JPS63245922A - Mask for x-ray exposure - Google Patents

Abstract

PURPOSE:To obtain an X-ray mask in uniform thickness by plating an absorber pattern, coating a resin and removing one part of the absorber pattern through etching together with the resin by ion beams. CONSTITUTION:An electrode layer 2 is superposed onto a membrane thin-film 1 by the laminating of a CVDBN film and a PIQ film in order of Ti/Au/Mo, and a stencil layer 3 consisting of a PIQ resin is formed. A stencil pattern is shaped through electron beam lithography and RIE. A Ti-electrode protective film is removed through RIE using CF4, and Au is precipitated from an exposed electrode through electroplating. A resin layer 5 is spin-coated, and the surface is flattened. Etching is conducted by oxygen ion beams, ion beam etching is performed by using the mixed gas of O2(20%)+Ar immediately before the appearance of an Su surface, etching is carried out until a thinnest Au surface appears, a flat surface is acquired, and a PIQ protective film 6 is shaped, thus completing the title mask.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an X-ray exposure mask, and more particularly to an X-ray mask with excellent uniformity in the thickness of an absorber pattern.

[Conventional technology]

As one method of forming a mask pattern used for X-ray exposure, a method of forming Au, PT, or the like by plating is known. In this method, on top of the plated electrode layer,
A stencil pattern is formed to serve as a female pattern for plating, and Au and PT are deposited on the exposed electrode portions. However, in electrolytic plating, the deposition rate depends on the pattern density, and the lower the pattern density, the faster the deposition rate. For this reason, the thickness of the plating layer changes depending on the distribution of the pattern, resulting in poor uniformity.The reason for this phenomenon is that the precipitation reaction is rate-determining the supply of Au and pt ions, and the pattern is sparse. This is because ions are sufficiently supplied from the surroundings, the precipitation rate becomes faster, and the thickness becomes thicker.

In addition, in the plating method, since the electrode layer is deposited faithfully to the surface shape of the electrode layer, if the electrode surface has irregularities, the absorber surface also has irregularities, and this also causes the thickness to be non-uniform.

[Problems to be Solved by the Invention] Such non-uniformity in the thickness of the absorber pattern affects the effect of penumbra blur in transfer and deteriorates the dimensional accuracy of the transferred pattern. Therefore, it was necessary to improve the uniformity of the thickness.

An object of the present invention is to provide an X-ray mask with a uniform absorber pattern thickness and a method for manufacturing the same.

[Means for solving problems]

The above purpose is to form an absorber pattern using a plating method.
This can be achieved by etching a portion of the absorber in the thickness direction depending on the thickness.

That is, after forming an absorbent pattern, resin is laminated,
Forms a flat resin surface. Next, the entire surface is etched with an ion beam, keeping the surface flat.
Etching the resin and absorber pattern. This makes it possible to obtain an X-ray mask with a uniform absorber thickness.

[Effect]

The present invention will be explained in detail using FIG. Figure (a) shows an absorber pattern 4 formed by direct current plating of the anchor palm. As shown, the thickness varies depending on the pattern dimensions. Next, as shown in the same figure (b), resin 5 is placed on top of this.
When the resin 5 is spin-coated, the surface becomes flat due to the flow of the resin 5. Subsequently, as shown in FIG. 2C, the entire surface is etched using an ion beam. The amount of etching shall be until the thinnest absorber pattern is exposed. At this time, the type and pressure of the gas are adjusted as described below so that the etching speeds of the resin 5 and the absorber 4 are equal.As the etching speeds are the same, the etching progresses while the flat surface is preserved. A uniform) Mf absorber pattern is obtained. As shown in FIG. 4(d), after removing unnecessary electrode layers, a protective layer 6 is laminated to form an xB mask.

Here, the gas composition and the etching rate of Au and resin in ion beam etching will be described. As the resin, Az resist (manufactured by Hekis I Co., Ltd., trade name) was used.

