JP2000031226A - Manufacturing device and method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to measuring the thickness of a film on a semiconductor region by optical evaluation in a clustered manufacturing device. SOLUTION: A cleaning chamber 1, a rapid oxidizing chamber 2, an optical measuring chamber 5, etc., are arranged centered on a load lock chamber 3 for providing the manufacturing device of clustered semiconductor device. An optical measuring system is arranged with a light source 7 for exciting light, a light source for measuring light, a photodetector 9, a control analysis system 13. For example, in the formation time of an oxide film, after cleaning up a wafer in the cleaning chamber 1, the remaining extent, etc., of a natural oxide film is measured by photomodulation reflecting power spectroscope in the optical measuring chamber 5 to be oxidized later in the rapid oxidizing chamber 2. In such a constitution, the wafer surface is not oxidized by atmospheric exposure so that the wafer surface status on the way of a series of processing may be monitored thereby making it possible to control the manufacturing steps using the clustered device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing a semiconductor device and a method for manufacturing the same, and more particularly, to the surface of a semiconductor layer during a manufacturing process using a manufacturing apparatus clustered in an atmosphere insulated from the atmosphere. The present invention relates to management of characteristics of a film formed thereon.

[0002]

2. Description of the Related Art In recent years, with the progress of high integration of semiconductor integrated circuits, there is a demand for miniaturization and high performance of elements such as transistors, which are constituent elements of MOS devices. However, miniaturization of elements such as transistors must not impair the reliability of the entire device. Therefore,
There is a demand for miniaturization and reliability improvement of each element constituting an element such as a transistor.

In particular, the thickness of a gate insulating film (gate oxide film), which is an important component of a MOS device, is being rapidly reduced. In the 21st century, a very thin insulating film of 4 nm or less is used. It is expected to be. Here, the characteristics of the gate insulating film are the characteristics of the MOS transistor,
Further, it is said that the electrical characteristics of the semiconductor integrated circuit are determined, and realization of an insulating film having good characteristics is strongly desired.

Here, it has been known that the characteristics of the insulating film largely depend on the surface state of the semiconductor layer before the insulating film is formed. Therefore, a cleaning method for improving the characteristics of the semiconductor layer is known. Etc. are being studied. For example, S
At the research level, it has been reported that a very thin gate oxide film with a thickness as low as about 1.2 nm and high quality can be formed by employing a cleaning method (pre-gate cleaning treatment) that can minimize irregularities on the i-substrate surface. I have.

Further, such a pre-gate cleaning process
A clustered manufacturing device that realizes a series of steps of forming a gate insulating film without exposing it to the atmosphere and prevents the formation of a natural oxide film and the attachment of contaminants due to the exposure to the air has also been reported. 1: Schuegraf et al., I
EEE / International Reliability and Physics Symposiu
m 97, p. 7). It has been verified that a high-quality gate insulating film can be obtained by a manufacturing process using this clustered manufacturing apparatus. In particular, in the step of forming a gate insulating film having a thickness reduced to 4 nm or less, clustering is performed. It is desirable to use production equipment that has been developed.

[0006]

On the other hand, the characteristics of a gate insulating film in a MOS device are conventionally managed by forming a device such as a MOS capacitor or a MOS transistor and analyzing the electrical characteristics of the device. Is being done. Therefore, if any trouble occurs in the process of forming the gate insulating film, the existence of the trouble is discovered by evaluating the electrical characteristics after forming the MOS capacitor and the like. Follow the steps to take measures to resolve the problem. For this reason, a large amount of gate insulating film having poor electric characteristics is continuously formed until a trouble is discovered, which causes a decrease in production efficiency.

However, if an ellipsometer conventionally used for measuring a film thickness in a manufacturing process is used for measuring a thin film, a measured value is shown, but the reliability of the measured value is limited to about 10 nm. However, it is difficult to say that the accuracy of the measured value is sufficiently compensated for a thinner film thickness. In particular, for ultra-thin films having a thickness of about 4 nm or less, a reliable evaluation method that can be performed during the manufacturing process has not yet been established.

In a process using a clustered manufacturing apparatus as described above, after a series of many processes are performed on a wafer, an MO formed on the wafer is processed.
The electrical characteristics of the S capacitor etc. will be measured,
There is no method for managing the state of the wafer in the middle of the series of processes. Therefore, at the laboratory level, in the mass production process of MOS devices, there is no guarantee that a high-quality gate insulating film can be formed even by using a clustered manufacturing apparatus.

A first object of the present invention is to provide a method of manufacturing a semiconductor device incorporating an engineering evaluation method capable of compensating for sufficient reliability and accuracy even for an extremely thin film.

A second object of the present invention is to optically measure the characteristics of an insulating film, particularly the thickness, in a pre-gate process → insulating film forming process using a clustered manufacturing apparatus.
An object of the present invention is to provide a method and an apparatus for manufacturing a semiconductor device which realizes the characteristic management method.

[0011]

According to the present invention, there is provided an apparatus for manufacturing a semiconductor device, comprising: a plurality of processing chambers for processing a wafer having a semiconductor region; and an atmosphere in which a space including the plurality of processing chambers is shielded from the atmosphere. A common container surrounding the common container, a transfer means for transferring the wafer in the common container, and optically changing the surface state of the wafer in a state where the wafer is installed in any part of the common container. And an optical measuring means for evaluation.

Thus, it is possible to optically evaluate the surface state of the wafer without being affected by a natural oxide film formed by exposing the wafer to the atmosphere or the attached dirt. That is, by optically evaluating the surface state of the wafer after removing the film and the surface state of the wafer after forming the film, it is possible to measure, for example, the thickness of the oxide film with high accuracy. Become. In addition, since it is not necessary to take the wafer out of the common container for optical measurement, the in-line evaluation should be used to properly manage the semiconductor device manufacturing process without adversely affecting the wafer during the manufacturing process. Can be.

In the semiconductor device manufacturing apparatus, the optical measuring means may include a first light source for generating excitation light, a second light source for generating measurement light, and an excitation light generated by the first light source. A first light guide member for intermittently irradiating light to a semiconductor region of a wafer in the common container;
A second light guide member for irradiating the semiconductor region with the measurement light generated by the light source, a reflectance detection unit for detecting a reflectance of the measurement light radiated to the semiconductor region, and the semiconductor A third light guide member for causing the measurement light reflected from the region to enter the reflectance detection means, and receiving an output of the reflectance detection means and irradiating the semiconductor region with excitation light when excitation light is irradiated. A change calculation that calculates a value obtained by dividing a difference between the reflectance of the measurement light when the light is not irradiated and the reflectance of the measurement light when the excitation light is not irradiated as a change ratio of the reflectance of the measurement light. Means.

As a result, the following effects can be obtained. First
When the semiconductor region is irradiated with the excitation light guided by the light guide member, carriers in the semiconductor region are excited, and an electric field is generated by the carriers. Due to this electric field, the reflectivity of the measuring light guided to the semiconductor region by the second light guide member is:
The ratio changes depending on whether the excitation light is irradiated or not, and the rate of change changes depending on the magnitude of the electric field intensity and the wavelength of the measurement light. On the other hand, if there is a defect serving as a recombination center of carriers near the surface of the semiconductor region, the life of the excited carriers is shortened, and the electric field intensity formed by the carriers is reduced. That is, the rate of change of the reflectance with and without the excitation light irradiation changes depending on the number of defects and the like near the surface of the semiconductor region. In addition, if a film is present on the semiconductor region, the thickness of the film increases and the process of attaching electrons occurs, and the rate of change in reflectance increases. Therefore, when the change calculation means calculates the change rate of the reflectance of the measurement light in the semiconductor region from the detection value of the reflectance detection means, the change rate of the reflectance is determined by the crystal state of the semiconductor region, the presence or absence of a film, or It contains information about the thickness and the like.
Therefore, the surface state of the wafer can be evaluated with high sensitivity based on the change ratio of the reflectance.

In the apparatus for manufacturing a semiconductor device, the plurality of processing chambers may include a processing chamber for performing a cleaning process including an etching action on the wafer, and a processing chamber for forming a film on a semiconductor region of the wafer. The optical evaluation can be performed with the film on the wafer removed, or the optical evaluation can be performed after the film has been formed on the wafer. Optical evaluation of the wafer surface becomes possible.

In the apparatus for manufacturing a semiconductor device, an optical measurement chamber provided in the common container may be further provided, and the optical measurement means may be provided in the optical measurement chamber.

Further, by making the above-mentioned optical measurement chamber also function as a cooling chamber for cooling a wafer, optical evaluation can be performed using a cooling chamber which is often provided in a clustered manufacturing apparatus. It can be carried out.

