Plasma assisted method of accurate alignment and pre-bonding for microstructure including glass or quartz chip

Abstract

The plasma-assisted method of precise alignment and pre-bonding for microstructure of glass and quartz microchip belongs to micromachining and bonding technologies of the microchip. The steps of which are as follows: photoresist and chromium layers on glass or quartz microchip are completely removed followed by sufficient cleaning of the surface with nonionic surfactant and quantities of ultra-pure water. Then the surface treatment is proceeded for an equipping surface with high hydrophily with the usage of plasma cleaning device. Under the drying condition, the precise alignment is accomplished through moving substrate and cover plate after being washed with the help of microscope observation. Further on, to achieve precise alignment and pre-bonding of the microstructure of glass and quartz microchip, a minute quantity of ultrapure water is instilled into a limbic crevice for adhesion, and entire water is completely wiped out by vacuum drying following sufficient squeezing. Based on the steps above, it is available to achieve permanent bonding by further adopting thermal bonding method. In summary, it takes within 30 min to finish the whole operation of precise alignment and pre-bonding by this method. Besides, this method is of great promise because of its speediness, efficiency, easy maneuverability, operational safety and wide applications.

Claims

1. A plasma-assisted method of accurate alignment and pre-bonding for a microstructure including a glass or quartz chip, the method comprising sequential steps of: a) removing superficial photoresist and chromium layers of substrate and cover plates of glass or quartz microchips after wet etching; b) washing the substrate and cover plates using a detergent and then water to remove superficial organics, solid particles, and dust; c) blowing majority of the water away from the substrate and cover plates and then performing a rinse and activation using a plasma cleaning device to make the substrate and cover plates to be hydrophily; d) obtaining the rinsed and activated subtract and cover plates and then sticking the rinsed and activated subtract and cover plates, thereby performing a preliminary alignment; wherein the performing the preliminary alignment comprises performing the preliminary alignment using naked eyes; e) performing an accurate alignment on the rinsed and activated subtract and cover plates under a drying condition and then placing water into an edge of a gap between the subtract and cover plates to form a hydrophilic layer between surfaces of the subtract and cover plates and to make the subtract and cover plates stick tightly to each other; wherein the performing the accurate alignment comprises performing the accurate alignment under a microscope; f) removing extra water from the subtract and cover plates by pressing the subtract and cover plates and then blowing water away from the edge; and g) removing remaining water from the subtract and cover plates by vacuuming using the plasma cleaning device to obtain pre-bonded glass or quartz chips.

2. The method of claim 1, wherein materials of the substrate plates in step a) comprise glass or quartz materials.

3. The method of claim 1, wherein the performing the rinse and activation in step c) comprises performing the rinse and activation for 3-10 minutes and gas for stimulating plasma of the plasma cleaning device comprises air, nitrogen or oxygen.

4. The method of claim 1, wherein the placing the water into the edge of the gap comprises placing water on the edge of the gap using 2-7 L water such that the water enters the gap via capillary penetration after the performing the accurate alignment in step e).

5. The method of claim 1, wherein the blowing the water away comprises blowing the water away using a high-pressure air gun.

6. The method of claim 1, wherein the vacuuming using the plasma cleaning device in step g) comprises vacuuming for 5-20 minutes using the plasma cleaning device.

7. The method of claim 6, wherein the accurate alignment and pre-bonding are performed within 20-35 minutes.

8. The method of claim 6, Further comprising: performing a thermal bonding method on the pre-bonded glass or quartz chips by placing the pre-bonded glass or quartz chips into a muffle furnace and heating the pre-bonded glass or quartz chips based on a predetermined heating procedure to obtain permanent bonded glass or quartz chips.

9. The method of claim 8, wherein a rate of the predetermined heating procedure is 1-3 C. per minute, an initial temperature of the predetermined heating procedure is a room temperature, the maximum temperature of the predetermined heating procedure is 550 C.-1200 C., a temperature holding time of the predetermined heating procedure is 1-3 hours, a cooling rate of the predetermined heating procedure is 0.5-5.5 C. per minute, and a final temperature of the predetermined heating procedure is the room temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a photograph of the microstructure of soda glass substrate microchip before precise alignment in this disclosure.

(2) FIG. 2 is a photograph of the microstructure of soda glass substrate microchip after precise alignment in this disclosure.

(3) FIG. 3 is an effect picture of a cross section of soda glass substrate microchip after thermal bonding in this disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) The disclosure is further illustrated in more details accompanied by specification with attached maps and concrete examples so that researchers in the related field can better understand this disclosure scheme. However, this disclosure is not limited to the following examples.

