JPH05343344A - Ion implanting method for manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent channeling uniformly as an entire semiconductor substrate without necessity of complicated steps by forming a direction of a crystal face on a surface of the substrate previously on a surface in which the channeling bardly occurs in the case of ion implanting, or ion implanting from a direction in which the channeling bardly occurs. CONSTITUTION:A semiconductor substrate 1 (100) is inclined 3 deg. to 9 deg. toward two directions of <0, 1, 1> axis (X-axis) and <0, -1, 1> axis (Y-axis) perpendicular to <1, 0, 0> axis (Z-axis) perpendicular to the surface of the substrate 1. Further, impurities are ion implanted from a direction in which a difference of inclining angles of the <0, 1, 1> axis direction and the <0, -1, 1> axis direction is 3 deg. or more. Thus, when the ion implantation is conducted by a method for inclining 3 to 9 deg., a channel region becomes minimum to an incident direction of an ion beam, and hence channeling hardly occurs. Thus, channeling can be prevented uniformly as the entire substrate effectively without necessity of complicated steps.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for implanting ions into a semiconductor substrate used for impurity diffusion in the manufacture of semiconductor devices.

[0002]

2. Description of the Related Art Semiconductor substrates used in semiconductor devices are
Single crystal materials (eg silicon) are often used.

In single crystal silicon, atoms are regularly arranged, and the orientation planes, that is, <1,0,0>, <1,1,
There is a region “channel” where atoms do not exist in the 0>, <1, 1, 1> axis directions.

On the other hand, when forming an impurity diffusion layer in the process of manufacturing a semiconductor device, an ion implantation method is generally used. However, when impurities are implanted in the direction perpendicular to the surface of the semiconductor substrate by this ion implantation method, the impurity atoms enter the channel between the atomic arrangements to a deep position without undergoing energy loss due to collision with Si atoms. .. That is, a channeling phenomenon occurs.

Conventionally, the following method has been considered as a method for preventing this channeling phenomenon.

(1) The semiconductor substrate for the ion beam
Ion implantation from a slightly inclined direction.

(2) A method of forming an amorphous oxide film on the surface of a semiconductor substrate and performing ion implantation through the film.

[0008]

However, among the conventional methods, the method (1) is insufficient in the effect of preventing channeling and cannot be reliably prevented. Particularly when it is desired to obtain a deep diffusion layer (well layer, etc.), it is necessary to increase the acceleration energy of ion implantation, and in such a case, there is almost no effect.

Further, although the method (2) has a high effect of preventing channeling, it has the problem that the process is complicated because an amorphous oxide film has to be formed.

It is an object of the present invention to provide a semiconductor substrate and an ion implantation method that reliably prevent the above-mentioned channeling and do not require complicated steps.

[0011]

For the above-mentioned purpose, the present invention is directed to <1,0,0 perpendicular to the (100) plane of the semiconductor substrate.
<0,1,1 orthogonal to the> axis (z axis in terms of coordinates)
> Axis (x-axis) and <0, -1,1> axis (y-axis) or <
0, -1, -1> axis and <0, -1, 1> axis, or <0,
-1, -1> axis and <0, 1, -1> axis, or <0, 1,
3 for any one of the 1> axis and the <0,1, -1> axis
Inclination from 9 ° to 9 °, and the difference in each inclination angle is 3
The ion implantation is performed in a certain direction or more, or the plane orientation of the semiconductor substrate is tilted from the (100) plane so as to satisfy the ion implantation direction.

[0012]

As described above, according to the present invention, when performing ion implantation, the crystal plane orientation of the surface of the semiconductor substrate is set to a surface in which channeling is difficult to occur in advance, or ion implantation is performed from a direction in which channeling is difficult to occur. As a result, complicated steps are not required, channeling can be prevented effectively and uniformly over the entire semiconductor substrate, and transistor characteristics (particularly threshold voltage) can be stabilized.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the range of the ion implantation angle of impurities in the embodiment of the present invention, and the hatched portion in the figure is the implantation angle range of the present embodiment. The same figure (aa)
As shown in (ba), the (100) semiconductor substrate 1 is perpendicular to the <1, 0, 0> axis (z axis) perpendicular to the surface, for example, <0,
2 of 1,1> axis (x axis) and <0, -1,1> axis (y axis)
Tilt from 3 ° to 9 ° in one direction and <0,1,
1> Inclination angle in the axial direction (Fig. 1 (a)) and <0, -1, 1
> Impurity ions are implanted from a direction in which the difference between the inclination angles in the axial direction (FIG. 1B) is 3 ° or more. The range of such implantation angles is <0,1,1><0,-1,1><0, -1,
Since there is a combination of inclining by 3 ° to 9 ° with respect to two of the four directions of the −1><0,1,−1> axis, there are eight regions as shown in FIG. Therefore, as described above, <0,1,1> and <0, -1,1>, <0, -1,
-1> and <0, -1, 1>, <0, -1, -1> and <
There are two areas each of which is inclined toward the axes of two directions of 0, 1, -1>, <0, 1, 1> and <0, 1, -1>, which is 8 areas.

In addition to performing the ion implantation by tilting the above-mentioned ion implantation angle with respect to two directions, the semiconductor substrate itself is set to <1,
For example, <0,1,1> axis and <0,-
Tilted in the two directions of the 1,1> axis from 3 ° to 9 °, and <
The semiconductor substrate is set such that the direction in which the difference between the tilt angle in the 0, -1,1> axis direction and the tilt angle in the <0, -1,1> axis direction is 3 ° or more is the crystal axis of the semiconductor substrate surface. It can also be realized by doing. In that case, the ion implantation may be from a vertical (with respect to the horizontal) direction. That is, it is equivalent to tilting the ion implantation angle described above.

When the ion implantation is performed by the method of tilting from 3 ° to 9 ° as described above, the channel region described above is minimized in the incident direction of the ion beam, so that channeling is unlikely to occur.

[0016]

As described above in detail, according to the present invention, the crystal plane orientation on the surface of the semiconductor substrate is made to be a surface in which channeling is difficult to occur in advance, or ion implantation is performed from a direction in which channeling is difficult to occur. Since it is performed, complicated steps are not required, channeling can be prevented effectively and uniformly over the entire semiconductor substrate, and transistor characteristics (particularly threshold voltage) can be stabilized. ..

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the present invention.

[Explanation of symbols]

 1 Semiconductor substrate (wafer)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Muneyuki Matsumoto 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (1)

[Claims] 1. When ion-implanting impurities or the like in the manufacture of a semiconductor device, an x-axis perpendicular to the z-axis and a direction orthogonal to the z-axis and the x-axis and the z-axis are orthogonal to the z-axis which is a direction perpendicular to the surface of the semiconductor substrate. 3 ° to 9 in both directions with y-axis
An ion implantation method for manufacturing a semiconductor device, wherein ions are implanted into the semiconductor substrate from a tilted direction.