A Quick Overview of Thin-Film Growth Processing Equipment

As the core platform for material deposition in integrated circuit manufacturing, thin-film growth equipment has a technological evolution closely tied to process requirements.Through structural optimization and mechanism innovation, various types of equipment continue to push the performance limits, meeting the stringent demands of advanced nodes for thin-film uniformity, purity, and structural complexity.

Vacuum evaporation equipment

The vacuum evaporation equipment is based on the vacuum system, evaporation system, and heating system as the core architecture, which reduces the probability of gas molecule collision through a high vacuum environment and ensures the directional deposition of evaporated atoms and the purity of the film.

As an important branch, electron beam evaporation achieves high-purity deposition of refractory metals (such as W, Mo) and compounds (such as SiO₂, Al₂O₃) with a high energy density of 3000~6000°C, but high-energy ion bombardment is easy to cause substrate damage, and X-ray radiation requires special protection, so it gradually retreats to specific scenario applications such as LED electrodes in mainstream IC manufacturing.

In order to improve the uniformity of large-size substrates, the equipment optimizes the growth rate and material utilization by increasing the source base distance and rotating the substrate, but it is necessary to balance the growth rate and material utilization to reflect the fine control characteristics of the process parameters.

DC physical vapor deposition

Direct current physical vapor deposition (DCPVD) relies on the cathode-anode electric field to accelerate the bombardment of argon ions to achieve efficient sputtering of conductor targets, but the high voltage of Qihui leads to strong electron bombardment, and the insulating target is easy to terminate sputtering due to charge accumulation.

Magnetron sputtering equipment

Magnetron sputtering constructs an alternating electromagnetic field through the magnet on the back of the target, extending the electron motion path and increasing the plasma concentration, significantly reducing the enlightenment voltage and target voltage, reducing substrate damage, and improving the deposition rate and large-size uniformity.

Commercial equipment mostly adopts rotating magnet design to balance film uniformity, target utilization and full-target sputtering requirements, avoid local excessive consumption of targets and particle pollution caused by fixed magnetic fields, and reflect the technological progress of dynamic magnetic field control.

RF Physical Vapor Deposition

RFPVD uses an RF power source such as 13.56MHz as the excitation source, realizes the stable negative potential of the target surface through the alternating positive and negative half-cycles, is compatible with conductor and non-conductor target sputtering, and the low target voltage characteristics effectively control the kinetic energy of the deposited particles, optimize the film formation structure and reduce the substrate damage, and is suitable for the precise control of ultra-thin film thickness. However, the low target voltage leads to a decrease in sputtering yield, and the deposition rate is not as good as that of DCPVD. Therefore, DC and RF hybrid loading technology has emerged, which not only maintains low damage characteristics but also improves the deposition rate, showing application value in fine structures such as metal grids, and reflecting the technology integration trend of multi-power supply collaboration.

Ionization physical vapor deposition equipment

Ionization physical vapor deposition equipment focuses on the problem of high aspect ratio structure coverage, and realizes directional deposition through metal atom plasmization and wafer bias regulation.

The core of the technology is to increase the proportion of metal ions to form a vertical ion flow, and the technical paths include RF coil plasma generation, high field magnetron sputtering source enhanced ionization rate and self-ionization technology. The latter reduces ion scattering through high magnetic field strength, low pressure/zero argon processes (such as copper self-sputtering), enhances the bottom coverage of the step and weakens the overhang structure of the trench, and optimizes the corner coverage by using the anti-sputtering effect. This technology has led the preparation of aluminum interconnect isolation layer, tungsten embolic adhesion layer and copper interconnect seed crystal layer, and is integrated with metal CVD chamber to form a multi-process collaborative system to meet the requirements of advanced node fine structure.

Atmospheric Pressure Chemical Vapor Deposition

Atmospheric chemical vapor deposition (APCVD) operates in a near-atmospheric pressure environment, and has become the main equipment for industrial mass production by virtue of its simple structure, low cost, high deposition rate and high production efficiency.

