CN105428215A - A method of peeling off the whole surface of epitaxial wafer based on metal stress layer and hydrophilic agent treatment - Google Patents

Abstract

The invention discloses an epitaxial wafer whole-face stripping method based on metal stress layer and hydrophilic agent treatment, which mainly utilizes the high corrosion selectivity characteristic of AlAs in HF acid to introduce a metal stress layer with preset thickness, and an epitaxial structure on an epitaxial wafer is curled upwards under the action of the metal stress layer, so that the epitaxial structure and a substrate of the epitaxial wafer can be separated in time, corrosive liquid can supplement a region to be reacted in time, and a hydrophilic agent is introduced to effectively reduce the surface tension of a contact surface and reduce a contact angle, so that bubbles generated by reaction can be discharged in time, and further the reaction is promoted. The method can obtain the complete stripped substrate and the complete stripped epitaxial structure.

Description

A method of peeling off the whole surface of epitaxial wafer based on metal stress layer and hydrophilic agent treatment

technical field

The invention relates to the technical field of semiconductor optoelectronics, in particular to a method for peeling off the entire surface of an epitaxial wafer based on the treatment of a metal stress layer and a hydrophilic agent.

Background technique

Compound semiconductor devices such as gallium arsenide, indium phosphide, etc., are affected by their raw materials, and their prices and costs have always been higher than those of silicon-based electronic devices. A large proportion of the cost comes from the epitaxial growth. substrate. If the substrate can be recycled, semiconductor lasers, solar cells, heterojunction bipolar transistors, and high electron mobility transistors based on gallium arsenide and indium phosphide materials will play an important role in signal transmission, optical communication, and electronic signal processing. The cost of advanced optoelectronic devices will be greatly reduced, and the thin-film solar cells and thin-film semiconductor lasers after removing the substrate will be significantly better than traditional devices in terms of power-to-weight ratio and heat dissipation characteristics.

In the early days, most of the removal of the substrate was done by mechanical grinding. In recent years, the substrate stripping recovery technology based on the sacrificial layer process has been favored by more researchers. For germanium-based, gallium arsenide-based, and indium phosphide-based devices, a certain thickness of AlAs sacrificial layer is generally used, and its high corrosion selectivity in HF (hydrofluoric) acid is used to achieve the peeling off of the epitaxial layer structure. However, in the process of lateral corrosion, if the reaction products are not discharged in time, and the sacrificial layer cannot be in contact with fresh corrosion solution in time, the further progress of the reaction will be hindered to a large extent, and the reaction will even be stopped.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies and shortcomings of the prior art, and propose a method for peeling off the entire surface of an epitaxial wafer based on a metal stress layer and a hydrophilic agent. This method can obtain a complete peeled off substrate, and a complete peeled off down the epitaxial structure.

In order to achieve the above object, the technical solution provided by the present invention is: a method of peeling off the whole surface of the epitaxial wafer based on the metal stress layer and the treatment of the hydrophilic agent. This method mainly uses the high corrosion selectivity of AlAs in HF acid, and introduce The metal stress layer with a preset thickness, under the action of the metal stress layer, the epitaxial structure on the epitaxial wafer will be curled upward, so that the epitaxial structure and the substrate of the epitaxial wafer can be separated in time, so that the etching solution can replenish the reaction area in time, and at the same time Introducing a hydrophilic agent to effectively reduce the surface tension of the contact surface and reduce the contact angle, so that the bubbles generated by the reaction can be discharged in time to promote the reaction. In addition, the high uniformity and repeatability of the electron beam evaporation equipment characteristics, the metal stress layer can be prepared in large quantities at the same time, and then the substrate is removed in batches, and the substrate can be recycled; it includes the following steps:

1) Perform organic cleaning and surface oxide cleaning on the grown epitaxial wafer to improve the adhesion of the metal stress layer on the surface of the epitaxial wafer, wherein the epitaxial wafer includes a substrate, an AlAs sacrificial layer stacked in sequence from bottom to top , device functional structure layer;

2) Move the cleaned epitaxial wafer to electron beam evaporation equipment, and conduct multiple evaporations by electron beam evaporation, and prepare a metal stress layer on the device functional structure layer of the epitaxial wafer. During the preparation process, control the key process parameters to control the stress of the metal stress layer until the thickness of the metal stress layer reaches the preset requirement;

3) Put the evaporated epitaxial wafer into the plug, and immerse it horizontally in the water bath HF etching solution containing a hydrophilic agent to peel off the epitaxial structure. After soaking for a preset time, the complete epitaxial structure can be obtained, and the substrate recycle and re-use.

In step 1), the thickness of the AlAs sacrificial layer is 5-15nm;

The organic cleaning and surface oxide cleaning include: ultrasonic cleaning with acetone for 5-7 minutes; ultrasonic cleaning with isopropanol for 5-7 minutes; diluted hydrochloric acid solution for 50 seconds to 70 seconds, and the dilution ratio is HCl: _H2O = 1:1; BOE solution 50 seconds to 70 seconds.