Figure 2 (a) shows the relationship between the composition ratio of Ar and 02 and the etching rate, and Figure 2 (b) shows the relationship between the composition ratio of Ar and C2 and Fe and the etching rate.The current density of the ion beam is 1 , 5 mA/cllI", and the accelerating voltage is 5
As the concentration of SOZ (00V) increases, the etching rate of the resist increases, and conversely, the etching rate of Au decreases. In the case of a composition of Δr of 80%, 5oz, and 20'%, the etching rates of the two become equal. Also, Cz Fe
Regarding, as the concentration increases, the etching rate of both A u and the resin decreases, and the difference in etching rate also decreases. Therefore, by increasing the concentration of CzFe, the difference in etching rate between the two can be reduced.

In this way, by adjusting the Class A 2 composition of the etching gas in ion beam etching, ΔU and the etching rate of the resin can be made approximately equal.

Note that the method of applying a resin to obtain a flat surface and etching it to achieve flatness is a technique already known as an etch-back method. However, its purpose is mainly to flatten the interlayer insulating layer between wiring patterns. On the other hand, in the present invention, it has been found that after obtaining a flat surface, etching the resin and the pattern at the same time at the same etching rate is effective in making the pattern 75 uniform. Thereby, the uniformity of the thickness of the absorber pattern in the xB mask can be improved, and pattern transfer accuracy can be improved.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained in more detail with reference to FIG. As shown in Figure (a), on a membrane film 1 (thickness: 5 μm) consisting of a l(N film) formed by the CVD method and an IO film laminated by coating, T i / A u
/ M o (film thickness 0.0210.110.02μm
14 layers 2 are stacked in the order of ). Here, the Mo layer is an adhesive layer between the membrane layer and the electrode Au, and the Ti layer is an electrode protective layer when processing the stencil layer 3. Next, a thickness of 1.5μ
A stencil layer 3 made of m PIQ resin is formed. The stencil pattern is formed by a three-layer process using electron beam drawing and reactive ion etching.6 Next, the Ti film of the electrode protection layer is removed by reactive ion etching using CFa gas, and the exposed electrode is exposed to electrolytic etching. A u using plating
4 is precipitated to an average thickness of about 1 μm. At this time, the plating conditions were direct current and current density of 6 mA/cI12. The plating solution is Neutronex 210 (product name: Tanaka Shokukin Co., Ltd.)
was used. As shown in the figure, in DC plating, the plating thickness depends on the pattern dimensions, and as the pattern size decreases, the thickness increases.

Next, as shown in FIG. 5B, a resin layer 5 is further laminated by spin coating. The resin used was photoresist AZ1.
350J (manufactured by Hoechst), and the film thickness is approximately 3 μm. This flattens the surface of the resin.

Subsequently, as shown in FIG. 4(c), the resin 5 and Au4 are simultaneously etched by ion beam etching using 02 gas and a mixture of 02 gas and an inert gas. At the beginning of etching, only 02 gas, which has a high resin etching speed, was used, and just before the Au surface appeared, a mixed gas of 02 gas (20%) and Ar gas was used. By using a mixed gas, the etching speeds of the resin and Au can be matched, so that the etching progresses uniformly and a flat surface can be obtained. Here, etching was performed until the surface of the thinnest Au pattern was etched. The etching conditions at this time were a current density of 60
mA/cm” acceleration voltage is 500V, gas pressure is 5X
10-”P a theal.

Finally, as shown in FIG. 4(d), after removing unnecessary electrode layer 2', 3 μm of PIQ is applied as a protective layer 6 to form an X-ray mask.

As described above, according to this embodiment, even in the case of DC plating, the surface of the absorber is flattened in advance by applying a resin layer, and then both the resin and the absorber pattern are etched at the same speed. The pattern height, that is, the thickness, can be made uniform regardless of pattern dimensions.

Another embodiment of the present invention will be shown using FIG. Figure (a)
As shown in the figure, Au/Mo (film thickness 0.1
The electrode films 2 are stacked in the order of 10.02 pm). continue,
Stencil M made of PIQ resin with JFX thickness of 1.5 μm
form 3. The stencil pattern is made using electron beam drawing and Oz.
It is formed by a three-layer process using reactive ion etching using gas. In this embodiment, since a Ti film serving as an electrode protection film is not used, the underlying electrode Au is sputtered by 02 ions during PIQ etching and adheres to the side wall of the PIQ pattern 2'.

