JP3188926B2 - Display method of semiconductor device sectional structure - 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 displaying a cross-sectional structure of a semiconductor device, which allows the cross-sectional structure of the semiconductor device to be clearly displayed at high speed.

[0002]

2. Description of the Related Art A cross-sectional structure of a semiconductor device to be manufactured is described by pattern data of a photomask used for manufacturing the semiconductor device and forming conditions such as a material used for each layer, a forming method, and a film thickness. Is possible. There are two methods for drawing the cross-sectional structure of the semiconductor device: a method based on shape simulation and a method based on a simple model (SI developed by the University of California, Berkeley).
MPL). Normally, the shape simulation is used when it is desired to accurately know the cross-sectional shape of a narrow area, and the simple model is used when it is desired to display a cross-sectional structure in a relatively wide range at high speed.

In the drawing of these cross-sectional structures, in any method, the boundaries between the layers are expressed by broken lines using vector data. For example, as shown in FIG. 9, a first material region 91, a second material region 92, a third material region 93, and an air region 94 which constitute a cross section of a semiconductor device to be drawn on a CRT of a shape simulation device.
With the material boundaries 95 and 96 and the surface boundary 9 respectively.
7 are separated by polygons (polygonal lines) formed by.

When a new layer is formed on the material region 93, for example, when a state in which an insulating film of silicon oxide is formed is drawn, the formation state such as anisotropy of the formed silicon oxide is formed. In consideration of the above, a movement vector of each vertex of the polygonal line of the material boundary line 97 indicating the outermost surface is formed and moved to form a new boundary line. Here, the destination of each vertex is calculated in minute increments. Then, when the intersection of the movement vectors or the division of one area occurs, a graphic operation (calculation processing by a program) is performed on the shape data to generate new data (new boundary line) without contradiction, Thereby, the boundary line is drawn.

[0005]

Conventionally, as described above, if it is attempted to increase the drawing accuracy, it takes a long time to calculate a boundary line and takes a long time to draw a cross section. There was a problem. The conventional method is effective for analysis and design of individual semiconductor manufacturing processes because a high-precision drawing of a cross-sectional shape is possible. However, since a long calculation time is required, for example, all processing processes including several hundred steps are required. However, it has been difficult to apply the method to applications such as failure analysis of a semiconductor device that requires high-speed display of a cross-sectional structure of a semiconductor device manufactured through the above.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can accurately draw a cross-sectional structure of a semiconductor device without using complicated arithmetic processing or taking much time. The purpose is to be.

[0007]

According to the present invention, there is provided a method for displaying a sectional structure of a semiconductor device, in which a shape change corresponding to a directional component of a processing process such as etching or deposition is performed to solve the above problems. After approximating the processing characteristic diagram, which is a figure represented by a combination of a plurality of basic figures, the type of substance is defined by the pixel value attached to each pixel of the display cross section of the drawing target displayed on the screen, A process of determining a pixel whose pixel value is different from its own pixel value as a boundary pixel of the substance, and a process of obtaining one of a plurality of basic figures on a display cross section by centering on the boundary pixel. And, on this drawing cross section, the pixel having a specific value on the predetermined display cross section displayed on the screen before the process of obtaining the drawing cross section is And generating a cross-sectional structure screen and a process of redrawing back to a specific value of the repeated several times.

[0008]

The state of each layer constituting the cross section is drawn without using the boundary line indicating the boundary of the substance.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, the basic concept of the present invention will be described. FIG. 1 is an explanatory view schematically showing the definition of a material region and a material boundary in the method for displaying a sectional structure of a semiconductor device according to the present invention. In the figure, 1 is a first material region, 2 is a second material region, 3 is a third material region, 4 is an air region, p
Reference numeral 1 denotes a pixel indicating the first material region 1, p2 indicates a pixel indicating the second material region 2, p3 indicates a pixel indicating the third material region 3, and p4 indicates a pixel indicating the air region 4.
The pixel is a pixel of the minimum unit when displaying the drawing, and for example, the pixel p1 indicates that the pixel (pixel) at this position in displaying the value indicates the pixel p1.

