JP4023021B2 - Interlayer insulation film level difference measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a step measuring apparatus for an interlayer insulating film.
[0002]
[Prior art]
A conventional interlayer insulating film level difference measuring apparatus has a level difference measuring unit and a mapping unit, and the level difference measuring unit measures the level difference of the interlayer insulating film on the semiconductor substrate and uses the level difference of the interlayer insulating film as the mapping unit. To provide mapping.
[0003]
[Problems to be solved by the invention]
In such a conventional level difference measuring apparatus, accurate level difference measurement cannot be performed due to warpage of the semiconductor substrate (wafer), poor flatness (flatness) accuracy of the stage of the level difference measuring means, or the like.
[0004]
In view of this point, the present invention intends to propose an interlayer insulating film level difference measuring apparatus capable of performing accurate level difference measurement.
[0005]
[Means for Solving the Problems]
In the interlayer insulating film level difference measuring device according to the present invention, the level difference measuring unit, the film thickness measuring unit, and the level difference measuring unit measured the level difference of the interlayer insulating film on the semiconductor substrate by the film thickness measuring unit. And a step correcting means for correcting the thickness of the portion of the interlayer insulating film not including the wiring layer and a mapping means for performing mapping by supplying the step of the interlayer insulating film corrected by the step correcting means.
[0006]
According to the present invention, the step of the interlayer insulating film on the semiconductor substrate measured by the level difference measuring unit by the level difference correcting unit is measured by the film thickness measuring unit and does not include the wiring layer of the interlayer insulating film. The thickness of the interlayer insulating film is corrected by the thickness, and the level difference of the corrected interlayer insulating film is supplied to the mapping means to perform mapping.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a step of an interlayer insulating film on a semiconductor substrate measured by a step measuring means, a film thickness measuring means, and a step measuring means, and a wiring layer of the interlayer insulating film measured by the film thickness measuring means. An interlayer insulating film level difference measuring apparatus having level difference correcting means for correcting with a thickness of a portion not included, and mapping means for performing mapping by supplying a level difference of the interlayer insulating film corrected by the level difference correcting means.
[0008]
[Specific Examples of Embodiments of the Invention]
An interlayer insulating film level difference measuring apparatus according to a specific example of an embodiment of the present invention will be described below with reference to the drawings. First, FIG. 2A will be described. a is a semiconductor substrate (wafer) (semiconductor integrated circuit chip), an interlayer insulating film b is deposited on the semiconductor substrate a, and a wiring layer c is deposited on the interlayer insulating film b. This is the case where the interlayer insulating film b is deposited over the interlayer insulating film b. It is also possible to deposit the wiring layer c on the uppermost interlayer insulating film b and deposit the interlayer insulating film b over the interlayer insulating film b and the wiring layer c.
[0009]
In general, an n-layer interlayer insulating film is deposited between the semiconductor substrate and the n-layer (n = 1, 2, 3,...) On the semiconductor substrate. An interlayer insulating film is deposited on the interlayer insulating film and over the uppermost wiring layer.
[0010]
With reference to FIG. 1, the configuration of a step measuring apparatus for an interlayer insulating film as a specific example will be described. Reference numeral 1 denotes a level difference measuring means, for example, a contact level difference measuring machine that measures the unevenness (level difference) of the entire surface of the interlayer insulating film b by tracing the entire surface of the interlayer insulating film b to be measured with a needle. is there. Reference numeral 2 denotes a film thickness measuring means, for example, a portion that does not include the wiring layer c of the interlayer insulating film b set in advance by irradiating the surface of the interlayer insulating film b to be measured and measuring its refractive index. (Part without the wiring layer c corresponding to the arrow in FIG. 2A) (predetermined, for example, a 40 μm square part) (circled part in FIG. 2B) It is a contact-type film thickness measuring machine. Then, in the level difference correcting unit 3, the level difference of each point of the entire interlayer insulating film b between a certain point on the semiconductor substrate a and a certain other point in the vicinity thereof measured by the level difference measuring unit 1 (FIG. 2B). ) Is corrected by the thickness of the portion of the interlayer insulating film b that is set in advance and does not include the wiring layer c, measured by the film thickness measuring means 2. FIG. 2C shows a change in the corrected step of the interlayer insulating film b.
[0011]
Then, the level difference corrected by the level difference correction unit 3 is supplied to the mapping unit 4 to perform mapping.
[0012]
Next, the step correction means 3 will be described. The level difference correction means 3 includes a memory 6, a calculation means 7, and a CPU 5 that controls the memory 6 and the calculation means 7. Reference numerals 6a and 6b denote partial memory areas of the memory 6, respectively.
