JP2003163211A - Film forming method for low dielectric constant, film forming device and electronic device using the film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film forming device capable of forming a boron, carbon and nitrogen thin film with a low dielectric constant. <P>SOLUTION: The film forming device has a process for generating plasma in a film forming chamber, reacting nitrogen atoms with boron and carbon in the film forming chamber and being irradiated with light after the boron, carbon and nitrogen film is formed on a substrate. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method for forming a film containing boron carbon nitrogen and an electronic device using the same.

[0002]

2. Description of the Related Art Up to now, in a semiconductor integrated circuit, plasma CVD (Chemi
A SiO ₂ or SiN film formed by the cal vapor deposition method has been used. However, with the high integration of transistors, wiring delay occurs due to capacitance between wirings, which has been a problem as a factor that impedes the speeding up of switching operation of elements. Further, improvement of wiring delay in a liquid crystal display panel is also desired. In order to solve this, it is necessary to reduce the dielectric constant of the wiring interlayer insulating thin film, and a new material having a low dielectric constant is required for the interlayer insulating film.
Under such circumstances, attention has been paid to organic materials and porous materials,
It is possible to realize an extremely low dielectric constant (relative permittivity κ to 2.5 or less), but there is a problem in terms of chemical and mechanical resistance and thermal conductivity. Further, in recent years, an extremely low dielectric constant of 2.2 has been achieved in a boron nitride thin film, but it is known that there is a problem in moisture absorption resistance.

[0003]

Under such circumstances, a boron-carbon-nitrogen thin film having excellent heat resistance and moisture absorption resistance and an extremely low dielectric constant is drawing attention, but a film formation technique by the plasma CVD method has been established. At present, there is no such thing, and further reduction of dielectric constant is desired. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a film forming method capable of forming a low dielectric constant boron carbon nitrogen thin film.

[0004]

A film forming method of the present invention for solving the above problems is to generate plasma in a film forming chamber,
The method is characterized by including a step of reacting nitrogen atoms with boron and carbon in a film forming chamber to form a boron-carbon-nitrogen film on a substrate, and then performing light irradiation. The same effect of lowering the dielectric constant can be obtained whether the light irradiation step is performed in the film forming chamber or in any part of the manufacturing step after the film formation.

Further, the film forming method of the present invention for achieving the above object is characterized in that after film formation, irradiation of ultraviolet light is carried out for several minutes using a mercury lamp. Optimal conditions can be obtained by the irradiation light intensity and irradiation time.

Further, either a xenon lamp or a deuterium lamp can be used as the light source.

Further, in the film forming method of the present invention for achieving the above object, after the film formation, infrared rays are irradiated using an infrared lamp to raise the temperature of the thin film. This holding temperature is 250 ° C to 5
It is preferably set to 50 ° C. 350 ° C-450 ° C
Is more preferable, and 400 ° C. to 450 ° C. is further preferable.
Below 250 ° C, the effect of lowering the dielectric constant is not noticeable,
When it exceeds 550 ° C, the dielectric constant increases.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The film forming method and film forming apparatus of the present invention will be described in detail below with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic side view showing a film forming apparatus for carrying out the film forming method of the first embodiment of the present invention.
An inductively coupled plasma generation unit 2 is provided in the cylindrical container 1, and is connected to a high frequency power source 4 via a matching unit 3.
The high frequency power supply 4 can supply high frequency power of 1 kw to 10 kw. Nitrogen gas is supplied from the nitrogen gas introduction unit 5 to generate plasma 50. A substrate 60 is placed on the substrate holder 6, and a heater 7 is mounted inside the substrate holder 6. The temperature of the substrate 60 is changed from room temperature to 6 by the heater 7.
It can be set in the range of 00 ° C. The cylindrical container 1 is provided with an introduction part 8 for introducing a boron chloride gas using hydrogen gas as a carrier.

An introducing portion 9 for introducing a hydrocarbon gas into the cylindrical container 1 is provided. An exhaust unit 10 is mounted below the substrate holding unit 6.

Regarding the supply flow rate range of each gas, the flow rate ratio of nitrogen gas and boron chloride (nitrogen gas / boron chloride)
Is 0.1 to 10.0, and the flow rate ratio of hydrocarbon gas to boron chloride (hydrocarbon gas / boron chloride) is 0.01 to
5.0, the flow rate ratio of hydrogen gas and boron chloride (hydrogen gas / boron chloride) can be set to be 0.05 to 5.0.

