sp3's experience using hot filament CVD reactors to grow diamond for an expanding set of applications

doi:10.1016/j.tsf.2005.07.108

Thin Solid Films

Volume 501, Issues 1–2, 20 April 2006, Pages 65-69

https://doi.org/10.1016/j.tsf.2005.07.108 Get rights and content

Abstract

The present status of sp3 in the area of diamond growth using hot filament CVD is given. After a brief description of the deposition systems being used by sp3 and a discussion of selected applications of sp3's products, the paper focuses on why the hot filament technique was selected as the deposition technique of choice. Topics discussed include ease of scaling, deposition system costs, film growth rate and film uniformity, safety issues, and temperature and process control. Finally, the economics of hot filament reactors compared to other deposition types are discussed.

Introduction

sp3 was incorporated over 10 years ago in Mountain View, California with the goal of developing Chemical Vapor Deposition (CVD) equipment, processes and products that would exploit the unique properties of diamond. One of the main challenges was to select a technical path that would provide for production scale, reliable and cost effective manufacturing day after day. After much analysis the path selected was Hot Filament CVD. The initial products using this approach were diamond coated cemented carbide cutting tools. sp3 has performed over 5000 reactor runs and successfully coated over one million carbide cutting tools during its tool coating history. sp3's tooling effort has expanded into a full offering of diamond cutting tools. In addition to the coated tools, sp3 now offers fabricated tipped diamond tools using both its proprietary CVD thick film diamond (TFd™), often called “sheet” diamond, and traditional polycrystalline diamond (PCD). In addition to producing cutting tools, sp3 designs, manufactures and sells Hot Filament reactors, and using diamond CVD, has developed additional products and processes for a wide range of applications. This paper starts with a very brief discussion of selected applications of sp3's products using Hot Filament reactors, and concludes with a discussion of why the Hot Filament technique was selected as the deposition method of choice. Pictures of the various products can be seen on the sp3 web site.

Section snippets

Equipment, process and film growth using Hot Filament reactors

The sp3 Hot Filament system deposits over an area approximately 300 mm by 400 mm. The system employs fine wire filaments (0.12 mm in dia.) in a cold wall aluminum chamber and the typical total system input power is between 22 kW and 30 kW. The system's filaments are horizontal [1] and can be arranged in a two-dimensional or three-dimensional array. A sophisticated process controller provides for complex deposition recipes with up to 58 discrete steps. This high degree of program control is

Ease of scaling

The deposition area of a microwave reactor is in part limited by the frequency of the plasma generator. The maximum deposition area in a state-of-the-art microwave systems is limited to about 150 mm in diameter. Some DC torches are capable of deposition over areas up to 200 mm in diameter. The present sp3 Hot Filament reactor deposits over an area 300 mm by 400 mm. There are Hot Filament reactors in Europe depositing over an area about 400 mm by 800 mm. sp3 is currently considering a reactor

The economics of Hot Filament reactors

The costs to coat typical cemented carbide cutting tool inserts are compared in Fig. 3. The costs are normalized for three different thicknesses of films grown in Hot Filament reactors and compared to the normalized costs to grow similar films in microwave, laser and arc jet systems. For the sake of comparison an sp3 Model 600 Hot Filament system is compared with a large microwave system depositing over a 6 in. diameter, a spot laser system such as the one offered at one time by QQC, and sp3's

sp3's experience in the production environment

In its production history sp3 has successfully completed over 6000 individual reactor runs, coating over 1 million tools. Typical reactor availability is over 95%, time between runs is usually less than 1 h and over 99% of runs are completed successfully. After initial setup and start, the systems run unattended, often for over 24 h when thicker films are required.

The primary reason for an aborted run comes from power outages from our local power provider, accounting for over 75% of these

Summary

For sp3, Hot Filament reactors have proven to be efficient and cost-effective diamond deposition systems for an ever-widening set of applications. The systems are easy to operate and have proven to be very reliable. Hot Filament reactors successfully coat both flat and round cemented carbide cutting tools, silicon carbide seals of various shapes and sizes, and silicon wafers for applications from as small as 50 mm up to a maximum of 300 mm.

At the same time diamond deposition represents only a

References (2)

sp3 patents 5,883,753 and...
sp3 patents 6,063,149, 6,319,610 and...

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