A semiconductor laser chip using a patterned metal substrate and a preparation method thereof

Abstract

The present invention relates to a semiconductor laser chip using a patterned metal substrate and a method for preparing the same. This approach addresses the problem that, when existing semiconductor laser chips use gallium arsenide as the chip substrate, the heat source generated by the chip substrate is high, and the traditional heat dissipation path has high thermal resistance and poor heat dissipation efficiency during heat transfer. The present invention provides an etched groove on the original chip substrate, and arranges a deposited metal layer within the etched groove to replace part of the gallium arsenide substrate material. The metal material within the deposited metal layer has low electrical resistance and high thermal conductivity. This design reduces the overall resistance of the chip substrate and the heat source, thereby improving electro-optical conversion efficiency. The deposited metal layer is located below the light-emitting unit, so that the heat generated by the light-emitting unit can be conducted through the deposited metal layer to the solder layer, and then to the heat sink, thereby reconstructing the heat transfer path. Furthermore, the deposited metal layer has low thermal resistance, which can reduce the conduction thermal resistance along the entire heat transfer path and enhance heat dissipation.

Description

Technical Field

[0001] The present invention relates to a semiconductor laser chip, in particular to a semiconductor laser chip using a patterned metal substrate and a preparation method thereof. Background Art

[0002] In the field of optics, the main electro-optical conversion component for converting electrical energy into light energy is a semiconductor laser chip. However, some semiconductor laser chips have requirements for electrodes, and generally require the chip to be packaged in a positive package. For example, a semiconductor laser chip with a separated electrode design has an existing design in which the light-emitting unit 4 of the semiconductor laser chip is set on a chip substrate 3, and the chip substrate 3 is fixed on a heat sink 1 through a solder layer 2, and the entire chip is packaged in a positive package. The specific structure is as follows: Figure 1 As shown, however, with this arrangement, when the light emitting unit 4 transfers heat, the conduction thermal resistance in the vertical direction is relatively large, and the chip substrate 3 also generates relatively high heat source heat.

[0003] The heat generated by semiconductor laser chips is mainly divided into three parts: non-radiative recombination, free-carrier absorption, and Joule heating. Non-radiative recombination and free-carrier absorption are related to the epitaxial structure design of the light-emitting unit 4, while Joule heating is mainly generated in the electrodes, light-emitting unit 4, and chip substrate 3. For a specific laser structure, the thermal resistance and electrical resistance of the electrodes and the active area epitaxial structure cannot be changed, so the current focus of chip heat dissipation research is on the chip substrate 3. However, currently, near-infrared semiconductor laser chips generally use gallium arsenide as the chip substrate 3. Gallium arsenide is a semiconductor material with high resistivity (for example, a typical n-type doped 1*10 20 cm -3 , 3.6*10 -3 The characteristics of low Ω∙cm) and low thermal conductivity (typical value 46 W / m∙K) not only generate additional Joule heating, but also have relatively poor heat conduction and current conduction characteristics.

[0004] When the semiconductor laser chip generates heat, the heat generated by the light-emitting unit 4 is transferred to the solder layer 2 via the gallium arsenide substrate, and then conducted to the heat sink 1 via the solder layer 2. The heat is then conducted by the heat sink 1 to the coolant inside it, where heat exchange occurs at the solid-liquid interface, and the coolant removes the heat. Due to the characteristics of the gallium arsenide substrate, this traditional heat dissipation path results in high thermal resistance and poor heat dissipation efficiency during heat transfer. Although existing semiconductor laser chips use a new flip-chip packaging method to solve the problem of thermal conductivity characteristics, it still does not solve the problem of excessive heat from the chip substrate 3. Summary of the Invention

