JP2803982B2 - Quantitative method of glow discharge emission spectrometry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for quantitative analysis of glow discharge emission spectroscopy for analyzing the composition of a material composed of multi-elements and analyzing the depth direction from the surface.

[0002]

2. Description of the Related Art Glow discharge optical emission spectroscopy is a method for examining the distribution of elements in a depth direction from a relatively smooth material surface. Industrially, this analysis method has a very wide application range for evaluating thin metallic plates, such as analysis of elements in the depth direction of the surface layer of alloys such as various steel plates.

In glow discharge emission spectroscopy, usually, a sample is used as a cathode, an electrode in a discharge tube is used as an anode, and the discharge tube is evacuated to a vacuum. A high voltage is applied, and light generated by the generated glow discharge is detected by a spectroscope. At this time, the intensity of light of a specific wavelength from several elements is measured with respect to the time of the glow discharge and used as data. There are usually a constant voltage method (constant voltage) and a constant current method (constant current) depending on how to apply a voltage between electrodes when causing discharge.

Further, several methods have been proposed for calculating a quantitative composition from these data. For example, representative of the emission intensity I _m wavelength m of a certain element by the following equation. _{I m = k m · c A} · C QM · i 2 · (U-U o) x [7] Here, k _m is the concentration of the factors for such devices, c _A the element A, C _QM is related to the matrix Constant, i is the current,
_Uo is a threshold voltage of sputtering, and X is an index obtained experimentally. There is a method in which a constant in this relationship is obtained for some elements, and the concentration of a sample having an unknown composition is obtained using those constants. These methods are described, for example, in Spectrochimica, Acta, Volume 40B, 1985, p. 631.

On the other hand, the sputter rate under conditions glow discharge constant voltage v (g · s ^-1), when the emission intensity of a certain element I _m, the concentration of c _i (weight fraction), a standard Using the sample, the effective luminescence yield R _i is obtained as R _i = I _m / c _i v ⁱ [8], and the weight W _i sputtered at a certain time of the sample having the unknown composition is I _i / R _i made determined from the relationship, the concentration c _i

(Equation 7) There is also a method to obtain from. These methods are described in, for example, Vol. 73 of Iron and Steel, 1987, p.565.

[0006]

In the conventional quantification method for glow discharge emission spectroscopy, quantification is not always performed in consideration of the basic characteristics of glow discharge. Therefore, there is an ambiguous point in the quantification, and the quantification is not always excellent.

For example, in the quantification method based on the formula [7], each parameter must be determined under certain measurement conditions, and the content of the determined parameter is not always clear. Therefore, there is a problem in applying this method to samples having various compositions, and this method is poor in versatility. On the other hand, the expression

In the method based on the effective luminous yield of [9], the luminous intensity is normalized by the concentration and the sputter rate, but the correction of the change in the current during the discharge at a constant voltage is not performed. Therefore, there is an unclear point in this quantification method.

It is an object of the present invention to provide a method for determining the bulk concentration of an alloy and the concentration distribution in the depth direction from the surface of the alloy in these methods for glow discharge emission spectrometry. And

[0009]

Means for Solving the Problems The present invention, in order to solve the above problems, in the glow discharge emission spectroscopic analysis, the standard sample S including the element i (i = 1~n) atomic fraction f _S ⁱ Is sputtered in a constant current mode, the emission intensity of the spectral line m of the element i is _ImS ⁱ , and the sputtering speed is v (mol
· S ^-1 ), the effective luminescence yield R _{m of the} element i
ⁱ a (s · mol ^-1) given by I _mS ⁱ / vf _S ^i, the discharge voltage of a solid pure substance of the element i in the sputtering conditions and V _S ⁱ (V), then the measurement sample X The emission intensity of the element i when sputtering under the sputtering conditions is I
When a _mX ^i, quantitative method of glow discharge optical emission spectrometry and obtains the atomic fraction f _x ⁱ of the element i of the measurement sample from (1) formula,

(Equation 8)

