CN115483120B - Micro-connection process based on laser ultrasonic coupling - Google Patents

Abstract

The invention relates to the technical field of electronic component packaging, and provides a micro-connection process based on laser ultrasonic coupling, comprising: sequentially attaching a first adhesion layer, a seed layer, a first bonding layer, a second bonding layer and an anti-oxidation layer on the open end face of a tube shell, and sequentially attaching a second adhesion layer and a third bonding layer on the cover surface of a semiconductor wafer cover; placing the electronic component into the tube shell, and covering the cover surface of the semiconductor wafer cover plate on the open end face; determining a laser bonding path by the open end, turning on an ultrasonic generator to drive the tube shell and the semiconductor wafer cover plate to vibrate; controlling the laser emitted by the laser generator to move along the laser bonding path on the semiconductor wafer cover plate; the first bonding layer and the third bonding layer are made of the same material, and the melting point of the first bonding layer is higher than the melting point of the second bonding layer; the invention ensures the instantaneousness and reliability of packaging by using laser as a heat source for transient liquid phase bonding and intervening ultrasonic waves in the reaction process of transient liquid phase bonding.

Description

Micro-joining process based on laser ultrasonic coupling

Technical Field

The invention relates to the technical field of electronic component packaging, and in particular to a micro-connection process based on laser ultrasonic coupling.

Background technique

With the development of the integrated circuit field, electronic components are becoming miniaturized and highly integrated. In order to ensure the stability and reliability of the electronic components, they need to be well packaged. On the one hand, it can reduce the mechanical vibration damage of the electronic components, and on the other hand, it can ensure good vacuum and airtightness.

Existing packaging methods include thermocompression bonding and surface activated bonding. Thermocompression bonding is achieved by heating and applying pressure to the bonding interface to allow atoms to diffuse and recrystallize to achieve connection. However, the process temperature of thermocompression bonding usually reaches above 300°C. High temperature will increase the thermal stress in the bonding joint, reduce the connection strength, and easily damage the thermosensitive components. Surface activated bonding is achieved by bombarding the bonding interface with a high-energy particle beam to remove the surface oxide layer and contaminants to obtain a highly active material surface. Applying pressure can achieve a strong bond at room temperature. However, the process of surface activated bonding is complicated and has high requirements for equipment.

Summary of the invention

The present invention provides a micro-connection process based on laser ultrasonic coupling, which is used to solve or improve the problems of complex packaging process and low reliability in the packaging process of existing electronic components.

The present invention provides a micro-connection process based on laser ultrasonic coupling, comprising: sequentially attaching a first adhesion layer, a seed layer, a first bonding layer, a second bonding layer and an anti-oxidation layer on an open end surface of a tube shell, and sequentially attaching a second adhesion layer and a third bonding layer on a cover surface of a semiconductor wafer cover plate;

Putting electronic components into the tube shell, and placing the covering surface of the semiconductor wafer cover plate on the open end surface so that the anti-oxidation layer contacts the third bonding layer;

Determine a laser bonding path according to the opening, turn on an ultrasonic generator to drive the tube shell and the semiconductor wafer cover to vibrate; control the laser emitted by the laser generator to move along the laser bonding path on the semiconductor wafer cover;

The first bonding layer and the third bonding layer are made of the same material, and the melting point of the first bonding layer is higher than the melting point of the second bonding layer.

According to a micro-connection process based on laser ultrasonic coupling provided by the present invention, the covering surface of the semiconductor wafer cover plate is placed on the open end surface, comprising:

The tube shell is placed in the groove of the packaging platform, and the covering surface of the semiconductor wafer cover plate is placed on the end surface of the opening, and the semiconductor wafer cover plate abuts against the end surface of the opening under the action of the transparent pressing plate on the packaging platform;

Wherein, the ultrasonic generating device is arranged on the packaging platform.

According to a micro-connection process based on laser ultrasonic coupling provided by the present invention, the first adhesion layer, the seed layer, the first bonding layer, the second bonding layer and the anti-oxidation layer are sequentially attached to the open end surface of the tube shell, comprising:

Depositing the first adhesion layer having a thickness ranging from 1.9 micrometers to 2.1 micrometers on the end surface by an electron beam evaporation process;

Wherein, the first adhesion layer is a nickel adhesion layer.

