JP2010236040A - Film deposition system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film thickness control device of a thin film in which the thin film having a desired physical quantity with high precision and uniformity is deposited without need of large remodelling of a system. <P>SOLUTION: A film deposition system includes: a physical quantity measurement element for measuring a physical quantity of the thin film during deposition; a comparison section for comparing the physical quantity of the thin film with the desired physical quantity; and a control section for controlling a film deposition condition and/or film deposition time based on the compared result of the comparison section. Thereby, in the deposition of the thin film with the desired physical quantity, the thin film having the desired physical quantity uniformly in the film is deposited. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thin film forming apparatus, and more particularly to a film forming apparatus that controls the film quality and thickness of a thin film.

As a conventional technique for producing a thin film resistor, a metal material such as Ta or NiCr is formed by sputtering, vapor deposition, or the like, and the film thickness is controlled so that the sheet resistance changing with the film thickness becomes a desired resistance. A technique for producing a resistor is generally known. In this conventional thin film resistor fabrication technique, for example, Ta is sputtered in an arbitrary N ₂ atmosphere, reactive sputtering is performed to deposit TaN using Ta as a sputtering target, or resistance is achieved using NiCr. When creating a body, improvements are often made to the elemental composition to obtain the desired resistance and other physical properties, such as by taking a technique of changing the elemental ratio of Ni and Cr. In this way, it can be said that it is important to control the film thickness and constituent elements in the formation of the resistor.

  When the NiCr resistor is formed by sputtering, film formation is generally performed using NiCr prepared in advance with a desired alloy ratio as a target. However, when film formation is repeated using the same target, the alloy ratio of the formed NiCr changes due to the difference in sputtering rates of Ni and Cr. As a result, even with NiCr resistors having the same film thickness, there was a phenomenon that the resistance value changed between the film formed immediately after the sputtering target was attached and the film formed after several film formations thereafter. . This is a phenomenon that occurs not only in sputtering, but also in vapor deposition and using any alloy or compound. This phenomenon creates a resistor having a desired resistance value stably. Making it difficult.

  To solve this problem, a technique disclosed in Patent Document 1 is known as a technique for reducing a difference in resistance value between film forming batches. In the technique disclosed in Patent Document 1, in the sputtering method, the resistance value of the resistor deposited in the immediately preceding batch is quickly read on the resistance measurement stage adjacent to the deposition chamber and fed back to the deposition condition. The film forming conditions are controlled. Thereby, the resistance value of the manufactured resistor can be kept stable without reducing the throughput.

  However, in the technique disclosed in Patent Document 1, the information fed back to the film formation conditions is information on the film formation one batch before and cannot be information on the thin film currently formed. Thus, for example, when the film formation rate fluctuates greatly during film formation, the film thickness of the thin film produced in the film formation batch is different from the target film thickness, and the resistance value and electrical characteristics are also different from the target film thickness. It will be a thing.

  To solve this problem, there is a technique disclosed in Patent Document 2 as a technique for monitoring the resistance value of a thin film during film formation. In the technique disclosed in Patent Document 2, an electrode is placed on a sample to be formed, and a resistance value between the electrodes during film formation is read over time to form a film until a target resistance value is reached. Film formation is terminated when the target resistance value is reached.

JP-A-5-9719 Japanese Patent Laid-Open No. 6-80498

  However, in the technique disclosed in Patent Document 2, a thin film having a target resistance value can be obtained. However, since the film forming conditions are not controlled, the physical property distribution of the thin film to be formed is determined. Is affected by the film formation condition such as film formation rate fluctuation, and it is difficult to form a thin film having uniform film quality at any depth position in the thin film. An adverse effect caused by such a thin film with non-uniform film quality includes a gate electrode formation process in a CMOS process. When Al is used for the gate electrode, first, Al is formed on the entire surface of the wafer by sputtering. Thereafter, a portion to be left as the gate electrode is protected with a resist, and the entire surface of the wafer is dry-etched to remove Al other than the portion used as the gate electrode. In this gate process, when an Al thin film having a non-uniform film quality as described above is first formed on an Al thin film formed by sputtering, side etching corresponding to the film quality occurs during subsequent dry etching. As a result, the gate electrode shape is different from the target gate shape, which causes deterioration of transistor performance and increase in variation.

  In addition, when the technique disclosed in Patent Document 2 is implemented, it is necessary to wire the sample in order to measure the resistance of the film formation sample. For this reason, when the film is formed on the sample, the sample rotates or rotates. Since it cannot be revolved, the in-plane variation of the film thickness of the thin film becomes large. Further, since a resistance measurement pattern is required for the sample, there is a problem that the yield is lowered.

