JPH01206629A - Formation of thin film - Google Patents

Abstract

PURPOSE:To enable a thin film to be formed on a substrate at high speed and low temperature by a method wherein a compound containing at least one atom out of the atoms comprising a thin film is jetted from a nozzle to be adiabatically expanded and then carried to the substrate. CONSTITUTION:A compound containing at least one atom out of the atoms comprising a thin film is jetted at supersonic rate from a nozzle 12 to be carried to a substrate 13 at low temperature whereon a thin film is to be formed at high speed. The thin film to be formed on the substrate 13 is either one out of insulating film, a conductive thin film and a semiconductor thin film. The compound blown out of the nozzle 12 at a supersonic speed is adiabatically expanded to be cooled down normally while the relieving process of this cooling down gas is accelerated in the order of a rotational mode, a translational mode and an oscillating mode. Therefore, the compound hitting and absorbing the surface of the substrate 13 before the oscillating mode of the gas is relieved is normally unstable to be decomposed spontaneously at once for shifting to the stable energy state consequently the compound is provided with the sufficient reactivity. Through these procedures, the substrate temperature can be lowered enabling an insulating film to be formed on the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for forming thin films such as insulating films, conductive thin films, and semiconductor thin films used in the manufacture of semiconductor devices.

(Prior Art) High integration of semiconductor devices is brought about by miniaturization of constituent elements. For example, IMDRAM, 256KS
RAM j is made with design standards of ±1 to 1.2 μm, and devices are being made with even finer submicron design standards.

In order to create small, high-speed devices, it is necessary to create devices with shallow junctions, narrow wiring widths, and small wiring pitches. To preserve these characteristics, process temperatures tend to be low. This is to prevent the redistribution of the shallowly formed impurity profile and protect the A1/Si wiring, which has low resistance to heat.

However, process temperatures are still high. This is because conventionally, thermal energy is mainly used to form thin films.

Next, the disadvantages of high process temperatures will be explained using an example of a process for forming wiring. There are two reasons why AI/Si wiring breaks: electromigration and stress migration. First, the causes of electromigration include reduced wiring width, increased electrical stress, and uneven film thickness at the bottom of the step. On the other hand, thermal stress is said to be the most important cause of stress migration. For example, after forming the -th layer A1/Si wiring, a plasma 5in2 film is usually formed as an interlayer insulating film, but the deposition temperature at this time exceeds 200°C. When the temperature is returned to room temperature, the thermal stress proportional to the temperature difference between the deposition temperature and room temperature is
- It is said that the Al-3i film will be disconnected due to the damage to the Si film.

Methods that can form an insulating film at a lower temperature than plasma CVD include bias ECR plasma CVD and photoCVD. The bias ECR plasma CVD method is
It has not yet been put into practical use because of the damage it causes to the substrate and the slow deposition rate.

Further, although the possibility of photo-CVD has been pointed out, it is still a thin film forming method in the research stage in terms of film quality and productivity.

(Problems to be Solved by the Invention) As mentioned above, in the conventional technology, there is a serious problem in that the process temperature for forming wiring of a device that is fine and suitable for high speed is high. To solve this problem, plasma CV
Although there is a method mentioned above that forms an insulating film at a lower temperature than the D method, there are many problems that need to be solved, such as damage to the substrate and slow deposition rate.

In view of the above-mentioned prior art, the present invention provides an improved method for forming a thin film to solve the problem.

[Structure of the invention]

(Means for Solving the Problems) A method for forming a thin film according to the present invention includes jetting a compound containing at least one of the atoms constituting the thin film from a nozzle at supersonic speed, transporting it onto a low-temperature substrate, and It is characterized by forming a thin film at high speed on
The thin film formed on the substrate is any one of an insulating film, a conductive thin film, and a semiconductor thin film.

(Function) The compound blown out from the nozzle at supersonic speed expands adiabatically and is generally cooled. The relaxation process of the gas to be cooled at this time is faster in the order of rotational mode, translational mode, and vibrational mode. For this reason, the gas collides with the substrate surface before the vibration mode of the gas relaxes, and the adsorbed compounds are generally unstable, and the next moment they spontaneously decompose or try to transition to a stable energy state. Therefore, it is highly reactive. This process is relatively insensitive to substrate temperature, and the three modes of gas temperature govern the phenomenon. This phenomenon is utilized to lower the substrate temperature and form an insulating film on the substrate.

(Example) Hereinafter, one example of the method for forming a thin film of the present invention will be described.

Prior to explaining the thin film forming method, the manufacturing apparatus will first be explained with reference to FIG.

A gas reservoir 2 is installed in the upper part of the reaction chamber 1.

