DFB laser chip capable of realizing on-chip detection and wafer structure
In-wafer testing of DFB laser chips using inclined waveguide ends simplifies the detection process, reducing waste and costs by allowing direct observation of chip performance before dicing.
Patent Information
- Application Number
- CN202421931772.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-09
- Publication Date
- 2025-07-15
- Estimated Expiration
- 2034-08-09
AI Technical Summary
Existing DFB semiconductor lasers require separate testing after dicing, which is cumbersome and time-consuming, leading to inefficiencies in full inspection and potential waste of resources.
Designing the ends of the waveguide layer as inclined surfaces to redirect light reflection or refraction to the top or bottom surface of the waveguide layer, allowing direct in-wafer testing of DFB laser chips without dicing.
Facilitates efficient in-wafer testing, reducing material and time wastage, and lowering detection costs by enabling immediate identification of defective chips before further processing.
Smart Images
Figure CN223109455U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of semiconductor lasers, and specifically provides a DFB laser chip and a wafer structure capable of realizing in-situ detection. Background Art
[0002] A DFB semiconductor laser is an edge-emitting semiconductor laser. When testing its performance, it is usually necessary to cleave and scribe the chip and then add electrodes to test. After cleavage and scribing, the chip becomes a bar, and each bar needs to be separately placed and coupled for testing. The process is relatively troublesome and time-consuming, and it is difficult to achieve full inspection and testing.
[0003] In the prior art, the detection of DFB chips cannot achieve full inspection and testing. Moreover, during the later testing process, it is often necessary to cleave into single tubes and then patch and wire them before testing. When there are defective samples, this kind of testing is a waste of processes, materials, and man-hours. Summary of the Utility Model
[0004] In order to solve the above problems, the utility model provides a DFB laser chip and a wafer structure capable of realizing in-situ detection. By designing the two ends of the waveguide layer as inclined surfaces, the light is reflected or refracted by the inclined surfaces to be transmitted to the upper surface or the lower surface of the waveguide layer, so that the DFB laser chip on the wafer can be directly detected from the top or the bottom, simplifying the chip detection process and reducing the chip detection cost.
[0005] In a first aspect, the DFB laser chip capable of realizing in-situ detection provided by the utility model includes: a waveguide layer disposed on a substrate, wherein the two ends of the waveguide layer are inclined surfaces, and the inclined surfaces change the transmission direction of photons in the waveguide layer.
[0006] Preferably, the inclined surfaces reflect or refract the photons in the waveguide layer to the upper surface or the lower surface of the waveguide layer.
[0007] Preferably, the included angle between the inclined surface and the substrate is greater than 90 degrees.
[0008] Preferably, the included angle between the inclined surface and the substrate is less than 90 degrees.
[0009] Preferably, the waveguide layer includes a straight waveguide, a first bent waveguide, and a second bent waveguide. The first bent waveguide and the second bent waveguide are respectively located at both ends of the straight waveguide, and the first bent waveguide and the second bent waveguide are bent laterally with respect to the straight waveguide.
[0010] In a second aspect, a wafer structure includes a plurality of DFB laser chips capable of realizing in-situ detection arranged at equal intervals.
[0011] In a third aspect, a wafer structure includes multiple rows of DFB laser chips capable of on-chip detection and having bent waveguides, and the bending directions of the first bent waveguide and the second bent waveguide of the DFB laser chips in adjacent rows are opposite.
[0012] Preferably, the distance between two straight waveguides of adjacent DFB laser chips in the same row is equal to the length of the straight waveguides; the left end of the straight waveguide of any one DFB laser chip is longitudinally aligned with the right end of the straight waveguide of the DFB laser chip with the smallest distance in the adjacent row.
[0013] Compared with the prior art, the present utility model can achieve the following beneficial effects:
[0014] The present utility model changes the photon transmission direction in the waveguide through the inclined surface, so that the photons in the waveguide are emitted from above or below the wafer. When performing on-chip detection, the light emission situation can be directly observed from above or below the wafer, and defective products can be promptly picked out before chip cleavage, simplifying the detection process of DFB laser chips, reducing the waste of subsequent processes, materials, and man-hours, and reducing the economic cost.
