JP4257140B2 - Metal oxide insulating film thickness evaluation apparatus and film quality evaluation apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal oxide insulating film thickness evaluation apparatus and film quality evaluation apparatus.
[0002]
[Prior art]
[Non-Patent Document 1]
Hitachi Kokusai Electric 49th Spring Applied Physics Related Conference Proceedings 28p-A-11-14)
In recent years, with high integration of semiconductors, metal oxides having a high dielectric constant are used for the insulating films. For example, Al ₂ O ₃ and HfO ₂ are known as the metal oxide insulating film. As a technique for forming such a metal oxide insulating film, for example, ALD (Atomic Layer Deposition); ) Method and MOCVD method (metal organic chemical vapor deposition method). Before SL ALD method (see Non-Patent Document 1), when using, for example, trimethyl aluminum: using (TMA Al (CH _{3) 3)} and water vapor (H ₂ O), the Si substrate of these raw materials are alternately The Al ₂ O ₃ film is formed by spraying. At this time, the CH ₃ group (methyl group) constituting the raw material is taken into the film, and this acts as an impurity (C _X H _y ), thereby deteriorating the film quality.
[0003]
The HfO ₂ thin film is formed on the Si substrate by MOCVD using Hf [N (C ₂ H ₅ ) ₂ ] ₄ and O ₂ gas that do not contain oxygen in the molecular structure. FIG. 7 shows experimental data D obtained by measuring the relative dielectric constant of the HfO ₂ thin film with respect to the film formation temperature. From FIG. 7, it can be seen that the relative dielectric constant increases when the film forming temperature is 190 to 280 ° C. This is considered to be due to an increase in the density of the HfO ₂ thin film accompanying an increase in the film formation temperature. In addition, it can be seen from FIG. 7 that the relative dielectric constant decreases when the film forming temperature is 400 ° C. This is presumably because the interdiffusion of component elements between the Si substrate and the HfO ₂ thin film becomes significant, and the Si element is mixed into the HfO ₂ thin film. The reason why the relative permittivity further increases at the film forming temperature of 450 ° C. is considered to be due to the increase in the density of the HfO ₂ thin film.
[0004]
[Problems to be solved by the invention]
Incidentally, there has been a demand for a simple apparatus for evaluating the film thickness and / or film quality of the metal oxide insulating film immediately after film formation or after annealing. In particular, metal oxide insulating films are subject to film deterioration due to contamination by impurities and mutual diffusion of each component element between the film and the substrate, depending on various conditions such as the temperature at the time of film formation and the temperature and time at the time of annealing. appear.
[0005]
The present invention has been made in consideration of the above-mentioned matters, and its purpose is to evaluate the film thickness and film quality of a metal oxide insulating film and to confirm the degree of film quality deterioration and the relative dielectric constant. An object of the present invention is to provide a film thickness evaluation apparatus and a film quality evaluation apparatus for an object insulating film.
[0006]
[Means for Solving the Problems]
To achieve the above object, the present invention film Atsuhyo valent device metal oxide insulating film by sputtering by glow discharge in the formed metal oxide dielectric film surface on a semiconductor substrate of a metal oxide insulating film an apparatus for evaluating the film thickness of the metal oxide insulating film by a line cormorants glow discharge analysis means the component analysis in the depth direction, each component of the obtained in the glow discharge analysis means metal oxide insulating film Means for measuring the film thickness of the metal oxide insulating film based on the position of the inflection point obtained by second-order differentiation of the element characteristic curve , and the measured film thickness is a component element in the metal oxide insulating film and a means for determining whether exceeded a predetermined threshold value or range set in advance corresponding to the further characterized in that the predetermined threshold value or range is a storage unit that is stored And
[0007]
[0008]
The apparatus for evaluating the quality of a metal oxide insulating film according to the present invention performs component analysis in the depth direction of the metal oxide insulating film by sputtering using glow discharge on the surface of the metal oxide insulating film formed on the semiconductor substrate. an apparatus for evaluating the film quality of the metal oxide insulating film using earthenware pots glow discharge analysis means, by comparing the quality of the metal oxide insulating film after the annealing and after the metal oxide insulating film, the semiconductor The component concentration characteristic curve obtained by glow discharge analysis means to find the annealing conditions of temperature and time by evaluating the degree of interdiffusion of the component elements between the substrate and the metal oxide insulating film , in the metal oxide insulating film Yes inclination of the component elements will index indicating the degree of diffusion of the constituent elements of the semiconductor substrate, means for determining whether exceeded a predetermined threshold value or range set in advance And wherein the Rukoto.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereby.
