JP3364151B2 - X-ray mask and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to an X-ray mask used in X-ray lithography and a method for manufacturing the same.

[0002]

2. Description of the Related Art An X-ray mask used for X-ray lithography comprises an X-ray absorber for blocking X-rays processed into a predetermined pattern and a support film for supporting the X-ray absorber. In the X-ray mask, the supporting film is required to sufficiently transmit X-rays, and therefore the supporting film needs to be sufficiently thin. Therefore, if stress is generated between the X-ray absorber and the support film, distortion is easily introduced into the X-ray mask, which greatly affects the mask position accuracy. Therefore, it is extremely important how to manufacture the X-ray mask while suppressing the stress between the X-ray absorber and the support film.

In order to manufacture a highly accurate X-ray mask with little mask distortion, the stress between the X-ray absorber and the support film must be as close to zero as possible. In addition, once the stress is adjusted to zero, it is used in the subsequent mask manufacturing process, such as the thermal process used for wafer and frame adhesion and resist coating, the acid or alkali cleaning process, or after being left in the air for a long time. It is necessary to prevent the stress value from changing due to factors such as the above. Therefore, the X-ray absorber must be thermally and chemically stable.

From such a viewpoint, a Ta-based material excellent in chemical resistance and dry etching property is used as the X-ray absorber. In particular, an amorphous film such as a TaB film, a TaSi film, or a TaGe film does not have crystal grains and has a smooth pattern edge at the time of etching unlike a normal Ta film, so that a highly accurate pattern can be formed. TaB film,
In the conventional method of manufacturing an X-ray absorber using an amorphous film such as a TaSi film or a TaGe film, zero stress adjustment was performed by annealing in a nitrogen atmosphere after film formation.

When heat treatment is performed in a nitrogen atmosphere after film formation,
The stress value changes to the tensile side. Also, this variation is
The higher the temperature, the larger it becomes. Therefore, according to the conventional method for manufacturing an X-ray absorber, X
The film of the linear absorber is formed, the stress value immediately after the film formation is measured, the annealing temperature is set from the difference between the measured stress value and zero stress, and the annealing is performed at this set temperature,
The stress was adjusted to zero.

[0006]

[Problems to be Solved by the Invention] However, TaB
Amorphous films such as films, TaSi films and TaGe films are
When annealing at about 300 ° C. in the atmosphere, as shown in FIG. 9, the stress value temporarily shifts to the tensile stress side, but thereafter, the change in stress changes to the compressive stress side, and the compressive stress increases with time. It has been clarified for the first time by the inventor of the present application.

Therefore, even if the stress is adjusted to zero by annealing after the film formation, the zero stress is changed to the compressive stress in the subsequent heat treatment step performed in the air, for example, the process of adhering the substrate to the mask frame. , X-ray mask had distortion introduced. An object of the present invention is to provide an X-ray mask in which stress does not fluctuate due to high temperature annealing in the atmosphere after zero adjustment of stress, and a manufacturing method thereof.

[0008]

[Means for Solving the Problems] The above object is to provide a supporting film,
A first element formed of Ta on the support film ,
A second element consisting of Ge, having an X-ray absorber and a third <br/> elements oxygen from the outside to be more either nitrogen or Cr prevented from being taken comprises at least containing film Is achieved by the X-ray mask. By constructing the X-ray mask in this way, it is possible to construct an X-ray mask in which the stress does not fluctuate even if high-temperature annealing is performed in the atmosphere after zero adjustment of the stress.

Further, in the above X-ray mask, it is desirable that the third element is nitrogen, oxygen, chromium or rhenium. The third element is an element that functions to prevent oxidation of the film by entering the film, or
An element that functions to increase the film density and prevent oxygen from easily entering the film can be applied, for example, nitrogen, oxygen,
Chromium or rhenium can be used.