[0015] In addition, the present utility model designs the waveguide layer as a combination of straight waveguides and bent waveguides. By increasing the distance between adjacent inclined surfaces through the bent waveguides, the chip arrangement density on the wafer can be increased, enabling more DFB laser chips to be distributed on the wafer. Description of the Drawings
[0016] Figure 1 is a schematic diagram of a DFB laser chip provided in Embodiment 1 of the present utility model;
[0017] Figure 2 is a schematic diagram of a DFB laser chip provided in Embodiment 2 of the present utility model;
[0018] Figure 3 is a schematic diagram of a DFB laser chip provided in Embodiment 3 of the present utility model;
[0019] Figure 4 is a schematic diagram of a wafer structure provided in Embodiment 4 of the present utility model;
[0020] Figure 5 is a schematic diagram of a wafer structure provided in Embodiment 5 of the present utility model;
[0021] Figure 6 is a partially enlarged three-dimensional structure diagram of the D area of the wafer provided in Embodiment 5 of the present utility model;
[0022] Figure 7 is a sectional three-dimensional structure diagram of the D area of the wafer along the dotted line C provided in Embodiment 5 of the present utility model;
[0023] Figure 8It is a schematic diagram of a wafer structure for in - wafer detection provided by Embodiment 5 of the present utility model. Detailed implementation manners
[0024] In the following, embodiments of the present utility model will be described with reference to the accompanying drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, their detailed descriptions will not be repeated.
[0025] In order to make the objectives, technical solutions and advantages of the present utility model more clearly understood, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model, but not to limit the present utility model.
[0026] Embodiment 1:
[0027] As Figure 1 shown, the DFB laser chip 10 capable of realizing in - wafer detection provided by Embodiment 1 of the present utility model includes, from the lower layer to the upper layer in sequence: a substrate 1, a buffer layer 2, a waveguide layer 3, and a contact layer 4. Among them, the waveguide layer 3 includes, from the lower layer to the upper layer in sequence: a lower confinement layer 31, a lower waveguide layer 32, an active layer 33, an upper waveguide layer 34, and an upper confinement layer 35. A grating 36 is further provided in the upper waveguide layer 34. Photons during the operation of the DFB laser chip 10 are transmitted within the waveguide layer 3.
[0028] Both the first end face 3A and the second end face 3B on both sides of the waveguide layer 3 are inclined faces. The included angles formed by the first end face 3A, the second end face 3B and the substrate 1 (or the buffer layer 2) are greater than 90 degrees. No electrode openings are formed on the first end face 3A and the second end face 3B to prevent possible leakage problems during electrical injection, and there is no metal blockage on the first end face 3A and the second end face 3B either. During the preparation process of the DFB laser chip 10, both the first end face 3A and the second end face 3B are prepared by additional photolithography and etching. Depending on the materials and processes, the first end face 3A and the second end face 3B have the effect of reflecting or refracting light. Therefore, during the transmission of photons within the waveguide layer 3, the first end face 3A and the second end face 3B can reflect or refract the photons towards the lower surface or the upper surface of the waveguide layer 3.
[0029] The DFB laser chip 10 is obtained by fabricating on a wafer. The substrate 1 and the buffer layer 2 both belong to the wafer structure. When detecting the above DFB laser chip 10, it is not necessary to cleave the DFB laser chip 10 from the wafer for detection. During the etching process of the first end face 3A and the second end face 3B, etching openings will be left on the wafer 5, and these etching openings can be used as light-emitting ports. After the tester energizes the DFB laser chip 10, the light-emitting situation of the DFB laser chip 10 can be observed from the light-emitting port at the bottom of the wafer to detect the quality of the DFB laser chip 10. If no light is emitted from the light-emitting port or the light-emitting situation does not meet the standard, it indicates that the DFB laser chip 10 is a defective product; if the light-emitting situation at the light-emitting port meets the standard, it indicates that the DFB laser chip 10 is a qualified product. By cleaving perpendicularly along the cleavage plane A and the cleavage plane B, the DFB laser chip 10 that meets the production requirements can be obtained, and the defective DFB laser chips 10 do not need to undergo subsequent processes such as cleavage. The DFB laser chip 10 in the embodiment of the present invention can achieve in-situ detection, avoiding the meaningless processing of defective products and reducing the losses of materials, working hours, and costs.
