Method for forming thermal oxide film of semiconductor substrate and method for manufacturing semiconductor device

Abstract

The present application relates to a method for forming a thermal oxidation film of a semiconductor substrate, which has: a step of preparing a plurality of semiconductor substrates having different amounts of OH groups in a chemical oxidation film formed by cleaning, and performing thermal oxidation treatment on the semiconductor substrates under the same thermal oxidation treatment conditions, and obtaining a first correlation between the amount of OH groups and the thickness of the thermal oxidation film; a step of measuring the amount of OH groups of a substrate cleaned under the same cleaning conditions and with changed drying conditions, and obtaining a second correlation between the drying conditions and the amount of OH groups; a step of obtaining a third correlation between the drying conditions and the thickness of the thermal oxidation film using the first and second correlations; a step of determining the drying and thermal oxidation treatment conditions from the third correlation; a step of performing cleaning of the substrate; and a step of drying and forming a thermal oxidation film on the cleaned substrate using the conditions determined in the step of determining the drying and thermal oxidation treatment conditions. Thus, a method for forming a thermal oxidation film is provided, which can form a thermal oxidation film to a desired thickness with good reproducibility without changing the composition of the cleaning solution.

Description

Technical Field

[0001] This invention relates to a method for forming a thermal oxide film on a semiconductor substrate and a method for manufacturing a semiconductor device. Background Technology

[0002] With the increasing multilayering and thinning of semiconductor integrated circuit devices, there is a need for further thinning of the various films constituting the devices. For example, Patent Document 1 describes that the silicon wafers used in the bonding of silicon wafers need to have a surface with OH groups, and are cleaned using a common SC1 cleaning solution to form a thin oxide film on the surface. Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 09-063910 Patent Document 2: Japanese Patent No. 6791453 Patent Document 3: Japanese Patent No. 6791454 Summary of the Invention The technical problem to be solved by the present invention

[0004] In order to form such an extremely thin silicon oxide film uniformly and reproducibly in-plane or inter-plane (between substrates), the presence of a natural oxide film or a chemical oxide film (an oxide film formed by cleaning the semiconductor substrate with a cleaning solution) pre-formed on the semiconductor substrate cannot be ignored.

[0005] In fact, the inventors of this application learned through investigation and research that, for example, when the cleaning method of the semiconductor substrate is different, the thickness of the subsequent thermal oxide film varies, and such differences in the thickness of the thermal oxide film do not depend on the thickness of the natural oxide film or the chemical oxide film before thermal oxidation. Therefore, before actually performing thermal oxidation of the semiconductor substrate and attempting to evaluate the thickness of the thermal oxide film, it is impossible to know the differences in the thickness of the actually formed thermal oxide film, making it difficult to manage the thermal oxide film formation process.

[0006] As solutions to this problem, the inventions described in Patent Documents 2 and 3 focus on the amount of OH groups in the naturally formed oxide film after cleaning, which is a factor affecting the thickness of a thinner thermal oxide film. They found that the more OH groups there are, the thicker the thermal oxide film. Specifically, they adjust the amount of OH groups by changing the composition of the cleaning chemical solution. However, the inventors of this application continued their investigation and research and discovered the following new problem: if the composition of the cleaning solution is changed, the cleaning force will vary. It is necessary to control the thickness of the thermal oxide film with good reproducibility and high precision while maintaining the cleaning force at a certain level.

[0007] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a method for forming a thermal oxide film on a semiconductor substrate, which can reproducibly form a thermal oxide film of the desired thin thickness without changing the composition of the cleaning solution. Technical means to solve technical problems

[0008] This invention is made to achieve the above-mentioned objective. This invention provides a method for forming a thermal oxide film on a semiconductor substrate. The method is characterized by the following steps: a first correlation acquisition step, wherein multiple semiconductor substrates are prepared in advance, each having a chemical oxide film formed by cleaning, and the amount of OH groups contained in the chemical oxide film being different; the multiple semiconductor substrates are subjected to thermal oxidation treatment under the same thermal oxidation treatment conditions to form a thermal oxide film; and the correlation between the amount of OH groups in the chemical oxide film and the thickness of the thermal oxide film is acquired as a first correlation; a second correlation acquisition step, wherein the amount of OH groups in the chemical oxide film of each of the multiple semiconductor substrates that have formed chemical oxide films by changing the drying conditions after cleaning under the same cleaning conditions is measured, and the drying conditions are acquired as a second correlation. The process includes: a second correlation relationship between the conditions and the amount of OH groups in the chemical oxide film; a third correlation relationship acquisition process, wherein the first and second correlation relationships are used to acquire the correlation relationship between the drying conditions after cleaning of the semiconductor substrate and the thickness of the thermal oxide film as the third correlation relationship; a drying and thermal oxidation treatment condition determination process, wherein the drying conditions and thermal oxidation treatment conditions are determined using the third correlation relationship in a manner that makes the thickness of the thermal oxide film on the semiconductor substrate to which the thermal oxide film is to be formed a predetermined thickness; a cleaning process, wherein the semiconductor substrate to which the thermal oxide film is to be formed is cleaned; and a drying process and a thermal oxide film formation process, wherein the semiconductor substrate to which the thermal oxide film is to be formed is dried and thermally oxidized after the cleaning process using the drying conditions and thermal oxidation treatment conditions determined in the drying and thermal oxidation treatment condition determination process.

[0009] According to this method for forming thermal oxide films on semiconductor substrates, the thermal oxide film can be formed to the desired thin thickness with good reproducibility without changing the composition of the cleaning solution. As a result, the thermal oxide film formation process is easy to manage.

[0010] At this time, in the process of determining the drying and thermal oxidation treatment conditions, the thermal oxidation treatment conditions can be determined to be the same as the thermal oxidation treatment conditions in the first correlation acquisition process.

[0011] Therefore, it is possible to form a thermal oxide film of a certain thickness easily and with higher reproducibility and accuracy.

