JP2009221496A - Thin film deposition apparatus, and method of manufacturing thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film deposition apparatus capable of comprehending the vapor flow density distribution of a vapor deposition material with a simple configuration, thereby controlling the vapor deposition rate and the thickness of a thin film. <P>SOLUTION: The thin film deposition apparatus is used for depositing a thin film on the surface of a workpiece 7 arranged on a ceiling side by vaporizing a vapor deposition material 3 provided in an evaporation source 1 by the irradiation of electron beam 5. The apparatus includes: a plurality of film thickness sensors 8, 9 for measuring the film thickness of the vapor deposition material 3 deposited on itself; a calculation unit 10 for calculating the thickness of the thin film deposited on the surface of the workpiece 7 based on the plurality of film thicknesses measured by the plurality of film thickness sensors 8, 9; and an electron beam source 11 for controlling the output of the electron beam 5 according to the thickness of the thin film calculated by the calculation unit 10. At least two film thickness sensors are provided at the different angles from each other which are formed between the vertically upward direction to the evaporation surface from a center point of a part for storing the vapor deposition material 3 in the evaporation source 1 and the direction reaching the self film thickness sensor from the center point. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thin film forming apparatus for forming a thin film by electron beam evaporation and a method for manufacturing the thin film.

  Conventionally, vacuum deposition has been performed in which a solid substance is placed in a reduced pressure state, heated to increase vapor pressure, evaporate a material to be evaporated prepared in advance in an evaporation source, and form a solid film on the substance to be a substrate. It has been broken. As an example of an apparatus for performing such vacuum vapor deposition, an electron beam vapor deposition apparatus that evaporates the material by heating it by irradiating the material with an electron beam. A thin film obtained by vacuum deposition can be used in various fields as an optical thin film element utilizing the interference effect of light, for example, by having a desired film thickness. As another example, a thin film formed on a wafer is used for forming a circuit pattern as an insulating film or a conductive film. In the case of forming a thin film with an electron beam evaporation apparatus, the evaporation rate is generally controlled by a film thickness sensor.

  Patent Document 1 describes an optical thin film forming apparatus and method provided with a correction mechanism for film thickness distribution deterioration accompanying a change in evaporation coefficient in the formation of a dielectric multilayer optical filter. The evaporation coefficient that indicates how far the evaporation material evaporates from the evaporation source varies depending on the difference in electron beam width and position incident on the evaporation material and the evaporation material dissolution surface height in the actual film formation process. To do. Therefore, maintaining these conditions constant and preventing the deterioration of the in-plane film thickness distribution and the accompanying yield reduction are important manufacturing issues.

The optical thin film forming apparatus described in Patent Document 1 includes an evaporation source monitoring mechanism, a film thickness distribution measuring mechanism, an evaporation source position adjusting mechanism, and a crystal film thickness sensor angle adjusting mechanism. In addition, the in-plane film thickness distribution of the deposition substrate can be improved by constantly monitoring the in-plane distribution of the deposition substrate and feeding back to the evaporation source position and the electron beam irradiation conditions.
JP 2005-120441 A

  However, in the apparatus for forming an optical thin film described in Patent Document 1, the film thickness distribution measuring mechanism measures the film thickness distribution by measuring the transmittance and reflectance of the measurement light with respect to the thin film. It cannot be used depending on the material of the film formation substrate. Further, the optical thin film forming apparatus includes an evaporation source monitoring mechanism, a film thickness distribution measuring mechanism, an evaporation source position adjusting mechanism, and a quartz crystal in order to constantly monitor the in-plane distribution of the evaporation source and the deposition substrate during the film forming process. A complicated mechanism such as a film thickness sensor angle adjusting mechanism is required, and costs are also increased.

The quartz film thickness sensor measures the film thickness of a thin film formed on a film formation substrate by utilizing the fact that the vapor flow density distribution in vapor deposition is a distribution approximate to cos ^λθ. When the film formation is continued without supplying the vapor deposition material, the vapor deposition material is reduced, the height of the evaporation surface is lowered, and the density distribution of the vapor flow is changed. The relative ratio of the upper deposition rate changes, and it is difficult to estimate the thickness of the thin film from the result measured by the quartz film thickness sensor.