A pipe 3 for exhausting the gas reservoir is connected to the gas reservoir 2 via a leak valve 4. Further, pipes 5 and 6 for introducing gas are connected through valves 7 and 8, respectively. Further, a capacitance type pressure gauge 9 is installed to observe the pressure inside the gas reservoir. A confusion plate 10 is provided in the gas reservoir to increase gas mixing efficiency. The gas reservoir 2 and the reaction chamber 1 are separated by an electromagnetic shutter 11.
A supersonic nozzle 12 is installed isolated by a. Further, the gas reservoir is heated by a heat source 20.

A substrate support 14 is provided in the reaction chamber 1 on which a substrate 13 is placed.
It can be heated by a heat source 15 provided at the bottom. In the present invention, a 3k11 resistance heating heat source was used as the heat source 15.

The reaction chamber 1 is evacuated by a high vacuum evacuation system through an evacuation pipe 16, and the pressure inside the reaction chamber is constantly observed with a pressure gauge 17. Further, a pipe 19 for introducing gas for pressure adjustment during deposition is connected to the reaction chamber 1 via a valve 18.

Next, a method for forming a thin film using the above-mentioned apparatus will be explained.

After the substrate 13 is introduced into the reaction chamber 1 and placed on the substrate support 14, it is evacuated by a high vacuum evacuation system via the evacuation piping 16. At this time, the pressure gauge 17 indicates that the pressure in the reaction chamber 1 is 10-' Pa.
Make sure that the inside reaches.

Next, the substrate is heated to a predetermined temperature from room temperature to 300° C. via the heat source 15 as necessary. During this time, gas reservoir 2
Close the valve 7.8, open the valve 4, evacuate with the second high vacuum evacuation system, and confirm that the pressure level 19 reaches a pressure on the order of 10''Pa. At this time, the electromagnetic shutter 11 is in a closed state, and the gas reservoir 2 and the reaction chamber 1 are isolated.

Next, after confirming that the ultimate pressure of the gas reservoir 2 is IP6Pa, open the valve 7 and use trimethylsilane S.
The pipe 5 that flows iH(CI(3)3) and SIH(CJ(3)a) is connected to a mass flowmeter and has a flow rate of 0 to 1010.
05e can flow. At this time, the pressure inside the gas reservoir 2 is adjusted by opening and closing the leak valve 4 so that it is on the order of 10''Pa. At this time, carrier gas Ar or He may be allowed to flow through the pipe 6.

Next, after confirming that the pressure inside the reaction chamber 1 is on the order of 10-6 Pa, the valve 8 is opened and the oxygen 02 is
The flow rate was cc/min. Adjust the exhaust power of the high vacuum exhaust system,
The pressure inside the reaction chamber is set to be in the range of 0 to 10-''Pa.

When the electromagnetic shutter 11 is opened in this state, SiH(CH3)a in the gas reservoir 2 is ejected to the reaction chamber 1 side via the supersonic nozzle 12. During this ejection process, SIH(CH3)3 heated to a predetermined temperature undergoes adiabatic expansion and is rapidly cooled.
By setting the temperature to below m, 5it((CH3)3 is supplied to the substrate surface while the vibrational temperature of SiH(CH3)3 remains unrelaxed.

This SiH(CH3)3 whose oscillation temperature has not been relaxed is very unstable, and at the same time it was adsorbed onto the substrate surface, it reacted with 02 (or O) on the substrate surface to form a SiO□ film.

At this time, the substrate temperature was varied within the range of room temperature to 300°C.
In all cases, the 5i02 film was deposited on the substrate at a deposition rate of 20 to 3000 people/n.

In this example, a case was shown in which a 5in2 film was deposited using SiH(CH3)3 and 02, but the present invention is not limited to this material, and any material that can obtain a gaseous compound may be used. However, the thin film to be deposited may also be Si.
It is not limited to O2, but also conductive films such as metals,
A semiconductor film such as silicon may also be used.

〔Effect of the invention〕

In this invention, a compound containing at least one of the atoms constituting a thin film is ejected from a nozzle, adiabatically expanded, and transported onto a substrate, which makes it possible to form a thin film on a substrate at low temperature and high speed. There are advantages.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing a manufacturing apparatus used to achieve the present invention. 1-----1----Reaction chambers 5, 6, 19-----1-Reaction gas supply pipe 12--
-------Supersonic nozzle 13-----Substrate 14-----M-Substrate support stand 15, 20-----Heat source for heating

Claims (4)

[Claims] (1) Formation of a thin film characterized by ejecting a compound containing at least one of the atoms constituting the thin film from a nozzle at supersonic speed, transporting it onto a low-temperature substrate, and forming a thin film on the substrate at high speed. Method. (2) The method for forming a thin film according to claim 1, wherein the thin film formed on the substrate is an insulating film. (3) The method for forming a thin film according to claim 1, wherein the thin film formed on the substrate is a conductive thin film. (4) The method for forming a thin film according to claim 1, wherein the thin film formed on the substrate is a semiconductor thin film.