阅读说明：本技术 一种减少注入损伤制备soi的方法 (method for preparing SOI by reducing implantation damage ) 是由 彦丙智 佟姝雅 于 2019-10-28 设计创作，主要内容包括：本发明提供一种减少注入损伤制备SOI的方法,所述方法包括：选取三片原始硅片,分别为第一硅片、第二硅片和第三硅片；对第一硅片进行机械减薄,对第二硅片和第三硅片进行氧化；将氧化后的第二硅片和减薄后的第一硅片进行一次键合,得到一次键合片；对一次键合片进行离子注入；对离子注入后的一次键合片进行剥离；将剥离后的一次键合片与氧化后的第三硅片进行二次键合,得到二次键合片；对二次键合片进行裂片,以得到绝缘层上硅结构；对绝缘层上硅结构进行退火和化学机械抛光处理,得到高质量的SOI。本发明的减少注入损伤制备SOI的方法,可以去除注入损伤及离子残留,有效减少SOI的缺陷,显著提高硅片表面状态。(The invention provides methods for preparing an SOI (silicon on insulator) by reducing implantation damage, which comprise the steps of selecting three original silicon wafers, namely a th silicon wafer, a second silicon wafer and a third silicon wafer, mechanically thinning the th silicon wafer, oxidizing the second silicon wafer and the third silicon wafer, bonding the oxidized second silicon wafer and the thinned th silicon wafer times to obtain a -time bonded wafer, implanting ions into the -time bonded wafer, stripping the -time bonded wafer after ion implantation, secondarily bonding the stripped -time bonded wafer and the oxidized third silicon wafer to obtain a secondary bonded wafer, splitting the secondary bonded wafer to obtain a silicon structure on an insulating layer, and annealing and chemically and mechanically polishing the silicon structure on the insulating layer to obtain a high-quality SOI.)

1, methods for reducing implantation damage to produce SOI, comprising:

selecting three original silicon chips which are respectively an th silicon chip, a second silicon chip and a third silicon chip;

mechanically thinning the th silicon wafer, and oxidizing the second silicon wafer and the third silicon wafer;

bonding the oxidized second silicon wafer and the thinned th silicon wafer times to obtain times of bonding sheets;

performing ion implantation on the bonding sheets;

stripping the bonding sheets after ion implantation;

bonding the peeled -time bonding sheet and the oxidized third silicon wafer for the second time to obtain a secondary bonding sheet;

splitting the secondary bonding sheet to obtain a silicon-on-insulator structure;

and annealing and chemically and mechanically polishing the silicon structure on the insulating layer to obtain the high-quality SOI.

2. The method of claim 1, wherein the th silicon wafer after mechanical thinning has a thickness of less than or equal to 1um, and wherein the oxide layer thickness of the second silicon wafer and the oxide layer thickness of the third silicon wafer are both greater than or equal to 200A.

3. The method of claim 1, wherein the bonds are under vacuum conditions with a vacuum of less than 1Torr and a plasma activation time of 5s to 20 s.

4. The method of claim 1, wherein the implantation source of the ion implantation is hydrogen or hydrogen helium, and the uniformity of the implanted ion distribution is greater than or equal to 95%.

5. The method of claim 1, wherein the stripping is etching with hydrofluoric acid and tetramethylammonium hydroxide, wherein the hydrofluoric acid has a concentration of 1:10 and an etching rate of 4A/s; the concentration of the methyl ammonium hydroxide is 1:1, and the corrosion rate is 100A/s.

6. The method of claim 1, wherein the secondary bonding is performed under vacuum conditions having a vacuum of less than 1Torr and a plasma activation time of 5s to 20 s.

7. The method of claim 1, wherein the annealing conditions are: the annealing temperature is 950-1100 ℃, and the annealing time is 100-120 min.

8. The method of claim 1, wherein the chemical mechanical polishing process has a removal rate of: 1A/s-14A/s.

9. The method of any of claims 1-8, wherein the high quality SOI has a grain @0.8 < 20, a flatness TTV ≦ 6um, a thickness uniformity ± 5um, and a roughness Rms ≦ 0.1 nm.

Technical Field

The present invention relates generally to the field of silicon wafer technology, and more particularly to methods for fabricating SOI with reduced implantation damage.

