JPH11271958A - High resolution photomask and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a high-resolution photomask by decreasing the fluctuations in the critical dimensions(CD). SOLUTION: The decrease of the fluctuations in the CD may be embodied by using a thin conductive transfer layer 13 which may be patterned by electron beam lithography and dry or wet etching. The patterns are transferred to a lower layer film 12 by reactive ion etching. The lower layer film may be made opaque or partially transparent at 365, 248 and 193 nm. The thin conductive transfer layer 13 is formed of, for example, a thin Cr film and the opaque or partially transparent material may be formed of a carbon film, silicide metal or silicide oxy-nitride film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an integrated circuit (IC).
In particular, the present invention relates to a photomask structure useful for fabricating a semiconductor device, and more particularly to a photomask capable of manufacturing a Si device with a very large uniformity and a high operation speed with greatly improved line width control.

[0002]

2. Description of the Related Art Photomask requirements will be more stringent for next generation gigabit DRAM memories and microprocessors with features below 0.25 .mu.m. Photomasks used to write fine line features and patterns on photoresist will have a significant impact on the manufacturing process. The binary mask used today is
It will not be sufficient to write lithographic features that meet specifications such as those required for critical dimension (CD) control. For the masks used today, the variation in CD is on the order of 40 nm (3σ). For future requirements of gate lengths of 0.25 μm or less, CD variations cannot be allowed to exceed ± 10 nm across the quartz mask plate.
This poses a serious challenge to today's photomask manufacturing.

At present, the standard photomask material is Cr. This opaque material is sputtered onto a quartz plate that has high transmission at deep ultraviolet (DUV) wavelengths.
To achieve very fine lines, Cr is patterned using electron beam lithography. After the pattern is formed on the photoresist, Cr is wet-etched using the photoresist as a protective mask. 1 to 5 show a mask manufacturing process. First, a Cr film is sputtered on a quartz plate (FIG. 1). Photoresist is spin-coated on top (FIG. 2) and patterned using e-beam lithography (FIG. 3). By using photoresist as an etching mask, Cr is wet etched into fine lithographic lines (FIG. 4). Finally, the photoresist is removed on Cr (FIG. 5).

[0004] FIG. 4 shows how a substantial metal undercut is caused by wet etching of Cr. For example, if the original resist line width is 1 (FIG. 3), the line width transferred to Cr after wet etching will be 1-2d. For a typical Cr film thickness of 1100 °, the undercut d is on the order of 1000 °. Therefore, in order to obtain the correct Cr line width, it is necessary to compensate or bias the photoresist image in consideration of the metal undercut.

[0005] This limits the ultimate resolution achievable with DUV photomasks. One solution to this problem is to use a photoresist as a mask to
Reactive ion etching of the membrane. Unfortunately, today's e-beam resists used to make photomasks cannot withstand a reactive ion etching process. Another solution is to reduce the undercut by reducing the thickness of Cr. The Cr film used for the mask is not an optically uniform single layer in order to satisfy all the photomask requirements, but rather has a multilayer structure.
If the thickness of r is reduced, several problems arise. Note that these photomask requirements include the following. Have opacity with optical density greater than 2 at UV and DUV (365, 248 nm); Reflectivity must be less than 20% for UV and DUV. The film etching must be very precisely controlled.

FIG. 6 shows an example of a Cr mask structure. FIG.
Is used to achieve optical densities greater than 2. A Cr oxide layer or a Cr oxy-nitride layer is used to achieve better control under wet acid etching. It may be difficult to perform a wet etch reliably with only dark Cr and may have high reflectivity. The upper layer contains some Cr carbide compounds and needs to obtain a low reflectivity of about 11-14%. C
If only r-oxide, Cr oxy-nitride, Cr carbide are used, the film cannot have the correct optical density to be partially transparent at DUV.
Therefore, if a thin Cr layer (approximately 400 °) must be used, only dark Cr has the correct opacity while its reflectivity is too high (> 30).
%), Control of film etching is deteriorated. When exposing the photoresist, low reflectivity is required to prevent light from being reflected into the UV optical stepper. In addition, the low reflectivity facilitates electron beam patterning of the photoresist.

From the above discussion, the thin Cr of about 400 °
Obviously, it cannot be used to improve the control of the mask line width.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved mask by using different films as the absorbing layer.

It is another object of the present invention to provide an improved mask having a thin film absorber formed by utilizing a thin conductive transfer layer.

It is yet another object of the present invention to provide a method of manufacturing a photomask having a thin absorber film with very small CD variations as compared to Cr films used today.

