CN110018331A - A method of characterization adatom climb and fall spreading probability ratio - Google Patents

Abstract

The invention discloses a method for characterizing the diffusion probability ratio of the increasing atoms up and down in the technical field of increasing atoms. Used to simulate surface topography, RMS and PSD spectra; S3: Obtain the protruding size data (i.e. h, s) of each rough surface; S4: Calculate the slope of the Δh/h0‑Δs/s0 line to obtain the up and down slopes under this preparation condition The diffusion probability ratio δ, the invention uses the experimental results to guide the simulation, and provides a method to characterize the diffusion probability ratio of the up-slope and up-slope of the increasing atoms by means of the unique correspondence between the surface roughness and the PSD map and the surface morphology, which is useful for further research on surface roughening. Microscopic mechanisms play a driving role. The method for characterizing the probability ratio of increasing atomic diffusion up and down slope has a simple process and high efficiency, and has wide applicability to various deposition processes, which greatly promotes the development of thin film surface technology.

Description

A method to characterize the probability ratio of up- and down-slope diffusion of augmented atoms

technical field

The invention relates to the technical field of characterizing boosting atoms, in particular to a method for characterizing the diffusion probability ratio of boosting atoms up and down slopes.

Background technique

In the process of physical vapor deposition, the phenomenon of thin film surface roughening, that is, the phenomenon that the surface roughness increases with the increase of the film thickness, is commonly found in various thin film systems such as metals, ceramics, and semiconductors. Conductivity, catalysis and energy storage are critical. In precision VLSI, the roughness at the SiO2 gate interface in transistors needs to be reduced to the atomic scale; in the field of biomedicine, in order to control the growth of cells along a fixed direction, the roughness of the substrate Ti6Al4V material needs to be increased to Above 30nm; in the field of self-cleaning, in order to obtain super-hydrophobic properties, the surface roughness of Au, SiO2 and other materials needs to reach several microns. However, due to the lack of understanding of the microscopic mechanism of surface roughening, the surface roughness in thin film deposition has been controlled empirically by changing deposition parameters. In order to understand the microscopic mechanism of the surface roughening phenomenon during film growth, the researchers established a series of non-equilibrium models and theories. The research showed that the thin film surface roughening phenomenon can be mainly attributed to the upslope and downslope diffusion probability of augmented atoms. Compare. Therefore, it is very important to devise a method to characterize the ratio of the up-slope diffusion probability of augmented atoms.

So far, there are two main difficulties in characterizing the probability ratio of the up-slope diffusion of augmented atoms: (1) The augmented atomic diffusion cannot be characterized dynamically. At present, the only characterization methods that can observe atomic particles are spherical aberration correction transmission electron microscopy and scanning tunneling microscopy. And increasing atomic diffusion is too complicated. During the deposition process, a large number of accelerants are simultaneously deposited and diffused, and the diffusion direction is random, so there is no way to characterize them one by one. Therefore, it is currently unrealistic to realize dynamic characterization of atomic diffusion in experiments. (2) The factors affecting the diffusion direction of the augmented atoms are not clear. Because the diffusion direction of the augmented atoms is affected by both kinetic and thermodynamic factors, and different preparation methods and deposition conditions will also affect it, it is impossible to establish a theoretical model that is highly consistent with the experiment to characterize the up-slope diffusion probability ratio. Based on this, the present invention devises a method for characterizing the ratio of the up-slope diffusion probability of augmented atoms to solve the above-mentioned problems.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for characterizing the ratio of the up-slope diffusion probability of the booster atom.

In order to achieve the above object, the present invention provides the following technical solutions: a method for characterizing the probability ratio of increasing atomic up-slope diffusion, comprising the following steps:

S1: Using atomic force microscopy (AFM) to measure the surface topography of the sample to obtain roughness (RMS) and PSD spectra;

S2: Using Gwyddion software to simulate surface topography, RMS and PSD spectra;

S3: Obtain the protrusion size data (ie h, s) of each rough surface;

S4: Calculate the slope of the Δh/h0-Δs/s0 straight line to obtain the up-slope diffusion probability ratio δ under the preparation conditions.