[0010] and, in a glow discharge emission spectroscopic analysis, the standard sample S having an atomic fraction f _S ⁱ of the elements i (i = 1 to n) is sputtered in a constant current mode, the emission spectral lines m of the element i intensity I _mS ^i, when sputtering speed is v (mol · s ^-1), the effective light emission yield of elements i R _m ⁱ a (s · mol ^-1) given by I _mS ⁱ / vf _S ⁱ the discharge voltage of the solid pure substance of the element i in the sputtering conditions and V _S ⁱ (V), then at the sputtering conditions of a measurement sample X time _{Δt k (s) (k =} 1~p) When the emission intensity of the element i and the discharge voltage at the time of sputtering are I _mXk ⁱ and V _Xk (V), respectively, the atomic fraction f _xk ⁱ of the element i in the measurement sample is obtained from the equation (2). Ρ ⁱ (g · g)
m ⁻³ ), atomic weight M ⁱ (g · mol ⁻¹ ), discharge area A
(M ² ), the sputter depth Δd _k (m) at the time Δt _k (s) is _obtained from the equation [3] to obtain the depth from the surface of the measurement sample.

(Equation 9) Determination method of glow discharge optical emission spectrometry and obtains the atomic fraction f _xp ⁱ in,

(Equation 10)

[0011] and, in a glow discharge emission spectroscopic analysis, the standard sample S having an atomic fraction f _S ⁱ of the elements i (i = 1 to n) is sputtered at a constant voltage mode, the emission spectral lines m of the element i intensity I _mS ^i, when sputtering speed is v (mol · s ^-1), the effective light emission yield of elements i R _m ⁱ a (s · mol ^-1) given by I _mS ⁱ / vf _S ⁱ , a discharge current of a solid pure substance of the element i in the sputtering conditions as i _S ⁱ (a), the discharge current dependence of the effective emission yield ai _S ⁱ + b (a and b are constants) expressed in the next time the emission intensity at the time of sputtering the sample X in the sputtering conditions are I _mX ^i, wherein the determination of the atomic fraction f _x ⁱ of the elements i of the measurement sample from [4] formula Glow discharge emission spectrometry quantitative method,

[Equation 11]

In the glow discharge emission spectroscopy, a standard sample S having an element i (i = 1 to n) having an atomic fraction f _S ⁱ is sputtered in a constant voltage mode to emit light of a spectrum line m of the element i. intensity I _mS ^i, when sputtering speed is v (mol · s ^-1), the effective light emission yield of elements i R _m ⁱ a (s · mol ^-1) given by I _mS ⁱ / vf _S ⁱ , a discharge current of a solid pure substance of the element i in the sputtering conditions as i _S ⁱ (a), the discharge current dependence of the effective emission yield a ⁱ i _S ⁱ + b ⁱ (a ⁱ and b ⁱ Is a constant), and then the measurement sample X is subjected to the time Δt under the sputtering conditions.
_{k (s) (k = 1~p} ) emission intensity of the element i at the time of sputtering by the I _MXK ^i, when the discharge current is i _Xk (A), atomic content of the element i of the measurement sample Rate f _xk
ⁱ is obtained from the equation [5], and the density of the pure substance of the element i in the solid state is ρ ⁱ (g · m ⁻³ ), and the atomic weight is M ⁱ (g
Mol ⁻¹ ) and the discharge area is A (m ² ), the sputter depth Δd _k (m) at the time Δt _k (s) is _obtained from the equation [6], thereby obtaining the surface of the measurement sample. Depth from

(Equation 12) Determination method of glow discharge optical emission spectrometry and obtains the atomic fraction f _xp ⁱ in,

(Equation 13) I will provide a.

[0013]

The operation of the quantification method of the present invention will be described. First, the case of sputtering in the constant current mode will be described. Standard sample S are made of n kinds of elements, the atomic fraction of each element i (i = 1~n) and f _S ^i. The number of types of elements included in the standard sample may be less than n, and in that case, the measurement may be performed by focusing on each element included in the plurality of standard samples. When the standard sample S is sputtered at a constant current with the measurement conditions such as the gas pressure kept constant, the emission intensity of the spectral line m of each element i is _ImS ⁱ , and the sputtering speed is v (mol · s ⁻¹ ). Suppose there is. Element i
Is assumed to be V _S ⁱ (V).
When a solid solid substance cannot be obtained, the apparent discharge voltage may be obtained by externally applying the discharge voltage to the solid pure substance from the composition dependency of the discharge voltage of the standard sample. Sputter velocity v depends on the composition of the sample, but the use of effective emission yields ^{_{R m i (s · mol -1}} ) of the element i as follows, that the effect is to include in the active emission yield it can. Given by ^{_{R m i = I mS i /}} v i f S i [10].

