JPH056868A - Shape simulation method of semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To provide a technique wherein the prediction of a cross-sectional shape after having executed the working process of an LSI can be executed by taking into consideration the influence of a surface shape in a direction perpendicular to an analytic corss section and in a short computation time. CONSTITUTION:A shielding plate S in which a properly shaped hole A has been made is defined virtually with reference to each movement computation point on the surface according to an anticipation angle theta in a range where the sky can be looked over without being shielded by walls on both sides when the sky is looked up from the point; the movement of the point is computed by taking into consideration the shielding effect of a three-dimensional incident particle by the shielding plate S. Thereby, the shape simulation of a semiconductor integrated circuit which has taken into conseiration the effect of a surface shape in a direction perpendicular to an analytic cross section M can be executed easily. The computation time can be shortened sharply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for simulating a shape of a semiconductor integrated circuit, and more particularly to a processed shape of a surface of a large-scale semiconductor integrated circuit (hereinafter referred to as LSI) after a processing process (deposition or etching). The present invention relates to a simulation technique for predicting the above, and to a shape simulation method for an LSI that improves the prediction accuracy and shortens the calculation time.

[0002]

2. Description of the Related Art Conventional shape simulation (for example,
Tazawa et al., “Unified Topography Simulator for Complex
Reaction including both Deposition and Etchin
g ", Symposium on VLSI Technology, 1989.), two-dimensional deformation calculation is performed assuming that the cross-sectional shape of the simulation object is infinitely continuous in the vertical direction of the analysis cross-section after the process is performed. In this case,
The concept of shielding calculation for incident particles contributing to deposition or etching is shown in FIG.

In this conventional method, as shown in FIG. 4, with respect to each movement calculation point on the surface, when the sky is looked up from that point, there is a range in which the sky can be seen without being shielded by the walls on both sides. The amount of movement of the point was calculated by two-dimensionally integrating the contribution of the incident particle within the angle of view. However, on an actual LSI, the influence of the surface shape in the direction perpendicular to the analysis cross section is often not negligible. Especially, in the case of a hole such as a through hole, the walls existing in the front and back of the analysis cross section cause There is a problem that accurate shape prediction cannot be performed unless the effect of blocking incident particles that contribute to deposition or etching is taken into consideration.

As a method for solving the above problems, LS is used.
There is a method of treating the shape of I as three-dimensional data and performing a three-dimensional deformation calculation (see, for example, Yamaguchi et al., “Three-dimensional shape simulation”, Proceedings of 36th Joint Lecture of the Applied Physics Society of Japan).

[0005]

However, in general, LSI
Although it is sufficient to predict the cross-sectional shape of the hole when performing the pattern design and process design of the above, since the deformation of the entire shape of the hole is calculated in three dimensions, this method can be used as an ordinary two-dimensional simulation. There has been a problem that a huge amount of calculation time is required to obtain the same degree of accuracy.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to predict the cross-sectional shape of a semiconductor integrated circuit after the fabrication process is performed, and to predict the surface in the direction perpendicular to the analysis cross-section. An object of the present invention is to provide a technique that can be implemented in a short calculation time while taking the influence of the shape into consideration.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

In order to solve the above-mentioned problems, according to the present invention, in a shape simulation method of a semiconductor integrated circuit for predicting a sectional shape after deposition or etching on the surface of the semiconductor integrated circuit, In the case where the incident of particles that contribute to deposition or etching is subject to the shielding effect of the surrounding three-dimensional shape like the part of (3), the surface shape is expressed on the analysis cross section at each time step. When calculating the movement of each point, when looking up at the sky from that point, a shield plate with a hole with an appropriate shape is hypothesized according to the view angle of the range that can be seen without looking at the walls on both sides. By performing the movement calculation by taking into account the shielding effect of the incident particles by this shielding plate, the high-speed simulation considering the three-dimensional shape effect can be realized approximately. The most important feature that. ..

[0009]

According to the above-described means, it is possible to perform a simulation in consideration of the effect that the particles existing in the front and the back of the analysis cross section shield the incident particles that contribute to deposition or etching at the hole. .. Further, when a hole is formed in a film or a film is added to a hole, there may be a situation in which the shape of the hole is rounded or sharpened. In the present invention, for example, an ellipse, a rectangle, or a star shape is used. From
By assuming an appropriate hole shape (setting the coefficient of an appropriate hole shape approximation equation), calculation considering this effect can also be performed. Furthermore, by changing the hole shape (changing the coefficient of the approximate equation of the hole shape) at each time step, it is possible to perform calculation taking into consideration the hole shape change over time.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a view for explaining the concept of an embodiment of a semiconductor integrated circuit shape simulation method of the present invention, and FIG. 2 is a hole shape after an actual process (sputter deposition of a metal film) is carried out. 3 is a copy of an example of a scanning electron microscope (SEM) photograph viewed from above, in which (a) is an elliptical shape and (b) is a star shape. FIG. 3 is a diagram showing an example of a hole-shaped approximate figure of the present embodiment, where (a) is an elliptical example,
(B) is a rectangular type, and (c) is a star type.

