JPH01204434A - Manufacture of insulating thin film - Google Patents

Abstract

PURPOSE:To control the formation of a film in the order of an atomic layer with good reproducibility over a wide area, by supplying a halogen compound incorporating a silicon element on a substrate, and alternately repeating a step for forming an adsorbing layer and a step for introducing at least one of nitrogen, oxygen or gas of a compound of nitrogen or oxygen. CONSTITUTION:A first step is a step wherein a silicon compound or its radical is attached on the surface of a substrate. Adsorbing conditions and manufacturing conditions are selected so that adsorbing energy of the adsorbing species of the silicon compound and the like into a ground is higher than adsorbing energy of adsorbing species into an existing adsorbing layer. Then, the conditions for forming a two-dimensional adsorbing layer are obtained. In a second step, the adsorbing layer which is formed in the first step is oxidized or nitrided. The first and second steps such as these are alternately performed. In this way, a uniform thin film characterized by excellent film thickness control in the order of an atomic layer and excellent reproducibility in the substrate having a large area can be formed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to the production of insulating thin films.

[Conventional technology]

In recent years, insulating thin films have come to play an extremely important role as a means of downsizing, improving performance, and improving the performance of electronic device elements. In particular, the performance of insulating thin films containing silicon, such as gate insulating films of thin film transistors, various semiconductor devices, and insulating thin films for capacitors, has a great influence on device characteristics.

Furthermore, insulating thin films used for padding and interlayer insulation are essential for improving reliability. Such insulating thin films have conventionally been manufactured by chemical methods such as chemical vapor deposition techniques and coating methods under normal pressure or reduced pressure, and physical methods such as vacuum evaporation methods and sputtering methods.

[Problem to be solved by the invention]

As the range of applications for insulating thin films expands, there is an increasing need to form films uniformly and with good reproducibility on large-area substrates. This is a particularly important problem in thin film elements for displays. Conventional technology requires precise control of gas flow rate φ pressure during film formation, evaporation amount,
Careful management of numerous manufacturing parameters was required, including input power, substrate temperature and its distribution, consideration of gas flow, and substrate rotation ring. Other features include precise control of film deposition time.

The film thickness was indirectly controlled. As described above, the current situation is that there are a wide variety of thin film manufacturing parameters, and great efforts are being made to control them. However, as substrates become larger, it is becoming increasingly difficult to form an insulating thin film having a uniform thickness with good reproducibility. In particular, the insulating thin film for display panels has a very large substrate.
For example, variations in film thickness affect panel performance and reliability.

Furthermore, new devices using ultra-thin films, which have been actively researched in recent years, require manufacturing technology that accurately and reproducibly controls growth rates on the order of atomic layers. However, as mentioned above, it has been difficult to satisfy these requirements with the conventional techniques.

An object of the present invention is to provide a new method for manufacturing an insulating thin film, which enables film formation control on the order of atomic layers with good reproducibility over a wide area.

[Means to solve the problem]

The insulating thin film manufacturing method according to the present invention includes a first step of supplying and adhering a nologate/compound containing at least one silicon element or its radical to the substrate surface, and at least one of nitrogen, oxygen, or a compound gas thereof. The second step of supplying the gas to the substrate surface is alternately performed.

[Effect]

Is the 8gl process basically a silicon compound or its radicals on the surface? This is the process of attaching it. At this time, the coverage ratio of the adsorption layer may become less than 1 due to desorption from the surface due to insufficient adsorption energy or steric hindrance between adsorbed molecules. However, what is important in this case is not to cause the island-like multilayer adsorption growth of the Volmer-Weber style. In other words, the form of the adsorbed N species and the manufacturing conditions f are adjusted so that the adsorption energy of adsorbed species such as silicon compounds to the substrate is higher than the adsorption energy of the adsorbed species to the already adsorbed layer.
By selecting t, two-dimensional adsorption layer formation conditions can be obtained. The present inventor used various silico/compounds to explore the conditions.

