TW528860B - Temperature measuring method and apparatus and semiconductor heat treatment apparatus - Google Patents

Abstract

A radiation thermometer measures a temperature of a semiconductor wafer according to a non-contact manner without using a complicated hardware structure. A state variable is obtained according to estimate algorithm calculation based on a result of measurement of a radiation light from the semiconductor wafer. The state variable includes an effective emissivity as an unknown variable. The temperature of the semiconductor wafer is calculated based on the calculated state variable.

Description

528860 A7 B7 V. Description of the Invention (1) Technical Field The present invention relates to a temperature measurement technology using a radiation thermometer, and particularly to a temperature measurement method and device for measuring the temperature of an object to be measured in a non-contact manner. BACKGROUND ART During the heat treatment of a semiconductor wafer, the temperature of the heated semiconductor wafer must be accurately measured. A contact-type temperature measuring device, such as a thermocouple, cannot be used to measure the temperature of a semiconductor wafer because the actual semiconductor circuit will be formed on the surface of the semiconductor wafer. Therefore, on a semiconductor wafer heat treatment apparatus, a radiation thermometer is usually used to measure the temperature of the semiconductor wafer. A radiation thermometer measures the intensity of infrared rays emitted from the surface of an object to be measured, and estimates the temperature of the object to be measured from the measured intensity. The intensity of infrared radiation emitted by a semiconductor wafer varies with the emissivity of the radiating surface of the semiconductor wafer. For example, when an oxide film is formed on the radiating surface of a semiconductor wafer, the emissivity of this oxide film will be different from the emissivity of the semiconductor wafer surface during the initial heating period. Therefore, a measurement method which is not affected by the emissivity of the radiating surface and a measurement method which can modify the emissivity as described below have been proposed. 1) Use a reference light source with a predetermined intensity to irradiate a test object (semiconductor wafer), and measure the intensity of the reference light source reflected by the test object to obtain its actual emissivity. In other words, according to the relationship (emissivity = reflection factor-1), the actual emissivity can be obtained, and the temperature of the object to be measured can be obtained from the emissivity. -4-This paper size is in accordance with Chinese National Standard (CNS) A4 specification (210 X 297 mm) 5. Description of the invention (2 2) Establish two or more effective emissivity states and calculate Solve the equation to get the emissivity. After the emissivity obtained in this way is calculated, the temperature of the object to be measured can be obtained. U.S. Patent No. 5,6660,472 has disclosed one such approach. 3) Form a multiple reflection structure with the object to be measured so that its effective emissivity is close to 1. For example, after a semiconductor wafer to be tested is arranged, the light radiated from the surface of the semiconductor wafer Multiple reflections are generated between the semiconductor wafer and the positioning platform, and the temperature of the object to be measured can be calculated based on the multiple reflections and the intensity of the radiated light. That is, the temperature I is calculated by assuming that an object to be measured is a pseudo-black body (emissivity = 丨). Examples of this method are disclosed in U.S. Patent Nos. 6,174,080 and 6,293,696. There is a problem with the above-mentioned radiation thermometer temperature measurement method, that is, the measurement device has a complicated structure and is expensive. Furthermore, another problem is that the temperature accuracy of the measurement is not high due to the low reproducibility of the results. This is due to the environmental changes that occur when the temperature measurement point is approached and the I measurement system formed over time. The impact of factors such as characteristics changes. For example, the aforementioned method 1) uses a reference light source with a predetermined intensity to illuminate the object to be measured, and the wavelength and intensity of the reference light source need to be accurately controlled. However, a device capable of generating such an accurate reference light source is expensive β In addition, although The aforementioned method 2) establish two or more states of effective emissivity, and maintain the environmental conditions close to the temperature measurement point to achieve 528860 A7 B7 V. Description of the invention (3) A predetermined effective emissivity state. However, it is not easy to maintain the environment near the temperature measurement point. Furthermore, if the characteristics of the measurement system change over time, it is very difficult to maintain accurate temperature measurement under the influence of this change in characteristics over time. In addition, although method 3) forms a multiple reflection structure with the object to be measured, it is necessary to form multiple reflections between the object to be measured and an object having a reflectance equal to 1. However, no object with a reflectance equal to 1 actually exists. Therefore, its calculation must be performed by treating an object with a reflectance not equal to 1 as an object with a reflectance equal to 1, thus causing an unavoidable error. This error will be included in the temperature value obtained by using this calculation method. 0 DISCLOSURE OF THE INVENTION The purpose of the present invention is to propose an improved and effective temperature measurement method to eliminate the aforementioned problems. A more precise object of the present invention is to propose a temperature measurement method and device, so as to accurately measure the temperature of an object to be measured using a non-contact method, without using a complicated hardware structure. In addition, a semiconductor heat treatment apparatus using this temperature measurement method is also proposed. In order to achieve the above-mentioned object, on the one hand, the present invention will propose a non-contact temperature measurement method to measure the temperature of an object to be measured. The steps include: measuring the radiation emitted by the object to be measured; The estimated value made by the measurement results is calculated algorithmically to obtain a state variable; the state variable obtained from this operation is used to calculate the temperature of the object to be measured. Steps to obtain this state variable according to the temperature measurement method obtained by the present invention-6-This paper size applies Chinese National Standard (CNS) A4 specification (210 X 297 mm) 528860 A7 B7 V. Description of the invention (4) Step includes input This state variable is obtained by calculating an energy value for heating the object to be measured, and calculating based on a thermal balance model that takes the energy value as an input and the measurement result of the radiated light as an output. This state variable also contains an unknown variable of the temperature of the object to be measured. This estimated algorithm is an extension of the Kalman filter algorithm, which is obtained by extending the Kalman filter and wave algorithm to a non-linear system. In addition, another part of the present invention also provides a non-contact temperature measuring device for measuring the temperature of the object to be measured, which includes: a measuring device required to measure the radiant light emitted by the #measuring object; and a state value capture Taking a device so as to perform an arithmetic calculation of the estimated value according to the measurement result of light rays (the measurement result of the ray is an unknown variable with an effective emissivity) to obtain a state variable; a temperature calculation device, In order to calculate the temperature of the object to be measured according to the state variables obtained from the operation. In the temperature measuring device obtained according to the present invention, the state value acquisition device includes an input device for inputting an energy value for heating the object to be measured, so as to facilitate a measurement result based on an energy value input and radiated light. Calculate this state variable for the output heat balance model. The measurement result of the radiated light is a state variable and includes an unknown variable of the temperature of the object to be measured. This estimated value algorithm operation can be an extension of the Kalman filter algorithm, which is obtained by extending the Kalman filter algorithm to a non-linear system. Furthermore, another part of the present invention also proposes a semiconductor heat treatment device, which can perform heat treatment on semiconductor substrates, including: a heating device for heating the semiconductor substrate; a radiation thermometer for measuring the temperature of the semiconductor substrate, this radiation-7-this paper Standards apply to China National Standard (CNS) A4 (210 X 297 mm)