In the above-described apparatus for manufacturing a semiconductor device, a processing chamber for forming a film on the wafer is configured to form an oxide film by performing a thermal oxidation process on a semiconductor region of the wafer. And a processing chamber for forming a conductive film on the oxide film is further provided in the inside, so that the conductive film can be formed thereon without exposing the wafer on which the thermal oxide film is formed to the atmosphere. Will be possible.
Therefore, it is possible to form a semiconductor device such as a MOS transistor having an oxide film whose thickness is thin and whose value is accurately controlled.

The first method of manufacturing a semiconductor device according to the present invention comprises:
A method of manufacturing a semiconductor device including a process of forming a film on a semiconductor region of a wafer or removing a film on a semiconductor region of the wafer, the method comprising: irradiating the semiconductor region of the wafer with measurement light; (B) intermittently irradiating the semiconductor region of the wafer with the excitation light, and reflecting the measurement light when the semiconductor region of the wafer is irradiated with the excitation light and when the excitation light is not irradiated. (C) calculating a value obtained by dividing the difference in the reflectance by the reflectance of the measurement light when the excitation light is not irradiated as a reflectance change rate, and based on the reflectance change rate. This is a method for determining the thickness of the film.

According to this method, as described above, when a film is present on a semiconductor region where light modulation reflectance spectroscopy is performed,
Using the fact that the rate of change in reflectance increases due to the process of electron attachment occurring with the increase in film thickness, information on the film thickness can be obtained by light modulation reflectance spectroscopy. In the measurement of the film thickness by the ellipsometry method which is currently widely used, when the film thickness is reduced to about 4 nm or less, either the measurement error is extremely large or the measurement sensitivity cannot be obtained. On the other hand, according to the light modulation reflectance spectroscopy, it is possible to accurately measure the film thickness of such a thin film.

In the first method of manufacturing a semiconductor device, in the step (c), a spectrum of a change ratio of the reflectance when the wavelength of the measurement light is changed is prepared, and the change of the reflectance is calculated. By determining the thickness of the film based on the peak value that is the maximum value of the absolute value of the ratio, the film thickness can be measured with high sensitivity.

In the step (c), a spectrum of the rate of change of the reflectance when the wavelength of the measurement light is changed is prepared in advance, and the maximum value on the positive side of the rate of change of the reflectance and the negative value are prepared. By determining the thickness of the film based on the peak value from the valley, which is the difference from the maximum value on the side, the film thickness can be measured with the highest sensitivity.

In the first method of manufacturing a semiconductor device, in the step (c), the reflection at a certain wavelength close to the wavelength of the measuring light having a peak value which is the maximum value of the absolute value of the change rate of the reflectance. By determining the thickness of the film based on the rate of change of the ratio, the time required for measuring the film thickness can be reduced.

In the first method for manufacturing a semiconductor device, the thickness of the film which cannot be measured by the conventional optical measurement method is 2n.
m or less, the film thickness can be measured with high accuracy.

In particular, when the thickness of the film is 1 nm or less, a high measurement sensitivity and high measurement accuracy can be obtained by performing the above-described optical evaluation on the p-type semiconductor region as the semiconductor region.

In the first method for manufacturing a semiconductor device, the thickness of the film is measured for both the p-type semiconductor region and the n-type semiconductor region as the semiconductor region, and it is determined that the thickness of the film is 1 nm or less. For the measured value, the measured value in the p-type semiconductor region is adopted as the thickness of the film. For the measured value determined to exceed 1 nm in the film thickness, the measured value in the n-type semiconductor region is calculated as the thickness of the film. By using the fact that the characteristic indicating the relationship between the reflectance change rate and the film thickness differs depending on the conductivity type of the semiconductor region, the film thickness of the ultrathin film can be measured with the highest sensitivity.

In the first method for fabricating a semiconductor device, the semiconductor region preferably has a resistivity of 0.1 Ωcm ⁻¹ or less.

According to a second method of manufacturing a semiconductor device of the present invention,
A plurality of processing chambers, a common container surrounding the space including the plurality of processing chambers so as to maintain an atmosphere shielded from the atmosphere, and a transfer unit for transferring a wafer in the common container, and are clustered. A method for manufacturing a semiconductor device using a semiconductor device manufacturing apparatus, wherein a film is formed on a wafer or a film on a wafer is removed in one of the plurality of processing chambers (a). And (b) obtaining the thickness of the film by optically evaluating the surface state of the wafer at any site in the common container.

According to this method, the thickness of the film on the wafer before the series of processing is continuously performed or before the series of processing is completed and returned to the atmosphere can be obtained from the optical evaluation. . Therefore, it is possible to determine whether or not the conditions of the intermediate process or the entire process in the series of processes in the clustered manufacturing apparatus are appropriate and whether or not the film formed on the wafer is acceptable.

In the second method of manufacturing a semiconductor device, the step (b) may include the sub-step (x) of irradiating the semiconductor region of the wafer with measurement light, and the step of intermittently applying excitation light to the semiconductor region of the wafer. (Y) irradiating the semiconductor light-emitting device with the excitation light, and determining a difference in reflectance of the measurement light between when the semiconductor region of the wafer is irradiated with the excitation light and when the excitation light is not irradiated. A sub-step (z) of calculating a value obtained by dividing the reflectance of the measurement light when there is no change as a reflectance change rate, and obtaining the thickness of the film based on the reflectance change rate.

By utilizing the fact that information on the thickness of an extremely thin film is obtained by light modulation reflectance spectroscopy as described above by this method, the thickness of the film and the presence or absence of the film in the clustered apparatus are determined. It becomes possible to grasp.

In the second method for fabricating a semiconductor device, the step (a) includes a process of removing a natural oxide film on the wafer, and the step (b) includes determining a thickness of the natural oxide film. In addition, an extremely thin natural oxide film having a thickness of several nm can be removed without excess or deficiency.

In the second method for manufacturing a semiconductor device, the method further comprises the step (c) of managing the processing time so that the remaining thickness of the natural oxide film becomes a predetermined value or less. It is possible to keep the thickness at the most preferable value.

In the second method of manufacturing a semiconductor device, the step (a) includes a process of forming a gate insulating film on a wafer, and the thickness of the gate insulating film is determined in the step (b). it can.

In the second method of manufacturing a semiconductor device, the step (a) may further include a step of forming a conductor film for a gate electrode on the gate insulating film,
After the step (b), before forming the gate electrode conductor film, a step (c) of managing the thickness of the gate insulating film based on the change rate of the reflectance obtained in the step (b). Further provisions may be made.

In the second method of manufacturing a semiconductor device, in the step (b), the p-type semiconductor region and n
The rate of change of the reflectance is measured for both the p-type semiconductor region and the n-type semiconductor region. It is preferable to determine the remaining thickness of the oxide film.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Processes by Clustered Manufacturing Apparatus Prior to describing a semiconductor device manufacturing apparatus according to an embodiment of the present invention, clustering is performed in a series of processes of cleaning and gate insulating film formation. A method using no manufacturing apparatus and a method using a clustered manufacturing apparatus will be described.

FIGS. 18a to 18c are sectional views showing a method without using a clustered manufacturing apparatus. First, FIG. 18A is a diagram showing a state of a wafer before cleaning. As shown in FIG. 18A, a natural oxide film is formed on the semiconductor region. Next, in the step shown in FIG. 18B, cleaning for removing the oxide film, that is, acid treatment or the like is performed. At this time, a chemical oxide film is formed on the semiconductor region by performing ammonia cleaning on purpose. Next, in a step shown in FIG. 18C, for example, a thermal oxidation process is performed, and an oxide film is formed on the semiconductor region via a chemical oxide film.

On the other hand, FIGS. 19A to 19D are cross-sectional views showing a method using an apparatus for manufacturing a clustered semiconductor device. First, FIG. 19A is a diagram illustrating a state of a wafer when it is carried into a manufacturing apparatus of a clustered semiconductor device. As in the first method, a natural oxide film is formed on the semiconductor region. Next, in the step shown in FIG. 19B, cleaning for removing the oxide film, that is, an acid treatment is performed. At this time, the natural oxide film is once completely removed to expose the surface of the semiconductor region. However, as shown in FIG. 19c, an extremely thin native oxide film may remain on the semiconductor region. Further, in a step shown in FIG. 19D, for example, a thermal oxidation process is performed to form an oxide film on the semiconductor region.

In the following first to third embodiments, FIG.
a- A series of processes of cleaning and forming an oxide film are performed according to the method shown in FIG. 19D.

(First Embodiment) -Configuration of Clustering Chamber- FIG. 1 is a block diagram schematically showing a configuration of an apparatus for manufacturing a clustered semiconductor device according to the present embodiment.