Thus, for example, the third material region 3
It is represented by a set of pixels having a value indicating the pixel p3. Here, the value indicating the pixel p1 is a value at which the pixel emits “red”, for example. Similarly, assuming that the pixel p2 has a value of “blue”, the pixel p3 has a value of “yellow”, and the pixel p4 has a value of “white”, the first material region 1 is displayed in “red” in FIG. The second material region 2 is displayed in “blue”, the third material region 3 is displayed in “yellow”, and the air region 4 is displayed in “white”.

Accordingly, in such a display, the material region,
It does not have material boundary data, and it is determined that the area where pixels with the same pixel value continue on the screen is the same material area, and the place where the pixel value of the adjacent pixel differs from its own pixel value is the boundary of the material ( Boundary pixel). On the screen, a pixel corresponding to each material constituting the semiconductor device is called a material pixel, and all pixels existing in a space above the surface of the semiconductor device, for example, the pixel p4 in FIG. 1 are defined as air pixels. Furthermore,
A material pixel in contact with an air pixel is defined as a surface boundary pixel.

Next, a case will be described in which a state in which a fourth substance is newly deposited and formed on the third substance region 3 of the semiconductor device thus displayed by CVD is displayed. As shown in FIG. 2A, a “circle” having a radius corresponding to the deposited film thickness is drawn centered on all surface boundary pixels. The pixel p4 of the air region 4 where this circle is drawn
Is changed to a pixel value indicating the fourth substance, and for example, “green” is displayed. Then, in order to restore the pixel which has been changed to the pixel value indicating the fourth substance in the substance area 3, the pixel is redrawn so as to take a logical sum with the original drawing state. As a result, as shown in FIG.
The fourth material region 5 is displayed on the third material region 3. The fourth material region 5 is a region indicated by a pixel p5 that has a pixel value indicating the fourth material and displays “green”. It should be noted that the display may be performed in the same color even if it has different pixel values, or the same pixel value may be displayed even if there are different display colors.

The above-mentioned "circle" is a processing characteristic figure which is a figure representing a change in cross-sectional shape due to etching or deposition. FIG. 3 shows an example of a processing characteristic figure corresponding to a directional component such as etching or deposition anisotropy. The horizontal axis and the vertical axis indicate the horizontal and vertical directions on the display where the drawing is performed.

Here, in a processing process such as etching, the direction in which a point having a surface having an inclination θ moves while maintaining the inclination θ is φ, and the moving distance after a certain time t in that direction is r. Then, the locus of (r, φ) formed when θ is changed from −π to π becomes the contour line of the machining characteristic figure. The speed at which the surface having the inclination θ moves in the vertical direction is represented by v
Assuming that (θ), (r, φ) is given by the following equations (1) and (2).
Is shown as

Φ = θ + tan ⁻¹ (v ′ (θ) / v (θ)) (1) r = t (v (θ) ² + v ′ (θ) ² ) ^1/2 (2) )

FIGS. 3 (a) and 3 (b) show processing characteristic figures during isotropic deposition and isotropic etching without anisotropy, respectively. In this case, since the deposition or etching proceeds uniformly in all directions, v (θ) becomes logarithmic, and using a constant A, v (θ) = A, so that φ = θ, r = At, that is, the processing characteristic figure becomes a circle.

FIGS. 3 (c) to 3 (i) show machining characteristic figures in an anisotropic machining process. For example, in the case of sputter etching, v (θ) can be expressed as the following equations (3) and (4).

V (θ) = Bcos θ + C sin ² θ cos θ (3) v (θ) = 0 (θ <−π / 2 and π / 2 <θ) (4) where B and C are Is a constant.

The first term of the equation (3) represents a vertical component, and the second term represents a peculiar component of sputter etching. In this case, a processing characteristic diagram is as shown in FIG.

In the case of bias ECR, v (θ)
Can be expressed as follows.

V (θ) = A + Bcosθ + Csin ² θcosθ (5) v (θ) = A (θ <−π / 2 and π / 2 <θ) (6) where A, B, C is a constant.

