Wafer temperature measuring device and preparation method of narrow-band optical filter

Abstract

The invention provides a wafer temperature measuring device and a preparation method of a narrowband filter, the wafer temperature measuring device comprises an infrared temperature measuring module and a narrowband filter, the narrowband filter is arranged between a heating lamp and a wafer, and the infrared temperature measuring module is arranged below the wafer; the infrared temperature measurement module is configured to measure the temperature of the wafer through thermal radiation light of the wafer, wherein the wavelength of the thermal radiation light is 1.55 [mu] m; the narrowband filter is configured to reflect or absorb infrared light having a wavelength of 1.55 [mu] m. The narrow-band optical filter is arranged between the heating lamp and the wafer, the infrared temperature measurement module is arranged below the wafer, and the infrared light with the wavelength of 1.55 microns is reflected or absorbed through the narrow-band optical filter, so that the infrared light with the wavelength of 1.55 microns in background light cannot reach the infrared temperature measurement module; the infrared light with the wavelength of 1.55 [mu] m received by the infrared temperature measurement module is the thermal radiation light of the wafer itself, thereby eliminating the interference of the background light on the wafer temperature measurement, and improving the accuracy of the temperature measurement.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor manufacturing, and more specifically relates to a wafer temperature measuring device and a method for preparing a narrow-band filter. Background Art

[0002] Rapid thermal processing (RTP) equipment uses infrared temperature measurement. Existing pyrometers mostly use a narrow spectrum around 1 micron to measure temperature through photoelectric conversion. This type of pyrometer usually requires the wafer temperature to be above 300-400°C for measurement. However, as the temperature decreases, the spectrum intensity decreases rapidly, seriously affecting the sensitivity and accuracy of the detector and failing to accurately reflect the actual temperature of the wafer. Summary of the invention

[0003] Based on the technical problems existing in the prior art, the present invention provides a wafer temperature measuring device and a method for preparing a narrow-band filter, aiming to solve the technical problem that the sensitivity and accuracy of the pyrometer in the prior art decrease as the temperature decreases, and the actual temperature of the wafer cannot be accurately measured.

[0004] To achieve the above-mentioned purpose, according to the first aspect of the technical solution of the present invention, the present invention provides a wafer temperature measuring device, including an infrared temperature measuring module and a narrow-band filter, the narrow-band filter is arranged between the heating lamp and the wafer, and the infrared temperature measuring module is arranged under the wafer; the infrared temperature measuring module is configured to measure the temperature of the wafer through the thermal radiation light of the wafer, wherein the wavelength of the thermal radiation light is 1.55μm; the narrow-band filter is configured to reflect or absorb infrared light with a wavelength of 1.55μm.

[0005] Optionally, the infrared temperature measurement module includes an infrared sensor and an infrared thermometer connected to the infrared sensor, the infrared sensor is used to receive thermal radiation light from the wafer, and the infrared thermometer can obtain the temperature of the wafer based on the irradiation intensity of the thermal radiation light.

[0006] Optionally, the narrow-band filter includes alternately stacked transparent substrates and dielectric multilayer film structures, and each transparent substrate is provided with a dielectric multilayer film structure on the upper and lower sides; each dielectric multilayer film structure includes alternately stacked first reflective films and second reflective films, and each first reflective film is provided with a layer of second reflective film on the upper and lower sides, wherein the first reflective film is made of a low refractive index material, and the second reflective film is made of a high refractive index material.

[0007] Optionally, the transparent substrate is glass or quartz.

[0008] Optionally, the transparent substrate has a thickness of 1 to 3 mm.

[0009] Optionally, the number of film layers in the dielectric multilayer film structure is less than 80 layers.

[0010] Optionally, the bonding force between the multiple transparent substrates is greater than 40N / cm 2 .

[0011] Optionally, the low refractive index material is SiO2.

[0012] Optionally, the high refractive index material is Ta2O5.

[0013] According to the second aspect of the technical solution of the present invention, a method for preparing a narrow-band filter is provided, comprising: step S1. cleaning a transparent substrate; step S2. performing plasma activation treatment on the cleaned transparent substrate; step S3. coating a dielectric multilayer film structure on the surface of the transparent substrate by sputtering; step S4. stacking a plurality of transparent substrates coated with the dielectric multilayer film structure; step S5. firmly bonding the stacked plurality of transparent substrates coated with the dielectric multilayer film structure with a sealing adhesive component.

