JPS5986227A - Forming method for glass film - Google Patents

Abstract

PURPOSE:To form a film which has high reliability without low polarization, low fluidity nor ultrafine crack by sputterng and depositing cation in glass on a wafer in a sputtering unit of specific conditions and thermally fluidizing it at a temperature of fluidizing point or higher. CONSTITUTION:The pressure (1-50mTorr) and the voltage (500V-2.0kV) of sputtering are specified, ions which have 0.5 or less of polarizability of cation in glass under these conditions are sputtered over a wafer to fluidize and solidify it at a high temperature of glass fluidizing point or higher, thereby forming a protective film of a semiconductor. For example, the wafers 1 are horizontally aligned on an anode 4, and a target glass 2 is mounted on a cathode plate 3. Then, a target glass which has mole composition of 0.4 B2O3, 0.2 SiO2, 0.3 GeO3, and 0.1 MgO is employed, sputtered with Ar gas of 30mTorr, and 1kV and fluidized at 800 deg.C, thereby forming a film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] This invention relates to a method for forming a glass film that is reflowed at low temperatures and forms a highly reliable LSI protective film using a low polarizability glass film.

[Prior art and its problems]

In the past, phosphoric acid silica glass has been used as a protective film for LSIs. This has a relatively low polarizability and a highly reliable membrane, but the pour point is as high as 1000°C and it does not fluidize at low temperatures.

Further, this film flows at a high temperature of 1000° C. or higher, and because of the brittleness of the film itself, it is easily susceptible to microcracks. Furthermore, when used in LSI, flattening is impossible at low temperatures. On the contrary, p
BO glasses have been used for passivation, but although they fluidize and flatten at low temperatures, they have a high polarizability and have a negative effect on the C-■ characteristics of devices.

[Purpose of the invention]

The present invention was made to improve these drawbacks, and its purpose is to reduce the sputtering pressure (1
~50mTorr) and voltage (500W~2, OKW)
Under these conditions, ions with a polarizability of cations in the glass of 0.5 or less are scattered onto the wafer, and are fluidized and assimilated at a high temperature above the glass pour point to form a protective film for the semiconductor. It is something. In this case, it is possible to form a highly reliable coating with particularly low polarization and fluidity (pour point: 800° C.) and no minute cracks.

[Summary of the invention]

The outline of this film forming method is as follows: First, glass is set as a target in a sputtering device, and Ar, N@
, etc., and the pressure is set at 1 to 50 mTo in order for the low polarizable ions in the glass to fly efficiently.
rr, voltage 500 W ~2. Set within the OKW range. This is because if the pressure is less than 1 mTorr, low polarizability ions may be scattered, and if the pressure is more than 50 mTofr, ions may be scattered, but the film becomes inhomogeneous and does not function as a protective film. Also, if the voltage is less than 500W, low polarizability ions may be scattered.2. This is because if it exceeds OKW, the target glass will be damaged.

Further, it is desirable that the ions used to form the film have a molar polarizability of 0.5 or less. A film may be formed by scattering one or more ions simultaneously or separately. When a large number of ions with a molar polarizability of 0.5 or more are used,
This is because the load increases on the surface of the semiconductor, which adversely affects the C-VIPf properties. A large number of ions in the target glass are ejected onto the semiconductor wafer like a needle, heated above the glass pour point, and fluidized and solidified to form a film.

〔Effect of the invention〕

By the above-mentioned treatment and means, it has become possible to form a glass film as a protective film for a semiconductor with a pour point of about 800°C. In addition, since the molar polarizability of cations in the glass is 0.5 or less, they are scattered and deposited under the above conditions, so the negative polarization voltage of the glass does not increase, so the desired C of the device can be achieved.
-■Characteristics can be obtained. In addition, it has good fluidity, allows multilayer wiring to be made flat, and has no cracks as a protective film, so a highly reliable passivation board can be obtained.

[Embodiments of the invention]

Next, specific examples will be described in detail with reference to the drawings. The figure shows the melting when a glass protective film is sputtered onto Ueno using a target glass. The wafers 1 are arranged horizontally, and the target glass 2 is attached to the cathode plate 3. 4 is an anode.

Step 5: Use this when starting sputtering with the shutter. 6 is grounded with a shield. 7 is a reaction chamber. 8 is a tube leading to a vacuum gauge, 9 is an exhaust system, and 10 is an inert gas inlet. Next, an example in which sputtering was performed using low polarizability glass will be described.〇 (Example 1) 0.4 B, O,,0,28i0. ．． 0.3GeO,
A target glass having a molar composition of ,0,1MIO was prepared. In terms of molar polarizability, K B l◆== 0.00
76, Ks i”=0.084, Koe”=
0.36, and KMt""=0.238, both of which have molar polarizabilities of 0.5 or less. The total molar polarizability of glass is 0
．． It is 152. Sputtering was performed using Ar glass at 0 mTorr l KW and fluidized at 800°C. There were no cracks in the coating.

(Example 2) Q, 6B, o, 0.38i0. ．． A target glass tube with a molar composition of 0.1 TiO was prepared. KB now = 0.
0076, Ks i'= 0.084, KT i
” = 0.47, and the molar polarizability of both ions is 0.
5 or less. The total mole fraction of glass is 0.0865. Sputtering was performed using Ar gas of 2 QmTorr and 1.5 KW, and fluidization was achieved by heat treatment at 850°C. There were no two coats of glue.

(Example 3) o, 6B, Os 0.35GeO, 0,05As, O,
glass was produced. KB” = 0.0076, Ko
e"=0.36, KAs"=0.26, and the total molar polarizability of this glass cation was 0.143. A
Sputtering was performed at r 30 mTorr, I KW, and fluidized at 800°C. There were no cracks in the film.

As mentioned in the examples above, the molar polarizability of the glass in this bass basin is extremely small and it fluidizes at low temperatures.
Excellent protection without adversely affecting the C-■ characteristics of the device! O that can be used as a film It goes without saying that this glass film can be used not only for semiconductors, but also for other ceramic seals and glasses for metal coverings.

DESCRIPTION OF SYMBOLS 1... Wafer, 2... Target, 3... Cathode plate, 4... Anode, 5... Shutter, 6... Shield, 7... Chamber, 8... Vacuum gauge, 9...
Exhaust system, 10...Inert gas inlet.

Claims (1)

[Claims] Inert gas pressure is 1 to 50 mTorr, voltage 500
W~2. In OKW's sputtering equipment, ions with a molar polarizability of cations in the glass of 0.5 or less are scattered and deposited on the wafer, heated and fluidized at a temperature above the pour point, and the glass is deposited on the substrate. A method for forming a glass film, the method comprising forming a film.