JPS6184508A - Evaluating device for film quality of insulation film - Google Patents

Abstract

PURPOSE:To vary an insulating film during measuring operation and obtain versatile information by irradiating a sample insulating film with light for annealing while irradiating the film with light for measurement at a specific angle, and holding the film at specific temperature through a sample heating device. CONSTITUTION:The light from a measurement light source 1 is reflected by the surface of the sample 100 and enters a photodetector 7 through a rotary analyzer 6. The sample heating device 11 heats the sample 100 up to the specific temperature. The sample 100 is irradiated with annealing light from an annealing light source 10. The rotary analyzer 6 starts continuous operation after the same is heated up to the specific temperature and the annealing light source enters stable operation. The output of the photodetector 7 is transmitted on every rotation of the analyzer 61 and a computer calculates the film thickness and refractive index. The insulating film has variation owing to the annealing light and heating, so versatile information is obtained with time.

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.

[JIA-Small technology]

Conventionally, this type of device was called “ELLIPSOMETRY”.
ANDPOLARIZED LIGHT, R,M
, A, AZZAM AND N,? +.

BASHARA, N0RTH-11OLLAND P
UBLISIIIING COMPANY-AMSTE
RDAM, NIEW YORK, 0XFORD,
1977, page 412, which is shown in FIG. 100 in the figure
is the 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, and 3 is 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; 5 is a sample for checking whether the light is reflected at a desired angle on the surface of the sample 100; Alignment target 61 is an analyzer rotated at a constant speed by a synchronous motor (not shown), 62
is an angle encoder that detects the rotation angle θ of the analyzer 61; 6 is a rotary analyzer configured by integrating the analyzer 61 and the angle encoder 62; 7 is a rotary analyzer that detects the intensity of light passing through the rotary analyzer 6. 8 is an A-D converter that converts the analog signal regarding the light intensity from the photoelectric detector 7 into a digital signal by the data pulse regarding the angle from the rotating analyzer 6; A digital signal and a start pulse signal from the angle encoder 62 indicating the cutting angle of the analyzer 61 are input, and the sample 1
This is a computer that calculates the film thickness and refractive index of 00.

FIG. 6 shows details of the sample 100, and in the figure, 1
01 is an insulating film, and 102 is a substrate on which the insulating film 1111!101 is formed.

Next, the operation will be explained. The light from measurement light source 1 is
After being polarized by the polarizer 2, the insulating film 1 of the sample 100
The light is incident on the sample 100 at a constant angle, in this case 70°, with respect to the normal to the 01 plane. This incident light is reflected by the sample 100 and passes through the analyzer 61 of the rotating analyzer 6 to the photoelectric detector 7.
incident on .

When the analyzer 61 starts to rotate by the synchronous motor, the angle concoder 62 outputs the start pulse signal S1 shown in FIG. equally spaced data pulses S2
The photoelectric detector 7 also outputs an analog signal S3 shown in FIG. 7(C).

The analog signal S3 is converted by the data pulse S2 into the digital signal S4 shown in FIG. 7(d) in the AD converter 8. Each rotation of the analyzer 61, the start pulse signal S1 in FIG. 7(a) and the digital signal S4 in FIG. The film thickness and refractive index of the insulating film 101 are calculated from the optical conditions of the light incident on the insulating film 100 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 sample 100 is changed to a sample with a different film quality, the film thickness will vary.

The refractive index hardly changes over time, so even if the rotating analyzer 6 is operated continuously, only approximately the same film thickness and refractive index can be obtained.
Regarding 00, there was a drawback that multifaceted information regarding film quality could not be obtained.

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 with the measurement light while the sample is held at a predetermined temperature.
A light stimulus that changes the refractive index over time is applied to the sample,
Furthermore, the temporal changes in the film thickness and refractive index are accelerated by heating.

〔Example〕

Hereinafter, embodiments of the present invention will be described 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 equivalent parts, and 10 is an annealing light source for irradiating the sample 100 with annealing light different from the light of the measurement light source 1;
For example, high-pressure mercury lamps.

