1. A construction method of a TSV electroplating filling additive constitutive model is characterized by specifically comprising the following steps:

s1, preprocessing the electrode; preparing electroplating base liquid and an additive to be tested, and injecting the diluted electroplating base liquid into a five-port electrolytic cell;

s2, connecting an electrolytic cell circuit, and measuring the current-time curve of the electroplating base liquid before and after the additive is added by adopting a chrono-amperometry method under the action of different potentials;

s3, carrying out normalization processing on the current density according to the current-time curve to obtain the coverage rate of the additive;

and S4, fitting the change rule of the coverage rate of the additive with the concentration of the additive under different potentials, and constructing a constitutive equation according to the adsorption kinetics of the additive.

2. The method of constructing a TSV electroplated fill additive constitutive model as claimed in claim 1, wherein the additive includes an inhibitor, a leveler and an accelerator.

3. The method for constructing the TSV electroplated filler additive constitutive model as claimed in claim 1, wherein the step S1 of preprocessing the electrode specifically includes:

polishing the electrode to remove an oxide layer on the surface of the electrode; and (4) carrying out ultrasonic cleaning, absolute ethyl alcohol soaking and ultrasonic cleaning on the polished electrode in sequence to obtain the pretreated electrode.

4. The method for constructing the TSV electroplated filler additive constitutive model as claimed in claim 1, wherein the potentials in the step S2 are set to 0.5V, 0.53V, 0.55V and 0.6V.

5. The method for constructing the TSV electroplated filler additive constitutive model as claimed in claim 1, wherein the step S3 specifically includes:

according to the Butler-Walmer equation, the change of the cathode surface current density reflects the coverage rate of the additive;

measuring the current density J of the electroplating base solution before the additive is injected by chronoamperometry₀And current density J of the plating solution after the injection of the additive_addDefining the change J in current density of the plating solution after the addition of the additive_add-J₀Current density J of electroplating base liquid before injecting additive₀Is normalized current density J_NFor characterizing the coverage of additives

6. The method for constructing the constitutive model of the TSV electroplating filling additive according to claim 1, wherein the constitutive equation constructed according to adsorption kinetics of the additive is as follows:

the above-mentionedIs the concentration of the additive in the bulk solution, θ_addIs the local coverage of the additive(s),is the saturation coverage of the additive, K_addIs the adsorption coefficient of the additive; gamma ray_addIs the consumption coefficient of the additive.

7. A construction system of a TSV electroplating filling additive constitutive model is characterized by comprising rotary disc electrode equipment, an electrochemical workstation, a computer, five-port electrolytic tanks, a platinum counter electrode, a silver reference electrode and a silver chloride reference electrode;

the rotating disc motor equipment, the electrochemical workstation, the five-port electrolytic tank, the platinum counter electrode and the silver and silver chloride reference electrode form an electrochemical workstation-rotating disc electrode measuring system which is used for measuring the current densities of additives with different concentrations under the action of different potentials;

and the computer is used for acquiring detection data of the electrochemical workstation-rotating disk electrode measuring system and constructing a constitutive equation of the additive through mathematical modeling and data fitting.

Background

Integrated circuit technology is rapidly evolving with moore's law, and higher circuit integration densities have led to higher interconnect densities. Stacking and integrating chips with different functions (such as a memory, a processor and the like) into a three-dimensional integrated package of a multifunctional system becomes a necessary choice for improving the performance and the cost performance of the device.

One scheme of three-dimensional integration adopts a large number of high-density TSVs (Through Silicon vias) penetrating Through a Silicon substrate, so that vertical up-and-down interconnection between stacked chips is realized, high-density three-dimensional integration is formed, and numerous advantages of high density, multiple functions and small size are brought. The TSV electroplating filling process is an important process for determining the TSV three-dimensional integration cost and accounts for about 26% -40% of the total production cost. Due to the current density concentration at the position of the TSV hole in the electroplating process, the growth speed of deposited copper at the TSV hole is higher than that at the bottom, and a clamping opening is formed. The additive becomes an essential component of the TSV plating solution in order to inhibit the growth of pore-bottom deposited copper and promote the growth of pore-bottom deposited copper.

The physical behavior of the additive during the TSV electroplating filling process is complex. The material transmission of the additive from the bulk solution to the cathode surface comprises various physical behaviors such as diffusion, convection, electromigration and the like; the additive on the surface of the cathode needs to undergo physical processes such as adsorption, desorption, consumption and the like; and there is an interaction between the different additives.

