Inductively coupled plasma CVD

Details Inductively coupled plasma CVD Inductively coupled plasma CVD

1996-12-23

2001-02-06

Bowers, Charles (Department: 2813)

Semiconductor device manufacturing: process

Coating of substrate containing semiconductor region or of...

Insulative material deposited upon semiconductive substrate

C438S624000, C438S631000, C438S695000, C438S784000, C438S786000, C438S778000, C438S788000, C438S789000, C438S902000, C438S906000, C427S573000, C427S579000, C204S192230

Reexamination Certificate

active

06184158

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a method and apparatus for high-density plasma-enhanced chemical vapor deposition of semiconducting and dielectric films and more particularly to techniques for depositing such films into high aspect ratio gaps on semiconductor substrates such as silicon wafers having metal interconnection layers.
DESCRIPTION OF THE RELATED ART
Chemical vapor deposition (CVD) is conventionally used to form various thin films in a semiconductor integrated circuit. CVD can form thin films such as SiO
2
, Si
3
N
4
, Si or the like with high purity and high quality. In the reaction process of forming a thin film, a reaction vessel in which semiconductor substrates are arranged can be heated to a high temperature condition of 500 to 1000° C. Raw material to be deposited can be supplied through the vessel in the form of gaseous constituents so that gaseous molecules are thermally dissociated and combined in the gas and on a surface of the substrates so as to form a thin film.
A plasma-enhanced CVD apparatus utilizes a plasma reaction to create a reaction similar to that of the above-described CVD apparatus, but at a relatively low temperature in order to form a thin film. The plasma CVD apparatus includes a process chamber consisting of a plasma generating chamber which may be separate from or part of a reaction chamber, a gas introduction system, and an exhaust system. Plasma is generated in such apparatus by various plasma sources. A substrate support is provided in the reaction chamber which may include a radio frequency (RF) biasing component to apply an RF bias to the substrate and a cooling mechanism in order to prevent a rise in temperature of the substrate due to the plasma action.
Vacuum processing chambers are generally used for chemical vapor depositing of materials on substrates by supplying deposition gas to the vacuum chamber and applying of an RF field to the gas. For example, parallel plate and electron-cyclotron resonance (ECR) reactors have been commercially employed. See U.S. Pat. Nos. 4,340,462 and 5,200,232. The substrates are held in place within the vacuum chamber during processing by substrate holders. Conventional substrate holders include mechanical clamps and electrostatic clamps (ESC). Examples of mechanical clamps and ESC substrate holders are provided in U.S. Pat. No. 5,262,029 and U.S. application Ser. No. 08/401,524 filed on Mar. 10, 1995.
Plasma-enhanced chemical vapor deposition (PECVD) has been used for depositing intermetal dielectric layers at low temperatures in integrated circuit applications. A publication by M. Gross et al. entitled “Silicon dioxide trench filling process in a radio-frequency hollow cathode reactor”, J. Vac. Sci. Technol. B 11(2), March/April 1993, describes a process for void-free silicon dioxide filling of trenches using a hollow cathode reactor wherein silane gas is fed through a top target which supports a low frequency (1 MHz), low pressure (~0.2 Pa) oxygen and xenon discharge. In this process, high ion bombardment and a low rate of gas phase reaction produce an ion induced reaction with surface adsorbates, leading to directional oxide film growth whereby trenches with one micron openings and aspect ratios up to 2.5:1 are filled at rates over 400 Å/min.
A publication by P. Shufflebotham et al. entitled “Biased Electron Cyclotron Resonance Chemical-Vapor Deposition of Silicon Dioxide Inter-Metal Dielectric Thin Films,” Materials Science Forum Vol. 140-142 (1993) describes a low-temperature single step gap-filled process for use in inter-metal dielectric (IMD) applications on wafers up to 200 mm in diameter wherein sub −0.5 micron high aspect ratio gaps are filled with SiO
2
utilizing an O
2
—Ar—SiH
4
gas mixture in a biased electron cyclotron resonance plasma-enhances chemical-vapor deposition (ECR-CVD) system. That single step process replaced sequential gap-filling and planarization steps wherein CVD SiO
2
was subjected to plasma etch-back steps, such technique being unsuitable for gap widths below 0.5 microns and aspect ratios (gap height:width) above 1.5:1.
Prior art apparatuses suffer from several serious disadvantages with respect to IMD applications. ECR and helicon sources which rely on magnetic fields are complex and expensive. Moreover, magnetic fields have been implicated to cause damage to semiconductor devices on the wafer. ECR, helicon and helical resonator sources also generate plasmas remotely from the wafer, making it very difficult to produce uniform and high quality films at the same time and also difficult to perform in-situ plasma cleans necessary to keep particulates under control without additional equipment. Furthermore, ECR, helicon and helical resonator, and domed inductively-coupled plasma systems require large, complex dielectric vacuum vessels. As a corollary scale-up is difficult and in-situ plasma cleaning is time consuming.
SUMMARY OF THE INVENTION
The present invention is directed to processes that employ an inductively coupled plasma-enhanced chemical vapor deposition (IC PECVD) high density plasma system. The system is compact, in-situ cleanable and produces high quality semiconductor and dielectric films.
In one aspect, the invention is directed to a method for filling gaps between electrically conductive lines on a semiconductor substrate comprising the steps of: providing a substrate in a process chamber of an inductively coupled plasma-enhanced chemical vapor deposition reactor which can include a substantially planar induction coil; introducing a process gas which can include a noble gas into the process chamber wherein the amount of noble gas is sufficient to assist in gap filling; and growing a dielectric film on the substrate with dielectric film being deposited in gaps between electrically conductive lines on the substrate.
In another aspect, the invention is directed to a method for filling gaps between electrically conductive lines on a semiconductor substrate comprising the steps of: providing a substrate in a process chamber of an inductively coupled plasma-enhanced chemical vapor deposition reactor which can include a substantially planar induction coil; filling gaps between electrically conductive lines on the substrate by: (i) introducing a first process gas which can include a noble gas into the process chamber wherein the amount of noble gas is sufficient to assist in gap filling; and (ii) growing a first dielectric film in the gaps at a first deposition rate; and depositing a capping layer comprising a second dielectric film onto the surface of said first dielectric film by introducing a second process gas into the process chamber, said capping layer being deposited at a second deposition rate that is higher than the first deposition rate.
In a further aspect, the invention is directed to a method of depositing a dielectric film on a substrate comprising the steps of: providing a substrate in a process chamber of an inductively coupled plasma-enhanced chemical vapor deposition reactor wherein the substrate is positioned on a substrate holder; introducing a process gas which can include a noble gas into the process chamber, wherein the amount of noble gas is sufficient to assist in depositing the dielectric film; controlling the temperature on a surface of the substrate holder; and energizing the process gas into a plasma state by inductively coupling RF energy into the process chamber and growing a dielectric film on the substrate.
In yet another aspect, the invention is directed to an inductively coupled plasma processing system comprising: a plasma processing chamber, a substrate holder supporting a substrate within said processing chamber wherein the substrate holder is at a temperature of about 80° C. to 200° C., an electrically-conductive coil that is disposed outside said processing chamber; means for introducing a process gas into said processing chamber; and an RF energy source which inductively couples RF energy into the processing chamber to energize the process gas into a plasma state. Planar and non-pla

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