In the present invention, when the emission intensity of the element i is I _mX ⁱ and the discharge voltage is V _X (V) when the measurement sample X composed of n kinds of elements is sputtered in the constant current mode, the measurement is carried out in the present invention. the atomic fraction f _x ⁱ of the element i in the sample

[Equation 14] Find from such a relationship. In the constant current mode, the effective light emission yield shows voltage dependence, and a correction for that is necessary. The correction is made by using the equation (1).

Further, the quantitative determination in the depth direction, that is, the composition and the depth at each sputtering stage is performed as follows. Time Δt when measuring sample X was sputtered in constant current mode
_{k (s) (k = 1~p} ) by the emission intensity of the element i at the time of spatter I _MXK ^i, the discharge voltage is assumed to be V _xk (V). Atomic fraction f of element i at each sputtering stage
The _Xk ⁱ

(Equation 15) The composition can be determined from the following values. Further, the density of the pure substance of element i in the solid state is ρ ⁱ (g ·
m ⁻³ ), atomic weight M ⁱ (g · mol ⁻¹ ), discharge area A
(M ² ), the sputtering depth Δd _k (m) at time Δt _k (s) is

(Equation 16) From this value, an effective depth by sputtering is obtained. According to these procedures, the relationship between the depth from the surface of the measurement sample and the composition (atomic fraction) can be obtained.

On the other hand, the case of sputtering in the constant voltage mode will be described. If the standard sample S is a constant current and has become a kind of element in the same manner, the atomic fraction of each element i (i = 1~n) and f _S ^i. And constant measurement conditions such as gas pressure, when the sputter a standard sample S at a constant voltage, the emission intensity of the spectral line m is I _ms ⁱ of each element i, and sputter rate v (mol · s ^-1) Suppose there is. Since the discharge current i _S ⁱ (A) of element i depends on the composition of the standard sample,
The discharge current i _S ⁱ of solid pure substance equivalent of each element or determined from the discharge current of a solid pure substance is obtained by extrapolating the discharge current of a solid pure substance from the composition dependency of the discharge current. Effective emission yields ^{_{R m i (s · mol -1}} ) of the element i, as in the constant current mode is determined as follows. R _m ⁱ = I _mS ⁱ / v ⁱ f _S ⁱ [10] Further, the change of the effective emission yield with the discharge current is determined by slightly changing the gas pressure, and the dependence of the effective emission yield on the discharge current is determined. It is expressed as follows. ^{_{R m i = a i i S}} i + b i [11] Here, a ⁱ and b ⁱ are constants.

Next, when the measurement sample X is sputtered in the constant voltage mode, the emission intensity is _Im x ⁱ , and the discharge voltage is V
_{When X} (V), the present invention uses the element i in the measurement sample.
The atomic fraction f _x ⁱ of

[Equation 17] Find from such a relationship. In the constant voltage mode, the effective light emission yield shows current dependence, and a correction for that is necessary, but the correction is made by using equation [10].

Further, the quantitative determination in the depth direction, that is, the composition and the depth at each sputtering stage is performed as follows. Time when sample X was sputtered in constant voltage mode

(Equation 18) The emission intensity when continuously sputtered at a time was I _mXk ⁱ , the discharge current was i _Xk (A), and the element i in the measurement sample was
The atomic fraction f _xk ⁱ of

[Equation 19] Find from the relationship. Further, the density in the solid state of the pure substance of element i is ρ ⁱ (kg · m ⁻³ ), and the atomic weight is M (g · mol
^-1 ), and when the discharge area is A (m ² ), the time Δt
The sputter depth Δd _i (m) at _k (s)

(Equation 20) From the relationship. Thereby, the relationship between the depth from the surface of the measurement sample and the composition can be obtained.

