JPH0817716A - Manufacture of reflection-type mask - Google Patents

Abstract

PURPOSE:To work an X-ray absorber layer into a pattern without damaging a multilayer film by a method wherein a resist pattern is formed on the surface of an X-ray reflection layer and the X-ray absorber layer is formed by using the resist pattern as a mold. CONSTITUTION:A multilayer X-ray reflection layer 2 is formed on an Si wafer 1 as a mask substrate. Then, a resist layer 4 is formed on the surface of the multilayer X-ray reflection layer 2. Then, the resist layer 4 is worked into a pattern. Then, an X-ray absorber layer 3 is formed, by an electrolytic plating method, on pattern grooves 4b which are formed by a resist pattern 4a. A mask which has been used in the electrolytic plating method is cleaned by pure water, it is dried, the resist layer 4 is then removed, and a reflection-type mask is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a reflection type X-ray mask used for X-ray projection exposure.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for miniaturization of semiconductor integrated circuit devices in order to realize high integration and high performance of semiconductor integrated circuits. X using an X-ray having a much shorter wavelength
Line reduction projection lithography has been proposed. X-ray lithography using this X-ray has an advantage that a mask pattern can be projected onto a wafer with high resolution. As a mask used for such X-ray lithography, a transmission type mask and a reflection type mask can be mentioned.

The former transmissive mask is a self-supporting film (membrane) having a thickness of 1 μm or less and made of a substance that easily transmits X-rays.
A thin film made of a substance that hardly absorbs X-rays is adhered and formed thereon, and a desired pattern is formed on this thin film. Therefore, since the incident light is absorbed in a desired pattern, only the light transmitted through the portion where the thin film is not formed is imaged on the wafer.

Further, in the latter reflection type mask, an X-ray reflection multilayer film for reflecting X-rays is formed on a mask substrate, and the interference effect of light reflected at a large number of interfaces is utilized to make a reflection portion and a non-reflection portion. And a pattern is formed by the difference in reflectance between the X-ray absorbing layer and the X-ray absorbing layer, and the X-ray absorbing layer is provided on the multilayer X-ray reflecting layer.
The thing which pattern-processes this etc. is mentioned.

However, the former transmissive mask has a very weak membrane strength, which makes it difficult to manufacture a mask having a large area, and when the X-ray is irradiated, the patterned thin film becomes X-shaped. Since the wire is absorbed, there is a problem that the membrane is easily deformed by the heat generated at this time.

On the other hand, in the latter reflection type mask, since the pattern is formed on a thick substrate, not only the influence of heat generated when absorbing X-rays is mitigated, but also cooling such as water cooling is performed from the back surface. It is also possible to do so. Further, since it is possible to manufacture a mask having a large area, the performance is better than that of the above-mentioned transmission type mask. Therefore, a reflective mask is generally used rather than a transmissive mask.

FIG. 5 shows a schematic block diagram of such a reflective mask. FIG. 5A is a schematic configuration diagram of a reflective mask obtained by patterning the X-ray reflective multilayer film 52a provided on the mask substrate 51a, and FIG. 5B is a schematic configuration diagram on the mask substrate 51b. After providing the X-ray reflective multilayer film 52b, the X-ray absorber layer 53b further formed on the X-ray reflective multilayer film 52b.
It is a schematic block diagram of the reflective mask obtained by patterning.

The multi-layer X-ray reflection layer (hereinafter referred to as a multi-layer film) formed on the surface of the mask substrate has two kinds of materials having greatly different refractive indexes, that is, a material containing a heavy element as a main component and a light material. It has a structure in which a substance containing an element as a main component is alternately laminated in a thickness of several nm.

This multilayer film utilizes the interference effect of light reflected at a large number of interfaces. One cycle length (cycle length) of the multilayer film is d, the X-ray incident angle is θ, and the X-ray wavelength is. When λ is λ, a high reflectance is provided if the following expression (1) (Bragg's conditional expression) is satisfied. 2d sin θ = nλ (where n is a positive integer) ... (1) Expression

[0010]

However, since the mask used for X-ray lithography has a fine pattern, defects are likely to occur. Generally, several tens of mask patterns are sequentially printed on the wafer by the time the semiconductor integrated circuit is completed, and if even one of them has a defect in the mask, the obtained semiconductor integrated circuits become all defective products.
The yield of semiconductor integrated circuits is significantly reduced, leading to a huge loss.

However, in reality, it is quite difficult to manufacture a defect-free mask, so it is important to perform defect inspection of the manufactured mask and correct the found defects to obtain a high-quality mask. It has become a challenge.

The repair (repair) of the found defect can theoretically be performed by changing the defective portion to a non-reflective portion if it is a reflective portion, and conversely, if the defective portion is a non-reflective portion. If there is any, it can be performed by changing it to a reflection part, but actually, for example, in the case of a reflection type mask obtained by patterning a multilayer film as shown in FIG. Is difficult to change into a reflection part.

In a reflective mask obtained by patterning a multilayer film, a part of the multilayer film is removed by a laser beam such as a focused ion beam (FIB) in order to change the reflective portion to the non-reflective portion. It is good, but in order to change the non-reflective part to the reflective part, the reflective pattern is composed of multiple layers of thin layers over a small area. Must be accurately formed, which is quite difficult.

