe card according to Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0010] 1 shows a schematic configuration of an inspection apparatus according to one embodiment of the present invention. The inspection apparatus is composed of a prober 1 and a tester 2. A silicon wafer 31 on which an optoelectronic device to be inspected is formed is fixed to a wafer chuck 13 and moved in three axial directions by a drive mechanism 12 on a base 11. A probe card 21 is fixed via a circuit board 22 to a test head 23 connected to the tester 1. The tester 1 controls the drive mechanism 12 to bring probe pins 24 of the probe card 21 into contact with electrodes formed on each chip of the silicon wafer 31. The probe pins 24 are connected to the tester 1 via the circuit board 22 and the test head 23.

[0011] The probe pins 24 of the probe card 21 of this embodiment include an electric probe for measuring electrical characteristics and an optical probe for measuring optical characteristics. The test head 23 also includes an optical element optically coupled to the optical probe, an optical circuit, an optical / electrical converter, and an electrical / optical converter, and exchanges electrical signals with the tester 1, enabling measurement of optical characteristics.

[0012] Fig. 2 shows a schematic configuration of a probe card for the inspection apparatus of this embodiment. As shown in Fig. 2(a), the probe card 21 has a configuration in which an electric probe and an optical probe are connected to a substrate 101 made of silicon (Si) or silica (SiO2) for each region 102 corresponding to one chip of an electronic circuit, optical element, and optical circuit formed on a silicon wafer. The substrate 101 has a circular shape that matches the shape of the silicon wafer to be measured.

[0013] Figure 2(b) is an enlarged view of the area 102 corresponding to one chip, showing the connection of the electric probe 201 and the optical probes 103-106. By using this probe card, the electrical and optical characteristics of multiple chips on a wafer can be measured at once. This allows for a significant reduction in the number of inspection processes and improves throughput in the manufacturing process.

[0014] Optical probes 103-106 are optical fiber cores with an outer diameter of 125 μm, and are attached so that their optical axes are perpendicular to the surface of substrate 101. Electric probe 201 is a probe pin made of an alloy such as beryllium copper, and is divided into a pipe and a contact pin (also called a plunger) at the tip, and various types of electric probes can be used, such as those with a structure that allows the contact pin to be replaced or those with a structure that has a spring mechanism built into the pipe.

[0015] The probe card of this embodiment is a so-called vertical probe card, and while the pitch of probe pins in a general probe card for semiconductor devices is about 500 μm, it is possible to narrow the pitch to about 200 μm.

[0016] 3 shows another example of a probe card for use in the inspection apparatus of this embodiment. As described above, optical characteristics are measured by optically coupling the tips of optical probes 103-106 attached to the probe card with grating couplers, elephant couplers, etc., in the optical circuits pre-formed on each chip. Therefore, the attachment angle of optical probes 103-106 to substrate 101 is tilted from the vertical direction so that the direction of light emitted from optical elements such as grating couplers in the optical circuits is aligned with the optical axis of the optical fiber.

[0017] The probe card of this embodiment is connected to the test head 23 via the circuit board 22 shown in FIG. 1 for testing. The alignment of the probe card and the wafer is performed using as an index the coupling rate when light emitted from the optical elements in the optical circuit is coupled to the end faces of the optical probes 103-106. As mentioned above, the direction of light emitted from the optical elements may be tilted diagonally upward from the substrate, and the angle of the probe may also be tilted accordingly. By tilting the probe at an angle, reflection at the end face can be minimized. [Example]

[0018] 4 shows the steps for fabricating a probe card according to Example 1 of the present invention. A substrate 301 made of silicon (Si) or silica (SiO2) is prepared (step 1), and a resist 302 for forming via holes is applied (step 2). After patterning the positions where the via holes will be formed by photolithography (step 3), the via holes are formed by etching (step 4). The diameter of via hole 303a for the optical probe is 125 μm, and the diameter of via hole 303b for the electrical probe is determined taking into consideration the diameter of the probe pin and the thickness of the metal-plated inner wall of the via hole.

[0019] After removing the remaining resist 302a (step 5), in the case of a silicon substrate, heat treatment is performed to form an insulating film 304 (step 6). Resist 305 for metal plating is applied and patterned by photolithography (step 7). The metal plating is applied to the inner walls of via holes 303b for the electric probes and to the solder areas around the via holes 303b for fixing the probe pins of the electric probes. After forming metal plating 306 (step 8), the remaining resist 305 is removed (step 9).

[0020] An optical fiber 307 is inserted into the via hole 303a for the optical probe and fixed to the top surface of the substrate, i.e., the surface opposite the surface facing the wafer, using adhesive 308 (step 10). At this time, the end face of the optical fiber 307 is left slightly protruding from the surface facing the wafer. The bottom surface 309 of the substrate, i.e., the surface facing the wafer, is polished to remove the metal plating 306, and the end face of the optical fiber 307 is also polished to make it flush (step 11).

