JPS6027123A - Method of photo plasma gas phase reaction - Google Patents

Abstract

PURPOSE:To obtain the Si oxide film which is hard and has no void by a method wherein the reactive gas of hydride or halogenide of silicon is mixed with oxide gas and the light of 1,500-300cm<-1> wavenumber is projected and at the same time, plasma reaction is performed. CONSTITUTION:The reactive gas is sent from a doping system 20 to the substrate 1 arranged in a reaction system 10 of the device for photo plasma gas phase reaction. Next, the far infrared rays of 1,500-300cm<-1> wavenumber are projected to the substrate 1 by a lamp 9. These rays are resonance-absorbed in an Si-H coupling in the reactive gas, thereby activating the reactive gas. Next, plasma glow discharge is performed by a high-frequency oscillator 4 and electrodes 5 and 6 to cause a plasma reaction. Then, as photo excitation by the far infrared rays and the plasma reaction are carried out at a time, a step coverage of an uneven surface is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for combining a silicide gas and an oxide gas made of silicon hydrides or halides using a photoplasma vapor phase method (PPP vapor phase method).
The present invention relates to a method of forming a silicon oxide film by reacting with the method (referred to as CVD).

Conventionally, in order to make a silicon oxide film at a temperature of 500°C or less, there has been a method patented by the present inventor in which silane and oxygen are produced by a reduced pressure vapor phase method (Japanese Patent Publication No. 56-52877, Japanese Patent Publication No. 58-58). 24374) or a plasma CVD (referred to as PCVD) method using a reaction between silane and NLO is known.

The former has the advantage that even if the surface to be formed has irregularities, it is possible to form a thick film on the side surface of the surface, which is the same as that on the surface of the first surface, that is, it is possible to form a film with excellent stability. However, it had the disadvantage that the coating was soft.

On the other hand, although No. 1 & No. 1 & No. 1 had the advantage of being able to form a hard coating, it had the disadvantage that voids (holes) were formed at some of the corners of the uneven surface. These holes have a major drawback in that during microfabrication of integrated circuits, the ζ etching solution penetrates laterally through the holes, resulting in side etching at the stepped portions.

The present invention proposes a method for producing a film containing high-temperature silicon oxide and having no voids, in addition to being produced at a temperature of 500°C or less, preferably 200 to 350°C, as well as having a hard film. It is an object.

For this purpose, the present invention provides a method in which the S t-H bond in silane, which is a silicon hydride, is 2000 to 2200 cm-
'(peak value 2100 cm-1) and 1100-70
0 cm-' (peak value 950 cm', 830c
The purpose is to perform a plasma gas phase reaction accompanied by optical excitation by utilizing the characteristic of resonant absorption at wavelengths m-', that is, selective absorption of such long wavelength light energy.

For this purpose, the present invention uses a ceramic light-emitting heating element that emits continuous far-infrared light with a wavelength of 1500 cm' or less. For this purpose, 1100-700 of 5i-H
Far-infrared light (
By irradiating the reactive gas with FIR (hereinafter referred to as FIR) and absorbing it, the reactive gas could be activated.

Furthermore, the S i -H bond is the above FlI? It cannot be decomposed just by adding . Therefore, in addition to this, electrical energy was added to the reactive gas to generate a plasma reaction due to glow discharge.

By simultaneously performing the FIR and plasma reaction of the present invention, it is possible to achieve good stent coverage on uneven surfaces at microscopic levels that could not be achieved with the conventional PCVO method. 11.8), which further eliminates the presence of convergent surfaces in the concave portion, and proposes a method that is extremely effective for νLSI. Furthermore, even with weak electrical energy that is difficult to cause plasma excitation, PPCVD has made it possible to sustain the generation of discharge, and in turn, it has become possible to form a film on an uneven surface.

Therefore, it has become possible to reduce spatter (damage) caused by plasma on the surface to be formed.

It is now possible to perform impedance matching even in a wider pressure range, which makes it possible to perform impedance matching even in a wider pressure range.
10 torr), it also has the feature of being able to generate a large amount of active species in the plasma space.

On the other hand, conventionally, as a photo-CVD method, a C of 10.6 μ
A silicon oxide film can also be formed by optical CVD using only an O2 laser. However, in this case, the reaction space cannot be made larger than 1 OctI1, and the surface on which it is formed cannot be made larger than lcJ. Such l H/
In the photoCVD method, which is carried out by applying light energy of cJ or more, the coating surface is extremely small at 0.1 to 0.3 persons/second, and the power consumption ratio required for effective coating is large. , it is not effective in terms of energy saving either.

Furthermore, the area of the present invention is not extremely small as described above, but is at least 10 times that size, or more than 100 d (in this embodiment, the area is 4225.ffl), and the space is also 1.
000. ff1 or more (105625cJ in this example)
) and is characterized by proposing a method that can be industrially mass-produced.

