JPS6193617A - Manufacture of silicon film - Google Patents

Abstract

PURPOSE:To make it possible to manufacture an Si film having a uniform thickness, by exposing a substrate, which is kept at 250 deg.C or more to a gas including a compound, which further includes silicon atoms, reducing the pressure of an atmosphere in the vicinity of the substrate, projecting ultraviolet rays on the surface of the substrate, and repeating the processes, at the temperature of the substrate, which is lower than the conventional temperature. CONSTITUTION:A substrate, which is kept at 250 deg.C or more is exposed to a gas including the compound, which further includes Si atoms. The pressure of an atmosphere in the vicinity of the surface of the substrate is reduced. With the pressure of the atmosphere in said vicinity being reduced, ultraviolet rays are projected on the surface of the substrate. These processes are sequentially repeated. For example, a solenoid valve 15 is opened, and argon Ar of about 10cm<3> including 5% disilane Si2H6 is introduced in the vicinity of a substrate 8. At the same time, a solenoid valve 14 is opened, pure argon Ar of about 30cm<3> is introduced and blown to a window 6. The solenoid valves 15 and 14 are closed in this order. Then the gas is exhausted for about 1.5-5sec. The vacuum degree in a reaction chamber is made to be 10<-4>Torr or less. A shutter 2, which is accompanied by a low voltage mercury light 1, is opened. Converged ultraviolet rays are projected on the substrate 8 for 3sec. This procedure is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing silicon films, which is a basic process in the integrated circuit industry.

Conventional configurations and their problems The manufacturing process of integrated circuits includes the production of silicon (Si) films, silicon dioxide (SIO□) films, and silicon nitride (S) films.
It consists of processes such as diffusion of impurities. This silicon (si)
) In the production of membranes, chemical vapor deposition (CVD) is usually used.
is employed, when the substrate temperature is at least about SO
It is possible to manufacture a silicon (S1) film by keeping the substrate temperature near room temperature using a vapor deposition method, etc.
The film quality is very poor. That is, the fabrication of a silicon (Si) film is approximately eo.

A substrate temperature of ℃ or higher is required.

Substrate temperatures of about aOO° C. or higher appear to make silicon (Si) film manufacturing equipment complicated and expensive. Furthermore, in order to make the manufacturing process of integrated circuits more flexible, it is desirable to lower the substrate temperature during the manufacturing of silicon (Si) films.

Further, in the conventional manufacturing process of a silicon (Si) film, for example, for a 4-inch substrate, the best film thickness distribution is approximately 6 inches. However, this variation in film thickness is directly caused by
This is reflected in product yield and property variations. The distribution of this film also needs to be about 2 to 3%.

OBJECTS OF THE INVENTION It is an object of the present invention to produce a silicon (Si) material that has a lower substrate temperature than conventional ones, good film quality, and improved film thickness uniformity.
) by providing a method for manufacturing membranes.

Structure of the Invention The method for producing a silicon (Sil) film of the present invention includes the steps of sequentially exposing a substrate maintained at 250° C. or higher to a gas containing a compound containing silicon (Si) atoms, and then exposing the substrate near the surface of the substrate to a gas containing a compound containing silicon (Si) atoms. The process of reducing the pressure of the atmosphere and the process of irradiating the surface of the substrate with ultraviolet light while reducing the pressure of the atmosphere in the vicinity are repeated. A silicon (Sil) film can be produced with the temperature of the substrate lowered, and the film thickness distribution does not depend so much on the size of the substrate and can be within 2 to 3 inches.

There are no particular limitations on the substrate as long as the surface has good flatness. Most preferably, the substrate is a glass substrate, a fluoride substrate, a single crystal silicon (Sl) substrate, a MgAffi20.
aF2) Ruru board. Suba,/- method and chemical vapor deposition (CYD)
) A glass substrate coated with a silicon (si) film, a Macne Spinel (M9AR204) film, or a calcium fluoride (CaF2) film is also desirable as a substrate.

The temperature of the substrate needs to be 260°C or higher.

When the substrate temperature is lowered to 250C or more, the luster of the formed silicon CSI film becomes dull and the film quality becomes poor. When the substrate temperature is significantly increased by 700° C., the uniformity of the film thickness tends to deteriorate.

