JPS62226631A - Forming method for insulating film - Google Patents

Abstract

PURPOSE:To reduce leak current, and form an insulating film at a low temperature and in a short time period, by laminating a second film whose film forming speed is high on a first film whose electrical characteristics are excellent, at the time of forming on Si system insulating film on a substrate by a photochemical gas phase reaction. CONSTITUTION:An Si substrate 3 is mounted on a stand 2 in a sample chamber 1, which is exhausted at 10<-3> Torr by driving successively a rotary pump 10 and a mechanical booster pump 9. hluring the exhausting process, the temperature of the substrate is kept at 300 deg.C by an infrared ray lamp, and a specified amount of SiH4 and NO2 are introduced at equal to or lower than 10-3 Torr. Keeping 2.5 Torr, an Hg lamp 6 is operated, and a first SiO2 film is formed on the substrate 3. Then an inlet 7 is closed to keep the state equal to or lower than 10-3 Torr, and a specified amount of Si2H6 and O2 are introduced. While keeping 2.5 Torr, the Hg lamp is operated, and a second SiO2 film is continuously formed and laminated. According to this constitution, an insulating film of 200 nm thick can be formed in about 60 min. The first film of SiO2 and the second film of Si3N4 are also effective, both of which can be formed at a low temperature in a short time period.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to an improvement in a method for forming, for example, an interlayer insulating film by photochemical vapor phase reaction, and in particular to an insulating film formation method for forming a thick silicon-based insulating film in a short time. It is about the method.

<Conventional technology> In recent years, damage-free films have been formed at low temperatures, and photochemical vapor phase reactions using light energy have been used to improve step coverage and electrical properties compared to insulating films produced by the one-length method. It has excellent physical characteristics, etc.

<Problems to be Solved by the Invention> However, in forming a thin film by direct excitation photochemical reaction, the film formation rate is low, and for example, it is difficult to form a film thickness required for an interlayer insulating film (for example, 200 nm). It has the disadvantage that it takes a very long time.

The present invention was devised in view of the above points, and an object of the present invention is to provide an insulating film forming method for forming an insulating film on a substrate at low temperature in a short time.

Means for Solving the Problems In order to achieve the above object, the insulating film forming method of the present invention provides a method for forming a silicon-based insulating film with excellent electrical properties in the process of forming a silicon-based insulating film on a substrate by photochemical vapor phase reaction. The second silicon-based insulating film is formed at a high deposition rate on the first silicon-based insulating film.

Further, as an embodiment of the present invention, the first insulating film is S
After a silicon oxide film is formed using an iH4/N20-based gas, a silicon oxide film is continuously formed as a second insulating film by photochemical vapor deposition using a 5i2Ha10z-based gas.

Function> With the above configuration α, the time required to form the insulating film can be significantly shortened, and the time required to form the insulating film described above can be significantly shortened. An embodiment of the present invention will be described in detail with reference to FIG.

FIG. 1 is a schematic diagram showing an example of a thin film forming apparatus used to carry out the insulating film forming method of the present invention. In FIG. 1, 1 is a reaction chamber (sample chamber), 2 is a wafer susceptor,
3 is a silicon wafer, 4 is an IR clamp 5 is a synthetic quartz,
6 is a mercury lamp (Hg lamp), 7 is an I-i gas inlet, 8 is a gate pulp, 9 is a mechanical booster pump, IOI
/'i It is an oil rotary pump.

First, a P-type (+oO) silicon (Si) substrate (15-20Ω-crn) is placed on the wafer susceptor 2 in the sample chamber of the apparatus configured as described above, and then the rotary pump is operated. After roughly reducing the pressure in the sample chamber 1, the mechanical booster pump 9 was used to evacuate the sample chamber 1 to 10 -3 Torr. During this exhaust operation, the temperature of the substrate 3 is 1aoo using the IR lamp 4.
('c) and held. After evacuation to below +o [Torr] using the mechanical booster pump 9, silane (5iH4) gas and N20 gas are introduced from the gas introduction lower, for example, at 15 (SCCM) or less.
] and 250[:SCCM], the pressure in the sample chamber I was kept at 2.5 (Torr), and a first silicon-based insulating film was deposited on the silicon substrate 3 using a mercury lamp (Hg lamp) 6. A silicon oxide film was formed.

