JPH02291109A - Development method - Google Patents

Abstract

PURPOSE:To easily form a resist pattern whose cross-sectional shape is rectangular by a method wherein a cooled developer is supplied onto a resist and the resist is heated after the developer come to a standstill on a substrate. CONSTITUTION:Immediately after a developer 2 has been supplied onto a semiconductor wafer 1, the developer 2 is shaken. Since the developer 2 is held in a cooled state during this period, a dissolution speed of a resist by the developer 2 is extremely small; accordingly, a developing operation of the resist hardly progresses. After the developer 2 has been supplied onto the semiconductor wafer 1, a shake of the developer 2 is settled after a short time; the developer 2 comes to a standstill on the semiconductor wafer 1. Then, in a state that the developer 2 is at a standstill on the semiconductor wafer 1, this developer 2 is heated up to, e.g. about room temperature by using, e.g. a heating apparatus 4 which has been installed directly above the semiconductor wafer 1. The dissolution speed of the resist by the developer 2 is increased by this heating operation by means of the heating apparatus 4; the developing operation of the resist by the developer 2 progresses. Thereby, after the developing operation has been finished, it is possible to easily obtain a resist pattern whose cross-sectional shape is rectangular.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing method, and particularly to a resist developing method.

[Summary of the invention]

The present invention provides a developing method in which a resist pattern is obtained by exposing a resist formed on a substrate in a predetermined pattern and then developing the resist, supplying a cooled developer onto the resist, The resist is heated after the developer comes to rest on the substrate.

As a result, a resist pattern having a rectangular cross-sectional shape can be easily obtained.

[Conventional technology]

In the lithography process in the manufacturing process of semiconductor devices, a resist is first applied onto a semiconductor wafer, then this resist is exposed in a predetermined pattern using an exposure device, and the exposed resist is developed to form a desired resist pattern. obtain.

Conventionally, as a method for developing the above-mentioned resist, a method is known in which development is performed by supplying a developer at room temperature onto a semiconductor wafer on which a resist is formed.

[Problem to be solved by the invention]

However, with the conventional developer supply method, it is impossible to avoid the developer from shaking when it is supplied onto the semiconductor wafer, and as a result, a resist pattern with a rectangular cross-sectional shape cannot be obtained. was difficult. The reason for this will be explained in detail below.

In recent years, with the progress of pattern miniaturization, resist exposure is often performed using a reduction projection exposure apparatus (stepper). The light intensity distribution during exposure by this reduction projection exposure apparatus is rectangular directly below the mask pattern on the reticle, but usually becomes a broad distribution on the semiconductor wafer.

According to the findings of the present inventors, in order to obtain a resist pattern with a rectangular cross-sectional shape, it is necessary to increase the dissolution rate of the upper layer when developing the exposed resist. This is due to the following reasons. That is, in the exposed portion of the resist, the surface tension of the developer in the vicinity of the surface decreases due to the resist eluted by the developer. As a result, the affinity of the developing solution for the resist improves, and the rate of dissolution from 1 to 1 is increased. That is, as the development progresses to the lower layer of the resist, the amount of dissolved resist increases, and the dissolution rate of the resist gradually increases. This tendency becomes particularly noticeable when the developer is stationary on the semiconductor wafer. The resist dissolution rate characteristic in this case is as shown by curve a in FIG. If a resist dissolution rate characteristic as shown by this curve a is obtained, a resist bag having a rectangular cross section can be formed on the semiconductor wafer 101 as shown in FIG. 3.

However, as mentioned above, in the conventional developer supply method 2, the developer oscillates on the semiconductor wafer, and the resist eluted by the developer is diffused in the developer by this oscillation. As a result, the resist dissolution rate does not increase even in the lower layer of the resist. In this case, the resist dissolution rate characteristic becomes as shown by curve b in FIG. 2, and the cross-sectional shape of the resist pattern 102 obtained by development becomes a tapered shape as shown in FIG. 4, which is different from a rectangular shape. No.

As described above, it has been difficult to obtain a resist pattern with a rectangular cross-sectional shape using conventional development methods.

Therefore, an object of the present invention is to provide a developing method that can easily obtain a resist pattern having a rectangular cross-sectional shape.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a developing method in which a resist pattern is obtained by exposing a resist formed on a substrate (1) in a predetermined pattern and then developing the resist. A cooled developer (2) is supplied, and the resist is heated after the developer (2) has come to rest.

Here, the cooling temperature of the developer (2) is selected to be such a temperature that the progress of development of the resist can be suppressed, and is selected, for example, to a temperature within a range of about 5° C. from the freezing point of the resist to be used. Specifically, this cooling temperature is, for example, 0 to
The temperature is selected within a range of about 5°C. On the other hand, the developer (
The heating temperature in step 2) is selected so that the rate of resist dissolution by the developer (2) is sufficiently high for practical purposes. This heating temperature is practically sufficient at a temperature at which the resist dissolution rate by the cooled developer (2) recovers to the same level as before cooling, for example. This heating temperature is specifically selected to be about room temperature, for example.