It is still another object of the present invention to provide a method for manufacturing a photomask as described below. That is, in this manufacturing method, a thin carbon film or MoS
i and other dry-etchable materials, such as MoSi oxy-nitride (MoSiON), are described in reference "A.
ttenated phase shift mass
k blanks with oxide or ox
y-nitirideof Cr or MoSia
bsorbtive shifter "byY.Sai
to et al. , Photomask Japan
'94, Kanagawa Science Par
It is an object of the present invention to provide a method for manufacturing a photomask using an absorber as found in K. Kanagawa, Japan and a very thin Cr oxy-nitride-carbide conductive layer as a pattern transfer body (see above). The teaching content of the literature is cited as the content of this specification). Using electron beam lithography for patterning and reactive ion etching of Cr oxy-nitride-carbide and transferring the pattern to the absorber film using Cr oxy-nitride-carbide as an etching mask. , A fine line pattern is formed. US Patent 5,506,080
The specification discloses a method for producing a defect-free mask using a Cr layer as a transfer layer. As described in our application, a Cr layer is not appropriate to achieve the CD control required for next generation photomasks. As mentioned above, a pure Cr layer is unsuitable for wet etching, which creates an uncontrollable excessive undercut and severely limits CD control. Furthermore,
As described above, the high reflectivity of pure Cr is inappropriate when the photoresist is exposed to ultraviolet light.

[0012]

SUMMARY OF THE INVENTION A general aspect of the present invention is a high resolution photomask and a method of manufacturing the same.

[0013] Particular embodiments of the invention include UV and DUV
A manufacturing method by using a carbon photomask and a very thin conductive Cr transfer etching layer.

Another specific embodiment of the method and structure according to the present invention is described in US application Ser. No. 08 / 664,729 (199).
An opaque or partially transparent (at 365, 248, 193 nm) carbon film as described in U.S. Pat. And then depositing a thin Cr film of about 400 ° which can contain atomic species such as oxygen, nitrogen, carbon and trace water vapor. The contents of the above two U.S. patent application specifications are cited as the contents of this specification.

Yet another aspect of the method and structure of the present invention is to deposit a dry-etchable opaque or partially transparent metal, such as MoSiON, or a metal oxy-nitride as an absorber film. That is. Other silicide materials may include WSi, TaSi, TiSi, ZrSi with variable amounts of oxygen and nitrogen.

Yet another specific aspect is a process for manufacturing a photomask having greatly improved CD control.
This process involves forming an opaque or partially transparent absorber film on a quartz substrate, and about 40 Å on top of the absorber film.
Forming a thin Cr or Cr-rich alloy film of 0 ° or less, forming a photoresist layer on the thin Cr alloy sensitive to electron beam radiation, exposing the photoresist to an electron beam, and masking the photoresist Forming a pattern, using photoresist as a mask,
Carefully control the undercut of the r-alloy,
Etching the alloy, removing the photoresist, anisotropically dry-etching the absorber film in plasma using the Cr alloy as an etching mask, and optionally Cr alloy on the absorber film Removing the layer.

By using this method, excellent control of the mask line width can be obtained. In particular, variations in line width across the quartz plate can vary from about ± 40 nm typical of today's state-of-the-art
It can be reduced to 10 nm. Therefore, it is possible to control the critical dimension of the Si device, which exhibits a higher degree of uniformity and speed, and is excellent.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photomask structure and a method for manufacturing the same. The mask structure is a thin carbon film,
Alternatively, it is manufactured by depositing a metal oxy-nitride such as MoSiON and then depositing a thin Cr oxy-nitride film or Cr oxy-nitride carbide film on top. This thin C
The r-containing film is patterned using electron beam lithography to form a thin Cr oxy-nitride or Cr
Using oxy-nitride carbide as an etching mask, reactive ion etching of the lower absorbing (lower) film results in very fine lines.
Features can be formed. For example, when the absorber film is carbon, oxygen reactive ion etching can be used. Masks made in accordance with the present invention have significantly better CD control than standard photomasks when it is necessary to write line features smaller than 0.25 microns. This will be apparent from the detailed description below.

The following examples relate to carbon reticles. Other materials that are dry-etchable, such as MoSiON, and can be made opaque or translucent at UV and DUV wavelengths should be used equally equally with minor analytical modifications. be able to.

To analyze the lithographic performance of a carbon film on a chrome-on-glass reticle, we look at the process window for nested line space patterns and isolated line space patterns. it can. The process window is a measure of how much focus variation is acceptable in a lithographic process, given that the process has a certain amount of exposure dose variation. Thus, the process window is a measure of the depth of focus (DOF) and exposure latitude (EL) in the lithographic process to keep critical features within a certain tolerance of their desired size, ie, within the critical dimension (CD). It is. The process window is typically the D
It can be displayed graphically as OF vs. EL or reduced to a single index of goodness, such as depth of focus at 10% exposure latitude. Another useful index of goodness is the DOF called the total window
The area under the curve versus the EL.

Here, we assume that the exposure apparatus is 248 nm
Consider a lithographic process that is a quadruple system using an exposure wavelength of 0.5, a numerical aperture of 0.5, and a partial coherence of 0.6. Note that these values are typical for a 0.25 micron DUV lithography apparatus. We will consider the lithographic performance of a photomask that includes nominally 1.00 micron (4x) features written at 0.25 micron (1x) on the wafer. We consider the case of isolated lines and a completely nested line space pattern. Further, we assume that the photomask contains small errors in the size of critical features. For a standard chrome-on-glass type mask, we estimate that these errors are ± 0.040 microns (4
It is assumed that the error can be reduced to a value in the range of ± 0.010 to ± 0.040 microns for carbon film reticles. In the case of a carbon film reticle, in addition to the CD error, we need to consider the effects of phase and transmittance variations in the film across the reticle.
For this reason, we assume that the film thickness can be maintained to about ± 3% variation, and based on these film thickness variations,
Calculate phase and transmittance variations. All of these values correspond to current mask manufacturing capabilities.

