JPS59187457A - Method of polishing semiconductor base board - Google Patents

Abstract

PURPOSE:To polish the whole surface area of a base board to the same depth along the surface and at a high speed by adding abrasive grains smaller than a particular grain size into a polish liquid which is poured onto a rotating polish pad and uniformly separating by friction the separated-out Cu by means of said abrasive grain. CONSTITUTION:As for the types of abrasive grains, silicon carbide, alumina, silicon dioxide, etc. are used, and the grain size of less than 20mumphi or so, which inflicts less damage to the polishing surface while whose frictional effect is large, is desirable. The polishing is carried out, with the treated Si base board surface brought in contact with the face of a polish pad 6 which is being rotated at the number of revolution of 50 to 100r.p.m. and onto which a Cu plating polish liquid is poured at a rate of 2l/min. Thus, the Cu which is separated out on the polishing surface of the treated Si base board is separated from the Si surface by means of the friction with the abrasive grains contained in the polish liquid which is deposited on and rotated with the polish pad, thereby carrying out polishing at a high speed and to a uniform depth along the surface, without inflicting damage.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method of polishing a semiconductor substrate, and particularly to a method of polishing a semiconductor substrate that is curved due to warpage or the like at high speed along its curved surface.

(b) Conventional technology and problems When polishing a semiconductor substrate with a large amount of warpage, such as a silicon (St) substrate, to a uniform depth along its surface, copper plating polishing technology is used. Cu) plating polishing technology is copper nitrate CLI(NO3)2 and ammonium fluoride NH,F.
A polishing liquid (slurry) whose main component is acidic ammonium fluoride (NH4F-HF is often used) is poured onto the Si substrate surface, replacing Si as shown in the reaction formula below and copper plating the substrate surface. This is a known technique in which a layer is deposited, the Cu plating layer is scraped off, and this reaction is repeated to perform Sf polishing.

S i +2 Cu (NOs) 2 +4 NH4F
→(NH4)2 S i F6+4 NH4N0 a
A normal single-sided polishing device is used for the Cu plating and polishing, and the Si substrate surface is polished at O~80 [: f /crl
] Chemical polishing is performed by the reaction while contacting with a pressure of about 100%.

However, for example, a substrate with a diameter of 100 [mmφ]
When polishing a Si substrate that has a large reaction of about ~200 [μm], the Cu plating polishing technique described above has the property of polishing uniformly along the substrate surface.
S
A problem has arisen in that one surface is not polished uniformly along its warp.

That is, the material of the polishing pad is usually a synthetic leather-like plastic abrasive pad of about 2 to 3 [m], called Voritex, etc., or a brush in which 2 to 3 (+n+++3) short nylon fibers are planted. For example, synthetic leather-like polishing, when cloth is used, the center of the board is rubbed strongly with the polishing cloth, so the center of the board is polished the most, and brush-like polishing When cloth is used, the short nylon fibers in contact with the substrate surface fall down due to pressure contact of the substrate, resulting in insufficient supply of slurry to the center of the substrate surface, so the amount of polishing at the center of the substrate surface is less than that at the periphery. This causes the problem that the amount of energy decreases.

This state is shown in Figure 1, in which (a) shows a silicon substrate S having a warp of about 150 μm on a synthetic leather-like polishing pad PR as shown by the arrow. This figure shows the in-plane distribution of the polishing amount when polishing is performed using a conventional polishing liquid while pressing on the brush-like polishing pad PB. Similarly, it shows the in-plane distribution of the polishing amount when the Si substrate S was polished using a conventional chiller. The conventional Cu plating polish solution (slurry) used here was Cu(N-03)2:500(?]lN
H4F HF: 2500(r)+H20:10[
With the mixed solution of A'), polishing amount 2C1/=]
, polishing pad rotation speed 80 [r.

p9m]+substrate pressure contact load 10C9/ctl'J.

(C) Purpose of the Invention The purpose of the present invention is to provide a copper plating-polinoche method that eliminates the above-mentioned problems and can uniformly polish a semiconductor substrate surface along its surface shape. .

(d) Structure of the Invention That is, the present invention is a semiconductor substrate polishing method in which a copper plating polishing solution containing abrasive grains and containing copper nitrate and ammonium fluoride as main components is poured onto a rotating polishing pad. At the same time, the semiconductor substrate surface is chemically polished by bringing the polish pad surface into contact with the semiconductor substrate surface.

