JP5927652B2 - Optical monitor and vacuum deposition apparatus using the same - Google Patents

Description

  The present invention relates to an optical monitor for measuring a film thickness and a vacuum deposition apparatus using the same.

  Patent Document 1 discloses an example of a vacuum vapor deposition apparatus equipped with an optical monitor. The vacuum vapor deposition apparatus of the same document includes a monitor unit (21), a substrate dome (22), and a monitor glass (41). The evaporation material from the evaporation source is deposited on the deposition region on the lower surface of the monitor glass through the opening window (42a) of the monitor window (42) provided at the center of the substrate dome. The monitor unit includes a light projecting unit (43), a mirror (44), and a light receiving unit (47), and light from the light projecting unit is reflected by the mirror (44a) and incident on the monitor glass, and reflected light from the monitor glass. Is reflected by the mirror (44b) and enters the light receiving section. The film thickness of the deposited material on the monitor glass is measured based on the intensity of the reflected light at each wavelength by a calculation means (not shown).

  In the optical monitor as described above, a chopper plate may be provided for reducing the amount of deposition on the monitor glass. FIG. 8A shows a conventional optical monitor 105 provided with a chopper plate. The optical monitor 105 includes a monitor glass 10, a mask 15, a light projecting unit 21, a light receiving unit 22, and a chopper plate 130. As shown in FIG. 8B, slits 133 are provided radially on the chopper plate 130 and rotated about the rotation axis X. The slit 133 is disposed so as to pass through the front surface of the deposition region 11 of the monitor glass 10. The light projecting unit 21 enters measurement light into the measurement region 12 on the back surface of the deposition region 11 of the monitor glass 10, and the light receiving unit 22 receives the reflected light R 1 from the measurement region 12. Then, in the calculation means (not shown), the film thickness of the deposited material on the monitor glass is measured based on the intensity of the reflected light received by the light receiving unit 22.

JP 2007-270332 A

However, the optical monitor as shown in FIGS. 8A and 8B has the following problems.
First, as shown in FIG. 8A, the light emitted from the light projecting unit 21 is reflected not only on the monitor glass 10 but also on the chopper plate 130, and the reflected light R <b> 1 ′ enters the light receiving unit 22. It becomes a problem. That is, the light receiving unit 22 receives not only the reflected light R1 directly related to the reflectance in the measurement region 12, but also the light R1 ′ not related to the reflectance, so that the film thickness measurement accuracy is lowered. there were. Here, for example, if antireflection processing such as roughening is performed on the back surface (upper surface in the drawing) of the chopper plate 130, reflection at the chopper plate 130 can be prevented at the beginning of processing. However, in the subsequent vapor deposition process, the evaporation material goes around to the back side of the chopper plate 130, and as it is deposited, the processing surface becomes flat and the effect of the antireflection processing is diminished. Thus, the antireflection processing on the back surface of the chopper plate 130 is not an effective measure. For this reason, a configuration is required that can reliably prevent reflection on the back surface of the chopper plate even when the vapor deposition process is continuously performed.

  Secondly, in the optical monitor, the evaporated material needs to be uniformly deposited in the deposition region 11 of the monitor glass 10. However, in the chopper plate 130 shown in FIG. 8B, since the width of the slit 133 is constant in the radial direction, in the deposition region 11, the shielding rate is larger on the peripheral side than on the center side of the chopper plate 130 ( That is, the open rate becomes small). Therefore, as shown in FIG. 8C, the film thickness of the peripheral side portion 11b is smaller than the central side portion 11a of the chopper plate 130 in the deposition region 11, and a substantially concentric film spot is generated. And, due to the film spots, there is a problem that the measurement accuracy and the reproducibility thereof are lowered.

  Therefore, an object of the present invention is to improve the film thickness measurement accuracy by reliably preventing the reflection of measurement light from the back surface of the chopper plate in an optical monitor device using a chopper plate. Moreover, this invention makes it a subject to prevent the film spot in the deposition area | region of monitor glass, and to improve a measurement precision and its reproducibility.

  A first aspect of the present invention is an optical monitor for measuring a film thickness that is disposed to face an evaporation source, and includes a monitor glass and a slit installed so that vapor deposition material from the evaporation source is deposited in a predetermined region. The chopper plate that shields and exposes the predetermined area from the evaporation source, and makes the light incident on the measurement area located on the back surface of the predetermined area of the monitor glass and receives the reflected light, and based on the characteristics of the reflected light A measurement unit for calculating the film thickness is provided. The chopper plate has a tapered portion that is inclined with respect to the monitor glass at least in a portion corresponding to the predetermined region.

