JPS59218735A - Manufacture of insulating film and interface between insulating film and semiconductor - Google Patents

Abstract

PURPOSE:To enable to easily perform the introduction of fluorine into an SiO2 system-insulating film and to confine the DELTANFB value of an Si (111) plane- MOS to 10<10>cm<-2> or less by a method wherein carbon fluoride system-gas is specified. CONSTITUTION:A silicon, a silicon compound or a silicon oxide film is heated in gas of an atmosphere wherein CHXFYClZ (X+Y+Z=4, X=0-2, Y, Z=1-3) gas has been included oxidizing gas. Examplified as carbon fluoride system-gas are CHF2Cl, CF2Cl2, CF3Cl gasses, etc. Used as oxidizing gas are O2, CO2, NOX gasses, etc. For example, in case CF2Cl2 gas is included, the DELTANFB value in case the CF2Cl2 gas was included up to 5% to oxidizing gas is smaller than that in case the CF2Cl2 was not included and, in case the conclusion is up to 0.1%- 3%, the decrease of nearly one digit is observed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a high-quality silicon oxide-based insulating film and an insulating film-semiconductor interface.

Conventionally, to immobilize mobile ions in 5i02 and stabilize its electrical properties, S was used in a high-temperature atmosphere containing phosphorus oxide.
By heat treating Z O2 to form a phosphorus glass layer on the surface to getter the mobile ions, or by thermally oxidizing 5cot Z in an atmosphere containing chlorine or hydrogen chloride, the chlorine atoms become a barrier to mobile ions. as S
*It was taken in during 2002. This chlorine oxidation is further 5c
o2 It is known that it is effective in reducing the interface states at the Si interface, reducing the variation in the dielectric strength voltage of the 5LOz film (however, an increase in the dielectric strength value cannot necessarily be expected), and reducing crystal defects on the Si surface. There is. However, since the atomic radius of the chlorine atom is larger than that of Si, it is difficult to completely fill the defects in SiO□ and the defects on the surface of the SL coat. On the other hand, hydrogen has a small atomic radius, which is convenient for filling defects.
Although this effect exists, it dissociates after heat treatment at 300 to 400°C, and SL 02 and 5i02-8i
It has drawbacks such as being easily dissociated by high-energy carriers or electron beams transported to the interface, or by ultraviolet rays. The present inventors found that fluorine atom is a monovalent atom smaller than Si and S L
02 and S to 2 - We focused on the fact that it is effective in stabilizing the interface of semiconductors and improving quality, but it is known that fluorine ions are generally dissolved by fire in SiO□, and that they can be used in quartz reaction tubes used for thermal oxidation. It is being

The main purpose is to improve the quality and properties of the S*0@ system-semiconductor interface, and to solve this problem,
Previously, we proposed a method in which a Si compound is mixed into an oxidizing gas atmosphere such as carbon fluoride gas, CO2, NOx, etc., or a SiO2 film is heated in the above atmosphere. . In this case, the carrier gas is N
! + An inert gas such as Ar or Ha can be used. According to experiments, when the above-mentioned carbon fluoride gas is mixed into an oxidizing gas atmosphere, the quartz reaction tube also becomes S*02.
A high quality silicon oxide film could be obtained without any damage to the film. Note that the silicon oxide type mentioned above is a general term for silicon oxide and silicon oxide containing other elements such as nitrogen, chlorine, and phosphorus. The invention proposed above will be described below.

When a silicon substrate was thermally oxidized at a temperature of 800°C to 1200°C in an oxidizing atmosphere using CF, '& as a carbon fluoride gas, a decrease in the interface state density at the Sin, -Si interface was observed. Ta. FIG. 1 is an example of this, and the horizontal axis shows the volume attack of CF against oxidizing gas. In this example, the interface state sensitivity is reduced to 1/4. The dielectric strength of the S t 02 film grown under similar conditions was improved over that produced without the addition of CF. Figure 2 shows an example of this.
Even in the insulating film manufacturing technology with low plane j pressure, the average breakdown voltage value is improved from 4V to IOV by mixing CF4i. Here, the dielectric strength voltage is 10-10-15 for the insulating film.
Conveniently measured as a current of the order of A" or a flowing voltage.
%, the effect of improving withstand voltage is small.

