JPH02260423A - Dry etching of organic film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for dry etching an organic film formed with a batten, and more particularly to an etching method that is effective in making the etching rate of the organic film equal regardless of the aspect ratio of the batten.

[Conventional technology]

As a conventional method for etching a resist film of a multilayer resist, for example, the 35th Applied Physics Association Lecture Preliminary Collection,
As stated in Volume 2, 28a-G-4, p496,
In order to prevent side etching that occurs during dry etching of a resist film, a method is known in which the substrate temperature is cooled to -100° C. before etching.

[Problem M that the invention attempts to solve]

The above-mentioned conventional method for etching a resist film of a multilayer resist has the effect of preventing side etching, but does not take into account the dependence of the etching rate on the aspect ratio that occurs when etching a resist film. An object of the present invention is to provide a batten forming method in which the etching rate of an organic resist film does not depend on batten dimensions such as aspect ratio by controlling the temperature of the substrate. (Means for solving the problem 1) The above purpose is achieved by dry etching the organic film with oxygen-containing plasma while keeping the temperature of the substrate coated with the organic film in the range of -110°C or lower -135°C or higher. achieved.

[Effect 1] In dry etching of organic films, the substrate temperature is
By controlling the temperature within the range of 0°C or below - 135°C or above,
Deposit reaction products generated during dry etching of organic films. Due to the attachment of this deposited film, it is possible to reduce the aspect ratio dependence of the etching rate of the organic film, which has been a problem in the past. (Example) The present invention will be explained below with reference to Examples. In this example, as shown in FIG. After coating the top 2 and heat-treating at a temperature of 200° C. or higher, a 5jO7 film 3 of 0.1 μm was formed, and then an organic resist film 4 of 1 μm was coated again, and the organic resist film 4 was exposed and developed. and pattern it.
Using the upper organic resist 4 as a mask, the intermediate SiO
2 film 3 is etched. Then, using the upper organic resist film 4 and the middle 5in2 film 3 as masks, the lower 2 μm organic resist film 1 is dry etched to form a resist mask. This lower organic resist film 1
In dry etching, etching is performed using an etching gas containing oxygen. The etching device used was one capable of applying high frequency power of 13.56 MHz to the discharge electrode, and was connected to a liquid nitrogen tank for cooling. When dry etching the sample shown in FIG. 2, the aspect ratio dependence of the etching rate of the organic resist film is can be suppressed. FIG. 1 shows the etching rate when changing the substrate temperature. Etching pressure is 5 mTorr
, the high frequency power is 60v. The difference in etching speed between 10 μm space 5 and 0.5 μI space 6 is 20°C.
It is 32%. The etching speed at this time is 10μ
The speed was 0.8 μs/win in the m space, and 0°54 μm/min in the 0.5 μm space. The temperature at which the difference in etching rate becomes the smallest is 17% at -120°C. The etching speed at this time is 0.7 in a 10 μm space.
57zw/min, 0.5μm space 0.62μ
m/min. Figure 3 shows the processed shape at this time. FIG. 4 shows the etching rate of the organic resist film when the high frequency power was 901i1. The minimum difference in etching speed between 10 μm space and 0.5 μm space is 13
%, and the etching rate at this time was 0.88 μm/min for a 10 μm space, and 0.76 μm/min for a 0.5 μm space. The temperature at which the difference in etching rate becomes smaller is -1115° C., which is shifted to a higher temperature side than when the high frequency power is 60111. Figures 5(a) and 5(b) show the intermediate shapes of the organic resist mask formed at substrate temperatures of -100°C and -135°C, respectively. The etching pressure was 5 mTorr and the high frequency power was 60W. In (a), the substrate temperature is -100'C, and the etching rate for a 0 μm space with a small aspect ratio is 0.78 μm.
0.5μm with large m/l1in and large aspect ratio
The space etching rate is as low as 0.58 μm/n+in. In (b), the substrate temperature is -13.5°C, and contrary to (a) above, the etching rate of the 0.5 μm space with a large aspect ratio is as high as 0.74 μm/min, and the etching rate of the 10 μm space with a small aspect ratio is as high as 0.74 μm/min. Etching speed is 0.
