The power requirements for semiconductor manufacturing equipment vary significantly depending on the type of equipment and its specific needs. Unlike AC power supplies or batteries commonly found in household equipment, semiconductor manufacturing equipment requires specialized power sources.
This includes high-powered DC supplies capable of delivering hundreds of amperes, high-voltage power supplies reaching tens of kilovolts, and high-frequency power supplies.
To ensure optimal performance in each manufacturing system, it's crucial to select power supplies matching the precise specifications of the equipment. However, standard off-the-shelf power supplies often fall short of meeting the needs of the semiconductor manufacturing industry. Therefore, power supply manufacturers are frequently requested to produce custom-designed power supplies that meet specific performance criteria and functionality requirements of the semiconductor manufacturing equipment of their clients.
This article aims to provide a comprehensive overview of semiconductor manufacturing equipment, their power needs/requirements, and delves into the intricacies of the power supplies best suited to meet these needs.
Types of Semiconductors
Semiconductors are materials with properties between those of conductors (which allow electricity to flow) and insulators (which stop electric flow). This characteristic is critical to creating sophisticated components and, by extension, complex circuits that allow for more precise control over electric flow. Semiconductors can also be really small, which allows for the creation of complex circuits with multiple semiconductor elements (like transistors and diodes) on silicon wafers. These circuits are called integrated circuits. The term "integrated" signifies that different types of components (with different electric properties and functions) are collected/consolidated on the same chip/wafer. When the density of these semiconductor elements exceeds a certain threshold, they are classified as large-scale integrated circuits (LSIs).
Semiconductors and ICs created using these semiconductors can be classified into various types and categories based on their functions. The following sections will explain these different semiconductor categories in detail.
Logic Semiconductors and ICs
Logic semiconductors serve as the "brains" of electronic devices like smartphones, computers, home appliances, and automobiles. They perform various information and signal processing tasks to control and guide the operation of these devices.
The most common logic application is the Central Processing Unit (CPU), which controls the overall logic and operation in various devices including computers and smartphones. Recently, Graphics Processing Units (GPUs) have gained attention because they are better at parallel processing compared to CPUs. This makes these specialized logic semiconductors and ICs handle image processing, graphics, AI, and machine learning tasks better than CPUs.
Other types of logic semiconductors (and ICs) include Field Programmable Gate Arrays (FPGAs), which allow for post-manufacture programming of logic circuits, and Application-Specific Integrated Circuits (ASICs), designed for specific functions or applications. All these variants - CPUs, GPUs, FPGAs, and ASICs - fall under the category of logic semiconductors (and ICs), each playing a crucial role in modern electronic devices.
Analog Semiconductors
Analog semiconductors can process non-digital electrical signals (analog signals) such as light, sound, and temperature. They can capture and process data from the environment and other non-electric sources. They also perform crucial conversions: analog-to-digital (AD) and digital-to-analog (DA). This allows them to bridge the gap between our analog world and digital devices. When they convert analog-to-digital, they allow electronic devices to capture information from the world around them and process and use it in the form of electrical signals. Similarly, digital-to-analog allows these devices to interact with the outside world.
These versatile components have applications in a wide range of fields. They're used in smartphone light and temperature sensors, automobile pressure sensors, Internet of Things (IoT) devices, and medical equipment like heart rate monitors. For instance, light sensors in smartphones convert ambient light intensity into electrical signals. This enables automatic screen brightness adjustment and proximity sensing during calls to detect when the phone is held to the user's face.
Image Sensors
Image sensors are semiconductor devices that convert light into electrical signals. They are used in digital cameras, smartphones, medical imaging devices, etc. These electrical signals or digital signals basically convert the information conveyed by the light into a complex series of binary codes (0,1) that is used to create images and videos in a digital format. Previously, the information conveyed in the form of light (for an image or a video) could only be "captured" on a magnetic film but not converted.
An image sensor contains an electronic circuit with millions of light-receiving elements. Their primary function is to transform the light collected (by the sensor) into digital signals. These signals are then processed by CPUs and GPUs to produce images or videos in a format that we can see and process. In essence, image sensors perform a role similar to the retina in the human eye, which converts light into signals that our brain can process
Image sensors are broadly classified into two types. The first is CMOS (Complementary Metal-Oxide-Semiconductor), primarily used in smartphone cameras. The second type is CCD (Charge-Coupled Device), mainly found in industrial cameras and professional digital cameras requiring high image quality.
