Method for evaluating the performance of cleaning solution of semiconductor substrate

Abstract

One embodiment of the present invention provides a method for evaluating a semiconductor substrate cleaning solution, comprising the steps of: preparing a tip for an atomic force microscope (AFM) containing a substrate material which is a constituent material of a semiconductor substrate; preparing a specimen on which an abrasive material included in an abrasive for a semiconductor substrate is adsorbed; measuring a first adhesion energy between the substrate material and the abrasive material using an atomic force microscope (AFM) equipped with the tip; preparing an electrode for a passive oscillator microbalance (QCM) containing the substrate material; preparing a cleaning solution for a semiconductor substrate mixed with the abrasive material; measuring a second adhesion energy between the electrode and the abrasive material mixed in the cleaning solution using a passive oscillator microbalance (QCM) equipped with the electrode; and comparing the first adhesion energy with the second adhesion energy to quantify the performance of the cleaning solution.

Description

Technology Field

[0001] The present invention relates to a method for evaluating the performance of a cleaning solution for a semiconductor substrate. Background Technology

[0003] In semiconductor manufacturing processes, the surface of semiconductor substrates is susceptible to contamination by various contaminants. Contaminants on semiconductor substrates are removed using cleaning solutions for semiconductor substrates. There is a need to develop evaluation methods to assess the performance of various types of cleaning solutions for semiconductor substrates. The problem to be solved

[0005] One of the problems that the present invention aims to solve is to provide a method for evaluating a semiconductor substrate cleaning solution that can objectively indicate the performance of the cleaning solution for a semiconductor substrate. means of solving the problem

[0007] As a means of solving the aforementioned problem, one embodiment of the present invention provides a method for evaluating a semiconductor substrate cleaning solution, comprising the steps of: preparing a tip for an atomic force microscope (AFM) containing a substrate material which is a constituent material of a semiconductor substrate; preparing a specimen on which an abrasive material included in a semiconductor substrate abrasive is adsorbed; measuring a first adhesion energy between the substrate material and the abrasive material using an atomic force microscope (AFM) equipped with the tip; preparing an electrode for a passive oscillator microbalance (QCM) containing the substrate material; preparing a cleaning solution for a semiconductor substrate mixed with the abrasive material; measuring a second adhesion energy between the electrode and the abrasive material mixed in the cleaning solution using a passive oscillator microbalance (QCM) equipped with the electrode; and comparing the first adhesion energy with the second adhesion energy to quantify the performance of the cleaning solution.

[0009] In addition, one embodiment provides a method for evaluating a semiconductor substrate cleaning solution, comprising the steps of: measuring a first adhesion energy between a tip of an atomic force microscope (AFM) and an abrasive material using an atomic force microscope (AFM); measuring a second adhesion energy between an electrode of a passive vibrator microbalance (QCM) and the abrasive material mixed in a semiconductor cleaning solution using a passive vibrator microbalance (QCM); and comparing the first adhesion energy and the second adhesion energy to quantify the performance of the cleaning solution. Effects of the invention

[0011] According to embodiments of the present invention, by using an atomic force microscope and a passive oscillator microbalance, a method for evaluating a semiconductor substrate cleaning solution that can objectively indicate the performance of the cleaning solution can be provided. Brief explanation of the drawing

[0013] FIG. 1 is a flowchart illustrating a method for evaluating a cleaning solution according to one embodiment of the present invention. Figure 2 is a flowchart specifically illustrating the step of measuring the first adhesion energy in the flowchart of Figure 1. Figure 3 is a force-distance graph showing the force acting between the tip and the specimen as measured by an atomic force microscope (AFM). Figure 4 is a flowchart specifically illustrating the step of measuring the second adhesion energy in the flowchart of Figure 1. Figure 5 is an adsorption amount-time graph showing the amount of abrasive material adsorbed in a cleaning solution measured by a passive vibrator microbalance (QCM). Figure 6 is an adsorption rate-temperature graph showing the adsorption rate of abrasive material in a cleaning solution according to temperature measured by a passive vibrator microbalance (QCM). FIG. 7 is a conceptual diagram showing the step of quantifying the performance of a cleaning solution according to one embodiment of the present invention. Specific details for implementing the invention

[0014] Hereinafter, preferred embodiments of the present invention will be described as follows with reference to the attached drawings.

