JPH03196521A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To detect the end point of etching at the same time as the end point of a pattern by forming the irradiation target of a laser in an aggregate conformed to the pattern shape of a section, where the end point of etching must be detected. CONSTITUTION:The pattern of a mask material 1 is formed in the shape of the aggregates of four of an original slender rectangular material to be etched 2a and three dummy materials to be etched 2b in the same size and shape as the material 2a so that the dummy materials 2b are exposed. Consequently, the etching of the original material to be etched 2a and the three dummy materials to be etched 2b is completed simultaneously. Since the pattern of the mask material 1 is formed in the four aggregates, the change of the intensity of the reflected beams of a laser is made larger than one aggregate by quadruple. Accordingly, the end point of etching is detected at the same time as the completion of the etching of the original material to be etched 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and in particular to a method for detecting the end point of etching in a step of patterning a metal film, semiconductor film, or insulating film by dry etching or using selective chemical gas. This invention relates to improving the accuracy of a method in which a laser is irradiated onto the surface of a semiconductor substrate and changes in the intensity of reflected light are used to monitor the thickness of a grown film in the process of growing a semiconductor film or an insulating film by phase growth.

Conventionally, in this type of end point detection method or growth film thickness monitoring method, the laser irradiation target is a certain portion of the mask material 1 formed in various patterns in advance, as shown in FIG. The semiconductor substrate surface has no mask material 1 and exposed parts of the etched material or the growth target surface 2, or
Or, as shown in Figure 2, mask material 1 is prepared in advance.
The surface of the semiconductor substrate was an exposed material to be etched or a surface to be grown 2 without any mask material 1 from which all of the mask material 1 had been removed.

By the way, in the above-mentioned conventional end point detection method or growth film thickness monitoring method, the etching rate of the material to be etched 2 or the growth rate of the film 2 is higher than that of the mask material 1 during dry etching or selective chemical vapor deposition. As a result, the temporal accuracy of detecting the end point or the end point of growth deteriorates.

FIGS. 3A to 3C are diagrams of the semiconductor substrate at the time of end point detection, for explaining the above-mentioned problems.

FIG. 3a is a plan view. FIG. 3 is a cross-sectional view of a portion 11 and 12 of FIG. 3a connected by a straight line. FIG. 3C is a cross-sectional view of a portion 13 and 14 in FIG. 3A connected by a straight line. Due to the difference in the pattern of the mask material 1 during dry etching, in FIG. Figure 3C showing the parts
In this case, the etching of the material to be etched 2 is not yet completed. Normally, we would like to detect the end point of the part C in Figure 3 where etching completion is delayed, but the laser beam size is
The exposed area of the material 2 to be etched in the portion shown in FIG. 3 is larger than that in FIG. I was left and right.

Therefore, there is a problem in that the end point is detected earlier than the actual etching of the portion of the mask material 1 with a small opening area is completed.

Furthermore, depending on the dry etching conditions, the difference in the etching speed of the material to be etched 2 depending on the pattern of the mask material 1 may be opposite to the above case, and the end point may be detected at a later point than the actual completion of etching. .

Also, in selective chemical vapor deposition, there is a problem that the actual grown film thickness and the film thickness monitor value deviate, similar to the above-mentioned dry etching.

1-1 - In this invention, a plurality of patterns are designed and formed with the pattern size and shape of a portion where etching end point detection or film thickness monitoring is desired.

According to the above method, since the laser irradiation target is a collection of patterns with the same size and shape as the pattern of the part where the end point is to be detected, the exposed area of the material to be etched that is irradiated with the laser increases, and the laser The etching of the irradiation target is completed at the same time as the etching of the part where the end point is to be detected is completed, and the intensity of the laser reflected light can be greatly changed.

Similarly, in selective chemical vapor deposition, the film thickness monitor value can be set to the same thickness as the portion where the film thickness is desired to be monitored.

Tsubouen This invention will be explained below with reference to the drawings.

FIGS. 1A to 1S are plan views of laser irradiation targets on a semiconductor substrate in embodiments of the present invention having different patterns.

In the case of FIG. 1a, the pattern of the mask material 1 is formed in the shape of four aggregates, so that the pattern is straight. Due to this,
Etching of the original material to be etched 2a and the three dummy materials to be etched 2b is completed at the same time, and since they are a collection of four materials, the change in the intensity of the laser reflected light is the same as that of one material. The etching end point is detected at the same time as the etching of the material 2a to be etched is completed.

In the case of Figure 1, the pattern of the mask material 1 is made by providing 15 dummy etching materials 2d of the same size and shape in addition to the original small square etching material 2c, and forming 16 square etching materials. The material to be etched is formed into an aggregate shape so that the material to be etched is exposed. As a result, the etching of the small square original material to be etched 2c and the dummy material to be etched 2d are completed at the same time, and since they are a collection of 16 pieces, the change in the intensity of the laser reflected light is , is 16 times larger than in the case of one piece, and the completion of etching of the laser irradiation target is detected at the same time as the completion of etching of the original material to be etched 2c.

Incidentally, although the above example describes the case of dry etching, film formation using selective chemical vapor deposition can also be performed.
Since a growth rate difference occurs depending on the growth pattern, the only difference is that the film grows in the opposite direction to that which was etched in the above embodiment, and it can be applied as a growth film thickness monitor for a film through which a laser beam passes.

As explained above, the present invention uses a laser irradiation target for end point detection to design and form a mask material as an aggregate according to the pattern shape in which the end point of dry etching is to be detected. The end point can be detected at the same time as the end point of the pattern you want to detect.

Similarly, in selective chemical vapor deposition, the film thickness monitor value can be set to the same thickness as the film thickness of the pattern to be monitored.

[Brief explanation of drawings]

FIGS. 1A to 1S are plan views of semiconductor substrates of different embodiments of the method of this invention. FIGS. 2A to 2S are plan views of semiconductor substrates according to different examples of the conventional method. FIGS. 3A to 3C are a plan view and a cross-sectional view of a semiconductor substrate at the time of detecting the end point of dry etching in a conventional method. 1... Mask material, 2 a + 2 c... Original material to be etched or surface to be grown, 2b, 2d... Dummy material to be etched or surface to be grown, 3... Base material, 11, 12. 13. 14... Symbol that corresponds to a plan view and a cross-sectional view. d Figure (b) Mask group 2b12'-', y'''-1jz%>7''1-JcoP
J 寥形癲11 Figure (a) Figure (b)

Claims (1)

[Claims] 1. In the process of patterning a metal film, semiconductor film, or insulating film formed on a semiconductor substrate by dry etching, or in the process of forming a semiconductor film or an insulating film on a semiconductor substrate, the end point of etching is In order to detect or monitor the thickness of a formed film, a laser is irradiated onto the surface of a semiconductor substrate and changes in the intensity of the reflected light are used to detect the end point of the laser irradiation and the end point of etching. Alternatively, it can be created in advance in the form of a collection of multiple patterns with the same size and shape as the pattern whose thickness is to be monitored, thereby improving the temporal accuracy of detecting the end point of etching or monitoring the thickness of the formed film. A method for manufacturing a semiconductor device, characterized in that: