Understanding chip manufacturing from fourteen core materials: "domestic substitution" will become inevitable

High-purity electronic special gases commonly used in semiconductor manufacturing

According to data from SEMI and IC Mtia, the global market size of electronic special gases was approximately US$3.68 billion in 2016, of which the domestic market size was approximately RMB 4.6 billion. The leading companies in the global electronic special gases market are mainly Air Products and Chemicals and Praxair in the United States, Air Liquide of France, Linde Group, and Taiyo Nippon Sanso of Japan.

Photoresist

Photoresist is a pattern transfer medium that uses different solubility after light reaction to transfer the mask pattern to the substrate. It is currently widely used in the processing and production of fine pattern circuits in the optoelectronic information industry and is a key material in the field of electronic manufacturing. Photoresist is generally composed of photosensitizer (photoinitiator), photosensitive resin, solvent and additives, among which photoinitiator is the core component and plays a decisive role in the sensitivity and resolution of photoresist. Photoresist can be divided into positive photoresist and negative photoresist according to different chemical reaction principles.

Taking semiconductor photoresist as an example, in the photolithography process, the photoresist is evenly coated on the substrate, and after exposure (changing the solubility of the photoresist), development (using the developer to dissolve the soluble part of the modified photoresist) and etching, the pattern on the mask is transferred to the substrate to form a geometric pattern that completely corresponds to the mask. The photolithography process accounts for about 35% of the total chip manufacturing cost and 40-60% of the total chip process time. It is the most core process in semiconductor manufacturing.

According to data from SEMI and IC Mtia, the global photoresist market size was approximately US$1.44 billion in 2016, of which the domestic market size was approximately RMB 2 billion. The global photoresist market is mainly monopolized by companies in countries and regions such as Europe, the United States, Japan, South Korea, and Taiwan.

Sputtering Target

The principle of using sputtering targets is to use the ions generated by the ion source, which are accelerated and gathered in a high vacuum to form a high-speed energy ion beam to bombard the solid surface. The ions and the atoms on the solid surface exchange kinetic energy, causing the atoms on the solid surface to leave the solid and deposit on the substrate surface. The bombarded solid is the raw material for depositing thin films by sputtering, so it is called a sputtering target.

The unit device of a semiconductor chip is composed of a substrate, an insulating layer, a dielectric layer, a conductor layer and a protective layer, among which the dielectric layer, the conductor layer and even the protective layer all require sputtering coating technology. The targets used for coating in the field of integrated circuits mainly include aluminum targets, titanium targets, copper targets, tantalum targets, tungsten-titanium targets, etc., and the target materials are required to have a very high purity, generally above 5N (99.999%).

The world's leading sputtering target companies are mainly Honeywell and Praxair in the United States, and Nippon Mining and Metals, Sumitomo Chemical, ULVAC, Mitsui Mining and Tosoh in Japan.

3. Packaging materials 

Semiconductor packaging refers to the process of processing the tested wafers into independent chips according to the product model and functional requirements. The packaging process is as follows: the wafers from the wafer front-end process are cut into small chips (Die) through the dicing process, and then the cut chips are glued to the corresponding substrate (lead frame) frame island, and then the ultra-fine metal (gold, tin, copper, and aluminum) wires or conductive resins are used to connect the bonding pads (Bond Pad) of the chip to the corresponding pins (Lead) of the substrate to form the required circuit; then the independent chips are packaged and protected with a plastic shell, and a series of operations are required after the plastic packaging. After the packaging is completed, the finished product is tested, usually after the incoming inspection, test test and packaging Packing process, and finally shipped. The materials needed for the entire packaging process mainly include chip bonding materials, ceramic packaging materials, bonding wires, lead frames, packaging substrates, cutting materials, etc.