[0014] Compared with the prior art, the wafer temperature measuring device and the method for preparing a narrow-band filter provided by the present invention have the following beneficial effects: By setting a narrow-band filter between the heating lamp and the wafer and an infrared temperature measurement module under the wafer, the infrared light with a wavelength of 1.55μm is reflected or absorbed by the narrow-band filter, so that the infrared light with a wavelength of 1.55μm in the background light cannot reach the infrared temperature measurement module. The infrared light with a wavelength of 1.55μm received by the infrared temperature measurement module is all thermal radiation light of the wafer itself, thereby eliminating the interference of background light on wafer temperature measurement and improving the accuracy of temperature measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0016] Figure 1 A schematic diagram of the structure of a wafer temperature measuring device provided by an embodiment of the present invention; Figure 2 A schematic diagram of a blackbody spectrum distribution curve provided by an embodiment of the present invention; Figure 3 The transmittance of silicon, the material of the wafer provided in the embodiment of the present invention, to light with a wavelength of 1.55 microns; Figure 4 A schematic diagram of the structure of a narrow-band filter provided by an embodiment of the present invention; Figure 5A schematic diagram of the principle of a dielectric multilayer film provided by an embodiment of the present invention.

[0017] The reference numerals in the above drawings are as follows: 1. Process chamber; 2. Wafer holder; 3. Wafer; 4. Light box; 5. Heating lamp; 6. Infrared temperature measurement module; 61. Infrared sensor; 62. Infrared thermometer; 7. Narrowband filter; 71. Transparent substrate; 72. Dielectric multilayer film structure. DETAILED DESCRIPTION

[0018] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0019] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0020] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0021] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0023] As described in the background art, currently, infrared temperature measurement in the semiconductor industry usually uses a near-infrared narrow spectrum response with a wavelength of 1 micron, but it cannot measure wafers with temperatures between 160°C and 300°C.

[0024] Please refer to Figure 1 As shown, in order to solve the above problems, the present invention provides a wafer temperature measuring device, which is used in a process chamber 1 of a semiconductor device. As shown in the figure, a wafer holder 2 is arranged at the bottom of the process chamber 1, and a wafer 3 is arranged on the wafer holder 2. The top of the process chamber 1 has an opening, and a light box 4 is arranged at the opening. A plurality of heating lamps 5 for heating the wafer 3 are arranged in the light box 4, and the heating lamps 5 are usually halogen lamps. The wafer temperature measuring device includes an infrared temperature measuring module 6 and a narrow-band filter 7, wherein the narrow-band filter 7 is arranged between the heating lamp 5 and the wafer 3, and the infrared temperature measuring module 6 is arranged below the wafer 3; the infrared temperature measuring module 6 is configured to measure the temperature of the wafer 3 through the thermal radiation light of the wafer 3, wherein the wavelength of the thermal radiation light is 1.55μm; and the narrow-band filter 7 is configured to reflect or absorb infrared light with a wavelength of 1.55μm.

[0025] It should be noted that according to Wien's displacement law: as the temperature increases, the wavelength that radiates the most energy will become shorter; conversely, as the temperature decreases, the wavelength that radiates more energy will become longer, so it is necessary to select a relatively long wavelength to measure low-temperature wafers, such as Figure 2 The technical solution of the present invention selects the short-wave infrared band with a wavelength of 1.55 microns as the measurement band, but Figure 3 As shown, the material of the wafer 3, silicon, has a transmittance of about 50% for light with a wavelength of 1.55 microns. Therefore, about 50% of the infrared light with a wavelength of 1.55 microns in the background light can pass through the wafer 3 and be received by the infrared temperature measurement module 6, and interfere with the temperature measurement of the wafer 3, reducing the accuracy of temperature measurement. In order to avoid the interference of background light, a narrow-band filter 7 is added between the wafer 3 and the heating lamp 5 to reflect or absorb the infrared light with a wavelength of 1.55 microns in the background light, thereby improving the temperature measurement accuracy of the infrared temperature measurement module 6 for 160°C to 300°C wafers.

[0026] By applying the above technical scheme of the present invention, a narrow-band filter 7 is arranged between the heating lamp 5 and the wafer 3, and an infrared temperature measurement module 6 is arranged under the wafer 3. The narrow-band filter 7 reflects or absorbs infrared light with a wavelength of 1.55 μm, so that the infrared light with a wavelength of 1.55 μm in the background light cannot reach the infrared temperature measurement module 6. The infrared light with a wavelength of 1.55 μm received by the infrared temperature measurement module 7 is all thermal radiation light of the wafer 3 itself, thereby eliminating the interference of the background light on the temperature measurement of the wafer 3 and improving the accuracy of the temperature measurement.

