JPS5843901B2 - Plating thickness measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method suitable for measuring the thickness of a plating layer formed on a semiconductor device.

In general, in semiconductor devices, required portions are often plated with metal to form electrodes and wiring.

However, since there is no appropriate means to relatively accurately and easily measure the plating thickness, it is difficult to measure the plating thickness with tolerances that greatly exceed the electrical and mechanical properties required for electrodes and wiring. It is formed.

However, if these electrodes and wiring are made of inexpensive materials, there will be no problem, but if gold-Au is plated, as in the case of beam-lead type semiconductor devices, for example, it will have a significant impact on the cost. .

Normally, the beam lead is 10 to 20 μm, and the internal wiring is 1
Gold plating is applied to a thickness of ~5 capes.

It is not that the thickness of metal plating on semiconductor devices has not been measured in the past, but since the surface of semiconductor devices is often uneven and the patterns are minute, it is difficult to measure the thickness of metal plating on semiconductor devices. It is difficult to use mechanical methods such as

The present invention relies on microscopic observation, relatively accurately, and
This allows the plating thickness to be easily measured, and will be explained in detail below.

Generally, if a pattern is formed using a photoresist film with a thickness of tμm on the part to be plated, and then gold plating is performed with a thickness of tμm, the plating in each pattern will be perpendicular to the thickness from the edge of the pattern. t in the direction
-t pμm is known to spread.

The present invention utilizes this phenomenon.

That is, at least two monitor patterns are placed side by side at the same time using a photoresist film at appropriate locations on a semiconductor device using a predetermined photomask, and then those patterns are plated at the same time as the electrodes, wiring, etc. are plated. The plating thickness is determined based on the size of the gap between each pattern due to the plating film.

Since the gaps between each pattern are formed using the same photomask, they can be formed uniformly with high precision, and it is easy to know the dimensions in advance.

The extent to which the pattern gap narrows due to plating is to be observed with a microscope at any time during the plating process.

Figure 1 is a plan view of the vicinity of the pattern used to measure plating thickness, Figure 2 is a sectional view taken along line A-A', and Figure 3 is taken along line B-
Each of the cross-sectional views at B' is shown, and ad represents the progress of the plating process.

Refer to a. It is now assumed that a silicon dioxide film 2, a titanium film 3, and a platinum film 4 are formed on a silicon semiconductor substrate 1.

Incidentally, since the titanium film 3 is a part of the electrode/wiring, it goes without saying that it is in contact with the substrate 1 through the electrode contact window formed in the silicon dioxide film 2 at an appropriate location.

Now, a photoresist film 5 is formed on the platinum film 4, and the photoresist film 5 is patterned to form a monitor pattern 6.7 at the same time as a desired plating pattern.

Note that the pattern 6 has a notch 6A on the edge opposite to the pattern 7.

This notch 6A is for measuring the limit value of the plating thickness, but it may not be formed if the measurement does not require much precision.

Note that although the pattern 6.7 in this example is based on a rectangle, its shape is not limited to this.
The point is that the gap between the two patterns can be maintained constant and can be easily observed.

In this example, the distance l in Figure 2 a is 26 μm1 in Figure 3 a
Pattern 6.7 was formed so that the distance l' was 32 μm.

Further, the thickness of the photoresist film 5 is 0.5 μm, and it is intended that the entire film 8 will ultimately have a thickness of 15±1.5 μm.

See b. The plating thickness in the illustrated example is 13.5 μm or less.

See C. The plating thickness in the illustrated example is 15±0.5 μm.

In this case, the ease of visual inspection due to the effect of the notch 6A is remarkable.

d reference The plating thickness in the illustrated example is 16.5 μm or more.

Therefore, it is best to complete the plating work in state C.

In the above embodiment, there were two monitor patterns, 6 and 7, but the number can be selected appropriately.

For example, if pattern 6 is divided into two,
Stop the formation of the notch 6A for determining the plating limit value, appropriately select the gap formed between the two patterns 6,
The limit value can also be determined by comparing the degree to which the gap is filled by gold plating and the degree to which the gap between pattern 6 and pattern 7 is filled.

Further, the present invention is not limited to the embodiments, and can be applied to general measurement of plating thickness.

As can be seen from the above explanation, according to the present invention, at least two monitor patterns are formed at appropriate locations on a semiconductor device at the same time as a desired plating pattern, and the state of plating with respect to the monitor patterns is visually observed. Since the plating thickness can be determined fairly accurately and easily, there is no need to perform unnecessary plating that greatly exceeds the required properties, which not only shortens manufacturing time, but also improves the plating material. This is a great way to reduce costs when the cost is high.

[Brief explanation of the drawing]

FIG. 1 a = d is a plan view of the main part of a semiconductor device for explaining the process of implementing an example of the present invention, and FIGS.
A cross-sectional view taken along the line A-A' in the figure, and FIG. 3 a=d represent a cross-sectional view taken along the line B-B' in FIG. 1, respectively. In the figure, 1 is a substrate, 2 is a silicon dioxide film, 3 is a titanium film, 4 is a platinum film, 5 is a photoresist film, 6 and 7 are patterns, 8 is the entire film, and 6A is a cutout.

Claims (1)

[Claims] 1 Form a photoresist film on the substrate, and
The resist film is patterned to form at least two monitor patterns facing each other at a predetermined interval, and then the monitor patterns are simultaneously plated on the areas that require plating.
A plating thickness measuring method characterized in that the plating thickness is measured by plating the patterns and observing the state in which the gap between the monitor patterns is narrowed by the plated metal.