JP4456921B2 - Evaporator for emitter formation - Google Patents

Description

  The present invention relates to a vapor deposition apparatus for forming an emitter array built in a field emission device represented by a field emission display.

An apparatus configuration of a general vapor deposition apparatus for forming the emitter array is shown in FIG. FIG. 1 is a schematic view showing the inside of a vacuum vapor deposition chamber, in which a metal crucible 1 as an evaporation source and a substrate 2 are arranged to face each other via a shutter 3. A heater 4 is installed on the back surface of the substrate 2. When the electron beam (EB) is irradiated from a non-illustrated electron gun to the crucible 1 containing a vapor deposition material 5 such as Mo metal, vapor deposition is performed. The material 5 evaporates upward from the opening 1 a of the crucible 1. Then, when the shutter 3 is opened, it is deposited on the substrate 2 heated to 150 to 300 ° C. by the heater 4. The ultimate pressure during film formation is generally 1 × 10 ⁻⁴ Pa or less. In FIG. 1, reference numeral 6 denotes a film thickness monitor, which is arranged so as to monitor the evaporation rate of the vapor deposition material that diffuses and evaporates uniformly from the opening 1a of the crucible 1 to the upper space. In general, the film thickness monitor 6 indirectly monitors the film thickness growth of the vapor deposition material on the substrate 2 and opens and closes the shutter 3 in accordance with the measured value.

  An emitter array formed using such a vapor deposition apparatus is formed through a process as shown in FIG. That is, the surface of the substrate 2 in FIG. 1 will be described in detail. As shown in FIG. 2A, the cathode electrode 21 and the gate electrode 22 are laminated via the insulating layer 23, and the central gate electrode 22 In the non-continuous portion 24, a hole portion where the cathode electrode 21 is exposed as a bottom portion is formed.

As shown in FIG. 2B, conical emitter cones 25 are formed at the bottom of the hole by the deposition of the vapor deposition material arriving from below in a transpiration state, and the cones 25 are formed at a number of locations on the substrate. Is obtained. In addition, as shown in FIG. 2B, the vapor deposition material cannot be selectively or intensively guided only to the non-continuous portion 24. Therefore, in practice, the vapor deposition material Mo26 is deposited also on the gate electrode 22 facing the crucible 1 (see FIG. 1). As a result, after the discontinuous portion 24 is closed, the vapor deposition material Mo26 is removed. Thus, the emitter cone 25 is obtained as shown in FIG. Therefore, it is required to accurately form the emitter cone 25 having a desired shape before the non-continuous portion 24 is closed.

More specifically, the cone-shaped slope portion 25a of the emitter cone 25 is not only in contact with the gate electrode 22 or the insulating layer 23, as well as being formed in a precise cone shape that is isotropic. A structure that stands upright on the cathode electrode 21 with a gap between them is required. It is also important that the tip 25b of the cone 25 is located on the extension line of the gate electrode 22. For this purpose, it is ideal that the vapor deposition material arriving from below in the transpiration state is substantially perpendicular to the incident direction with respect to the hole portion whose bottom is the substrate 2, particularly the cathode electrode 21. By using an emitter cone having a desired shape, the electron emission characteristics of the emitter are improved, and as a result, accurate control of the electroluminescent device is facilitated.

  By the way, the increase in the screen size of displays in recent years has progressed without exception in field emission devices, and a large substrate is often used corresponding to this. The process for forming the emitter array needs to correspond to this. For example, as described above, as a method for obtaining a substantially vertical incident direction, there is a long-distance process type film forming method in which the distance between the crucible 1 as a vapor deposition source and the substrate 2 in FIG.

  However, the method using the long-distance process type cannot sufficiently cope with the recent progress in the enlargement of the substrate. For example, even when a general 400 mm square large substrate is used, in order to limit the incident angle of the vapor deposition material to the substrate to 10 ° or less, the distance between the crucible 1 and the substrate 2 needs to be 1600 mm or more. Further, when a larger 1000 mm square substrate is used, the necessary distance is increased to 4000 mm or more, and thus the size of the apparatus cannot be avoided. Moreover, when this space | interval expands, the vapor deposition rate of the vapor deposition material with respect to a board | substrate will fall. The time required to form an emitter cone 1 μm high was about 10 minutes for a large 400 mm square substrate, but more than 60 minutes for a 1000 mm square substrate, which is disadvantageous in terms of process efficiency. I cannot deny.