Die Attach Materials

Chip bonding materials are materials that use bonding technology to connect the die to the base or packaging substrate. In terms of physical and chemical properties, they must meet the requirements of high mechanical strength, stable chemical properties, electrical and thermal conductivity, low curing temperature and strong operability. In practical applications, the main bonding technologies include silver paste bonding technology, low melting point glass bonding technology, conductive adhesive bonding technology, epoxy resin bonding technology, and eutectic welding technology. Epoxy resin is a widely used bonding material, but the surface of the chip and the basic packaging material presents different hydrophilicity and hydrophobicity. The surface needs to be plasma treated to improve the fluidity of the epoxy resin on its surface and improve the bonding effect.

Schematic diagram of chip bonding material (taking package solder ball as an example)

According to data from SEMI and IC Mtia, the global market size of chip bonding materials in 2016 was approximately US$750 million, of which the domestic market size was approximately RMB 2 billion.

Ceramic packaging materials

Ceramic packaging materials are a type of electronic packaging materials, used to carry mechanical support, environmental sealing and heat dissipation functions of electronic components. Compared with metal packaging materials and plastic packaging materials, ceramic packaging materials have good moisture resistance, good linear expansion coefficient and thermal conductivity, and extremely stable performance in terms of electrothermal mechanics, but the processing cost is high and it has high brittleness. At present, the ceramic substrate materials used in actual production and development and utilization mainly include Al2O3, BeO and AIN. In terms of thermal conductivity, BeO and AIN substrates can meet the requirements of natural cooling. Al2O3 is the most widely used ceramic material. BeO has certain toxic side effects. AIN with excellent performance will gradually replace the other two ceramic packaging materials.

Examples of Al2O3 electronic ceramic packaging materials

According to SEMI data, the global ceramic packaging material market size in 2016 was approximately US$2.17 billion, accounting for about 11% of the total packaging material market size, of which the domestic market size was approximately RMB 3.5 billion. The global leading companies are mainly Japanese companies, such as Kyocera, Sumitomo Chemical, and NTK Corporation.

Package substrate

The packaging substrate accounts for the largest proportion of the packaging material cost, and it mainly plays the role of carrying and protecting the chip and connecting the upper chip and the lower circuit board. The complete chip is composed of a bare chip (wafer) and a package (package substrate and sealing materials, leads, etc.). The packaging substrate can protect, fix and support the chip, enhance the thermal conductivity and heat dissipation performance of the chip, and can also connect the chip to the printed circuit board to achieve electrical and physical connection, power distribution, signal distribution, and communication between the internal and external circuits of the chip.

Early chip packaging usually used lead frames as carriers for connecting chips and supporting chips. However, as IC feature sizes continue to shrink and integration continues to increase, only packaging substrates can expand the interconnection area from lines to surfaces, thereby reducing the package volume. Therefore, there is a trend for traditional lead frames to gradually become the mainstream high-end packaging material.

Package Substrate Example (CSP Series)

Packaging substrates can generally be divided into three categories: organic, inorganic and composite. Each has its own advantages and disadvantages in different packaging fields. Organic substrates have a low dielectric constant and are easy to process, which are suitable for high-frequency signal transmission with low thermal conductivity requirements; non-polar substrates are supported by inorganic ceramics, have good heat resistance, easy wiring and dimensional stability, but have certain limitations in cost and material toxicity; composite substrates are composed of different organic and inorganic materials according to different requirements. In the future, organic and composite substrates are expected to be the mainstream substrate materials.

According to data from SEMI and IC Mtia, the global market size of organic substrates and ceramic packages reached US$10.45 billion in 2016, accounting for 53.3% of all packaging materials, and the domestic market size was about RMB 8 billion, accounting for 30% of all packaging materials. The leading global packaging substrate companies are mainly Ibiden, Kobelco and Kyocera in Japan, Samsung Electro-Mechanics, Suntech Electronics and Dade Electronics in South Korea, UMTC, Nanya Circuits, Kinsus Technology in Taiwan and other companies.

Bonding Wire

Semiconductor bonding wire is used to weld and connect chips and brackets, and it plays a key role in the electrical connection between chips and the outside world. The material of bonding wire has gradually developed from a single material in the past to a variety of products composed of gold, silver, copper, aluminum and related composite materials. According to different application fields and needs, different metal composite wires can be selected.