  In order to prevent the deposition material from decreasing and the conditions such as density distribution from changing, there is a thin film forming device that has a mechanism for supplying the material by wire feed, but it is difficult to process into a wire shape. In the case of using a material, it cannot be used, and it requires a complicated mechanism and costs.

  SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and grasps the vapor flow density distribution of the vapor deposition material with a simple configuration and can control the vapor deposition rate and the film thickness of the thin film, and a thin film manufacturing method It is an issue to provide.

  In order to solve the above problems, a thin film forming apparatus according to the present invention evaporates a vapor deposition material provided in an evaporation source by irradiation with an electron beam, and deposits the vapor deposition material on the surface of a workpiece disposed on a ceiling side. In the thin film forming apparatus for forming a thin film, at least two film thickness sensors for measuring the film thickness of the vapor deposition material deposited on the thin film forming apparatus, and the workpiece based on a plurality of film thicknesses measured by the at least two film thickness sensors. A calculation unit that calculates the film thickness of the thin film formed on the surface of the film, and a control unit that controls the output of the electron beam according to the film thickness of the thin film calculated by the calculation unit, the at least two films The thickness sensor has an angle formed by a direction perpendicular to the evaporation surface from the center point of the evaporation source containing the vapor deposition material and a direction from the center point to the film thickness sensor. Te, characterized in that provided in the different angles.

  ADVANTAGE OF THE INVENTION According to this invention, a vapor deposition rate and film thickness control of a thin film can be performed with a simple structure irrespective of the change of the vapor flow density distribution of vapor deposition material.

  Embodiments of a thin film forming apparatus and a thin film manufacturing method according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a thin film forming apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, the thin film forming apparatus includes an evaporation source 1, a work 7, film thickness sensors 8 and 9, a calculation unit 10, and an electron beam power source 11. The evaporation source 1 includes a crucible 2, a vapor deposition material 3 disposed in advance in the crucible 2, and an electron gun 4.

  The thin film forming apparatus in this embodiment evaporates the vapor deposition material 3 provided in the evaporation source 1 by irradiation of the electron beam 5, and deposits the vapor deposition material 3 on the surface of the work 7 arranged on the ceiling side to form a thin film. The thin film is formed in a reduced pressure environment inside a vacuum chamber or the like (not shown). The vapor deposition material 3 may be a metal material such as aluminum or titanium.

  The evaporation source 1 uses an electron gun 4 provided with a filament by supplying power from an electron beam power source 11 to be described later, and converges the electron beam 5 on the vapor deposition material 3 to heat and evaporate it. Here, the electron beam 5 irradiated by the electron gun 4 is bent in the direction in the crucible 2 by controlling the beam trajectory and shape by a magnetic field generated from a magnetic circuit (not shown), and collides with the vapor deposition material 3 in the crucible 2. To do. At that time, the electron beam 5 is scanned so as to hit an arbitrary position on the evaporation surface of the vapor deposition material 3 to evaporate the vapor deposition material 3. The vapor deposition material 3 evaporated from the evaporation source 1 generates a vapor flow 6.

  The work 7 is a substrate or the like on which a thin film made of the evaporated vapor deposition material 3 is formed, and is disposed at a position facing the evaporation source 1.

  The film thickness sensors 8 and 9 measure the film thickness of the vapor deposition material 3 deposited on itself. As an example of the film thickness sensors 8 and 9, a crystal film thickness sensor can be considered. The quartz film thickness sensor utilizes the fact that the natural frequency of the crystal resonator changes due to its mass change. The evaporated material 3 is deposited on the crystal resonator to detect the natural vibration frequency, and the frequency change. Is monitored to measure the film thickness of the vapor deposition material 3 deposited on itself. The number of film thickness sensors in the present invention is not limited to two, and it is sufficient that at least two film thickness sensors are provided. In this embodiment, it is assumed that two film thickness sensors 8 and 9 are provided.

