JP2000077494A - Manufacture of semiconductor integrated circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable irregularities of the roughemed surface of a film to be checked with good reproducibility at high speed by a method, wherein the surface area increase rate of the roughened surface of the film is obtained through the reflectivity of a measurement sample which is irradiated with light. SOLUTION: Standard sample 1a which is each provided with a roughened film whose surface area increase rate is known are prepared in plural number, the standard samples 1a are irradiated with continuous light rays of different wavelengths, and the reflectivity of the sample 1a is measured for light rays of each wavelength. Then, the relational expression between a surface area increase rate S of the standard sample 1a and a reflectivity R of the standard sample 1a for light rays of specific wavelength is obtained. Then, a measurement sample 1b, which is equipped with a roughened surface and whose surface area increase rate is unknown, is irradiated with a light ray of specific wavelength, and a reflectivity Ru of the measurement sample 1b for light rays of specific wavelength is measured. By substituting the measured reflectivity Ru of the measurement sample 1b for the reflectivity R in the relational expression between the surface area increase rate S and the reflectivity R for light rays of specific wavelength, the surface area increase rate Su of the roughened film provided in the measurement sample 1b is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technology for manufacturing a semiconductor integrated circuit device, and more particularly to a technology effective when applied to a semiconductor integrated circuit device having a roughened film.

[0002]

2. Description of the Related Art In one of semiconductor integrated circuit devices, a memory cell is a memory cell selecting MISFET (Metal Insulator).
Semiconductor Field Effect Transistor) and a DRAM (Dynami) composed of an information storage capacitive element consisting of a lower electrode and an upper electrode provided with a capacitive insulating film interposed therebetween.
c Random Access Memory). But DRAM
However, there is a problem that the memory cell is miniaturized with the increase in the capacity, the amount of charge stored in the information storage capacitor element is reduced, and the information holding characteristic is deteriorated.

Therefore, in a DRAM of 64 Mbit or more, a capacitor over bit line (Capacitor Over B) in which an information storage capacitor is arranged above a bit line.
It has an it line (COB) structure, and the lower electrode has a three-dimensional shape such as a cylindrical shape or a fin shape, thereby increasing the surface area to increase the amount of accumulated charges.

However, in a DRAM of 256 Mbit or more, even if a memory cell including an information storage capacitor having a cylindrical lower electrode is adopted, the height of the lower electrode is required to obtain a required amount of stored charge. Must be set to 1 μm or more, processing of the lower electrode becomes difficult, and the mechanical strength of the lower electrode is weakened, so that the lower electrode is easily peeled off.

Therefore, the cylindrical lower electrode is made of a polycrystalline silicon film, and the surface is roughened to increase the effective surface area of the lower electrode, and the accumulated charge is increased within the range where the cylindrical height can be processed. A method to make it work is being studied.

Area enhancement rate (Area Enhancement F) which is one of the important evaluation items of a roughened polycrystalline silicon film
actor; AEF) can be determined from the effective surface area calculated from the electrical characteristics. However, in order to obtain electrical characteristics, a step of sequentially forming a capacitor insulating film and an upper electrode on the roughened polycrystalline silicon film is necessary. It takes time to determine the quality.

Therefore, an atomic force microscope (Attomic Force Microscope)
The relationship between the surface roughness of the roughened polycrystalline silicon film measured using a microscope (AFM) and the surface area increase rate obtained from the electrical characteristics is obtained in advance, and the roughened polycrystalline silicon film is obtained. A method of quantifying the surface area increase rate of a roughened polycrystalline silicon film by measuring the roughness of the polycrystalline silicon film immediately after the formation of the crystalline silicon film is being studied.

[0008] Measurement of roughness using AFM (hereinafter referred to as AF
In M measurement), the probe is scanned in a two-dimensional plane direction while controlling the probe so that the atomic force or the distance between the roughened polycrystalline silicon film and the AFM probe is constant. By obtaining three-dimensional information of the irregularities on the surface of the roughened polycrystalline silicon film, it is possible to know the roughness of the roughened polycrystalline silicon film.

[0009]

However, according to the studies made by the present inventors, in the AFM measurement, the surface of the roughened polycrystalline silicon film and the probe come into contact during the measurement and both are worn. Therefore, it is difficult to obtain reproducibility of the roughness of the roughened polysilicon film, and a clear relationship between the surface area increase rate and the roughness of the roughened polysilicon film is obtained. There was a problem that there was no.