As a developing device for actually carrying out this development, for example, a standard developing device that is commonly used is equipped with a cooler (3) for cooling the resist and a heating device (4) for heating the resist. The configuration provided can be used.

[Effect]

The developer (2) supplied onto the resist after exposure oscillates at first, but becomes stationary after a while. Here, since the developer (2) has been cooled, the development of the resist does not proceed while it is being oscillated.

Therefore, when the cooled developer (2) is then heated to, for example, room temperature, the rate of resist dissolution by the developer (2) increases and development of the resist progresses.

In this way, the developing solution (2) is in a cooled state while it is rocking on the substrate (1), so the development of the resist does not proceed during this time, and development does not proceed until after it is heated. It will start to progress. As a result, a resist dissolution rate characteristic as shown by curve a in FIG. 2 is obtained, and the cross-sectional shape of the resist pattern obtained by development becomes a rectangle similar to that shown in FIG. 3.

As described above, according to the above-described means, it is possible to easily obtain a resist 1 pattern having a rectangular cross-sectional shape.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, development is performed using a single-wafer type developing device equipped with a developer cooler and a heating device, as will be described later.

1A to 1C illustrate a developing method according to an embodiment of the present invention.

In FIG. 1A, reference numeral 1 indicates a semiconductor wafer, such as a silicon wafer. On this semiconductor wafer 1,
A resist (not shown), such as a positive photoresist, which has been exposed in a predetermined pattern using, for example, a reduction projection exposure device, is applied. Therefore, first, a developer 2 supplied from a developer supply source (not shown) is cooled by passing through a cooler 3, and then a predetermined amount of the cooled developer 2 is supplied onto the semiconductor wafer 1. Here, the cooling temperature of the developer 2 is selected so that the resist dissolution rate by the developer 2 is sufficiently low, and specifically, for example, 0°C.
selected according to degree. Further, various types of developer can be used as the developer 2, and specifically, for example, an alkaline developer containing 2.38% of tetramethylammonium hydroxide is used.

Immediately after the developer 2 is supplied onto the semiconductor wafer 1, the developer 3 oscillates, but during this time the developer 2 remains cooled, so the rate of resist dissolution by the developer 2 is extremely small. , therefore, the development of the resist hardly progresses.

After a while after the developer 2 is supplied onto the semiconductor wafer 1, the shaking of the developer 2 stops, and the developer 2 becomes stationary on the semiconductor wafer 1, as shown in FIG. 1B.

Next, as shown in FIG. 1C, while the developer 2 is stationary on the semiconductor wafer 1 as described above, the developer 2 is heated, for example, by a heating device 4 provided directly above the semiconductor wafer 1. Heat to about room temperature. Here, as the heating device 4, specifically, for example, an infrared heating device or a microwave heating device can be used. This heating device 4
The resist dissolution rate of the developer 2 increases due to the heating, and the development of the resist by the developer 2 progresses.

After the development is completed in this way, the development process is completed after processing such as rinsing and drying.

As described above, according to this embodiment, the developer 2 cooled to a temperature that prevents the development of the resist from proceeding is supplied onto the semiconductor wafer 1 on which a resist exposed in a predetermined pattern is formed. After the fluctuation of the developer 2 has subsided and it is in a stationary state, the developer 2 is heated by the heating device 4 to, for example, room temperature to increase the resist dissolution rate and progress the development. A resist dissolution rate characteristic as shown by curve a in the figure is obtained, and as a result, after development is completed, a resist pattern having a rectangular cross-sectional shape similar to that shown in FIG. 3 can be easily obtained.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiment, the case where the substrate is the semiconductor wafer 1 is explained, but the semiconductor wafer 1
It is possible to use various types of substrates other than the above.

〔Effect of the invention〕

Since the present invention is configured as described above, a resist pattern having a rectangular cross-sectional shape can be easily obtained.

[Brief explanation of the drawing]

1A to 1C are cross-sectional views for explaining the developing method according to an embodiment of the present invention in the order of steps, FIG. 2 is a graph showing the dissolution rate characteristics of the resist, and FIGS. 3 and 4 are FIG. 3 is a cross-sectional view showing the cross-sectional shape of each resist pattern. Explanation of main symbols in the drawings 1. 2. Semiconductor wafer, 2. Developing solution, 3. Cooler, 4.
: Heating device.

Claims (1)

[Scope of Claims] A developing method in which a resist pattern is obtained by exposing a resist formed on a substrate in a predetermined pattern and then developing the resist, wherein a cooled developer is supplied onto the resist. A developing method characterized in that the resist is heated after the developer comes to rest on the substrate.