In FIG. 1, 1 is a cleaning chamber, 2 is a rapid oxidation (Rapid Thermal Processing) chamber,
Denotes a load lock chamber, 4 denotes a wafer cooling chamber, 5 denotes an optical measurement chamber, and 6 denotes a wafer load / unload unit. That is, the load lock chamber 3 and each of the chambers 1, 2, 4, 5, and 5 attached thereto like a tuft.
Function as a common container that surrounds a space under a reduced-pressure atmosphere shielded from the atmosphere, and is a so-called clustered manufacturing apparatus. For example, in the process of forming an oxide film, the wafer is cleaned in the cleaning chamber 1 and subsequently oxidized in the high-speed oxidation chamber 2. At that time, the natural oxide film on the wafer is removed in the wafer cleaning step. Further, the load lock chamber 3 is configured to optimize and process the transfer of the wafer, and the inside thereof is reduced in pressure. Therefore, even after the completion of the cleaning step, the wafer surface is not oxidized due to exposure to the atmosphere.

The feature of the present embodiment is that the optical measurement chamber 5 is arranged in a common space of the clustered manufacturing apparatus, and the optical measurement chamber 5 is provided with the excitation light source 7. (Ar ion laser), light source 8 for measuring light (Xe lamp of 150 W), photodetector 9 for detecting the intensity of reflected light of measuring light, light source 7 for excitation light, light source 8 for measuring light, respectively. And optical fibers 10, 11, and 12 that serve as light guide paths between the photodetector 9 and the optical measurement chamber 5, and control of equipment and calculation and analysis of data during measurement by light modulation reflectance spectroscopy. And a control / analysis system 13 for performing the control.

-Optical Measurement System- FIG. 2 is a perspective view schematically showing an optical measurement system provided in the semiconductor device manufacturing apparatus.

In FIG. 2, reference numeral 21 denotes a wafer stage, 2
2 is a wafer, 23 is a quartz window, 24 is an incident measuring light introducing section,
25 is a reflection measuring light deriving unit, 26 is an excitation light introducing unit, 27 is a light shielding plate for blocking stray light which is light which is reflected by the wafer 22 and returns, and 30 is an excitation light introducing unit 2
7 shows signal lines connecting between the control system 7 and the control / analysis system 13, respectively. Here, each of the incident measurement light introducing unit 24, the reflection measurement light deriving unit 25, and the excitation light introducing unit 26 has a function as an optical fiber supporting device. Further, although not shown, the excitation light introducing unit 26 has 50
A chopper for intermittently irradiating (modulating) the DUT with excitation light at a frequency of 0 Hz is provided. The chopper is controlled by a control / analysis system so as to operate in synchronization with the photodetector 9. Have been. That is, the semiconductor device manufacturing apparatus according to the present embodiment controls the manufacturing process while optically monitoring the state of the wafer during a series of processes of cleaning and forming the gate insulating film, thereby providing a high-quality gate insulating film. Is configured to be able to be formed without trouble.

-Principle of Light Modulation Reflectance Measurement- Here, the measurement principle of light modulation reflectance spectroscopy will be described with reference to the structure of the measuring apparatus of the present embodiment shown in FIG. The excitation light generated by the excitation light source 7 is sent into the optical measurement chamber 5 via a chopper attached to the excitation light introduction unit 26, and is applied intermittently to the semiconductor region in the wafer 22. In the present embodiment, the semiconductor region is n
Type diffusion layer. Then, the difference ΔR between the intensity of the reflection measurement light when the semiconductor region in the wafer 22 is irradiated with the excitation light and the intensity when the excitation light is not irradiated is divided by the intensity R of the reflection measurement light when the excitation light is not irradiated. The value (ΔR / R) is detected by the control / analysis system 13 as a change ratio of the reflection intensity. With the above configuration, the change in the change rate of the reflection intensity is monitored. Unlike the measurement using an ellipsometer, it is not necessary to dispose a polarizer on the measurement light incident side and an analyzer on the reflection side. However, it is possible to arrange a polarizer and an analyzer to add an ellipsometry function.

The change rate of the reflection intensity (ΔR /
R) is considered to be caused by the following actions. In general, when light is irradiated to a semiconductor region, the number of carriers excited by light increases, and thereafter, when the carriers return to the original energy level, the carriers emit light and disappear. The electric field intensity in the region of the semiconductor region irradiated with the excitation light changes with the change in the number of carriers. Therefore, the reflection intensity of the measurement light differs between when the excitation light is irradiated and when the excitation light is not irradiated. However, if there are many defects near the surface of the semiconductor region, the defects cause interface states having low energy levels. Since defects having such an interface level function as a carrier trapping layer, even when irradiated with light, carriers are trapped by the defects and are not excited to a sufficiently high energy level, or a high energy level is not excited. If the excited carriers are trapped by defects, the intensity of light generated when the excited carriers return to a low energy level decreases. As a result, the electric field intensity in the excitation light irradiation region of the semiconductor region also changes. Therefore, the change rate (ΔR / R) of the reflection intensity of the measurement light changes depending on the number of trap levels near the surface of the semiconductor region. When a film exists on the semiconductor region and electron attachment near the surface of the semiconductor region is remarkable, the change rate of the reflectance (Δ
R / R) increases. Therefore, by monitoring the rate of change of the reflection intensity of the measurement light, information on the physical state of the region near the surface of the semiconductor region can be obtained.

The frequency of the chopping is considered to be related to the time when the electric field strength in the semiconductor region changes due to the recombination of the carriers. According to experiments, the frequency is preferably 1 kHz or less, more preferably 500 Hz or less. I know. Further, it is preferable that the photon energy of the excitation light be larger than the band gap of the semiconductor region. When a silicon substrate is used, it is preferable to use excitation light having a wavelength of photon energy of 1.1 eV or more. The above is the same in each embodiment described later.

In the present embodiment, since the irradiation intensity (in each wavelength range) of the measurement light is assumed to be constant, the detection of the reflection intensity is replaced by the detection of the reflectance. That is, the measurement of the change ratio of the reflection intensity is performed by irradiating the semiconductor region of the wafer 22 intermittently with the excitation light as the Ar ion laser light and continuously irradiating the measurement light as the Xe lamp light from another direction. This is performed by detecting a change in the reflection intensity of the measurement light. That is, the difference ΔR between the reflection intensity when the semiconductor region is irradiated with the excitation light and the reflection intensity when the excitation light is not irradiated is represented by the reflection intensity R when the semiconductor region is not irradiated with the excitation light. Divided value (ΔR / R)
Is the rate of change of the reflectance. In other words, light modulation reflectance spectroscopy is a technique that changes the wavelength of the probe light while repeatedly irradiating and not irradiating the excitation light, and measures the rate of change of the reflectance for each wavelength (light energy value). This is a method for examining the spectrum shape.

FIG. 9 shows the relationship between the value of photon energy proportional to the reciprocal of the wavelength λ of the probe light incident on the single-crystal silicon layer as the semiconductor region and the rate of change of the reflectance (ΔR / R). FIG. 4 is a spectrum diagram of a simple pattern. The value of the change rate of the reflectance (ΔR / R) shown in FIG.
This is a relative value with the initial state being 0. The position where the change rate of the reflectance (ΔR / R) fluctuates is the highest in the vicinity of the negative peak value shown in FIG. Therefore, in the present embodiment, the peak value means the negative peak value, and the wavelength of the probe light at that time is about 3.30 e, which is almost equal to the energy value indicating the negative peak value.
A wavelength of 376 nm corresponding to V is used. In the following description, the height from the negative peak value to the positive peak value is referred to as “peak value from valley”.

When obtaining this spectrum shape,
It is preferable to detect and analyze the spectrum of the probe light in the wavelength range of 200 to 500 nm.

-Management of Cleaning Step and Optical Measurement- Next, a series of processes of cleaning and forming a gate insulating film using the above-described semiconductor device manufacturing apparatus and optical measurement system will be described.

First, in order to remove a natural oxide film on a wafer, a product wafer including a preceding wafer (monitor wafer) is carried into the load lock chamber 3 from the wafer loading / unloading section 6. In order to perform high-sensitivity measurement,
An n-type semiconductor region having a resistivity of 0.02 Ωcm ⁻¹ is formed in the wafer. Load lock room 3 is about 50mTo
The pressure has been reduced to rr. First, the preceding wafer is guided from the load lock chamber 3 to the cleaning chamber 1, and cleaning with HF vapor and etching of the wafer surface with radicals generated by dissociation of Cl ₂ gas by UV irradiation are performed.
The natural oxide film is removed to form a flat interface. For this purpose, the cleaning chamber 1 is subjected to a corrosion prevention treatment or the like.

Here, the wafer is once carried into the optical measurement chamber 5, and the above-mentioned light modulation reflectance spectroscopy is performed to measure the state of the semiconductor region.

