JP3297996B2 - 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 (X-rey mask).
mask) and its manufacturing method, especially during the X-ray lithography process.
nment mark)
The present invention relates to an X-ray mask capable of maximizing the contrast of a signal (t signal) and a method of manufacturing the same.

[0002]

2. Description of the Related Art A chip pattern (chip pat) is formed on a wafer.
A general process for forming a tern) is to position a wafer and an X-ray mask in an exposure apparatus, and to transfer an image of a chip pattern designed on the X-ray mask onto the wafer by an X-ray exposure process ( transfer) and a step of forming a chip pattern on the wafer through a developing process and an etching process.

Generally, several tens of steps are required to manufacture one device through a process of manufacturing a semiconductor device. A chip pattern is formed on a wafer at each stage, and the alignment accuracy (alignment accuracy) between the formed chip pattern and a chip pattern formed later affects the reliability of the device. That is, when the accuracy of interlayer alignment is low, there is a problem that the element malfunctions due to an electric short circuit and a disconnection phenomenon. One of the factors hindering the accuracy of interlayer alignment is a case where alignment between a wafer and a mask is not performed accurately in an exposure apparatus. In order to align the wafer and the mask, an alignment mark is inserted into the mask, and during the X-ray lithography process,
The wafer and the mask are aligned by sensing an alignment signal generated from the alignment mark.

FIG. 8 is a plan view of a conventional X-ray mask 10, and FIG. 9 is a cross-sectional view of the X-ray mask 10 taken along the line AA1 in FIG. In the figure, a conventional X-ray mask 10 includes a mask substrate 1, a main chip window 4R in which a main chip pattern 4 is located, and a number of alignment windows 5R in which a number of alignment marks 5 are located. The main chip pattern 4 is formed on the membrane 2 (refer to FIG. 9; a first X-ray transmitting body described later) in the main chip window 4R, and a number of alignment marks 5 are formed on the membrane 2 (in the alignment window 5R). It is formed on a first X-ray transmitting body (to be described later).

Next, the manufacturing process of the conventional X-ray mask 10 is as follows. First, the first surface 8 of the mask substrate 1
The X-ray transmitting body 2 is formed, and the second X-ray transmitting body 3 is formed on the back surface 9 of the mask substrate 1. Next, the selected portion of the second X-ray transmitting body 3 and the mask substrate 1 is moved to the first X-ray transmitting body 2.
The main chip window 4R and a number of alignment windows 5R around the main chip window 4R are formed by sequentially etching until the substrate is exposed. The first X-ray transmitting member 2 in the main chip window 4R and the multiple alignment windows 5R is used as an X-ray mask membrane. Excluding this portion, the portion where the mask substrate 1, the first X-ray transmitting member 2, and the second X-ray transmitting member 3 are laminated becomes the X-ray non-transmissive region 7R. The main chip pattern 4 is formed on the first X-ray transmitting body 2 in the main chip window 4R, and the alignment mark 5 is formed on the first X-ray transmitting body 2 in the alignment window 5R. A pyrex ring 6 is formed along the outer periphery of the second X-ray transmitting body 3.

In the above, the mask substrate 1 is formed of silicon. In the main chip window 4R and the alignment window 5R, the first X-ray transmitting member 2 used as a membrane of the mask is formed to a thickness of about 2 μm. The membrane composed of the first X-ray transmitting body 2 is X
Since the line transmittance is required to be 5% or more, and the optical characteristics of the membrane greatly affect the improvement in the degree of alignment between the wafers, the light used for alignment has a transmittance in the visible light region. Must be kept above 80%.
Furthermore, there must be no deformation of the substance by X-ray exposure. X-ray mask membranes currently being developed are X
Silicon nitride (S
iN), silicon carbide (SiC), polysilicon (Poly-Si) and diamond.

The silicon nitride (SiN) thin film has advantages in that it has high transparency to light or X-rays, has good mechanical stability, and is easy to form a thin film.
Widely used as a membrane for X-ray masks. However, this silicon nitride (SiN) thin film
There is a problem in that deformation occurs in the line exposure process, and it is difficult to accurately transfer the image of the chip pattern 4 designed on the X-ray mask 10 to a wafer.

