JPH0313542B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for evaluating the film quality of an insulating film used in a semiconductor element.

[Conventional technology]

Traditionally, this type of device was called ellipsometry and polarized light (“ELLIPSOMETRY AND POLARIZED”).
LIGHT”，RMAAZZAM AND NM
BASHARA, NORTH−HOLLAND
PUBLISHING COMPANY−AMSTERDAM,
NEW YORK, OXFORD, 1977, page 412), which is shown in FIG. In the figure, 100 is a sample whose film quality is to be evaluated, 1 is a measurement light source that emits light of a single wavelength,
2 is a polarizer that polarizes the light from the measurement light source 1;
3 is an additional 1/4 wavelength plate used when it is desired to change the phase of the light that has passed through the polarizer 2; 4 is an aperture that regulates the cross-sectional shape of the light;
61 is an analyzer rotated at a constant speed by a synchronous motor (not shown); 62 is the rotation angle θ of the analyzer 61; 6 is a rotary analyzer configured by integrating an analyzer 61 and an angle encoder 62, 7 is a photoelectric detector that detects the intensity of light passing through the rotary analyzer 6, and 8 is a rotary analyzer. An A-D converter 9 converts an analog signal regarding the light intensity from the photoelectric detector 7 into a digital signal by means of data pulses regarding the angle from the photon 6; This computer receives a start pulse signal from the angle encoder 62 indicating the initial angle of the sample 100, and calculates the film thickness and refractive index of the sample 100.

FIG. 6 shows details of the sample 100. In the figure, 101 is an insulating film, and 102 is an insulating film 101.
is the substrate formed on the top surface.

Next, the operation will be explained. After the light from the measurement light source 1 is polarized by the polarizer 2, it is applied to the sample 1.
A certain angle with respect to the normal to the insulating film 101 surface of 00,
In this case, the beam is incident on the sample 100 at an angle of 70°. This incident light is reflected by the sample 100, and the rotating analyzer 6
The light passes through the analyzer 61 and enters the photoelectric detector 7 . When the analyzer 61 begins to rotate by the synchronous motor,
The angle encoder 62 outputs a start pulse signal S1 shown in FIG. 7a, and also outputs a plurality of equally spaced data pulses S2 shown in FIG. Vessel 7
outputs an analog signal S3 shown in FIG. 7c.

The analog signal S3 is converted by the data pulse S2 into the digital signal S4 shown in FIG. 7d in the AD converter 8. The start pulse signal S1 shown in FIG. 7a and the digital signal S4 shown in FIG. The thickness and refractive index of the insulating film 101 are calculated from the optical conditions of the light and the optical properties of the substrate 102 by a known ellipsometry method.

[Problem that the invention seeks to solve]

The conventional insulating film quality evaluation device is configured to repeat the above operation every time the analyzer 61 rotates once, so if the analyzer 61 is rotated continuously, The computer 9 can calculate the film thickness and refractive index values. However, unless the sample 100 is changed to a sample with a different film quality, the film thickness and refractive index hardly change over time. Only the refractive index can be obtained, and as a result, the conventional apparatus described above has the disadvantage that multifaceted information regarding the film quality cannot be obtained for the same sample 100.

The present invention was made in order to eliminate the drawbacks of the conventional methods as described above, and it is possible to detect temporal changes in the thickness and refractive index of an insulating film, and to evaluate the film quality of an insulating film from many aspects. The purpose is to provide a membrane quality evaluation device.

[Means for solving problems]

The present invention is an insulating film quality evaluation device in which a sample insulating film is irradiated with light from an annealing light source that is different from light from a measurement light source, and the sample is heated and maintained at a predetermined temperature. It is something.

[Effect]

In the present invention, the annealing light is irradiated together with the measurement light while the sample is maintained at a predetermined temperature, thereby providing optical stimulation to the sample that changes the film thickness and refractive index over time. , the temporal change in refractive index is promoted by heating.

〔Example〕

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

FIG. 1 shows an apparatus for evaluating the quality of an insulating film according to an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 5 indicate the same or corresponding parts, and 10 indicates the measurement light source 1.
This is an annealing light source for irradiating the sample 100 with annealing light different from the light, and for example, a high-pressure mercury lamp, a halogen lamp, or the like is used. 11a is a sample heating unit for raising the temperature of the sample 100; 12 is a temperature controller connected to the sample heating unit 11a to adjust the temperature of the sample 100;
A heating device 11 is configured to raise and maintain the temperature of 0 at a predetermined temperature. Reference numeral 13 denotes a display section for recording and displaying temporal changes in film quality and refractive index of the insulating film 101 of the sample 100 calculated by the computer 9.

Next, the effects will be explained.