In the above X-ray mask, the X
The line absorber is preferably a TaGeN film. Among the above X-ray absorbers, the TaGeN film has a high X-ray absorptivity and can reduce the film thickness of the X-ray absorber, and therefore is particularly effective in producing a highly accurate X-ray mask. Further, on the support film, the first element made of Ta, the second element made of Ge, and nitrogen or nitrogen for preventing oxygen from being taken in from the outside are provided.
Heat treated and the X-ray absorber formed forming at least including <br/> no X-ray absorber and third element composed of more either Cr, the support film and the X-ray absorber, the support almost a heat treatment step of adjusting the zero, and patterning step of patterning the X-ray absorber, a mask frame the supporting film, wherein the X-ray absorber is formed a stress value between the membrane and the X-ray absorber A method of manufacturing an X-ray mask, comprising: By manufacturing the X-ray mask in this way, the stress value does not fluctuate even after high-temperature annealing in the atmosphere after zero adjustment of stress, for example, heat treatment in the mask frame bonding step. Absent. Thus, it is possible to manufacture a high-precision X-ray mask with no distortion.

Further, in the above X-ray mask manufacturing method, in the step of forming the X-ray absorber, the X-ray absorption is formed on the support film by sputtering a target containing the first to third elements. It is desirable to deposit the body. Further, in the above X-ray mask manufacturing method, in the X-ray absorber forming step, the first element and the second element may be formed.
It is desirable to deposit the X-ray absorber on the support film by sputtering a target containing the element of No. 3 in an atmosphere containing the third element.

Further, in the above X-ray mask manufacturing method, the processing temperature in the heat treatment step is preferably equal to or higher than the processing temperature at which the supporting film is bonded to the mask frame in the bonding step. If heat treatment is not performed at a temperature higher than the annealing temperature for zero adjustment of the stress value in the subsequent process, the zero adjusted stress value can be maintained. It is effective to construct the manufacturing process so that the temperature is higher than the heat treatment for bonding the mask frame.

In the above X-ray mask manufacturing method, the third element is preferably nitrogen, oxygen, chromium or rhenium. Further, in the above-mentioned method for manufacturing an X-ray mask, it is desirable that the X-ray absorber is a TaGeN film.

[0014]

DETAILED DESCRIPTION OF THE INVENTION An X-ray mask and a method of manufacturing the same according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing the structure of the X-ray mask according to the present embodiment, FIGS. 2 to 4 are process cross-sectional views showing the method of manufacturing the X-ray mask according to the present embodiment, and FIG. 5 is a variation in stress value in the TaGeN film. 6 is a graph showing the relationship between the amount and the heat treatment temperature, FIG. 6 is a graph showing the relationship between the film forming chamber pressure and the stress value when the TaGeN film is formed, and FIG. 7 is the heat treatment time dependence of the variation of the stress value. FIG. 8 is a graph showing the relationship between the pressure in the film forming chamber and the stress value when forming the TaGe film when the amount of Ge mixed is changed.

First, the structure of the X-ray mask according to the present embodiment will be explained with reference to FIG. On the support film 1 2 of SiC film, X-rays absorber 14 is processed into a predetermined pattern made of TaGeN film is formed. Support film 1 2 mask frame 1 through the silicon substrate 10
It is glued to 8 . Thus, the X-ray mask according to the present embodiment is constructed.

As described above, the X-ray mask according to the present embodiment is characterized in that the X-ray absorber for absorbing X-rays is composed of the TaGeN film. As will be described later, the TaGeN film has an extremely small change in stress due to high temperature heat treatment in the atmosphere. For this reason, even if a high temperature heat treatment process such as adhesion to a mask frame is performed after zero adjustment of stress, the stress value does not change, and a highly accurate X-ray mask without mask distortion can be configured. .

The X-ray mask and the method for manufacturing the same according to the present embodiment will be described below in detail along with the manufacturing process. First, a SiC film is deposited on the silicon substrate 10 by, for example, the LPCVD method. SiC film is a film serving as a support film 1 2. Then, the surface of the SiC film is polished to form Si.
The film thickness of the C film is adjusted to, for example, about 2 μm. Thus, S
A supporting film 12 made of an iC film is formed (FIG. 2A).
The SiC film is polished in order to remove the irregularities on the surface of the SiC film immediately after the deposition.

