MICRONAS - Micronas Backend Overview

Summary

The video script details the backend production process at Micronus, focusing on the meticulous testing and assembly of integrated circuits. It showcases the use of special equipment for parameter testing, probe cards for individual die testing, and the precise placement of components. The process includes dicing silicon wafers, bonding dice onto lead frames, and wire bonding. Quality control measures such as mechanical tests and statistical process control ensure reliability. The components are then molded, trimmed, and inspected, with final checks at extreme temperatures to simulate real-world applications. Each component is marked with a laser for identification, ensuring high-quality standards from Micronus.

Takeaways

• 📦 Silicon wafers are transported in dust-type boxes from the wafer fabrication facility to the backend production area.
• 🔬 A comprehensive testing process includes a parameter test to ensure the integrated circuit properties meet specifications.
• 📌 Individual die testing uses probe cards with up to 130 needles, precisely aligned to aluminum contact openings.
• 🎨 Defective ICs are marked with a small colored dot for later elimination.
• 🔄 Both digital and analog circuits are tested, with up to 500 tests required for a typical IC.
• ⚙️ The assembly area involves dividing tested wafers into individual dice using a dicing process with diamond-bladed saws.
• 🧲 Dice are bonded onto copper lead frames using an epoxy resin adhesive, which hardens in a furnace at 145°C.
• 🔗 Multi-chip assemblies require precise bonding and wire connections, with 276 individual wire connections applied in under 50 seconds.
• 🔬 Extensive quality inspections and statistical process control are used to maintain process parameters within specification limits.
• 🛡️ Components are molded with a plastic compound containing ultrafine glass particles to protect sensitive wire connections and prevent corrosion.
• 🔍 Post-molding, components undergo X-ray inspection to ensure the integrity of the gold wires and positioning.
• 🏷️ Each component is marked with a laser beam, including type, manufacturing date, and batch number for traceability and quality control.

Q & A

What is the first test conducted on the silicon wafers in the backend production process?

The first test conducted on the silicon wafers is the parameter test, which ensures that the properties of the integrated circuit, such as specific transistor characteristics, comply precisely with the specifications.

How are the individual needles of the probe card positioned during testing?

The individual needles of the probe card have to be accurately positioned on the aluminium contact openings, which are only about 100 micrometers in size.

What is done to mark defective integrated circuits during the testing phase?

Defective integrated circuits are marked with a small colored dot on the wafer, which allows for their elimination at a later stage.

How many tests are typically necessary to check the digital and analog circuits in a micronus IC?

In a typical case, 500 tests are necessary to check the digital and analog circuits in a micronus IC.

What is the purpose of the adhesive film used when mounting the wafers in a metal frame?

The adhesive film ensures that the dice remain in their original position even after they've been sawn apart and that the wafer can be further processed in a reliable manner.

What is the width of the saw blades used in the dicing process?

The saw blades used in the dicing process are fitted with minute diamonds and are only 30 micrometers wide.

How are the individual dice picked up after the dicing process?

The individual dice are picked up by fully automatic machines with an integrated imaging system, which corrects any positioning errors.

What is the role of the copper strips in the assembly area?

The copper strips, also known as lead frames, form the electric contact with the printed circuit board and are bonded onto the dice with an epoxy resin adhesive.

How is the electric contact between the aluminium contact surfaces on the dice and the fingers of the copper lead frame achieved?

The electric contact is achieved through a thin gold wire, which is welded on by fully automatic wire bonders at a temperature of 200° C with the aid of pressure and ultrasonic energy.

What is the purpose of the plasma cleaning operation after the silver conducting adhesive has been hardened?

The plasma cleaning operation serves to remove any organic contamination on the contact surfaces of the printed circuit board or the dice.

How is the quality of the components ensured during the molding process?

Quality is ensured through extensive quality inspections, such as mechanical pull tests and statistical process control, which keeps individual parameters within specification limits.

Outlines

00:00

🔍 Quality Assurance in Micronus Wafer Fab

The script describes the meticulous quality control processes at Micronus's back-end semiconductor manufacturing facility. Wafers are tested for compliance with specifications using special test equipment and structures. A parameter test is conducted to ensure the integrated circuits' properties meet the required standards. Each die is individually tested using probe cards with precision alignment on tiny contact openings. Defective ICs are marked and later eliminated. The wafers are then divided into individual dice using a dicing process with diamond-coated blades. The dice are picked up by machines with imaging systems to correct any positioning errors. Defective dice are left on the adhesive film, while the rest are bonded onto copper strips for electrical contact with the printed circuit board. The process involves both in-house and purchased memory chips, with a high level of precision and quality control to ensure customer satisfaction.