[0012] At this point, a further step is provided to estimate the thickness of the thermal oxide film, wherein an initial value for the drying conditions of the semiconductor substrate is set, and it is assumed that the semiconductor substrate to which the thermal oxide film is to be formed has been processed under the same drying conditions as the initial value and the thermal oxidation treatment conditions in the first correlation acquisition step, and the thermal oxide film thickness at the assumed time is estimated using the third correlation. In the drying and thermal oxidation treatment condition determination step, the drying conditions and thermal oxidation treatment conditions can be determined based on the thermal oxide film thickness estimated in the thermal oxide film thickness estimation step.

[0013] Therefore, it is easier and more stable to form a thermal oxide film of a certain thickness with high precision and reproducibility.

[0014] At this time, in the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying temperature used as the drying condition is determined to be a higher value than the initial value of the drying temperature of the drying condition in the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying temperature used as the drying condition is determined to be a lower value than the initial value of the drying temperature of the drying condition in the thermally oxidized film thickness estimation step. When the estimated thickness of the thermal oxide film is the same as the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying temperature, which is the drying condition, can be determined to be the same as the initial value of the drying temperature of the drying condition in the thermal oxide film thickness estimation step.

[0015] Furthermore, in the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying time, which serves as the drying condition, is determined to be a longer drying time than the initial value of the drying time for the drying condition in the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying time, which serves as the drying condition, is determined to be a shorter drying time than the initial value of the drying time for the drying condition in the thermally oxidized film thickness estimation step. When the estimated thickness of the thermal oxide film is the same as the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying time, which is the drying condition, is determined to be the same as the initial value of the drying time of the drying condition in the thermal oxide film thickness estimation step.

[0016] Furthermore, in the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the step of determining the drying and thermal oxidation treatment conditions, the heat treatment time used as the thermal oxidation treatment condition is determined to be a shorter heat treatment time than the heat treatment time in the heat treatment conditions of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the step of determining the drying and thermal oxidation treatment conditions, the heat treatment time used as the thermal oxidation treatment condition is determined to be a longer heat treatment time than the heat treatment time in the heat treatment conditions of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermal oxide film is the same as the specified thickness, in the process of determining the drying and thermal oxidation treatment conditions, the heat treatment time used as the thermal oxidation treatment condition is determined to be the same as the heat treatment time in the heat treatment conditions of the thermal oxide film thickness estimation process.

[0017] Furthermore, in the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the step of determining the drying and thermal oxidation treatment conditions, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be a lower heat treatment temperature than the heat treatment temperature in the heat treatment conditions of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be a higher heat treatment temperature than the heat treatment temperature in the heat treatment conditions of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermal oxide film is the same as the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be the same as the heat treatment temperature in the heat treatment conditions of the thermal oxide film thickness estimation step.

[0018] Therefore, it is possible to easily and stably form a thermal oxide film of a certain thickness with high precision and reproducibility.

[0019] At this time, the specified thickness can be 1 to 10 nm.

[0020] If the thickness of the formed thermal oxide film is within such a range, a thin thermal oxide film of a certain thickness can be formed with better reproducibility.

[0021] At this point, the chemical oxide film can be measured using an ATR (attenuated total reflectance) prism, based on 3300 cm⁻¹. -1 The amount of OH groups is calculated from the absorbance of nearby OH groups.

[0022] Compared to conventional transmission FT-IR (Fourier transform infrared spectroscopy), ATR-FT-IR is more sensitive to OH groups present on the surface, thus enabling more precise evaluation of the amount of OH groups.

[0023] At this time, the semiconductor substrate can be a silicon wafer, and the thermal oxide film can be a silicon oxide film.

[0024] The method for forming a thermal oxide film on a semiconductor substrate according to the present invention is particularly suitable for silicon oxide films formed on silicon wafers.

[0025] At this point, a method for manufacturing a semiconductor device is available that uses a semiconductor substrate with a thermally oxidized film formed by the above-described method for forming a thermally oxidized film on a semiconductor substrate to manufacture a semiconductor device.

[0026] Therefore, semiconductor devices can be manufactured using semiconductor substrates with thin thermal oxide films that are free from misalignment between substrates, thus enabling the maintenance of quality uniformity or improved yield. Invention Effects

[0027] As described above, according to the present invention, a thermal oxide film can be formed to the desired thin thickness with good reproducibility without changing the composition of the cleaning solution. As a result, the thermal oxide film formation process is easy to manage. Attached Figure Description

[0028] Figure 1 The flowchart of the method for forming a thermal oxide film on a semiconductor substrate according to the present invention is shown. Figure 2 The amount of OH groups (3300 cm⁻¹) is shown as an example of the first correlation. -1 The relationship between absorbance and thickness of thermally oxidized film. Figure 3 The drying temperature and the amount of OH groups (3300 cm⁻¹) are shown as an example of the second correlation. -1 The relationship between absorbance and light intensity. Figure 4 The relationship between drying temperature and thermal oxide film thickness is shown as an example of the third correlation. Detailed Implementation

[0029] The present invention will now be described in detail, but the invention is not limited thereto.

[0030] As described above, there is a need for a thermal oxide film formation method that can reproducibly form a thermal oxide film of the desired thin thickness on a semiconductor substrate without changing the composition of the cleaning solution.