Then, on the support film 12, a film made of a compound of Ta, Ge and N (hereinafter referred to as "sputtering method").
"TaGeN film") is deposited. Thus Ta
The X-ray absorber 14 made of a GeN film is formed (see FIG. 2).
(B)). For example, a TaGeN film is formed by using a target having a composition ratio of Ta and Ge of 4: 1, Ar and N ₂ as a sputtering gas, and an N ₂ partial pressure of 3%.
The TaGeN film may be formed by a sputtering method using a TaGe target mixed with nitrogen.

Since the stress value of the TaGeN film changes to the tensile side by annealing, the film is formed under the condition that the stress is introduced to the compression side at the film forming stage. Further, the stress value at that time is set according to the heat treatment temperature imposed in the subsequent process. For example, if a heat treatment process at 300 ° C. is assumed, 300
Taking into consideration the variation of the stress value introduced by the heat treatment at ℃ to the tensile side, the film is formed so that the compressive stress is introduced in anticipation thereof.

For example, as shown in FIG. 5, the stress value is about 200 MPa on the tensile side when the annealing temperature is 300.degree.
a fluctuates. Therefore, in the process of forming the TaGeN film, about −
The film is formed so that a compressive stress of 200 MPa is introduced.
The pressure in the film forming chamber at this time is about 15 m as shown in FIG.
Torr. Therefore, in this case, the pressure is about 15m.
If a TaGeN film is formed by Torr, the compressive stress is about -2.
A TaGeN film of 00 MPa can be formed, and the annealing can be performed at 300 ° C. thereafter to reduce the stress value to almost zero.

After that, annealing is performed to adjust the stress value to zero. In the above example, the stress value can be made almost zero by the heat treatment at 300 ° C. When setting the heat treatment temperature, it is possible to measure the stress value immediately after the deposition of the X-ray absorber 14 and calculate the heat treatment temperature at which the stress can be almost zero from the graph as shown in FIG. desirable. By doing so, the accuracy of zero adjustment of the stress value can be improved.

FIG. 7 is a graph showing the relationship between the amount of change in stress value and the annealing time when annealing is performed at 300 ° C. In the figure, ● indicates the case of TaGeN film, and ○ indicates T
The case of an aGe film is shown. As shown in the figure, in the conventionally used TaGe film, the stress value temporarily shifts to the tensile stress side, but thereafter, the variation of the stress value changes to the compressive stress side, and the compressive stress increases with time. On the other hand, in the TaGeN film, the stress value varies on the tensile stress side in the initial stage of the heat treatment, but it stabilizes after that and maintains a substantially constant stress value even if the heat treatment time increases. That is, in the TaGe film, when the high-temperature heat treatment is performed after the zero stress adjustment, the stress value fluctuates toward the compression side. However, in the TaGeN film, even if the high-temperature heat treatment is performed after the zero stress adjustment, a stress value Is almost unchanged.

The heat treatment for zero adjustment of the stress value is preferably performed at least until the stress value becomes stable. For example, in the example shown in FIG.
The stress value can be stabilized by heat treatment for about a minute. Although the mechanism by which the stress value can be stabilized by introducing nitrogen into the film is not clear, considering the experimental result that the stress value fluctuates toward the compression side due to the oxidation of the Ta film, Ta in the film is N
It is considered that it becomes difficult to combine with oxygen in the atmosphere by connecting with, and as a result, it is possible to prevent the stress value from fluctuating toward the compression side.

The Ge concentration in the TaGeN film is important in considering the relationship between the stress fluctuation amount and the film forming pressure.
FIG. 8 shows the Ge value of the stress value and the film forming pressure in the TaGe film.
This shows the concentration dependence. As shown, Ge
The higher the concentration, the more gradual the gradient of the graph becomes, and the fluctuation of the stress value with respect to the fluctuation of the film forming chamber pressure is small.