The silicon carbide (SiC) thin film has attracted attention as an X-ray mask membrane material because of its much higher mechanical strength than other silicon (Si) -based thin films. However, this silicon carbide (SiC) thin film has a drawback that the light transmittance is as low as about 4%. Therefore, in order to increase the light transmittance, there is a method of depositing a non-reflective substance when forming a silicon carbide (SiC) thin film. However, even with this method, the light transmittance can be increased only by 10 to 20%, and to this extent, the light transmittance for improving the accuracy of interlayer alignment is still insufficient.

The polysilicon (Poly-Si) thin film can use the existing silicon manufacturing process as it is, can adjust the stress depending on the deposition temperature, and hardly loses due to X-ray exposure. There is an advantage. However, this polysilicon (Poly-S)
i) Thin films have the disadvantage that light transmission cannot exceed 50% due to light absorption which is assumed to occur at the grain boundary. Further, the diamond thin film has a high mechanical strength, but also has a disadvantage of low light transmittance.

As described above, silicon nitride (SiN), silicon carbide (SiC), and polysilicon (Poly) used as membrane materials for X-ray masks are used.
In the case of a substance such as Si-) and diamond, when the light transmittance is excellent, there is a deformation due to X-ray exposure.
If there is no deformation due to line exposure, the light transmittance is as low as 50% or less, and there is a limit to improving the accuracy of interlayer alignment.

The main chip pattern 4 and the alignment mark 5 absorb X-rays well, and are materials such as gold (Au), tungsten (W) and tantalum (Ta), which are easy to deposit, pattern and adjust distortion. Is formed.

As described above, in the conventional X-ray mask, the alignment mark is formed on the membrane.
In this case, since the membrane is present in the entire area of the alignment window, the alignment signal is greatly attenuated when passing through the membrane in the alignment window. Therefore, it is necessary to select the material of the membrane to be used in consideration of the high light transmittance in preference to the problem of deformation due to X-ray exposure. There is a limit to improving the accuracy of the interlayer alignment that occurs.

[0013]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above problems, and has poor light transmittance despite excellent other properties. Therefore, the membrane material for an X-ray mask is required. Even if a material that was difficult to use as a membrane material is used, the contrast of an alignment signal generated from an alignment mark can be maximized in an X-ray lithography process.
It is an object of the present invention to provide an X-ray mask and a method for manufacturing the same.

[0014]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The X-ray mask according to the present invention, which has been described above, has a mask substrate, a main chip window and a main chip window.
Possess an alignment window formed around 3 or more, an X-ray mask in which the plurality of alignment marks on the membrane of each alignment window portion is formed for aligning the wafer, the mask substrate
The front and back surfaces are SiN, SiC, polysilicon,
Membrane made of material selected from Earmond
A first X-ray transmitting body and a second X-ray transmitting body are respectively formed.
And the multiple alignment marks are Au, W,
X-ray absorber selected from WTi, Ta, TaN, Mo
At right angles on a plane parallel to the mask surface
A vertical crossing that crosses the alignment window
Alignment mark and horizontal alignment mark
Each alignment mark is
When provided on the first X-ray transmitting body of the window portion,
Both ends on the surface of the first X-ray transmitting body are aligned.
Formed so that it extends beyond the window
In the alignment window portion.
Excluding the membrane part excluding the
A large number of through holes are formed by removing.