[0013]
The data of the level difference of the interlayer insulating film b between a certain point on the semiconductor substrate a measured by the level difference measuring means 1 and another point in the vicinity thereof is stored in the memory area 6a of the memory 6, and Data on the thickness of the interlayer insulating film b in a portion not including the wiring layer c of the predetermined interlayer insulating film b measured by the film thickness measuring unit 2 is stored in the memory area 6 b of the memory 6.
[0014]
Step data and thickness data respectively stored in the memory areas 6a and 6b are read out and supplied to the calculation means 7, and calculation is performed based on a program stored in a ROM (not shown) in the CPU 5. Thus, step data obtained by correcting the step data with the thickness data is obtained. This corrected step data is accurate and corrected for errors caused by warpage of the semiconductor substrate (wafer) (semiconductor integrated circuit chip) and poor flatness of the step of the step measuring means. It becomes step data.
[0015]
Next, the step correction will be described with reference to FIG. In FIG. 3, points a, b, and c indicate points in the interlayer insulating film b that do not include the wiring layer c on the semiconductor substrate a in FIG. FIG. 3A shows the distribution of steps at the points a, b, and c measured by the step measuring means 1. In this example, in the interlayer insulating film b, the point b is higher than the point a by a step of 100 nm, the points b and c are the same height, and the step is 0 nm.
[0016]
FIG. 3B shows the thickness of the interlayer insulating film b at points a, b, and c measured by the film thickness measuring means 2. The film thickness at both the points a and b is 500 nm, and the film thickness at the point c is 400 nm.
[0017]
FIG. 3C shows the steps at points a, b, and c corrected by the step correction means 3. From FIG. 3B, since the film thicknesses of the points a and b were both the same as 500 nm, the height of the point a is set to the same height as the height of the point b, and the step between them is set to 0 nm. The height of point b does not change. Since the film thickness at the point c is 400 nm, which is 100 nm lower than the film thickness at the point b, the height of the point c is made 100 nm lower than the height of the point b to provide a step 100 nm.
[0018]
In FIG. 3A, when there is a step measuring point at the center x point between the points b and c, the height of the point x may be lowered by (500 + 400) / 2 (nm). Also, when the point x between the point b and the point c is the wiring layer c, the height is increased by the thickness of the wiring layer c. In this case, the height of the point x is set to (500 + 400). ) / 2 (nm). When the position of the x point is not at the center between the b point and the c point, the height of the x point may be determined by proportional distribution according to the distance between the x point, the b point, and the c point. .
[0019]
Then, the corrected step data is supplied to the mapping means 4 for mapping. This mapping means that the measured step data (corrected by the measured film thickness in this case) is represented by the distribution of the contour of the step, and the distribution of the contour of the step is represented by a cathode ray tube ( It can be displayed on the tube surface of a liquid crystal display device (not shown) or a display surface of a liquid crystal display device (not shown), and the contour curve distribution of the step can be printed by a printer (not shown). It is.
[0020]
【The invention's effect】
According to the present invention described above, the step of the interlayer insulating film on the semiconductor substrate measured by the step measuring means, the film thickness measuring means, and the step measuring means is measured by the film thickness measuring means. Since there is a step correction unit that corrects by the thickness of a portion not including the wiring layer and a mapping unit that performs mapping by supplying the step of the interlayer insulating film corrected by the step correction unit, accurate step measurement is performed. It is possible to obtain a step measuring apparatus for an interlayer insulating film that can be used.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an interlayer insulating film level difference measuring apparatus according to a specific example of an embodiment of the present invention;
FIG. 2 is an explanatory diagram illustrating a method for measuring a step of an interlayer insulating film according to a specific example of an embodiment of the present invention.
FIG. 3 is an explanatory diagram showing step correction of a step measurement method for an interlayer insulating film according to a specific example of an embodiment of the present invention;
[Explanation of symbols]
1 step measuring means, 2 film thickness measuring means, 3 step correcting means, 4 mapping means, 5 CPU, 6 memory, 6a, 6b memory area, 7 computing means.

Claims (1)

Step measuring means;
Film thickness measuring means;
A level difference correcting means for correcting the level difference of the interlayer insulating film on the semiconductor substrate measured by the level difference measuring means by the thickness of the portion of the interlayer insulating film not including the wiring layer, measured by the film thickness measuring means; ,
An interlayer insulating film level difference measuring apparatus comprising: mapping means for performing mapping by supplying a level difference of the interlayer insulating film corrected by the level difference correcting means.

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