Since such a tendency is considered to be the same also in the TaGeN film, the stress controllability at the time of zero adjustment of the stress value of the TaGe film can be improved by introducing Ge in a predetermined concentration or more. From Figure 8, Ge is 5%
It is desirable to include more than. In addition, when the N concentration in the TaGeN film is greater than about 5%, a remarkable effect of preventing the variation of the stress value can be seen. On the other hand, when it exceeds about 10, the stress value hardly changes. Therefore, Ta
The N concentration in the GeN film is preferably about 10%.

After the zero adjustment of the stress value of the X-ray absorber 14 made of the TaGeN film is performed in this manner, the Cr film 16 having a thickness of about 30 nm is deposited on the X-ray absorber 14 by, for example, the sputtering method. (FIG. 2 (c)). The Cr film 16 is
This film is used as a hard mask when patterning the X-ray absorber. Then, the substrate thus formed,
It is adhered to the mask frame 18 (FIG. 3A). At this time, a heat treatment of about 300 ° C. is required, but as shown in FIG. 7, the TaGeN film is extremely stable at this heat treatment temperature, and the stress value of the TaGeN film does not change due to this heat treatment.

Then, the back surface of the silicon substrate 10 is etched to remove the silicon substrate 10 in the mask frame 18 (FIG. 3B). Then, a photoresist is applied on the Cr film 16. Next, a predetermined pattern for forming the X-ray mask is transferred to the photoresist by electron beam drawing and developed to form a resist mask 20 having the predetermined pattern (FIG. 3C).

Subsequently, the Cr film 16 is patterned using the resist mask 20 as a mask. For example, the Cr film 16 is formed by dry etching using a mixed gas of chlorine and oxygen.
To etch. After that, the resist mask 20 is removed (FIG. 4A), and the X-ray absorber 14 made of the TaGeN film is patterned using the patterned Cr film 16 as a mask (FIG. 4B). For example, the X-ray absorber 14 is etched by dry etching using chlorine.
Thus, the X-ray absorber 14 made of the TaGeN film and processed into a predetermined pattern is formed.

Then, the Cr film 16 on the X-ray absorber 14 is removed. Thus, the X-ray absorber 14 forms an X-ray mask composed of the TaGeN film (FIG. 4C).
As described above, according to the present embodiment, the X-ray absorber 14 is set to the T
Since the aGeN film is used, the stress value does not change even if high-temperature heat treatment is performed after zero adjustment of the stress of the TaGeN film that will be the X-ray absorber 14. Therefore, it is possible to form a highly accurate X-ray mask without mask distortion.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, Ta and G
Although the X-ray absorber 14 is made of a compound composed of e and N, the same effect can be obtained by introducing another third element instead of N. That is, as a result of examination by the inventor of the present application, oxygen, Cr (chromium), Re
The same effect could be obtained by introducing (rhenium).

Although the characteristics of the substance required as the third element are not clear, it is considered that the stress value fluctuates toward the compression side by the heat treatment because the X-ray absorber is oxidized. TaGe by entering inside
By introducing any third element as long as it is an element that functions to prevent oxidation of the film or an element that functions to increase the film density of the X-ray absorber and prevent oxygen from easily entering the film, It is considered that the same effect can be obtained.

In the above embodiment, the X-ray absorber in which the third element is introduced into the TaGe film is shown.
The same effect can be obtained by forming an X-ray absorber in which the third element is introduced into the B film or the TaSi film. However, B in the TaB film and Si in the TaSi film are TaGeN.
Since the X-ray absorptivity is lower than that of Ge in the film, the X-ray absorptivity of the X-ray absorber is reduced by the ratio containing these, and the film thickness must be increased accordingly. Therefore, in order to improve the processing accuracy of the X-ray absorber, TaG containing Ge having an X-ray absorptance higher than Ta in the X-ray wavelength region is included.
It is desirable to apply an eN film.

[0033]

As described above, according to the present invention, the support film, the first element made of Ta, the second element made of Ge , and the oxygen, which are formed on the support film, and oxygen are taken in from the outside. since constituting the X-ray mask by an X-ray absorber made of either become more third element and at least containing film of nitrogen or Cr prevented by the a high temperature in the air after the zero adjustment of the stress Even if annealing is performed, the stress between the support film and the X-ray absorber does not change. As a result, it is possible to prevent distortion from being introduced into the X-ray mask, so that it is possible to configure a highly accurate X-ray mask.