Therefore, it is preferable to use a reflection type mask obtained by forming an X-ray absorber layer on a multilayer film as shown in FIG. 5B and patterning the X-ray absorber layer. ing. In the case of this reflective mask, the reflective pattern is X
Since it is made of a line absorber, a part of the multilayer film can be removed by a laser beam such as a focus ion beam (FIB) to change the non-reflecting part to the reflecting part. Moreover, the reflecting part can be changed to the non-reflecting part. Since it is sufficient to attach the X-ray absorber to a part of the surface of the multilayer film by laser chemical vapor deposition (CVD) or the like, it is more practical than the reflective mask obtained by patterning the multilayer film described above. .

Here, FIG. 6 shows a manufacturing process of a reflective mask having a structure in which the X-ray absorber layer is patterned. Figure 6
6A to 6F, a multilayer film 62, an X-ray absorber layer 63, and a resist layer 64 are formed on the mask substrate 61 in this order from the mask substrate 61 side, and then pattern exposure is performed. After being transferred to the X-ray absorber layer 63, the resist layer 64
2 shows the step of forming a mask pattern by removing.

First, on the mask substrate 61, two kinds of substances having greatly different refractive indexes, that is, a substance containing a heavy element as a main component and a substance containing a light element as a main component are alternately formed with a thickness of several nm. A multilayer film 42 having a laminated structure is formed (FIG. 6).
(A)). Mask substrate 61 on which the multilayer film 42 is formed
An X-ray absorber layer 63 is formed on top (FIG. 6B), and X
A resist layer 64 is formed on the line absorber layer 63 (FIG. 6C).

After forming the resist layer 64, pattern exposure and development are performed to form a resist pattern 64a (FIG. 6 (d)). The resist pattern 64a is transferred to the X-ray absorber layer 63 by an ion milling method or an RIE (reactive ion etching) method (see FIG. 6).
(E)), the resist layer 64 is removed (FIG.6 (f)).

However, the reflection type mask obtained by such a method is an ion milling method or an R milling method when the X-ray absorber layer is processed into a predetermined pattern shape.
If the processing is performed using the IE method, the surface of the multilayer film will also be etched. Therefore, the surface roughness of the multilayer film increases, and the X-ray reflectance of the mask multilayer film decreases. Further, even when the ion milling method is used, the multilayer structure is destroyed by ion mixing, which causes a problem that the X-ray reflectance of the multilayer film of the mask is lowered.

The decrease in the reflectance of the mask causes a further problem that the X-ray projection exposure apparatus lengthens the X-ray irradiation time required to obtain a desired exposure amount, thereby decreasing the throughput.

The present invention has been made in view of the above problems, and when manufacturing a reflective mask having an X-ray absorber layer on the surface of a multilayer film, without damaging the multilayer film,
It is an object to provide a method for patterning an X-ray absorber layer. It is another object of the present invention to provide a method for manufacturing a reflective mask that has a simple manufacturing process and improved throughput.

[0021]

In order to achieve the above object,
According to a first aspect of the present invention, when a reflective mask for X-ray projection exposure is manufactured by forming an X-ray absorbing layer having a predetermined pattern on the surface of the X-ray reflecting layer, A resist pattern forming step of forming a patterned resist layer on the surface; an X-ray absorbing layer forming step of forming an X-ray absorbing layer on the surface of the X-ray reflecting layer exposed from the pattern of the resist layer; A method of manufacturing a reflective mask is proposed, which includes a resist removal step of removing the resist layer after the step of forming a line absorption layer.

According to the invention of claim 2, in the invention of claim 1, in the step of forming the X-ray absorbing layer, the surface of the X-ray reflecting layer exposed from the pattern of the resist layer is plated with the X-ray absorbing layer. A method of manufacturing a reflection-type mask that is formed by deposition by the method is proposed.

Further, the invention according to claim 3 is the invention according to claim 2, wherein a multilayer film X-ray reflecting layer is used as the X-ray reflecting layer, and the uppermost layer of the multilayer film X-ray reflecting layer is used as a plating electrode for electrolytic plating. It proposes a method of manufacturing a reflective mask in which the X-ray absorbing layer is formed by a method.

According to a fourth aspect of the present invention, in the second aspect of the invention, a multilayer film X-ray reflecting layer is used as the X-ray reflecting layer, and the uppermost layer of the multilayer film X-ray reflecting layer is a plating reaction initiation catalyst layer. As a method, a method of manufacturing a reflection type mask in which the X-ray absorbing layer is deposited by electroless plating is proposed.

Further, the invention according to claim 5 is, in the invention of claim 3, a reflection type in which, prior to the step of forming the X-ray absorbing layer, a conductive treatment step of making the surface of the X-ray reflecting layer conductive is performed. A mask manufacturing method is proposed.

The invention according to claim 6 is the reflection type according to the invention of claim 4, wherein a catalyzing process step for catalyzing the surface of the X-ray reflecting layer is performed before the X-ray absorbing layer forming step. A mask manufacturing method is proposed.

