Revolutionizing Wafer Cleaning: BATCHSPRAY® and SicOzone™ Reduce Chemical Consumption Significantly
The global semiconductor fabs are actively working toward sustainability. Using ozone for cleaning directly supports these efforts in semiconductor manufacturing. Batch spray cleaning with the SicOzone™ process ensures high throughput, low media consumption, and reliable performance. Additionally, spiking technology with ozone achieves cleanliness levels on par with traditional methods.
Single-wafer wet cleaning is the most common method. It uses ultrasonics to help remove tiny particles from the wafer surface, but it has major downsides. Cleaning wafers one by one uses a lot of chemicals and slows down production. On the other hand, batch spray cleaning is a better option because it uses fewer chemicals and cleans more wafers at once, making it more efficient and eco-friendly.
Resist strip / organic clean vs. SicOzone™
Traditionally, a piranha mixture is used to clean organic residues or remove photoresist. This sulfuric acid and hydrogen peroxide solution needs frequent refreshing with peroxide, which leads to high chemical use. In contrast, a batch spray cleaner with ozone eliminates the need for sulfuric acid and peroxide while cutting DI water use by 22.4%. It achieves low chemical consumption by spraying DI water and ozone gas onto the wafer surface, effectively cleaning organic residues.
SPM clean/strip & ozone based clean/strip
To remove photoresist, the process alternates between strip and clock steps to boost the removal rate. During the strip step, the wafers spin at very high speeds, reducing the DI water layer to a minimum. This allows ozone to pass through the water and react directly with the photoresist on the wafer surface. As a result, the reaction produces CO₂ and other residues, depending on the photoresist’s composition.
Organic clean vs. SicOzone™
To achieve the cleaning power of a traditional SC1 mixture (1:1:5 ratio), the system uses an NH4OH spiking process. In addition to ozone gas and DI water flow, 20 mL of NH4OH per minute is injected into the DI water. This creates the same SC1 effect, effectively removing organic material by etching particles from the wafer surface.
SC1 clean & ozone based clean
The comparison shows an organic clean step followed by a rinse and dry sequence. NH4OH use drops by 81.4%, and ozone replaces peroxide, cutting DI water use to 20.1%. Oxide loss stays below 0.5 Å, with slight variations due to metrology. A closer look at a 50-wafer process lot reveals consistent results across all wafers.
Metal clean vs. SicOzone™
Metal contamination is usually cleaned with SC2, a mixture of HCl, H₂O₂, and water (1:1:5 ratio). To replicate this in a batch tool, an HCl spiking system adds 50 mL per minute to the DI water stream. Ozone gas is injected into the process chamber the same way as in SC1.
SC2 clean & ozone based clean
Because the metal clean process differs from the organic clean, it uses less DI water and ozone. HCl consumption drops by 81.14%, and DI water use is reduced by 32.11% compared to traditional SC2.
Oxide etch vs. SicOzone™
An additional spiking system offers flexibility to etch either native or grown oxide. To etch the oxide, HF flow is adjusted from 5 to 120 mL per minute and injected into the DI water stream to achieve a specific etch rate.
Traditional & batch spray oxide removal
HF use is reduced by 17.66%, and DI water consumption is lowered by 8.5%. Adjustments in temperature, flow, and spiking amount result in different etch rates based on process requirements. For simple native oxide removal, only a few mL per minute of HF are needed, while removing 500 Å requires a flow rate of 120 mL per minute. Both processes can be done within the same system.
Consumption
The biggest advantage of this cleaning method is the reduced chemical consumption, leading to significant savings in both chemicals and DI water. By combining all cleaning and rinse steps, additional savings are achieved. Rinse steps are kept short due to the highly diluted chemicals, resulting in shorter process times and higher throughput. Another benefit of batch spray cleaning is that multiple process and rinse steps can be done without extra handling, saving time. NH4OH is reduced to 1.16 mL per wafer, and HCl is also reduced to 1.16 mL. HF consumption depends on the specific purpose but can be reduced to 0.45 mL per wafer for oxide removal. DI water use drops by almost 21.4%. Ozone eliminates the need for H₂O₂ and H₂SO₄, and extended post-SPM rinses to remove sulfuric ions from the wafer surface are no longer needed.
Cleaning silicon-based wafers in a batch spray cleaning tool with ozone reduces the use of critical resources like multiple chemistries and DI water. It also lowers the need for fresh chemicals and waste treatment, or even eliminates them. These benefits help semiconductor manufacturing facilities achieve the important goal of reducing their carbon footprint.