JPS5870530A - Resist pattern formation - Google Patents

Abstract

PURPOSE:To control development hours based on the intensity information and to form a pattern with high accuracy by a method wherein a developing pattern is exposed to the monitor regions of a resit film and an electromagnetic wave is aimed at the regions at the time of a development process and the penetrated electromagnetic wave is detected. CONSTITUTION:Three kinds of patterns as developing patterns are exposed with equal areas to the minotr regions 3a-3c of a resisit film 3 on a substrate 1 before development. The region 3a is formed as the pattern permitting the exposure of all processed substances and the region 3b is formed as the pattern covered all the revese of the processed substance with a resist and the pattern having the same kind of width as that of a fine pattern on the substrate 1 is formed on the region 3c. An electromagnetic wave such as infrared rays is aimed at the respective regions through a mask 7 and the intensity of the infrared rays detectors 8a-8c and developing hours are controlled based on the value detected by the respective detectors 8a-8c at the developing process for the substrate 1 and the fine pattern of the substrate 1 is developed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a resist pattern, and particularly to a method for forming a resist pattern in which dimensional control during a development process is highly accurate.

In recent years, the density of integrated circuits has increased significantly, and the dimensions of the patterns that form the elements are about to become as small as 1 [mu] or the size of an electronic circuit. Such fine pattern formation is shown in Figure 1←)
As shown in FIG. 9, a resist is formed on the substrate l and roughly formed on the workpiece 2}y! This resist film S is irradiated with energy beams such as light, electron beams, or X-rays in accordance with a desired pattern, and then developed as shown in FIG. 4B to form a resist pattern 4. Next, the workpiece 2 is etched using the remaining resist film 3 as a mask, and the resist pattern 4 is transferred onto the workpiece 2 by a pick etching method.

However, this type of method has the following problems. That is, when forming a resist pattern, exposure can be carried out with extremely high precision, but the dimensional controllability of the pattern by development is difficult. For this reason, the development time is controlled while observing the resist pattern 4 with an optical microscope during development. However, for patterns of 1 (11 m) or Sapunchron whose resolution is less than that of an optical microscope, the edges of the patterns become unclear, making it difficult to accurately measure dimensions.

As a result, accurate dimensional control is difficult, and for this reason, fine patterns cannot be formed with high precision.

The present invention has been made in consideration of the above circumstances, and its purpose is to improve pattern size controllability during development of a resist film and to form fine patterns with high precision. be.

First, the present invention will be explained in detail. In the present invention, a resist film is applied and formed on a workpiece, and then the resist film is bonded and formed.
In the method of forming a desired resist pattern by development, a development monitoring pattern is exposed on a monitor area of the resist film before the development process, and electromagnetic waves are irradiated to the monitor area during the development process to expose the monitor area. This method detects the intensity of the electromagnetic waves that have passed through it, and controls the current acid time based on this detected information.

That is, the gist of the present invention is to irradiate an electromagnetic wave onto a monitor area where a development monitor pattern has been exposed, and to measure the dimensions of the developed pattern from the amount of the electromagnetic wave transmitted.

As shown in FIG. 2, three types of patterns are exposed in equal areas 8o as development monitoring patterns in the monitor areas 5a, 6b, and 5c of the resist on the substrate I. Here, the monitor area 5a has a pattern (full area exposure) in which the underlying workpiece 2 is completely exposed as shown in FIG. 3(a), and the monitor area 6b has a pattern as shown in FIG. 3(b) K. A pattern completely covered with resist (1! No light) is formed. Further, the monitor area 6clC forms a pattern in which patterns having a pattern width comparable to that of a confectionery fine pattern are regularly lined up, for example, a line pattern with a predetermined pitch as shown in FIG. 3(C).

Note that 6 in FIG. 2 indicates an element region.

Next, dimension measurement during development is carried out by irradiating each monitor area 5a, 5b, 5c with a source (electromagnetic wave). IK should be selected in a wavelength range that is almost transparent. Ordinary resists are not made of polymer materials, and the substrate 1 and workpiece 2 are made of silicon or silicon compounds, so if the wavelength λ is chosen to be in the infrared absorption range of the resist, the substrate
The transmittance of light to the workpiece 2 can be considered to be approximately 1. Assuming that the intensity of light per unit area is α, the rate of transmission through the resist is α, and the exposure rate of the underlying workpiece in area 5C of the monitor is t, it is detected on the back side of the substrate after a certain period of time. The amount of transmitted light is for the monitor area 6a...
...For I8° monitor area 5b...
・・・・・・・・・α・Work・8゜For monitor area 5C-
・・・・・・・・・・・・・・・ [tα+(x−i)
)I・80. The amount of light in the monitor area 5C increases as development progresses and t increases. Here, since the ideal value of t can be known in advance from the design value of the pattern, if the ratio of the three amounts of transmitted light is measured and the development is stopped when the amount of transmitted light in the monitor area 5C reaches the ideal value, The fine pattern has values extremely close to the design values. For example, if the exposure pattern of the monitor area 5C is a pattern in which the width and spacing of lines are difficult (half area exposure), t=0.5, and the transmitted light amount ratio of the monitor areas 5h, lb, and 5c is I, respectively.
, .alpha., and .alpha., the amount of transmitted light emitted from each region 5a, 5b, 5c changes with development time as shown in FIG. 4.