The film formation and method of the present invention will be explained below with reference to the drawings.

Figure 1 shows monosilane (St)-14) among silanes.
The reaction formula is shown using as an example, but polysilane (s
i2H, etc.) is similarly possible.

FIG. 1 shows an outline of an apparatus for carrying out the method of the present invention in which the reaction system is PPCV D.

FIG. 1 has a reaction system (10 doping system (20) and an exhaust system (30).

The reaction system (10) consists of a reaction container (2) [inner volume (0190
cm, height 60cm, depth 90cm), reaction space (6
5cm x 65cm x 25cm, 105625 cIa
)), a substrate (1) having a surface to be formed is placed in the space (3).
2) and is held in a quartz holder (31).

This holder has a length of 65 cm, but has a width of 20 cm in the flow direction of the reactive gas, and allows 100 5-inch wafers to be inserted at the same time (total surface area to be formed: 12,266 mm).

The substrate is heated to 100 to 500 by the halogen auxiliary heater (7).
It is heated to, for example, 250°C. In addition, 1500cm
-1 (9,3p) ~ 700 cm-' (14,3μ)
Lamp for photochemical reaction that emits light at the FIR wavelength (9)
(Maximum 3KW.

27 mW/ant) is provided at the same time. The reactive gas enters the reaction space (32) from the introduction D (H,) through the nozzle (3), and reaches the exhaust system (30) through the outlet (8) and (12).

The exhaust system (30) includes a pressure adjustment valve (13), a 7 valve (14), and a mechanical booster pump (17).
, waste materials are discharged to the outside from the rotary pump (18).

The substrate is first placed in the preliminary chamber (16) using a holder, and after vacuuming is performed at (22>, (23)), the substrate is placed at the gate (3).
7) was opened and moved to the reaction space (32). The reactive gas is silane from (26) in the doping system (20),
Other gases for boron glass such as diporane (BzHc) or gases for phosphorus glass such as phoshine (PH3) (24
〉, oxide gas nitrogen dioxide (NO) (25),
Nitrogen or helium (27) as carrier gas was added via a flow meter (29), respectively, controlled by a valve (28).

Oxide gases include not only NLO, but also GOL, No.
It may also be NO2.

In FIG. 1, the valves (25>, (4β) are reached through the pressure regulating valve (32).

A reactive gas having an S t -H bond for semiconductors made of silane (39) passes through (26) and a flow needle to reach the reaction system (10). This reaction system is provided with a surface to be formed which is maintained at 100-500°C, preferably 200-350°C, typically 250°C, and the pressure in the reaction area (32) is maintained at 0.0-10 torr, for example. I torr,
Silane flow rate 1-200cc for 7 minutes e.g. 20cc/
The amount was supplied.

In addition, the NLO is NLO/5tH4>5, here 200cc/min is supplied, and the FIR light energy is transferred to a ceramic heating element such as a zircon ceramic (ZrSi%
) emitted by a lamp (length 680mm, diameter 11m
Light irradiation was performed using six (3 KW in total) mφ output 500 W).

FIG. 2 shows the luminescence characteristics (50) of a ceramic heating element using the method of the present invention. In such characteristics, 1
It can be seen that sufficient heat generation occurs at wave numbers of 500 cm' or less. It goes without saying that this ceramic heating element may be made of not only zircon but also heat-resistant ceramics such as alumina and zirconia.

Further, the absorption peak of the S 1-1t bond of silane was also shown in curve (51), and infrared light could be sufficiently resonantly absorbed around 10μ (1000cm').

The effect was small when the FIH output was 5 mW/cJ1 or less, and the effect was more pronounced at higher outputs within a range that did not cause the substrate temperature to rise too much above the set value.

Next, the electrical energy is transmitted to a high frequency oscillator (frequency 10 to 5
00KIIz (relatively low frequency, e.g. 50KHz), from (4) to the pair of electrodes (5), (,6)
00-For example, 200 W was applied to cause a plasma glow discharge to perform a PPCV D reaction.

This discharge is prevented from reaching the heating element (9).
9) Prevent silicon oxide from adhering to the possible locks,
Made it so that it does not interfere with FIR light emission.

Change this frequency to 500KHz or higher, for example 13.56FIH
If z, it is difficult to obtain a homogeneous electric field of the discharge plasma, and the variation in the material and film thickness exceeds ±5%.The substrate position is arranged parallel to the irradiation light, Photochemical reactions were carried out on the reactive gas in flight rather than on the substrate surface. By doing this, PP can be produced in large quantities.
CVD could be performed.

Regarding side quality, especially density (hardness), it is better if the irradiation light is perpendicular to the substrate, but in terms of mass productivity, it is the first
The layout of the figures was excellent.

This FI I? Due to the irradiation, among the silicide gases, silane in particular exhibits an associated state in advance in the cylinder.

