JPS6146951A - Resist peeling method - Google Patents

Abstract

PURPOSE:To easily peel a resist without scorching by bringing plasma into contact with the resist contg. the surface layer denatured by ion implantation for a controlled contact time, and then, allowing activated plasma to attack it. CONSTITUTION:In peeling the resist contg. the surface layer denatured by ion implantation from the object 6 to be worked by using the resist as a mask and injecting ions, gaseous plasma nonreacting with the object 6, such as argon plasma, is allowed to attack it for a controlled time length so as to leave the resist on the object 6, and after removing a part of the resist, the object 6 is set at an afterglow discharge chamber 1. Oxygen contg. a fluorocarbon type gas is introduced into a glow discharge chamber 3, excited with microwaves, converted into plasma, passed through a metallic screen, converted into an activated type, and brought into contact with the object 6, thus permitting the residual resist to be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for stripping a resist used as a mask from a workpiece into which ions have been implanted.

BACKGROUND OF THE INVENTION A wet or dry method is used to remove the resist from a wafer chip in which ions have been implanted using a resist as a mask. The wet method is dangerous to handle depending on the chemicals used, is expensive, and cannot be used when the amount of ions implanted is large because it does not peel off. There are methods using plasma, and so-called afterglow discharge, that is, methods that utilize active species generated by plasma without directly touching the plasma.

In normal plasma, the workpiece is heated to about 300°C, which has the disadvantage of burning the resist, but afterglow has the advantage of being able to process at temperatures as low as room temperature to around 70°C. However, the surface layer altered by ion implantation or the like cannot be removed.

Problem: When a resist on a workpiece into which ions have been implanted is treated with active species, special treatment is required to remove the surface layer of the resist that has been altered by the ion implantation.

Solution The above problem is solved by a method of stripping the resist, including the surface layer altered by ion implantation, from a workpiece into which ions have been implanted using the resist as a mask. After removing a portion of the resist by controlling the contact time to such an extent that at least the resist on the object remains, an oxygen plasma containing fluorinated carbon gas is passed through a metal mesh to generate active species from the plasma. This problem can be solved by a resist stripping method in which the resist gold remaining in the previous plasma treatment is removed using the activated species.

Example Positive resist on silicon wafer (manufactured by Tokyo Ohka).

FPR800 (trade name) was coated, patterned and used as a mask, and P ions were accelerated with LookeV and implanted into the wafer at a density of 1×10 ions/cm”.

The surface of the resist was altered to a depth of several hundred.

The wafer with this resist surface deteriorated was heated to 0.05 Torr.
The sample was exposed to argon plasma for a period of time long enough for at least the resist on the workpiece to remain.

The contact time at this time was 10 seconds. This level of treatment does not cause the renost to burn, and on the other hand, the surface layer can be removed or easily absorbed by the plasma converted into active species in the next afterglow discharge chamber. Note that oxygen can also be used for plasma instead of argon.

A device having an afterglow discharge chamber 1 as schematically shown in FIG.
Oxygen plasma containing fluorinated carbon gas used for etching and etching is a well-known technique.

The after-glow discharge chamber 1 communicates with a glow discharge chamber 3 through a plurality of windows 2t- made of aluminum mesh with a mesh size of 2 ml, and this glow discharge chamber 3 has walls 4 of alumina made of dielectric material.
It adjoins the microwave generation chamber 5 through the t-. A 0□-51% CF4 mixed gas of 1.5 Torr is introduced into the glow discharge chamber 3 and discharged from the afterglow discharge chamber 1. The mixed gas in the glow discharge chamber 3 is excited by a 1 kW microwave and becomes plasma. When the plasma passes through the aluminum screen window 2, it changes into active species that have lost most of their charge.

The wafer 6 having the resist that had been previously plasma-treated was placed in the afterglow discharge chamber 1 and brought into contact with the active species for 30 seconds. As a result, the wafer was not damaged and the resist could be ashed without burning.

Effects of the Invention The Lennost stripping method of the present invention first applies a plasma of a gas that does not react with the workpiece by controlling the contact time to such an extent that at least the resist remains on the surface of the workpiece. So that the stone never scorches and resists. Furthermore, a resist having a surface layer altered by ion implantation can be easily ashed by afterglow discharge plasma, that is, plasma transformed into active species.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an afterglow discharge device used in the method of the invention. 1... Afterglow discharge chamber, 2... Metal mesh window, 3
. . . Glow discharge chamber, 4. Dielectric wall, 5. Microwave generation chamber, 6. Wafer.

Claims (1)

[Claims] 1. A method of stripping the resist, including the surface layer altered by ion implantation, from a workpiece into which ions have been implanted using the resist as a mask. After removing a portion of the resist by controlling the contact time to such an extent that the resist remains, active species are extracted from an oxygen plasma containing fluorinated carbon gas through a metal mesh, and with this active species,
A resist stripping method characterized by removing resist remaining in a previous plasma treatment.