Page 178 - Semiconductor Manufacturing Handbook

Geng(SMH)_CH13.qxd 04/04/2005 19:50 Page 13.1

Source: SEMICONDUCTOR MANUFACTURING HANDBOOK

CHAPTER 13

PHYSICAL VAPOR DEPOSITION

Florian Solzbacher
University of Utah
Salt Lake City, Utah

13.1 INTRODUCTION TO PHYSICAL VAPOR DEPOSITION

Physical vapor deposition (PVD) is a high-vacuum deposition process for metals, metal alloys, or
other solid chemical compounds using thermal energy (evaporation) or kinetic energy of ions (sput-
tering) to remove material from a source (sputter target or crucible) and deposit it onto a substrate.

13.1.1 Motivation and Key Properties
PVD is the most commonly used process for the deposition of metals and metal oxides in semicon-
ductor processing. The motivation for using PVD processes lies in the specific properties of the
process and the deposited layers:

• A wide range of layer thicknesses ranging from tens of nanometers to tens of micrometers is pos-
sible.
• The layer uniformity and reproducibility is high.
• Essentially, there is no limitation in the choice of source materials (such as metals, semiconduc-
tors, glass, ceramics, and plastics) that can be deposited.
• Multilayer systems can be deposited in one vacuum process.
• The substrate temperature can be kept low (down to room temperature) and seldom exceeds 350°C
during deposition. Thus, no damage is being done to underlying layers.
• The layer properties (specific resistance, temperature coefficient of resistance (TCR), adhesion,
structure, composition, density, refractive index) can be modified by changing the process para-
meters (substrate temperature, residual gas pressure, process pressure, particle energy, deposition
rate, and gas atmosphere).

13.2 FUNDAMENTALS OF PVD PROCESSES

PVD processes are vacuum processes. In order to understand their specifics, it is necessary to briefly
introduce some of the main concepts of vacuum physics like pressure and mean free path. As dis-
cussed in Chap. 7, pressure p can be described as gas molecules with concentration n per unit

Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) 13.1
Copyright © 2004 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.