  The present invention has been made to solve the above-described problems of the prior art, and its purpose is to produce a thin film having a desired physical quantity with high accuracy and uniformity without requiring a significant modification of the apparatus. It is an object of the present invention to provide a film thickness control device for a thin film that makes it possible.

  As a result of intensive studies to solve the above problems, the present invention has found that the object can be achieved by making the structure of the film forming apparatus fair in characteristics, and has reached the present invention based on this knowledge. . That is, a thin film is formed separately from the film formation sample in the film formation chamber, a physical quantity measuring element that reads the physical quantity of the thin film during film formation, a comparison unit that compares the physical quantity with a desired physical quantity, and a comparison result And a controller for controlling the film formation conditions and / or the film formation time.

  The physical quantity may be a resistance value of the thin film being formed, an electron mobility of the thin film being formed, or an electric capacity of the thin film being formed. The physical quantity measuring element may have two or more electrodes on an insulating substrate, and the thin film being formed may be a film made of two or more elements.

  ADVANTAGE OF THE INVENTION According to this invention, in manufacture of the thin film which has a desired physical quantity, manufacture of the thin film which has a desired physical quantity uniformly in a film | membrane is enabled.

5 is a flowchart showing a film forming flow for controlling film forming conditions in the film forming apparatus according to the present invention. It is a figure which shows the structure and arrangement | positioning of an EB vapor deposition machine as an example of the film-forming apparatus by this invention. It is a figure which shows the detail of the structure of the physical quantity measuring element in this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3, taking NiCr (80:20) thin film deposition using an EB vapor deposition machine as an example.

FIG. 1 is a flowchart showing a film forming flow for controlling film forming conditions in a film forming apparatus according to the present invention.
In step S101, a film formation rate and a target film thickness are set. Here, as an example, the film formation rate is set between the film formation rate lower limit R0 and the film formation rate upper limit R1, and the film formation is performed up to y0. Using this setting content, comparison and control are performed in subsequent steps. Next, in step S102, emission of the EB power source is started and film formation is started. Next, in step S103, resistance measurement using a physical quantity measuring element is performed. Here, the thin film thickness y and the film thickness change amount are calculated from the change in resistance value, and the film formation rate R is calculated from the relationship with the elapsed time.

  In step S104, the calculated film thickness y is compared with the set film thickness y0 set in step S101. If the film thickness y has reached the set film thickness y0, the process proceeds to step S107, and the EB vapor deposition ends. If the film thickness y does not reach the set film thickness y0 in step S104, the process proceeds to step S105 and step S106, and the film formation rate R is compared.

  In step S105, if the film formation rate R has not reached the film formation rate lower limit R0 set in step S101, the process proceeds to step S108, where the EB power supply POWER is increased to increase the film formation rate R. In step S105, when the film formation rate R has reached the film formation rate lower limit R0, the process proceeds to step S106.

  In step S106, when the film formation rate R is equal to or less than the film formation rate upper limit R1, the power of the EB power source is determined to be an appropriate amount, and the process proceeds to step S109, and the power of the EB power source is maintained. In step S106, if the film formation rate R is higher than the film formation rate upper limit R1, the process proceeds to step 110, where the POWER of the EB power source is lowered and the film formation rate R is lowered. Subsequent to step S108 to step S110, the process proceeds to step S111. In step S111, film formation is performed for a predetermined time, and then the process proceeds to step 103 again.

  As described above, by performing film formation while performing POWER control of the EB power supply, film formation can be performed up to the target film thickness while maintaining the film formation rate set in step S101, and the film quality is uniform. It is possible to perform proper film formation. When more strict control is performed, the widths of R0 and R1 are narrowed, the film formation time and cycle time in step 111 are shortened, and a high-resolution measuring device may be used as the physical quantity measuring element. The film forming apparatus may use not only the EB vapor deposition machine but also MBE, PCVD, CVD, MOCVD, and sputtering.

FIG. 2 is a diagram showing the configuration and arrangement of an EB vapor deposition machine 200 as an example of a film forming apparatus according to the present invention.
As film forming conditions, the degree of vacuum of the film forming chamber 201 was 1 × 10 ⁻⁷ Torr, and the sample 204 was a GaAs substrate. The sample 204 was set in the planetary holder 208 in order to make the distance between the sample 204 and the vapor deposition source 202 constant. This planetary holder 208 revolves. The vapor deposition source 202 was a NiCr (80:20) φ30 mm tablet with a thickness of 3 mm, and was filled in a tungsten hearth.

