JPH04196209A - Formation of stencil mask - Google Patents

Abstract

PURPOSE:To obtain the formation method of a stencil mask for electron-beam reduction and transcription lithography use by a method wherein, after an insulating film on the rear of a silicon substrate has been removed selectively, the silicon substrate is removed selectively by making use of the insulating film as a mask. CONSTITUTION:An inorganic resist film 12 is deposited on a silicon substrate 11; a pattern is formed on the inorganic resist film 12 by using a photolithographic technique. Then, a silicon oxide film 13 is deposited on the rear of the silicon substrate 11; the silicon oxide film 13 is removed selectively by using a photo- lithographic technique and a dry etching technique. The silicon substrate 11 is dissolved and removed by using a solution while the silicon oxide film 13 which has been removed selectively is used as a mask; it is possible to form a stencil mask which uses the inorganic resist film 12 for a mask stencil as it is. Thereby, the inorganic resist film on which the pattern has been formed can be used for the mask material as it is, and the process to form the stencil mask for electron-beam reduction and transcription use is simplified.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to electron beam lithography technology for microfabrication of semiconductor devices, and particularly relates to a base stencil mask in reduction transfer type electron beam lithography using a stencil mask. This relates to a forming method.

Conventional technology Electron beam lithography technology (e.g., electron beam lithography technology) is used as a tool for advanced development of LSIs because it does not require the use of a reticle and can form fine patterns.

Conventionally, the widely used electron beam writing method (i) is a method in which patterns are drawn one by one using a Gaussian beam or a variable shaped beam using a field emission type or thermionic type electron gun, and is a so-called -brush drawing method. This method is called a writing method.By focusing the electron beam generated from the electron gun into a narrow beam spot on the resist surface using a focusing lens and then controlling the position of the beam spot using a deflection system, an arbitrary figure can be created on the resist. is a method that can be drawn.

This method has the advantage that distortion and aberration inside the deflection field can be corrected electrically, and accuracy can be improved depending on the control technology, and many developments have been made and it has been put into practical use.However, on the other hand, In this method, the spot diameter of the electron beam is approximately 0.1 to 2 μm, so the size of the pattern to be drawn becomes small, and the number of spots to be drawn becomes enormous.Also, due to the limit of the operating frequency of the deflection system, The disadvantage is that there is a limit to the spot movement speed, the time required for drawing becomes very long, and the throughput decreases.

So-Q Recently, to solve these drawbacks, LSI
Instead of drawing the entire chip pattern like a brush stroke, a reduction transfer method was devised in which a partial pattern is transferred using a mask. This method involves breaking down the pattern into partial patterns, forming this pattern on a stencil mask, and sequentially transferring the pattern using this mask. However, it is expected that the throughput of this method will be very fast.The stencil mask used is very difficult to form. For example, an example of the currently considered stencil mask forming method is shown in FIG. An accelerating voltage of 50 KV and a dose of lXl0'' are applied to the semiconductor silicon substrate 11.
Boron ions 52 are implanted at 1.cm-'. % ion implantation layer 51 is formed (FIG. 5(a)). A silicon shrimp layer 53 is formed on this, and a nitride film is further deposited as a protective film 54 on the shrimp layer and on the back surface of the silicon substrate (FIG. 5(b)). After that, the silicon oxide film on the back side of the silicon substrate is selectively removed using lithography technology and dry etching technology. Using the silicon oxide film as a mask, the back side of the silicon substrate is coated with an ethylenediamine-pyrocatechol solution up to the boron implanted layer. (Fig. 5(C)). A resist pattern 55 is formed on the shrimp layer using electron beam lithography (FIG. 5(d)). Using this resist pattern as a mask, the shrimp layer and the ion-implanted layer are etched (to form a mask pattern (Fig. 5(e)). By the above method, a stencil mask used in electron beam reduction transfer lithography is formed. However, in this way (!.

Since it is necessary to form a mask that blocks the electron beam using only the silicon ion-implanted layer and the shrimp layer, the mask film thickness is several tens of micrometers or more, and etching is not easy.

Problems to be Solved by the Invention As mentioned above, when only silicon material is used in a stencil mask used in electron beam reduction transfer lithography, the acceleration voltage is usually 20 to 50 KV. Etching a silicon film with a thickness of several tens of micrometers or more is extremely difficult, and requires many steps such as ion implantation, epitaxial techniques, lithography, and etching. However, there is a drawback that the process of creating a stencil mask becomes complicated.