As a result, it became clear that silicon halogen compounds or their radicals were suitable. The reason is,
Although it is not clear at present, silicon chloride, for example,
5iCI! z and 5iCI! In the form of 17 L, chlorine prevents multilayer adsorption at appropriate temperatures. For this reason,
This adsorption layer is considered to be two-dimensional. Furthermore, the compound smoothly undergoes oxidation or nitridation reactions at appropriate temperatures. Furthermore, when the Tonogen compound was used, even if the adsorption layer coverage was 1 or less, a uniform thin film could be formed by repeating the first and second steps of the present invention. This suggests that localized multilayer adsorption layers do not occur when using the No. 1 loge/compound.

The step 1@2 is a step of oxidizing or nitriding the adsorbed ni formed in the first step using the silicon-halogen compound or its radicals. In this step, only the surface adsorption layer is reacted, and the surface reaction is completed at a very early stage after the introduction of nitrogen, oxygen, or a gaseous compound thereof. The underlying layer of the adsorption layer where the surface chemical reaction occurs has undergone a nitriding or oxidation reaction in the previous stage. therefore.

After this surface reaction is completed, no untoward reactions occur. For this reason, it has also become possible to uniformly nitride or oxidize an adsorption layer formed on a large-area substrate.

In this way, the adsorption layer formation in the first step and the second
By utilizing the effects of oxidation and nitridation of the adsorbed layer in the process, thin films are formed on the order of atomic layers. As already mentioned, the aforementioned effects can be produced uniformly over a wide range. In other words, it has become possible to control and form a uniform insulating thin film over a wide range on the order of atomic layers, which was difficult with conventional techniques. This eliminates the need for many devices that were conventionally necessary to form a uniform insulating film, such as gas flow unique to the device, uniform temperature distribution inside the reactor and substrate, and substrate movement and rotation.

On the other hand, the first step and the second step are made into one cycle, and in that one cycle, growth on the order of atomic layer 1. ? Because of this method, the time required for film formation is longer than that of the prior art. However, since the above-mentioned effect is utilized, an insulating thin film having a uniform thickness can be formed with good reproducibility even if a large-area substrate is processed multiple times. Therefore, the overall throughput of manufacturing an insulating thin film according to the present invention is not low.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

[Example 1] A block diagram of the insulating thin film manufacturing apparatus used in the present invention is shown in the first example.
As shown in the figure. In this example, dichlorosila? was used as the starting material for the first step. In this example, a procedure for manufacturing a silicon nitride thin film will be described. The gas used in the second step was 100
% ammonia NHs. As shown in FIG. 1, three systems, a dichlorosilane supply system, an ammonia supply system, and a replacement gas (Ar) supply system, are connected to a reaction chamber 1 made of quartz. After introducing several large substrates 5 into the reaction chamber IK,
Evacuate the reaction chamber to below 10-' Torr. At this time, it is important to keep the back pressure of residual gases such as oxygen and Hz O as low as possible. This is because the influence of residual gas on the film quality is large because the film formation rate is low. three-way valve 2, connected to the dichlorosilane and ammonia supply system;
3, and dichlorosilica/and ammonia are alternately introduced into the reaction chamber 1. The three-way valve 2.3 is controlled by a microcomputer. The electric furnace 6 heats the substrate. It has the ability to heat up to about 800C.

In this example, after first heating to 700C,
stabilize it. First, dichlorosilane and ammonia are respectively poured into the exhaust side and stabilized. Next, the displacement gas (
Ar) is introduced into the reaction chamber. At this time, the pressure adjusting pulp 7 is adjusted so that the pressure in the reaction chamber is around ITorr. At this time, the pressure regulating valves 12 and 14 are adjusted so that the pressure in the dichlorosilane and ammonia supply lines is 5 Torr or more. First, 3-way valve 2 for 2 seconds
is operated to close the reaction chamber side and exhaust side to supply dichlorosilane to one reaction chamber. This is the first step in which dichlorosilane is deposited on the substrate surface to form a silicon compound adsorption layer. Next, the three-way valve 2 is closed to the side of the reaction chamber for 1 second to terminate the supply of dichlorosilane and replace the gas in the reaction chamber. Next, the three-way valve 3 is opened for 2 seconds on the reaction chamber side and closed on the exhaust side to supply ammonia onto the substrate. This is the second step of nitriding the silicon compound adsorption layer. After completing this second step, gas replacement is performed for 1 second.

The above series of steps is regarded as one cycle, and is repeated a predetermined number of cycles.