FIG. 3 is a spectrum diagram of the reflectance change showing the result of the light modulation reflectance spectrum. In the figure, the horizontal axis represents the photon energy inversely proportional to the wavelength, and the vertical axis represents ΔR / R. As shown in "Before cleaning" in the figure, it can be seen that the peak value of the spectrum of light modulation reflectance spectroscopy is large because a thick native oxide film is formed on the semiconductor region before cleaning. Also, as shown in the "chemical oxide film" in the figure, even when the chemical oxide film formed by the conventional method is formed, the peak is larger than that in the case where the thick native oxide film is initially formed. Although the value is small, it can be seen that an oxide film having a considerable thickness exists. On the other hand, when the washing is not sufficient, there is a slight but peak as shown in "After washing-2" in FIG. When the oxidation step is performed in this state, a slight defect has occurred in a subsequent reliability evaluation test.

On the other hand, after proper cleaning, almost no peak was observed in the spectrum of light modulation reflectance spectroscopy, as indicated by "after cleaning-1" in FIG.
When the oxidation step was performed in this state, it was found in the subsequent reliability test that almost no defects occurred. As described above, it can be understood that the measurement data of the reflectance spectrum is used for determining whether the cleaning process including the etching action is appropriate.

FIG. 4 is data showing the relationship between the cleaning time and the peak value in the spectrum of light modulation reflectance spectroscopy. As shown in the figure, it can be seen that the peak value decreases as the cleaning time becomes longer, and the natural oxide film is completely removed.

That is, needless to say, in the case of using the conventional non-clustered manufacturing apparatus, even in the case of using the clustered manufacturing apparatus, the cleaning is performed only for an empirically set time, and then the oxidation is performed. When the process is performed, the quality of the gate insulating film may be deteriorated due to a slight remaining natural oxide film. On the other hand, according to the process using the manufacturing apparatus of the present embodiment, it is possible to detect the presence or absence of a very thin oxide film on the semiconductor region before cleaning and after cleaning after cleaning, thereby causing troubles such as defective gate insulating film. Can be reliably prevented.

In the optical measurement chamber 5,
If it is found that an oxide film remains on the cleaned wafer, the wafer is returned to the cleaning chamber 1 again, and the cleaning is performed for a time necessary to remove the remaining oxide film thickness. Just do it. That is, if the process proceeds to the next step as it is, a defective wafer can be relieved, and the wafer can be used effectively.

In this embodiment, the peak value of the spectrum of light modulation reflectance spectroscopy is set to 0.1 as a criterion of pass / fail before oxidation, but this criterion depends on the S / N ratio of the measurement system. Therefore, it is not necessarily required to be 0.1. That is, it is possible to adopt a judgment criterion suitable for each manufacturing process.

After the cleaning, a chemical oxide film may be formed intentionally. In such a case, the appropriate range of the peak value of the spectrum of light modulation reflectance spectroscopy may be grasped in advance. It is possible to perform management of the manufacturing process, such as detecting the occurrence of deviation from the appropriate condition of the manufacturing process and adjusting the manufacturing condition. That is, the method of manufacturing a semiconductor device according to the present invention is not limited to the clustered manufacturing apparatus. However, when a clustered manufacturing apparatus is used, the wafer is not taken out of the apparatus until a series of processes is completed. Therefore, as in the present embodiment, the optical evaluation is performed within the clustered manufacturing apparatus. Is performed, a remarkable effect that the suitability of each process in a series of processes can be determined. Further, since the state of the wafer surface is not affected by environmental conditions (existence of oxygen, moisture, etc.) outside the apparatus, the wafer surface is
The thickness of the oxide film having a small thickness of nm or less can be grasped while removing the influence of the natural oxide film and the like, and there is an advantage that higher measurement accuracy can be obtained.

Further, in the present embodiment, the wafer is subjected to the oxidation step by arranging the high-speed oxidation chamber 2; The present invention can also be applied to a process of forming a nitride film by using the method.

Although the present embodiment has been described only for the case where the film thickness is 2 nm or less, the present invention is not limited to this embodiment. If the relationship between the film thicknesses is determined in advance, it goes without saying that the same effect as in the present embodiment can be obtained.

It is also possible in principle to measure the film thickness by a conventionally used ellipsometry method in a clustered manufacturing apparatus instead of the light modulation reflectance spectrum described in this embodiment. . However, in the measurement of a film by the ellipsometry method, it is necessary to install a polarizer and an analyzer in the observation unit as described above, whereas in the case of the light modulation reflectance spectroscopy of the present invention, the polarizer and the analyzer There is no need to deploy an analyzer or analyzer. Therefore, the adoption of the light modulation reflectance spectroscopy means that the measurement of a thin film having a thickness of 1.5 nm or less can be performed with high accuracy, and from the viewpoint of space saving, clustering that can secure only a limited space. In the manufacturing apparatus described above, it is more advantageous than the ellipsometry method.

(Second Embodiment) Next, a second embodiment relating to the control of the thickness of the oxide film when forming the oxide film will be described. Also in this embodiment, it is assumed that the clustered manufacturing apparatus shown in FIGS. 1 and 2 in the first embodiment is used.

First, a processed wafer including a preceding wafer (monitor wafer) is loaded from the load / unload section 6 into the load lock chamber 3, and then, in the cleaning chamber 1, "after cleaning-1" shown in FIG. Washing is performed under such conditions that a spectrum can be obtained, and this is moved to the optical measurement chamber 5 to perform measurement by light modulation reflectance spectroscopy in the optical measurement chamber 5.

Further, the wafer from which the natural oxide film has been completely removed is oxidized, and at the same time, measurement by light modulation reflectance spectroscopy is performed for each oxidation process by changing the oxidation method and time.

FIG. 5 is a spectrum diagram of light modulation reflectance spectroscopy in this embodiment. The film thickness values shown in the figure are the film thickness values confirmed by TEM observation. However, the peak value in FIG.
Since it changes depending on the N ratio, it merely indicates a value relative to the film thickness. As shown in the figure, almost no peak was observed in the spectrum measured for the wafer immediately after cleaning, and as a result of TEM observation, the thickness of the oxide film was measured to be almost 0 nm.

FIG. 6 shows data indicating the relationship between the film thickness observed by TEM and the peak value in the spectrum of light modulation reflectance spectroscopy. As shown in the figure, the peak value in the spectrum increases as the film thickness increases until the film thickness of the oxide film reaches a value near 2.0 nm. However, it was also found that when the thickness of the oxide film exceeded 2.0 nm, the peak value in the spectrum decreased.

FIG. 7 is a copy of a TEM photograph of a cross-sectional structure of a 2.4-nm-thick oxide film and a polysilicon film deposited on a silicon substrate.
As shown in the figure, in the present application, the thickness of the oxide film is confirmed using the result of TEM observation having a resolution such that the network structure of the silicon oxide film is observed.

Next, based on this data, 1.5 nm
A process for forming an oxide film having a thickness of will be described. First, the wafer is guided to the high-speed oxidation furnace 2, and O ₂ gas is introduced at a flow rate of 500 sccm in the high-speed oxidation furnace 2.
The temperature is raised to 1000 ° C. in about 1 minute. Then, by appropriately setting the subsequent holding time, an oxide film having a desired thickness can be formed. In the experiment in this embodiment, an oxide film having a thickness of about 1.5 nm was obtained with a holding time of about 10 sec. When the optical measurement system of this embodiment is used, the peak value in the spectrum of the light modulation reflectance spectrum at this time is set near 1.8 shown in FIG. 6 to manage the manufacturing process. Was. As a result, according to the conventional method without using the optical measurement while using the clustered manufacturing apparatus, only an oxide film having a variation of 1.5 nm ± 0.2 nm could be formed. On the other hand, in the experiment in the present embodiment, an oxide film having a thickness in the range of 1.5 nm ± 0.1 nm can be formed, and the variation in the thickness of the oxide film
It was able to fall within the range of 0.1 nm.

In the optical measurement chamber 5,
If it is found that an oxide film remains on the cleaned wafer, the wafer is returned to the cleaning chamber 1 again, and the cleaning is performed for a time necessary to remove the remaining oxide film thickness. Just do it. That is, if the process proceeds to the next step as it is, a defective wafer can be relieved, and the wafer can be used effectively.

As described above, the pass / fail of the oxide film is determined and
Appropriate measures such as "proceed to the next process", "perform additional oxidation process", and "remove the first oxidation process after removing the oxide film" can be performed.

Whether the standard value for controlling the manufacturing process is appropriate depends on various factors.
It is preferable to adopt a value suitable for the situation of the process / measurement system.

Further, the measuring method according to the present embodiment is not only applicable to the clustered manufacturing apparatuses and methods, but can also be applied to the conventional film thickness control after the oxidation step. That is, by incorporating such an optical measurement method into the process of forming the insulating film, the film thickness can be accurately grasped during the manufacturing process, so that the process of manufacturing the insulating film such as the gate insulating film can be more appropriately performed. Can be managed.

In particular, when a clustered manufacturing apparatus is used, a wafer is not taken out of the manufacturing apparatus until a series of processes is completed. Therefore, an optical evaluation is performed in the clustered manufacturing apparatus. In addition, it is possible to determine the suitability of each process during a series of processes. Further, since the state of the wafer surface is not affected by environmental conditions (existence of oxygen, moisture, etc.) outside the apparatus, the thickness of the thin oxide film having a thickness of 2 nm or less is removed while removing the influence of the natural oxide film. There is an advantage that higher measurement accuracy can be obtained.