[0005] The purpose of the present invention is to solve the technical problems that when existing semiconductor laser chips use gallium arsenide material as the chip substrate, the heat source generated by the chip substrate is high, the heat dissipation path has high thermal resistance during heat transfer, and the heat dissipation efficiency is poor. The present invention provides a semiconductor laser chip using a patterned metal substrate and a preparation method thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A semiconductor laser chip using a patterned metal substrate comprises a chip substrate and a plurality of light-emitting units located on top of the chip substrate; the plurality of light-emitting units are evenly arranged along the length or width of the chip substrate, are arranged parallel to each other, and have a gap between adjacent light-emitting units; a solder layer is provided on the lower surface of the chip substrate, a heat sink is provided on the lower surface of the solder layer, and the chip substrate is fixed to the upper surface of the heat sink via the solder layer. The special feature of the chip laser chip is that:

[0008] The chip substrate is provided with a plurality of etching grooves, the depth direction of the etching grooves is arranged along the thickness direction of the chip substrate, and the plurality of etching grooves are respectively located under the plurality of light-emitting units and correspond to the positions of the light-emitting units;

[0009] A deposited metal layer matching the shape of the etching grooves is respectively provided in each of the etching grooves, and the bottom end surface of the deposited metal layer is flush with the lower surface of the chip substrate and contacts the upper surface of the solder layer;

[0010] The depth of the etched groove is the same as the thickness of the chip substrate, and the top width is 10%-150% of the width of the light-emitting unit. The bottom of the light-emitting unit is in contact with the chip substrate and the deposited metal layer.

[0011] Alternatively, the depth of the etched groove is not less than 50% of the thickness of the chip substrate, the top width is 10%-150% of the width of the light-emitting unit, and the opening is set downward, and the bottom of the light-emitting unit is connected to the top of the chip substrate.

[0012] Furthermore, the projection shape of the etched groove in a vertical plane perpendicular to the length direction of the light-emitting unit is a rectangle, an isosceles trapezoid or a stepped shape.

[0013] Furthermore, the depth of the etched groove is the same as the thickness of the chip substrate, the top width of the etched groove is greater than or equal to 10% of the width of the light-emitting unit and less than or equal to 50% of the width of the light-emitting unit, a plurality of etched grooves are provided on the bottom surface of a light-emitting unit, the layout direction of the plurality of etched grooves is the same as the layout direction of the light-emitting unit and the plurality of etched grooves are arranged parallel to each other, and the distance between two adjacent etched grooves is 50%-100% of the top width of the etched groove;

[0014] Alternatively, the depth of the etching groove is the same as the thickness of the chip substrate, the top width of the etching groove is greater than 50% of the width of the light-emitting unit and less than or equal to 150% of the width of the light-emitting unit, and an etching groove is provided on the bottom surface of a light-emitting unit.

[0015] Furthermore, the depth of the etched groove is not less than 50% of the thickness of the chip substrate, the top width of the etched groove is greater than or equal to 10% of the width of the light-emitting unit and less than or equal to 50% of the width of the light-emitting unit, a plurality of etched grooves are provided on the bottom surface of a light-emitting unit, the layout direction of the plurality of etched grooves is the same as the layout direction of the light-emitting unit and the plurality of etched grooves are arranged parallel to each other, and the distance between two adjacent etched grooves is 50%-100% of the top width of the etched groove;

[0016] Alternatively, the depth of the etching groove is not less than 50% of the thickness of the chip substrate, the top width of the etching groove is greater than 50% of the width of the light-emitting unit and less than or equal to 150% of the width of the light-emitting unit, and an etching groove is provided on the bottom surface of a light-emitting unit.

[0017] At the same time, the present invention also provides a method for preparing a semiconductor laser chip using a patterned metal substrate as described above, which is special in that it includes the following steps:

[0018] S1. Prepare semiconductor laser chip;

[0019] S2. Partially removing the chip substrate by etching to form a plurality of etched grooves on the chip substrate, wherein the plurality of etched grooves are respectively located under the plurality of light-emitting units and correspond to positions of the light-emitting units;

[0020] S3, filling the multiple etched grooves with metal materials using a deposition technique to form multiple deposited metal layers;

[0021] S4. After the deposition is completed, the lower surface of the chip substrate is polished so that the bottom end surface of the deposited metal layer is flush with the lower surface of the chip substrate and the lower surface of the chip substrate remains flat as a whole;

[0022] S5. Solder the lower surface of the chip substrate to the upper surface of the heat sink through the solder layer, and the bottom end surface of the deposited metal layer contacts the upper surface of the solder layer, thereby completing the preparation of the semiconductor laser chip using the patterned metal substrate.

