JPH02276145A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To properly neutralize the charge-up of a substrate, which occurs when implanting charged beams into the substrate with a large-current ion implantation device by implanting ion beams generated in the ion implantation device into the substrate while alternating the cations and the anions of the same element. CONSTITUTION:As<+> or As<-> ion beams are implanted into a substrate 2 alternately. At this time, the beam currents in implantation enter a Faraday cup 4 through the part of a hole provided in a disc rotating at high speed, and beam currents in implantation are monitored by a DC ammeter 5. This way, in case of using both cations and anions, for the DC ammeter 5 to monitor beam currents, the current quantity is instructed both in positive and negative directions, so as the beam currents for use in calculation of implantation quantity the current quantity treated as an absolute value becomes necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high-current ion implantation apparatus, which is one of semiconductor device manufacturing apparatuses.

(Prior Art) When forming a semiconductor element using a high-current ion implantation device, charge accumulation (hereinafter referred to as charge accumulation) in the substrate is performed by ion implantation in order to inject t% of charged ions consisting of high density cations into the substrate. ) occurs. This charge-up causes property deterioration and destruction of semiconductor elements, so
A neutralization device (hereinafter referred to as an electron shower) is required to neutralize the charged beam.

(Problems to be Solved by the Invention) Generally, an electron shower used in a large current ion implantation apparatus has a mechanism that directly rains a low-energy secondary electron beam onto a substrate into which ions are implanted.

As shown in FIG. 3, the conventional electron shower has a structure in which the secondary electron beam 14 of the electron shower falls on the area where the positive ion beam 11 is directly injected into the substrate 2.

At this time, the substrate 2 is placed on the disk 3 rotating at high speed.

In this case, the positive ion beam 11 is an elliptical beam, and since the center of the charged beam is flying as a beam with high beam density, the secondary electron beam 14 of the electron shower is directed toward the center of the positive ion beam 11. There is a problem that it is difficult to neutralize. In addition, the secondary electron beam 1 of the ffl child shower
4 is rained down over a wide area by the metal reflection plate 13 of the electron shower, so there is a problem that the positive ion beam falls on parts of the substrate 2 that have not yet been implanted, especially during implantation. When the secondary electron beam 14 of the electron shower enters the Faraday cup 4 that monitors the charged beam amount (beam current), the dose cannot be accurately measured, resulting in an error in the implanted amount.

(Means for Solving the Problems) In order to solve the above problems, the present invention prevents charge-up without using an electron shower, and uses a positive ion beam and a negative ion beam with approximately equal beam currents. are injected into the substrate alternately.

The positive charge-up that occurs when a positive ion beam is implanted into the substrate is neutralized by implanting a negative ion beam into the substrate. Further, unless the cycle of the negative and cationic ion beam is suppressed to within 80% of the breakdown voltage of the implanted object (for example, an oxide film), the film quality of the implanted object will deteriorate.

(Function) According to the present invention, it is possible to moderately neutralize the charge-up of the substrate that occurs when a charged beam is implanted into the substrate with a large current ion implantation device.

(Embodiment) An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic diagram of an embodiment of the invention. Further, FIG. 2 shows a top view of a high current ion implantation device using a positive ion beam and a negative ion beam.

As shown in FIG. 1, ion beams 1 of As" or As- are alternately implanted into a substrate 2. At this time, the beam current during implantation is transmitted through a hole provided in a disk 3 rotating at high speed. It enters the Faraday cup 4 through the opening, and the beam current during injection is monitored by a DC ammeter 5, as in the present invention.

When using both positive and negative ion beams,
Since the DC ammeter 5 that monitors the beam current is instructed to indicate the amount of current in both positive and negative directions, the amount of current treated as an absolute value is required as the beam current when used for calculating the injection amount.

As shown in FIG. 2, it has two ion sources 6, an extraction electrode 7 with a negative voltage to extract a positive ion beam (As") 11, and an extraction electrode 7 with a positive voltage to extract a negative ion beam (As-) 12. An extraction electrode 8 is provided in front of each ion source, and each ion beam passes through a mass spectrometry magnet 9 to a predetermined ion beam (in this case, As
Then, immediately after passing through the mass spectrometry magnet 9, the ion beam trap 10 is alternately inserted so that the positive ion beam 11 and the negative ion beam 12 can be injected alternately. By opening and closing, it is possible to perform implantation using a positive ion beam and implantation using a negative ion beam alternately.

(Effects of the Invention) As explained above, according to the present invention, it is possible to completely prevent the charge-up of the substrate that occurs during ion implantation in a high-current ion implantation device even in the center of the positive ion beam, and to Deterioration of characteristics and destruction of the element can be prevented. Furthermore, it becomes possible to accurately control the dose of ion implantation.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 is a top view of a high-current ion implantation device using a positive ion beam and a negative ion beam, and Fig. 3 is a schematic diagram for explaining a conventional example. Show the diagram. ■...Ion beam (As" ions and As- ions)
, 2... Substrate, 3... Disk, 4... Faraday cup, 5... DC ammeter, 6... Ion source, 7... Extraction electrode (negative voltage),
8... Extraction electrode (positive voltage), 9... Magnet for mass spectrometry, 10... Ion beam trap, 11... Positive ion beam (As''), 12- Negative ion beam (As-), 13...metal reflective plate, 1
4...Secondary electron beam. Patent applicant Matsushita Electronics Co., Ltd.

Claims (1)

[Claims] A semiconductor device manufacturing apparatus characterized in that an ion beam generated from an ion implantation apparatus is alternately switched between positive ions and negative ions of the same element and implanted into a substrate.