JP2009270834A - Sample shape measuring method, holding device and shape measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple measuring method of the shape of a sample for rapidly changing the temperature of the sample to a desired temperature with favorable temperature distribution and rapidly and accurately determining the sample of the sample, a holding device and a shape determination device. <P>SOLUTION: The method measures the shape of a sample 90 using an interferometer 40, and includes the steps of: providing a housing unit 25 for housing a low vapor pressure fluid 253 in the inside of a casing 21 made of an airtight material; placing the sample 90 on a light path OP of a measuring light emitted form a light source of the interferometer 40 with a part thereof immersed in the low vapor pressure fluid 253; sealing the inside of the case 21 and reducing the pressure therein; acquiring interference data by emitting the measuring light from the light source to a part 91 of the sample 90 which is not immersed in the low vapor pressure fluid 253; and determining the shape of the sample 90 based on the interference data. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for measuring the shape of a sample, and more specifically to a measurement method for measuring the shape of a sample using an interferometer.

  Conventionally, a system using an interferometer has been used to precisely measure the shape of the sample and its changes. However, fluctuations caused by air in the optical path of the interferometer (air fluctuations) can reduce the measurement accuracy. It is the cause. Therefore, when high measurement accuracy is required, a measurement apparatus in which a sample and an interferometer are arranged in a vacuum chamber is used.

  However, in such a measuring apparatus, since the heat conduction speed of the sample atmosphere is extremely smaller than that of the air, it takes a long time to adjust the temperature, and a measurement error due to the heat distribution of the sample is likely to occur.

Therefore, Patent Document 1 discloses a measuring apparatus in which a work stocker is disposed adjacent to a vacuum chamber. According to this measuring apparatus, since the sample is set in the vacuum chamber after the temperature is adjusted in advance by the work stocker, the time spent for adjusting the temperature in the vacuum chamber can be shortened.
JP 7-318308 A

  By the way, extremely low expansion materials such as extremely low expansion glass ceramics disclosed in Japanese Patent Application Laid-Open No. 2005-89272 often require high-precision dimensional stability, and the thermal expansion characteristics within the material are often required. Uniformity may be a problem. Therefore, when measuring the distribution of thermal expansion characteristics of such materials nondestructively, the temperature conditions of the material (sample) are changed, the shape of the material under each temperature condition is measured with high accuracy, Based on the change in the shape of the material due to the change, the distribution of the expansion characteristics of the material can be measured.

  However, in the measurement apparatus disclosed in Patent Document 1 described above, when measurement is performed under a plurality of temperature conditions, it is necessary to transfer the sample between the vacuum chamber and the work stocker each time measurement is performed. Here, if the position where the sample is placed in each measurement is slightly different, the accuracy of the shape comparison is lowered. Further, in order to accurately adjust the installation position, a separate control device is required, which complicates the device.

  The present invention has been made in view of the above circumstances, and a simple measurement method, a holding device, and a shape measurement that can quickly and accurately measure the shape of a sample by quickly reaching the target temperature with a good temperature distribution. An object is to provide an apparatus.

  The inventors of the present invention have found that the shape can be measured quickly while suppressing fluctuation by performing measurement in a state where the sample is immersed in a low vapor pressure liquid under reduced pressure conditions, and the present invention has been completed. Specifically, the present invention provides the following.

(1) A measurement method for measuring the shape of a sample using an interferometer,
In the housing formed of an airtight material, an accommodating means for accommodating a low vapor pressure liquid is provided,
The sample is placed on the optical path of measurement light emitted from the light source of the interferometer, with a part of the sample immersed in the low vapor pressure liquid,
The inside of the housing is sealed and decompressed,
The measurement light is emitted from the light source to a portion of the sample that is not immersed in the low vapor pressure liquid to obtain interference data,
A measurement method comprising a step of measuring the shape of the sample based on the interference data.

  (2) The measurement method according to (1), further including a temperature adjustment step of changing the temperature of the sample through temperature adjustment of the low vapor pressure liquid.

(3) A part or all of the housing means is provided with a high heat transfer member having high thermal conductivity,
The measurement method according to (1) or (2), further including a step of bringing the low vapor pressure liquid into contact with the high heat transfer member.

