Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
Langmuir. 2012 Jan 10;28(1):1049-55. doi: 10.1021/la203661d. Epub 2011 Dec 2.
We present the results of large-scale molecular dynamics simulations of two different nanolithographic processes, step-flash imprint lithography (SFIL), and hot embossing. We insert rigid stamps into an entangled bead-spring polymer melt above the glass transition temperature. After equilibration, the polymer is then hardened in one of two ways, depending on the specific process to be modeled. For SFIL, we cross-link the polymer chains by introducing bonds between neighboring beads. To model hot embossing, we instead cool the melt to below the glass transition temperature. We then study the ability of these methods to retain features by removing the stamps, both with a zero-stress removal process in which stamp atoms are instantaneously deleted from the system as well as a more physical process in which the stamp is pulled from the hardened polymer at fixed velocity. We find that it is necessary to coat the stamp with an antifriction coating to achieve clean removal of the stamp. We further find that a high density of cross-links is necessary for good feature retention in the SFIL process. The hot embossing process results in good feature retention at all length scales studied as long as coated, low surface energy stamps are used.
我们呈现了两种不同纳米光刻工艺的大规模分子动力学模拟结果，即步进闪光压印光刻（SFIL）和热压印。我们将刚性印章插入玻璃化转变温度以上的缠结珠-簧聚合物熔体中。在平衡后，根据要模拟的特定过程，聚合物以两种方式之一硬化。对于 SFIL，我们通过在相邻珠之间引入键来交联聚合物链。为了模拟热压印，我们将熔体冷却到玻璃化转变温度以下。然后，我们研究了通过去除印章来保留特征的能力，包括零应力去除过程（其中印章原子立即从系统中删除）和更物理的过程（其中以固定速度从硬化聚合物中拉出印章）。我们发现有必要在印章上涂覆减摩涂层以实现印章的清洁去除。我们进一步发现，对于 SFIL 工艺，要获得良好的特征保留，需要有高密度的交联。只要使用涂覆有低表面能的印章，热压印工艺在所有研究的长度尺度上都能实现良好的特征保留。
