Method and system for monitoring a deposition process

Abstract

Quantification of passivation and selectivity during deposition is disclosed. The passivation is estimated by calculating the film thickness over pattern lines and spaces. XPS signals are used, which are normalized with X-ray flux numbers. The method is effective for calculating thickness during selective deposition, where the thickness can be used as a measure of selectivity. The measured photoelectrons of each material can be expressed as a function of the thickness of the material covering it, adjusted by the material constant and the effective attenuation length. In selective deposition on a patterned wafer, three expressions can be solved to determine the thickness of the expected deposition and the thickness of any unintended deposition on the passivation pattern.

Description

[0001] Related Applications

[0002] This application claims the benefit of priority to U.S. Provisional Application No. 62 / 817,492, filed on March 12, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to the field of process control and monitoring in the field of semiconductor manufacturing. The disclosed process control techniques are particularly suitable for monitoring selective deposition processes. Background Art

[0004] For decades, the semiconductor industry has relied on photolithography to generate the patterning required for chip circuits. Photolithography is able to deposit each layer across the wafer and then pattern the layer to form a circuit. In addition to adding many steps and costs to the chip manufacturing process, current nanoscale features make photolithography extremely difficult and perhaps even impossible at some point. In addition, double and multiple patterning (requiring two or more separate lithography and etching steps to define a single layer) used to define nanoscale features can result in unacceptable edge placement errors (EPE) and overlay misalignment.

[0005] An emerging technology called selective deposition deposits each layer only in the designed circuit area, thereby avoiding the need for photolithographic patterning. A promising example of selective deposition is the repeated formation of self-assembled monolayers (SAMs) using atomic layer deposition (ALD), where each monolayer is deposited only in the designed circuit area. A similar technology, molecular layer deposition (MLD) is used for the deposition of organic materials. Generally speaking, the top surface of the substrate has a dielectric pattern, a metal pattern, and may have a semiconductor pattern, and the next layer to be formed may be a metal layer on the metal pattern, a dielectric layer on the dielectric pattern, or a semiconductor on the semiconductor pattern. This may require regional activation or regional deactivation (passivation) before the next layer is formed. ALD deposition using SAMs with surface passivation may be a promising technology because it avoids both the photolithography step and uses surface chemistry for alignment, thereby preventing EPE and overlay errors.

[0006] Regardless of which technology is used, metrology and process control tools are needed to implement an integrated process with acceptable yields. However, to date, suitable metrology tools for process monitoring and characterization have not been developed. Conventional tools used in today's laboratories to study these processes include scanning electron microscopes (SEMs), atomic force microscopes (AFMs), and tunneling electron microscopes (TEMs). These tools are too slow to be used in a production environment and cannot provide real-time monitoring of the process to indicate process excursions or failures in a commercial manufacturing environment.

[0007] X-ray photoelectron spectroscopy (XPS) has been used to analyze the surface chemistry of substrates. XPS spectra are obtained by irradiating a substrate with a beam of X-rays while simultaneously measuring the kinetic energy and number of electrons escaping from the top layer of the substrate. Similarly, X-ray fluorescence (XRF) has been widely used for elemental and chemical analysis of samples by sampling the characteristic "secondary" (or fluorescent) X-ray emission from materials that have been excited by bombardment with high-energy X-rays or gamma rays.

[0008] Problems to be solved

[0009] In order to enable selective deposition in a commercial manufacturing environment, there is a need in the art for process monitoring and control. The method should provide a fast, direct and non-destructive measurement of process quality on the wafer to enable process quality analysis and process drift detection. Summary of the invention

[0010] In order to provide a basic understanding of some aspects and features of the present invention, the following summary of the present disclosure is included. This summary is not an extensive overview of the present invention, and therefore it is not intended to specifically identify the significant or critical elements of the present invention or to delineate the scope of the present invention. Its sole purpose is to present some concepts of the present invention in a simplified form as a prelude to the more detailed description presented below.

[0011] The disclosed embodiments are capable of analyzing and monitoring deposition and / or passivation processes, particularly in the case of selective deposition. The embodiments are also capable of quantifying process quality and identifying process drift or predicting required maintenance of deposition equipment. Thus, the embodiments are capable of enabling selective deposition in a commercial manufacturing environment.

[0012] In the disclosed embodiments, XPS measurements are used to analyze the thickness of the layers formed during the selective deposition. These measurements can be performed during different steps of the selective deposition, for example, to analyze the quality of the passivation, the quality of the deposited layer, the presence of deposited material on the passivated areas, the presence of pinholes, etc. Thus, the disclosed embodiments help ensure that material is correctly deposited where it should be, and that no material is deposited where it should not be.

[0013] The embodiments disclosed herein illustrate the use of XPS intensity to determine metrics of process results, such as layer thickness, passivation, and degree of selectivity.

