2.5D and 3D applications using through silicon vias (TSVs) are increasingly being considered as an alternative to conventional packaging. Miniaturization and high performance product requirements are driving this move, although in many cases the cost of both 2.5D and 3D is still high. In this paper we will identify the major cost drivers for 2.5D and 3D packaging and assess cost reduction progress, including current costs versus expected future costs. We will also compare these costs to alternative packaging.

2.5D and 3D packaging can provide significant size and performance advantages over other packaging technologies. However, these advantages usually come at a high price. Since 2.5D and 3D packaging costs are significant, today they are only used if no other option can meet the product requirements, and most of these applications are relatively low volume. Products such as high end FPGAs, high performance GPUs, and high bandwidth memory are great applications but none have volume requirements close to mobile phones or tablets. Without the benefit of volume production, the cost of 2.5D and 3D packaging could stay high for a long time. In this paper, we will provide cost model results of a complete 2.5D and 3D manufacturing process. Each manufacturing activity will be included and the key cost drivers will be analyzed regarding future cost reductions. Expensive activities that are well down the learning curve (RDL creation, CMP, etc.) will probably not change much in the future. However, expensive activities that are new to this process (DRIE, temporary bond/debond, etc.) provide good opportunities for cost reduction. A variety of scenarios will be included to understand how design characteristics impact the cost. Understanding how and why the dominant cost components will change over time is critical to accurately predicting the future cost of 2.5D and 3D packaging.

Miniaturization and increased performance demands are driving the industry to explore 2.5D and 3D packaging. Although progress has been made in recent years, many barriers remain. One primary cost driver for 2.5D and 3D processes is the temporary bond and debond method used for thin wafer handling. Various solutions are appearing on the market, but there is not a single method taking the lead as the obvious best choice. Many factors must be considered when looking at the total cost of a thin wafer handling solution. In this paper, we will use cost modeling to carry out detailed cost and yield trade-offs for temporary bond and debond methods. Instead of concentrating on one proposed solution that is available on the market, we will analyze a range of solutions, focusing on variables such as tool cost, material cost, throughput, yield, and interposer cost. With this analysis, we will determine the most significant cost drivers within the temporary bond and debond process and propose process details for a reasonable solution.

Miniaturization and increased performance demands are driving the industry to explore 2.5D and 3D packaging. Although progress has been made in recent years, many barriers remain. One primary cost driver for 2.5D and 3D processes is the temporary bond and debond method used for thin wafer handling. Various solutions are appearing on the market, but there is not a single method taking the lead as the obvious best choice. Many factors must be considered when looking at the total cost of a thin wafer handling solution. In this paper, we will use cost modeling to carry out detailed cost and yield trade-offs for temporary bond and debond methods. Instead of concentrating on one proposed solution that is available on the market, we will analyze a range of solutions, focusing on variables such as tool cost, material cost, throughput, and yield. With this analysis, we will determine the most significant cost drivers within the temporary bond and debond process and propose process details for a reasonable solution.

When a product requires the bonding of two die or wafers, there are a number of methods that may be used. Not only does the type of bonding process itself have to be selected, but it must also be determined whether the items being bonded will be in wafer or die form. This paper will focus on wafer-to-wafer bonding, which has the highest throughput compared to die-to-wafer and die-to-die bonding; it also has the potential to be the lowest cost option if proper yields are achieved. This paper will introduce the background and general pros and cons of wafer-to-wafer, die-to-wafer, and die-to-die bonding. Activity based cost modeling will be used to construct a generic flow of a wafer-to-wafer bonding process. The process flow will be divided into a series of activities, and the total cost of each activity will be identified. The cost of each activity will be determined by analyzing the following attributes: time required, amount of labor required, cost of material required (consumable and permanent), tooling cost, depreciation cost of the equipment, and yield loss associated with the activity. The model will be used to explore multiple variables that affect the total cost of the wafer-to-wafer bonding process, including: incoming wafer cost, incoming wafer defect density, time required for the dicing process, time required for the bonding process, cost of the equipment for the bonding process, and the yield of the bonding process. First, a sensitivity analysis will be conducted to determine the impact each variable has on the total cost. Then scenarios will be created to conduct trade-offs between multiple variables. Only one, generic wafer-to-wafer bonding model will be created, but there will be enough variables to accurately reflect different bonding methods in use by the industry today. Methods for bonding two wafers together will also be discussed in the paper, as well as the cost and yield issues associated with each. An example of these methods are thermo compression bonding and direct bonding. The goal of this analysis will be to understand the cost and yield drivers associated with wafer-to-wafer bonding, and to determine scenarios in which wafer-to-wafer bonding is a suitable, cost effective technology selection.