In step 2), the metal in the metal stress layer is selected to be gold particles, silver particles or copper particles. During evaporation, the vacuum degree is controlled above 1E-7 Torr, and the evaporation rate is set at 2.5 angstroms per second to 3.5 angstroms per second, the evaporation adopts the intermittent stage heating method, the heating temperature is 145 degrees to 155 degrees, the temperature heating opening time is when the melting material reaches the vacuum degree requirement, and the heating time lasts for 30 minutes; repeated evaporation to the metal stress layer The thickness reaches 25 microns to 27 microns.

In step 3), the hydrophilic agent is acetone, and the temperature of the water bath is controlled at 40-50 degrees. During corrosion, the epitaxial wafer is placed in the plug to keep the side of the metal stress layer on the top, and the proportion of the corrosion solution is Acetone:HF:water=1:1:1.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The invention provides an epitaxial wafer whole surface peeling technology based on metal stress layer and hydrophilic agent treatment, through which the substrate can be completely peeled off and recycled, thereby significantly reducing the manufacturing cost of devices. Experiments have proved that the time for peeling off a 4-inch complete wafer by the method of the present invention can be shortened to 13 hours, and the higher uniformity and repeatability of the electron beam evaporation equipment can be used to prepare the metal stress layer simultaneously in large batches (in practice Among them, the machine we use can perform 52 simultaneous operations at a time), and then remove the substrate. Moreover, optoelectronic devices such as thin-film solar cells and thin-film semiconductor lasers after removing the substrate are obviously superior to traditional devices in terms of power-to-weight ratio and heat dissipation characteristics.

Description of drawings

FIG. 1 is a schematic structural view of the epitaxial wafer described in the embodiment after the upper metal stress layer is prepared.

detailed description

The present invention will be further described below in conjunction with specific examples.

The epitaxial wafer whole-surface peeling method based on the metal stress layer and hydrophilic agent treatment described in this embodiment mainly uses the high corrosion selectivity of AlAs in HF acid to introduce a metal stress layer with an appropriate thickness. Under the action of the epitaxial wafer, the epitaxial structure on the epitaxial wafer will be slightly upward curled, so that the epitaxial structure and the substrate of the epitaxial wafer can be separated in time, so that the etching solution can replenish the area to be reacted in time, and at the same time, a hydrophilic agent is introduced to effectively reduce the friction of the contact surface. The surface tension can reduce the contact angle, so that the bubbles generated by the reaction can be discharged in time, and then the reaction can be promoted. In addition, using the high uniformity and repeatability of the electron beam evaporation equipment, the metal stress layer can be prepared in large quantities at the same time. Substrate removal is then carried out in batches, and the substrate can be recycled; it includes the following steps:

1) Perform organic cleaning and surface oxide cleaning on the grown epitaxial wafer to improve the adhesion of the metal stress layer on the surface of the epitaxial wafer; wherein, the epitaxial wafer includes a substrate, an AlAs sacrificial layer stacked sequentially from bottom to top, Layer, device functional structure layer, as shown in Figure 1; And the organic cleaning and surface oxide cleaning that carry out include acetone ultrasonic cleaning 5-7 minutes successively, preferred time 6 minutes; Isopropanol ultrasonic cleaning 5-7 minutes, preferred time 6 minutes; 50 seconds to 70 seconds for the diluted hydrochloric acid solution, the preferred time is 60 seconds, the dilution ratio is HCl:H2O=1:1; 50 seconds to 70 seconds for the BOE solution, the preferred time is 60 seconds.

2) Move the cleaned epitaxial wafer to the electron beam evaporation equipment, conduct multiple evaporations by electron beam evaporation, and prepare a metal stress layer on the device functional structure layer of the epitaxial wafer. During the preparation process, control key process parameters , to control the stress of the metal stress layer until the thickness of the metal stress layer reaches preset requirements; wherein, the metal in the metal stress layer is selected as gold grains, silver grains or copper grains, preferably gold grains (the gold grains are chemically inert and strong , the subsequent tape-out is not affected); during evaporation, the vacuum degree is controlled above 1E-7Torr, the evaporation rate is set at 2.5 angstroms per second to 3.5 angstroms per second, and the preferred rate is set at 3 angstroms per second; evaporation Adopt intermittent stage heating method, the heating temperature is 145 degrees to 155 degrees, the preferred temperature is 150 degrees; the heating time is 30 minutes when the temperature heating is completed and the vacuum degree is reached; repeat the evaporation to the metal stress layer The thickness reaches 25 microns to 27 microns.