(4) The casing is provided with an optical window that transmits the measurement light,
The measurement method further includes a step of arranging the light source outside the housing and causing the measurement light emitted from the light source to reach the sample through the optical window. Measuring method.

  (5) The measuring method according to any one of (1) to (4), wherein a change in the shape of the sample accompanying a change in temperature of the sample is measured.

  (6) The measurement method according to (5), wherein a distribution of thermal expansion characteristics of the sample is measured from a change in shape accompanying a temperature change of the sample.

(7) A holding device for holding a sample whose shape is measured using an interferometer,
A housing made of an airtight material and capable of being sealed inside;
Pressure reducing means for reducing the internal pressure of the housing;
A housing means provided inside the housing and housing a low vapor pressure liquid;
The sample is disposed on the optical path of measurement light emitted from the light source of the interferometer to a portion not immersed in the low vapor pressure liquid in a state where a part of the sample is immersed in the low vapor pressure liquid. Holding device.

  (8) The holding device according to (7), further comprising temperature adjusting means for changing the temperature of the sample through temperature adjustment of the low vapor pressure liquid.

(9) A part or all of the housing means is provided with a high heat transfer member having high thermal conductivity,
The holding device according to (7) or (8), wherein the high heat transfer member is brought into contact with the low vapor pressure liquid.

  (10) The holding device according to any one of (7) to (9), wherein the housing is provided with an optical window that transmits the measurement light.

  (11) The holding device according to any one of (7) to (10), an interferometer having a light source that emits measurement light to the optical path of the holding device, and the sample based on interference data obtained by the interferometer A shape measuring device comprising: a measuring means for measuring a shape.

  (12) The shape measuring apparatus according to (11), wherein the measuring unit measures a change in the shape of the sample accompanying a temperature change of the sample.

  (13) The shape measuring apparatus according to (12), wherein the measuring unit measures a distribution of thermal expansion characteristics of the sample from a shape change accompanying a temperature change of the sample.

According to the present invention, since the sample is immersed in the liquid in the storage means provided inside the housing, the liquid acts as a heat medium, and the sample can reach the target temperature quickly and with good temperature distribution. And it can measure simply and rapidly by emitting measurement light to the part which is not immersed in the liquid.
Moreover, since the low vapor pressure liquid is adopted as the liquid, the inside of the housing is sufficiently decompressed. Thereby, since fluctuation is suppressed, shape measurement can be performed accurately.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a shape measuring apparatus 10 according to an embodiment of the present invention. The shape measuring apparatus 10 includes a holding device 20, a base 30, an interferometer 40, and measurement means (not shown). Hereinafter, each component will be described in detail.

[Holding device]
The holding device 20 includes a housing 21 made of an airtight material. The housing 21 includes a main body 211 and a lid 213 that closes an opening of the main body 211. When the lid 213 is closed, the inside of the housing 21 is sealed, and when the lid 213 is opened, the inside of the housing 21 is released. The airtight material is not particularly limited as long as it is not porous and has excellent air permeability, and may contain various metals, resins, etc., but when the inside of the casing 21 is decompressed as described later. Has a strength sufficient to retain the shape.

  The shape measuring apparatus 10 further includes a decompression unit 23 as decompression means, and the decompression unit 23 reduces the internal pressure of the housing 21. Specifically, the decompression unit 23 has a vacuum pump 231, and the vacuum pump 231 is communicated with the inside of the housing 21 through a communication pipe 233. When the vacuum pump 231 is operated with the lid 213 closed, the gas inside the housing 21 is sucked into the vacuum pump 231 and the internal pressure of the housing 21 decreases (however, a low vapor pressure liquid 253 described later). Will not drop below the vapor pressure). The internal pressure of the housing 21 may be maintained by continuously operating the vacuum pump 231, but may be maintained by providing a closing valve in the middle of the communication pipe 233 and closing the closing valve. Thereby, it can suppress that a measurement precision falls by the fine vibration transmitted from the vacuum pump 231. FIG.