(e+ Embodiments of the Invention Below, seven embodiments of the present invention will be explained in detail with reference to figures.) Figure 2 is a schematic cross-sectional view of a single-sided polishing device, and Figure 3 is a method for polishing a silicon substrate by the method of the present invention. FIG. 4 is an in-plane distribution diagram of the amount of polishing when performing this process.

In the method of polishing a semiconductor substrate of the present invention, a chemical polishing solution of about 50 to 200 [2] is used as a copper (Cu) plating polishing solution to the conventional Cu plating polishing solution 10 [[]. Silicon carbide (S
in), alumina (AA!203) and silicon dioxide (
SiO2) etc. are used, and the particle size is 20 [μm], which has the best friction effect and causes less damage to the polished surface.
φ] or less is desirable. In this example, Cu(NQ, ) is used as an example of the composition.

: 500Cry, NH41-HF: 2500Cry:
L H2O: Approximately 100 (r') in a mixed solution of 1 (7)
5iC (particle size: 0.06 to 16 [μmφ]) using a Cu plating polishing solution containing one scoop of abrasive grains. In the same figure, 1 is a flat rotary table, 2 is a polishing pad, 3 is a substrate holding plate to be processed, 4 is a support shaft and a polishing liquid injection pipe, 5 is the susceptor, 6 is the Si substrate to be processed, 7 is the Borisshi liquid injection arrow, and 8 is the arrow indicating the rotation of the polishing pad.0 And during polishing, 50 to 1001: r, p, m'l
The Cu-plated solution of the present invention was applied to the polysomatic φ pad 2 which was rotated at a rotational speed of about 2CIl/-i-.
When the polishing liquid of the present invention is used, polishing is carried out by bringing the surface of the Sl substrate to be processed onto the borisosy pad while adding the polishing liquid in an amount of about Since the Cu is peeled off from the Si surface by the friction caused by the abrasive grains contained in the rotating polishing material deposited on the polynosy pad, the pressure of the polished Si surface contacting the polynosy pad is 0 to io. [f/ci
] is sufficient. As the material for the polynosie pad, it is more desirable to use the brush-like abrasive cloth described above, which is soft in its application to the surface to be polished and can contain a large amount of borisshy liquid. In this case, the polishing solution is sufficiently supplied over the entire area of the surface to be polished, and the precipitated Cu is uniformly frictionally peeled off by the abrasive grains, so that there is no variation over the entire area of the surface to be polished, as shown in Figure 3. A substantially uniform polishing amount distribution of 101 μm or less can be obtained. The Si substrate to be processed used in this example had a convex surface of 100 to 200 mm on the side to be polished.
(μm) of 100 [mmφ] single crystal Si
The polishing speed obtained in this example was 15 μm for the substrate.
/ familiarity] level.

Note that the composition of the chemical reaction components in the Cu plating/volinosity solution of the present invention is not limited to the composition of the above embodiments, and the abrasive grains mixed in are limited to SiC. ) As described in detail, according to the present invention, the entire surface of a silicon substrate, which is formed into a nine-curved shape by warping or the like, can be coated at a uniform depth along the surface at high speed and without damage. Therefore, by applying the method of the present invention to the manufacturing process, it is possible to improve the manufacturing yield of semiconductor ICs and the like.

[Brief explanation of drawings]

Figures 1 (a) and (b) are in-plane distribution diagrams of the polishing amount in the conventional copper plating polysing method, and Figure 2 is a schematic cross-sectional view of a single-sided polishing device used in an embodiment of the present invention. FIG. 3 is an in-plane distribution diagram of the amount of polishing in an embodiment of the present invention. In the figure, 1 is a flat rotary table 2, 2 is a volunty band, 3 is a substrate holding plate, 4 is a spindle cover polynosy liquid injection tube, 5 is a susceptor, 6 is a silicon substrate to be processed,
7 is a policy liquid injection arrow, 8 is an arrow indicating the rotation of the policy pad, S is a silicon substrate, PR is a synthetic leather-like policy pad, PB is a brush-like policy pad.
Showing pads. ← 1 Factor (4) 14a-3rd θ-Ari θ/θ2ρJO# [nmer]
- 1 year old anti-call...,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, anti-call, - (so u3'''', z3θ] - the distance between the board and A11, et al. is the best? flash l/ (heart 5 closed = group o's anti-17) Wa・ra・1 Komaidei −−→322
−

Claims (1)

[Claims] While pouring a copper plating polishing solution containing abrasive grains and mainly consisting of copper nitrate and ammonium chloride onto a rotating polishing pad, the surface of the polishing pad is brought into contact with the semiconductor substrate surface. A method for polishing a semiconductor substrate, the method comprising chemically polishing the surface of the semiconductor substrate.