THE DIAMOND TIP                                                                                       

DIAMOND TIPS ON SILICON CANTILEVERS

DIAMOND TIPS ON SAPPHIRE CANTILEVERS

ACCESSORIES

DIAMOND TIP CARE AND RESHARPENING SERVICE

PRICES

THE DIAMOND TIP

Micro Star diamond tips are made from a single crystal diamond which is shaped as a 3-sided symmetrical pyramid terminating on a sharp point.  Only a single crystal diamond can be honed to nanometer scale sharpness. This is not possible with diamond coatings or polycrystalline diamonds.

The advantages of diamond probes over standard silicon tips are durability and defined tip geometry.  Depending on care, a diamond tip lasts many more scans than a silicon tip, especially on hard specimens. The predictable diamond tip geometry also allows more precise definition of specimen features.

  Diamond Tip Geometry

The 3-sided symmetrical pyramid profile is defined by the half angle, which is the angle between the pyramid center line and any of its three faces. A given half angle determines the front and side projection angles.  The table shows typical half angles used on Micro Star diamond tips with their front and side projections. 

  Standard Diamond Tip Half-Angles and Their Projections

The diamond tip height is normally between 50 and 100µm, but it can be made up to 300µm. A diamond tip radius at the apex is normally less than 20 nm.  Very sharp tips less than 5 nm can be achieved on 7° tips.  One TEM micrograph showing the side projection at 60,000X is included with each tip.

The following images are two examples:

  Tem Images of Diamond Tips at 60,000X

For specimen features requiring a high aspect ratio, Micro Star makes especial “spike” tips. These are tips terminating in a short, straight and narrow spike, which is part of the same single crystal diamond. Typically the spike is about 1µm long and 300nm thick, with a sharp point of a few nanometers radius. The image shows an example.

  Spike Diamond Tip

DIAMOND TIPS ON SILICON CANTILEVERS

Micro Star can attach a diamond tip to any standard silicone cantilever. The cantilever may be tip-less or may have the original silicon tip. Micro Star will remove the silicone tip and attach the diamond. The SEM images show an example.

  SEM Images of Diamond Tip on Silicon Cantilever

The diamond is attached with a hard polymer adhesive.  The polymer durometer hardness is 80. In the same scale a bowling ball is 90.

Micro Star has some silicon cantilevers available as shown in the table.  There are many types of silicon cantilevers made with different properties.

The main properties of interest are: cantilever stiffness measured in N/m, resonant frequency in KHz and the cantilever length in microns.

  Types of Silicon Cantilevers Available From Micro Star

The values in the table are approximations. The frequency provided is that of a cantilever before a diamond is attached. After a diamond tip is attached, the resonant frequency is reduced by as much as 50% of the original value.  The stiffness value provided on the card is supplied by the cantilever manufacturer.  All AFM diamond probes are supplied with a specification card indicating the actual measured values.

NOTE: Adding the diamond tip to the cantilever can sometimes reduce the resonant frequency by as much as half. 

Selection of Diamond Tip on Silicon Cantilever

A)  Select a diamond tip by specifying the Half Angle: 13, 9, 7° or Spike tip.

B)  Select a type of silicon cantilever:  M, N, P, or Q.

C) Alternatively, you can send us a silicon cantilever with the known properties you want (include 2 extra ones to allow for failures). Since the silicon tip is removed, it does not matter if the cantilever you send is already worn. 

D)  Let us know if you have other requirements.

(SEE PRICES BELOW)

DIAMOND TIPS ON SAPPHIRE CANTILEVERS

Micro Star has developed a technique to fabricate single crystal diamond probes on sapphire cantilever beams. The extreme hardness of diamond offers increased durability and consistency over silicon probes. The sapphire beam with its high modulus provides a sharp resonant frequency peak and is considerably stronger than silicon. A wide range of beam stiffness and resonant frequencies is available as shown in the table below.  These probes are ideal for long life, hard samples and micro machining applications.

The diamond tip is metal bonded to a sapphire cantilever. The cantilever is also metal bonded to a sapphire substrate. The metal has yield strength of 0.4GPa (60,000psi) up to 500°C.  For laser reflection, the top side of the cantilever is a plated optical flat.

