CN111969408A - Packaging structure and packaging method - Google Patents

Abstract

The present invention provides a package structure, which is characterized by comprising: a VCSEL type laser source, including a first DBR region and a second DBR region, an active region disposed between the first DBR region and the second DBR region, Also includes a base layer connected to the first DBR region, electrically connected to the first electrode of the first DBR region and electrically connected to the second electrode of the second DBR region, the first electrode and the second electrode are located on the same side of the second DBR region; the VCSEL type laser source is electrically connected to the two electrodes of the package substrate; the VCSEL type laser source is directed from the active region to the base layer The directional output emits light. On the one hand, the distance between the active area and the package substrate is set closer, which is conducive to quickly exporting a large amount of heat generated by the active area to ensure the reliability of the laser source. On the other hand, the two The electrodes and the package substrate are electrically connected by plane to eliminate the parasitic inductance caused by the use of lead wires in the prior art.

Description

A packaging structure and packaging method

technical field

The present invention relates to the technical field of packaging, and in particular, to a packaging structure and a packaging method for a VCSEL laser.

Background technique

Semiconductor-type lasers, due to their excellent controllable performance and easy implementation of array-type integrated design, are more and more used in various detection processes, and can be easily realized by controlling voltage and other characteristics. The adjustment of laser parameters is very beneficial to the entire system. Semiconductor lasers refer to lasers that use semiconductor materials as working substances, also known as semiconductor laser diodes (LDs), which are a kind of laser developed in the 1960s. There are dozens of working materials of semiconductor lasers, such as gallium arsenide (GaAs), cadmium sulfide (CdS), etc. The excitation methods mainly include electric injection, optical pumping and high-energy electron beam excitation. The advantages of semiconductor lasers mainly include the following aspects: 1) Small size and light weight. 2) Injectable excitation: it can be driven by injecting milliampere current with only a few volts. No other energizing equipment and components other than the power supply unit are required. Electric power is directly converted into optical power, with high energy efficiency. 3) Wide wavelength range: With proper selection of materials and alloy ratios, lasers of any wavelength can be realized in a wide wavelength range of infrared and visible light. 4) Can be directly modulated: The signal is superimposed on the driving current, and the oscillation intensity, frequency and phase can be modulated in the range of DC to G Hz. 5) High coherence: a single transverse mode laser can obtain output light with high spatial coherence. In Distributed Feedback (DFB) and Distributed Bragg Reflection (DBR) lasers, stable single longitudinal mode lasing can be obtained, and advantages such as high temporal coherence can be obtained.

One of the most widely used semiconductor lasers at present is the surface-emitting semiconductor laser, which also has many advantages compared with the traditional edge-emitting laser. -Emitting Lasers) because of its low threshold, circular beam, easy coupling and easy two-dimensional integration, it also has the advantages of high side mode suppression ratio, low threshold, small size, easy integration, and high output power. . Examples include structured light sources for 3D imaging, laser detection and ranging (LADAR), time-of-flight (TOF) 3D imaging, aerospace defense and fusion research, etc. Vertical Cavity Surface Emitting Lasers (VCSELs) are commonly used in many semiconductor laser applications due to low power applications and high frequency advantages and manufacturing advantages over other types of semiconductor laser devices. In the TOF ranging process, it is necessary to ensure that the VCSEL laser source has reliable laser light The output, however, is the current packaging scheme in which the VCSEL device is front mounted to the packaged substrate via solder or epoxy. Then, wire bonding can be used to connect the VCSEL device to the external circuit, so that there is parasitic inductance between the leads itself, for example, there is a parasitic inductance of 1nH in the lead of 1mm. , so that the performance of the VCSEL device itself, the heat generated by the VCSEL itself is mainly the P-DBR and the active area. The distance between the P-DBR and the active region is far from the substrate, which is not conducive to the timely export of heat, resulting in heat accumulation, which affects the light extraction efficiency of the VCSEL. These factors affect the reliability of the package structure, especially the reliability application in the TOF ranging process, which restricts the accuracy of the TOF ranging.

Therefore, it is an urgent problem to develop a package structure and method that can eliminate the parasitic inductance generated by the leads of the prior art, have reliable heat dissipation, and can be produced quickly and efficiently, and use it in the TOF ranging system to achieve high-precision measurement .

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a semiconductor laser transmitter in view of the above-mentioned deficiencies in the prior art, so as to solve the parasitic inductance caused by the lead wire, difficult heat dissipation, low detection efficiency and poor accuracy in the related art. Some series of problems can even cause the entire laser transmitter to be unusable.