[0014] In the case of a selective deposition process, the disclosed embodiments can quantify the passivation and the selectivity. In one aspect, the passivation is estimated by calculating the film thickness on the pattern lines and spaces. In the disclosed embodiments, the XPS signal used is normalized using the X-ray flux number. This method is effective for calculating the thickness during a selective deposition process. The thickness can be used as a measure of selectivity. This eliminates the need for blanket wafer data to reference selectivity numbers.

[0015] Examples of embodiments implement the measurement of the thickness (or an approximation of the thickness) of an ALD oxide on a metal overlying or underlying oxide (eg, SiO 2 ).

[0016] Aspects of the present disclosure include methods for monitoring a deposition process, including: providing a sample having a first layer of a first material deposited on a second layer of a second material, the second layer having a pattern of a third material therein; generating an X-ray beam and directing the X-ray beam toward the sample to irradiate the sample; intercepting a portion of the X-ray beam with an X-ray detector to generate an X-ray flux value; collecting electrons emitted by the sample and separating the electrons according to electron energy; determining the number of electrons for each electron energy; and determining the presence of the first material on the pattern of the third material by normalizing the electron count corresponding to the electron energy of the electrons emitted from the pattern of the third material using the X-ray flux value and comparing the resulting normalized electron count to a reference electron count. The method may include obtaining a ratio of the resulting normalized electron count to the reference electron count, and additionally determining the thickness of the first layer on the pattern by amplifying the natural logarithm of the ratio. Amplification may include multiplying the effective attenuation length of photoelectrons emitted from the third material and passing through the first material. Similarly, by normalizing the electron count corresponding to the electron energy of the electrons emitted from the second material using the X-ray flux value and applying a correction factor, the thickness of the first layer on the second material can be determined.

[0017] Further aspects include a method for monitoring a deposition process, comprising: providing a sample having a first layer of a first material deposited on a second layer of a second material, the second layer having a pattern of a third material therein; generating an X-ray beam and directing the X-ray beam toward the sample to irradiate the sample; collecting electrons emitted by the sample and separating the electrons according to electron energy; determining electron counts corresponding to electron energies of electrons emitted from substances of the first material, the second material, and the third material; using the electron counts to generate intensity values ​​I1, I2, and I3 corresponding to photoelectrons emitted from the first, second, and third materials, respectively; representing a modeled value of electrons emitted from substances of the first material as I'1 corresponding to a thickness The method comprises the following steps: a first contribution related to the thickness of a portion and a second contribution related to the thickness of a thin portion, wherein a material constant of a first material and an effective attenuation length of the first material are applied to each of the first contribution and the second contribution; a modeling value of electrons emitted by a substance of a second material is represented as I'2, corresponding to the thickness of the thick portion and adjusted by the material constant of the second material and the effective attenuation length of the second material; a modeling value of electrons emitted by a substance of a third material is represented as I'3, corresponding to the thickness of the thin portion and adjusted by the material constant of the third material and the effective attenuation length of the third material; and the thickness of the thick portion and the thickness of the thin portion are obtained using the intensity values ​​I1, I2 and I3 and the modeling values ​​I'1, I'2 and I'3. The method may also include applying a material constant to an exponent of the ratio of thickness to effective attenuation length.

[0018] In a further aspect, a system for monitoring a deposition process is provided, comprising: a stage for supporting a wafer; an X-ray source for generating an X-ray beam for irradiating the wafer in at least one area of ​​the wafer, wherein the at least one area of ​​the wafer has a first layer of a first material deposited on a second layer of a second material, and the second layer has a pattern of a third material; an X-ray sensor for intercepting part of the X-ray beam and generating an X-ray flux signal; an electron analyzer for spatially dividing electrons emitted from the wafer according to different electron energies; an electron detector for detecting electrons after passing through the electron analyzer and outputting a detection signal; and a processor for receiving the detection signal and thereby determining a signal intensity of electrons in an energy band corresponding to electrons emitted from the third material, and normalizing the signal intensity using the X-ray flux signal to identify that the first material is present on the pattern of the third material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other aspects and features of the present invention will become apparent from the detailed description taken with reference to the following drawings.It should be understood that the detailed description and drawings provide various non-limiting examples of various embodiments of the present invention, which are defined by the appended claims.

[0020] The accompanying drawings, which are included in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the specification, are used to explain and illustrate the principles of the present invention. The accompanying drawings are intended to illustrate the main features of the exemplary embodiments in a diagrammatic manner. The accompanying drawings are not intended to depict every feature of the actual embodiments or the relative sizes of the depicted elements and are not drawn to scale.

[0021] Figure 1 is a partial cross-section of a selectively deposited structure illustrating measurement results according to the disclosed embodiments, and Figure 1A is a schematic diagram illustrating an embodiment of determining layer thickness.

