Electrode preparation method for preventing gold wire from turning up and laser preparation method

Abstract

The present invention discloses a method for preparing an electrode with a gold wire anti-flipping function, comprising the following steps: S1, using photoresist to complete electrode photolithography, S2, after the electrode photolithography is completed, etching the material layer of the metal to be deposited, and controlling the etching depth to be greater than the thickness of the metal to be deposited during etching, S3, after the etching is completed, the photoresist is separated from the material layer and a bottom incision structure is generated, S4, metal deposition is performed, part of the metal is deposited on the photoresist, and part of the metal is deposited on the etching area of ​​the material layer, S5, the photoresist is stripped to remove the metal on the photoresist, leaving the metal on the material layer, and the electrode preparation is completed. A laser preparation method is also provided, which adopts the above-mentioned method for preparing an electrode with a gold wire anti-flipping function to prepare an electrode. The present invention etches the material layer to separate the photoresist from the material layer and generate an undercut, and the metal is deposited on the material layer, thereby separating from the photoresist, thereby avoiding the phenomenon of electrode stripping and gold wire flipping.

Description

Technical Field

[0001] The invention relates to the technical field of lasers, and in particular to a method for preparing a gold wire anti-flipping electrode and a method for preparing a laser. Background Art

[0002] With the development of optical communication, low loss, large capacity and long distance have become the development direction of optical fiber transmission system, and semiconductor laser chip is the core of optical communication system. x The laser is fabricated by combining mask, photolithography and etching techniques to produce ridge waveguide, and then the electrical injection window and electrode are fabricated in sequence. The traditional electrode uses a single layer of photoresist. Figure 1 During the metal deposition process, a large amount of metal film will be deposited on the side wall of the photoresist. Figure 2 After stripping, the metal is connected to the metal on the side wall of the photoresist, causing the gold wire to turn up. Figure 3 The gold wire will break and scatter in the subsequent process and scratch the laser, affecting the laser yield. Secondly, the gold wire will cause the tip to release, causing the laser to fail.

[0003] The patent application with publication number CN115542687A adopts a double-layer glue process to produce electrode patterns to solve the metal deposition phenomenon on the side wall of the photoresist. In this double-layer glue process, the upper layer of glue adopts photosensitive photoresist to produce electrode patterns, and the lower layer adopts non-photosensitive photoresist. By controlling the development rate, an undercut structure is formed to obtain a discontinuous metal layer during metal deposition, thereby achieving an effect of easy peeling.

[0004] However, the patent application uses electron beam evaporation electrodes, which are not suitable for straight or inverted ridge waveguide lasers and have a poor practical range. The sputtering process is widely used because of its good sputtering length, which can cover the straight or inverted sidewalls of the ridge waveguide. Due to its good sputtering length, when the electrode is made using a double-layer glue process, the metal will move to the inside of the undercut during the deposition process. If the undercut is too small, the metal will still be connected to the sidewall of the lower glue layer. Figure 4 , after the double-layer glue is peeled off, the gold wire will turn up; if the undercut is too large, the upper layer of glue will collapse and connect to the metal, Figure 5 , the stripping solution has difficulty in contacting the photoresist, resulting in stripping difficulties. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing an electrode with anti-flipping gold wire and a method for preparing a laser, which can at least solve some of the defects in the prior art.

[0006] To achieve the above-mentioned purpose, the embodiment of the present invention provides the following technical solution: a method for preparing an electrode with anti-flipping of gold wire, comprising the following steps:

[0007] S1, electrode lithography is completed using photoresist,

[0008] S2, after the electrode lithography is completed, the material layer of the metal to be deposited is etched, and the etching depth is controlled to be greater than the thickness of the metal to be deposited.