According to a micro-connection process based on laser ultrasonic coupling provided by the present invention, the first adhesion layer, the seed layer, the first bonding layer, the second bonding layer and the anti-oxidation layer are sequentially attached to the open end surface of the tube shell, and further includes:

electroplating the seed layer having a thickness ranging from 2.85 micrometers to 3.15 micrometers on the first adhesion layer;

Wherein, the seed layer is a gold seed layer.

According to a micro-connection process based on laser ultrasonic coupling provided by the present invention, the first adhesion layer, the seed layer, the first bonding layer, the second bonding layer and the anti-oxidation layer are sequentially attached to the open end surface of the tube shell, and further includes:

The first bonding layer is electroplated on the seed layer with a thickness ranging from 2.85 microns to 3.15 microns.

According to a micro-connection process based on laser ultrasonic coupling provided by the present invention, the first adhesion layer, the seed layer, the first bonding layer, the second bonding layer and the anti-oxidation layer are sequentially attached to the open end surface of the tube shell, and further includes:

The second bonding layer having a thickness ranging from 1.9 micrometers to 2.1 micrometers is electroplated on the first bonding layer.

According to a micro-connection process based on laser ultrasonic coupling provided by the present invention, the first adhesion layer, the seed layer, the first bonding layer, the second bonding layer and the anti-oxidation layer are sequentially attached to the open end surface of the tube shell, and further includes:

Electroplating the anti-oxidation layer with a thickness ranging from 0.027 micrometers to 0.033 micrometers on the second bonding layer;

Wherein, the material of the anti-oxidation layer is the same as that of the first bonding layer.

According to a micro-connection process based on laser ultrasonic coupling provided by the present invention, the second adhesive layer and the third bonding layer are sequentially attached to the covering surface of the semiconductor wafer cover plate, comprising:

Depositing the second adhesion layer having a thickness ranging from 0.045 micrometers to 0.055 micrometers on the covering surface by an electron beam evaporation process;

Wherein, the second adhesion layer is a titanium adhesion layer.

According to a micro-connection process based on laser ultrasonic coupling provided by the present invention, the second adhesive layer and the third bonding layer are sequentially attached to the covering surface of the semiconductor wafer cover plate, and further comprises:

The third bonding layer having a thickness ranging from 2.85 micrometers to 3.15 micrometers is electroplated on the second adhesion layer.

According to a micro-connection process based on laser ultrasonic coupling provided by the present invention, the first bonding layer and the third bonding layer are both silver bonding layers, and the second bonding layer is an indium bonding layer;

Alternatively, the first bonding layer and the third bonding layer are both gold bonding layers, and the second bonding layer is a tin bonding layer;

Alternatively, the first bonding layer and the third bonding layer are both copper bonding layers, and the second bonding layer is a tin bonding layer.

The micro-connection process based on laser ultrasonic coupling provided by the present invention uses laser as the heat source of transient liquid phase bonding and introduces ultrasound into the reaction process of transient liquid phase bonding. While ensuring the performance of electronic components, it reduces the bonding heat affected zone, accelerates the reaction process of transient liquid phase bonding, and improves the stability, reliability and efficiency of electronic component packaging. The micro-connection process based on laser ultrasonic coupling has good adaptability and is particularly suitable for applications in the fields of thermosensitive components, infrared detectors and wafer-level airtight packaging.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic diagram of a process flow of a micro-connection process based on laser ultrasonic coupling provided by the present invention;

FIG2 is a schematic diagram of the overall structure of the tube shell and the semiconductor wafer cover provided by the present invention;

3 is a schematic structural diagram of a second metallization layer on a semiconductor wafer cover provided by the present invention;

FIG4 is a schematic diagram of the structure of the first metallization layer on the tube shell provided by the present invention;

FIG5 is a schematic diagram of the structure of a packaging platform provided by the present invention;

FIG6 is a schematic structural diagram of an ultrasonic generating device provided by the present invention;

7 is a schematic diagram of the structure of the tube shell and the semiconductor wafer cover plate after bonding provided by the present invention;

Reference numerals:

1: tube shell; 11: adhesion layer; 12: seed layer; 13: first bonding layer; 14: second bonding layer; 15: anti-oxidation layer; 2: semiconductor wafer cover; 21: second adhesion layer; 22: third bonding layer; 3: packaging platform; 31: sample stage; 32: spring clamp; 33: three-axis displacement platform; 331: first handle; 332: second handle; 333: third handle; 34: base; 35: transparent pressing plate; 4: ultrasonic generator; 5: laser generator; 6: Ag ₂ In layer.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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.

