JP2795052B2 - Method of forming boron element-containing film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boron element-containing film formed on a predetermined substrate for forming a boron element-containing film used in various thin film device fields such as semiconductor devices and fields requiring wear resistance. To a method of forming

[0002]

2. Description of the Related Art In forming a boron element-containing film on a predetermined substrate for forming various thin film devices such as a semiconductor device or forming a wear-resistant film on a mechanical material, etc.
Vacuum deposition or sputtering of boron (B) or a substance containing boron (B) element is often used.

In such film formation, a film formation monitor using a quartz oscillator is frequently used for film formation control (thickness control, substance evaporation amount control, film formation speed control, etc.).
As shown in FIG. 3, a film formation monitor using a quartz oscillator
Usually, electrodes 72 made of gold (Au) or silver (Ag) are provided on both surfaces of a quartz oscillator 71 having a thickness t cut by AT (cut in the direction of the smallest thermal expansion coefficient), and an oscillator 73 is connected to the electrodes. It has a basic structure.

When a high-frequency voltage is applied to the electrodes 72 on both surfaces of the crystal unit 71, a thickness shear vibration propagates in the thickness direction. The frequency of the voltage to be applied is
When the frequency reaches a natural frequency fq determined by the thickness t and the elastic constant, a standing wave vibration of the slip of the thickness is generated. At this time, a relationship of fq = v / 2t (v: propagation speed of a standing wave) holds.

If the thickness of the vibrator 71 changes by Δt, the natural frequency decreases by Δf and Δf / f
q = −Δt / t. Density on the surface [rho, and film is deposited with a thickness of d, when the thickness is Δt change, Δf / fq = -ρd / ρ q t (ρ q: Density of Crystal)
Becomes If the frequency becomes f due to the deposition of the film, Δf = f
-Fq next, the frequency after the change becomes f = fq (1-ρd / ρ q t).

Thus, the frequency of the vibrator 71 is
It decreases in proportion to the film thickness of the film deposited on the substrate, and can be used as a monitor for the film thickness at the time of film formation, the amount of substance evaporated, the film formation speed, and the like. The monitor of film thickness and the like using this crystal resonator is simpler in structure and operation than the monitor of film thickness and the like by an optical method, and has sensitivity equal to that of the optical method. Widely used.

[0007]

The electrode 72 formed on the quartz oscillator 71 in FIG. 3 is generally formed of Au or Ag having long-term stability as described above. In the film formation control of the boron element-containing film, the film formation control is performed by forming the boron element-containing film on the electrode. However, since the film has poor adhesion to the Au electrode or the Ag electrode, the film formation is controlled. The film tends to be partially peeled off from the electrode during the operation, and as a result, the frequency of the monitored vibrator 71 varies or disturbs, and the frequency becomes unstable. It can even be possible.

Further, when the film on the electrode peels off,
Since it is difficult to control the film formation, the quartz oscillator must be replaced. During the replacement, the film cannot be formed, resulting in a remarkably low productivity. It is conceivable to replace the electrode 72 with a metal having good adhesion to the boron element-containing film, for example, titanium (Ti). However, in this case, long-term stability cannot be ensured due to oxidation of the electrode and the like. This causes a problem that storage and handling of the vibrator becomes difficult.

Accordingly, the present invention is a method for forming a boron element-containing film on a substrate by a vacuum evaporation method and / or a sputtering method, wherein the film formation of the boron element-containing film can be controlled simply, accurately and inexpensively. Another object of the present invention is to provide a method with good film productivity.

[0010]

According to the present invention, there is provided a method for forming a boron element-containing film on a substrate by a vacuum evaporation method and / or a sputtering method according to the above object. Is performed using a film-forming monitor using a quartz oscillator, wherein before the formation of the boron-element containing film on the substrate, silicon is attached to the surface of the electrode on the quartz oscillator in the film-forming monitor where the boron element-containing film is attached. Another object of the present invention is to provide a method for forming a boron element-containing film, which comprises forming a titanium film and subsequently forming a boron element-containing film on the substrate.

[0011] A silicon (Si) film or a titanium (T
i) The film is preferably formed by, for example, vacuum deposition or sputtering, and is preferably performed immediately before the start of the formation of the boron (B) element-containing film on the substrate. This is because the film is used for a film formation monitor while the Si film or the Ti film formed on the electrode is still stable. The formation of the film on these electrodes may be performed in a vacuum vessel different from the vacuum vessel for forming the boron (B) element-containing film on the substrate, or in the same vacuum vessel.

[0012]

According to the method of the present invention, boron (B) is deposited on a substrate.
Prior to the formation of the element-containing film, a silicon or titanium film is formed on the surface of the electrode on the crystal oscillator of the film formation monitor using the crystal oscillator used for controlling the film formation, where the boron element-containing film is attached. Thereafter, formation of a boron (B) element-containing film on the substrate is started.

The boron or a boron element-containing substance evaporated by the vacuum evaporation method and / or the sputtering method is deposited on the electrode surface on the quartz oscillator with good adhesion. Therefore, a change in the vibration frequency of the vibrator according to the deposition can be accurately monitored, and one or two or more of the film thickness on the substrate, the evaporation amount of boron or a boron element-containing substance, and the film formation rate are determined. Since it is detected with high accuracy and the number of times of replacing the vibrator due to uncontrollability is reduced, a film having a designed function can be obtained with high productivity.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows a schematic configuration of an example of a film forming apparatus used for carrying out the method of the present invention. This apparatus includes a vacuum vessel 1, in which a substance evaporation source 2 by heating using an electron beam (EB), a substrate support holder 3 above the source, and a quartz oscillator arranged at a predetermined position. The sensor unit 4 (see FIG. 2) of the film monitor 40 is provided. An evaporation material 2 a is contained in the evaporation source 2. The sensor unit 4
The structure shown in FIG. 3 is substantially the same as that shown in FIG. 3. Electrodes 42 made of gold (Au) are provided on both sides of a quartz oscillator 41 (resonant frequency 5 MHz) which is AT-cut. An AC electric field is applied. An oscillator 43 is connected to the electrode 42.

