JPS61270761A - Mask for forming pattern - Google Patents

Abstract

PURPOSE:To enable use of a photomask for a long period by forming a diamond-like carbon film as a surface protective layer. CONSTITUTION:After the photomask or an X-ray mask has been prepared, the diamond-like carbon film is formed on its surface by the CVD process including the plasma process and plasma injection process and the like, the ionization vapor deposition process, or the reactive ion sputtering process, or the like to obtain the surface protective layer, thus permitting the obtained carbon film to be high in hardness, chemically stable, and good in heat conductivity and electric characteristics, and this photomask to be used for a long period.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the use of KSiO, such as high-purity synthetic quartz.
! 7. Transparent glass substrate having as main component It relates to so-called photomasks and the like on which a thin film pattern is formed.

[Prior art]

Conventionally, photomasks of this kind have been used which have a transparent glass base and mainly use pure zero material as a thin film pattern.

However, looking at the recent situation, with the increasing integration of LSIs, there is an increasing demand for photomasks with high resolution, high precision, and fewer defects. The reality is that the mask is not technically compatible with this. In other words, the conventional photomask substrate is 510x, with At snow Qs as the main component, and R
Saponified divalent metals represented by O and Rho (CaO,
MgO, etc.) and monovalent metal oxides (Nag O# Ks
The so-called blue plate, white plate, or so-called low-expansion glass containing a large amount of RO (O, etc.), or the so-called low-expansion glass containing a large amount of RO, and the thermal expansion coefficient further increases. A small high-purity synthetic quartz substrate is used.

On the other hand, when looking at exposure equipment, conventionally, mainly
Since low-integration ICs with wide processing line widths were the mainstream, 1
:1 contact exposure and 1:1 four-section exposure were mainly used, so the components used as the master reticle,
The method used was to duplicate a large number of working masks and perform actual work.
After 7th, reticules with a value of There are many cases where K
For example, if we look at photomasks, for example, the number of high-precision and expensive photomasks that can be used for long periods of time without damaging them is becoming much smaller due to yield issues. It has become an important issue to do so.

[Problem that the invention seeks to solve]

However, as mentioned above, conventional photomask substrates are mainly white plates, blue plates, low expansion glass, or synthetic quartz substrates, and these substrates have a hardness of about 530 to 540 kg/kg for blue plates and white plates. wJ, 65 with low expansion glass
0 kVi level 2 synthetic quartz has a value of 620~, which is not necessarily sufficient, and the patterned film such as G formed on this surface has problems with hardness and adhesion with the substrate, and is susceptible to external factors and electricity. It has the major drawback of being extremely susceptible to scratches due to various factors.

Therefore, if an extremely thin film can be formed to protect the photomask, the life of the photomask can be greatly extended. However, as is well known, photomask substrates need to efficiently transmit light with shorter wavelengths, such as ultraviolet light, in order to increase the degree of integration of ICs. The reality is that protective films have traditionally not been formed well.

In addition to photomasks, an exposure method that uses X-rays, which are electromagnetic waves with significantly shorter wavelengths, is currently being considered. The pattern is usually made of heavy metal such as Au*Tu, and there are very large cases where the pattern is damaged by external or electrical factors.
In the case of an X-ray mask, 1:1 pro-chip exposure is generally used, and the pattern accuracy of the mask itself is extremely high.
The problem is serious.

The present invention provides a new method to overcome these shortcomings of the prior art.

[Means for solving problems]

That is, the present invention is characterized by forming a diamond-like carbon film on its surface, which has high transmittance to exposure light or exposure X-rays and has excellent protective functions such as hardness, and serves as a protective film. A pattern forming mask is provided.

Diamond-like carbon film has high hardness, usually 1001
There are more than 0001q, and the maximum is 10,000 keys
It can also be made to exceed -, making it ideal as a protective film in terms of mechanical strength. In addition, it has excellent chemical stability, good thermal conductivity and electrical properties, and has a relatively low density. It also has excellent transparency to ultraviolet light, making it ideal as a protective film for photomasks and X-ray masks.

In carrying out the present invention, a photomask or an X-ray mask is created by a conventional method, and then the surface of the mask is coated with a c? It is possible to adopt a method that suits the substrate material and patterning material, such as by using the D method, or by applying a sputtering method such as ionized vapor deposition or reactive sputtering, and the thickness of the protective film can be adjusted. Although the thickness varies depending on the substrate, for example, in the case of a quartz substrate, it is possible to make it relatively thick to the order of μ, but normally a thinner one is sufficient.

Further, depending on the case, some conductivity may be imparted to the layer to serve as a protective layer. In this case, it is not only effective against mechanical damage, but also extremely effective against electrostatic damage.

Note that the protective layer does not necessarily have to be on the outermost surface;
In some cases, even if it is formed on a substrate and a pattern layer is formed thereon, a great effect can be obtained.

〔Example〕

The present invention and examples will be described below.

After making a photomask using a conventional method using blue plate, white plate, low expansion glass, and synthetic silica glass, diamond-like carbon is formed using a CvO method to a thickness of 0.2 μm as a protective film to prolong the life of the mask. compared.

That is, the lifespan was compared under the assumption of 1:1 contact exposure. Considering the relative lifespan of a white plate without a protective layer as 1, both blue plate, white plate, low expansion glass, and synthetic quartz glass currently have a life of 5 or more, and they are used without any problems.

As stated above, the present invention has an industrial effect through the procedure 1.
Seisho (@t) Showa 6 Rumor August 14EI

Claims (1)

[Claims] A pattern forming mask characterized by forming a diamond-like carbon film as a surface protective layer.