JP3036320B2 - Method of manufacturing transmission mask for charged beam exposure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged beam (electron beam or charged) widely used for manufacturing fine patterns such as semiconductor integrated circuits such as LSIs, VLSIs, etc., and modifying materials. More specifically, the present invention relates to a transmission mask having through holes for charged beam exposure and a method of manufacturing the same.

[0002]

2. Description of the Related Art A typical method of manufacturing a conventional transmission mask will be described with reference to FIG. First, as shown in FIG. 3A, a Si substrate is prepared by bonding a supporting Si substrate on which an insulating layer is formed by thermal oxidation or the like and an upper Si substrate by thermal bonding or the like, and the upper Si substrate is provided with a predetermined transmission hole. And thinned to a thickness of Next, as shown in FIG. 3B, a mask layer is formed by depositing a SiN film or the like on the front and back surfaces of the bonded Si substrate, and then, as shown in FIG. An opening is formed by etching the mask layer on the back surface of the substrate.

Next, as shown in FIG. 1D, the upper Si substrate is etched to form a transmission hole, and then, as shown in FIG. 1E, a supporting Si substrate having an opening is formed using a mask layer as a protective layer. Is etched with a KOH aqueous solution or the like to form an opening. Thereafter, the mask layer is removed and the insulating layer is etched to form a transmission hole as shown in FIG.
Finally, a conductive mask for charged beam exposure can be obtained by forming a conductive layer on the upper Si substrate by sputtering or the like as shown in FIG.

However, the conventional method of manufacturing a transmission mask is as follows.
As described above and also shown in FIG. 3, the number of steps is large,
In addition, a polishing step requiring a long time and a bonding step requiring heating were included. For this reason, since a lot of labor and a long manufacturing time are required, the production cost is increased, and a decrease in the yield due to a large number of processes is inevitable.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to reduce the number of manufacturing steps, reduce the time required for manufacturing, and increase the yield as compared with the prior art. An object of the present invention is to make it possible to easily and stably manufacture a transmission mask, that is, to manufacture a transmission mask having high productivity.

[0006]

In order to achieve the above-mentioned object, the present invention provides a means for providing a through-hole having a predetermined pattern shape and arrangement and a conductive thin film in a plane of a substrate. In the method of manufacturing a transmission mask for beam exposure, (a) a step of selectively removing an Si substrate, which is a structure of the transmission mask for charged beam exposure, in a plane to an intermediate depth of the substrate thickness; The substrate is made of SiC or gold having resistance to an etchable liquid, and at least the same surface side of the substrate is coated as a thin film for stopping etching, and the opposite surface side of the substrate is (C) etching the substrate from the opening pattern on the opposite side of the substrate to reach the etching stop thin film, selectively covering the surface while leaving the opening pattern selectively; That until etching is a method for producing a charged beam exposure transmissive mask, characterized by comprising at least more than the (i) of (c) step.

Further, in a method of manufacturing a charged mask for light transmission mask, in which a through hole and a conductive layer having a predetermined pattern shape and arrangement are provided in the plane of the substrate, (a) the structure of the charged mask exposure mask is provided. A step of selectively removing an in-plane portion of the Si substrate by etching to a depth in the middle of the thickness of the substrate; (b) using SiN having resistance to a liquid capable of etching the substrate; (C) a step of covering the surface on the same side as the above to form a thin film for stopping etching, and covering the surface on the opposite side of the substrate selectively leaving an opening pattern to form a protective film for etching; Etching the substrate from the opening pattern on the opposite side until the etching stop thin film is reached; (d) forming a conductive layer on the structure of the transmission mask for charged beam exposure When a method for producing a charged beam exposure transmissive mask, characterized by comprising at least more than the (i) of (d) step.

[0008] In particular, when a single crystal of Si is selected as a substrate, the property of etching anisotropy caused by its crystallinity can be utilized in a manufacturing process. Can be easily formed by etching. In addition, when the Si single crystal substrate is a silicon wafer that is often used particularly in the manufacture of semiconductor integrated circuits, since there are particularly few defects, it is difficult to form a fine through-hole through which a charged beam is transmitted. This is convenient because it makes it easy to make expensive ones.

Hereinafter, the present invention will be described in more detail with reference to the drawings. First, FIG. 1 is a sectional view showing one embodiment of a method of manufacturing a transmission mask according to the present invention in the order of steps. A resist is applied to the surface of an Si substrate such as a silicon wafer, and a resist pattern is formed on a portion of the transmission mask, which is to be a transmission hole for a charged beam, by ordinary photolithography or electron beam lithography (FIG. 1A). Next, using the resist pattern as a mask, S
The i-substrate is etched by an amount equal to the depth of a predetermined transmission hole by means such as reactive ion etching, and then the resist pattern is peeled off to form a Si pattern on a surface of the Si substrate, which becomes a transmission hole of a charged beam. (FIG. 2B).

Next, the entire surface of the Si substrate on which the transmission hole is formed is covered with a thin film. The film forming method is not particularly limited,
For example, the use of a low pressure CVD method is convenient because the entire surface can be coated at once. The material of the thin film here is
In the subsequent step of etching from the rear surface side of the Si substrate, a material having an etching rate sufficiently lower than that of Si or having a property of not being etched is used. (Figure (c)).