[0027]

Since the invention according to the present application is configured as described above, it has the following effects. First, in claim 1, in a method of manufacturing a reflective mask in which an X-ray absorbing layer having a desired pattern is formed on the surface of an X-ray reflecting layer, a resist for forming a patterned resist layer on the surface of the X-ray reflecting layer. A pattern forming step, and forming an X-ray absorbing layer on the surface of the X-ray reflecting layer exposed from the pattern of the resist layer X
It is proposed that the method has a line absorbing layer forming step and a resist removing step of removing the resist layer after the X-ray absorbing layer forming step.

That is, in the present invention, the patterning process of the X-ray absorber layer is different from the conventional one, and a resist pattern is provided on the surface of the X-ray reflecting layer, and this resist pattern is used as a template for X-ray etching.
Since the X-ray absorber layer is formed, the X-ray absorber layer can be patterned without damaging the surface of the X-ray reflection layer.

That is, according to the method of the present invention, the X-ray absorber layer can be patterned by the additive method, and a highly accurate reflective mask can be obtained by a simple manufacturing process. Further, since the line width of the pattern provided on the mask can be adjusted by the resist pattern, it is possible to sufficiently deal with a fine pattern used for X-ray projection exposure.

Furthermore, in the case of repairing (repairing) when there is a defect in the obtained mask pattern, when changing the non-reflecting portion to the reflecting portion (removing the X-ray absorber layer), a laser beam such as an ion beam is used. The unnecessary part of the X-ray absorber should be deleted, and when changing the reflection part to the non-reflection part (forming the X-ray absorber layer), the X-ray absorber layer should be added again to the part to be added. A X-ray absorber layer may be formed by forming a resist pattern and using this as a template. Therefore, the process for repair is simple and the workability is good, and the manufacturing efficiency (of the reflective mask) is good.

Further, since the pattern of the resist layer is obtained by exposure by projection exposure or the like, the X-ray reflection layer is not destroyed during the patterning of the resist. Further, since the resist layer is dissolved and removed when the resist layer is removed, there is no fear of destroying the X-ray absorber layer as well as the X-ray absorber layer. An ashing method may be used as such a resist removing method. Therefore, the reflective mask obtained by the method of the present invention has a surface with no roughness and a good reflectance.

The resist is a polymer thin film which is altered by radiation. As the resist to be used, a negative type resist for forming a resist pattern by making a portion irradiated with radiation insoluble in a developing solution, and a radiation A positive type resist that forms a resist pattern by insolubilizing a portion which is not irradiated with a developer in a developing solution can be used, but either resist may be used in the present invention.

This is because, regardless of whether a negative resist is used or a positive resist is used,
This is because it may be designed so that the region that finally dissolves in the solvent becomes the non-reflective layer in the mask pattern.

Furthermore, since the mask obtained by the method of the present invention does not cause a decrease in reflectance, when the mask is used for exposure, the amount of the reflected light flux imaged on the wafer is produced by the conventional manufacturing method. The number of masks can be increased more than that of the masks described above, and thus the exposure time can be shortened. In other words, the irradiation time required to obtain the dose amount required for one exposure is shortened, and the life of the mask is extended.

On the contrary, the irradiation time is set to the same level as the conventional one,
Even if the light source to be used is a light source having a lower brightness than the conventional one, the same effect as the conventional one can be exhibited, so that the cost can be kept low by this configuration. From the above, by using the mask obtained by the method of the present invention, it is possible to improve the throughput of the exposure apparatus as a whole.

Further, the invention of claim 2 is the method for manufacturing a reflective mask according to claim 1, wherein in the step of forming the X-ray absorbing layer, X-rays are exposed on the surface of the X-ray reflecting layer exposed from the pattern of the resist layer. A method for manufacturing a reflective mask in which an absorption layer is formed by plating is proposed. That is, claim 2
Proposes a method of manufacturing a reflection type mask to which an additive method, which is a method of adding a necessary portion by a plating method, is applied.

Generally, when the mask pattern is miniaturized,
Since the etching mask for forming the mask pattern is also miniaturized, the number of steps for manufacturing the mask (particularly at the time of patterning the X-ray absorber layer) is also increased, but the present invention uses the plating method. Therefore, the number of manufacturing steps can be reduced.

In particular, even when forming a fine pattern, the patterning of the mask can be performed by almost one plating process. Therefore, as compared with the conventional method, two to three steps,
When there are many processes, the number of processes can be reduced by four or more.
Therefore, the cost required for each process can be reduced. Of course, the cost of the apparatus used is lower than that of the dry process which requires the use of a vacuum apparatus.

Further, when the pattern is formed by the plating method, the line width of the desired pattern is highly accurate and almost conforms to the resist pattern. Can be adjusted to.

Further, unlike the ion milling method or the reactive ion etching method, there is no troublesome work such as having to put the mask in and out of the vacuum container, and therefore the working efficiency can be improved, so that the reflection It is possible to improve the throughput (processing capacity) in manufacturing the mold mask.

Further, since the reflective mask obtained by the present invention has a good pattern rectangularity, the range of dose amount which is an index for obtaining an exposure pattern with good contrast is wide,
Because it is easy to optimize, the product yield rate improves. Also,
By using the plating method, it is easy to manufacture a large area pattern, and low cost and mass production are facilitated.

Further, in the invention of claim 3, in the method of manufacturing a reflective mask according to claim 2, a multilayer film X-ray reflective layer is used as the X-ray reflective layer, and the uppermost layer of the multilayer film X-ray reflective layer is plated. A method has been proposed in which the X-ray absorbing layer is formed as an electrode by an electrolytic plating method.