[0023] Furthermore, in step S2, the etching method is dry etching or wet etching.

[0024] Furthermore, in step S3, the deposition technology is vacuum thermal evaporation deposition, vacuum electron beam evaporation deposition, magnetron sputtering deposition or ion beam sputtering deposition.

[0025] The beneficial effects of the present invention are:

[0026] (1) The present invention provides a semiconductor laser chip using a patterned metal substrate. An etched groove is opened on the original chip substrate, and a deposited metal layer is set in the etched groove to replace part of the gallium arsenide substrate material. The metal material in the deposited metal layer has low resistance and high thermal conductivity. This design reduces the overall resistance value of the chip substrate and reduces the heat source, thereby improving the electro-optical conversion efficiency; and the deposited metal layer is located on the lower side of the light-emitting unit, so that the heat generated by the light-emitting unit can be conducted to the solder layer through the deposited metal layer, and then to the heat sink, reconstructing the heat transfer path. The thermal resistance of the deposited metal layer is low, so the conduction thermal resistance on the entire heat transfer path can be reduced, thereby enhancing heat dissipation; in addition, compared with gallium arsenide, the deposited metal layer is a highly conductive channel, which helps to adjust the current distribution in the active area.

[0027] (2) The present invention provides a method for preparing a semiconductor laser chip using a patterned metal substrate, which does not change the original semiconductor laser chip tape-out process, and the original process of the chip substrate is retained. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of an existing semiconductor laser chip;

[0029] Figure 2 1 is a schematic structural diagram of an embodiment of a semiconductor laser chip using a patterned metal substrate according to the present invention;

[0030] Figure 3 is a pie chart showing the percentage of Joule heat of the chip substrate in an embodiment of the present invention;

[0031] Figure 4 This is a bar chart showing an example calculation distribution of Joule heat of a chip substrate in an embodiment of the present invention.

[0032] The following are the descriptions of the reference numerals:

[0033] 1-heat sink, 2-solder layer, 3-chip substrate, 4-light-emitting unit, 5-deposited metal layer. DETAILED DESCRIPTION

[0034] To further clarify the objectives, advantages, and features of the present invention, the following describes in further detail a semiconductor laser chip using a patterned metal substrate and a method for fabricating the same, in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent through the following specific embodiments.

[0035] Reference Figure 2The present invention discloses a semiconductor laser chip using a patterned metal substrate, comprising a chip substrate 3 and a plurality of light-emitting units 4 located on top of the chip substrate 3. The light-emitting units 4 are grown on the chip substrate 3 by crystal growth to form a single unit. In this embodiment, the light-emitting units 4 are transistors. The light-emitting units 4 are evenly arranged along the length or width of the chip substrate 3, and are arranged parallel to each other, with spaces between adjacent light-emitting units 4. A solder layer 2 is provided on the lower surface of the chip substrate 3, and a heat sink 1 is provided on the lower surface of the solder layer 2. The chip substrate 3 is fixed to the upper surface of the heat sink 1 via the solder layer 2.

[0036] Heat sink 1, like traditional semiconductor laser chips, utilizes a liquid-cooled heat sink, offering excellent heat dissipation and widespread use in existing chip production, eliminating the need for specialized customization and reducing production costs. The semiconductor laser chip of the present invention, utilizing a patterned metal substrate, generally shares the same structure as a traditional semiconductor laser chip, differing in that the chip substrate 3 is provided with multiple etched grooves, the depth of which extends along the thickness of the chip substrate 3. Each of the multiple etched grooves contains a deposited metal layer 5, each shaped to match the grooves. The multiple etched grooves are located below and align with the positions of the light-emitting units 4. The bottom surface of the deposited metal layer 5 is flush with the lower surface of the chip substrate 3 and in contact with the upper surface of the solder layer 2, thereby forming a patterned metal substrate.

