JPH0320023A - Forming method for n-type diffused layer - Google Patents

Abstract

PURPOSE:To form an N-type diffused layer with arsenic without electrostatic breakdown of an insulating film and without deterioration of the quality of the film by employing fluorine compound ions of the arsenic as N-type impurity substance. CONSTITUTION:After an element isolation region 2 is formed on a P-type silicon substrate 1, a capacitor and a gate are formed, and an ion implantation is conducted. The capacitor is formed of an N-type diffused layer 3, an insulating film 4 and an electrode 5, and the gate is formed of an insulating film 6 and an electrode 7. Fluorine compound ions 8 of arsenic are implanted as N-type impurity source. Fluorine atoms (F) have largest electronegativity of all atoms to be easily bonded to electrons, and its electric neutralization is facilitated. Since AsFn<+> is bonded to electrons in an implanting atmosphere, an electrostatic breakdown, deterioration of the quality of the insulating film are prevented. Thus, an N-type insulating layer 9 can be formed without breakdown, deterioration of the capacitor insulating film, the gate insulting film, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor manufacturing method, and particularly to an ion implantation method effective for forming an N-type diffusion layer of arsenic. It is.

When forming an N-type diffusion layer of arsenic using conventional ion implantation, arsenic ions (As'') are used.1
In addition, in order to prevent charge-up during ion implantation, a layer of electrons called an electron shower is introduced just before implantation to electrically neutralize the Am+ ions and implant arsenic into the semiconductor substrate surface. method is adopted.

Problems to be Solved by the Invention With the above-mentioned conventional techniques, electrical neutralization becomes difficult depending on the implantation conditions. In particular, the injection conditions are injection amount 1×101
If the beam current is 500 .mu.A or more at a current of 3 cN, charge-up will be significant, leading to destruction or deterioration of the capacitor insulating film, gate insulating film, etc. The present invention aims to provide a method that can solve this problem.

Means for Solving the Problems In order to solve the above problems, the present invention uses arsenic fluorine compound ions as an N-type impurity source.

Function: In the structure described above, the fluorine atom F has the highest degree of electronegativeness among all atoms. Therefore,
AsFn+ is more easily bonded to electrons than As+, and electrical neutralization is facilitated. First, in implantation using AsFn+, since it combines with electrons in the implantation atmosphere, electrostatic breakdown and insulation film quality deterioration can be prevented. Furthermore, even under implantation conditions of high implantation amount and large beam current, the problems of the prior art can be solved by using an electron shower in combination.

Example An embodiment of the present invention will be explained with reference to FIG.

After forming an element isolation region 2 on a P-type silicon substrate 1,
Shape and ion implant the capacitor and gate.

(Figure 1(a)). The capacitor is formed by an N-type diffusion layer 3, an insulating film 4, and an electrode 6, and the gate is formed by an insulating film 6 and an electrode 7.

Arsenic fluorine compound ions (As+Fn
``Hn=1~5)8 is used, Figure 1(b)
As shown in FIG. 2, even if the N-type diffusion layer 9 is formed, it does not affect the capacitor or the gate in any way.

FIG. 2 shows the insulation film breakdown voltage distribution in this case.

When arsenic ions (As'') 10 are used, a broken capacitor insulating film 12 and a deteriorated gate insulating film 13 are generated due to charge-up of the capacitor electrode 11 and gate electrode 14. Figure 3 shows the membrane breakdown pressure distribution.

In this experiment, it was effective when the implantation amount was in the range of 1E11 to 1E21cI1-2 and the beam current was in the range of 0.1 to 7.0mA.
-2, the beam current is 0.6~s. A significant difference was observed in the OmA region.

Furthermore, any number of fluorine atoms from 1 to 5 was effective.

In both Figures 2 and 3, the injection amount is 3 x 1o15c.
The results are for the case where the Ir2 beam current is 1 mA and a 200 nm silicon oxide film is used as the insulating film.

In addition, in this example, a load of ions is described, but
Needless to say, this also applies to ions with two or more charges.

Effects of the Invention As in the present invention, by implanting arsenic fluorine compound ions, there is no electrostatic damage to the insulating film or film quality deterioration, and N due to arsenic can be removed.
It is now possible to change the shape of the mold diffusion layer.

[Brief explanation of the drawing]

Fig. 1(a), Φ) Process diagram showing an embodiment of the present invention, Fig. 2
3 are distribution charts showing the effects of the tree embodiment. DESCRIPTION OF SYMBOLS 1... P-type silicon substrate, 2... Element isolation region, 3, 9... N-type diffusion layer, 4, 12...
...Capacitor insulating film, 5,11...
Capantor electrode, 6, 13... Gate insulating film, 7, 14... Gate electrode, 8... Arsenic fluoride compound ion, 10... Arsenic ion.

Claims (1)

[Claims] A method for forming an N-type diffusion layer, which comprises implanting arsenic fluorine compound ions as an N-type impurity source in the step of forming an N-type diffusion layer in a semiconductor substrate of one conductivity type using an ion implantation method.