JPH11135399A - Manufacturing method for x-ray mask and the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a controlling performance and line width uniformity of an EB(electronic beam) drawing pattern line width, when an X-ray mask is made in a back etching preceding process. SOLUTION: A PEB(post-exposure bake) processing of a post-exposure resist 29 is performed by making a pattern surface of an X-lay mask 13 to have a hot plate 11 approach a heating surface 11A which is faced downward from the lower side. Many holes are provided through the hot plate and remaining of fluid, solvent and so on is pretend. A temperature controlling performance and uniformity of resist PEB processing after EB exposure, which is applied on the X-lay mask 13 having a complex structure and large thermal capacity can be improved, and as a result an X-ray mask pattern having a high line width controlling performance and uniformity can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for manufacturing an X-ray mask, and more particularly to a resist for forming an X-ray absorber pattern on an X-ray mask, which is mainly used in X-ray lithography in a semiconductor device manufacturing process. A method and apparatus for heat-treating

[0002]

2. Description of the Related Art In equal-magnification X-ray lithography, an X-ray mask having a transfer pattern on a wafer and an equal-magnification pattern is brought close to the wafer with a gap of about 10 to 30 μm, and soft X-rays having a wavelength of about 1 nm are converted to X-rays. This is a technique of irradiating a wafer through a mask and transferring a fine pattern on an X-ray mask to a resist on the wafer.

FIGS. 3A and 3B show the structure of a general X-ray mask, wherein FIG. 3A is a plan view and FIG. 3B is a sectional view. The X-ray mask includes an X-ray transparent thin film (membrane) 21 that transmits soft X-rays, an X-ray absorber pattern 23 formed thereon for absorbing soft X-rays, and a silicon frame 25 that holds the membrane 21. And a support frame 27. In a general X-ray mask, the thickness of the membrane 21 is 1 to 2 μm, and the thickness of the silicon frame 25 is 0.5 to
The thickness of the support frame 27 is 2 to 8 mm, and the thickness of the entire X-ray mask is about 8 mm.

The X-ray absorber pattern 23 is usually formed by forming a resist pattern on the X-ray absorber thin film using an electron beam (EB) drawing apparatus, and etching the X-ray absorber thin film using the resist pattern as a mask. Formed. Since EB writing requires a long time for exposure, a chemically amplified resist having high exposure sensitivity is generally used as a resist. Chemically amplified resist is subjected to heat treatment after exposure,
A crosslinking reaction or a dissociation reaction of the resin proceeds in the resist using the acid generated by the exposure as a catalyst. In the subsequent development processing, only the portion irradiated with X-rays remains or dissolves in the developer, and a resist pattern having a desired shape is formed.

The heat treatment after exposure is generally performed by PEB (Post E
xposure Bake). FIG. 4 shows a state of PEB processing for processing a wafer. Since the crosslinking reaction and dissociation reaction of the resin in the resist are very sensitive to the temperature, it is necessary to control the PEB temperature with high precision in order to reduce the variation in the line width of the resist pattern. In the PEB process during the wafer process, the pattern surface 3
The wafer 31 with 1A facing upward is subjected to PEB processing by bringing the heating surface 33A close to the hot plate 33 with upward facing with a gap of several tens of μm. Here, the reason why the wafer 31 is not brought into contact with the hot plate 33 is to prevent generation and adhesion of particles due to the contact.

Normally, a shielding plate 35 for suppressing heat dissipation is arranged above the hot plate 33, and the gap between them is narrow.
The controllability and uniformity of temperature in the space between 5 are improved. In addition, the shielding plate 35 usually has a large number of holes 35A.
Are formed. This is to prevent the solvent and moisture evaporated from the resist from staying between the wafer 31 and the shielding plate 35.