[0037] The etched groove can be processed by dry etching or wet etching, and the etched groove can be processed into different shapes. For example, the projection shape of the etched groove in the vertical plane perpendicular to the length direction of the light-emitting unit 4 can be a rectangle, an isosceles trapezoid or a stepped shape. In this embodiment, in order to facilitate processing, the projection shape of the etched groove is a rectangle.

[0038] The deposited metal layer 5 needs to be filled into the etched grooves using a deposition technique. Common deposition techniques include vacuum thermal evaporation, vacuum electron beam evaporation, magnetron sputtering, or ion beam sputtering. The material used for the deposited metal layer 5 is generally a metal material with high conductivity and low thermal resistance, such as copper, gold, or other alloys. This allows part of the gallium arsenide substrate material to be replaced. The deposited metal layer 5 deposited into the etched grooves forms a metal channel with low resistance and high thermal conductivity, which can effectively reduce the resistance of the entire chip substrate 3, reduce Joule heating, and thus improve the electro-optical conversion efficiency.

[0039] The upper end surface of the deposited metal layer 5 can be in contact with the bottom surface of the light-emitting unit 4 or there can be a gap, that is, the depth of the etching groove is the same as the thickness of the chip substrate 3 or the depth of the etching groove is not less than 50% of the thickness of the chip substrate 3. If it is less than 50%, it will affect heat transfer.

[0040] After the etching groove is processed, its top width is generally 10%-150% of the bottom width of the light-emitting unit 4. The top width of the etching groove is 50% of the bottom width of the light-emitting unit 4. The top width of the etching groove and its depth have the following four corresponding relationships:

[0041] The first type is that the depth of the etching groove is the same as the thickness of the chip substrate 3, the top width of the etching groove is greater than or equal to 10% of the width of the light-emitting unit 4 and less than or equal to 50% of the width of the light-emitting unit 4, and multiple etching grooves can be provided on the bottom surface of a light-emitting unit 4. The layout direction of the multiple etching grooves is the same as the layout direction of the light-emitting unit 4 and the multiple etching grooves are arranged parallel to each other, and the distance between two adjacent etching grooves is 50%-100% of the top width of the etching groove;

[0042] The second type is that the depth of the etched groove is the same as the thickness of the chip substrate 3, but the top width of the etched groove is greater than 50% of the width of the light-emitting unit 4 and less than or equal to 150% of the width of the light-emitting unit 4. In this case, one etched groove is provided on the bottom surface of each light-emitting unit 4.

[0043] The third type is that the depth of the etching groove is not less than 50% of the thickness of the chip substrate 3, the top width of the etching groove is greater than or equal to 10% of the width of the light-emitting unit 4 and less than or equal to 50% of the width of the light-emitting unit 4, and a plurality of etching grooves are provided on the bottom surface of a light-emitting unit 4. The layout direction of the plurality of etching grooves is the same as the layout direction of the light-emitting unit 4 and the plurality of etching grooves are arranged parallel to each other, and the distance between two adjacent etching grooves is 50%-100% of the top width of the etching groove;

[0044] The fourth type is that the depth of the etching groove is not less than 50% of the thickness of the chip substrate 3, the top width of the etching groove is greater than 50% of the width of the light-emitting unit 4 and less than or equal to 150% of the width of the light-emitting unit 4, and an etching groove is correspondingly provided on the bottom surface of a light-emitting unit 4.

[0045] This arrangement makes the correspondence between the light emitting units 4 and the etching grooves more diverse, and during processing, the most suitable combination can be selected according to the processing capacity and actual conditions.