[0019]

EXAMPLE An example in which quantitative analysis was performed by the glow discharge optical emission spectrometry of the present invention will be described. Glow discharge optical emission spectroscopy of Fe—Cr alloys having six types of compositions was performed in a constant current mode with an argon gas pressure of 8 Torr and 30 mA. FIG.
Are the values obtained by chemical analysis of the Cr atomic fraction of these samples (Cr atomic fraction (chemical analysis)) and the values obtained by the quantitative method using a constant current according to claim 1 of the present invention (Cr atomic fraction (G
DS)). The linearity of this relationship is good, indicating that the quantification method of the present invention is excellent.

Glow discharge emission spectroscopy analysis of a thin steel sheet plated with Zn to a thickness of about 1.8 μm was performed at an argon gas pressure of 10
The test was performed in a constant current mode of Torr and 40 mA. FIG. 2 shows the result of analyzing the concentration distribution in the depth direction from the surface by the constant-current depth direction determination method according to claim 2 of the present invention. From this figure, it is understood that not only the composition at each sputtering depth but also the depth can be quantified.

Glow discharge emission spectroscopy analysis of Fe—Ni alloys having five types of compositions was carried out at an argon gas pressure of 10 Torr and a pressure of 6 Torr.
The test was performed in the constant voltage mode of 00V. FIG. 3 shows the value obtained by chemical analysis of the atomic fraction of Ni (Ni atomic fraction (chemical analysis)) and the value obtained by the quantitative method using a constant voltage according to claim 3 of the present invention (Ni atomic fraction (GDS)). ). The linearity of this relationship is excellent over a wide range.

Glow discharge emission spectroscopy analysis of a thin steel sheet plated with Sn to a thickness of about 1 μm was performed at an argon gas pressure of 8 Torr.
r, performed in a constant voltage mode of 550V. FIG. 4 shows the result of analyzing the concentration distribution in the depth direction by the constant-current depth direction determination method according to claim 4 of the present invention. This method can also determine not only the Sn composition at each sputtering depth but also the depth.

[0023]

According to the method for glow discharge emission spectrometry of the present invention, the quantitativeness of the surface analysis of a steel plate or the like, for example, the method of evaluating the concentration of the surface layer and the oxide film of a plating material or a coating material is further improved. In particular, it has become possible to analyze a film having a non-uniform composition in the depth direction, and it has become possible to perform a detailed analysis that could not be obtained conventionally. As a result, the versatility of this analysis method is greatly expanded, and the effect in evaluating the material is extremely large.

[Brief description of the drawings]

FIG. 1 shows Cr in an Fe—Cr alloy having six types of compositions.
The values obtained by chemical analysis of the atomic fraction (Cr atomic fraction (chemical analysis)) and the values (Cr atomic fraction (GDS)) determined by the constant current quantitative method according to claim 1 of the present invention are shown.

FIG. 2 shows the result of analyzing the concentration distribution in the depth direction from the surface of a thin steel sheet plated with Zn to a thickness of about 1.8 μm by the constant current depth direction determination method according to claim 2 of the present invention. Is shown.

FIG. 3 shows Ni in an Fe—Ni alloy having five compositions.
Are shown by a value (Ni atomic fraction (chemical analysis)) obtained by chemical analysis and a value (Ni atomic fraction (GDS)) obtained by a constant voltage quantitative method according to claim 3 of the present invention.

FIG. 4 shows the results of analyzing the concentration distribution in the depth direction of a thin steel sheet plated with Sn to a thickness of about 1 μm by the constant voltage depth direction determination method according to claim 4 of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kaoru Mizuno 20-1 Shintomi, Futtsu City, Chiba Prefecture Nippon Steel Corporation Technology Development Division (56) References JP-A-60-203838 (JP, A) Kaihei 5-149879 (JP, A) Analytical Chemistry, Vol. 35 (1986), No. 8, pp. 673-680 (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 21/62- 21/74

Claims (4)

