Hallo thank you v much for the video!! could you please tell me why could the photoresist have a taper after the ion implantation? does the HMDS prime time have an effect on the taper? when could we have an overcut/undercut profile? thank you!!!!!!!!!
The starting material is a p-type single crystal silicon wafer having 5 to 20 ohm-cm resistivity and thickness of approximately several hundred micrometers. The diameter can be 50, 75, 100, 125, or 150 mm. The most standard size is 100 mm or about 4 inches A thin layer of SiO2 is formed on all surfaces of a p-type silicon wafer by exposing it to oxygen or water vapour in an electric furnace. The first masking step defines the area for n+ buried layers, (also called sub-collector). The function of this layer is to reduce the collector resistance of the transistor. The SiO2 is removed in these areas by chemical etching. Thermal diffusion or ion implantation forms the desired heavily doped n-type, that is, n+ buried layer region. The resulting structure is shown in the figure below. The SiO2 masking layer is removed, exposing the entire silicon wafer surface. By epitaxial deposition, an n-type layer is grown, over the entire surface. It is n-type single-crystal silicon 2 to 5 micro meter thick with its resistivity in the range of 0.1 to 1 ohm-cm. During the epitaxial process, the n-type dopant previously introduced in the buried layer areas diffuses in all directions. This is shown in the figure below. The wafer with the epitaxial layer is then oxidized at an elevated temperature in an H2O ambient. This forms a layer of SiO2, approximately 0.5 micro meters thick over the entire surface of silicon. A second masking step defines a border completely enclosing n-type islands of silicon that are to be electrically isolated collectors of transistors. P-type diffusion into the border areas is continued until the entire epitaxial layer has been penetrated, as shown in the figure below. Thus, islands of n-type silicon are bounded on all sides by p-type Si. Isolation is achieved by applying voltages such that this p-n junction is always reverse- biased. The p-type diffusion uses boron as impurity. A new layer of thermal oxide is grown over the isolation areas. The third masking step defines base regions of n-p-n transistors. Patterns of resistors are formed simultaneously in separate isolated n-type regions. Boron is again diffused (but this time not as deeply) or implanted to forms bases and resistors. The n-type collector is converted to p-type when the density of p-type impurities exceeds that of n-type impurities. The resulting structure is shown in figure below. The fourth photolithographic step defines n-type transistor emitters and n-type regions for low resistance contacts to collector regions, as in the figure below. Again conversion of p-type base to n-type requires impurity compensation. An oxide is again thermally grown over the entire wafer and via photolithography, (5th mask) those regions where contact is to be made to the silicon are defined. Metal (AI) is then deposited by vacuum evaporation. The photolithographic process (6th mask) is then used to define the appropriate metallization inter-connection pattern, and the remaining metal is removed. The figure below shows the contact areas (defined by 5th mask) to collector, base, and emitter. The 6thmasking step is not shown in figure.
Angreji kaha se sikhe ho ?
Very good explanation, very useful topic in ic fabrication
thank you for explaining
nice explanation mam
good explanation. don't stop uploading more videos.
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mera bhi🙂
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ma'am plz make more videos on vlsi
Thanku so much mam ji...🙏🙏
Y u talking in hindi
good explanation mam keep it up and thanks a lot forthis lecture
Hallo thank you v much for the video!! could you please tell me why could the photoresist have a taper after the ion implantation? does the HMDS prime time have an effect on the taper? when could we have an overcut/undercut profile? thank you!!!!!!!!!
nice explanation mam
Thank you sister 👍
well understood
which one is best??
Mam can you share your insta id
Mam next video link
Thanku ma'am explaining such a complex topic in simple manner
very helpful thank you
The starting material is a p-type single crystal silicon wafer having 5 to 20 ohm-cm resistivity and thickness of approximately several hundred micrometers. The diameter can be 50, 75, 100, 125, or 150 mm. The most standard size is 100 mm or about 4 inches A thin layer of SiO2 is formed on all surfaces of a p-type silicon wafer by exposing it to oxygen or water vapour in an electric furnace. The first masking step defines the area for n+ buried layers, (also called sub-collector). The function of this layer is to reduce the collector resistance of the transistor. The SiO2 is removed in these areas by chemical etching. Thermal diffusion or ion implantation forms the desired heavily doped n-type, that is, n+ buried layer region. The resulting structure is shown in the figure below. The SiO2 masking layer is removed, exposing the entire silicon wafer surface. By epitaxial deposition, an n-type layer is grown, over the entire surface. It is n-type single-crystal silicon 2 to 5 micro meter thick with its resistivity in the range of 0.1 to 1 ohm-cm. During the epitaxial process, the n-type dopant previously introduced in the buried layer areas diffuses in all directions. This is shown in the figure below. The wafer with the epitaxial layer is then oxidized at an elevated temperature in an H2O ambient. This forms a layer of SiO2, approximately 0.5 micro meters thick over the entire surface of silicon. A second masking step defines a border completely enclosing n-type islands of silicon that are to be electrically isolated collectors of transistors. P-type diffusion into the border areas is continued until the entire epitaxial layer has been penetrated, as shown in the figure below. Thus, islands of n-type silicon are bounded on all sides by p-type Si. Isolation is achieved by applying voltages such that this p-n junction is always reverse- biased. The p-type diffusion uses boron as impurity. A new layer of thermal oxide is grown over the isolation areas. The third masking step defines base regions of n-p-n transistors. Patterns of resistors are formed simultaneously in separate isolated n-type regions. Boron is again diffused (but this time not as deeply) or implanted to forms bases and resistors. The n-type collector is converted to p-type when the density of p-type impurities exceeds that of n-type impurities. The resulting structure is shown in figure below. The fourth photolithographic step defines n-type transistor emitters and n-type regions for low resistance contacts to collector regions, as in the figure below. Again conversion of p-type base to n-type requires impurity compensation. An oxide is again thermally grown over the entire wafer and via photolithography, (5th mask) those regions where contact is to be made to the silicon are defined. Metal (AI) is then deposited by vacuum evaporation. The photolithographic process (6th mask) is then used to define the appropriate metallization inter-connection pattern, and the remaining metal is removed. The figure below shows the contact areas (defined by 5th mask) to collector, base, and emitter. The 6thmasking step is not shown in figure.
Book name plz
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CVD diamond process lacture dena mam
Best Explained
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Best video on locos on youtube
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Thank u mam 🤗
please make the playlist of every subject, which contains all the videos of that particular subject
i am from IIT you are teaching better than my professors
Present Sir
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Present sir
Present sir
Present sir
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i have attended this lecture
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May I ask you a question about a type of photoresist
May I ask you a question about a type of photoresist