Preferably, each surface topography in step S1 can be quantitatively described by surface root mean square roughness (RMS) and power spectral density (PSD) spectra, and the thinnest sample with a thickness of d0 has a surface convex at The dimension in the vertical direction is h0, the dimension in the horizontal direction is s0, and the surface roughness is R0.

Preferably, in step S2, the average protruding size data of the surface in different stages of the film growth is (h, s).

Preferably, step S3 needs to ensure that the high-frequency slopes of the RMS and PSD curves obtained in the experiment and simulation are equal.

Preferably, in step S4, the calculation formula of the up and down slope diffusion probability ratio δ is:

(Δh/h0)/(Δs/s0)

Among them, with the continuous deposition of atoms, the thickness of the film is d0+Δd, the size of the protrusion in the vertical direction is h0+Δh, the size in the horizontal direction is s0+Δs, and the roughness is R0+ΔR, then the uphill diffusion probability is is Δh/h0, and the downhill diffusion probability is Δs/s0.

Compared with the prior art, the beneficial effects of the present invention are: the present invention uses the experimental results to guide the simulation, and by means of the unique corresponding relationship between the surface roughness and the PSD map and the surface topography, the method for characterizing the probability ratio of the up- and down-slope diffusion of amplifying atoms is given. The method can quantitatively give the probability ratio of up and down slope diffusion, which builds a bridge between macroscopic surface roughening and microscopic atom-increasing diffusion, and promotes further research on the microscopic mechanism of surface roughening. The method for characterizing the probability ratio of increasing atomic diffusion up and down slope is simple and efficient, and has wide applicability to various deposition processes, which greatly promotes the development of thin film surface technology.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a PSD diagram obtained by simulation in Example 1. FIG.

FIG. 2 is a PSD diagram obtained in the experiment of Example 1. FIG.

FIG. 3 is a graph of the probability ratio of up and down slope diffusion in Example 1. FIG.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Please refer to Figures 1-3, the present invention provides a technical solution: a method for characterizing the probability ratio of increasing atomic up-slope diffusion, comprising the following steps:

S1: Using atomic force microscopy (AFM) to measure the surface morphology of the sample to obtain the roughness;

S2: Using Gwyddion software to simulate surface topography, RMS and PSD spectra;

S3: Obtain the protrusion size data (ie h, s) of each rough surface;

S4: Calculate the slope of the Δh/h0-Δs/s0 straight line to obtain the up-slope diffusion probability ratio δ under the preparation conditions.

Among them, each surface topography in step S1 can be quantitatively described by surface root mean square roughness (RMS) and power spectral density (PSD) spectra. The thinnest film with a thickness of d0 has a surface convex in the vertical direction. The dimension in the direction is h0, the dimension in the horizontal direction is s0, and the surface roughness is R0.

Wherein, the average protruding size data of the surface of the film growth in different stages in step S2 is (h, s).

Among them, step S3 needs to ensure that the high-frequency slopes of the RMS and PSD curves obtained in the experiment and simulation are equal.

Wherein, in step S4, the calculation formula of the up and down slope diffusion probability ratio δ is:

(Δh/h0)/(Δs/s0)

Among them, with the continuous deposition of atoms, the thickness of the film is d0+Δd, the size of the protrusion in the vertical direction is h0+Δh, the size in the horizontal direction is s0+Δs, and the roughness is R0+ΔR, then the uphill diffusion probability is is Δh/h0, and the downhill diffusion probability is Δs/s0.

The simulation is carried out experimentally, and the following data are obtained:

Embodiment 1: the preparation method of this embodiment is:

A hafnium nitride film was deposited on a single-crystal Si substrate by reactive sputtering with high-purity Hf as the target source and Ar and N2 as the discharge gas. The radio frequency power applied to the hafnium target is 150W, the total sputtering pressure is 0.8Pa, the deposition temperature is not heating up, the target-base distance is 70mm, the vacuum degree is 8×10-4Pa, the nitrogen flow rate ratio is 3.2%, and the sample tray is applied The negative voltage was -40V, and the deposition times were 5, 10, 20, 40, 80, and 160 min, respectively. The substrates were ultrasonically cleaned with acetone, ethanol and distilled water, respectively, before being introduced into the sputtering vacuum chamber. After deposition, the surface roughness of the samples was characterized by AFM as 0.34, 0.58, 0.92, 1.31, 2.52 and 2.92 nm, and the experimental PSD high frequency slopes were -2.26, -3.23, -3.49, -3.58, 3.62 and 3.71, respectively. Then, using the simulation software, try to ensure that the surface roughness and the high-frequency slope of the PSD are the same, and the average surface bump sizes h are 1.1, 2.2, 3.5, 5, 10.12, and 11.86 nm, respectively, and s are 3, 5.1, 6.4, 8, and 8. 12.8 and 14.5 nm, the simulated surface roughness at this time is 0.34, 0.59, 0.96, 1.31, 2.52 and 2.93 nm, and the PSD high frequency slope is -2.26, -3.23, -3.49, -3.58, 3.62 and 3.71. After calculation, it is found that the probability ratio of up and down diffusion of hafnium nitride film under this preparation condition is 2.81.

Embodiment 2: the preparation method of this embodiment is:

A hafnium nitride film was deposited on a single-crystal Si substrate by reactive sputtering with high-purity Hf as the target source and Ar and N2 as the discharge gas. The radio frequency power applied to the hafnium target is 150W, the total sputtering pressure is 0.8Pa, the deposition temperature is not heating up, the target-base distance is 70mm, the vacuum degree is 8×10-4Pa, the nitrogen flow rate ratio is 3.2%, and the sample tray is applied The negative voltage was -10V and the deposition times were 5, 10, 20 and 40 min. The substrates were ultrasonically cleaned with acetone, ethanol and distilled water, respectively, before being introduced into the sputtering vacuum chamber. After deposition, the samples were characterized by AFM for surface roughness and experimental PSD high frequency slope. Then use the simulation software to try to ensure that the surface roughness and the high frequency slope of the PSD are the same as the average surface bump sizes h and s obtained. After calculation, the probability ratio of the hafnium nitride film up and down slope diffusion under the preparation conditions is 0.84.

Embodiment 3: the preparation method of this embodiment is:

A hafnium nitride film was deposited on a single-crystal Si substrate by reactive sputtering with high-purity Hf as the target source and Ar and N2 as the discharge gas. The radio frequency power applied to the hafnium target is 150W, the total sputtering pressure is 0.8Pa, the deposition temperature is not heating up, the target-base distance is 70mm, the vacuum degree is 8×10-4Pa, the nitrogen flow rate ratio is 3.2%, and the sample tray is applied The negative voltage was -160V and the deposition times were 5, 10, 20 and 40 min. The substrates were ultrasonically cleaned with acetone, ethanol and distilled water, respectively, before being introduced into the sputtering vacuum chamber. After deposition, the samples were characterized by AFM for surface roughness and experimental PSD high frequency slope. Then use the simulation software to try to ensure that the surface roughness and the high frequency slope of the PSD are the same as the average surface bump sizes h and s obtained. After calculation, the probability ratio of the hafnium nitride film up and down slope diffusion under the preparation conditions is 3.52.

Embodiment 4: the preparation method of this embodiment is:

A hafnium nitride film was deposited on a single-crystal Si substrate by reactive sputtering with high-purity Hf as the target source and Ar and N2 as the discharge gas. The radio frequency power applied to the hafnium target is 150W, the total sputtering pressure is 0.8Pa, the deposition temperature is not heating up, the target-base distance is 70mm, the vacuum degree is 8×10-4Pa, the nitrogen flow rate ratio is 3.2%, and the sample tray is applied The negative voltage was -240V and the deposition times were 5, 10, 20 and 40 min. The substrates were ultrasonically cleaned with acetone, ethanol and distilled water, respectively, before being introduced into the sputtering vacuum chamber. After deposition, the samples were characterized by AFM for surface roughness and experimental PSD high frequency slope. Then use the simulation software to try to ensure that the surface roughness and the high frequency slope of the PSD are the same as the average surface bump sizes h and s obtained. After calculation, the probability ratio of the hafnium nitride film up and down slope diffusion under the preparation conditions is 7.23.