[0046] At the same time, the present invention also provides a method for preparing the semiconductor laser chip using the patterned metal substrate, comprising the following steps:

[0047] S1. Prepare semiconductor laser chip;

[0048] S2. removing a portion of the chip substrate 3 by dry etching or wet etching on the chip substrate 3 to form a plurality of etching grooves, wherein the plurality of etching grooves are respectively located under the plurality of light-emitting units 4 and correspond to the positions of the light-emitting units 4;

[0049] S3, filling metal materials in the multiple etching grooves by vacuum thermal evaporation deposition, vacuum electron beam evaporation deposition, magnetron sputtering deposition or ion beam sputtering deposition to form multiple deposited metal layers 5;

[0050] S4. After the deposition is completed, the bottom surface of the chip substrate 3 is polished so that the bottom end surface of the deposited metal layer 5 and the lower surface of the chip substrate 3 are located in the same plane, and the lower surface of the chip substrate 3 remains flat as a whole;

[0051] S5. Solder the lower surface of the chip substrate 3 to the upper surface of the heat sink 1 through the solder layer 2, and the bottom end surface of the deposited metal layer 5 contacts the upper surface of the solder layer 2, completing the preparation of the semiconductor laser chip using the patterned metal substrate.

[0052] The solution of the present invention is carried out after the epitaxial structure growth process is completed, has no impact on the traditional chip tape-out process, belongs to post-processing, and does not need to change the traditional chip tape-out process due to the production of a patterned metal substrate.

[0053] In order to verify the heat dissipation capability of semiconductor laser chips using patterned metal substrates, the following experiments were designed:

[0054] The control group used a 940nm semiconductor laser chip with a traditional gallium arsenide substrate and a drive current of 1100A. The laser chip has two power supply modes: pulse current and continuous current. The continuous current mode with the highest heat generation was selected for power supply. In this power supply mode, the optical power was 1050W and the electro-optical conversion efficiency was 67.4%. The chip substrate was n-type doped with 1*10 20 cm -3 The calculation is performed using a GaAs substrate as an example;

[0055] According to Joule's law, the entire GaAs substrate will generate 261.36 W of Joule heat, while the sum of non-radiative recombination, free carrier absorption, and electrode Joule heat is 246.5 W, and the total heat is 507.86 W. Figure 3 As shown, its Joule heat accounts for more than 50% of the total heat.

[0056] The experimental group implemented local pattern metallization on the chip substrate at a ratio of 60%, such as Figure 4 As shown in the figure (J represents Joule heat, 0.6Cu represents 60% copper, and 0.4GaAs represents 40% gallium arsenide), the yellow bar represents Joule heat, and the blue bar represents the sum of non-radiative recombination, free carrier absorption, and electrode Joule heat. It can be seen that the Joule heat of the chip substrate is reduced to 20.8% of the original total heat. This reduced heat alone can push the electro-optical conversion efficiency to 75%.

[0057] The embodiments described above are merely descriptions of specific implementation methods of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A semiconductor laser chip using a patterned metal substrate, comprising a chip substrate (3) and a plurality of light-emitting units (4) located on top of the chip substrate (3); the plurality of light-emitting units (4) are evenly arranged along the length or width direction of the chip substrate (3), are arranged parallel to each other, and a gap is provided between two adjacent light-emitting units (4); a solder layer (2) is provided on the lower surface of the chip substrate (3), a heat sink (1) is provided on the lower surface of the solder layer (2), and the chip substrate (3) is fixed to the upper surface of the heat sink (1) through the solder layer (2), characterized in that: The chip substrate (3) is provided with a plurality of etching grooves, the depth direction of the etching grooves being arranged along the thickness direction of the chip substrate (3), the plurality of etching grooves being respectively located on the lower side of the plurality of light-emitting units (4) and corresponding to the positions of the light-emitting units (4); A deposited metal layer (5) adapted to the shape of the etching grooves is respectively provided in each of the plurality of etching grooves, and the bottom end surface of the deposited metal layer (5) is flush with the lower surface of the chip substrate (3) and in contact with the upper surface of the solder layer (2); The depth of the etched groove is the same as the thickness of the chip substrate (3), and the top width is 10%-150% of the width of the light-emitting unit (4). The bottom of the light-emitting unit (4) is in contact with the chip substrate (3) and the deposited metal layer (5). Alternatively, the depth of the etched groove is not less than 50% of the thickness of the chip substrate (3), the top width is 10%-150% of the width of the light-emitting unit (4), and the opening is arranged downward, and the bottom of the light-emitting unit (4) is connected to the top of the chip substrate (3).