[0031] The inventors of this application have repeatedly studied the above-mentioned problems and discovered a method for forming a thermal oxide film on a semiconductor substrate. This method comprises the following steps: a first correlation acquisition step, wherein multiple semiconductor substrates are prepared in advance, each having a chemical oxide film formed by cleaning, and the amount of OH groups contained in the chemical oxide film being different. The multiple semiconductor substrates are subjected to thermal oxidation treatment under the same thermal oxidation treatment conditions to form a thermal oxide film, and the correlation between the amount of OH groups in the chemical oxide film and the thickness of the thermal oxide film is acquired as a first correlation; a second correlation acquisition step, wherein the amount of OH groups in the chemical oxide film of each of the multiple semiconductor substrates that have formed a chemical oxide film by changing the drying conditions after cleaning under the same cleaning conditions is measured, and the drying conditions are obtained. The method includes a second correlation relationship, which is the correlation between the amount of OH groups in the chemical oxide film and the component; a third correlation relationship acquisition step, in which the first and second correlation relationships are used to acquire the correlation between the drying conditions after cleaning of the semiconductor substrate and the thickness of the thermal oxide film as the third correlation relationship; a drying and thermal oxidation treatment condition determination step, in which the drying conditions and thermal oxidation treatment conditions are determined using the third correlation relationship in a manner that makes the thickness of the thermal oxide film on the semiconductor substrate to which the thermal oxide film is to be formed a predetermined thickness; a cleaning step, in which the semiconductor substrate to which the thermal oxide film is to be formed is cleaned; and a drying and thermal oxide film formation step, in which the semiconductor substrate to which the thermal oxide film is to be formed is dried and thermally oxidized after the cleaning step using the drying conditions and thermal oxidation treatment conditions determined in the drying and thermal oxidation treatment condition determination step. This method for forming a thermal oxide film on a semiconductor substrate enables the formation of a thermal oxide film of the desired thin thickness with good reproducibility without changing the composition of the cleaning solution. As a result, the thermal oxide film formation process is easy to manage, thus completing the present invention.

[0032] The following explanation is based on the accompanying drawings.

[0033] [First Implementation Plan] First, refer to Figures 1-4 The method for forming a thermal oxide film on a semiconductor substrate according to the first embodiment of the present invention will be described.

[0034] (First Relevance Acquisition Process) First, multiple semiconductor substrates are prepared. Silicon wafers are preferably used as these semiconductor substrates. The thermal oxide film formed is a silicon oxide film. Silicon wafers are widely used as semiconductor substrates, especially since thermal oxide films are formed during semiconductor device fabrication processes. Therefore, a more accurate evaluation can be made by evaluating the silicon wafers themselves after the formation of the thermal oxide film.

[0035] Next, the semiconductor substrate is preferably cleaned with an aqueous HF solution (hydrofluoric acid) to achieve a state where no oxide film is formed on the surface of the prepared semiconductor substrate. After removing the oxide film by cleaning with the aqueous HF solution, further cleaning is performed. The cleaning method performed after cleaning with the aqueous HF solution is not particularly limited; for example, cleaning using chemical solutions such as SC1 cleaning or O3 cleaning, or rinsing with pure water, can be performed. Through cleaning with the aqueous HF solution, a chemical oxide film is formed on the surface of the semiconductor substrate. At this time, the amount of OH groups contained in the chemical oxide film of multiple semiconductor substrates varies. When cleaning with chemical solutions, it is preferable to easily create semiconductor substrates with different amounts of OH groups in the chemical oxide film by using chemical solutions with different concentrations of OH groups. Furthermore, if SC1 cleaning is used, the higher the concentration of NH4OH groups, the stronger the alkalinity, and 3300 cm⁻¹... -1 The higher the absorbance (i.e., the more OH groups it contains), the easier it is to fabricate semiconductor substrates with varying amounts of OH groups in the chemical oxide film by changing the NH4OH concentration; therefore, this is preferred. The range of correlations between the concentration of the cleaning solution and the amount of OH groups varies depending on the cleaning method. Therefore, it is preferable to perform the cleaning with as many different cleaning types and / or conditions as possible, based on the obtained correlation, to obtain multiple correlations between cleaning conditions and the amount of OH groups.

[0036] Next, the amount of OH groups contained in each chemical oxide film formed by each cleaning method is measured. At this time, it is preferable to use an ATR measurement prism to perform ATR-FT-IR measurement of the chemical oxide film. Compared with conventional transmission FT-IR, ATR-FT-IR measurement can evaluate the OH groups present on the semiconductor substrate surface with sufficient sensitivity.

[0037] For example, the amount of OH groups contained in a chemically oxidized film can be determined by examining its infrared absorption characteristics. As a method for measuring infrared absorption characteristics, ATR-FT-IR measurement can be performed, for example, based on a 3300 cm⁻¹ depth. -1 The amount of OH groups was calculated from the relative absorbance in the vicinity. At this point, it was possible to [observe] 3300 cm⁻¹ -1 The relative absorbance value in the vicinity serves as an indicator of the amount of OH groups.

[0038] Next, multiple semiconductor substrates with varying amounts of OH groups in the chemical oxide film are thermally oxidized under the same thermal oxidation conditions to form a thermal oxide film. The formation conditions for the thermal oxide film are not particularly limited and can be performed using conventional methods. Then, the thickness of the formed thermal oxide film is measured. For example, it can be measured using spectroscopic ellipsometry or similar methods.

[0039] Figure 2 The graph illustrating the first correlation shows the relationship between the amount of OH groups in the chemical oxide film on the actual silicon substrate surface and the thickness of the thermal oxide film. Furthermore, the heat treatment conditions at this time were 900°C, 5% oxygen, and 60 minutes. It can be seen that the thickness of the thermal oxide film increases with 3300 cm⁻¹. -1 The film thickness increases due to the increase in relative absorbance (the amount of OH groups). This phenomenon is similar to the phenomenon that the oxidation rate of wet oxidation is greater than that of dry oxidation when using gaseous thermal oxidation, and it can be considered that the film thickness after thermal oxidation varies due to the different amounts of OH groups contained in the chemical oxide film formed on the surface.

[0040] Furthermore, it is possible to use a monitor wafer that has undergone the same cleaning and thermal oxidation treatment as the semiconductor substrate on which the thermal oxide film is formed, or to extract a portion of the semiconductor substrate that has undergone the same treatment to measure the amount of OH groups in the chemical oxide film (3300 cm⁻¹). -1 Measurement of the relative absorbance of the vicinity or the thickness of the thermally oxidized film.

