JPS63178529A - Resist pattern forming method - Google Patents

Abstract

PURPOSE:To obtain an excellent resist pattern by treating a lower layer resist by a developer, into which a liquid having solubility to an upper layer resist is mixed, when an upper-layer resist pattern is transferred to the lower layer resist. CONSTITUTION:When an ultraviolet beam positive type resist 23 is applied onto a foundation film to be etched 22 with a stepped section 21 and flattened and a resist 24 is superposed, a mixed layer 25 is formed on the interface. The upper layer resist 24 is patterned, the whole surface is irradiated with far ultraviolet rays 26 as the mixed layer 25 in an exposed section is left as it is, and a lower layer resist 23 in a section in which there is no upper layer resist 24 is exposed. When the layer 23 is treated with the developer of the lower layer resist 23 into which a liquid having solubility to the upper layer resist 24 is mixed, the mixed layer 25 is also removed, and the pattern of the upper layer resist 24 is transferred to the lower layer resist, thus completing an etching mask for the foundation film 22. According to the method, an excellent resist pattern can be shaped without O2 plasma treatment.

Description

[Detailed Description of the Invention] (Chapter Field of Application) The present invention is directed to the use of PCM (Portable Condenser) in the photolithography process in the semiconductor device manufacturing process.
Formal Maak) The present invention relates to a resist/gutter formation method using multilayer resist growth.

(Prior Art) A conventional resist pattern forming method of this type will be explained with reference to FIG.

First, as shown in FIG. 2 (&), a first resist 13 (PMMA: 5000-300
00λ)t-Apply. Next, apply a second resist 1 on top of that.
4. Specifically, apply a positive resist. At this time, a mixed layer 15 (interlayer) is formed at the interface between the second resist 14 (hereinafter referred to as upper layer resist) and the first resist 13 (hereinafter referred to as lower layer resist).

Next, the upper resist 14 is turned 79 times.

After that, the mixed layer 1 in the exposed part by the patterning is
5 is removed by etching using oxygen plasma as shown in 211(b).

After that, as shown in FIG. 2(a), the entire surface is exposed to deep ultraviolet light 16 (
λ=230 to 270 ntn) to expose portions of the lower resist 13 where the upper resist 14 does not exist. Furthermore, after this exposure, the lower resist 13 is developed and the pattern of the upper resist 14 is transferred to the lower resist 13 as shown in FIG. Complete the formation of a resist/four turns that will serve as an etching mask.

According to this more advanced PCM multilayer resist process, the upper layer resist 14 for pattern formation is the lower layer resist 13.
Because the film thickness becomes uniform with almost no influence from the underlying step portion 11, the controllability of the /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// “Turn line width during formation of fine/#///////////////////” pattern line width is significantly improved. (Problems to be Solved by the Invention) However, the conventional methods described above have the following problems. After patterning the upper layer resist 14 of FIG. 2 (IL), FIG. 2 (C).

While proceeding to the transfer step (d), the mixed layer 15 is removed using oxygen! The use of vacuum technology called 2RM reduces the processing capacity per wafer and expands the equipment space due to having a vacuum system, and as a mass production technology, wafer processing is made into an assembly line. However, there are problems in that the device configuration becomes complicated and workability is significantly reduced.

This invention uses the above-mentioned PCM multilayer resist process, and uses oxygen! , a new nine-layer technology that enables the removal of mixed layers without using 7ZM or additional steps, and also enables the formation of excellent resist/4 turns equivalent to the conventional PCM multilayer resist process. An object of the present invention is to provide a resist pattern forming method using a PCM multilayer resist process.

(Means for Solving the Problems) The present invention provides a PCM multilayer resist process in which a pattern of a second resist (upper layer resist) is transferred to a second resist (lower layer resist). The lower resist layer is developed using a developer solution.