Given these constraints, we can evaluate the relative benefits of carbon-based reticles over standard chrome-on-glass. We perform this analysis on carbon films having 1% and 2% transmission and 0 °, 90 °, 180 ° phase with respect to the transparent quartz area. For reference, a standard attenuated phase shift mask (PSK) with 7% membrane transmission is also analyzed. Because it is difficult to make dark films with 0 ° and 90 ° phase shifts, we have equivalent 360
Create films with phase shifts of ° and 270 °. FIG.
Shows% transmittance versus refractive index (n) and absorption coefficient (k) for a film that produces a 180 ° phase shift for 248 nm light. In this case, the selection range of n and k does not take into account the 1% transmittance film, but point 301 represents the values of n and k that produce a 2% transmittance film. FIG. 8 shows a similar curve for a film with a 270 ° phase shift, in which case
Point 302 represents a 1% transmittance film, and point 303 represents a 2% transmittance film. For reference, point 304 also produces a 2% transmittance film, but produces a film with different values of n and k than point 303. FIG. 9 is a curve similar to a film with a 360 ° phase shift, where point 305 is a 1% transmittance film and point 306 is a 2% transmittance film.

In the case of a film having a phase shift of 180 °,
A thickness variation of ± 3% corresponds to a phase variation of approximately 5 °.
For a film with a 270 ° phase shift, this is about 7.
For a film with a phase shift of 5 ° and a phase shift of 360 °, this is a phase shift of 10 °. 0.01
For a (1%) transmittance membrane, the thickness variation is about ± 0.0
A change in transmittance of 013 occurs. For a 2% transmittance membrane,
This variation is ± 0.0022, which is ± 0.005 for a 7% transmittance membrane. The performance of carbon-based reticles varies independently across the reticle.
The evaluation was based on D, phase, and transmittance. This is a worst case scenario and may not be possible in practice (because the transmittance will almost certainly decrease with increasing film thickness, rather than increasing with a positive phase error) Because).

In FIG. 10, we plot the total window of the isolated 250 nm line under the conditions described above. Each curve represents a different amount of mask CD error (given by a factor of four or reticle size). For reference, the performance of a standard chrome-on-glass (COG) reticle is given for each curve as the left-most point. A dotted line is drawn through each of these points. COG reticles are
Typically, assuming a CD variation of ± 40 nm, the lowest dotted line 401 through point 402 represents the baseline for comparison with the carbon mask. Points 403-40
5, it can be seen that maintaining the phase close to 180 ° is generally beneficial, but acceptable performance can be achieved with low transmission 0 ° (point 4) as long as the CD variation is small enough.
06) and 90 ° (point 407). For an isolated line, the phase is 18
When it is close to 0 ° it can clearly be seen that there is little difference in performance with different transmittances. However, if the phase differs from 180 °, it is better to use a darker film, as can be seen by comparing points 408 and 406. Points 403 and points 409-411 show the improvement of the process window when the error of the mask CD is reduced. As an example, for a process window of ± 10 nm CD error, the improvement of a 180 ° phase shift carbon mask, as shown by points 410 vs. 402, can be as large as 100%. For the out-of-phase carbon mask, the improvement over the Cr mask is about 50%, as shown by point 412 versus point 402. Similar results apply for nested lines, as seen in FIG.

For features smaller than 250 nm,
The relative benefits of carbon reticles are greater. This is due to an increase in mask error during the lithography drawing process. Therefore, CDM * MEF / Mag
At the wafer level equal to However, CDM is the spread of mask error on the reticle,
MEF is a mask error expansion coefficient, and Mag is a magnification of an exposure machine. Ideally, the MEF is close to 1, but the desired CD is the wavelength of the exposure machine divided by twice the numerical aperture (in this case, 250n
As it gets smaller for m), the MEF becomes larger than 3. Thus, the total process window effectively and rapidly shrinks with the CD error.
Develop the curves 0,11. This effect makes the carbon reticle more suitable for use with the most advanced basic rules.