[0010]
1 to 6 show an embodiment of the present invention. In an embodiment of this employs the HfO ₂ thin film as a metal oxide insulating film. That is, as shown in FIG. 2, the H fO ₂ thin film 11 has a natural oxide film (SiO ₂ ) 12 attached by MOCVD using Hf [N (C ₂ H ₅ ) ₂ ] ₄ and O ₂ gas as raw materials. It is formed on a p-type Si (100) substrate 13. Then, 59, HfO ₂ thin film 11, a base portion of a semiconductor chip having a natural oxide film (SiO ₂₎ 12 and the Si substrate 13.
[0011]
First, the Marcus type high-frequency glow discharge analyzer 1 as a glow discharge analysis means will be briefly described.
[0012]
As shown in FIG. 1, the glow discharge analysis apparatus 1 includes a glow discharge tube 2 for generating a glow discharge in the HfO ₂ thin film 11, a power supply unit 3 for supplying high-frequency power to the glow discharge tube 2, not A gas supply unit 4 that supplies a gas necessary for measurement of active gas or the like, a spectroscope 5 that splits the light L generated from the discharge light emitting unit 2a of the glow discharge tube 2 and measures the intensity thereof, and the measurement of the light L An arithmetic processing unit 6 that mainly obtains and outputs the concentration of the measurement target component (Hf, O component, residual impurities such as C, N, and H) based on the value is mainly provided. Reference numeral 7 denotes a display of the arithmetic processing unit 6.
[0013]
The glow discharge tube 2 includes a condensing lens 2b, and the spectroscope 5 includes a slit 5a that transmits light L at a focal position of the condensing lens 2b, and a diffraction grating 5b that disperses the light L transmitted through the slit 5a. If has a slit 5 c to transmit light split into wavelengths corresponding to the respective measurement target component, a photomultiplier tube for detecting the intensity of light transmitted through the slit 5 c (or the solid state detector) and 5d ing.
[0014]
The power supply unit 3 supplies high-frequency AC power of , for example, 13 MHz. The gas supply unit 4 is as the inert gas such as argon gas Ar and the oxygen gas O ₂ and a cylinder 4a and the electromagnetic valve 4b respectively supply.
[0015]
In measurement, the glow discharge tube 2 preliminary discharge occurs between the anode and the HfO ₂ thin film 11, which argon ions are generated on the basis of, the argon ions are accelerated by a high electric field, the HfO ₂ film 11 It collides with the surface and emits light. Then , predetermined sputtering is performed by the collision of argon ions, and particles (including atoms and molecules) containing ions are ejected from the surface of the HfO ₂ thin film 11, and when these particles are excited in the plasma and return to the ground state. The element emits light unique to the element. These light L is derived in the spectrometer 5 direction which is connected to the glow discharge tube, a qualitative analysis is performed.
[0016]
The arithmetic processing unit 6, the measurement value data 30 indicating the measured values for the sputtering time thus detected measurement value to the photomultiplier 5 d and the relationship of the measurement time when that caused Jo Tokoro time continuously glow discharge Is stored in the storage unit 6m of the arithmetic processing unit 6.