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528860 A7 B7 V. Description of the invention (5) The radiation thermometer includes: a measuring device for measuring the radiated light emitted by a heated semiconductor substrate, an arithmetic calculation based on an estimated value, and a measurement result of the radiated light (the measurement result of the radiated light is The effective variable emissivity of the unknown variable) to obtain a state variable acquisition device of a state variable; in addition, it includes a temperature calculation device, which can calculate the temperature of the object to be measured according to the state variable obtained by this operation; The control device can adjust the energy provided to the heating device according to the temperature calculated by the temperature calculation device. In the semiconductor heat treatment device provided by the present invention, the state variable capturing device includes an input device for inputting an energy value for heating an object to be measured, so as to facilitate a measurement result based on an energy value input and radiated light ( The measurement result of this radiant ray is a state variable and includes an unknown variable of the temperature of the object to be measured) as the output heat balance model to calculate this state variable. This estimated value algorithm operation can be an extension of the Carmen filter algorithm, which is obtained by extending the Carmen filter algorithm into a non-linear system. According to the above invention, the temperature of the object to be measured is obtained by calculating and estimating its effective emissivity, so there is no need to actually measure its effective emissivity. That is, the temperature of the object to be measured can be known only by measuring the light emission intensity of the object to be measured. Therefore, a hardware architecture for measuring effective emissivity becomes redundant, thereby reducing its corresponding manufacturing price. The estimation of the effective emissivity and the calculation of the temperature of the object to be measured are obtained by performing an algorithm calculation of the estimated value based on a thermal equilibrium model containing the effective emissivity and the temperature of the object to be measured. Such algorithms are easy to set up. In addition, the estimation with the extended Carmen filter algorithm is performed -δ _ This paper size applies to China National Standard (CNS) Α4 specification (210 X 297 mm) 528860