Then, a resist is applied to the opposite surface of the Si substrate, and an opening is formed in a portion to be an opening (through hole) of the transmission mask by means of photolithography (which may be ultraviolet rays, electron beams or other electromagnetic waves). A resist pattern is formed. Then, the thin film is etched using the resist pattern as a mask. At this time, as a matter of course, an etching method may be used by selecting a means which has an etching property for the thin film material and a resist pattern is not etched (or extremely hardly etched). Thereafter, the resist pattern is peeled off (by means such as reactive ion etching) to form an opening pattern for etching protection of the Si substrate (FIG. 4D).

Next, the Si substrate is etched with a KOH aqueous solution or the like using the thin film portion of the etching protection opening pattern as an etching mask. Then, the etching of the portion facing the transmission hole is performed by selecting an etching stop thin film formed on the bottom of the transmission hole (in advance, selecting a material whose etching rate is sufficiently lower than Si or which is not etched at all). When the film reaches the formed thin film), it stops in a self-aligned manner, and only the thin film remains in the transmission hole portion (FIG. 9E).

When the etching of the portion facing the transmission hole is stopped, the etching of the Si substrate with the KOH aqueous solution or the like is completed. Thereafter, by removing the thin film remaining in the transmission hole portion, a desired transmission mask structure can be obtained. (FIG. 6F) When the thin film is an insulating film such as a SiN film, a conductive layer is formed after removing the thin film on the surface of the mask structure as usual, in order to prevent electrification. I do. Also, as described later, when the thin film has conductivity, it is not necessary to dare to form a conductive layer separately.

FIG. 2 is a cross-sectional view showing a transmission mask of another embodiment according to the manufacturing method according to the present invention.

A transmission mask for charged beam exposure according to the present invention is completed in substantially the same manner as in FIG. 1. However, unlike the process described with reference to FIG. 1, a thin film covering the entire surface of a Si substrate having a transmission hole formed therein. Is a conductive thin film such as a SiC film or a metal film, there is no need to remove and form a conductive layer as shown in FIG. 1F, and the thin film may be left on the surface of the Si substrate.

Further, when coating the surface of the Si substrate on which the transmission hole portion is formed with a thin film, it may be difficult to simultaneously cover the front and back surfaces depending on the film formation method. After that, the back side may be separately coated as an etching mask layer of the Si substrate. In this case, the thin films coated on the front and back sides do not necessarily need to be the same type of thin film.

[0017]

According to the manufacturing method of the present invention, an etching stop layer is formed on a Si substrate after first forming a pattern to be a transmission hole on the surface of the (Si) substrate. For this reason, the bonding step, which was conventionally required and required a long manufacturing time and a great deal of labor, is not required, and the polishing step of the upper and lower Si substrates required for bonding is also omitted. You can do it. As a result, the number of steps and the manufacturing time can be significantly reduced. In addition to this, since the manufacturing becomes easy, it leads to the improvement of the yield.

[0018]

<Example 1> A positive photoresist MP1400 was formed on the surface of a Si wafer substrate having a diameter of 3 inches and a thickness of 500 μm and a plane orientation of <100>.
Was spin-coated by 5 μm, and a transmission hole pattern on a photomask was transferred and formed by known photolithography. At this time, the exposure dose of the g-line was 300 mJ / cm ² . Next, the Si substrate was etched to a depth of 20 μm by an ECR (Electron Cyclotron Resonance) ion beam etching apparatus using the resist pattern as a mask.
At this time, the etching gas used was a mixture of Cl ₂ and SF ₆ added at 10%, and the microwave output was 200 W.
Thereafter, the resist was removed by O ₂ plasma to form a Si pattern to be a transmission hole on the surface of the Si substrate.

Next, the Si substrate on which the through-hole pattern was formed was placed in a low-pressure CVD apparatus, and a 1000 ° -thick SiCx film was formed on the entire surface of the Si substrate using C ₂ H ₂ and SiH ₂ Cl ₂ as source gases. . Thereafter, an opening pattern is formed on the back side of the Si substrate by ordinary photolithography, and RIE is performed using the resist pattern as a mask.
After etching the backside SiCx film by (reactive ion etching), the resist was removed to form an etching protection opening pattern of the Si substrate made of the SiCx film.

Next, the Si substrate is etched with a 30% KOH aqueous solution at a liquid temperature of 90 ° C. using the etching protection opening pattern as a mask.
The membrane was formed while leaving only the iCNx film. Thereafter, the SiCx film remaining in the transmission hole was removed while performing cleaning, thereby completing the transmission mask shown in FIG.

<Example 2> First, a Si pattern to be a transmission hole was formed on the surface of a Si wafer substrate having the same specifications as in Example 1 by the same method as in Example 1. Thereafter, the Si substrate was placed in an electron beam heating vapor deposition apparatus, and a 1000-Å-thick Au film was formed on the surface of the through-hole pattern side. Example 1 After forming an SiNx film having a thickness of 1000 ° on the back surface of the Si substrate by sputtering,
An opening pattern for etching protection of a Si substrate made of a SiNx film was formed in the same manner as described above.