[0017]
The arithmetic processing unit 6, the intensity of light measured components of the respective wavelengths thus detected photomultiplier 5 d using measurements data 30 (Hf, components of O, C, N, such as H Quantitative analysis is performed by converting to the concentration of residual impurities. Further, this measured value (intensity or concentration) is calculated in consideration of the progress speed of sputtering obtained from the magnitude of the electric power supplied to the glow discharge tube 2 and the measured concentration of each component. And the arithmetic processing part 6 memorize | stores the relationship between the depth position of a sample and the density | concentration of each measuring object component in the memory | storage part 6m as the conversion value data 31 which shows the relative intensity change ratio with respect to sputtering depth.
[0018]
The measurement value data 30 needs to be accumulated simultaneously with the glow discharge, but the conversion value data 31 can be created and stored by calculation based on the measurement value data 30. Therefore, the conversion of the measured value data 30 can be performed according to the user's operation after a series of glow discharges is completed.
[0019]
Figure 3 shows with a front Symbol glow discharge analyzer 1, an example of a result calculated by the calculation processing unit 6 when analyzing HfO ₂ thin film 11 immediately after the film formation (see Fig. 2). In FIG. 3, the horizontal axis represents the sputtering speed (T), and the vertical axis represents the light intensity (I). Then, 20 of Hf (Hafuniu beam) characteristic curve in HfO ₂ thin film 11, 21 is the C (carbon containing) characteristic curve in HfO ₂ thin film 11, O (oxygen) characteristics in HfO ₂ thin film 11 is 22 the curve 23 is the H (hydrogen) characteristic curve in HfO ₂ thin film 11, 24 are respectively the N (nitrogen) characteristic curve in HfO ₂ thin film 11. Then, 25 components characteristic curve of the Si substrate, i.e., the S i characteristic curve, 25a denotes a natural oxide film of Si characteristic curve in (SiO ₂₎ 12, respectively. Also, A is shows the HfO ₂ thin film region, B denotes an Si substrate region. The position of the T = 0 corresponds to the surface 11a position of HfO ₂ thin film 11 is the start position of the sputtering by glow discharge.
[0020]
The characteristic configuration of the present invention will be described below.
[0021]
In Figure 1, 39 is a device for evaluating the thickness and quality of the metal oxide insulating film (HfO ₂ film) 11, the thickness and quality evaluation apparatus 39, the S i characteristic curve 25 or,, HfO ₂ A means 40 for measuring the film thickness d of the HfO ₂ thin film based on the characteristic curves 20 to 24 of each component element in the thin film 11, and a predetermined threshold value or a predetermined range in which the measured film thickness d is set in advance. and a determining means 41 whether or not exceeded. The determination means 41 includes a storage unit 41a in which a predetermined threshold value or a predetermined range corresponding to each component element in the HfO ₂ thin film 11 is stored, and a predetermined value corresponding to each component element in the HfO ₂ thin film 11. with an input section 41b for inputting a threshold value or a predetermined range, the measured thickness d is provided with a means 42 for outputting an alarm signal to the threshold value or a predetermined range when is exceeded.
[0022]
Then, the film thickness d is, the inflection points obtained by the characteristic curve 20 to 24 of the respective component elements of the glow discharge spectrometer during the previous SL H fO ₂ thin film 11 obtained in 1 second derivative and Ru is measured positions based on. 4, 60 denotes an inflection point obtained by the S i characteristic curve 25 in the Si substrate 13 and second derivative. Further, 61 indicates an inflection points obtained the H f characteristic curve in HfO ₂ thin film 11 20 secondary differentiation on.
[0023]
The front Symbol evaluation device 39, in HfO ₂ thin film 11 obtained in the glow discharge analysis apparatus 1, the concentration of each component including residual impurities (Hf, O, C, N and H, etc.) value has a determining means 44 whether exceeded a predetermined threshold value or a predetermined range which is set in advance, respectively, further, the alarm signal the concentration of each component of the threshold value or a predetermined range when is exceeded, respectively Is provided.
