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PlasmaTherm-DSE (PT-DSE) Capabilities, Specifications and Operation

PT-DSE is an ICP (Inductively Coupled Plasma) etch system configured for Si etches using Bosch process. This equipment belongs to the "Contaminated" group.
 
Contents
  1. Picture and Location
  2. Background
  3. Process Capabilities
    1. Cleanliness Standard
    2. Performance of the Tool
  4. Contact List and How to Become a User
    1. Contact List
    2. Training to Become a Tool User
  5. Operating Procedures
  6. Process Monitoring and Machine Qualification
    1. Tool Qualification Run
    2. Machine Status States
    3. Process Monitoring Results

Picture and Location

PT-DSE 

PT-DSE

The tool is located in area B on the Lab Map.

Equipment Locations (gif)

Background

 The Deep Silicon Etching (DSE™) Technology has been developed to achieve extremely high aspect ratio features on silicon substrates.  The DSE™ Technology is based on the well-known time division multiplex (TDM) etch process. The TDM process (also known as the Bosch process) employs alternating deposition (passivation) and etching cycles as illustrated below. 

 Bosch_Etch

For enabling faster etch rate, the source power generator (ICP power, 2MHz)  has an increased capacity of 3500 W and the max flow for SF6 MFC is 653 sccm.  In order to minimize the sidewall roughness, DSE uses a faster gas switching technique.  During cycling the reactive gases (C4F8 for dep and SF6 for etch step) are diverted to either the process module or pump depending on whether it is a dep or an etch step.  This enables a cycle time smaller than 1 sec if needed.  In addition, in order to facilitate faster RF tuning when switching between steps frequency tuning option is utilized in the DSE.    Also, in the DSE, bias voltage is controlled as opposed to bias power in the other etchers.  

 

Process Capabilities

Cleanliness Standard

 PT-DSE is a flexible tool and belongs to the "Contaminated" group.

Performance of the Tool

What the Tool CAN do

  • Deep silicon etching
  • Etching SOI wafers

 

What the Tool CANNOT do

  • Resist reticulation with deeper etches restricts the utilization of resist mask.
  • Hard clamp and resulting stickiness also restricts the versatility of the resist mask process.

 


Contact List and How to Become a User

Contact List

The following people make up the Tool Quality Circle:

  • Process Staff:  Usha Raghuram, Jim McVittie, Nancy Latta
  • Maintenance: Elmer Enriquez
  • Super-Users: Jim Kruger, Justin Snapp

 

Training to Become a Tool User

General Information About Plasma Therm Verasline Software


The software that runs the pt-dse is the same as runs three other systems.  It is described here.

Here is an example of a  typical process sequence step.  It contains ranges, gases, and min/max for various parameters.

Operating Procedures

 PT-DSE is very similar to other PlasmaTherm etchers and the operating procedure is described here.  Recipe set up is slightly different for PT-DSE as "Looping" and "Morphing" options are utilized in DSE and not in other etchers.  Procedure to set up looping and morphing parameters can be found here.

 

Process Parameters/ Limits

Process pressure, Max = 100mT

Backside He cooling pressure, max = 10 Torr

ICP power, max = 3500 W

Bias voltage, max = 1500 V

Electrode temp, max = 40 C; min = -40 C

Lid temp, Max = 180 C

Liner temp, max = 180 C

Spool temp, max = 180 C

Process gases, max flow

C4F8 = 420 sccm

SF6 = 653.4 sccm

Ar = 48.5 sccm

O2 = 48.25 sccm

 

Process Monitoring and Machine Qualification

Tool Qualification Run

 

Frequency

 Quals are run periodically:

  • Roughly once a quarter to check system performance
  • After major repairs to the system
  • When a labmember reports s variance from normal results.

Procedure

 A patterned Si wafer (with resolution pattern) was etched using the standard recipe (DSE-FAT) for 15 cycles.  Resist loss was measured using NanoSpec and Si loss using AlphaStep.

Responsibility

 

 

Recommendation to users with critical processes

 

Machine Status States

Red:

Yellow:

Green:

 

Process Monitoring Results

Etch Recipe:  DSE-FAT 

Etch Conditions:  

Dep Step:  150 C4F8/ 30 Ar/ 25mT/ 2000W ICP/ 10 V BV/ 2.5sec

Etch A Step:  150 SF6/30 Ar/ 40mT/ 2000W ICP/ 250V BV/ 1.5sec

Etch B Step:  300 SF6/ 30 Ar/ 75 mT/3000W ICP/ 10V BV/3.0sec

Electrode temp - 15 C; Liner temp - 70 C; Lid temp - 150 C; Spool temp - 180 C; Backside He = 4 T

 

Qual Data from 7/30/2014 (No of cycles = 15)

Si Etch rate = 8.55 um/min; Unif = 4.1% (AlphaStep Step height measurement; 5 sites; Patterned Si wafer)

Photoresist (PR)  ER = 764 A/min; Unif = 3.7% (NanoSpec measurement; 5 sites; Patterned Si wafer with 3612 resist)

Si: PR Selectivity = 112

Qual Data 10/2/2014 (No of cycles = 20)

 Si Etch rate = 8.03um/min; Uniformity = 2.19% (Alpha Step- Step height measurements; 5 sites; patterned Si wafer)

PR Etch rate = 747A/min; Uniformity = 2.95% (Nanospec measurements; 5 sites; patterned Si wafer with 1um 3612 resist)

Si: PR Selectivity = 108

 

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