JP2856562B2 - Insulation film inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a semiconductor device, and more particularly to a method for inspecting an insulating film.

[0002]

2. Description of the Related Art In semiconductor devices, wiring and electrodes are insulated,
Alternatively, an insulating film is formed for protection, and this insulating film is important in determining characteristics of the semiconductor device. For this reason, inspection of the insulating film is performed, and an inspection apparatus as shown in FIG. 7 is conventionally used. This apparatus, for example, as shown in FIG.
The sample 21 on which the sample 3 is formed is irradiated with X-rays by an X-ray tube 24, and a secondary X-ray emitted from the sample 21 is set in accordance with the angle of each element. And a phosphor counter tube 26 are arranged to measure the respective intensities, and the thickness of the film is determined by converting the measurement result into the concentration of impurities in the film, thereby determining the state of the insulating film.

[0003]

Since the above-mentioned conventional method for detecting an insulating film is an X-ray method, it is not an actual semiconductor device, but an inspection using a sample having an insulating film formed on a substrate. It is. For this reason, it is difficult to detect the flatness of the insulating film that reflects the difference in the underlying electrode width, electrode spacing, and the like. Further, in the actual semiconductor device manufacturing process, after the insulating film is formed and adhered, a nitrogen treatment at 900 ° C. to 950 ° C. is performed and reflow is performed. I couldn't understand the impact of the processing,
There is also a problem that an accurate inspection cannot be performed. An object of the present invention is to provide an inspection method capable of inspecting the flatness and other states of an insulating film of an actual semiconductor device.

[0004]

According to the method for inspecting an insulating film of the present invention, a second insulating film covering a wiring layer formed on a semiconductor device is provided.
After a reflective film is applied on the surface of the film , He-Ne laser light is irradiated, the light intensity of the reflected light from the reflective film is detected by a detector, and the second absolute value is detected based on the detected output. By determining the state of the edge film, the flatness and other states are inspected. Here, the second insulating film is made of phosphosilicate glass.
It is a film or a phosphorus-boron silicate glass film. In addition,
The reflection film is a tungsten film.

[0005]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an insulating film inspection apparatus according to the present invention.
In FIG. 1, reference numeral 1 denotes a semiconductor device to be inspected. For example, as shown in FIG. 2, this semiconductor device forms a polycrystalline silicon electrode wiring 4 on a surface insulating film 3 of a substrate 2, It is assumed that an insulating film 5 such as a phosphosilicate glass film or a phosphorus-boron silicate glass film is formed to cover the electrode wiring 4, and a tungsten upper layer film 6 is further formed thereon.

[0006] The inspection apparatus has a He-Ne laser light source 11, and outputs the laser light to a lens 12 and a beam splitter 1.
3 and is projected on the surface of the semiconductor device 1. Further, the scattered light of the laser light reflected from the surface of the semiconductor device 1 is reflected by the beam splitter 13 and detected by the detector 16 through the lens 14 and the slit mask 15. Then, by performing signal processing on the detection output of the detector 16, the light intensity of the scattered light can be detected. The semiconductor device 1 can move at a constant speed and is configured to scan with a laser beam.

According to this configuration, the He-Ne laser light is focused on the surface of the semiconductor device 1 moving at a constant speed, and the scattered light is detected by the detector 16 so that the scattered light is converted into the insulating film. Since the strength differs depending on the flatness of No. 5, the flatness of the insulating film can be inspected by this strength.

For example, a thermal oxide film is grown on a silicon semiconductor substrate at a thickness of 1000.degree., And polycrystalline silicon is deposited on the oxide film by a vapor deposition method at a thickness of 4000.degree.
A 1.0 μm electrode wiring is formed. A phosphorus-boron silicate glass film is formed thereon by vapor phase epitaxy (5 mol% of phosphorus, 14 mol% of boron), (5 mol% of phosphorus, 10 mol% of boron), (5 mol% of phosphorus, 5 mol% of boron, (6 mol%) of three kinds of insulating films are deposited at 4000 ° C., and are subjected to nitrogen treatment at 900 ° C. for 30 minutes to reflow, and then tungsten is deposited by a sputtering method to prevent light transmission. Thus, FIG.
(A), the first to third samples shown in FIGS. 4 (a) and 5 (a) were prepared.

Then, when the intensity of the scattered light of the laser beam is measured for these samples in the inspection apparatus shown in FIG. 1, the intensity of the first sample shown in FIG. 3A becomes as shown in FIG. 3B. Constant, no peak value. FIG. 4 (a)
Assuming that the intensity of the second sample of FIG.
A strength of 20 was obtained. Similarly, the intensity of the third sample in FIG. 5A was 50 as shown in FIG. 5B. It can be seen that the better the flatness is, the lower the strength is.

Further, as shown in FIG. 6, when the sum of the phosphorus concentration and the boron concentration is plotted on the horizontal axis and the intensity is plotted on the vertical axis, there is a strong correlation between the two. According to the method, it can be seen that not only the flatness of the insulating film but also the impurity concentration can be inspected.

[0011]

As described above, according to the present invention, light is reflected on the surface of the second insulating film covering the wiring layer formed on the semiconductor device.
After the film is applied, the reflected light of the He—Ne laser beam applied to the reflective film is detected, whereby the second insulating film is formed.
Depending on the concentration of impurities contained in the film,
The flatness of the second insulating film can be inspected by utilizing the degree of drooping of the film , and the impurity concentration of the insulating film can be inspected at the same time, and the state of the insulating film can be inspected with high accuracy. There is an effect that can be .

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an inspection apparatus for performing an inspection method of the present invention.

FIG. 2 is a sectional view showing an example of the semiconductor device inspected in FIG.

FIGS. 3A and 3B are diagrams showing a first sample according to the present invention and a signal intensity thereof. FIG.

FIGS. 4A and 4B are diagrams showing a second sample and the signal strength thereof according to the present invention.

FIGS. 5A and 5B are diagrams showing a third sample and the signal strength thereof according to the present invention.

FIG. 6 is a diagram showing a correlation between an impurity concentration and a signal intensity.

FIG. 7 is a schematic configuration diagram showing an example of a conventional inspection method.

FIG. 8 is a sectional view of a sample used in a conventional inspection method.

[Description of Signs] 1 Semiconductor device 5 Insulating film 11 He-Ne laser light source 13 Beam splitter 16 Detector

Claims (3)

(57) [Claims] A first insulating film formed on a main surface of the substrate;
In a semiconductor device having a wiring layer and a second insulating film covering the wiring layer, the semiconductor device has a reflection on a surface of the second insulating film.
Film deposited and irradiated with a laser beam from a He-Ne laser light source to the surface of the reflective film, anti from said reflective film
Inspection method of the insulating film, which detects the light intensity of the morphism light detector, to determine the state of the second insulating film on the basis of the detection output. 2. The method according to claim 1, wherein the second insulating film is a phosphosilicate glass film,
Or a phosphor-boron silicate glass film.
Inspection method for insulating film . (3) The said reflection film is a tungsten film
Item 3. The inspection method for an insulating film according to item 1 or 2.