| Electronics > Beginners |
| Chip making process |
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| jmelson:
--- Quote from: ZeroResistance on October 13, 2018, 09:21:13 am ---I hope the learned and experienced folks over here would shed some light on the chip making process, I mean more so with if we want to get chips made what is the whole pipeline associated with it? I have a few questions and hope the learned folks address it 1. If I have a schematic that consists a op-amp amplifier and say a mosfet driver would this finally be flattened to transistors at the lowest level. --- End quote --- Yes, certainly, transistors are the basic element. But, actually, there is a lower level, which is the individual layer masks. --- Quote ---Will the same be applicable for digital circuits? --- End quote --- Yes, at the lowest level, it is all analog, and all transistors, resistors and wires. --- Quote ---2. Do I have to select a process node like 22nm etc.. or does the foundry decide that? --- End quote --- Yes, you must select a process first, to have the parameters of the silicon, doping, etc. before you can start describing the transistor channel width and length. Each transistor is described by length, width and type (doping). Each process has a "design kit' which has all these specs. --- Quote ---3. If I have tested by circuit using a specific op-amp from TI and mosfet driver from Fairchild, how do I ensure that he same spec gets transferred to the final flattened transistors? --- End quote --- You really CAN'T! These are proprietary parts, and TI, etc. will not give out the internal design. So, you have to redesign these parts in the process you select. Then, simulate until the performance is what you want. --- Quote ---4. What tools are required for creating and sending the designs to mask maker and foundry? --- End quote --- There are several major programs. If you are not at a university, the commercial design suites are very expensive, like 50K US dollars/seat, with massive costs to renew each year. Cadence is the leader, Mentor is still used, I think. There are also some open-source design packages. --- Quote ---5. What are the costs and MOQ involved in the whole process? --- End quote --- I am involved in a university project making chips for nuclear physics experiments. We use MOSIS, and a university Cadence license. We used to use the AMI (now ON Semi) C5 process, a 350 nm 5V process. We just did our first chip with the Austria Semi (AMS) fab. Their design kit is WAY better than the AMI/ON Semi kit. Minimum order is 40 parts (untested) and you can order more in 40-part increments. Our chip was fairly large, about 5 x 7 mm, and the cost for 40 parts would run some $28K US dollars, unpackaged. They usually charge something like $7500 for packaging. --- Quote ---6. I have heard of companies like MOSIS / Europractice who work with low volumes. Do these companies handle the whole process from mask making and dealing with the foundry on their own. Does any of you have any experience in dealing with these companies? --- End quote --- Well, MOSIS combines dozens of masks from different projects onto one wafer, and thus spreads the cost of the masks across multiple projects. So, you must provide them the mask layers, generally as a "Calma stream", and they have to meet a number of criteria to be acceptable for fabrication. If the mask data is accepted, then MOSIS handles the whole interaction with the fab. Jon |
| ZeroResistance:
--- Quote from: jmelson on October 15, 2018, 03:36:07 pm ---We use MOSIS, and a university Cadence license. We used to use the AMI (now ON Semi) C5 process, a 350 nm 5V process. We just did our first chip with the Austria Semi (AMS) fab. Their design kit is WAY better than the AMI/ON Semi kit. Minimum order is 40 parts (untested) and you can order more in 40-part increments. Our chip was fairly large, about 5 x 7 mm, and the cost for 40 parts would run some $28K US dollars, unpackaged. They usually charge something like $7500 for packaging. --- End quote --- How much time does Mosis take to send you back the chips, once you send them the design files? How do you handle the unpackaged chips, do they need special care? do you need to pour epoxy on them before testing them? Do they come with pads to solder on the PCB? How does the software help you in designing the circuit, does it have high level components like op-amps, adc's etc. and them during synthesis these blocks get flattened to transistors? |
| jmelson:
--- Quote from: ZeroResistance on October 15, 2018, 04:02:06 pm --- How much time does Mosis take to send you back the chips, once you send them the design files? How do you handle the unpackaged chips, do they need special care? do you need to pour epoxy on them before testing them? Do they come with pads to solder on the PCB? How does the software help you in designing the circuit, does it have high level components like op-amps, adc's etc. and them during synthesis these blocks get flattened to transistors? --- End quote --- It takes at least 3 months to get the chips back. Since we require some different packaging (completely filled plastic packages) that costs a few extra weeks. We do not get unpackaged chips, we always get them packaged. Some design kits have a lot of stock modules like op-amps included, some do NOT. You have to get the specific kit to know what will be included. Otherwise, there are some generic circuits like op-amps that you might be able to download from people. Well, there is no synthesis for analog parts, that's why each transistor needs to be "carved" to meet your needs. So, the modules are just a bunch of transistors with dimensions included in them. Jon |
| ZeroResistance:
--- Quote from: jmelson on October 15, 2018, 04:54:08 pm --- Some design kits have a lot of stock modules like op-amps included, some do NOT. You have to get the specific kit to know what will be included. Otherwise, there are some generic circuits like op-amps that you might be able to download from people. Well, there is no synthesis for analog parts, that's why each transistor needs to be "carved" to meet your needs. So, the modules are just a bunch of transistors with dimensions included in them. Jon --- End quote --- Thanks for the info, Do these design kits need to be purchased from the foundry? eg. AMS Its interesting to hear that each transistor in an analog circuit needs to be manually crafted. Your would need a quite a big team to make a large circuit wouldn't it? |
| coppice:
--- Quote from: ZeroResistance on October 15, 2018, 05:24:29 pm --- --- Quote from: jmelson on October 15, 2018, 04:54:08 pm --- Some design kits have a lot of stock modules like op-amps included, some do NOT. You have to get the specific kit to know what will be included. Otherwise, there are some generic circuits like op-amps that you might be able to download from people. Well, there is no synthesis for analog parts, that's why each transistor needs to be "carved" to meet your needs. So, the modules are just a bunch of transistors with dimensions included in them. Jon --- End quote --- Thanks for the info, Do these design kits need to be purchased from the foundry? eg. AMS Its interesting to hear that each transistor in an analog circuit needs to be manually crafted. Your would need a quite a big team to make a large circuit wouldn't it? --- End quote --- Unless you can find a canned analogue solution that exactly suits your needs, licensable in a reasonable manner, tailored for the exact process you will use, expect your analogue development to be fairly expensive and protracted. |
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