First, to explain the operating principle of the apparatus of this embodiment, when annealing light is irradiated from an annealing light source 10 consisting of a high-pressure mercury lamp to an insulating film 101 of a sample 100, if the insulating film 101 is a plasma silicon nitride film, for example, the annealing light source 10 is a high pressure mercury lamp. Differences appear in the film thickness and temporal changes in refractive index depending on the film quality. This is because when light stimulation is applied, the bonding state of nitrogen-hydrogen, silicon-hydrogen, silicon-nitrogen, etc. changes, and the amount of this change varies depending on the film quality. This is because the transition of the bond state, that is, the amount of change over time, also differs depending on the film quality. If the temperature of the sample 100 is raised by the sample heating section 11a to promote the above-mentioned changes in film quality and refractive index due to optical stimulation, the film thickness and refractive index will change more reliably over time, and as a result, Multifaceted information regarding the film quality of the insulating film 101 can be obtained.

Next, the operation of this embodiment will be explained in Figs. 2 and 7.
This will be explained using figures. In this example device, sample 1
00 is placed on the sample heating section 11a, the temperature is raised by heat conduction from the sample heating section 11a, and then the surface of the sample 100 is irradiated with light from the annealing light source 10 perpendicularly.

The temperature increase control of the sample 100 is started when the temperature controller 12 is started by the pulse signal S5 of FIG. The temperature controller 12 controls the temperature to rise to a preset temperature at a heating rate of , and thereafter controls to maintain the set temperature.

Then, at time t2 when the set temperature is reached, the computer 9 gives the pulse signal S6 shown in FIG. At time t3, the pulse signal S7 shown in FIG. 2c is applied from the computer 9 to the angle encoder 62, and the rotary analyzer 6 is in continuous operation from this time t3.

In the operating state of the rotary analyzer 6, the analyzer 61 continues to rotate, and the angle encoder 62 outputs the start pulse signal S1 shown in FIG. 7a to the computer 9 every time the analyzer 61 rotates once. , the analog signal S3 from the photoelectric detector 7 by the measuring light and the data pulse S2 shown in FIG. The film thickness and refractive index are calculated for each rotation of the photon 61.
Since the analyzer 61 is continuously rotating, the above film thickness,
The refractive index is also calculated continuously. At this time, optical stimulation by annealing light is applied to the sample 100,
In addition, the optical stimulation is promoted by increasing the temperature, and as a result, the film thickness and refractive index of the insulating film 101 change as the irradiation time elapses, and these values are output to the display section 13 and displayed. For example, output plots A and B of film thickness and refractive index shown in FIG. 3 are displayed on the display section 13.

In this example, when measuring the film thickness and refractive index of the insulating film 101 using measurement light, the sample 100 is irradiated with annealing light and the sample 100 is irradiated with the annealing light.
00 is maintained at a predetermined temperature by the sample heating device, the above film thickness and refractive index can be changed over time by optical stimulation of the annealing light, and the optical stimulation can be changed by maintaining the temperature. This makes it possible to reliably obtain temporal changes in film thickness, etc., and as a result, the characteristics of the insulating film 101 can be evaluated from multiple angles.

FIG. 4 shows a modification of the above embodiment. In the figure, the same reference numerals as in Figure 1 indicate the same parts.
In the illustrated embodiment, the sample 100 was placed in the atmosphere, but in this modification, the sample 100 is kept in a predetermined atmospheric gas. In FIG. 4, reference numeral 14 is a sample hood provided to cover the sample 100, and this sample hood 14 has a window 14 in the optical path so as not to obstruct the incidence and exit of light.
In addition, gas introduction and exhaust passages 14b and 14c are provided for causing a desired gas to flow into the sample hood 14 and then flow out of the hood 14.

In this modification, the atmospheric gas surrounding the sample 100 can be changed to a desired gas, and the insulating film 1
The film quality of No. 01 can be evaluated from more aspects.

〔Effect of the invention〕

As described above, according to the insulating film quality evaluation device according to the present invention, the sample is heated and held at a predetermined temperature,
The film thickness and refractive index were continuously measured while applying optical stimulation to the sample using annealing light.
It is possible to detect changes in film thickness, etc. over time, and has the effect of obtaining multifaceted information regarding the insulating film.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an insulating film quality evaluation apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are diagrams for explaining its operation, and FIG. 4 is an embodiment of the insulating film quality evaluation apparatus shown in FIG. 5 is a block diagram showing a conventional insulating film quality evaluation device, FIG. 6 is a cross-sectional view of a sample, and FIG.
FIG. 4 is a diagram for explaining the operation of the embodiment of FIG. 4 and the conventional device. In the figure, 1 is a measurement light source, 10 is an annealing light source, and 11 is a sample heating device. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. Irradiating measurement light onto a sample insulating film at a predetermined angle, detecting the reflected light from the sample, and determining temporal changes in the film thickness and refractive index of the insulating film from the detected reflected light. and a sample heating device for maintaining the sample at a predetermined temperature. An insulating film quality evaluation device characterized by: 2. The insulating film quality evaluation apparatus according to claim 1, wherein the annealing light source is a high-pressure mercury lamp that irradiates the sample with annealing light from the normal direction.