阅读说明：本技术 薄型光学传感器 (Thin optical sensor ) 是由 尤里·赛文基 于 2020-02-04 设计创作，主要内容包括：本发明涉及一种具有一光发射器和一光传感器的用于测量距离的薄型光学传感器。更具体地,所述光学传感器包括一具有一系列遮盖的聚焦膜,以过滤漫反射光而不需要聚焦透镜。所述光学传感器可用于多种应用,包括使用两个传感器来测量物体的厚度或使用3个传感器来确定两个表面之间的角度。本发明还涉及校准传感器和使用3个或更多个光学传感器来调平半导体沉积设备中的喷头和卡盘的校准方法。(The invention relates to a thin optical sensor for measuring distances, having a light emitter and a light sensor. More specifically, the optical sensor includes a focusing membrane having a series of covers to filter diffusely reflected light without the need for a focusing lens. The optical sensor may be used in a variety of applications, including measuring the thickness of an object using two sensors or determining the angle between two surfaces using 3 sensors. The present invention also relates to a calibration sensor and a calibration method for leveling a showerhead and a chuck in a semiconductor deposition apparatus using 3 or more optical sensors.)

1. An optical sensor, comprising:

a light source emitting light and directed to a target point;

the light sensing unit is used for receiving reflected light from the target point;

the shading device is positioned between the target point and the light sensing unit so as to prevent a part of reflected light from reaching the light sensing unit; and

and the processing unit is used for processing the light received by the light sensing unit.

2. An optical sensor as claimed in claim 2, wherein the light shield comprises at least 2 or more covers.

3. An optical sensor as claimed in claim 3, wherein the light shield comprises a series of covers.

4. The optical sensor of claim 3, wherein the cover is positioned substantially perpendicular to the light sensing unit.

5. The optical sensor of claim 4, wherein the light blocking device is positioned adjacent to the light sensing unit.

6. The optical sensor of any one of claims 1-5, wherein the light source emits from a reference point; the processing unit is used for processing the reflected light received by the sensing unit to determine the distance between the reference point and the target point.

7. An optical sensor as claimed in any one of claims 1 to 9, further comprising a communications transmitter for transmitting information to a receiving device.

8. The optical sensor of claim 9, wherein the communication transmitter is wireless.

9. The optical sensor of claim 9, wherein the communication transmitter operates using bluetooth technology.

10. An optical sensor as claimed in any one of claims 1 to 9, further comprising a means for remotely activating the sensor.

11. An optical sensor as claimed in any one of claims 1 to 10, further comprising a precision accelerometer.

12. The optical sensor of any one of claims 1-11, further comprising a housing unit configured to maintain the relative positions of the light source, the light sensing unit, and the light blocking device.

13. The optical sensor of any one of claims 1-12, wherein the communication transmitter transmits information in real time.

14. An optical sensor as claimed in any one of claims 5 to 16, wherein the optical sensor is a charge coupled device.

15. A sensor for determining an angle between two surfaces, comprising:

at least three optical sensors, each optical sensor being located at a known position relative to a first surface; and

a processing unit;

each optical sensor includes:

a light source emitting light and directed to a target point on the second surface;

the light sensing unit is used for receiving reflected light from the target point;

the shading device is positioned between the target point and the light sensing unit so as to prevent a part of reflected light from reaching the light sensing unit;

wherein the processing unit processes output signals from each of the at least three light sensing units and calculates a distance between each sensor and each corresponding target point; and

the processing unit determines an angle between the first surface and the second surface using the measured distance.

16. A sensor according to claim 15, wherein the shading means comprises at least two or more covers.

17. A sensor according to claim 16, wherein the light shield comprises a series of covers.

18. A sensor according to any of claims 17, wherein the cover is positioned substantially perpendicular to the light sensing unit.

19. A sensor according to any of claims 15 to 18, wherein the light blocking means is located adjacent the light sensing unit.

20. A sensor according to any of claims 15 to 19, further comprising a communications transmitter for transmitting information to a receiving device.

21. The sensor of claim 20, wherein the communication transmitter is wireless.

22. The sensor of claim 20, wherein the communication transmitter operates using bluetooth technology.

23. A sensor according to any of claims 15 to 22, further comprising a means for remotely activating the sensor.

24. A sensor according to any of claims 15 to 23, further comprising a precision accelerometer.

25. A sensor according to any of claims 15 to 24, further comprising a housing unit configured to maintain the relative positions of the light source, the light sensing unit and the light blocking means for each optical sensor.

