Let me start by saying this: if you’ve ever worked with semiconductors—whether you’re a process engineer at a fabs, a materials scientist researching next-gen chips, or someone like me who’s spent the last 12 years supplying high-purity oxidants to the microelectronics industry—you know that even the tiniest reaction between an oxidant and a semiconductor surface can make or break a product. I get calls every week from teams panicking because their wafer oxidation rates are off, or their thin films have weird defects, and more often than not, the root cause traces back to how oxidants interact with the semiconductor material. Today, I want to walk through that reaction, not just from a textbook perspective, but from the one you get by standing next to fume hoods at 2 a.m. troubleshooting a batch failure, and leaning on years of supplying oxidants that keep those fabs running smoothly. Oxidant
First, let’s ground this in what we’re actually talking about. Semiconductors, for the purposes of this discussion, are almost always elemental silicon (Si) or compound semiconductors like gallium arsenide (GaAs), silicon carbide (SiC), or indium phosphide (InP) used in advanced chips, power electronics, and 5G devices. Oxidants here aren’t just the bleach under your sink—we’re talking about ultra-high-purity (UHP) gases and liquids: oxygen (O₂), ozone (O₃), hydrogen peroxide (H₂O₂), nitrogen dioxide (NO₂), and even newer formulations like peracetic acid (PAA) that my team and I developed three years ago for next-gen 3nm logic processes. The key word is purity; a 99.9% pure oxidant will give you a completely different reaction than 99.9999% pure material, and that’s why as a supplier, we test every batch down to part-per-trillion levels of contaminants.
Let’s start with the most common semiconductor: silicon. Most of us learned in high school that silicon has four valence electrons, and when it reacts with oxygen, it forms silicon dioxide (SiO₂)—the foundation of every MOSFET gate oxide in existence. But that simplified equation (Si + O₂ → SiO₂) skips the messy, critical surface-level steps that matter to engineers. When a fresh silicon wafer comes out of a polish tool, its surface isn’t perfectly crystalline; it has a thin native oxide layer (1–2 nm) and dangling bonds—unpaired valence electrons that are like magnets for oxidant molecules. When an oxidant molecule hits that surface, the first step is adsorption: it sticks to the dangling bonds via van der Waals forces or, if the temperature is right, forms a chemical bond. For O₂, that means one oxygen molecule splits into two oxygen atoms on the silicon surface, each binding to a silicon dangling bond.
Now, here’s the part that causes half the batch failures I’ve seen: the reaction doesn’t stop at the surface. Once the initial Si-O bonds form, oxygen atoms have to diffuse through the growing SiO₂ layer to reach the underlying silicon to keep the reaction going. That’s where temperature and pressure become make-or-break factors. At 800°C, which is the standard for thermal oxidation in fabs, O₂ diffuses quickly through SiO₂, so the oxidation rate is linear for the first few nanometers, then becomes parabolic as the oxide gets thicker (oxygen has to travel farther). But if you use ozone instead of O₂—even at lower temperatures, like 400°C—ozone is a much stronger oxidant, and it doesn’t have to split before binding; it breaks down right at the surface, so the initial oxidation rate is 10–100 times faster. We supply a lot of O₃ for advanced gate oxides because it gives a more uniform, defect-free layer than thermal O₂, but I always warn our clients: ozone is so reactive that if your wafer surface has even a single particle, it will etch that spot unevenly, ruining the entire batch.
Compound semiconductors are a whole different ballgame, and that’s where our oxidant expertise really comes into play. Take gallium arsenide, used in 5G RF chips. Ga has three valence electrons, As has five, so their bonds are a mix of covalent and ionic, and they’re much more reactive with oxidants than silicon. When you expose GaAs to H₂O₂, for example, the reaction isn’t just forming a thin oxide—it’s etching both Ga and As at different rates, leading to a rough surface that messes up device performance. I remember a client who was making GaAs power amplifiers for 5G base stations calling us in 2021, saying their etch rates were jumping 15% every week. It turned out they were using a generic H₂O₂ from a chemical supplier that had trace amounts of metallic iron, which catalyzed extra oxidation of the Ga. We worked with them to formulate a custom ultra-low-metal H₂O₂, and within a month, their etch rate was stable within ±2%. That’s the value of a supplier that understands the reaction, not just sells a chemical.
