CN114220783A - Hybrid bonding structure and preparation method thereof - Google Patents
Hybrid bonding structure and preparation method thereof Download PDFInfo
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- CN114220783A CN114220783A CN202111574515.9A CN202111574515A CN114220783A CN 114220783 A CN114220783 A CN 114220783A CN 202111574515 A CN202111574515 A CN 202111574515A CN 114220783 A CN114220783 A CN 114220783A
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L24/02—Bonding areas ; Manufacturing methods related thereto
- H01L24/07—Structure, shape, material or disposition of the bonding areas after the connecting process
- H01L24/08—Structure, shape, material or disposition of the bonding areas after the connecting process of an individual bonding area
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
- C25C1/12—Electrolytic production, recovery or refining of metals by electrolysis of solutions of copper
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/12—Semiconductors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L24/02—Bonding areas ; Manufacturing methods related thereto
- H01L24/03—Manufacturing methods
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L24/10—Bump connectors ; Manufacturing methods related thereto
- H01L24/11—Manufacturing methods
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L24/10—Bump connectors ; Manufacturing methods related thereto
- H01L24/15—Structure, shape, material or disposition of the bump connectors after the connecting process
- H01L24/16—Structure, shape, material or disposition of the bump connectors after the connecting process of an individual bump connector
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
- H01L24/81—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a bump connector
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
- H01L24/82—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected by forming build-up interconnects at chip-level, e.g. for high density interconnects [HDI]
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- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Manufacturing & Machinery (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electroplating And Plating Baths Therefor (AREA)
- Electroplating Methods And Accessories (AREA)
Abstract
The invention discloses a hybrid bonding structure and a preparation method thereof. The hybrid bonding structure comprises a first substrate and a second substrate which are oppositely arranged, wherein a first bonding layer and a second bonding layer are respectively arranged on the first substrate and the second substrate and are bonded to form a bonding interface; a copper bonding point with (110) crystal face preferred orientation is arranged in the first bonding layer and/or the second bonding layer, the copper bonding point comprises a twin crystal structure, the twin crystal structure comprises twin crystal layers, and the twin crystal layers are mainly distributed along the grain growth direction at an included angle of 45 degrees; the proportion of the crystal grains with the twin crystal sheet layer in the total number of the crystal grains at the copper bonding points is more than or equal to 50 percent, and/or the proportion of the volume of the twin crystal structure in the total volume of the copper bonding points is more than or equal to 50 percent. The mixed bonding structure can effectively improve the bonding force between chips, can ensure better electrical connection, has excellent tissue thermal stability and mechanical property of a copper bonding point, and improves the service reliability.
Description
Technical Field
The invention relates to the technical field of microelectronic packaging and integrated circuit packaging, in particular to a hybrid bonding structure and a preparation method thereof.
Background
In recent years, more and more people skilled in the field of microelectronic packaging have begun to research into emerging 2.5D or 3D packaging technologies to meet the requirements of miniaturization, high performance and high reliability of electronic products. According to the technology, two or more chips or wafers can be stacked in a bump bonding mode, and the three-dimensional arrangement of the chips is realized, so that the signal transmission distance is remarkably reduced, and high-speed transmission and low power consumption are realized. The bonding technology, one of the key technologies, is essential to ensure reliable electrical connection and mechanical support between chips.
Common bonding methods are oxide bonding, solder bonding, copper-copper bonding, organic polymer bonding, and hybrid bonding. The hybrid bonding is that the gaps between the salient points are filled by the dielectric layer and are bonded with each other at the same time of copper-copper bonding. Compared with other methods, the hybrid bonding effectively improves the bonding force between chips, and simultaneously can ensure better electrical connection, thereby having better application prospect. However, the copper bump is easily recrystallized during the thermocompression bonding process and during subsequent processes such as reflow soldering or heat treatment, so that the mechanical strength of the copper bump is reduced, thereby increasing the risk of failure of the device.
Disclosure of Invention
In view of the above problems in the prior art, the present invention is directed to a hybrid bonding structure and a method for manufacturing the same.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a hybrid bonding structure, where the hybrid bonding structure includes a first substrate and a second substrate that are arranged opposite to each other, a first bonding layer is arranged on the first substrate, a second bonding layer is arranged on the second substrate, and the first bonding layer and the second bonding layer are bonded to form a bonding interface;
a copper bonding point is arranged in the first bonding layer and/or the second bonding layer, the copper bonding point has (110) crystal face preferred orientation, the twin copper material comprises a twin tissue, the twin tissue comprises a twin sheet layer, and the twin sheet layer is mainly distributed along the grain growth direction with an included angle of 45 degrees; the proportion of the crystal grains with the twin crystal sheet layer in the total number of the crystal grains of the twin crystal copper material is more than or equal to 50 percent, and/or the ratio of the volume of the twin crystal tissue in the total volume of the twin crystal copper material is more than or equal to 50 percent.