For this reason, there are generally so-called clusters in the silicon oxide film, which are observed under an electron microscope to have a stoichiometrically large amount of silicon. Then, during the subsequent heat treatment, densification occurs and cracks are more likely to occur. This conventional pcv
The clusters observed in o gave FIR and the ζ-associated silanes could be dispersed and made into monomolecules.

Since each of the decomposed particles was reacted with an oxygenate, no clusters were observed under a transmission electron microscope, and thus a silicon oxide film could be produced using the PPCVD method of the present invention.

In this embodiment of the apparatus, the substrate was disposed in the positive column region of the generated glow discharge plasma, and a silicon oxide film was formed on the surface to be formed, for example, based on the following formula.

SiH4+ 3NL OSt Oo +21(20'+
3Nt Furthermore, when simple PCVD was performed using this apparatus for comparison, an attempt was made to apply only electrical energy together with so-called thermal energy for heating without adding optical energy from an FIR lamp.

This growth rate was 5 to 8 people/second, for example 6 people/second, for PCVD alone.

In PPCVD, the rate was 6 to 13 people/second, for example, 9 people/second.

In PPCVD, when trying to obtain the same film growth rate, the electrical energy is 10% (light energy 0.1 KW) to 50% (3) [W
) could also be weakened. In this PPCVD method, it is extremely important that the process involves light irradiation and then electrical energy is applied to generate plasma. By doing so, damage to the substrate surface due to plasma shock waves at the start of discharge can be prevented, and plasma damage can be substantially prevented electrically.

Figure 3 shows an SEM (
It is a cross-sectional view of a scanning electron microscope (SEM) photograph.

In other words, a nest 41) is seen on the substrate (1) at a height of 1.5 .mu.rl]2 .mu.m convex portion. This is the conventional P C, V
3 in order to improve the uniformity of the frequency in the D method.
This is presumed to be due to the fact that the active reaction product was as low as 0Kllz and the active reaction product could not reach the four parts.

On the other hand, in the ppcvo method of the present invention shown in FIG. 4, the photoexcited active reaction product could be sufficiently diffused even deep into the recess.

That is, the amount of surrounding debris was significantly improved by applying light energy, and no nests were observed at all in some of the four corners. This is seen when the FIR is 5mW/cn or higher, and the case at 28mW/c4 (3kW) is the fourth
The figure shows the shape using an electron microscope.

This is extremely important for obtaining high reliability of VLSI and for creating submicron patterns, and it cannot be denied that it has great industrial effects.

In addition, we were able to increase the effective utilization rate of the reactive gas introduced into the reactor (yield: silicon adhered to the film/introduced silicon), which was 2 to 5% in the PCVD method. With the PPCVD method of the present invention, it is possible to increase this to 10-20%.

In the method of the present invention, the output of the FIR was 28 mW/cJ per unit space force of 3 KW. However, it is effective to further increase this output to 50 to 500 mW/cJ to further enhance the FIR effect and to reduce the electrical energy required for the photoplasma reaction in order to prevent damage to the surface on which it is formed.

In this specification, an insulating film containing silicon oxide as a main component is shown. Boron or phosphorus is simultaneously added to this insulating film to form boron glass (BSG) or phosphorus glass (
PSG) is also BIHt during film formation.

Alternatively, it goes without saying that PHJ may be introduced.

Furthermore, it is effective to simultaneously introduce methane or ammonia to form a silicon oxide film doped with carbon or nitrogen.

In this specification, examples of silicon hydrides are shown. However, 5i-F is 1300~100100O', S
i-CI can obtain its resonance absorption at 1000-600 ci. This allows S+F++ instead of 5il-14! 1□SiF21JSiCI□5iC
It is effective to use halides such as I as the silicide gas.

[Brief explanation of drawings]

FIG. 1 shows a reaction system using the method of the present invention. Figure 2 shows the far-infrared emission characteristics used in the present invention and 5
This is the infrared absorption characteristic of the i-II bond. FIG. 3 shows a longitudinal cross-sectional view of a coating obtained by a conventional example. FIG. 4 is a longitudinal cross-sectional view of a film made by the optical plasma vapor phase method of the present invention. patent applicant

Claims (1)

[Scope of Claims] (2) By mixing an oxide gas into a reactive gas of silicon hydride or halide, irradiating continuous light with a wave number of 1,500 to 300 cm'', and supplying electrical energy, optical plasma is produced. A light plasma vapor phase reaction method characterized in that a silicon oxide film is produced by allowing a reaction to occur. 2. In claim 1, SiH4 is used as a silicon hydride and N20 is used as an oxide gas. At the same time, continuous light of 5mW/cJ or more is used at 500KIIz.
A photoplasma vapor phase reaction method characterized in that a silicon oxide film is produced on an uneven surface by supplying electrical energy with the following frequencies.