There are two types of X-ray mask manufacturing processes: a pattern formation precedent process and a back etch precedent process. In the pattern formation preceding process, after forming the X-ray absorber pattern, the silicon under the pattern region is removed by etching to form a membrane. This process is shown in FIGS. 5A to 5F in the order of steps. As shown in the drawing, the process includes an X-ray transparent thin film forming step (a),
X-ray absorber thin film forming step (b), EB drawing configuration (c), X
It comprises a line absorber etching step (d), a back etch step (e), and a frame bonding step (f).

During the back-etching step (e) for removing silicon by etching, positional distortion occurs in the pattern due to the stress of the membrane and the X-ray absorber pattern. Also,
Also in the step (f) of bonding the support frame, the X-ray mask substrate is deformed to cause positional distortion.

FIG. 6 similarly shows the back etch precedent process in sequence. The difference from FIG. 5 is that the back etch step (c) in which positional distortion occurs and the frame bonding step (d) are performed before the EB drawing step (e).
Therefore, in the back etch precedent process, positional distortion is significantly reduced as compared with the pattern formation precedent process, and it is considered that the back etch precedent process will become the mainstream of the future X-ray mask manufacturing process.

[0010]

In a manufacturing process of an X-ray mask using a back etch precedent process, if PEB processing after EB drawing is performed on a conventional hot plate used in a general wafer process, X Since the thickness of the line mask is as large as about ten times the thickness of the wafer, a gap of about several mm is generated between the membrane 21 and the hot plate 33. This situation is shown in FIG. Because of this gap, heat conductivity from the hot plate 33 to the resist is deteriorated, and since the heat capacity of the silicon frame 25 and the support frame 27 is large, the temperature rise rate between the center and the periphery of the membrane 21 is reduced. In contrast, there was a problem that the controllability and uniformity of the PEB temperature were poor.

Here, it is conceivable to improve the controllability and uniformity of the temperature by providing irregularities on the surface of the hot plate 33 in accordance with the irregularities of the X-ray mask 13. This is shown in FIG. However, if this configuration is adopted, another hot plate is required for X-ray masks having different window sizes, and there is a problem that the cost is increased. Alternatively, if the X-ray mask 13 is turned upside down and PEB processing is performed, in the subsequent development processing, the X-ray mask reversal processing in which the pattern surface is turned up is necessary, and For example, the production cost of an automatic developing apparatus increases, such as the necessity of an apparatus.

In view of the above, the present invention provides a method for controlling a pattern line width by heating a resist applied on a thin film with good controllability and uniformity during PEB processing after EB drawing of an X-ray mask in a back etch precedent process. It is an object of the present invention to provide a method and an apparatus for manufacturing an X-ray mask capable of improving the properties and uniformity.

[0013]

In order to achieve the above object, a method of manufacturing an X-ray mask according to the present invention comprises applying a resist on an X-ray absorber thin film grown on a substrate, and applying a predetermined resist to the resist. In the method of manufacturing an X-ray mask for drawing a pattern, performing baking after drawing and then performing patterning, and patterning the X-ray absorber thin film using the patterned resist as a mask, heating the hot plate for performing the baking after drawing It is characterized in that the surface faces downward.

Further, the apparatus for manufacturing an X-ray mask of the present invention comprises:
A film forming apparatus for forming an X-ray absorber thin film on a substrate;
A resist coating device for applying a resist on the X-ray absorber thin film, a drawing device for writing a predetermined pattern on the resist on the X-ray absorber thin film, and a hot plate for heating after writing the resist on which the predetermined pattern is drawn An X-ray mask manufacturing apparatus, comprising: a developing device for patterning the resist heated after drawing, and a patterning device for patterning the X-ray absorber thin film using the patterned resist as a mask. Characterized in that the heating surface is disposed downward.

According to the above configuration, the distance between the heating surface of the hot plate and the pattern surface of the X-ray mask can be reduced without providing unevenness on the heating surface of the hot plate, and the controllability and uniformity of temperature can be improved. improves. In this case, it is not necessary to invert the X-ray mask for the developing process.