In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

A micro-connection process based on laser ultrasonic coupling provided by the present invention is described below in conjunction with FIGS. 1 to 7 .

As shown in FIG. 1 , the micro-connection process based on laser ultrasonic coupling shown in this embodiment includes: step 110 , step 120 and step 130 .

Step 110, sequentially attaching a first adhesive layer, a seed layer, a first bonding layer, a second bonding layer and an anti-oxidation layer on the open end surface of the tube shell, and sequentially attaching a second adhesive layer and a third bonding layer on the covering surface of the semiconductor wafer cover.

As shown in FIG2 , the material of the tube shell 1 is alumina. The manufacturing method of the tube shell 1 is as follows, taking a rectangular block of alumina with a length, width and height of 7 mm, 7 mm and 0.8 mm as an example for explanation, a rectangular mounting groove with a length of 6.1 mm, a width of 6.1 mm and a depth of 0.5 mm is provided in the center of the square face of the rectangular block, thereby forming a tube shell 1 with an opening at one end, the notch of the mounting groove is the opening of the tube shell 1, and the mounting groove is used to arrange the electronic components to be packaged.

Among them, a metal pad is pre-made on the tube shell 1, so that the electronic components in the tube shell 1 can be electrically connected with the components outside the tube shell 1 by wire bonding.

The material of the semiconductor wafer cover plate 2 is silicon, and the semiconductor wafer cover plate 2 is cut on the wafer by a semiconductor dicing machine, and the wafer is made by the front-end process; the length, width and height of the semiconductor wafer cover plate 2 are 6.8mm, 6.8mm, and 0.5mm respectively, so that the semiconductor wafer cover plate 2 of this size can be adapted to the tube shell 1 of the above size, and the semiconductor wafer cover plate 2 can be covered on the opening of the tube shell 1 to form a closed structure.

As shown in FIGS. 3 and 4 , after the tube shell 1 and the semiconductor wafer cover plate 2 are manufactured, the first adhesion layer 11, the seed layer 12, the first bonding layer 13, the second bonding layer 14 and the anti-oxidation layer 15 are sequentially attached to the open end surface of the tube shell 1, and the first adhesion layer 11, the seed layer 12, the first bonding layer 13, the second bonding layer 14 and the anti-oxidation layer 15 form a first metallization layer; the second adhesion layer 21 and the third bonding layer 22 are sequentially attached to the covering surface of the semiconductor wafer cover plate 2, and the second adhesion layer 21 and the third bonding layer 22 form a second metallization layer, thereby preparing for the bonding package of the tube shell 1 and the semiconductor wafer cover plate 2.

The attachment method of the first adhesion layer 11 , the seed layer 12 , the first bonding layer 13 , the second bonding layer 14 and the anti-oxidation layer 15 , and the attachment method of the second adhesion layer 21 and the third bonding layer 22 will be described later.

The first bonding layer 13 and the third bonding layer 22 are made of the same material, and the melting point of the first bonding layer 13 is higher than the melting point of the second bonding layer 14 .

When the first bonding layer 13 and the third bonding layer 22 are both made of silver, the second bonding layer 14 is made of indium, that is, the first bonding layer 13 and the third bonding layer 22 are both silver bonding layers, and the second bonding layer 14 is an indium bonding layer.

When the first bonding layer 13 and the third bonding layer 22 are both made of gold, the second bonding layer 14 is made of tin, that is, the first bonding layer 13 and the third bonding layer 22 are both gold bonding layers, and the second bonding layer 14 is a tin bonding layer.

When the first bonding layer 13 and the third bonding layer 22 are both made of copper, the second bonding layer 14 is made of tin, that is, the first bonding layer 13 and the third bonding layer 22 are both copper bonding layers, and the second bonding layer 14 is a tin bonding layer.

That is, a total of three bonding material systems are included but not limited to, and the three bonding material systems are: silver and indium, gold and tin, and copper and tin.