  Further, the film thickness sensor 8 and the film thickness sensor 9 are from the center point of the portion of the evaporation source 1 containing the vapor deposition material 3 to the upper direction perpendicular to the evaporation surface and from the center point to the own film thickness sensor. The angles formed by the directions are different from each other. If there are three or more film thickness sensors, at least two of the film thickness sensors are provided at angles different from each other, and the angles are the same for all film thickness sensors. There shall be no.

  The calculation unit 10 is, for example, a microprocessor, and calculates the film thickness of the thin film formed on the surface of the workpiece 7 based on the plurality of film thicknesses measured by the plurality of film thickness sensors 8 and 9. A specific calculation method will be described later. The thin film thickness calculated by the calculation unit 10 may be output by an output unit such as a display (not shown).

  The electron beam power source 11 corresponds to the control unit of the present invention, and controls the output of the electron beam 5 by supplying power to the electron gun 4 according to the film thickness of the thin film calculated by the calculation unit 10. A specific control method will be described later.

Next, the operation of the present embodiment configured as described above will be described. FIG. 2 is a block diagram showing the positional relationship of each component of the thin film forming apparatus according to Embodiment 1 of the present invention. As shown in FIG. 2, the film thickness sensor 8 is provided at a distance r ₁ away from the center point of the portion of the evaporation source 1 that stores the vapor deposition material 3. The film thickness sensor 9 is provided at a distance r ₂ away from the center point of the portion of the evaporation source 1 that stores the vapor deposition material 3. In this embodiment, it is assumed that r ₁ = r ₂ .

Furthermore, as shown in FIG. 2, the angle formed between the center point of the portion of the evaporation source 1 containing the vapor deposition material 3 and the direction perpendicular to the evaporation surface and the direction from the center point to the film thickness sensor 8 is it is θ _1. Similarly, the angle formed between a direction leading to a film thickness sensor 9 vertically upward and the center point with respect to the evaporation surface from the center point is theta _2. Further, as described above, θ ₁ ≠ θ ₂ .

Here, the density distribution of the vapor flow 6 by the vapor deposition material 3 evaporated from the evaporation source 1 will be described. FIG. 3 is a diagram showing the vapor flow density distribution of the vapor flow released from the evaporation source. Assuming that the vapor flow density in the vertical upward direction with respect to the evaporation surface of the vapor deposition material in the evaporation source is φ ₀ and the vapor flow density in the angle direction that forms an angle θ with the vertical upward direction is φ _θ , φ ₀ and φ _θ The vapor flow density distribution showing the relationship is expressed by equation (1). Note that both φ ₀ and φ _θ are vapor flow densities at a point equidistant from the evaporation source.

  As described above, if the film formation is continued without supplying the vapor deposition material, the vapor deposition material is decreased and the height of the evaporation surface is decreased. Along with this, since the value of λ shown in the equation (1) changes, the vapor flow density distribution changes, and the deposition rate of the thin film to be formed becomes unstable.

The thin film forming apparatus in the present embodiment controls the formation of the thin film as follows in order to avoid the thin film formation due to the unstable deposition rate as described above. First, the relationship between the thickness t _{0 of the} thin film formed on the workpiece 7 and the measured values t ₁ and t ₂ of the thickness of the vapor deposition material 3 deposited by the film thickness sensors 8 and 9 is ( It is expressed by the formulas 2) and (3).

Here, A is a sensitivity correction coefficient of the film thickness sensors 8 and 9, and is a value common to both sensors if the two film thickness sensors 8 and 9 are calibrated by the same standard. The value of A is a known value because it is a numerical value calculated in advance, and may be calculated once in the preparation stage before actual thin film formation, and thereafter the same numerical value is continuously used. As a specific method of calculating the value of A, a film is formed on the work 7 under appropriate conditions, and at that time, measured values t ₁ and t ₂ by the film thickness sensors 8 and 9 are recorded. Thereafter, the film thickness t _{0 of} the thin film formed on the work 7 is directly measured by a step gauge or the like. By substituting the values of angles θ ₁ , θ ₂ based on the positions of t ₀ , t ₁ , t ₂ and film thickness sensors 8, 9 measured as described above into equations (2) and (3), the value of A is obtained. Can be sought. In addition, the value of λ at that time can be obtained by the following equation (4).