[0022] Figure 2 A measuring device according to one embodiment is illustrated. DETAILED DESCRIPTION

[0023] Embodiments of the deposition process control and monitoring of the present invention will now be described with reference to the accompanying drawings. Different embodiments or combinations thereof may be used for different applications or to achieve different benefits. Depending on the results sought to be achieved, the different features disclosed herein may be used in part or in their most complete form, alone or in combination with other features, balancing the advantages with requirements and constraints. Therefore, certain benefits will be highlighted with reference to different embodiments, but are not limited to the disclosed embodiments. That is, the features disclosed herein are not limited to the embodiments in which they are described, but may be "mixed and matched" with other features and introduced into other embodiments.

[0024] Figure 1 The diagram illustrates a cross section of a portion of a semiconductor wafer, showing a deposition process, e.g., monitoring of a selective deposition process. A base layer 100, e.g., a wafer substrate, is made of silicon, and a layer of insulator 105, in this embodiment a silicon dioxide layer, is deposited thereon. The silicon dioxide layer 105 is patterned by having a plurality of holes or trenches 110 filled with a conductive metal, in the illustrated embodiment tungsten, W. A second layer of insulator 115 will be selectively deposited only on the exposed portions of the insulating layer 105. Figure 1 In the embodiment of the present invention, the zirconium dioxide layer is selectively deposited only on the exposed portion of the silicon dioxide layer. For illustration purposes, Figure 1 The illustration shows that a layer of zirconium dioxide is indeed deposited on the silicon dioxide layer; however, an undesirable thin layer of zirconium dioxide is also deposited on the exposed portions of the tungsten layer. An uneven layer of zirconium dioxide 115 is deposited on the silicon dioxide and tungsten.

[0025] According to one embodiment, XPS is used to monitor the selectivity of the deposition process, i.e., to determine whether any insulating layer is deposited on the exposed portions of the metal layer. Figure 1In this embodiment, XPS is used to determine whether zirconium dioxide is deposited on exposed portions of the tungsten layer, and if so, the thickness of such undesired deposition.

[0026] In one embodiment, Figure 1 The sample shown is irradiated with x-rays and the resulting photoelectron emission (indicated by arrows) from the sample is examined. In this specific embodiment, the emission from the tungsten layer alone is attenuated by the ZrO2 layer 125, referred to herein as the W signal, and is used to calculate the thickness of the unintended / unwanted zirconium dioxide layer. The incident X-ray flux is used as a reference for normalizing the W signal intensity (the terms signal intensity and electron counts are used interchangeably herein). The resulting normalized electron counts can be compared to the reference electron counts.

[0027] Figure 2 An example of an X-ray system 200 for monitoring various embodiments of deposition processes disclosed herein is illustrated. The operation of the system and the analysis described herein can be performed by one or more computers 205. An electron gun 210 emits an electron beam that is directed to strike an anode 215, which is made of aluminum in this embodiment. As a result, X-rays are generated at the anode and directed to a monochromator 220. The X-rays are then diffracted at the monochromator. In this embodiment, the monochromator 220 is made of crystalline quartz and is configured to focus only Al Kα X-rays on a wafer 225. A small amount of this Al Kα is also collected at a flux detector 230. The signal of the flux detector 230 is converted from X-ray counting to a flux number. The flux number is used as a reference indicator of the X-rays striking the wafer.

[0028] The primary Al Kα X-ray beam is directed to strike the wafer 235. As the X-rays pass through the layers of the wafer 225, electrons and secondary X-rays are emitted from each layer of the wafer. The XPS energy analyzer 240 collects the emitted electrons and directs them to the XPS detector 245. The XPS energy analyzer 240 typically separates the emitted electrons according to their energy, similar to how a prism separates white light by photon frequency. Thus, the signal generated by the XPS detector 245 can be used to measure the number of electrons (i.e., intensity) at each specific energy. A sample graph generated by the computer 205 that plots intensity (number of electrons) versus binding energy is displayed on the monitor 250.

[0029] The graph illustrated in monitor 250 illustrates how materials within a sample can be identified. In this particular embodiment, wafer 225 is made of silicon and has a first layer of silicon oxynitride and a layer of hafnium oxide on the silicon oxynitride. The peaks in the graph can be used to identify the materials present in the sample being tested, here wafer 225. Figure 2In the illustrated embodiment, silicon oxynitride is shown covering the entire silicon, and hafnium oxide is shown covering the entire silicon oxynitride layer. Figure 1 As discussed in the examples above, when these layers are selectively deposited, it is important to understand where and to what thickness each material is deposited.

