The showerhead (also known as gas distribution plate or gas homogenization plate) in semiconductor manufacturing equipment serves as the "gas distribution heart" of core processes such as etching, chemical vapor deposition (CVD), and atomic layer deposition (ALD). It determines the uniformity of deposited film thickness and etching rate consistency, directly impacting chip yield. However, its technical barriers are extremely high, and it has long been monopolized by overseas manufacturers, with a single unit costing hundreds of thousands of RMB. As process nodes continue to shrink to 7nm and below, the chip manufacturing environment becomes increasingly challenging. Showerheads face higher temperatures (above 600°C), higher pressures, and more intense corrosive plasmas (e.g., fluorine‑based and chlorine‑based plasmas), while simultaneously demanding unprecedented levels of gas distribution uniformity and chamber cleanliness. Showerheads made of advanced ceramic materials such as aluminum nitride and silicon carbide, leveraging their core advantages of high‑temperature resistance, high electrical insulation, strong corrosion resistance, and low metal contamination, have become the top choice for advanced process showerheads, with substantial market growth potential. This article explores the application trends of ceramic materials in this semiconductor manufacturing component.
1. Structure and Working Principle of the Showerhead
The showerhead typically has a disk shape. Its main body contains an internal gas pressure‑equalizing channel optimized via fluid dynamics simulations, and its bottom surface is densely perforated with thousands of micro‑holes. The top is connected to gas inlet lines for different reactive gases. Taking a typical CVD reaction chamber as an example: after gas inlet, different reactive gases diffuse and split through the internal precision pressure‑equalizing channels to form a uniform concentration field. They are then vertically ejected from the bottom surface of the showerhead through thousands of micron‑sized through‑holes in a laminar flow manner onto the wafer surface, where they react and form a thin film. By influencing the gas flow pattern inside the chamber, the showerhead helps avoid turbulence and dead zones. This not only ensures extreme uniformity of the reactive gases over the wafer surface but also ensures that reaction byproducts are promptly evacuated, allowing fresh gas to continuously contact the wafer surface. Ultimately, this guarantees film thickness uniformity and etch rate consistency, thereby safeguarding chip yield.
2. Material Evolution of Semiconductor Showerheads and Application Trends of Ceramic Materials
The choice of material for the showerhead directly determines its service life, environmental resistance, and process compatibility. Currently, semiconductor showerhead materials fall into three main categories, catering to different processes and cost budgets:
Metallic materials, including aluminum alloys, stainless steel, pure nickel, and nickel‑based alloys. Among these, aluminum alloys are the most widely used for conventional processes (28nm and above) due to their light weight, good thermal conductivity, and moderate cost. Through hard anodizing treatment, their corrosion resistance can be improved. However, under high‑temperature, strong plasma environments, the plasma bombardment resistance of the aluminum alloy matrix is limited, leading to surface damage or performance degradation. Currently, in critical processes such as extreme ultraviolet (EUV) lithography and atomic layer deposition (ALD), nickel‑based alloys and titanium alloys are gradually replacing aluminum alloys due to their superior plasma bombardment resistance and high‑temperature stability.
Silicon‑based materials, also known as silicon electrodes, are made from high‑purity monocrystalline silicon. The material is highly pure, not prone to releasing impurities, thus reducing contamination of reactive gases and improving process yield. They are suitable for low‑to‑mid‑end etching and deposition processes but have weaker plasma corrosion resistance and require periodic replacement.
Ceramic matrix materials such as aluminum nitride, silicon carbide, and alumina, as well as functional coatings like yttria and diamond‑like carbon (DLC). These offer advantages such as high‑temperature resistance, corrosion resistance, high purity, and high thermal conductivity. They are primarily used in high‑end processes at 7nm and below, representing an important direction in the evolution of showerhead materials.
01 Aluminum Nitride (AlN)
Compared to traditional aluminum alloys, AlN ceramic has a thermal conductivity of up to 170 W/(m·K) and temperature resistance exceeding 1000°C. It can quickly dissipate heat generated during showerhead operation, avoiding structural deformation due to localized overheating and thus ensuring gas distribution uniformity. Additionally, it has no metallic impurity precipitation, effectively preventing wafer contamination, meeting the stringent requirements of sub‑7nm processes.
02 CVD‑SiC
The most prominent feature of CVD‑SiC showerheads is their excellent resistance to fluorine/chlorine plasma corrosion, with a service life 2–4 times longer than that of silicon showerheads. They can withstand extreme environments with highly corrosive plasmas and high‑frequency plasma bombardment, improving the uptime of dry etching equipment and significantly reducing replacement frequency and downtime maintenance costs. They are suitable for use as upper electrode plates in reaction chambers and as edge focusing rings around wafers. However, CVD‑SiC showerheads are difficult to manufacture and currently cannot be mass‑produced domestically (in China), relying on imports.
03 Yttria (Y₂O₃) Coating
Yttria coatings exhibit exceptional chemical stability under high‑energy ions and halogen plasmas, effectively preventing corrosive gases and plasmas from attacking the showerhead substrate. They are a key protective material for high‑end etching chambers, suitable for logic and memory chip manufacturing below 7nm, significantly extending component life. Currently, yttria coatings are typically applied using advanced techniques such as magnetron sputtering and ALD.
04 Diamond‑Like Carbon (DLC) Coating
DLC is an amorphous carbon film containing both sp³ (diamond structure) and sp² (graphite structure) hybrid bonds. It features high hardness, self‑lubrication, and excellent chemical inertness. It can significantly reduce gas flow resistance and minimize wear on the inner walls of the showerhead's micro‑holes. Notably, its low surface energy characteristics also reduce adhesion of reaction byproducts. As chip integration continues to increase, the demands on showerhead cleanliness and wear resistance are rising, and the application proportion of DLC coatings is expected to gradually increase.