[0021] Finally, a probe pin 310 of the electric probe is inserted into the via hole 303b for the electric probe and fixed to the solder area of ​​the remaining metal plating 306a using solder 311 (step 12).

[0022] The method for forming via holes in Example 1 can apply conventional photolithography and etching processes for forming optical circuits on silicon substrates, resulting in high processing accuracy and easily achieving a narrow pitch for the probe pins of the probe card. [Example]

[0023] 5 shows the steps of fabricating a probe card according to Example 2 of the present invention. A substrate 301 made of silicon (Si) or silica (SiO2) is prepared (Step 1), and a resist 302 for forming via holes for the electric probes is applied (Step 2). After patterning the positions where the via holes will be formed by photolithography (Step 3), the via holes are formed by etching (Step 4). The diameters of the via holes 303a and 303b for the electric probes are determined taking into consideration the diameter of the probe pins and the thickness of the metal-plated inner walls of the via holes.

[0024] After removing the remaining resist 302a (step 5), in the case of a silicon substrate, heat treatment is performed to form an insulating film 304 (step 6). Resist 305 for metal plating is applied and patterned by photolithography (step 7). The metal plating is applied to the inner walls of via holes 303a and 303b for the electric probes and to the solder areas around the via holes 303a and 303b for fixing the probe pins of the electric probes. After forming metal plating 306 (step 8), the remaining resist 305 is removed (step 9).

[0025] Next, a resist 321 is applied to form a via hole for the optical probe (Step 10). After patterning the position where the via hole is to be formed by photolithography (Step 11), the via hole 322 is formed by etching (Step 12). The diameter of the via hole 322 for the optical probe is 125 μm.

[0026] The remaining resist 321a is removed (step 13), and an optical fiber 307 is inserted into the via hole 322 for the optical probe and fixed with adhesive 308 to the top surface of the substrate, i.e., the surface opposite the surface facing the wafer (step 14). At this time, the end face of the optical fiber 307 is left slightly protruding from the surface facing the wafer. The bottom surface 309 of the substrate, i.e., the surface facing the wafer, is polished to remove the metal plating 306, and the end face of the optical fiber 307 is also polished to make it flush (step 15).

[0027] Finally, probe pins 310a and 310b of the electric probe are inserted into via holes 303a and 303b for the electric probe, and fixed to the soldered areas of the remaining metal plating 306a using solders 311a and 311b (step 12).

[0028] In the method for forming via holes according to the second embodiment, the via holes for the electric probes and the via holes for the optical probes are formed in separate processes. As shown in Fig. 3, when the electric probe 201 is installed vertically to the substrate 101 and the optical probes 103-106 are installed at an angle from the vertical direction to the substrate 101, the via holes for the former are formed vertically and the via holes for the latter are formed at an angle from the vertical direction. According to the second embodiment, the directions of the via holes for the electric probes and the via holes for the optical probes can be changed, thereby increasing the degree of freedom in the direction of the via holes. [Example]

[0029] The via holes for both the electric probe and the optical probe may be formed by laser microfabrication. In this case, steps 2 to 5 in Example 1 and steps 2 to 5 and 10 to 13 in Example 2 can be replaced with laser processing. For example, as shown in FIG. 3, this is useful when forming a via hole for the optical probe at an angle from the vertical direction to the substrate.

Claims

1. A probe card for measuring electrical and optical characteristics of an optoelectronic device, a probe pin that is inserted into a first via hole formed in the substrate and is attached in a vertical direction from the substrate to measure the electrical characteristic; an optical fiber inserted into a second via hole formed in the substrate for measuring the optical characteristics, the optical fiber having an attachment angle different from that of the probe pin; and A probe card comprising:

2. 2. The probe card according to claim 1, wherein the optical axis of the optical fiber is tilted from a direction perpendicular to the surface of the substrate.

3. 2. The probe card according to claim 1, wherein the optical axis of the optical fiber is in the direction in which light is emitted from an optical element formed on the substrate.

4. The substrate is made of silicon (Si) or silica (SiO 2 4. The probe card according to claim 1, wherein the probe card comprises:

5. 1. A method for manufacturing a probe card for measuring electrical and optical characteristics of optoelectronic devices formed on a wafer, comprising: forming a first via hole in the substrate; forming a metal plating film on the substrate for fixing probe pins for measuring the electrical characteristics; forming a second via hole in the substrate; a step of inserting an optical fiber for measuring the optical characteristics into the second via hole and fixing it so that it slightly protrudes from the surface facing the wafer; polishing a surface of the substrate facing the wafer; inserting the probe pin into the first via hole and fixing it to the region where the metal plating is formed; A method for manufacturing a probe card, comprising:

6. The substrate is made of silicon (Si) or silica (SiO 2 ) 6. The method for manufacturing a probe card according to claim 5, wherein the step of forming the first via hole and the second via hole in the substrate is performed by photolithography and etching.

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