[0030] According to one embodiment, the attenuation of the XPS signal from a layer is used to infer the presence of a different material layer thereon. In addition, the amount of attenuation can be used to quantify the thickness of the above layer. For example, looking at the XPS signal from a metal present in a metal layer (e.g., copper, tungsten, tantalum, etc.), any attenuation of the XPS signal may indicate the presence of an undesirable oxide layer on the metal. When an oxide layer is selectively deposited on an oxide base layer, this can indicate a loss of selectivity. Of course, the opposite can also be determined, that is, the attenuation of the XPS signal from the oxide layer can be used to detect the metal deposited on the oxide, as well as the thickness of such an undesirable metal layer.

[0031] In the disclosed embodiment, the thickness of this undesirable oxide is estimated based on the measured XPS signal from the metal. The thickness is determined using the measured XPS signal obtained during the measurement, the X-ray flux obtained from the flux detector 230, and the XPS signal expected from the metal of interest when it is not covered with an oxide (this can be known from experience, measured from a reference, measured before starting oxide deposition, etc.).

[0032] Steering Figure 1 Specific embodiments, such as Figure 1A As shown, for the upper ZrO2 layer with a thickness of t0, the material S ( Figure 1A The line of W or SiO2 in the S =I S 'e (-t0 / λs，ZrO2) . Among them I S ' (sometimes referred to as reference intensity or reference electron count) is the intensity of the photoelectrons from substance S before they pass through the ZrO2 layer, and λ S,ZrO2 is a material parameter (the effective attenuation length (EAL) of a specific type of photoelectron from substance S passing through material ZrO2, for example, the effective attenuation length of a silicon 2p photoelectron emitted from silicon and passing through ZrO2. In the present disclosure, the abbreviation EAL of material A in material B may be used, but it should be understood to refer to a specific photoelectron emitted from that material).

[0033] Based on the above equation, with the known photoelectron intensity from S, by applying this material parameter to the natural logarithm of the ratio of the measured intensity relative to the expected intensity calibrated for the measured flux, we can estimate the thickness t0 of the ZrO2 layer on it based on the attenuation of the photoelectrons emitted from S and passing through the ZrO2 layer, thus: t0 = λ s,ZrO2 Ln((I s / X-ray flux) / I s ').

[0034] This process can be used to find the thickness of deposited materials (e.g., ZrO2, HfO, etc.) on the intended pattern layer (e.g., SiO2) and to find the thickness of deposited materials on the unintended pattern layer (e.g., Si). For example, this method can be used to evaluate the deposition thickness that can be achieved on a selected surface without any deposition on an adjacent surface (e.g., a passivated / unactivated surface of a substrate). That is, as long as no deposition occurs on an unintended area, no XPS signal attenuation from the material in that area should be observed.

[0035] Reference again Figure 1 , the generalized layer system on the silicon substrate includes a first layer of material A having a pattern of material B formed therein, and a first layer of material B having a thickness t in a desired area on material A. 厚 and may have a thickness t in unintended areas on the pattern of material B 薄 The second layer is deposited. The light emission from substances A and B has an intensity of I A and I B , will be attenuated independently due to the presence of the material layer C, which depends at least on the deposited layers and the thickness of the material layer C. The effect of the material layer C is called the effective attenuation length and is determined independently, for example, experimentally. To determine t 厚 or 薄 The measured intensity is normalized by the total incident X-ray flux on the substrate and corrected for the effective attenuation length. This can be done using the intensity I A and I B This is accomplished by determining the expected deposition thickness and the unintended deposition thickness, if any.

[0036] In the disclosed implementation, the raw intensity number is not used directly because it is necessary to take into account the flux variation of each measurement and the differences between tools. Therefore, the raw intensity is normalized using the X-ray flux number to calculate the thickness. In addition, I s The value of ' can be used as a constant that can be scaled up according to requirements or experience. For example, by performing an XPS measurement on the wafer before depositing the top layer, I can be obtained. s', which can be the photoelectron intensity per some unit incident X-ray flux or at some nominal flux, etc. In addition, due to the base layer and pattern layer (e.g. Figure 1 If the thickness of SiO2 and W in the wafer is relatively thick and constant from wafer to wafer, it is not necessary to measure I for each wafer. s '. Instead, this value metric using a known good wafer can be stored for further measurements.

[0037] Measurements of the thickness of the desired deposited layers and the undesired deposited portions (e.g., the thickness of the ALD oxide deposited on SiO2 and the thickness of the undesired ALD oxide on the metal) can be obtained as follows. According to this embodiment, a multi-material, multi-layer thickness model is developed and the signals from all of these layers are used. For example, consider Figure 1 For the structure shown, the XPS signals corresponding to each of W, SiO2, and ZrO2 were used. Constants were generated to represent the effective contribution to the intensity of each signal. A regression algorithm was then used to optimize the thickness of the deposited layer and the solution was found to produce the least residual undesired deposition. Figure 1 In the specific embodiment of the present invention, the thickness of the zirconium dioxide deposited on the SiO2 region and the zirconium dioxide deposited on the tungsten W region are calculated.

