A polishing method for a thermal-optic modulation PLC optical chip

Abstract

The application provides a polishing method for a thermal-optical modulation PLC optical chip, and belongs to the technical field of optical communication, and aims to solve the technical problem that adhesive remains on the surface of a metal electrode after polishing of the end face of the chip.The application comprises the following steps: (1) pasting a strip-shaped cover plate on a cutting channel of a wafer; (2) cutting the wafer along the cutting channel into bars, each strip-shaped cover plate is divided into two narrow cover plates, and two narrow cover plates are pasted on the two ends of the upper surface of each bar; (3) clamping the upper and lower surfaces of the bar by using a clamp, the clamp is in contact with the narrow cover plate on the upper surface, and then the two end faces in the width direction of the bar are polished.The application can avoid direct contact between the clamping plate of the clamp and the metal electrode, and avoid damaging the metal electrode.No adhesive needs to be coated on the metal electrode during polishing, and the cover plate on the metal electrode does not need to be removed after polishing, thereby avoiding the problem that adhesive remains on the metal electrode.

Description

Technical Field

[0001] This invention belongs to the technical field of optical communication, and particularly relates to a polishing method for a thermo-optical modulation PLC optical chip. Background Technology

[0002] With the rapid development of optical fiber communication, optical devices have emerged as a key component in the communication industry, showing great promise for applications in the field. To achieve end-face coupling, silicon-based silicon dioxide optical waveguide chips require polishing of their end faces. In traditional semiconductor processes, a suitable fixture is used to hold the chip, and the end face is polished at an appropriate angle. When the entire fixture disk is placed on a rotating polishing disc, the chip end face contacts the disc. By adding polishing fluid to the disc and rotating it, the chip end face can be polished smooth.

[0003] Active devices have a layer of metal electrodes grown on their top surface. Directly bonding the chip can easily damage these metal electrodes, causing chip defects or even rendering the chip unusable. A release liner is attached to the chip's top surface to protect the top surface and end-face waveguides from damage during polishing. The liner is removed after polishing. Alternatively, to improve polishing consistency and efficiency, some dicing-polishing processes first cut the wafer into bars along the dicing kerf, then attach a release liner to the metal electrodes on the top surface of the bars. For example, patent publication number CN108372457A discloses a grinding and cutting method for a low-channel arrayed waveguide grating wavelength division multiplexer chip. The two end faces of the strip-shaped chip in the width direction are ground and polished on a grinding machine until they form different preset angles with the upper surface of the first glass cover plate. This allows the input and output end faces of a single chip to form different preset angles with the upper surface of the first glass cover plate. The strip-shaped chip is relatively large, facilitating grinding and polishing. Furthermore, angle detection of the two end faces in the width direction of the strip-shaped chip allows for simultaneous angle detection of the input and output end faces of multiple single chips, improving detection efficiency. However, using a method of attaching the cover plate to the bar strip cannot guarantee the parallelism between the cover plate and the bar strip, resulting in inconsistencies between the ground and polished end faces and the output end faces of the optical waveguide device. Meanwhile, in the above processes, the cover plate needs to be removed after the end face polishing is completed. Since the adhesive used to attach the cover plate is usually hot melt adhesive, the chip needs to be heated first to melt the hot melt adhesive before the cover plate can be peeled off. Then, organic solvents such as acetone are used to clean the remaining hot melt adhesive. This results in adhesive residue easily remaining on the metal electrode surface, and the metal surface is easily damaged during the removal and cleaning process, leading to poor stability and reduced reliability in subsequent metal bonding processes. Furthermore, the polishing process is complex and cumbersome, and the material costs are high, failing to effectively save costs. Summary of the Invention

[0004] To address the technical problem of needing to remove the cover plate on the metal electrode surface after polishing the chip end face, this invention proposes a polishing method for thermo-optical modulation PLC optical chips. After polishing, it is not necessary to remove the cover plate on the metal electrode, thus avoiding the problem of residual adhesive on the metal electrode.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A polishing method for optical chips in thermo-optical modulation PLCs includes the following steps:

[0007] Step 1: Cut the entire cover plate into ultra-short strips, with the length of the strip cover plate being the same as the length of the dicing track at the corresponding position on the wafer.