Although the present embodiment has been described only for the case where the film thickness is 2 nm or less, the present invention is not limited to such an embodiment. If the relationship between the film thicknesses is determined in advance, it goes without saying that the same effect as in the present embodiment can be obtained.

Instead of the light modulation reflectance spectroscopy described in this embodiment, it is possible in principle to measure the film thickness by a conventional ellipsometry method in a clustered manufacturing apparatus. . However, as described in the first embodiment, light modulation reflectance spectroscopy is more advantageous than ellipsometry.

Further, in this embodiment, the wafer is subjected to the oxidation step by arranging the high-speed oxidation chamber 2; however, the process of forming the nitrided oxide film by performing the nitridation together with the oxidation, or only the nitriding The present invention can also be applied to the process of forming a nitride film by grasping the relationship between the film thickness and the peak value in the spectrum of light modulation reflectance spectroscopy.

(Third Embodiment) Next, a third embodiment will be described. Also in this embodiment, the clustered manufacturing apparatus shown in FIGS. 1 and 2 in the first embodiment is used.

First, after a processed wafer including a preceding wafer (monitor wafer) is loaded from the load / unload section 6 into the load lock chamber 3, the "after cleaning-1" shown in FIG. Washing is performed under such conditions that a spectrum can be obtained, and this is moved to the optical measurement chamber 5 to perform measurement by light modulation reflectance spectroscopy in the optical measurement chamber 5. The shape of the spectral spectrum obtained from the wafer at this time corresponds to the spectral shape of “０0 nm” shown in FIG. That is, the natural oxide film is almost completely removed, and the surface of the clean wafer is exposed, so that almost no peak appears.

Next, the wafer is moved into the high-speed oxidation chamber 2 and oxidized for about 30 seconds using the gas type, gas flow rate, and temperature rising conditions described in the second embodiment, thereby obtaining a thickness. Forms an oxide film of 3.5 nm.

Next, a nitrogen mixed gas was introduced into the high-speed oxidation chamber 2 to perform a heat treatment (nitriding treatment) on the oxide film on the wafer surface.

FIG. 8 is a diagram showing a spectrum of a change ratio of the reflectance as a measurement result of the light modulation reflectance spectrum before and after the nitriding treatment. As shown in the figure, the reason why the spectral shape, especially the peak value, changes before and after the heat treatment has not been elucidated yet,
_It is conceivable to reduce the number of ₂ / Si interface states generated, to reduce strain near the interface, and the like.

Conventionally, the thickness is 3.5 nm by a high-speed oxidation method.
In the case where an oxide film of a degree is formed, nitriding of the oxide film is performed due to various factors such as generation of an interface state of SiO ₂ / Si. There was no management method. On the other hand, according to the method of the present embodiment, it is possible to provide a criterion for determining the quality of the nitrided oxide film by comparing the light modulation spectrum before and after the nitriding treatment. By comparing the conditions of the nitriding treatment with the quality of the oxide film after the nitriding treatment, it is possible to manage the nitriding treatment process. For example, by determining the appropriate range of the peak value of the spectrum shown in FIG. 8 and controlling the manufacturing process, it is possible to solve various troubles associated with the nitriding process and determine whether or not the nitrided oxide film is acceptable. Thus, it is possible to take appropriate measures such as proceeding to the next processing, performing additional nitridation processing, and starting again from the cleaning step for removing the oxide film.

Whether the standard value for managing the manufacturing process is appropriate depends on various factors.
It is preferable to adopt a value suitable for the situation of the process / measurement system.

Further, the measuring method according to the present embodiment is not only applicable to the clustered manufacturing apparatuses and methods, but can also be applied to the conventional management of the nitriding process after forming an oxide film. That is, by incorporating such an optical measurement method into the nitriding process after the formation of the oxide film, the film thickness can be accurately grasped during the manufacturing process, so that the nitriding process of the oxide film can be performed more appropriately. Can be managed. However, when a clustered manufacturing apparatus is used, the wafer is not taken out of the apparatus until a series of processes is completed. Therefore, as in the present embodiment, the optical evaluation is performed within the clustered manufacturing apparatus. Is performed, a remarkable effect that the suitability of each process in a series of processes can be determined. Further, since the state of the wafer surface is not affected by environmental conditions (existence of oxygen, moisture, etc.) outside the apparatus, 2 nm
The thickness of the thin oxide film having the following thickness can be grasped while removing the influence of the natural oxide film and the like, and there is an advantage that higher measurement accuracy can be obtained.

In this embodiment, the case where the nitriding treatment is performed as the heat treatment of the oxide film has been described. However, the present invention is not limited to this embodiment. For example, a thin oxide film may be formed between the silicon layer and the tantalum oxide layer by forming a tantalum oxide film on the silicon layer and then performing a heat treatment. Method can be applied.

(Fourth Embodiment) In the first to third embodiments, an optical measurement system for performing light modulation reflectance spectroscopy is attached to the optical measurement chamber 5 in the clustered manufacturing apparatus. However, the present invention is not limited to such an embodiment. For example, the present invention can be applied to the following non-clustered manufacturing apparatus.

FIG. 10 schematically shows a configuration in which optical measurement is performed in a single chamber according to the fourth embodiment, which is not a clustered manufacturing apparatus, for example, in a reaction processing chamber 50 for performing plasma CVD. It is sectional drawing. As shown in FIG. 1, an anode electrode 53 serving as a lower electrode and a cathode electrode 5 serving as an upper electrode are provided in a reaction processing chamber 50.
And a wafer 22 made of p-type silicon is placed on the anode electrode 53. A silicon oxide film (not shown) is formed on the n-type semiconductor region 24 of the wafer 22 by CVD. Then, a high-frequency power is supplied between the electrodes 53 and 54 from a high-frequency power supply 51 via a coupling capacitor 52 to generate a plasma 55 in the reaction processing chamber 50. Also, on the wall surface of the reaction processing chamber 50, an end point detection window 57, a probe light incidence window 58, and a reflected light observation window 5 are provided.
9 are provided.

On the other hand, an end point detection system 59 is provided outside the reaction processing chamber 50, and the reflection intensity R
A member for observation is provided. First, a Xe lamp 61 for generating a probe light for irradiating the n-type semiconductor region 24 is provided. After a probe light 71 generated by the Xe lamp 61 is reflected by a mirror 62, a probe light incident window 58 is formed. Through the silicon oxide film of the wafer 22 set in the reaction processing chamber 50 through the silicon oxide film, the n-type semiconductor region 24 is reached. Then, the reflected probe light 72 reflected by the n-type semiconductor region 24 is taken out of the reaction processing chamber 50 from the reflected light observation window 59 and is reflected by the reflection intensity observation system 66 (particularly at a wavelength of 376 nm and energy of 3). .3eV). Then, data on the reflection intensity measured by the reflection intensity observation system 66 is sent to the etching control system 68 via the signal path 67. An Ar ion laser 63 for generating excitation light for irradiating the n-type semiconductor region 24 is provided.
The excitation light 73 generated by the Ar ion laser 63 is chopped by the chopper 64 at a frequency of 200 Hz and is sent intermittently. The excitation light 73 is sent into the reaction processing chamber 50 through the end point detection window 57, and is applied to the n-type semiconductor region 24 intermittently. Then, as described above, the difference ΔR between the reflection intensity of the reflection probe light 72 (ie, the intensity of the reflection probe light 72) when the excitation light 73 is irradiated and when the excitation light 73 is not irradiated is determined by the irradiation of the excitation light 73. The value (ΔR / R) divided by the reflection intensity R when there is no reflection intensity is detected by the reflection intensity observation system 66 as the change ratio of the reflectance. Note that a polarizer may be arranged on the incident side of the probe light, and an analyzer may be arranged on the reflection side.

With the above structure, the change in the rate of change of the reflection intensity is monitored in the reaction processing chamber where the insulating film is actually formed by CVD or the like. Therefore, the film thickness of the film formed by utilizing the spectrum of light modulation reflectance spectroscopy is not limited to a clustered manufacturing apparatus but also to an apparatus that independently performs film formation such as CVD, sputtering, and thermal oxidation. Can be measured. In particular, as described in the above embodiments, in the measurement by light modulation reflectance spectroscopy,
The ellipsometry method, which is currently widely used, has the advantage that measurement can be performed in a thickness range where a measurement error is large, or in a thickness range where detection is difficult to obtain and the thickness range is too thin to detect.