  For example, the chopper plate is configured to be rotatable with respect to the rotation axis, the slits are formed radially with respect to the rotation axis, and the separation distance between the taper portion and the monitor glass is increased toward the outer edge side of the chopper plate. The

Further, the taper portion is provided at the outer edge portion of the chopper plate , the chopper plate is configured to be able to reciprocate in parallel with the monitor glass, and a plurality of slits are arranged in the reciprocating direction, and the taper portion and the monitor glass are The separation distance may be increased or decreased in a direction perpendicular to the reciprocating direction of the chopper plate .

  Here, the opening width of the slit is preferably formed so as to increase from the rotating shaft side toward the outer edge side.

  Further, the chopper plate is configured to be rotatable with respect to the rotation axis, the slits are formed radially with respect to the rotation axis, and the separation distance between the taper portion and the monitor glass is reduced toward the outer edge side of the chopper plate. You may make it do.

  The second aspect of the present invention is a vacuum deposition apparatus including an evaporation source, the above-described optical monitor, a substrate holder that holds a processing substrate, and a vacuum chamber that encloses the evaporation source, the optical monitor device, and the substrate holder.

  Here, the vacuum chamber and the substrate holder are substantially cylindrical, the processing substrate is held on the inner surface of the substrate holder, the evaporation source and the optical monitor are arranged on the inner surface side of the substrate holder, and the substrate holder is centered on the cylindrical axis. Configured to be rotated.

It is a front view which shows the vacuum evaporation system by the Example of this invention. It is the arrow line view which cut | disconnected the vacuum evaporation system of FIG. 1A by AA '. It is the arrow line view which cut the vacuum evaporation system of Drawing 1A with BB '. It is a schematic front view of the optical monitor by the Example of this invention. It is a schematic plan view of the chopper board by the Example of this invention. It is a figure explaining the optical monitor by the Example of this invention. It is a bird's-eye view of the chopper board by the Example of this invention. It is a figure explaining the chopper board by the 1st modification of this invention. It is a figure explaining the chopper board by the 2nd modification of this invention. It is a figure explaining the chopper board by the 3rd modification of this invention. It is a figure explaining the chopper board by the 4th modification of this invention. It is a figure explaining the chopper board by the 4th modification of this invention. It is a figure which shows the conventional optical monitor. It is a figure which shows the chopper board in the conventional optical monitor. It is a figure explaining the conventional optical monitor.

Example.
FIG. 1A shows a front view of a vacuum deposition apparatus 1 according to an embodiment of the present invention, and FIGS. 1B and 1C show arrow views of the vacuum deposition apparatus 1 as viewed from AA ′ and BB ′, respectively. FIG. 1A omits the vacuum chamber front door. The vacuum deposition apparatus 1 includes a vacuum chamber 2, an evaporation source 3, a substrate holder 4, and an optical monitor 5. The vacuum chamber 2 in the present embodiment is substantially cylindrical, and the evaporation source 3 and the optical monitor 5 are arranged to face each other at a position on the diameter of the vacuum chamber 2 in the front view.

  In this embodiment, the evaporation source 3 includes two evaporation sources 3a and 3b, and after the vacuum chamber 2 is evacuated, two kinds of vapor deposition materials can be evaporated at different times or simultaneously. In this embodiment, the evaporation source 3 is composed of two evaporation sources, but the number of evaporation sources may be 1 or 3 or more. The substrate holder 4 is also cylindrical and is disposed along the inner surface of the vacuum chamber 2, and a substrate to be processed is held on the inner surface. In order to perform uniform vapor deposition from the evaporation source 3 to the substrate, the substrate holder 4 is rotated around a cylindrical axis. Although the substrate holder 4 in this embodiment is cylindrical, it may be polygonal as long as the substrate is held on the inner surface and can be rotated in the vacuum chamber 2. The optical monitor 5 will be described later.