[0016] FIG. 1 is a flowchart illustrating a method for evaluating a cleaning solution according to one embodiment of the present invention.

[0017] Referring to FIG. 1, a method for evaluating a cleaning solution according to one embodiment of the present invention may include the steps of: measuring a first adhesion energy between a substrate material and an abrasive material included in an abrasive using an atomic force microscope (AFM) (S110); measuring a second adhesion energy between an electrode and an abrasive material mixed in the cleaning solution using a quartz crystal microbalance (QCM) (S120); and quantifying the performance of the cleaning solution by comparing the first adhesion energy and the second adhesion energy (S130). The present invention determines the adsorption energy of the substrate material and the abrasive material before and after exposure to the cleaning solution using an atomic force microscope and a quartz crystal microbalance. Accordingly, the amount of reduction in adsorption energy between the semiconductor substrate and the abrasive material caused by the cleaning solution can be quantified, and the performance of the cleaning solution can be objectively evaluated. Here, the substrate material is a material constituting a semiconductor substrate, the polishing material is residual particles of abrasive present on the semiconductor substrate after the planarization (CMP) process, and the cleaning solution may refer to a cleaning solution that removes particles of abrasive remaining on the semiconductor substrate.

[0019] FIG. 2 is a flowchart specifically showing the step (S110) of measuring the first adhesion energy in the flowchart of FIG. 1, and FIG. 3 is a force-distance graph showing the force acting between the tip and the specimen measured by an atomic force microscope (AFM).

[0020] Referring to FIG. 2, the step of measuring the first adhesion energy (S110) may include: preparing a tip containing a substrate material which is a constituent material of a semiconductor substrate (S111); preparing a specimen containing an abrasive material which is a constituent material of an abrasive (S112); representing the force acting between the tip and the specimen according to the distance between the tip and the specimen when tapping the specimen with the tip as a force (nN)-distance (μm) graph (S113); calculating the contact area of ​​the tip in contact with the specimen using the force-distance graph (S114); calculating the adsorption energy acting when the tip and the specimen are separated using the force-distance graph (S115); and calculating the first adhesion energy, which is the adsorption energy per atom (eV / #) for the abrasive material of the substrate material, using the contact area of ​​the tip and the adsorption energy (S116).

[0022] In the step (S111) of preparing a tip including a substrate material, the substrate material may include at least one of an insulating material including silicon, silicon oxide, and silicon nitride, and a conductive material including copper (Cu), aluminum (Al), tungsten (W), and titanium (Ti).

[0024] In the step (S112) of preparing a specimen containing an abrasive material, the abrasive material comprises at least one of alumina (Al2O3), silica (SiO2), and ceria (CeO2), and the abrasive material may be in a state of adsorption on the surface of the specimen. For example, the abrasive material may be in a state of coating or dispersion on the surface of the specimen.

[0026] In the step (S113) of representing the force acting between the tip and the specimen as a force (nN)-distance (μm) graph, the force-distance graph may include an approach graph indicating a state in which the tip and the specimen are getting closer and a detach graph indicating a state in which the tip and the specimen are getting further apart.

[0028] In the step (S114) of calculating the contact area of ​​the tip in contact with the specimen, the contact area of ​​the tip can be calculated using the distance (μm) of the point where the force (nN) is maximum in the approach graph. For example, the distance from the point where the tip first contacts the specimen (the point where the distance is 0 μm) in the approach graph to the point where the force is maximum represents the depth of the tip penetrating into the specimen, and using this, the contact area of ​​the tip that contacts the specimen and interacts with the abrasive material coated on the surface of the specimen can be calculated.

[0030] In the step (S115) of calculating the adsorption energy applied when the tip and the specimen are separated, the adsorption energy can be calculated using the area of ​​the region where the force (nN) is 0 or less in the detach graph. For example, the region where the force in the detach graph goes down to 0 or less represents the magnitude of the adsorption force applied between the specimen and the tip, and this can be used to calculate the total amount of adsorption energy applied when the specimen and the tip are completely separated.

[0032] In the step (S116) of calculating the first adhesion energy, which is the adsorption energy per atom (eV / #) for the abrasive material of the substrate material, the first adhesion energy can be obtained by dividing the total amount of adsorption energy applied when the tip and the specimen are separated by the number of atoms of the substrate material corresponding to the contact area of ​​the tip.