To achieve the above purpose, the technical solutions adopted in the embodiments of the present invention are as follows:

A first aspect of the embodiments of the present invention provides a package structure, which is characterized by comprising: a VCSEL type laser source, including a first DBR region and a second DBR region, and disposed between the first DBR region and the second DBR region an active region between, further comprising a base layer connected to the first DBR region, electrically connected to the first electrode of the first DBR region and electrically connected to the second electrode of the second DBR region, The first electrode and the second electrode are located on the same side of the second DBR region; the VCSEL type laser source and the two electrodes of the package substrate are both electrically connected in plane; the VCSEL type laser source is powered by the active The region outputs the emitted light in the direction of the base layer.

Optionally, the first DBR layer is an N conductive type material, and the second DBR layer is a P conductive type material.

Optionally, an insulating structure is included between the first electrode and the second electrode so that the first electrode and the second electrode cannot be electrically connected.

Optionally, a VCSEL type laser source driver connected to the packaging substrate is also included, and the laser source driver and the VCSEL type laser source are located on the same side of the packaging substrate.

Optionally, it also includes an array-type receiving module connected to the packaging substrate, and the connecting conductors of the array-type receiving module are located in the packaging substrate or the ceramic frame.

A second aspect provides an encapsulation method for implementing the encapsulation structure described in the first aspect, comprising:

a VCSEL type laser source, comprising a first DBR region and a second DBR region, an active region disposed between the first DBR region and the second DBR region, and a base layer connected to the first DBR region, a first electrode electrically connected to the first DBR region and a second electrode electrically connected to the second DBR region, the first electrode and the second electrode being located on the same side of the second DBR region ; The plane is electrically connected to the two electrodes of the VCSEL type laser source and the packaging substrate; the VCSEL type laser source outputs the emitted light from the active region to the direction of the base layer.

Optionally, the first DBR layer is an N conductive type material, and the second DBR layer is a P conductive type material.

Optionally, an insulating structure is included between the first electrode and the second electrode so that the first electrode and the second electrode cannot be electrically connected.

Optionally, a VCSEL type laser source driver connected to the packaging substrate is also included, and the laser source driver and the VCSEL type laser source are arranged on the same side of the packaging substrate.

Optionally, an array-type receiving module connected to the packaging substrate is also included, and the connecting conductors of the array-type receiving module are located in the packaging substrate or the ceramic frame.

The beneficial effects of the present invention are as follows: the present invention proposes a package structure, which is characterized by comprising: a VCSEL type laser source, including a first DBR area and a second DBR area, and are arranged in the first DBR area and the second DBR area The active region between the regions further comprises a base layer connected to the first DBR region, electrically connected to the first electrode of the first DBR region and electrically connected to the second electrode of the second DBR region electrodes, the first electrode and the second electrode are located on the same side of the second DBR region; the VCSEL type laser source and the two electrodes of the package substrate are both electrically connected in plane; the VCSEL type laser source is formed by the The active region outputs the emitted light in the direction of the base layer. On the one hand, the distance between the active region and the package substrate is set closer by such a design, which is conducive to quickly exporting a large amount of heat generated by the active region and ensuring the reliability of the laser source. On the other hand, the two electrodes of the laser source and the package substrate are electrically connected by plane to eliminate the parasitic inductance caused by the use of lead wires in the prior art.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

1 is a schematic diagram of the package structure of a VCSEL laser source and a drive and detection array provided in the prior art;

2A is a structural front view of a VCSEL laser source provided by an embodiment of the present invention;

2B is a top view of the structure of a VCSEL laser source according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a connection between a VCSEL laser source and a packaging substrate according to an embodiment of the present invention;

4A is a front view of a connection between a VCSEL laser source, a Driver driver chip and a package substrate provided by an embodiment of the present invention;

4B is a top view of a connection between a VCSEL laser source, a Driver driver chip and a package substrate provided by an embodiment of the present invention;

5A is a front view of a package structure of a sensor detection chip according to an embodiment of the present invention;

5B is a top view of a package structure of a sensor detection chip according to an embodiment of the present invention;

6A is a front view of a package structure of each module of a detection device provided by an embodiment of the present invention;

6B is a top view of a package structure of each module of a detection device according to an embodiment of the present invention.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments.