For this reason, conventionally, in order to keep the substrate and the evaporation source at a relatively short distance, the incident angle such as a shielding plate is regulated so as to regulate the incident angle when the vapor deposition material particles from below are deposited on the substrate. A regulating member is provided (see, for example, Patent Document 1).
JP-A-10-176262 (page 3, Fig. 1-2)

  However, the method according to Patent Document 1 ensures a uniform film density with respect to an unspecified portion on the substrate, and therefore there remains a problem in applying it to a field emission device as it is. In particular, when one evaporation source is shared for each of a plurality of emitter arrays, it becomes difficult to obtain the isotropicity of the emitter array as the distance from the center position of the evaporation source increases. For this reason, quality varies in each emitter array, and it becomes difficult to obtain a high-definition screen with high accuracy.

  In view of the above problems, an object of the present invention is to provide a vapor deposition apparatus capable of forming emitters of uniform quality over the entire substrate corresponding to a large substrate.

In order to solve the above-described problems, an emitter forming vapor deposition apparatus according to the present invention forms an emitter by depositing a cone-shaped emitter cone on a rectangular substrate while conveying the substrate in the longitudinal direction by a conveying means. A vapor deposition apparatus, wherein a plurality of vapor deposition sources are arranged in a diagonal direction of the substrate so as to face the substrate, and an incident angle regulating means for regulating an incident angle of vapor deposition material particles adhering to the substrate is provided for each evaporation source. It was set up .

  According to this, in the process of manufacturing a normal field emission display in which a large number of emitters are mounted, when forming the emitter cone corresponding to the field emission portion, the deposition material particles from the evaporation source as the material supply source are formed. Since the incident angle restricting means is provided, the transpiration process of the material particles is regulated and arranged at a specific incident angle. Thus, film formation can be performed in a relatively short film formation time without requiring widening of the substrate-vapor deposition source distance. Moreover, since such an incident angle restricting means is provided for each evaporation source corresponding to each emitter cone, the formed emitter cone is assumed to have a shape as designed at each of a number of points necessary for the display configuration. can get.

  As a result, the field emission display of the final product has a high-definition screen with high precision, in which high-performance emitters are uniformly distributed over the entire screen.

  The evaporation source to be arranged may correspond to the emitter cone on a one-to-one basis, or a specific multipoint emitter cone as a unit, and the unit of the emitter cone and the evaporation source have a one-to-one relationship. You may make it correspond. What is important is that the deposition material arrives at an angle of incidence controlled to a specific range for a specific population of emitter cones.

  Further, the substrate portion on which these evaporation sources are arranged to face each other is at least a part of a plurality of locations on the substrate where the emitter cone is to be formed, and the film formation on the partial substrate portion is completed each time the film formation is completed. By horizontally transporting the substrate, it is possible to perform the pass-type film formation in which the substrate portion newly disposed opposite to the evaporation source is the next film formation target. Thereby, it is possible to efficiently form emitter cones at many points.

Alternatively, the substrate portion on which these evaporation sources are opposed to each other is at least a part of a plurality of locations on the substrate. By continuously forming the substrate portion opposed to the substrate as the next film formation target, it is possible to perform the continuous film formation of the passing type, and further improve the efficiency of the emitter cone formation .

  In these cases, as the incident angle restricting means, a shielding member that surrounds at least a part of the space separating the substrate portion where the evaporation source and the emitter cone should be formed and the opening portion of the evaporation source may be used. By adopting such a shielding member, many portions of the transpiration process from the opening portion of the evaporation source opened upward to the substrate portion are surrounded by the shielding member.

  As a result, the material particles arriving at the substrate portion go through a process path exceeding the upper end of the shielding portion, and as a result, the incident angle with respect to the substrate portion is selected. Then, attachment to the substrate is performed in a state where the incident angle is selected, and it becomes easy to form an emitter cone having a desired shape.

