IIC Fabrication Process Steps

IC Fabrication Process StepsIC Fabrication Process StepsIC Fabrication Process Steps

The fabrication of integrated circuits consists basically of the following process steps:

• Lithography: The process for pattern definition by applying thin uniform layer of viscous liquid (photo-resist) on the wafer surface. The photo-resist is hardened by baking and than selectively removed by projection of light through a reticle containing mask information.
• Etching: Selectively removing unwanted material from the surface of the wafer. The pattern of the photo-resist is transferred to the wafer by means of etching agents.
• Deposition: Films of the various materials are applied on the wafer. For this purpose mostly two kind of processes are used, physical vapor deposition (PVD) and chemical vapor deposition (CVD).
• Chemical Mechanical Polishing: A planarization technique by applying a chemical slurry with etchant agents to the wafer surface.
• Oxidation: In the oxidation process oxygen (dry oxidation) or HO (wet oxidation) molecules convert silicon layers on top of the wafer to silicon dioxide.
• Ion Implantation: Most widely used technique to introduce dopant impurities into semiconductor. The ionized particles are accelerated through an electrical field and targeted at the semiconductor wafer.
• Diffusion: A diffusion step following ion implantation is used to anneal bombardment-induced lattice defects.

Models describing the steps used in fabricating ICs have also been incorporated into process simulators. It is therefore quite possible today to ``build'' new semiconductor structures and predict their performance using these computer tools. The state of the art in such simulators is that they are indeed very useful, but can not completely replace real laboratory experiments, because the models used in the simulators are not complete in some cases, or are purely empirical in other cases.
As the models are improved with ongoing research, the simulators will become more robust and therefore more generally useful. There is great motivation to do this, because real laboratory experiments are very expensive and very time consuming, especially as chip technology continuates to advance.

VLSI QUESTIONS

VLSI QUESTIONS 1. tabulate the comparision b/w cmos and bipolar technologies
2. discuss on mos transistor threshold voltage
3. explain the design considerations of bi cmos inverter with suitable circuit diagram operation and its body effect
4. design and draw circuit diagram of nmos inverter and explain its operation with the help of transfer characteristics
5. explain the processing steps used in ic fabrication
6. define the following with necessary expressions
  (i) gm (ii) gds (iii) figure of merit
7. deduce the expressions for drain to source current versus drain to source voltage relations
8. find the pull up to pull down ratio for an nmos inverter driven through one or more pass transistors
9. draw and explain the characteristics of nmos transistor in different modes of operation and its body effect

8086 Interrupt Vector Table

8086 Interrupt Vector Table

 –

 The first 1Kbyte of memory of 8086 (00000 to003FF) is set aside as a table for storing thestarting addresses of Interrupt Service Procedures(ISP).

 –

Since 4-bytes are required for storing startingaddresses of ISPs, the table can hold 256 Interruptprocedures.

 –

 The starting address of an ISP is often called the

Interrupt Vector

or

Interrupt Pointer

. Thereforethe table is referred as

Interrupt Vector Table.

 –

In this table, IP value is put in as low word of thevector & CS is put in high vector.

8086 Interrupt Vector Table

interrupt vector table

An interrupt vector table, a concept common across various processor architectures, is a table of interrupt vectors that associates an interrupt handler with an interrupt request in a machine specific way. A dispatch table is one method of implementing an interrupt vector table.

When the CPU is interrupted by an interrupt, it looks up the interrupt handler in the interrupt vector table, and transfers control to it.

Mathematically a vector is described as having magnitude and direction.^{[citation needed]} Practically, you can apply this to an interrupt vector table by describing the address (or address length) as its magnitude, and its location as a direction within the table (see below).^{[citation needed]}

A commonly used x86 Real Mode interrupt is 0x10, the VGA BIOS code to handle primitive screen drawing functions

OSI 7 LAYERS

OSI LAYERS

OSI 7 LAYERS

MID-1 EXAMS (MP&MC)

MID-1 EXAMS QUESTIONS (MP&MC)

QUESTIONS

1. (a).Draw the architecture of 8086 microprocessor and explain each block.
    (b).Draw the functional pin diagram of 8255 PPI and also explain its modes of operation.
2. (a).Write an ALP to find the largest number from an unordered array.
    (b).Write an ALP to find the no of even and odd numbers in an array of numbers.
3. Explain the maximum mode operation of 8086 microprocessor with neat read and
     write cycle timing diagrams and also explain the need for bus control.
4. (a).Explain interrupt vector table ? also explain the vector cycle of 8086.
     (b).What do you mean by addressing modes. Explain different modes supported by 8086 by suitable examples.


SET 2

1. (a). Form a effective address for following
      (i) mov AX,[5000h]
     (ii) mov AX,5000[BX]
     (iii) mov AX,5000[BX][SI]
     (iv) mov AX,[BX][SI]    and with having following registers
[AX]=1000,   [BX]=2000,  [SI]=3000,  [DI]=4000,  BP=5000,  [SP]=6000,[CS]=0000
[DS]=1000,   [SS]=2000,   [IP]=7000.
  (b). Explain the following instructions with an example.
     (i).Exchange      (ii). AAA      (iii).push F      (iv).CMPS
2. (a). What is an assembler? What are advantages of assembler directive? List out between machine language & assembly language program.
    (b). Write about the special processor activities.
3. (a). Write an ALP to display a message HAPPY BIRTHDAY on the CRT screen of a micro       computer.
    (b). Write an ALP to move a string from one location to another location.
4.  Draw the functional pin diagram of 8086 microprocessor and explain the functions of each p  in

TIMETABLE FOR MID-1 3-2