S t O! System insulating films are often obtained with positive charges trapped in them at room temperature, and therefore conductive electrodes -8i0. In many cases, more electrons than in a thermal equilibrium state are induced on the semiconductor surface of a system insulating film-semiconductor (COS) structure. The surface density NFB of the excess electrons is proportional to the magnitude of the positive charge on the semiconductor surface side in the insulating film, and is preferably smaller, and it is also important that the variation with respect to the voltage, temperature, and tone applied to the CO8 structure is small. It was confirmed that by mixing fluorocarbon gas, the value of NFB becomes small, and the fluctuation of NFB with respect to bias and temperature is also small. Figure 3 shows Si on the (100) plane Si.
O2'? : CF4 In the measured values when grown in an oxidizing atmosphere, the NFB value changes from zero to a negative value, with the opposite sign from that of the conventional S*02 film. This property is useful for setting the gate threshold voltage of an n-channel MO transistor. Also CF.

It can be seen that when the amount of mixed chi is around 1%, the NFB fluctuation (ΔNyn) with respect to bias and temperature is also reduced.

By the way, when K S t Ot is grown on (111) plane Si, this ΔNrB is 1011 even if chlorine is mixed.
It is said that it cannot be reduced to less than cm-20 order.

The present invention has been made in view of the above points, and by specifying a fluorocarbon gas, ΔNFB can be reduced to 101O1.
01O or less.

The present invention will be explained below.

The present invention uses CHF, ClCF2 as carbon fluoride gas.
CHxFy Cl z (
X+Y+Z=4, X=0~2, y, Z=1~a) isu y
t to make ΔNFB Y 1010cn+-2 or less.

Figure 4 shows the value of ΔNFB when CF, C1, - is mixed, and when it is mixed up to 5% of the oxidizing gas, it is smaller than when it is not mixed, and from 0.1% to 3% it is almost a single digit. A decrease has been observed. This is thought to be due to the synergistic effect of gas (elementary) and fluorine. Conventionally, MO8-IC was mainly made of (100) planes in order to achieve a small value of NFB and ensure fire stability, but the present invention If we use the technique of (I
ll) A stable MO3-IC can also be obtained. It was observed that the interfacial state density also decreased on the (111) plane due to the mixing of this fluorocarbon gas containing chlorine. Furthermore, by the method of the present invention, rノ, S*02
S*Ot was also obtained without exhibiting VII'l properties, which suggests a decrease in the concentration of traps in the oxidizing gas.
Even when heat treated with air, interface states and traps decrease + NF
B *A reduction effect in ΔNFII was observed.

In addition, a silicon compound such as SiH, 5iC14 is supplied onto the heated substrate in a similar atmosphere, and S t Oz
A similar effect was obtained by forming a film of this type.

As described above, the present invention uses CHXFyClz scum as a fluorocarbon-based gas, making it easier to introduce fluorine into the 5402-based insulating film, which was difficult to do in the past, and moreover, it can be easily mixed with chlorine. Due to synergy, s;, (] 1 ])
The ΔNyB of the surface MOS can be made less than lQlO(M-2), which will greatly contribute to the semiconductor electronics industry.

[Brief explanation of drawings]

Figure 1 is a measurement diagram of an example showing the effect of reducing the interface state density layer due to the mixing of CF and gas according to the previously proposed invention, and Figure 2 is the same (measured diagram of an example showing the effect of improving dielectric strength due to the mixing of OF and gas) , Figure 3 is the same (CF. Decrease in NFB due to gas mixture, decrease in ΔNrn (stabilization)
Figure 4 is an example of measurement diagrams showing the effect. Figure 4 is an example of the present invention, where fluorocarbon containing chlorine is mixed in. Figure 4 CF2 C12 ('10)

Claims (1)

[Claims] CHx Fy Clz (X 10 Y 10 Z=4, x
=o~2°Y, Z=1~3) An insulating film and an insulating film-semiconductor interface characterized by heating silicon, a silicon compound, or a silicon oxide film in an atmospheric gas in which a gas is mixed with an oxidizing gas. manufacturing method.