That is, in the present invention, the X-ray reflection layer is formed of a multilayer film. The X-ray reflection layer determines the reflection characteristics of the X-ray reflection layer based on the difference in the refractive index of the individual constituent films forming the multilayer film (that is, due to the coherence). Freely select
The X-ray reflective layer having a desired reflectance can be easily obtained.

The multilayer X-ray reflection layer used in the present invention is preferably composed of two types of substances having greatly different refractive indexes, in other words, a substance containing a heavy element as a main component and a light element as a main component. It is preferable to use a material obtained by alternately stacking a substance having a thickness of several nm on a mask substrate to form a multilayer film.

Further, in the present invention, since the uppermost layer of this multilayer film is used as the electrode for plating, it is preferable to form the multilayer X-ray reflection layer so that a substance having good conductivity becomes the uppermost layer. The conductive substance is not particularly limited, but for example, Ag, Au, Co, Cu, Fe, Ir, M
Examples include o, Ni, NiCr, Pd, Pt, Sn, W, Zn and the like. Of course, a non-conductive substance may be formed as the uppermost layer, and in this case, the surface may be subjected to a conductive treatment.

In the present invention, the X-ray absorbing layer is formed by the electrolytic plating method using the cathode of the uppermost layer of the multilayer X-ray reflecting layer thus constructed. In this electrolytic plating method, the uppermost layer is a cathode, and the substance to be plated is added to the reaction system as metal ions in a metal salt aqueous solution, and a voltage is applied (electricity is applied) to reduce the metal ions by an electrolysis reaction, and It is a method of depositing a metal on the surface of the uppermost layer of the multilayer X-ray reflection layer. As the anode, the same kind of material can be used as a metal ion supplement source for plating, and an insoluble material such as carbon or platinum can also be used.

Since the uppermost layer of the multilayer X-ray reflection layer is exposed in a pattern conforming to the resist pattern, the absorber layer obtained by deposition also conforms to the resist pattern. become. (For example, when the resist pattern is negative, the resulting absorber layer pattern is positive.)

Further, the resist functioning as a mask is
It can be easily dissolved by a solvent or can be easily removed by using an ashing method. This solvent does not damage the X-ray absorbing layer and the multilayer film which is particularly difficult to repair. It is possible to always obtain a reflective mask having good performance without lowering the reflectance of the mask.

In this way, since the X-ray absorbing layer is deposited by the electrolytic plating method, it is possible to obtain a reflection type mask having a good transfer efficiency with good efficiency by a simple operation.
Furthermore, the manufacturing efficiency is improved because fewer manufacturing steps are required as compared with the conventional method, and it is roughly 20% in terms of time (of course, since it depends on the material of the mask and the conventional method for comparison, it can be generally said. However, on average, it can be shortened to improve productivity.

Further, since the electroplating method is used, when a defective product is produced, the repair of the defective portion can be easily carried out regardless of whether it is a reflective portion or a non-reflective portion, so that the product yield is also improved. It is possible to

Further, in the invention of claim 4, in the method of manufacturing the reflective mask according to claim 2, a multilayer film X-ray reflective layer is used as the X-ray reflective layer, and the uppermost layer of the multilayer film X-ray reflective layer is plated. As a reaction initiation catalyst layer, a method of depositing and forming the X-ray absorbing layer by electroless plating has been proposed.

That is, in the present invention, the X-ray reflection layer is formed of a multilayer film. The X-ray reflection layer determines the reflection characteristics of the X-ray reflection layer based on the difference in the refractive index of the individual constituent films forming the multilayer film (that is, due to the coherence). Freely select
The X-ray reflective layer having a desired reflectance can be easily obtained.

Here, the multilayer X-ray reflection layer used in the present invention is preferably composed of two kinds of substances having greatly different refractive indexes, in other words, a substance containing a heavy element as a main component and a light element as a main component. It is preferable to use a material obtained by alternately stacking a substance having a thickness of several nm on a mask substrate to form a multilayer film.

Further, in the present invention, since the uppermost layer of the multilayer film is used as the plating reaction initiation catalyst, it is preferable to form the multilayer X-ray reflection layer so that the substance having the catalytic function becomes the uppermost layer. Of course, a substance having no catalytic function may be configured as the uppermost layer, and in this case, the surface may be subjected to a catalytic treatment. Also, when the substance forming the multilayer film does not have a catalytic function, the surface of the multilayer film may be similarly catalyzed.

Among the X-ray absorbers, the one known to be deposited by electroless plating is, for example, A
g, Au, Co, Cu, Fe, Ir, Ni, Os, P
Examples thereof include d, Pt, Rh, Ru, etc., but the reaction initiation catalyst layer may use any catalytically active substance regardless of the type of the X-ray absorber to be deposited.

A typical example of the reaction initiation catalyst layer is Pd. Pd is the most commonly used catalyst for initiating the reaction in electroless plating. Of course, in addition to Pd, Co,
Fe, Ir, Ni, Os, Pt, Rh, Ru and the like can be mentioned, and these may be used without using Pd. Specific examples of the structure of such a multilayer film include one in which Pd and Si are alternately laminated and one in which Ti and Ni are alternately laminated.