The present invention has been made to achieve the above object.
X-ray mask manufacturing method according to
Providing a mask substrate, and the mask substrate
A first X-ray transmitting body is formed on the surface of the
Forming a second X-ray transmitting body on the back surface of the mask substrate;
Forming an X-ray absorber on the first X-ray transmitting body;
Removing a selected portion of the X-ray absorber,
A chip pattern is formed in the chip window,
An alignment mark is formed on the alignment window
On both sides of the structure formed by the above process
Step of applying photoresist, double-sided exposure and development
The alignment window on the mask surface by a process
A portion of the first X-ray transmitting body, and
Before the chip window and alignment window
The photoresist is exposed so that the second X-ray transmitting body is exposed.
The pattern is patterned, and
Before the etching process using the etched photoresist as an etching mask
The exposed portions of the first and second X-ray transmitting bodies are removed.
Removing the patterned photoresist.
An etching mask is used.
The exposed part is removed and the main tip
In the window part, it is used as a mask membrane.
All of the first X-ray transmitting bodies are present,
In the alignment window,
Stage where a through hole is formed in the part excluding the print mark
Removing the patterned photoresist,
Pyrex along the outer part of the second X-ray transmitting body
And bonding the ring .

The mask substrate is formed of silicon.
It is characterized by being performed. In addition, the alignment
Window is less around the main chip window
It is characterized in that three or more are formed. In addition,
The alignment mark is located on the alignment window
Across the alignment mark, and both ends of the alignment mark
Formed so that it extends to parts other than the
It is characterized by being performed .

Further , the first and second X-ray transmitting bodies are S
Of iN, SiC, polysilicon and diamond
It is characterized by being formed by any of them. In addition,
The first and second X-ray transmitting members are formed to a thickness of about 2 μm.
It is characterized by the following. Further, the X-ray absorber is Au,
W, WTi, Ta, TaN or Mo
It is characterized by being performed .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a first X-ray mask 100 according to the first embodiment of the present invention, and FIG.
3A to 3D are cross-sectional views of the first X-ray mask 100 taken along the line A-A1. FIGS. 3A to 3D are views showing a process of forming the first X-ray mask 100 of FIG. .

Referring to FIGS. 1 and 2, a first X-ray mask 100 includes a mask substrate 11 made of silicon,
A main chip window 14R formed on the surface 18 of the mask substrate 11 and having the main chip pattern 14 positioned on the first X-ray transmitting member 12 used as a mask membrane, and a first X-ray transmitting member used as a membrane A number of alignment marks 15 are located on 12,
The through holes 150 are provided between the plurality of alignment marks 15.
Are formed, and at least three or more alignment windows are formed around the main chip window 14R.
5R and a Pyrex ring 16 adhered to the back surface 19 of the mask substrate 11. The portion excluding the portions of the main chip window 14R and the alignment window 15R is an X-ray non-transmissive region 17R.

Referring to FIG. 3A, on the surface 18 of the mask substrate 11, a first X-ray transmitting body 12 used as a mask membrane is formed. Also, the mask substrate 11
The second X-ray transmitting body 13 is formed on the back surface 19 of the substrate. Further, an X-ray absorber 140 is formed on the first X-ray transmitting body 12.

The first and second X-ray transmitting bodies 12 and 13
Is formed to a thickness of about 2 μm using one of materials having high X-ray transmittance and high mechanical strength, such as silicon nitride, silicon carbide, polysilicon and diamond. . X-ray absorber 140
Is formed of any material such as gold, tungsten, tungsten titanium, tantalum, tantalum nitride, and molybdenum, which are materials that absorb X-rays well and are easy to deposit, pattern, and adjust distortion.

Referring to FIG. 3B, an X-ray absorber 1 is formed by an electron beam lithography process and an anisotropic etching process.
By removing the selected portion 40, the main chip pattern 14 is formed on the first X-ray transmitting body 12 in the main chip window 14R. Also, a number of alignment marks 15 are formed on the first X-ray transmitting body 12 in the alignment window 15R. As shown in FIG. 1, the multiple alignment marks 15 traverse the alignment window 15R and are formed such that both ends extend to a portion other than the alignment window 15R (X-ray opaque region).