1 is a schematic diagram of the packaging structure of a VCSEL laser source and a drive and detection array in the prior art; after the VCSEL chip is attached to the submount, the positive and negative electrodes are drawn out by wire bonding, and the packaging of the entire module is completed in cooperation with the laser driver and the sensor chip. , where the VCSEL laser source 101 is positioned above the Driver drive part 103, one electrode of the VCSEL laser source 101 is connected to the connecting plate plane between the drive part 103 and the VCSEL laser source, and the other electrode needs to be drawn out due to the characteristics of the laser The lead 102 is connected to the other pole of the output of the driving part 103. In addition, the connection of the driving part 103 also needs the lead 104. Similarly, the Sensor (usually an array type photosensitive part) 107 also needs the lead 106 and the package substrate 105. Connection, under this existing package connection structure, there will be some disadvantages as follows: a) The lead inductance of 1mm 1nH is inevitable when the VCSEL leads out. b) The driver signal from the driver chip is sent to the VCSEL through the flex board. The path is very long, and the design of eliminating the inductance must be done on the flex board. c) The VCSEL is placed on the upper surface of the driver chip Driver, which poses a great challenge to the heat dissipation design of the VCSEL, so that the VCSEL cannot work for a long time because the heat cannot be dissipated. d) The VCSEL emits light from the P surface. According to the performance of the VCSEL device itself, the heat generated by the VCSEL itself is mainly the P-DBR and the active area. However, under the existing structure, the P-DBR and the active area are far away from the substrate, which is not conducive to heat in time. The export generates heat accumulation, which in turn affects the light extraction efficiency of the VCSEL.

2A is a front view of the structure of a VCSEL laser source provided by an embodiment of the present invention; the present invention first optimizes the structure of the VCSEL laser source, wherein 202a and 202b are the first electrode and the second electrode of the laser source, wherein the electrodes Materials can be (Au), germanium (Ge), silver (Ag), palladium (Pd), platinum (Pt), nickel (Ni), titanium (Ti), vanadium (V), tungsten (W). ), chromium (Cr), aluminum (Al), copper (Cu), zinc (Zn), tin (Sn) and indium (In) and other materials, of course, not limited to metal materials, but also metal oxides, etc. A transparent electrode is formed, the first electrode is connected to the first DBR layer (that is, the 211N Bragg Reflector Distributed Bragg Reflection in the figure), which has a laminated structure in which low-refractive index layers and high-refractive index layers are alternately stacked. The low refractive index layer is, for example, n-type AlX1Ga(1-X1)As (0<X1<1) with an optical film thickness of λ/4 (or (2k+1)*λ/4). λ represents the oscillation wavelength of the semiconductor laser 1 . The high refractive index layer is, for example, n-type AlX2Ga(1-X2)As (0≤X2<X1) with an optical film thickness of λ/4 (or (2k+1)*λ/4), which is only illustratively described here , and it is not specifically limited that the implementation material must be for this purpose, and the Bragg-type structure setting in which the medium and low refractive index and the high refractive index are alternately stacked can be satisfied. The second electrode 202b is connected to the second DBR layer, namely 209 in the figure, which has a laminated structure in which low-refractive index layers and high-refractive index layers are alternately stacked. The low refractive index layer is, for example, p-type AlX3Ga(1-X3)As (0<X3<1) with an optical film thickness of λ/4 (or (2k+1)*λ/4). The high-refractive-index layer is, for example, p-type AlX4Ga(1-X4)As (0≤X4<X3) with an optical film thickness of λ/4 (or (2k+1)*λ/4), which is just an example here. Note, it is not specifically limited that the implementation materials must be for this purpose, and the Bragg-type structure setting in which the medium and low refractive index and the high refractive index are alternately stacked can be set. The active region 210 has a quantum well structure, and in the quantum well structure, alternately stacked A quantum well layer with an undoped Al0.11As0.89GaAs quantum well layer with a thickness of 8 nm and a barrier layer with an undoped Al0.3Ga0.7As layer with a thickness of 5 nm. For example, the active region 210 is designed to emit light with a wavelength of 780 nm (actually not limited to this wavelength), and the optical thickness of the active region 210 is an integer multiple of 1/2 the laser wavelength to satisfy the resonance condition. The isolation layer formed by the undoped Al0.6Ga0.4As layer as a layer for forming the active region 210 includes a quantum well structure in its center, of course, the specific material and thickness relationship is not limited to this, here only for example descriptions. The film thickness of the entire isolation layer is as large as an integer multiple of λ/n _r , where λ is the oscillation wavelength and n _r is the refractive index of the medium, and a voltage is applied through the first electrode 202a and the second electrode 202b to realize the light emission of the diode, In the present invention, both the first electrode 202a and the second electrode 202b are arranged to be connected to the second DBR region 209 through internal settings, and are located on the same side of the second DBR region 209, the upper part in the figure, so as to ensure the driving of the laser source. The two electrodes are located on the same side, which is easy to realize the plane connection with the packaging substrate. On the other hand, the VCSEL type laser source outputs the emitted light from the active region to the direction of the base layer, so that the connection part with the substrate is It is arranged on the side away from the base layer 208, and the light exits in the direction of the base layer 208, so that the active area 210, as the largest heat generating part, will generate more heat to the first electrode and the second electrode side, and the heat generated in this way will soon be led to the package substrate 205, and in this configuration, the substrate 208 layer will no longer be an obstacle to heat dissipation. In this way, the effect of rapid heat dissipation of the device is achieved, and the operating reliability of the device and the accuracy of laser emission are ensured. The insulating structure 212 is included between the first electrode and the second electrode, so that the first electrode and the The second electrodes cannot be electrically connected, so that the same effect as the separate arrangement of the first electrode and the second electrode can be achieved, and there will be no influence between the two electrodes, which also ensures the reliable operation of the entire device.