In the present invention, the X-ray absorbing layer is deposited by the electroless plating method using the uppermost layer of the multilayer X-ray reflecting layer thus constructed as a reaction initiation catalyst. The electroless plating method is a method in which the uppermost layer is used as a reaction initiation catalyst and a substance to be plated is reduced by a chemical reduction reaction to deposit the reduced metal on the uppermost layer surface of the multilayer X-ray reflection layer. .

Since the uppermost layer of the multilayer X-ray reflection layer is exposed in a pattern conforming to the resist pattern, the metal layer obtained by deposition also conforms to the resist pattern. Become. (For example, when the resist pattern is negative, the obtained metal layer pattern is positive.)

Further, the resist functioning as a mask is
It can be easily removed by using a solvent or an ashing method. Such a removing method does not damage the X-ray absorbing layer and the multilayer film which is particularly difficult to repair. It is possible to always obtain a reflective mask having good performance without lowering the reflectance.

In this way, X is obtained by the electroless plating method.
Since the line absorption layer is formed by deposition, a reflective mask with good transfer accuracy can be obtained efficiently by a simple operation. Furthermore, the manufacturing efficiency is improved because fewer manufacturing steps are required compared to the conventional method, and the time is about 20% (of course,
It cannot be said unequivocally because it depends on the material of the mask and the conventional method for comparison, but on average, it can be shortened and productivity is improved.

Since the electroless plating method is used,
When a defective product is generated, the defective portion can be easily repaired regardless of whether it is a reflective portion or a non-reflective portion, so that the product yield can also be improved. Further, the electroless plating method can form the X-ray absorber layer with a simpler device (no power supply is used) than the above-described electrolytic plating method, and thus it is inexpensive and has good workability. There is also an advantage.

Further, in the invention of claim 5, in the method of manufacturing the reflection type mask of claim 3, before the step of forming the X-ray absorbing layer, there is a conductive treatment step of making the surface of the X-ray reflecting layer conductive. A method characterized by being further provided is proposed. That is, since the entire surface of the X-ray reflection layer is made conductive, X
There is no limitation on the material of the line reflection layer, and regardless of what kind of material the X-ray reflection layer is made of, it is possible to always perform good electrolytic plating treatment.

The material used for the electrode layer added by this conductivity treatment is not particularly limited as long as it is a substance having high conductivity, but for example, Ag, Au, Co, Cu, Fe,
Ir, Mn, Mo, Ni, Pb, Pd, Pt, Rh, R
u, Re, Sn, W and the like can be mentioned. The electrode layer may be very thin, as long as the entire surface of the multilayer film is made conductive. Therefore, even if the electrode layer is added by the conductive treatment, the X-ray reflectance of the multilayer film is hardly affected.

Further, in the invention of claim 6, in the method of manufacturing the reflective mask according to claim 4, before the step of forming the X-ray absorbing layer, a step of catalyzing the surface of the X-ray reflecting layer is performed. A method characterized by being further provided is proposed. That is, similarly to the case where the entire surface of the X-ray reflection layer is made conductive, there is no limitation on the material of the X-ray reflection layer, and it is always preferable that the X-ray reflection layer is made of any material. Electroless plating treatment can be performed.

The catalyst added by this electroconductivity treatment includes Co, Fe, Ir, Ni, Os, Pd, Pt,
Rh, Ru, etc. can be mentioned. These catalyst layers may be very thin as long as the entire surface of the multilayer film has a catalytic action. Therefore, even if the catalyst layer is added by the catalysis treatment, the X-ray reflectance of the multilayer film is hardly affected.

Therefore, it is of course possible to obtain a reflection type mask having a good transfer performance, and of course, it is possible to obtain a production mask which is convenient for the production side such as production cost and availability without being influenced by the material of the X-ray reflection layer. Can be selected to

[0067]

The present invention will be described in more detail with reference to the following examples. FIG. 1 is a sectional view showing a first embodiment of the present invention in the order of steps. In the first embodiment, the case where the X-ray absorber layer is formed by the electrolytic plating method is mentioned.

FIG. 1A shows a mask substrate of 160 m.
It shows a state in which a multilayer film X-ray reflection layer 2 is formed on an m-square Si wafer 1. The multilayer X-ray reflection layer 2 is made of Mo.
(Molybdenum) and Si (silicon) are alternately laminated by using an ion beam sputtering method. When the Mo film and the Si film are a pair of layers, 50
It is composed of a pair of layers and has a period length of 6.7 nm and a film thickness ratio of 0.5. Further, in order to use the uppermost layer of the multilayer X-ray reflective layer 2 as an electrode, the uppermost layer is formed as a Mo film.

FIG. 1B shows a state in which the resist layer 4 is formed on the surface of the multilayer X-ray reflection layer 2 described above.
The resist layer 4 has a thickness of about 1 μm on the surface of the multilayer X-ray reflection layer 2 (made by Sumitomo Chemical: PFi).
After applying -15), 90 ° C with a hot plate,
Pre-baking was performed for 1 minute to form the resist layer 4.

Further, FIG. 1C shows a state where the resist layer 4 is patterned. That is, ultraviolet rays (i-line)
The resist layer 4 is exposed to a resist pattern of 0.4 to 4 μmL & S by a reduction projection exposure method using
After baking at 110 ° C. for 1 minute on a hot plate, the resist pattern 4a is transferred to a mask by developing with a developing solution (NMD-3).