[0041] (Second Relevance Acquisition Process) In the second correlation acquisition process, the amount of OH groups in the chemical oxide film is measured on multiple semiconductor substrates that have been cleaned under the same cleaning conditions and then dried under different drying conditions. The correlation between the drying conditions and the amount of OH groups in the chemical oxide film is obtained as the second correlation. As the drying conditions, parameters that affect the amount of OH groups can be appropriately selected, such as drying temperature or drying time. An example of using drying temperature as a parameter will be described in the following explanation.

[0042] Next, the semiconductor substrate is preferably cleaned using an aqueous HF solution (hydrofluoric acid) to form an oxide-free state on the surface of the prepared semiconductor substrate. The oxide film is removed by cleaning with the aqueous HF solution, followed by further cleaning. The cleaning method after cleaning with the aqueous HF solution is not particularly limited; for example, depending on the purpose, cleaning using chemical solutions such as SC1 cleaning or O3 cleaning can be performed, or rinsing with pure water can also be used. Then, the drying temperature of the semiconductor substrate is varied. By changing the drying temperature after cleaning with HF, chemical oxide films of different compositions are formed on multiple prepared semiconductor substrates. The lower the drying temperature of the semiconductor substrate, the better. (3300 cm⁻¹) -1 The greater the absorbance (i.e., the more OH groups it contains), the easier it is to produce semiconductor substrates with different amounts of OH groups in the chemical oxide film by changing the drying temperature, which is therefore preferred.

[0043] Next, the amount of OH groups contained in each chemically oxidized film at each drying temperature was measured. The determination of the amount of OH groups was as described in the first correlation acquisition step.

[0044] Figure 3 A graph illustrating the relationship between drying temperature and the amount of OH groups in the chemical oxide film on the surface of the silicon substrate during the drying process after SC1 cleaning using the above method is presented, i.e., the second correlation relationship. Furthermore, the drying time was consistently 3 minutes. It can be seen that the amount of OH groups decreases as the drying temperature increases.

[0045] As mentioned above, drying time can be used instead of drying temperature as the drying condition. There is a tendency that the amount of OH groups decreases if the drying time is increased.

[0046] There is no limitation on the order in which the first correlation acquisition step and the second correlation acquisition step are performed. After obtaining the second correlation by measuring the amount of OH groups in the chemical oxide film of multiple semiconductor substrates that have been cleaned under the same cleaning conditions and then dried under different conditions, the first correlation is obtained by performing the aforementioned thermal oxidation treatment on the multiple semiconductor substrates. In this case, since both the first and second correlations can be obtained from the same semiconductor substrate, a higher accuracy correlation can be obtained.

[0047] (Third Relevance Acquisition Process) In the third correlation acquisition process, the first and second correlations are used to obtain the correlation between the drying conditions of the semiconductor substrate after cleaning and the thickness of the thermal oxide film as the third correlation. Figure 4This is a graph illustrating the third correlation derived from the first and second correlations described above. Specifically, it shows the relationship between the drying temperature and the thickness of the thermally oxidized film when a silicon substrate, after SC1 cleaning, is dried at varying temperatures and then subjected to thermal oxidation under fixed conditions (e.g., 900°C, 5% oxygen, 60 minutes). Figure 4 It is known that the thickness of the thermal oxide film decreases as the drying temperature increases. Based on the discussions to date, this can be attributed to the reduction in the amount of OH groups in the chemical oxide film on the silicon substrate surface due to the increased drying temperature.

[0048] (Determination of drying and thermal oxidation treatment conditions) Next, the first implementation plan will not be carried out. Figure 1 The “thermal oxide film thickness estimation process” shown uses the aforementioned third correlation to determine the drying conditions and thermal oxidation treatment conditions in a manner that ensures the thickness of the thermal oxide film on the semiconductor substrate to which the thermal oxide film is to be formed is a predetermined thickness. Figure 4 The graph illustrating the third correlation shows the relationship between drying temperature (°C) on the horizontal axis and thermal oxidation film thickness (nm) on the vertical axis. However, since the first correlation used to obtain the third correlation includes thermal oxidation treatment conditions, it can be said that the third correlation also reflects the thermal oxidation treatment conditions. Specifically, in Figure 4 In the third correlation, when the conditions are thermal oxidation treatments that thicken the oxide film (e.g., high heat treatment temperature and long heat treatment time), Figure 4 The third correlation shown shifts to the upper right; conversely, under thermal oxidation conditions where the oxide film thickness decreases, the correlation shifts. Figure 4 The third correlation shown shifts to the lower left. Using this correlation, it is possible to utilize... Figure 4 The third correlation shown determines the drying conditions and thermal oxidation treatment conditions.

[0049] For example, when the oxidation conditions are fixed, the amount of OH radicals can be changed by adjusting the drying conditions of the semiconductor substrate, thereby forming a predetermined thermal oxide film thickness. Examples of drying conditions for the semiconductor substrate include drying temperature and time; there is a tendency that the higher the temperature and the longer the time, the less OH radicals are present. Considering the takt time of the cleaning process, it is generally preferred to change the drying temperature in the drying conditions. On the other hand, when the drying conditions are fixed, an oxide film of the target thickness can be formed with good reproducibility by adjusting the thermal oxidation conditions (oxidation time or oxidation temperature, etc.).

[0050] It is particularly preferable to determine the thermal oxidation treatment conditions to be the same as those in the first correlation acquisition process. This allows for direct utilization of... Figure 4The third correlation shown allows for the selection of the target thermal oxide film thickness (nm) from the vertical axis, and the simple and accurate determination of the corresponding drying temperature as the drying condition for the semiconductor substrate to which the thermal oxide film is to be formed.

[0051] The thickness specified above is preferably 1 to 10 nm. If the target (expected) thickness of the formed thermal oxide film is within this range, a thin thermal oxide film of a certain thickness can be formed with better reproducibility.

[0052] (Cleaning process) Next, a process is performed to form a thermal oxide film on the semiconductor substrate on which the thermal oxide film is to be formed. First, the semiconductor substrate on which the thermal oxide film is to be formed is cleaned. The cleaning conditions are the same as those used when obtaining the second correlation.