26. A sensor according to any one of claims 20 to 25, wherein the communications transmitter transmits information in real time.

27. The sensor of any one of claims 15-26, further comprising a ridged housing to maintain the relative position of each of the at least three optical sensors.

28. The sensor of claim 27 wherein the sensors are equally spaced around the base of the ridge housing.

29. A sensor as claimed in any one of claims 15 to 28, wherein the light sensor is a charge coupled device.

30. A method of determining the presence of an object, comprising:

emitting a light beam to a target point on the object;

blocking a portion of the reflected light from falling on an optical sensor;

receiving a portion of the reflected light as an input to the optical sensor; and

the input or lack of input on the optical sensor is suitably used to determine whether an object is present.

31. A method of measuring a distance between two points, comprising:

emitting a light beam to a target point;

blocking a portion of the reflected light from falling on an optical sensor;

receiving a portion of the reflected light as an input to the optical sensor; and

the input on the optical sensor is appropriately converted to calculate the distance of the target point from a reference point.

32. The method of claim 42, wherein a portion of the reflected light is blocked by a series of masks.

33. A method of evaluating an angle between two surfaces, comprising:

emitting at least three light beams from at least three corresponding reference points relative to the first surface;

directing the at least three light beams toward at least three corresponding target points on a second surface;

blocking at least a portion of reflected light from each of the three light beams reflected from the corresponding target point;

receiving a portion of each reflected light as an input to each of three respective light sensors;

converting the input on each photosensor to determine the distance between each reference point and its corresponding target point;

the distance between each reference point and its corresponding target point is used to evaluate the angle between the two surfaces.

34. The method of claim 33, wherein the angle between the two surfaces is evaluated by comparing the distances to determine if they are substantially equal to determine if the two surfaces are substantially parallel.

35. The method of claim 33, wherein the evaluation of the angle between the two surfaces comprises using the distance to determine the angle between the two surfaces.

36. The method of any one of claims 33-35, wherein the sensor is activated remotely.

37. The method of claim 36, wherein the sensor is activated by a magnetic switch.

38. Use of the sensor of claim 15 for calibrating a semiconductor deposition apparatus, wherein at least three determined distances are compared and the relative positions of the showerhead and the chuck are changed until the at least three distances are equal.

Technical Field

The following generally relates to an optical sensor and system for measuring a distance between two points. More particularly, it relates to a thin optical sensor and the use of multiple sensors to level two boards. Further, the following relates to calibrating a semiconductor deposition apparatus using a plurality of sensors.

Background

Optical sensors, in particular laser optical sensors, are present in the art. Such sensors work by emitting a beam of light from a laser, which passes through a focusing lens before hitting a target point. The light is diffusely reflected back through a second focusing lens to focus the reflected light onto a spot on the light sensor. The position of the light on the photosensor is then processed and used to determine the distance between the laser and the target point. This method of optically measuring distance is useful in many applications, but the sensor, and particularly the focusing lens, requires adequate space to function effectively.

Without a focusing lens, the dispersed light would fall on a larger area of the light sensor, which would not be able to obtain accurate position readings. Therefore, optical sensors, particularly laser optical sensors, have not been found to be useful in applications requiring a thin sensor in a small space.

For example, in semiconductor deposition equipment, very precise alignment between the chuck and the showerhead is required to achieve a uniform thin film across the entire wafer. Typically, a thin wafer capacitive gap sensor is used due to the limited spacing between the chuck and the showerhead. A series of three capacitive gap sensors is used to measure the gap between the chuck (on which the sensors are located during calibration) and the showerhead. The relative positions of the chuck and the showerhead are adjusted until all three sensors measure the same gap so that the chuck and showerhead are parallel to each other.

Capacitance is an electrical characteristic of two conductive plates, such as a sensor and a showerhead, separated by an insulator, in this case air or vacuum, between them. It is proportional to the area of the plates and the dielectric constant of the insulator separating them, and inversely proportional to the gap separating the plates, as shown by the equation below.