Its gas control, heating, transmission, reaction chamber and exhaust gas treatment system work together to achieve uniform distribution of reaction sources through precise regulation of the gas circuit and gas injection device, electromagnetic induction or infrared heating to provide reaction heat sources, and multi-piece/monolithic equipment to adapt to different production capacity needs. However, the atmospheric pressure environment leads to frequent collisions of gas molecules, which can easily cause homogeneous nucleated particle pollution, which puts forward strict requirements for chamber design and maintenance.

Low-pressure chemical vapor deposition

Low-pressure chemical vapor deposition (LPCVD) significantly increases the average free path and diffusion coefficient of the gas, improves the uniformity of film thickness, resistivity consistency and step coverage, and reduces the retention of self-doping and reaction by-products by reducing the working pressure to 10-100mTorr and the high temperature of 350-1100°C, so as to achieve the preparation of high-quality films with steep transition zones. The equipment adopts a hot-wall/cold-wall heating system, the former requires regular cleaning of the inner wall deposits for full-cavity heating, and the latter only heats the wafer to reduce chamber contamination, and the cold-wall system is more mainstream in single-chip equipment. LPCVD continues to evolve in the direction of high production capacity, low temperature and new reaction sources, adapting to the high-quality deposition needs of traditional materials such as silicon oxide, silicon nitride, polysilicon and emerging materials such as gallium nitride and graphene, and supporting the stable preparation of high-precision and low-defect films in advanced nodes.

Plasma enhances chemical vapor deposition

Plasma-enhanced chemical vapor deposition (PECVD) has become a key process for heat-sensitive substrate structures by virtue of its plasma-activated reaction precursor to achieve the growth of highly active films in a low-temperature environment. The plasma generation mechanism is divided into radio frequency (13.56MHz) and microwave bands, and uses capacitive coupling (CCP) to directly generate plasma or inductive coupling (ICP) to accelerate electrons to produce high-density plasma through high-frequency electric fields.

The deposition rate is relatively limited due to the low ionization rate of capacitive coupling. Inductive coupling enhances reactivity and optimizes deposition efficiency by increasing plasma density. PECVD is widely used in the back-end metal interconnect process of integrated circuits, and can optimize film density, chemical composition, stress and mechanical toughness by precisely controlling plasma parameters to meet the needs of low damage and high uniformity. In recent years, this technology has been extended to new displays, flexible electronics and other fields, achieving uniform deposition over large areas through plasma spatial distribution control, supporting the reliable manufacturing and performance improvement of flexible devices.

Atomic layer deposition equipment

Atomic layer deposition (ALD) equipment relies on the self-limiting surface reaction mechanism to grow layer by layer in the form of quasi-single atomic layers, and the thickness control accuracy reaches the sub-nanometer level, which has become the core equipment of advanced node thin film deposition. Thermal ALD relies on thermal energy to drive the chemical reaction of precursors, with an operating temperature range of 200-500°C. Plasma-enhanced ALD (PEALD) introduces plasma to reduce the activation energy of the reaction, and the operating temperature is extended to room temperature to 400°C, while increasing the film density and reducing the impurity content. The structure of ALD equipment covers the design of sprinkler head type and flow pattern, which adapts to the transportation needs of different precursors, and its low thermal budget, high uniformity and excellent step coverage play a key role in gate sidewalls, high-k media, metal grids and 3D integrated packaging. At present, ALD technology is developing in the direction of multi-material compatibility, low-temperature process and high production capacity, supporting the precision deposition of complex structures such as 3D NAND and advanced packaging, and expanding to emerging fields such as 2D materials and quantum dots.