Memory Semiconductors
Memory semiconductors are storage devices that record data in the form of digital signals (0,1). These devices contain numerous individual components called memory cells, which are the smallest units for data recording - A single bit. These memory cells record digital signals by altering their state from off (0) to on (1) or on to off through changes in voltage or magnetism.
Semiconductor memory offers several advantages over conventional memory, including high read/write speeds, high recording density, and low power consumption. Semiconductor memory is categorized into two types: volatile memory, which can store data only while powered, and non-volatile memory, which retains data even when power is removed.
Common examples of volatile memory include DRAM (Dynamic Random Access Memory), used as main memory in computers, and SRAM (Static Random Access Memory), which has significant faster and more expensive compared to DRAMs.
Non-volatile memory examples include a flash drive that retains its data even when disconnected from a computer. SSDs (Solid State Drives) are another example. These are used as both internal and external memory sources for computers and other devices.
Power Semiconductors
Power semiconductors, including those made from GaN (gallium nitride) and SiC (silicon carbide), are designed to control and convert electrical energy. Unlike other semiconductors that process information and signals (requiring relatively low power-handling capabilities), power semiconductors can handle high voltages and large currents. They perform functions such as converting direct current to alternating current (inverters) and vice versa (converters), voltage regulation, switching, and signal amplification.
These components have diverse applications. In renewable power generation, GaN and SiC semiconductors are used to convert DC power from wind and solar sources into AC power (for mains). In the automotive industry, power semiconductors, particularly those using SiC, are crucial for motor control in electric vehicles (EVs) and hybrid vehicles (HVs). In telecommunications, GaN semiconductors are employed in 5G base stations to amplify transmitted signals efficiently.
| Type of Semiconductor | Function | Products/Applications |
|---|---|---|
| Logic Semiconductors | Calculation and processing of digital signals using logic circuits | PCs, smartphones, home appliances, etc. |
| Analog Semiconductors | Process analog signals such as voltage, current, frequency, sound, pressure, etc. | Sensors, audio equipment, etc. |
| Image Sensors | Convert light input into electrical signals (output) | Digital cameras, surveillance cameras, etc. |
| Memory Semiconductors | Data storage in digital form | Storage devices such as PCs (ROM, RAM, SSD, etc.) |
| Power Semiconductors | Control and conversion of electric power (electrical energy) | Power conversion devices and power control in equipment like EVs. |
Semiconductor Manufacturing Process Overview
The semiconductor manufacturing process is divided into three major categories, from circuit design to actual production.
Overview of the Semiconductor Manufacturing Process
Semiconductor manufacturing is divided into three main processes: "design process," "front-end process," and "back-end process." The work performed in each process is as follows:
Design Process
The semiconductor design process is the first step in semiconductor manufacturing and includes the following:
Circuit Design:
Electronic circuits (logic circuits) to be placed on semiconductor chips are designed, and efficient circuit patterns are created through operational simulations.
Photomask Creation
The designed circuit pattern is drawn on a transparent glass plate, creating a master (original) copy that is used to transfer the circuit onto the wafers.
Front-End Process
The front-end process involves forming fine circuits on silicon wafers. The main steps are as follows:
Wafer Surface Oxidation
The wafer surface is oxidized at high temperatures to form an insulating oxide film/layer.
Film Deposition (Thin Film Formation)
Thin films of various materials are formed on the wafer surface. Methods include CVD (Chemical Vapor Deposition) using raw material gas decomposition and sputtering, which ionizes materials through glow discharge.
Exposure (Circuit Pattern Transfer)
The photoresist is applied to the wafer and baked. The pattern is transferred onto the photoresist using an exposure device that irradiates ultraviolet light through a photomask. EUV (Extreme Ultraviolet) light is used to process the latest fine wiring pattern.
Etching
Oxide or thin films are removed along the formed pattern, shaping the wiring area. Methods like plasma etching are used.
Ion Implantation
Impurity ions (e.g., boron and phosphorus) are implanted into the wafer surface using an ion implanter and then activated through heat treatment diffusion. They are critical to achieve the requisite semiconductor properties.