FIG. 1D shows the resist pattern 4a.
The state in which the X-ray absorber layer 3 is formed by the electrolytic plating method on the pattern groove 4b (here, one place is shown as a representative) formed by is shown.

The composition of the electrolytic plating solution was an aqueous solution of nickel sulfamate (450 g / l), boric acid (30 g / l) and sodium lauryl sulfate (0.5 g / l). The conditions for electrolytic plating were a current density of 1 A / dm ² and a pH of 3. ~ 4,
The bath temperature is set to 50 ° C., and the electrolytic nickel 3 is grown to a thickness of about 110 nm.

Here, nickel (Ni) is grown as an absorber layer, but as the absorber material to be added by the electrolytic plating method, in addition to Ni, for example, Ag, Au,
Cd, Co, Cr, Cu, Fe, Mn, Pb, Pt, R
It is possible to use h, Sn, Zn and their alloys CdTe, Cow, etc., and the plating solution may be adjusted according to the X-ray absorber to be deposited, and the optimum plating conditions may be selected.

The thickness of the plating may be determined according to the required mask contrast (ratio of the reflectance of the reflection portion and the non-reflection portion). For example, when Ni is used as an absorber at a wavelength of 13 nm, a mask contrast of about 100 times is obtained at a film thickness of 75 nm, and a mask contrast of about 1000 times is obtained at a film thickness of 110 nm.

Similarly, when Au is used as the absorber at a wavelength of 13 nm, the film thickness is about 10 when the film thickness is 100 nm.
A mask contrast of 0 times is obtained, and at a film thickness of 150 nm, a mask contrast of about 1000 times is obtained. Furthermore, when Cr is used as an absorber at a wavelength of 13 nm, a mask contrast of about 100 times is obtained at a film thickness of 135 nm, and a mask contrast of about 1000 times is obtained at a film thickness of 200 nm.

Further, FIG. 1 (e) shows a state where a mask of electrolytic plating is washed with pure water and dried, and then the resist 4 is removed to obtain a reflection type mask. An acetone cleaning method is used to remove the resist 4.
(Of course, another method such as the O ₂ ashing method may be used.) Through the above steps, an exposure field of 120 mm square (absorption body pattern: thickness of about 110 n) is formed on a 160 mm square substrate.
m, 0.4 to 4 μmL & S) reflective mask was obtained.

FIG. 2 is a sectional view showing a second embodiment of the present invention in the order of steps. In the second embodiment, the case where the X-ray absorber layer is formed by the electroless plating method is mentioned.

FIG. 2A shows a mask substrate of 160 m.
It shows a state in which the multilayer X-ray reflection layer 22 is formed on the m-square Si wafer 21. This multilayer X-ray reflection layer 22
Is a structure in which Pd (palladium) and Si (silicon) are alternately laminated by using an ion beam sputtering method, and when the Pd film and the Si film are a pair of layers, 50 pairs of layers are formed. And a period length of 6.7 nm and a film thickness ratio of 0.5. Furthermore, this multilayer film X
In order to use the uppermost layer of the line reflection layer 22 as a reaction initiation catalyst, the uppermost layer is formed as a Pd film.

FIG. 2B shows a state in which the resist layer 24 is formed on the surface of the above-mentioned multilayer X-ray reflection layer 22. The resist layer 24 is formed by applying a resist (Sumitomo Chemical Co., Ltd .: PFi-15) on the surface of the multilayer X-ray reflection layer 22 to a film thickness of about 1 μm, and then prebaking at 90 ° C. for 1 minute with a hot plate. By performing the above, a resist layer 24 was formed.

Further, FIG. 2C shows a state in which the resist layer 24 is patterned. That is, ultraviolet rays (i
Resist layer 24 by a reduction projection exposure method using
Resist pattern of 0.4 to 4 μmL & S (line and space pattern) is exposed to light on a hot plate at 110 ° C. for 1 minute, and then developed with a developing solution (NMD-3) to form a resist pattern. 24a is transferred to the mask.

FIG. 2D shows the resist pattern 24.
The state in which the X-ray absorber layer 23 is formed by the electroless plating method is shown on the pattern groove 24b (here, one position is representatively shown) formed by a.

The composition of the electroless plating solution is nickel chloride 3
0 g / l, 10 g / l of sodium hypophosphite, and 10 g / l of sodium citrate were used. The conditions for electroless plating were pH 4 to 6, bath temperature of 90 ° C., and electroless nickel 23 of about 150 nm. Grow to thickness.

Here, nickel (Ni) is grown as the absorber layer, but as the absorber material added by the electrolytic plating method, in addition to Ni, for example, Ag, Au,
It is possible to use Co, Cu, Pd, Pt and alloys having these as a base metal, and the optimum plating conditions may be selected by adjusting the plating solution according to the X-ray absorber to be deposited.

Further, as shown in FIG. 2E, after the electrolytic plated mask is washed with pure water and dried, the resist 24 is removed.
Is removed to obtain a reflective mask.
An acetone cleaning method is used to remove the resist 24. (Of course, another method such as O ₂ ashing method may be used.)