[0053] (Drying process, thermal oxidation film formation process) In the drying process following the cleaning process and the thermal oxidation film formation process, the drying and thermal oxidation processes are performed using the drying and thermal oxidation conditions determined in the drying and thermal oxidation process determination process.

[0054] According to the method for forming a thermal oxide film on a semiconductor substrate according to the first embodiment, a thermal oxide film can be formed to the desired thin thickness easily and with good reproducibility without changing the composition of the cleaning solution. As a result, the thermal oxide film formation process is easy to manage.

[0055] [Second Implementation Plan] The second implementation plan differs from the first implementation plan in the following aspects: Figure 1 As shown, a "thermal oxide film thickness estimation step" is performed before the drying and thermal oxidation treatment condition determination step in the first embodiment described above. In the drying and thermal oxidation treatment condition determination step, the drying conditions and thermal oxidation treatment conditions are determined based on the thermal oxide film thickness estimated in the thermal oxide film thickness estimation step. The thermal oxide film thickness estimation step is the following step: setting an initial value for the drying conditions of the semiconductor substrate, assuming that the semiconductor substrate to which the thermal oxide film is to be formed has been processed with the same drying conditions as the initial value and the thermal oxidation treatment conditions obtained in the first correlation relationship acquisition step, and estimating the thermal oxide film thickness when the above assumption is made using a third correlation relationship.

[0056] (Estimation process for thermal oxidation film thickness) First, initial values ​​for the drying conditions of the semiconductor substrate are set. The choice of these initial values ​​is not particularly limited; either the drying conditions to be used in the actual processing or the drying conditions for the upcoming actual processing can be selected. Using a third correlation, the thickness of the thermal oxide film during the thermal oxidation process is obtained by using the set initial drying conditions and a first correlation. Specifically, this can be achieved by reading... Figure 4 The thickness of the thermal oxide film is estimated by using the thermal oxide film thickness (vertical axis) corresponding to the drying temperature (horizontal axis) equivalent to the initial value.

[0057] (Determination of drying and thermal oxidation treatment conditions) In the drying and thermal oxidation treatment condition determination step following the thermal oxidation film thickness estimation step, the drying conditions and thermal oxidation treatment conditions are determined based on the thermal oxidation film thickness estimated in the thermal oxidation film thickness estimation step, as described above. At this time, one of the drying conditions and the thermal oxidation treatment conditions is determined as the desired condition, and the other is adjusted, thereby determining the drying conditions and thermal oxidation treatment conditions.

[0058] First, the determination of drying conditions will be explained in detail. The thermal oxide film thickness obtained in the thermal oxide film thickness estimation process is compared with the target specified thermal oxide film thickness. When the estimated thermal oxide film thickness is the same as the target thermal oxide film thickness, the drying conditions (i.e., the initial values) that are the same as those in the thermal oxide film thickness estimation process are determined as the drying conditions for the semiconductor substrate to which the thermal oxide film is to be formed.

[0059] When the estimated thermal oxide film thickness deviates from the target value, the drying conditions are adjusted based on the initial value of the drying conditions in the thermal oxide film thickness estimation process, in order to obtain the target thermal oxide film thickness.

[0060] For example, in the second correlation, when changing the drying temperature as a drying condition to obtain the correlation between drying temperature and the amount of OH groups in the chemically oxidized film, such as... Figure 4 As shown, the third correlation is the correlation between drying temperature and the thickness of the thermal oxide film. Furthermore, when the thickness is estimated to be thicker than the target thickness in the thermal oxide film thickness estimation process, the drying conditions for the semiconductor substrate to which the thermal oxide film is to be formed are determined by adjusting the temperature to a higher value than the initial value of the drying conditions in the thermal oxide film thickness estimation process; conversely, when the thickness is estimated to be thinner than the target thickness, the drying conditions for the semiconductor substrate to which the thermal oxide film is to be formed are determined by adjusting the temperature to a lower value than the initial value of the drying conditions in the thermal oxide film thickness estimation process.

[0061] Furthermore, in the second correlation, when the correlation between drying time and the amount of OH groups in the chemical oxide film is obtained by changing the drying time as a drying condition, the third correlation is the correlation between drying time and the thickness of the thermal oxide film. Moreover, when the thickness of the thermal oxide film is estimated to be thicker than the target thickness in the thermal oxide film thickness estimation process, the drying conditions for the semiconductor substrate to which the thermal oxide film is to be formed are determined by adjusting the drying time to a value longer than the initial value of the drying time in the thermal oxide film thickness estimation process; when the thickness is estimated to be thinner than the target thickness, the drying conditions for the semiconductor substrate to which the thermal oxide film is to be formed are determined by adjusting the drying time to a value shorter than the initial value of the drying time in the thermal oxide film thickness estimation process.

[0062] Next, the determination of thermal oxidation conditions will be explained in detail. The thermal oxidation film thickness obtained in the above-mentioned thermal oxidation film thickness estimation process is compared with the target specified thermal oxidation film thickness. When the estimated thermal oxidation film thickness is the same as the target thermal oxidation film thickness, the thermal oxidation conditions (i.e., the initial values) that are the same as those in the thermal oxidation film thickness estimation process are determined as the thermal oxidation conditions for the semiconductor substrate to which the thermal oxidation film is to be formed.

[0063] When the estimated thermal oxide film thickness deviates from the target value, the thermal oxidation conditions, such as thermal oxidation temperature or thermal oxidation time, are adjusted based on the thermal oxidation conditions of the process for estimating the thickness of the thermal oxide film to obtain the target thickness, thereby determining the thermal oxidation conditions.