[0030] Embodiment 2:
[0031] As Figure 2 shown, the DFB laser chip 20 capable of realizing in-situ detection provided in Embodiment 2 of the present invention has basically the same structure as the DFB laser chip 10 in Embodiment 1, and the only difference is that:
[0032] The waveguide layer 3 includes a first bent waveguide 301, a straight waveguide 302, and a second bent waveguide 303. The first bent waveguide 301 and the second bent waveguide 303 are respectively arranged at both ends of the straight waveguide 302. The first bent waveguide 301 and the second bent waveguide 303 facing the first end face 3A and the second end face 3B at both ends are inclined planes. The included angles formed by the first end face 3A, the second end face 3B and the buffer layer 2 are less than 90 degrees. The first end face 3A and the second end face 3B reflect the photons in the waveguide layer 3 to the upper surface of the waveguide layer 3.
[0033] As Figure 6 and Figure 7 shown, the first bent waveguide 301 and the second bent waveguide 303 are bent laterally relative to the straight waveguide 302, that is, the first bent waveguide 301 and the second bent waveguide 303 have a bending angle in the horizontal direction and no bending angle in the vertical direction. The design of the first bent waveguide 301 and the second bent waveguide 303 can increase the distance between adjacent inclined planes of adjacent DFB laser chips 20 on the wafer, making the arrangement density of DFB laser chips 20 on the wafer larger, so that more DFB laser chips 20 can be distributed on the wafer and the material utilization rate is improved.
[0034] When detecting the above DFB laser chip 20, since the light emission direction of photons is towards the upper surface of the waveguide layer 3, after the DFB laser chip 20 is powered on, the DFB laser chip 20 can be directly detected from its upper surface by the detector.
[0035] After the in-chip detection is completed, cleavage is performed along the cleavage plane A and the cleavage plane B respectively, and the first bent waveguide 301 and the second bent waveguide 303 can be removed.
[0036] Embodiment 3:
[0037] As Figure 3 shown, the DFB laser chip 30 capable of realizing in-chip detection provided in Embodiment 3 of the present invention has basically the same structure as the DFB laser chip 20 in Embodiment 2, and the difference is only that: the inclination angles of the two end faces of the waveguide layer 3 in Embodiment 3 are different from those in Embodiment 2. In Embodiment 3, the angles formed by the first end face 3A, the second end face 3B and the substrate 1 are greater than 90 degrees.
[0038] Embodiment 4:
[0039] As Figure 4 shown, the wafer structure provided in Embodiment 4 of the present invention includes: N DFB laser chips 10 as disclosed in Embodiment 1 are arranged at equal intervals on the wafer 5. Since the angles formed by the first end face 3A, the second end face 3B and the substrate 1 are greater than 90 degrees, the first end face 3A and the second end face 3B can reflect photons to the lower surface of the waveguide layer 3. When etching the first end face 3A and the second end face 3B, light-emitting ports 501 will be formed on the wafer 5. Therefore, the light emitted from the waveguide layer 3 will be emitted from the light-emitting ports 501. During detection, after the detector powers on the DFB laser chip 10, the light emission condition of the DFB laser chip 10 can be observed from the light-emitting ports 501 at the bottom of the wafer, and the in-chip detection process is completed.
[0040] The distance between the DFB laser chips 10 needs to ensure that the light emitted from two adjacent DFB laser chips 10 will not be coupled, that is, the distance between the adjacent light-emitting ports 501 of two adjacent DFB laser chips 10 is greater than the coupling distance.
[0041] Embodiment 5:
[0042] As Figure 5 shown, the difference between the wafer structure provided in Embodiment 5 of the present invention and the wafer structure provided in Embodiment 4 is that: multiple rows of DFB laser chips 20 as disclosed in Embodiment 2 are provided on the wafer 5, and as Figure 6 and Figure 7As shown, the bending directions of the first bent waveguide 301 and the second bent waveguide 303 of the DFB laser chips 20 in two adjacent rows are opposite. For example, in the first row 100, both the first bent waveguide 301 and the second bent waveguide 303 of the DFB laser chip 20 bend away from the first bent waveguide 301 and the second bent waveguide 303 of the DFB laser chip 20 in the second row 200. Such a design can avoid coupling between the DFB laser chips 20 in adjacent rows.
[0043] In addition, the corresponding DFB laser chips 20 in adjacent rows are not in the same column. For example, the DFB laser chips 20 in the first row 100 and the DFB laser chips 20 in the second row 200 are not aligned longitudinally. Such a design can further increase the distance between the corresponding two DFB laser chips 20 in adjacent rows, further reduce the coupling probability, and also helps to arrange more DFB laser chips 20 on the wafer 5.