FIGS. 12 and 13 show the relative performance of carbon and COG reticles for the more advanced basic rules. In FIG. 13, 150 nm at a 420 nm pitch
The total window of the lines is plotted for the various films. In this case, the state of the stepper is a numerical aperture of 0.6, an inner sigma of 0.5 and an outer sigma of 0.7.
5 ring light. For this analysis, the membrane is expected to change by 1%. In this case, the baseline COG process window is given by line 501 passing through point 502. Furthermore, the best performance is that point 509 is at baseline 5
This can be seen in the case of a 180 ° phase film showing a great advantage (about 10 times) over 01. In the case of a 90 ° phase film,
As shown by point 508, an improvement of 7.5 for a CD error of ± 10 nm can be achieved. Comparing the curves of FIGS. 12 and 13 with those of FIGS.
Two things are clear. (1) The process window is generally much smaller for the more advanced basic rules shown in FIGS. (2) In comparison, the curves of the respective CD fluctuations are wider in FIGS. 12 and 13 and show a larger MEF. It is also clear that the nested line curve of FIG. 13 has a greater spread than the isolated line curve of FIG. This means that more nested lines have ME
F indicates that it is large.

From the above discussion, it can be seen that C spreading on the photomask
It is clear that if D is reduced, the process window (total window) becomes considerably larger. For the currently used Cr photomask process, CD
The error is about ± 40 nm, which is difficult to reduce.
This is because, as mentioned above, the Cr layer is not uniform to meet the appropriate optical properties, and is therefore difficult to etch with greater uniformity. Furthermore, a reliable electron beam that can be etched with reactive ions to expand the basic rules and CD uniformity level.
There is no resist.

Next, a specific embodiment of the present invention will be described in detail. Applicable alternative embodiments are also briefly described.

A double-layer mask system will be described as an example of the structure of the present invention. In this double layer mask, the top layer is a good CD
A selective sacrificial layer that facilitates control and low CD variation. The upper sacrificial layer may be any material that can be wet-etched or dry-etched. In the present invention, the upper layer is preferably a thin Cr oxy-nitride / carbide [CrON (C)] layer. The lower layer is a blanket deposited carbon layer or other partially permeable membrane, such as metal oxides, metal nitrides, metal fluorides, metal silicon oxides, metal silicide nitrides, Metal silicide oxy
It is a night ride, but not limited to these. The basic concept is to use commonly used patterning techniques like e-beam lithography and etching,
The use of this upper layer as a dry etching mask to pattern an upper layer (eg, a CrON (C) layer) and pattern the underlying absorber film by reactive ion etching. By using a wet-etchable thin CrON (C) layer, the undercut due to wet etching is minimized and when a carbon film is used,
Vertical sidewalls can be obtained by using an oxygen-reactive ion etch that does not attack CrON (C). If a metal silicide oxy-nitride film is used as the absorber, it is desirable to use reactive ion etching based on fluorine chemicals. Under these conditions, the mask line width can be controlled extremely well, and excellent CD control on the Si wafer can be realized. It also provides a wide total process window, sub-micron
Enables advanced lithography of features.

An example of a process for manufacturing the preferred embodiment of the present invention will now be described. The following examples are provided to illustrate the scope of the present invention. The present invention is not limited to this example, as this example is provided for illustrative purposes only.

The following example uses an amorphous carbon film as the absorber. If the process variation is small,
As described above, MoSiON, TaSiON, WSi
Other absorber films such as ON, PtSiON can also be used.

Example 1 First, the carbon film 12 described in the above-cited US Patent Application is deposited on a quartz plate 10 as a blanket film. In order to deposit an opaque carbon film, it is necessary to minimize the hydrogen content or exclude hydrogen. A small amount of nitrogen can be included to increase the opacity of the film. The thickness of the carbon film is
If it is sufficiently opaque at 365, 248, 193 nm,
It is desirable to set it in the range of 200 to 3000 °. The carbon film is partially transparent (> 1%, but 365,248,19)
(<10% at 3 nm), the film thickness satisfies the requirements of the attenuated phase mask described in the cited U.S. patent application, particularly the 180 ° phase shift at the wavelengths in question. It is desirable, but not necessary.

A thin CrON (C) film 13 is blanket deposited over the carbon film 12 (FIG. 14). Cr
The thickness of the ON (C) film can be in the range of 20-2000 °, preferably 400 °. CrON (C) films can include various amounts of oxygen, carbon, and nitrogen. This is the 30 required for film patterning.
% And helps to keep the film reflectivity below 10% and make the film resistant to acid etching. The small amount of carbon in the film increases its resistance to acid etching, resulting in a more controllable CrON
(C) An undercut of the film occurs.

A photoresist 14 is spin-coated on the CrON (C) layer 13. Desirably, the photoresist is resist sensitive to electron beam radiation. Desirably, the resist thickness is about 1000 ° (FIG. 15).

The photoresist 14 is patterned using normal lithography (FIG. 16).

Using an etching process, the photoresist is used as an etching mask, and the CrON
(C) The layer 13 is patterned. In the present invention, both dry and wet etching can be used.
It is desirable to use a standard Cr (ON) (C) wet etch. As described above, since CrON (C) is thin, a minimum undercut can be obtained (FIG. 1).
7). This small undercut significantly improves CD control on the mask, so that the lithographic process window can be significantly improved when using these masks.

The photoresist 14 is then removed using a conventional wet process (FIG. 18).

The carbon film is anisotropically reactive ion etched in oxygen plasma by using the patterned CrON (C) as an etching mask. Vertical sidewalls are obtained for the carbon film.
Further, since quartz is not etched in oxygen plasma, it serves as an etching stopper (FIG. 19).