2. The semiconductor laser chip using a patterned metal substrate according to claim 1, characterized in that: The projection shape of the etching groove in a vertical plane perpendicular to the length direction of the light-emitting unit (4) is a rectangle, an isosceles trapezoid or a stepped shape.

3. The semiconductor laser chip using a patterned metal substrate according to claim 2, characterized in that: The depth of the etching groove is the same as the thickness of the chip substrate (3); the top width of the etching groove is greater than or equal to 10% of the width of the light-emitting unit (4) and less than or equal to 50% of the width of the light-emitting unit (4); a plurality of etching grooves are provided on the bottom surface of a light-emitting unit (4); the layout direction of the plurality of etching grooves is the same as the layout direction of the light-emitting unit (4) and the plurality of etching grooves are arranged parallel to each other; and the distance between two adjacent etching grooves is 50%-100% of the top width of the etching groove; Alternatively, the depth of the etching groove is the same as the thickness of the chip substrate (3), the top width of the etching groove is greater than 50% of the width of the light-emitting unit (4) and less than or equal to 150% of the width of the light-emitting unit (4), and one etching groove is provided on the bottom surface of one light-emitting unit (4).

4. The semiconductor laser chip using a patterned metal substrate according to claim 2, characterized in that: The depth of the etching groove is not less than 50% of the thickness of the chip substrate (3); the top width of the etching groove is greater than or equal to 10% of the width of the light-emitting unit (4) and less than or equal to 50% of the width of the light-emitting unit (4); a plurality of etching grooves are provided on the bottom surface of a light-emitting unit (4); the layout direction of the plurality of etching grooves is the same as the layout direction of the light-emitting unit (4) and the plurality of etching grooves are arranged parallel to each other; and the distance between two adjacent etching grooves is 50%-100% of the top width of the etching groove; Alternatively, the depth of the etching groove is not less than 50% of the thickness of the chip substrate (3), the top width of the etching groove is greater than 50% of the width of the light-emitting unit (4) and less than or equal to 150% of the width of the light-emitting unit (4), and one etching groove is provided on the bottom surface of one light-emitting unit (4).

5. A method for preparing a semiconductor laser chip using a patterned metal substrate according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Prepare semiconductor laser chip; S2, removing a portion of the chip substrate (3) by etching on the chip substrate (3) to form a plurality of etching grooves, wherein the plurality of etching grooves are respectively located on the lower sides of the plurality of light-emitting units (4) and correspond to the positions of the light-emitting units (4); S3, filling the plurality of etched grooves with metal material using a deposition technique to form a plurality of deposited metal layers (5); S4. After the deposition is completed, the lower surface of the chip substrate (3) is polished so that the bottom end surface of the deposited metal layer (5) is flush with the lower surface of the chip substrate (3), and the lower surface of the chip substrate (3) remains flat as a whole; S5. The lower surface of the chip substrate (3) is welded to the upper surface of the heat sink (1) through the solder layer (2), and the bottom end surface of the deposited metal layer (5) is in contact with the upper surface of the solder layer (2), thereby completing the preparation of the semiconductor laser chip using the patterned metal substrate.

6. The method for preparing a semiconductor laser chip using a patterned metal substrate according to claim 5, wherein: In step S2, the etching method is dry etching or wet etching.

7. The method for preparing a semiconductor laser chip using a patterned metal substrate according to claim 6, wherein: In step S3, the deposition technique is vacuum thermal evaporation deposition, vacuum electron beam evaporation deposition, magnetron sputtering deposition or ion beam sputtering deposition.

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