# US 9,752,975 B2 · Method and apparatus for determining cleanliness of a sample

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- Number: US 9,752,975 B2
- Document ID: US9752975B2
- Status: Granted
- Kind: B2
- Application number: 14/991,955
- Filed: 2016-01-10
- Published: 2016-07-07
- Granted: 2017-09-05
- Earliest claimed: 2013-07-11
- Assignees: Persys Technology Ltd.
- Applicants: Persys Technology Ltd.
- Inventors: Leo Mendelovici; Gideon Drimer; Yitzhak Vanek
- Web page: https://patentgrep.com/patent/US9752975B2

## CPC

- G01N 15/0612: {Optical scan of the deposits (G01N15/0625 takes precedence)}
- G01N 15/0205: by optical means
- G01N 15/1429: Signal processing
- G01N 2015/0046: {in gas, e.g. smoke}
- G01N 2015/1486: {Counting the particles}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Determining cleanliness of a sample by providing a continuous flow of clean air into a chamber through a HEPA filter, taking a reference reading of particle counts while the chamber is empty, introducing the sample into the chamber and taking a first reading of a particle count received from all sides of the sample in the chamber to determine loose particles in a particle size range of 0.1 microns up to 5 microns associated with the sample.

## Claims

### Claim 1

A non-destructive method for determining cleanliness of a sample, the method comprising:
an operating apparatus,
wherein the operating apparatus comprises:
a chamber having a door and a sample holder or an integrated sample jig for holding both the sample in said chamber and providing a high velocity air stream over the sample; in said chamber,
a HEPA filter unit with a blower or a dome to provide clean dry air (CDA) disposed above said chamber and in fluid connection with said chamber; said blower or dome adapted to provide a constant flow to said chamber,
a nozzle set activated by a set of valves to provide a stream of high velocity clean air or short pulses of high velocity clean air over the sample, wherein the air to the nozzles set is provided through in-line HEPA filter units,
a valve coupled to an electrostatic discharge device (ESD) for generating ionized air, in fluid connection with said nozzle set, located in said chamber, said nozzle set configured to direct a stream of air via said in-line HEPA filter unit onto the sample,
a particle counter, coupled with the chamber, configured to count particles passed in a stream of air from said sample to said particle counter, and
a programmable controller for operating said apparatus, and
an electrostatic precipitator device (ESP) with a removable electron microscope holder coated with a detachable carbon sticker to which high voltage (5 KV) is applied in order to catch particles released from the sample for analyzing the chemical composition of trapped particles:
wherein the operating apparatus determines the cleanliness of the sample by the following steps:
a) providing a continuous flow of clean air into the chamber; through the HEPA filter,
b) taking a reference reading of particle counts while said chamber is empty,
c) introducing said sample into the chamber, and
d) taking a first reading of a particle count received from all sides of said sample in said chamber to determine loose particles in a particle size range of 0.1 microns up to 5 microns associated with said sample.

### Claim 2 (depends on 1)

The method of claim 1, wherein said sample is a generally three-dimensional sample.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
e) directing a stream of ionized air over said sample from a valve coupled to an electrostatic discharge device (ESD) for generating said ionized air, in fluid connection with said set of nozzles;
f) taking a second reading of particles count of said sample; and
g) calculating a difference between the first reading and the second reading thereby determining said cleanliness of said sample based upon said difference.

### Claim 4 (depends on 3)

The method of claim 3, wherein a third reading is taken during said directing step and wherein said cleanliness of said sample is calculated based upon a difference between the third reading and the second reading, or between the three readings, while taking into account said reference reading.

### Claim 5 (depends on 4)

The method of claim 4, wherein the determining comprises comparing the difference with a predetermined threshold.