[0064] For example, in the thermal oxide film thickness estimation process, when the estimated thickness is thicker than the target thickness, the thermal oxidation conditions of the semiconductor substrate to which the thermal oxide film is to be formed can be determined by adjusting the time to a shorter value than the initial value of the heat treatment time of the thermal oxidation conditions in the thermal oxide film thickness estimation process. When the estimated thickness is thinner than the target thickness, the thermal oxidation conditions of the semiconductor substrate to which the thermal oxide film is to be formed can be determined by adjusting the time to a longer value than the initial value of the heat treatment time of the thermal oxidation conditions in the process of estimating the thickness of the thermal oxide film.

[0065] Furthermore, in the thermal oxide film thickness estimation process, when the estimated thickness is thicker than the target thickness, the thermal oxidation conditions of the semiconductor substrate to which the thermal oxide film is to be formed can be determined by adjusting the temperature to a lower value than the initial value of the heat treatment temperature of the thermal oxidation conditions in the thermal oxide film thickness estimation process. When the estimated thickness is thinner than the target thickness, the thermal oxidation conditions of the semiconductor substrate to which the thermal oxide film is to be formed can be determined by adjusting the temperature to a higher value than the initial value of the heat treatment temperature of the thermal oxidation conditions in the thermal oxide film thickness estimation process.

[0066] Furthermore, in this invention, not only can the oxide film thickness be controlled to a specified thickness by adjusting the heat treatment time or heat treatment temperature, but the oxide film thickness can also be controlled to a specified thickness by adjusting the oxygen concentration of the heat treatment atmosphere.

[0067] Similar to the first embodiment, after cleaning the semiconductor substrate to which the thermal oxide film is to be formed, drying and thermal oxidation are performed under the drying conditions and thermal oxide film forming conditions determined above, in a manner that aims to achieve the desired thickness of the thermal oxide film.

[0068] [Third Implementation Plan] While drying and thermal oxidation conditions can be adjusted independently, it is preferable to combine these adjustments to determine the specific drying and thermal oxidation conditions. Particularly when adjusting only the drying or thermal oxidation conditions to determine the target thermal oxide film thickness using a third correlation method fails to achieve the desired thickness, the adjustments can be combined. The drying and thermal oxidation conditions from the thermal oxide film thickness estimation process can be used as a reference to adjust the drying and thermal oxidation conditions, thereby determining the drying and thermal oxidation conditions for the semiconductor substrate to which the thermal oxide film is to be formed.

[0069] For example, when comparing the estimated thickness of the thermal oxide film formed under determined drying conditions with the target thickness of the thermal oxide film, and the thermal oxide film thickness cannot be formed to the target thickness, the thermal oxidation conditions can be adjusted and determined using the thermal oxidation conditions of the process for which the thermal oxide film thickness is estimated as a benchmark, by utilizing a third correlation relationship. Alternatively, when comparing the estimated thickness of the thermal oxide film formed under determined thermal oxidation conditions with the target thickness of the thermal oxide film, and the thermal oxide film thickness cannot be formed to the target thickness, the drying conditions can be further adjusted and determined using a third correlation relationship.

[0070] (Semiconductor device manufacturing method) Semiconductor devices can be manufactured using a semiconductor substrate with a thermal oxide film formed by the thermal oxide film formation method of the semiconductor substrate described above. Semiconductor devices can be manufactured using a semiconductor substrate with a thin thermal oxide film of high quality and no inter-substrate misalignment, thus achieving effects such as maintaining quality uniformity or improving yield. Example

[0071] The present invention will be specifically described below with reference to examples, but these examples do not limit the present invention.

[0072] (Example 1) In this embodiment, the following experiment was conducted to achieve a target thickness of 5.1 nm for the thermal oxide film formed on the semiconductor substrate on which the thermal oxide film is to be formed. First, a 300 mm diameter silicon wafer doped with boron and of normal resistivity was prepared as the semiconductor substrate. After SC1 cleaning, it was dried at temperatures of 30°C, 60°C, 80°C, 200°C, and 300°C to create wafers with different amounts of OH groups in the chemical oxide film. The drying time was 3 minutes for all wafers. Then, the silicon wafers were cut and subjected to ATR-FT-IR measurements at 3300 cm⁻¹. -1 The absorbance was used to determine the amount of OH groups in the chemically oxidized film. From this, a second correlation was obtained, representing the relationship between drying conditions (drying temperature) and the amount of OH groups in the chemically oxidized film. Figure 3 ).

[0073] Next, each wafer under various drying conditions underwent a prescribed thermal oxidation treatment (900°C, 5% oxygen, 60 minutes), and the thickness of the thermally oxidized film was measured to determine the relationship between the amount of OH groups in the chemically oxidized film and the thickness of the thermally oxidized film. The expected thickness of the thermally oxidized film at this time was 5.1 nm. Thus, the first correlation relationship representing the relationship between the amount of OH groups in the chemically oxidized film and the thickness of the thermally oxidized film was obtained. Figure 2 Then, according to Figure 2 First correlation and Figure 3 The second correlation was obtained Figure 4 The third correlation.

[0074] Next, drying temperatures of 50°C and 300°C were set as initial drying conditions. Additionally, for verification, a 300mm diameter silicon wafer doped with boron and a standard resistivity was prepared. After SC1 cleaning, it was dried at 50°C and 300°C respectively, thus creating wafers with different amounts of OH groups in the chemical oxide film. Test samples were cut from the silicon wafers and subjected to ATR-FT-IR measurements, measuring the values ​​at 3300 cm⁻¹ corresponding to the amount of OH groups. -1 The absorbance was measured, and the results showed that the absorbance was 0.18 at a drying temperature of 50℃ and 0.11 at a drying temperature of 300℃.

[0075] If the initial values ​​of the drying conditions and Figure 4 Based on the third correlation, the thickness of the thermal oxidation film under the conditions of 900℃, 5% oxygen, and 60 minutes is estimated. The thickness is 5.17 nm at a drying temperature of 50℃ and 5.07 nm at a drying temperature of 300℃. It can also be deduced that different drying temperatures result in different amounts of OH groups, thus affecting the film thickness. Therefore, if using... Figure 4The third correlation, setting the drying temperature to 200℃, predicts a thermal oxide film thickness of 5.1 nm. Therefore, the drying temperature was determined to be 200℃, and the drying time to be 3 minutes. In practice, a silicon wafer dried under these conditions was subjected to thermal oxidation treatment (900℃, 5% oxygen, 60 minutes) to form a thermal oxide film. The film thickness was measured using spectroscopic ellipsometry, and the result showed that a thermal oxide film of 5.1 nm was formed as expected.