In the present invention, "mainly" in "the twin lamella is mainly distributed along the 45 ° included angle in the grain growth direction" means 50% or more (for example, 52%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 92%, 95%, 96%, 98%, 99%, 100%, etc.) of the twin lamella. The included angle refers to an acute included angle of the grain growth direction of the twin crystal lamella.
In the present invention, the proportion of the crystal grains having the twin crystal layer in the total number of crystal grains of the twin crystal copper material may be, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98%, or 99%.
In the present invention, the ratio of the volume of the twin structure to the total volume of the twin copper material may be, for example, 50%, 52%, 55%, 60%, 63%, 65%, 70%, 75%, 80%, 85%, 88%, 90%, 95%, 97%, 98%, or 99%.
The hybrid bonding structure provided by the invention can effectively improve the bonding force between chips, can ensure better electrical connection, has excellent tissue thermal stability and mechanical properties (especially high-temperature mechanical properties) of copper bonding points, has high mechanical strength and toughness, and improves the service reliability.
The use of the copper bonding point with the specific composition avoids the recrystallization of the copper bonding point in the hot-pressing bonding process and the subsequent processing procedures such as reflow soldering or heat treatment, thereby solving the problems of insufficient mechanical strength, poor service reliability and the like caused by the recrystallization.
The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.
Preferably, the height of the copper bonding sites is 0.5-500 microns, such as 0.5 microns, 0.8 microns, 1 micron, 2 microns, 3 microns, 5 microns, 8 microns, 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, 60 microns, 65 microns, 70 microns, 80 microns, 90 microns, 100 microns, 115 microns, 130 microns, 140 microns, 150 microns, 160 microns, 180 microns, 200 microns, 220 microns, 240 microns, 265 microns, 280 microns, 300 microns, 320 microns, 340 microns, 350 microns, 375 microns, 385 microns, 400 microns, 405 microns, 420 microns, 450 microns, 470 microns, 480 microns, 490 microns, etc., preferably 30-300 microns, within this window where the electro-crystallized microstructure is uniformly stable, ensuring high proportion annealing crystal generation.
In the present invention, the material of the first substrate and the second substrate is not particularly limited, and the material of the first substrate and the second substrate independently includes silicon, a compound, ceramic, or glass.
As a preferred technical solution of the hybrid bonding structure of the present invention, the first bonding layer includes a dielectric layer and copper bonding points arranged in the dielectric layer at intervals, and the copper bonding points are exposed on the surface of the first bonding layer for bonding.
Preferably, the second bonding layer comprises a dielectric layer and copper bonding points arranged in the dielectric layer at intervals, and the surface copper of the second bonding layer exposes the bumps for bonding.
Preferably, the material of the dielectric layer in the first bonding layer and the material of the dielectric layer in the second bonding layer are independently selected from at least one of organic polymers or oxides, and preferably comprise benzocyclobutene, SU-8, polyimide or SiO2At least one of (1).
In a second aspect, the present invention provides a method of preparing a hybrid bonded structure as described in the first aspect, the method comprising the steps of:
(1) providing a first substrate and a second substrate, forming a first bonding layer on the first substrate, forming a second bonding layer on the second substrate, and arranging a copper bump in the first bonding layer and/or the second bonding layer, wherein the copper bump is a pre-electroplated copper material with a (111) crystal face preferred orientation;
(2) oppositely arranging the first substrate and the second substrate, carrying out hot-press bonding, and bonding the first bonding layer and the second bonding layer to form a bonding interface to obtain the mixed bonding structure;
wherein the temperature of the hot-press bonding is more than or equal to 200 ℃.
In the method of the present invention, the first substrate and the second substrate are oppositely arranged, which means that the first bonding layer on the first substrate and the second bonding layer on the second substrate are oppositely arranged.
In an alternative embodiment, the copper bumps in the first bonding layer correspond to and contact the copper bumps in the second bonding layer one to one.
In the method of the present invention, the temperature of the thermocompression bonding is 200 ℃ or more, for example, 200 ℃, 220 ℃, 240 ℃, 260 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃ or the like. The thermocompression bonding at this temperature corresponds to the annealing treatment, and the annealing twin structure (i.e., twin structure) can be continuously formed during the annealing treatment under this temperature condition.
According to the method, the arranged copper bump has certain (111) crystal face preferred orientation and a growth twin boundary parallel to the deposition direction, an annealing twin structure can be formed after hot-pressing bonding (for example, the temperature of the hot-pressing bonding is 200 ℃) to obtain a copper bonding point, the copper bonding point has (110) crystal face preferred orientation, twin crystal layers are distributed along the crystal grain growth direction at an included angle of 45 degrees, the proportion of crystal grains with the twin crystal layers in the total number of the crystal grains of the copper bonding point is more than or equal to 50%, and/or the proportion of the volume of the twin crystal structure in the total volume of the copper bonding point is more than or equal to 50%.