The p-type silicon substrate 60 is placed on the substrate holding portion 6, and the inside of the container 1 is evacuated to 1 × 10 ⁻⁶ Torr. Set the substrate temperature to 300 ° C. Then, nitrogen gas is introduced into the cylindrical container 1 from the introduction part 5. High frequency power (1
Plasma 50 is generated by supplying 1 kW of 3.56 MHz. Then, using hydrogen gas as a carrier gas, boron chloride is transported into the container 1. Further, methane gas is supplied into the container 1. The gas pressure in the container 1 is 0.6T
The boron nitride carbon film 61 is synthesized by adjusting to orr.
Boron chloride and methane gas decomposes boron chloride and methane gas by nitrogen plasma instead of plasma, generates boron atoms and carbon atoms, and reacts with nitrogen atoms to synthesize boron nitride carbon film 61. Chlorine combines with hydrogen atoms to become hydrogen chloride, and the incorporation of chlorine atoms into the film is suppressed. After film formation, the film surface is irradiated with light using a mercury lamp. Irradiate for 4 minutes in room temperature atmosphere.

A boron nitride carbon film 61 having a thickness of 100 nm is deposited on a p-type silicon substrate 60 to form a boron nitride carbon film 61.
After depositing Au on the electrode and forming the electrode, the capacitance-voltage characteristics were measured, and the capacitance value of the metal / boron carbon nitride film / accumulation region of the P-type silicon structure and the thickness of the boron nitride carbon film 61 were used. The relative permittivity was evaluated. In the film having a relative dielectric constant of 2.8 to 3.0 before the light irradiation, a low relative dielectric constant of 2.2 to 2.4 was obtained after the light irradiation for 4 minutes.

The relationship between the relative permittivity of the film before and after light irradiation and the time of irradiation is examined and shown in FIG. When light irradiation was performed using a mercury lamp (800 mmW / cm ² , distance to lens: 15 cm, in air), a decrease in relative permittivity was observed in an irradiation time of 3 minutes to 6 minutes.

Although nitrogen gas, boron chloride and methane gas are used as the material gas in this embodiment, ammonia gas can also be used as the nitrogen material. Further, diborane gas can be used instead of boron chloride. Further, as the carbon supply, it is possible to use hydrocarbon gas such as ethane gas or acetylene gas other than methane gas, and organic compounds of boron and nitrogen as well as trimethylboron. Also,
Although a mercury lamp was used as a light source for light irradiation, a xenon lamp or a deuterium lamp can also be used.

(Embodiment 2) A second embodiment of the present invention uses the same film forming apparatus as that of the first embodiment. An inductively coupled plasma generation unit 2 is provided in the cylindrical container 1, and is connected to a high frequency power source 4 via a matching unit 3. High frequency power source 4 is 1kW
A high frequency power of 10 kW can be supplied. Nitrogen gas is supplied from the nitrogen gas introduction unit 5 to generate plasma 50. The substrate 60 is placed on the substrate holder 6, and the substrate holder 6
A heater 7 is mounted inside. The heater 7 allows the temperature of the substrate 60 to be set within the range of room temperature to 600 ° C. The cylindrical container 1 is provided with an introduction part 8 for introducing a boron chloride gas using hydrogen gas as a carrier. Further, an introduction part 9 for introducing a hydrocarbon-based gas into the cylindrical container 1 is provided. An exhaust unit 10 is mounted below the substrate holding unit 6.

Regarding the supply flow rate range of each gas, the flow rate ratio of nitrogen gas and boron chloride (nitrogen gas / boron chloride)
Is 0.1 to 10.0, and the flow rate ratio of hydrocarbon gas to boron chloride (hydrocarbon gas / boron chloride) is 0.01 to
5.0, the flow rate ratio of hydrogen gas and boron chloride (hydrogen gas / boron chloride) can be set to be 0.05 to 5.0.