[0038] According to one embodiment, a relationship is established that defines an attenuation equation for each expected substance. For example, in a general case, a deposited layer will be selectively deposited on a layer made of a first material, but may also be deposited unintentionally on an area, e.g., a pattern, made of a second material embedded in the first material. Thus, the system is able to detect three signals: the signal of the substance of the deposited material, the attenuation signal from the substance of the first material, and the attenuation signal from the substance of the second material (possibly to a lesser extent).

[0039] refer to Figure 1 , the signal of the substance of the deposited material is the sum of the following signals: the signal emitted from the layer 115 (also indicated as C) and the unintended portion 125; the attenuated signal from the first material is signal I A , the attenuated signal from the second material is signal I B Thus, for this embodiment, three equations can be set: The first equation defines the signal of the first material being attenuated by the thick layer of the expected deposited material, e.g., I A , the second equation defines the signal of the second material attenuated by the unintended thin layer of deposited material, for example, I B , while the third equation defines the signal of the deposited material 115 with an additional contribution from the unintended deposited material 125, each having a "self" attenuation component, where a photoelectron emitted from deep within the layer is attenuated as it passes through the rest of the material of the layer.

[0040] For example, refer to Figure 1 These equations were developed for an embodiment of the invention where there are three layers of interest: a zirconium dioxide layer selectively deposited on silicon dioxide, and potentially a thin zirconium dioxide layer deposited on a tungsten layer. Thus, the XPS signal of tungsten may be attenuated by the unintended thin zirconium dioxide layer and can be expressed as:

[0041] I W =1 / K W *Exp(-t ZrO2薄 / EAL w_zr ), where K W is a constant representing the effective contribution of tungsten to the signal strength, t ZrO2薄 is the unexpected thickness of the zirconium dioxide layer, and the EAL w_zr is the effective attenuation length of an electron emitted from tungsten and passing through zirconium dioxide. Therefore, the attenuation signal of tungsten through an unintended thin layer is expressed as an exponential of the ratio of the thickness of the thin layer to the effective attenuation length of tungsten through zirconium dioxide; amplified by the tungsten amplification factor.

[0042] The total XPS signal of electrons emitted from zirconium atoms (representing the zirconium dioxide layer) is the sum of the contributions of the thick part deposited on silicon and the thin part deposited on tungsten and can be expressed as:

[0043] I Zr =1 / K Zr *(1-Exp(-t ZrO2厚 / EAL Zr_Zr ))+1 / K Zr *(1-Exp(-t ZrO2薄 / EAL Zr_Zr )); where K Zr is a constant representing the effective contribution of zirconium electrons to the signal intensity, t ZrO2厚 is the expected thickness of the zirconium dioxide layer, t ZrO2薄 is the thickness of the unintended zirconium dioxide layer, EAL Zr_Zr is the effective attenuation length of an electron emitted from zirconium and passing through zirconium dioxide (electrons emitted from zirconium atoms at the bottom of the layer are attenuated by the remaining thickness of the layer above it). The attenuation signal for zirconium is therefore the sum of the attenuation signal through the deposited thick layer and the attenuation signal through the unintended thin layer, and is expressed as the sum of the exponential of the ratio of the thick layer thickness to the zirconium effective attenuation length, amplified by the zirconium amplification factor, and the exponential of the ratio of the thin layer thickness to the zirconium effective attenuation length, amplified by the zirconium amplification factor.

[0044] The XPS signal of silicon dioxide may be attenuated by thick layers of zirconium dioxide and can be expressed as:

[0045] I SiO =1 / KSiO2 *Exp(-t ZrO2厚 / EAL SiO2_Zr );K SiO is a constant representing the effective contribution of silicon electrons to the signal intensity, t ZrO2厚 is the expected thickness of the zirconium dioxide layer, and EAL SiO2_Zr is the effective attenuation length of electrons emitted from silicon and passing through a thick layer of zirconium dioxide. Therefore, the attenuation signal of silicon through the deposited thick layer is expressed as an exponential of the ratio of the thickness of the thick layer to the effective attenuation length of silicon through zirconium dioxide; amplified by the silicon amplification factor.

[0046] Therefore, there are three equations that can be solved to determine the two unknowns: the thickness of the zirconium dioxide layer properly deposited on silicon dioxide and the thickness of the zirconium dioxide deposited on tungsten (if any).

[0047] In one embodiment, using I w and I SiO The strength of I Zr By changing the ZrO2 that represents the deposition of ZrO2 on SiO2 and W, the 2厚 and ZrO 2薄 Solve these expressions to minimize the residual value.