[0076] (Example 2) The first, second, and third correlations were obtained in the same manner as in Example 1. Initial values ​​for the drying conditions (50°C and 300°C) were set. Figure 4 The third correlation is used to estimate the thickness of the thermal oxide film during thermal oxidation at 900°C, 5% oxygen, and for 60 minutes. Then, based on... Figure 4 The third correlation was used to adjust the thermal oxidation time (with fixed drying conditions), determining that the thermal oxidation time was 58 minutes at a drying temperature of 50℃ and 63 minutes at a drying temperature of 300℃. Actual drying and thermal oxidation treatments were performed under the determined conditions, and the expected thermal oxidation film thickness of 5.1 nm was achieved at both drying temperatures of 50℃ and 300℃.

[0077] (Example 3) The first, second, and third correlations were obtained in the same manner as in Examples 1 and 2. Initial values ​​for the drying conditions (50°C and 300°C) were set, and the thickness of the thermal oxide film under thermal oxidation conditions of 900°C, 5% oxygen, and 60 minutes was estimated using the third correlation. Then, the drying temperature and thermal oxidation time were adjusted according to the third correlation, and the drying temperature was determined to be 250°C and the thermal oxidation time to be 62 minutes. Drying and thermal oxide film formation under these conditions resulted in the expected 5.1 nm thermal oxide film.

[0078] (Comparative Example) A 300mm diameter silicon wafer doped with boron and a standard resistivity was prepared. After SC1 cleaning, it was dried at 50℃ and 300℃ respectively to create wafers with different amounts of OH groups in the chemical oxide film. The silicon wafers were then cut and subjected to ATR-FT-IR measurements, and the values ​​at 3300cm⁻¹ corresponded to different amounts of OH groups. -1 The absorbance was measured, and the results showed that the absorbance was 0.18 at a drying temperature of 50℃ and 0.11 at a drying temperature of 300℃.

[0079] To evaluate the electrical properties of the two silicon wafers by measuring GOI (Gate Oxide Integrity), thermal oxidation was performed under the same conditions (900°C, 5% oxygen, 60 minutes) without any adjustments to the drying and thermal oxidation conditions. The results showed that the thickness of the thermally oxidized film was 5.17 nm in the wafer with a drying temperature of 50°C and 5.07 nm in the wafer with a drying temperature of 300°C, deviating from the target of 5.1 nm.

[0080] As described above, embodiments of the present invention have demonstrated that a thermal oxide film can be formed to the desired thin thickness without altering the composition of the cleaning solution, resulting in easy management of the thermal oxide film formation process.

[0081] Furthermore, the present invention is not limited to the above-described embodiments. The above embodiments are illustrative examples, and any solutions that have substantially the same composition and perform the same effects as the technical concept described in the claims of the present invention are included within the technical scope of the present invention.

Claims

1. A method for forming a thermal oxide film on a semiconductor substrate, characterized by comprising the following steps: The first relevance acquisition process, in which... Multiple semiconductor substrates are prepared in advance. The multiple semiconductor substrates have chemical oxide films formed by cleaning and the amount of OH groups contained in the chemical oxide films is different. The multiple semiconductor substrates are subjected to thermal oxidation treatment under the same thermal oxidation treatment conditions to form a thermal oxide film. The correlation between the amount of OH groups in the chemical oxide film and the thickness of the thermal oxide film is obtained as the first correlation relationship. The second correlation acquisition process includes measuring the amount of OH groups in the chemical oxide film of multiple semiconductor substrates that have been cleaned under the same cleaning conditions and then dried under different drying conditions, and obtaining the correlation between the drying conditions and the amount of OH groups in the chemical oxide film as the second correlation. The third correlation acquisition process involves using the first and second correlations to obtain the correlation between the drying conditions of the semiconductor substrate after cleaning and the thickness of the thermal oxide film as the third correlation. The drying and thermal oxidation treatment conditions determination process, wherein the drying conditions and thermal oxidation treatment conditions are determined using the third correlation relationship in such a way that the thickness of the thermal oxidation film on the semiconductor substrate to which the thermal oxidation film is to be formed is a predetermined thickness; The cleaning process includes cleaning the semiconductor substrate to which the thermal oxide film is to be formed; and The drying process and the thermal oxidation film formation process, wherein the semiconductor substrate to which the thermal oxidation film is to be formed is dried and thermally oxidized after the cleaning process is performed using the drying conditions and thermal oxidation conditions determined in the drying and thermal oxidation treatment condition determination process.

2. The method for forming a thermal oxide film on a semiconductor substrate according to claim 1, characterized in that, In the process of determining the drying and thermal oxidation treatment conditions, the thermal oxidation treatment conditions are determined to be the same as those in the process of obtaining the first correlation relationship.

3. The method for forming a thermal oxide film on a semiconductor substrate according to claim 1, characterized in that, The process further includes a thermal oxide film thickness estimation step, wherein an initial value for the drying conditions of the semiconductor substrate is set, and it is assumed that the semiconductor substrate to which the thermal oxide film is to be formed has been processed under the same drying conditions as the initial value and the thermal oxidation treatment conditions in the first correlation acquisition step, and the thermal oxide film thickness when the above assumption is made is estimated using the third correlation. In the process of determining the drying and thermal oxidation conditions, the drying conditions and thermal oxidation conditions are determined based on the thermal oxidation film thickness estimated in the process of estimating the thermal oxidation film thickness.