Embodiment 5: the preparation method of this embodiment is:

A hafnium nitride film was deposited on a single-crystal Si substrate by reactive sputtering with high-purity Hf as the target source and Ar and N2 as the discharge gas. The RF power applied to the hafnium target is 150W, the total sputtering pressure is 0.8Pa, the deposition temperature is 400°C, the target-base distance is 70mm, the vacuum degree is 8×10-4Pa, the nitrogen flow rate ratio is 3.2%, and a negative pressure is applied to the sample tray. The voltage was -40V and the deposition times were 5, 10, 20 and 40 min. The substrates were ultrasonically cleaned with acetone, ethanol and distilled water, respectively, before being introduced into the sputtering vacuum chamber. After deposition, the samples were characterized by AFM for surface roughness and experimental PSD high frequency slope. Then use the simulation software to try to ensure that the surface roughness and the high frequency slope of the PSD are the same as the average surface bump sizes h and s obtained. After calculation, it is found that the probability ratio of the hafnium nitride film up and down slope diffusion under the preparation conditions is 3.16.

A method for characterizing the ratio of increasing atomic up-slope diffusion probability of the present invention has the following beneficial effects:

The invention uses the experimental results to guide the simulation, and provides a method for characterizing the diffusion probability ratio of amplifying atoms up and down slope by means of the unique corresponding relationship between the surface roughness and the PSD map and the surface topography, and can quantitatively give the diffusion probability ratio of the up and down slope. A bridge is built between macroscopic surface roughening and microscopic atom-enhancing diffusion, which promotes further research on the microscopic mechanism of surface roughening. The method for characterizing the probability ratio of increasing atomic diffusion up and down slope is simple and efficient, and has wide applicability to various deposition processes, which greatly promotes the development of thin film surface technology.

In the description of this specification, description with reference to the terms "one embodiment," "example," "specific example," etc. means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one aspect of the present invention. in one embodiment or example. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above-disclosed preferred embodiments of the present invention are provided only to help illustrate the present invention. The preferred embodiments do not exhaust all the details, nor do they limit the invention to only the described embodiments. Obviously, many modifications and variations are possible in light of the content of this specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is to be limited only by the claims and their full scope and equivalents.

Claims (5)

1. a method for characterizing increasing atomic up and down slope diffusion probability ratio, is characterized in that: comprise the following steps: S1: Using atomic force microscopy (AFM) to measure the surface topography of the sample to obtain roughness (RMS) and PSD spectra; S2: Use Gwyddion software to simulate surface topography to obtain RMS and PSD spectra; S3: Obtain the protrusion size data (ie h, s) of each rough surface; S4: Calculate the slope of the Δh/h0-Δs/s0 straight line to obtain the up-slope diffusion probability ratio δ under the preparation conditions. 2. a method for characterizing the ratio of increasing atomic up-slope diffusion probability according to claim 1, is characterized in that: in step S1, each surface topography can pass through surface root mean square roughness (RMS) and power spectral density (PSD) spectra quantitatively describe the thinnest film of sample thickness d0 with surface protrusions of size h0 in the vertical direction and s0 in the horizontal direction, and with a surface roughness of R0. 3 . The method of claim 1 , characterized in that: in step S2 , the average protruding size data of the surface at different stages of film growth is (h, s). 4 . 4 . The method for characterizing the ratio of increasing atomic up-slope diffusion probability according to claim 1 , wherein in step S3, it is necessary to ensure that the high-frequency slopes of the RMS and PSD curves obtained in experiments and simulations are equal. 5 . 5. a method for characterizing the ratio of the up-and-down-slope diffusion probability of increasing atoms according to claim 1, is characterized in that: in step S4, the calculation formula of the up-down-slope diffusion probability ratio δ is: (Δh/h0)/(Δs/s0) Among them, with the continuous deposition of atoms, the thickness of the film is d0+Δd, the size of the protrusion in the vertical direction is h0+Δh, the size in the horizontal direction is s0+Δs, and the roughness is R0+ΔR, then the uphill diffusion probability is is Δh/h0, and the downhill diffusion probability is Δs/s0.