Background

Silicon-On-Insulator (SOI) is new Silicon-based semiconductor materials with a unique "Si/Insulator/Si" tri-layer structure formed by a buried insulating layer (usually SiO, Silicon dioxide)₂) And the all-dielectric isolation of the device and the substrate is realized.

In the conventional method, an original silicon wafer is oxidized and implanted, then bonded to another original silicon wafer or an oxidized silicon wafer, and the silicon wafer is separated from the implanted layer by the thermal microwave technique to obtain a silicon-on-insulator structure, and as an example, an oxide film is formed on at least silicon wafers out of two silicon wafers, and hydrogen ions or rare gas ions are implanted into another silicon wafer to form a microbubble layer (i.e., an ion implanted layer) inside the another silicon wafer, and the silicon wafers are bonded to each other with the oxide film interposed therebetween, and then annealed to secure the bonded surface, and then the wafer of another silicon wafer is peeled in a thin film form by microwave heat treatment using the microbubble layer as a cleavage surface to form an SOI.

However, in practical production, ion implantation causes ion damage and ion residue on the surface of the silicon wafer, so that the grain and roughness of the surface of the prepared SOI are poor, and the yield of the SOI cannot be guaranteed.

Disclosure of Invention

The invention aims to provide methods for preparing SOI by reducing implantation damage, which can remove implantation damage and ion residues, effectively reduce SOI defects and obviously improve the surface state of a silicon wafer.

The invention provides methods for preparing an SOI (silicon on insulator) by reducing injection damage, which comprise the steps of selecting three original silicon wafers, namely a th silicon wafer, a second silicon wafer and a third silicon wafer, mechanically thinning the th silicon wafer, oxidizing the second silicon wafer and the third silicon wafer, bonding the oxidized second silicon wafer and the thinned th silicon wafer times to obtain a -time bonded wafer, implanting ions into the -time bonded wafer, stripping the -time bonded wafer after ion implantation, secondarily bonding the stripped -time bonded wafer and the oxidized third silicon wafer to obtain a secondary bonded wafer, splitting the secondary bonded wafer to obtain a silicon structure on an insulating layer, and annealing and chemically and mechanically polishing the silicon structure on the insulating layer to obtain the high-quality SOI.

Optionally, the thickness of the th silicon wafer after mechanical thinning is less than or equal to 1um, and the thickness of the oxide layer of the second silicon wafer and the thickness of the oxide layer of the third silicon wafer are both greater than or equal to 200A.

Optionally, the times of bonding are performed under the vacuum condition that the vacuum degree is less than 1Torr, and the plasma activation time is 5-20 s.

Optionally, the implantation source of the ion implantation is hydrogen or hydrogen helium, and the uniformity of the distribution of implanted ions is greater than or equal to 95%.

Optionally, the stripping is performed by etching with hydrofluoric acid and tetramethylammonium hydroxide, wherein the concentration of the hydrofluoric acid is 1:10, and the etching rate is 4A/s; the concentration of the methyl ammonium hydroxide is 1:1, and the corrosion rate is 100A/s.

Optionally, the secondary bonding is performed under a vacuum condition with the vacuum degree of less than 1Torr, and the plasma activation time is 5s-20 s.

Optionally, the annealing conditions are: the annealing temperature is 950-1100 ℃, and the annealing time is 100-120 min.

Optionally, the removal rate of the chemical mechanical polishing treatment is: 1A/s-14A/s.

Optionally, the high quality SOI has a grain @0.8 < 20, a flatness TTV of 6um or less, a thickness uniformity of 5um or less, and a roughness Rms of 0.1nm or less.

According to the method for preparing the SOI by reducing the implantation damage, high-energy ion implantation is carried out after Si-O bonding, so that implanted ion residues and implantation damage are effectively prevented; the defects of the implanted silicon wafer are effectively reduced or prevented by stripping the film layer with the ion residues and damage defects (namely removing the ion residues and the implantation damage of the non-implanted layer in the implantation path); then, after Si-O bonding is carried out again, thermal microwave fragmentation is carried out to form SOI, and then annealing and chemical mechanical polishing treatment are carried out to obtain SOI with good surface and internal states after implantation, and the SOI has expectable huge economic value and social value.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a flow chart of a method for fabricating SOI with reduced implantation damage according to an embodiment of the present invention;

fig. 2 is a schematic diagram of the reduction of implantation damage for SOI fabrication according to an embodiment of the present invention.

Detailed Description

Various exemplary embodiments will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments are shown.

A method for fabricating an SOI with reduced implantation damage according to an embodiment of the present invention is described below with reference to fig. 1 and 2.

Fig. 1 is a flowchart of a method for fabricating an SOI with reduced implantation damage according to an embodiment of the present invention, and fig. 2 is a schematic diagram of a method for fabricating an SOI with reduced implantation damage according to an embodiment of the present invention.

Referring to fig. 1 and 2, three original silicon wafers, i.e., a th silicon wafer 100, a second silicon wafer 200, and a third silicon wafer 300, are selected in step S10.

For example, the th, second, and third silicon wafers 100, 200, and 300 may be all high resistance silicon wafers, the th, second, and third silicon wafers 100, 200, and 300 may be all low resistance silicon wafers, the th, second, and third silicon wafers 200, 300 may all be thick film silicon wafers, the th, second, and third silicon wafers 100, 200, and 300 may all be thick film silicon wafers, or the th and second silicon wafers 100 and 200 may all be high resistance silicon wafers, third silicon wafers 300, and the like.

In step S20, the th silicon wafer 100 is mechanically thinned, and the second silicon wafer 200 and the third silicon wafer 300 are oxidized.

By way of example, the thickness of the th silicon wafer 100 after being mechanically thinned (i.e., the thickness of the th silicon wafer 100 remaining after being mechanically thinned) is less than or equal to 1um, the thickness of the oxide layer of the second silicon wafer 200 is greater than or equal to 200A, and the thickness of the oxide layer of the third silicon wafer 300 is greater than or equal to 200A.

Preferably, mechanical thinning may be performed using a DGP8761 apparatus, but the invention is not limited thereto.

Preferably, the second silicon wafer 200 and the third silicon wafer 300 may be oxidized by dry oxygen and wet oxygen mixed oxidation. It is to be understood that the second silicon wafer 200 and the third silicon wafer 300 may be oxidized at the same time, or the second silicon wafer 200 and the third silicon wafer 300 may be oxidized separately, which is not limited in the present invention.

It is to be understood that the oxidized second silicon wafer includes the th oxide layer 202 (i.e., the oxide layer formed on the upper surface of the second silicon wafer 200), the second silicon layer 204, and the second oxide layer 206 (i.e., the oxide layer formed on the lower surface of the second silicon wafer 200). As an example, the th oxide layer 202 has a thickness of 200A or more, and the second oxide layer 206 has a thickness of 200A or more.

The oxidized third silicon wafer includes a third oxide layer 302 (i.e., an oxide layer formed on the upper surface of the third silicon wafer 300), a third silicon layer 304, and a fourth oxide layer 306 (i.e., an oxide layer formed on the lower surface of the third silicon wafer 300). As an example, the thickness of the third oxide layer 302 is greater than or equal to 200A, and the thickness of the fourth oxide layer 306 is greater than or equal to 200A.

In step S30, the oxidized second silicon wafer and the thinned th silicon wafer were subjected to times of bonding, resulting in times of bonded wafer 400.

That is, the oxidized second silicon wafer and the thinned th silicon wafer were Si-O bonded.

In this case, the bonding sheets 400 sequentially include, from top to bottom, a th silicon layer 102 formed by a thinned th silicon wafer, the th oxide layer 202, the second silicon layer 204, and the second oxide layer 206.

Preferably, the times of bonding is carried out under the vacuum condition that the vacuum degree is less than 1Torr, and the plasma activation time is 5s-20s, that is, under the vacuum condition that the vacuum degree is less than 1Torr, the plasma activation technology is adopted to carry out 5s-20s of treatment on the surface so as to enhance the pre-bonding force during bonding, and the pre-bonding is carried out, so that the thinned th silicon wafer and the oxidized second silicon wafer are bonded from .

As an example, the plasma activation time of the bonds may be 8s, 12s, or 16s, but the invention is not limited thereto.

In step S40, ion implantation is performed on the bonding pads.

The implanted ions are sequentially (i.e., implantation path) implanted into the second silicon layer 204 through the th silicon layer 102 and the th oxide layer 202 of the th silicon layer 204 to form an ion-implanted layer 205 in the second silicon layer 204. in this case, defects generated during high-energy ion implantation may remain in the th silicon layer 102 and the th oxide layer 202. that is, implanted ion residues and implantation damage are prevented in the th silicon layer 102 and the th oxide layer 202.