Back-End Process
The back-end process involves cutting semiconductor chips from wafers created in the front-end process and assembling them into final products. The main steps are as follows:
Dicing
The wafer is cut with a diamond blade and separated into individual semiconductor chips.
Wire Bonding
Individual semiconductor chips are fixed to metal lead frames. On their own, the chips cannot form electrical connections with circuits and devices, but when attached to the lead frames, they can be inserted, installed, mounted, or otherwise connected to an electronic device or circuit. Then, the semiconductor chips and lead frames are bonded with wire (typically gold wire) to create electrical connections.
Molding
The chip is covered with resin to protect it from environmental elements, external shocks, and physical forces that might damage it.
Final Inspection
Electrical characteristics, heat dissipation, and reliability tests are conducted to eliminate defective products and ensure adequate product quality.
Four Front-End Processes and Equipment Used
This section describes the roles of the following important processes in the semiconductor front-end process and the types of equipment (especially power supplies) required for them.
Thin Film Deposition Process
The deposition process in semiconductor manufacturing leverages multiple technologies for forming thin films on wafers. The process plays an essential role in the production of semiconductor devices.
What is Deposition?
Deposition is the process of vaporizing a solid material and depositing it as a thin film on a wafer, which is made of pure silicon in most cases, but it can also be another material like Gallium Arsenide or Silicon Carbide. There are two main deposition methods: Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD).
Physical Vapor Deposition (PVD)
In PVD, thin films are formed on wafers by physically evaporating the relevant material and depositing it on the wafer. This may be achieved using techniques such as vacuum evaporation and sputtering. In vacuum evaporation, the material is heated to a high temperature to vaporize, and the vapor is deposited on the wafer to form a thin film. In sputtering, the target material is bombarded by ions in a plasma state. They transfer enough energy into the particles of the target material to change states (from solid or liquid to gas-vapor). The scattered vaporized particles then adhere to the wafer.
Chemical Vapor Deposition (CVD)
CVD is a method of forming thin films on wafers using chemical reactions in the gas phase. A gaseous compound containing the desired material (not in its pure form) is introduced to the deposition chamber where another material, a precursor, is already present. The precursor, which is a chemical compound that can react with the introduced gas, facilitates the release of the desired material through a chemical reaction. The desired material then forms a thin film on the wafer surface. CVD is widely used in the fabrication of high-performance semiconductor devices because it allows the formation of films with high uniformity and adhesion.
Equipment Used in the Deposition Process
The main equipment used in the deposition process is as follows:
Vacuum Evaporation Equipment
This equipment is used to vaporize a substance in a vacuum to form a thin film on a substrate. Film deposition materials are heated using resistance heating or electron beam heating and evaporated to form a thin film on the wafer surface.
Sputtering Equipment
Sputtering equipment creates a plasma from source gases, generating active radicals and ions. These energetic particles react chemically with the wafer surface to form a thin film. This method offers two key advantages: it allows for film deposition at low temperatures and can uniformly create thin films from a wide variety of materials.
Plasma CVD Equipment
Plasma CVD equipment creates a plasma state from raw material gases, generating active radicals and ions that cause chemical reactions on the wafer to form thin films. This method enables film deposition at low temperatures and is capable of uniformly forming thin films of various materials.
Types and Characteristics of Power Supplies
The following are typical power supplies used in semiconductor manufacturing equipment for various deposition processes:
Sputtering DC Power Supplies
These power supplies are used for sputtering metal targets (conductive materials).
Sputtering RF Power Supplies
These high-frequency power supplies are essential when using non-conductive materials/insulators, such as oxides and nitrides, as targets.
Sputtering DC Pulse Power Supplies
These power supplies achieve high throughput while suppressing abnormal discharge during the sputtering process.
Ion Beam Power Supplies
These are high-voltage DC power supplies used in Focused Ion Beam (FIB) equipment. They feature multiple output terminals necessary for electrostatic lenses and accelerators, and are required to provide stable voltage supply.
High-Voltage Power Supplies for Plasma CVD
These power supplies provide the high voltage necessary for plasma CVD processes, supporting uniform thin film formation with stable output.
Piezo Drivers
These are specialized power supplies designed for the stable control of the displacement and vibration of various piezoelectric elements. They enable precise movement of components in deposition equipment, ensuring uniform thin film formation. Additionally, these drivers control minute vibrations during the deposition process, maintaining stability and consistency in film quality.