[0008] Step 2: Using UV-curable adhesive, align the strip cover plate with the wafer dicing line, press and stick it to ensure that the strip cover plate is tightly bonded to the wafer without any air bubbles.

[0009] Step 3: Use a UV lamp to irradiate the adhesive area to cure it once.

[0010] Step 4: Place the cured wafer and cover plate into a high-temperature baking oven for a second curing.

[0011] Step 5: Place the wafer into the dicing machine and cut the wafer into bar strips along the dicing path. Each bar strip is divided into two narrow cover plates, and two narrow cover plates are attached to both ends of the upper surface of each bar strip.

[0012] Step 6: Use a clamp to hold the upper and lower surfaces of the bar strip. The clamp contacts the narrow cover plate on the upper surface to avoid direct contact between the clamp plate and the metal electrode. Then, grind and polish the two end faces of the bar strip in the width direction to a preset angle.

[0013] The strip-shaped cover plate is made of silicon dioxide, such as silicon dioxide glass.

[0014] In step 1, the width of the strip cover plate is greater than the width of the cutting channel, less than the distance between adjacent metal electrodes on both sides of the cutting channel, and the end face must be ground out at a preset angle.

[0015] Preferably, the width of the strip cover plate is at most 2.3-5mm.

[0016] The thickness of the strip cover plate in step 1 is between 0.2 mm and 1 mm.

[0017] The wafer in step 1 has metal electrodes on its upper surface.

[0018] In step 2, the width of the wafer dicing channel is the same as the width of the dicing blade.

[0019] Preferably, the wafer dicing width is 0.3 mm.

[0020] In step 2, the cover plate is bonded to the wafer, ensuring that there are no air bubbles in the adhesive. Excess adhesive on both sides of the cover plate is wiped away with lint-free paper.

[0021] Preferably, in step 2, the strip cover plate coincides with the central axis of the cutting channel.

[0022] In step 4, the secondary curing temperature in the high-temperature baking oven is approximately 70-90°C.

[0023] The width of the narrow cover plate in step 5 is 1-2 mm.

[0024] During the bar polishing process in step 6, the surface of the thermo-optical modulated metal electrode needs to be covered with a wax layer to ensure that the metal layer is not damaged during the polishing process.

[0025] The beneficial effects of this invention are:

[0026] (1) This invention employs a strip-shaped cover plate. At the wafer level, the strip-shaped cover plate is adhered to the middle position of two sets of wafer bar dicing channels. While the wafer is being diced into bars, the upper strip-shaped cover plate is also split in two from the middle position of the dicing channel. This is more efficient and saves material costs compared to directly adhering the cover plate to the bars or chip. Furthermore, the end face of the narrow cover plate after dicing is consistent with the output end face of the bar.

[0027] (2) When the thermo-optical modulation device is subsequently subjected to end face grinding and polishing using a clamp, the clamp contacts the narrow cover plate on the upper surface, which can prevent the clamp plate of the clamp from directly contacting the metal electrode and avoid damaging the metal electrode.

[0028] (3) During the end face coupling process, the narrow cover plate, as part of the output end face, also participates in the coupling. The increased coupling area of ​​the narrow cover plate improves the coupling strength of the end face.

[0029] (4) This invention eliminates the need to apply adhesive to the metal electrode during polishing and to remove the cover plate after polishing, thus avoiding the problem of residual adhesive on the metal electrode. Furthermore, this method is highly reliable, simple to implement, ensures the integrity of the metal electrode and the consistency of the light wave emission end face, improves overall process efficiency, and reduces labor and material costs. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of a wafer with a strip cover plate attached.

[0032] Figure 2 This is a schematic diagram of wafer cutting.

[0033] Figure 3 This is a schematic diagram of the bar strips of the PLC device after cutting.

[0034] Figure 4 This is a side view of the PLC device after the bar has been polished.

[0035] In the figure, 1 is the wafer; 11 is the dicing channel; 12 is the bar; 13 is the metal electrode; 2 is the strip cover plate; and 21 is the narrow cover plate. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] A polishing method for optical chips in thermo-optical modulation PLCs includes the following steps:

[0039] Step 1: Cut the entire glass cover plate into ultra-short strips to form strip cover plates 2. The length of strip cover plates 2 is the same as the length of the cutting channel 11 at the opposite position of wafer 1. The width of strip cover plates 2 is 2.3mm and the thickness is 0.5mm.