(Fifth Embodiment) Next, a description will be given of a fifth embodiment relating to the measurement of light modulation reflectance for an n-type semiconductor region and a p-type semiconductor region. Although illustration of the manufacturing apparatus and the optical measurement system in the present embodiment is omitted, those in the first or fourth embodiment can be used. That is, in the following description, a measurement procedure using the clustered manufacturing apparatus and the optical measurement system shown in FIGS. 1 and 2 will be described for convenience, but the non-clustered CVD shown in FIG.
Apparatus and optical measurement systems may be used.

-Relationship Between Oxide Film Thickness and Optical Modulation Reflectance Spectroscopic Measurement Data- First, a processing wafer including a preceding wafer having an n-type semiconductor region and a p-type semiconductor region is introduced from the load chamber 6, The wafer is cleaned by the method described in the second embodiment.

Next, the surface of the wafer is oxidized to form an oxide film on the n-type semiconductor region and the p-type semiconductor region. Then, measurement samples having different film thicknesses were formed by variously changing the oxidation time, and the film thickness of each sample was measured by light modulation reflectance spectroscopy.

FIG. 11 is data showing the relationship between the film thickness obtained by TEM observation and the “peak value from the valley” in the spectrum of light modulation reflectance spectroscopy. In the same figure, ■ indicates measured value data for the oxide film on the p-type semiconductor region,
Indicates data on the oxide film on the n-type semiconductor region.
The “peak value from the valley” in FIG. 11 indicates the maximum value (positive peak value) and the minimum value (negative peak value) of the spectrum.
Shows the difference between

FIG. 12 is a view showing an actually measured spectrum before performing noise removal processing of light modulation reflectance spectrum in the n-type semiconductor region.

As shown in FIG. 11, when the thickness of the oxide film is about 1.0 nm or less, the change rate (ΔR) of the reflectance in the p-type semiconductor region is larger than that in the n-type semiconductor region.
/ R) "peak value from valley" is large, that is, the measurement sensitivity is high. On the other hand, when the thickness of the oxide film exceeds about 1.0 nm, the “peak value from the valley” in the n-type semiconductor region is higher. In the p-type semiconductor region, when the thickness of the oxide film exceeds 1.0 nm, the “peak value from the valley” tends to decrease.

On the other hand, as shown in FIG. 12, the spectrum in the n-type semiconductor region has an oxide film thickness of 0.2 n
In the vicinity of m, finding the peak portion itself due to the unevenness due to noise becomes troublesome.

The following is a summary of the above data. As the thickness of the gate insulating film increases, the electron attachment process increases, and this effect is obtained when the thickness is in the range of 0 to 2 nm. In particular, on the surface of the n-type semiconductor region, as shown in FIG. 11, the rate of change of the reflectance due to the increase in electron attachment is remarkable in the thickness range of 1 nm or more, whereas p
On the surface of the type semiconductor region, the change in the change rate of the reflectance caused by the increase in electron attachment becomes remarkable in the thickness range of 0.5 to 1.5 nm. At this time, although the signal intensity change characteristic also depends on the film forming process conditions, information on the film thickness can be obtained from the signal intensity change characteristic.

In particular, the measurement data in the p-type semiconductor region is adopted when the thickness of the oxide film is 1.0 nm or less, and the measurement data in the n-type semiconductor region is adopted when the thickness of the oxide film exceeds 1.0 nm. By adopting it, it has become possible to accurately measure the thickness of the oxide film in almost the entire range where the thickness is 1.5 nm or less, which has been difficult in the past. This effect is obtained irrespective of whether the clustered manufacturing apparatus is used.

—Management of Oxide Film Thickness— Next, a result of managing the oxide film thickness using the data shown in FIG. 11 will be described.

The light modulation reflectance spectrum of the gate oxide film on each wafer was measured, and the peak value from the valley in the spectrum of each wafer was 1.5 n as shown in FIG.
The manufacturing process was controlled so as to obtain a value corresponding to the thickness position of m.

FIG. 13 is data showing the fluctuation of the leakage current value of the gate oxide film managed by the method of controlling the thickness of the gate oxide film in this embodiment. In the figure, the horizontal axis represents the wafer number, and the vertical axis represents the variation (%) expressed as the ratio of the measured value to the standard value of the gate leak current. In addition, ○ indicates measurement data of the gate leak current of the device formed by the manufacturing process incorporating the management method of the present embodiment, and ● indicates the data formed by the conventional manufacturing process not incorporating the management method of the present embodiment. 4 shows a gate leak current of the device. As shown in the figure, since the variation in the thickness of the gate oxide film manufactured by using the management method of the present embodiment is small, it can be seen that the fluctuation amount of the gate leak current is also small.

That is, in the conventional empirical management method,
In the process of forming the gate oxide film at the 1.5 nm level, the variation in the thickness of the gate oxide film has increased with the elapse of the operation time of the manufacturing apparatus, and thus the gate oxide film has often failed. On the other hand, according to the method for controlling the thickness of the gate oxide film of the present embodiment, as shown in FIG. 13, the amount of change in the gate leak current can be suppressed small, and as a result, the occurrence of defects in the gate oxide film is reduced. We were able to. That is, a high-performance device having a gate insulating film having a thickness of 1.5 nm can be realized by the method for evaluating the film thickness and the method for manufacturing a semiconductor device according to the present embodiment.

-Management of Cleaning Step- Next, in the cleaning step (including the action of removing the oxide film) corresponding to the first embodiment, optical measurement is performed on both the p-type semiconductor region and the n-type semiconductor region. The result of measuring the thickness of the oxide film will be described.

In this case, similarly to the cleaning processing in the first embodiment, after the processing wafer including the preceding wafer (monitor wafer) is loaded from the load / unload section 6 into the load lock chamber 3, the cleaning chamber 1 Cleaning is performed for various times in the apparatus. At this time, the wafer surface is etched by radicals that have been able to dissociate the Cl ₂ gas by light irradiation to form a flat interface. For this reason, the surface of the cleaning chamber 1 is subjected to a treatment for preventing corrosion and the like.

Next, after the cleaning of the wafer, the wafer is transferred to the optical measurement chamber 5, and the optical measurement is performed by means of optical variable reflectance spectroscopy using the optical measurement system shown in FIG.

FIG. 14 shows the change of the “peak value from the valley” in the spectrum of the light modulation reflectance spectrum with respect to the cleaning time when the wafer is cleaned using the clustering apparatus shown in FIGS. Data. In the figure, ■ indicates a measured value in the p-type semiconductor region, and ● indicates a measured value in the n-type semiconductor region. The data for the n-type semiconductor region apparently differs from the data shown in FIG. 4 because the data processing method is different between FIG. 4 and FIG. Both data show the same trend. In any of the regions, the film thickness is large while the cleaning time is insufficient and the oxide film cannot be sufficiently removed, and the film thickness of the oxide film decreases when the cleaning is sufficiently performed. I have.

Here, the n-type semiconductor region and p in FIG.
Comparing the data for the n-type semiconductor region, the peak value from the valley is higher in the n-type semiconductor region until the cleaning time reaches 3.0 to 4.0 × 10 ² sec. If it exceeds 0 to 4.0 × 10 ² sec, the peak value from the valley is higher in the p-type semiconductor region. this is,
As long as the cleaning time is insufficient and the oxide film is not so thin, higher measurement sensitivity and measurement accuracy can be obtained by using data of the n-type semiconductor region, but the cleaning time is longer and the oxide film is removed. It indicates that higher measurement sensitivity and higher measurement accuracy can be obtained by using the measurement data in the p-type semiconductor region. This tendency is consistent with the tendency shown by the data in FIG.

Therefore, in the cleaning step, light modulation reflectance spectroscopy is performed on the n-type semiconductor region and the p-type semiconductor region to obtain data (ΔR / R) showing higher sensitivity.
By controlling the cleaning conditions and the cleaning time while monitoring the thickness of the oxide film by utilizing the method, the cleaning accompanied by the removal of the oxide film can be necessary and sufficiently performed.

Also, from the data of FIG.
It can be seen that, when the oxide film is formed by the method described above, a measurement value having a slope opposite to each characteristic line shown in FIG. That is, using the data shown in FIG. 14, it is also possible to control the film thickness when forming a thermal oxide film or a CVD oxide film on the p-type semiconductor region and the n-type semiconductor region.

(Other Embodiments) In the first to third embodiments, in the clustered manufacturing apparatus,
As shown in FIG. 1, a cleaning chamber 1, a high-speed oxidation chamber 2 for forming an oxide film, a cooling chamber 4, and an optical measurement chamber 5 are arranged around a load lock chamber 3. The wafers can be transferred under reduced pressure without being exposed to the atmosphere between the chambers, but the present invention is not limited to such an embodiment. For example,
Instead of the apparatus shown in FIG. 1, the following clustered manufacturing apparatus configuration is possible.

First, an optical measurement system may be provided in the wafer cooling chamber 4 without separately providing the optical measurement chamber 5.

Second, instead of the high-speed oxidation chamber 2, an oxide film, a nitride film,
A chamber for forming a polysilicon film may be provided.

