JPS6381826A - Device for detecting end point of ion milling process - Google Patents

Abstract

PURPOSE:To enable detect a end point of an etching by measuring a current flowing into a wafer stage during an ion milling process. CONSTITUTION:A wafer stage 1 insulated by an insulator 2 is provided opposing to a chamber wall 5 of an ion milling apparatus while the wafer stage 1 is made smaller than a wafer 6 on to be exposed to ion during ion milling process. A bias power supply 3 supplys bias voltage to be supplied for the wafer stage 1. At this time, the bias voltage can be set up to be converted either into positive or negative. Furthermore, can ampere meter to measure the current flowing from the wafer stage 1 is provided. The wafer 6 is placed on the wafer stage 1 insulated from the chamber wall of ion milling apparatus to supply the wafer stage 1 with bias voltage for measuring the current flowing from the wafer stage 1 during ion milling process. Through these procedures, the current will be changed at an end point of etching so that the end point of etching can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to an end point detection device for ion milling during wiring formation.

[Conventional technology]

In order to form wiring for semiconductor devices, metal is deposited on the entire surface of the wafer, a resist pattern is formed on it, and then
A method is used in which metal parts unnecessary for wiring are etched by ion milling. At this time, it is necessary to detect the end point of etching the metal part. Conventionally, as a method for detecting the end point, there is a method of detecting the metal species sputtered by ion milling and detecting the end point from a change in the signal. Methods for detecting metal species include (1)
There are two methods: (2) detecting sputtered metal by mass spectrometry; and (2) detecting specific fluorescence induced by a laser. Another method is to provide a diffraction grating in the wiring pattern, measure the interference caused by the laser, and detect the end point based on the change in the vicinity of the end point. Furthermore, a method has been considered in which two metal pads are provided in the wiring pattern, which are electrically insulated after the metal portion is etched, and a change in resistance near the end point is detected.

[Problem that the invention seeks to solve]

The conventional end point detection method for detecting sputtered metal has problems such as expensive equipment and low detection sensitivity. Furthermore, the method of forming a specific pattern for detecting the end point on a wiring pattern also has the problem that unnecessary portions must be created on the wafer in terms of device fabrication.

This invention was made to solve the above-mentioned problems, and it is possible to easily detect the end point at low cost.
The purpose of the present invention is to obtain an end point detection device for ion milling that can detect the end point without special work on a wafer.

[Means for solving problems]

The end point detection device for ion milling according to the present invention places a wafer on a wafer stage insulated from the chamber wall of an ion milling device, applies a bias voltage to the wafer stage, and detects the flow from the wafer stage during ion milling. This makes it possible to measure the current that flows.

[Effect]

In this invention, the bias voltage has the effect of introducing or excluding secondary electrons generated during ion milling into the current measurement system. The measurement current changes before and after the end of etching due to the difference in the generation rate of secondary electrons between the metal part and the underlying insulating layer exposed to ions at the end of etching, and due to charge-up, making it possible to detect the end point.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

The drawing is a block diagram of an apparatus for detecting the end point of etching metal wiring by ion milling, showing an embodiment of the present invention. In this embodiment, as shown in the figure, a wafer stage 1 is provided which is insulated from a chamber wall 5 of an ion milling device with an insulator 2, and this wafer stage 1 is protected from being exposed to ions during ion milling. It is smaller than wafer 6. The bias voltage applied to the wafer stage 1 is supplied by three bias power supplies. At this time, the bias voltage can be set to be variable between positive and negative.

Furthermore, an ammeter 4 capable of measuring the current flowing from the wafer stage 1 is provided.

Next, the operation will be explained.

The current flow in and out on the wafer 6 during ion milling is (
1) Current of incident ions, (2) Current of sputtered metal particles with charge, (3) 2 generated during ion injection.
It is the sum of three secondary electron currents.

Among these, (2) and (3) above differ depending on the material. Therefore, a change in current occurs at the end point of etching, making it possible to detect the end point.

Here, the bias voltage is generated from the 6th surface of the wafer (
2) Set so that the sum of the currents in (3) is the largest. That is, in order to prevent the generated secondary electrons from re-entering the wafer 6, the wafer 6 should be set at a negative voltage, and in order to prevent positively charged sputtered particles from re-entering the wafer 6, the wafer 6 should be set to a It is sufficient to set the voltage, taking these into consideration. Furthermore, since charge-up occurs at the end point of etching depending on the pattern on the wafer 6, this can also be interpreted as a change in current, making it possible to detect the end point.

In the above embodiment, a bias voltage is applied to the wafer stage 1 and the chamber wall 5 is grounded, but the same effect can be obtained by simply connecting the ammeter 4 to the wafer stage 1 and applying a bias voltage to the chamber wall 5. brings about the effect of

〔Effect of the invention〕

As explained above, this invention is configured to detect the end point of etching by measuring the current flowing into the wafer stage during ion milling, so the equipment can be made at low cost and does not require any special modifications to the wafer. This has the advantage that end point detection can be realized.

[Brief explanation of the drawing]

The drawing is a schematic configuration diagram of an ion milling end point detection device showing an embodiment of the present invention. In the figure, 1 is a wafer stage, 2 is an insulator, 3 is a bias TLB, 4 is an ammeter, 5 is a chamber wall, and 6 is a wafer.

Claims (1)

[Claims] A wafer stage insulated from the chamber wall of an ion milling device, a constant voltage source that can change the bias voltage applied to the wafer stage, and changes in the ion current incident on the wafer placed on the wafer stage are measured. An end point detection device for ion milling, characterized by being equipped with an ammeter to detect the end point of ion milling.