Preferably, the uniformity of the distribution of implanted ions is greater than or equal to 95%.

The implantation source of the ion implantation may be hydrogen or hydrogen helium, as an example, that is, the bonding sheets may be subjected to hydrogen or hydrogen helium ion implantation.

In step S50, the times bonding sheets after ion implantation were peeled off.

The times of bonding sheets after being stripped are the second silicon layer 204 with the ion implantation layer 205, that is, the th silicon layer 102, the th oxide layer 202 and the second oxide layer 206 in the times of bonding sheets after being ion implanted are stripped to achieve the purpose of removing implantation damage and ion residues, thereby effectively reducing the defects of the silicon wafer after being implanted and obtaining the silicon wafer with good surface state after being implanted.

For example, the stripping can be performed by etching with hydrofluoric acid and tetramethylammonium hydroxide (TMAH), specifically, the th silicon layer 102 can be etched with tetramethylammonium hydroxide, and after the stripping of the th silicon layer 102 is completed, the th oxide layer 202 and the second oxide layer 206 can be etched with hydrofluoric acid.

For example, the concentration of the hydrofluoric acid is 1:10, and the etching rate is 4A/s; the concentration of the tetramethylammonium hydroxide is 1:1, and the corrosion rate is 100A/s. It is understood that the etching time may be determined according to the thickness of the film to be etched and the etching rate.

In step S60, the times peeled bonded piece and the oxidized third silicon wafer are secondarily bonded to obtain a secondary bonded piece.

Preferably, the ion-implanted layer side of the times bonded wafer after the lift-off was Si — O bonded to the oxidized third silicon wafer.

Preferably, the oxidized third silicon wafer is a substrate. In this case, the secondary bonding sheet 500 includes, from top to bottom: a second silicon layer 204 with an ion implanted layer 205, said third oxide layer 302, said third silicon layer 304 and said fourth oxide layer 306.

Preferably, the secondary bonding is carried out under the vacuum condition that the vacuum degree is less than 1Torr, and the plasma activation time is 5s-20s, namely, under the vacuum condition that the vacuum degree is less than 1Torr, the surface is treated for 5s-20s by adopting the plasma activation technology to enhance the pre-bonding force during bonding, the pre-bonding is carried out, and the times of bonding sheets after being stripped and the third silicon wafer after being oxidized are bonded from .

As an example, the plasma activation time of the secondary bonding may be 8s, 12s, or 16s, but the present invention is not limited thereto.

In step S70, the secondary bond pad is cleaved to obtain a silicon-on-insulator structure 600 (i.e., SOI).

Preferably, the secondary bonded sheet can be split by a thermal microwave splitting method, so that the top silicon of the secondary bonded sheet is stripped. Specifically, the top silicon of the secondary bonding pad is a silicon layer 207 of the second silicon layer 204 except for the ion implantation layer 205.

In step S80, the SOI of the SOI structure 600 on insulator is annealed and Chemically Mechanically Polished (CMP) to obtain a high quality SOI 700.

By way of example, the high quality SOI700 has less than 20 particles of 0.8 particle size (i.e., particles @0.8 < 20), a Total Thickness Variation (TTV) in flatness of less than or equal to 6um, a Thickness uniformity of ± 5um, and a Root mean square roughness (Rms) in roughness of less than or equal to 0.1 nm.

Preferably, the annealing conditions are: the annealing temperature is 950-1100 ℃, and the annealing time is 100-120 min.

Preferably, the removal rate of the chemical mechanical polishing treatment is: 1A/s-14A/s.

In addition, according to the method for preparing the SOI with reduced implantation damage, high-energy ion implantation is performed after Si-O bonding, so that implanted ion residues and implantation damage are effectively prevented; the defects of the silicon wafer after implantation are effectively reduced and/or prevented by stripping the film layer with the ion residues and damage defects (namely removing the ion residues and implantation damage of the non-implantation layer in the implantation path); then, after Si-O bonding is carried out again, thermal microwave fragmentation is carried out to form SOI, and then annealing and chemical mechanical polishing treatment are carried out to obtain SOI with good surface and internal states after implantation, and the SOI has expectable huge economic value and social value.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.