It should be noted that, for ease of description, the following text uses a bonding material system of silver and indium as an example, that is, the first bonding layer 13 and the third bonding layer 22 are both made of silver, and the second bonding layer 14 is made of indium.

Step 120, placing the electronic components into the tube shell, and placing the covering surface of the semiconductor wafer cover plate on the open end surface so that the anti-oxidation layer contacts the third bonding layer.

In the process of bonding and packaging the tube shell 1 and the semiconductor wafer cover plate 2, the tube shell 1 and the semiconductor wafer cover plate 2 need to be fixed by means of the packaging platform 3 to ensure the packaging accuracy.

As shown in FIG5 , the packaging platform 3 includes: a sample stage 31 , a spring clamp 32 , a three-axis displacement platform 33 and a base 34 ; the sample stage 31 is connected to the base 34 via the three-axis displacement platform 33 , and a groove is provided on the sample stage 31 , which is adapted to the tube shell 1 .

Place the tube shell 1 into the groove to fix the tube shell 1; cover the covering surface of the semiconductor wafer cover plate 2 on the open end surface of the tube shell 1, and the transparent pressing plate 35 on the spring clamp 32 presses the semiconductor wafer cover plate 2 against the opening of the tube shell 1, so that the semiconductor wafer cover plate 2 abuts against the opening of the tube shell 1 to avoid relative movement between the semiconductor wafer cover plate 2 and the tube shell 1.

In the subsequent packaging process, since the laser needs to transmit the transparent pressure plate 35 and irradiate the semiconductor wafer cover 2, the transparent pressure plate 35 needs to have a high transmittance, and the material of the transparent pressure plate 35 can be selected as alumina; the applicant discovered during the research and development process that the transmittance of the alumina material for the laser with a wavelength of 980nm can reach more than 80%.

Step 130, determine the laser bonding path according to the opening of the tube shell, turn on the ultrasonic generator to drive the tube shell and the semiconductor wafer cover to vibrate; control the laser emitted by the laser generator to move along the laser bonding path on the semiconductor wafer cover.

As shown in FIG6 , an ultrasonic generating device 4 is arranged on the side of the base 34 away from the sample stage 31. The ultrasonic generating device 4 includes a generator, a transducer and a mold. The generator is used to convert 220V AC power into a high-frequency AC signal to drive the transducer to work. The transducer is used to convert the high-frequency AC signal into mechanical vibration, i.e., ultrasonic wave and transmit it to the mold. The mold transmits the ultrasonic wave to the base 34, thereby driving the entire packaging platform 3, the tube shell 1 and the semiconductor wafer cover plate 2 to vibrate synchronously.

During the packaging process, the laser needs to be irradiated vertically on the opening of the tube shell 1 and move around the opening of the tube shell 1. If the shape of the opening of the tube shell 1 is a square, the path of the laser movement is also a square, that is, the shape of the opening of the tube shell 1 can represent the path of the laser movement, thereby determining the laser bonding path through the opening.

As shown in FIG7 , while the tube shell 1 and the semiconductor wafer cover plate 2 are vibrated at high frequency by ultrasound, the laser moves along the laser bonding path. The heat of the laser melts the indium bonding layer with a lower melting point, and generates an intermetallic compound (IMC) Ag ₂ In with the silver bonding layer with a higher melting point. Ag ₂ In forms an Ag ₂ In layer 6, thereby forming an Ag-Ag ₂ In-Ag interface structure to achieve transient liquid phase bonding, thereby achieving airtight packaging of the tube shell 1 and the semiconductor wafer cover plate 2. The melting point of Ag ₂ In is higher than 700 degrees Celsius, so that the bonding joint formed by the Ag ₂ In layer 6 has good high temperature resistance.

Among them, the use of laser as a heat source for transient liquid phase bonding has the advantage that the energy of the laser is highly concentrated. When the laser moves along the laser bonding path, it can selectively heat the local interconnection area to increase the temperature of the bonding area to above the melting point of the material within a few seconds, while the temperature of other parts except the interconnection area is basically maintained at the initial temperature. While ensuring the bonding connection between the materials, it can prevent heat transfer, thereby avoiding damage to the thermosensitive elements in the tube shell 1 caused by high temperature during the bonding process. Another feature of laser bonding is that a vertical thermal gradient is formed between the bonding material and the base material of the tube shell, which reduces the thermal warping of electronic components due to thermal stress during the bonding process and improves the stability and reliability of the package.

