YIELD Engineering Systems Inc.

YES ovens are designed to give total parameter control over your process, in a clean environment. Wafers placed in a YES high temperature vacuum oven stay clean, so you get the results you want. YES ovens provide an ideal processing environment for curing:

Pulling a vacuum in a series of nitrogen purge cycles removes oxygen, moisture and atmospheric contaminants. Running at 250 Torr (1/3 of atmosphere) gently draws out solvents in a gentle vertical laminar flow that removes particles. Processing at reduced pressure prevents a problematic heat reaction, in which a hard skin forms on the top of polyimide film before it is completely baked and traps solvents.

The vacuum is pulled from the bottom of the oven, and preheated nitrogen enters from above and goes through a restraining stainless steel flat plate filter. This induces vertical flow and the constant removal of particles from the substrate. Plus, as a bonus, a vacuum process significantly reduces the amount of nitrogen flow required compared to atmospheric ovens.

The constant vacuum and hot nitrogen mix pulls out the solvent with more efficiency. It also provides a gentle laminar flow to remove particles. (Older methods of heating polyimide relied on dwell steps to allow the substrate to heat up and boil out solvent).

Using a vacuum provides tighter control of your process. Processing conditions are very repeatable because of reduced pressure combined with temperature profile of ramp baked.

4. Temperature Uniformity. Using a vacuum allows an adjustable air-mixing ratio for chamber cooling to adapt the tool for best performance over a broad range of operating temperatures. (Vacuum + pre-heated nitrogen gives control of process atmosphere).

Using a vacuum achieves oxygen levels below 10ppm during processing. All of our polyimide bake ovens have double door seals, creating a nitrogen "buffer" between the outside atmosphere and the inside chamber.

YES high temperature cure ovens are designed to provide a controlled ramp curing process for temperatures up to 450ºC in an oxygen-free environment. In addition, YES ovens provide a cleaner process in a controlled environment, so you’ll get higher yields. Our ovens offer a unique cooling package to reduce your process time and utilize laminar flow technology, so wafers in our ovens stay clean. (Automatic systems - see below)

Yield Engineering System’s YES 450PB Series

Critical steps in any cure process include complete removal of residual solvents, uniform temperature distribution, pressure control, ability to maintain dry inert atmosphere, and control of heating and cooling rates. Our systems achieve this plus particle reduction in most applications.

Yield coalescing condensate trap assembly

Solvent vapor that evaporates from wafer films during the cure process condenses as soon as the process gas cools. If condensation is not controlled, condensable process effluents can plug vacuum lines, affect control valve operation and degrade the performance of vacuum pumps. YES-PB Series tools use a coalescing condensate trap assembly to control the accumulation and disposal of solvent condensates.

YES high temperature vacuum cure ovens offer vertical laminar airflow paired with a unique cooling package to cool the chamber. The vertical laminar flow carries particulates away so they won't deposit onto wafers. Directing the airflow so it streams from the top of the system and out the bottom ensures there's no air turbulence, allowing particle reduction in most applications.

The YES-450PB Series cooling package allows for faster chamber cooling times as well as temperature uniformity control throughout the process. Adjustable air mixing ratio for chamber cooling adapts the tool for best performance over a broad range of operating temperatures. The design allows the process engineer total control of ramp down rates within the tool's specifications. The cooling package only uses air, no water.

Model YES-6-2P-CP -  Technical Note 
Model YES-8-2P-CP - Technical Note 

Model YES-12-2P-CP -  Technical Note 

When creating a high-reliability MEMS package, it is imperative to have complete moisture removal and moisture prevention to extend the life of the MEMS device.
The YES-450PB-HV (High Vac) provides a critical component which allows a degas and moisture abatement process for devices, getters/lids in a single tool. The tool uses high temperature and high vacuum to achieve complete moisture removal.
The device life is protected (extended) in an extremely small, hermetically-sealed package. Maintaining a completely dry environment depends on being able to absorb the gas from the package perimeter that would otherwise destroy the desired atmosphere.
Our YES-450PB-HV Series is designed to ensure complete and permanent moisture and hydrogen removal using high vacuum (10-6) and high temperature (up to 450°C). Our patented nitrogen purge precedes process preparation and creates a successful procedure for improved MEMS lifetime and performance.

MODEL 6-2P-CP

MODEL 8-2P-CP

MODEL 12-2P-CP

Clean Room Compatibility

Class 10

Wafer Size

Up to 150mm

Up to 200mm

Up to 300mm

Capacity

Up to 50 Wafers/Batch

Operation Temperature

Ambient to 450°C

N₂ Flow Rate

1 SCFM

Interior Chamber Dimen.

10.8" ID X 22.0" D

14.4" ID (Barrel) x 26.2" D

21.0" ID X 26.0" D

Chamber Process Area

6.4"W X 14"D X 7.3"H

9.4"W x 18.1"D x 9.8"H

14.8"W X 22.3"D X 14.2"H

Overall System Dimen.

23.7"W X 50.75"D X 27.3"H

27.2"W x 50.75"D x 30.8"H

33.8"W X 67.03"D X 37.4"H

Control Console Dimen.