  In the step of forming the optical film on the substrate, first, the evaporation source 3 is filled with the vapor deposition material, the substrate to be processed (not shown) is placed on the substrate holder 4, and the vacuum chamber 2 is evacuated. In the vacuum state, the substrate holder 4 is rotated and evaporation of the vapor deposition material is started from the vapor deposition source 3. As the vapor deposition process proceeds, the vapor deposition material is deposited on the substrate and a monitor glass described below. The optical monitor 5 measures the film thickness deposited on the monitor glass, and calculates the thickness of the film formed on the substrate from the measured film thickness, the chopper shielding rate, and the like. The vapor deposition process is stopped when the film thickness measured by the optical monitor 5 reaches a predetermined value. The operations of the vacuum chamber 2, the evaporation source 3, the substrate holder 4, and the optical monitor 5 may be comprehensively controlled by a control unit (not shown).

  FIG. 2A shows a front view of the optical monitor 5 of the present embodiment. The optical monitor 5 includes a monitor glass 10, a mask 15, a measuring unit 20, and a chopper plate 30. FIG. 2B shows a plan view of the chopper plate 30, and FIG. 2C shows the positional relationship among the monitor glass 10, the mask 15, and the chopper plate 30.

  Referring to FIGS. 2A-2C, the monitor glass 10 is disk-shaped or annular and is rotated about the rotation axis Y. The monitor glass 10 is shielded from the evaporation source 3 by a mask 15 except for the deposition region 11. In other words, the deposition region 11 exposed to the evaporation source 3 is defined by the opening of the mask 15, and the slit 33 of the chopper plate 30 passes through the entire surface. The back surface of the deposition region 11 becomes the measurement region 12, and both regions can be changed on the monitor glass 10 for each deposition process by the rotation operation about the rotation axis Y.

  The measurement unit 20 includes a light projecting unit 21, a light receiving unit 22, and a calculation unit 23. The light projecting unit 21 emits measurement light toward the measurement region 12, and the light receiving unit 22 receives the reflected light R1. The calculation unit 23 measures the film thickness of the vapor deposition material deposited in the deposition region 11 based on the characteristic of the reflected light R1 received by the light receiving unit 22, that is, the intensity at each wavelength.

  The chopper plate 30 has a disk shape as shown in FIG. 3 and is rotated with respect to the rotation axis X by a drive source (not shown). The chopper plate 30 includes a center portion 31 and a tapered portion 32 formed concentrically, and slits 33 are radially formed in the tapered portion 32. That is, the slit 33 passes through the front surface of the deposition region 11 by rotating the chopper plate 30. In the drawing, the slit 33 is formed only in the tapered portion 32, but the slit 33 may extend from the tapered portion 32 to the center portion 31.

  Here, as shown in FIG. 2A, the tapered portion 32 is formed such that the separation distance between the chopper plate 30 and the monitor glass 10 increases toward the peripheral edge side of the chopper plate 30. The inclination angle of the tapered portion 32 (the angle formed by the tapered portion 32 and the monitor glass 10) may be about 3 to 45 degrees, more preferably about 5 to 15 degrees. In the embodiment, the angle formed by the tapered portion 32 and the monitor glass 10 is set to 9 degrees. However, the angle between the center portion 31 and the monitor glass 10 is arbitrary. Here, the measurement light that has passed through the monitor glass 10 from the light projecting portion 21 and entered the tapered portion 32 forms reflected light R <b> 2 when reflected by the tapered portion 32. As shown in FIG. 2A, the portion where the measurement light is incident is tapered, so that the reflected light R <b> 2 proceeds in the direction of the mask 15, not the deposition region 11, and is not incident on the light receiving unit 22. Therefore, in the film thickness measurement of the measurement unit 20, the film thickness can be measured based only on the reflected light R1, and the film thickness measurement accuracy can be improved.

  Each of the slits 33 is formed in a substantially sector shape so that the opening width thereof increases from the rotation axis X side toward the outer edge portion side. Thereby, the shielding rate by the chopper plate 30 in the deposition region 11 (that is, the aperture ratio by the slit 33) becomes uniform, and the film thickness of the deposited material deposited in the deposition region 11 becomes uniform. Therefore, the occurrence of film spots in the deposition region, which has been a problem with the conventional configuration (FIGS. 8A to 8C), is prevented, and the monitoring accuracy and reproducibility thereof are improved. The opening width of the slit 33 and its spreading angle (change in opening width with respect to the longitudinal direction), length, number, etc. are selected according to a desired shielding rate (opening ratio).

Modified example.
In the said Example, although the taper part of the chopper board showed the structure inclined to the evaporation source side, the structure of a chopper board is not restricted to this. Specifically, the chopper plate may have a tapered portion that is inclined with respect to the monitor glass 10 at least in a portion that shields the deposition region 11. Below, the modification of a chopper board is shown with reference to FIGS. 4-6 and FIG. 7A and 7B.