[0033] For example, referring to Fig. 3, the depth of the tip penetrating into the interior of the specimen in the approach graph (dotted line) is "L", and the amount of total adsorption energy calculated in the detach graph (solid line) is the area of ​​region "A" (nN*μm). Based on this, the adsorption energy per atom (eV / #) for the abrasive material of the substrate material can be calculated to be approximately 0.5 eV / #. Here, the tip may be made of silicon oxide (SiO2), and the surface of the specimen may be coated with ceria (CeO2).

[0035] FIG. 4 is a flowchart specifically showing the step (S120) of measuring the second adhesion energy in the flowchart of FIG. 1, FIG. 5 is an adsorption amount-time graph showing the amount of abrasive material adsorbed in the cleaning solution measured by a passive vibrator microbalance (QCM), and FIG. 6 is an adsorption rate-temperature graph showing the adsorption rate of abrasive material in the cleaning solution according to temperature measured by a passive vibrator microbalance (QCM).

[0036] Referring to FIG. 4, the step of measuring the second adhesion energy (S120) may include the step of preparing an electrode containing a substrate material (S121), the step of preparing a cleaning solution mixed with an abrasive material (S122), the step of representing the amount of abrasive material mixed in the cleaning solution that is adsorbed to the electrode over time at a specific temperature as an adsorption amount (ng)-time (s) graph (S123), the step of representing the amount of abrasive material (ng)-time (s) graph at a different specific temperature, the step of representing the adsorption rate (ng / s) according to temperature as an adsorption rate (ng / s)-temperature (T) graph (S124), and the step of calculating the second adhesion energy, which is the adsorption energy per atom (eV / #) for the abrasive material of the substrate material in the cleaning solution, using the adsorption rate (ng / s)-temperature (T) graph.

[0038] In the step of preparing an electrode including a substrate material (S121) and the step of preparing a cleaning solution mixed with an abrasive material (S122), the substrate material and the abrasive material may be the same materials used in the step of measuring the first adhesion energy (S110). For example, the substrate material may include at least one of an insulating material including silicon, silicon oxide, and silicon nitride, and a conductive material including copper (Cu), aluminum (Al), tungsten (W), and titanium (Ti). Additionally, the abrasive material may include at least one of alumina (Al2O3), silica (SiO2), and ceria (CeO2), and may be mixed into the cleaning solution in a slurry state.

[0040] Step (S123), which represents the adsorption amount (ng)-time (s) graph, indicates the amount of abrasive material in the cleaning solution adsorbed onto the substrate material over time at a specific temperature. Thus, the adsorption rate of the abrasive material at a specific temperature can be determined.

[0042] The step (S124) of representing the adsorption rate (ng / s)-temperature (T) graph can show the change in adsorption rate according to temperature by repeating the step (S123) of representing the adsorption amount (ng)-time (s) graph with different temperature conditions.

[0044] The step of calculating the second adhesion energy (S125) can be performed using the Arrhenius equation, Langmuir equation, Frumkin equation, Temkin equation, Freundlich equation, or Dubinin-Radushkevich equation.

[0045] For example, by referring to Figures 5 and 6, the adsorption rate of the abrasive material (CeO2) on the substrate material (SiO2) in a specific cleaning solution can be determined, and by using the Arrhenius equation to calculate the adsorption energy (eV / #) per atom of the abrasive material (CeO2) on the substrate material (SiO2) in the cleaning solution, approximately 0.3 eV / # can be obtained.

[0047] FIG. 7 is a conceptual diagram showing the step (S130) of quantifying the performance of a cleaning solution according to one embodiment of the present invention.

[0048] Referring to FIG. 7, the step of quantifying the performance of the cleaning solution (S130) is a step of evaluating the performance of the cleaning solution into objective numerical values ​​by comparing the reduction in adhesive energy between the first adhesive energy determined using AFM and the second adhesive energy determined using QCM.

[0049] For example, the adhesion energy of silicon oxide (SiO2) and ceria (CeO2) before exposure to the cleaning solution calculated in Fig. 4 is about 0.5 eV / #, and the adhesion energy of silicon oxide (SiO2) and ceria (CeO2) after exposure to the cleaning solution calculated in Figs. 5 and 6 is about 0.3 eV / #, so the performance of the cleaning solution can be expressed as an objective numerical value using the reduction in adhesion energy of oxide (SiO2) and ceria (CeO2) by the cleaning solution (about 0.2 eV / #).