In the present embodiment, each of the plurality of film thickness sensors 8 and 9 is equidistant (r ₁ = r ₂ ) from the center point of the portion of the evaporation source 1 containing the vapor deposition material 3. Therefore, equations (2) and (3) are established. When r ₁ ≠ r ₂ , the expressions (2) and (3) do not hold as they are, and thus the expression needs to be modified. This will be described in Example 2.

Moreover, it is preferable that the angles θ ₁ and θ ₂ that are values related to the positions of the film thickness sensors 8 and 9 do not take very close values. When the angles θ ₁ and θ ₂ are very close values, the values of the equations (2) and (3) are also very close values, so that the calculation of λ in the equation (4) is performed accurately. This is because there is a possibility of not being broken. As an example, it can be considered that θ ₁ = 30 ° and θ ₂ = 45 °.

In addition, if the angles θ ₁ and θ ₂ take too large values (for example, 60 ° or 70 °), it is considered that an error with the cosine law equation shown in the equations (2) and (3) appears. It is preferable to take a small value (for example, 45 ° or less).

  Next, the operation of the present invention in the actual thin film formation process will be described. First, the evaporation source 1 uses the electron gun 4 to supply power from the electron beam power supply 11 to converge the electron beam 5 onto the vapor deposition material 3 and heat and evaporate it.

  The vapor deposition material 3 evaporated from the evaporation source 1 becomes vaporized particles to generate a vapor flow 6, reaches the work 7 on the ceiling side, and then vaporizes to form a thin film on the work 7. At that time, the evaporated vapor deposition material 3 reaches the film thickness sensors 8 and 9 and is deposited.

The film thickness sensors 8 and 9 measure the film thickness of the vapor deposition material 3 deposited on itself. The film thickness measurement value t ₁ measured by the film thickness sensor 8 is output to the calculation unit 10. Similarly, the film thickness measurement value t ₂ measured by the film thickness sensor 9 is output to the calculation unit 10.

The calculation unit 10 uses a plurality of film thickness measurement values t ₁ and t ₂ measured by the plurality of film thickness sensors 8 and 9 and known values θ ₁ and θ _{2 according} to the equation (4). λ is calculated. Further, the calculation unit 10 uses the known values A, t ₁ , t ₂ , θ ₁ , θ ₂ , and the calculated λ to form a thin film on the work 7 according to the equation (2) or (3). The thickness t ₀ is calculated, and the calculation result is output to the electron beam power source 11.

The electron beam power supply 11 controls the output of the electron beam 5 by supplying electric power to the electron gun 4 according to the film thickness t ₀ of the thin film calculated by the calculation unit 10. Specifically, the electron beam power supply 11 stores a target film thickness value in advance, and the thin film thickness t ₀ calculated by the calculation unit 10 is a predetermined film thickness (target film thickness value). When reaching the above, the output of the electron beam 5 is controlled to stop. Thereby, the thin film forming apparatus according to the present invention can form a thin film having a desired film thickness.

Further, the electron beam power source 11 stores a target deposition rate in advance, and an increase amount of the thin film thickness t ₀ calculated by the calculation unit 10 every predetermined time is a predetermined deposition rate (target deposition rate). The output of the electron beam 5 is controlled to match the rate. That is, the electron beam power source 11 increases the output of the electron beam 5 when the increase amount of the thin film thickness t ₀ calculated by the calculation unit 10 per predetermined time does not reach the target deposition rate. Control to reach the target deposition rate. On the contrary, the electron beam power source 11 reduces the output of the electron beam 5 when the increase amount of the thin film thickness t ₀ calculated by the calculation unit 10 per predetermined time exceeds the target deposition rate. Control to match the target deposition rate.