Next, as shown in FIG. 4B, Au4 is deposited by electrolytic plating using Neutronex 210. The plating conditions were a current density of 6 mA/c- and a deposited film thickness of about 1 μm. Also, what about the deposit 2'? I! As a result, the Au on the side wall portion is precipitated in an abnormal manner as shown in FIG. 2(b), and the thickness of the absorber becomes non-uniform within the pattern.

Subsequently, a resist is spin-coated to form a resin layer 5 with a flat surface (FIG. 1(e)).
Similarly, AZ1350J was used, and the film thickness was 3 μm.
Next, the resin is removed by reactive ion etching using 02 gas until just before part of the Au pattern is exposed. Next, Ar gas (10%) and Cz Fe gas (
By ion beam etching using a mixed gas of 90%), the resin and Au are simultaneously etched at almost the same speed, and the abnormally deposited portions of Au are removed while keeping the surface flat (see figure (d)). )).

Finally, as a protective film 6, PIQ was applied to a thickness of 3 μm to form an X-ray mask (FIG. 6(e)).

As described above, according to this embodiment, it is possible to remove abnormal precipitation at the pattern ends caused by the protrusions of the electrodes, so an absorber pattern with a uniform thickness can be formed without using an electrode protective film. It is possible to obtain an X-ray mask having

This sixth embodiment, which shows still another embodiment of the present invention with reference to FIG. 4, relates to the modification of an X-ray mask.

In the case where there is a missing pattern in the part A after manufacturing the xm mask as shown in FIG.

Regarding how to fix this. First, the PIQ layer, which is the protective film of the xa mask, is removed by reactive ion etching using 02 gas, and then resist 7 is deposited on the entire surface with a thickness of approximately 2 μm.
lt cloth. PMMA (polymethyl methacrylate) was used for resist 1-. Subsequently, a desired portion A is irradiated with a focused ion beam using Be and developed to obtain a stencil pattern 7' for plating with a PMMA resist (FIG. 4(b)).

The irradiation conditions were an acceleration voltage of 300 k e V and a dose of 8.
Development conditions were 2 minutes using a mixed solution of methyl isobutyl ketone and isopropyl alcohol.

Next, A u 4 ′ was newly deposited as an absorber pattern on the exposed electrode portion by electrolytic plating (FIG. 4(C)). Here, the plating solution is Neutronex 210
The current density was set to approximately 6 mA/cm". In the case of such mask correction, it is difficult to accurately determine the area of the mask because the number and area of the repaired parts differ depending on the case. For this reason, the current density It is difficult to precisely control the density, and it is difficult to control the plating film thickness.Therefore, as shown in Figure (c), it is precipitated thickly.
Etching is performed in the next step to match the thickness of the absorber layer with the original thickness. PMMA used as stencil layer after plating
7' is removed with acetone, and then a resin layer 5 is applied to form a flat surface. AZ1350J was used as the resin. Thereafter, the resin layer 5 and the newly deposited Au pattern 4' are simultaneously etched by ion beam etching using a mixture of O2 gas and Ar gas to match the thickness of the initial absorber 4 (FIG. 4(e)).

Here, the reason why AZ1350J was used instead of PMMMA as the flattening resin layer is that PMMA has a fast etching rate and it is difficult to etch it at the same rate as Au.

As described above, according to this embodiment, the thickness can be made uniform even in the absorber pattern in which defects have been corrected.

〔Effect of the invention〕

According to the present invention, since the thickness of the absorber pattern can be made uniform, an X-ray mask with excellent transfer accuracy can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the operation of the present invention and a first embodiment, FIG. 2 is a diagram showing the relationship between gas composition and etching rate, and FIG. 3 is a process diagram showing a second embodiment. Figure 4 is the third
It is a process diagram showing an example of. DESCRIPTION OF SYMBOLS 1... Membrane film, 2... Electrode layer, 3... Stencil layer, 4... Absorber pattern, 5... Resin layer,
6...Protective film.

Claims (1)

[Claims] 1. In an X-ray exposure mask in which an X-ray absorber pattern is formed by a plating method, after plating the absorber pattern, a resin is applied, and then an ion beam is used to form the absorber pattern together with the resin. An X-ray exposure mask characterized by etching a part of. 2. The X-ray exposure mask according to claim 1, wherein the absorber pattern is made of Au or Pt formed by plating, or an alloy containing these.