05:01

🔧 Backend Production Process at Micronus

This paragraph details the backend production process at Micronus, where expert employees and advanced equipment work continuously to ensure quality. After the adhesive is hardened, a plasma cleaning operation removes organic contamination from the contact surfaces. Electric contact is established through gold wire bonding, which is applied by automatic machines at high temperatures and with ultrasonic energy. Quality inspections are conducted, including mechanical tests and statistical process control to maintain parameters within specification limits. Components are molded with a plastic compound under high pressure to protect the wire connections and prevent corrosion. The molding compound is made of a thermoset material with ultrafine glass particles to minimize thermal expansion differences with the silicon dice. The molded components are inspected using an X-ray microscope to confirm the integrity of the gold wires. The copper lead frame's leads are then cut in a stamping process to separate the components.

10:02

🛠 Final Processing and Quality Checks at Micronus

The final steps in Micronus's production process involve electrochemically plating the copper lead frame to facilitate further processing by customers. The electroplated leads are then trimmed and shaped before being separated into transport trays. Micronus conducts comprehensive checks to ensure the functionality of both digital and analog circuits at various temperature ranges, simulating real-world operating conditions. Components that fail to meet specifications are scrapped. Each component is marked with a laser beam, indicating type, manufacturing date, and batch number for identification and traceability. Before storage, a complex imaging system checks the leads against package specifications to ensure they are suitable for automated customer processing. The process concludes with a commitment to delivering high-quality soldered joints and components.

Keywords

💡Multichip

A multichip refers to an integrated circuit that contains multiple chips or dies on a single substrate. This technology allows for the integration of various functionalities into one compact unit. In the context of the video, multichip production is highlighted as a complex process that involves testing, assembly, and bonding of different types of chips onto a single substrate, showcasing the advanced capabilities of the manufacturing process.

💡Parameter Test

The parameter test is a quality control measure used in semiconductor manufacturing to ensure that the properties of the integrated circuits, such as specific transistor characteristics, comply with the design specifications. This test is crucial for monitoring the process parameters employed in the fabrication of wafers. In the video, the parameter test is mentioned as an initial step to ensure the integrity of the integrated circuits before further processing.

💡Probe Cards

Probe cards are tools used in the semiconductor industry to make electrical contact with the tiny contact pads on integrated circuits for testing purposes. They contain numerous needles, each of which must be accurately positioned on the aluminum contact openings. The video describes how these cards are used to conduct tests on individual dice on the wafer, highlighting the precision required in the testing process.

💡Dicing

Dicing is the process of cutting a wafer into individual dice or chips using a high-precision saw with diamond-coated blades. This process is critical in the backend of semiconductor manufacturing as it separates the wafer into individual units that can be assembled into final products. The video script mentions dicing as a fully automatic process where wafers are cut into individual dice with blades that are only 30 micrometers wide.

💡Lead Frame

A lead frame is a metal structure that supports and electrically connects the semiconductor die to the external circuitry. It is used as a base for the die and provides the necessary electrical connections through its leads. In the video, lead frames are mentioned as a key component in the assembly process, where they form the electric contact with the printed circuit board.

💡Wire Bonding

Wire bonding is a process used to create electrical connections between the semiconductor die and the lead frame by attaching thin gold wires. This is done using specialized equipment that applies pressure and ultrasonic energy to weld the wires. The video emphasizes the precision and speed of this process, with a multi-chip requiring 276 individual wire connections applied in less than 50 seconds.

💡Molding Compound

A molding compound is a plastic material used to encapsulate the semiconductor device, providing protection from mechanical damage and environmental factors such as moisture. The video describes the use of a thermoset molding compound containing ultrafine glass particles to minimize the difference in thermal expansion between the compound and the silicon die, ensuring reliable long-term performance.

💡Plasma Cleaning

Plasma cleaning is a process used to remove organic contamination from surfaces, such as the contact surfaces of dice or printed circuit boards. This is an important step in the semiconductor manufacturing process to ensure the quality of electrical connections. The video mentions plasma cleaning as a step that follows the hardening of the silver conducting adhesive, emphasizing the attention to cleanliness in the production process.

