Kei Kasuya

Improvement of post-exposure delay stability of chemically amplified positive resist

We have been developing a novolak-based chemically amplified positive resist for next generation photomask (below 0.18 micrometer) fabrication. This resist prevents footing profile by use of a hydrophilic polyphenol compound. We succeeded in improving PED and PCD stability by addition of an ion- dissociative compound. We obtained vertical resist profiles on a chromium-oxide (CrOx) substrate. With the resist, we could make a well defined 0.25 micrometer line-and-space patterns on a CrOx substrate at a dose of 4.0 uC/cm2. Under the ambient air (amines concentration: 4 ppb, humidity: 45%), the line width change was less than 10 nm when the delay time between EB exposure and post-exposure-baking was from 0 to 8 hours. Under the same condition, the line width change was less than 20 nm even when the post-coating delay (PCD) time was 7 days.

Chemically amplified positive resist for next-generation photomask fabrication

We have been developing novolak-based chemically amplified positive resists for the next generation photomask fabrication. In this paper, we report two different types of EB resists: RE-5150P and RE-5160P. Our resist materials consist of four components: a novolak matrix resin, a polyphenol compound, an acid generator and a dissolution inhibitor. We applied two different types of dissolution inhibitors to our resist materials. RE-5150P and RE-5160P employed respective a high and a low activation energy type of a dissolution inhibitor. RE-5150P has high contrast and RE- 5160P has wide process window. As a result, we confirmed RE- 5150P could achieve 0.24 micrometer line-and-space vertical resist pattern profiles at 8 (mu) C/cm2 using the 50 kV EB- writer HL-800M, and RE-5160P has wide process window: post exposure delay stability is over 24 hrs. and post coating delay stability is over 30 days.

Acid-breakable-resin-based chemical amplification positive resist for 0.1-μm-rule reticle fabrication: design and lithographic performance

We have designed a new chemical amplification (CA) positive resist for 0.1micrometers reticle fabrication. This positive resist consists of an acid-generator, an acid-diffusion controller, and an acid-breakable (AB) resin that can be converted to initial polyphenol units by an acid-catalyzed reaction. In the exposed region, main-chain scission of the AB resin matrix produces nearly mono-dispersed fragments (the polyphenol). This complete fragmentation results in an extremely high dissolution rate with an aqueous-base developer (tetramethylammonium hydroxide: 2.38 wt%). The AB resin-based resist enabled fabrication of scum free 0.15micrometers line-and-space patterns on a CrOx plate by using a 50-kV electron-beam reticle writer (HL series). The line- edge roughness of patterns delineated by this resist (<10 nm) was less than half that for previously developed novolak-resin-based CA resists (RE series:>30nm).

Improvement of the resolution and accuracy of chemical-amplification positive resist for 0.13-μm reticle fabrication

We have developed a novolak-based chemical-amplification resist for 0.13-micrometers or later reticle fabrication. For the 0.13-micrometers or later design-rule reticle-fabrication with OPC patterns, the resist resolution is required under 0.2-micrometers on the mask substrate. To improve the chemical-amplification resist resolution, it is necessary to control the acid- diffusion in the resist film. We have developed the technique of the acid-diffusion control with neutral-salt additives. By use of the resist with this technique, we could fabricate 0.14-micrometers 1/s patterns on a CrOx substrate at a dose of 9.3-(mu) C/cm2. The resist has a good margin of doses.