4. The method for forming a thermal oxide film on a semiconductor substrate according to claim 3, characterized in that, In the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying temperature used as the drying condition is determined to be a higher value than the initial value of the drying temperature of the drying condition in the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying temperature used as the drying condition is determined to be a lower value than the initial value of the drying temperature of the drying condition in the thermally oxidized film thickness estimation step. When the estimated thickness of the thermal oxide film is the same as the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying temperature, which is the drying condition, is determined to be the same as the initial value of the drying temperature of the drying condition in the thermal oxide film thickness estimation step.

5. The method for forming a thermal oxide film on a semiconductor substrate according to claim 3, characterized in that, In the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying time, which serves as the drying condition, is determined to be a longer drying time than the initial value of the drying time for the drying condition in the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying time, which serves as the drying condition, is determined to be a shorter drying time than the initial value of the drying time for the drying condition in the thermally oxidized film thickness estimation step. When the estimated thickness of the thermal oxide film is the same as the specified thickness, in the drying and thermal oxidation treatment condition determination step, the drying time, which is the drying condition, is determined to be the same as the initial value of the drying time of the drying condition in the thermal oxide film thickness estimation step.

6. The method for forming a thermal oxide film on a semiconductor substrate according to claim 3, characterized in that, In the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment time used as the thermal oxidation treatment condition is determined to be a shorter heat treatment time than the heat treatment time in the thermal oxidation treatment condition of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the step of determining the drying and thermal oxidation treatment conditions, the heat treatment time used as the thermal oxidation treatment condition is determined to be a longer heat treatment time than the heat treatment time in the thermal oxidation treatment conditions of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is the same as the specified thickness, in the process of determining the drying and thermal oxidation treatment conditions, the heat treatment time used as the thermal oxidation treatment condition is determined to be the same as the heat treatment time in the thermal oxidation treatment condition of the process of estimating the thickness of the thermally oxidized film.

7. The method for forming a thermal oxide film on a semiconductor substrate according to claim 4, characterized in that, In the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment time used as the thermal oxidation treatment condition is determined to be a shorter heat treatment time than the heat treatment time in the thermal oxidation treatment condition of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the step of determining the drying and thermal oxidation treatment conditions, the heat treatment time used as the thermal oxidation treatment condition is determined to be a longer heat treatment time than the heat treatment time in the thermal oxidation treatment conditions of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is the same as the specified thickness, in the process of determining the drying and thermal oxidation treatment conditions, the heat treatment time used as the thermal oxidation treatment condition is determined to be the same as the heat treatment time in the thermal oxidation treatment condition of the process of estimating the thickness of the thermally oxidized film.

8. The method for forming a thermal oxide film on a semiconductor substrate according to claim 5, characterized in that, In the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment time used as the thermal oxidation treatment condition is determined to be a shorter heat treatment time than the heat treatment time in the thermal oxidation treatment condition of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the step of determining the drying and thermal oxidation treatment conditions, the heat treatment time used as the thermal oxidation treatment condition is determined to be a longer heat treatment time than the heat treatment time in the thermal oxidation treatment conditions of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is the same as the specified thickness, in the process of determining the drying and thermal oxidation treatment conditions, the heat treatment time used as the thermal oxidation treatment condition is determined to be the same as the heat treatment time in the thermal oxidation treatment condition of the process of estimating the thickness of the thermally oxidized film.

9. The method for forming a thermal oxide film on a semiconductor substrate according to claim 3, characterized in that, In the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be a lower heat treatment temperature than the heat treatment temperature in the thermal oxidation treatment condition of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be a higher heat treatment temperature than the heat treatment temperature in the thermal oxidation treatment condition of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is the same as the specified thickness, in the process of determining the drying and thermal oxidation treatment conditions, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be the same as the heat treatment temperature in the thermal oxidation treatment conditions of the process of estimating the thickness of the thermally oxidized film.

10. The method for forming a thermal oxide film on a semiconductor substrate according to claim 4, characterized in that, In the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be a lower heat treatment temperature than the heat treatment temperature in the thermal oxidation treatment condition of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be a higher heat treatment temperature than the heat treatment temperature in the thermal oxidation treatment condition of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is the same as the specified thickness, in the process of determining the drying and thermal oxidation treatment conditions, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be the same as the heat treatment temperature in the thermal oxidation treatment conditions of the process of estimating the thickness of the thermally oxidized film.

11. The method for forming a thermal oxide film on a semiconductor substrate according to claim 5, characterized in that, In the process of estimating the thickness of the thermally oxidized film, When the estimated thickness of the thermally oxidized film is thicker than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be a lower heat treatment temperature than the heat treatment temperature in the thermal oxidation treatment condition of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is thinner than the specified thickness, in the drying and thermal oxidation treatment condition determination step, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be a higher heat treatment temperature than the heat treatment temperature in the thermal oxidation treatment condition of the thermally oxidized film thickness estimation step. When the estimated thickness of the thermally oxidized film is the same as the specified thickness, in the process of determining the drying and thermal oxidation treatment conditions, the heat treatment temperature used as the thermal oxidation treatment condition is determined to be the same as the heat treatment temperature in the thermal oxidation treatment conditions of the process of estimating the thickness of the thermally oxidized film.

12. The method for forming a thermal oxide film on a semiconductor substrate according to claim 1, characterized in that, The specified thickness is 1~10nm.

13. The method for forming a thermal oxide film on a semiconductor substrate according to claim 1, characterized in that, The ATR-FT-IR of the chemically oxidized film was performed using an ATR prism, based on a 3300 cm⁻¹. -1 The amount of OH groups is calculated from the absorbance of nearby OH groups.

14. The method for forming a thermal oxide film on a semiconductor substrate according to any one of claims 1 to 13, characterized in that, The semiconductor substrate is a silicon wafer, and the thermal oxidation film is a silicon oxide film.

15. A method for manufacturing a semiconductor device, characterized in that, Semiconductor devices are manufactured using a semiconductor substrate with a thermally oxidized film produced by the method for forming a thermally oxidized film on a semiconductor substrate according to any one of claims 1 to 14.

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