Matsusada Precision's Elemental Technologies
Matsusada Precision's elemental technologies used in semiconductor manufacturing's deposition process are as follows:
Matsusada designs and develops power supplies suitable for vacuum evaporation equipment, sputtering equipment, and plasma CVD used in the deposition process. Additionally, the lineup includes piezo drivers, piezo actuators, and power supplies for electrostatic chucks.
| Matsusada Precision's Elemental Technologies | Applicable Process | Function of Applicable Process | Applicable Model Number | |
|---|---|---|---|---|
| ① | DC power supply for ionization | Filament | Ionization of applicable material (Metal) | RE series, RK series, TB series, PEK/REKJ series, PRT series |
| ② | Ion beam power supply | Vacuum evaporation | Evaporation of film deposition materials | K12-R series, HIB series, AU series, RK series, TB series, KAS series |
| ③ | Plasma CVD power supply | Heater | Plasma formation of deposition materials | RE series |
| ④ | Piezo driver | Processes ① - ④ above | Power supply for wafer positioning | PZM-0.12BS series |
| ⑤ | Piezo actuator | Processes ① - ④ above | Actuator for wafer positioning | PZ series |
| ⑥ | Power supply for electrostatic chuck | Processes ① - ④ above | For accurate wafer fixation | HECD series |
Exposure Process
The exposure process encompasses the steps from photoresist application after film deposition to photoresist removal following UV irradiation.
What is Exposure?
It's the process of imprinting a circuit pattern onto a wafer. Here's a detailed explanation:
Resist (Photosensitive Agent) Application
A photosensitive material called photoresist is uniformly applied to the wafer surface. This is done through spin coating, where the resist is dripped onto the wafer as it rotates at high speed, creating a uniform thin film.
Soft Bake
After photoresist's application, the wafer undergoes a low-temperature heating process (soft bake). This evaporates the resist solvent and cures the resist film onto the wafer.
Exposure (Pattern Transfer)
A photomask containing the semiconductor circuit pattern is positioned over the resist-coated wafer. The photoresist is then exposed to ultraviolet (UV) or extreme ultraviolet (EUV) light. The photomask has areas that allow light to pass through and areas that block it. This difference in light transmission transfers the circuit pattern onto the photoresist, by casting a "shadow" of the desired circuit pattern.
Development
After exposure, the resist is treated with a developer (a chemical solution)to remove unnecessary portions. For positive resists, the exposed areas are dissolved and removed. For negative resists, the unexposed areas are dissolved. Either way, the circuit pattern is formed on the wafer.
Hard Bake
Following development, the wafer undergoes another heating process (hard bake) to cure the remaining resist further. This step enhances the durability of the pattern.
Equipment Used in the Exposure Process
The main equipment used in the exposure process is as follows:
Resist Coater
A resist coater is a device that uniformly applies photoresist onto the wafer surface.
Exposure Equipment
The exposure equipment transfers the circuit pattern from the photomask onto the wafer. Here are two common exposure methods:
Stepper Method
The stepper method scales down the circuit pattern on the photomask and transfers it onto the wafer while moving (stepping) across the wafer surface. This technique enables the formation of extremely fine circuits (such as wiring) on the wafer. When exposing resist coated on a thin film, the stepper requires very precise alignment between the light source and the wafer. Consequently, when transferring multiple circuit patterns onto the wafer, the stepper must be carefully moved across the wafer, repeating the process of imprinting the same circuit pattern.
Scanner Method
The scanner method, short for "step-and-scan," exposes the photomask and wafer simultaneously, in contrast to stepper method where only relevant segments of the wafer are exposed. Like the stepper method, it uses a scaled-down projection for exposure. However, while the stepper exposes a square area in a single shot, the scanner method exposes an elongated slit-shaped area, scanning horizontally while projecting light.
Types and Characteristics of Power Supplies
Piezo Driver Power Supplies
Piezo driver power supplies are amplifier-type units designed for stable control of the displacement and vibration of various piezoelectric elements. In exposure process equipment, each component must move with high precision to ensure uniform thin film formation. These power supplies play a crucial role in controlling minute vibrations during deposition, which is essential for producing stable and high-quality thin films.