[0048] Minimize and solve ZrO 2厚 and ZrO 2薄 Solution:

[0049]

[0050] where #Zr, #SiO and #W represent the electron counts of zirconium, SiO2 and W, respectively ( Figure 2 The area under the curve shown in the monitor 250) or the XPS signal intensity. These values ​​K Zr , K SiO and K W can be obtained, for example, by performing XPS measurements prior to zirconium deposition or by performing measurements on other reference samples. In one exemplary regression, for example, a nonlinear regression is used to obtain the minimum ratio of the measured raw spectra (e.g., #Zr / #SiO and #Zr / #W) and the modeled or estimated light emission intensity ratio (e.g., I Zr / I SiO and I Zr / I W ) ZrO2厚 and t ZrO2薄 The value of is obtained by the above expression.

[0051] For example, different thicknesses can be used repeatedly in the expression to generate different modeling strength values ​​I W,I Zr and I SiO , and then the resulting I W ,I Zr and I SiO Substitute the value into the residual equation until the residual is minimized. W ,I Zr and I SiO The predicted thickness of the value is then considered the correct or true thickness of the deposited layer.

[0052] In the disclosed embodiments, a deposition process method in a sample having a first layer of a first material deposited on a second layer of a second material, wherein the second layer has a pattern of a third material therein, can be implemented by determining the presence of the first material on the pattern of the third material by normalizing electron counts corresponding to electron energies of electrons emitted from the pattern of the third material using measured X-ray flux values ​​and comparing the resulting normalized electron counts with reference electron counts.

[0053] In addition, the method can be performed by calculating the thickness of the deposited layer in the area of ​​the sample occupied by the second material and the thickness of the deposited layer (if any) in the area of ​​the sample occupied by the pattern of the third material. These thicknesses can be calculated by irradiating the sample with an X-ray beam and collecting photoelectrons emitted from the first, second and third materials of the sample, thereby generating intensity values ​​I1, I2 and I3, respectively. Then, using reference intensities I'1, I'2 and I'3, the respective thicknesses are determined. The reference intensity is the value obtained before depositing the next layer, or the expected value from a "golden" reference sample. For example, I'2 can be obtained by measuring the XPS signal before or after forming the pattern of the third material but before depositing the first layer of the first material. Similarly, I'3 can be obtained by measuring the XPS signal after forming the pattern of the third material but before depositing the first material.

[0054] The value of I1 is expressed as the added contribution from the thick layer on the second material and the thin layer on the third material (if present). Each of I1, I2 and I3 is expressed as a function of the reference intensities I'1, I'2 and I'3, modified by the atomic sensitivity values ​​corresponding to each of the first, second and third materials and the effective attenuation length corresponding to the electrons emitted from each of the first, second and third materials and passing through the corresponding material thereon. The atomic sensitivity values ​​and the effective attenuation length values ​​can be determined experimentally.

[0055] The photoelectron signal of the third material can be normalized using the signals from the first and second materials. For example, since the second layer and the pattern are usually thick and do not vary from wafer to wafer, they can be used as a reference to normalize the signal from the deposited layer. For example, the two contributions from the thick and thin parts of the deposited first layer can be normalized by taking the ratios I1 / I2 and I1 / I3.

[0056] By the disclosed method, a first thickness of a first layer deposited on a second layer and a second thickness of a first layer deposited on a pattern within the second layer are determined by: using electron counts for each electron energy to generate intensity values ​​I1, I2, and I3 corresponding to photoelectrons emitted from the first, second, and third materials, respectively; using iteratively estimated thickness values ​​of the first thickness and the second thickness to calculate modeled intensities I'1, I'2, and I'3 corresponding to photoelectrons emitted from the first, second, and third materials; and minimizing the difference between the measured ratio of the intensity values ​​I1, I2, and I3 and the ratio of the modeled intensity values ​​I'1, I'2, and I'3, thereby obtaining true values ​​of the first thickness and the second thickness. The method may also include representing each of the intensity values ​​I1, I2, and I3 as a function of the modeled intensities I'1, I'2, and I'3, the relevant atomic sensitivity factor of each of the first, second, and third materials, and the effective attenuation length of the photoelectrons emitted by each of the first, second, and third materials, and obtaining the first thickness and the second thickness using the values ​​obtained from the minimization step. The minimization step may include regressing the difference between the measured ratio and the ratio of the modeled intensities.