Further, since the AFM measurement takes 15 minutes or more, the in-line QC (Qual
When the AFM measurement is used for the ity control, the throughput is reduced.

An object of the present invention is to provide a technique capable of inspecting unevenness of a roughened film with good reproducibility and at high speed.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0013]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

The method of manufacturing a semiconductor integrated circuit device according to the present invention uses a photometer capable of measuring light scattering or reflection when analyzing the surface state of a roughened film whose surface area increase rate is unknown. Te, a plurality of standard samples lambda ₁ from lambda _k wavelengths of different continuous light irradiation, respectively, the at each wavelength from lambda ₁ lambda _k plurality having a membrane surface area increase rate is known roughening a step of measuring the reflectance of the standard sample of each, and the surface area increase rate of each of said plurality of standard samples, and a reflectance of each of said plurality of standard samples, at each wavelength from lambda ₁ lambda _k Calculating a correlation coefficient between the surface area increase rate and the reflectance of the plurality of standard samples; and a specific wavelength when the correlation coefficient between the surface area increase rate and the reflectance of the plurality of standard samples is minimized. Determining the plurality of The step of plotting and graphing the relationship between the surface area increase rate of each of the standard samples and the reflectance at each of the specific wavelengths of each of the plurality of standard samples. A step of obtaining a relational expression between the surface area increase rate and the reflectance at each of the plurality of standard samples at the specific wavelength, and using the photometer, the surface area increase rate is unknown and the surface is roughened. Irradiating the measurement sample having the specific wavelength of light, measuring the reflectance of the measurement sample, the surface area increase rate of each of the plurality of standard samples, and each of the plurality of standard samples Substituting the reflectance of the measurement sample into the relational expression with the reflectance at the specific wavelength, and calculating the surface area increase rate of the roughened film of the measurement sample. Than it is.

According to the above-described means, it is possible to know the rate of increase in the surface area of the roughened film based on the reflectance of the light applied to the measurement sample without contacting the measurement sample. The wear of the film surface and the deterioration of the measuring device do not occur, and the inspection can be performed in a short time.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. An inspection method for determining the surface area increase rate of a roughened film from light reflectance according to an embodiment of the present invention will be briefly described with reference to steps 100 to 103 shown in FIG. In all the drawings for describing the embodiments, components having the same function are denoted by the same reference numerals, and the repeated description thereof will be omitted.

First, as a step 1, after preparing a plurality of standard samples having a roughened film with a known surface area increase rate, the standard samples are irradiated with continuous lights having different wavelengths to reflect light at each wavelength. The ratio is measured (step 100). Then, determine the relation between the surface area increase rate S for the standard sample and the reflectance R with light of a specific wavelength lambda _x (step 101).

Next, in step 2, the reflectance R _u with light of a specific wavelength lambda _x by irradiating light of a specific wavelength lambda _x in the measurement sample having a membrane surface area increase rate is unknown roughened measured (step 102), the relationship between the reflectance R with light of said specific wavelength and the surface area increase rate S obtained in step 101 lambda _x, by substituting the measured reflectance R _u, determining the surface area increase ratio S _u of the roughened film measured sample have (step 103).

Next, calculation method of the surface area increase rate is step 1 obtain the relationship between the reflectance R with light of a known specific wavelength and the surface area increase rate S in a standard sample having a roughened film lambda _x Will be described in detail with reference to FIGS.

FIG. 2 is a process chart for explaining the above-mentioned calculation method, FIG. 3 is a schematic diagram of the configuration of the surface area increase rate inspection apparatus M _AEF , and FIG. 4 is a schematic diagram of the optical system of the surface area increase rate inspection apparatus M _AEF. FIG. 5 is a graph showing the relationship between the light reflectance and the wavelength in the standard sample, and FIG. 6 is a correlation coefficient obtained from the relationship between the surface area increase and the light reflectance in the standard sample. FIG. 7 is a graph showing the relationship between the surface area increase rate of the standard sample and the reflectance at a specific wavelength of light.

First, a plurality (n) of standard samples having a roughened film whose surface area increase rate is already known is
prepare.

