JPS6240735A - Film thickness monitoring method - Google Patents

Abstract

PURPOSE:To enable a non-destructive inspection by coating a film with a pattern having a step of a monitoring pattern, then observing by an optical microscope from above a substrate, and measuring the film thickness coated on the side of the step as a plane size in the microscope visual field. CONSTITUTION:The ratio of the thickness of a film coated on a plane surface to that of a film coated on the side of a step always becomes constant if physical conditions at coating time such as a material of the film, a coating principle and the type of a coating machine are secured. When observing from above the film thickness monitoring pattern after film coating, the width of the monitoring pattern is observed to be increased due to the film coating on the side of the step. Thus, if the end W1 of the monitoring pattern is obtained in advance, the width of the monitoring pattern after film coating is observed by the microscope to monitor the film thickness coated on the plane surface.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a film thickness monitoring method. The present invention relates to a film thickness monitoring method suitable for film deposition processes for manufacturing semiconductor devices.

[Conventional technology]

Metal films and dielectric films are used in the manufacturing process of semiconductor devices.

There are several steps for depositing semiconductor films, etc., and the required thickness for each step is determined. Methods for monitoring the thickness of such films include optical monitoring methods such as ellipsometry and optical interferometry for transparent films such as SiO*, S1, N4, etc., and optical monitoring methods such as optical interference method for opaque films such as metals. For such films, methods have been used in which a part of the deposited film is removed to create a step, and this is monitored by a stylus method or an optical interference method, respectively.

[Problem that the invention seeks to solve]

All of the conventional film thickness monitoring methods described above have the disadvantage of requiring a dedicated and expensive film thickness measuring device.

Another problem is that the above-mentioned monitoring method for opaque films is a destructive inspection method that removes a portion of the deposited film, requires man-hours to remove the deposited film, and takes time to monitor the film thickness. .

An object of the present invention is to provide a film thickness monitoring method that solves these problems.

[Means for solving problems]

The film thickness monitoring method according to the present invention is a film thickness monitoring method in which a film thickness monitoring pattern is formed on a substrate, a film is deposited, and then the deposited film thickness is determined using the monitoring pattern.
The monitor pattern has a step, and after the crotch has been applied, the monitor pattern is inspected from above the substrate using an optical microscope, and the thickness of the film deposited on the side surface of the step is measured as the planar dimension in the microscope field. However, there is a method for determining the deposited film thickness, especially when the film thickness monitoring pattern is a groove pattern with a predetermined width corresponding to the desired film thickness in the film deposition process, or a group of groove patterns with a plurality of different widths. This is a film thickness monitoring method that can further facilitate film thickness monitoring.

[Effect]

The ratio of the thickness of the film deposited on a flat surface to the thickness of the film deposited on the side of a step depends on the material of the deposited film and the principle of deposition.

If the mechanism of the deposition device and the physical conditions at the time of deposition are fixed, it will always be constant. When observing the film thickness monitoring pattern from above after the film has been deposited, it appears that the width of the film thickness monitoring pattern has increased due to the film being deposited on the side surface of the step. Therefore, if the width of the film thickness monitoring pattern is determined in advance, the thickness of the film deposited on a flat surface can be monitored by measuring the width of the film thickness monitoring pattern using a microscope after the film has been deposited. can do.

[Example 1] An example of the present invention will be described below with reference to the drawings. Figure 1 (a), (b) and Figure 2 (al, (b)
) are drawings for explaining the first embodiment of the present invention in the order of steps; FIG. 1 is a plan view, and FIG. 2 is a sectional view taken along line XX in FIG. 1. 1 in Figure 1(a) and Figure 2(a)
1 is an Sl substrate, and 21 is a 1.5μ thick layer formed on this.
This is a film thickness monitoring pattern made of a SlO film of m.