Finally, the CrON (C) film is selectively
It can be removed by ordinary acid etching (FIG. 20). Thus, the manufacture of the mask is completed.

While the present invention has been described with particular reference to preferred embodiments thereof, those skilled in the art will recognize that these and other changes may be made in configuration and detail without departing from the spirit and scope of the invention. Will be done.

In summary, the following matters are disclosed regarding the configuration of the present invention. (1) In a method of forming a high-resolution photomask at wavelengths of ultraviolet light and deep ultraviolet light, a step of adhering a two-layer film structure having an upper layer and a lower layer on a quartz blank plate, and lithography and etching of the upper layer. Patterning; and etching the lower layer using the upper layer as a pattern transfer layer. (2) The wavelengths of the ultraviolet light and the deep ultraviolet light are each 3
The method according to (1), wherein the method is selected from the group consisting of 65, 248, and 193 nm. (3) The method according to the above (1), wherein the upper layer contains Cr and the lower layer contains carbon. (4) The method according to the above (3), wherein the upper layer is made of Cr. (5) The upper layer is selected from the group consisting of Cr oxide, Cr nitride, Cr carbide, and a combination thereof.
The method described in. (6) The method according to the above (3), wherein the lower layer is made of carbon. (7) The carbon film is a diamond-like carbon film (DLC), a nitrogen-like diamond-like film (N
DLC) and fluorinated diamond-like film (F
The method according to (6), wherein the method is selected from DLC). (8) The method according to (6), wherein the carbon film is hydrogenated. (9) The method according to the above (1), wherein the lower layer is metal / silicide. (10) The metal in the silicide is W, Mo, T
The method according to (9), wherein the method is selected from i, Pt, Zr, and Ta. (11) The metal / silicide is oxygenated, nitrogenated,
Or (1) characterized in that it is oxy-nitrogenated.
The method according to 0). (12) The method according to the above (3), wherein the upper layer has a thickness of 50 to 2000 mm. (13) The method according to (12), wherein the upper layer has a thickness of about 200 ° to about 600 °. (14) The method according to the above (13), wherein the upper layer has a thickness of 400 °. (15) The method according to the above (3), wherein the upper layer has a reflectance of less than 25%. (16) The method according to the above (3), wherein the lower layer has a thickness of 200 to 2000 mm. (17) The method according to the above (16), wherein the lower layer has a thickness of 800 to 1400 °. (18) The method according to the above (3), wherein the lower layer is opaque at the wavelength. (19) The method according to (18), wherein the lower layer has a transmittance of less than 5% at the wavelength. (20) The method according to the above (19), wherein the lower layer generates a phase shift of 180 ° at the wavelength. (21) The method according to the above (18), wherein the lower layer has an optical density greater than 2 at the wavelength. (22) The method according to the above (3), wherein the lower layer has a reflectance of less than 25% at the wavelength. (23) The method according to (3), wherein the lower layer has a reflectance of less than 19% at the wavelength. (24) The method according to (3), wherein the lower layer has a reflectance of 11% or less at the wavelength. (25) The method according to the above (1), wherein the upper layer is patterned using electron beam lithography. (26) The method according to the above (1), wherein the upper layer is subjected to wet chemical etching. (27) The upper layer is patterned using a patterned resist, and about 5 to 5
The method of claim 26, wherein there is an undercut in the range of about 100 nm. (28) The undercut of the upper layer is about 20 to about 40
(27) The method according to the above (27), which is in the range of nm. (29) The lower film is made of oxygen, fluorocarbon, 6
The method according to (1), wherein the upper layer is used as a pattern transfer layer in a plasma containing a species selected from the group consisting of sulfur fluoride and a combination thereof, and reactive ion etching is performed. The described method. (30) The method according to the above (29), wherein the upper layer is wet or dry chemically removed after the completion of the pattern transfer. (31) The method according to (1), wherein the upper layer is deposited by a process selected from the group consisting of sputtering, reactive sputtering, ion beam deposition, and thermal evaporation. (32) The method of (1) above, wherein the underlayer is deposited by a process selected from the group consisting of reactive sputtering from a target, plasma enhanced chemical vapor deposition, and reactive ion beam deposition. . (33) The method according to the above (1), wherein the upper layer is removed. (34) In a method for forming a high-resolution photomask at wavelengths of ultraviolet light and deep ultraviolet light, a step of attaching a two-layer film structure having an upper layer and a lower layer on a quartz blank plate, and lithography and etching of the upper layer. Patterning, etching the lower layer using the upper layer as a pattern transfer layer, and removing the upper layer, wherein the wavelengths of the ultraviolet light and the deep ultraviolet light are 365, 248, and 193 nm. Selected from the group consisting of Cr oxide, C