Third, in addition to the high-speed oxidation chamber 2,
A chamber for forming an oxide film, a nitride film, and a polysilicon film by sputtering or CVD may be provided. In particular, if a polysilicon film can be formed in this manufacturing apparatus after forming a gate oxide film, a polysilicon film for forming a gate electrode can be formed before a natural oxide film is formed on a wafer on which the gate oxide film is formed. There is an advantage that a silicon film can be formed.

It is also possible to provide a monitor area where a semiconductor device to be a product is not formed on a part of the wafer, and perform the above-described optical measurement on the semiconductor area in the monitor area. In that case, the measurement sensitivity can be increased by setting the impurity concentration in the semiconductor region in the monitor region higher than the impurity concentration in the semiconductor region in the semiconductor device to be a product. In addition, since the monitor area can be secured in a large area, there is an advantage that optical measurement can be easily performed.

The film whose thickness can be measured by light modulation reflectance spectroscopy of the present invention may be made of a material having a property of transmitting light (including ultraviolet rays). Therefore, it is not limited to an insulating film such as an oxide film, but may be a transparent conductive material or a thin metal film capable of transmitting light.
In particular, even if the film is made of the same material, the light is easily transmitted as the film becomes thinner, so that the limitation of the material to which the invention can be applied is eased.

Further, the structure of the optical measurement system suitable for the clustered manufacturing apparatus can also take the following forms.

FIG. 15 is a cross-sectional view showing an example of a structure when optical measurement systems are collectively arranged on the ceiling surface of a chamber. As shown in the figure, all the optical systems are arranged on the ceiling side of the optical measurement chamber 5 connected to the load lock chamber 3 in the clustered manufacturing apparatus. That is, a quartz window 23 for passing measurement light and excitation light is attached to the ceiling surface of the optical measurement chamber 5. Then, an incident measuring light introducing unit 24 and a reflected measuring light deriving unit 25 are mounted on the quartz window 23. Further, a light source 7 for excitation light (Ar ion laser)
A light source 8 for measuring light (150 W Xe lamp), a photodetector 9 for detecting the intensity of reflected light of the measuring light, and a light from the light source 8 for measuring light guided to the measuring light introducing unit 24. An optical fiber 11, an optical fiber 12 for guiding the light from the measuring light guide 25 to the photodetector 9, and a light source 7 for the excitation light.
A chopper 28 for intermittently irradiating (modulating) the device under test with the excitation light generated at the frequency of 500 Hz,
A control / analysis system 13 having a monitor and a CPU for controlling equipment and calculating and analyzing data during measurement by light modulation reflectance spectroscopy; a chopper 28 and a CPU in the control / analysis system 13; And a signal line 30 connecting between the two. Here, the incident measurement light introducing unit 2
4 and the reflection measurement light deriving unit 25 also have a function as an optical fiber support device, respectively. Then, the wafer stage 21 placed in the optical measurement chamber 5
The wafer 22 is placed on the upper surface, and the light modulation reflectance spectral measurement as described above is performed.

FIG. 16 is a cross-sectional view showing an example of a structure in the case where the angle of incidence of the measuring light on the object to be measured is large. As shown in the figure, a quartz window 23 for passing measurement light and excitation light is attached to the ceiling surface of the optical measurement chamber 5. Then, an optical fiber support device 44 for introducing excitation light is mounted on the quartz window 23. A measuring light introducing optical fiber support device 40 and a measuring light introducing unit 41, and a measuring light deriving unit 42 and a measuring light deriving optical fiber supporting device 43 are attached to the side of the optical measuring chamber 5. Further, although not shown, a light source for excitation light (Ar ion laser) and a light source for measurement light (X of 150 W) are provided outside the clustered manufacturing apparatus.
e-lamp) and a photodetector for detecting the intensity of the reflected light of the measurement light. An optical fiber 10 for guiding light from the excitation light source to the optical fiber support device 44 for introducing excitation light, an optical fiber 11 for guiding light from the light source for measurement light to the optical fiber support device 40 for introducing measurement light, Lead-out optical fiber support device 2
And an optical fiber 12 for guiding light from 5 to a photodetector. The excitation light is configured to be intermittently applied to the device under test at a frequency of 500 Hz by a chopper provided at a position (not shown). Further, a control / analysis system having a monitor and a CPU for controlling equipment and calculating and analyzing data at the time of measurement by light modulation reflectance spectroscopy is provided.

FIG. 17 is a cross-sectional view showing a structural example in which an optical measurement system is further integrated and mounted on the ceiling surface of the optical measurement chamber 5. A quartz window 23 is attached to the ceiling surface of the optical measurement chamber 5,
The spherical member 45 is mounted on the third member 3. The surface shape of the spherical member 45 substantially matches the spherical surface of the wafer 22 centered on the measured portion. The spherical member 45 includes a measuring light introducing optical fiber supporting device 40 supporting the optical fiber 11, a measuring light guiding optical fiber supporting device 41 supporting the optical fiber 12, and an excitation light introducing optical fiber supporting device 44 supporting the optical fiber 10. Is attached. Further, the measuring light introducing optical fiber support device 40 and the measuring light deriving optical fiber supporting device 41
The rack and pinion mechanism and the like are configured to be movable along the slope of the spherical member 45 while always keeping the same inclination angle from the perpendicular to each other. Then, the rack and pinion mechanism is operated by remote control from the outside of the clustered manufacturing apparatus, so that the measuring light introducing optical fiber supporting device 40 and the measuring light guiding optical fiber supporting device 41 are operated.
Is configured to be able to adjust the angle of inclination from the perpendicular. That is, the angle of incidence of the measurement light on the wafer 22 on the wafer stage 21 installed in the optical measurement chamber 5 can be adjusted. With such a structure, the light introduction / departure portion of the optical measurement system can be concentrated in a very small space, and is particularly suitable for mounting on a clustered manufacturing apparatus.

[0123]

According to the semiconductor device manufacturing apparatus of the present invention, a plurality of processing chambers for performing various kinds of processing on wafers are arranged in a clustered state in a common container which is isolated from the atmosphere. The optical measurement means for optically evaluating the surface state of the wafer with the wafer installed in any part of the wafer is provided, so that the oxide film on the wafer is not affected by the natural oxide film etc. The presence or absence, the thickness of an oxide film, and the like can be measured with high precision, and a semiconductor device manufacturing apparatus having a function of appropriately managing the manufacturing process of a miniaturized semiconductor device can be obtained.

According to the first method of manufacturing a semiconductor device of the present invention, the thickness of the film when forming or removing the film is measured by light modulation reflectance spectroscopy. Sensitivity that cannot be obtained by film thickness measurement
The film thickness can be measured with high accuracy.

According to the second method of manufacturing a semiconductor device of the present invention, a film is formed on a semiconductor region or a film is removed from a semiconductor region in a common container which is operated in an atmosphere shielded from the atmosphere. Since the thickness of the film is measured from the optical evaluation of the region, the semiconductor device can be manufactured using the in-line optical evaluation in the clustered device.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a configuration of an apparatus for manufacturing a clustered semiconductor device used in first to third embodiments of the present invention.

FIG. 2 is a sectional view schematically showing a configuration of an optical measuring mechanism used in the first to third embodiments of the present invention.

FIG. 3 is a reflectance spectrum diagram showing a result of light modulation reflectance spectroscopy in the first embodiment.

FIG. 4 is data showing a relationship between a cleaning time and a peak value in a spectrum of light modulation reflectance spectroscopy in the first embodiment.

FIG. 5 is a reflectance spectrum diagram showing a result of light modulation reflectance spectroscopy of various oxide films in the second embodiment.

FIG. 6 is data showing a relationship between a film thickness obtained by TEM observation and a peak value in a spectrum of light modulation reflectance spectroscopy in the second embodiment.

FIG. 7 is a copy of a TEM image of a cross-sectional structure of an oxide film and a polysilicon film deposited on a silicon substrate.

FIG. 8 is a diagram showing a spectrum of light modulation reflectance spectroscopy before and after performing a heat treatment on a 3.5-nm-thick oxide film in a third embodiment.

FIG. 9 is a spectral diagram showing a basic shape of light modulation reflectance spectrum obtained by the present invention.

FIG. 10 is a cross-sectional view schematically showing a configuration for performing optical measurement in a single chamber in a fourth embodiment.

FIG. 11 is data showing a relationship between a film thickness by TEM observation and a peak value from a valley in a spectrum of light modulation reflectance spectroscopy in the fifth embodiment.

FIG. 12 is a diagram showing an actually measured spectrum before performing noise removal processing of light modulation reflectance spectrum in an n-type semiconductor region in a fifth embodiment.

FIG. 13 is data showing a change in a leak current value of a gate oxide film managed by the gate oxide film thickness management method according to the fifth embodiment.