### Claim 6 (depends on 4)

The method of claim 4, wherein the difference represents an impurities particles count.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
activating the electrostatic precipitator device (ESP) with a removable electron microscope holder coated with a detachable carbon sticker to which high voltage (5 KV) is applied in order to catch particles released from the sample for analyzing the chemical composition of trapped particles; and
trapping the impurities particles released from the sample due to said stream of ionized air.

### Claim 8 (depends on 7)

The method of claim 7, further comprising analyzing the trapped particles to determine nature and chemical composition of the impurities particles.

### Claim 9 (depends on 1)

The method of claim 1, wherein the sample is selected from at least one of a metal part, quartz part, ceramic part, and plastic part, a machine part, a tool, a clean room gown, a clean room glove a clean room towel, a silicon wafer, and a magnetic disk.

### Claim 10 (depends on 9)

The method of claim 9, wherein said sample, once tested, is ready for use in a clean room following said method.

### Claim 11

An apparatus for determining cleanliness of a sample, the apparatus comprising:
a chamber having a door and a sample holder or an integrated sample jig for holding both the sample in said chamber and providing a high velocity air stream over the sample; in said chamber;
a HEPA filter unit with a blower or a dome to provide clean dry air (CDA) disposed above said chamber and in fluid connection with said chamber; said blower or dome adapted to provide a constant flow to said chamber;
a nozzle set activated by a set of valves to provide a stream of high velocity clean air or short pulses of high velocity clean air over the sample, wherein the air to the nozzle set is provided through in-line HEPA filter units;
a valve coupled to an electrostatic discharge device (ESD) for generating ionized air, in fluid connection with said nozzle set, located in said chamber, said nozzle set configured to direct a stream of air via said in-line HEPA filter unit onto the sample;
a particle counter, coupled with the chamber, configured to count particles passed in a stream of air from said sample to said particle counter; and
a programmable controller for operating said apparatus, and
an electrostatic precipitator device (ESP) with a removable electron microscope holder coated with a detachable carbon sticker to which high voltage (5 KV) is applied in order to catch particles released from the sample for analyzing the chemical composition of trapped particles.

### Claim 12 (depends on 11)

The apparatus of claim 11, wherein the sample is selected from at least one of a metal part, quartz part, ceramic part, a plastic part, a machine part, a tool, a clean room gown, a clean room glove a clean room towel, a silicon wafer and a magnetic disk.

### Claim 13 (depends on 11)

The apparatus of claim 11, wherein the nozzle set comprises a shower head connected to an in-line HEPA filter unit.

### Claim 14 (depends on 11)

The apparatus of claim 11, wherein the nozzle set comprises a nozzle and a shower head connected to an in-line HEPA filter unit.

### Claim 15 (depends on 11)

The apparatus of claim 11, wherein the chamber further comprises a filter detachably located in a filter holder for trapping particles released from the sample due to the stream of air by applying a vacuum through the filter.

### Claim 16 (depends on 15)

The apparatus of claim 15, wherein the filter is removable for analyzing the chemical composition of trapped particles.

### Claim 17 (depends on 11)

The apparatus of claim 11, wherein said valve is a Venturi valve for supplying a stream of clean air or ionized air.

### Claim 18 (depends on 11)

The apparatus of claim 11, wherein said particle counter is a laser type particle counter.

### Claim 19 (depends on 18)

The apparatus of claim 18, wherein said laser type particle counter particle counter requires an external vacuum pump.

### Claim 20 (depends on 19)

The apparatus of claim 19, wherein said external vacuum pump is a Venturi type pump.

### Claim 21 (depends on 11)

The apparatus of claim 11, wherein said ESD device is adapted for activation by supplying a voltage thereto to provide a constant flow of ionized air to said chamber.

### Claim 22 (depends on 11)

The apparatus of claim 11, wherein said chamber and said particle counter are connected via a counter isokinetic probe.

### Claim 23 (depends on 11)

The apparatus of claim 11, wherein said ESD device is located inside the chamber and adapted for activation by supplying a voltage thereto to provide a constant flow of ionized air to said chamber.