[0009] S3, after etching is completed, the photoresist is separated from the material layer and a bottom inscribed structure is generated,

[0010] S4, performing metal deposition, wherein part of the metal is deposited on the photoresist, and part of the metal is deposited on the etched area of ​​the material layer,

[0011] S5, stripping the photoresist to remove the metal on the photoresist and leaving the metal on the material layer, thereby completing the electrode preparation.

[0012] Furthermore, the thickness of the material layer is greater than the thickness of the metal to be deposited.

[0013] Furthermore, in step S1, the electrode pattern is manufactured by using a single-layer glue process or a double-layer glue process.

[0014] Furthermore, when a single-layer glue process is adopted, the width range of the inscribed structure formed by the photoresist and the material layer is between 1 and 10um; when a double-layer glue process is adopted, the width range of the inscribed structure formed by the upper layer glue and the lower layer glue is between 1 and 10um, the width range of the inscribed structure formed by the lower layer glue and the material layer is between 1 and 10um, and the width range of the inscribed structure formed by the upper layer glue and the material layer is between 2 and 20um.

[0015] Furthermore, the material layer is a passivation material layer or a semiconductor material layer.

[0016] Furthermore, the passivation material layer is a Si layer, a SiO2 layer or a SiN x layer; the semiconductor material layer is an InP layer, an InGaAsP layer, an InGaAs layer, or a GaAs layer.

[0017] Furthermore, in step S2, etching is performed using a corrosive solution. When the material layer is a SiO2 layer, the corrosive solution is diluted hydrofluoric acid or BOE; when the material layer is a SiN x When the material layer is an InP layer, the etching liquid is a hydrochloric acid-based etching liquid; when the material layer is an InGaAsP layer, the etching liquid is a sulfuric acid-based etching liquid.

[0018] The embodiment of the present invention provides another technical solution: a method for preparing a laser, which adopts the above-mentioned method for preparing an electrode with anti-flipping gold wire to prepare an electrode.

[0019] Furthermore, when preparing the laser front electrode, the material layer is a passivation material layer, specifically:

[0020] First, a ridge waveguide structure or buried heterojunction structure is made on the surface of the wafer.

[0021] After the fabrication is completed, the passivation material layer is grown.

[0022] Then, a front electrode pattern is produced, and the electrodes are prepared on the passivation material layer using the steps S2 to S5.

[0023] Further, when preparing the laser back electrode, specifically:

[0024] After the laser completes the thinning of the back substrate, the back material surface is a semiconductor material layer;

[0025] Then, a back electrode pattern is produced, and the electrodes are prepared on the semiconductor material layer using the steps S2 to S5.

[0026] Compared with the prior art, the beneficial effects of the present invention are: by etching the material layer, the photoresist is separated from the material layer and an undercut is generated, and the metal is deposited on the material layer, thereby being separated from the photoresist, thereby avoiding the phenomenon of electrode peeling and gold wire flipping. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of making electrodes for traditional laser single-layer glue process;

[0028] Figure 2 Schematic diagram of the electrode after sputtering for the traditional laser single-layer glue process;

[0029] Figure 3 Schematic diagram of the gold wire flipping up after the photoresist is stripped off in the traditional laser single-layer glue process to make electrodes;

[0030] Figure 4 Schematic diagram of the electrode made by the traditional laser double-layer glue process, where the width of the bottom inscribed structure is small and the deposited metal is connected to the side wall of the lower glue layer;

[0031] Figure 5 Schematic diagram of the electrode made by the traditional laser double-layer glue process, where the width of the bottom inscribed structure is large and the deposited metal is connected to the side wall of the upper glue layer;

[0032] Figure 6 This is a schematic diagram of etching a SiO2 layer using diluted hydrofluoric acid or BOE in Example 1 of the present invention;

[0033] Figure 7 This is a schematic diagram of the first embodiment of the present invention after metal deposition;

[0034] Figure 8This is a schematic diagram of the first embodiment of the present invention after peeling;