Referring to FIG. 3C, photoresist 1
Reference numeral 30 denotes a first X-ray transmitting body 1 on a mask surface 18 including a main chip pattern 14 and a number of alignment marks 15.
2 and on the second X-ray transmitting body 13 on the mask back surface 19. The applied photoresist 130 is subjected to a double-sided exposure and development process to form the first X-ray transmitting body 12 in the alignment window 15R of the mask surface 18 and the main X-ray window 14R of the mask back surface 19 and the second X-ray transmitting body in the alignment window 15R. 13 is patterned so as to be exposed. The exposed portions of the first and second X-ray transmitting members 12 and 13 are removed by using the patterned photoresist 130 as an etching mask. At this time, the alignment window 15 of the mask surface 18 is
Since a large number of alignment marks 15 are formed in the R portion, only the portion of the first X-ray transmitting body 12 other than the portion where the large number of alignment marks 15 are located is removed.

Referring to FIG. 3D, the patterned photoresist 130 is again used as an etching mask, and is exposed from the mask back surface 19 until the first X-ray transmitting body 12 on the mask surface 18 is exposed. Mask substrate 11
Is etched. At this time, in order to prevent the mask substrate 11 from being etched from the mask surface 18 through the alignment window 15R, the mask surface 18 is sufficiently protected by protective equipment such as a silicon etching chuck. Is carried out. As a result of the mask substrate 11 etching process, the first X-ray transmitting members 12 are all present in the main chip window 14R, and are used as a membrane of the mask. A through hole 150 is formed therebetween.

Thereafter, the photoresist 130 is removed,
The first X-ray mask 100 of the present invention shown in FIGS. 1 and 2 is manufactured by bonding the Pyrex ring 16 along the outer peripheral portion of the second X-ray transmitting body 13 on the mask back surface 19.

FIG. 4 is a plan view of a second X-ray mask 200 according to a second embodiment of the present invention, and FIG. 5 is a plan view of the second X-ray mask 200 cut along line A-A1 of FIG. 6A to 6D are cross-sectional views illustrating a process of forming the second X-ray mask 200 in FIG.

Referring to FIGS. 4 and 5, a second X-ray mask 200 includes a mask substrate 21 formed of silicon and a first X-ray mask formed on surface 28 of mask substrate 21 and used as a membrane of the mask. Main chip window 2 in which main chip pattern 24 is located on transparent body 22
4R and first X-ray transmitting body 2 used as a membrane
2, a large number of alignment marks 25A and 25B crossing in the vertical and horizontal directions are located, and through holes 250 are formed between the multiple alignment marks 25A and 25B to form at least three or more around the main chip window 24R. Window 25R to be formed and Pyrex ring 26 adhered to back surface 29 of mask substrate 21
Consisting of The portion excluding the portions of the main chip window 24R and the alignment window 25R becomes an X-ray non-transmissive region 27R.

Referring to FIG. 6A, first surface 18 of a mask substrate 21 is used as a mask membrane.
The X-ray transmitting body 22 is formed, and the back surface 29 of the mask substrate 21 is formed.
Then, the second X-ray transmitting body 23 is formed. First X-ray transmitting body 2
An X-ray absorber 240 is formed on 2. The first and second X-ray transmitting bodies 22 and 23 are made of a material that transmits X-rays well and has high strength, such as silicon nitride (SiN), silicon carbide (SiC), and polysilicon (Poly-S).
i) and a thickness of about 2 μm using any one of materials such as diamond. The X-ray absorber 240 is a material that absorbs X-rays well and is easy to deposit, pattern, and control distortion. Gold (Au), tungsten (W), tungsten titanium (WTi), tantalum (Ta), and tantalum nitride Ride (TaN) and molybdenum (Mo) are formed.

Referring to FIG. 6B, the X-ray absorber 2 is formed by an electron beam lithography process and an anisotropic etching process.
The main chip pattern 24 is formed on the first X-ray transmitting body 22 in the main chip window 24R by removing the selected portion 40, and a number of vertical lines are formed on the first X-ray transmitting body 22 in the alignment window 25R. The direction alignment mark 25A and a number of lateral direction alignment marks 25B are formed to intersect. As shown in FIG. 1, the vertical alignment marks 25A and the horizontal alignment marks 25B cross the alignment window 25R, and both ends of the alignment marks 25A and 25B are aligned with the alignment window 2 respectively.
It is formed so as to extend to a portion other than 5R (X-ray non-transmissive region).