According to the method, a certain (111) crystal face preferred orientation is converted into a copper bonding point with a (110) crystal face preferred orientation through hot-pressing bonding treatment, the copper bonding point has excellent structure thermal stability, and within a common heat treatment temperature range (about 200 to 400 ℃) for microelectronic interconnection, abnormal growth of crystal grains is not seen along with the increase of annealing temperature, the proportion of annealing twin crystals in the crystal grains is increased, the strength and toughness of copper bumps are enhanced, so that the copper bonding point is different from a micron crystal structure and a growing twin crystal structure bump which are annealed, softened and toughened, and the unique annealing, strengthened and toughened characteristic is shown.
The method improves the structural thermal stability and high-temperature mechanical property of the bonded copper salient points (namely copper bonding points), and increases the service reliability of the hybrid bonding structure.
As a preferable embodiment of the method of the present invention, in the step (1), the first substrate and/or the second substrate is prepared according to the following method, which comprises the steps of:
(i) preparing a substrate with a conductive layer;
(ii) carrying out patterning treatment on the surface of the conducting layer of the substrate by utilizing a photoetching process, forming a photoresist pattern on the conducting layer, and exposing the conducting layer at the part without the photoresist;
(iii) filling the part without the photoresist to form a copper bump;
(iv) removing the redundant photoresist and the conducting layer;
(v) a dielectric layer is deposited and a Chemical Mechanical Polishing (CMP) process is performed on the surface of the wafer to expose the copper bumps.
Wherein the substrate in step (i) is a first substrate or a second substrate.
In the invention, the photolithography process in step (ii) is to form a pattern by exposing photoresist, the pattern refers to a region covered by the photoresist, and a region uncovered by the photoresist is subsequently used for filling and forming a copper bump, for example, a pre-plated copper material with a preferred orientation of (111) crystal plane can be formed by electroplating to serve as the copper bump.
In the present invention, the purpose of performing CMP processing on the wafer surface in step (v) is to grind away the excess dielectric layer and expose the surface of the copper bump (e.g. copper pillar), and another important role is to make the bonding surface completely coplanar and achieve the roughness requirement required for bonding.
In an alternative embodiment, the conductive layer in step (i) may be an adhesion layer obtained by vapor deposition and a seed layer; or may be a through-hole silicon (TSV) top filled with a conductive metal. Illustratively, the material of the adhesion layer may be at least one of tantalum, titanium or nitride thereof. The seed layer is made of copper. The conductive metal is copper.
In an alternative embodiment, the TSV is circular in shape and has a diameter of 15-100 microns, such as 15 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, or 100 microns, and the like.
In an alternative embodiment, each substrate contains 1 and more than one independent TSV structures arranged in a sequence on the substrate.
Preferably, the photoresist formed in step (ii) has a thickness of 1-500 microns, such as 1 micron, 3 microns, 5 microns, 8 microns, 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 60 microns, 80 microns, 100 microns, 120 microns, 130 microns, 140 microns, 150 microns, 165 microns, 180 microns, 200 microns, 220 microns, 240 microns, 260 microns, 280 microns, 300 microns, 325 microns, 350 microns, 375 microns, 400 microns, 430 microns, 460 microns, 500 microns, or the like.
The method of depositing the dielectric layer in step (v) is not particularly limited, for example, the material of the dielectric layer is Benzocyclobutene (BCB), SU-8, Polyimide (PI), etc., and the deposition method is spin coating; in another example, the dielectric layer is SiO2The deposition method is physical vapor deposition.
Preferably, the dielectric layer should be slightly thicker than the copper bumps (e.g., copper pillars).
In an alternative embodiment, in step (v), after the CMP process, the wafer is subjected to a plasma cleaning process. Through plasma cleaning treatment, the remnants generated by CMP can be eliminated, and meanwhile, the bonding surface can be activated, and the bonding difficulty is reduced.
In an alternative embodiment, the parameters of the plasma cleaning are: argon gas at 70-100sccm (e.g., 70sccm, 80sccm, 85sccm, 90sccm, or 100 sccm), oxygen at 10-50sccm (e.g., 10sccm, 20sccm, 30sccm, 40sccm, or 50 sccm), power at 500-800W (e.g., 500W, 550W, 600W, 650W, 700W, or 800W), and time at 60-600s (e.g., 60s, 80s, 100s, 125s, 150s, 160s, 180s, 200s, 220s, 260s, 300s, 320s, 350s, 400s, 425s, 450s, 480s, 500s, 550s, or 600 s).
As a preferable embodiment of the method of the present invention, in the step (1), the first substrate and/or the second substrate is prepared according to the following method, which comprises the steps of:
(I) providing a silicon substrate with a TSV structure, and filling conductive metal in the TSV;
(II) coating a dielectric layer on one surface of the silicon substrate, and windowing at the position with the TSV structure by using a photoetching process to expose the conductive metal;
(III) filling and forming a copper bump at the position where the conductive metal is exposed;
(IV) carrying out CMP treatment on the surface of the wafer;
wherein the silicon substrate in the step (I) is a first substrate or a second substrate.