(Function) A mixed layer made of a mixture of both resists exists between the upper resist and the lower resist. Conventionally, this mixed layer has been removed by etching using oxygen glazma after patterning the upper resist layer and before exposing and developing (pattern transfer) the lower resist layer. However, as in the present invention, if the lower resist is developed using a developer mixed with a liquid that is soluble in the upper resist, the developer also has solubility in the mixed layer. Therefore, when the lower resist is developed, the mixed layer on the surface of the lower resist is simultaneously removed. Therefore, there is no need to perform etching removal using oxygen glazma in advance.

(Example) An embodiment of the present invention will be described below with reference to FIG.

First, as shown in FIG. 1 (IL), a second resist 23 (PMMA; 5000~
30,000 people). Next, a second resist 24, specifically an ultraviolet light positive resist, is applied on top of it at a density of 12,000.
Apply about λ. At this time, a mixed layer 25 having a thickness of about 2400 to 2500λ is formed at the interface between the second resist 24 (hereinafter referred to as upper layer resist 5) and the second resist 23 (hereinafter referred to as lower layer resist).

Next, the upper resist 24t is turned.

After that, mix layer 2 of the exposed part due to # buttering.
5, the entire surface is irradiated with deep ultraviolet light 26 (λ depth 230 to 270 nm) as shown in FIG. Furthermore, after this exposure, a lower resist 23 is mixed with a liquid having a solubility in the upper resist 24, such as cellosolve acetate or methyl ethyl ketone.
The cough lower layer resist 23 is developed using this developer.

Then, since the developer has solubility also in the mixed layer 25, as shown in FIG. 1(c), the lower resist 2
Along with the exposed portion of No. 3, a mixed layer 25 exists on top of it.
is also removed, and the pattern of the upper resist 24 is transferred to the lower resist 23. With the above steps, the formation of a resist pattern that will serve as an etching mask for the film to be etched (base film 22) is completed.

In such a method, the ratio of the mixed liquid such as cell solve acetate mixed into the lower resist developer is determined by the molecular weight of the lower resist 23, the molecular weight of the upper resist 24, the solid content, the solvent, the lower resist 23 and the upper resist 24. Heat treatment (gribake) applied after each coating
The optimum value varies depending on the operation sequence during coating of the upper resist 24, the heat treatment (post-bake) performed after the development process when forming the upper resist 24 by turning, etc., and the required grossness. determined.

Generally, as the concentration of the mixed solution in the developer increases, the removal speed of the mixed layer 25 increases, but at the same time, the removal rate of the lower resist layer 25 increases.
The amount of film thinning of the upper resist 24 that occurs during development also increases, and the etching maskability during etching of the base film 22, which is the film to be etched, also decreases. Therefore, the concentration of the mixed solution is determined so that the masking performance does not deteriorate due to the thinning of the upper resist 24, but the mixed layer 25 can be removed efficiently.

(Effect of the invention) As explained in detail above, according to the method of this invention,
Since the mixed layer can be removed at the same time as the first resist (lower resist) is developed, it is possible to use oxygen plasma to remove the mixed layer at the same time as developing the first resist (lower resist). Similar effects can be expected.

Therefore, it is possible to reduce the number of steps and improve workability without impairing the PCM multilayer multilayer resist process point, which enables the formation of excellent resist patterns. Improvements and downsizing of the device are easy, and the configuration of the device becomes significantly easier when mass production is implemented on a line.

[Brief explanation of the drawing]

FIG. 1 is a process cross-sectional view showing an embodiment of the resist/9-turn forming method of the present invention, and FIG. 2 is a process cross-sectional view showing a conventional resist pattern forming method. ... base film, 23... first resist (lower layer resist), 24... second resist (upper layer resist),
25... Mixed layer, 26... Far ultraviolet light.

Claims (1)

[Claims] After applying the first resist on the base and flattening the surface,
In the resist pattern forming method, the pattern of the second resist is transferred to the first resist after applying a second resist and patterning the second resist. A resist pattern forming method characterized in that, during transfer, the first resist is developed using a developer mixed with a liquid that is soluble in the second resist.