[0035] Fig. 9 This is a schematic diagram of a bottom inscribed structure with a small width or a long metal scattering length, after metal is deposited on the side wall of the SiO2 layer and peeled off, according to an embodiment of the present invention;

[0036] Fig.10 This is a schematic diagram of the InP layer after growth according to the second embodiment of the present invention;

[0037] Fig.11 This is a schematic diagram of etching the InP layer using a hydrochloric acid-based etching solution in the second embodiment of the present invention;

[0038] Fig.12 This is a schematic diagram of the second embodiment of the present invention after metal deposition;

[0039] Fig.13 This is a schematic diagram of the second embodiment of the present invention after peeling;

[0040] In the accompanying drawings: 1-wafer; 2-SiO2 layer; 3-photoresist; 4-upper layer of glue; 5-lower layer of glue; 6-metal; 7-turned-up gold wire; 8-InP layer; 9-bottom incision structure. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The embodiment of the present invention provides a method for preparing an electrode with anti-flipping of gold wires, comprising the following steps: S1, using photoresist 3 to complete electrode photolithography, S2, after the electrode photolithography is completed, etching the material layer of metal 6 to be deposited, and controlling the etching depth to be greater than the thickness of the metal 6 to be deposited during etching, S3, after the etching is completed, the photoresist 3 is separated from the material layer and a bottom incision structure 9 is generated, S4, metal 6 is deposited, part of the metal 6 is deposited on the photoresist 3, and part of the metal 6 is deposited on the etching area of ​​the material layer, S5, stripping the photoresist 3 to remove the metal 6 on the photoresist 3, leaving the metal 6 on the material layer, and completing the electrode preparation. In this embodiment, by etching the material layer, the photoresist 3 is separated from the material layer and an undercut (bottom incision structure 9) is generated, and the metal 6 is deposited on the material layer, thereby separating from the photoresist 3, and avoiding the phenomenon of electrode stripping and gold wire flipping 7. Specifically, by controlling the etching conditions, that is, controlling the etching depth to be greater than the thickness of the metal 6 to be deposited, the photoresist 3 can be separated from the material layer and an undercut can be generated. In this way, when the metal 6 is deposited on the material layer, Figure 7 and Fig.12 As shown, the metal 6 on the photoresist 3 does not affect the metal 6 on the material layer. When the photoresist 3 is stripped, the metal 6 on the photoresist 3 will be completely removed, which can effectively avoid the generation of gold wire flipping 7. Fig. 9 As shown, even if the undercut is small or the metal 6 scattering length is long, the metal 6 may be deposited on the sidewall of the passivation material layer, but still separated from the photoresist 3. Preferably, the etching can be dry etching or wet etching. The material layer in the electrode deposition area can be partially etched or completely etched.

[0043] As an optimization scheme of the embodiment of the present invention, a selective etching solution is used for etching. When making the front electrode, diluted hydrofluoric acid and BOE are used for treatment. BOE (Buffered Oxide Etch), a buffered oxide etching solution, is a mixture of hydrofluoric acid (49%) aqueous solution and ammonium fluoride aqueous solution in proportion. When making the back electrode, a hydrochloric acid-based etching solution is used for etching. Specifically, when the material layer is a SiO2 layer, the etching solution is diluted hydrofluoric acid or BOE; when the material layer is a SiN x When the material layer is an InP layer, the etching liquid is a hydrochloric acid-based etching liquid; when the material layer is an InGaAsP layer, the etching liquid is a sulfuric acid-based etching liquid.

[0044] As an optimization solution of the embodiment of the present invention, the thickness of the material layer is greater than the thickness of the metal 6 to be deposited. In this embodiment, by limiting the thickness of the material layer to be greater than the thickness of the metal 6 to be deposited, it can be ensured that the depth of the etched material layer is greater than the thickness of the metal 6 deposition.