[0044] In this embodiment, the angles formed by the first end face 3A and the second end face 3B of the DFB laser chips 20 in the first row 100 and the second row 200 with the substrate 1 are both less than 90 degrees. Therefore, during detection, observation is performed from the top of the wafer 5.
[0045] As a preferred embodiment, the distance between the two straight waveguides 302 of adjacent DFB laser chips 20 in the first row 100 is equal to the length of the straight waveguide 302. The left end of the straight waveguide 302 of any DFB laser chip 20 in the first row 100 is longitudinally aligned with the right end of the straight waveguide 302 of the DFB laser chip 20 with the smallest distance in the second row 200, that is, the straight waveguide 302 of the DFB laser chip 20 in the second row 200 is exactly within the interval of the straight waveguide 302 in the first row 100.
[0046] Based on the wafer structure provided in Embodiment 5, the in - wafer detection process of the laser chips 20 on the wafer 5 is as follows:
[0047] Power is applied to the wafer 5 shown in Embodiment 5, and it is observed from the top of the wafer 5 whether there is light at the first end face 3A and the second end face 3B of each DFB laser chip 20. If there is light emitted from both the first end face 3A and the second end face 3B of the DFB laser chip 20, it indicates that the DFB laser chip 20 is a qualified product; if there is no light emitted from both the first end face 3A and the second end face 3B of the DFB laser chip 20 or there is no light emitted from one end, it indicates that the DFB laser chip 20 is an unqualified product.
[0048] Based on the wafer structure provided in Embodiment 5, the cleavage process of the laser chips 20 on the wafer 5 is as follows:
[0049] Such as Figure 8As shown in the figure, the contact surfaces of the straight waveguide 302 of the DFB laser chip 20 with the first bent waveguide 301 and the second bent waveguide 302 are defined as vertical cleavage planes. The cleavage planes A and B of each DFB laser chip 20 are re-numbered as cleavage plane a, cleavage plane b, cleavage plane c, etc. Cleavage is performed along both ends of the straight waveguide 302 to obtain a bar. The plane parallel to the straight waveguide 302 of the DFB laser chip 20 is defined as a parallel cleavage plane, numbered as cleavage plane d, cleavage plane e, cleavage plane f, cleavage plane h, etc. Cleavage is performed on both the vertical cleavage plane and the parallel cleavage plane simultaneously to obtain a DFB single tube.
[0050] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.
[0051] The above specific embodiments of the present invention do not constitute a limitation to the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention should be included in the protection scope of the claims of the present invention.
Claims
1. A DFB laser chip capable of on-chip detection, characterized in that, It includes a waveguide layer disposed on a substrate. Both ends of the waveguide layer are inclined surfaces, and the inclined surfaces change the transmission direction of photons in the waveguide layer, and the inclined surfaces reflect or refract the photons in the waveguide layer towards the upper surface or the lower surface of the waveguide layer.
2. The DFB laser chip capable of realizing in-chip detection according to claim 1, wherein The included angle between the inclined surface and the substrate is greater than 90 degrees.
3. The DFB laser chip capable of on-chip detection according to claim 1, characterized in that The included angle between the inclined surface and the substrate is less than 90 degrees.
4. The DFB laser chip capable of realizing in-chip detection according to claim 1, characterized in that The waveguide layer includes a straight waveguide, a first bent waveguide, and a second bent waveguide. The first bent waveguide and the second bent waveguide are respectively located at both ends of the straight waveguide, and the first bent waveguide and the second bent waveguide are bent towards the side relative to the straight waveguide.
5. A wafer structure, characterized in that, It includes a plurality of DFB laser chips capable of on-chip detection as described in any one of claims 1 to 3 arranged at equal intervals.
6. A wafer structure, characterized in that, It includes multiple rows of DFB laser chips capable of on-chip detection as described in claim 4, and the bending directions of the first bent waveguide and the second bent waveguide of the DFB laser chips in adjacent rows are opposite.
7. The wafer structure according to claim 6, wherein, The distance between two straight waveguides of adjacent DFB laser chips in the same row is equal to the length of the straight waveguide; the left end of the straight waveguide of any DFB laser chip is longitudinally aligned with the right end of the straight waveguide of the DFB laser chip with the smallest distance in the adjacent row.