  The above incident angle regulating means regulates the incident angle of the vapor deposition material with respect to the substrate to 15 ° or less, thereby providing good electron emission characteristics even when a 1 m square large substrate is used for forming the field emission display. You can get the final product.

  In the present invention, since the evaporation source provided with the incident angle regulating means for regulating the incident angle of the vapor deposition material particles is arranged to face each substrate portion for each substrate portion on which the emitter cone is to be formed, the vapor deposition material particles Are attached to the substrate at an angle close to vertical, and thus the emitter cones formed at multiple points on the substrate are obtained as having shapes as designed respectively. In addition, it is possible to set a film forming process in a relatively short time while forming a film on a large substrate. As a result, the final field emission display has a high-precision screen with a high-performance emitter mounted on the entire screen.

Further, when the deposition process for these emitter formation, pass deposition, any of methods such as pass continuous film is selectable, can flexibly respond to demands of the manufacturing process.

FIG. 3 is a schematic view showing the arrangement of the substrate 32 and the crucibles 31a, 31b, 31c as the vapor deposition source in the vapor deposition apparatus of the first reference embodiment . After setting the deposition chamber containing the arrangement member to an ultimate pressure of less than 1 × 10 ⁻⁴ Pa, deposition of Mo metal or the like is performed on the substrate 32 heated to 250 ° C. by a heater (not shown). When the crucibles 31a, 31b, and 31c containing the materials 35a, 35b, and 35c are irradiated with an electron beam of 12 kW from an unillustrated electron gun, the vapor deposition materials 35a, 35b, and 35c are converted into the crucibles 31a, 31b, and 31c, respectively. Evaporate upward from the opening of the substrate to form a conical emitter cone on the substrate 32. As described above, in order to form an emitter cone having a size of several μm in a desired shape, the incident angle θ1 when the vapor deposition materials 35a, 35b, and 35c adhere to the substrate 32 is made as small as possible, and the vapor deposition material from below is formed. Ideally, the film adheres substantially perpendicularly to the substrate 32.

Therefore, in this embodiment, each of the crucibles 31a, 31b, and 31c simultaneously surrounds the crucible side surface portion including the opening portions and the opposing spaces 33a, 33b, and 33c of the crucible and the substrate 32, and opens up and down. Box-shaped housings 34a, 34b, and 34c were provided. And the vapor deposition material which goes to the board | substrate 32 direction with an incident angle of 15 degrees or more is interrupted | blocked, and the vapor deposition material which goes to the board | substrate 32 with an incident angle of 15 degrees or less can reach the board | substrate 32 exceeding the upper end of the housings 34a, 34b, 34c. I did it. Thereby, the emitter cone formed by the three regions of the substrate portions 32a, 32b, and 32c is obtained in a conical shape (see FIG. 2) having a desired shape and size.

  In FIG. 3A, the upper direction of the paper is the transport direction of the substrate 32, and the substrate portions 32a, 32b, and 32c to be deposited are transported by 50 mm / min to the crucibles 31a, 31b, and 31c that are fixed in position. Move relative to speed. Thereby, as the substrate 32 to be transported moves, the substrate portion to be newly formed is sent from the lower side of the paper so as to face each of the crucibles 31a, 31b, 31c, and the next film formation target The emitter cone forming process is continued in three regions.

  As described above, by continuously carrying the substrate 32, a continuous passing film formation method is realized. However, the present invention is not limited to this, and for example, relative movement of the substrate portions 32a, 32b, and 32c. By intermittently performing the above, it is possible to adopt an intermittent pass film formation method.

In either method, the emitter cones are formed as many points over the entire substrate 32 by sequentially performing the pass film formation. Since these emitter cones are obtained in a conical shape having a desired shape and size (see FIG. 2), the final field emission display can cope with a large screen and high definition.