  The shape measuring apparatus 10 further includes a housing portion 25 as a housing means, and this housing portion 25 is provided inside the housing 21, specifically, on the bottom surface 212 of the housing 21. The accommodating portion 25 accommodates a low vapor pressure liquid 253, and a part of the sample 90 is immersed in the low vapor pressure liquid 253. Thereby, the low vapor pressure liquid 253 acts as a heat medium, and the sample 90 can reach the target temperature quickly and with a good temperature distribution. As the portion of the sample 90 that is immersed in the low vapor pressure liquid 253 becomes wider, the temperature adjustment of the sample 90 is accelerated. However, in this embodiment, the upper surface 91 is irradiated with the measurement light. Care should be taken not to immerse in H.253.

Here, the low vapor pressure liquid refers to a liquid having a vapor pressure lower than that of water in a broad sense. Depending on the refractive index when the liquid is vaporized, the length of the measurement optical path, etc., it is about 0.1 nm. The liquid having a vapor pressure at room temperature of preferably 1 × 10 ⁻³ Pa or less, more preferably 1 × 10 ⁻⁵ Pa or less, and most preferably 1 × 10 ⁻⁶ Pa or less is preferable in that fluctuation error can be suppressed below. It is. Note that the vapor pressure of the low vapor pressure liquid is preferably as low as possible in the present invention, and the lower limit is not particularly defined. Since the vapor pressure of such a low vapor pressure liquid 253 is low, the inside of the housing 21 is maintained in a substantially vacuum state under reduced pressure conditions. Thereby, not only fluctuation is suppressed, but also the heat of the sample 90 is radiated to the interferometer 40 to be described later, so that the measurement accuracy is improved. In addition, it is preferable that the low vapor pressure liquid has a low refractive index when gasified, a high thermal conductivity, a small specific heat, a stable and low reactivity, and is difficult to react with the measurement sample and the container. Specific examples of such liquids include silicon oils such as tetraphenyltetramethyltrisiloxane and pentaphenyltrimethyltrisiloxane, phenyl ether oils such as pentaphenyl ether, tetraphenyl ether and alkyldiphenyl ether, and perfluoropolyethers. Fluoro oil is mentioned, and perfluoropolyether is preferred from the viewpoint of providing the required properties with a good balance.

  The low vapor pressure liquid is preferably small in fluctuation due to the vaporized gas (that is, has a low refractive index at the time of gas) in terms of improving measurement accuracy, and has a specific heat in that the temperature of the sample 90 can be rapidly changed. It is preferable that the thermal conductivity is small.

  At the time of measurement, the sample 90 is disposed on the optical path OP of the measurement light in a state where a part of the sample 90 is immersed in the low vapor pressure liquid 253. In the present embodiment, the sample 90 is disposed below the optical window 216. Here, the measurement light is light emitted from the light source 41 of the interferometer 40 to the portion 91 of the sample 90 that is not immersed in the low vapor pressure liquid 253, as will be described later. Further, the sample 90 has a temperature sensor (not shown) attached to its side surface, and a temperature value detected by the temperature sensor is transmitted to a control device described later. In the present embodiment, temperature sensors are attached to a plurality of locations in order to measure the temperature distribution of the sample.

  It is preferable that a part or the whole of the housing portion 25 is provided with a highly heat conductive member having a high thermal conductivity. The high heat transfer member 251 in the present embodiment constitutes the entire housing part 25 (specifically, the side wall and the bottom part), and comes into contact with the low vapor pressure liquid 253 housed in the housing part 25. Further, since the high heat transfer member 251 is also in contact with the temperature adjusting unit 26 as temperature adjusting means, the heat energy from the temperature adjusting unit 26 is efficiently conducted to the entire low vapor pressure liquid 253. The high heat transfer member may be a conventionally known metal or the like, but is preferably formed of a stable material that is not easily affected by the low vapor pressure liquid 253.

  The temperature adjustment unit 26 changes the temperature of the sample 90 through temperature adjustment of the low vapor pressure liquid 253. The type of adjusting the temperature of the low vapor pressure liquid 253 is not particularly limited, but in this embodiment, the temperature adjustment unit 26 is provided on the bottom side of the storage unit 25 and is in direct contact with the low vapor pressure liquid 253. The thermal energy is directly exchanged with the low vapor pressure liquid 253 and is indirectly exchanged via the high heat transfer member 251. In addition, the output of the temperature control part 26 is controlled by the control apparatus mentioned later.