During the research and development process, the applicant discovered that using laser as a heat source to heat the intermediate layer material of the glass frit can achieve airtight packaging of ceramic and kovar alloy heterogeneous materials; similarly, using laser to heat metal solder can achieve wafer-level packaging. Therefore, the solution of introducing laser as a bonding heat source is feasible.

During the laser heating process, ultrasound is introduced into the transient liquid phase bonding reaction process, which accelerates the reaction process, shortens the reaction time, and improves the packaging efficiency.

The transient liquid phase bonding process achieves effective connection between materials by melting low-melting point materials and forming intermetallic compounds with high-melting point materials; the formation and evolution of intermetallic compounds of each phase are the decisive factors affecting the strength and performance of the bonded joint. However, due to the instantaneous and highly concentrated nature of the laser heat source, the bonded joint in the traditional laser bonding process will cool and solidify within a few seconds after the heating is stopped, which greatly limits the metallurgical process in the joint, and the element diffusion and recrystallization are forced to be interrupted, which is not conducive to the formation of intermetallic compound components with good comprehensive properties such as homogeneity, fine grains and mechanical strength; therefore, in order to ensure that the metallurgical reaction process in the transient liquid phase process joint with laser as the heat source can be completed within seconds, the present application introduces an ultrasonic process to accelerate the element diffusion rate while utilizing laser heating, thereby ensuring the strength and density of the bonded joint to obtain an airtight package.

Among them, the principle of ultrasound accelerating the reaction process is that when ultrasound acts on the solid-liquid interface, extremely high tensile stress will be generated inside the liquid. When the value of the tensile stress exceeds the surface tension of the liquid, the liquid will rupture to form tiny bubbles. The bubbles will nucleate, grow and explode in a very short time, forming a negative pressure of several thousand atmospheres inside, causing the surrounding liquid to rush into the ruptured bubbles at a very fast speed to form microjets. Since most bubbles are formed at the solid-liquid interface and the direction of microbubble collapse is perpendicular to the solid-liquid interface, the direction of the microjets is also perpendicular to the solid-liquid interface. The movement of the microjets forms a strong impact force on the solid-liquid interface, which can break the oxide film on the surface of the solid material and even break the material itself, allowing more substances to participate in the reaction. In addition, the temperature at the center of the bubble can reach several thousand K. The impact and high temperature of the microjets cause the interface of the solid material to be "etched". This material interface etching phenomenon caused by ultrasound is called "acoustic erosion". The acoustic erosion effect greatly accelerates the reaction process.

With respect to silver-indium transient liquid phase materials, the applicant discovered during the research and development process that a spinodal decomposition Ag ₃ In-Ag ₂ In IMC spinodal structure has almost no holes inside compared to other IMC components, thereby ensuring the airtightness of the bonding joint; however, the formation of the bonding joint requires the element diffusion and solidification process at a second scale; therefore, in order to achieve airtight packaging of the thermosensitive element, the ultrasonic and laser bonding processes are simultaneously introduced into the transient liquid bonding process, which can generate a Ag ₃ In-Ag ₂ In IMC spinodal structure with better performance, further ensuring the reliability of the bonding joint.

The micro-connection process shown in this embodiment uses laser as the heat source of transient liquid phase bonding and introduces ultrasound into the reaction process of transient liquid phase bonding. While ensuring the performance of electronic components, it accelerates the reaction process of transient liquid phase bonding and improves the stability, reliability and efficiency of electronic component packaging. The micro-connection process based on laser ultrasonic coupling has good adaptability and is particularly suitable for applications in the fields of thermosensitive components, infrared detectors and wafer-level airtight packaging.

It should be noted that the vibration amplitude of the packaging platform 3 under the action of ultrasound is small. Therefore, it can be considered that the tube shell 1 and the semiconductor wafer cover plate 2 will not cause a large deviation to the laser bonding path during the vibration process, that is, the laser is always located on the laser bonding path during the movement.

