Abstract
The semiconductor industry is facing the transition from 300 mm to 450 mm wafer fabrication. Due to the increased size and weight, 450 mm wafers will pose unprecedented challenges on semiconductor wafer fabrication. To better handle and transport 450 mm wafers, an advanced Automated Material Handling System (AMHS) is definitely required. Though conveyor-based AMHS is expected to be suitable for 450 mm wafer fabrication, still it faces two main problems, traffic-jam problem and lot-prioritization. To address the two problems, in this research we have proposed an improved dispatching method, termed Heuristic Preemptive Dispatching Method using Activated Roller Belt (a-HPDB). We have developed some effective rules for the a-HPDB based on Activated Roller Belt (ARB). In addition, we have conducted experiments to investigate its effectiveness. Compared with the HPDB and R-HPD, two dispatching rules proposed in previous studies, our experimental results showed the a-HPDB had a better performance in terms of average lot delivery time (ALDT). For hot lots and normal lots, the a-HPDB had advantages of 4.14% and 8.92% over the HPDB and advantages of 4.89% and 8.52% over R-HPD, respectively.
Highlights
The semiconductor industry has experienced outstanding advancements over the past five decades
Leading semiconductor companies are undertaking their best efforts in the transition from 300 mm to 450 mm wafer fabrication, and they have achieved initial success
Though some researchers have found that conveyor-based Automated Material Handling System (AMHS) were suitable for 450 mm wafer transport, this kind of AMHSs remains to face the traffic-jam problem and the lot prioritization problem
Summary
The semiconductor industry has experienced outstanding advancements over the past five decades. One is technology advancement and another is wafer size increment [1]. Following the Moore’s rule, each of the wafer size transitions has nearly doubled the number of transistors in an IC chip [2]. The wafer size increments have led to the increase of IC dies. For the last transition of wafer size from 200 mm diameter to 300 mm diameter, the IC dies resulting from one wafer has been increased as much as 2.25 times [1], which has enhanced the productivity considerably. One essential part of the ARB is polyurethane rollers whose made of acetal. The diameter of these rollers is 22.3 mm and rollers are skewed either Appl. When these belt rollers are activated, products will move faster travel than the belt’s speed; otherwise, the product travels at the belt’s belt’s speed
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