JPS62145729A - Ion implantation and apparatus for the same - Google Patents

Abstract

PURPOSE:To implant ions uniformly into a semiconductor wafer by applying ion beams while the semiconductor wafer is turned. CONSTITUTION:A supporter 25 is formed into a disc shape and a shaft 27 is provided on the backside of the supporter 25 and extended so as to be linked with a rotary driving means such as a motor. A wafer 29 is hooked on the front surface of the supporter 25 and turned with the supporter 25. At least one turn of rotation is necessary during ion beam application and, moreover, if the semiconductor wafer is supported with a certain inclination angle, for instance 7 degree, against the ion beam, up to the part of the shadow of the pattern can be exposed to the ion beam.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an ion implantation method for implanting ions into a semiconductor wafer to form a predetermined pattern, and an apparatus therefor.

(Technical background of the invention and its problems) FIG. 4 shows a conventional apparatus for implanting ions into a semiconductor wafer 1. As shown in FIG. This device transfers ions emitted from an ion source 2 to a semiconductor tube 1 supported by a platen 3.
A separator 4 made of a magnet, an acceleration tube 5 that accelerates the ion beam, and a beam line 6 that narrows the ion beam are arranged in this order along the path of the ion beam 8 shown by the broken line. . The platen 3 is at a fixed angle with respect to the ion beam 8, for example 7! This device is designed to reduce channeling (7) to prevention (1) by tilting it at v. Next, the ions are accelerated in an acceleration tube 5, passed through a beam line 6, focused, and irradiated onto the semiconductor wafer 1.Then, the irradiated ions cause the semiconductor wafer 1 to be irradiated as shown in FIG. A predetermined pattern 7 is formed thereon.

FIG. 6 shows an example of the pattern formed as described above. A gate region 10 is formed in the semiconductor layer, a source region 11 and a drain region 12 are formed on both sides of the region 1 to 10, and an insulating film 13 is formed on the outside of these regions.

However, in this conventional implantation method, the platen 3 is tilted with respect to the ion beam 8, and the semiconductor chip 1 supported by the platen 3 is also tilted with respect to the ion beam 8. There is a problem that ions are implanted into the shadowed part of the pattern. For example, in FIG. 6, the ion beam 8 does not reach the lower portion 14 of the left side of the gate region 10, so the source region 11 does not extend below the gates 1-10. When a voltage is applied between the gate 10 and the drain region 12 or the source region 11 in this state, a depletion layer region 15 is extended between the gate region and the train region 12; The depletion layer region 16 does not extend between it and 11. For this reason, there is a problem that the electrical characteristics of the transistor are poor.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and it is an object of the present invention to provide an ion implantation method and apparatus for uniformly implanting ions over the entire wafer when forming a pattern on a semiconductor. .

[Summary of the invention]

In order to achieve the above object, the ion implantation method according to the present invention is characterized in that the semiconductor wafer is rotated during irradiation with the ion beam to uniformly implant ions into the semiconductor wafer. In addition, -3. The apparatus according to the present invention is characterized in that a rotatable support is provided on the platen, and a semiconductor wafer is hung on the support to enable the above-mentioned operation.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in more detail with reference to the accompanying drawings.

First, in the ion implantation method according to the present invention, ions are irradiated while rotating a semiconductor wafer. This rotation must be performed at least once during ion irradiation, and even if the semiconductor wafer is supported at a fixed angle to the ion beam, for example, 7 degrees, the shadow part of the pattern will be exposed to the ion beam. Can be exposed.

FIG. 1 shows the order in which semiconductor wafers are rotated. When implanting ions into the inclined portion of the pattern 21.degree. 22 as shown in FIG. 5(E), ions are first implanted into the diagonally shaded portion as shown in FIG. 2(A) by ion irradiation. and,
When the semiconductor wafer is rotated by 90 degrees, ions are implanted into the shaded area in FIG. 3B, and when the semiconductor wafer is rotated by 180 degrees, ions are implanted into the shaded area in FIG. The same figure (D>
Ions are implanted into the shaded area, and eventually the ions are implanted into the target area as shown in FIG. Therefore, as is clear from FIG. 1(E), even if the platen is tilted by, for example, 7 degrees with respect to the ion beam, the offset region can be reduced to 1/2 or less, and the extension of the depletion layer can be connected. .

Next, the apparatus used in such a method will be explained. This device consists of an ion source that emits ions, a separator that selects and extracts the necessary ions, and an acceleration tube that accelerates the ions, which are arranged in order along the path of the ion beam.
A platen for supporting a semiconductor wafer is provided at the end of the first path. Here, since the ion source, separator, and acceleration tube are all the same as in the conventional example, their explanation will be omitted, and the platen will be explained.

2 and 3 are side and front views of the platen 23 used in the apparatus according to the invention.

The platen 23 consists of a main body 24 and a support 25 provided within the main body 24. The main body 24 is mounted at a constant angle of inclination by brackets I to 26. The support body 25 is formed into a disk shape, and a shaft 27 extends from the back side, and the shaft 27 is directly or indirectly connected to a rotary drive means such as a not-shown rotor. , the support 25 is adapted to rotate within the body 24.

On the front surface of this support 25, there is a semiconductor chip 41 so as to be fixed (11) thereon. 11) A plurality of support pins 28 are attached to the peripheral edge of the support pin 28. The semiconductor wafer 29 is fitted and supported between the support pins 28, and even if the support body 25 rotates, it will not fall.
First, it rotates with the support body 25. Therefore, this
The above method can be easily implemented using a platen.

Note that it is also possible to support the semiconductor wafer by suction or mechanical chucking.

(Effects of the Invention) As described below, according to the method of the present invention, since ions are irradiated while rotating the semiconductor wafer, ions can be uniformly implanted into the semiconductor, thereby reducing defects in semiconductor devices. The occurrence of can be suppressed. Further, according to the apparatus of the present invention, the above method can be reliably implemented with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the method of the present invention; FIGS. 2 and 3 are side and front views of a platen used in the apparatus of the present invention; FIG. 4 is an overall plan view of the conventional apparatus; FIG. 5 is a side view of the main part thereof, and FIG. 6 is a side view of the pattern J: formed by the conventional method. 23...Platen, 24...Main body, 25...Support body, 28...Hanging pin, 29...Semiconductor wafer.

Claims (1)

[Scope of Claims] 1. An ion implantation method in which a pattern is formed by irradiating ions from an ion source onto the surface of a semiconductor wafer placed at a certain angle with respect to the ion beam. An ion implantation method characterized by implanting ions while rotating a semiconductor wafer in a predetermined direction along its surface. 2. Claim 1 for rotating the semiconductor wafer once
Ion implantation method described in section. 3. An ion implantation apparatus comprising an ion source that emits ions, an acceleration means that accelerates the ions, and a platen that supports a semiconductor wafer into which ions are implanted, the platen being rotatably provided in the main body. 1. An ion implantation apparatus comprising: a support body in the form of a flat plate, and the semiconductor wafer is attached to the support body. 4. The ion implantation apparatus according to claim 3, wherein the support body is provided with a support pin into which a semiconductor wafer is fitted.