[0024]
FIG. 5A plots the amount of residual C in the HfO ₂ thin film 11 for each film formation temperature. FIG. 5A shows that the residual C amount decreases as the film forming temperature increases. That is, the temperature at the time of film formation is determined from the residual amount of residual impurities other than the HfO ₂ thin film component in Hf [N (C ₂ H ₅ ) ₂ ] ₄ which is a raw material for forming the HfO ₂ thin film 11. can do. That is, by monitoring the concentration of residual impurities, it is possible to perform evaluation during film formation.
In this embodiment, an example is shown in which the evaluation at the time of film formation is monitored using the concentration of residual impurities. Naturally, the value to be monitored means the concentration of each component element, and before conversion to each concentration value. The intensity values may be as follows.
[0025]
5B and 5C are plots of the residual N amount and the residual H amount in the HfO ₂ thin film 11 for each film formation temperature, respectively.
[0026]
These are analyzed by the glow discharge analyzer 1, but can evaluate the results of this analysis in the previous SL evaluation device 39 can confirm the degree of quality deterioration.
[0027]
Incidentally, to evaluate the quality, each measuring the slope of each component density characteristic curves obtained by the glow discharge analyzer 1, the predetermined threshold value or a predetermined range of these slopes is preset ultra Etaka determine whether each slope may be configured to output an alarm signal if is exceeded a predetermined threshold value or range. That, Hf concentration characteristic curve in HfO ₂ thin film 11 obtained by the glow discharge analyzer 1, C concentration characteristic curves in HfO ₂ thin film 11, O concentration characteristic curves in HfO ₂ thin film 11, HfO ₂ thin film H concentration characteristic curve in 11, N concentration characteristic curves in HfO ₂ thin film 11, a predetermined inclination of the characteristic curves based on S i concentration curve of 13 in the Si substrate is set in advance Film quality can be assessed by determining whether a threshold or range has been exceeded. In FIG. 6, 20 ′ represents a Hf concentration characteristic curve in the HfO ₂ thin film 11 obtained by the glow discharge analyzer 1, and 25 ′ in the Si substrate 13 obtained by the glow discharge analyzer 1. It shows the S i concentration characteristic curve. Each slope of these characteristic curves, ing the index indicating the respective degree of diffusion. And each inclination in each concentration characteristic curve of other component elements obtained also becomes an index which shows the diffusion degree of each other component element.
[0028]
And, of course immediately after formation of the HfO ₂ thin film 11, by performing the evaluation in the previous SL evaluation device 39 also after annealing or the like, the degree of interdiffusion of constituent elements between the Si substrate 13 and HfO ₂ thin film 11 Can be judged. That is, the respective characteristic curves 20-25 immediately after formation of the film shown in FIG. 3 was varied after annealing, can compare the film quality of each characteristic curve corresponding to the characteristic curve 20-25, interdiffusion during annealing Can also be evaluated. This evaluation is very useful for finding annealing conditions (temperature and time).
[0029]
Thus, by evaluating the film thickness d and the film quality of the HfO ₂ thin film 11, the degree of film quality deterioration and the relative dielectric constant can be confirmed, and a reliable and high-quality semiconductor chip can be obtained. it can be supplied.
In this embodiment, the case of the HfO ₂ thin film 11 has been described. However, the present invention is not limited to this, and any metal oxide insulating film can be applied. The metallic oxide insulating film other than HfO ₂ thin film 11, for example, a _{ZrSiO 4, HfSiO 4, ZrO 2} , Ta 2 O 5 or the like.
[0030]
【The invention's effect】
As described above, according to the present invention, metal oxide insulating film which can confirm the size of the extent and relative dielectric constant of the evaluation to quality deterioration of the thickness and quality of the metal oxide insulating film Ru can be obtained thickness evaluation device and the film quality evaluation apparatus.