The use of photolithography for windowing in step (II) of the present invention is prior art and one skilled in the art can refer to the disclosure of the prior art for performing photolithographic windowing.
In the invention, the CMP treatment is carried out on the surface of the wafer in the step (IV), so that the copper salient points and the dielectric layer can be coplanar and lower roughness can be achieved.
In an alternative embodiment, in the silicon substrate having the TSV structure provided in step (I), the TSV has a circular shape and a diameter of 15-100 microns, such as 15 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns, and the like.
In an alternative embodiment, each substrate contains 1 and more than one independent TSV structures arranged in a sequence on the substrate.
In an alternative embodiment, the conductive metal is copper.
As a preferred technical scheme of the method, the copper bump is filled by adopting a direct current electroplating technology, the pre-electroplated copper material in the step (1) is prepared by electroplating, and the electroplating method comprises the following steps:
(a) preparing plating solution
The plating solution comprises copper ions, sulfuric acid, chloride ions, an additive and water, wherein the additive comprises an inhibitor and an auxiliary agent, and the auxiliary agent is selected from at least one of organic sulfonate;
(b) direct current electroplating
And immersing the anode and the cathode serving as a conductive substrate into the plating solution, and electroplating to obtain the pre-electroplated copper material.
The optimized scheme utilizes chemical regulation and control of a pre-plating additive combination, a pre-plated copper material shows certain (111) crystal face preferred orientation and does not form a growth twin crystal with a high proportion vertical to the growth direction, the pre-plated copper material is converted into (110) crystal face preferred orientation after heat treatment (such as annealing for 1 hour) at the temperature of more than or equal to 200 ℃, and the twin crystal layer is mainly distributed along the crystal grain growth direction with an included angle of 45 degrees along with the formation of the high proportion annealing twin crystal. The crystal grains are not abnormally grown in the temperature range of common thermal compression bonding, thereby showing excellent thermal stability.
In the method, the additive combination of the pre-plating has important influence on the structure of the pre-plating material: by adding the inhibitor into the plating solution, the deposition rate can be reduced, and the coarse and incompact crystallization can be avoided; the deposition rate can be improved by adding the auxiliary agent into the plating solution, dynamic controllable desorption of the double electric layer inhibitor is realized by the competitive action of the auxiliary agent and the inhibitor, and the necessary electro-crystallization defect concentration for hatching and annealing twin crystal boundaries is introduced. Preferably, the organic sulfonate of step (a) comprises at least one of polystyrene sulfonate, polyvinyl sulfonate, alkyl sulfonate and alkyl benzene sulfonate.
Preferably, the polystyrene sulfonate and the polyethylene sulfonate independently have a molecular weight of 1000-100000, such as 1000, 3000, 5000, 8000, 10000, 12500, 15000, 17000, 20000, 25000, 35000, 40000, 50000, 60000, 70000, 80000, 100000, or the like.
Preferably, the alkyl sulfonates and alkyl benzene sulfonates have a carbon number of 12 or more, and illustratively, the carbon number may be 12, 13, 14, 15, 16, 17, 20, or the like. The alkyl sulfonate and the alkylbenzene sulfonate may have the same or different carbon numbers.
Preferably, the concentration of the adjuvant in the plating solution of step (a) is 10 to 500ppm, such as 10ppm, 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 100ppm, 150ppm, 200ppm, 230ppm, 260ppm, 300ppm, 350ppm, 400ppm, 500ppm, or the like.
Preferably, the inhibitor of step (a) is gelatin.
Preferably, the gelatin has a congealing value of 10 to 300bloom, such as 10bloom, 20bloom, 30bloom, 50bloom, 70bloom, 80bloom, 100bloom, 125bloom, 150bloom, 180bloom, 200bloom, 225bloom, 240bloom, 260bloom, 300bloom, and the like.
Preferably, the inhibitor concentration in the bath of step (a) is 5-200ppm, such as 5ppm, 10ppm, 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 100ppm, 120ppm, 150ppm, 180ppm, 200ppm, or the like.
Preferably, in step (a), the concentration of copper ions in the plating solution is 20-70g/L, such as 20g/L, 30g/L, 40g/L, 50g/L, 60g/L or 70 g/L.
Preferably, in step (a), the concentration of sulfuric acid in the plating solution is 20-200g/L, such as 20g/L, 25g/L, 30g/L, 35g/L, 40g/L, 50g/L, 60g/L, 70g/L, 80g/L, 100g/L, 120g/L, 150g/L, 160g/L, 180g/L or 200g/L, etc.
Preferably, in step (a), the concentration of chloride ions in the bath is 20-80ppm, such as 20ppm, 30ppm, 40ppm, 45ppm, 50ppm, 60ppm, 70ppm, 80ppm, or the like.