  The housing 21 of the present embodiment is provided with an optical window 216, and measurement light can pass through the optical window 216. Specifically, the optical window 216 is provided substantially at the center of the upper wall 214 and transmits the measurement light from the interferometer 40 disposed above the optical window 216 to reach the sample 90.

〔base〕
The base 30 varies the position and posture of the sample 90 with respect to the interferometer 40. In this embodiment, since the phase shift method is used as will be described later, the base 30 holds the sample 90 horizontally. The base 30 is driven and controlled by a control device described later.

[Interferometer]
FIG. 2 is a schematic configuration diagram of an interferometer 40 according to an embodiment. Here, a Fizeau interferometer will be described in order to use the phase shift method, but the present invention is not limited to this, and a Fourier transform method (a kind of spatial carrier method) may be used.

  The interferometer 40 includes a light source 41 (for example, a He—Ne laser). A light beam emitted from the light source 41 becomes divergent light by the diverging lens 42, passes through the beam splitter 43, and becomes a parallel light beam by the collimator lens 44. A part of this parallel light beam is reflected by the reference surface 45 a of the reference plate 45. The remainder of the parallel light beam is transmitted through the reference plate 45, reflected by the upper surface 91 of the sample 90, transmitted through the reference plate 45 again, and interferes with the light beam reflected by the reference surface 45a. The interfered light beam is again transmitted through the collimator lens 44, reflected by the beam splitter 43, and applied to the image sensor 48 through the image pickup lens 47. Then, an interference fringe image is acquired by the image sensor 48. Here, the light traveling toward the sample 90 is referred to as measurement light. Although the upper wall 214 and the optical window 216 are omitted in FIG. 2, the optical window 216 is actually disposed on the optical path OP of the measurement light, and the measurement light and its reflected light are transmitted through the optical window 216. .

(Measuring means)
The measuring means measures the shape of the sample 90 based on the interference data obtained by the interferometer 40. The theory of measuring the shape from the interference data is well known in the art and will not be described. The measurement means includes a control device (not shown). The control device adjusts the output of the temperature adjustment unit 26 to change the temperature of the sample 90, and starts measurement based on the detection value from the temperature sensor. And a drive control unit that controls the drive of the base.

  The temperature control unit basically adjusts the output of the temperature adjustment unit 26 so as to change the temperature of the sample 90 to a set value, thereby quickly adjusting the temperature of the sample 90 at the set temperature. The shape of the sample 90 at temperature can be measured. It is preferable that the temperature control unit further has a function of adjusting the output of the temperature adjustment unit 26 so that the temperature of the sample 90 changes to a set value at a desired speed. As a result, the measuring means can accurately measure a change in shape associated with a temperature change of the sample 90.

  At this time, the drive control unit drives and controls the base 30 to adjust the inclination of the sample 90, and the shape of the sample 90 can be measured using a Fourier transform method, a phase shift method, or the like.

  The measurement start unit stops the measurement until the detection value from the temperature sensor reaches the set temperature, and starts the measurement when the set temperature is reached. Thereby, the shape of the sample 90 under preset temperature can be measured correctly.

  Since the temperature of the sample 90 changes in order from the side closer to the temperature control unit 26 (the lower side in FIG. 1), the temperature of the sample 90 tends to be non-uniform while the elapsed time after the temperature change is short. Therefore, the measurement start unit in the present embodiment further has a function of calculating variations in detection values from a plurality of temperature sensors and starting measurement when the variations fall within an allowable range. Thereby, the shape of the sample 90 under the set temperature can be measured more accurately, and the accuracy of the distribution of thermal expansion characteristics can be significantly improved.

[Measuring method]
A shape measuring method using the above shape measuring apparatus 10 will be described below.

  First, the accommodating part 25 is provided in the inside of the housing | casing 21 formed with the airtight material. Then, the sample 90 is placed on the optical path OP of the measurement light in a state where a part of the sample 90 is immersed in the low vapor pressure liquid 253. Here, the supply of the low vapor pressure liquid to the storage unit 25 and the arrangement of the sample 90 are not particularly limited.