The pattern width W1 was 4 μm. Next, an AI film 31 was deposited thereon by sputter deposition (FIGS. 1(b) and 2(b)). The deposition device is of a magnetron sputtering type, and the diameter of the AI target is 150 mm. The deposition conditions are sputtering gas (Ar) pressure 5Pa and gas flow rate 80S.
CCM, sputtering power 500W, electrode spacing 5Qmm, and sea urchin rotation speed 6 rpm were used. When these deposition conditions are used with this device, the ratio of the AJ deposited film thickness on the step side and the deposited film thickness on the flat surface is is 1:1.2. The width W of the film thickness measurement pattern after the Al film was deposited was measured using an optical microscope and a scale, and the width W was 6.4 μm. Wl #)
The value obtained by subtracting Wl (2.4 μm) is the value of A deposited on the side surface of the step.
Since this is twice the thickness of the Al film, the thickness of Al deposited on a flat surface is
It is no longer necessary to remove part of the Au film as in the conventional method.

[Embodiment 2] Figures Is), fb), and fc) are plan views for explaining another embodiment of the present invention. In the same figure (al), 22 is a film thickness monitoring pattern formed of 810. with a thickness of 2 μm, and the central part 222 is a groove with a width of 3 μm.The entire surface including the semiconductor substrate 12 has a thickness of 0.
．． After covering with a very thin laminated gold F4 film made by successively a1Mf of Tl and Au with a thickness of 05 μm, a non-cyanide plating solution (trade name Kou Aetronex 201) was heated to 60t3, and a prismatic shape with an inner bottom dimension of 200mm x 200mm was formed. In a Teflon container, while stirring at a flow rate of 1017 seconds, the pole spacing was 18! Electrolytic gold plating was applied while maintaining the Mfm.

Under such conditions, the ratio of the total thickness of the step side surface to the total thickness of the flat portion is 1:1. The thickness of the Au film in the flat portion can be monitored by measuring the change in the width of the film thickness pattern in the same manner as in the second embodiment.

Figure 3 (CL continues plating and the plating thickness is 1.6 μm.
It is a top view when it becomes m. The central part of the film thickness monitor, where a groove with a width of 3 μm had been formed, was blocked due to the adhesion of the gold film to the side surfaces of the step. In this way, by paying attention to whether or not the groove was filled, it was possible to very easily monitor whether the film had been deposited to a predetermined thickness or more without using a scale.

If the film thickness monitoring pattern shown in FIG. 4 is used instead of the film thickness monitoring pattern shown in FIG. 3 (al), film thickness monitoring can be performed even more easily.

In Fig. 4, 23 is a film thickness monitoring pattern formed of S50 with a thickness of 2 μm, and the groove width is from 1 pm to 5 μm.
It changes in 5 steps in 1 μm increments up to m. If we examine the pattern in which the grooves are closed after the film is deposited, it will be 1 pmlD.
It was possible to easily determine the thickness of the deposited film with accuracy just by observing it with a microscope.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, film thickness can be monitored using an optical microscope without using a dedicated and expensive film thickness measuring device. In addition, there is no need to remove the adhered film, which was required in conventional opaque film thickness monitors.
The effect is great because non-destructive testing can be performed.

[Brief explanation of the drawing]

FIG. 4 is a plan view for explaining a second embodiment of the present invention. 11.12.13...Semiconductor substrate, 21.22.23
... Film thickness monitoring pattern, 31... Deposited film. many mouths

Claims (3)

[Claims] (1) In a film thickness monitoring method in which a film thickness monitoring pattern is formed on a substrate and a film is deposited, the thickness of the deposited film is determined using the monitoring pattern. After the film is deposited, the monitor pattern is observed using an optical microscope from above the substrate, and the thickness of the film deposited on the side surface of the step is measured as a planar dimension in the field of view of the microscope. A film thickness monitoring method characterized by: (2) The film thickness monitor according to claim 1, wherein the step pattern for film thickness monitoring includes a groove pattern with a predetermined width corresponding to a desired film thickness in a film deposition process. Law. (3) The film thickness monitoring method according to claim 1, wherein the step pattern for film thickness monitoring includes a plurality of groove pattern groups having different dimension widths.