Preferably, in step (b), the anode is selected from a phosphor copper anode.
Preferably, the phosphorus content in the phosphorus copper anode is 0.03-0.075 wt.%, such as 0.03 wt.%, 0.04 wt.%, 0.05 wt.%, 0.06 wt.%, or 0.07 wt.%, etc.
Preferably, in step (b), the temperature of the plating is 20 to 50 ℃, for example, 20 ℃, 23 ℃, 25 ℃, 28 ℃, 30 ℃, 35 ℃, 40 ℃, 45 ℃ or 50 ℃, etc.
Preferably, in step (b), the electroplating is performed under constant temperature conditions.
Preferably, in step (b), the current density of the electroplating is 0.5-25A/dm2E.g. 0.5A/dm2、1A/dm2、1.5A/dm2、2A/dm2、3A/dm2、4A/dm2、5A/dm2、6A/dm2、7A/dm2Or 8A/dm2、8.5A/dm2、9A/dm2、10A/dm2、11A/dm2、12A/dm2、15A/dm2、16A/dm2、17A/dm2、18A/dm2、19A/dm2、20A/dm2、22A/dm2、23A/dm2Or 25A/dm2And the like.
Preferably, in the step (b), the electroplating time is 20-1800min, such as 20min, 30min, 40min, 60min, 80min, 90min, 120min, 150min, 180min, 200min, 240min, 280min, 300min, 350min, 450min, 500min, 550min, 600min, 700min, 800min, 850min, 900min, 1000min, 11000min, 1200min, 1250min, 1300min, 1400min, 1500min, 1600min, 1700min, or 1750 min.
Preferably, stirring is also applied to the plating solution during the electroplating in the step (b);
preferably, the agitation includes at least one of circulating jets, air agitation, magnetic agitation, and mechanical agitation.
As another preferred technical scheme of the preparation method of the invention, the temperature of the thermal compression bonding is 200-400 ℃.
Preferably, the rate of temperature rise to the temperature of the thermocompression bonding is 0.5-20 deg.C/min, such as 0.5 deg.C/min, 1 deg.C/min, 2 deg.C/min, 3 deg.C/min, 5 deg.C/min, 8 deg.C/min, 10 deg.C/min, 12 deg.C/min, 15 deg.C/min, 17 deg.C/min, or 20 deg.C/min, and the like.
Preferably, the pressure applied during the thermocompression bonding is 0.5-3MPa, such as 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa, or 3MPa, etc.
Preferably, the atmosphere of the thermocompression bonding is an inert atmosphere or vacuum. The gas in the inert atmosphere may be a mixture of one or more of nitrogen, helium, and argon, for example.
Preferably, the thermocompression bonding time is 1-2 hours, such as 1 hour, 1.2 hours, 1.5 hours, 1.7 hours, 2 hours, or the like.
Compared with the prior art, the invention has the following beneficial effects:
(1) in the mixed bonding structure provided by the invention, the copper bonding points have high proportion of annealing twin crystals and show the characteristic of annealing reinforcement, namely, the strength and toughness of the interconnection material are increased along with the increase of annealing temperature, and the copper bonding points are different from the electroplated copper bump of the general micron crystal structure which is softened by annealing, so that the overall mechanical property of the bonding interconnection structure is improved. Meanwhile, the annealing twin crystal layer has the characteristic of higher thermal stability, and the annealing twin crystal boundary proportion is not reduced and increased within the common heat treatment temperature range (about 200-400 ℃) of micro-electronic interconnection, and the crystal grains are not grown abnormally. Therefore, the technical scheme of the invention can reduce the failure risk of the bonding point in the bonding process or after multiple times of reflow and heat treatment processes, thereby enhancing the service reliability of the interconnection structure and the device.
(2) The preparation method of the hybrid bonding structure is based on copper bump electroplating filling and hot-pressing bonding technology, enhances the mechanical property of the copper bump interconnection structure only through the microstructure engineering of the electroplated copper material, has the advantages of easy operation, low cost, compatible process and the like, and is suitable for industrialized popularization in the field of microelectronic packaging.
Drawings
FIG. 1 is a flow chart of the preparation of a hybrid bond structure in one embodiment of the present invention;
FIG. 2 is a flow chart of preparing a hybrid bond structure in another embodiment of the present invention;
the multilayer structure comprises a substrate, a seed layer, a first substrate, a second substrate, a conductive layer, a second substrate, a conductive layer and a conductive layer, wherein the conductive layer comprises 01-the first substrate, 02-the composite layer of the adhesive layer and the seed layer, 03-photoresist, 04-the first copper bump, 05-a polyimide dielectric layer, 06-the second substrate, 07-the first silicon substrate, 08-conductive metal, 09-benzocyclobutene dielectric layer, 10-the second copper bump, 11-the second silicon substrate and 12-the second silicon substrate.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
Example 1
The embodiment provides a hybrid bonding structure and a preparation method thereof, as shown in fig. 1, the preparation method includes the following steps:
s1: an adhesion layer titanium and a seed layer copper are deposited on the upper surface of the first substrate 01 to form a composite layer 02 consisting of the adhesion layer and the seed, and the thicknesses of the adhesion layer and the seed layer are respectively 100nm and 400 nm.
