High temperature, high flow rate chemical vapor deposition...

Details High temperature, high flow rate chemical vapor deposition... High temperature, high flow rate chemical vapor deposition...

1997-02-12

2001-02-20

Pyon, Harold (Department: 1722)

Coating apparatus

Gas or vapor deposition

With treating means

C118S715000, C118S725000, C118S724000, C219S119000

Reexamination Certificate

active

06189482

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATIONS
This application is related to concurrently filed and commonly assigned patent application entitled “A HIGH TEMPERATURE CERAMIC HEATER ASSEMBLY WITH RF CAPABILITY AND RELATED METHODS”, having Jun Zhao, Charles Dornfest, Talex Sajoto, Leonid Selyutin, Stefan Wolff, Lee Luo, Harold Mortensen, and Richard Palicka listed as co-inventors; and to concurrently filed and commonly assigned patent application entitled “A HIGH TEMPERATURE, HIGH DEPOSITION RATE PROCESS AND APPARATUS FOR DEPOSITING TITANIUM LAYERS”, having Jun Zhao, Lee Luo, Xiao Liang Jin, Jia-Xiang Wang, and Stefan Wolff listed as co-inventors; and to concurrently filed and commonly assigned patent application entitled “APPARATUS FOR CERAMIC PEDESTAL AND METAL SHAFT ASSEMBLY”, having Jun Zhao, Talex Sajoto, Leonid Selyutin, Charles Dornfest, Stefan Wolff, Lee Luo, and Eller Juco listed as co-inventors; and to concurrently filed and commonly assigned patent application entitled “METHODS AND APPARATUS FOR A CLEANING PROCESS IN A HIGH TEMPERATURE, CORROSIVE, PLASMA ENVIRONMENT”, having Jun Zhao, Lee Luo, Jia-Xiang Wang, Xiao Liang Jin, and Stefan Wolff; the disclosures of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
The present invention relates to semiconductor processing. More specifically, the invention relates to methods and apparatus for forming films at temperatures greater than about 400° C. in a corrosive environment with a plasma. In some specific embodiments, the invention is useful for forming titanium-containing films such as titanium, titanium nitride, and titanium disilicide at temperatures of up to about 625° C. or greater. Such films may be used as patterned conductive layers, plugs between conductive layers, diffusion barrier layers, adhesion layers, and as a precursor layer to silicide formation. In addition, other embodiments of the present invention may be used, for example, to deposit other types of metal films, to alloy substrate materials, and to anneal substrate materials.
One of the primary steps in fabricating modem semiconductor devices is forming various layers, including dielectric layers and metal layers, on a semiconductor substrate. As is well known, these layers can be deposited by chemical vapor deposition (CVD) or physical vapor deposition (PVD). In a conventional thermal CVD process, reactive gases are supplied to the substrate surface where heat-induced chemical reactions (homogeneous or heterogeneous) take place to produce a desired film. In a conventional plasma CVD process, a controlled plasma is formed to decompose and/or energize reactive species to produce the desired film. In general, reaction rates in thermal and plasma processes may be controlled by controlling one or more of the following: temperature, pressure, plasma density, reactant gas flow rate, power frequency, power levels, chamber physical geometry, and others. In an exemplary PVD system, a target (a plate of the material that is to be deposited) is connected to a negative voltage supply (direct current (DC) or radio frequency (RF)) while a substrate holder facing the target is either grounded, floating, biased, heated, cooled, or some combination thereof. A gas, such as argon, is introduced into the PVD system, typically maintained at a pressure between a few millitorr (mtorr) and about 100 mtorr, to provide a medium in which a glow discharge can be initiated and maintained. When the glow discharge is started, positive ions strike the target, and target atoms are removed by momentum transfer. These target atoms subsequently condense into a thin film on the substrate, which is on the substrate holder.
Semiconductor device geometries have dramatically decreased in size since such devices were first introduced several decades ago. Since then, integrated circuits have generally followed the two-year/half-size rule (often called “Moore's Law”) which means that the number of devices which will fit on a chip doubles every two years. Today's wafer fabrication plants are routinely producing 0.5 &mgr;m and even 0.35 &mgr;m feature size devices, and tomorrow's plants soon will be producing devices having even smaller feature sizes. As device feature sizes become smaller and integration density increases, issues not previously considered crucial by the industry are becoming of greater concern. For example, devices with increasingly high integration density have features with high aspect ratios (for example, about 6:1 or greater for 0.35 &mgr;m feature size devices). (Aspect ratio is defined as the height-to-spacing ratio of two adjacent steps.) High aspect ratio features, such as gaps, need to be adequately filled with a deposited layer in many applications.
Increasingly stringent requirements for fabricating these high integration devices are needed and conventional substrate processing systems are becoming inadequate to meet these requirements. Additionally, as device designs evolve, more advanced capabilities are required in substrate processing systems used to deposit films made of materials needed to implement these devices. For example, the use of titanium is increasingly being incorporated into integrated circuit fabrication processes. Titanium has many desirable characteristics for use in a semiconductor device. Titanium can act as a diffusion barrier between, for example, a gold bonding pad and a semiconductor, to prevent migration of one atomic species into the next. Also, titanium can be used to improve the adhesion between two layers, such as between silicon and aluminum. Further, use of titanium, which forms titanium disilicide (silicide) when alloyed with silicon, can enable, for example, formation of ohmic contacts. A common type of deposition system used for depositing such a titanium film is a titanium sputtering deposition system which is often inadequate for forming devices with higher processing and manufacturing requirements. Specifically, sputtering may result in damaged devices which suffer from performance problems. Also, titanium sputtering systems may be unable to deposit uniform conformal layers in high aspect ratio gaps because of shadowing effects that occur with sputtering.
In contrast to sputtering systems, a plasma-enhanced chemical vapor deposition (PECVD) system may be more suitable for forming a titanium film on substrates with high aspect ratio gaps. As is well known, a plasma, which is a mixture of ions and gas molecules, may be formed by applying energy, such as radio frequency (RF) energy, to a process gas in the deposition chamber under the appropriate conditions, for example, chamber pressure, temperature, RF power, and others. The plasma reaches a threshold density to form a self-sustaining condition, known as forming a glow discharge (often referred to as “striking” or “igniting” the plasma). This RF energy raises the energy state of molecules in the process gas and forms ionic species from the molecules. Both the energized molecules and ionic species are typically more reactive than the process gas, and hence more likely to form the desired film. Advantageously, the plasma also enhances the mobility of reactive species across the surface of the substrate as the titanium film forms, and results in films exhibiting good gap filling capability.
However, conventional PECVD systems which use aluminum heaters may experience some limitations when used for certain processes, such as forming a titanium film from a vapor of, for example, titanium tetrachloride (TiCl
4
). Aluminum corrosion, temperature limitations, unwanted deposition, and manufacturing efficiency are some of the problems with such conventional PECVD systems that may be used to deposit a film such as titanium. In the exemplary process, titanium tetrachloride, which is a liquid at room temperature, and a carrier gas, such as helium, bubbled through this liquid generates vapor that can be carried to a deposition chamber. Such a titanium PECVD process may require a substrate temperature of about 600° C. to achieve a deposition rate of about 100 &angst

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