[0040] Step 2: Apply UV-curable adhesive and align the strip cover plate 2 with the dicing groove 11 of wafer 1, ensuring the central axis of the strip cover plate 2 coincides with that of the dicing groove 11. Press and adhere to ensure a tight bond between the strip cover plate 2 and wafer 1, without air bubbles. Wipe away any excess adhesive from both sides of the cover plate with lint-free paper. Since the upper surface of wafer 1 has metal electrodes 13, avoid attaching the strip cover plate 2 to the metal electrodes 13. The structure is as follows... Figure 1 As shown.

[0041] Step 3: Use a UV lamp to irradiate the adhesive area to cure it once.

[0042] Step 4: Place the first-cured wafer 1 and cover plate into a high-temperature baking oven and perform a second curing at 85°C.

[0043] Step 5: Place wafer 1 into the dicing machine. The width of the dicing blade in the dicing machine is 0.3mm. Divide wafer 1 into bar strips 12 along the dicing path 11 (e.g., Figure 2 As shown), each strip cover plate 2 is divided into two narrow cover plates 21, and two narrow cover plates 21 are attached to both ends of the upper surface of each bar strip 12 (as shown). Figure 3 As shown), the width of the narrow cover plate 21 is 1 mm.

[0044] Step 6: Cover the surface of the metal electrode 13 with a wax layer to ensure that the metal layer is not damaged during the polishing process. Use a clamp to hold the upper and lower surfaces of the bar strip 12. The clamp contacts the narrow cover plate 21 on the upper surface to avoid direct contact between the clamp plate and the metal electrode 13. Then polish the two end faces of the bar strip 12 in the width direction to 8°. Figure 4 As shown.

[0045] Example 2

[0046] A polishing method for optical chips in thermo-optical modulation PLCs includes the following steps:

[0047] Step 1: Cut the entire glass cover plate into ultra-short strips to form strip cover plates 2. The length of strip cover plates 2 is the same as the length of the cutting channel 11 at the opposite position of wafer 1. The width of strip cover plates 2 is 4.3mm and the thickness is 1mm.

[0048] Step 2: Apply UV-curable adhesive and align the strip cover plate 2 with the dicing groove 11 of wafer 1, ensuring the central axis of the strip cover plate 2 coincides with that of the dicing groove 11. Press and adhere to ensure a tight bond between the strip cover plate 2 and wafer 1, without air bubbles. Wipe away any excess adhesive from both sides of the cover plate with lint-free paper. Since the upper surface of wafer 1 has metal electrodes 13, avoid attaching the strip cover plate 2 to the metal electrodes 13. The structure is as follows... Figure 1 As shown.

[0049] Step 3: Use a UV lamp to irradiate the adhesive area to cure it once.

[0050] Step 4: Place the first-cured wafer 1 and cover plate into a high-temperature baking oven and perform a second curing at 70°C.

[0051] Step 5: Place wafer 1 into the dicing machine. The width of the dicing blade in the dicing machine is 0.3mm. Divide wafer 1 into bar strips 12 along the dicing path 11 (e.g., Figure 2 As shown), each strip cover plate 2 is divided into two narrow cover plates 21, and two narrow cover plates 21 are attached to both ends of the upper surface of each bar strip 12 (as shown). Figure 3 As shown), the width of the narrow cover plate 21 is 2mm.

[0052] Step 6: Cover the surface of the metal electrode 13 with a wax layer to ensure that the metal layer is not damaged during the polishing process. Use a clamp to hold the upper and lower surfaces of the bar strip 12. The clamp contacts the narrow cover plate 21 on the upper surface to avoid direct contact between the clamp plate and the metal electrode 13. Then polish the two end faces of the bar strip 12 in the width direction to 8°. Figure 4 As shown.

[0053] Example 3

[0054] A polishing method for optical chips in thermo-optical modulation PLCs includes the following steps:

[0055] Step 1: Cut the entire glass cover plate into ultra-short strips to form strip cover plates 2. The length of strip cover plates 2 is the same as the length of the cutting channel 11 at the opposite position of the wafer 1. The width of strip cover plates 2 is 5mm and the thickness is 0.2mm.