Capacitance (area) dielectric constant/gap

A limitation of capacitive gap sensors is that their accuracy depends on the electrical conductivity of the target material. It does not allow a large reference distance between the sensor and the target, limiting it to near field applications. Which may be sensitive to unwanted tilt, pitch and electrical noise as well as temperature, humidity and overall noise. Each sensor is very large, typically 12-60 mm in diameter, limiting its use in small applications. There remains a need for an accurate, reliable, thin sensor for measuring distances or leveling plates.

Disclosure of Invention

A thin optical sensor for measuring a distance having a light emitter and a light sensor is provided. More specifically, the optical sensor includes a focusing membrane having a series of covers to filter diffusely reflected light without the need for a focusing lens. The optical sensor may be used in a variety of applications, including measuring the thickness of an object using two sensors or determining the angle between two surfaces using three or more sensors. A calibration sensor and a calibration method using three or more sensors to level a showerhead and a chuck in a semiconductor deposition apparatus are also described below.

Drawings

The description is given by way of example only with reference to the accompanying drawings, in which:

FIG. 1 is a schematic illustration of an optical sensor and a light pattern emitted therefrom;

FIG. 2A is a schematic diagram of an optical path of an optical sensor at a maximum distance from a target point;

FIG. 2A is a schematic diagram of an optical path of an optical sensor with a target point at a minimum distance;

FIG. 3 shows a reflected light path and an optical sensor;

FIG. 4A is a side view of a first embodiment of a focusing film;

FIG. 4B is a side view of a second embodiment of a focusing film;

FIG. 5 is a schematic illustration of two optical sensors for determining the thickness of an object;

FIG. 6 is a schematic diagram of three optical sensors for determining whether two plates are level;

FIG. 7 is a schematic diagram illustrating the use of a calibration sensor in a semiconductor deposition apparatus;

FIG. 8 is a top view of the calibration sensor;

FIG. 9 is a partially exploded perspective view of the calibration sensor; and

FIG. 10 is a flow chart showing the interaction of components of the calibration sensor during use.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

Fig. 1 shows an optical sensor 2 having a light emitter 4, preferably a laser, and a light sensor 6, preferably a Charge Coupled Device (CCD). These elements are preferably contained in a housing (not shown). In use, the light emitter emits a light beam 8, directed towards a target point 10 on a surface 12. The emitted light beam 8 hits the target point 10 and is reflected/scattered from the surface 12 to the sensing unit 6 as reflected/scattered light 14. The reflected/scattered light 14 falls on the light sensor 6. The angle at which light is reflected/scattered from the surface 12 is determined by the distance of the target point from the light sensor 6. The reflected/scattered light 14 falls on the light sensor 6, and its position on the light sensor is used to determine the distance of the target point 10 from the light sensor 6. For example, if the target point 10 is far away, as shown in FIG. 2A (e.g., at a maximum specified range), the reflected light 14 will fall towards the end of the photosensor 6 that is farthest from the phototransmitter 4. Alternatively, as shown in FIG. 2B, if the target point 10 is at its closest position (at least within a minimum specified range), the reflected light 14 will fall on the other end of the light sensor 6 closest to the laser emitter 4. The range of distances that any particular sensor can measure is determined in part by the dimensions of the light sensor and the characteristics of the target surface and the light emitter. The received light 14 is processed and analyzed by a signal processor 16, which determines the distance to the target point 10 based on optical triangulation principles known to a person skilled in the art.

As shown in fig. 1 and 3, the reflected light 14 is diffusely reflected from the target point 10. Without first being filtered or focused in some way, the reflected light will fall on a large area of the light sensor 6 and the distance to the target point 10 cannot be accurately measured. To address this problem, a focusing film 18 is positioned between the reflective surface 12 and the light sensor 6. The focusing membrane 18 is preferably located near the receiving surface 20 of the light sensor 6. In an alternative embodiment, the focusing film is spaced apart from the light sensor 6, but arranged so as not to interfere with the light emitters. As shown in fig. 4A, the focusing film 18 includes a plurality of covers (blids) 22 extending outwardly from a transparent base surface 24, with a plurality of windows 26 formed between each set of adjacent covers. Preferably, the cover extends substantially perpendicular to the surface of the light sensor 6 to improve accuracy and reduce light loss. In a preferred embodiment a transparent top surface 28 is included to maintain the covering position. Alternatively, as shown in fig. 4B, in the focusing film 18B, there is no top surface, and the cover 22 protrudes outward from the base 24. Preferably, the covers 22 are evenly spaced, however, the spacing between the covers may be customized depending on the application.