Example 1

(5) S1 Plasma-Assisted Precise Alignment and Pre-Bonding for Microstructure of Soda Glass Substrate Microchip:

(6) 1) After wet etching, 2.3 mm thick optical cement on the surface of soda glass substrate microchip is dissolved with acetone, and then sufficiently washed with isopropyl alcohol and large quantities of water successively. Thirdly, the complete removal of chromium is carried out through putting glass substrate into decarbonisation solution which consists of ammonium ceric nitrate, acetic acid, and ultrapure water.

(7) 2) Superficial organics, solid particulates and dust on soda glass substrate and cover plate are wiped off by sufficient liquid detergent and quantities of ultra-pure water.

(8) 3) After blow-drying most water with a high-pressure air rifle, exterior cleaning, and activation which lasts for 3-10 min are processed in plasma cleaning device which is stimulated by air. A device used in this process is plasma cleaning device in the version of PLASMA CLEANER PDC-002 manufactured by HARRICK PLASMA cooperation.

(9) 4) A rough alignment is finished via adjusting angle and direction while fitting substrate and cover plate which are cleaned and activated by plasma.

(10) 5) Under drying condition, precise alignment is accomplished in the way of moving substrate on fixed cover plate under microscope observation. After alignment, an appropriate amount of ultra-pure water is added based on the size of microchips. When the size of soda glass microchips is 6.2 cm4.2 cm4.6 mm, 2 L ultrapure water is dropped into the limbic crevice. Because of the high hydrophily on the inner surface of substrate and cover plate obtained by plasma treatment, tight fitting of microchips is fulfilled via water drop capillary penetration.

(11) FIG. 1 is a photograph of the microstructure of soda glass substrate microchip before precise alignment in this disclosure. Subtle positional deviation in micro-channel remains after rough alignment. FIG. 2 is a photograph of the microstructure of soda glass substrate microchip after precise alignment in this disclosure. It can be inferred from comparing FIG. 1 and FIG. 2 that rough alignment after plasma cleaning is for the sake of adjustment of channel angle and direction; and then the precise alignment of micro-channel can be realized in the way of moving cover plate on fixed substrate under microscope observation, providing a powerful guarantee for microchips efficient utilization.

(12) 6) Soda glass substrate microchips after fitting are pressured to squeeze out extra water in the tunnel. Observation of interference fringe is needed; if there is one, step 1) to 5) should be repeated; if there is none, high-pressure air rifle is adopted to blow-dry limbic water.

(13) 7) Vacuum drying relying on the vacuum function of plasma cleaning device is performed on soda glass substrate microchips for 5-20 min to totally wipe out water in the channel and finish the pre-bonding process in the end. A device used in this process is plasma cleaning device in the version of PLASMA CLEANER PDC-002 manufactured by HARRICK PLASMA cooperation.

(14) S2 Thermal Bonding of Soda Glass Substrate Microchip:

(15) Permanent bonding of microchips is realized via high-temperature thermal bonding of the pre-bonded soda glass substrate microchips in muffle furnace following the preset heating procedure. That is: room temperature is set as initial temperature; the maximum temperature of 550 C. is reached at a heating rate of 1-3 C./min; the temperature is held at 550 C. for 1-3 h; and the final room temperature is reached at a cooling rate of 0.5-5.5 C./min.

(16) FIG. 3 is an effect picture of a cross section of soda glass substrate microchip after thermal bonding in this disclosure. The central position is edge-closed channels including a microstructure on a substrate and cover plate.

(17) FIG. 3 indicates no boundary between the substrate and cover plates as a result of a completely integrated whole transformed from 2.3 mm thick microchips before thermal bonding.

Example 2

(18) S1 Plasma-Assisted Precise Alignment and Pre-Bonding for Microstructure of Boron Glass Microchip:

(19) 1) After wet etching, 1.1 mm thick optical cement on the surface of boron glass substrate microchip is dissolved with acetone, and then sufficiently washed with isopropyl alcohol and large quantities of water successively. Thirdly, the complete removal of chromium is carried out through putting glass substrate into dechromisation solution which consists of ammonium ceric nitrate, acetic acid, and ultrapure water.

(20) 2) Superficial organics, solid particulates and dust on boron glass substrate and cover plate are wiped off by sufficient liquid detergent and quantities of ultra-pure water.

(21) 3) After blow-drying most water with a high-pressure air rifle, exterior cleaning, and activation which lasts for 3-10 min are processed in plasma cleaning device which is stimulated by air. A device used in this process is plasma cleaning device in the version of PLASMA CLEANER PDC-002 manufactured by HARRICK PLASMA cooperation.

(22) 4) A rough alignment is finished via adjusting angle and direction while fitting substrate and cover plate which are cleaned and activated by plasma.