Next, as shown in FIG.
light of different wavelengths emitted from the light source 2 of the surface area increase rate testing device M _AEF to a (λ ₁ ~λ _k) irradiating continuously receives the reflected or scattered light by the light receiving unit 3, enters the light receiving unit 3 The separated light is wavelength-resolved by the spectroscope 4 and each wavelength (λ _{1 to} λ
The reflectivity at _k ) is measured (step 100). It is not necessary to use a special optical system for the surface area increase rate inspection device M _AEF used here, and for example, a reflectometer shown in FIG. 4A or a scatterometer shown in FIG. 4B is used. .
The spot diameter of the light is, for example, about 0.1 μm.

Next, the measured reflectance is input to the analyzer 5 of the surface area increase rate inspection device M _AEF and stored (step 1).
01). The measurement and storage of the reflectance are repeated for n standard samples. In FIG. 5, as an example,
The relationship between the reflectance and the wavelength obtained with nine standard samples when the reflectometer shown in FIG. 4A is used for the optical system is shown.

Next, using the analyzer 5 of the surface area increase rate inspection apparatus M _AEF , the surface area increase rate and each wavelength (λ _{1 to} λ
The correlation coefficient with the reflectance in _k ) is _obtained by the following equation (1) (step 102).

Equation (1) ρ _i = ｛E [(SE (S))
(R−E (R))]｝ / σ (S) σ (R) where ρ _i is the correlation coefficient at the wavelength λ _i , E is the average in parentheses, S is the surface area increase rate, and R is the wavelength λ The reflectance for light _i , σ is the standard deviation in parentheses.

Table 1 summarizes the relationship between the reflectance data at each wavelength obtained by the measurement and the correlation coefficient obtained by equation (1).

[0027]

[Table 1]

FIG. 6 shows the relationship between the correlation coefficient and the wavelength obtained by the equation (1) when the reflectometer shown in FIG. 4A is used for the optical system. As shown in FIG. 6, the correlation coefficient obtained by the equation (1) changes depending on the wavelength of light. Here, the wavelength λ _x at which the correlation coefficient is minimum is obtained (step 103). In this case, the correlation coefficient becomes minimum at a wavelength of about 350 nm.

Further, by using the analyzer 5 of the surface area increase rate inspection apparatus M _AEF , the surface area increase rate S and the reflectivity R for light of a specific wavelength (λ _x = 350 nm) in the n standard samples shown in FIG. Is plotted and graphed (step 104). Thereafter, the surface growth rate S and the specific wavelength λ _x
The slope α and the intercept β are calculated and stored by the regression calculation shown in the following equation (2) from the relationship with the reflectance R with respect to the light (step 105).
_The data is output using the output device 6 of the _AEF .

[0030] Equation (2) S = β + αR view. 7 (a), the reflectance of the optical surface area increase rate S and a specific wavelength lambda _x in the case of using a scatterometer to measure the reflectance of the standard sample light R shows the relationship between FIG. 7 (b), the reflectance R of the optical surface area increase rate S and a specific wavelength lambda _x in the case of using a reflectometer for measuring the reflectance of the standard sample light Shows the relationship. The correlation coefficient in the measurement using a reflectometer is -0.747, and the variation in the surface area increase rate becomes large due to a measurement error or the like. However, the correlation coefficient in the measurement using a scatterometer is 0.978. Yes, measurement accuracy of surface area increase rate is 1
0% or less. With scatterometer, if the effective surface area is increased by increasing the rough surface of the measurement sample, regular reflectance light is scattered is reduced, the reflection of a light of a particular wavelength lambda _x surface area increase rate S The relationship with the rate R is obtained.

Next, the method of calculating the surface area increase rate in the measurement sample having a roughened film whose surface area increase rate is unknown, which is step 2, will be described in detail with reference to steps 100 to 103 shown in FIG. I do.

Firstly, the view as shown in 3, the measurement sample 1b light of a particular wavelength lambda _x and radiation emitted from the light source 2 of the surface area increase rate testing device M _{AE F,} the reflected or scattered light receiving section 3 in receiving, and wavelength-resolved by the spectroscopic unit 4 light enters the light receiving unit 3, measuring the reflectance R _u at a particular wavelength lambda _x (step 100). Here, the specific wavelength λ _x is the wavelength determined in step 103 of FIG.

Next, enter the measured reflectance R _u to the analyzer 5 of the surface area increase rate testing device M _AEF, stores (step 101). Next, using the analyzer 5, the reflectance R _u is substituted into the above equation (2) to calculate the surface area increase rate _Su (Step 102), and after saving, the output device 6 is used.
The data is output (step 103).