Although one molecular layer was not grown in one cycle, the thickness of the grown film was exactly proportional to the number of cycles. We also confirmed its reproducibility. That is, the manufacturing method according to the present invention enables film formation control on the order of atomic layers.

The film thickness distribution within the substrate was extremely uniform with ±1% or less.

In this example, dichlorosilane was used, but other materials such as trichlorosilane and silicon tetrachloride may also be used. Furthermore, a silicon oxide film could be manufactured using oxygen, HzO, etc. instead of ammonia. Or ammonia and Nz
A silicon oxynitride thin film could also be formed by using a gas mixture of O and Nx. At this time, the ratio of oxygen and nitrogen in the thin film could be adjusted by adjusting the ratio of oxygen and nitrogen in the supplied mixed gas.

In this way, a silicon-based insulating thin film can be formed using a combination of various gases, and the gases used in the first step and the second step are not particularly limited.

However, manufacturing conditions such as substrate temperature differed somewhat depending on the gas used, such as dichlorosilane, trichlorosilane, and silicon tetrachloride.

In addition, in the silicon nitride film formation in this example, the substrate temperature was 1
A similar effect was obtained in the range of 200 to 600C. However, below 2000, the adhesion rate (or a coverage rate) of adsorbed species
Almost no film growth was observed due to a decrease in surface reaction and a decrease in surface reaction. Moreover, at temperatures above 600 C, decomposition of dichlorosilane/ is progressed and three-dimensional growth begins, which is unsuitable for uniform thin film growth.

[Example 2] FIG. 2 shows a block diagram of the insulating thin film manufacturing apparatus used in this example. This device is basically the same as the device used in Example 1. The difference is that radical generators 26 and 27 are newly added to the dichlorosilane supply system and the oxygen supply system. Radicals are generated by a discharge phenomenon caused by high frequency waves, microwaves, DC high voltage, etc., or by light irradiation. In this embodiment, radicals are generated using microwave discharge. As the substrate 22, a large glass substrate was used. Several glass substrates are introduced into the reaction chamber 21, and a vacuum of less than h10-' Torr is created.

After reaching vacuum, heat the substrate to 2500 ℃. The procedure is the same as in Example 1, supplying dichlorosilane radicals for 2 seconds,
Replace for 1 second, supply oxygen radicals for 2 seconds, and replace again for 1 second. The above series of steps is one cycle, and is repeated a predetermined number of times.

The film formed was a silicon oxide thin film with high insulation properties. The film thickness distribution was very uniform within ±1%, and the surface showed a smooth surface with almost no defects such as pinholes. The grown film thickness was accurately proportional to the number of cycles, and its reproducibility was also good.

-Also, the same effect could be obtained even if only one of the radical generators was operated. That is, only oxygen and nitrogen are converted into radicals to activate and lower the temperature of the surface reaction in the second step, and to match the substrate temperature of the adsorption reaction in the first step. Or, conversely, the same effect can be obtained by radicalizing dichlorosilane/ in order to activate and lower the temperature in the first step. Further, the raw materials used in the first step may also be trichlorosilane or silicon tetrachloride. Similarly, the second
Similar effects can be obtained by using a mixture of two or more gases in various combinations as raw materials used in the process, such as nitrogen, nitrogen and NzO, ammonia and oxygen, HzO, nitrogen and oxygen, and nitrogen and HzO.

[Example 3] FIG. 3 shows a block diagram of the insulating thin film manufacturing apparatus used in this example. This equipment uses gases used in the IE2 process,
The structure is such that ammonia and N@O can be introduced from separate supply systems. The substrate 43 is made of single crystal silicon, and after introducing several substrates into one reaction chamber 41 and evacuating it, about 300
It is heated to t:'. First, dichlorosilane is supplied for 2 seconds, followed by a 1 second gas exchange period. Here, the ft exchange gas is Ar, which is constantly flowing into the reaction chamber at a pressure of 1 to 5 Torr. After that, only ammonia is introduced for 2 seconds, and gas replacement is performed again for 1 second. This series of procedures is called the first cycle. After repeating this first cycle six times, proceed to the second cycle. The second cycle refers to the series of steps described below. First, dichlorosilane is supplied for 2 seconds, and gas replacement is performed for 1 second. Thereafter, only NzO is introduced for 2 seconds, and a gas replacement period of 1 second is again allowed.

