TW201829992A - Characterization apparatus based on fourier transform infrared spectroscopy - Google Patents

Abstract

The present invention relates to a Characterization apparatus based on Fourier transform infrared spectroscopy. Through two movable reflecting mirrors inclined to a horizontal plane, light flux of infrared light may be increased by passing through wafer twice before reaching detector for digital signal transformation. Similarly, an additional V-shaped mirror may be used for increasing light flux. More intensity of the Infrared light may be absorbed by the wafer by the twice passing through the wafer. Therefore, the sensitivity to carbon concentration in the wafer may be enhanced, with the assumption that the thickness of the wafer is not changed, to facilitate the detection of the carbon concentration.

Description

   Characterization equipment based on Fourier transform infrared spectrum   

The invention relates to the technical field of semiconductor manufacturing, and in particular, to a characterization device based on Fourier transform infrared spectroscopy (FTIR).

The structure diagram of an existing FTIR analyzer is shown in FIG. 1, which mainly includes a light source 10, an interferometer 11, a detector 12, and two reflecting mirrors 13 and 14. The infrared light emitted by the light source 10 passes through the interferometer 11 and is incident on the wafer 15; the detector 12 is used to detect the infrared light after passing through the wafer 15. Because FTIR has the advantages of non-contact and pollution-free, in the field of semiconductors, FTIR has been widely used as a characterization tool to detect the concentration of carbon and oxygen on wafers. With the development of integrated circuits, in order to avoid the impact of wafers on the production yield of integrated circuits, the carbon concentration on the wafer must be controlled in a very low range, so the characterization tools must show better carbon concentration performance.

If the carbon concentration on the wafer is less than 0.1 ppma, by far the most common method is to increase the thickness of the wafer. FTIR can detect low carbon concentration (less than 0.1ppma) wafers with a thickness greater than 1.5mm, but cannot detect wafers that are too thin. In addition, detecting too thick wafers will reduce the service life of FTIR machines with automated systems.

The purpose of the present invention is to provide a FTIR-based characterization device to improve the problem that the existing FTIR device cannot detect the carbon concentration on an excessively thin wafer.

In order to solve the above technical problem, the present invention provides a FTIR-based characterization device, which includes two movable mirrors, and the two movable mirrors are inclined with a horizontal plane for reflecting the infrared light onto a wafer.

In the FTIR-based characterization device provided by the present invention, two movable mirrors inclined to the horizontal plane are added to increase the luminous flux and pass through the wafer twice before the infrared light reaches the detector and is converted into a digital signal; Based on the same principle, another V-shaped mirror can be added to the present invention. The infrared light passing through the wafer twice increases the amount of infrared light absorbed by the wafer, and increasing the amount of absorbed infrared light can keep the thickness of the wafer constant. The sensitivity of the carbon concentration in the wafer is enhanced, so that the characterization device can detect the carbon concentration in the wafer without increasing the thickness of the wafer.

10‧‧‧ light source

11‧‧‧ interferometer

12‧‧‧ Detector

13, 14‧‧‧ mirrors

15‧‧‧Chip

20‧‧‧ light source

21‧‧‧Interferometer

22‧‧‧ Detector

23, 24‧‧‧movable mirror

25‧‧‧Motor

26‧‧‧The first mirror

27‧‧‧Second Mirror

28‧‧‧Chip

30‧‧‧ light source

31‧‧‧ interferometer

32‧‧‧ Detector

33‧‧‧V type mirror

34‧‧‧First Mirror

35‧‧‧Second Mirror

36‧‧‧Chip

40‧‧‧light source

41‧‧‧Interferometer

42‧‧‧ Detector

43, 44‧‧‧ fixed mirror

45‧‧‧first mirror

46‧‧‧Second Mirror

47‧‧‧Chip

FIG. 1 is a schematic diagram of an existing FTIR-based characterization device; FIG. 2 is a schematic diagram of a FTIR-based characterization device provided in Embodiment 1 of the present invention; and FIG. 3 is a FTIR-based characterization device structure provided in Embodiment 2 of the present invention Schematic diagram; FIG. 4 is a schematic structural diagram of a FTIR-based characteristic device provided in Embodiment 3 of the present invention.

