JPH0685084B2 - Method of forming resist film pattern - Google Patents

Description

Detailed Description [Overview] An upper resist film made of a silicon polymer is exposed and developed, and then reactive ion etching is performed with hydrogen ions, and then a lower resist film is reactive ion etched with oxygen ions.

Then, the silicon residue of the upper resist film is removed and the patterning is completed.

TECHNICAL FIELD The present invention relates to a method for forming a resist film pattern, and in particular,
A method for patterning a multilayer resist.

When manufacturing semiconductor devices such as ICs, the photo process in the wafer process is extremely important, and miniaturization of ICs has been greatly promoted by the progress of photo technology (lithography technology).

However, if the pattern is as fine as sub-micron, it is not easy to pattern the semiconductor layer with a single-layer resist film with high precision, and a method of forming a two-layer or three-layer multilayer resist film pattern is adopted. Has been.

However, when forming such a multilayer resist film pattern, sufficient care must be taken so that each layer of the resist is patterned with high accuracy.

[Prior Art] The reason why a two-layer or three-layer multilayer resist film pattern is formed is that it has high sensitivity and high resolution, and has good dry etching resistance against plasma etching.
This is because it is difficult to obtain a resist material having both high pattern accuracy and etching resistance.

FIG. 2 (a) shows a pattern of a conventional three-layer resist film, S is a substrate to be processed, 1 is a novolac-based resist film (for example, AZ1300), 2 is a silicon-based resist film, 3 is high sensitivity, Resist film with high resolution (eg PAAM, PGM
A etc.). In such a three-layer resist film pattern, since the pattern of the resist film 3 is formed with high accuracy, the high accuracy pattern is transferred to the silicon-based resist film 2 having oxygen plasma resistance. Using the pattern of the silicon-based resist film 2 as a mask, the novolac-based resist film 1 is patterned by plasma etching with oxygen. Then, the substrate S to be processed is dry-etched and patterned by the three-layer resist film pattern. Then, since the novolac-based resist film having good dry etching resistance is formed with high precision, a high-precision pattern can be formed on the substrate S to be processed.

Further, FIG. 2B shows a two-layer resist film pattern, S is a substrate to be processed, 11 is a novolac resist film, 12
Is a silicon-based resist film. In this two-layer resist film pattern, since the pattern of the silicon-based resist film 12 has oxygen plasma etching resistance and can be formed with high accuracy, the pattern of the high-precision resist film 12 is formed.
Using this as a mask, the novolac resist film 11 is plasma-etched with oxygen. When the substrate S to be processed is dry-etched and patterned by the two-layer resist film pattern, the pattern of the novolac-based resist film 11 having good dry etching resistance is formed with high accuracy. A highly accurate pattern can be formed on the substrate S.

In this way, the resist film pattern of the lower layer having good dry etching resistance is provided, and the resist film pattern of high sensitivity and high resolution is formed on the upper layer to form the substrate to be processed with high accuracy. It is a resist film pattern.

[Problems to be Solved by the Invention] However, in such a multilayer resist film pattern, the resist having oxygen plasma etching resistance is a silicon-based resist (silicon polymer), and the one having relatively good dry etching resistance is It is a novolac resist.

However, in the step of sequentially exposing and developing each of these layers, when patterning the silicon-based resist film,
A small amount of silicon (such as silicon oxide) residue is likely to remain, which makes it difficult to remove it by oxygen plasma etching. As shown in FIG. 2 (b), silicon is removed in the portion to be removed. The residue r remains, which is a major cause of pattern defects.

The present invention proposes a method for forming a resist film pattern that eliminates such incomplete pattern formation.

[Means for Solving the Problems] The object is to provide a method for patterning a multilayer resist in which a resist film having dry etching resistance is used as a lower layer and a resist film made of a silicon polymer is used as an upper layer, and the upper layer made of the silicon polymer is used. Exposing and developing the resist film of
Then, after performing reactive ion etching with hydrogen ions, the underlying resist film is subjected to reactive ion etching with oxygen ions to achieve a resist film pattern forming method.

[Operation] That is, in the present invention, after exposing and developing the upper resist film made of a silicon polymer, reactive ion etching is performed with hydrogen ions, and then the lower resist film is reactive ion etched with oxygen ions.

Then, the silicon residue remaining during the exposure / development of the upper resist film is removed to eliminate the incomplete pattern.

[Examples] Hereinafter, examples will be described in detail with reference to the drawings.

FIGS. 1A to 1C are sectional views in order of steps of the forming method according to the present invention. First, as shown in FIG. 3A, a novolac-based resist film (for example, AZ13) having a film thickness of 1 to 2 μm and good dry etching resistance is formed on the substrate S to be processed.
00) 21 is applied, and a silicon polymer (silicon-based resist: siloxane) 22 having a film thickness of 0.1 to 0.2 μm is further applied thereon, using a desired mask (not shown),
For example, to form a 0.5 μm wide fine pattern,
The silicon polymer 22 is exposed.

Then, as shown in FIG. 1 (b), the silicon polymer
After developing 22, reactive ion etching using hydrogen (H ₂ ) gas is performed. The etching conditions are, for example, high frequency power of 0.3 to 1 watt / cm under a reduced pressure of 10 to 15 Torr.
Apply ² . Then, the silicon residue in the remaining unexposed area (when the silicon polymer is a negative resist) is removed.

Next, as shown in FIG. 1C, the novolac-based resist film 21 is patterned by reactive ion etching using oxygen (O ₂ ) gas using the pattern of the silicon polymer 22 as a mask. The etching conditions are the same as above, with a power of 0.3 to 1 watt / cm ² under a reduced pressure of 10 to 15 Torr.
Is applied. As is well known, Reactive Ion Ecthing is a directional ion etching method using a reactive gas, and is a highly accurate patterning method when etching is performed from directly above.

Using the pattern of the novolac-based resist film 21 having no pattern defect thus formed as a mask, the substrate S to be processed is etched by reactive ion etching using, for example, a fluorine-based gas. Since the resist film pattern is a resist film pattern formed with high accuracy and having resistance to dry etching, the substrate S to be processed is patterned with extremely high accuracy, and the pattern defects disappear.

Although the above-described embodiment has been described with the two-layer resist, the same applies to the case of the three-layer resist, and since the silicon residue on the novolac-based resist film 21 is completely removed, the pattern of the novolac-based resist film has no defect. Therefore, a highly precise pattern-free pattern moth is formed on the substrate S to be processed.

[Effects of the Invention] As is apparent from the above description, according to the present invention, a fine pattern is formed with higher accuracy in a photo process,
This is a significant contribution to high quality and high performance of ICs.

The exposure method is not limited to light exposure but electron beam exposure or X-ray exposure.
Of course, line exposure may also be used.

[Brief description of drawings]

1 (a) to 1 (d) are sectional views in order of the resist film pattern forming process according to the present invention, and FIGS. 2 (a) and 2 (b) are sectional views of a conventional multilayer pattern. In the figure, S is a substrate to be processed, 1,11,21 are novolac-based resist films, 2,12,22 are silicon-based resist films (silicon polymer), and 3 is a high-sensitivity / high-resolution resist film.

Claims (1)

[Claims] 1. A method of patterning a multi-layered resist comprising a resist film having a dry etching resistance as a lower layer and a resist film made of a silicon polymer as an upper layer, exposing and developing the upper resist film made of the silicon polymer,
Next, a method of forming a resist film pattern, characterized in that after reactive ion etching with hydrogen ions, the underlying resist film is reactive ion etched with oxygen ions.