After repeating this second cycle twice, the process returns to the first cycle. The first and second cycles described above are collectively referred to as one cycle, and are repeated a predetermined number of cycles.

The grown film thickness was accurately proportional to the number of cycles, and its reproducibility was also high. The formed thin film has a dielectric breakdown field comparable to that of silicon oxide, and a high dielectric strength comparable to that of silicon nitride.
It had a C rate. This is very effective for gate insulation and capacitor applications. It also had the characteristic of having a barrier effect as high as that of silicon nitride against mobile ions such as Na+.

The gas used in the first step may be trichlorosilane, chlorine tetrachloride, or the like. Similar effects can be obtained by combining various gases used in the second step depending on the purpose.

Furthermore, as already described in Example 2, at least one of dichlorosilane used in the first step, ammonia or N 20 used in the second step is radicalized and introduced into the reaction chamber. Good too. This made it possible to optimize and lower the substrate temperature for adsorption and surface chemical reactions in each process. Even in this manner, the effects of the present invention, such as excellent film quality such as uniformity of film thickness and insulation properties, and excellent film thickness controllability and reproducibility on the order of atomic layers, could be obtained.

[Example 4] The insulating thin film manufacturing apparatus used in this example was exactly the same as the apparatus used in Example 3. The substrates are single-crystal silicon, and several substrates are introduced into a reaction chamber, evacuated, and then heated to about 300C. First, introduce dichlorosilane for 2 seconds,
Wait for a 1 second gas replacement period. Next, ammonia is introduced for 2 seconds, and gas replacement is performed again for 1 second. Repeat the above series of steps 200 times. Next, after repeating the above procedure 50 times, in the second step of the 51st time, N2
Flow to 0'. At this time, ammonia was not flowing. The dichlorosilane y-ammonia procedure is then repeated 49 times and then the second step is flushed with N20 twice. Thereafter, in the same manner, the number of dichlorosilane-NzO steps is increased little by little, approaching the formation of a 5iO- film. The deposited film was a silicon oxynitride thin film with dielectric constant and refractive index varying in the film thickness direction over a wide area. In this way, it is also possible to change the gas used in the second step during film formation. A thin film having a desired composition in the film thickness direction could be manufactured on a large-area substrate with uniformity on the order of atomic layers and with good reproducibility.

〔Effect of the invention〕

Supplying a halogen compound containing silicon element onto the substrate,
The method according to the present invention for producing an insulating thin film by alternately repeating the first step of forming an adsorption layer and the second step of introducing at least one of nitrogen, oxygen, or a compound gas thereof includes the following steps. It worked. First, the film thickness can be controlled on the order of atomic layers. Second, it was possible to form a uniform thin film with good reproducibility even when a large number of large-area substrates were processed at the same time. Thirdly, by the manufacturing method according to the present invention, the structure of the thin film manufacturing apparatus can be made simpler than the conventional one. This is because the manufacturing method according to the present invention allows a uniform thin film to be formed without any special device modifications such as gas flow or substrate rotation. Fourth, the thin film composition could be controlled on the order of atomic layers.

Utilizing this effect, we have made it possible to apply new insulating thin films, such as in the manufacture of devices that require precise compositional control, such as superlattice structures. Fifth, since precise control of manufacturing parameters such as gas flow rate and pressure is not required, the entire process can be automated and labor-saving compared to conventional methods.

As described above, the present invention has many effects, and many applications such as thin film transistors are being considered.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an insulating thin film manufacturing apparatus used in Example 1 of the present invention. FIG. 2 is a block diagram of an insulating thin film manufacturing apparatus used in Example 2 of the present invention. FIG. 3 is a block diagram of an insulating thin film manufacturing apparatus used in Examples 3 and 4 of the present invention. 1, 21.41...Reaction chamber, 2,3...
・Three-way valve, 5, 22.43... Board, 6...
...Electric furnace, 7...Main pulp, 26.2
7 ...radical generator, work 2゜work 4...
...Pressure adjustment pulp. Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] (1) A first step of supplying and adhering a halogen compound containing at least one silicon element or its radical to the substrate surface, and a first step of supplying at least one gas of nitrogen, oxygen, or their compound gas to the substrate surface. A method for manufacturing an insulating thin film, characterized in that the second step of supplying the insulating thin film is performed alternately.