a material selected from the group consisting of r-nitride, Cr carbide, and a combination thereof, wherein the lower layer is a material selected from the group consisting of carbon and silicide, and the upper layer is 50 to 2000 mm thick; The upper layer has a reflectivity of less than 25%, the lower layer has a thickness of 200 to 2000 mm, the lower layer has an optical density of greater than 2, the lower layer has a transmittance of less than 5%, Are 365, 248, and 193
A method characterized by being opaque in nm. (35) The structure of a high-resolution photomask at ultraviolet and deep ultraviolet wavelengths, comprising a two-layer film structure on a quartz blank plate, wherein the two-layer film structure has an upper layer and a lower layer, and the upper layer is patterned. Wherein the lower layer has a corresponding pattern. (36) The wavelengths of the ultraviolet rays and far infrared rays are 365,
The structure according to (35), wherein the structure is 248 nm or 193 nm. (37) The two-layer structure includes an upper layer mainly containing Cr,
The structure according to the above (35), wherein the structure is formed by a lower layer mainly containing carbon. (38) The structure according to the above (37), wherein the upper layer is made of Cr oxide, Cr nitride, Cr carbide, or a combination thereof. (39) The structure according to the above (38), wherein the lower layer is made of carbon. (40) The method according to (3), wherein the carbon film is selected from a diamond-like carbon film (DLC), a nitrogenated diamond-like film (NDLC), and a fluorinated diamond-like film (FDLC).
The structure according to 7). (41) The structure according to the above (37), wherein the carbon film is hydrogenated. (42) The structure according to the above (35), wherein the lower layer is metal / silicide. (43) The metal in the silicide is W, MO, T
The structure according to (43), wherein the structure is selected from i, Pt, Zr, and Ta. (44) The metal / silicide is oxygenated, nitrogenated,
Alternatively, the structure according to the above (43), wherein the structure is oxy-nitrogenated. (45) The structure according to (35), wherein the upper layer has a thickness of 50 to 2000 mm. (46) The structure according to the above (45), wherein the upper layer is preferably 200 to 600 ° thick. (47) The structure according to the above (46), wherein the upper layer has a thickness of 400 °. (48) The structure according to the above (35), wherein the upper layer has a reflectance of less than 25% at the wavelength. (49) The structure according to the above (35), wherein the lower layer has a thickness of 200 to 2000 mm. (50) The structure according to (49), wherein the lower layer has a thickness of 800 to 1400 °. (51) The structure according to (35), wherein the lower layer is opaque at the wavelengths of the ultraviolet light and the deep ultraviolet light. (52) The structure according to (51), wherein the lower layer has a transmittance of less than 5% at the wavelength. (53) The structure according to the above (52), wherein the lower layer generates a phase shift of 180 ° at the wavelengths of the ultraviolet light and the deep ultraviolet light. (54) The structure according to (52), wherein the lower layer has an optical density greater than 2 at the wavelength. (55) The structure according to (35), wherein the lower layer has a reflectance of less than 25% at the wavelength. (56) The structure according to (35), wherein the lower layer has a reflectance of less than 19% at the wavelength. (57) The structure according to (35), wherein the lower layer has a reflectance of about 11% at the wavelength. (58) The structure according to (35), wherein the upper layer is patterned using electron beam lithography. (59) The structure according to the above (35), wherein the upper layer is subjected to wet chemical etching. (60) The structure according to (59), wherein the upper undercut under the photoresist is in a range of about 5 to 100 nm. (61) The upper layer undercut is about 20 to 40 nm
The structure according to the above (60), wherein: (62) The lower film is formed in a plasma containing oxygen and optionally fluorocarbon or sulfur hexafluoride,
The above (3), wherein the reactive ion etching is performed using a Cr-rich layer as a pattern transfer layer.
The structure according to 5). (63) The structure according to the above (62), wherein the upper layer is wet or dry chemically removed after the completion of the pattern transfer. (64) wherein said upper layer is deposited by a process selected from the group consisting of sputtering, ion beam deposition and thermal evaporation.
Structure described in. (65) The structure of (35), wherein the underlayer is deposited by a process selected from the group consisting of reactive sputtering from a target, plasma enhanced chemical vapor deposition, and ion beam deposition.

