JPS62140035A - Radiation thermometer - Google Patents

Abstract

PURPOSE:To make it possible to realize the highly accurate measurement of temp., by alternately irradiating an object to be measured with two kinds of lights having the same luminous intensity but different in a wavelength at a constant ratio. CONSTITUTION:Two kinds of lights (lambda1, lambda2) having the same luminous intensity but different in a wavelength at a constant ratio are alternately emitted from a light source 4 and divided into two by a half mirror 14 and the lights transmitting through the mirror 14 are reflected by a mirror 8 to irradiate an object 3 to be measured while the lights reflected from the mirror 14 are held to such a state that the wavelengths or intensities thereof or the ratio of the luminous intensities thereof are constant by a feedback circuit 7. Next, the light from the object 3 passes through an objective lens 9 to reach a dichroic mirror 5. As a result, light with a wavelength lambda1 reflects and light with a wavelength lambda2 transmits. The light with the wavelength lambda1 reflected from the mirror 5 and the light with the wavelength lambda2 transmitted through the mirror 5 are respectively inputted to a microprocessor (mup)17 which in turn measures the emissivity ratio of lights different in a wavelength from the rising in the temp. of the object 3 to measure the temp. of the object 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a radiation thermometer that is not affected by the emissivity of an object to be measured.

<Prior Art> Conventionally, a method as shown in FIG. 3 has been used as one of the means for practical use of copper thermometry that is not affected by emissivity. In Figure 3, 1 is /1ilfl>tct, 12 is the object to be measured, 3 is the radiation thermometer, and i71! I
with a radiation reflector placed between the objects.

A small hole is formed in the bottom of the hemispherical bowl, and the inside is plated with gold to make it highly reflective.

In the above configuration, an emission OA thermometer is attached to the top of the bowl and brought close to the surface of the radiation object, and the temperature of the radiation object is measured by using mutual reflection to make the apparent emissivity approximately 1. Measuring.

FIG. 4 shows the relationship between the output of the radiation thermometer and time in the configuration not shown in FIG. 3 when the Mffj light reflection plate is installed and when it is removed.

According to the figure, the output of the radiation thermometer increases to a certain level when the radiation reflection plate is installed, but the output decreases when the radiation reflection plate is removed. First, the temperature and emissivity of the object to be measured are determined by assuming that the IJJ ratio is approximately 1 when the radiation reflection plate is installed.

<Problems to be Solved by the Invention> However, in the above configuration, a space is required to take in and take out the emitted light reflecting plate, and the apparatus becomes large. Furthermore, since the radiation light reflecting plate must be placed very close to the object to be measured, the installation conditions are strict and the places where it can be used are generally limited.

The present invention does not require any special equipment outside the stocking temperature 31, is not affected by the Q1 rate, and has a highly accurate temperature 1. (t
, 1.1+ constant.

<Means for solving the problem> In order to solve the above problem, the configuration of the present invention alternately irradiates the measurement target with two types of light having different wavelengths having the same light intensity or a certain ratio. The temperature of the dyed object to be measured is measured by measuring the ratio of the detection rate of the light having different wavelengths based on the temperature rise of the object to be measured due to the light.

<Embodiment> FIG. 1 is a block diagram showing an embodiment of the radiation temperature S1 according to the present invention. In the figure, 3 is the object to be measured, and 4 is the same intensity or a certain ratio of the wavelength. For example, L E D which alternately emits two types of light (λ1 and λ2),
LD, CO2 laser amount F, and a light source such as a YAG laser. The light from this light source 4 is split into two by a half mirror 14 arranged at a predetermined angle.
The light transmitted through the object 4 is reflected by the mirror 8, passes through the objective lens 9, and irradiates the object 3 to be measured.
1 or λ2 wavelength is reflected). The circle reflected by the half mirror 5 is photoelectrically converted by a monitoring photodiode 6, and its wavelength, intensity, or ratio of light intensity is maintained constant by a feedback circuit 7.

