JPS58108744A - Manufacture of integrated circuit - Google Patents

Abstract

PURPOSE:To improve the adhesion of resist to substrate by a method wherein a substrate surface is sputteretched by means of appropriate plasma. CONSTITUTION:A substrate holder 2 fitted with the substrates 1 subject to cleaning process is fixed to a high frequency electrode 3 making the space in chamber 8 vacuum by ordinary means. The gas supply unit 6 supplies the chamber 8 with Ar or O2 gas up to the pressure of 1X10<-4>-1X10<-3> Torr and then the pressure in said chamber 8 is changed to 5X10<-3>-1X10<-1> Torr by means of adjusting the opening of the main valve 7. With this pressure sustained constantly, the high frequency electrode 3 is supplied with high frequency power to produce Ar or O2 plasma. The substrate after cleaning process for 5-10min may be coated with resist without heating and drying process as well as processing interfacial activator.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for manufacturing an integrated circuit, particularly a thin film integrated circuit,
In particular, it relates to the photolithography process.

The purpose of this invention is to improve the adhesion of photoresist to a substrate and to stably obtain fine patterns.

For example, the adhesion of Sibley's AZ photoresist to a substrate is greatly affected by humidity. In other words, the presence of moisture at the interface between the substrate and resist significantly reduces the adhesion. Conventionally, just before coating the resist, the substrate was immersed in dry air or a gas such as nitrogen for 10 minutes.
The surface was dried by heating at 0 to 150°C. This method removes some of the adsorbed moisture and somewhat improves the adhesion of the resist to the substrate. But 100～
Heating to 150°C has a variety of undesirable effects on the thin film already formed on the substrate, including the following:
A temperature of 0'C brings about physicochemical changes in the #1 pattern already formed on the substrate. Such thermal effects are particularly noticeable in the manufacture of Josephson integrated circuits made of low melting point metals (PI). Further, after heat treatment is performed for a certain period of time, it is necessary to cool the material in a dry gas stream to prevent water from being re-adsorbed by cooling. After cooling, a surface treatment with a surfactant is required, and then a resist must be applied in a relatively short period of time in a clean room with low humidity. In this way, it is necessary to carry out the steps from heat treatment to resist coating in a continuous time-controlled manner on a minute-by-minute basis in order to avoid deterioration of adhesion.

In a process that does not require the resist to have an overhang shape, sufficient adhesion can be obtained with this conventional method. However, in the manufacture of thin film integrated circuits such as Josephson integrated circuits, monochlorobenzene immersion treatment is necessary to give the resist an overhang shape, but when this treatment is performed, it affects the adhesion of the resist to the substrate. Traditionally, this is also emphasized. That is, 1
Even if baking is performed for drying at 00 to 150° C., peeling of the resist may occur if the monochlorobenzene immersion treatment is performed in an environment with a humidity of 50° C. or more.

The present invention aims to simplify the resist coating process, which requires careful process control, and to achieve better adhesion than the conventional resist coating process.

Before applying the resist, the substrate is placed in a plasma processing apparatus, and the surface of the substrate is subjected to a lath halter etching process using plasma of an appropriate gas. This cleaning treatment significantly improved the adhesion of the resist to the substrate.

Further, even when monochlorobenzene immersion was carried out in an environment with a humidity of 70% or higher, there was no peeling of the resist. Further, by carrying out the present invention, the resist coating process is greatly simplified, since the baking of the drying pot, the accompanying cooling process, and the surface treatment process using a surfactant, which were conventionally performed, are not necessary. There is no need to particularly strictly control the time period from when the surface is purified by plasma to when the resist is applied after being taken out from the chamber. It was experimentally confirmed that no deterioration in the adhesion of the resist was observed even when the resist was left in the air at 70% humidity for 5 hours. One of the advantages of this invention is that time management is easy in this way.