It is small at 56 μm/win. Note that at this temperature, the pattern is formed in a forward taper by the deposited film, and it is also possible to form a narrower space than the original upper layer pattern. In dry etching of organic resist film (a), (
b) Figure 6 shows the processed shape during etching when dry etching was performed for 30 seconds under two types of etching conditions. By combining the two types of etching conditions (a) and (b), the difference in etching speed between the 10 μm space and the 0.5 μm space can be kept within 5%. According to the present invention, in the sample shown in FIG. 2, when the film thickness of the organic resist 1 as the film to be etched is lpm, the film thickness of the organic resist 1 is 2 μm between the 5pI11 space and the 0.2511II11 space. It was confirmed that the same results as in the example were obtained. In addition, in the present invention, the substrate temperature during etching of the organic resist film 1 is below -100°C, at which point the etching rate in a wide space begins to drop and the difference in etching rate depending on pattern dimensions begins to decrease; Even if the etching speed decreases, it is preferable that 30% or more of the etching speed at room temperature can be obtained and the etching speed is within a range that does not cause problems in normal processing. Specifically, 0,5 J+m/
The temperature range in which an etching rate of min or higher is ensured is preferably -135°C or higher. If the substrate temperature is higher than 1100°C, side etching occurs during processing of the organic resist film 1, making it impossible to perform high-precision processing.Incidentally, when the substrate temperature is 190°C, the dimensional shift amount is 0. .1pm. Further, if the substrate temperature is lower than 1135° C., a sufficient etching rate cannot be obtained. For example, if the substrate temperature is
The etching speed at 40° C. is 0.2 μm, which is not a practical speed. Furthermore, according to the present invention, by suppressing the dependence of the etching rate on pattern size, there is no longer a need for long-time overetching as in the past, so that the size shift from the upper layer pattern due to overetching can be reduced and the pattern size can be reduced. Resist films can be processed with high precision. Furthermore, although the above embodiment uses a microwave plasma etching apparatus, a 13.56M7 RIE (
A similar effect can be obtained by using other discharge type etching equipment such as parallel plate electrode type reactive sputter etching.6 In addition to novolac type etching materials,
Similar effects were obtained with other organic films such as polyimide, acrylic, styrene, and cyclized rubber. Effect of the Invention 1 According to the present invention, the batten size dependence of the etching rate that occurs during dry etching of an organic film can be extremely effectively reduced by controlling the cooling temperature of the substrate.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the etching rate of an organic resist film and substrate temperature for different pattern sizes at a high frequency power of 60 W, and FIG. 2 is a cross-sectional view of a multilayer resist film according to an embodiment of the present invention before etching Figure 3 shows high frequency power 60
Cross-sectional view of the etched portion of the multilayer resist at w, No. 4
The figure is a cross-sectional view of the etched part showing the relationship between the etching rate of the organic resist film and the substrate temperature due to the difference in pattern size with high-frequency power 9011. Figure 5 (a) is a cross-sectional view of the etched part of the multilayer resist at a substrate temperature of -100°C. Fig. 5(b) is a cross-sectional view of the etched part of the multilayer resist at a substrate temperature of -135°C, and Fig. 6 is a sectional view of Fig. 5(a), (
FIG. 4 is a cross-sectional view of the etched portion of the multilayer resist in the etching combination of conditions b). Explanation of symbols 1... Lower organic resist film, 2... Semiconductor substrate, 3
...Sin, film, 4...organic resist mask, 5.
...10μ■ space, 6...0.5μm space,
t M diagram f Quantity, J, Ll, /i (°S

Claims (1)

[Claims] 1. In a method of dry etching an organic film on a substrate using oxygen-containing plasma, the substrate temperature is -100°C.
A dry etching method for an organic film, characterized in that the etching is controlled to a temperature of -135° C. or higher. 2. A dry etching method for an organic film, comprising etching stepwise at a plurality of temperatures by changing the substrate temperature within the temperature range according to claim 1. 3. A dry etching method for an organic film, comprising etching by continuously changing the substrate temperature within the temperature range according to claim 1.