FIG. 4 is a schematic view showing the arrangement of the substrate 42 and the crucibles 41a, 41b, 41c as the vapor deposition sources in the vapor deposition apparatus according to the first aspect of the present invention. The difference from the first embodiment is that the crucibles are not arranged linearly along the edge of the substrate 42 but are arranged linearly along the diagonal of the substrate 42. Since the box-shaped housings 34a, 34b, and 34c block the progress of the vapor deposition material, it is inevitable that the vapor deposition material adheres to the inside thereof, and periodic maintenance work is required. In the first reference aspect , it is expected that maintenance work is required particularly for the housing 34b arranged in the center. However, the arrangement as in the second aspect has an advantage that it can be reduced. .

FIG. 5 is a schematic view showing the arrangement of the substrate 52 and the crucibles 51a, 51b, 51c, 51d as the vapor deposition source in the vapor deposition apparatus of the second reference mode . By arranging each crucible in a square pattern, the entire substrate 52 is occupied by the substrate portions 52a, 52b, 52c, and 52d that are film formation targets. And the vapor deposition material which goes to the board | substrate 52 with the incident angle of 15 degrees or less was made to reach the board | substrate 52 exceeding the upper end of the housings 54a, 54b, 54c, and 54d. Thereby, the formed emitter cone is obtained in a conical shape (see FIG. 2) having a desired shape and size over the entire substrate. In the case of this embodiment, unlike the first reference embodiment and the first embodiment , a fixed film formation method in which the substrate 52 is stationary is used instead of the passage film formation method. The pressure conditions and the like were the same as in the first embodiment, and an emitter cone having a height of about 1 μm could be obtained in a film formation time of about 7 minutes, and the film formation time was greatly reduced.

  When the vapor deposition apparatus shown in FIGS. 3 to 5 is used, the incident angle of the vapor deposition material is changed by changing the length of the casing mounted on the vapor deposition apparatus, and the shape and electric field of the emitter cone obtained in each case are changed. When the emission current of the emission type device was measured, the result shown in FIG. 6 was obtained (relative value display when the design value is 1).

  From FIG. 6, it was found that when the incident angle exceeds 15 °, the height of the emitter cone and the emission current are lower than the design values, which directly leads to performance degradation.

  The present invention can be applied to a field emission device represented by a field emission display.

Schematic showing a general example of a deposition apparatus for emitter formation (A)-(c) Process drawing which shows an emitter cone formation process (A) Top view which shows the arrangement | positioning relationship of the 1st reference aspect of a vapor deposition apparatus . (B) Side surface sectional drawing of (a). (A) The top view which shows the arrangement | positioning relationship of the 1st aspect of the vapor deposition apparatus of this invention (b) Side surface sectional drawing of (a) (A) Top view which shows arrangement | positioning relationship of 2nd reference aspect of vapor deposition apparatus . (B) Side surface sectional drawing of (a). Graph showing the performance ratio (compared to the design value) corresponding to the incident angle of the vapor deposition material

1 31a 31b 31c Crucible (deposition source)
2 32 42 52 Substrate 21 Cathode electrode (Substrate)
25 Emitter cones 32a 32b 32c Deposition target substrate portions 34a 34b 34c Box-shaped enclosure (shielding member, incident angle regulating means)
41a 41b 41c Crucible (deposition source)
42a 42b 42c Deposition target substrate portions 44a 44b 44c Box-shaped housing (shielding member, incident angle regulating means)
51a 51b 51c 51d Crucible (deposition source)
52a 52b 52c 52d Deposition target substrate portions 54a 54b 54c 54d Box-shaped housing (shielding member, incident angle regulating means)
θ1 Incident angle

Claims (2)

  A vapor deposition apparatus for forming an emitter by depositing a cone-shaped emitter cone on a substrate while conveying a rectangular substrate by a conveying means in a longitudinal direction thereof, wherein a vapor deposition source is opposed to the substrate. An emitter forming vapor deposition apparatus comprising a plurality of incident angle regulating means arranged in the direction of the diagonal line for regulating the incident angle of vapor deposition material particles adhering to the substrate for each evaporation source.   An incident angle restricting means for restricting an incident angle of vapor deposition material particles adhering to the substrate to 15 ° or less is provided for the evaporation source, and film formation is performed continuously or intermittently on the substrate. The emitter forming vapor deposition apparatus according to claim 1.

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