KR20040070826A - Method for inspecting photo process margine in a semiconductor device - Google Patents

Abstract

PURPOSE: A method for inspecting a margin of a photolithography process is provided to overcome a variation of a process margin by estimating the margin of the first and second photolithography processes after a photoresist layer pattern is formed and an etch process is performed and by estimating a final process margin. CONSTITUTION: Exposure energy and focus is varied in the X-Y axis with respect to each die of a semiconductor wafer having a photoresist layer pattern to perform a photolithography process. The width of the photoresist layer patterns formed on each die according to the variation of the exposure energy and focus is measured(S100). The interval of exposure energy and focus is extracted to be set as the first photolithography process margin, having a width corresponding to the specification of the exposure equipment among the width of the photoresist layer patterns(S102). Each die is etched according to the photoresist layer pattern to form an arbitrary pattern in each die(S104). The exposure energy and focus with respect to the arbitrary pattern is varied in the X-Y axis to perform an exposure process. The width of the patterns formed in each die according to the variation of the exposure energy and focus is measured(S106). The interval of the exposure and focus is extracted to be set as the second photolithography process margin, having a pattern width corresponding to the specification among the width of the patterns(S108). The first and second photolithography process margins are compared to extract a final process margin(S110).

Description

TECHNICAL FOR INSPECTING PHOTO PROCESS MARGINE IN A SEMICONDUCTOR DEVICE

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photolithography process. In particular, a photolithography process margin inspection of a semiconductor device capable of determining whether there is a process margin by checking the focus and energy margin in a matrix form using a wafer before proceeding. It is about a method.

In general, in order to establish a new semiconductor line or to evaluate the manufacturing capability index of the semiconductor device according to the introduction of new equipment, various evaluation methods are executed, and a long-term evaluation seal is required.

In other words, when producing a specific semiconductor device with newly purchased equipment in the current production line, each process step of the semiconductor device has a unique margin or process index of process capability and process step. In order to evaluate the index, various variables must be measured.

Photographic process margin inspection method of a conventional semiconductor device requires a large number of types of inspection, such as measuring the size of a predetermined pattern, for example, in the photographic process, the depth of focus (Depth of Focus; DOF) and the exposure energy size margin In addition, astigmatism, such as field uniformity and lens aberration, of a reduced exposure apparatus, should also be measured.

Hereinafter, a conventional photographic process margin inspection method will be described with reference to the accompanying drawings. 1 is a view for explaining a conventional photo process margin measurement method.

First, as shown in FIG. 1, the exposure focus is changed in the horizontal direction (X-axis) during the exposure process for each die 12 on the semiconductor wafer 10 using the reduced exposure apparatus, and After the exposure process is performed by changing the exposure energy in the direction (Y-axis), lines / spaces (hereinafter referred to as L / S) in each die 12 formed on the semiconductor wafer 10 are angulated with an SEM measuring device. Exposure energy and focus section satisfying the specifications of the equipment (for example, 0.21 μm to 0.25 μm) after measuring the width of the pattern (Development Inspection Critical Dimension) according to the focus change of the horizontal axis (X axis) based on the energy axis If you confirm, the dies correspond to the X-marked area.

The widths of the photoresist pattern according to the exposure energy and the focus change of the dies included in the area X are shown in Table 1 below.

-0.2 -0.1 0 0.1 0.2 30 mJ 0.2456 0.2458 0.2475 0.2498 0.2487 34mJ 0.2311 0.2354 0.2325 0.2336 0.2358 38mJ 0.2214 0.2252 0.2256 0.2255 0.2245

As shown in Table 1 above, even if the change in focus is changed from -0.2 to 0.2, the specification of the process equipment is satisfied. Therefore, the focus margin is -0.2 to 0.2 in the photo process margin, and the exposure energy margin is 30 Mj to 38 Mj.

Arbitrary patterns of the die 12 are formed on the wafer 10 in accordance with the photoresist pattern formed on the die 12 based on the photo process margin measured in this way.

However, the photo process margin measurement method as described above can measure the process margin at which the production of the product starts, but there is a problem that cannot be solved such as a change in the process margin generated while the product is continuously being processed.

An object of the present invention is to solve the problems of the prior art, and after the pattern is formed by a photo process, the size of the pattern is inspected and the etching process according to the pattern after the size of the pattern is inspected after each pattern of The present invention provides a method for inspecting a photo process margin of a semiconductor device capable of securing a photo process margin by checking a detailed difference.

In order to achieve the above object, the present invention, for each die of the semiconductor wafer on which the photosensitive film pattern is formed to change the exposure energy and focus to the XY axis to proceed the photographing process, each die according to the exposure energy and focus change Measuring a width of the photoresist patterns formed on the substrate; extracting an exposure energy and a focus period having a width corresponding to a specification of an exposure apparatus among the widths of the patterns, and setting the first photo process margin as a first photo process margin; Etching each die of the semiconductor wafer in accordance with the photoresist pattern to form an arbitrary pattern on each die, and changing exposure energy and focus to the XY axis with respect to the arbitrary pattern. And patterns formed on the dies according to the exposure energy and the change in focus. Measuring a width of the light source; extracting an exposure energy and a focus period having a pattern width corresponding to the specification among the widths of the patterns and setting the second photo process margin; Comparing the final process margin.