  Sapphire Cantilever with Diamond Tip

  Cantilever dimensions and parameters (*set per customer specifications)

Selection of Diamond Tip on Sapphire Cantilever

A)  Select a diamond tip by specifying the Half Angle: 13, 9, 7° or Spike tip.

B) Select the most important parameter for your application: length L, stiffness K or frequency F. These three values and the cantilever thickness D are interrelated, so once one is selected the other two will have a limited range. For a more detail evaluation of these parameters see the selection graph.

C)  Let us know if you have other requirements. 

Conductive Diamond Tip on Sapphire Cantilevers

Micro Star has electrically conductive diamond available. The conductivity comes from Boron ions dispersed through the bulk of the material not from a surface coating.  The measured resistivity of this diamond is about 0.04Ohm•m which is similar to that of Graphite. The other properties of this diamond such as hardness, crystal orientation abrasion resistance etc. remain unchanged within measurable limits.

Sapphire cantilevers can be built with a conductive path from the diamond tip to the back of the substrate and a connection to a pin on the piezo module if requested.  Some of the applications of SPM conductive cantilever probes are in nano-lithography, electric charge and conductivity mapping or applications where static charge could distort the measurements.

Scanning Tunneling Microscopy (STM) Conductive Diamond Probes

A sharp conductive diamond tip for STM is one of the primary applications of conductive diamond. This tip is not mounted on a cantilever but is bonded to the wire-like probe used in the STM modules made by Veeco or other manufacturers.  Diamond tip half angle: 9°. Due to the nature of conductive diamond, the minimum that the radius can be specified as is "< 30 nm". 

(SEE PRICES BELOW)

ACCESSORIES

Micro Star makes two accessories for users of Dimension®, BioScope® and  Multimode® microscopes made by  Veeco or Digital Instruments.

Diamond Probe Module

The Micro Star Diamond AFM Probe is mounted permanently on this module which has the piezo crystal for tapping mode operation. It operates on the Dimension®/BioScope® SPM head and also on the Multimode® using the adaptor below.

  Module Shown with a Probe and In Its Box

This module provides a safe and reliable way to handle the diamond probe avoiding the use of tweezers to install it in the microscope. The module comes in a specially fitted box for safe shipping and storage.

Veeco Multimode® AFM Module Adaptor

This attachment provides a means of using the Module above on a Multimode® microscope. It comes in a specially fitted box which allows the storage of both the Adaptor and an attached Module.

  Adaptor Shown with a Module

DIAMOND TIP CARE AND RESHARPENING SERVICE

Diamond is the hardest material but the probe is delicate due to its nanometer size. Rough contact can damage the probe or the specimen.  An important value when using Micro Star diamond probes is the total tip height (H in the card) which is considerably larger than in standard silicon tips. Make sure that the safety distance parameter in your microscope is set at a larger value than the tip height. This will insure that the tip does not contact the specimen while at the high approach speed.

Micro Star diamond probes can be resharpened as long as the worn or broken tip end is not larger than 1µ.  Send us the probe for a free inspection to determine if it can be resharpened.

(SEE PRICE BELOW)

AFM DIAMOND PROBE SPECIFICATION CARD

  Specification Card Provided with Every Micro Star Probe

AFM SCAN IMAGES MADE WITH MICRO STAR DIAMOND PROBES - Courtesy of Dr. Sergei N. Magonov of Veeco Instruments. 

Tapping mode image of soft sample of triblock copolymer film using a diamond probe on sapphire cantilever with 23 N/m stiffness

Tapping mode image obtained on etched Al2O3 sample using a diamond probe on silicon cantilever with 4 N/m stiffness

Tapping mode image of soft sample of triblock copolymer film using a diamond probe on silicon cantilever 4 N/m stiffness

PRICES

Single Crystal Diamond Tip (13° or 9°)  ...................      $690

Mounted on Any Cantilever 

Additional Costs (added to the $690 price above):

7° Diamond Tip  ........................................................................        $100

Conductive Diamond   ............................................................        $250

Spike Diamond Tip  .................................................................        $250

Silicon Cantilever  ....................................................................        $50

Sapphire Cantilever  ................................................................        $200

AFM Module (for Veeco Dimension®)  ................................       $350

AFM Module Adaptor (for Veeco Multimode®)  .................       $550

Diamond Probe Resharpening  ............................................       $390

For items not listed, please request a quote.