Matsusada Precision's Elemental Technologies
In the exposure process, when photoresist is applied to thin films, steppers require extremely precise positioning between the light source and the wafer. Matsusada Precision provides piezo drivers and piezo actuators to meet this need. They are crucial for achieving the necessary level of accuracy.
The table below summarizes Matsusada Precision's elemental technologies used in the exposure process.
| Matsusada Precision's Elemental Technologies | Applicable Process | Function in Applicable Process | Applicable Model Number | |
|---|---|---|---|---|
| ① | Piezo Driver | Exposure Process | Power Supply for Wafer Positioning | PZJ series |
| ② | Piezo Actuator | Exposure Process | Actuator for Wafer Positioning | PZ series, PZA series |
Etching Process
The etching process is a crucial step that involves carving out the required circuit pattern after exposure. Here's a detailed explanation:
What is Etching?
In semiconductor manufacturing, the etching process is a critical stage for creating fine circuit patterns. This process selectively removes specific/unwanted parts of the deposited material/films, resulting in patterns and precise dimensions following the design specifications, allowing for intended semiconductor or IC creation. There are two primary etching methods: "wet etching" and "dry etching," each with distinct characteristics and applications.
Wet Etching
Wet etching utilizes liquid chemicals to dissolve the surface of semiconductor materials and remove unwanted portions. This technique offers advantages such as low cost and high productivity. However, it's less suitable for fine patterning due to its isotropic nature, meaning it etches in all directions equally. It cannot account for variations in the "depth" of the etch, preventing it from achieving the level of finesse and precision required for many semiconductors and ICs. Both acidic or alkaline etchants are used to remove material through chemical reactions, and both may offer different results for different materials.
Dry Etching
Dry etching employs plasma or gas to remove materials, allowing for high-precision processing. There are several types of dry etching, including plasma etching. In this technique, gas is ionized into a plasma state, and the generated ions are directed onto the semiconductor surface to selectively remove material. This method provides high anisotropy (directional etching) and selectivity, enabling the formation of fine circuit patterns.
Equipment Used in the Etching Process
The etching process employs sophisticated equipment that utilizes plasma and gases to achieve high-precision processing. To perform selective etching on specific semiconductor materials, the industry currently relies on plasma etching equipment and reactive ion etching (RIE) equipment.
Plasma Etching Equipment
Plasma etching is a method that uses plasma to etch the wafer surface. Similar to plasma CVD, gas flows over the wafer surface and is then ionized into a plasma state. In this process, ions collide with the wafer, causing chemical reactions with the substances on the surface (the segments that need to be removed). Following the chemical reaction, the unwanted segments are removed from the wafer surface.
Reactive Ion Etching Equipment
Reactive Ion Etching (RIE) is a dry etching technology used in semiconductor manufacturing that utilizes ions and radicals in plasma to process the wafer surface. It employs a high-frequency electric field to generate plasma. The highly precise anisotropic etching is achieved through the vertical collision of ions with the wafer and chemical reactions caused by radicals. RIE has become a mainstream etching process due to its ability to create fine circuit patterns at the nanometer scale.
Electrostatic Chuck
An electrostatic chuck is a device that secures a wafer (workpiece) using electrostatic force generated between the wafer and the chuck. During the etching process, it's crucial to keep the wafer stationary. However, due to the delicate nature of wafers, mechanical chucks are not suitable. This is where electrostatic chucks come into play.
The principle behind an electrostatic chuck is as follows: When positive and negative voltages are applied to two internal electrodes within the chuck, electric charges in the workpiece are attracted to their respective electrodes. This movement of charges creates an attractive force between the electrostatic chuck and the workpiece. This attractive force is utilized to firmly hold the wafer in place, preventing any movement during the etching process.
Types and Characteristics of Power Supplies
Dry etching is predominantly used in semiconductor manufacturing's etching process. The power supplies employed in this process include the following types:
High-Frequency Power Supplies (RF Power Supplies)
In dry etching processes, high-frequency power supplies, or RF power supplies, are commonly used. These power supplies provide the necessary energy to ionize the reaction gas into plasma. The RF power supply plays a crucial role in regulating the density and temperature of the plasma, which directly impacts the precision of the etching process.
