This is a novice question.
I would like to do some SPICE experiments using components from the TSMC 180nm manufacturing process. Why exactly this? I think I'm getting familiar with real components that can one day be integrated (MOSIS?)
Obviously I don't have access to an official PDK and so I know quite little.
I found some SPICE models for P and N mosfets, but I would like to understand something else. In this production process (TSMC 180nm) is there the possibility of having diodes (normal, Schottky or PIN)? In this case, are there any specific SPICE models? Is it possible to find them?
If there are no specific SPICE models for this process, can I create them manually? Is it a difficult or feasible process? Alternatively, can I use P or N MOSFETs using the internal diode? Is it convenient to do so?

Thanks in advance.

 

If you are designing an IC, you REALLY need the fab's models for their devices, especially for deep-submicron processes. If you don't use them, you will likely find that you have wasted your money on the chip, especially if it has any analog circuits on it.

Different processes have different options. CMOS processes generally allow lateral PN diodes and a common option is a PIN diode. I've never worked with on that supported Schottky, but we never needed them, so that doesn't say much.

 

I understand what you mean, but we are a startup with no revenue (yet), we have a prototype but we want to validate our idea directly with a real production process. I imagine that it is not possible to legally find TSMC models except directly from them by paying expensive licenses that we currently cannot afford. Is that so?

 

I understand what you mean, but we are a startup with no revenue (yet), we have a prototype but we want to validate our idea directly with a real production process. I imagine that it is not possible to legally find TSMC models except directly from them by paying expensive licenses that we currently cannot afford. Is that so?

Not necessarily. TSMC makes their money by fabricating chips, not by requiring people that want to pay the millions of dollars to fabricate chips to pay a bunch of fees to get the models needed to design the chips in the first place.

Contact MOSIS and ask them what is required to get the TSMC 180 nm models (for whatever variant you are interested in). Often times, all that is required is signing an NDA (though I have been out of the (IC design business for a number of years and things might have changed). In other words, don't imagine something -- go find out the answer.

IIRC, there is a one-time registration fee for MOSIS that was pretty substantial, but that fee was applied in its entirety to the first foundry order. The purpose was to weed out people that weren't serious about using the service. If you can't afford the registration fee (given that it is applied to your first order), then you can't afford to fab the chip in the first place.

You can also contact TSMC directly, as they (probably still) offer shuttle runs (engineering wafer runs) as an option.

On another point, is your prototype an IC? Or is it a prototype using discrete components? If it's not an IC, and if it involves any significant analog processing or has any kind of demanding performance requirements, then you can expect to have to completely redesign significant portions of the circuit since IC design and discrete circuit design are radically different.

 

[...]

Contact MOSIS and ask them what is required to get the TSMC 180 nm models (for whatever variant you are interested in). Often times, all that is required is signing an NDA (though I have been out of the (IC design business for a number of years and things might have changed). In other words, don't imagine something -- go find out the answer.

This is good advice. Thank you!

IIRC, there is a one-time registration fee for MOSIS that was pretty substantial, but that fee was applied in its entirety to the first foundry order. The purpose was to weed out people that weren't serious about using the service. If you can't afford the registration fee (given that it is applied to your first order), then you can't afford to fab the chip in the first place.

It all depends on the amount being asked for.

You can also contact TSMC directly, as they (probably still) offer shuttle runs (engineering wafer runs) as an option.

I'll try!

On another point, is your prototype an IC? Or is it a prototype using discrete components? If it's not an IC, and if it involves any significant analog processing or has any kind of demanding performance requirements, then you can expect to have to completely redesign significant portions of the circuit since IC design and discrete circuit design are radically different.

It's a prototype that uses discrete components. I have an FPGA but also a lot of external circuitry. I don't know what "analog" means and if it can be applied in my case; I have several voltage levels to deal with, but they are all discrete (they are not just two levels like normal boolean circuits). Yes, I expect to have to redesign everything heavily, but it's a necessary path and I want to take it. The prototype works well but some parameters (performance, occupied area, etc.) must be done directly on a silicon implementation, otherwise the numbers remain unrealistic.

 

I looked at MOSIS's website. Their registration fee is $10,000 and their minimum foundry order is $25,000. They don't have the price lists published anymore (which is a real shame), but even over a decade ago it was tough to get engineering samples (five die) for under $50k. A dedicated wafer run can easily exceed a million dollars, though probably somewhat less than that for 180 nm.

If you don't know what "analog" refers to in a circuit design, then you definitely need to find someone else to do your chip design for you.

 

I have always thought that "analog" means the processing of continuous signals (with continuous voltage values). Where I come from, "digital" always means "binary", i.e. circuits with ONLY two discrete levels. My circuit doesn't deal with continuous signals but it doesn't just have two discrete voltage levels either. It has 4 discrete voltage levels. According to the definitions I know it is neither analog nor digital (but not even mixed-signal, since it does NOT combine digital (binary) and analog circuits). So, either I don't know the definitions well or I don't really know how to define it.