[0050] Accordingly, since the evaluation method according to the present invention evaluates the performance of a cleaning solution by utilizing the inherent physical properties of the substrate material and polishing material constituting the semiconductor substrate, it can provide more objective and reliable evaluation results than an evaluation method that counts the number of residual particles in a localized area of ​​the semiconductor substrate after cleaning using an electron microscope, etc.

[0052] The present invention is not limited by the embodiments described above and the attached drawings, but is intended to be limited by the appended claims. Accordingly, various substitutions, modifications, and changes may be made by those skilled in the art within the scope of the technical concept of the present invention as described in the claims, and such are also to be considered to fall within the scope of the present invention.

Claims

Claim 1 A step of preparing a tip for an atomic force microscope (AFM) containing a substrate material which is a constituent material of a semiconductor substrate; a step of preparing a specimen on which an abrasive material included in an abrasive for a semiconductor substrate is adsorbed; a step of measuring a first adhesion energy between the substrate material and the abrasive material using an atomic force microscope (AFM) equipped with the tip; a step of preparing an electrode for a quartz crystal microbalance (QCM) containing the substrate material; a step of preparing a cleaning solution for a semiconductor substrate mixed with the abrasive material; and a step of measuring a second adhesion energy between the electrode and the abrasive material mixed in the cleaning solution using a quartz crystal microbalance (QCM) equipped with the electrode.The method includes a step of quantifying the performance of the cleaning solution by comparing the first adhesion energy and the second adhesion energy, wherein the step of measuring the first adhesion energy comprises: representing the force acting between the tip and the specimen according to the distance between the tip and the specimen when tapping the specimen with the tip as a force (nN)-distance (μm) graph; calculating the contact area of ​​the tip in contact with the specimen using the force-distance graph; calculating the adsorption energy applied when the tip and the specimen are separated using the force-distance graph; and calculating the first adhesion energy, which is the adsorption energy per atom (eV / #) for the abrasive material of the substrate material, using the contact area of ​​the tip and the adsorption energy. The step of measuring the second adhesion energy comprises: representing the adsorption amount of the abrasive material mixed in the cleaning solution that is adsorbed to the electrode over time at a specific temperature as an adsorption amount (ng)-time (s) graph; repeating the step of representing the adsorption amount (ng)-time (s) graph by varying the specific temperature, and adsorption according to temperature A method for evaluating a semiconductor substrate cleaning solution, comprising the steps of: representing a rate (ng / s) as an adsorption rate (ng / s)-temperature (T) graph; and calculating a second adhesion energy, which is the adsorption energy per atom (eV / #) for the abrasive material of the substrate material in the cleaning solution, using the adsorption rate (ng / s)-temperature (T) graph. Claim 2 A method for evaluating a semiconductor substrate cleaning solution according to claim 1, wherein the substrate material comprises at least one of an insulating material including silicon, silicon oxide, and silicon nitride, and a conductive material including copper (Cu), aluminum (Al), tungsten (W), and titanium (Ti). Claim 3 A method for evaluating a semiconductor substrate cleaning solution according to claim 1, wherein the polishing material comprises at least one of alumina (Al2O3), silica (SiO2), and ceria (CeO2). Claim 4 delete Claim 5 A method for evaluating a semiconductor substrate cleaning solution according to claim 1, wherein the force-distance graph comprises an approach graph indicating a state in which the tip and the specimen are approaching, and a detach graph indicating a state in which the tip and the specimen are moving away. Claim 6 A method for evaluating a semiconductor substrate cleaning solution according to claim 5, wherein in the step of calculating the contact area of ​​the tip in contact with the specimen, the contact area of ​​the tip is calculated using the distance (μm) of the point where the force (nN) is maximum in the approach graph. Claim 7 A method for evaluating a semiconductor substrate cleaning solution according to claim 5, wherein in the step of calculating the adsorption energy applied when the tip and the specimen are separated, the adsorption energy is calculated using the area of ​​the region where the force (nN) is 0 or less in the detach graph. Claim 8 delete Claim 9 delete Claim 10 delete

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