Here, the constants α and β are determined in step 10 of FIG.
5 and stored, the reflectance R _u obtained from the measurement sample is substituted into the equation (2) to obtain the surface area increase rate S of the roughened film of the measurement sample. _u can get.

Next, a case where the above-described method for inspecting the surface area increase rate of a roughened film according to the present embodiment is applied to an in-line QC for inspecting irregularities on the surface of a roughened polycrystalline silicon film. This will be described using steps 100 to 103 shown in FIG. The roughened polycrystalline silicon film,
A manufacturing method when applied to a lower electrode of an information storage capacitor constituting a memory cell of a DRAM will be described.

First, a memory cell selecting MI of a memory cell is selected.
A cylindrical lower electrode is formed of an amorphous silicon film having a relatively smooth surface on the semiconductor substrate on which the SFET and the bit line are formed (step 100).

Next, the surface of the amorphous silicon film is
After cleaning using an F-based solution, reduced pressure CVD (Chemical
1 × 10 ^-7 Torr using a Vapor Deposition device
By irradiating a SiH ₄ gas in the following high vacuum, stopping supply of the gas, and performing heat treatment at a high temperature, a silicon grain is formed on the surface of the amorphous silicon film to form a roughened polycrystalline silicon film. Form (Step 10)
1). The size of the silicon grain is, for example, 10 to 100 nm.
It is about.

Next, after forming a roughened polycrystalline silicon film, a product or QC semiconductor wafer is extracted. Then, by setting the above semiconductor wafer withdrawn to the surface area increase rate testing device M _AEF, after measuring the reflectance R _u with light of a specific wavelength lambda _x which is obtained in advance by the standard sample (step 102a), enter the reflectivity R _u to the analyzer 5, and stores. Next, using the analysis device 5,
The surface area increase rate by substituting the reflectance R _u in equation (2) S _u
Is calculated (step 102b), and after saving, the data is output using the output device 6 (step 102c).

[0039] When the surface area increase ratio S _u satisfies the standard value, then, in order to prevent oxidation of the polycrystalline silicon film which is roughened as a lower electrode, roughened polycrystalline silicon film Is nitrided. Thereafter, the upper layer film thickness 20nm approximately tungsten oxide (Ta ₂ O ₅₎ film of roughened polysilicon film deposited by the CVD method, then the semiconductor substrate is heat-treated at about 800 ° C. Ta ₂ Activate the O ₅ film (step 103).

Next, a titanium nitride (TiN) film having a thickness of about 150 nm is deposited on the Ta ₂ O ₅ film by CVD and sputtering (step 104). After that, the TiN is dry-etched using the resist pattern as a mask.
By sequentially processing the film and the Ta ₂ O ₅ film, Ti
An information storage capacitance element is formed which includes an upper electrode made of an N film, a capacitance insulating film made of a Ta ₂ O ₅ film, and a lower electrode made of a roughened polycrystalline silicon film.

As described above, according to the present embodiment, since the wear of the surface of the roughened film and the deterioration of the measuring device do not occur, the measurement accuracy of the surface area increase rate of the roughened film is 10%.
% Or less, and the time required for measurement can be shortened, so that a decrease in the throughput of in-line QC in the manufacturing process can be prevented.

Although the invention made by the inventor has been specifically described based on the embodiments of the present invention, the present invention is not limited to the above embodiments, and various modifications may be made without departing from the gist of the invention. Needless to say, it can be changed.

For example, in the above-described embodiment, the surface area increase rate is used for the in-line QC of the roughened film.
Surface area (Stephen Brunauer, Paul Emmett, Edward Tell
The same effect can be obtained by using the area determined by the BET isotherm derived by er) or the roughness.

In the above embodiment, light is used as the light source of the photometer. However, similar effects can be obtained by using a laser, an X-ray, an electron beam, or the like.

[0045]

Advantageous effects obtained by typical ones of the inventions disclosed by the present application will be briefly described as follows.
It is as follows.

According to the present invention, the variation in the data of the surface area increase rate of the roughened film is reduced, and the measurement of the surface area increase rate of the roughened film is performed in a short time in in-line QC in the manufacturing process. Therefore, the surface state of the roughened film can be inspected with good reproducibility and at high speed.

[Brief description of the drawings]

FIG. 1 is a process chart for explaining an inspection method for obtaining a surface area increase rate of a measurement sample from light reflectance according to an embodiment of the present invention.