  In FIG. 2, the EB vapor deposition machine 200 includes a physical quantity measuring element 205. When the physical quantity measuring element 205 is disposed on the holder 208, the physical quantity measuring element 205 is disposed immediately below the revolution axis that does not cause twisting of the wiring due to revolution. At this time, the surface to which the wiring cable 206 is connected is disposed so as to be opposite to the surface on which the vapor deposition source 202 is disposed. Further, when the physical quantity measuring element 205 is installed not on the holder 208 but on the inner wall of the chamber 201, for example, the physical quantity measuring element 205 has a distance between the vapor deposition source 202 and the sample 204. When the sphere is drawn around the vapor deposition source 202 at the same distance, the surface of the physical quantity measuring element 205 faces the normal line of the sphere, and the surface connecting the wiring is opposite to the vapor deposition source 202. Arrange as follows.

  As described above, the installed physical quantity measuring element 205 is connected to the physical quantity measuring device 207 outside the chamber 201 and measures the electrical characteristics of the film formed by the physical quantity measuring device 207. At this time, the physical quantity measuring device 207 is not limited to a device that measures the resistance of the thin film, but may be a device that measures other electrical characteristics such as electron mobility and capacitance. Also, the higher the resolution of the physical quantity measuring device 207, the higher the film formation controllability. Therefore, it is desirable to use a physical quantity measuring device with a high resolution.

FIG. 3 is a diagram showing details of the structure of the physical quantity measuring element in the present invention. FIG. 3a shows a top view of the physical quantity measuring element.
In FIG. 3 a, specifically, the structure of the physical quantity measuring element is a 3 cm × 5 cm, 3 mm thick glass plate 301 having an electrode 302 formed by depositing gold on both ends of 5 mm. However, these dimensions and materials are not determined, and any material having electrodes on an insulating flat plate may be used.

  FIG. 3 b shows a side view when the physical quantity measuring element and the physical quantity measuring device are connected by the wiring cable 303. In FIG. 3b, the physical quantity measuring element is connected to a wiring cable 303 for connecting to the measuring instrument at the electrode portion 302 on the back surface.

  FIG. 3 c shows a side view of another embodiment in which the physical quantity measuring element and the physical quantity measuring device are connected by the wiring cable 303. In FIG. 3c, the electrode of the physical quantity measuring element has a connector shape 306, and a socket 305 electrically connected to the physical quantity measuring instrument is provided on the chamber inner wall 304. By adopting a structure in which the electrode connector 306 of the physical quantity measuring element can be attached to the socket portion 305 on the inner wall of the chamber, the physical quantity measuring element can be installed with good reproducibility, and can be easily removed and easily used.

  FIG. 3d is a side view showing a state in which a thin film is formed on the physical quantity measuring element after film formation. The physical quantity measuring element should be disposable, and it is desirable to prepare a new one for each film forming batch. For example, when forming a film by PCVD, the physical quantity measuring element used was formed on the physical quantity measuring element. The thin film 307 may be plasma etched by the same PCVD, and the thin film 307 may be peeled off. In this case, it is not necessary to replace the physical quantity measuring element for each film forming batch. In this case, the film forming apparatus and the apparatus for removing the thin film are not necessarily the same, and may be different apparatuses.

  Further, the number of electrodes and the arrangement of the physical quantity measuring element can be improved to a multi-terminal structure such as four terminals. In this case, film formation control with higher accuracy such as four-terminal measurement can be performed. Furthermore, by providing a mechanism for generating a magnetic field in the electrode in the vicinity of the physical quantity measuring element, it is possible to perform hole measurement, fan der paw measurement, and perform film formation control using measurement parameters that can be confirmed by this. Is also possible.

DESCRIPTION OF SYMBOLS 201 Deposition chamber 202 Deposition hearth 203 Flying metal particle 204 GaAs wafer 205 Physical quantity measuring element 206 Wiring cable 207 Physical quantity measuring device 301 Glass plate 302 Gold electrode 303 Wiring cable 304 Inner wall 305 Socket 306 Connector 307 Thin film formed

Claims (6)

A physical quantity measuring element for measuring a physical quantity of a thin film during film formation;
A comparison unit for comparing the physical quantity of the thin film with a desired physical quantity;
A film forming apparatus comprising: a control unit that controls film forming conditions and / or film forming time based on a comparison result of the comparison unit.   The film forming apparatus according to claim 1, wherein the physical quantity is a resistance value of a thin film during film formation.   The film forming apparatus according to claim 1, wherein the physical quantity is an electron mobility of a thin film during film formation.   The film forming apparatus according to claim 1, wherein the physical quantity is an electric capacity of a thin film during film formation.   The film forming apparatus according to claim 1, wherein the physical quantity measuring element has two or more electrodes on an insulating substrate.   The film forming apparatus according to claim 1, wherein the thin film being formed is a film made of two or more elements.

Images