The processing characteristics in this case are shown in FIG.
(I). By the way, FIGS. 3 (c) to 3 (f)
Can approximate a machining characteristic figure with only one basic figure such as a circle, an ellipse, and a line segment.
Is difficult to approximate with only one basic figure, and is approximated using two or more machining characteristic diagrams. Although it is considered that some actual semiconductor device processing processes have various characteristic figures in addition to the characteristics shown in FIG. 3, here,
1 sputter etching and bias ECR deposition
As an example, a method for displaying a sectional structure of a semiconductor device according to the present invention will be described.

First, an approximation in generation of a cross-sectional structure by sputter etching using the processing characteristic diagram shown in FIG. FIG. 4 shows a conceptual diagram in which a processing characteristic diagram corresponding to a peculiar component of sputter etching, that is, a component obtained by removing the vertical component from the characteristics of FIG. In this approximation, first, FIG.
An approximation excluding the vertical component is performed from the processing characteristic diagram of FIG.
In this approximation, as shown in FIG. 4A, the machining characteristic diagram is located on the coordinate origin.

Here, the figure above the origin is disregarded from the machining characteristic diagram shown in FIG. 4A, and only the lower curve portion is approximated as the machining characteristic diagram as shown in FIG. 4B. .
In the processing of a normal semiconductor device, a shape corresponding to an upper curved portion rarely appears at the time of sputter etching, and since the shape change is small, sufficient approximation accuracy can be obtained even if this is ignored. . Note that, in FIG.
If it is not desired to ignore the upper curve portion, high-precision display can be performed by the same processing as the bias ECR deposition described later, but this is omitted here.

Next, in FIG. 4 (b), an approximation of the lower curved portion is performed. The curved portion of the lower part is shown in FIG.
As shown in FIG. 4, approximation is performed by a combination of a film formation (deposition) process using a basic figure using a part of an ellipse and an etching process using a basic figure using a rectangle, as shown in FIG. . That is, the display of the cross-sectional shape changed by sputter etching is shown in FIG.
FIG. 4C shows a state in which the film is formed by the basic pattern, and FIG. 4D shows a state in which the etching is performed by the basic pattern. After that, FIG. This is performed by showing a state in which etching has been performed with a basic figure approximated by a line segment indicating the removed component.

The processing characteristic diagram of RIE shown in FIG. 3F is a processing characteristic diagram showing sputter etching (FIG.
(G) The shape is very similar to that of (g), but since the peculiar component of sputter etching is smaller than the vertical component, it may be regarded as pure vertical etching. That is, even if the processing characteristic graphic shown in FIG. 3F is approximated by a line segment (basic graphic), sufficient approximation accuracy can be obtained. However, a higher display can be achieved again by approximation using a plurality of basic figures as described above.

Embodiment 1 FIG. FIG. 5 is a diagram showing two basic figures shown in FIG. 4 and a processing characteristic diagram shown in FIG.
3A shows a specific example of drawing a cross section of an etching process state according to the processing characteristic diagram shown in FIG. 3G using a basic figure of a line segment for approximation to the processing characteristic diagram shown in FIG. In FIG. 5, 51 is a substrate region showing a substrate, 52 is a semiconductor region showing a semiconductor layer, 53 is a mask region showing a resist pattern serving as a mask for patterning the semiconductor layer shown by the semiconductor region 52, and 54 is a semiconductor region 5
2. An air area on the mask area 53. In other words, this embodiment relates to drawing of a cross-sectional structure when a semiconductor layer is subjected to sputter etching using a resist pattern as a mask.

First, as shown in FIG. 5A, all pixel information of an initial screen showing a cross section in which a portion up to the mask region 53 before the etching process is drawn is saved. Next, the surface boundary pixels are searched from the top row of the pixels constituting the initial screen. This is done by first looking for the topmost horizontally extending surface boundary pixel, and then finding the vertically extending surface boundary pixel with no obstructions at the top.