The hot plate of the present invention or used in the present invention preferably has a through-hole formed on a heating surface thereof. In this case, the possibility that moisture or solvent evaporated from the resist stays between the X-ray mask and the hot plate is eliminated.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on embodiments of the present invention with reference to the drawings. FIG.
FIG. 1 is a schematic cross-sectional view illustrating a configuration of a PEB processing apparatus used in an X-ray mask manufacturing apparatus according to an embodiment of the present invention. This PEB processing apparatus is composed of a hot plate 11 and a shielding plate 35, with the heating surface 11 A of the hot plate 11 facing downward, and the membrane 21 of the X-ray mask 13.
This is heated in a state of facing upward. The X-ray mask includes a membrane 21, a silicon frame 25 and a support frame 27, and a resist after exposure (not shown) is formed on the upper surface of the membrane 21.

By setting the heating surface 11A of the hot plate 11 downward, regardless of the structure of the X-ray mask 13, the gap between the pattern surface of the membrane 21 of the X-ray mask 13 and the heating surface 11A is several tens μm. Temperature, so that the temperature of the PEB treatment can be controlled with high controllability and uniformity. Also, PEB
Although a small amount of the volatile component evaporates during the treatment, a small hole may be formed in the hot plate 11 as necessary to prevent the evaporated component from staying.

The method of manufacturing an X-ray mask according to the present invention is performed according to the same steps as those of the conventional method of manufacturing an X-ray mask described with reference to FIG. First, the X-ray transparent thin film 21 is grown on the entire surface of the silicon frame 25 (FIG. 6).
(A)), an X-ray absorbing thin film is grown on the main surface of the X-ray transmitting thin film 21 (FIG. 2 (b)). Subsequently, back etching is performed from the back surface of the X-ray mask, and the silicon frame 25 in the region used for transmitting X-rays and the X-ray transparent thin film 21 on the back surface are removed (FIG. 3C). Next, a support frame 27 for supporting the X-ray mask is attached to the periphery of the X-ray mask (FIG. 4D). While holding the X-ray mask at a predetermined position using the support frame 27, a resist 29 is applied by spin coating or the like, and then EB lithography is performed by an electronic lithography apparatus (FIG. 9E). The resist is heated using a PEB processing apparatus, and after patterning is performed, the X-ray absorber is etched using the resist as a mask (FIG. 1F).

FIG. 2 shows an example of an automatic resist coating / developing apparatus used in an X-ray producing apparatus for carrying out the above X-ray producing method. The development processing device 40 includes two resist coating units 4 that are selectively used depending on the type of resist.
1 and 42, two developing units 43 and 44 which can be used similarly, two normal hot plates 45 and 46, and a hot plate 47 exclusively for PEB.
And the cooling plate 48 are connected to the passage 5 of the transfer robot 49.
They are arranged facing each other with a 0 therebetween. The transfer robot 49 takes out, for example, about 10 X-ray masks 13 stored in each of the large number of X-ray mask carriers 51 from the corresponding dedicated carrier 51, and sequentially loads them into the necessary units 41 to 48, And take it out from there.

In general, a chemically amplified resist has poor stability after exposure, and when left in the air after exposure, a small amount of ammonia in the air adheres to the resist surface to inactivate the acid generated by the exposure. I do. Therefore, the entire automatic resist coating and developing apparatus 40 is covered with a hood, and the inside thereof is kept in a clean atmosphere using a chemical filter.

The X-ray mask 13 having the resist applied to the X-ray absorber thin film by the resist unit 41 or 42 is sent to an EB exposure device (not shown) arranged outside the processing apparatus 40, where the EB exposure is performed. receive. After the EB exposure, the X-ray mask 13 returns to the processing apparatus 40 again, and is conveyed to the PEB hot plate 47 of the automatic resist coating / developing apparatus 40 by the X-ray mask dedicated carrier 49. The hot plate 47 has a heating surface facing downward, and the temperature and its in-plane uniformity are controlled with high accuracy. X
The pattern surface of the line mask 13 is placed at a position of several tens μm from the heating surface of the hot plate 47 and is held for a certain time.
Next, the X-ray mask 13 is conveyed to the adjacent cooling plate 48, placed at a position of several tens μm from the cooling surface of the cooling plate 48, and held for a certain time. By keeping the heating and cooling times constant in this way, PEB processing can be performed with good reproducibility.