Modification 1
FIG. 4 shows an optical monitor 5 including the chopper plate 40 of the first modification. The chopper plate 40 includes a center part 41, a tapered part 42, and an edge part 44 formed concentrically, and is rotated with respect to the rotation axis X. The slits 43 are formed radially with respect to the rotation axis X from the center portion 41 through the tapered portion 42 to the edge portion 44. Here, when the measurement light that has passed through the monitor glass 10 from the light projecting unit 21 and is incident on the tapered portion 42 is reflected by the tapered portion 42, it is reflected toward the mask 15 in the same manner as in the above embodiment. The reflected light R2 is formed.

  Also in this modification, the reflected light R2 from the chopper plate 40 is not incident on the light receiving unit 22, and in the film thickness measurement of the measuring unit 20, the film thickness can be measured based only on the reflected light R1, The film thickness measurement accuracy can be improved. Further, in this modification, the outer edge portion of the chopper plate 40 (edge portion 44) is disposed at a position closer to the mask 15 than the outer edge portion of the chopper plate 30 (taper portion 32) in the embodiment. 15 and the outer edge of the chopper plate 40 can be prevented from entering the deposition region 11. Thereby, further improvement in monitor accuracy can be expected. However, it is necessary to adjust the spread angle of the slit 43 according to the steps between the center portion 41, the tapered portion 42, and the edge portion 44.

Modification 2
FIG. 5 shows an optical monitor 5 including a chopper plate 50 of a second modification. The chopper plate 50 includes a center portion 51 and a tapered portion 52 formed concentrically, and is rotated with respect to the rotation axis X. The slits 53 are formed in the tapered portion 52 radially with respect to the chopper rotation axis X. In the present modification, the tapered portion 52 is formed so that the separation distance between the chopper plate 50 and the monitor glass 10 decreases toward the peripheral edge side of the chopper plate 50. Here, the measurement light that has passed through the monitor glass 10 from the light projecting portion 21 and entered the tapered portion 52 forms reflected light R <b> 3 that is reflected toward the mask 15 when reflected by the tapered portion 52.

  Also in this modification, the reflected light R3 from the chopper plate 50 is not incident on the light receiving unit 22, and in the film thickness measurement of the measurement unit 20, the film thickness can be measured based only on the reflected light R1, The film thickness measurement accuracy can be improved. In the present modification, the outer edge of the tapered portion 52 is formed at a position closer to the mask 15 than in the first modification, so that the vapor deposition material enters the deposition region 11 from the gap between the mask 15 and the outer edge of the chopper plate. The state of entering can be further suppressed as compared with the first modification. Thereby, further improvement in monitor accuracy can be expected. However, also here, it is necessary to adjust the spread angle of the slit 53 according to the inclination of the tapered portion 52.

Modification 3
In FIG. 6, the top view of the chopper board 60 of the 3rd modification is shown. The chopper plate 60 includes a plurality of crests 65a (one-dot broken line) and troughs 65b (broken line) extending radially, and is rotated about the rotation axis X. The slit 63 is formed in the valley 65b. In the present modification, a region between the peak portion 65a and the valley portion 65b is a tapered portion. Here, the measurement light that has passed through the monitor glass 10 from the light projecting portion 21 and entered the tapered portion (between 65 a and 65 b) is reflected toward the mask 15 and does not reach the light receiving portion 22. Therefore, the same effect as the above embodiment can be obtained.

  In this modification, the configuration in which the slit 63 is formed in the valley portion 65b is shown, but the configuration in which the slit is formed in the peak portion 65a may be adopted. However, in consideration of the possibility that the vapor deposition material is deposited on the valley portion 65b as a result of cumulatively performing the vapor deposition process (the possibility that the light reflected by the deposit reaches the light receiving unit 22), It is preferable to provide the slit 63 in the valley 65b.

Modification 4
In the said Example and modification, the structure by which a disk-shaped chopper board is rotated was shown, However, In this modification, the structure by which a chopper board is reciprocated is shown.
7A and 7B show a front view of the optical monitor 5 including the chopper plate 70 of the fourth modification and a plan view of the chopper plate 70, respectively. The chopper plate 70 is composed of a base portion 71 and a tapered portion 72 that bisect a rectangular plate, and the tapered portion 72 has slits 73 each formed along an inclined direction. The separation distance between the tapered portion 72 and the monitor glass 10 increases toward the distal end side of the tapered portion 72. The chopper plate 70 is reciprocated in parallel with the monitor glass 10 in the direction in which the slits 73 are arranged (the direction of the arrows).