Further, on the support film, the first element made of Ta, the second element made of Ge , and either nitrogen or Cr for preventing oxygen from being taken in from the outside are formed. X to form the X-ray absorber comprising at least a third element
X-ray absorber forming step, heat treatment step of heat-treating the support film and the X-ray absorber to adjust the stress value between the support film and the X-ray absorber to substantially zero, and the X-ray absorber a patterning step of patterning the so producing an X-ray mask by a bonding step of bonding the supporting layer in which the X-ray absorber formed on the mask frame, the high-temperature annealing in the atmosphere after the zero adjustment of the stress Even if it does, the stress between the support film and the X-ray absorber does not change.
As a result, it is possible to prevent distortion from being introduced into the X-ray mask, so that it is possible to configure a highly accurate X-ray mask.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of an X-ray mask according to an embodiment of the present invention.

FIG. 2 is a process sectional view (1) showing the method for manufacturing the X-ray mask according to the embodiment of the present invention.

FIG. 3 is a process sectional view (No. 2) showing the method for manufacturing the X-ray mask according to the embodiment of the present invention.

FIG. 4 is a process sectional view (3) showing the method for manufacturing the X-ray mask according to the embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a heat treatment temperature and a variation amount of a stress value in a TaGeN film.

FIG. 6 is a graph showing a relationship between a film formation chamber pressure and a stress value when forming a TaGeN film.

FIG. 7 is a graph showing the heat treatment time dependency of the variation in stress value in the TaGeN film.

FIG. 8 shows TaGe when the amount of Ge mixed is changed.
It is a graph which shows the relationship between the film-forming chamber pressure at the time of film-forming, and a stress value.

FIG. 9 is a graph showing the heat treatment time dependency of the variation in stress value in a conventional X-ray absorber.

[Explanation of symbols]

10 ... Silicon substrate 12 ... Supporting membrane 14 ... X-ray absorber 16 ... Cr film 18 ... Mask frame 20 ... Resist mask

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 1/16

Claims (7)

(57) [Claims] 1. A support film and a T film formed on the support film.
a first element composed of a and a second element composed of Ge ,
Nitrogen or Cr that prevents oxygen from being taken in from the outside
X-ray mask and having a more composed X-ray absorber or become more third element and including at least the film of. 2. A X-ray mask according to claim 1 Symbol placement, the X-ray absorber, an X-ray mask which is a TaGeN film. To 3. A support film, a first element consisting of Ta, and the second element consisting of Ge, a third element which serves more either nitrogen or Cr to prevent the oxygen is taken in from the outside An X-ray absorber forming step of forming an X-ray absorber including at least , and heat-treating the support film and the X-ray absorber so that a stress value between the support film and the X-ray absorber is substantially zero. a heat treatment step of adjusting the, a patterning step of patterning the X-ray absorber, an X-ray mask; and a bonding step of bonding the supporting layer, wherein the X-ray absorber is formed on the mask frame Manufacturing method. 4. The method of manufacturing an X-ray mask according to claim 3 , wherein in the X-ray absorber forming step, the target containing the first to third elements is sputtered to form the target on the support film. X characterized by depositing an X-ray absorber
Method of manufacturing line mask. 5. The method of manufacturing an X-ray mask according to claim 3 , wherein in the X-ray absorber forming step, an atmosphere containing the target containing the first element and the second element and an atmosphere containing the third element is used. The X on the support film by sputtering in
A method of manufacturing an X-ray mask, which comprises depositing a line absorber. 6. The method of manufacturing X-ray mask according to any one of claims 3 to 5, the processing temperature in the heat treatment step, the time of bonding the supporting layer to the mask frame at the bonding step A method of manufacturing an X-ray mask, which is at a processing temperature or higher. 7. X according to any one of claims 3 to 6.
In the method of manufacturing an X-ray mask, the X-ray absorber is a TaGeN film.