[0045] As an optimization scheme of the embodiment of the present invention, in step S1, the electrode pattern is made by using a single-layer glue process or a double-layer glue process. When a single-layer glue process is used, the width range of the inscribed structure formed by the photoresist 3 and the material layer is between 1 and 10um; when a double-layer glue is used, the width range of the inscribed structure formed by the upper layer glue 4 and the lower layer glue 5 is between 1 and 10um, the width range of the inscribed structure formed by the lower layer glue and the material layer is between 1 and 10um, and the width range of the inscribed structure formed by the upper layer glue and the material layer is between 2 and 20um. In this embodiment, the electrode lithography can adopt a single-layer glue process or a double-layer glue process. The width of the inscribed structure defined in this embodiment is A, such as Figure 6 and Fig.11 As shown, it is the length of the photoresist 3 protruding relative to the material layer.

[0046] As an optimization solution of the embodiment of the present invention, the material layer is a passivation material layer or a semiconductor material layer. Preferably, the passivation material layer is a Si layer, a SiO2 layer or a SiN x The semiconductor material layer is an InP layer, an InGaAsP layer, an InGaAs layer, or a GaAs layer. In this embodiment, a passivation material layer is used in the manufacture of the front electrode, and a semiconductor material layer is used in the manufacture of the back electrode.

[0047] See also Figures 6 to 13 An embodiment of the present invention provides a method for preparing a laser, which uses the above-mentioned method for preparing an electrode with anti-flipping gold wire to prepare an electrode.

[0048] Specifically, the following two embodiments are respectively a method for preparing a front electrode of a laser and a method for preparing a back electrode. Embodiment 1

[0049] When preparing the laser front electrode, the material layer is a passivation material layer, specifically:

[0050] Fabricate a ridge waveguide structure or a buried heterojunction structure on the surface of wafer 1 by combining a dry method with a wet method;

[0051] After the fabrication, a Sio2 layer 2 is grown, wherein the thickness of the Sio2 layer 2 is greater than the thickness of the metal 6 to be deposited;

[0052] Use single-layer glue process or double-layer glue process to make electrode patterns, see Figure 1 , ensuring that there is no photoresist 3 residue at the bottom of the metal 6 deposition area (i.e. the area of ​​the material layer to be etched);

[0053] The metal 6 deposition area is treated with diluted hydrofluoric acid or BOE to etch away part of the passivation material layer. The etching depth is greater than the metal 6 deposition thickness. At this time, the photoresist 3 and the passivation material layer form an undercut. Figure 6 ;

[0054] After metal 6 deposition, Figure 7 Since the corrosion depth is greater than the deposition thickness of the metal 6, the deposited metal 6 is separated from the photoresist 3, and the stripping liquid easily contacts the photoresist 3, making it easy for the metal 6 to be stripped;

[0055] After peeling, see Figure 8 The deposited metal 6 is on the passivation material layer, which does not affect the stripping of the metal 6 and can effectively avoid the generation of gold wire flipping 7. If the undercut is small or the metal 6 lap length is long, the metal 6 may be deposited on the side wall of the passivation material layer, but still separated from the photoresist 3. Fig. 9 , after stripping, the gold wire can still be prevented from turning up 7;

[0056] After the front electrode is completed, it is thinned, and then the back electrode is sputtered, and alloying and other processes are performed to complete the laser production.

[0057] In the first embodiment, the passivation material layer may be a Si layer, a SiO2 layer or a SiN x Layer, the above embodiment uses a SiO2 layer as an example. Embodiment 2

[0058] When preparing the laser back electrode, the material layer is a semiconductor material layer, specifically:

[0059] After the laser has completed the thinning of the back substrate, a single-layer or double-layer glue process is used to make the back electrode pattern to ensure that there is no photoresist 3 residue at the bottom of the metal 6 deposition area (i.e., the area of ​​the material layer to be etched);

[0060] The InP layer 8 in the electrode pattern area is corroded by using a hydrochloric acid-based etching solution. At this time, the photoresist 3 and the InP layer 8 form an undercut. Fig.11 ;