FIG. 2 is a process chart for explaining a method of obtaining a relationship between a surface area increase rate of a standard sample and light reflectance according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a configuration of a surface area increase rate inspection apparatus according to an embodiment of the present invention.

FIGS. 4A and 4B are schematic diagrams of an optical system of a surface area increase rate inspection apparatus according to an embodiment of the present invention.

FIG. 5 is a graph showing light reflectance of a standard sample according to an embodiment of the present invention.

FIG. 6 is a graph showing a correlation coefficient obtained from a relationship between a surface area increase rate and a light reflectance of a standard sample according to an embodiment of the present invention.

FIGS. 7A and 7B are graphs showing the relationship between the surface area increase rate of a standard sample and the reflectance at a specific wavelength of light according to an embodiment of the present invention.

FIG. 8 is a process chart for explaining a method for obtaining a surface area increase rate of a measurement sample from light reflectance according to an embodiment of the present invention.

FIG. 9 is a process chart for explaining a method of inspecting a surface area increase rate applied to in-line QC according to an embodiment of the present invention.

[Explanation of symbols]

1a Standard sample 1b Measurement sample 2 Light source 3 Light receiving unit 4 Spectrometer 5 Analyzer 6 Output device M _AEF surface area increase rate inspection device

Continued on the front page F-term (reference) 2F065 AA50 AA58 CC17 CC19 DD06 DD08 FF41 FF61 GG01 GG04 GG23 HH04 JJ03 LL67 PP22 QQ17 QQ41 RR06 2G051 AA51 AB20 BA08 BA10 BA20 CA01 CB01 CB05 EB01 A02 AB03 A02 A BA20 CA24 DH01 DH12

Claims (7)

[Claims] 1. Using a photometer capable of measuring the scattering or reflection of light, the surface of a roughened film whose value is unknown is irradiated with light of a specific wavelength to measure the reflectance. After that, the relational expression between the value representing the surface state and the reflectance at a specific wavelength of light representing the existing surface state obtained using a known roughened film, A method of analyzing the surface condition of the roughened film whose value representing the surface condition is unknown by substituting the surface condition. 2. A method for manufacturing a semiconductor integrated circuit device comprising an inspection step of analyzing a surface condition of a roughened film whose value representing a surface condition is unknown, comprising: (a) controlling the scattering or reflection of light; using a photometer capable of measuring, a different continuous light wavelengths of lambda _k from lambda ₁ to a plurality of standard sample value representing the surface condition has a known roughened film irradiated respectively, lambda a step of measuring the reflectance of the plurality of standard samples at each wavelength of lambda _{k 1,} respectively, (b). and a value representing the surface condition of each of said plurality of standard samples, the plurality of standard samples and a respective reflectance of calculating a correlation coefficient of a value representing the surface condition of the plurality of standard samples at each wavelength from lambda ₁ lambda _k and reflectivity, (c). the plurality The correlation coefficient between the value representing the surface condition of the standard sample and the reflectance is the smallest. And (d) determining a value representing the surface state of each of the plurality of standard samples, and plotting a relationship between the reflectance at the specific wavelength of each of the plurality of standard samples. And (e) by a regression calculation, a relationship between a value representing the surface state of each of the plurality of standard samples and a reflectance of the plurality of standard samples at the specific wavelength. Obtaining a formula, and (f) using the photometer,
Irradiating light of the specific wavelength to a measurement sample having a roughened film whose value representing the surface state is unknown, and measuring the reflectance of the measurement sample; and (g) measuring the reflectance of the plurality of standards. Substituting the reflectance of the measurement sample into a relational expression between the value representing the surface state of each sample and the reflectance at the specific wavelength of each of the plurality of standard samples, the rough surface of the measurement sample A step of calculating a value representing a surface state of the film formed into a semiconductor device. 3. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein the light source of the photometer is light, X
A method for manufacturing a semiconductor integrated circuit device, comprising: a beam, an electron beam, or a laser. 4. The method of manufacturing a semiconductor integrated circuit device according to claim 1, wherein said photometer is an optical meter using scattering or an optical meter using reflection. Manufacturing method. 5. The method of manufacturing a semiconductor integrated circuit device according to claim 1, wherein the values representing the surface state are a surface area increase rate, a specific surface area, a BET surface area, and a roughness. A method for manufacturing an integrated circuit device. 6. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein a spot diameter of light of said photometer is about 0.1 μm. 7. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein said roughened film is a polycrystalline silicon film having silicon grains on its surface. Device manufacturing method.