During the film forming process, the inside of the vacuum vessel 1 is maintained at a predetermined film forming vacuum degree by the exhaust device 5. (Example 1) First, the base 6 is supported by the base holder 3,
Next, a Si (purity 5N) pellet is placed in the evaporation source 2 and heated using an electron beam to form a Si film 44 (see FIG. 2) on the Au electrode 42 of the quartz oscillator 41 of the sensor unit 4.
It was formed by vacuum evaporation of 0 nm.

Subsequently, boron (B) pellets (purity: 99.7%) are placed in the same evaporation source 2, which is heated by using an electron beam, and is heated on the substrate 6 at an evaporation rate of 0.3 nm / s. , And also on the electrode surface of the quartz oscillator (more specifically, the Si film 44 thereover). Finally, a 3 μm-thick boron film was formed on the substrate 6. During this time, the amount of boron evaporated is controlled stably by the film-forming monitor 40 using the quartz oscillator, and the variation and the disturbance of the frequency of the quartz oscillator 41 of the sensor unit 4 are not observed, and the accurate control is performed. A film could be formed. (Embodiment 2) First, the base 6 is supported by the base holder 3,
Next, a Ti (purity 5N) pellet is placed in the evaporation source 2 and heated using an electron beam, and a Ti film 45 (see FIG. 2) is formed on the Au electrode 42 of the quartz oscillator 41 of the sensor unit 4.
It was formed by vacuum evaporation of 0 nm.

Subsequently, boron (B) pellets (purity: 99.7%) are placed in the same evaporation source 2, which is heated by using an electron beam, and is heated on the substrate 6 at an evaporation rate of 0.3 nm / s. , And also on the electrode surface of the quartz oscillator (more specifically, the Ti film there). Finally, a 3 μm-thick boron film was formed on the substrate 6. During this time, the amount of boron evaporation is controlled stably by the film forming monitor 40 using a quartz oscillator, and the sensor unit 4 is controlled.
No variation or disturbance in the frequency of the quartz oscillator was observed, and the film could be formed under accurate control. (Comparative Example 1) A boron (B) pellet (purity 99.7%) was immediately placed in the evaporation source 2 without forming a Si film or a Ti film on the quartz crystal vibrator electrode 42 of the sensor unit 4, and this was charged with an electron beam. To start the formation of the boron film on the substrate 6.

When the thickness of the boron film on the substrate became 1.2 μm, the frequency of the quartz oscillator 41 became unstable, and it became impossible to control the amount of boron evaporated. As can be seen from the above description, the embodiment of the present invention has the following advantages. (1) Since, for example, an Au or Ag electrode having good long-term stability is formed on a quartz oscillator, storage and handling of the quartz oscillator having the electrodes formed thereon are easy. (2) After a Si film or a Ti film is formed on an Au or Ag electrode, a boron film is formed on the electrode, thereby making it difficult for the boron film to peel off. -Accurate monitoring can be performed, and as a result, control of the amount of boron evaporation, control of the film thickness, and the like can be performed accurately. Therefore, there is no variation in the characteristics of the obtained film, and a film having desired characteristics can be obtained. (3) In addition, since the frequency change of the crystal unit can be monitored stably and accurately for the above-mentioned reasons, productivity such as interruption of the film forming operation due to instability of the frequency and replacement operation of the crystal unit can be reduced. The problem of degradation is solved. (4) Even if a film forming monitor using a quartz oscillator having an inexpensive and simple mechanism is used, it is possible to accurately control the evaporation amount of boron for the above-described reason. Therefore, the structure of the film deposition monitor is simplified and the cost is reduced as compared with the technique of optically controlling the amount of boron evaporation.

[0019]

As described above, according to the present invention,
A method for forming a boron element-containing film on a substrate by a vacuum evaporation method and / or a sputtering method, in which the film formation control of the boron element-containing film can be performed easily, accurately, and at low cost.
It is possible to provide a method with good film productivity.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a film forming apparatus used for carrying out a method of the present invention.

FIG. 2 is a configuration diagram of a main part of a film formation monitor using a quartz oscillator used in the apparatus of FIG.

FIG. 3 is a configuration diagram of a main part of a film formation monitor using a conventional quartz oscillator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Material evaporation source 2a Evaporation substance 3 Substrate holder 40 Deposition monitor 4 Sensor part of monitor 40 41 Crystal oscillator 42 Au electrode 43 Oscillator 44 Si film 45 Ti film 5 Exhaust device 6 Substrate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-131708 (JP, A) JP-A-5-320902 (JP, A) JP-A-61-44933 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) C23C 14 / 54,14 / 34,14 / 24,14 / 06,14 / 14

Claims (1)

(57) [Claims] 1. A method of forming a boron element-containing film on a substrate by a vacuum deposition method and / or a sputtering method, wherein the film formation of the boron element-containing film is controlled by a film formation monitor using a quartz oscillator. In the method performed using, before the formation of the boron element-containing film on the substrate, a silicon or titanium film is formed on the boron element-containing film attachment surface of the electrode on the quartz oscillator in the film formation monitor, and thereafter, A method for forming a boron element-containing film, comprising forming a boron element-containing film on the substrate.