The gas may be a compound containing a silicon (is) atom (
It may consist of the above compound (gaseous) and a non-oxidizing gas such as hydrogen (H2), helium (H.), or argon (Mr).

If there is a leak in the silicon (S+) film manufacturing apparatus according to the present invention, oxidizing gases such as rR element (O2) may It is inferred that the content of is required to be significantly small.

As the compound, disilane (5i2H, 1% trisila/(si,!@)) was the most desirable.However, trifine (5Hs) seems to have a boiling point of about 50°C and is always non-oxidizing. It is used diluted with a toxic gas.

Friend, for safety reasons, disilane (Si2H,l or trisilane/(sre'a)t-argon (mr) or hydrogen (
It is preferable to use the gas in diluted form with H2). Disilla 7 (fsi2H4) and Trisilla/(s
It is assumed that the object of the present invention can be achieved even if the content of isg8) in the gas is about 0.5-.

Doping f- into silicon CSI film with impurities formed
Shiboraf (BzH6) for 1G gas, and Al7 for maku
Add a small amount of phosphine (1 Hs) or diborane (B2H) from another pipe.
6), or by introducing a gas prepared by diluting arsine (AmHsl) or phosphine (PHxl) into a non-oxidizing gas into the reaction chamber.

The substrate is maintained at a temperature of 250° C. or higher using a heater or the like.

A cryo pump or a mechanical booster pump is usually used to reduce the pressure of the atmosphere near the surface of the substrate. The ultimate degree of vacuum must be at least approximately 16 τorr.

Preferred sources of ultraviolet light include excimer lasers, low-pressure mercury lamps, and xeno lamps, but among these, low-pressure mercury lamps are the most desirable from the viewpoint of ease of handling.

For the optical system for condensing the ultraviolet light, a glass made of synthetic quartz is used. Furthermore, in the silicon (St) film manufacturing apparatus according to the present invention, the window for introducing the ultraviolet light is formed of synthetic quartz. In addition, pure hydrogen or pure argon is constantly blown to prevent clouding with precipitates.
It is inferred that this is the reason why the above-mentioned substances suddenly stopped adsorbing.

First, in the process of bathing the substrate in a gas containing disilane (st2M,) or 1-1 tridilaph (at,!4.), disilane y (Si2!tl
) molecules or trisilane (BL3H83 molecules, etc.)
e, NrfI consisting of several molecular layers is formed.

Therefore, in the process of reducing the pressure in the atmosphere near the substrate surface, the gin':)/(8'2H4) or trisilane (S
Gas components containing L and HsJ are exhausted and removed.

Next, in the process of irradiating the substrate surface with ultraviolet light while reducing the pressure of the atmosphere near the substrate surface, the ultraviolet light described in item 1 is absorbed by the adsorption layer. This light energy and the thermal energy originating from the substrate add adsorbed disilane (Si2H-molecules or trisilane (slsH,
) molecules are decomposed and 513 atoms of silicon are precipitated. At this time, the ultraviolet jf in 1) efficiently reaches the adsorption layer in 1 because the gas near the substrate surface is depressurized and exhausted. It seems that it will.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to one drawing.

[Example 1] The figure shows the configuration I of a silicon (Si) fA manufacturing apparatus in an example of the present invention! FIG. In the figure, 1 is 100
W low-pressure mercury lamp, 2 is a shutter, 3 is a lens made of synthetic quartz, 4 is a path for ultraviolet light, 6 is a reaction chamber, 6 is a window made of synthetic quartz, 7 is a substrate carrier with a built-in heater, 8 is the base,
e is a pipe for spraying pure argon onto the window 6 so that the window 5 does not open.

1o is Jishira 7 (812) 14) or To 17
(Piping for supplying gas containing 8i3H@1, 11 is a grain for adding impurities to the silicon (si) film 2/(B2H41, 6 or phosphine (PHx)%)
12 is a pipe for sucking the gas supplied from pipe 9, 13 is a distribution pipe! 10.11 is a pipe for suctioning the gas supplied, 14,155°16 is a solenoid valve, 17 is a cryo pump, and 18 is a cooling coil. In addition, the reaction chamber, including the piping, should be carefully examined to prevent leakage of outside air into the interior.