💡Quality Inspection

Quality inspection is a critical part of the semiconductor manufacturing process, involving various tests and checks to ensure that the components meet the required specifications. The video script describes extensive quality inspections, including mechanical pull tests and statistical process control, to detect and correct any deviations from the set point values, ensuring the components' reliability and performance.

💡Coefficient of Thermal Expansion (CTE)

The coefficient of thermal expansion (CTE) is a measure of how much a material expands or contracts with changes in temperature. In the context of the video, the CTE of the molding compound is discussed as an important factor to consider when selecting materials for encapsulating the semiconductor devices. A compound with a CTE that closely matches that of the silicon die helps to prevent mechanical stress and failure due to thermal cycling.

💡Laser Marking

Laser marking is a process used to permanently inscribe information onto a component's surface using a laser beam. This is typically used for identification purposes, such as marking the type, date of manufacture, and batch number of a semiconductor component. The video mentions laser marking as the final step before the components are sent to the sales warehouse, ensuring that each component can be precisely identified for quality control and customer service purposes.

Highlights

Micronus uses dust-type boxes for transporting processed silicon wafers from the wafer Fab.

Wafers undergo comprehensive testing with special equipment to ensure circuit properties meet specifications.

Parameter tests are conducted using test structures to monitor process parameters in the wafer Fab.

Individual die testing is done with probe cards containing up to 130 needles for precise electrical contact.

Defective ICs are marked with colored dots for later elimination.

Most micronus ICs require 500 tests, conducted in under three seconds.

Wafers are mounted in metal frames with adhesive film for dicing into individual dice.

Dicing process uses saw blades with minute diamonds, turning at over 30,000 rotations per minute.

Automatic machines with imaging systems pick up dice, correcting any positioning errors.

Defective dice are left on the adhesive film, while others are bonded onto copper strips.

Copper strips form the electric contact with the printed circuit board, also known as lead frames.

Silver conducting adhesive with silver particles is used for bonding and hardened in a furnace.

Multichip assembly involves bonding additional dice onto the printed circuit board with high precision.

Gold wire, only 25 micrometers thick, is used for electric contact between dice and lead frame fingers.

Quality inspections include mechanical tests and statistical process control to maintain parameter limits.

Components are molded with a plastic compound containing ultrafine glass particles to match thermal expansion.

Molding compound quality is critical for long-term reliability of the finished components.

X-ray microscope inspection confirms that molding has not affected the position of gold wires.

Leads of the copper lead frame are electrochemically plated for further processing by customers.

Components are subjected to temperature tests simulating minimum or maximum operating conditions.

Each component is marked with a laser beam containing type, date of manufacture, and batch number.

Final quality check ensures leads correspond precisely to package specifications for automatic customer processing.

Transcripts

back end at micronus taking the example

of multichip

[Music]

production the ready processed silicon

Wafers are supplied in dust type boxes

from the micronus wafer Fab next door

all the Wafers are now put through a

comprehensive range of tests with the

aid of special test

equipment first of all the so-called

parameter test is conducted this is

performed with test structures specially

generated for the purpose which are

arranged between the actual dice the

parameter test makes sure that the

properties of the integrated circuit

such as specific transistor

characteristics comply precisely with

the specifications this test thus

monitors the process parameters imployed

in micron's wafer Fab the next test is

conducted on each individual die on the

wafer the electrical contacts are made

with so-called probe cards which contain

up to 130

needles the individual needles have to

be accurately positioned on the

aluminium contact openings which are

only about 100 micrometers in size

defective ic's are marked with a small

colored dot on the wafer and eliminate

it at a later stage most micronus ic's

contain both digital and analog circuits

in a typical case 500 tests are

necessary to check these ic's tests that

are conducted in less than three

[Music]

seconds in the assembly area the tested

Wafers now have to be divided up into

individual

[Music]

dice first of all the Wafers are mounted

in a metal frame with the aid of an

adhesive film only 70 microm

[Music]

thick

the film that's clamped in the Metal

Frames ensures that the dice remain in

their original position even after

they've been swn apart and that the

wafer can be further processed in a

reliable

[Music]

manner the wafer is now aligned fully

automatically and cut into individual

dice with saw blades process also known

as

dicing the S blades are fitted with

minute diamonds and are only 30 micromet

wide they turn at more than 30,000

rotations per

minute deionized water is used to cool

the sore blade and to remove the Silicon

dust that's

[Music]

created

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the individual dice are picked up by

fully automatic machines with an

integrated Imaging system and any

positioning errors are

corrected the defective dice previously

marked with a small colored dot or the

defective printed circuit board in the

case of multichip assembly are left on

the adhesive

film the remaining dice or in this

particular case a small printed circuit

board are bonded onto copper strips with

an epoxy res

[Music]

adhesive these copper strips

subsequently form the electric contact

with the printed circuit board they're

also known by the technical term of lead

frames the silver conducting adhesive

which is filled with silver particles is

hardened for 45 minutes in a continuous

furnace operating at 145°

[Music]