(57) [Claims] 1. A glow discharge emission spectroscopic analysis, the standard sample S including the element i (i = 1~n) atomic fraction f _S ⁱ
Was sputtered in a constant current mode, the emission intensity of the spectral lines m of the element i is I _mS ^i, is sputter rate v (mol ·
When a s ^-1), effective light emission yield R _m ⁱ of the element i
(S · mol ⁻¹ ) is given by _ImS ⁱ / vf _S ⁱ , and the discharge voltage of the solid pure substance of the element i under the sputtering conditions is V
And _S ⁱ (V), the emission intensity of the element i at the time of next sputtering a measurement sample X in the sputtering conditions I _mX
When a ^i, quantitative method of glow discharge optical emission spectrometry and obtains the atomic fraction f _x ⁱ of the element i of the measurement sample from (1) expression. (Equation 1) 2. A glow discharge emission spectroscopic analysis, the standard sample S including the element i (i = 1~n) atomic fraction f _S ⁱ
Was sputtered in a constant current mode, the emission intensity of the spectral lines m of the element i is I _mS ^i, is sputter rate v (mol ·
When a s ^-1), effective light emission yield R _m ⁱ of the element i
(S · mol ⁻¹ ) is given by _ImS ⁱ / vf _S ⁱ , and the discharge voltage of the solid pure substance of the element i under the sputtering conditions is V
_S ⁱ (V), and then, when the measurement sample X is sputtered under the sputtering conditions for a time Δt _k (s) (k = 1 to p), the emission intensity of the element i is _ImXk ⁱ , and the discharge voltage is when a V _xk (V), determined the atomic fraction f _xk ⁱ of the element i of the measurement sample from (2) expression, further the element i
When the density of the pure substance in the solid state is ρ ⁱ (g · m ^-3 ), the atomic weight is M ⁱ (g · mol ⁻¹ ), and the discharge area is A (m ² ), the time Δt _k (s ) Sputter depth Δd _k
By calculating (m) from the formula [3], the depth from the surface of the measurement sample is given by A glow discharge optical emission spectrometric method for determining the atomic fraction f _xp ⁱ in the above method. (Equation 3) 3. A glow discharge emission spectroscopic analysis, the standard sample S having an atomic fraction f _S ⁱ of the elements i (i = 1 to n) is sputtered at a constant voltage mode, the emission spectral lines m of the element i The strength is _ImS ⁱ , and the sputtering rate is v (mol · s
^-1 ), the effective emission yield R of the element i
_m ⁱ a (s · mol ^-1) given by I _mS ⁱ / vf _S ^i, the discharge current of a solid pure substance of the element i in the sputtering conditions as i _S ⁱ (A), the effective light emitting yield when (the a ⁱ and b ⁱ constant) the discharge current dependence a ⁱ i _S ⁱ + b ⁱ represents, the light emitting intensity when the next sputtered sample X in the sputtering conditions are I _mX ^i, Determination method of glow discharge optical emission spectrometry and obtains the atomic fraction f _x ⁱ of the elements i of the measurement sample from [4] expression. (Equation 4) 4. A standard sample S having an element i (i = 1 to n) having an atomic fraction f _S ⁱ in glow discharge emission spectroscopy.
Is sputtered in a constant voltage mode, the emission intensity of the spectral line m of the element i is _ImS ⁱ , and the sputtering speed is v (mol ·
When a s ^-1), effective light emission yield R _m ⁱ of the element i
(S · mol ⁻¹ ) is given by I _mS ⁱ / vf _S ⁱ , and the discharge current of the solid pure substance of the element i under the sputtering conditions is i
And _S ⁱ (A), the discharge current dependence of the effective emission yield ^{_{a i i S i + b i}} (a i and b ⁱ are constants) expressed in, then the sample X in the sputtering conditions Delta] t _k (S) (k =
1 to p), when the emission intensity of the element i is I _mXk ⁱ and the discharge current is i _Xk (A), the atomic fraction f _xk ⁱ of the element i in the measurement sample is [5 ], Ρ ⁱ (g · m ⁻³ ), the atomic weight M ⁱ (g · mol ⁻¹ ), and the discharge area are A (m ² ). The time Δt _k (s)
By calculating the sputter depth Δd _k (m) from the equation (6), the depth from the surface of the measurement sample is given by A glow discharge optical emission spectrometric method for determining the atomic fraction f _xp ⁱ in the above method. (Equation 6)