JPH0442920A - Ion implanation - Google Patents

Abstract

PURPOSE:To prevent an insulating film from being broken by charging up a wafer by implanting ions with laminate resist, which consists of normal positive resist and conductive resist containing a conductive material such as carbon, used as a mask. CONSTITUTION:Laminate resist 2 consisting of normal positive resist and carbon- added positive resist applied continuously thereon is formed on a wafer 1 and patterned by photolithography and the wafer is put in the disc 3 of a heavy- current ion implanter. In this time, the wafer 1 is fastened by the whole periphery with a clamp ring 4 made of SUS, aluminum, or other metals. Ion beams 5 of boron, phosphorus, or arsenic are applied to implant ions into the wafer 1. A mask prevents electrostatic breakdown caused by increase in the charge potential of the surface of the resist in ion implantation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of ion implantation into a wafer, and particularly relates to an improvement of a photoresist which is a mask material.

[Summary of the invention 1 In a method of implanting ions onto a wafer, a conductive (lambda) resist is formed on a normal positive photoresist to prevent the wafer from being charged up during ion implantation. [Conventional technology] When ion implantation is performed using a resist as a masking material, the beam current density of the implanted ions is lowered, or the wafer is charged up using an electron shower or electron flat gun that supplies electrons according to the amount of charge on the wafer. is prevented.

[Problems to be Solved by the Invention] However, with the above-mentioned conventional technology, the ion implantation time becomes longer, the processing capacity of the equipment decreases, new equipment investment is required and its management becomes difficult, and the semiconductor device As the particles become finer, the effectiveness of electron shower and electron flat guns also decreases. This poses a problem.

The present invention is intended to solve these problems, and its purpose is to provide a masking material for preventing electrostatic breakdown caused by wafer charge-up during ion implantation.

[Means for Solving the Problems] The ion implantation method of the present invention involves forming a photosensitive resin (positive photoresist) based on a novolac resin on a wafer, and then adding carbon, silicon, etc. to the resin. The method is characterized in that a conductive positive resist to which a conductive substance is added is continuously formed, the resin layer is patterned, and then ions are implanted into the wafer using the resist layer as a mask.

[For production]

By using the masking material according to the present invention, it is possible to prevent electrostatic breakdown caused by an increase in the charged potential of the resist surface during ion implantation.

[Examples] Hereinafter, the present invention will be described in detail based on Examples.

In FIG. 1, a laminated resist 2 is formed on a wafer 1 by successively coating a regular positive resist as a lower layer and a carbon-added positive resist as an upper layer, and patterned by photolithography. This is set on the disk 3 of a high current ion implanter as shown in FIG. At this time, the entire periphery of the wafer 1 is fixed with a clamping ring 4 made of metal such as SUS or aluminum.

Next, as shown in FIG. 3, an ion beam 5 of boron, phosphorus, arsenic, etc. is irradiated to implant ions into the wafer 1. At this time, the charged ions 6 are transferred to the laminated positive resist 2.
Since the surface of the laminated positive resist 2 has conductivity, it flows from the disk 3 to the ground line via the crumbling 4, and as a result, no breakdown of the insulation film due to charge-up occurs.

Even if carbon is added to a positive photoresist, the heat resistance and resolution of the resist will not deteriorate. Also, when removing the resist, only the altered layer formed by ion implantation is removed. The conductive resist containing carbon may be ashed with plasma and then removed with a solution such as sulfuric acid and hydrogen peroxide, or the entire layered resist 2 may be removed with 02 plasma. Therefore, there is no problem with contamination of the inside of the wafer by the 02 plasma.

The resist may be made of a conductive substance other than carbon, and the same effect can be achieved, and the film thickness ratio between the normal resist and the conductive resist is not particularly defined.

It is a laminated resist, and as long as there is a conductive resist on the surface layer, it is clear that it contributes to preventing electrostatic damage to the wafer.

[Effect of the invention 1] As described above, by ion-implanting a resist having a laminated structure of a normal positive resist and a conductive resist containing a conductive substance such as carbon as a masking material, it is possible to reduce the charge-up caused by wafer charge-up. It has the effect of preventing insulation film breakdown.

1, 2, and 3 are main sectional views showing an embodiment of the ion implantation method according to the present invention.

wafer Laminated positive resist ion implanter disc crumbling ion beam charged ions that's all Applicant: Seiko Epson Corporation Agent: Patent attorney Kisanbe Suzuki (1 other person)

[Brief explanation of drawings]

Claims (1)

[Claims] After forming a photosensitive resin (positive type photoresist) composed of a novolac resin as a base on the wafer, a conductive positive resist in which a conductive substance such as carbon or silicon is added to the resin is continuously formed. An ion implantation method characterized in that after patterning a resin layer, ions are implanted into the wafer using the resist layer as a mask.