Then, a basic figure having the shape of the upper half of the vertical ellipse shown in FIG. 4C is drawn on each of the found surface boundary pixels such that the origin is located at the pixel center (FIG. 5B). ). Here, the pixel value of the basic figure is the same as the pixel value of the mask area 53.
Thereby, as shown in FIG. 5C, a state in which the deformation region 53a is formed on the substrate 51 and the semiconductor region 52 is shown. Pixels that form the deformation region 53a and that are arranged on the boundary with the air region 54 are new surface boundary pixels.

Next, this surface boundary pixel is found,
The basic figure shown in FIG. 4D is drawn such that the origin of the coordinates comes to this pixel (FIG. 5D). In the search for the surface boundary pixel, similarly to the above,
Actually, for each row of pixels constituting the screen, a search is performed for the surface boundary pixel located at the top and the surface boundary pixel on the vertical side surface on which no obstruction exists at the top. The basic figure at this time is a group of pixels having pixel values of air. As a result, FIG.
As shown in (e), the second deformation region 53b is drawn on the semiconductor region 52.

Next, as shown in FIG. 5 (f), a portion (including an air pixel) that was not a pixel to be etched is redrawn with the pixel value of the saved initial screen. Save all pixel information for. As a result, the cross-sectional shape of the mask region 53 serving as a mask when the semiconductor region 52 is sputter-etched changes, and it is possible to assume a state in which complete anisotropic etching is performed in this state. In this embodiment,
Since there is no change in the place that is not the pixel to be etched by the above-described processing, FIGS. 5E and 5F are the same. Finally, as shown in FIG.
By the redrawing using the processing characteristic diagram approximated by the line segment, the etching element region is replaced with an air pixel, and an etched state as shown in FIG. 5 (m) is obtained.

Here, in the case of this embodiment, the mask region 5
Not only 3 but also the semiconductor region 52 is to be etched. Therefore, before the processing using the basic graphic of the line segment,
The drawing process performed on the mask region 53 is performed in the semiconductor region 5.
Repeat for 2. This is shown in FIGS.
(H), which is similar to FIGS. 5 (a) to 5 (e) described above. However, in this case, since the etching rate for the semiconductor layer is different, the size of the basic figure is also different, and a drawing process of a large ellipse and a rectangle is performed as shown in the figure.

However, since this process is performed on the semiconductor region 52 having a flat surface, FIG.
When redrawing is performed with the saved drawing data at the stage (f), there is no change from the state of FIG. 5 (e) as shown in FIG. 5 (k). In other words, the above-described processing does not need to be performed on a region whose surface indicates a flat layer,
In the case of this embodiment, the processing shown in FIGS.
It is not necessary to do it. In the case where there are a plurality of substances having different etching rates and whose surfaces are not flat, it is necessary to repeat the above operation by the number of substances.

Embodiment 2 FIG. On the other hand, as shown in FIGS. 3 (h) and 3 (i), the processing characteristic figure of the bias-ECR deposition is not simple because it includes a sputter etching specific component. FIG. 6 shows a component of isotropic deposition and a specific component of sputter etching, that is, FIGS. 3 (h) and (i).
A conceptual diagram in which a processing characteristic diagram corresponding to a component obtained by excluding the vertical component from the characteristics described above is generated using a plurality of basic figures is shown.
In this step, since the figure of the upper etching curve portion appears on the flattened surface, this cannot be ignored. Here, as shown in FIGS. 6B, 6C, and 6D, the figure is decomposed into three parts and approximated. Among these, the lower etching curve portion shown in FIG. 6C has a vertically long ellipse (deposition) shown in FIG. 6E and a rectangle (etching) shown in FIG. Generated by a combination of

Hereinafter, a specific example of drawing a sectional state by bias-ECR deposition will be described with reference to FIG. First, all pixel information of the initial screen shown in FIG. 7A is saved. Next, all the surface boundary pixels are searched from the top row of the pixels constituting the initial screen.
Then, as shown in FIG. 7B, a circle centered on the found surface boundary pixel is drawn. This circle is
This is the basic figure shown in (b), which is drawn with pixel values corresponding to the substance to be deposited.

All pixel information in the state shown in FIG. 7C obtained as described above is saved, and then, FIG.
As shown in FIG. 7D, the coordinate is drawn so that the coordinate center of the basic figure composed of the upper half of the vertical ellipse shown in FIG.
Also in this case, drawing is performed using pixel values corresponding to the substance to be deposited, and a state as shown in FIG. 7E is obtained.