The p-type silicon substrate 60 is placed on the substrate holder 6, and the inside of the container 1 is evacuated to 1 × 10 ⁻⁶ Torr. Set the substrate temperature to 300 ° C. Then, nitrogen gas is introduced into the cylindrical container 1 from the introduction part 5. High frequency power (1
Plasma 50 is generated by supplying 1 kW of 3.56 MHz. Then, using hydrogen gas as a carrier gas, boron chloride is transported into the container 1. Further, methane gas is supplied into the container 1. The gas pressure in the container 1 is 0.6T
The boron nitride carbon film 61 is synthesized by adjusting to orr.
Boron chloride and methane gas decomposes boron chloride and methane gas by nitrogen plasma instead of plasma, generates boron atoms and carbon atoms, and reacts with nitrogen atoms to synthesize boron nitride carbon film 61.

Chlorine combines with hydrogen atoms to become hydrogen chloride, and the incorporation of chlorine atoms into the film is suppressed. After forming the film, the temperature of the formed sample was raised by heating with an infrared lamp and 4
Hold at 00 ° C for 10 minutes.

A boron nitride carbon film 61 having a thickness of 100 nm is deposited on a p-type silicon substrate 60 to form a boron nitride carbon film 61.
After Au was vapor-deposited thereon to form an electrode, the capacitance-voltage characteristic was measured, and the capacitance value of the metal / boron carbon nitride film / accumulation region of the p-type silicon structure and the thickness of the boron nitride carbon film 61 were used. The relative permittivity was evaluated. A low relative dielectric constant of 2.2 to 2.4 was obtained after heat treatment at a holding temperature of 400 ° C. in a film having a relative dielectric constant of 2.8 to 3.0 before temperature increase. Further, the ratio between the relative permittivity of the film subjected to the heat treatment while changing the temperature and the relative permittivity evaluated without raising the temperature of the film produced in the same manner was examined and shown in FIG. 3 as a function of the heat treatment temperature. The holding time was 10 minutes. At the holding temperature of 250 to 550 ° C., a decrease in the relative dielectric constant was observed after the temperature was maintained.

An example of application of the boron nitride carbon film formed by the film forming method of the present invention to an integrated circuit will be described with reference to FIG.
In order to make the wiring 502 have a multi-layered structure by increasing the integration of the transistor 501, it is necessary to use an interlayer insulating thin film 503 having a low dielectric constant between the wirings, and the boron nitride carbon film formed by the present film forming method. Membranes can be used.

Further, when an organic thin film or a porous film is used as the interlayer insulating thin film 503, mechanical strength and hygroscopicity become problems, but as shown in FIG. 7, the film is formed by the film forming method of the present invention. The boron nitride carbon film described above can be used as a protective film 504 of an organic thin film or a porous film. By combining such an organic thin film or a porous film and a boron nitride carbon film, a dielectric constant lower than that of a boron nitride carbon film single layer is achieved,
An effective relative permittivity of about 1.9 was obtained.

(Embodiment 3) FIG. 4 is a schematic side view showing a film forming apparatus for carrying out the film forming method of the third embodiment of the present invention.
An inductively coupled plasma generating unit 2 is provided inside the cylindrical container, and is connected to a high frequency power source 4 via a matching unit 3.
The high frequency power supply 4 can supply high frequency power of 1 kw to 10 kw. Nitrogen gas is supplied from the nitrogen gas introduction unit 5 to generate plasma 50. A substrate 60 is placed on the substrate holder 6, and a heater 7 is mounted inside the substrate holder 6. The temperature of the substrate 60 is changed from room temperature to 6 by the heater 7.
It can be set in the range of 00 ° C. Further, a window is provided above the substrate holding portion of the film forming chamber so that the sample surface can be irradiated with light from a mercury lamp. The substrate holder 6 can be moved toward the window during light irradiation by the mercury lamp. The cylindrical container 1 is provided with an introduction part 8 for introducing a boron chloride gas using hydrogen gas as a carrier. Further, an introduction part 9 for introducing a hydrocarbon-based gas into the cylindrical container 1 is provided. An exhaust unit 10 is mounted below the substrate holding unit 6.

Regarding the supply flow rate range of each gas, the flow rate ratio of nitrogen gas and boron chloride (nitrogen gas / boron chloride)
Is 0.1 to 10.0, and the flow rate ratio of hydrocarbon gas to boron chloride (hydrocarbon gas / boron chloride) is 0.01 to
5.0, the flow rate ratio of hydrogen gas and boron chloride (hydrogen gas / boron chloride) can be set to be 0.05 to 5.0.