As the substrate 8, a mirror-polished silicon-poor silicon (St) crystal plate, a mirror-polished calcium fluoride (CaF2) single crystal plate, and a mirror-polished sapphire plate were used. After washing and drying these, they were placed in the reaction chamber of the manufacturing apparatus described in 1 above, heated with a heater, and kept at about 600C for 1 hour. At this time, the reaction chamber is preliminarily evacuated using a separately provided oil rotary pump, and then the reaction chamber is evacuated using a cryo pump to maintain a reduced pressure state.

While maintaining the reduced pressure, the temperature of the substrate 8 is lowered to 5oot:, and thereafter this temperature is maintained during the formation of silicon (SL) 9. The degree of vacuum at this time was approximately 10 Torr.

The cryo-bonder is operated in a 1-a reaction chamber, and the reaction chamber is kept in an evacuated state at all times. Silicon (Si) is
Perform film formation.

First, open the solenoid valve 16 and add 60% of disilane (Si2H4).
About 10 d of argon containing 10% of argon is introduced into the vicinity of the substrate 8. At the same time, the solenoid valve 14 is opened and about 30 cd of pure argon (Mr) is introduced and blown onto the window 6. The time required for this process is approximately 0.6 seconds.

Thereafter, the solenoid valves 16 and 14 are closed in this order.

Next, exhaust the air for about 1.6 to 6 seconds. At this time, the degree of vacuum in the reaction chamber was 164τorr or less.

The shutter 2 associated with the lit 100 low pressure mercury lamp 1 is opened, and the substrate 8 is irradiated with concentrated ultraviolet light for t-3 seconds.

The above procedure was repeated to obtain silicon (31)@.

When the number of repetitions was about 400, the thickness of the formed silicon (51) film was about 2000 times, regardless of the substrate 8.

As a result of an electron beam diffraction experiment of the formed silicon (St) film, it was found that it was crystallized. Furthermore, when a single crystal plate of calcium fluoride 7-(CaF2), a sapphire plate, or a sapphire plate was used as the substrate B, the silicon (si) film formed thereon showed diffraction similar to that of single crystal. When the substrate 8 was made of a silicon crystal plate, the degree of single crystallization was reduced.

According to conventional methods, a silicon (8i) polycrystalline film cannot be obtained unless the substrate temperature is raised to at least aooc or higher using a vapor deposition method, and according to the chemical vapor deposition (CVD 3 method) the substrate temperature is raised to at least 600℃. It is known that the silicon (sB) film formed does not crystallize unless the temperature is above .degree.

Regarding the uniformity of the thickness of the silicon (Si) film formed,
If the substrate 8 is a calcium fluoride (CaF2) single crystal plate or a sapphire plate, it will vary slightly depending on the type of substrate 80, but the difference in film thickness will be within 1 inch when two substrates are placed 1° apart. Ta. According to the conventional method, this value can be achieved by increasing the size of the device, but there is a limit to this, and therefore it is a value that is difficult to reach. The film thickness (11111) was determined by using a step meter and by observing the cross section using a scanning electron microscope.

[Example 2] This example was made using the equipment shown in the figure. The base material is Pyrex glass and mirror-polished magnetism.
A spinel (Mg AItz O4) single crystal plate was used. Magne spinel (Mg12o) single crystals were obtained by a pulling method. After washing and drying these, l! After placing it in the reaction chamber of the I+ period apparatus, it was heated with a heater and kept at about 00°C for 1 hour.

At this time, the reaction chamber is preliminarily evacuated using a separately provided oil rotary pump, and then the reaction chamber is evacuated using a cryo pump to maintain a reduced pressure state.

1. While maintaining the reduced pressure state, the temperature of the substrate 8 is cooled to 250° C. and maintained at this temperature during the silicon (si) film formation. What is true at this time? ! The temperature was about 10 Torτ. A silicon (sB) film was formed using the same process as in Example 1 by operating the cryo pump and keeping one reaction chamber in an evacuated state. However, the gas used to expose the substrate was
About 10 Cjl of argon (μτ) containing (812M4) was used.