Present invention 4 This invention solves the above problems, and aims to provide a method for forming a stencil mask for electron beam reduction transfer lithography.

Means for Solving the Problems The present invention comprises a step of depositing an inorganic resist film on the surface of a silicon substrate, a step of forming a pattern on the inorganic resist film by lithography technology, and a step of depositing an insulating film on the back surface of the silicon substrate. and a step of selectively removing the insulating film using a lithography technique, and then selectively removing the silicon substrate using the insulating film as a mask. It is something to do. Furthermore, the present invention also includes a step of depositing an inorganic resist film on the surface of a silicon substrate, a step of forming a pattern on the inorganic resist film by lithography technology, a step of electroplating a metal using the inorganic resist film as an electrode, and a step of electroplating a metal using the inorganic resist film as an electrode. a step of depositing an insulating film on the back surface of a silicon substrate; and a step of selectively removing the insulating film using a lithography technique, and then selectively removing the silicon substrate using the selectively removed insulating film as a mask. The present invention also provides a stencil mask forming method characterized by comprising:
A step of depositing an inorganic resist film on the surface of a silicon substrate, a step of depositing a metal thin film on the inorganic resist film, and a step of exposing a pattern to the metal thin film using lithography technology to form a metal in the inorganic resist film. a step of photodoping, a step of removing the metal thin film and forming a pattern on the inorganic resist film, a step of depositing an insulating film on the back surface of the silicon substrate, and selectively removing the insulating film by lithography technology. and a step of selectively removing the silicon substrate using the insulating film as a mask.Furthermore, the present invention provides a method for forming a stencil mask.
a step of depositing an oxide film on a silicon substrate, a step of depositing an inorganic resist film on the deposited oxide film, a step of forming a pattern on the inorganic resist film by lithography technology, and a step of using the inorganic resist film as a mask. After etching the oxide film, depositing an insulating film on the back surface of the silicon substrate, and selectively removing the insulating film by lithography, the silicon substrate is etched using the insulating film as a mask. The present invention provides a stencil mask forming method characterized by comprising a step of selectively removing the stencil mask.

Effects of the Invention The stencil mask forming process described above simplifies the process of forming a stencil mask for electron beam reduction transfer by using an inorganic resist film patterned by lithography as a mask material as it is. The stencil mask is made of a metal with a higher mass number than silicon.Even if the film thickness of the stencil mask is made thinner, it can sufficiently block the electron beam.

Moreover, the present invention simplifies the process of forming a stencil mask for electron beam reduction transfer by using the above-described stencil mask forming process as a mask material using an inorganic resist film that is patterned by lithography technology and then electroplated. Also, if gold or silver is used as the electroplating metal, the electron stopping power will be increased, and the electron beam can be blocked sufficiently, and the electrical conductivity will be high, so beam distortion due to charge-up will not occur.

Additionally, the present invention (as described above) simplifies the process of forming a stencil mask for electron beam reduction transfer by using an inorganic resist film patterned by photodoping metal using lithography technology as a mask material. When several tens of percent of a metal with a large mass number, such as gold or silver, is diffused by photodoping, the electron stopping power increases and the electron beam can be sufficiently blocked. Through the stencil mask forming process, the inorganic cyst patterned using lithography technology and the etched oxide film can be used as mask materials.
The process of forming a stencil mask for electron beam reduction transfer is simplified, and the thickness can be increased by the thickness of the silicon oxide film, resulting in an increase in mechanical strength. Shown below. Silicon substrate 1
A 5e-Ge inorganic resist film 12 was deposited on the substrate 1 to a thickness of about 7 μm (FIG. 1(a)). A pattern was formed on the inorganic resist film 12 using photolithography technology (FIG. 1(b)). A 1 μm thick silicon oxide film 13 was deposited on the back surface ζQ of the silicon substrate II (FIG. 1(C)). Using photolithography and dry etching techniques, the silicon oxide film 13 is selectively removed. Using the selectively removed silicon oxide film 13 as a mask, the silicon substrate 1 is etched using an ethylenediamine-pyrocatechol solution.
1 was dissolved and removed, and a stencil mask was formed using the inorganic resist film 12 as it was as a mask material (see Figure 1 (
d)).

As described above, according to this example, by using the inorganic resist film patterned using photolithography technology as the mask material, the stencil mask creation process is greatly simplified. Force using photolithography technology for pattern formation＼ Electron beam lithography technology may be used.