In the present embodiment, the electron beam power source 11 controls the output of the electron beam 5 as a control unit. However, it should be understood that the calculation unit 10 may serve as the control unit of the present invention. In that case, the calculation unit 10 stores a target film thickness value or vapor deposition rate in advance, and controls the power supply of the electron beam power supply 11 according to the film thickness t ₀ calculated by itself. The output of the electron beam 5 is controlled so as to achieve a target film thickness value or vapor deposition rate.

  As described above, according to the thin film forming apparatus according to the first embodiment of the present invention, since the plurality of film thickness sensors 8 and 9 are provided at different angles, the vapor flow density distribution of the evaporated deposition material 3 is accurately determined. It is possible to control the deposition rate and the film thickness of the thin film. This is because the conventional thin film forming apparatus calculates the film thickness of the thin film with the value of λ in the cosine law of the vapor flow density distribution fixed, and thus the error in the calculated film thickness value when the actual value of λ fluctuates. However, since the thin film forming apparatus of the present invention includes the plurality of film thickness sensors 8 and 9 at different angles, it is possible to accurately calculate the value of λ that varies according to the equation (4). Because it can.

  Therefore, the present invention is particularly effective when a thin film is formed by vapor deposition using the vapor deposition material 3 in which it is difficult to provide a material supply mechanism in terms of material or cost. For example, when the thin film is formed by vapor deposition by continuously supplying and discharging the work 7, the vapor deposition material 3 is reduced by continuously forming the film without supplying the vapor deposition material 3, and the height of the evaporation surface is reduced. The film forming apparatus of the present invention corrects the deviation between the measured values of the film thickness sensors 8 and 9 and the actual film thickness, and grasps the accurate film thickness of the thin film formed on the work 7. Therefore, it is possible to control the deposition rate and the film thickness of the thin film, thus eliminating the need for a material supply mechanism for the deposition material 3, avoiding the complexity of the apparatus, reducing costs, and realizing stable deposition. it can.

  In addition, a complicated mechanism for constantly monitoring the in-plane distribution of the evaporation source and the film formation substrate during the film formation process described in Patent Document 1 is unnecessary, and the film thickness can be controlled with a simple configuration. It is.

Further, since each of the plurality of film thickness sensors 8 and 9 is equidistant (r ₁ = r ₂ ) from the center point of the portion of the evaporation source 1 that stores the vapor deposition material 3, (2) , (3), (4), there is less room for error in comparison with the case where the distance is different, and it is possible to accurately calculate λ and grasp the vapor flow density distribution.

  In the present embodiment, the work 7 is described as being vertically above the evaporation source 1, but it is not necessarily required to be directly above the evaporation source 1. Since the thin film forming apparatus in the present invention can grasp the state of the vapor flow density distribution by providing a plurality of film thickness sensors, even if the work 7 is provided obliquely above the evaporation source 1, This is because the film thickness of the thin film formed on the surface of the work 7 can be calculated from the state of the vapor flow density distribution.

The thin film forming apparatus according to the second embodiment of the present invention is the same as the configuration of the first embodiment shown in FIGS. The difference from the first embodiment is that the distance r ₁ between the film thickness sensor 8 and the central point of the portion of the evaporation source 1 containing the vapor deposition material 3 is different from the distance r ₂ between the film thickness sensor 9 and the central point. Only points with values. That is, in this embodiment, it is assumed that r ₁ ≠ r ₂ .

Next, the operation of the present embodiment configured as described above will be described. Since the vapor flow density is inversely proportional to the square of the distance, it can be said that the film thickness is also inversely proportional to the square of the distance. Therefore, in this embodiment, the following equation (5) is used instead of equation (3), and equation (6) is used instead of equation (4).

Here, t _{2 → 1} is a value converted when the measured value t ₂ measured by the film thickness sensor 9 at the distance r ₂ is measured at the distance r ₁ .