The FTIR-based characterization device provided by the present invention will be further described in detail below with reference to the drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and the scope of patent application. It should be noted that the drawings are in a very simplified form and all use inaccurate proportions, which are only used to facilitate and clearly assist the description of the embodiments of the present invention.

Example one

FIG. 2 is a schematic structural diagram of an FTIR-based characterization device provided by Embodiment 1 of the present invention, which uses infrared light to characterize the carbon concentration in a wafer. The FTIR-based characterization device includes two movable mirrors 23 and 24, The moving mirror 23 and the movable mirror 24 are inclined to the horizontal plane, and are used to reflect the infrared light back onto the wafer. And the movable mirror 23 and the movable mirror 24 are both connected to a motor 25, and the motor 25 is used for driving the movable mirror 23 and the movable mirror 24 to move in a horizontal plane, To change the position where the infrared light is incident on the wafer.

Specifically, the FTIR-based characterization device further includes a light source 20, an interferometer 21, a detector 22, and two reflecting mirrors. The two reflecting mirrors are a first reflecting mirror 26 and a second reflecting mirror 27, respectively. To change the direction of incidence of infrared light. The infrared light emitted by the light source 20 passes through the first reflecting mirror 26, changes its direction, enters the interferometer 21, and then reflects through the second reflecting mirror 27 onto the wafer 28; the detector 22 is used to detect penetration Infrared light after passing through the wafer 28.

Specifically, material nickel is deposited on the surfaces of the movable mirror 23 and the movable mirror 24. The material nickel has excellent corrosion resistance, high temperature resistance, and a high reflection coefficient, which makes it harsh in humidity and the like. Functions well in the environment.

Specifically, the distance between the center of the movable mirror 23 and the center of the movable mirror 24 is greater than 1 mm. Because the size of the infrared light spot is a maximum of 5 mm, in order to avoid the overlapping effect of the entire aperture range light and incident light transmitted through the mirror, the center of the movable mirror 23 and the center of the movable mirror 24 The distance between them is adjusted to be greater than twice the maximum spot size.

Preferably, the movable mirror 23 and the movable mirror 24 are inclined at an angle of 45 ° with a horizontal plane. As shown in FIG. 2, after the infrared light passes through the wafer 28, it is incident on the movable mirror 23, is reflected and incident on the movable mirror 24, and is reflected again, and the infrared light is incident again It is received by the detector 22 on and through the wafer 28. Infrared light passes through the wafer 28 twice, increasing the amount of infrared light absorbed by the wafer 28, and increasing the amount of infrared light absorbed can improve the wafer 28 without changing the thickness of the wafer 28 Medium carbon concentration sensitivity.

Example two

FIG. 3 is a schematic structural diagram of an FTIR-based characterization device provided by Embodiment 2 of the present invention. The carbon concentration in a wafer is characterized by infrared light, including a V-shaped mirror 33, which reflects the infrared light onto the wafer 36. .

Specifically, the FTIR-based characterization device further includes a light source 30, an interferometer 31, a detector 32, and two mirrors. The two mirrors are a first mirror 34 and a second mirror 35, respectively. To change the direction of incidence of infrared light. The infrared light emitted by the light source 30 passes through the first reflecting mirror 34 and changes its direction, enters the interferometer 31, and then reflects through the second reflecting mirror 35 to the wafer 36; the detector 32 is used to detect penetration Infrared light after passing through the wafer 28.

Specifically, a material nickel is deposited on the surface of the V-shaped mirror 33. The material nickel has excellent corrosion resistance, high temperature resistance, and a high reflection coefficient, so that it can perform well in harsh environments such as humidity. .

Preferably, an included angle of the V-shaped mirror 33 is 90 °, and an included angle of the V-shaped mirror 33 and a horizontal plane is 45 °. As shown in FIG. 3, after the infrared light passes through the wafer 36, it is incident on the V-shaped mirror 33. After two reflections, the infrared light is incident on the wafer 36 again and passes through the wafer 36. The detector 32 receives. The infrared light passes through the wafer 36 twice, which increases the amount of infrared light absorbed by the wafer 36. Increasing the amount of infrared light absorbed can increase the sensitivity to the carbon concentration in the wafer while the thickness of the wafer remains unchanged.