2B is a top view of the structure of a VCSEL laser source provided by an embodiment of the present invention; here the first electrodes of all emitting units of the entire VCSEL light source are connected together, and all the second electrodes are connected together, thereby forming a structure capable of driving the entire The driving part of the light-emitting array, of course, can also be connected together in actual use to form two or more light-emitting parts that can be driven separately to achieve the effect of partitioned emission. This is not limited to a schematic illustration. In this way, the first electrode 202a and the second electrode 202b can be arranged on the same side, and the two electrodes are optimally arranged in a planar structure, so that the VCSEL laser source can be easily connected to the package substrate.

3 is a schematic structural diagram of a connection between a VCSEL laser source and a packaging substrate provided by an embodiment of the present invention; through the structural design of the VCSEL laser source in FIG. Basically, the first electrode of the VCSEL laser source is directly welded to the second electrode of the VCSEL laser source and the corresponding electrode of the package substrate by welding, which realizes the direct connection of direct planarization, so that the two electrodes do not use external leads, which reduces or The parasitic inductance is eliminated, which is very important for ITOF ranging to obtain high-precision measurement results. On the other hand, the reliability of the connection is also achieved through this structure, and the VCSEL light source provided by the present invention is used for the rapid heat dissipation of the active area. The characteristic achieves a more accurate characteristic of the light output from the light source.

4A is a front view of the connection between a VCSEL laser source, a Driver driver chip and a packaging substrate provided by an embodiment of the present invention, and the packaging scheme is used in the packaging process of the ITOF ranging system, so that the layout of the entire chip is compact, The Driver part 403 and the VCSEL are arranged on the same side of the substrate 405, so that the electrical connection line between the two does not need to rely on the lead wire, which ensures the high working accuracy of the ITOF ranging system. In addition, this arrangement also ensures the entire module. The ease of installation allows the entire packaging operation to operate more efficiently.

4B is a top view of a VCSEL laser source connected to a driver chip and a package substrate according to an embodiment of the present invention, and each part and its functions are not repeated here.

5A is a front view of a package structure of a sensor detection chip provided by an embodiment of the present invention. This package solution may be called flipchip package. The connection conductor of the array-type receiving module is located in the package substrate or the ceramic frame, that is, in the figure 507 is an array type receiving module. For example, the application scenario of the present invention is ITOF ranging, which is a ranging array of the ITOF scheme. The distance information of the detected target is obtained by receiving four sets of return signals with different phase differences, and 513 is an array. In the present invention, the driver circuit is arranged in the substrate or the ceramic frame 514, and it is set in advance, and the contact portion of the driver circuit 513 is exposed at the end of the substrate or the ceramic frame 514. It is connected to the 507 array receiving module in other ways, so there is no need to set additional connection leads externally, thus ensuring that the entire detection system will not generate parasitic inductance, and the detection system packaged in this way can also achieve efficient and accurate detection results, especially ITOF In the detection scheme, the accuracy of the delay phase receiving control is very high. Therefore, the packaging structure is also the basis for ensuring high-precision and high-speed measurement of ITOF. The filter layer is not necessary and can also be replaced by other light-transmitting materials. Not limited here .