That is, the transmittance A in the monitor area 5& increases until a certain time, but then becomes constant (1). Monitor area 5
The transmittance B at b is constant (b) regardless of the development time. The transmittance C in the monitor area 5C increases with development time. The appropriate time for development is the transmittance C
t#) is denoted by the time To. In addition,
In FIG. 4, the film reduction in the resist salt 1 in the monitor area 5b is ignored, but even if there is film reduction, the ratio α
The current proper time can be detected in exactly the same way, only by increasing the number of times.

Thus, according to the present invention, it is possible to improve the pattern size controllability when actually designing a resist film, and it is now possible to accurately control 1 [μm] or sub-scale patterns, which has been difficult in the past. It is extremely effective in the production of.

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

Silicon urethane was used for the substrate I, polycrystalline silicon with a thickness of 5000 (^) was used for the workpiece 2, and PMMA (polymethyl methacrylate) with a thickness of 1 [μm] was used for the resist film S. Next, using well-known electron beam exposure technology,
A circuit pattern is exposed on the central element region 6 of the wafer, and patterns similar to those shown in FIG.
The area was formed by exposure to light. Here, although the minimum pattern width of the above circuit pattern was 0.5 (#0), the monitor area 5c has a line width of O, S (μ) and 0.!
A line pattern with an interval of S (sll) was formed.

Next, using urBx (methyl isobutyl ketone) as a developer, after development for a certain period of time, additional development was carried out while monitoring the pattern width to obtain an appropriate pattern width. Fifth
The figure is a schematic diagram showing the pattern width monitoring device used at this time.
IL.

A mask for irradiating only 13b and 13c, 8a,
ljb and 8c are infrared detectors. The pattern width is equivalently monitored by performing the above-described processing based on the detection outputs of the detectors 8a, 8b, and 8c. Note that the infrared light used exhibits strong diffraction due to the monitoring pattern, so the infrared detectors 8a, Ilb, 8
C was brought into contact with the back surface of the wafer so that all transmitted light could be detected.

When the resist pattern thus formed was observed with an electron microscope, it was found that the twin width and interval of the turns in the monitor area 5C were both 0.5 [μm], and the circuit I formed in the element area 6 was Therefore, according to the method of this embodiment, the resist pattern can be formed with repeatability, contributing to higher density of integrated circuits.

Note that the present invention is not limited to the embodiments described above. For example, for the development monitor/(one of the turns, a turn with equal line width and interval) was used, but this can be arbitrarily selected depending on the desired dimension of the turn. Three double areas are not necessarily required, and it is also possible to confirm the development state by exposing an appropriate pattern to one monitor area and detecting the amount of transmitted light in the double area. As a monitor pattern, a checker pattern of a fixed size as shown in Fig. 6 can also be used.Furthermore, in the actual process, the wafer is removed from the developing solution and monitored to check the degree of development. If the incident wavelength is selected appropriately, K
Monitoring in the developer is also possible.

In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawing]

FIG. 1(11)(b) is a schematic cross-sectional view showing the side of conventional resist pattern formation 1, FIGS. 2 to 4 are for explaining the present invention in detail, and FIG. 2 is a plan view; 3(a) to 3(e) are enlarged views of the main parts of FIG. 2, FIG. 4 is a characteristic diagram showing changes in transmittance with respect to development time, and FIG. FIG. 6 is a schematic diagram showing a nine-pattern width monitor mounting, and FIG. 6 is a plan view of a development monitor pattern showing a modified example. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Workpiece, 3...Resist film, 4...Resist pattern, 5a, 5b, 5C...Monitor area, 6...Element area, 7... Mask, 8a. #b, Jic...Infrared detector. Client's agent Patent attorney Takeshi Kagori 2 Figure 1 Figure 21Q Figure 4 Figure 5

Claims (2)

[Claims] (1) A resist film pattern forming method comprising the steps of forming a resist film on a workpiece, exposing the resist film to a desired I lean light, and then developing the resist film. Before the development step, the monitoring area of the resist 1lII4 is exposed to light for use in development monitoring, and during the development process, the monitoring area is irradiated with electromagnetic waves and the intensity of the electromagnetic waves transmitted through the monitor WA is detected. and controlling the development time based on the detected information. (2) The current iron monitor's (turn is /( without g light)
1. The method for forming a turn according to claim 1, characterized in that the pattern consists of a pattern of a turn and a half area exposure. A resist pattern characterized in that the wavelength range of the electromagnetic waves irradiated is in a wavelength range that has a high absorption coefficient for the resist film, a high transmission coefficient for the workpiece, and does not expose the resist film to light. Formation method.