θ 2 is a functional block diagram of the radon thermometer shown in FIG. 1; FIG. 3 is a schematic illustration of a thermal balance model on which the radiation thermometer is calculated; and FIG. 4 is a diagram showing the estimated temperature and effective radiation of the semiconductor wafer A block diagram of the rate process. f The present invention contains the most clarified solution. As shown in FIG. 1, a semiconductor heat treatment device implemented according to the present invention will be described below. Fig. 1 is a cross-sectional view of a semiconductor heat treatment apparatus realized according to the present invention. The thermal processing apparatus shown in FIG. 1 is a rapid thermal processing (RTP) apparatus, which can perform rapid thermal processing on a semiconductor wafer placed in a rapid thermal processing chamber. The 7F I heat treatment device i shown in FIG. 1 can heat a semiconductor wafer 3 quickly by using heat rays emitted by the halogen lamp 2 at a temperature of 1000 to achieve the purpose of performing heat treatment on the semiconductor wafer 3. The toothed lamp 2 is attached to a toothed lamp holder 4. The element lamp holder 4 has a power adjustment circuit (not shown) to adjust the electric power supplied to the element lamp 2. The semiconductor wafer 3 is completed in a heat treatment chamber 5. A quartz support ring 6 is placed in the heat treatment chamber 5 and a protective ring 7 is attached to the quartz support ring 6 (fifth, description of the invention)

Twenty two = put 6 :, protect the top and make the semiconducting Zhao Jing I back instead of the second m: so ’semiconductor thinks about the gap of wafer 3. One knife is facing the bottom of the flat plate 8 and a small one is formed between the two. It is made of a material with high reflectivity to reflect the radiation emitted by the ... , Can make half ^ t, t radiate light and = over light. The stone connected to the thermometer 1G is at a predetermined position in ㈣ =. The quartz rod u is connected to the semiconductor wafer 3 to radiate light, and the radiation ray absorbed by the stone rod 11 will pass through the light, and will be transmitted to the radiation thermometer 10. ^ Thermometer 1 () can be measured based on the light transmitted through ㈣9. + = The light intensity of light emitted from the body wafer 3, and according to this measurement result: the temperature of the abundant conductor wafer 3 is different. In other words, the 'radiation thermometer' calculates the temperature of the semiconductor based on the -f conductor crystal sm light measurement results. The radiation thermometer 10 transfers the calculated temperature of the semiconductor wafer 3 to the control unit i 3 through a series of connections 12. This control unit 3 is a device that controls the operation of the heat treatment device 1 and is connected to a power adjustment circuit located inside the toothed lamp holder 4. The power adjustment circuit can control the supply to the element according to the control signal issued by the control unit 3 Electrical power of lamp 2. Therefore, the process of heating the semiconductor wafer 3 using the halogen lamp 2 can be controlled, and the semiconductor wafer 3 is heated or maintained at a predetermined temperature. The light-emitting thermometer 10 shown in FIG. 1 will be described below based on FIG. 2. -10- This paper size applies to China National Standard (CNS) A4 (210X297 mm) 528860

FIG. 2 is a functional block diagram of light, private, itching, 丄, m degree w 10 in FIG. 1. This light thermometer 10 has a radiant ray measuring section 20 and a calculating section 22. The optical fiber 9 is connected to the radiant ray measurement section 20, and the light rays emitted from the semiconductor wafer 3 are transmitted to the radiant ray measurement section 20 via the optical fiber 9. The radiant ray measurement section 20 measures various items including the intensity of radiant ray transmitted through the optical fiber 9 and transmits the measurement results to the calculation section 22 ° The calculation section knife 2 2 calculates based on the measurement results provided by the radiant ray measurement section 2 〇 The temperature of the semiconductor wafer 3 can be obtained later. The semiconductor wafer 3 < temperature is transmitted to the control section 3 via the connection line 12. In addition, the electric power value to be transmitted to the pixel lamp 2 is transmitted from the control section 13 to the calculation section 22 via the connection line 12.2. Next, a description will be given of a temperature estimation method on which the calculation section 22 performs temperature calculation. This temperature estimation method is carried out ㈣—a device model regarding the thermal balance of the semiconductor wafer 3 as the object to be measured. Fig. ^ Is a schematic illustration of a heat balance model according to which the calculation part 22 of the radiation thermometer is calculated. In the heat balance model shown in Fig. 3, the heat conduction amount of the wafer can be expressed by the following formula (1), where Δ is a discrete time interval. δ〇 = ΔχΛ, κε ^ + ε, θ ^ σΤ: .4 ^)-willow 0-L (0) -moxibustion 2 (Γ / (0-(0) + ^ (w (r))) (1) In equation (1), the subscript i indicates that when the semiconductor wafer 3 is divided into multiple identical -11-

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: Circle = 'i-th element of semiconductor wafer 3' and A; prime field. kJk2 is the coefficient of heat conduction, and. For Steguel 2 :: Γ hanging number. In addition, ε 1 represents the placement of the reflector 4 a of the halogen lamp holder 4, and ε 2 represents the emissivity of the surface of the bottom plane 8. The surface dances: the wafer 3. In order to consider the effective emissivity when facing the multiple reflections of the semiconductor wafer 3 of the toothed lamp 2, the% ^ is the effective emissivity when considering the multiple reflections on the bottom plate 8 (the surface of the semiconductor wafer 3). Furthermore, in formula (1), u is the input of the halogen lamp (for example, the current transmitted to the halogen lamp), and the light energy transmitted by the halogen lamp 2 to the semiconductor wafer 3 is given by the function g (u ). The first term in formula ⑴ represents the heat radiated from the front and back sides of the semiconductor wafer #, the second term represents the plutonium exchange amount between element BU1 and element i + 1, and the third term represents the halogen light The heat input. In addition, the temperature of the element 'is represented by the following formula ⑺, where Me! Is the heat capacity of the element i.

Ti (t + i) = (t) + AQ / M〇i (2) In addition, the light ray intensity measured by the radiation / mmeter is expressed by the following formula (3) using Planck's law , Where h is the Planck constant, c is the speed of light, kB is the Bozman constant, and λ is the wavelength obtained from the measurement. y (r) = ^ 2tt / ic202 A5expi _ ^ _ Vl ⑶

\ kBxm J Calculate the semiconductor wafer temperature L .__ -12- according to the formulas (1), (2), and (3) above. Explanation (10) The extended Carmen wave method that estimates the effective emissivity can be set by setting the effective emissivity center and t of the front and back sides of the semiconductor wafer as unknown and setting this half; the temperature of bile and yen is a state variable. Design. Figure 4 is a block diagram showing the process of estimating the effective emissivity and temperature of an actual semiconductor wafer. This Carmen filtering method is an online data algorithm, which can be based on the dynamic characteristics of a system that generates signals, 2 ) The statistical characteristics of a noise, 3) the previous information about the initial value and the observation data obtained over time to continuously provide a least square estimate of the state of the system. Assume that the difference equation of a linear system can be expressed by the following formula (4), where u is the input, y is the output, and X is the state. ^ = + B (u (+ w (yt ^ Ctxt + vt (4), according to one of the Carmen filtering methods, the estimated value of the state x χ Λ can be expressed by the following formula (5) (5) where t is one of the discrete-time systems At the time point, it is a value with Carmen gain. This card n gain Kt can be expressed by the following formula ⑷, using the common variable analysis matrix Pt /, 丨, [Xt_x ~ t 乂 of the estimated value error (Xt_ ~) and adding the output signal The common variable analysis moment of noise is expressed as 1 R t '. (6) _______ -13 ·

This paper is suitable for S S M ^ HCNS) A4 ^ (21〇X297 ^ T 528860 A7 B7 V. Description of the invention (11)

The design of the Carmen filter method is based on a linear system similar to equation (4). An extended Kalman filter method takes a linearization step near the operating point in order to extend the Kalman filter method to a nonlinear system. That is, the Carmen filter method can be designed for a system with known operating characteristics. However, when an unknown constant is included, the unknown value will be reselected as a variable to establish the differential equation of the system, and then an extended filtering method can be designed using the extended Carmen filter algorithm. When a system can be represented by the following equation containing an unknown value 0, one of the state variables X in the differential equation (7) of this system can be replaced by z, as shown in equation (8) to obtain equation (9 ). ^ r + l = Α (θ) Xf + Β (β) Ug + W (= + Vf

(B)

rA (G) x (+ B (9) ut, Θ

Therefore, the state value X (for example, the temperature of the semiconductor wafer) can be obtained by calculating and performing an extended Carmen filter algorithm on equation (9) to estimate the unknown value Θ. It should be noted that the coefficients A, B and c in the above formula (4) are determined based on the results of various experimental comparisons using a black body furnace. As mentioned above, in the current entity, the temperature of this semiconductor wafer 3 can be -14-