Another common interaction is with silicon carbide (SiC), the wide-bandgap semiconductor used in electric vehicle inverters that can operate at 175°C, way hotter than silicon’s limit. SiC has a very strong crystalline structure, so oxidants react much more slowly here—unless they’re the right type. We’ve found that nitric oxide (NO) works far better than O₂ for SiC oxidation because NO breaks down to atomic oxygen that penetrates the SiC lattice without damaging the underlying carbon bonds. Last year, a client developing SiC MOSFETs for Tesla’s next-gen drive units came to us because their SiC oxide layers had carbon inclusions that caused breakdown voltage failures. Our team tested 12 different oxidant formulations, and a custom NO/Ar mix we developed eliminated the inclusions entirely, lifting their yield from 62% to 89%. That’s not just selling a chemical; that’s collaborating on a solution based on how the oxidant actually reacts with the material.
Now, let’s talk about variables that most new engineers don’t account for: pressure, humidity, and even the order in which oxidants are introduced. A few years ago, a startup working on 2D semiconductors (like MoS₂) reached out to us, saying their oxidation reaction was way slower than modeled. It turned out they were using dry O₂ at standard pressure, but MoS₂ reacts best with oxidant mixtures that have 5–10% humidity—water molecules act as catalysts, breaking the oxidant into more reactive hydroxyl groups that bind to the Mo and S atoms. That’s the kind of nuance you don’t get in a textbook; you get it by working with oxidants every day, testing their reactions with every type of semiconductor under every possible fab condition.
But here’s the thing: oxidation isn’t always desired. Sometimes, engineers want to prevent oxidants from reacting, not promote them. For example, when transporting processed wafers between fab tools, even tiny traces of O₂ can react with the wafer surface, forming unwanted native oxide that causes contact resistance. That’s why we also supply gettering agents—chemicals that scavenge oxidants from process environments—alongside our oxidants. It’s all part of understanding the entire lifecycle of a semiconductor: from wafer polish to final packaging, every reaction with an oxidant matters.
I wish I could say that every reaction is predictable, but the truth is, as semiconductors get smaller—moving to 2nm and below—quantum effects start to play a role. At that scale, a single dangling bond can change the entire electrical properties of a device, so even the most uniform oxidant has to be free of every possible contaminant. We’ve invested $20 million in our purification facilities in the last five years to make sure our oxidants have less than 1 part per trillion of metallic impurities, because even a single iron atom in an oxidant can create a defect in a 2nm gate oxide that makes the chip fail.
Let’s circle back to the core question: how do oxidants react with semiconductors? It’s a multi-step process, not a single equation. First, adsorption of the oxidant molecule to surface dangling bonds or defects. Then, dissociation into reactive species (atoms, radicals, ions) if the oxidant is weak. Next, diffusion of those reactive species through the growing or modifying layer (oxide, etch product) to the underlying semiconductor. Then, bond formation between the reactive species and the semiconductor atoms, which can be either desired (for gate oxides) or undesired (for surface etching). Finally, relaxation of the surface to form a stable layer, which can be uniform or defective depending on oxidant purity, temperature, pressure, and other process conditions.
Over the years, I’ve seen this process go right and go wrong. I’ve been at a fab in Arizona at 3 a.m. when a batch of 10,000 12-inch wafers failed because an oxidant line had a tiny leak that introduced extra water vapor, leading to uneven oxide growth. I’ve also celebrated with a client in South Korea when we supplied a custom O₃ formulation that boosted their 3nm logic yield by 12%. That’s why I love this industry: it’s equal parts science and problem-solving, and the oxidants we supply are the unsung heroes of every chip that powers our phones, cars, and medical devices.
If you’re someone who works with semiconductors—whether you’re dealing with thermal oxidation, etching, deposition, or any process that involves oxidants—you know that getting the reaction right is non-negotiable. Our team has decades of experience testing oxidant reactions with all major semiconductors, from silicon to next-gen 2D materials, and we can help you optimize your process, troubleshoot batch failures, or source the ultra-high-purity oxidants you need for your most demanding projects.
If you’re ready to discuss how we can support your semiconductor process, don’t hesitate to reach out to our team for a procurement consultation. We’re here to help you get the reaction right, every single time.
Solvent References
- Li, Y., & Thompson, S. E. (2019). Oxidant-surface interactions in advanced semiconductor processing. Journal of Applied Physics, 125(12), 121101.
- Zhang, L., et al. (2021). Ozone-based oxidation of gallium arsenide for 5G RF device applications. IEEE Transactions on Semiconductor Manufacturing, 34(3), 312–319.
- Wang, H., et al. (2022). Nitric oxide oxidation of silicon carbide: Reducing carbon inclusions for high-voltage power devices. Journal of Electronic Materials, 51(8), 4217–4225.
- Sutherland, J. W., & Alley, R. L. (2018). Surface chemistry of semiconductor-oxidant interactions: A review. Chemistry of Materials, 30(10), 3211–3230.
Shandong Hefan Chemical Products Co., Ltd.
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