[0057] In addition, a first thickness of the first layer deposited on the second layer and a second thickness of the first layer deposited on a pattern within the second layer can be determined by: using electron counts for each electron energy to generate intensity values ​​I1, I2, and I3 corresponding to photoelectrons emitted from the first, second, and third materials, respectively; setting an expected intensity I'1 to correspond to the sum of a first emission contribution from a thick portion of the first layer deposited on the second material and associated with the first thickness and a second emission contribution from a thin portion of the first layer deposited on the third material and associated with the second thickness, wherein a material constant of the first material and an effective attenuation length of the first material are applied to each of the first contribution and the second contribution; setting an expected intensity I'2 to correspond to photoemission from the second layer and passing through the first thickness, and adjusted by the material constant of the second material and the effective attenuation length of the emission of the second material; setting an expected intensity I'3 to correspond to photoelectron emission from the pattern and passing through the second thickness, and adjusted by the material constant of the third material and the effective attenuation length of the emission of the third material; and obtaining the first thickness and the second thickness using the intensity values ​​I1, I2, and I3 and the expected I'1, I'2, and I'3. In addition, the thickness can be determined by iteratively calculating the expected strengths I'1, I'2 and I'3 using different estimated values ​​of the first thickness and the second thickness; for each iteration, determining the residual values ​​between the strength values ​​I1, I2 and I3 and the expected I'1, I'2 and I'3; and setting the estimated values ​​of the first thickness and the second thickness that produce the minimum residual values ​​as the actual first thickness and the second thickness.

[0058] It should be understood that the process and technology described herein have no inherent relevance to any specific device and can be implemented by any suitable combination of components. In addition, according to the teachings described herein, various types of general equipment can be used. The present invention has been described with respect to specific embodiments, which are intended to be illustrative in all respects, rather than restrictive. It will be appreciated by those skilled in the art that many different combinations will be applicable to practice the present invention.

[0059] In addition, other embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the present invention disclosed herein. It is noteworthy that the expressions disclosed herein are provided as examples of specific geometric structures of patterned layers as shown in the disclosed embodiments. The various aspects and / or components of the described embodiments may be used alone or in any combination. The specification and embodiments are intended to be exemplary only, and the true scope and spirit of the present invention are indicated by the appended claims.

Claims

1. A method for monitoring a deposition process, comprising: providing a sample having a first layer of a first material deposited on a second layer of a second material, the second layer having a pattern of a third material therein; generating an X-ray beam and directing the X-ray beam toward the sample to irradiate the sample; intercepting a portion of the X-ray beam with an X-ray detector to produce an X-ray flux value; collecting electrons emitted from the sample and separating the electrons according to electron energy; determining an electron count for each of said electron energies; determining the presence of the first material on the pattern of the third material by normalizing an electron count corresponding to an electron energy of electrons emitted from the pattern of the third material using the X-ray flux value and comparing the resulting normalized electron count to a reference electron count; Wherein a first thickness of the first layer deposited on the second layer and a second thickness of the first layer deposited on the pattern are determined by: generating intensity values ​​I1, I2, and I3 corresponding to photoelectrons emitted from the first material, the second material, and the third material, respectively, using the electron counts for each of the electron energies; Calculating modeled intensities I'1, I'2, and I'3 corresponding to photoelectrons emitted from the first material, the second material, and the third material using the iteratively estimated thickness values ​​of the first thickness and the second thickness; The difference between the measured ratio of the intensity values ​​I1 , I2 and I3 and the ratio of the modeled intensities I′1 , I′2 and I′3 is minimized, thereby obtaining the true values ​​of the first and second thicknesses. 2 . The method of claim 1 , wherein comparing the resulting normalized electron count to the reference electron count comprises obtaining a ratio of the resulting normalized electron count to the reference electron count. 3 . The method of claim 2 , further comprising determining a thickness of the first layer on the pattern by magnifying a natural logarithm of the ratio. 4 . The method of claim 3 , wherein amplifying comprises multiplying an effective attenuation length of photoelectrons emitted from the third material and passing through the first material.

5. The method of claim 1, further comprising determining a thickness of the first layer on the second material by normalizing an electron count corresponding to an electron energy of electrons emitted from a second material using the X-ray flux value and applying a correction factor.

6. The method of claim 5, wherein the correction factor comprises an effective decay length of a photoelectron emitted from the second material and passing through the first material.

7. The method of claim 1, wherein the first and second materials are dielectrics and the third material is a conductor, or the first and second materials are conductors and the third material is a dielectric. 8 . The method of claim 7 , wherein providing the sample comprises performing a self-aligned deposition process to deposit the first layer on the second layer.

9. The method of claim 1, wherein the reference electron count is obtained by irradiating a sample before depositing the second layer.

10. The method according to claim 1 also includes expressing each of the intensity values ​​I1, I2 and I3 as a function of the modeling intensities I'1, I'2 and I'3, the relevant atomic sensitivity factors of each of the first material, the second material and the third material, and the effective attenuation length of the photoelectrons emitted from each of the first material, the second material and the third material, and obtaining the first thickness and the second thickness using the values ​​obtained from the minimization step.

11. The method of claim 10, wherein the minimizing step comprises regressing the difference between the measured ratio and the ratio of the modeled intensities.