528860 A7 B7 V. Description of the invention (12) In the calculation part 22 of the radiation thermometer 10, an extended Carmen filter method is used to estimate the emissivity of the semiconductor wafer 3 and obtain it. When using a radiation thermometer to measure the temperature of a bare wafer heated to about 600 ° C and a heating rate of 10 ° C / sec according to the current entity, the error of the temperature measured by using a thermocouple is about ± 1 0 ° C. As mentioned above, the current radiation thermometer in the entity can obtain a temperature value which is very close to the actual temperature only by measuring the intensity of the radiation. Therefore, the structure of the radiation thermometer can be simplified, and the radiation thermometer can be manufactured at a price of about 1/4 that of a conventional radiation thermometer that actually measures emissivity. The invention is not limited to the entities explicitly disclosed, and any possible variations and modifications will not exceed the scope of the invention. __- 15- This paper size applies to China National Standard (CNS) A4 (210X297 mm)

Claims (1)

528860 A8 B8 C8 Patent Application Scope • A temperature measurement method that measures the temperature of an object to be measured in a non-contact manner, the steps include: measuring the radiation emitted by the object to be measured; and estimating the value based on the measurement results of this radiation Algorithm to obtain a state variable that includes the effective emissivity of an unknown variable; and The temperature of the object to be measured is calculated based on the state variables obtained from this operation. 2. If the temperature measurement method according to item 1 of the scope of patent application, wherein the step of obtaining a state variable includes inputting an energy value for heating the object to be measured, and calculating the state variable according to a thermal equilibrium model, the thermal equilibrium model has a The input of I value and the output of a ray measurement result. The measurement result of the radiant ray is another state variable with the temperature of the object to be measured being an unknown variable. 3 · = Application, the temperature measurement method of item 1 of the profit range, wherein the estimated value calculation 夬 operation is an extended Carmen filter algorithm obtained by extending the ^ gate filtering method to form a nonlinear system. 4 .: A type of temperature measuring device ‘measures the temperature of an object to be measured in a non-contact manner’, which includes: Measure! Measuring device for radiated light emitted from the object to be measured; an estimation algorithm calculation is performed according to the measurement result of the radiated ray, and a state value acquisition device for obtaining a #like complaint variable, and the state variable includes an effective emissivity of an unknown variable ; And calculate the temperature of the object to be measured according to the state variables obtained by this operation -16- 528860 6 5. 6. 7. A8 B8 C8 D8 Patented temperature calculation device. For example, the temperature measurement device of the fourth scope of the patent application, wherein the state value acquisition device includes an input device for inputting an energy value for heating the object to be measured, and calculates the state variable according to a thermal equilibrium model, and the thermal equilibrium model It has an input of an energy value and an output of the measurement result of the radiant ray, and the measurement result of the radiant ray is another state variable having an unknown variable temperature of the object to be measured. For example, the temperature measurement device according to item 4 of the patent application, wherein the estimated value algorithm operation is an extended Carmen filter algorithm obtained by extending a Carmen filter method to form a nonlinear system. A semiconductor heat treatment device that can perform heat treatment on a semiconductor substrate includes: a heating device for heating the semiconductor substrate; a radiation thermometer for measuring the temperature of the semiconductor substrate, and the radiation thermometer includes a measurement device for measuring light rays emitted from the heated semiconductor substrate And a state variable acquisition device, which can perform an estimation algorithm calculation to obtain a state variable based on the radiant ray measurement result, and the state variable includes an effective emissivity of an unknown variable, and further includes a temperature calculation device, which can The temperature of the object to be measured is calculated according to the state variables obtained from the calculation; and the control device can adjust the energy transmitted to the heating device according to the temperature calculated by the temperature calculation device. For example, the semiconductor heat treatment device for item 7 of the patent application scope, wherein the state variable extraction device includes inputting an energy value for heating the object to be measured. -17- This paper size applies to China National Standard (CNS) A4 specification (210X297 mm). ) 528860 Six A8 B8 C8 D8 patent-applied input devices, and based on a thermal balance model that takes an energy value as input and a measurement result of Korean rays as output, to calculate this state variable, and the measurement result of the radiant light is Another state variable has the temperature of the object to be measured is an unknown variable. For example, the semiconductor heat treatment device of the seventh patent application range, wherein the estimated value arithmetic operation is an extended Carmen filter algorithm obtained by extending a Carmen filter method to form a non-linear system. -18- This paper size applies to China National Standard (CNS) A4 (210X297 mm)