Molecular beam epitaxy system

The molecular beam epitaxy (MBE) system grows single crystal films layer by layer on the surface of the substrate through thermal energy atom/molecular beam in an ultra-high vacuum (10⁻⁸-10⁻¹¹Torr) environment, so as to achieve atomic-level precise control of thickness, interface, components and impurity concentration. The system consists of an ultra-high vacuum system, a molecular beam source, a substrate heating/transfer device, in-situ monitoring (such as reflection high-energy electron diffractometer RHEED) and a control system, with the growth chamber as the core unit, equipped with source furnace shutter, cooling system and real-time monitoring module to ensure that the growth process is controllable. MBE technology originated from the preparation of semiconductor single crystal thin films, and has now expanded to multi-material systems such as group III.-V, group II.-VI, silicon germanium, graphene, oxide and organic films, supporting the research and development of microwave devices, optoelectronic devices and quantum materials. Its slow growth rate and high equipment cost have been gradually improved through multi-growth chamber configuration, in-situ monitoring optimization and automated control. In recent years, MBE has made breakthroughs in the controllable growth of two-dimensional materials, quantum dots, and superlattice structures, promoting the innovative development of new quantum devices, optoelectronic devices, and superconducting materials, and has become a core platform for cutting-edge materials research.

Gas phase epitaxial system

Vapor-phase epitaxy (VPE) systems generate single crystal layers through the chemical reaction of gaseous compounds on the surface of the substrate, supporting homogeneous (such as Si/Si) and heterogeneous (such as SiGe/Si, GaN/Al₂O₃) epitaxy, and are widely used in the fields of nanomaterial preparation, power devices, semiconductor optoelectronic devices, solar photovoltaics, and integrated circuits.

Its core lies in the optimization of reaction chamber design, airflow uniformity control, temperature/pressure precise control and particle defect suppression, and the evolution of mainstream commercial equipment towards large film capacity, fully automatic control and real-time monitoring of the growth process. The structural form covers vertical, horizontal, and cylindrical types, and the heating methods use resistor, high-frequency induction or infrared radiation - silicon-based thick film epitaxy mostly uses induction heating, while the film tends to be infrared heating to achieve rapid temperature rise and fall. The typical silicon/germanium-silicon VPE process uses silane, dichlorosilane, and trichlorosilane as the silicon source, germanium and methyl silane as germanium/carbon sources, and hydrogen as the carrier gas to support the preparation of high-performance epitaxial layers in modern integrated circuits. In recent years, VPE technology has made breakthroughs in the direction of improving the uniformity of large-size substrates, epitaxy of new material systems (such as SiC and GaN) and in-situ doping control, promoting the development of wide bandgap semiconductor devices and high-efficiency photovoltaic devices, and combining in-situ monitoring technology to achieve real-time regulation of growth dynamics and improve the stability of the process window.

Liquid phase epitaxy system

The liquid phase epitaxy (LPE) system realizes crystal growth through the precipitation of solutes in low-temperature solvents, and is suitable for the preparation of Si, GaAs, AlGaAs and other materials, as well as group III.-V and cadmium tellurium mercury semiconductor devices, and can be used to produce optoelectronic devices, microwave devices and solar cells.

The system consists of gas control, heating, control, charging chamber, reaction chamber and vacuum module, and is divided into horizontal sliding boat, vertical impregnation and rotating crucible (centrifugal) system. Its advantages are simple equipment structure, fast growth rate, epitaxial large thickness, wide range of dopants and safe operation. Limitations include difficulty in controlling large-size uniformity, high cost due to high substrate requirements, difficulty in growth when lattice mismatch exceeds 1%, difficulty in controlling nanoscale thickness, and slightly inferior surface quality to VPE. At present, LPE equipment is mostly self-made by laboratories or manufacturers, relying on high-stability power supplies to ensure temperature uniformity and optimize growth dynamics through temperature gradient regulation. In recent years, LPE still has application value in specific fields such as infrared detectors and high-power laser diodes, especially in scenarios that require large-thickness epitaxial layers or special doping, and at the same time improve process stability and yield through automated control and in-situ monitoring technology, supporting the innovation of new device structures.