Next, close the gas introduction lower and mechanical booster pump 9
Sample chamber using! After evacuating the inside to 10 (Torr) or less, disilane (5izHs) gas and 02
For example, 3 [SCC
M], 250 [:SCCM] was introduced, the pressure in the sample chamber l was maintained at f2.5 (Torr), and a mercury lamp (Hg
lamp) 6 on the substrate 3 on which the SiH4/N20-based silicon oxide film was formed! A silicon oxide film serving as the silicon-based insulating film No. 2 was continuously formed to a thickness of 160 nm.

Next, the gas introduction lower is closed, and the inside of the sample chamber I is evacuated to below 10 [:Torr] using the mechanical booster pump 9. After that, N2 gas is introduced into the sample chamber 1 to return it to atmospheric pressure, and the sample chamber I is returned to atmospheric pressure. 1. Fully opened and sample 8 was taken out.

In addition, Fig. 2 shows SiH4/N20 system, 5i2H6102
Figure 3 shows the dependence of the growth rate of silicon oxide films on substrate temperature.
MIS capacitors were fabricated for each sample in which a 102-based silicon oxide film was formed, and the electric-voltage characteristics were shown.

It took time.

Furthermore, when using high-order silane gas, an insulating film of a desired thickness can be formed in a shorter time;
As is clear from the figure, electrical characteristics such as dielectric strength voltage deteriorate, which is not preferable.

On the other hand, in the above embodiment, a silicon oxide film based on SiH4/N20 with excellent electrical properties is used as the gIJ+ insulating film, and 5izH6102, which has a fast deposition rate, is used on the @l insulating film. As a result, an insulating film of a desired thickness can be formed in a short time without deteriorating electrical characteristics.

Note that the present invention is not limited to the above embodiments,
It is possible to carry out various modifications without departing from the gist; for example, the film structure may be SiH4/N2
It goes without saying that the structure is not limited to the two-layer structure of silicon oxide films of the 0 series and 5i2H6102 series, and for example, a three-layer structure may be used.

Furthermore, the insulating film used is not limited to a silicon oxide film, and may have a two-layer structure of, for example, a silicon oxide film and a silicon nitride film. a silicon oxide film, and a second silicon oxide film.
A two-layer structure of silicon oxide film/silicon nitride film may be used in which the insulating film is a 160 nm silicon nitride film.

Furthermore, it goes without saying that conditions such as the gas pressure in the sample chamber, the substrate heating temperature, and the film thickness of each oxide film may be determined as appropriate according to specifications and the like.

<Effects of the Invention> As described above, according to the present invention, it is possible to reduce leakage current and form an insulating film at low temperatures in a short time, and as a result, a thin film forming apparatus used for interlayer insulation can be improved. A schematic diagram showing an example of the configuration of the SiH4/N2
FIG. 3 is a diagram showing the substrate temperature dependence of the deposition rate of 0 series and 5i2H6102 series silicon oxide films, and FIG. 3 is a diagram showing the current-voltage characteristics of each silicon oxide film.

I...sample chamber, 2...wafer susceptor, 3...
Silicon wafer, 4...IR lamp, 6...Mercury lamp (Hg lamp), 7...Gas inlet.

Patent applicant: Todoroki, director of the Agency of Industrial Science and Technology Figure 1 103/Tsub (K7’) A friend is Yufu Tenraito Circulation/)T Figure 2 S 　　　　　　　　　　10 E (M/cm) υshida-monme pressure eyesjunction

Claims (1)

[Claims] 1. In the step of forming a silicon-based insulating film on a substrate by photochemical vapor phase reaction, a step of forming a first silicon-based insulating film, and a step of forming the above-mentioned silicon-based insulating film on the first silicon-based insulating film. A method for forming an insulating film, comprising the step of forming a second silicon-based insulating film at a film-forming rate faster than the film-forming rate of the film-forming step, and forming an insulating film with a multilayer structure. 2. The first silicon-based insulating film is SiH_4/N_2
2. The method of forming an insulating film according to claim 1, wherein the second silicon-based insulating film is formed using an O-based gas and the second silicon-based insulating film is formed using an Si_2H_6/O_2-based gas. 3. The insulation according to claim 1, wherein a silicon oxide film is formed as the first silicon-based insulating film, and a silicon nitride film is formed as the second silicon-based insulating film. Film formation method.