Power Supplies for Electrostatic Chucks
These are high-voltage power supplies designed to drive electrostatic chucks. They are compatible with electrostatic chucks, regardless of whether they are using Coulomb force or Johnsen-Rahbek force.
Matsusada Precision's Elemental Technologies
The elemental technologies from Matsusada Precision used in the etching process are summarized in the following table.
| Matsusada Precision's Elemental Technologies | Applicable Process | Function in Applicable Process | Applicable Model Number | |
|---|---|---|---|---|
| ① | Piezo Driver | Plasma Etching Equipment | Power Supply for Wafer Positioning | PZJ series |
| ② | Piezo Actuator | Plasma Etching Equipment | Actuator for Wafer Positioning | PZ series, PZA series |
| ③ | Power Supply for Electrostatic Chuck |
|
For accurate wafer fixation. Electrostatic chuck technology holds the workpiece using electrostatic force generated between the workpiece and the chuck | HECD series, ECU series, EJC series, ECA series, EC series, MEC series |
Ion Implantation Process
The ion implantation process is a crucial step in semiconductor manufacturing that alters the electrical characteristics of semiconductor devices. Here's a detailed explanation:
What is the Ion Implantation Process?
Ion implantation is a vital process in semiconductor manufacturing where impurities (dopants) are introduced into silicon wafers to modify their electrical properties. This process consists of several key steps:
Ionization and Acceleration
In the ion implantation process, impurity elements (like boron or phosphorus) are ionized and then accelerated at high voltages, driving these ions into the silicon wafer.
Implantation Process
When ions are bombarded onto the silicon crystal, the affected area becomes amorphous. A subsequent heat treatment restores the crystalline structure, allowing dopants to settle into correct positions, thus enabling proper semiconductor functionality.
Equipment Used in the Ion Implantation Process
The ion implanter used in the ion implantation process consists of the following components:
- ①Ion source: Generates the desired ions
- ②Mass analyzer: Extracts the required ions
- ③Acceleration tube: Accelerates ions
- ④Scanner: Scans the ion beam
- ⑤Deflector: Controls the ion beam's incident position
- ⑥Q-lens:Focuses the spread ion beam using a magnetic field
- ⑦Extraction electrode:Extracts generated ions using an electric field
- ⑧Analysis slit: Improves mass spectrometry resolution
Types and Characteristics of Power
Power supplies for ion implanters include the following:
- ① High-voltage filament power supplies for ion sources
- ② High-voltage power supplies for extraction electrodes
- ③ Constant current power supplies for analyzer magnets
- ④ High-voltage power supplies for ion acceleration
- ⑤ High-speed, high-voltage bipolar power supplies for ion beam scanning
- ⑥ High-voltage power supplies for secondary electron suppression
Matsusada Precision's Elemental Technologies
Matsusada Precision offers a comprehensive range of power supplies for ion implantation processes. Their lineup includes high-voltage filament power supplies for ion sources, high-voltage power supplies for extraction electrodes, and constant-current power supplies for analyzer magnets. They also provide high-voltage power supplies capable of up to 200 kV for ion acceleration, high-speed high-voltage bipolar power supplies for ion beam scanning, and high-voltage power supplies for secondary electron suppression. The following table summarizes Matsusada Precision's elemental technologies for the ion implantation process.
| Matsusada Precision's Elemental Technologies | Applicable Process | Function in Applicable Process | Applicable Model Number | |
|---|---|---|---|---|
| ① | Ion Beam Power Supply | Ion Implantation | High-voltage filament power supply | HIB series, RE series |
| ② | High-voltage, High-power, High-performance Power Supply | Ion Implantation | Ion Implantation Various power supplies for ion implanter | AKP series, AU series, AK series, RE series, AMPS series, AMP series, PEK/REKJ series |
Conclusion
The semiconductor manufacturing process comprises three stages: design, front-end, and back-end processing. The front-end process involves four critical steps: deposition, exposure, etching, and ion implantation. Each of these processes requires specialized equipment and power supplies.
The deposition process utilizes sputtering equipment and plasma CVD equipment, while the exposure process employs stepper or scanner equipment, depending on specific application requirements. Each process uses optimized power supplies tailored to its unique needs.
Matsusada Precision offers a comprehensive range of solutions for these processes, including high-frequency power supplies, piezo drivers, and high-voltage power supplies for electrostatic chucks.