Study on the Large-area Micro-Nano Imprinting using Soft Mold and Gas Pressure Mechanism
Date Issued
2004
Date
2004
Author(s)
Chao, Chi-Chung
DOI
zh-TW
Abstract
Abstract
This thesis is devoted to the development a system and process for large area micro-nano imprinting. Conventional molds for impriting are of Si-based, glass-base or electroplated metal-based. Poor contact is a common problem when such molds are used for replication, especially when the area is large. When the substrate and the mold are brought into contact and are compressed using conventional hot press, the accuracy and area of replication were limited due to the contact condition and the inherent non-uniform pressure distribution. Si-wafers are easily broken if imprinting area is very large. Besides, when the resist coated thickness is thin, the effective imprinting area is further limited.
In this study, the soft mold made of PDMS is used; Gas is used employed as pressuring media. Compared to Si-base and Ni-base molds using conventional hot-plate compressing, the contact condition between the PDMS mold and the substrate is much better, as demontrated in the image using a pressure film. Conformal contact and uniform imprinting pressure throughout the whole area can be achieved. This technique has great potential for effectively replicating micro-nano structures directly from large wafers. Furthermore, PDMS mold had low surface energy can anti-adhere to resist.
For developing the PDMS molds for gas-assited imprinting process, three studies have been carried out: (i) preventing distortion of the PDMS mold, (ii) understanding the replication capacity under different processing parameters, and (iii) evaluating the mold life. Results showed that using a holder to support PDMS mold can overcome distortion. The rigid outer holder should match the outward lateral geometry of the PDMS mold with a height equal to or less than that of the PDMS mold. Imprinting using a gas pressure between 10 to 100 kgf/cm2 and with imprinting time between 30 seconds to 5 minutes yields good replication; but different gas pressure will determine the final thickness of the residual layer of photo-resist. Imprinting temperature is found to depend upon the molecular weight of resist, usually they are 40~60℃above the Tg's of the resist. Mold life depends on the micro-features; it is shorter than molds made of other material.
The capacity of gas-assisted imprinting using PDMS molds for large-area micro-feature replications has been demonstrated in this study. Succesful replication of micro-features onto the photo-resists on flat 6-inch and 12-inch Si substrates and 2-inch curved surface have been achieved. The minimum critical dimension is about 300nm.
Subjects
氣體熱壓
奈米壓印
PDMS軟模
大面積壓印
gas hot em
nano imprinting
large-area imprinting
Type
thesis
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