Due to the complexity of the action of the additive in the TSV electroplating filling process, constructing the constitutive equation of the additive is particularly important for clarifying the action mechanism of the additive, optimizing process parameters and developing a more effective novel additive. At present, on one hand, the academic circles mainly guess the constitutive equation of the additive according to theoretical formulas of physical processes such as diffusion, adsorption and the like, and reversely verify the additive through TSV filling experiment results, so that the constitutive equation is continuously optimized. The method has the advantages of large experimental workload, high cost and low reliability. On the other hand, because of no reliable and targeted guidance of the constitutive model, the industry often finds the optimal concentration ratio of the additives in the electroplating solution and the optimal electroplating process parameters by an empirical test method, which is time-consuming, high in cost and low in accuracy.

Disclosure of Invention

Based on the technical problem, the invention provides a method and a system for developing a TSV electroplating filling additive constitutive model, wherein an amperometric method is adopted, the influence of additives with different concentrations on current density under the action of different potentials is researched through an electrochemical workstation-rotating disk electrode measuring system, and a constitutive equation of the additives is constructed through mathematical modeling and data fitting.

The invention provides a method for constructing a TSV electroplating filling additive constitutive model, which specifically comprises the following steps:

s1, preprocessing the electrode; preparing electroplating base liquid and an additive to be tested, and injecting the diluted electroplating base liquid into a five-port electrolytic cell;

s2, connecting an electrolytic cell circuit, and measuring the current-time curve of the electroplating base liquid before and after the additive is added by adopting a chrono-amperometry method under the action of different potentials;

s3, carrying out normalization processing on the current density according to the current-time curve to obtain the coverage rate of the additive;

and S4, fitting the change rule of the coverage rate of the additive with the concentration of the additive under different potentials, and constructing a constitutive equation according to the adsorption kinetics of the additive.

Further, the additives include inhibitors, levelers, and accelerators.

Further, the step S1 of preprocessing the electrode specifically includes:

polishing the electrode to remove an oxide layer on the surface of the electrode; and (4) carrying out ultrasonic cleaning, absolute ethyl alcohol soaking and ultrasonic cleaning on the polished electrode in sequence to obtain the pretreated electrode.

Further, the potentials in the step S2 are set to 0.5V, 0.53V, 0.55V, and 0.6V.

Further, the step S3 specifically includes:

according to the Butler-Walmer equation, the change of the cathode surface current density reflects the coverage rate of the additive;

measuring the current density J of the electroplating base solution before the additive is injected by chronoamperometry₀And current density J of the plating solution after the injection of the additive_addDefining the change J in current density of the plating solution after the addition of the additive_add-J₀Current density J of electroplating base liquid before injecting additive₀Is normalized current density J_NFor characterizing the coverage of additives

Further, the constitutive equation is constructed according to the adsorption kinetics of the additive:

the above-mentionedRepresents the concentration of the additive in the bulk solution, θ_addRepresents the local coverage of the additive,represents the saturation coverage of the additive, K_addRepresents the adsorption coefficient of the additive; gamma ray_addIs gamma_addIs the consumption coefficient of the additive, is the mathematical deformation of an additive adsorption kinetic equation according to a fitted curve equation,

based on the same invention concept, the invention also provides a construction system of the TSV electroplating filling additive constitutive model, and the construction system specifically comprises rotary disc electrode equipment, an electrochemical workstation, a computer, five-port electrolytic tanks, platinum counter electrodes and silver chloride reference electrodes;

the rotating disc motor equipment, the electrochemical workstation, the five-port electrolytic tank, the platinum counter electrode and the silver and silver chloride reference electrode form an electrochemical workstation-rotating disc electrode measuring system which is used for measuring the current densities of additives with different concentrations under the action of different potentials;

and the computer is used for acquiring detection data of the electrochemical workstation-rotating disk electrode measuring system and constructing a constitutive equation of the additive through mathematical modeling and data fitting.

Has the advantages that:

(1) the invention provides a method for developing an additive constitutive model by data fitting based on experimental sample data, sample data measured by a scientific electrochemical measurement experiment is real and accurate, and the constitutive model obtained by fitting a large amount of sample data is scientific and rigorous. Compared with a feedback optimization modeling method, the experimental method based on electrochemical measurement has the advantages of simpler experimental steps and lower cost; the constitutive equation obtained by fitting based on a large amount of sample data has higher reliability; and the data fitting is more intuitive and scientific.

