Building a semiconductor fab, or fabrication plant, is a complex and expensive undertaking. It involves a wide range of specialized equipment and facilities, as well as a highly trained workforce. As such, there is no one-size-fits-all approach to building a semiconductor fab, and the cheapest way to do so will depend on a number of factors, including the specific semiconductor manufacturing process being used and the size and scale of the fab.

Here are some general steps that may be involved in building a semiconductor fab:

1. Develop a detailed plan for the fab, including the manufacturing processes that will be used, the equipment and facilities that will be needed, and the workforce that will be required.
2. Secure funding for the project, either through private investment or public funding sources.
3. Acquire a suitable site for the fab, taking into account factors such as the availability of infrastructure (e.g. power, water, gas), access to transportation, and proximity to suppliers and customers.
4. Design and build the fab, including the construction of cleanroom facilities, the installation of manufacturing equipment, and the integration of utilities and support systems.
5. Hire and train a workforce with the skills and expertise needed to operate the fab.
6. Commission and qualify the fab, including testing and calibrating the equipment, verifying that the manufacturing processes are operating correctly, and ensuring that the fab meets all relevant regulatory standards.
7. Begin production at the fab, using the established processes and equipment to manufacture semiconductor devices.
8. Continuously monitor and optimize the fab's operations, including regular maintenance and upgrades to equipment, and ongoing training and development for the workforce.

Also here are a few things to keep in mind while setting up a semiconductor fabrication plant:

1. The semiconductor industry is competitive. Manufacturers are continually looking for ways to offer the lowest-cost products. New manufacturing techniques can yield significant cost reductions. This trend will continue for the foreseeable future.

2. The cost of ownership of a fab is an important consideration for the semiconductor industry. It’s important for engineers to determine where they can cut their costs and make the investment as worthwhile as possible.

3. The factory is only as good as the people working in it.

4. The best plants are fully automated and require minimal supervision and the lowest possible levels of operator training.

5. A fab’s productivity is closely related to its use of equipment and tools. Good use of existing equipment can reduce plant overhead and make the most of the resources already available.

6. Fabs need skilled operators to produce high-quality devices. Train or hire competent operators to deliver high-quality, consistent yields from all operations.

7. The cost of a semiconductor fab is about 30 percent capital and 70 percent operating. Capital costs include the initial investment, equipment, plant, and equipment upgrades. Operating costs include labor, power, overhead, and utilities.

8. Design automation is a key to reducing fab costs. With design automation, you can design more functions, components, and circuit features in a smaller space, reducing cost and the amount of chip surface area consumed by chips. Design automation can reduce labor costs by freeing up the designers and engineers to create better chips. Design automation can also increase throughput and reduce cycle time.

9. The biggest cost savings in a fab is throughput. Higher throughput yields higher production capacity and reduces the amount of time spent on making wafers. You can also use advanced technologies that enable you to handle many more wafers in a given amount of time.

10. Set up the facility as far away from industrial pollution as possible.

11. Keep in mind the flow of materials and their storage requirements. Plan them well in advance so that, at times of shortage, you have the required materials ready for processing. Make sure you have extra storage space.

12. Have backup equipment ready in case of a malfunction in the power supply.

13. Install necessary facilities to handle toxic gases that might be required in processing. You can take help from experts in this field for advice.

14. Make sure you select quality building materials that can resist the effect of radiation, temperature, and moisture. Also, choose building materials according to the nature of the environment (such as high humidity).

15. Have a water recycling facility to recycle water and wastewater for use in any chemical process.

16. Make sure you have a power generation system and backup power system ready. Use state-of-the-art equipment for monitoring environmental parameters, like air, water, and heat.