[0027] See also Figure 1 As shown, in some embodiments, the infrared temperature measurement module 6 includes an infrared sensor 61 and an infrared thermometer 62 connected to the infrared sensor 61, the infrared sensor 61 is used to receive the thermal radiation light of the wafer, and the infrared thermometer 62 can obtain the temperature of the wafer 3 based on the irradiation intensity of the thermal radiation light. Specifically, the heating lamp 5 heats the wafer 3, and the wafer 3 emits thermal radiation light when heated. The infrared sensor 61 detects the thermal radiation light and obtains an electrical signal, which is used to characterize the intensity of the thermal radiation light. The infrared thermometer 62 obtains the temperature of the wafer 3 according to the electrical signal.

[0028] See also Figure 1 and Figure 4 As shown, in some embodiments, the narrowband filter 7 includes a transparent substrate 71 and a dielectric multilayer film structure 72 alternately stacked, and each transparent substrate 71 is provided with a dielectric multilayer film structure 72 on both sides; each dielectric multilayer film structure 72 includes a first reflective film and a second reflective film alternately stacked, and each first reflective film is provided with a second reflective film on both sides, wherein the first reflective film is made of a low refractive index material, and the second reflective film is made of a high refractive index material. It should be noted that the reflectivity R of an optical element coated with a single layer of film when light is incident vertically is (n1-n2) 2 / (n1+n2) 2 In the calculation formula, n1 and n2 are the refractive indices of two different materials. It can be seen that the larger n1 is, the larger R is. However, the actual film refractive index n1 is limited, and the maximum reflectivity that a single-layer film can achieve will not exceed 50%. Figure 5 As shown, if a high refractive index (n H ), low refractive index (n L ) alternating dielectric multilayer film structures, and the outermost layers on both sides of the dielectric multilayer film structure 72 are high refractive index layers, each layer has a thickness of (λ0 / 4), when (n H / n L ) is larger, the more layers (2S+1) there are, where S is the number of low refractive index film layers, and the maximum reflectivity R for vertical incidence at the center wavelength (λ0) is maxThe larger (λ0), the closer it can be to 100% in theory. However, the reflective film needs to limit the number and thickness of the film in the dielectric multilayer film structure 72, otherwise it will cause excessive stress in the film layer or even film peeling. In order to solve the problem of excessive stress, the present invention reduces the number of single coating layers and increases the dielectric multilayer film structure. Specifically, the transparent substrate 71 is made into a thin sheet of about 1 mm, and a dielectric multilayer film structure 72 is plated on one side thereof, and finally n (n>2) coated transparent substrates 71 are pressed into an integrated narrowband filter 7. Increasing the number of coating layers in this way can make the pass rate of short-wave infrared light with a wavelength of 1.55 microns less than 0.1%, and at the same time solve the problem of excessive stress or even film peeling caused by the increase in the number of single coating layers. Using this narrowband filter 71 between the wafer 3 and the heating lamp 5 can effectively reduce the interference of background light on infrared temperature measurement of wafers with a temperature of 160°C to 300°C, and improve the temperature measurement accuracy of the wafer.

[0029] In some embodiments, the transparent substrate 71 is glass or quartz. The narrow-band filter 7 made on the glass or quartz material has high reflectivity and stability.

[0030] In some embodiments, the thickness of the transparent substrate 71 is 1-3 mm. This arrangement can ensure the strength of the transparent substrate 71 and prevent deformation caused by coating stress.

[0031] In some embodiments, the number of film layers in the dielectric multi-layer film structure 72 is less than 80 layers.

[0032] In some embodiments, the bonding force between the plurality of transparent substrates 71 is greater than 40 N / cm 2 , can avoid peeling.

[0033] In some embodiments, the low refractive index material is SiO 2. Of course, other low refractive index materials such as SiO 3, Al 2 O 3 or MgF 2 may also be used.

[0034] In some embodiments, the high refractive index material is Ta2O5. Of course, other high refractive index materials such as TiO2, Nb2O5 or HfO2 may also be used.

[0035] The present invention provides a method for preparing a narrow-band filter, which is used in the wafer temperature measuring device of the present invention. The method for preparing the narrow-band filter 7 comprises: Step S1. Cleaning the transparent substrate 71; Step S2. performing plasma activation treatment on the cleaned transparent substrate 71; Step S3. A dielectric multilayer film structure is deposited on the surface of the transparent substrate 71 by sputtering. Specifically, the first reflective film and the second reflective film are alternately plated on the surface of the transparent substrate 71 for multiple times.

[0036] Step S4. stacking a plurality of transparent substrates 71 coated with dielectric multilayer film structures; Step S5: Use a sealing adhesive component to firmly bond the stacked transparent substrates 71 coated with a dielectric multilayer film structure.