  Subsequently, after closing the lid 213 and sealing the inside of the housing 21, the vacuum pump 231 is operated to decompress the inside of the housing 21. Thereby, although the internal pressure of the housing 21 falls, it does not fall below the vapor pressure of the low vapor pressure liquid 253 mentioned later. As described above, since the vapor pressure of the low vapor pressure liquid 253 is low, the inside of the housing 21 is in a substantially vacuum state.

  Here, when the temperature control unit 26 is set to a predetermined output, the sample 90 can quickly reach the target temperature with good temperature distribution using the low vapor pressure liquid 253 as a heat medium. In the present embodiment, the high heat transfer member 251 provided on the side wall and the bottom of the storage unit 25 is brought into contact with the low vapor pressure liquid 253. As a result, the low vapor pressure liquid 253 not only directly transfers thermal energy to and from the temperature adjusting unit 26 but also indirectly transfers thermal energy via the high heat transfer member 251, so that the temperature leveling is further improved. Done quickly.

  When it is determined that substantially the entire temperature of the sample 90 has reached the set value based on the detection value of the temperature sensor, the measurement is started. That is, light is emitted from the light source 41 and measurement light is emitted to a portion 91 of the sample 90 that is not immersed in the low vapor pressure liquid. In the present embodiment, the interferometer 40 is disposed outside the housing, and the measurement light reaches the sample 90 through the optical window 216. The measurement light is reflected by the upper surface 91 of the sample 90, and the reflected light passes through the optical window 216 again and returns to the interferometer 40. During this time, since the inside of the housing 21 is in a substantially vacuum state, fluctuations are suppressed.

  The reflected light from the upper surface 91 interferes with the light beam reflected by the reference surface 45a. The interfered light beam is again transmitted through the collimator lens 44, reflected by the beam splitter 43, and applied to the image sensor 48 through the image pickup lens 47. Thereby, an interference fringe image is acquired by the image sensor 48. Then, the shape of the sample 90 is measured based on the acquired interference data.

  After the above measurement, in this embodiment, the output of the temperature adjustment unit 26 is adjusted, and the temperature of the sample 90 is changed to the next set temperature through the temperature adjustment of the low vapor pressure liquid 253. This temperature change is also quickly made because the low vapor pressure liquid 253 acts as a heat medium. After this temperature change is completed and the temperature of almost the entire sample reaches the set value, the shape of the sample 90 is measured again. Thereafter, if necessary, the temperature of the sample 90 is further changed to the next set temperature, and the shape is similarly measured. In this way, the change in the shape of the sample 90 accompanying the temperature change is measured. Further, the distribution of the thermal expansion characteristics of the sample 90 is measured from the change in shape accompanying the temperature change of the sample 90.

[Function and effect]
According to this embodiment, the following effects can be obtained.

Since the sample 90 is immersed in the liquid 253 in the housing portion 25 provided inside the housing 21, the liquid 253 acts as a heat medium, and the sample 90 sample can reach the target temperature quickly and with good temperature distribution. And it can measure simply and rapidly by emitting measurement light to the part 91 which is not immersed in the liquid 253. FIG.
In addition, since a low vapor pressure liquid is used as the liquid 253, the inside of the housing 21 is sufficiently decompressed. Thereby, since fluctuation is suppressed, shape measurement can be performed accurately.

  By changing the temperature of the sample 90 through the temperature adjustment of the low vapor pressure liquid 253, the change in the shape of the sample accompanying the temperature change can be measured quickly and accurately. In addition, the distribution of the thermal expansion characteristics of the sample 90 can be quickly and accurately measured from the change in the shape of the sample 90 accompanying the temperature change.

  Since the high heat transfer member 251 is provided in the housing portion 25, the temperature of the low vapor pressure liquid 253 changes efficiently via the high heat transfer member 251, so that the measurement can be performed more quickly and accurately.

  Since the measurement light can reach the sample 90 through the optical window 216, the interferometer 40 can be disposed outside the housing 21. As a result, the housing 21 can be miniaturized and the pressure reduction efficiency can be improved, so that the measurement can be performed more accurately.

