EP0504714A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Semiconductor substrate having a SOI structure and method of producing the same
Assignee: Shin-Etsu Handotai Co Ltd
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Filing: 1992-03-10
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Granted: —
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Expires: 2012-03-10
Abstract
Abstract A semiconductor substrate is formed by bonding wafers together by heat-treatment without causing the substrate to be thermally damaged to have thermal strain, separation, cracks, etc. due to a difference in the thermal expansion coefficients of the wafers. Particularly, a semiconductor substrate having an SOI structure with a silicon film thin enough to allow various integrated circuits or TFL-LCD to be formed, is produced. After wafers are bonded temporarily in a low temperature range, one of the wafers is made thin by chemical treatment, then the wafers are bonded fully by heat-treatment in a temperature range (where the thermal expansion coefficients of the wafer are not affected) higher than the above low temperature range, and then said one wafer can be made thinner by mechanical grinding or polishing mechano-chemically. Even if a semiconductor substrate is formed by sticking a silicon wafer and a quartz wafer together, damages that will be caused thermally due to thermal expansion can be prevented, and a film can be easily obtained which is sufficiently thin as required for forming various integrated circuits or TFT-LCD or the like.
Inventors
- 👤 Takao Abe
- 👤 Yasuaki Nakazato
- 👤 Atsuo Uchiyama
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 20:07
CPC Classifications
H; H10; H10P; H10P90/00; H10P90/19; H10P90/1904; H10P90/1906; H10P90/1914; H10W; H10W10/00; H10W10/10; H10W10/181; G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1345; G02F1/13454; Y; Y10; Y10S; Y10S438/00; Y10S438/977
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
177 words
A semiconductor substrate formed by bonding two wafers different in thermal expansion coefficient, which semiconductor is produced by heat-treating two wafers, which have been at least polished and cleaned, in a first temperature range with the surfaces of the wafers to be bonded being pressed to each other thereby forming a temporarily bonded substrate, subjecting the surface of at least one of the wafers of said temporarily bonded substrate to chemical treatment to make the wafer thin, and heat-treating the substrate in a second temperature range higher than the first temperature range, if necessary, after chemically treating or mechanically treating the surface of said one wafer, which has been made thin, to make said one wafer thinner, heat-treating the substrate in a third temperature range higher than said second temperature range, wherein the step of making said one wafer further thinner and heat-treatments in a further higher temperature range are repeated, thereby ultimately forming a fully bonded substrate having the wafers bonded together, and mechano-chemically polishing the surface of the thinned wafer of the fully bonded substrate.
Claim 2
Dependent Claim
38 words
A semiconductor substrate having an SOI structure as claimed in claim 1, characterized in that the thinning of one of the wafers of the temporarily bonded substrate is carried out by chemical etching with an aqueous alkali solution.
Claim 3
Dependent Claim
169 words
A semiconductor substrate having an SOI structure as claimed in claims 1 and 2, which is obtained by using, as the wafers of different thermal expansion coefficients, a silicon wafer and a quartz wafer, heat-treating the wafers in a first temperature range of about 110 to 350°C with the surfaces of the wafers to be bonded which have at least been polished and cleaned being pressed to each other thereby forming a temporarily bonded substrate, making at least the silicon wafer of said temporarily bonded substrate thin by chemical treatment to assume a thickness of about 100 to 200 µm, heat-treating the temporarily bonded substrate in a second temperature range of about 350 to 500°C to form a fully bonded substrate, subjecting the surface of the thinned silicon wafer of said fully bonded substrate to surface grinding to reduce the thickness to about 20 µm, and polishing the surface of said further thinned silicon wafer to reduce the thickness of said further thinned silicon wafer to about 2 µm.
Claim 4
Independent Claim
224 words
A method of producing a semiconductor substrate having an SOI structure formed by bonding two wafers of different thermal expansion coefficients, comprising: a step of heat-treating two wafers, which have been at least polished and cleaned, in a first temperature range with the surfaces of the wafers to be bonded being pressed to each other, thereby forming a temporarily bonded substrate, a step of subjecting the surface of at least one of the wafers of said temporarily bonded substrate to chemical treatment to make the wafer thin, a step of heat-treating the substrate in a second temperature range higher than the first temperature range, thereby allowing the temporarily bonded substrate to remain as it is or to be made into a fully bonded substrate, if necessary, after a step of chemically treating or mechanically treating the surface of said one wafer, which has been made thin, to make said one wafer thinner, a step of heat-treating the substrate in a third temperature range higher than said second temperature range, wherein the step of making said one wafer further thinner and heat-treatments in a further higher temperature range are repeated, thereby ultimately forming a fully bonded substrate having the wafers bonded together, and a step of mechano-chemically polishing the surface of the thinned wafer of said fully bonded substrate to make said particular wafer thinner.
Claim 5
Dependent Claim
42 words
A method of producing a semiconductor substrate having an SOI structure as claimed in claim 4, characterized in that the thinning of one of the wafers of the temporarily bonded substrate is carried out by chemical etching with an aqueous alkali solution.
Claim 6
Independent Claim
180 words
A method of producing a semiconductor substrate having an SOI structure as claimed in claims 4 and 5, wherein a silicon wafer and a quartz wafer are used as the wafers of different thermal expansion coefficients, comprising: a step of heat-treating the wafers in a first temperature range having a temperature of about 110 to 350°C with the surfaces of the wafers to be bonded which have at least been polished and cleaned being pressed to each other, thereby forming a temporarily bonded substrate, a step of making at least the silicon wafer surface of said temporarily bonded substrate thin by chemical treatment to reduce its thickness to about 100 to 200 µm, and heat-treating the temporarily bonded substrate in a second temperature range having a temperature of about 350 to 500°C to form a fully bonded substrate, and a step of subjecting the thinned silicon wafer of said fully bonded substrate to surface grinding to reduce the thickness to about 20 µm, and mechano-chemically polishing said further thinned silicon wafer surface to reduce its thickness to about 2 µm.
References Cited (Backward Citations)
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