[0037] In some embodiments, the transparent substrate 71 is a glass or quartz sheet with a thickness of 1 to 3 mm, and the coating material is SiO2 and Ta2O5. The surface of the glass or quartz sheet is cleaned with acetone, anhydrous ethanol and deionized water in turn; plasma is used to remove tiny particles on the surface of the glass or quartz sheet, activate the substrate surface, and improve the adhesion of the film; SiO2 and Ta2O5 are alternately coated on the surface of the glass or quartz sheet multiple times by sputtering coating, wherein the coating requires that the infrared light transmittance of a wavelength of 1.55 μm is less than 0.1%, the infrared light transmittance of a wavelength of 0.7-1.1 microns is greater than 96%, and the average infrared light transmittance of a wavelength of 0.3-2.5 microns is greater than 95%; multiple coated glass or quartz sheets are stacked, wherein the number of film layers in the dielectric multilayer film structure is less than 80.

[0038] In summary, the wafer temperature measurement device and the method for preparing a narrow-band filter provided in this embodiment have at least the following beneficial technical effects: By arranging a narrowband filter 7 between the heating lamp 5 and the wafer 3, and arranging an infrared temperature measurement module 6 under the wafer 3, the infrared light with a wavelength of 1.55 μm is reflected or absorbed by the narrowband filter 7, so that the infrared light with a wavelength of 1.55 μm in the background light cannot reach the infrared temperature measurement module 6, and the infrared light with a wavelength of 1.55 μm received by the infrared temperature measurement module 7 is all thermal radiation light of the wafer 3 itself, thereby eliminating the interference of the background light on the temperature measurement of the wafer 3 and improving the accuracy of the temperature measurement.

[0039] The above are only preferred embodiments of the present invention, and only specifically describe the technical principles of the present invention. These descriptions are only for explaining the principles of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations here, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention, and other specific implementations of the present invention that can be associated with by technicians in this field without creative labor, should be included in the scope of protection of the present invention.

Claims

1. A wafer temperature measuring device, characterized in that: It includes an infrared temperature measurement module and a narrow-band filter, wherein the narrow-band filter is arranged between the heating lamp and the wafer, and the infrared temperature measurement module is arranged below the wafer; The infrared temperature measurement module is configured to measure the temperature of the wafer through the thermal radiation light of the wafer, wherein the wavelength of the thermal radiation light is 1.55 μm; The narrow band filter is configured to reflect or absorb infrared light having a wavelength of 1.55 μm.

2. The wafer temperature measuring device according to claim 1, characterized in that: The infrared temperature measurement module includes an infrared sensor and an infrared thermometer connected to the infrared sensor, the infrared sensor is used to receive the thermal radiation light of the wafer, and the infrared thermometer can obtain the temperature of the wafer based on the irradiation intensity of the thermal radiation light.

3. The wafer temperature measuring device according to claim 1, characterized in that: The narrowband filter comprises a transparent substrate and a dielectric multilayer film structure which are alternately stacked, and each of the transparent substrates is provided with a dielectric multilayer film structure on both sides of the upper and lower sides; Each of the dielectric multilayer film structures includes a first reflective film and a second reflective film alternately stacked, and a layer of the second reflective film is provided on the upper and lower sides of each of the first reflective films, wherein the first reflective film is made of a low refractive index material, and the second reflective film is made of a high refractive index material.

4. The wafer temperature measuring device according to claim 3, characterized in that: The transparent substrate is glass or quartz.

5. The wafer temperature measuring device according to claim 3, characterized in that: The thickness of the transparent substrate is 1 mm to 3 mm.

6. The wafer temperature measuring device according to claim 3, characterized in that: The number of film layers in the dielectric multi-layer film structure is less than 80.

7. The wafer temperature measuring device according to claim 3, characterized in that: The bonding force between multiple transparent substrates is greater than 40N / cm 2 .

8. The wafer temperature measuring device according to claim 3, characterized in that: The low refractive index material is SiO2.

9. The wafer temperature measuring device according to claim 3, characterized in that: The high refractive index material is Ta2O5.

10. A method for preparing a narrow-band filter, wherein the prepared narrow-band filter is used in the wafer temperature measurement device according to claim 3, characterized in that: The preparation method of the narrow-band filter comprises: Step S1. Cleaning the transparent substrate; Step S2. performing plasma activation treatment on the cleaned transparent substrate; Step S3. sputtering to form a dielectric multilayer film structure on the surface of the transparent substrate; Step S4. stacking a plurality of transparent substrates coated with dielectric multilayer film structures; Step S5: Use a sealing adhesive component to firmly bond the stacked transparent substrates coated with the dielectric multilayer film structure.

Images