S2: a layer of photoresist 03 with the thickness of 15 microns is coated on the upper surface of the composite layer 02 of the adhesive layer and the seed layer in a spinning mode, exposure and development are carried out, patterning is carried out on a specific position of the first substrate 01, and the composite layer 02 of the adhesive layer and the seed layer is exposed.
S3: filling the first copper bump 04 by using a direct current electroplating process, wherein the height of a plating layer of the first copper bump 04 is 15 microns;
wherein, the direct current electroplating process comprises the following steps:
(a) preparation of plating solution
The following components are adopted to prepare the electroplating solution and uniformly disperse the electroplating solution: 30g/L of copper ions, 50g/L of sulfuric acid, 30ppm of chloride ions, 100ppm of gelatin (condensation value of 200bloom), 100ppm of sodium polyvinyl sulfonate (molecular weight of 50000) and water.
(b) Direct current electroplating
A titanium plate cathode and a high-purity phosphor copper anode (with the phosphor content of 0.04 wt.%) are immersed in the plating solution, and the plating solution is controlled to be constant at the temperature of 25 ℃. Then connected into a rectifier to form a 3A/dm voltage2And (4) plating at current density.
S4: the photoresist 03 is removed using a photoresist solution, and the composite layer 02 of the adhesion layer and the seed layer is removed using a wet etching method.
S5: a polyimide dielectric layer 05 is covered on the upper surface of the first substrate 01 by using a spin coating method, the thickness of the polyimide dielectric layer 05 is 20 micrometers, and then the polyimide dielectric layer 05 is subjected to semi-curing treatment.
S6: the upper surface of the polyimide dielectric layer 05 is polished by CMP until the upper surface of the first copper bump 04 is exposed. The grinding is continued so that the first copper bump 04 and the polyimide dielectric layer 05 are coplanar and reach a lower roughness. After the CMP, the first copper bump 04 and the upper surface of the polyimide dielectric layer 05 are plasma cleaned in order to clean and activate the bonding surface. The parameters of the plasma cleaning are argon gas 70sccm, oxygen gas 20sccm, power 500W and time 360 s.
S7: the above steps are repeated on the upper surface of the second substrate 06, and then the second substrate 06 is aligned with the corresponding bonding position of the first substrate 01, and bonding between copper bumps and adhesion between dielectric layers are performed in a nitrogen atmosphere. The bonding parameters were: the heating temperature is 300 ℃, the applied pressure is 1MPa, and the heating time is 1 hour. The bonding process is also a process of annealing the first copper bump 04, so that an annealed twin structure is formed in the first copper bump 04 after the bonding is completed.
After the process is completed, the bonding point is subjected to a shear strength test and a temperature cycle test, and the result shows that the shear strength of the bonding point prepared according to the embodiment is 38MPa, and the contact resistance increase rate is less than 10% after the bonding point is cycled for 1000 times from-55 ℃ to 70 ℃.
Example 2
The embodiment provides a hybrid bonding structure and a preparation method thereof, as shown in fig. 2, the preparation method includes the following steps:
s1: a first silicon substrate 07 having a TSV structure with a diameter of 60 microns and a depth of 300 microns is prepared. The TSV is filled with conductive metal 08 made of copper.
S2: a benzocyclobutene dielectric layer 09 is coated on one surface of the first silicon substrate 07 in a spin coating mode, and the thickness of the benzocyclobutene dielectric layer 09 is 60 micrometers. A window is opened at the location having the TSV structure using photolithography techniques, exposing the surface of the conductive metal 08.
S3: electroplating the second copper bump 10 on the surface of the conductive metal 08, so that the plating height of the second copper bump 10 is 60 microns;
wherein, the electroplating process comprises the following steps:
(a) preparation of plating solution
The following components are adopted to prepare the electroplating solution and uniformly disperse the electroplating solution: 50g/L of copper ions, 150g/L of sulfuric acid, 70ppm of chloride ions, 20ppm of gelatin (the condensation value is 100bloom), 300ppm of sodium polystyrene sulfonate (the molecular weight is 40000) and water.
(b) Direct current electroplating
A titanium plate cathode and a high-purity phosphor copper anode (the phosphor content is 0.07 wt.%) are immersed in the plating solution, and the plating solution is controlled to be constant at 25 ℃. Then connecting into a rectifier to be at 6A/dm2And (4) plating at current density.