A second embodiment of the present invention is shown in FIG. 2, in which a silicon nitride film may be used instead of a silicon oxide film as a mask for etching the back surface of a silicon substrate. Silicon substrate 1
1, a GQSe-Ge inorganic resist film 12 was deposited to a thickness of about 3 μm (FIG. 2(a)). A pattern was formed on the inorganic resist film 12 using photolithography technology (FIG. 2(b)). Gold was electroplated using the patterned inorganic resist film as an electrode to form an electroplated layer 21 with a thickness of 3 μm on the inorganic resist film (Figure 2 (C)).
.

Silicon oxide film 13 is 1 μm thick on the back side of silicon substrate 11.
m was deposited (Fig. 2(d)). Using photolithography and dry etching techniques, the silicon oxide film 13 is selectively removed. Using the selectively removed silicon oxide film 13 as a mask, the silicon substrate 11 is etched using an ethylenediamine-pyrocatechol solution. A stencil mask was formed using the inorganic resist film electroplated with gold as the mask material (FIG. 2(e)).

As described above, according to this embodiment, by using an inorganic resist film patterned using photolithography technology and electroplated with gold as the mask material, the process of creating a stencil mask can be greatly simplified. Gold has a large electron blocking ability, so even if the thickness of the inorganic resist film is made thinner, it may not be possible to block the electron beam sufficiently.Here, photolithography technology is used to pattern the inorganic resist. (Electron beam lithography technology may also be used. Also, here we will use a silicon oxide film as a mask for etching the back side of the silicon substrate.
A silicon nitride film may be used, or gold may be used for electroplating (other metals may also be used).

A third embodiment of the invention is shown in FIG. Silicon substrate 1
A 5e-Ge inorganic resist film 12 of approximately 5 μm thickness was deposited on the 5e-Ge inorganic resist film 12, and a thin silver film 31 was deposited thereon (Fig. 3(a)).
. A pattern was exposed using a photolithography technique to diffuse several tens of percent of silver into the inorganic resist film in the exposed area, thereby forming a photodoped layer 32 (FIG. 3(b)). The silver thin film 31 was removed using an acid, and the inorganic resist film that was not photodoped was removed using an alkaline solution (FIG. 3(C)). A silicon oxide film 13 having a thickness of 1 μm was deposited on the back surface of the silicon substrate 11 (FIG. 3(d)). Using photolithography and dry etching techniques, the silicon oxide film 13 is selectively removed. Using the selectively removed silicon oxide film 13 as a mask, the silicon substrate 11 is etched using an ethylenediamine-pyrocatechol solution.
A stencil mask was formed using the inorganic resist film photodoped with silver as a mask material (FIG. 3(e)).

As described above (2) According to this embodiment, the stencil mask creation process is greatly simplified by using the inorganic resist film that is patterned using photolithography technology and photodoped with silver as the mask material. Since silver having a large mass number is diffused at a concentration of several tens of percent, the electron blocking ability becomes large, and even if the thickness of the inorganic resist film is made thin, it is possible to sufficiently block the electron beam.

Here, we will discuss the power of using photolithography technology to pattern an inorganic resist (electron beam lithography technology may also be used. Also, here we will discuss the power of using a silicon oxide film as a mask for etching the back side of a silicon substrate.
A silicon nitride film may also be used. Also, here we used silver for photodoping (other metals may also be used).

A fourth embodiment of the invention is shown in FIG. Silicon substrate 1
A silicon oxide film 41 was deposited to a thickness of IO .mu.m on top of the silicon oxide film 41, and a 5e-Ge inorganic resist film 12 was deposited to a thickness of about 3 .mu.m thereon (FIG. 4(a)). A pattern was formed on the inorganic resist film 12 using a photolithography technique (FIG. 4(b)).

Using the patterned inorganic resist as a mask, the silicon oxide film 41 was etched (FIG. 4(C)). A silicon oxide film 13 having a thickness of 1 μm was deposited on the back surface of the silicon substrate 11 (FIG. 4(d)). The silicon oxide film 13 is etched using photolithography and dry etching techniques.
(9) Using the selectively removed silicon oxide film 13 as a mask, the silicon substrate 11 is dissolved and removed using an ethylenediamine/pyrocatechol solution.
I wanted to be able to form a stencil mask using the silicon oxide film 41 and the inorganic resist film 12 as mask materials.
Figure (e)).

As described above, according to this embodiment, the stencil mask creation process is greatly simplified by using the inorganic resist film and silicon oxide film patterned using photolithography technology as mask materials as they are. The mechanical strength of the mask can be increased by the thickness of the mask.