The p-type silicon substrate 60 is placed on the substrate holder 6, and the inside of the container 1 is evacuated to 1 × 10 ⁻⁶ Torr. Set the substrate temperature to 300 ° C. Then, nitrogen gas is introduced into the cylindrical container 1 from the introduction part 5. High frequency power (1
Plasma 50 is generated by supplying 1 kW of 3.56 MHz. Then, using hydrogen gas as a carrier gas, boron chloride is transported into the container 1. Further, methane gas is supplied into the container 1. The gas pressure in the container 1 is 0.6T
The boron nitride carbon film 61 is synthesized by adjusting to orr.
Boron chloride and methane gas are not made into plasma but decompose nitrogen chloride and methane gas by nitrogen plasma to generate boron atoms and carbon atoms and react with nitrogen atoms to synthesize boron nitride carbon film 61.

Chlorine combines with hydrogen atoms to form hydrogen chloride, and the incorporation of chlorine atoms into the film is suppressed. After film formation, a mercury lamp (800 mmW / c
Light irradiation was performed for 3 to 6 minutes by using m ² and a distance from the lens of 15 cm in the atmosphere.

A boron nitride carbon film 61 having a thickness of 100 nm is deposited on a p-type silicon substrate 60 to form a boron nitride carbon film 61.
After Au was vapor-deposited thereon to form an electrode, the capacitance-voltage characteristic was measured, and the capacitance value of the metal / boron carbon nitride film / accumulation region of the p-type silicon structure and the thickness of the boron carbon nitride film 61 were used. When the relative permittivity was evaluated, a suitable value having a low relative permittivity was obtained.

(Embodiment 4) FIG. 5 is a schematic side view showing a film forming apparatus for carrying out the film forming method of the fourth embodiment of the present invention.
An inductively coupled plasma generation unit 2 is provided in the cylindrical container 1, and is connected to a high frequency power source 4 via a matching unit 3.
The high frequency power supply 4 can supply high frequency power of 1 kw to 10 kw. Nitrogen gas is supplied from the nitrogen gas introduction unit 5 to generate plasma 50. A substrate 60 is placed on the substrate holder 6, and a heater 7 is mounted inside the substrate holder 6. The temperature of the substrate 60 is changed from room temperature to 6 by the heater 7.
It can be set in the range of 00 ° C. The cylindrical container 1 is provided with an introduction part 8 for introducing a boron chloride gas using hydrogen gas as a carrier. Further, an introduction part 9 for introducing a hydrocarbon-based gas into the cylindrical container 1 is provided. An exhaust unit 10 is mounted below the substrate holding unit 6. An annealing chamber is attached to hold the temperature of the film through the film forming chamber and the gate valve, and light can be emitted from a mercury lamp.

Regarding the supply flow rate range of each gas, the flow rate ratio of nitrogen gas and boron chloride (nitrogen gas / boron chloride)
Is 0.1 to 10.0, and the flow rate ratio of hydrocarbon gas to boron chloride (hydrocarbon gas / boron chloride) is 0.01 to
5.0, the flow rate ratio of hydrogen gas and boron chloride (hydrogen gas / boron chloride) can be set to be 0.05 to 5.0.

The p-type silicon substrate 60 is placed on the substrate holding portion 6, and the inside of the container 1 is evacuated to 1 × 10 ⁻⁶ Torr. Set the substrate temperature to 300 ° C. Then, nitrogen gas is introduced into the cylindrical container 1 from the introduction part 5. High frequency power (1
Plasma 50 is generated by supplying 1 kW of 3.56 MHz. Then, using hydrogen gas as a carrier gas, boron chloride is transported into the container 1. Further, methane gas is supplied into the container 1. The gas pressure in the container 1 is 0.6T
The boron nitride carbon film 61 is synthesized by adjusting to orr.
Boron chloride and methane gas are not made into plasma but decompose nitrogen chloride and methane gas by nitrogen plasma to generate boron atoms and carbon atoms and react with nitrogen atoms to synthesize boron nitride carbon film 61.

Chlorine combines with hydrogen atoms to form hydrogen chloride, and the incorporation of chlorine atoms into the film is suppressed. After the film formation, the substrate temperature is set to 400 ° C. by the heater 7 mounted in the substrate holding unit 6, and the substrate is held for 10 minutes.