  Also in this modification, the reflected light R2 from the chopper plate 70 is not incident on the light receiving unit 22, and in the film thickness measurement of the measuring unit 20, the film thickness can be measured based only on the reflected light R1, The film thickness measurement accuracy can be improved. Further, the configuration of this modification can also be applied to the configuration of Modification 1-3. That is, a rectangular chopper plate may be applied to the first modification, and a part of the chopper plate (part parallel to the slit arrangement direction and corresponding to the deposition region) may be inclined, or may be applied to the second modification. The taper portion may be inclined to the monitor glass side with respect to the base portion (the separation distance between the taper portion and the monitor glass decreases toward the tip end side of the taper portion). It is good also as a structure which forms the peak part and trough part extended in the direction perpendicular | vertical to a moving direction, and forms a slit in a trough part (or peak part).

  As described above, according to the above-described embodiments and modifications, in the optical monitor device using the chopper plate, it is possible to improve the film thickness measurement accuracy by eliminating the influence of the measurement light reflected from the back surface of the chopper plate. In addition, it is possible to improve the monitor accuracy and reproducibility by preventing film spots in the deposition area of the monitor glass.

1. 1. Vacuum deposition apparatus 2. Vacuum chamber Evaporation source 4. 4. substrate holder Optical monitor 10. Monitor glass 11. Deposition region 12. Measurement area 15. Mask 20. Measurement unit 21. Projecting unit 22. Light receiving unit 23. Calculation unit 30. Chopper board 31. Center part 32. Taper portion 33. Slit 40. Chopper board 41. Center part 42. Taper portion 43. Slit 44. Edge part 50. Chopper board 51. Center part 52. Taper portion 53. Slit 60. Chopper plate 63. Slit 65a. Yamabe 65b. Tanibe 70. Chopper board 71. Base part 72. Taper portion 73. slit

Claims (7)

An optical monitor for measuring a film thickness disposed opposite to an evaporation source,
A monitor glass installed so that the vapor deposition material from the evaporation source is deposited in a predetermined area;
A chopper plate that has a slit, shields and exposes the predetermined area from the evaporation source, and makes light incident on a measurement area located on the back surface of the predetermined area of the monitor glass and receives reflected light; It has a measuring unit that calculates the film thickness based on the characteristics of the reflected light,
An optical monitor in which the chopper plate has a tapered portion inclined with respect to the monitor glass at least in a portion corresponding to the predetermined region.   The optical monitor according to claim 1, wherein the chopper plate is configured to be rotatable with respect to a rotation axis, the slits are formed radially with respect to the rotation axis, and a separation distance between the tapered portion and the monitor glass is the chopper. An optical monitor formed to increase toward the outer edge side of the plate.   The optical monitor according to claim 1, wherein the chopper plate is configured to be rotatable with respect to a rotation axis, the slits are formed radially with respect to the rotation axis, and a separation distance between the tapered portion and the monitor glass is the chopper. An optical monitor formed so as to decrease toward the outer edge side of the plate. The optical monitor according to claim 1.
The tapered portion is provided at an outer edge of the chopper plate;
The chopper plate is configured to reciprocate in parallel with the monitor glass, and the plurality of slits are arranged in the reciprocating direction,
An optical monitor , wherein a separation distance between the tapered portion and the monitor glass increases or decreases in a direction orthogonal to a reciprocating direction of the chopper plate .   The optical monitor according to claim 2, wherein an opening width of the slit is formed so as to increase from the rotating shaft side toward the outer edge portion side.   A vacuum deposition apparatus comprising: the evaporation source; the optical monitor according to claim 1; a substrate holder that holds a processing substrate; and a vacuum chamber that contains the evaporation source, the optical monitor device, and the substrate holder.   7. The vacuum vapor deposition apparatus according to claim 6, wherein the vacuum chamber and the substrate holder are substantially cylindrical, the processing substrate is held on an inner surface of the substrate holder, and the evaporation source and the optical monitor are the substrate holder. A vacuum deposition apparatus arranged on the inner surface side of the substrate and configured to be rotated about a cylindrical axis.

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