In this example, photolithography technology was used to form a pattern on an inorganic resist. Electron beam lithography technology may also be used. Also, here is a sumo wrestler using silicon oxide film as a mask for etching the back side of a silicon substrate. Silicon nitride film. According to the present invention, an inorganic resist film patterned by lithography technology is directly used as a mask material.However, the process of forming a mask can be simplified, and the inorganic resist is silicon. Even if the film thickness of the stencil mask is made thinner, it can sufficiently block the electron beam.
It acts as a stencil mask for electron beam reduction transfer lithography and can greatly contribute to the production of ultra-high density integrated circuits. Furthermore, the present invention simplifies the process of forming a mask by using an inorganic resist film, which is patterned by lithography technology and then electroplated with metal, as a mask material. In addition, if the metal to be electroplated is a metal with a large mass number and high electrical conductivity, the electron blocking ability will also increase, and even if the inorganic resist film is thin, it will be able to sufficiently block the electron beam, and the Since distortion can be suppressed, it can also act as a stencil mask for electron beam reduction transfer lithography, greatly contributing to the production of ultra-high density integrated circuits. Furthermore, the present invention simplifies the process of forming a mask by using as a mask material an inorganic resist film patterned by photodoping metal using lithography technology. When several tens of percent of metals with large mass numbers, such as gold and silver, are diffused by photodoping, the electron stopping power increases, and even if the inorganic resist film is made thinner, it can sufficiently block the electron beam, reducing the electron beam. Although it can act as a stencil mask for transfer lithography and greatly contribute to the production of ultra-high density integrated circuits, the inorganic resist patterned by lithography technology and the etched oxide film can be used as mask materials as they are. The mask formation process is simplified and the mask can be made thicker by the thickness of the silicon oxide film, increasing its mechanical strength and acting as a stencil mask for electron beam reduction transfer lithography, which can be used to manufacture ultra-high-density integrated circuits. can make a big contribution

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the stencil mask forming process of the first embodiment of the present invention. Figure 2 is a cross-sectional view of the process of the second embodiment. Figure 3 is a cross-sectional view of the process of the third embodiment. is a cross-sectional view of the process of the fourth embodiment. FIG. 5 is a cross-sectional view of the conventional stencil mask forming process. ...Electric Metsukiou 3
1... Silver thin WL 32... Photodoping 凰 33
...Light 41...Silicon oxidation [51...Ion implantation 52...Boron ion, 53...Shrimp#
54...Protective wind 55...Resist pattern. Name of agent: Patent attorney Akira Okaji and two others Figure 1 Figure 2 Figure 3 Figure 4

Claims (4)

[Claims] (1) A step of depositing an inorganic resist film on the surface of the silicon substrate, a step of forming a pattern on the inorganic resist film using lithography technology, a step of depositing an insulating film on the back surface of the silicon substrate, and a step of depositing the inorganic resist film on the back surface of the silicon substrate. A method for forming a stencil mask, comprising the steps of selectively removing the silicon substrate using a lithography technique, and then selectively removing the silicon substrate using the insulating film as a mask. (2) a step of depositing an inorganic resist film on the surface of the silicon substrate; a step of forming a pattern on the inorganic resist film by lithography; a step of electroplating a metal using the inorganic resist film as an electrode; and a step of electroplating a metal on the silicon substrate. a step of depositing an insulating film on the back surface of the silicon substrate; and a step of selectively removing the insulating film using a lithography technique, and then selectively removing the silicon substrate using the insulating film as a mask. A method for forming a stencil mask. (3) A step of depositing an inorganic resist film on the surface of a silicon substrate, a step of depositing a metal thin film on the inorganic resist film, and a step of exposing a pattern to the metal thin film using lithography technology to form a pattern in the inorganic resist film. A step of photodoping a metal, a step of removing the metal thin film and forming a pattern on the inorganic resist film, a step of depositing an insulating film on the back surface of the silicon substrate, and selectively depositing the insulating film using a lithography technique. and then selectively removing the silicon substrate using the insulating film as a mask. (4) a step of depositing an oxide film on a silicon substrate; a step of depositing an inorganic resist film on the deposited oxide film;
a step of forming a pattern on the inorganic resist film using a lithography technique; a step of etching the oxide film using the inorganic resist film as a mask; a step of depositing an insulating film on the back surface of the silicon substrate; A method for forming a stencil mask, comprising the steps of selectively removing the silicon substrate using a lithography technique, and then selectively removing the silicon substrate using the insulating film as a mask.