A boron nitride carbon film 61 having a thickness of 100 nm is deposited on the p-type silicon substrate 60 to form a boron nitride carbon film 61.
After Au was vapor-deposited thereon to form an electrode, the capacitance-voltage characteristic was measured, and the capacitance value of the metal / boron carbon nitride film / accumulation region of the p-type silicon structure and the thickness of the boron carbon nitride film 61 were used. When the relative permittivity was evaluated, a suitable value having a low relative permittivity was obtained.

[0033]

Effects of the Invention The film forming method of the present invention has mechanical and chemical stability, moisture absorption resistance, and high thermal conductivity by irradiating a boron nitride carbon film produced by a plasma vapor phase synthesis method with light. A boron nitride carbon film having a low dielectric constant can be formed. A film forming apparatus for performing plasma vapor phase synthesis is provided with a nitrogen gas introducing unit, a plasma generating unit and a substrate holding unit below the cylindrical gas introducing unit, and a boron chloride and carbon supply source between the nitrogen introducing unit and the substrate holding unit. A means for introducing hydrocarbons and organic materials as described above is provided, and nitrogen plasma is allowed to react with boron and carbon atoms to form a boron nitride carbon film on the substrate, and then a light irradiation step is provided to the film formation sample. As a result, a boron nitride carbon film having moisture absorption resistance, high thermal conductivity, and low dielectric constant can be formed at high speed.

The boron carbon nitride film according to the present invention can be used as a wiring interlayer insulating thin film or a protective film of an integrated circuit.

The boron nitride carbon film according to the present invention can be used as a wiring interlayer insulating thin film or a protective film of an integrated circuit. This film is a compound semiconductor (GaAs, InP)
Stray capacitance can be reduced by using it as a protective film on the semiconductor surface between the source and gate or between the gate and drain of a field effect transistor (FET) or a bipolar transistor aiming at high frequency operation made of a GaN system, a GaN system, etc. The frequency characteristic can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a film forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a graph showing the ratio of relative permittivity before and after light irradiation with respect to light irradiation time.

FIG. 3 is a graph showing a ratio of a relative dielectric constant before and after heat treatment with respect to a heat treatment temperature.

FIG. 4 is a sectional view showing a film forming apparatus according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a film forming apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of an integrated circuit using a boron nitride carbon film formed by a film forming method according to an example of the present invention.

FIG. 7 is a schematic cross-sectional view of an integrated circuit using a boron nitride carbon film formed by a film forming method according to an example of the present invention.

[Explanation of symbols]

1 ... Cylindrical container 2 ... Inductively coupled plasma generator 3 ... Matching device 4. High frequency power supply 5. Nitrogen gas introduction section 6 ... Board holding part 7 ... Heater 8, 9 ... Introduction section 10 ... Exhaust section 50 ... Plasma 60 ... Board 61 .. Boron nitride carbon film 501 ... Transistor 502..Wiring 503 .. Interlayer insulator thin film 504 ... Protective film

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaki Kusuhara             4-2-1 Nihonbashi Muromachi, Chuo-ku, Tokyo             Watanabe Shokai Co., Ltd. (72) Inventor Yu Umeda             4-2-1 Nihonbashi Muromachi, Chuo-ku, Tokyo             Watanabe Shokai Co., Ltd. F-term (reference) 4K030 AA03 AA09 AA13 AA17 AA18                       BA26 BA27 BA49 CA04 FA04                       FA15                 5F058 BA07 BC20 BF07 BF22 BF26                       BF30 BJ02

Claims (7)

[Claims] 1. A method for forming a low dielectric constant film, which comprises the step of irradiating light after forming a film containing boron carbon nitrogen atoms. 2. A method for forming a low dielectric constant film, wherein any one of a mercury lamp, a xenon lamp and a deuterium lamp is used as a light source of irradiation light. 3. A method for forming a low dielectric constant film, wherein an infrared lamp is used as a light source of irradiation light. 4. A semiconductor device, wherein the film produced by the method according to claim 1 is used as a wiring interlayer film. 5. A semiconductor device using the film produced by the method according to claim 1 as a protective film. 6. An information processing / communication system comprising the device according to claim 4 or 5. 7. A semiconductor surface formed by a method according to claim 1, wherein a source-gate and / or a gate-drain of a field effect transistor or a bipolar transistor made of a compound semiconductor is used as a semiconductor surface. A semiconductor device comprising a protective film.