As a result of an electron beam diffraction experiment of the formed silicon (gi), it was found that it is amorphous and solid regardless of the type of substrate 8.

As a result of measuring the effect of simple photoconduction by irradiating light from a tungsten lamp, it was found that silicon (Sl) films made by plasma chemical vapor deposition (OVD) at the same substrate temperature as described above were also 1
It was found that this example was superior. This shows that the silicon (Sl) film according to the present invention has better film quality than the conventional method.

Regarding the uniformity of the thickness of the silicon (Si) film formed,
According to cross-sectional observation using a scanning atomic electron microscope, 10a++
The difference in thickness of the two substrates separated by 1 wX was within 1 inch.

[Example 3] This example was made using the apparatus shown in FIG. However, as the ultraviolet light source 1, a 1KW xenon lamp was used. As the substrates, a fused silica plate coated with calcium fluoride (CaF2) and a fused quartz plate coated with magne spinel (M9 mm i, o,) were used.

Summary Calcium fluoride (CaF2) films and magne spinel (v9A4,0.) films are formed by the Suba method. As a result of X-ray diffraction experiments, it was found that these films were crystallized. The thickness of these films is approximately 1ooO
The number of people was 6-3. After washing and drying these, they were placed in the reaction chamber of the above-mentioned device and heated with a heater to reach about so.
I kept it at o'c for 1 hour. At this time, the reaction chamber is preliminarily evacuated using a separately provided oil rotary valve, and then the reaction chamber is evacuated using a cryo pump to maintain a reduced pressure state.

1. While maintaining the reduced pressure state, the temperature of the substrate 8 is lowered to rsooc, and thereafter maintained at this temperature during the formation of the silicon (Sl) film. The degree of vacuum at this time was about 16'' Torr.

The cryo-bog 17 is operated to keep one reaction chamber constantly in an evacuated state, and silicon (Si) PA is formed in the following steps.

First, open the solenoid valves 115 and 16. From pipe 10,
Trijiraf (51, argon containing about 1 liter of Hal)
] Approximately 20 cd t-, diborane (B
About 1 cd of argon (Mr) containing about 0.1%
t- simultaneously introduced into the vicinity of the substrate 8. At the same time, solenoid valve 1
4 is opened, about 3oc11 of pure argon (^τ) is introduced, and it is blown onto the window 6. The time required for this process is approximately O,S
Think about it in about seconds. After this, the magnetic valves 16, 16, and 14 are closed in this order.

Each time, exhaust the air for about 1.6 to 6 seconds. At this time, the degree of vacuum in the reaction chamber was 10'Torr or less.

The shutter 2 accompanying the lit 1KW xenon lamp 1 is opened, and the base 8 is irradiated with the focused ultraviolet light for 1 second.

The above procedure was repeated to obtain a silicon (SL) film.

When the number of repetitions is about 400, the thickness of the silicon (51) film formed is about 2000, regardless of the substrate.

As a result of an electron beam diffraction experiment of the silicon (Si) film formed, it was found that it was crystallized. Further, according to the measurement of thermoelectromotive force, the conductivity type of the silicon (51) film formed was P, which was six.

According to conventional methods, such as vapor deposition, a silicon (St) polycrystalline film cannot be obtained unless the substrate temperature is at least 800°C, and chemical vapor deposition (CVD) requires a substrate temperature of at least 800°C. It is known that a silicon (St 2 ) film formed does not crystallize unless the temperature is 600° C. or higher.

Regarding the uniformity of the thickness of the silicon (Si) film formed,
103 In two substrates separated.

The difference in film thickness was within 1 inch.

[Example 4] In this example, an apparatus as shown in FIG. 1 was used. However, as an ultraviolet light source, 60W fluoride 1 Lugo/[MrF]
Ekinmar V-G was used. - This laser is normally used in pulsed oscillation.

The substrate is mirror-polished calcium fluoride (CaF).
2) A single crystal plate was used. After washing and drying this, it was placed in the reaction chamber of the inscription device, heated with a heater, and kept at about 600° C. for 1 hour.

