Semiconductor knowledge explanation: PVD knowledge 30 questions
Nov 27, 2024
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01
What is Target?
Answer: In PVD, the target is a metal material that is used to provide a film.
02
What is the principle of PVD process?
Answer: In addition to the high potential difference between the target and the wafer, the process gas Ar is dissociated into Ar under the high level difference, and then the Ar is positively attracted by the electric field and collides with the target, so that the metal grains generated by the target fall to the wafer to form a film due to gravity, this process is PVD
.
03
What is the material of general metal wire in semiconductors?
Answer: Tungsten wire (W) / aluminum wire (Al) / copper wire (Cu).
04
What kinds of metal films can be obtained in PVD?
Answer: Aluminum (AL), titanium (Ti), titanium nitride (TiN), cobalt (Co). Generally, when wafer enters the PVD machine, it must be plated with titanium/titanium nitride/aluminum/titanium/titanium nitride. Five-layer metal, cobalt functions as silicide.
05
What is the function of titanium (Ti)?
Answer: Reduce the metal contact resistance.
06
What is the function of titanium nitride (TiN)?
Answer: (1) As a diffusion barrier layer, it blocks the diffusion between aluminum and silicon oxide. (2) As an adhesive layer, tungsten and silicon oxide do not adhere well, and adding titanium nitride between the two can increase the adhesion to each other. (3) As an ARC layer, an anti-reflective layer is required to reduce the high reflectivity from aluminum in order to achieve high resolution in the microimaging process.TIN Chamber is the container where the process occurs.
07
After the chamber is on standby for a period of time, why do you need to do Dummy?
Answer: After the chamber is on standby for a period of time, the chamber condition (vacuum, temperature) changes slightly. If you don't do dummy, the first few pieces of product will be affected. Generally, the process engineer formulates the standby time rules according to the actual state, and then the manufacturing operator puts the stall into the chamber coating (its recipe is similar to the recipe of the product). After DUMMY, the chamber condition will return to normal level, so you can produce with peace of mind.
08
Why do I need to add a small amount of copper to the aluminium target?
Answer: When the current moves in the aluminum metal layer, the aluminum atoms will move along the grain interface, if this phenomenon is too sharp, it will cause the metal wire to break, adding a small amount of copper can prevent the aluminum wire from breaking.
09
Since adding copper can prevent aluminum spikes, why only add 0.5%?
Answer: Too much copper will cause etching difficulties (copper chloride is not volatile).
10
Why do PVD targets need to be cooled?
Answer: Avoid the surface temperature of the target is too high, which will cause the evaporation phenomenon, and make the quality of the metal film unstable.
11
Why is it necessary to control the purity of the water when the machine must use cooling water?
A: Prevent scaling, or insulation.
12
Why do process gas lines have to be heated?
Answer: Prevent the process gas from condensing into liquid, which will affect the process.
13
What is PM? Why tools need PM?
Answer: PM is preventive maintenance, and corresponding maintenance or replacement measures are taken for the corresponding parts (spare parts) of the machine according to the cycle, in order to maintain the stability of the performance of the machine, prevent the decline of process yield, and prolong the life of the machine and Parts.
According to the schedule, it can be divided into monthly maintenance, quarterly maintenance, and annual maintenance.
According to the number of wafers, it is for quantity maintenance.
14
Why does an engineer have to cool the heater to the appropriate temperature when doing PM?
A: For the safety of engineers and machines.
15
Why does the chamber have to bake out when the engineer does PM?
A: In order to exhaust gas, prevent impure gases from entering the film and affecting the process.
16
What role do PVD and W-CVD play in IC manufacturing?
A: Aluminum and tungsten are metal layers, and the wires that connect the device and the package form a path between them, so that the current can flow unimpeded.
17
What is Bake out?
Answer: When the engineer does PM, when the chamber is opened, the inside of the chamber is exposed to the atmosphere, and when the engineer finishes the PM, he must do a bake out, heat the chamber, and drive away the water molecules and other gases attached to the inside, so as to increase the vacuum level.
18
What is the gas used in the PVD process?
Answer: N2 vs. Ar.
19
What is the purpose of N2 and Ar in PVD process?
Answer: After Ar is ionized by electrons, the bullet that becomes the target hits the target and knocks down the atoms of the TARGET on the wafer, and the purpose of N2 is to nitride the surface atoms of the target.
20
Why use Ar as a gas source for PVD sputtering?
Answer: (1) Blunt gas, not easy to chemical changes. (2) Heavy mass (AMU 40), good splashing effect. (3) The price is cheap.
21
What is the process pressure of PVD?
A: 2~20 mTorr.
22
PVD Measuring Machine Project: Why?
A: Reflectivity index, thickness, resistance sheet, particle, uniformity.
23
Why does the machine use helium for leak detection?
Answer: (1) The amount of helium in the atmosphere is very low, so avoid miscalculation. (2) Helium has strong permeability and is easy to detect leaks. (3) Helium is a blunt gas, which is not easy to cause pollution or corrosion.
24. In the PVD process, why do I need to remove the original oxide layer before coating?
A: The original oxide layer is removed in advance so that the resistance between the metal layers is not too large and the adhesion between the film and the substrate is increased.
25. Why does PVD use DC power?
Answer: Using DC power, coupled with a certain amount of argon (Ar gas), plasma (plasma) will be formed in the vacuum chamber. The ions in the ion metal hit the target, knocking the atoms of the target down on the wafer and forming a metal film.
26.Why do machines need to use cooling water?
Answer: Control the temperature to prevent the temperature from being too high and causing damage to the machine.
27.What is Process kit?
Answer: A shield is formed inside the chamber, and the coating can prevent the coating from being plated inside the chamber, and it can be removed for cleaning or replacement every time it is PM. 0020-40946 CLAMP RING, 8" SNNF, AL, 0020-27113 CLAMP RING 6 SMF TI,0020-24896 COVER RING 6" SST 101 AL,0020-28205 6" TI COVER RING,0021-35946 Edge Ring, TXZ, 200MM, SNNFare all metal parts of process kits.0200-00221 INSULATOR QUARTZ, 8' and 0200-00218 Cover Top Quartz 8" PCII are quartz parts of process kits.
28.Why should the rough vacuum pump use the dry type instead of the oil type?
Answer: Prevent oil back stream to the machine.
29
How many vacuum pumps are used for PVD?
A: Rough vacuum is pumped from atmospheric pressure to 5 mTorr for rough vacuum, and cryo pump is pumped from 5 mTorr to 10E-9 Torr for high vacuum.
30 How can I get a high vacuum in the 30PVD process?
A: Use a high vacuum pump.
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