FIG. 14 shows a change in a peak value from a valley in a spectrum of light modulation reflectance spectrum with respect to a cleaning time when a wafer is cleaned using the clustering apparatus shown in FIGS. 1 and 2 in the fifth embodiment. It is the data shown.

FIG. 15 is a cross-sectional view showing a structural example when optical measurement systems are collectively arranged on a ceiling surface of a chamber in another embodiment.

FIG. 16 is a cross-sectional view illustrating a structural example in a case where the angle of incidence of measurement light on an object to be measured is large in another embodiment.

FIG. 17 is a cross-sectional view showing a structural example when an optical measurement system is further integrated and mounted on a ceiling surface of an optical measurement chamber in another embodiment.

FIG. 18 is a cross-sectional view showing a manufacturing process in which a series of processes of cleaning and forming a gate insulating film is performed on a wafer without using a clustered manufacturing apparatus.

FIG. 19 is a cross-sectional view showing a manufacturing process in which a series of processes of cleaning and forming a gate insulating film is performed on a wafer using a clustered manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cleaning chamber 2 High-speed oxidation chamber 3 Load lock chamber 4 Wafer cooling chamber 5 Optical measurement chamber 6 Wafer loading / unloading section 7 Light source for excitation light (Ar ion laser) 8 Light source for measurement light (Xe lamp) Reference Signs List 9 photodetector 10-12 optical fiber 13 control / analysis system 30 signal line 21 wafer stage 22 wafer 23 quartz window 24 incident measuring light introducing unit 25 reflection measuring light deriving unit 26 excitation light introducing unit 27 light shielding plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/304 645 H01L 21/31 B 21/31 21/302 N

Claims (21)

[Claims] A plurality of processing chambers for performing processing on a wafer having a semiconductor region; a common container surrounding the space including the plurality of processing chambers so as to maintain an atmosphere shielded from the atmosphere; A transfer unit for transferring the wafer, and an optical measurement unit for optically evaluating the surface state of the wafer in a state where the wafer is installed in any part of the common container. An apparatus for manufacturing a semiconductor device, comprising: 2. The apparatus for manufacturing a semiconductor device according to claim 1, wherein said optical measuring means comprises: a first light source for generating excitation light; a second light source for generating measuring light; A first light guide member for intermittently irradiating the semiconductor region of the wafer in the common container with excitation light generated by the light source; and irradiating the semiconductor region with measurement light generated by the second light source. A second light guide member, a reflectance detecting unit for detecting a reflectance of the measuring light applied to the semiconductor region, and a measuring light reflected from the semiconductor region to the reflectance detecting unit. A third light guide member for causing the light to enter, and a reflectance of the measurement light when the semiconductor region is irradiated with the excitation light and when the excitation light is not irradiated by receiving the output of the reflectance detection means. The difference between the above is not irradiated with the excitation light Apparatus for manufacturing a semiconductor device according to claim to have a change calculation means for calculating a value obtained by dividing the reflectance of the Kino measurement light as the change rate of the reflectance of the measurement light. 3. The semiconductor device manufacturing apparatus according to claim 1, wherein the plurality of processing chambers include a processing chamber for performing a cleaning process including an etching action on the wafer, and a film formed on a semiconductor region of the wafer. And a processing chamber for forming a semiconductor device. 4. The apparatus for manufacturing a semiconductor device according to claim 1, further comprising an optical measuring chamber provided in said common container, wherein said optical measuring means is provided with said optical measuring means. An apparatus for manufacturing a semiconductor device, wherein the apparatus is provided in a physical measurement chamber. 5. The semiconductor device manufacturing apparatus according to claim 4, wherein said optical measurement chamber also functions as a cooling chamber for cooling a wafer. 6. The semiconductor device manufacturing apparatus according to claim 3, wherein the processing chamber for forming a film on the wafer is configured to form an oxide film by performing a thermal oxidation process on a semiconductor region of the wafer. An apparatus for manufacturing a semiconductor device, comprising: a processing chamber provided in the common container and configured to form a conductive film on the oxide film. 7. A method for manufacturing a semiconductor device including a process of forming a film on a semiconductor region of a wafer or removing a film on a semiconductor region of a wafer, wherein the semiconductor region of the wafer is irradiated with measurement light. Step (a), step (b) of irradiating the semiconductor region of the wafer intermittently with excitation light, and step (b) when the semiconductor region of the wafer is irradiated with excitation light and when it is not irradiated with excitation light. (C) calculating a value obtained by dividing the difference in reflectance of the measurement light by the reflectance of the measurement light when the excitation light is not irradiated, as a change ratio of the reflectance. A method for manufacturing a semiconductor device, comprising: determining a thickness of the film based on a ratio. 8. The method of manufacturing a semiconductor device according to claim 7, wherein in the step (c), a spectrum of a change ratio of a reflectance when a wavelength of the measurement light is changed is created, and the reflection is performed. A method for manufacturing a semiconductor device, comprising: determining a thickness of the film based on a peak value that is a maximum value of an absolute value of a rate of change of a rate. 9. The method of manufacturing a semiconductor device according to claim 7, wherein in the step (c), a spectrum of a change ratio of a reflectance when a wavelength of the measurement light is changed is created, and the reflection is performed. A method of manufacturing a semiconductor device, comprising: determining a thickness of a film based on a peak value from a valley, which is a difference between a positive maximum value and a negative maximum value of a rate of change of a rate. 10. The method of manufacturing a semiconductor device according to claim 7, wherein in the step (c), the constant value close to a wavelength of the measuring light having a peak value which is a maximum value of the absolute value of the change rate of the reflectance. A method for manufacturing a semiconductor device, wherein a thickness of the film is obtained based on a change ratio of a reflectance at a wavelength. 11. The method for manufacturing a semiconductor device according to claim 7, wherein said film has a thickness of 2 nm or less. 12. The method of manufacturing a semiconductor device according to claim 11, wherein when the thickness of the film is 1 nm or less, the optical evaluation is performed on a p-type semiconductor region as the semiconductor region. Device manufacturing method. 13. The method for manufacturing a semiconductor device according to claim 7, wherein the thickness of the film is measured for both a p-type semiconductor region and an n-type semiconductor region as the semiconductor region. A method of manufacturing a semiconductor device, wherein a measured value in a semiconductor region exhibiting a large value in a change ratio of the reflectance between the p-type semiconductor region and the n-type semiconductor region is adopted as the thickness of the film. 14. The method for manufacturing a semiconductor device according to claim 12, wherein the resistivity of the semiconductor region is 0.1 Ωcm ⁻¹ or less. 15. A plurality of processing chambers, a common container surrounding the space including the plurality of processing chambers so as to maintain an atmosphere shielded from the atmosphere, and a transfer unit for transferring a wafer in the common container. A method of manufacturing a semiconductor device using a clustered semiconductor device manufacturing apparatus, comprising: forming a film on a wafer or removing a film on a wafer in one of the plurality of processing chambers. (A) performing the step, and (b) determining the thickness of the film by optically evaluating the surface state of the wafer at any site in the common container. Manufacturing method of a semiconductor device. 16. The method for manufacturing a semiconductor device according to claim 15, wherein said step (b) comprises: a sub-step (x) of irradiating the semiconductor region of said wafer with measurement light; (Y) intermittently irradiating the excitation light; and determining the difference in the reflectance of the measurement light between when the semiconductor region of the wafer is irradiated with the excitation light and when the excitation light is not irradiated. (Z) calculating a value obtained by dividing the reflectance of the measurement light when not radiated as a reflectance change rate, and calculating the thickness of the film based on the reflectance change rate. A method for manufacturing a semiconductor device. 17. The method of manufacturing a semiconductor device according to claim 16, wherein said step (a) includes a process of removing a natural oxide film on a wafer, and said step (b) includes a step of removing a thickness of said natural oxide film. And a method for manufacturing a semiconductor device. 18. The method for manufacturing a semiconductor device according to claim 16, wherein said step (a) includes a process of forming a gate insulating film on a wafer, and said step (b) includes a step of forming a thickness of said gate insulating film. And a method for manufacturing a semiconductor device. 19. The method of manufacturing a semiconductor device according to claim 18, wherein said step (a) further includes a step of forming a conductor film for a gate electrode on said gate insulating film. And a step (c) of managing the thickness of the gate insulating film based on the change ratio of the reflectance obtained in the step (b) before forming the conductor film for the gate electrode. A method for manufacturing a semiconductor device. 20. The method of manufacturing a semiconductor device according to claim 16, wherein in the step (b), the reflectance is set for both the p-type semiconductor region and the n-type semiconductor region. Measuring the rate of change of the reflectance of the p-type semiconductor region and the n-type semiconductor area, and determining the remaining thickness of the native oxide film based on the dependency characteristic indicating the larger value of the rate of change of the reflectance. A method for manufacturing a semiconductor device. 21. The method of manufacturing a semiconductor device according to claim 16, wherein said film has a thickness of 2 nm or less.