(2) The invention provides a model method for representing inhibitor coverage rate by using normalized current density, so that the microscopic parameter of the additive coverage rate can be accurately and intuitively measured by an experimental means, and the obtained constitutive equation

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a flowchart of a method for constructing a TSV electroplating filling additive constitutive model according to an embodiment of the present invention;

FIG. 2 is a graph of current versus time before and after inhibitor injection into an electroplating base solution according to an embodiment of the present invention;

FIG. 3 is a graph showing current-time curves before and after a leveling agent is injected into an electroplating base solution according to an embodiment of the present invention;

FIG. 4 is a graph of current versus time before and after an accelerator is injected into an electroplating base solution according to an embodiment of the present invention;

FIG. 5 is a graph of normalized current density as a function of inhibitor concentration at various potentials provided by an example of the present invention;

FIG. 6 is a graph of normalized current density as a function of leveler concentration at different potentials provided by an embodiment of the present invention;

FIG. 7 is a graph of normalized current density as a function of accelerator concentration for various potentials provided by an embodiment of the present invention;

FIG. 8 is a graph of inhibitor coverage as a function of concentration at various potentials provided by an example of the present invention;

FIG. 9 is a graph of leveler coverage as a function of leveler concentration at different potentials provided by an embodiment of the present invention;

FIG. 10 is a graph of accelerator coverage as a function of concentration for different potentials provided by an embodiment of the present invention;

fig. 11 is a schematic structural diagram of a system for constructing a TSV electroplating filling additive constitutive model according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, in the embodiment of the present invention, a flow chart of a method for constructing a TSV electroplating filling additive constitutive model is provided, which specifically includes the following steps:

step S101, preprocessing an electrode; and preparing electroplating base liquid and an additive to be tested, and injecting the diluted electroplating base liquid into a five-port electrolytic cell.

In the embodiment of the invention, the electrode pretreatment comprises polishing and cleaning of the electrode to ensure good conductivity of the electrode, and firstly, the electrode is polished by using polishing cloth to remove an oxide layer on the surface of the electrode. Then, ultrasonic cleaning is carried out, and secondary ultrasonic cleaning is carried out after the electrode is soaked in absolute ethyl alcohol, so that impurities and stains on the surface of the electrode are removed. Then 100mL of electroplating base liquid diluted by deionized water is injected into the five-port electrolytic tank, wherein the model of the electroplating base liquid is SYS 2510. The purpose of diluting the electroplating base liquid is to reduce the reaction speed of the additive, thereby slowing down the change process of the current density and facilitating the measurement. Next, a corresponding volume of additive was prepared in the syringe according to the concentration of the desired test additive.

And S102, connecting an electrolytic cell circuit, and measuring the current-time curve of the electroplating base liquid before and after the additive is added by adopting a chronoamperometry method under the action of different potentials.

In the embodiment of the invention, the additives comprise an inhibitor, a leveling agent and an accelerator, and particularly adopt an inhibitor UPT33 3320S, an accelerator UPT3320A and a leveling agent UPT 3320L. The current-time curves before and after the injection of 0mL, 0.1mL, 0.2mL, 0.3mL, 0.4mL, 0.5mL, 0.6mL, 0.8mL and 1.0mL of the inhibitor in 100mL of the plating base solution were measured by chronoamperometry at potentials of 0.5V, 0.53V, 0.55V and 0.6V, respectively, for the inhibitor, and specific applied potentials and the concentrations of the inhibitor added are shown in table 1. The current-time curves before and after the plating base solution was injected with the inhibitor are shown in FIG. 2, wherein J₀Current density representing equilibrium state of the plating solution before inhibitor injection, J_suppRepresenting the current density of the bath equilibrium state after inhibitor injection.

TABLE 1 correspondence table of applied potential and inhibitor addition concentration

For leveling agents, 100mL of plating base solution was measured by chronoamperometry at potentials of 0.5V, 0.53V, 0.55V and 0.6V, respectivelyThe current-time curves before and after the injection of 0mL, 0.4mL, 0.8mL, 1.2mL, 1.6mL, 2.0mL, 2.4mL, 2.8mL, and 3.2mL of leveling agent, respectively, and the specific applied potentials and the concentrations of leveling agent added are shown in Table 2. The current-time curves before and after the plating base solution is injected with the leveler are shown in FIG. 3, wherein J₀Current density representing equilibrium state of the plating solution before leveling agent injection, J_leveRepresenting the current density of the bath equilibrium state after the leveler is injected.

TABLE 2 correspondence table of applied potential and leveling agent addition concentration

Applying an electric potential (V)	Inhibitor concentration (ml/L)
		-0.6	0,4,8,12,16,20,24,28,32
0.55	0,4,8,12,16,20,24,28,32
		-0.53	0,4,8,12,16,20,24,28,32
-0.5	0,4,8,12,16,20,24,28,32

With respect to the accelerator, current-time curves before and after the injection of 0mL, 0.2mL, 0.4mL, 0.5mL, 0.6mL, 0.8mL, 1.0mL and 1.2mL of the accelerator into 100mL of the plating base solution were measured by chronoamperometry at potentials of 0.5V, 0.55V and 0.6V, respectively, and specific applied potentials and the addition concentrations of the accelerator are shown in table 3. Electroplating baseThe current-time curves before and after the base liquid is injected with the accelerator are shown in FIG. 4, wherein J₀Current density representing equilibrium state of the plating solution before accelerator injection, J_accRepresenting the current density of the bath equilibrium state after the accelerator is injected.