[Brief description of the drawings]

FIG. 1 is a diagram showing a mask manufacturing process currently being implemented.

FIG. 2 is a diagram showing a mask manufacturing process currently being implemented.

FIG. 3 is a diagram showing a mask manufacturing process currently being performed.

FIG. 4 is a diagram showing a mask manufacturing process currently being performed.

FIG. 5 is a diagram showing a mask manufacturing process currently being performed.

FIG. 6 illustrates an example of a Cr mask structure currently used for mask fabrication.

FIG. 7 is a graph showing transmittance versus refractive index for various values of the absorption coefficient when the transmittance is set to give a 180 ° phase shift.

FIG. 8 is a graph showing transmittance versus refractive index for various values of the absorption coefficient when the transmittance is set to give a phase shift of 270 ° (90 °).

FIG. 9 is a graph showing transmittance versus refractive index for various values of the absorption coefficient when the transmittance is set to give a phase shift of 360 ° (0 °).

FIG. 10 shows the total process window of a 250 nm isolated line for different transmittances and phase angles as a function of various CD errors.

FIG. 11 shows the total process window of a 250 nm nested line for different transmittances and phase angles as a function of various CD errors.

FIG. 12 shows the total process window of a 150 nm isolated line for different transmittances and phase angles as a function of various CD errors.

FIG. 13 shows the total process window of a 150 nm nested line for different transmission and phase angles as a function of various CD errors.

FIG. 14 is a diagram showing a mask manufacturing process using Cr as a thin transfer etching layer.

FIG. 15 is a diagram showing a mask manufacturing process using Cr as a thin transfer etching layer.

FIG. 16 is a diagram showing a mask manufacturing process using Cr as a thin transfer etching layer.

FIG. 17 is a diagram showing a mask manufacturing process using Cr as a thin transfer etching layer.

FIG. 18 is a diagram showing a mask manufacturing process using Cr as a thin transfer etching layer.

FIG. 19 is a diagram showing a mask manufacturing process using Cr as a thin transfer etching layer.

FIG. 20 is a diagram showing a mask manufacturing process using Cr as a thin transfer etching layer.

[Explanation of symbols]

 Reference Signs List 10 quartz plate 12 carbon film 13 CrON (C) film 14 photoresist

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katherine E. Bayvic United States 10514 New York, Cappaca Birchwood Close 153 (72) Inventor Alessandro Caesar Calegari United States 10598 Yorktown Heights, New York Hanover Street 756 (72) Inventor Wallace Ray Carpenter United States 05495 Williston Paddock Lane, Vermont 4 (72) Inventor Scott Marshall Mansfield United States 12533 New York Hopewell Junction Stormville Road 159 (72) Inventor Sampath Prussissaman United States 10598 New York State York Un Heights Ravoie co-over door 2075

Claims (65)