[0056] Step 2: Apply UV-curable adhesive and align the strip cover plate 2 with the dicing groove 11 of wafer 1, ensuring the central axis of the strip cover plate 2 coincides with that of the dicing groove 11. Press and adhere to ensure a tight bond between the strip cover plate 2 and wafer 1, without air bubbles. Wipe away any excess adhesive from both sides of the cover plate with lint-free paper. Since the upper surface of wafer 1 has metal electrodes 13, avoid attaching the strip cover plate 2 to the metal electrodes 13. The structure is as follows... Figure 1 As shown.

[0057] Step 3: Use a UV lamp to irradiate the adhesive area to cure it once.

[0058] Step 4: Place the first-cured wafer 1 and cover plate into a high-temperature baking oven and perform a second curing at 90°C.

[0059] Step 5: Place wafer 1 into the dicing machine. The width of the dicing blade in the dicing machine is 0.7mm. Divide wafer 1 into bar strips 12 along the dicing path 11 (e.g., Figure 2 As shown), each strip cover plate 2 is divided into two narrow cover plates 21, and two narrow cover plates 21 are attached to both ends of the upper surface of each bar strip 12 (as shown). Figure 3 As shown, the width of the narrow cover plate 21 is 1.8 mm.

[0060] Step 6: Cover the surface of the metal electrode 13 with a wax layer to ensure that the metal layer is not damaged during the polishing process. Use a clamp to hold the upper and lower surfaces of the bar strip 12. The clamp contacts the narrow cover plate 21 on the upper surface to avoid direct contact between the clamp plate and the metal electrode 13. Then polish the two end faces of the bar strip 12 in the width direction to 8°. Figure 4 As shown.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polishing method for a thermo-optical modulation PLC optical chip, characterized in that, Includes the following steps: (1) Attach the strip cover plate (2) to the dicing groove (11) of the wafer (1), the length of the strip cover plate (2) being the same as the length of the dicing groove (11) at the opposite position of the wafer (1); (2) Cut the wafer (1) with strip cover plate (2) attached in step (1) into bar strips (12) along the dicing channel (11). Each bar strip (12) has two narrow cover plates (21) at both ends of its upper surface. (3) The bar strip (12) is held by a clamp, and the clamp contacts the narrow cover plate (21) on the upper surface. Then the two end faces of the bar strip (12) are polished.

2. The polishing method for thermo-optical modulation PLC optical chips according to claim 1, characterized in that, In step (1), the strip cover plate (2) is attached to the dicing channel (11) of the wafer (1) with UV-curing adhesive and cured by UV irradiation.

3. The polishing method for thermo-optical modulation PLC optical chips according to claim 2, characterized in that, The wafer (1) and strip cover plate (2) cured by ultraviolet light are baked at 70-90℃ for secondary curing.

4. The polishing method for a thermo-optical modulation PLC optical chip according to claim 1, characterized in that, The material of the strip cover plate (2) is silicon dioxide.

5. The polishing method for a thermo-optical modulation PLC optical chip according to claim 1, characterized in that, The width of the cutting channel (11) is the same as the width of the cutting blade used in step (1).

6. The polishing method for a thermo-optical modulation PLC optical chip according to claim 1, characterized in that, The width of the strip cover plate (2) is greater than the width of the cutting channel (11) and less than the distance between adjacent metal electrodes (13) on both sides of the cutting channel (11).

7. The polishing method for a thermo-optical modulation PLC optical chip according to claim 1, characterized in that, In step (1), the strip cover plate (2) is pasted on the dicing channel (11) of the wafer (1), and the strip cover plate (2) coincides with the central axis of the dicing channel (11).

8. The polishing method for a thermo-optical modulation PLC optical chip according to claim 1, characterized in that, The thickness of the strip cover plate (2) is 0.2-1mm.

9. The polishing method for a thermo-optical modulation PLC optical chip according to claim 1, characterized in that, The width of the narrow cover plate (21) is 1-2 mm.

10. The polishing method for a thermo-optical modulation PLC optical chip according to claim 1, characterized in that, In step (3), when the bar strip (12) is polished, the surfaces of the upper and lower metal electrodes (13) of the bar strip (12) are coated with a wax layer.

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