NOVELTY - An aqueous alkali solution is supplied on surface of a silicon substrate (1, 5). The surface of silicon substrate is subjected to anisotropic etching by wet etching. The aqueous alkali solution comprises alcoholic additive or surfactant having hydrophilic-lipophilic balance value of 10 or more, and silicate compound. The molar ratio of silica and alkali oxide in the silicate compound is 1.4-2.1. The silicon conversion concentrations of the silicate compound is 0.2-0.6 wt.%.    USE - Etching method of silicon substrate used for manufacture of solar cell (claimed).    ADVANTAGE - The method enables effective etching of silicon substrate providing texture having excellent flatness on the slope and reduced reflectivity. The solar cell manufactured using the etched silicon substrate has excellent photoelectric conversion efficiency.    DETAILED DESCRIPTION - An aqueous alkali solution is supplied on surface of a silicon substrate. The surface of silicon substrate is subjected to anisotropic etching by wet etching. The aqueous alkali solution comprises alcoholic additive of formula: X-(OH)n or surfactant having hydrophilic-lipophilic balance value of 10 or more, and silicate compound of formula: lX'2O.mSiO2.n'H2O. The molar ratio of silica and alkali oxide in the silicate compound is 1.4-2.1. The silicon conversion concentrations of the silicate compound is 0.2-0.6 wt.%.    X=optionally saturated 4-7C hydrocarbyl;    n=1 or more;    X'=alkali metal element;    l=amount of alkali oxide;    m=amount of silica;and    n'= amount of water in silicate compound.    INDEPENDENT CLAIMS are included for the following:    (1) etching liquid (3); and    (2) manufacture of solar cell, which involves forming a conductivity-type semiconductor layer on the electroconductive silicon substrate opposite to silicon substrate by which etching process is carried out.    DESCRIPTION OF DRAWING(S) - The drawing shows schematic view of wet etching treatment process of the silicon substrate for texture formation on the surface of the silicon substrate.    Silicon substrate (1,5)    Etching tank (2)    Etching liquid (3)    Hydrogen gas (4)    Texture (6)