Light from the object to be measured 3 passes through an objective lens 9 and reaches a dichroic mirror 10 arranged at a predetermined angle. As a result 1, for example, light with a wavelength of λ1 is reflected, and light with a wavelength of λ2 is transmitted. Light λ reflected by dichroic mirror 10
, passes through an interference filter 10a, is photoelectrically converted by a photodiode 11a, and is amplified by an amplifier 15a. The output from this amplifier 15a is switched by a switch 13a in synchronization with the on/off of the light source, and one side passes through a DC cut filter 12a, is amplified by an amplifier 15b, is input to an integrator 16a, and is output from this integrator 116a. is input to the microprocessor 17 (hereinafter referred to as μP). In addition, when the switch 13a switches to the amplifier 15c side, the light 8!4 is turned off, the light emitted only from the object to be measured is amplified, and its output is μ1)1
7 is input.

On the other hand, the light transmitted through the dichroic mirror 5 passes through an interference filter 10b, is photoelectrically converted by a photodiode 11b, and is amplified by an amplifier 15d.

The output from this amplifier 15d is switched by the switch 13b at a predetermined time real fn, and one is amplified by the amplifier 15f after passing through the DC component cut filter 12b.
The signal is input to an integrator 16b. The output of this integrator 16b is input to μP17. In addition, when the switch 13b is switched to the amplifier 15e side, the light source 4 is turned off, and the /12 QJ light of only the object to be measured is amplified.
The output is input to μD17.

Note that the switching of the light switching 1b switches 13a and 13b of the light having wavelengths λ1 and λ2 of the light source 4 is determined based on m5 of the microprocessor 17.

Figure 2 (a) to (b) are time charts showing the state of the output horns of the amplifiers 15a to 15f'.
5a shows the output, where the level a is the output due to light from the object to be measured, the level b is the output when the temperature has sharply increased to 0 due to active reflection components from the surface of the object 3 to be measured,
Level C is the maximum output of the object to be measured when the object is irradiated for a predetermined period of time, level d is the output immediately after the light source is turned off, and the temperature of the object to be measured slowly decreases from level d. Return to the original output level of a (the integral value of this curve corresponds to the energy absorbed by the dyed object)
. At this time, the same level of output is generated in the amplifier 15d shown in FIG.

(B) The amplifier 15b in the figure shows the output when the switch 13a is switched to the capacitor 12a side. (B)
The DC component of the output waveform shown in the figure is cut, resulting in an output that gradually attenuates from point d. This output is input to the integrator 16a, leveled, and input to μp17.

(c) The figure shows switch 13a set to amplifier 15C side.
This shows the output of the amplifier 15C when the output from the light source 4 is turned off, and is the output of only the object to be measured.

(D) The figure shows a state in which light with a wavelength of λ2, for example, is irradiated from the light source 4, and from the amplifier 15d, the light that is transmitted through the dichroic mirror 5 and is combined with the charged and converted measurement object and the light with a wavelength of λ2 is emitted. Output. (d) The explanation of each point (a to d) of the output waveform shown in the figure is the same as that in the figure (a), and will therefore be omitted.

(e) The figure shows the output of the amplifier 15f when the switch 13b is switched to the capacitor 12b side. (d)
The DC component of the output waveform shown in the figure is cut, resulting in an output that gradually attenuates from point d. This output is input to the integrator 16b, leveled, and input to μp17.

(v) The figure shows the output of the amplifier 15e when the switch is switched to the amplifier 15e side and the output from the light source 4 is turned off, and is the output of only the object to be measured 3.

In the above configuration.

Intensity of light source with two wavelengths giving the same intensity 71...ΔB
(W) Each wavelength of the light source...λ1. λ2 <m) Emissivity at the above wavelength...B1. ε2 Temperature of the object to be measured...T(K).

The light emitted from the light tA4 at a wavelength of 21 is measured at the measurement target 3.
When it hits, ε, ・ΔB light is absorbed.

Similarly, the light emitted with a wavelength of λ2 is B2·ΔB light is absorbed.

In other words, the light intensity of B1 .DELTA.B (B2 .DELTA.B) locally increases the temperature of the dye to be measured.

Let this increased temperature of the measurement object be ΔT1.

ΔT+=81ΔB-K (ΔT1 becomes the input to the amplifier 15b) Similarly, the temperature at which the light of wavelength λ2 raises the measurement pair or object is ΔT2 = ε2 ΔB-K (ΔT2 becomes the input to the amplifier 15f) Here, ni=
Constants as a measurement system.