Furthermore, the vibration direction can be kept consistent with the moving direction of the laser, thereby avoiding the deviation of the laser bonding path due to vibration; taking the laser bonding path as a square as an example, when the laser moves along the edge of the square in the X-axis direction, the packaging platform 3 can be controlled to vibrate along the X-axis direction to avoid the deviation of the laser bonding path in the Y-axis direction; when the laser moves along the edge of the square in the Y-axis direction, the packaging platform 3 can be controlled to vibrate along the Y-axis direction to avoid the deviation of the laser bonding path in the X-axis direction.

Before using laser heating, it is necessary to calibrate the relative position between the sample stage 31 and the laser generator 5. A CCD industrial camera can be set on the laser generator 5. The CCD industrial camera can emit multiple sets of cross alignment lines. With the assistance of the LCD screen, the operator adjusts the position of the sample stage 31 through the three-axis displacement platform 33.

The three-axis displacement platform 33 includes a first handle 331, a second handle 332 and a third handle 333. The first handle 331 is used to drive the sample stage 31 to move in the X-axis direction, the second handle 332 is used to drive the sample stage 31 to move in the Y-axis direction, and the third handle 333 is used to drive the sample stage 31 to rotate around the Z-axis. The first handle 331, the second handle 332 and the third handle 333 drive the sample stage 31 to move or rotate by a screw drive.

It is known from common knowledge that the energy of the laser spot is the highest at the center, and the energy decreases as the distance from the center increases.

Therefore, the applicant conducted a quantitative analysis of various parameters affecting laser energy during the research and development process.

The calculation formula of laser heat flux F is as follows:

Where _PL is the laser power, _RL is the laser radius, _RF is the distance between any point in the laser spot and the center of the spot, and _Ab is the absorptivity factor.

Considering that the scattering phenomenon of laser light will cause a part of laser energy to be lost, an absorption factor A _b is introduced into the above formula. In this embodiment, A _b = 0.6.

The formula for calculating _RF is as follows:

Wherein, x is the abscissa of the point to be calculated in the laser spot, y is the ordinate of the point to be calculated in the laser spot, _xC is the abscissa of the center of the laser spot, and _yC is the ordinate of the center of the laser spot.

It can be seen from the calculation formula of the laser heat flux F that the laser radius _RL and the laser power _PL are the two major factors that affect the laser energy; at the same time, when the laser is used as the bonding heat source of the transient liquid phase, the moving speed of the laser along the laser bonding path will also affect the total energy of the laser input during the bonding process. Therefore, in the process of transient liquid phase bonding using the laser, the laser parameters are adjusted by controlling the laser radius, the laser power and the moving speed of the laser, so as to reduce the total energy of the laser input as much as possible under the condition that the second bonding layer with a lower melting point can be melted, thereby controlling the heat transfer and reducing the damage to the thermal sensitive element in the tube shell 1.

The following describes a method for manufacturing the first metallization layer on the tube shell 1 and the second metallization layer on the semiconductor wafer cover plate 2 in conjunction with FIG. 3 and FIG. 4 .

A first adhesion layer 11 with a thickness ranging from 1.9 microns to 2.1 microns is deposited on the open end surface of the tube shell 1 by electron beam evaporation process; the specific thickness of the first adhesion layer 11 can be 1.9 microns, 1.95 microns, 2 microns, 2.05 microns or 2.1 microns, preferably 2 microns; wherein the first adhesion layer 11 is a nickel adhesion layer, that is, the material of the first adhesion layer 11 is nickel.

Specifically, depositing the first adhesion layer 11 on the open end surface is beneficial to the subsequent electroplating deposition of the seed layer 12. At the same time, the first adhesion layer 11 can also inhibit the material of the seed layer 12 from diffusing into the tube shell 1, that is, the first adhesion layer 11 has both adhesion and diffusion blocking effects.

After the first adhesion layer 11 is produced, a seed layer 12 with a thickness ranging from 2.85 microns to 3.15 microns is electroplated on the first adhesion layer 12; the specific thickness of the seed layer 12 can be 2.85 microns, 2.9 microns, 3 microns, 3.1 microns or 3.15 microns, preferably 3 microns; wherein the seed layer 12 is a gold seed layer, that is, the material of the seed layer 12 is gold.

