10/5/2023 0 Comments Smallest transistor intel![]() “The problem is that you don’t necessarily get what you want to get. “This is one of the main reasons why flash memory moved to vertical NAND,” said G. Beginning several years ago, NAND memory companies reported seeing unexpected irregularities in how data moved in and out of memory. “It means you have to optimize the ground rules to maximize throughput out of the EUV tool.”įlash memory was one of the first places that chipmakers began experiencing quantum effects firsthand. “You can see increased line edge roughness, variability, the potential for opens and shorts where you didn’t expect them,” said Gary Patton, CTO at GlobalFoundries. Source: Intel/MITĪt 7/5nm and beyond, there is a whole new set of worries to add to the list that are associated with quantum effects. ![]() 1: Metal gate improvement over poly depletion with associated capacitance and drive current improvement. We got better field coupling into the channels and started to do things in technology to reduce some of these quantum effects.”įig. Metal gate got rid of the poly depletion. Then we did things like high-k metal gate. We went off and studied, learned it, and built it into our predictive device models. That little bit further away from the interface is a quantum effect, and at 130/90/65nm it became a measurable delta in the behavior of the inversion capacitance. It sits a little bit further away because of the density of stage function in the channel of the transistor. If you go back 10 to 15 years, before we had high-k and metal gate, we had polysilicon depletion effects on one side of the gate, and a quantum confinement effect, where the carrier channel doesn’t sit at the interface of the transistor. The question is the extent to which they influence your ability to understand physical and electrical behavior of the devices. “You can’t really solve the transistor equation without understanding periodic lattice and quantum effects. “Quantum effects have always been there,” said David Fried, vice president of computational products at Coventor, a Lam Research Company. But in the chip world, these quantum effects show up in a variety of strange behaviors that are becoming increasingly problematic. Quantum tunneling, for example, has been documented for nearly a century in alpha particle decay research. Quantum effects have been observed, studied and theorized for years, and not just in the semiconductor industry. Going forward, more quantum effects are expected due to transistor-body dimension reduction, which is required to maintain electrostatics, and to gate-length reduction.” This effect has existed in CMOS technologies for a while now, and it is a quantum effect. ![]() “For example, as a consequence of gate dielectric scaling and that of the increasing electric fields within the device, the carriers in the inversion layer are no longer located at the silicon dioxide-silicon interface, but somewhere below, resulting in an increased effective dielectric thickness. “Quantum effects happen in the device as soon as certain device dimensions become very small, due to scaling and its associated requirements,” said Anda Mocuta, director of technology solutions and enablement at Imec. ![]() But as designs shrink to 7/5nm and beyond, quantum effects are emerging as a more widespread and significant problem, and one that ultimately will affect everyone working at those nodes. This explains why foundries and manufacturing equipment companies so far are the only ones that have been directly affected, and they have been making adjustments in their processes and products to account for those effects. Quantum effects typically occur well behind the curtain for most of the chip industry, baked into a set of design rules developed from foundry data that most companies never see. Quantum effects are becoming more pronounced at the most advanced nodes, causing unusual and sometimes unexpected changes in how electronic devices and signals behave.
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