In addition, the radiance B from the object to be measured at the wavelength λ when no light is irradiated from the light source 4 is calculated from the Wien equation as B+=E+C+/λ15eXl)(C2/λ+T)...
・(1) Similarly, the radiation 11 degrees B2 from the measurement object at λ2 is B2 = 62 CI /λ2 ''3XI)
(C2/λ2T)...(2) Here, CI, C2=constant Also, the radiance (B+-, B2-) when irradiated with light of each wavelength from the light source 4 is as follows. Become.

B 1 ′ −ε +C+/λ ,′−exp
(, C2/λ, (T+ΔT+))...(3
)B2' = 82 CI/λ2'-exp(C2/
λ2 (T+ΔT2)) ... (4) (3).

If d3 is ^T+ and ΔT2(T in equation (4), then the following approximate equation can be obtained.

81' = ε +C+/λ, 5
-exp(C2/λ, T(1-ΔT,/T)) =εIC+/λ+ 5eXl) (C2/λ+T>・
<1+C2/λ1T・ΔT+) ...(5)82'
=ε2C1/λ2s-exp (-C2/λ2T(1-ΔT2./T>)=B2 C
2/'λ25eXI) (-02/λ2T) (1+0
2/22 teeth・ΔT2)...(6)(+),
From equations (2), (5), and (f;), (B+'
−8+ )/B+ = C2ΔT + /” <λ+T2) ... (7
) (B2 '-82> / B2 -=C2ΔT2/(λ2T2) ... (8) (7)
Dividing the equation by the equation (8).

((B+ 'B+)/'B+)/f (B2
'B2)/B2)-ΔTl/'ΔT2・
λ27/λ, ...(9) Here, 6T1-ε+a
B-K.

Substituting AT2=82 Δ B-K into equation (9) gives <8+ 'B+ )/(B2 '-82>
・ (82/Bl) = (λ 2 / λ goose) ・ (ε I
/ ε 2 ) ... (10) From the (lO) formula, (ε1/ε2) = (λ2/λ1 ) ・ (81' Bl) / (B2' B2) ・(
B2 /81 > ...(11) Expression (1) becomes (2)
When divided by Eq.

B+/B2-(ε1/ε2) (λ2/λ1)5・e
X p (02/T(1/λ I −1/λ 2
))...(12) The temperature of the object to be measured can be determined from equations 11 and 12 as follows.

T=02 (1/λ, -1/λ2)/1n(B+/B2)2・(B2'B2)/(B+'
B+)・(λI/λ2)4)・・・(13) Above (
Equation 13) makes it possible to realize a radiation thermometer that is not affected by emissivity.

In addition, all the 101 arithmetic calculations can be done using μp17. Also, from the true temperature T obtained from equation (13) and equations (1) and (2), emissivity ε1. ε
It is possible to obtain 2. This emissivity is useful for evaluating the physical properties of wafers in semiconductor processes, and by focusing on this emissivity, the radiation thermometer of the present invention can
It can also be used as a semiconductor process evaluation device.

Furthermore, the arrangement of parts such as the light source, half mirror, mirror, dichroic mirror, etc. is not limited to this example, and various modifications are possible.

<Effect of the invention> As specifically explained above along with the embodiments.

According to the invention.

(1) Highly accurate temperature measurement without the influence of emissivity can be performed without providing an external radiation reflector or the like.

(2) Resistant to gray attenuation in the atmosphere (uniform weakening of light regardless of wavelength). .

(3) Can be manufactured in the same size as a conventional radiation thermometer,
Furthermore, it is also possible to manufacture a handy type.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a radiation thermometer according to the present invention, FIGS. FIG. 4 is a configuration diagram showing a conventional example, in the configuration shown in FIG. 3,
It is a figure which shows the relationship between the output of a radiation thermometer and time when the radiation light reflection plate is installed and removed. 3...Measurement object, 4...Light source, 5...Dichroic mirror, 6...Monitoring photodiode, 7.
...Feedback circuit, 8...Mirror, 9...Objective lens. 10a, 10b--interference filter, 11a, 11b-
...Photodiode, 12a, 12b...Capacitor. 13a, 13b...Switch, 14...Half mirror-115a-15"...Amplifier, 16a, 16b-...
・Integrator, 17...Microprocessor.

Claims (1)

[Claims] Alternately irradiating the object to be measured with two types of light having the same or constant light intensity and different wavelengths, and measuring the emissivity ratio of the lights of different wavelengths based on the temperature rise of the object due to the light. A radiation thermometer characterized in that the temperature of the object to be measured is measured.