Next, 50% hydrazine (N _{2) at a} liquid temperature of 110 ° C. is used by using the etching protection opening pattern as a mask.
The Si substrate was etched with an H ₄ ) aqueous solution. The hydrazine aqueous solution anisotropically etches Si as in the case of the KOH aqueous solution, but unlike the KOH aqueous solution, the thin film of Au is hardly etched, so that it was possible to form a membrane while leaving only the Au film in the through-hole portion. Thereafter, the Au film remaining in the transmission hole was removed while performing cleaning, thereby completing the transmission mask.

When the edge shape of the transmission hole of the transmission mask according to <Example 1> and <Example 2> was inspected with an electron microscope, it was found that the transmission hole was covered with the thin film and the conventional technology was used. As described above, there is little jagged edge caused by a minute edge along the surface of single crystal Si. As for the conductivity, a better result was obtained as compared with the conventional technique because the surface area covered with the conductive film was wider and the insulating film was not included in the middle. And good thing was obtained as well as dimensional accuracy and hole shape. In addition, the manufacturing method is simpler than that of the related art, and has led to a reduction in time. As a whole, the manufacturing time was short, the number of steps was small, and a high-quality transmission mask could be easily and stably manufactured.

[0024]

As described above, according to the method for manufacturing a transmission mask according to the present invention, after a pattern portion serving as a transmission hole is first formed on the surface of a Si substrate, an etching stop layer of the Si substrate is formed. Since the bonding is performed, the bonding step that has been conventionally required is not required, and therefore, the polishing step of the upper and lower Si substrates for bonding can be omitted. The laminating step and the polishing step not only require a long manufacturing time but also increase the number of steps, and are troublesome, which also causes a reduction in yield. Further, depending on the film formation method, the etching stop layer and the etching mask layer of the Si substrate can be simultaneously formed, or if a conductive film is used as the etching stop layer, the formation of a new conductive layer becomes unnecessary. come.

As a result, it is possible to greatly reduce the number of steps and the manufacturing time, thereby greatly improving the yield and reducing the production cost. As a result, it is possible to easily and stably manufacture a transmission mask having a smaller number of manufacturing steps, a shorter required manufacturing time and a higher yield than before.
That is, it was possible to provide a method of manufacturing a transmission mask capable of exhibiting high productivity in its manufacture.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a step of a method of manufacturing a transmission mask according to the present invention in the order of steps using cross-sectional views.

FIG. 2 is an explanatory view showing another embodiment of the method of manufacturing a transmission mask according to the present invention in the order of steps using cross-sectional views.

FIG. 3 is an explanatory view showing an example of a method of manufacturing a transmission mask according to a conventional technique in the order of steps using cross-sectional views.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Silicon substrate 2 ... Resist pattern 3 ... Transmission hole part 4 ... Thin film 4 '... Etching stop layer 5 ... Opening pattern 6 ... Transmission mask structure 7 ... Conductive layer 8: Supporting silicon substrate 9: Upper silicon substrate 10: Insulating layer 11: Bonded silicon substrate 12: Mask layer 13: Opening pattern 14: Transmission hole 14 '... Transmission hole 15 ... Opening 16 ... Conductive layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-109608 (JP, A) JP-A-4-106923 (JP, A) JP-A-62-276621 (JP, A) JP-A-62 106625 (JP, A) JP-A-4-137520 (JP, A) JP-A-6-37000 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 1 / 16

Claims (2)

(57) [Claims] 1. A method for manufacturing a charged mask for transmitting a charged beam, comprising: providing a through-hole having a predetermined pattern and arrangement in a plane of a substrate and a conductive thin film ; Si
A step of selectively removing the surface of the substrate by etching to an intermediate depth of the substrate thickness; (b) having a resistance to a liquid capable of etching the substrate;
Using SiC or gold , at least the same surface side of the substrate as described above covers the surface to form an etching stop thin film,
And (c) etching the substrate from the opening pattern on the opposite side of the substrate by covering the surface on the opposite side of the substrate selectively leaving an opening pattern to form a protective film for etching. A method of manufacturing a transmission mask for charged beam exposure, comprising: performing etching until the etching stop thin film is reached; and at least the above steps (a) to (c). 2. A predetermined pattern shape and arrangement in a plane of a substrate.
Beam mask with charged through-hole and conductive layer
In the method of manufacturing a mask , (a) Si as a structure of a transmission mask for charged beam exposure
Selective in-plane with respect to the substrate
Having in the step of etching away, resistance to etching possible solution to (b) the substrate
At least the same surface side of the substrate as described above using SiN
Is coated on the surface to form a thin film for stopping etching.
The other side covers the surface, leaving the opening pattern selectively
The step of the etching protection film to the substrate through the opening pattern (c) the reflected face of the substrate
Etch until the etch stop thin film is reached.
(D) Applying a conductive layer to the structure of the transmission mask for charged beam exposure
Forming, having at least the above steps (a) to (d).
Production side of the charged beam exposure transmissive mask, wherein bets
Law.