[Claims] 1. A method for forming a high resolution photomask at ultraviolet and deep ultraviolet wavelengths, comprising: depositing a two-layer film structure having an upper layer and a lower layer on a quartz blank plate; Patterning by etching; and etching the lower layer using the upper layer as a pattern transfer layer. 2. The method of claim 1, wherein said ultraviolet and deep ultraviolet wavelengths are selected from the group consisting of 365, 248, and 193 nm, respectively. 3. The method of claim 1 wherein said upper layer contains Cr and said lower layer contains carbon. 4. The method according to claim 3, wherein said upper layer is made of Cr. 5. The method of claim 3 wherein said upper layer is selected from the group consisting of Cr oxide, Cr nitride, Cr carbide, and combinations thereof. 6. The method of claim 3, wherein said lower layer is carbon. 7. The method according to claim 1, wherein the carbon film is selected from a diamond-like carbon film (DLC), a nitrogenated diamond-like film (NDLC), and a fluorinated diamond-like film (FDLC). Item 7. The method according to Item 6. 8. The method of claim 6, wherein said carbon film is hydrogenated. 9. The method of claim 1, wherein said underlayer is metal / silicide. 10. The metal in said silicide is W, M
10. The method of claim 9, wherein the method is selected from o, Ti, Pt, Zr, and Ta. 11. The method of claim 10, wherein said metal / silicide is oxygenated, nitrided, or oxy-nitrided. 12. The method of claim 3, wherein said top layer is between 50 and 2000 degrees thick. 13. The method of claim 12, wherein said top layer is between about 200 ° and about 600 ° thick. 14. The method of claim 13, wherein said top layer is 400 ° thick. 15. The method of claim 3, wherein said upper layer has a reflectivity of less than 25%. 16. The method of claim 3, wherein said underlayer is between 200 ° and 2000 ° thick. 17. The method of claim 16, wherein said underlayer is between 800 and 1400 degrees thick. 18. The method of claim 3, wherein said underlayer is opaque at said wavelength. 19. The method of claim 18, wherein said underlayer has a transmission of less than 5% at said wavelength. 20. The method of claim 19, wherein said underlayer produces a 180 ° phase shift at said wavelength. 21. The method of claim 18, wherein said underlayer has an optical density greater than 2 at said wavelength. 22. The method of claim 3, wherein said underlayer has a reflectivity of less than 25% at said wavelength. 23. The method of claim 3, wherein said underlayer has a reflectivity of less than 19% at said wavelength. 24. The method of claim 3, wherein said lower layer has a reflectance of less than 11% at said wavelength. 25. The method of claim 1, wherein said upper layer is patterned using electron beam lithography. 26. The method of claim 1, wherein said upper layer is wet-chemically etched. 27. The method according to claim 26, wherein said upper layer is patterned using a patterned resist, and there is an undercut in the range of about 5 to about 100 nm below said resist. . 28. The undercut of the upper layer is approximately 20 to
28. The method of claim 27, wherein the method is in the range of about 40nm. 29. The method according to claim 29, wherein the lower layer is formed by reacting the upper layer as a pattern transfer layer in a plasma containing a species selected from the group consisting of oxygen, fluorocarbon, sulfur hexafluoride, and a combination thereof. Sex ion
The method of claim 1 wherein the method is etched. 30. The method according to claim 29, wherein said upper layer is wet or dry chemically removed after pattern transfer is completed. 31. The method of claim 1, wherein said top layer is deposited by a process selected from the group consisting of sputtering, reactive sputtering, ion beam deposition, and thermal evaporation. 32. The method of claim 1, wherein said underlayer is deposited by a process selected from the group consisting of reactive sputtering from a target, plasma enhanced chemical vapor deposition, and reactive ion beam deposition. . 33. The method of claim 1, wherein said top layer is removed. 34. A method for forming a high-resolution photomask at ultraviolet and deep ultraviolet wavelengths, comprising: depositing a two-layer structure having an upper layer and a lower layer on a quartz blank plate; Patterning by etching, etching the lower layer using the upper layer as a pattern transfer layer, and removing the upper layer, wherein the wavelengths of the ultraviolet light and the deep ultraviolet light are 365, 248, and 1
Selected from the group consisting of 93 nm, wherein said upper layer comprises:
Cr oxide, Cr nitride, Cr carbide,
And the lower layer is a material selected from the group consisting of carbon and silicide, the upper layer is 50-2000 mm thick, and the upper layer is less than 25%. The lower layer has an optical density of greater than 2, the lower layer has a transmittance of less than 5%, and the lower layer has a reflectance of
A method characterized by being opaque at 48, and 193 nm. 35. The structure of a high-resolution photomask at ultraviolet and deep ultraviolet wavelengths, comprising a two-layer film structure on a quartz blank plate.
The layered film structure has an upper layer and a lower layer, wherein the upper layer is patterned, and the lower layer has a corresponding pattern. 36. The wavelength of the ultraviolet ray and the far infrared ray is 3
The structure of claim 35, wherein the structures are 65, 248, and 193 nm. 37. The structure according to claim 35, wherein said two-layer structure is formed by an upper layer mainly containing Cr and a lower layer mainly containing carbon. 38. The structure of claim 37, wherein said upper layer is Cr oxide, Cr nitride, Cr carbide, or a combination thereof. 39. The structure according to claim 38, wherein said lower layer is made of carbon. 40. The carbon film is selected from a diamond-like carbon film (DLC), a nitrogenated diamond-like film (NDLC), and a fluorinated diamond-like film (FDLC). Item 38. The structure according to Item 37. 41. The structure according to claim 37, wherein the carbon film is hydrogenated. 42. The structure according to claim 35, wherein said lower layer is metal / silicide. 43. The metal in the silicide is W, M
The structure of claim 43, wherein the structure is selected from O, Ti, Pt, Zr, and Ta. 44. The structure of claim 43, wherein said metal / silicide is oxygenated, nitrided, or oxy-nitrided. 45. The structure of claim 35, wherein said upper layer is 50-2000 mm thick. 46. The upper layer is preferably 200-600.
46. The structure of claim 45, wherein the structure is thick. 47. The structure of claim 46, wherein said upper layer is 400 ° thick. 48. The structure of claim 35, wherein said upper layer has a reflectance of less than 25% at said wavelength. 49. The structure of claim 35, wherein said underlayer is 200-2000 mm thick. 50. The structure of claim 49, wherein said lower layer is between 800 and 1400 degrees thick. 51. The structure of claim 35, wherein said underlayer is opaque at said ultraviolet and deep ultraviolet wavelengths. 52. The structure according to claim 51, wherein said lower layer has a transmittance of less than 5% at said wavelength. 53. The structure of claim 52, wherein said underlayer produces a 180 ° phase shift at the ultraviolet and deep ultraviolet wavelengths. 54. The structure of claim 52, wherein said lower layer has an optical density greater than 2 at said wavelength. 55. The structure of claim 35, wherein said lower layer has a reflectivity of less than 25% at said wavelength. 56. The structure of claim 35, wherein said lower layer has a reflectivity of less than 19% at said wavelength. 57. The structure of claim 35, wherein said underlayer has a reflectivity of about 11% at said wavelength. 58. The method according to claim 35, wherein the upper layer is patterned using electron beam lithography.
The described structure. 59. The structure of claim 35, wherein said upper layer is wet chemically etched. 60. The structure of claim 59, wherein the upper undercut under the photoresist is in the range of about 5-100 nm. 61. The upper layer undercut is about 20 to 4
61. The structure of claim 60, wherein said structure is in the range of 0 nm. 62. The underlayer film is reactive ion etched in a plasma containing oxygen and optionally fluorocarbon or sulfur hexafluoride using a Cr-rich layer as a pattern transfer layer. 36. The structure of claim 35, wherein: 63. The method according to claim 63, further comprising:
63. The structure of claim 62, wherein the structure is removed wet or dry. 64. The upper layer is formed by sputtering, ion
The structure of claim 35, wherein the structure is deposited by a process selected from the group consisting of beam deposition and thermal evaporation. 65. The method according to claim 65, wherein the underlayer comprises reactive sputtering from a target, plasma enhanced chemical vapor deposition, and ion
The structure of claim 35, wherein the structure is deposited by a process selected from the group consisting of beam deposition.