JPH02271525A - Simulation of etching process - Google Patents

Abstract

PURPOSE:To simulate a plurality of substances whose etch rates are different by a method wherein dot rows are given to circumferences of all substances to be etched and it is detected by a crossing of the dot rows whether an etching operation has reached another adjacent substance to be etched or not. CONSTITUTION:Dot rows 5 are given to circumferences of all substances 1 to 4 to be etched; an etching process to etch the individual substances to be etched from their upper part is simulated. Whether an etching operation has reached another adjacent substance to be etched or not is detected by detecting a crossing of the successive dow rows 5; when another substance to be etched is detected, this simulation is continued by using an etch rate of the substance. Thereby, it is possible to execute the simulation which is matched to a practical etching operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for simulating an etching process.

[Conventional technology]

In the conventional etching simulation method, as shown in the cross-sectional view of FIG. 4, a material to be etched 6 is placed on a silicon substrate 1, and a dot array 5 is provided in a region that is in contact with an etching material such as ions or hydrochloric acid. I'm going. That is, the fifth
As shown in the figure, the Mikasa arc minute B with respect to the point sequence 5 is set as the etching direction A, and the etching distance obtained from the product of this etching direction A, etching time, and etching speed is determined for each point, and each of these points is A new point sequence 5 is obtained by moving the point by an etching distance in the direction shown in FIG.

[Problem to be solved by the invention]

The conventional etching simulation method described above can only handle the etching rate of a single material 6 to be etched. The problem is that it cannot be determined that the etching rate is the same, and etching continues at the same etching rate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for simulating an etching process that eliminates these drawbacks and enables simulation for a plurality of materials having different etching rates.

[Means to solve the problem]

The structure of the present invention is an etching process that simulates an etching process in which a dot array is provided around each of the materials to be etched, and each material to be etched is isotropically or anisotropically etched from above. In the simulation method, whether or not etching has reached another adjacent material to be etched is detected by sequentially detecting intersections of a series of points, the other material to be etched is detected, and the etching rate of the material is determined. The feature is that the simulation is continued using .

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a flow diagram for detecting contact with a different substance in an embodiment of the present invention, and FIGS. 2(a) to 2(f) are schematic diagrams explaining the flow of FIG. 1. That is, in this embodiment, when the material to be etched in the etching process is a different material, the detection procedure becomes a problem. First, in step 11, the material to be etched made of the same material is surrounded by a series of dots, and then surrounded by a series of strings on the right (
2(a), (c)), next, in step 12, etching proceeds, and at this time, the string in contact with air is removed at a time step Δt.

Material-dependent velocity vector V1. When the movement vector is RI, the movement is performed by R1=Δt*v.

Next, in step 13, the intersection point P of one line segment and another line segment is
It is determined whether or not is within the line segment (Fig. 2 (b)). In this case, the determination is made for all line segments as in step 14, and when the determination of all line segments is completed, the process proceeds to step 17. However, if the determination has not been completed, the presence or absence of an intersection is determined as in step 15, and if there is an intersection, step 1 is performed.
6, the string row is divided into one string row, and the process returns to step 13 (FIG. 2(d)).

(e)).

In step 17, left rotation data in the string string is deleted (Fig. 2 (f)). In step 18, it is determined that the etching time has ended, and if the etching time has elapsed, the process returns to step 12 and is repeated. Processing ends when time expires.

In the etching simulation method of this embodiment, contact with other adjacent materials during the etching process is detected by detecting the intersection of strings. in this case,
As mentioned above, the entire periphery of the etched material made of the same material is surrounded by a string of dots, and each time the string of dots moves as etching progresses, the intersection of the string of dots is detected. I do. Then, the intersecting strings of points are deleted, and the string of points that has been one continuous string is divided into multiple strings of points. By deleting this point sequence, it is determined that another material to be etched has been exposed.

The etching rate (V+) of the exposed material is applied to the other exposed material to be etched, and the dot sequence is moved at the etching rate unique to each material. The intersection of this series of points is whether the intersection of the equation of a straight line representing one line segment between points and the equation of a straight line representing another line segment is on either line segment. You can find out whether or not.

FIGS. 3(a) to 3(d) are cross-sectional views illustrating a simulation step by step when this embodiment is applied to a silicon substrate. First, as shown in FIG. 3 (a), an oxide film (SiOz) 2 is placed on a silicon substrate 1, a nitride film (Si3 N4) 3 is placed on this oxide film 2, and It is assumed that there is a developed resist 4 above the JI 3.

Next, as shown in Figure 3(b), dot arrays are placed around each substance.
will be established. At this time, the etching is progressed in the same manner as shown in FIG.
Detect the intersection of At the stage when these point sequence 5 is detected,
The material is divided to expose the underlying material to be etched (2) as shown in FIG. 3(c), and the surface in contact with the etching material (this surface) is exposed as shown in FIG. 3(d). A flag is given to the point sequence included in the point sequence as a candidate for a point to be moved), and etching can be continued at an etching rate determined from each etching target material and the etching material.

〔Effect of the invention〕

As explained above, in the present invention, the optimum etching time and selection of etching material are determined and simulated in advance by setting the same conditions as those used for actual microfabrication of integrated circuits, so that the actual etching This has the effect of being able to perform simulations that suit the situation.

(a) to (f) are schematic diagrams explaining Fig. 1, and Fig. 3 (a)
) to (d) are sectional views showing the order of etching simulation steps in this embodiment, FIG. 4 is a sectional view illustrating a conventional etching simulation step, and FIG. 5 is a schematic diagram showing the etching direction in FIG. 4. .

DESCRIPTION OF SYMBOLS 1...Silicon substrate, 2...Oxide film, 3...Nitride film, 4...Resist, 5...Dot array, 6...Etched material, 11-18...Processing step , A...
Etching direction, B... trisecting angle.

Claims (1)

[Claims] In an etching process simulation method, an etching process is simulated in which dot arrays are provided around each of the etching target materials, and each of these etched materials is isotropically or anisotropically etched from above. It is detected whether the etching has reached another material to be etched by sequentially detecting the intersection of a series of points, and when the other material to be etched is detected, a simulation is performed using the etching rate of that material. A method for simulating an etching process characterized by a continuous etching process.