JPS5967626A - Method and device for ion implantation - Google Patents

Abstract

PURPOSE:To shallow the depth of ion implantation by obliquely projecting ions to the implanting surface of a material to be ion-implanted. CONSTITUTION:When ion beams 6 pass in magnetic fields 10 formed to the upper section of a wafer 7, the beams 6 are bent in the direction rectangular to the direction of the magnetic fields 10, and their flying paths are varied. The beams 6 are projected to the wafer 7 at a fixed tilt angle. The depth H of implantation is obtained by DXsintheta. Where D is the flying distances of ions in the wafer. Accordingly, depth H can ge shallowed only by the rate of sintheta (smaller than 1).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion implantation method, which is a doping technique in the production of semiconductor devices, and to an apparatus directly used for carrying out this method.

In general, doping technology using ion implantation is characterized by the ease of controlling the amount and distribution of impurities, and has therefore become established as the primary technology for forming a diffusion layer in the manufacturing process of semiconductor devices.

However, as the degree of integration increases and patterns become finer, shallow junction depths are required to form source and drain regions that require high impurity concentrations to suppress short channel effects. It's here.

An object of the present invention is to meet this demand and provide an ion implantation method and apparatus that can achieve a shallow junction depth.

Hereinafter, the present invention will be explained according to embodiments shown in the drawings.

FIG. 1 is a schematic front view showing one embodiment of an ion implantation apparatus according to the present invention, and FIG. 2 is the same (an enlarged perspective view of the main parts).

In this embodiment, the ion implantation apparatus includes an ion source 1 that generates ions of an impurity element to be doped, an extraction section 2 that extracts the generated ions, and an ion source 1.
an acceleration section 4 that provides the necessary energy to the ions, and a scanning section that uniformly scans the ion beam 6 over the wafer 7. Further, a magnet 8 is provided near the wafer 7 as a means for forming a magnetic field above the implantation surface of the wafer 7 and parallel to this surface. Then, the wafer 7 is transported by a feeding device (not shown) as shown in FIG.
As shown by the arrow 9 in FIG. 2, the ion beam 6 is configured to be sent in a direction perpendicular to the scanning deflection plane, and the magnetic field of the magnet 8 is also 1° as shown in FIGS. 1 and 2. , so that they are formed parallel to each other in the same direction.

Next, an embodiment of the ion implantation method according to the present invention using the ion implantation apparatus having the above configuration will be described.

The ions generated and extracted by the ion source 1 are selected to be necessary, and after being given the necessary energy, they are focused into a beam, which is deflected and scanned by a scanning section 5 consisting of a parallel plate deflection electrode, etc. Be irradiated in the direction of the wafer 7. When this ion beam 6 passes through a magnetic field 10 formed above a wafer 7, the ion beam 6 is bent in a direction perpendicular to the direction of the magnetic field 10, changing its flight path, as shown in FIG. With this change, the ion beam 6
is incident on the wafer 7 at a predetermined inclination angle θ.

When ions are incident on the wafer 7 at an angle, the ion implantation state is as shown in FIG.

As is clear from FIG. 3, the depth H of ion implantation into the wafer 7 is determined by the following equation.

H=DX8jnθ Here, D is the flight distance of the ions in the wafer, and is determined by the intensity of the ion energy.

Therefore, when ions are implanted into the wafer at an angle of inclination θ, the implantation depth H is sin θ (less than 1) than when ions are implanted into the wafer at right angles.
The value of the driving depth H can be freely adjusted by controlling the inclination angle θ.

When the ion energy is kept constant, the tilt angle θ can be freely controlled by adjusting the strength of the magnetic field.

By the way, if ions are implanted into the wafer at an angle, the fourth
As shown in the figure, a portion is formed under the resist film 11 on the incident side where the ions are not implanted.However, as shown in Figure 4, the ions are tilted from two opposite directions. If this is done, the part where no ions are implanted will be eliminated, and the diffusion layer will instead have a bulge.

As a means of implanting ions from two directions at an angle,
For example, as shown in FIG. 1 and FIG. may be done alternately.

The ion implantation is carried out on the entire surface of the wafer (excluding the surface on which the resist film is formed) when the wafer 7 is fed perpendicularly to the ion scanning position.
A desired diffusion layer is formed.

According to this embodiment, the ion implantation depth can be made shallow, and the depth can be easily controlled. Moreover, since the distances from the ion beam scanning section 5 are almost equal within the ion beam, the implantation concentration becomes uniform.

The ion implantation method according to the present invention can be carried out by methods other than using the ion implantation apparatus described above.

That is, as shown in FIG. 5 or FIG. 6, respectively, by tilting the Ueno beam 7 with respect to the flight path of the ion beam 6, the ion beam may be incident on the Ueno beam at an angle. .

In FIG. 5, the wafer 7 is tilted in the direction of the scanning amplitude of the ion beam 6, and is fed in a direction perpendicular to the plane of the paper.

In FIG. 6, the wafer 7 is inclined in a direction perpendicular to the scanning width of the ion beam 6, and is fed in the direction of an arrow 9.

As shown, the wafer 7 is aligned with the flight path of the ion beam 6.
If the wafer is tilted, the ions will be implanted into the wafer at an angle, and the implantation depth of the ions will become shallow, as described above.

In addition, in order to avoid the occurrence of non-implanted portions of ions,
When implanting ions while tilting the wafer, as shown in Figure 5, the same wafer may be alternately tilted symmetrically, or the wafer may be reversed and fed (in the case of Figure 6).
do it.

As explained above, according to the present invention, the ion implantation depth can be made shallow.

[Brief explanation of the drawing]

1 and 2 are a front view and an enlarged partial perspective view showing a situation in which an embodiment of the ion implantation method according to the present invention is implemented using an embodiment of the ion implantation cylinder according to the present invention; Figure 3 is an explanatory diagram showing the principle of shallow implantation. Figure 4 is an explanatory diagram showing the principle of eliminating the non-implanted area. Figure 5 is a front view showing another embodiment of the ion implantation method using pressure according to the present invention. 6 is an enlarged partial perspective view showing another embodiment. 1... Ion source, 2... Extracting part, 3...
Mass spectrometry section, 4... Acceleration section, 5... Scanning section, 7...
・Wafer, 8...Magnet, 9...Wafer feeding direction, 1
0...Magnetic field. 115 Figure 5

Claims (1)

[Scope of Claims] 1. An ion implantation method characterized in that ions are incident on the implantation surface of an ion implantation object at an angle. 2. The ion implantation method according to claim 1, characterized in that the ions are incident at an angle by applying a magnetic field parallel to the implantation surface and bending the ion flight path. 3. The ion implantation method according to claim 1, wherein the ions are incident at an angle by tilting the object with respect to the flight path of the ions. 4. An ion implantation device that includes means for applying a magnetic field parallel to the implantation surface around the ion implantation target, and bends the flight path of the ions so that the ions are incident on the implantation surface at an angle.