Through the above steps, a reflective mask having an exposure field of 120 mm square (absorber pattern: thickness of about 110 nm, 0.4 to 4 μmL & S) was obtained on a 160 mm square substrate.

FIG. 3 is a sectional view showing a third embodiment of the present invention in the order of steps. In the third embodiment, the case where the X-ray absorber layer is formed by electrolytic plating after the surface of the X-ray reflection layer is made conductive.

FIG. 3A shows a mask substrate of 160 m.
It shows a state in which the multilayer X-ray reflection layer 32 is formed on the m-square Si wafer 31. This multilayer X-ray reflection layer 32
Is a structure in which Mo (molybdenum) and Si (silicon) are alternately laminated by using an ion beam sputtering method. When the Mo film and the Si film are a pair of layers, the uppermost layer is Si. It is composed of 50 pairs of layers configured to form a film, and has a period length of 6.7 nm and a film thickness ratio of 0.5.

FIG. 3B shows a state in which the electrode layer 35 is formed on the surface of the above-mentioned multilayer X-ray reflection layer 32 as a conductive treatment. The electrode layer 35 was formed of Ru (ruthenium) so as to have a film thickness of about 3 nm by using an ion beam sputtering method.

FIG. 3C shows a state in which the resist layer 34 is formed on the surface of the electrode layer 35 described above. The resist layer 34 is a resist (PFi- manufactured by Sumitomo Chemical Co., Ltd.) on the surface of the multilayer X-ray reflection layer 32 so that the film thickness is about 1 μm.
After applying 15), use a hot plate at 90 ° C for 1
The resist layer 34 was formed by performing pre-baking for a minute.

Further, FIG. 3D shows a state where the resist layer 34 is patterned. That is, ultraviolet rays (i
Resist layer 34 by a reduction projection exposure method using
A resist pattern of 0.4 to 4 μmL & S was exposed to light, baked at 110 ° C. for 1 minute on a hot plate, and then developed with a developing solution (NMD-3) to form a resist pattern 34a.

FIG. 3E shows the resist pattern 34.
The state where the X-ray absorber layer 33 is formed by the electrolytic plating method on the pattern groove 34b (here, one place is shown as a representative) formed by a is shown.

The composition of the electroplating solution was an aqueous solution of 450 g / l nickel sulfamate, 30 g / l boric acid, and 0.5 g / l sodium lauryl sulfate. The conditions for electroplating were: current density 1 A / dm ² , pH 3 ~ 4,
The bath temperature is set to 50 ° C., and the electrolytic nickel that is the absorber layer 33 is grown to a thickness of about 110 nm.

Here, nickel (Ni) is grown as the absorber layer, but as the absorber material added by the electrolytic plating method, in addition to Ni, for example, Ag, Au,
Cd, Co, Cr, Cu, Fe, Mn, Pb, Pd, P
t, Rh, Sn, Zn and their alloys CdTe, Co
It is possible to use w or the like, and the plating solution may be adjusted according to the X-ray absorber to be deposited, and the optimum plating conditions may be selected.

Further, FIG. 3 (f) shows that after the electrolytic plated mask is washed with pure water and dried, the resist 34 is used.
Is removed to obtain a reflective mask.
An acetone cleaning method is used to remove the resist 34. (Of course, another method such as O ₂ ashing method may be used.)

Through the above steps, a reflective mask having an exposure field of 120 mm square (absorber pattern: thickness of about 110 nm, 0.4 to 4 μmL & S) was obtained on a 160 mm square substrate.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention in the order of steps. In the fourth embodiment, the case where the X-ray absorber layer is formed by the electroless plating method after the surface of the X-ray reflection layer is catalyzed.

FIG. 4A shows a mask substrate of 160 m.
It shows a state in which the multilayer X-ray reflection layer 42 is formed on the m-square Si wafer 41. This multilayer X-ray reflection layer 42
Is a structure in which Mo (molybdenum) and Si (silicon) are alternately laminated by using an ion beam sputtering method. When the Mo film and the Si film are a pair of layers, the uppermost layer is Si. It is composed of 50 pairs of layers configured to form a film, and has a period length of 6.7 nm and a film thickness ratio of 0.5.

FIG. 4B shows a state in which a catalyst layer 46 is formed on the surface of the above-mentioned multilayer X-ray reflection layer 42 as a catalytic treatment. The catalyst layer 46 was formed of Pd (palladium) by an ion beam sputtering method so as to have a film thickness of about 2 nm.

FIG. 4C shows a state in which the resist layer 44 is formed on the surface of the catalyst layer 46 described above. The resist layer 44 is a resist (PFi- manufactured by Sumitomo Chemical Co., Ltd.) so that the film thickness is about 1 μm on the surface of the multilayer X-ray reflection layer 42.
After applying 15), use a hot plate at 90 ° C for 1
The resist layer 44 was formed by performing pre-baking for a minute.

Further, FIG. 4D shows a state in which the resist layer 44 is patterned. That is, ultraviolet rays (i
Resist layer 44 by a reduction projection exposure method using
Was exposed to a resist pattern of 0.4 to 4 μmL & S, baked at 110 ° C. for 1 minute on a hot plate, and then developed with a developing solution (NMD-3) to form a resist pattern 44a.