Referring to FIG. 6C, the photoresist 2
Reference numeral 30 denotes a first X-ray transmitting body 2 on a mask surface 28 including a main chip pattern 24 and a number of alignment marks 25.
2 and on the second X-ray transmitting body 23 on the mask back surface 29. The applied photoresist 230 is subjected to a double-sided exposure and development process to form the first X-ray transmitting body 22 on the alignment window 25R of the mask front surface 28, the main chip window 24R on the mask back surface 29, and the second X-ray transmitting body 23 on the alignment window 25R. Is patterned so as to be exposed. The exposed portions of the first and second X-ray transmitting members 22 and 23 are removed using the patterned photoresist 230 as an etching mask. At this time, since a large number of vertical alignment marks 25A and a large number of horizontal alignment marks 25B are formed in the alignment window 25R of the mask surface 28, the first X-rays other than those where the alignment marks 25A and 25B are located are formed. Only the transparent body 22 is removed.

Referring to FIG. 6D, the patterned photoresist 230 is again used as an etching mask, and is exposed from the mask back surface 29 until the first X-ray transmitting body 22 on the mask surface 28 is exposed. Mask substrate 21
Is etched. At this time, in order to prevent the mask substrate 21 from being etched from the mask surface 28 through the alignment window 25R, the mask surface 28 is sufficiently protected by protective equipment such as a silicon etching chuck. Is carried out. As a result of the mask substrate 21 etching process, the first X-ray transmitting members 22 are all present in the main chip window 24R, are used as a membrane of the mask, and have a large number of vertical alignment marks 2 in the alignment window 25R.
A through hole 250 is formed between 5A and each of the multiple lateral alignments 25B.

Next, the photoresist 230 is removed, and the Pyrex ring 26 is adhered along the outer peripheral portion of the second X-ray transmitting body 23 on the back surface 29 of the mask, whereby the second embodiment of the present invention shown in FIGS. The 2X-ray mask 200 is manufactured.

FIG. 7 is a view in which a wafer 400 and an X-ray mask 100 or 200 of the present invention are arranged in an X-ray lithography exposure apparatus. In the exposure apparatus, the wafer 400 and the X of the present invention are used.
After the line mask 100 or 200 is positioned, the chip pattern image of the mask 100 or 200 is transferred to the wafer 400 by irradiating X-rays. The irradiated X-rays are reflected at the alignment mark portion of the alignment window portion and pass through 100% through the through-hole of the alignment window portion. The X-ray reflected from the alignment mark is detected by the alignment microscope 300 based on the alignment signal. 100 X-rays in through hole
%, The alignment signal sensed by the microscope 300 becomes relatively high.

[0034]

As described above, according to the present invention, an alignment mark is formed on a membrane in an alignment window portion, and in the alignment portion, a membrane portion excluding the alignment mark portion is removed to form a through hole. By doing so, the light transmittance in the alignment window becomes 100%, so that the contrast of the alignment signal generated in the alignment mark during the X-ray lithography process can be maximized. As a result, materials having excellent mechanical strength and being free from deformation due to X-ray exposure, but having low light transmittance and being unable to be used as a membrane material for an X-ray mask are used as a membrane material for an X-ray mask. A possible X-ray mask and a method of manufacturing the same can be realized, and an excellent effect of opening the way to commercialization of the substance can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of an X-ray mask according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the X-ray mask according to the present invention, taken along the line AA1 in FIG.

3 (a) to 3 (d) are views showing steps of forming the X-ray mask shown in FIG.

FIG. 4 is a plan view of an X-ray mask according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of X of the present invention taken along line AA1 in FIG.
It is sectional drawing of a line mask.

6 (a) to 6 (d) are views showing steps of forming the X-ray mask shown in FIG.

FIG. 7 is a diagram in which a wafer and an X-ray mask are arranged in an X-ray lithography exposure apparatus.

FIG. 8 is a plan view of a conventional X-ray mask.

FIG. 9 is a cross-sectional view of the conventional X-ray mask taken along the line AA1 in FIG.