First, the relationship between the thickness t _{0 of the} thin film formed on the workpiece 7 and the measured values t ₁ and t ₂ of the thickness of the vapor deposition material 3 deposited by the film thickness sensors 8 and 9 is ( It is expressed by the formulas 2) and (5). As shown in the equation (5), t _{2 → 1} can be obtained by multiplying the measurement value t ₂ measured by the film thickness sensor 9 by (r ₂ / r ₁ ) ² .

Thereafter, as in the first embodiment, the values of the angles θ ₁ and θ ₂ based on the positions of t ₀ , t ₁ , t _{2 → 1} and the film thickness sensors 8 and 9 are substituted into the equations (2) and (5). Thus, the value of A can be obtained. In addition, the value of λ at that time can be obtained by equation (6).

Next, the operation of the present invention in the actual thin film formation process is the same as that in the first embodiment until the film thickness measurement value t ₂ measured by the film thickness sensor 9 is output to the calculation unit 10.

The calculating unit 10 calculates t _{2 → 1} based on the input t ₂ , and then uses t ₁ , t _{2 → 1} and known values θ ₁ and θ ₂ to calculate λ according to equation (6). Is calculated. Furthermore, the calculation unit 10 uses the known values A, t ₁ , t _{2 → 1} , θ ₁ , θ ₂ , and the calculated λ, and the thin film on the work 7 according to the equation (2) or (5). The film thickness t ₀ is calculated, and the calculation result is output to the electron beam power source 11.

  Since the subsequent operation is the same as that of the first embodiment, a duplicate description is omitted.

  As described above, according to the thin film forming apparatus according to the second embodiment of the present invention, in addition to the effects of the first embodiment, the film thickness sensor 8, 9 is limited, and even if it is difficult to install both film thickness sensors at the same distance from the evaporation source 1, the vapor flow density distribution can be grasped without problems and formed on the workpiece 7. It is possible to control the thickness of the thin film.

  The present invention is applicable to a thin film forming apparatus that forms a thin film by electron beam evaporation.

It is a block diagram which shows the structure of the thin film forming apparatus of the form of Example 1 of this invention. It is a block diagram which shows the positional relationship of each structure of the thin film forming apparatus of the form of Example 1 of this invention. It is a figure which shows the vapor flow density distribution of the vapor flow discharge | released from an evaporation source.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Evaporation source, 2 ... Crucible, 3 ... Evaporation material, 4 ... Electron gun, 5 ... Electron beam, 6 ... Steam flow, 7 ... Workpiece, 8 ... Film thickness sensor, 9 ... Film thickness sensor, 10 ... Calculation part, 11: Electron beam power supply.

Claims (5)

In a thin film forming apparatus for forming a thin film by evaporating a vapor deposition material provided in an evaporation source by irradiation with an electron beam and depositing the vapor deposition material on a surface of a work,
At least two film thickness sensors for measuring a film thickness of the vapor deposition material deposited on the self;
A calculation unit that calculates a film thickness of a thin film formed on the surface of the workpiece based on a plurality of film thicknesses measured by the at least two film thickness sensors;
A control unit for controlling the output of the electron beam according to the thickness of the thin film calculated by the calculation unit,
The at least two film thickness sensors are formed by an angle formed between a central point of a portion of the evaporation source that stores the vapor deposition material and a direction perpendicular to the evaporation surface, and a direction from the central point to the film thickness sensor. Are provided at different angles from each other.   2. The thin film formation according to claim 1, wherein the control unit controls the output of the electron beam to stop when the thickness of the thin film calculated by the calculation unit reaches a predetermined thickness. apparatus.   The said control part controls the output of the said electron beam so that the increase amount per predetermined time of the film thickness of the thin film calculated by the said calculation part may correspond to a predetermined vapor deposition rate. The thin film forming apparatus according to claim 2.   4. Each of the at least two film thickness sensors has an equidistant distance from a center point of a portion of the evaporation source that stores the vapor deposition material. The thin film forming apparatus according to claim 1.   A method for producing a thin film, comprising the step of forming a thin film on a workpiece by the thin film forming apparatus according to claim 1.

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