In the semiconductor integrated circuit shape simulation method according to the present embodiment, the concept of the shielding calculation when calculating the movement of each point representing the surface shape is as shown in FIG. When the user looks up, the shielding plate S having a hole A of an appropriate shape is virtually defined according to the angle of view θ of the range in which the sky can be seen without being shielded by the walls on both sides, and the incidence by this shielding plate S The movement calculation is performed taking into consideration the particle shielding effect. That is, inside the solid angle of the calculation point with respect to the hole A of the shield plate S (inside the weight formed by the calculation point P and the hole A of the shield plate S), the contribution of the incident particles is three-dimensionally integrated. , Calculate the amount of movement at that point. In FIG. 1, M is an analysis cross section.

FIG. 2 shows an example of an SEM photograph of the hole shape seen from above after the actual process (sputter deposition of a metal film). The left photograph (a) shows the deposition result on a round hole, and the right photograph (b) shows the deposition result on a rectangular hole. In this example, it can be seen that the round hole maintains the round shape and the rectangular hole has the star shape.

The hole shape of the present embodiment is, for example, as shown in FIG. 3, an elliptical shape (a), a rectangular shape (b), and a star shape (c).
This shape is approximated by the following equations 1 and 2.

In case of elliptical type (a)

[0016]

## EQU1 ## x ⁿ / a ⁿ + y ⁿ / β ⁿ = 1 In Equation 1, when n → ∝, a rectangular type (b) is obtained.

In case of star type (c)

[0018]

[Number 2] ^{x = α (p m + q} m) y = β (p m + q m) | p | + | q | in = 1 Equation 2, a rectangular type (b) when m → 1.

Here, α and β are coefficients showing the ratio of the length of the hole in the analysis cross section direction to the width of the hole in the analysis cross section vertical direction. Initially, the coefficient is determined to match the initial shape of the hole. After that, for example, assuming that the dimension in the width direction also changes in accordance with the change in the dimension in the length direction, the coefficient can be automatically determined for each step. Further, n and m are parameters relating to the curvature, and when the rectangular hole gradually changes to an elliptical shape by changing these values with time (n = ∝ → 2), the rectangular hole is changed. It is also possible to perform a simulation when changes gradually to a star shape (m = 1 → ∝).

According to the present embodiment, the shape simulation of the semiconductor integrated circuit in which the influence of the surface shape in the direction perpendicular to the analysis cross section is taken into consideration can be achieved by only partially modifying the movement calculation section of the conventional two-dimensional simulator. , Can be easily implemented.

Further, it is possible to significantly reduce the calculation time as compared with the case where the content of the graphic data and the deformation calculation are completely three-dimensionalized.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention. ..

[0023]

As described above, according to the present invention, it is possible to easily carry out a shape simulation of a semiconductor integrated circuit in consideration of the influence of the surface shape in the direction perpendicular to the analysis cross section. In addition, it is possible to significantly reduce the calculation time.

[Brief description of drawings]

FIG. 1 is a view for explaining the concept of one embodiment of a semiconductor integrated circuit shape simulation method of the present invention;

FIG. 2 is a copy of an example of a scanning electron microscope (SEM) photograph in which the hole shape after the actual process (sputter deposition of a metal film) of the present embodiment is performed,

FIG. 3 is a diagram showing an example of an approximate figure of a hole shape according to the present embodiment,

FIG. 4 is a conceptual diagram of shielding calculation in a conventional two-dimensional simulation.

[Explanation of symbols]

M ... Analysis cross section, P ... Calculation point, θ ... View angle, S ... Shield plate, A ... Hole.

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[Procedure amendment]

[Submission date] August 7, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

FIG. 1 is a view for explaining the concept of an embodiment of a semiconductor integrated circuit shape simulation method of the present invention, and FIG. 2 is a hole shape after an actual process (sputter deposition of a metal film) is carried out. 3A and 3B are schematic views showing an appearance based on an example of a scanning electron microscope (SEM) photograph viewed from above, (a) is an elliptical shape, and (b) is a star shape. Figure 3
Is a diagram showing an example of a hole-shaped approximate figure of the present embodiment,
(A) is an example of an elliptical shape, (b) is an example of a rectangular shape, and (c) is a star shape.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

FIG. 2 is a schematic view showing an appearance based on an example of a scanning electron microscope (SEM) photograph of a hole shape seen from above after the actual process (sputter deposition of a metal film) of this embodiment is performed.
Figure ,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seitaro Matsuo 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (1)

Claim: What is claimed is: 1. A semiconductor integrated circuit shape simulation method for predicting a cross-sectional shape after deposition or etching on a surface of a semiconductor integrated circuit, for each movement calculation point on the surface. From that point, when you look up at the sky, you can virtually define a shield plate with a hole of an appropriate shape according to the angle of view of the area where you can see the sky without being shielded by the walls on both sides. A shape simulation method for a semiconductor integrated circuit, characterized in that the movement of a point is calculated in consideration of a three-dimensional incident particle shielding effect.