Next, the developer is dropped on the pattern surface of the X-ray mask 13 transported to the developing unit 43 or 44, and the resist pattern is developed. After that, the pattern surface is washed with pure water, and the conventional hot plate 4
It is sent to 1 or 42 to perform a drying process. Through this series of processes, the crosslinking or dissociation reaction of the resist proceeds with high accuracy and good reproducibility, and a resist pattern having a line width as designed can be formed. The X-ray absorber is etched using the obtained resist pattern as a mask to complete the X-ray mask.

As described above, the present invention has been described based on the preferred embodiments. However, the method and apparatus for heat-treating a resist according to the present invention are not limited only to the configuration of the above-described embodiment. Various modifications and changes from the configuration of the example are also included in the scope of the present invention.

[0025]

According to the method and apparatus for manufacturing an X-ray mask of the present invention, a resist pattern used as a mask for an X-ray absorber thin film is formed on an X-ray mask having a complicated structure and a large heat capacity by controlling the temperature of the resist pattern. Since PEB processing can be performed with high uniformity, an X-ray mask pattern with high controllability of line width and high uniformity can be formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a PEB processing apparatus in an X-ray mask manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic plan view illustrating a configuration of an automatic resist coating and developing apparatus in the apparatus for manufacturing an X-ray mask according to the present invention.

FIGS. 3A and 3B are a plan view and a cross-sectional view, respectively, showing the structure of a general X-ray mask.

FIG. 4 is a schematic sectional view of a general baking hot plate.

FIGS. 5A to 5F are cross-sectional views of an X-ray mask in each process step of a pattern formation precedent process.

FIGS. 6A to 6F are cross-sectional views of an X-ray mask in each process step of a back etch precedent process.

FIG. 7 is a cross-sectional view showing an example of an X-ray mask and a baking hot plate.

FIG. 8 is a sectional view showing another example of an X-ray mask and a baking hot plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... PEB processing apparatus 11 ... Hot plate 13 ... X-ray mask 15 ... Shielding plate 21 ... Membrane 23 ... X-ray absorber thin film 25 ... Silicon frame 27 ... Support frame 29 ... Resist 40 ... Automatic resist coating and developing processing apparatus 41, 43 ... Resist coating units 45, 47 ... Developing units 49, 51 ... Hot plate 53 ... Hot plate dedicated to PEB 55 ... Cooling plate

Claims (4)

[Claims] 1. A resist is applied on an X-ray absorber thin film grown on a substrate, a predetermined pattern is drawn on the resist, a pattern is baked after drawing, patterning is performed, and the patterned resist is masked. A method of manufacturing an X-ray mask for patterning an X-ray absorber thin film, wherein a heating surface of a hot plate for performing baking after drawing is directed downward. 2. The method for manufacturing an X-ray mask according to claim 1, wherein a through hole is formed in a heating surface of said hot plate. 3. A film forming apparatus for forming an X-ray absorber thin film on a substrate, a resist coating apparatus for applying a resist on the X-ray absorber thin film, and a resist coating apparatus for applying a resist on the X-ray absorber thin film. A drawing device for drawing a pattern, a hot plate for drawing and heating a resist on which a predetermined pattern is drawn, a developing device for patterning the heated resist after drawing, and the X using the patterned resist as a mask. An apparatus for manufacturing an X-ray mask, comprising: a patterning device for patterning a line absorber thin film, wherein the heating surface of the hot plate is arranged downward. 4. The apparatus according to claim 3, wherein a through hole is formed in the heating surface.