S4: since the surface of the first silicon substrate 07 has no redundant photoresist and conductive layer, CMP processing is directly performed on the upper surfaces of the second copper bump 10 and the benzocyclobutene dielectric layer 09, so that the second copper bump 10 and the benzocyclobutene dielectric layer 09 are coplanar and achieve low roughness. And after the CMP is finished, performing plasma cleaning on the upper surfaces of the second copper bump 10 and the benzocyclobutene dielectric layer 09, wherein the parameters are argon gas 60sccm, oxygen gas 30sccm, power 700W and time 180 s.
S5: the above steps are repeated for the other surface of the first silicon substrate 07, resulting in an up-down symmetrical structure.
S6: steps S1 to S4 are repeated for the second silicon substrate 11 and the second silicon substrate 12, respectively, and then the respective bonding positions of the first silicon substrate 07, the second silicon substrate 11, and the second silicon substrate 12 are aligned and bonded in a nitrogen atmosphere. The bonding parameters were: the heating temperature was 200 ℃, the applied pressure was 2MPa, and the heating time was 2 hours.
After the process is completed, the bonding point is subjected to a shear strength test and a temperature cycle test, and the result shows that the shear strength of the bonding point prepared according to the embodiment is 45MPa, and the contact resistance increase rate is less than 10% after the bonding point is cycled for 1000 times from-55 ℃ to 70 ℃.
Example 3
This example differs from example 1 in that the heating temperature in the bonding parameters was 400 ℃.
Along with the increase of the annealing temperature, the annealing twin crystal proportion is increased, crystal grains do not grow obviously, and the strength and the toughness of the salient points are improved.
After the process is completed, the bonding point is subjected to a shear strength test and a temperature cycle test, and the result shows that the shear strength of the bonding point prepared according to the embodiment is 50MPa, and the contact resistance increase rate is less than 10% after the bonding point is cycled for 1000 times from-55 ℃ to 70 ℃.
Comparative example 1
This comparative example is identical to the S1-S2 and S4-S7 procedures of example 1, except that:
the direct current electroplating process in S3 comprises the following steps:
(a) preparation of plating solution
The following components are adopted to prepare the electroplating solution and uniformly disperse the electroplating solution: 50g/L of copper ions, 100g/L of sulfuric acid, 50ppm of chloride ions, 10ppm of sodium dithiodipropyl sulfonate, 200ppm of polyethylene glycol, 20ppm of Jianna green and water.
(b) Direct current electroplating
A titanium plate cathode and a high-purity phosphor copper anode (with the phosphor content of 0.04 wt.%) are immersed in the plating solution, and the plating solution is controlled to be constant at the temperature of 25 ℃. Then connected into a rectifier to form a 3A/dm voltage2And (4) plating at current density.
2. The bonding site does not form an annealed twin structure in S7.
After the process is implemented, the shear strength test and the temperature cycle test are carried out on the bonding point, and the result shows that the shear strength of the bonding point prepared according to the comparative example is 22MPa, and the contact resistance is increased by 10-20% after the bonding point is cycled for 1000 times from-55 ℃ to 70 ℃.
In conclusion, the hybrid bonding structure provided by the invention can effectively improve the bonding force between chips and simultaneously ensure better electrical connection, and the copper bonding point has excellent tissue thermal stability and mechanical properties (especially high-temperature mechanical properties), high mechanical strength and toughness and improved service reliability.
The use of the copper bonding point with the specific composition avoids the recrystallization of the copper bonding point in the hot-pressing bonding process and the subsequent processing such as reflow soldering or heat treatment, thereby solving the problems of insufficient mechanical strength, poor service reliability and the like caused by the recrystallization.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, improvements, etc. made within the spirit and principle of the present invention should be included in the protection of the present invention.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. A hybrid bonding structure is characterized by comprising a first substrate and a second substrate which are oppositely arranged, wherein a first bonding layer is arranged on the first substrate, a second bonding layer is arranged on the second substrate, and the first bonding layer and the second bonding layer are bonded to form a bonding interface;
a copper bonding point is arranged in the first bonding layer and/or the second bonding layer, the copper bonding point has a preferred orientation of a (110) crystal plane, the copper bonding point comprises a twin crystal tissue, the twin crystal tissue comprises a twin crystal sheet layer, and the twin crystal sheet layer is mainly distributed along the grain growth direction at an included angle of 45 degrees; the proportion of the crystal grains with the twin crystal sheet layer in the total number of the crystal grains at the copper bonding points is more than or equal to 50 percent, and/or the proportion of the volume of the twin crystal structure in the total volume of the copper bonding points is more than or equal to 50 percent.
2. Hybrid bond structure as claimed in claim 1, characterized in that the height of the copper bond sites is 0.5-500 micrometers, preferably 30-300 micrometers.
3. The hybrid bond structure of claim 1 or 2, wherein the first and second substrates are independently comprised of silicon, a compound, a ceramic, or a glass.