FIG. 4E shows the resist pattern 44.
The state in which the X-ray absorber layer 43 is formed by the electroless plating method on the pattern groove 44b (here, one place is shown as a representative) formed by a is shown.

The composition of the electroless plating solution is nickel chloride 3
0 g / l, sodium hypophosphite 100 g / l, sodium citrate 10 g / l aqueous solution, electroless plating conditions are pH 4-6, bath temperature 90 ° C. Nickel is grown to a thickness of about 150 nm.

Here, nickel (Ni) is grown as an absorber layer, but as the absorber material added by the electroless plating method, in addition to Ni, for example, Ag or A is used.
It is possible to use u, Co, Cu, Pd, Pt and alloys having these as a base metal. The plating solution may be adjusted according to the X-ray absorber to be deposited and the optimum plating conditions may be selected. .

Further, FIG. 4 (f) shows a state in which the mask subjected to electroless plating is washed with pure water and dried, and then the resist layer 44 is removed to obtain a reflection type mask. An acetone cleaning method is used to remove the resist layer 44. (Of course, another method such as O ₂ ashing method may be used.)

Through the above steps, a reflective mask having an exposure field of 120 mm square (absorber pattern: thickness of about 110 nm, 0.4 to 4 μmL & S) was obtained on a 160 mm square substrate.

[0106]

As described above, according to the present invention, since the X-ray absorber layer can be patterned without damaging the surface of the X-ray reflection layer, the surface of the reflective mask has no roughness and is excellent. A reflective mask having a reflectance can be obtained. Furthermore, a reflective mask with good transfer accuracy can be obtained by a simple manufacturing process by the additive method.

Since the line width of the pattern provided on the mask can be adjusted by the resist pattern, it is possible to sufficiently deal with a fine pattern used for X-ray projection exposure. Of course, the process of repair is simple and the workability is good, so that the manufacturing efficiency of the reflective mask is improved.

Furthermore, since the mask obtained by the method of the present invention has a good reflectance, when exposure is performed using this mask, an image can be formed on the wafer without significantly reducing the light amount of the reflected light flux. Therefore, the exposure time can be shortened. That is, the irradiation intensity of the illumination light for the mask per unit number does not decrease, so that the irradiation time per unit number is shortened and the life of the mask is further extended.

On the contrary, the irradiation time is set to the same level as the conventional one,
Even if the light source to be used is a light source having a lower brightness than the conventional one, the same effect as the conventional one can be exhibited, so that the cost can be kept low by this configuration.

From the above, by using the mask obtained by the method of the present invention, the throughput of the exposure apparatus as a whole can be improved. Further, by using the plating method, mass production is facilitated at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention in the order of steps.

FIG. 2 is a sectional view showing a second embodiment of the present invention in the order of steps.

FIG. 3 is a sectional view showing a third embodiment of the present invention in the order of steps.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention in the order of steps.

5A is a cross-sectional view of a reflective mask obtained by patterning an X-ray reflective multilayer mirror, and FIG. 5B is a reflective mask obtained by patterning an X-ray absorber layer. It is sectional drawing of a mask.

FIG. 6 is a cross-sectional view showing the manufacturing process of a conventional reflective mask in the order of processes.

[Explanation of symbols]

1, 21, 31, 41, 51a, 51b, 61 Mask substrate 2, 22, 32, 42, 52a, 52b, 62 Multi-layer X-ray reflection layer 3, 23, 33, 43, 53b, 63 Absorber 4, 24 , 34, 44, 64 resist 4a, 34a, 44a resist pattern 4b, 34b, 44b pattern groove 35 electrode layer 46 catalyst layer

Claims (6)

[Claims] 1. When manufacturing a reflective mask for X-ray projection exposure by forming an X-ray absorbing layer having a predetermined pattern on the surface of the X-ray reflecting layer, a pattern is formed on the surface of the X-ray reflecting layer. A resist pattern forming step of forming a patterned resist layer, an X-ray absorbing layer forming step of forming an X-ray absorbing layer on the surface of the X-ray reflecting layer exposed from the pattern of the resist layer, and the X-ray absorbing layer. And a resist removing step of removing the resist layer after the forming step. 2. In the X-ray absorbing layer forming step, X is formed on the surface of the X-ray reflecting layer exposed from the pattern of the resist layer.
The method of manufacturing a reflective mask according to claim 1, wherein the line absorption layer is deposited by a plating method. 3. A multilayer X-ray reflection layer is used as the X-ray reflection layer, and the X-ray absorption layer is deposited by electrolytic plating using the uppermost layer of the multilayer X-ray reflection layer as a plating electrode. The method of manufacturing a reflective mask according to claim 2. 4. A multilayer X-ray reflection layer is used as the X-ray reflection layer, and the X-ray absorption layer is deposited by electroless plating using the uppermost layer of the multilayer X-ray reflection layer as a plating reaction initiation catalyst layer. The method for manufacturing a reflective mask according to claim 2, wherein 5. The reflective mask according to claim 3, further comprising a conductive treatment step of converting the surface of the X-ray reflective layer to conductive before the step of forming the X-ray absorbing layer. Production method. 6. The reflective mask according to claim 4, further comprising a catalyzation treatment step of catalyzing the surface of the X-ray reflection layer before the X-ray absorption layer formation step. Production method.