C

in multichip assembly two further dice

are now bonded onto the printed circuit

board in a further bonding

operation one of the dice comes from the

micrones wafer Fab and is processed as a

diced wafer in the manner already

[Music]

described

the second die is a memory chip that has

been purchased it's been fully tested

and is supplied on surf

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tapes the fully automatic machine

employed for this process is able to

process both dice at one and the same

time and position them with a degree of

precision in excess of 25

[Music]

micromet to ensure the necessary high

quality is achieved in the elaborate

process steps performed in backend

production expert employees and state

of-the-art equipment work Right Round

the

[Music]

Clock after the silver conducting

adhesive has been hardened once again

during a second run through the furnace

a plasma cleaning operation takes place

this serves to remove any organic

contamination on the contact surfaces of

the printed circuit board or the

[Music]

dice the electric contact between the

aluminium contact surfaces on the dice

and the fingers of the copper lead frame

is achieved through a thin gold wire

wire this is welded on by fully

automatic wire bonders at a temperature

of 200° C with the aid of pressure and

ultrasonic

energy a multi-chip requires 276

individual wire connections which are

applied in less than 50

seconds

[Music]

[Music]

the gold wire which is only 25

micrometers thick ensures a perfect

electric

contact to ensure that any deviations in

the process are detected as early on as

possible extensive quality inspections

are carried out such as this mechanical

pool

test statistical process control is used

to keep the individual parameters within

the specification limits on the basis of

so-called control charts any deviations

from the set point values are detected

in this way and can be corrected without

delay this guarantees liability which in

turn ensures that we meet our customers

quality

demands

[Music]

to protect the sensitive wire

connections from mechanical damage and

to prevent the Silicon Dice from

corroding through moisture all the

components are molded with a plastic

compound under high pressure at a

temperature of 175°

C the plastic compound used is a

thermoset which contains more than 80%

ultrafine glass particles as a filler

this ensures that the difference between

the coefficient of thermal expansion of

the molding compound and the Silicon Dy

is kept as small as possible the quality

requirements placed on the molding

compound in terms of processibility

Purity and specified mechanical

properties are extremely high they

ensure that the finished components will

operate reliably over a very long period

of

[Music]

time

when the molded component is inspected

in an x-ray microscope a highly enlarged

shadow image of the Interior is seen

this serves to confirm that the molding

operation has not changed the position

or course of the fine gold

[Music]

wires after the molding operation the

individual leads of the copper lead

frame are still all connected to each

[Music]

other this so-called Dam bar is now cut

in a stamping

[Music]

process

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the surface of the copper lead frame

that's still bare is now

electrochemically plated in The Next

Step this ensures that the finished

components can then be further processed

by the customer without any

[Music]

problems

the electroplated leads now have to be

trimmed to the right length and given

their final shape in a number of

different forming

[Music]

stages after this the individual

components are separated and placed in

transport

[Music]

trays

micronus then conducts another full

check to ensure that the digital and

analog circuits on all the finished

components are working perfectly this

check is conducted at -45° C at ambient

temperature and at plus 95° C depending

on the

requirements these values simulate the

minimum or maximum operating temperature

of the components that can occur in a

subsequent application of the

customers

components that don't comply with all

the specified properties such as if

electrical parameters have been

adversely affected through the molding

process are eliminated after this

process step and

[Music]

scrapped

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as the final step each component is

marked with a laser

beam this inscription contains the type

date of manufacturer and the batch

number it's also used for precise

identification in the event of a

customer

[Music]

complaint before the components are

taken to the sales Warehouse a check is

conducted with a complex Imaging system

to ensure that the leads correspond

precisely to the package

[Music]

specification this ensures that our

customers can further process the

products we deliver by predominantly

automatic means and above all it means

that the solded joints we Supply are all

perfect

quality from

[Music]

micronus