Referring to fig. 3, when the reflected light 14 is diffusely reflected off the target point 10, it passes through the focusing film 18 before falling on the light sensor 6. The focusing film 18 serves to block some of the diffusely reflected light 14 from falling on the light sensor 6, resulting in a smaller area of the light sensor 6 being activated and therefore more accurate measurements. In many applications, without a focusing membrane or lens, the sensor would be equally illuminated along its length and no measurement could be determined. For purposes of illustration, the diffusely reflected light 14 is shown in FIG. 3 as a series of dashed lines 14a-14i, each dashed line representing a portion of the diffuse light. The angles at which the light portions 14d, 14e, 14f, and 14g located inside the diffusion patterns fall on the focusing film 18 allow light to pass through the windows 26a, 26b, 26c, and 26d, respectively. These light portions fall on the light sensor 6, the position of which is used to determine the distance of the target point 6. However, the light portions outside the diffusing pattern, including 14a, 14b, 14c, 14h, and 14i, pass through the angle on the focusing film 18 so that the light falls on the masks 22a, 22b, 22c, 22d, and 22e, respectively. This prevents these portions of the reflected light 14 from contacting the light sensor 6. Since only a portion of the diffusely reflected light 14 passes through the focusing film 18, the area of the photosensor activated by light is reduced. The overall effect of the focusing film is that the reflected light 14 is filtered, producing a small area of light on the light sensor, without the need for a focusing lens.

Separately, the optical sensor of the present invention can be used to measure distance or the presence of an object. By adjusting various characteristics, such as the robustness of the housing, the size of the optical sensor, the spacing and size of the cover in the focusing film, or the characteristics of the light emitters, the optical sensor can be adapted for a variety of applications and environments, from small spaces to outdoor or industrial uses. Common applications include, but are not limited to, quality control, error proofing, and positioning applications.

A lensless design with a height of at least as little as 8mm is particularly advantageous in small space applications. In addition, the optical sensor is robust and can be used under a variety of conditions, including temperatures of 20 ℃ to 65 ℃, various humidities and pressures, including in vacuum.

Optical sensors may also be used in pairs. As shown in fig. 5, sensors 27 and 29 may be placed on opposite sides of object 30 to determine the distance from each sensor 32 and 34 to object 30. This information can then be used to determine the thickness t of the object of interest 30.

Three optical sensors may be used in combination to determine whether two plates are level/parallel. As shown in fig. 6, three optical sensors 34, 36 and 38 are arranged on a first plate 40 and positioned such that they each emit light onto different target points 42, 44 and 46, respectively, on a second plate 48. The first optical sensor determines the distance d1 between it and the first target point 42, the second optical sensor determines the distance d2 between it and the second target point 44, and the third optical sensor determines the distance between it and the third target point 46. With d1, d2, and d3 all equal, the panels are leveled and aligned parallel to each other. Preferably, all three sensors are fixed in a common base 50 to facilitate use and maintain their relative positions. With three known distances, the angle of one plate relative to the other can also be calculated. Thus, this type of sensor can be used to calibrate or position the two plates at any relative angle. While at least 3 sensors are required to determine the angle between the two plates, it will be appreciated that more sensors may be used.

In a preferred embodiment, the sensor 60 comprises a communication transmitter, preferably wireless or Bluetooth, to transmit the measurements in real time. In another embodiment, a precision accelerometer is included in one or more sensors to measure the inclination of the sensor relative to the earth. The sensor may also be configured for remote activation.

This design is particularly useful in semiconductor deposition equipment calibration procedures. Fig. 7 shows a simplified semiconductor deposition apparatus 52 having a showerhead 54 and a chuck 56 in a lower housing 58. The chamber surrounding the chuck and showerhead, as well as other components found in this type of apparatus, are omitted for simplicity. In order to produce a wafer product having a uniform thickness, it is important that the showerhead 54 and chuck 56 be leveled. Therefore, the semiconductor deposition apparatus is calibrated before the production of the product. A calibration sensor 60 comprising at least 3 optical sensors is placed on the chuck and activated to determine at least 3 distances between the chuck and the showerhead. The chuck and/or showerhead is then adjusted until all three measured distances are equal. There is no time limit to aligning the chuck with the showerhead due to the ability to remotely activate the calibration sensor.

Fig. 8 shows a preferred design of a wafer-like calibration sensor 62, which includes three optical sensors 64, 66 and 68 arranged and fixed on a base 70. While a variety of materials can be used to make the base, potential base materials for use in preferred embodiments as semiconductors include, but are not limited to, Meldin (a polyimide plastic produced by Saint Goban), Celazole (a brand of polybenzimidazole plastic), Torlon (a brand of polyamide-imide), PEEK (polyetheretherketone plastic), Vespel (a polyamide plastic produced by DuPont), anodized aluminum and ceramic, fused silica, silicon or sapphire. The base is preferably rigid to prevent relative movement between the sensors. Since the distance is usually measured from the sensor position to the target point, the stiffness of the base ensures that the distance from the base to the light emitter remains constant. The base is preferably designed to have a large change in base characteristics (e.g., expansion or contraction) under different temperature or pressure conditions. Each optical sensor has a light emitter 72, 74 and 76 located near a light sensor 78, 80 and 82, respectively. As can be seen in fig. 9, which shows an exploded view of the optical sensor 66, the optical sensor 80 has a focusing membrane 84 affixed to its top. This is consistent for each sensor. A cap 86 is provided to protect the working components of the calibration sensor 62. A first set of slots 88 is provided to allow each light emitter 72, 74, and 76 to emit light, and a second set of slots 90 is provided in the top cover 86 to expose the light sensors 78, 80, and 82. The cap may be integrally formed or composed of multiple covers, each covering protecting a particular aspect of the calibration sensor. The cap may be removably secured to the base in any manner known to those skilled in the art. In the preferred embodiment shown in the figures, screws are used.

In the preferred embodiment of this figure, the calibration sensors are circular, with the optical sensors 64, 66 and 68 located near the base edge and equally spaced around the circumference. By spacing the sensors as large as the base allows, the distance between the three measured target points is maximal. This results in more accurate leveling than if the three points were closer together.

The center of the base can be used to house other working components, such as a transmitter, preferably wireless or bluetooth, to transmit the measurement to an external transceiver. With this design, the measurements can be used as input to calibration software that can automatically adjust the position of the chuck and/or showerhead in response to real-time measurements. In addition, the center of the base may be used to house a power supply unit 92 to power the three optical sensors. The power supply unit is preferably battery-based to allow for a completely wireless calibration of the sensor, but other power supply units may be known to the skilled person. Since the preferred embodiment includes the ability to wirelessly activate the sensor, one advantage of the design is that the sensor can be used remotely without releasing the vacuum in the semiconductor housing.

The overall interaction of the components of the calibration system is shown in the flow chart of fig. 10. The calibration sensor is first activated by the magnetic switch 100. The voltage from the battery is regulated by the switching regulator 102. The microcontroller unit (MCU) is then powered to start the software algorithm 104. The data from the CCD light sensors 106 is processed and the final calculated distance value from each light sensor is sent to a PC (personal computer) 108 via the MCU which sends a radio signal 110 on a radio channel received by the PC. One advantage of a magnetic switch is that the robot can move the sensor next to the magnet to activate the sensor. Thus, no human intervention is required.

In use, the calibration system is activated using a magnetic switch, with control options built into the corresponding software. The calibration sensor is placed in a closed semiconductor deposition chamber without manual contact during calibration. The light emitter activates and transmits the three distance measurements in real time. The appropriate software will compare the distances and determine the optimal adjustment to be made to the position of the cartridge and/or showerhead.

Although a wide range of powers is known to be acceptable and known to those skilled in the art, preferred embodiments include laser emitters emitting a maximum power of 0.67mW at 100mm, which is considered safe for the unprotected human eye. Other light sources are known to those skilled in the art, including but not limited to LEDs or incandescent light sources. The shape or wavelength of the light beam may vary from ultraviolet to infrared. However, a preferred embodiment of the calibration sensor also comprises a light emitter having an operating wavelength of 850 nm. Linear CCD sensors with pixel sizes <10 μm are preferred, although other light sensors may be useful and known. The smaller the pixel size, the more accurate the measurement, and in a preferred embodiment a CCD photosensor with a pixel size of 8 μm is used. With this preferred configuration, the target point location is 120mm + -5 mm from the sensor center, with a measurement range of 15mm + -5 mm.

The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.