(23) 5) Under drying condition, precise alignment is accomplished in the way of moving substrate on fixed cover plate under microscope observation. After alignment, an appropriate amount of ultra-pure water is added based on the size of microchips. When the size of boron glass microchips is 6.2 cm4.2 cm4.6 mm, 2 L ultrapure water is dropped into the limbic crevice. Because of the high hydrophily on the inner surface of substrate and cover plate obtained by plasma treatment, tight fitting of microchips is fulfilled via water drop capillary penetration.

(24) 6) Boron glass substrate microchips after fitting are pressured to squeeze out extra water in the tunnel. Observation of interference fringe is needed; if there is one, step 1) to 5) should be repeated; if there is none, a high-pressure air rifle is adopted to blow-dry limbic water.

(25) 7) Vacuum drying relying on the vacuum function of plasma cleaning device is performed on boron glass substrate microchips for 5-20 min to totally wipe out water in the channel and finish the pre-bonding process in the end. A device used in this process is plasma cleaning device in the version of PLASMA CLEANER PDC-002 manufactured by HARRICK PLASMA cooperation.

(26) S2 Thermal Bonding of Boron Glass Substrate Microchip:

(27) Permanent bonding of microchips is realized via high-temperature thermal bonding of the pre-bonded boron glass substrate microchips in muffle furnace following the preset heating procedure. That is: room temperature is set as initial temperature; the maximum temperature of 650 C. is reached at a heating rate of 1-3 C./min; the temperature is held at 650 C. for 1-3 h; and the final room temperature is reached at a cooling rate of 0.5-5.5 C./min.

(28) The same thermal bonding effect as obtained by soda glass substrate microchips in Example 1 can also be achieved through thermal bonding performance on boron glass substrate microchips which are fabricated by the pre-bonding method proposed in this disclosure. The effect picture can be referred to FIG. 3.

Example 3

(29) S1 Plasma-Assisted Precise Alignment and Pre-Bonding for Microstructure of Quartz Microchip:

(30) 1) After wet etching, 1.1 mm thick optical cement on the surface of quartz glass substrate microchip is dissolved with acetone, and then sufficiently washed with isopropyl alcohol and large quantities of water successively. Thirdly, the complete removal of chromium is carried out through putting glass substrate into dechromisation solution which consists of ammonium ceric nitrate, acetic acid, and ultrapure water.

(31) 2) Superficial organics, solid particulates, and dust on substrate and cover plate of quartz are wiped off by sufficient liquid detergent and quantities of ultra-pure water.

(32) 3) After blow-drying most water with a high-pressure air rifle, exterior cleaning, and activation which lasts for 3-10 min are processed in plasma cleaning device which is stimulated by air. A device used in this process is plasma cleaning device in the version of PLASMA CLEANER PDC-002 manufactured by HARRICK PLASMA cooperation.

(33) 4) Rough alignment is finished via adjusting angle and direction while fitting substrate and cover plate which are cleaned and activated by plasma.

(34) 5) Under drying condition, precise alignment is accomplished in the way of moving substrate on fixed cover plate under microscope observation. After alignment, an appropriate amount of ultra-pure water is added based on the size of microchips. When the size of boron glass microchips is 6.2 cm4.2 cm4.6 mm, 2 L ultrapure water is dropped into the limbic crevice. Because of the high hydrophily on the inner surface of substrate and cover plate obtained by plasma treatment, tight fitting of microchips is fulfilled via water drop capillary penetration.

(35) 6) Quartz substrate microchips after fitting are pressured to squeeze out extra water in the tunnel. Observation of interference fringe is needed, for if there is one, step 1) to 5) should be repeated, if there is none, a high-pressure air rifle is adopted to blow-dry limbic water.

(36) 7) Vacuum drying relying on the vacuum function of plasma cleaning device is performed on quartz substrate microchips for 5-20 min to totally wipe out water in the channel and finish the pre-bonding process in the end. A device used in this process is plasma cleaning device in the version of PLASMA CLEANER PDC-002 manufactured by HARRICK PLASMA cooperation.

(37) S2 Thermal Bonding of Quartz Substrate Microchip:

(38) Permanent bonding of microchips is realized via high-temperature thermal bonding of the pre-bonded quartz substrate microchips in muffle furnace following the preset heating procedure. That is: room temperature is set as initial temperature; the maximum temperature of 1100 C. is reached at a heating rate of 1-3 C./min; the temperature is held at 1100 C. for 1-3 h; the final room temperature is reached at a cooling rate of 0.5-5.5 C./min.

(39) The same thermal bonding effect as obtained by soda glass substrate microchips in Example 1 can also be achieved through thermal bonding performance on quartz substrate microchips which are fabricated by the pre-bonding method proposed in this disclosure. The effect picture can be referred to FIG. 3.