23.4"W X 37.8"D X 9.3H

Chamber Material

316L Stainless Steel

Process Gas Inputs

1 Standard, up to 3 Optional

Mass Flow Controllers

Optional, up to 3 for Gas Mixing

Laminar Flow Filter

100 Micron Mott Plate Filter

Cleanliness

Particle Reduction in Most Applications

No. of Recipes

8 Temperature Profiles

No. of Steps for ea. Recipe

16 Program Steps

Uniformity of Temperature

±5°C During Dwell after Stabilization Period

±5°C During Dwell after Stabilization Period

±7°C During Dwell after Stabilization Period

Max. Heat-Up Rate

10°C/min

7.5°C/min

6.5°C/min

Max. Cool-Down Rate

7°C/min

4.5°C/min

3.5°C/min

Oxygen Concentration

10ppm Over Background

The YES-VertaCure automated, high temperature cure series of ovens is designed for today’s most advanced MEMS and semiconductor process applications. Whether it’s for proper curing of polyimide in Wafer-level Packaging (WLP)/ Redistribution Layers (RDL) applications or annealing copper in an advanced semiconductor device, the YES-VertaCure helps achieve total environmental control to increase yields and extend device performance.
The system incorporates the laminar flow technology of the YES-450PB series. It accommodates 200 and 300mm wafers with one or two load ports and a wafer handling robot inside an integrated Class 1 minienvironment. Up to 50 wafers are loaded into a stainless steel cassette-type rack on the oven chamber door and, when loading is complete, lifted up into the vacuum chamber.

YES-VertaCure series

VertaCure Series is designed to achieve tight control over your process atmosphere:

The VertaCure Series is available with:

Which supports the following MEMS applications: 

METAL ANNEALING  

Annealing is a heat treatment where the microstructure of a material is altered, causing changes in its properties such as strength and hardness. In the semiconductor industry, silicon wafers are annealed so that dopant atoms (such as boron, phosphorus or arsenic), can be incorporated into substitutional positions into the crystal lattice, which drastically changes the electrical properties of the semiconducting material. In the case of copper, adding an anneal step:

WAFER DEHYDRATION  

The moisture on the surface of wafers will cause unintended reactions with various deposition steps. These reactions result in unstable surface which degrade over time. Vacuum dehydration provides a clean stable starting surface resulting in superior films.

GETTER ACTIVATION  

Getters are used to scavenge unwanted gases in many applications. In MEMS devices, getters may be used to tie up excess moisture or hydrogen which may interfere with the long term operation of the device. Activating the getter material involves high temperature and high vacuum processing to ensure the material starts as moisture / hydrogen-free as possible.

THERMAL TREATMENT OF THIN FILM RESISTORS  

Thin film resistors can change properties rapidly as they age unless they are properly thermally treated. The process stabilizes the crystal grain and ensures long term predictable behavior.

SURFACE TENSION MODIFICATION  

As devices are made smaller and smaller, static friction (stiction) becomes more and more significant. By modifying the surface tension with a class of fluorinated silanes, the operating life of moving parts in MEMS devices can be significantly lengthened. Conversely, if surfaces need to be bonded together, other silanes can be coated which enhance bonding strengths between unlike materials.

The process begins with vacuum cycle purges to remove oxygen and water vapor followed by a continuous horizontal laminar flow of up to four process gases. The laminar flow of gas can be maintained during a recipe-driven temperature profile. Operating temperatures are 150°C to 450°C; pressure range is 50-500 Torr.

The process begins with vacuum cycle purges to remove oxygen and water vapor followed by a continuous horizontal laminar flow of up to four process gasses. The laminar flow of gas can be maintained during a recipe-driven temperature profile. Operating temperatures are 150°C to 450°C; laminar flow pressure range is 0.50-500 Torr. The tool is also capable of evacuation down to 5E-5 Torr using a vacuum turbo pump.
The YES-VertaVac gives engineers moisture resistant surface modification and increased time available between process steps.

The Silane vapor deposition is a process that assists in the de position of a thin film of various chemistries in order to achieve precise surface modification. Vapor deposition is the preferred method for coating surfaces with silanes.
As technology shrinks, there is a growing need for precise control over nanoscale surface areas. The YES-VertaCoat gives you total control over your process environment. The tool also is designed as a flexible system to accom modate a variety of silanes and processes.
Specifically, the silane vapor deposition process assists with MEMS coating to reduce damaging stiction and photoresist adhesion for semiconductor wafers. The entire YES-VertaCure series is designed to give you uniform, repeatable results with an added bonus of cost savings!

Cleanliness

Class 10 clean room

Chamber Cleanness

Class 1

Interior Chamber Dimen.

Ø 17.74" (45.1 cm) x 21.22" (59.9 cm) deep

Chamber Process Area

Chamber Material

316L stainless steel with Titanium fasteners

Process Gas inputs

1 gas standard, 3 gases optional

Mass Flow Controllers 

Optional on any/all 4 process gases

Capacity

200 mm only configuration: 50 wafers

200/300 mm option configuration: 25 wafers
300 mm only configuration: 50 wafers

Temperature

Ambient up to 450°C chamber temperature

Temperature Uniformity

±3.5°C dwell after stabilization period

Throughput

300 mm only configuration: 20 wafers/hr *

200/300 mm option configuration: 10 wafers/hr *
200 mm only configuration: 20 wafers/hr *

* based on 50 wafers per cycle w/typical polyimide process time cure cycle of approx. 2.5 hr. (1hr. dwell @ 350 °C)

Safety

Audible and visual alarms. Redundant over-temp monitoring.

User Interface

SEMI E37 compliant HSMS host communications optional,

Complies with SEMI E30 & SEMI E5,

Number of Recipes

25 temperature profiles

N0. of Steps for each recipe

16 program steps

Range of Exposure Time

0- 600 minutes

Resolution of Timer Setting

1 minute

RF Plasma Frequency

40 KHz

RF Plasma Power

100- 1000 Watts

Process Gas Inputs

1

Plasma Gas Inputs

3

Wafer Throughput

Typically 1- 2 loads/hr; varies by process