[Explanation of symbols]

 1, 11, 21 mask substrate 2, 12, 22 first X-ray transmitting member (membrane) 3, 13, 23 second X-ray transmitting member 4, 14, 24 main chip pattern 4R, 14R 24R main chip window 5, 15, 25A, 25B alignment mark 5R, 15R, 25R alignment window 6, 16, 26 pyrex ring 7R, 17R, 27R X-ray non-transparent area 8, 18 , 28 mask front 9,19,29 mask back 10,100,200 X-ray mask 130,230 photoresist 140,240 X-ray absorber 150,250 through hole 300・ Alignment microscope 400 ・ ・ Wafer

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kim Boo-Young, Korea Republic of Korea Daejeon Metropolitan City, Yuseong-gu, Yeonseok-dong Hanbit Apartment 107-1704 130-1206 (56) References JP-A-57-199220 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 1/16

Claims (8)

(57) [Claims] 1. A mask substrate and a main chip window.
Three or more are formed around the main chip window
It was closed and alignment window, an the X-ray mask multiple alignment marks on the membrane is formed in each alignment window portion for aligning the wafer, on the surface and the back surface of the mask substrate, SiN , SiC,
Made of material selected from polysilicon and diamond
The first X-ray transmitting body and the second X-ray transmitting body, which are membranes,
Each of the alignment marks is formed of Au, W, WTi,
It consists of an X-ray absorber selected from Ta, TaN, and Mo.
At right angles on a plane parallel to the disc surface
Vertical alignment across the alignment window
Mark and a lateral alignment mark, each said alignment mark being a respective alignment window.
The window is provided on the first X-ray transmitting body, and
1 Both ends on the surface of the X-ray transmitting body
The alignment window portion is formed so as to extend to a portion other than the window.
Remove the membrane portion excluding the
An X-ray mask, wherein a large number of through-holes are formed . 2. A method of manufacturing an X-ray mask, comprising: providing a mask substrate; forming a first X-ray transmitter on a front surface of the mask substrate; and providing a second X-ray transmitter on a back surface of the mask substrate. Forming, forming an X-ray absorber on the first X-ray transparent body, removing a selected portion of the X-ray absorber, forming a chip pattern on a main chip window portion, A step of forming an alignment mark in the alignment window portion, a step of applying a photoresist to both surfaces of the structure formed by the above-described process, and a double-sided exposure and development process, wherein the first X of the alignment window portion on the mask surface is formed. The X-ray transmitting body and the second X-ray transmitting body in the main chip window and the alignment window on the back surface of the mask are exposed. Patterning the photoresist, removing the exposed portions of the first and second X-ray transmitting members by an etching process using the patterned photoresist as an etching mask, The photoresist is again used as an etching mask, and the exposed portion of the back surface of the mask is removed by an etching process, so that the first X-ray transmitting body used as a membrane of the mask is entirely present in the main chip window portion. Forming a through-hole in a portion of the alignment window excluding the alignment mark; removing the patterned photoresist to form a Pyrex ring along an outer portion of the second X-ray transmitting body; X-rays comprising the steps of bonding Mask manufacturing method. 3. The method according to claim 2 , wherein the mask substrate is formed of silicon. 4. The method according to claim 2 , wherein at least three or more alignment windows are formed around the main chip window. 5. The X-ray mask according to claim 2 , wherein the alignment mark is formed so as to traverse the alignment window portion and both ends of the alignment mark extend to portions other than the alignment window. Production method. 6. The method according to claim 2 , wherein the first and second Xs are provided.
The method for manufacturing an X-ray mask, wherein the line transmitting body is formed of any one of SiN, SiC, polysilicon and diamond. 7. The method according to claim 2 , wherein the first and second Xs are provided.
The method for manufacturing an X-ray mask, wherein the radiation transmitting body is formed to a thickness of about 2 μm. 8. The method according to claim 2 , wherein the X-ray absorber comprises:
An X-ray mask manufacturing method characterized by being formed of any one of Au, W, WTi, Ta, TaN and Mo.