TABLE 3 correspondence table of applied potential and accelerator addition concentration

And S103, carrying out normalization processing on the current density according to the current-time curve to obtain the coverage rate of the additive.

In the embodiment of the invention, in the TSV copper plating filling process, the additive is adsorbed on the surface of the cathode, so that the current density distribution on the surface of the cathode is influenced. Defining the surface area of the cathode as S and the adsorption area of the additive as S_addFree surface area of S_freeThe coverage of the additive is shown in equation (1).

According to the Butler-Volmer equation, the change in the cathode surface current density reflects the coverage of the additive as shown in equation (2). The current density (J) of the plating base liquid before the injection of the additive was measured by chronoamperometry₀) And current density (J) of the plating solution after the injection of the additive_add) Defining the change in current density of the plating solution after addition of the additive (J)_add-J₀) And current density (J) of plating base solution before injection of additive₀) Is normalized current density (J)_N) And is used to characterize the coverage of the inhibitor, as shown in equation (3).

θ_add＝J_N＝(J_add-J₀)/J₀ (3)

The normalized current densities of the plating base solutions injected with different concentrations of the suppressor, leveler, and accelerator at different potentials are shown in fig. 5, 6, and 7.

And S4, fitting the change rule of the coverage rate of the additive with the concentration of the additive under different potentials, and constructing a constitutive equation according to the adsorption kinetics of the additive.

In the embodiment of the invention, the change rule of the normalized current density along with the concentration of the additive after the additive is injected into the electroplating base liquid at different potentials is measured by a mathematical fitting experiment, and the change curves of the coverage rates of the inhibitor, the leveling agent and the accelerator along with the concentration are respectively shown in fig. 8, fig. 9 and fig. 10.

And (3) constructing a constitutive model of the additive according to a fitted curve equation and combining the adsorption kinetic process of the additive on the surface of the cathode, wherein the constitutive model is shown in formula (4). Wherein the content of the first and second substances,represents the concentration of the additive in the bulk solution, θ_addRepresents the local coverage of the additive,represents the saturation coverage of the additive, K_addRepresenting the adsorption coefficient of the additive. Gamma ray_addIs a mathematical transformation of the adsorption kinetics equation of the additive according to a fitted curve equation, as shown in equation (5). Wherein, delta_addThickness of the boundary layer representing the concentration of the additive, k_addRepresenting the consumption rate of the additive, D_addRepresenting the diffusion coefficient of the additive.

According to the method, constitutive equations of the inhibitor, the leveling agent and the accelerator under different potentials are obtained, and corresponding coefficients are shown in tables 4-6 respectively.

TABLE 4 inhibitor constitutive equation coefficients

TABLE 5 leveling agent constitutive equation coefficients

TABLE 6 Accelerator constitutive equation coefficients

According to the invention, through an electrochemical test experiment, current-time curves of the electroplating base liquid before and after the additive is added are measured by adopting a chronoamperometry method under the action of different potentials, the current density is normalized according to the current-time curves to obtain the coverage rate of the additive, and a constitutive model of the additive is constructed according to a fitted curve equation and in combination with the adsorption kinetic process of the additive on the surface of a cathode.

As shown in fig. 11, an embodiment of the present invention further provides a system for constructing a TSV electroplating filling additive constitutive model, where the constitutive model specifically includes a rotating disk electrode device, an electrochemical workstation, a computer, a five-port electrolytic cell, a platinum counter electrode, and a silver/silver chloride reference electrode.

The rotating disc motor equipment, the electrochemical workstation, the five-port electrolytic tank, the platinum counter electrode and the silver and silver chloride reference electrode form an electrochemical workstation-rotating disc electrode measuring system which is used for measuring the current densities of additives with different concentrations under the action of different potentials. In the embodiment of the invention, the electrochemical workstation-rotating disk electrode measuring system mainly comprises: a Shanghai Chenghua CHI660E electrochemical workstation, a GARY rotating disk electrode device, a computer, a platinum counter electrode, a silver-silver chloride reference electrode and a five-port electrolytic cell with the volume of 100 mL.

And the computer is used for acquiring detection data of the electrochemical workstation-rotating disk electrode measuring system and constructing a constitutive equation of the additive through mathematical modeling and data fitting.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

It should be understood that, although the steps in the flowcharts of the embodiments of the present invention are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in various embodiments may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a non-volatile computer-readable storage medium, and can include the processes of the embodiments of the methods described above when the program is executed. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.