A halogen lamp or the like is used. lla is a sample heating section for raising the temperature of the sample 100, and 12 is a sample heating section 11a.
is a temperature controller for adjusting the temperature of the sample 100, and this heating section 11a, controller 1
2 constitutes a heating device 11 that raises and maintains the sample 100 at a predetermined temperature. Reference numeral 13 denotes a display unit that records and displays 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 the insulating film 101 of the sample 100 is irradiated with annealing light from annealing light #10 consisting of a high-pressure mercury lamp, if the insulating film 101 is a plasma silicon nitride film, for example, Depending on the quality of the film, differences appear in the film thickness and changes in refractive index over time. 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, and the above bonding state changes over time when this light stimulation is applied. This is because the transition of , that is, the amount of change over time, also differs depending on the film quality. and,
Raising the temperature of the sample 100 by the sample heating section 11a,
If the above-described changes in film quality and refractive index due to optical stimulation are promoted, 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 using FIG. 2 and FIG. 7. In the apparatus of this embodiment, the sample 100 is placed on the sample heating section 11a, the temperature is raised by heat conduction from the sample heating section 11a, and then light from the annealing light source 10 is irradiated perpendicularly onto the surface of the sample 100. do.

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

Then, at time t2 when the set temperature is reached, a pulse signal S6 from the computer 9 (see Fig. 2) is sent to the annealing light source 10.
As a result, the annealing light source 10 starts operating, and at time t3 when the annealing light source 10 enters a stable operating state, the pulse signal S7 shown in FIG. The photon 6 enters a continuous operation state from this time t3.

In the operating state of the rotating analyzer 6, the analyzer 61 continues to rotate, and the angle encoder 62 outputs the start pulse signal S1 shown in FIG. 7(a) to the computer 9 every time the analyzer 61 rotates once. In addition, the analog signal S3 from the photoelectric detector 7 by the measurement light and the data pulse S2 shown in FIG. The film thickness and refractive index are calculated each time the analyzer 61 rotates.

Since the analyzer 61 is continuously rotating, the film thickness and refractive index are also continuously calculated. At this time, the sample 100 is optically stimulated by annealing light, and the optical stimulation is accelerated by increasing the temperature, and as a result, the thickness and refractive index of the insulating film 101 change as the irradiation time passes. , and these values are output to the display section 13, where, for example, the film thickness and refractive index output plots A and B shown in FIG. 3 are displayed.

In this way, in this embodiment, the insulating film 101 is
When measuring the film thickness and refractive index of sample 1, apply the annealing light to sample 1.
00, and the sample 100 was maintained at a predetermined temperature by the sample heating device, so that the above film thickness and refractive index could be changed over time by optical stimulation of the annealing light. By maintaining the temperature described above, optical stimulation can be promoted, and temporal changes in film thickness etc. can be reliably observed, 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 FIG. 1 indicate the same parts, and in the embodiment shown in FIG. This is how it was done. In FIG. 4, 14 is a sample hood provided to cover the sample 100, and this sample hood 1
4 has a window 14 in the optical path so as not to obstruct the entrance and exit of light.
A is provided, and 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 film quality of the insulating film 101 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 film thickness and refractive index are continuously measured while raising and maintaining the temperature of the sample at a predetermined temperature and applying optical stimulation to the sample with annealing light. Since the measurement is carried out, it is possible to detect changes in the film thickness over time, which has the effect of obtaining multifaceted information regarding the insulating film.

[Brief explanation of drawings]

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 above-mentioned FIG. 1. FIG. 5 is a block diagram showing a conventional insulating film quality evaluation apparatus, FIG. 6 is a cross-sectional view of a sample, and FIG. FIG. 2 is a diagram for explaining the operation of a conventional device. In the figure, 1 is a measurement light source, 10 is an annealing light source, 1
1 is a sample heating device. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) The measurement light is irradiated onto the sample insulating film at a predetermined angle, the reflected light from the sample is detected, and the temporal changes in the film thickness and refractive index of the insulating film are obtained from the detected reflected light to obtain the above-mentioned insulation film. An apparatus for evaluating film quality of a film, characterized by comprising an annealing light source that irradiates the sample with annealing light at the same time as the measurement light, and a sample heating device that maintains the sample at a predetermined temperature. A film quality evaluation device for insulating films. (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.