Example three

FIG. 4 is a schematic structural diagram of an FTIR-based characterization device provided by Embodiment 3 of the present invention. Infrared light is used to characterize a carbon concentration in a wafer, and includes a fixed reflection mirror 43 and a fixed reflection mirror 44, the fixed reflection mirror 43 and the The fixed mirror 44 is inclined to the horizontal plane, and reflects the infrared light onto the wafer.

Specifically, the FTIR-based characterization device further includes a light source 40, an interferometer 41, a detector 42, and two reflecting mirrors. The two reflecting mirrors are a first reflecting mirror 45 and a second reflecting mirror 46, respectively. To change the direction of incidence of infrared light. The infrared light emitted by the light source 40 passes through the first reflector 45, changes its direction, enters the interferometer 41, and then reflects on the wafer 47 through the second reflector 46. The detector 42 is used to detect penetration. Infrared light after passing through the wafer 47.

Specifically, material nickel is deposited on the surfaces of the fixed mirror 43 and the fixed mirror 44. The material nickel has excellent corrosion resistance, high temperature resistance, and a high reflection coefficient, making it suitable for harsh environments such as humidity. Can also perform very well.

Specifically, the distance between the center of the fixed mirror 43 and the center of the fixed mirror 44 is greater than 1 mm. Because the size of the infrared light spot is a maximum of 5 mm, in order to avoid the overlapping effect of the entire aperture range light and the incident light transmitted through the fixed mirror, between the center of the fixed mirror 43 and the center of the fixed mirror 44 The distance is adjusted to be greater than twice the maximum spot size.

Preferably, the fixed mirror 43 and the fixed mirror 44 are inclined at an angle of 45 ° to a horizontal plane. As shown in FIG. 4, after the infrared light passes through the wafer 47, it is incident on the fixed mirror 43, is reflected and incident on the fixed mirror 44, and is reflected again, and the infrared light is incident again on the The wafer 47 is received by the detector 42 on and through the wafer 47. The infrared light passing through the wafer 47 twice increases the amount of infrared light absorbed by the wafer 47. Increasing the amount of infrared light absorbed can increase the sensitivity to the carbon concentration in the wafer while the thickness of the wafer remains unchanged. .

Each implementation in this specification is described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, it is described relatively simply. For the related part, please refer to the description of the method.

The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention. Any changes and modifications made by those skilled in the art according to the above disclosure shall fall within the protection scope of the claims.

Claims (12)

    A characterization device based on Fourier transform infrared spectroscopy (FTIR) includes two movable mirrors. The movable mirrors are inclined with a horizontal plane for reflecting infrared light onto a wafer.         The FTIR-based characterization device according to item 1 of the scope of the patent application, wherein the characterization device further includes a motor for driving the movable mirrors to move at the horizontal plane.         The FTIR-based characterization device according to item 1 of the patent application scope, wherein the characterization device further includes a light source, an interferometer, a detector, and two reflectors, and the light source emits infrared light and passes through the interferometer. The light is then reflected on the wafer by the mirrors; the detector is used to detect the infrared light after passing through the wafer.         The FTIR-based characterization device according to item 1 of the scope of patent application, wherein one surface of the movable mirrors is deposited with a material nickel.         According to the FTIR-based characterization device described in item 3 of the patent application scope, wherein the movable mirrors are inclined at an angle of 0 ° to 90 ° at the horizontal plane.         According to the FTIR-based characterization device described in item 5 of the scope of patent application, wherein the movable mirrors are inclined at an angle of 45 ° at the horizontal plane.         According to the FTIR-based characterization device described in item 6 of the patent application scope, wherein the distance between the centers of the movable mirrors is greater than 1 mm.         A characterization device based on Fourier transform infrared spectroscopy (FTIR) includes a V-shaped mirror for reflecting infrared light onto a wafer.         The FTIR-based characterization device according to item 8 of the scope of the patent application, wherein a material nickel is deposited on one surface of the V-shaped mirror.         The FTIR-based characterizing device according to item 9 of the scope of patent application, wherein the included angle of the V-shaped mirror is 90 °.         According to the FTIR-based characterization device described in item 10 of the scope of patent application, wherein the angle of the V-shaped mirror in a horizontal plane is 0 ° to 90 °.         The FTIR-based characterizing device according to item 11 of the scope of patent application, wherein the angle of the V-shaped mirror in the horizontal plane is 45 °.