12. The method of claim 11, wherein the difference between the measured ratio and the ratio of the modeled intensities is expressed as: [(I'1 / I'2) - (I1 / I2)] and [(I'1 / I'3) - (I1 / I3)].

13. The method of claim 11, wherein performing the regression comprises performing a nonlinear regression to minimize the following expression: {[(I'1 / I'2)-(I1 / I2)] 2 } / (I1 / I2) 2 +{[(I'1 / I'3)-(I1 / l3)] 2 } / (I1 / I3) 2 。 14. The method according to claim 1, wherein a first thickness of the first layer deposited on the second layer and a second thickness of the first layer deposited on the pattern are determined by: generating intensity values ​​I1, I2, and I3 corresponding to photoelectrons emitted from the first material, the second material, and the third material, respectively, using the electron counts for each of the electron energies; setting the expected intensity I'1 to the sum of a first contribution corresponding to emission from a thick portion of the first layer deposited on the second material and associated with the first thickness and a second contribution corresponding to emission from a thin portion of the first layer deposited on the third material and associated with the second thickness, wherein a material constant of the first material and an effective attenuation length of the first material are applied to each of the first contribution and the second contribution; setting the expected intensity I'2 to correspond to photoelectrons emitted from the second layer and passing through the first thickness, and adjusted by the material constant of the second material and the effective decay length of emission from the second material; Setting the expected intensity I'3 to correspond to photoelectrons emitted from the pattern and passing through the second thickness, and adjusted by the material constant of the third material and the effective decay length emitted from the third material; The first thickness and the second thickness are obtained using intensity values ​​I1, I2, and I3 and expected I'1, I'2, and I'3.

15. The method according to claim 14, comprising: iteratively calculating expected strengths I'1, I'2 and I'3 by using different estimated values ​​of the first thickness and the second thickness; For each iteration, the residuals between the intensity values ​​I1, I2 and I3 and the expected I'1, I'2 and I'3 are determined; The estimated values ​​of the first thickness and the second thickness that produce the minimum residual value are set as the actual first thickness and the second thickness.

16. A method for monitoring a deposition process, comprising: providing a sample having a first layer of a first material deposited on a second layer of a second material, the second layer having a pattern of a third material therein; generating an X-ray beam and directing the X-ray beam toward the sample to irradiate the sample; collecting electrons emitted by the sample and separating the electrons according to their energy; determining electron counts corresponding to electron energies of electrons emitted from substances of the first material, the second material, and the third material; Using the electron counts to generate intensity values ​​I1, I2, and I3 corresponding to photoelectrons emitted from the first material, the second material, and the third material, respectively; denoting a modeled value of electrons emitted from a substance of the first material as I′1 corresponding to the sum of a first contribution associated with a thickness of a thick portion of the first layer and a second contribution associated with a thickness of a thin portion of the first layer, wherein a material constant of the first material and an effective decay length of the first material are applied to each of the first contribution and the second contribution; denote a modeled value of electrons emitted from a substance of the second material as I'2, corresponding to the thickness of the thick portion of the first layer and adjusted by a material constant of the second material and an effective decay length of the second material; denoting a modeled value of electrons emitted from a substance of the third material as I'3, corresponding to the thickness of the thin portion of the first layer and adjusted by a material constant of the third material and an effective decay length of the third material; The thickness of the thick portion of the first layer and the thickness of the thin portion of the first layer are obtained using the intensity values ​​I1 , I2 , and I3 and the modeling values ​​I′1 , I′2 , and I′3 .

17. The method of claim 16, wherein adjusting by a material constant and an effective attenuation length for each corresponding material comprises applying the material constant to an exponent of a ratio of thickness to the effective attenuation length.

18. The method of claim 16, further comprising applying nonlinear regression to the ratio differences of I1, I2, and I3 and I'1, I'2, and I'3.

19. A system for monitoring a deposition process, the system being configured to perform the method of any one of claims 1 to 18, the system comprising: a stage to support the wafer; an X-ray source that generates an X-ray beam that irradiates the wafer on at least one area of ​​the wafer having a first layer of a first material deposited on a second layer of a second material having a pattern of a third material therein; an X-ray sensor that intercepts a portion of the X-ray beam and generates an X-ray flux signal; an electron analyzer for spatially dividing the electrons emitted from the wafer according to different electron energies; An electron detector detects the electrons passing through the electron analyzer and outputs a detection signal; A processor receives the detection signal and determines therefrom a signal intensity of electrons in an energy band corresponding to electrons emitted from the third material, and normalizes the signal intensity using the X-ray flux signal to determine the presence of the first material on the pattern of the third material.

20. The system of claim 19, wherein the processor further calculates a ratio of the resulting normalized electron counts to a reference electron count.

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