Specifically, by electroplating the seed layer 12 on the first adhesion layer 11 , the mechanical strength of the bonding joint after bonding can be improved, and cracks and porosity can be reduced, thereby ensuring the reliability of the package.

After the seed layer 12 is produced, a first bonding layer 13 with a thickness ranging from 2.85 microns to 3.15 microns is electroplated on the seed layer 12; the specific thickness of the first bonding layer 13 can be 2.85 microns, 2.9 microns, 3 microns, 3.1 microns or 3.15 microns, preferably 3 microns.

After the first bonding layer 13 is manufactured, a second bonding layer 14 with a thickness ranging from 1.9 microns to 2.1 microns is electroplated on the first bonding layer 13; the specific thickness of the second bonding layer 14 can be 1.9 microns, 1.95 microns, 2 microns, 2.05 microns or 2.1 microns, preferably 2 microns.

For the bonding material system of silver and indium, the applicant has verified through experiments that effective bonding can be achieved as long as the temperature reaches above 180 degrees Celsius. Compared with the existing hot pressing bonding with a process temperature of more than 300 degrees Celsius, this embodiment can achieve bonding at a relatively low temperature, thereby reducing damage to the thermal sensitive components in the tube shell 1.

After the second bonding layer 14 is completed, an anti-oxidation layer 15 with a thickness ranging from 0.027 microns to 0.033 microns is electroplated on the second bonding layer 14; the specific thickness of the anti-oxidation layer 15 can be 0.027 microns, 0.028 microns, 0.03 microns, 0.032 microns or 0.033 microns, preferably 0.03 microns; wherein the material of the anti-oxidation layer 15 is the same as the material of the first bonding layer 13, and for the bonding material system of silver and indium, the material of the anti-oxidation layer is silver.

Specifically, since exposed indium is easily oxidized by air at room temperature to form an indium oxide layer, and indium oxide has high thermal and chemical stability, the indium oxide layer is not conducive to the bonding of silver and indium. Accordingly, it will reduce the mechanical strength of the bonding joint, which is not conducive to the formation of a sealed package, and the reliability of the package is low. Therefore, a layer of silver is attached to the second bonding layer 14 to form an anti-oxidation layer 15.

Before cutting the semiconductor wafer cover on the wafer, the entire wafer needs to be double-sided polished to reduce the surface roughness, thereby facilitating the subsequent deposition of the second metallization layer; wherein the wafer is a silicon wafer.

A second adhesion layer 21 with a thickness ranging from 0.045 microns to 0.055 microns is deposited on the covering surface by an electron beam evaporation process; the thickness of the second adhesion layer 21 can specifically be 0.045 microns, 0.048 microns, 0.05 microns, 0.052 microns or 0.055 microns, preferably 0.05 microns; wherein the second adhesion layer 21 is a titanium adhesion layer, that is, the material of the second adhesion layer 21 is titanium.

Specifically, depositing the second adhesion layer 21 on the semiconductor wafer cover plate 2 is beneficial to the subsequent electroplating deposition of the third bonding layer 22 and can also inhibit the diffusion of the material of the third bonding layer 22 into the semiconductor wafer cover plate 2 .

After the second adhesion layer 21 is produced, a third bonding layer 22 with a thickness ranging from 2.85 microns to 3.15 microns is electroplated on the second adhesion layer 21; the specific thickness of the third bonding layer 22 can be 2.85 microns, 2.9 microns, 3 microns, 3.1 microns or 3.15 microns, preferably 3 microns; wherein the material of the third bonding layer 22 is the same as the material of the first bonding layer 13.

After the first metallization layer on the tube shell 1 and the second metallization layer on the semiconductor wafer cover plate 2 are manufactured, transient liquid phase bonding can be performed under the combined action of laser and ultrasonic waves to complete the packaging of electronic components.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A micro-connection process based on laser ultrasonic coupling, comprising:

a first adhesion layer, a seed layer, a first bonding layer, a second bonding layer and an oxidation resistant layer are sequentially attached to the end face of the opening of the tube shell, and a second adhesion layer and a third bonding layer are sequentially attached to the covering surface of the semiconductor wafer cover plate;

placing an electronic component into the tube shell, and covering the cover surface of the semiconductor wafer cover plate on the end surface of the opening so that the oxidation resistant layer is in contact with the third bonding layer;

determining a laser bonding path according to the opening, and starting an ultrasonic generating device to drive the tube shell and the semiconductor wafer cover plate to vibrate; controlling laser emitted by a laser generator to move along the laser bonding path on the semiconductor wafer cover plate;

the first bonding layer and the third bonding layer are made of the same material, and the melting point of the first bonding layer is higher than that of the second bonding layer.