1 is a view for explaining a photographic process margin inspection process according to the prior art,

2 is a flowchart illustrating a photographic process margin inspection process of a semiconductor device according to the present invention;

3 is a view for explaining a photo process margin inspection process of a semiconductor device according to the present invention.

<Description of the code | symbol about the principal part of drawing>

10 wafer 12 die

There may be a plurality of embodiments of the present invention, and a preferred embodiment will be described in detail below with reference to the accompanying drawings. Those skilled in the art will be able to better understand the objects, features and advantages of the present invention through this embodiment.

Hereinafter, a photographic process margin inspection method of a semiconductor device will be described with reference to the accompanying drawings. 2 is a flowchart illustrating a photographic process margin inspection process of a semiconductor device according to the present invention.

Prior to the description, a photosensitive film pattern is formed on the wafer by exposure with a reticle having an arbitrary mask pattern.

Referring to FIG. 2, each die 12 of the semiconductor wafer image 10 on which the photoresist pattern is formed is subjected to a reticle exposure process using a reduced exposure apparatus with a reticle used at the time of photoresist pattern formation. At this time, the exposure process is performed by changing the exposure focus in the horizontal direction (X axis) and changing the exposure energy in the vertical direction (Y axis), and scanning the photosensitive film pattern width of each die 12 formed on the semiconductor wafer 10. Measure with a measuring device (S100). At this time, the SEM measuring device measures the pattern width according to the change in focus for each exposure energy.

Among the measured photoresist pattern widths, an exposure energy and a focus section having a pattern width corresponding to a specification of the exposure equipment (for example, 0.21 μm to 0.25 μm) are extracted and set as a first photo process margin (S102).

Each die 12 of the semiconductor wafer 10 is etched according to the photosensitive film pattern based on the first photographic process margin set in step S102, and an arbitrary pattern is formed on each die as shown in FIG. 3 (S104). .

Then, the exposure process is performed with the reticle used at the time of photosensitive film pattern formation with respect to each die 12 on the semiconductor wafer 10 on which the arbitrary pattern was formed using the reduction exposure apparatus. At this time, the exposure process is performed by changing the exposure focus in the horizontal direction (X axis) and changing the exposure energy in the vertical direction (Y axis) in the same manner as measuring the photoresist pattern width. The width of the patterns formed on each die 12 is measured (S106).

As an example, it can be seen that the widths of the patterns 14 formed in each die 12 are shown in Table 2 below.

-0.2 -0.1 0 0.1 0.2 30 mJ 0.2556 0.2458 0.2475 0.2498 0.2587 34mJ 0.2011 0.2354 0.2325 0.2336 0.2558 38mJ 0.2514 0.2252 0.2256 0.2255 0.2045

The exposure energy and the focus section having the pattern width corresponding to the specifications of the exposure equipment (for example, 0.21 µm to 0.25 µm) are extracted from the pattern widths measured in step S106 and set as the second photographic process margin (S108). In this case, unlike the first photo process margin, it can be seen that the pattern width at the exposure focus (-0.2 and +0.2) shows a defect pattern not satisfying the specification of the exposure apparatus as shown in Table 2 above.

The user may calculate the final process margin necessary for the photo process using the difference between the first photo process margin after the exposure process and the second photo process margin after the etching process, and then proceed with the photo process using the final process margin. In addition, it is possible to grasp from the viewpoint of the pattern formed after etching what point is a problem in the focus margin (or exposure energy margin) which was not abnormal in the photoresist pattern (S110 and S112).

As described above, the present invention calculates the first and second photo process margins after forming the photoresist pattern and after the etching process, and then calculates the final process margin by comparing the first and second photo process margins, thereby processing process margins according to the process progress. Can overcome the change.

Claims (2)

Performing a photographic process by changing the exposure energy and focus on the X-Y axis of each die of the semiconductor wafer on which the photoresist pattern is formed, and measuring the widths of the photoresist patterns formed on the die according to the exposure energy and the focus change; Extracting an exposure energy and a focus period having a width corresponding to a specification of an exposure apparatus from among the widths of the patterns and setting the first photo process margin; Etching each die of the semiconductor wafer according to the photoresist pattern based on the first photo process margin to form an arbitrary pattern on each die; Performing an exposure process by changing exposure energy and focus on the X-Y axis with respect to the arbitrary pattern, and measuring widths of patterns formed on the dies according to the exposure energy and focus change; Extracting an exposure energy and a focus period having a pattern width corresponding to the specification from the widths of the patterns and setting the second photo process margins; And comparing the first and second photo process margins to extract final process margins. The method of claim 1, The photographic process margin inspection method of the semiconductor device, the final process margin photographic process margin inspection method of the semiconductor device, characterized in that further comprising the step of applying to the photographic process in the future production of the product.