  The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  For example, in the above embodiment, the interferometer 40 is arranged outside the housing 21 and the measurement light reaches the sample 90 via the optical window 216. However, the present invention is not limited to this, and the housing is provided with an optical window. Alternatively, an interferometer may be arranged inside the housing. In this case, a decrease in measurement accuracy due to air fluctuation outside the housing 21 can be suppressed.

  When a wavelength modulation phase shift interferometer is used as the interferometer, the reference surface of the interferometer is placed inside the housing 21, i.e., between the optical window 216 and the sample 90, so that the optical window 216 changes in temperature. Measurement errors and the influence of air fluctuation between the optical window 216 and the reference surface when the reference surface is arranged outside the housing 21 can be avoided, and a more accurate sample shape measurement can be performed.

It is a schematic block diagram of the shape measuring apparatus which concerns on one Embodiment of this invention. It is a schematic block diagram of the interferometer which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Shape measuring apparatus 20 Holding apparatus 21 Housing 211 Main body part 216 Optical window 23 Depressurization part (decompression means)
25 Accommodation part (accommodation means)
251 High heat conductivity member 253 Low vapor pressure liquid 26 Temperature control unit (temperature control means)
40 Interferometer 41 Light source 90 Sample 91 Upper surface

Claims (13)

A measurement method for measuring the shape of a sample using an interferometer,
In the housing formed of an airtight material, an accommodating means for accommodating a low vapor pressure liquid is provided,
The sample is placed on the optical path of measurement light emitted from the light source of the interferometer, with a part of the sample immersed in the low vapor pressure liquid,
The inside of the housing is sealed and decompressed,
The measurement light is emitted from the light source to a portion of the sample that is not immersed in the low vapor pressure liquid to obtain interference data,
A measurement method comprising a step of measuring the shape of the sample based on the interference data.   The measurement method according to claim 1, further comprising a temperature adjustment step of changing the temperature of the sample through temperature adjustment of the low vapor pressure liquid. A part or all of the accommodating means is provided with a high heat transfer member having high thermal conductivity,
The measurement method according to claim 1, further comprising a step of bringing the low vapor pressure liquid into contact with the high heat transfer member. The housing is provided with an optical window that transmits the measurement light,
4. The measurement method according to claim 1, further comprising a step of disposing the light source outside the housing and causing the measurement light emitted from the light source to reach the sample through the optical window. 5. .   The measurement method according to claim 1, wherein a change in the shape of the sample accompanying a change in temperature of the sample is measured.   The measurement method according to claim 5, wherein a distribution of thermal expansion characteristics of the sample is measured from a change in shape accompanying a temperature change of the sample. A holding device for holding a sample whose shape is measured using an interferometer,
A housing made of an airtight material and capable of being sealed inside;
Pressure reducing means for reducing the internal pressure of the housing;
A housing means provided inside the housing and housing a low vapor pressure liquid;
The sample is disposed on the optical path of the measurement light emitted from the light source of the interferometer to a portion not immersed in the low vapor pressure liquid in a state where a part of the sample is immersed in the low vapor pressure liquid. Holding device.   The holding device according to claim 7, further comprising temperature adjusting means for changing the temperature of the sample through temperature adjustment of the low vapor pressure liquid. A part or all of the accommodating means is provided with a high heat transfer member having high thermal conductivity,
The holding device according to claim 7 or 8, wherein the high heat transfer member is brought into contact with the low vapor pressure liquid.   The holding device according to claim 7, wherein the housing is provided with an optical window that transmits the measurement light.   11. A holding device according to claim 7, an interferometer having a light source that emits measurement light to an optical path of the holding device, and a measurement for measuring the shape of the sample based on interference data obtained by the interferometer A shape measuring apparatus comprising: means.   The shape measuring apparatus according to claim 11, wherein the measuring unit measures a change in the shape of the sample accompanying a change in temperature of the sample.   The shape measurement apparatus according to claim 12, wherein the measurement unit measures a distribution of thermal expansion characteristics of the sample from a shape change accompanying a temperature change of the sample.

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