2. The laser ultrasonic coupling-based micro-connection process according to claim 1, wherein,

the covering surface of the semiconductor wafer cover plate is covered on the end face of the opening, and the method comprises the following steps:

placing the tube shell in a groove of a packaging platform, and covering the cover surface of the semiconductor wafer cover plate on the end surface of the opening, wherein the semiconductor wafer cover plate is abutted with the end surface of the opening under the action of a transparent pressing plate on the packaging platform;

wherein, ultrasonic wave generating device locates on the encapsulation platform.

3. The laser ultrasonic coupling-based micro-connection process according to claim 1, wherein,

the first adhesion layer, the seed layer, the first bonding layer, the second bonding layer and the antioxidation layer are sequentially attached to the end face of the opening of the tube shell, and the antioxidation layer comprises:

depositing the first adhesion layer on the end face by an electron beam evaporation process to a thickness in a range of 1.9 micrometers to 2.1 micrometers;

wherein the first adhesion layer is a nickel adhesion layer.

4. The laser ultrasonic coupling-based micro-connection process according to claim 1, wherein,

the first adhesion layer, the seed layer, the first bonding layer, the second bonding layer and the antioxidation layer are sequentially attached to the end face of the opening of the tube shell, and the device further comprises:

electroplating the seed layer having a thickness in the range of 2.85 micrometers to 3.15 micrometers over the first adhesion layer;

wherein the seed layer is a gold seed layer.

5. The laser ultrasonic coupling-based micro-connection process according to claim 1, wherein,

the first adhesion layer, the seed layer, the first bonding layer, the second bonding layer and the antioxidation layer are sequentially attached to the end face of the opening of the tube shell, and the device further comprises:

electroplating the first bonding layer having a thickness in the range of 2.85 micrometers to 3.15 micrometers over the seed layer.

6. The laser ultrasonic coupling-based micro-connection process according to claim 1, wherein,

the first adhesion layer, the seed layer, the first bonding layer, the second bonding layer and the antioxidation layer are sequentially attached to the end face of the opening of the tube shell, and the device further comprises:

electroplating the second bonding layer having a thickness in the range of 1.9 micrometers to 2.1 micrometers over the first bonding layer.

7. The laser ultrasonic coupling-based micro-connection process according to claim 1, wherein,

the first adhesion layer, the seed layer, the first bonding layer, the second bonding layer and the antioxidation layer are sequentially attached to the end face of the opening of the tube shell, and the device further comprises:

electroplating the oxidation-resistant layer having a thickness in the range of 0.027 microns to 0.033 microns over the second bonding layer;

wherein, the material of the antioxidation layer is the same as the material of the first bonding layer.

8. The laser ultrasonic coupling-based micro-connection process according to claim 1, wherein,

the method for sequentially attaching the second adhesion layer and the third bonding layer on the covering surface of the semiconductor wafer cover plate comprises the following steps:

depositing the second adhesion layer on the capping surface by an electron beam evaporation process to a thickness in the range of 0.045 micrometers to 0.055 micrometers;

wherein the second adhesion layer is a titanium adhesion layer.

9. The laser ultrasonic coupling-based micro-connection process according to claim 1, wherein,

the second adhesion layer and the third bonding layer are sequentially attached to the covering surface of the semiconductor wafer cover plate, and the method further comprises the following steps:

and electroplating the third bonding layer having a thickness ranging from 2.85 micrometers to 3.15 micrometers on the second adhesive layer.

10. The micro-connection process based on laser ultrasonic coupling according to any one of claims 1 to 9, wherein,

the first bonding layer and the third bonding layer are silver bonding layers, and the second bonding layer is an indium bonding layer;

or, the first bonding layer and the third bonding layer are both gold bonding layers, and the second bonding layer is a tin bonding layer;

or, the first bonding layer and the third bonding layer are copper bonding layers, and the second bonding layer is a tin bonding layer.