[Brief description of the drawings]
FIG. 1 is an overall configuration explanatory view showing an embodiment of the present invention.
FIG. 2 is a structural explanatory view showing a semiconductor including an HfO ₂ thin film used in the embodiment.
FIG. 3 is a diagram showing an analysis result of the HfO ₂ thin film used in the embodiment.
FIG. 4 is a diagram for explaining a method for measuring the film thickness of the HfO ₂ thin film used in the embodiment.
FIG. 5A is a plot diagram showing the amount of residual C in the HfO ₂ thin film used for evaluating the film quality of the HfO ₂ thin film used in the embodiment.
(B) is a plot diagram showing the amount of residual N in the HfO ₂ thin film used for evaluating the film quality of the HfO ₂ thin film used in the embodiment.
(C) is a plot diagram showing the amount of residual H in the HfO ₂ thin film used for evaluating the film quality of the HfO ₂ thin film used in the embodiment.
FIG. 6 is a diagram showing component element (Hf, Si) concentration characteristic curves used in another film quality evaluation method for the HfO ₂ thin film used in the embodiment.
FIG. 7 is a diagram showing experimental data obtained by measuring a relative dielectric constant of an HfO ₂ thin film with respect to a film formation temperature.
[Explanation of symbols]
1 ... RF glow discharge spectrometer, 11 ... metal oxide insulating film, 11a ... metal oxide surface of the insulating film, 13 ... semiconductor substrate, 39 ... film thickness and film quality evaluation apparatus of the metal oxide insulating film, 40 ... Means for measuring the film thickness of the metal oxide insulating film, 41... Means for determining whether or not the measured film thickness exceeds a predetermined threshold value, 42... Alarm signal output means, 61. , d ... thickness.

Claims (5)

The film thickness of the metal oxide insulating film by a line cormorants glow discharge analysis means the component analysis in the depth direction of the metal oxide insulating film by sputtering by glow discharge in the formed metal oxide dielectric film surface on a semiconductor substrate The metal oxide is based on the position of the inflection point obtained by second-order differentiation of the characteristic curve of each component element in the metal oxide insulating film obtained by the glow discharge analysis means. and means for measuring the thickness of the insulating film, means for determining whether the film was measured thickness has exceeded a predetermined threshold value or range set in advance corresponding to the component elements in the metal oxide dielectric film the a, further, the predetermined metal oxide insulating film of film Atsuhyo value and wherein the threshold or range is provided with a storage unit stored. The measured thickness film Atsuhyo valent device metal oxide insulating film according to claim 1, further comprising means for outputting a signal when a predetermined threshold value or range of the set in advance is exceeded. By sputtering by glow discharge to formed on a semiconductor substrate a metal oxide insulating film surface of the metal oxide insulating film in the depth direction component analysis using a row cormorants glow discharge analysis means film quality of the metal oxide insulating film The degree of mutual diffusion of component elements between the semiconductor substrate and the metal oxide insulating film by comparing the film quality of the metal oxide insulating film immediately after the formation of the metal oxide insulating film and after the annealing The degree of diffusion of the component elements in the metal oxide insulating film and the constituent elements of the semiconductor substrate of the component concentration characteristic curve obtained by the glow discharge analysis means for evaluating the temperature and time annealing conditions is shown. slope becomes index, film quality evaluation apparatus of the metal oxide insulating film, characterized in that it comprises means for determining whether exceeded a predetermined threshold value or range set in advance. Film quality evaluation apparatus of the metal oxide insulating film according to claim 3, wherein the slope is provided with a means for outputting a signal if is exceeded a predetermined threshold value. A means for determining the degree of mutual diffusion of component elements between the semiconductor substrate and the metal oxide insulating film, and by monitoring the concentration or light intensity of the component elements remaining in the metal oxide insulating film, things insulating film film quality evaluation apparatus of the metal oxide insulating film according to claim 3 or claim 4 is configured to determine the temperature at the time of formation.

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