In order to carry out the plasma purification treatment of the surface of a substrate according to the present invention, it is ideal to use a processing apparatus provided with a high frequency electrode to which the substrate can be attached. This is because the negative DC bias voltage generated at the high frequency electrode can be controlled arbitrarily. If such a device is not available, plasma can be obtained by installing a discharge electrode and a neon transformer in an ordinary vapor deposition device. In this case, the location of the substrate and the potential distribution of the plasma are different from those using high-frequency electrodes.
It also has the disadvantage of poor controllability.

The present invention will be explained in more detail with reference to examples below. In the drawing, a substrate holder (2) on which a substrate (1) to be subjected to cleaning treatment is mounted is attached to a high frequency electrode (3), and a vacuum is obtained in a conventional manner. The drawing shows a vacuum device that uses an exhaust system that combines an oil rotary pump (4) and an oil diffusion pump (5). Gas supply device (6) to A
r or 02 gas at 1×10-4 to 1×1O-3 Tor
Introduce the pressure up to r. It is desirable that this introduction pressure be within the normal operating range of the exhaust system used. Next, adjust the opening degree of the main valve (7) to reduce the pressure in the chamber (8) to 5.
Set to X 10-3 to I X 10' Torr.

While maintaining this pressure stably, high frequency power is supplied to the high frequency electrode (3) to generate Ar or 02 plasma. The high frequency power at this time is 1 to 2 W, and the DC bias voltage is -50 to -100V.

Increasing the high frequency power will further enhance the cleaning of the substrate surface, but this is undesirable since it may damage the surface features due to etching.

After completing the cleaning process for 5 to 10 minutes, the supply of high frequency power and the introduction of gas are stopped, the pressure in the chamber is brought to atmospheric pressure, and the substrate is taken out. A substrate subjected to plasma cleaning treatment can be coated with a resist with excellent adhesion without undergoing a heating drying process or a surfactant (eg, hexamethyldisilazane) treatment process.

Even if these two steps were omitted, no peeling was observed at the interface between the resist and the substrate after immersion in chlorobenzene, indicating that the plasma cleaning treatment has a great effect on the adhesion of the resist to the substrate. This effect of improving adhesion is particularly noticeable when resist is applied on the SiO thin film.

In the production of thin film integrated circuits, the layers are stacked by a photolithography process, a thin film formation process mainly by vapor deposition, and a lift-off process, so the influence on the mechanical and electrical properties of the interface between the films cannot be ignored. The plasma cleaning treatment according to the present invention is originally intended to improve the adhesion of the resist, but it is necessary to remove minute resist residues from lift-off for the previous circuit formation prior to the resist coating process for the next circuit formation. It has the effect of completely removing it.

As described above, implementing the present invention provides the following advantages.

Improved resist adhesion improves the efficiency of the integrated circuit manufacturing process and improves product yield. In addition, since there is no need to use a surfactant, electrical characteristics can be stabilized due to cleaning of the laminated thin film interface by not using it, and there is no need to include a heating drying process, so do not include it. Accordingly, thermal damage to the integrated circuit can be reduced. Furthermore, since the present invention requires simple components as described above, it can be easily incorporated into existing vacuum equipment or in-line automated manufacturing equipment.

[Brief explanation of the drawing]

The drawing is a configuration diagram showing an example of a processing apparatus for carrying out the plasma processing of the present invention. (1) =-substrate, (2)-substrate holder, (3)-high frequency electrode, (4)--oil rotary pump, (5)-oil diffusion pump, (6)-gas supply device, (ma)- main valve,
(8)-・Chamber, (9)-m-DC bias voltage monitoring device, (10)-impedance matching device, 01)-
High frequency power supply, (Mizu - Vacuum gauge. Agent Makoto Kuzuno)

Claims (1)

[Claims] 1. A method for manufacturing an integrated circuit, which comprises subjecting the surface of a substrate to plasma treatment before applying photoresist to the substrate in a pattern photolithography process.