Next, a surface boundary pixel is searched out in the newly obtained screen in the same manner as in the first embodiment, and this pixel has a coordinate center.
Is drawn with pixel values of air as shown in FIG. 7 (f) to obtain the state shown in FIG. 7 (g). The horizontal side of this rectangle is equivalent to the length obtained by subtracting the diameter of the circle shown in FIG. 7B from the length of the minor axis of the vertical ellipse shown in FIG. It is equivalent to the length obtained by subtracting the radius of the circle from the length of half the length of the major axis. Here, as shown in FIG. 7 (h), after the place which was an air pixel on the saved screen shown in FIG. 7 (c) is redrawn with the pixel value, all pixel information of this screen is displayed. Save.

Next, as a drawing process corresponding to the upper etching curve portion, first, as shown in FIG.
The surface boundary pixel in (a) is searched for in the same manner as described above, and the lower part of the horizontal ellipse (basic figure) is brought into contact with a point moved upward by a distance corresponding to the isotropic deposition component from this surface boundary pixel. This horizontal ellipse on the screen shown in FIG. 7C is drawn with pixel values of air, and FIG.
The state shown in (j) is obtained. The major axis of the horizontal ellipse, which is the basic figure, is set equal to the length of the minor axis of the vertical ellipse.

Next, as shown in FIG.
In the saved screen shown in (h), all the locations that were material pixels of the deposition material are overlaid with the pixel values of the material. Next, as shown in FIG. 8 (l), the surface boundary pixel located at the top of the generated screen is searched, and from this point, the length corresponding to this component is shifted upward by the pixel value of the deposition material. Line segment (basic figure)
To draw. Finally, as shown in FIG. 8 (m), all the positions of the material pixels other than the deposition material on the initial screen are redrawn using the pixel values of the initial screen.

[0040]

As described above, according to the present invention, when a cross-sectional state of a semiconductor device is drawn by simulation, accurate calculation can be performed without a great deal of arithmetic processing for drawing a boundary line of a cross-sectional structure. It becomes possible to draw.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing the definition of a material region and a material boundary in a method for displaying a sectional structure of a semiconductor device according to the present invention.

FIG. 2 is an explanatory diagram for explaining the concept of the present invention.

FIG. 3 is an explanatory diagram showing an example of a processing characteristic figure.

FIG. 4 is an explanatory diagram showing a concept of generating a processing characteristic diagram corresponding to a specific component of sputter etching using a plurality of approximate basic figures.

FIG. 5 is an explanatory diagram showing one embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a concept of generating a processing characteristic diagram corresponding to a singular component of bias-ECR deposition using a plurality of approximate basic figures.

FIG. 7 is an explanatory view showing another embodiment of the present invention.

FIG. 8 is an explanatory view following FIG. 7, showing another embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a conventional drawing state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st substance area 2 2nd substance area 3 3rd substance area 4 Air area p1, p2, p3, p4, p5 Pixel

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ban Nakajima 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (58) Field surveyed (Int.Cl. ⁷ , DB name) G06F 17 / 50 H01L 21/00 H01L 29/00

Claims (1)

(57) [Claims] 1. A method of displaying a cross-sectional structure of a location specified on the screen of a computer based on process data and mask pattern data at the time of manufacturing a semiconductor device, the method comprising: After approximating a processing characteristic figure, which is a figure representing a shape change corresponding to a component, by a combination of a plurality of basic figures, a material is determined by a pixel value attached to each pixel of a display cross section of a drawing target displayed on the screen. A process in which a pixel value of an adjacent pixel that is different from its own pixel value is determined as a boundary pixel of the substance; Processing for obtaining a drawing cross-section by performing three depictions, and a process in which the drawing cross-section is displayed on a screen before the processing for obtaining the drawing cross-section. A process of redrawing a pixel having a specific value on the display cross-section of the display device so as to return the pixel to the specific value a plurality of times to generate a cross-sectional structure screen, wherein .