At this time, after preliminary evacuation is performed using a separately provided oil rotary pump, the reaction chamber is evacuated using a cryo pump 1a to maintain a reduced pressure state.

While maintaining the reduced pressure, the temperature of the substrate 8 is lowered to 460° C. and maintained at this temperature thereafter during the silicon (8i) layer formation. The degree of vacuum at this time was approximately 10 Torr g degrees.

The cryo pump 17 is operated to keep the reaction chamber 5 in an evacuated state at all times, and a silicon (Si) film is formed by the following steps.

First, open the solenoid valve 16 and
About 10 cd of argon (Mr) containing 0.3% of phosphine (PHs) is introduced into the vicinity of the substrate 8. At the same time, the solenoid valve 14 is opened, and about 30 i of pure argon is introduced and blown onto the window 6. The time required for this process is approximately 0.5
It takes about seconds. Thereafter, the solenoid valves 15 and 14 are closed in this order.

Next, exhaust the air for about 1.6 to 5 seconds. At this time, the accuracy in the reaction chamber was 1 oτ orr or less.

Next, with the shutter 2 open, an SOW argon fluoride (MrF) excimer laser t-a is activated to irradiate the substrate 8 with a single laser beam.

The above procedure was repeated about 60 times to obtain a silicon (sB) film. The thickness of the silicon (Si) film was about 230.

As a result of an electron diffraction experiment of the silicon (si) film formed,
It was found that the crystallization was close to that of a single crystal.

According to conventional methods, such as vapor deposition, a silicon (ail) polycrystalline film cannot be obtained unless the substrate temperature is at least 800°C, and chemical vapor deposition (CI/D) requires a substrate temperature of at least 800°C. It is known that a silicon (15i) film formed does not crystallize unless the temperature is at least 600° C. or higher.

Regarding the uniformity of the formed silicon (Si) film, when the film thickness is small like this, the error is large and accurate evaluation is difficult. However, from other experiments and the like, it was concluded that even in the case of such a small film thickness, the uniformity of the film thickness is very good.

Effects of the InventionAs is clear from the above explanation, the present invention sequentially
The substrate kept at 0°C or higher is exposed to a gas containing a compound containing silicon (Sil) atoms, the atmosphere near the surface of the substrate is depressurized, and the surface of the substrate is exposed to ultraviolet light. Since the irradiation process is configured to repeat, it has the excellent effect of obtaining a silicon (SL) film with good density at low temperatures.This effect allows the semiconductor integrated circuit process to be performed at even lower temperatures. The present invention will greatly contribute to the manufacturing of thin film transistors and thin film transistors.

[Brief explanation of drawings]

The figure shows a silicon (Si) film manufacturing equipment for carrying out the present invention! FIG. 1...Ultraviolet light source, 2.../Yaketa, 3
...Synthetic quartz lens, 4..Ultraviolet light passage, 5..Reaction chamber, 6.Synthetic quartz breather, 7..Heater. Built-in base carrier, 8...
・Base body, 9... Piping for spraying pure Argo/(μτ) onto the window 6 so that the window 6 is not cloudy, 1o...
...Si2y (Si2Hi) or trisilane (f9
Piping for supplying gas containing 1AH9), 11
・・・・・・Sibo 2 (32H4), 6 or phosphine (PHs) for adding impurities to silicon (St) film
), or piping for supplying gas containing Al7/(muIH5), 12...Piping for sucking gas supplied from distribution W9, 13...Arrangement F
Piping for sucking gas supplied from 10 and 11,
14.15.16... Solenoid valve, 1 completion...
・Cryo pump, 18... Cooling pipe.

Claims (2)

[Claims] (1) Sequentially, the substrate kept at 250°C or higher is made of silicon
) A step of exposing the substrate to a gas containing a compound containing atoms, a step of reducing the pressure of the atmosphere near the surface of the substrate, and a step of irradiating the surface of the substrate with ultraviolet light while reducing the pressure of the atmosphere near the substrate. A method for manufacturing a silicon film characterized by repetition. (2) The method for manufacturing a silicon film according to claim 1, wherein the compound is disilane (Si_2H_6) or trisilane (Si_3H_3).