3) Put the vapor-deposited epitaxial wafer (structure shown in Figure 1) into the plug, and immerse horizontally in a water bath HF corrosion solution containing a hydrophilic agent to peel off the epitaxial structure. After soaking for a preset time, the peeling can be obtained The complete epitaxial structure (the epitaxial structure can be bonded to the supporting substrate for the process tape-out of conventional solar cells), and the substrate is recycled at the same time. Wherein, the hydrophilic agent is acetone; the temperature of the water bath is controlled at 40-50 degrees, preferably 45 degrees; the epitaxial wafer is placed in the jam during corrosion to keep the side of the metal stress layer on the top; the proportion of the corrosion solution is acetone :HF:water=1:1:1.

Remarks: Semiconductor strip lasers, vertical cavity surface emitting lasers, heterojunction bipolar transistors, high electron mobility transistors, flip-chip solar cells, flexible solar cells and other optoelectronic devices can be realized by this method.

To sum up, after adopting the above solution, the method of the present invention can accelerate the entire stripping process, and the substrate can be completely stripped for recycling, thereby significantly reducing the manufacturing cost of the device. Experiments have proved that the time for peeling off a 4-inch complete wafer by the method of the present invention can be shortened to 13 hours, and the higher uniformity and repeatability of the electron beam evaporation equipment can be used to prepare the metal stress layer simultaneously in large batches (in practice Among them, the machine we use can perform 52 simultaneous operations at a time), and then remove the substrate. In addition, optoelectronic devices such as thin-film solar cells and thin-film semiconductor lasers after removing the substrate are significantly superior to traditional devices in terms of power-to-weight ratio and heat dissipation characteristics, and are worthy of promotion.

The implementation examples described above are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Therefore, all changes made according to the shape and principles of the present invention should be covered within the protection scope of the present invention.

Claims (4)

1. epitaxial wafer whole stripping means based on metal stresses layer and hydrophilizing agent process, it is characterized in that: the corrosion Selection radio characteristic that the method mainly utilizes AlAs high in HF acid, introduce the metal stresses layer of preset thickness, under the effect of metal stresses layer, epitaxial structure on epitaxial wafer will upsweep, thus epitaxial structure can be separated in time with the substrate of epitaxial wafer, make corrosive liquid can supplement question response district in time, introduce hydrophilizing agent simultaneously, effectively to reduce the surface tension of contact-making surface, reduce contact angle, the steam bubble that reaction is produced can be drained in time, and then advance the carrying out of reaction, in addition, utilize high uniformity and the repeatability of electron beam evaporation equipment, metal stresses layer can be prepared in enormous quantities simultaneously, then batch carries out substrate removal, and substrate recoverable, it comprises the following steps:

1) the complete epitaxial wafer of growth is carried out organic washing and oxide on surface cleaning, to improve the bonding force of metal stresses layer on epitaxial wafer surface, wherein said epitaxial wafer comprises the substrate, AlAs sacrifice layer, the device function structure sheaf that are cascading from bottom to up;

2) the complete epitaxial wafer of cleaning is moved to electron beam evaporation equipment, the mode of electron beam evaporation is adopted to carry out repeatedly evaporation, the device function structure sheaf of epitaxial wafer prepares metal stresses layer, wherein in preparation process, control key process parameter, to control the stress of metal stresses layer, until the thickness of metal stresses layer reaches preset requirement;

3) epitaxial wafer complete for evaporation is put into jam, and carry out epitaxial structure stripping in level is immersed in containing hydrophilizing agent water-bath HF etchant solution, can obtain after soaking Preset Time peeling off complete epitaxial structure, substrate is recycled simultaneously.

2. a kind of epitaxial wafer whole stripping means based on metal stresses layer and hydrophilizing agent process according to claim 1, is characterized in that: in step 1) in, described AlAs sacrificial layer thickness is 5-15nm;

The organic washing of carrying out and oxide on surface cleaning comprise successively: acetone ultrasonic cleaning 5-7 minute; Isopropyl alcohol ultrasonic cleaning 5-7 minute; The hydrochloric acid solution of dilution 50 seconds to 70 seconds, dilution proportioning is HCl:H ₂o=1:1; BOE solution 50 seconds to 70 seconds.

3. a kind of epitaxial wafer whole stripping means based on metal stresses layer and hydrophilizing agent process according to claim 1, it is characterized in that: in step 2) in, metal in described metal stresses layer is chosen as goldc grains, silver granuel or shot copper, during evaporation, vacuum degree control is on 1E-7Torr, it is per second per second to 3.5 dusts that evaporation rate is set in 2.5 dusts, evaporation adopts clearance-type stepwise heating mode, heating-up temperature is 145 degree to 155 degree, the heating temperatures opening time melt is complete reach vacuum level requirements time, heating time continue 30 minutes; Repeat evaporation to metal stresses layer thickness and reach 25 microns to 27 microns.

4. a kind of epitaxial wafer whole stripping means based on metal stresses layer and hydrophilizing agent process according to claim 1, it is characterized in that: in step 3) in, described hydrophilizing agent is acetone, bath temperature controls at 40 degree of-50 degree, during corrosion, the placement of epitaxial wafer in jam keeps metal stresses layer side upper, and the proportioning of etchant solution is acetone: HF: water=1:1:1.