4. The hybrid bond structure of any of claims 1-3, wherein the first bond layer comprises a dielectric layer and copper bond sites spaced within the dielectric layer, a surface of the first bond layer exposing the copper bond sites for bonding;
preferably, the second bonding layer comprises a dielectric layer and copper bonding points arranged in the dielectric layer at intervals, and the surface copper of the second bonding layer exposes the bumps for bonding.
5. The hybrid bonded structure of any of claims 1-4, wherein the material of the dielectric layer in the first bonding layer and the dielectric layer in the second bonding layer is independently selected from at least one of an organic polymer or an oxide, preferably comprises benzocyclobutene, SU-8, polyimide, or SiO2At least one of (1).
6. A method of making a hybrid bonded structure according to any of claims 1-5, comprising the steps of:
(1) providing a first substrate and a second substrate, forming a first bonding layer on the first substrate, forming a second bonding layer on the second substrate, and arranging a copper bump in the first bonding layer and/or the second bonding layer, wherein the copper bump is a pre-electroplated copper material with a (111) crystal face preferred orientation;
(2) oppositely arranging the first substrate and the second substrate, carrying out hot-press bonding, and bonding the first bonding layer and the second bonding layer to form a bonding interface to obtain the mixed bonding structure;
wherein the temperature of the hot-press bonding is more than or equal to 200 ℃.
7. The method of claim 6 wherein the pre-plated copper material of step (1) is prepared by electroplating, the electroplating method comprising the steps of:
(a) preparing plating solution
The plating solution comprises copper ions, sulfuric acid, chloride ions, an additive and water, wherein the additive comprises an inhibitor and an auxiliary agent, and the auxiliary agent is selected from at least one of organic sulfonate;
(b) direct current electroplating
And immersing the anode and the cathode serving as a conductive substrate into the plating solution, and electroplating to obtain the pre-electroplated copper material.
8. The method of claim 7, wherein the organic sulfonate of step (a) comprises at least one of polystyrene sulfonate, polyvinyl sulfonate, alkyl sulfonate, and alkyl benzene sulfonate;
preferably, the polystyrene sulfonate and the polyethylene sulfonate independently have a molecular weight of 1000-;
preferably, the carbon atom number of the alkyl sulfonate and the alkyl benzene sulfonate is more than or equal to 12;
preferably, the concentration of the adjuvant in the plating solution of step (a) is 10-500 ppm;
preferably, the inhibitor of step (a) is gelatin;
preferably, the gelatin has a congealing value of 10 to 300 bloom;
preferably, the concentration of the inhibitor in the plating solution of step (a) is 5-200 ppm.
Preferably, in the step (a), the concentration of copper ions in the plating solution is 20-70 g/L;
preferably, in the step (a), the concentration of the sulfuric acid in the plating solution is 20-200 g/L;
preferably, in step (a), the concentration of chloride ions in the plating solution is 20-80 ppm.
9. The production method according to any one of claims 6 to 8,
in step (b), the anode is selected from a phosphor copper anode;
preferably, the phosphorus content in the phosphorus copper anode is 0.03-0.075 wt.%;
preferably, in step (b), the temperature of the electroplating is 20-50 ℃;
preferably, in step (b), the electroplating is carried out under constant temperature conditions;
preferably, in step (b), the current density of the electroplating is 0.5-25A/dm2；
Preferably, in the step (b), the time of electroplating is 20-1800 min;
preferably, stirring is also applied to the plating solution during the electroplating in the step (b);
preferably, the agitation includes at least one of circulating jets, air agitation, magnetic agitation, and mechanical agitation.
10. The method according to any one of claims 6 to 9, wherein the thermal compression bonding temperature is 200 ℃ to 400 ℃;
preferably, the heating rate of heating to the temperature of the thermal compression bonding is 0.5-20 ℃/min;
preferably, in the hot-press bonding process, the applied pressure is 0.5-3 MPa;
preferably, the atmosphere of the thermocompression bonding is an inert atmosphere or vacuum;
preferably, the thermocompression bonding time is 1 to 2 hours.
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| WO2023116715A1 (en) * | 2021-12-21 | 2023-06-29 | 中国科学院深圳先进技术研究院 | Twin crystal copper material and hybrid bonding structure |
| WO2023116634A1 (en) * | 2021-12-21 | 2023-06-29 | 中国科学院深圳先进技术研究院 | Hybrid bonding structure and preparation method therefor |
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| CN114220783B (en) * | 2021-12-21 | 2024-09-17 | 中国科学院深圳先进技术研究院 | Hybrid bonding structure and preparation method thereof |
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Cited By (2)
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| WO2023116715A1 (en) * | 2021-12-21 | 2023-06-29 | 中国科学院深圳先进技术研究院 | Twin crystal copper material and hybrid bonding structure |
| WO2023116634A1 (en) * | 2021-12-21 | 2023-06-29 | 中国科学院深圳先进技术研究院 | Hybrid bonding structure and preparation method therefor |
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| CN114220783B (en) | 2024-09-17 |
| WO2023116634A1 (en) | 2023-06-29 |
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