[0061] After the metal 6 is deposited, the deposited metal 6 is separated from the photoresist 3 because the corrosion depth is greater than the deposition thickness of the metal 6. Fig.12 , the stripping liquid easily contacts the photoresist 3 and is easy to strip the metal 6;

[0062] After peeling, see Fig.13 If the undercut is small or the metal 6 spurt length is large, the metal 6 may be deposited on the InP sidewall, but still separated from the photoresist 3, and the gold wire can still be prevented from turning up after stripping 7;

[0063] After the back metal 6 is peeled off, the front electrode is made, and alloying and other processes are performed to complete the laser production.

[0064] In the second embodiment, the semiconductor material layer may be an InP layer, an InGaAsP layer or an InGaAs layer. The above embodiment uses the InP layer as an example.

[0065] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an electrode with a gold wire that prevents it from turning up, characterized in that: The steps include: S1, electrode lithography is completed using photoresist, S2, after the electrode lithography is completed, the material layer of the metal to be deposited is etched, and the etching depth is controlled to be greater than the thickness of the metal to be deposited. S3, after etching is completed, the photoresist is separated from the material layer and a bottom inscribed structure is generated, S4, performing metal deposition, wherein part of the metal is deposited on the photoresist, and part of the metal is deposited on the etched area of ​​the material layer, S5, stripping the photoresist to remove the metal on the photoresist, leaving the metal on the material layer, and completing the electrode preparation. In step S1, the electrode pattern is made using a single-layer glue process or a double-layer glue process. When a single-layer glue process is used, the width range of the inscribed structure formed by the photoresist and the material layer is between 1 and 10um; when a double-layer glue process is used, the width range of the inscribed structure formed by the upper and lower layers of glue is between 1 and 10um, the width range of the inscribed structure formed by the lower layer of glue and the material layer is between 1 and 10um, and the width range of the inscribed structure formed by the upper layer of glue and the material layer is between 2 and 20um.

2. The method for preparing a gold wire anti-flipping electrode according to claim 1, characterized in that: The thickness of the material layer is greater than the thickness of the metal to be deposited.

3. The method for preparing an electrode with gold wire anti-flipping according to claim 1, characterized in that: The material layer is a passivation material layer or a semiconductor material layer.

4. The method for preparing an electrode with gold wire anti-flipping as claimed in claim 3, characterized in that: The passivation material layer is a Si layer, a SiO2 layer or a SiN x layer; the semiconductor material layer is an InP layer, an InGaAsP layer, an InGaAs layer or a GaAs layer.

5. The method for preparing a gold wire anti-flipping electrode according to claim 1, characterized in that: In step S2, etching is performed using a corrosive solution. When the material layer is a SiO2 layer, the corrosive solution is diluted hydrofluoric acid or BOE; when the material layer is a SiN x When the material layer is an InP layer, the etching liquid is a hydrochloric acid-based etching liquid; when the material layer is an InGaAsP layer, the etching liquid is a sulfuric acid-based etching liquid.

6. A method for preparing a laser, characterized in that: The electrode is prepared by using the method for preparing an electrode with gold wire anti-flipping as described in any one of claims 1 to 5.

7. The laser manufacturing method according to claim 6, characterized in that: When preparing the laser front electrode, the material layer is a passivation material layer, specifically: First, a ridge waveguide structure or buried heterojunction structure is made on the surface of the wafer. After the fabrication is completed, the passivation material layer is grown. Then, a front electrode pattern is produced, and the electrodes are prepared on the passivation material layer using the steps S2 to S5.

8. The laser manufacturing method according to claim 6, characterized in that: When preparing the laser back electrode, specifically: After the laser completes the thinning of the back substrate, the back material surface is a semiconductor material layer. Then, a back electrode pattern is produced, and the electrodes are prepared on the semiconductor material layer using the steps S2 to S5.

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