5B is a top view of a package structure of a sensor detection chip according to an embodiment of the present invention, and the functions and effects of each part will not be described in detail here.

6A is a front view of the packaging structure of each module of a detection device provided by an embodiment of the present invention; here the detection system mainly refers to that each module of the ITOF ranging system is arranged on one side of the packaging substrate, thus realizing the entire detection system The simplicity of installation, but the actual implementation is not limited to this method, in which the VCSEL light source 601 and the Driver driving part 603 share the packaging substrate, and the detector receiving module 607 can be shared with the packaging substrate of the two, or use a ceramic frame, here It is not limited, and the detection system where the detection system is ITOF is packaged according to this structure, which ensures the efficiency of production and the convenience of installation. Encapsulating the VCSEL as shown in Figure 6A is far away from the detection array, which can ensure that the heat between these two components is not affected, and the heat can be quickly transferred to ensure the working efficiency of the entire system. In addition, the VCSEL and the The distance between the detection arrays and the Driver drive unit can ensure that the light emitted by the transmitting end will not affect some pixels of the detector array, especially the pixels near the edge, which ensures the accuracy of the detection results. The high efficiency and accuracy of the system is ensured by not using the lead method, which will not be repeated here. Of course, the layout structure of FIG. 6A may not be used. For example, the driver is placed on the other side of the package substrate, and the VCSEL substrate and the The sandwich stack structure of the Driver is not limited here. According to the design of this solution, a heat dissipation structure can be provided on the other side of the package substrate, thereby ensuring the reliability of the entire system, which will not be repeated here.

FIG. 6B is a top view of the package structure of each module of a detection device according to an embodiment of the present invention, and the functions and effects of each component are not repeated here.

The following technical advantages are achieved through the technical solution of the present invention:

1. The parasitic parameters brought by the lead process can be reduced.

2. Reduce the signal crosstalk generated by the large high-speed driving current signal through the inductive effect of the lead.

3. Reduce the lead steps and have no moving parts at all, improving reliability.

It should be noted that, in this document, relational terms such as "first" and "second" etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply these There is no such actual relationship or sequence between entities or operations. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element. The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application. It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures. The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims (10)

1. A package structure, comprising:

a VCSEL-type laser source comprising a first DBR section and a second DBR section, an active region disposed between the first DBR section and the second DBR section, and a base layer connected to the first DBR section, a first electrode electrically connected to the first DBR section and a second electrode electrically connected to the second DBR section, the first electrode and the second electrode being located on the same side of the second DBR section;

the VCSEL type laser source is electrically connected with two electrodes of the packaging substrate in a planar mode;

the VCSEL type laser source outputs emitted light from the active region toward the base layer.

2. The package structure of claim 1, wherein the first DBR layer is an N-conductivity type material and the second DBR layer is a P-conductivity type material.

3. The package structure of claim 1, wherein an insulating structure is included between the first electrode and the second electrode to prevent electrical connection between the first electrode and the second electrode.

4. The package structure of claim 1, further comprising a VCSEL-type laser source driver connected to the package substrate, and wherein the laser source driver is located on the same side of the package substrate as the VCSEL-type laser source.

5. The package structure of claim 1, further comprising an array-type receiving module connected to the package substrate, wherein the connection conductors of the array-type receiving module are located within the package substrate or the ceramic frame.

6. A packaging method for implementing the package structure of claim 1, comprising:

a VCSEL-type laser source comprising a first DBR section and a second DBR section, an active region disposed between the first DBR section and the second DBR section, and a base layer connected to the first DBR section, a first electrode electrically connected to the first DBR section and a second electrode electrically connected to the second DBR section, the first electrode and the second electrode being located on the same side of the second DBR section;

the plane is electrically connected with the VCSEL type laser source and two electrodes of the packaging substrate; the VCSEL type laser source outputs emitted light from the active region toward the base layer.

7. The method of packaging of claim 6, wherein the first DBR layer is an N-conductivity type material and the second DBR layer is a P-conductivity type material.

8. The method of claim 6, wherein an insulating structure is disposed between the first electrode and the second electrode to prevent electrical connection between the first electrode and the second electrode.

9. The packaging method of claim 6, further comprising a VCSEL-type laser source driver connected to the packaging substrate, and wherein the laser source driver is disposed on the same side of the packaging substrate as the VCSEL-type laser source.

10. The method of claim 6, further comprising an array-type receiving module connected to the package substrate, wherein the connection conductors of the array-type receiving module are located within the package substrate or the ceramic frame.

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